# Sticky  Soundproofing master thread



## granroth

Do you have a question about soundproofing your theater? Then this is the thread for you. It is a sister thread to the Acoustical Treatments Master Thread, but for soundproofing questions instead of acoustic questions.

*Basic Q & A*

*Q. What is Soundproofing?*

The goal of soundproofing is the reduction of sound leakage into or out of a room.

*Q. Do I need soundproofing? I don't have close neighbors and everybody in my home watches movies at the same time!*

Soundproofing refers to sound leakage both going out of the room (sound generated by your theater) _and_ the sound entering the room. Arguably, controlling the sound entering a room might be more important than controlling it from leaving.

*Q. Why? Who cares what happens outside the theater?*

Sound leaking into the conditioned space of your theater adds to the noise floor in the room. This requires that in order to hear the quietest parts of a movie, you'd need to turn up the volume quite a bit just to hear over the noise from outside the room. How much? This quote by Dennis Erskine says it all:



Dennis Erskine said:


> The softest sound on a sound track is 22dB. The typical noise floor in a quiet home in a quiet area is 33dB to 35dB. That is in the range of 6 to 7 times louder than the bottom of the sound track. Ok, so for whispers, and other low dB cues and voices on the sound track, that's no big deal...turn up the volume. But, now you run into problems. Normal speech is now 6-7 times louder ... talking is now yelling on the sound track. Next comes the louder sounds ... traffic, bombs, gun fire, etc. They are now 6-7 times louder as well ... too loud for comfort (or realistic listening). With the top of the dynamic range in a sound track at 105dB, that now must be 6-8 times louder. The problem is the vast majority of consumer equipment (amps/speakers) cannot handle that increase on the top end ... blowing out tweeters, clipping the amps, or amplifier distortion as you reach those levels.



*Q. What's the difference between soundproofing and acoustics?*

Technically, soundproofing is a form of acoustic control, but most people think of them as two different categories. Soundproofing is all about controlling the sound leakage in and out of the room. Acoustics is all about controlling the sound that is in the room. Think echos, reflections, reverberations, and the like. Both are important, if not at the same level. Soundproofing is likely important to many home theater builders -- acoustics is important to all of them.

*Q. What are the fundamental basics of soundproofing?*

There are four primary elements of soundproofing, roughly in order:


Decoupling
Adding Mass
Damping
Absorbing

All soundproofing methods will involve at least one of those elements.

Decoupling refers to creating gaps between solid surfaces. Sound is just a vibration and it travels very well on direct solid pathways. Decouple the solid materials and the pathway is broken.

Adding mass means to make the vibrating surfaces "heavier." Again, since sound is a vibration, it needs to actually vibrate any substance that it passes through. Heavier materials are simply harder to vibrate than lighter materials.

Damping is all about adding some material (usually a viscoelastic compound) to a surface to keep it from vibrating as much as it normally would. This is a relatively new development in soundproofing, but is so effective that it has become almost ubiquitous.

Absorbing is what you think it is - you add materials that can "trap" air and slow down resonating sound. This is an important step (and critical for acoustics) but for soundproofing, it is not as effective as the other four elements. That is, just adding a batt of fiberglass in your wall by itself will not do very much.

*Q. How do I apply those elements, practically?*

There are many ways to soundproof a room, and those elements can be adapted to fit many types of situations. Here are some high level thoughts:

First, address your walls. If you are able, consider decoupling them by creating a "room within a room". This is a separate 2x4 wall separated from your existing walls by an inch or so. If space is tight and it is new construction, then consider a staggered stud wall. Another alternative is to float the drywall by attaching the sheets to channels that are separated from the studs via clips. Add mass by layering at least two layers of 5/8" Type X drywall. Damp the drywall by putting Green Glue (or equivalent) between the sheets. Add absorption with insulation.

Then, do the same with the ceiling. Your ceiling is likely connected to either the floor above you or to the shared attic with the rest of the house. Decouple it by "floating" the ceiling, either using floating joists (in a "room within a room" concept) or via clips and channels. The former costs less from a materials perspective, but requires more room and is not always feasible. Add mass, damp, and add absorption the exact same way as the walls.

Now take care of your door. The door is typically the weakest link in the soundproofing chain, since it will be substantially thinner than the walls and will also need to be moveable. At the very least, get a 1 3/4" solid core door. Then add perimeter door seals (like weatherstripping). Consider an automatic door bottom to seal off the bottom of the door. If you need more soundproofing, then try adding more mass to the door using layers of MDF and damp with Green Glue. If even that is not enough, then (assuming you have room), create an "airlock" with two sealed solid core doors. That's the decoupling component.

You might also look at your floor, especially if it is on a concrete slab. Concrete transmits low frequencies very well and so it's possible for vibrations from air conditioning units or freezers or the like to intrude in your theater. Combat this by decoupling the floor via an additional layer of OSB or plywood laying on an underlayment. The underlayment adds mass and some absorption.

*Essential Reading*

Here are two links that give a great introduction to the topic of soundproofing:

Advice from Anthony Grimani (PMI) - Soundproofing 101: How to Keep Your Home Theater Quiet
Advice from Ted White (Soundproofing Company) - 4 Elements of Soundproofing

Quite a few articles on soundproofing quote from the original research done by the National Research Council of Canada. The most quoted white paper is here: Control of Sound Transmission through Gypsum Board Walls. If you ever hear references to "triple leaf", then this is where some of the key research concerning that was done. It's a very accessible paper.

In general, the articles on the Soundproofing Company website are excellent. The site is trying to sell soundproofing products, but the founder is an AVS Forum regular and the articles are very unbiased. Start with these articles: Soundproofing 101. Move on to these articles: Soundproofing Articles

This article is from the perspective of apartment buildings, but soundproofing is soundproofing and this is a great intro: Acoustical Considerations for Mixed-Use Wood-Frame Buildings (PDF)

*Interesting Links in this Thread*

Using OSB instead of Drywall as an initial layer (Post #4)
Should the "air gap" in a double wall be filled with insulation? (Post #10) (TL;DR - no)
Essential soundproofing links from BasementBob (Post #20)
Comparing soundproof door solutions (Post #30-50)
Solutions for non-permanently "plugging" a window in a theater (Post #31)
OSB as first layer; Does next layer of drywall need to be screwed into channels or directly into the OSB? (Post #64) (TL;DR - channels)


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## granroth

*Notable Soundproofing Threads and Links*

*General Soundproofing Topics*

*Need help with soundproofing my new HT*


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## granroth

One more reservation, just in case


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## granroth

First question! I am curious about people's experience with using OSB instead of drywall for at least one layer. Specifically, why was it done, and how was the soundproofing as a result?


Starting with "why". The two reasons I've heard so far is that OSB has better shear strength than drywall and thus is a better fit for freestanding "room in a room" walls AND that using OSB allows you to screw things (columns, soffits, acoustics treatments, etc) anywhere, without regard to studs. Are there more reasons?


OSB definitely has less mass than drywall for the same thickness but not by a huge amount. 5/8" Type X drywall tends to be around 2.2 lbs sq ft, while 19/32" OSB is around 2.0 lbs sq ft. The far more reasonable priced 15/32" OSB is 1.5 lbs sq ft. From a practical point of view, what kind of difference does this make in soundproofing?


I guess the meta question is: is it worth spending 2x the cost to use OSB?


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## BIGmouthinDC

On OSB the reasons why I've gone along with it on a few builds include:


1) it was already delivered and stacked in the basement when I got there or,

2) we intended to screw a lot of extra crap inside the room and wanted a good secure layer. Things like soffits, Coffered ceilings, tiered level ceilings etc.


We always used 5/8 because if you are going to put up with the splinters in your hands you might as well go all in.


There is one thing I almost always do and and that is to substitute at least one sheet of 5/8 in the projector mount location for the first layer of drywall then cover it with drywall.


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## granroth




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/0_100#post_24152143
> 
> 
> On OSB the reasons why I've gone along with it on a few builds include:
> 
> 
> 1) it was already delivered and stacked in the basement when I got there or,
> 
> 2) we intended to screw a lot of extra crap inside the room and wanted a good secure layer. Things like soffits, Coffered ceilings, tiered level ceilings etc.



Is the OSB more a convenience thing, even then? It seems like putting up soffits, coffered ceilings, and the like can be one "conventionally" using blocking attached to studs or joists. Is it that OSB makes it easier to not have to worry at all about placement OR is it that having to hit channels properly is that much more of a pain?


> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/0_100#post_24152143
> 
> 
> We always used 5/8 because if you are going to put up with the splinters in your hands you might as well go all in.
> 
> 
> There is one thing I almost always do and and that is to substitute at least one sheet of 5/8 in the projector mount location for the first layer of drywall then cover it with drywall.



That makes a lot of sense!


You've done at least a couple builds with floating joists, right? In that case, since the walls aren't attached to anything but themselves and their spanning joists, were you ever concerned that drywall wouldn't have enough shear support to keep the walls from moving?


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## PApilgrim

This thread is one I read through since still in the planning phases of my build and discusses more of the performance and value end of the OSB vs drywall question. It is a little dated in terms of costs perhaps but a good read.

http://www.avsforum.com/t/1157120/does-osb-seem-all-that-less-dense 


My two cents - I plan on using OSB for the ease of future use for all soffit and inside the soundproofed room construction. It allows more flexibility for sure.


An analogy from my unrelated experience - I resided my old house with vinyl siding (was aluminum). It was built in the 70's and they used this fiber board stuff which has the structural integrity of a greasy pizza box. So, I had to try and guess where there 16" studs were for the majority of the house siding since measuring from the last stud that I finally found would get you only within about 2" of the next stud center due to the builders having framed it up inconsistently spaced (I am sure this has never occurred in any of your houses!).


I have no desire to try and hit the studs and/or furring channel only and worry that all my $$$ devoted to clips and channel and general soundproofing could be short circuited by a few misplaced screws. Hope this is helpful.


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## BIGmouthinDC

Yes rigidity of a totally floating structure was a reason for OSB in one case. When I talk about having a secure screwing surface I am reffering to walls and ceiling on a clips and channel system. Mostly all I ever do.


As for hitting channel on the ceiling. Let me know how that works out for you. I'd rather just screw anyplace I can. This is a four level tiered ceiling built inside the clip and channel ceiling with a layer of OSB and a layer of DW.


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## granroth




> Quote:
> Originally Posted by *PApilgrim*  /t/1509173/soundproofing-master-thread/0_100#post_24153232
> 
> 
> This thread is one I read through since still in the planning phases of my build and discusses more of the performance and value end of the OSB vs drywall question. It is a little dated in terms of costs perhaps but a good read.
> 
> http://www.avsforum.com/t/1157120/does-osb-seem-all-that-less-dense



Oh, this thread is darn near perfect for my question! I love, too, that I get two direct quotes from Ted White himself:


> Quote:
> Originally Posted by *Ted White*  /t/1157120/does-osb-seem-all-that-less-dense/0_100#post_16692736
> 
> 
> The OSB first layer is a great idea. I would not worry about the small differences in density



and (emphasis added by me)


> Quote:
> Originally Posted by *Ted White*  /t/1157120/does-osb-seem-all-that-less-dense/0_100#post_16692949
> 
> 
> Mass is mass. True enough. There is the other factor of stiffness also. If, as the OP indicated, GG is involved, there is the matter of damping efficiency. Damping is optimized when the stiffness of each layer is the same.
> 
> 
> So double 5/8" drywall is massive and equal in stiffness. Optimal. Small deviation in stiffness (no idea what that delta is) will reduce damping efficiency.
> 
> 
> Having said all that, I would myself be inclined to use an initial layer of OSB for the sheer convenience of being able to stick a screw anywhere layer. *The small variance in mass and stiffness is likely quite minimal to the point of being a non-issue.*





> Quote:
> Originally Posted by *PApilgrim*  /t/1509173/soundproofing-master-thread/0_100#post_24153232
> 
> 
> My two cents - I plan on using OSB for the ease of future use for all soffit and inside the soundproofed room construction. It allows more flexibility for sure.
> 
> 
> An analogy from my unrelated experience - I resided my old house with vinyl siding (was aluminum). It was built in the 70's and they used this fiber board stuff which has the structural integrity of a greasy pizza box. So, I had to try and guess where there 16" studs were for the majority of the house siding since measuring from the last stud that I finally found would get you only within about 2" of the next stud center due to the builders having framed it up inconsistently spaced (I am sure this has never occurred in any of your houses!).
> 
> 
> I have no desire to try and hit the studs and/or furring channel only and worry that all my $$$ devoted to clips and channel and general soundproofing could be short circuited by a few misplaced screws. Hope this is helpful.



Yeah, I'm pretty convinced to use OSB based on the input here and on the quoted thread. I don't have to worry about accurate spacing in my theater, since I'm going to control every single stud and joist... but not having to worry about the spacing at all would make things so much easier. Outside of the theater, though... I try not to think about the building practices of whoever built my house back in 1980. Either there was no such thing as a building code back then (doubtful) or they paid off the inspector. Yeesh.


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## granroth

(Moved from poor choice of initial thread )


I am trying to find an answer to an apparently esoteric acoustic question: does inserting insulation in between the walls in a double wall scenario either a) hurt the soundproofing b) increase the soundproofing or c) do nothing one way or another? I am finding directly contradictory info on this topic and am hoping that some acoustics experts here can set me straight.


Okay, to start, there appears to be two primary sources of info related to soundproofing with "double leaf" assembly. The original source was the Owens Corning study done by Geiger and Hamme in 1972. I find this referenced all over the place, but have not found the actual original research. The other primary source is the work done the National Research Council of Canada in the publication Control of Sound Transmission through Gypsum Board Walls . There is also secondary (excellent) information found on such sites as The SoundProofing Company.


From them, we have the canonical example of a "double leaf" wall assembly with an STC 63 rating.

 


The documents all describe the "air gap" as being 8" in this example, since the insulation acts as air in a double leaf scenario. Therefore, the "air" is made up of *3.5" Batt + 1" empty space + 3.5" Batt*


I'm going to dwell on the fact that "insulation = air" for a bit. On the SoundProofing Company website, we see this quote :


> Quote:
> For thermodynamic reasons, insulation essentially mimics a somewhat larger air cavity.



That's in support of the reasoning that adding insulation to this assembly will notably decrease sound leakage compared to having pure empty space. I take from that that "insulation = air" AND "insulation = better air than air".


The research done by NRC appears to say that same thing here :


> Quote:
> The optimal amount and type of soundabsorbing material for use in a cavity were investigated in a preliminary study in which seven different absorptive materials were used in a window-sized specimen formed from two layers of 3-mm-thick plastic. The study showed that:
> sound reduction continuously improves as the thickness of sound-absorbing material covering the whole face of the specimen is increased.
> there is no significant change when the sound-absorbing material is moved from the middle of the cavity to a position near one face.
> *partially filling the cavity from bottom to top, or from sides toward the middle, is less effective than having the same amount of material completely covering the whole inner face of the cavity.*
> the type of material used influences the sound reduction measured in frequencies ranging from 500 to 2000 Hz. The greater the airflow resistivity of the material, the greater the sound reduction. Because there is a direct correlation between the density of the materials and sound reduction in this frequency range, the sound reduction tends to increase as the density of the sound-absorbing material increases. However, in terms of the STC, no important acoustical differences were found among the sound-absorbing materials used in this preliminary investigation



I stressed that line, because to me, that is saying that the canonical example of a "double leaf" assembly actually is non-ideal, since the cavity is partially filled with insulation and NRC's research claims that the best results come from cavities that are completely filled with insulation (no empty space).


So let's take that "knowledge" and apply it thusly:

 


This is the exact same as the canonical example, but now we've replaced the empty air gap with insulation. If "insulation = air" and "insulation = better air than air" and "a full cavity is more efficient than a partially filled cavity", then it stands to reason that this assembly would be at _least_ as good if not _better_ than the typical assembly.


Right now, if you are reading this and know that I am completely wrong, then jump right in and tell me how wrong I am and why I'm wrong!


If I'm not wrong, then why can't I find any evidence that my conclusion is true?







In search after search on AV sites, studio forums, and the like, I keep hearing that the gap between the walls MUST be empty air and MUST NOT be insulation. But nobody says why and nobody references the above research one way or another.


So yeah, I'm really confused. If I'm wrong, then what am I missing? If I'm not wrong, then why isn't this talked about?


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## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24153664
> 
> 
> Insulation in the walls helps soundproofing.
> 
> Amongst other things, it dampens the resonance of the wall leafs.
> 
> 
> If you're building walls, ceilings, around a home theatre, the rule of thumb is: insulation in the cavity is REQUIRED.
> 
> 
> I don't regard Owens Corning as an expert in this area.
> 
> NRC is an expert. Very much an expert.
> 
> 
> The stuff published by Brian at soundproofingcompany.com (aka Green Glue) is also really really good -- especially for us since it's mostly done from a home theatre point of view. Some of it gets dumbed down by the web guys there though, which isn't optimal.
> 
> 
> This line by the NRC is correct,
> *partially filling the cavity from bottom to top, or from sides toward the middle, is less effective than having the same amount of material completely covering the whole inner face of the cavity.*
> 
> 
> but you've interpreted it incorrectly.
> 
> You're thinking of batts of fiberglass pink, or rigid Rockwool.
> 
> Consider what happens with blown in cellulose insulation in a wall cavity.
> 
> 
> They're not talking about coupling the entirety of the leaves to each other by insulation as you drew.
> 
> 
> What they mean is any of these are good:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> but this is bad
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Similarly batts that fall off one wall, or shrink with time, or blown in cellulose insulation, all break the rule:
> 
> The sound must go through insulation to be damped.
> 
> If there's a path around the insulation, (over it as would be the case with cellulose, or around it as shown in the above diagram), that's bad.
> 
> 
> Note that Brian of soundproofingcompany.com did some tests and was surprised to find that
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> worked remarkably well, from a bang-for-the-buck point of view.
> 
> .



Thank you! That does, indeed, sound like a much more reasonable interpretation of the NRC data than I had.


I don't know that it fully answers my question, though. It shows that a fundamental pillar of my reasoning was flawed, but not necessarily that the conclusion was completely incorrect.


The key end question for me is if filling the empty air gap with a thin layer of fiberglass insulation will be detrimental at all? I get that the NRC data doesn't indicate that it would help, but they apparently don't address if it would hurt. Does anybody?


I wonder if small scale testing could actually work in cases like this. That is, what if I created some 2' x 2' walls with studs and drywall and insulation and the like, just like a full-size wall. I could separate the mini-walls with a 1" gap and then put speakers and/or a subwoofer on one side and a microphone on the other side. The speaker side could be completely incased with a couple feet of insulation. If I then ran one test with an empty air gap between the mini-walls and one test with insulation there, would I have an accurate representative sample of the differences? Or does some property of the sound negate all kinds of small scale tests?


I'm thinking that a small scale test definitely wouldn't work with acoustical treatment, since so much of treatment depends on the size of the sound waves per individual frequencies. I'm not sure if that translates to soundproofing or not.


(BTW, I just now realized that BasementBob is the one and the same as Bob Golds. I love your site! It's high up there on my "Google Suggests" URL bar)


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## Ted White

Let's keep in mind that insulation doesn't do much on its very best day. Of the 4 Elements, it brings the least to the table. Interestingly, however, it's sometimes the most discussed.


What we see is that a bit of insulation does most of the work and the remaining insulation does little more. When they talk about the cavity being "filled" they are more referring to the side-to-side filling of the cavity. Insulation is filling the space between wall studs or joists.


Filling a cavity 50%-70% is about as good as it gets. Filling 100% doesn't get you anything audible. Keep in mind 3 STC points is audible. 2 STC point difference isn't perceivable by the human ear.

http://www.avsforum.com/t/1045780/ceiling-insulation-thickness 


I have not and do not suggest completely filling the ceiling cavities beyond R13. I also don't spec filling that 1" insulation gap in a double stud wall. Not at all.


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## granroth




> Quote:
> Originally Posted by *Ted White*  /t/1509173/soundproofing-master-thread/0_100#post_24157995
> 
> 
> Let's keep in mind that insulation doesn't do much on its very best day. Of the 4 Elements, it brings the least to the table. Interestingly, however, it's sometimes the most discussed.
> 
> 
> What we see is that a bit of insulation does most of the work and the remaining insulation does little more. When they talk about the cavity being "filled" they are more referring to the side-to-side filling of the cavity. Insulation is filling the space between wall studs or joists.
> 
> 
> Filling a cavity 50%-70% is about as good as it gets. Filling 100% doesn't get you anything audible. Keep in mind 3 STC points is audible. 2 STC point difference isn't perceivable by the human ear.
> 
> http://www.avsforum.com/t/1045780/ceiling-insulation-thickness
> 
> 
> I have not and do not suggest completely filling the ceiling cavities beyond R13. I also don't spec filling that 1" insulation gap in a double stud wall. Not at all.



Thanks! This is quickly demolishing the entire framework for my hypothesis on the effectiveness of filling the space. The one remaining bit is that some people have asserted that any fiberglass in the air gap would actually create a sound bridge between the two walls, thus re-coupling them and making everything worse. What's your take on that?


Also, I added the Ceiling Insulation Thickness thread to the summary posts. I doesn't look like the NRC original research doc (IR-766) is online anymore, so it's handy that the table is quoted.


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## granroth

*Open question:* What are the best build threads that go into detail on soundproofing aspects?


I'm having a tough time finding such threads, beyond the two I have already posted above. Most build threads I've bookmarked tend to spend lots of time on such things as risers and stages and screen walls and speakers and the like (all great, which is why they are bookmarked) but tend to gloss over the soundproofing bits.


What are some great threads on installing doors? Building a staggered wall? Building a dead vent? Floating a floor? Etc?


Really, any thread that goes into great detail on any aspect of soundproofing will be appreciated!


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## Ted White

I'm glad you mentioned Brian Ravnaas above. He is truly the soundproofing master. He developed the Green Glue and he and his brother founded the company. Was great to be part of all that way back in the day.


granroth, we have SIMs for all these construction aspects already. Fully illustrated.


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## matthewa




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/0_50#post_24159691
> 
> *Open question:* What are the best build threads that go into detail on soundproofing aspects?
> 
> 
> I'm having a tough time finding such threads, beyond the two I have already posted above. Most build threads I've bookmarked tend to spend lots of time on such things as risers and stages and screen walls and speakers and the like (all great, which is why they are bookmarked) but tend to gloss over the soundproofing bits.
> 
> 
> What are some great threads on installing doors? Building a staggered wall? Building a dead vent? Floating a floor? Etc?
> 
> 
> Really, any thread that goes into great detail on any aspect of soundproofing will be appreciated!



Check out Elill build he's getting into soundproofing and doing a lot around DIY vents ATM http://www.avsforum.com/t/1186799/downunder-theatre-mkii/250_50#post_24153073


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## granroth




> Quote:
> Originally Posted by *Ted White*  /t/1509173/soundproofing-master-thread/0_100#post_24160387
> 
> 
> granroth, we have SIMs for all these construction aspects already. Fully illustrated.



Yes, I know. Right now, if I type 's' into Google Chrome, it automatically sends me to your website, since it knows that that's where I'm going. Why bother having me type out more if it knows for certain that that's where I'm going. Fully 90% of your website hits lately are probably from me! I'm definitely going to be calling you guys sometime in the next few weeks (hopefully; my build thread has more info).


But here's the deal -- all of those SIMs will be useful for _me_ and for anybody else that is a customer, but since they are almost surely copyrighted, they can't be posted for general consumption. I'm really hoping that this thread will mirror the usefulness of the rest of AVS Forum and give people the info that they need, without having to become a customer of a specific company. For instance, I can get tons of info on acoustical treatments in the Acoustical Treatments Master Thread, without actually contracting with Erskine or GIK or MSR/PMI.


I know that so far this thread is just me asking a bunch of questions, but that's NOT my intent. I really want this to be both a central clearing house of proven soundproofing methods as well as an appropriate place to ask specific soundproofing questions. I've only been an AVS Forum member for a little while, but I've lurked for much longer... and I've seen so many of the same questions asked over and over. It really seems like there should be a thread like this (one way or another) for those. To make it truly effective, though, all of the info on it needs to be freely shared.


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## BasementBob




> Quote:
> Originally Posted by *Ted White*  /t/1509173/soundproofing-master-thread#post_24157995
> 
> 
> Filling a cavity 50%-70% is about as good as it gets.


Yep I'll agree with that.

Although I'd be willing to go as high as 87% (7" of an 8" cavity is both studs filled with a 1" air gap), but I don't complain about anything over 25% of the gap filled.

It's exponential diminishing returns for your dollar.


I like your NRC ir766 chart









although I was going by what Brian said too.


> Quote:
> Originally Posted by *someone*
> 
> I'm wondering if putting insulation in between the walls will HURT the performance


What do you mean by performance?

- performance within the room, acoustically (absorb, diffuse, reflect)

- performance of the wall as a sound stopper, transmission/reflect


I'm assuming you know what the resonance dip and coincidence dip are in STC, from your travels to SoundproofingCompany (Green Glue).


If you mean stopping sound from going through the wall, then

a) a little insulation in a wall cavity is a good thing (1" thick) from "two perspectives".

b) more insulation up to 87% of the wall cavity is a good thing, with diminishing returns

c) coupling otherwise decoupled walls by having touching insulation, is probably a bad thing. In any event it's already a complete waste due to (b), so who cares.


"two perspectives"

- soundproofing, stopping sound from going through the wall. You want this for two reasons: to stop annoying the wife and sleeping kids and rattling dishes in the kitchen cupboards; and to keep the noise floor in the room low so you can hear the quiet scenes without raising the volume when trucks and airplanes go past your house or someone flushes the toilet or the furnace starts.

- acoustics, within the room itself. If you have a room mode that's the same frequency as the walls resonate, then the walls could help to damp that, but: (1) there are perhaps two people on the planet who can build such a wall and rebuild/tune it after the room is full of furniture and an average people load so odds are really good that any effort made on this technique will only make the room acoustics worse, and (2) doing so would completely defeat the purpose of the first perspective above as it would let a lot of sound through the walls at this frequency.


Build the walls according to the observations/recommendations of NRC and Green Glue.

Deal with in-the-room issues within the room, not with the walls.

Step 1: Decide what isolation you want, at each frequency, and pick a wall from the NRC/Green guys that matches. That's engineering.

Reduce the wall isolation if you've got other issues that would bypass it, or if the significant other refuses the cost. and redo step 1.


Understand a bit why it works, so that during construction you can avoid problems.

Why is nailing through a RISC clip bad?

If someone leaves a stick leaning from one decoupled wall to another decoupled wall within the wall cavity, why is this bad?

Where is acoustical caulking needed, and how long does it last?

What is receptacle putty?

etc


If green glue happens to damp some additional room modes, well that's cool too. A free benefit. But not a design consideration for the walls themselves.


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread#post_24159663
> 
> 
> . I doesn't look like the NRC original research doc (IR-766) is online anymore.


 http://primaryacoustics.com/images/ir766.pdf


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread#post_24159691
> 
> *Open question:* What are the best build threads that go into detail on soundproofing aspects?
> 
> 
> What are some great threads on installing doors? Building a staggered wall? Building a dead vent? Floating a floor? Etc?



The book "Home Recording Studio: Build It Like the Pros" by Rod Gervais 

There's nothing better than this. Answers everything you want to know, with practical advice.


Honourable mentions

- "How to Build a Small Budget Recording Studio from Scratch " by F. Alton Everest and Mike Shea 

- "Noise Control in Buildings: A Practical Guide for Architects and Engineers" by Cyril M. Harris (the paperback version is cheaper. Nice stuff about concrete walls)



Combined with the NRC papers

and Brian's stuff (the website, and about 40+ papers),

and to a lesser extent the Resilient Sound Isolation Clip (RSIC-1) stuff,

And maybe Paul Woodlock's (his walls, his floating room, his hvac, and of course his door ), and Galaxy Studios (Belgium) (with the unheard insulation value of plus 100 dB between 2 rooms 60cm apart) for over-the-top examples of floating rooms and doors and hvac.

that's all I needed to form an opinion.



> Quote:
> old NRC papers
> 
> 
> ir772 Electrical Recepticals BackToBack.pdf
> 
> IRC - Institute for Research in Construction.htm
> 
> IRC 02-108.htm
> 
> IRC Avoiding Flanking Noise Transmission.htm
> 
> IRC BSI '85 - Noise Control in Buildings - Questions and Answers.htm
> 
> IRC BSI '85 - Sound Transmission Through Building Components.htm
> 
> IRC CBD-164_ Acoustical Effects of Screens in Landscaped Offices.htm
> 
> IRC CBD-186_ Office Partitions Acoustical Requirements for Design and Construction.htm
> 
> IRC CBD-236_ Introduction to Building Acoustics.htm
> 
> IRC CBD-239_ Factors Affecting Sound Transmission Loss.htm
> 
> IRC CBD-240_ Sound Transmission Through Windows.htm
> 
> IRC CBD-41_ Sound and People.htm
> 
> IRC concrete block ir586.pdf
> 
> IRC ctu01e Gypsum Board Walls.pdf
> 
> IRC ctu13e Concrete Block Walls.pdf
> 
> IRC ctu16e Sound Isolation and Fire Resistance firestop airgap.pdf
> 
> IRC ctu22e Floor Vibrations.pdf
> 
> IRC ctu25e Airborne Sound through Floors.pdf
> 
> IRC ctu27e Electrical Outlet.pdf
> 
> IRC ctu35e Impact Sound through Floors.pdf
> 
> irc electrical receptacles boxes nrcc43410.pdf
> 
> IRC Fire stops in walls can provide both fire resistance and sound isolation.htm
> 
> IRC flanking multi family dwellings rr218.pdf
> 
> irc flanking nrcc46629.pdf
> 
> irc flanking rr103.pdf
> 
> IRC flanking wood rr219.pdf
> 
> irc floating floor ir802.pdf
> 
> irc floor flanking nrcc45724.pdf
> 
> irc floor impact ctu35e.pdf
> 
> IRC floor rr169.pdf
> 
> IRC floor wall rr168.pdf
> 
> IRC How wall-floor details affect sound insulation in multi-family dwellings.htm
> 
> IRC ir693 walls.pdf
> 
> IRC ir760 airport.pdf
> 
> IRC ir761 walls.pdf
> 
> ir766.pdf
> 
> IRC ir811 floors.pdf
> 
> IRC ir826 test facility.pdf
> 
> IRC NRC's Institute for Research in Construction- Search.htm
> 
> IRC nrcc44692 resilient channel wall model.pdf
> 
> irc nrcc44764 brick.pdf
> 
> IRC rr103 flanking.pdf
> 
> IRC sand in walls cupboard door heard brn232.pdf
> 
> IRC Sound Transmission Through Concrete Block Walls.htm
> 
> IRC Thickness of Air Space in Double Glazing.htm
> 
> IRC Thirteen concert hall test data ir668.pdf
> 
> IRC Washing Machine, Dryer, Dishwasher, Counter, Toilet resonance resilient channel RC 125hz.htm
> 
> IRC Washing Machine, Dryer, Dishwasher, Counter, Toilet resonance resilient channel RC 125hz_files


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24163310
> 
> 
> What do you mean by performance?
> 
> - performance within the room, acoustically (absorb, diffuse, reflect)
> 
> - performance of the wall as a sound stopper, transmission/reflect
> 
> 
> I'm assuming you know what the resonance dip and coincidence dip are in STC, from your travels to SoundproofingCompany (Green Glue).
> 
> 
> If you mean stopping sound from going through the wall, then
> 
> a) a little insulation in a wall cavity is a good thing (1" thick) from "two perspectives".
> 
> b) more insulation up to 87% of the wall cavity is a good thing, with diminishing returns
> 
> c) coupling otherwise decoupled walls by having touching insulation, is probably a bad thing. In any event it's already a complete waste due to (b), so who cares.



Performance, in this context, refers to using the wall as a sound stopper. Your c) is the key bit in this -- does loosely packed fiberglass couple the two decoupled walls? That is, I know that any sort of rigid material like wood (2x4s), steel (screws, nails), foam (insulation), etc will definitely couple the walls. Fiberglass is used enough in a single 2x4 wall where it touches both sides that I wonder if it's considered a coupling agent at all. If it's not, then perhaps having it fill the air gap would not hurt the soundproofing performance.


It's a fair question to ask why you'd want to do it, if it's not helping at all (we've established that it definitely does not). Consider exterior walls and those with an attic above them. In the exterior wall case, that extra R-3.5 for the inch (vs R-0.68 for the empty air) could be appreciated. In the attic case, it could prevent all sorts of things (bugs, debris, etc) from falling down into the gap from the attic. That is, it doesn't have any soundproofing benefits, but if it doesn't hurt the soundproofing, then it still has benefit from other perspectives.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24163333
> 
> http://primaryacoustics.com/images/ir766.pdf



Yeah, I found that. I was a little leery about posting it, though, since the article was removed from the NRC website. Reposting copyrighted materials gets into some grey areas that I prefer to avoid. Of course, this is just linking to it but the US courts haven't always agreed that that's a worthwhile distinction.


As far as that goes, I also found a PDF of the Rod Gervais Home Recording Studio book. Same deal, though -- it's copyrighted material and providing a link to it might be more trouble than it's worth.


In general, lots of stuff is available in PDF form if you do an Advanced Search in Google and specify 'pdf' as the type (or add 'filetype: pdf' to the end of a search)


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread#post_24164710
> 
> 
> Yeah, I found that. I was a little leery about posting it, though, since the article was removed from the NRC website.


Ok, then this one
http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir766/ir766.pdf 


I'd be less worried about copyright on the NRC stuff.


> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread#post_24164710
> 
> 
> I also found a PDF of the Rod Gervais Home Recording Studio book.


That one copyright applies. People should really buy that book. And not just because I know the author.


----------



## granroth

Thanks, Bob! I updated the summary posts with your links. And no, I wouldn't dream of posting a link to a copyrighted book that is currently available for sale.


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread#post_24164687
> 
> 
> Performance, in this context, refers to using the wall as a sound stopper. Your c) is the key bit in this -- does loosely packed fiberglass couple the two decoupled walls?


Actually, the key is this


Step 1: Decide what isolation you want, at each frequency, and pick a wall from the NRC/Green guys that matches. That's engineering.


If you build something that hasn't been tested and measured, you're guessing. Why bother. Personally I wouldn't even consider it.


If on the other hand you have the NRC's or Green Glue's research budget, you can build the wall configuration you're curious about and test it at a rated facility.

But if you're not willing to do that, you won't get answers, unless someone else does.


Tweaking in your home with radical ideas, usually is just money wasted. When Brian started doing the green glue stuff, the big internet question was if limp mass in the walls really helped or not. (turns out not, sometimes it's just a 3 leaf wall which is bad)


When considering if filling that last inch with fluffy fiberglass pink is going to do any good,

you'd be much better off considering if you could use concrete instead of drywall, using a tested with published frequency loss measurements, design with concrete.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24165304
> 
> 
> Actually, the key is this
> 
> 
> Step 1: Decide what isolation you want, at each frequency, and pick a wall from the NRC/Green guys that matches. That's engineering.
> 
> 
> If you build something that hasn't been tested and measured, you're guessing. Why bother. Personally I wouldn't even consider it.
> 
> 
> If on the other hand you have the NRC's or Green Glue's research budget, you can build the wall configuration you're curious about and test it at a rated facility.
> 
> But if you're not willing to do that, you won't get answers, unless someone else does.
> 
> 
> Tweaking in your home with radical ideas, usually is just money wasted. When Brian started doing the green glue stuff, the big internet question was if limp mass in the walls really helped or not. (turns out not, sometimes it's just a 3 leaf wall which is bad)
> 
> 
> When considering if filling that last inch with fluffy fiberglass pink is going to do any good,
> 
> you'd be much better off considering if you could use concrete instead of drywall, using a tested with published frequency loss measurements, design with concrete.



I don't disagree with you, but I do think you are describing a form of the holy grail. Lab tested data is definitely what we all want to get, but it sometimes just doesn't exist. Sometimes the only answers we can get is "best guess" or anecdotal and that, I'd argue, is better than nothing.


For instance, as far as I know, there are no lab tests that compare OSB + GG + Drywall vs Drywall + GG + Drywall. But when Ted says that he thinks the damping impact would be too minimal to worry about, then that's as good as it'll get and good enough for me.


So what I'm looking for with the insulation question is just that -- an educated guess or some anecdotal evidence.


----------



## granroth

*Question:* What are the prevailing opinions on the validity of small scale soundproofing tests?


I'm wondering if it's possible to perform some small scale tests to compare various soundproofing methods. I'm not even remotely suggesting that any small scale tests would even start to approach the reliability of a full lab test... but would they be at least a little useful?


The biggest reason I'm thinking that maybe they wouldn't be at all valid is because I'm 99% certain that small scale tests absolutely won't work for comparing acoustical treatment plans. Acoustical treatments are designed to work with specific wave lengths and so the actual size of a room matters a lot.


But is that true for soundproofing? If all I'm going to test is an overall DB drop, then would a small scale test at least approximate a result?


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread#post_24165799
> 
> 
> I'm wondering if it's possible to perform some small scale tests to compare various soundproofing methods. I'm not even remotely suggesting that any small scale tests would even start to approach the reliability of a full lab test... but would they be at least a little useful?



Yes.

Brian once did an experiment like this:

Most of the noise through a wall is at resonance, and resonance can be tested with a small 1'x1' piece of material and an accelerometer.

As I recall, he used it to give him a better idea of what to build full scale and test in a real testing facility.


But resonance in a 2 leaf wall, is because of the leaf-air-leaf system, I'm not sure how to test that small scale off hand.


I think he even mused how to, although I don't know if he ever got around to it, make his own testing facility with thin concrete walls to test gypsum walls approximately.


> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread#post_24165799
> 
> 
> But is that true for soundproofing? If all I'm going to test is an overall DB drop, then would a small scale test at least approximate a result?


No.

Just good quick hints of what to really test; of what might give good results.


----------



## granroth

*Question*: Is there qualitative data on the effectiveness of various door designs?


There's a decent amount of test data concerning the effectiveness of various forms of wall construction. I'm not finding any such data concerning doors, beyond the basic "hollow core" vs "solid core".


For instance, it makes intuitive sense that adding a layer of 3/4" MDF + Green Glue to a solid core door will make it more sound proof. But do we know the numbers? What about adding another layer?


Now compare that to single doors vs double doors. Will that approach the effectiveness of a double wall, if they are solid core? And what about a mass-added single door vs a conventional double door setup?


----------



## BasementBob

There's single doors: wood hollow core, steel hollow core, wood solid core, steel fire door (aka steel hollow core, thicker steel, filled with insulation, often with better seals), custom door, professional acoustical doors.

There's double doors: communicating doors (aka tandem doors, width of the double stud wall) , airlock doors (one man room), and lobby doors (a real room).


Back in 1994, BBC did a study of "door blanks" and "door seals" which included multi frequency test results, but it was mostly the types of doors they had handy which were kind of thin.


Most of the 'professional acoustical doors' or manufactured units specifically designed for sound isolation are sold with an STC rating only.

Steel doors going up to around STC 55, wood doors up to around STC 49.


Overly is nice enough to have frequency tests at the bottom of each of their products
http://door.overly.com/products.aspx?family=Acoustical&prodType=door&material=metal 


An airlock, with a couple of heavy steel fire doors with decent seals, usually works well.


SAE used to have some very nice summary pages on acoustical isolation techniques, again over a decade ago. One of the things they recommended for airlocks was hanging thin open-cell foam on the side of the doors on the inside of the airlock. Given the study of walls above it should be obvious why this helps.


Doors are remarkably sensitive to the seals they have, so a simple study of door types while indicative is not predictive of installed results. I seem to recall a bunch of multi frequency test results for single doors, where they glued the door into a test frame.


----------



## tmhouse

*Question:* What are the best techniques to isolate a window when already installed windows exist in a wall that will be part of the "soundproof" room?


My main concern is for a window that must remain in use (basement egress). A plug is the most common recommendation here when the window will remain in use. How best to create this plug? Tolerance for the size of the plug compared to the size of the opening to be covered? Good build threads that present method for building the plug?


Alternative question could be for windows that can be covered - and probably an easier answer.


In my case, the wall around the window will be on clips, hat channel, DD + GG, or something very similar to this plan. Does this common method for room isolation of the wall around the window create any changes in recommendation?


----------



## granroth




> Quote:
> Originally Posted by *tmhouse*  /t/1509173/soundproofing-master-thread/0_100#post_24176165
> 
> *Question:* What are the best techniques to isolate a window when already installed windows exist in a wall that will be part of the "soundproof" room?
> 
> 
> My main concern is for a window that must remain in use (basement egress). A plug is the most common recommendation here when the window will remain in use. How best to create this plug? Tolerance for the size of the plug compared to the size of the opening to be covered? Good build threads that present method for building the plug?
> 
> 
> Alternative question could be for windows that can be covered - and probably an easier answer.
> 
> 
> In my case, the wall around the window will be on clips, hat channel, DD + GG, or something very similar to this plan. Does this common method for room isolation of the wall around the window create any changes in recommendation?



Thank you for asking this question, because I'm going to have to do the _exact_ same thing in my theater. In my case, it's not a basement, but it is still two very large windows that cannot be permanently covered.


The best build thread on a window plug that I've seen so far is in the Dark Knight Theater thread. Here's a link to the post with some details: The Dark Knight Theater - Window Plug Details Post 


I'm still searching for even more details on pros/cons and possibly other options, if they exist.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24171842
> 
> 
> SAE used to have some very nice summary pages on acoustical isolation techniques, again over a decade ago. One of the things they recommended for airlocks was hanging thin open-cell foam on the side of the doors on the inside of the airlock. Given the study of walls above it should be obvious why this helps.
> 
> 
> Doors are remarkably sensitive to the seals they have, so a simple study of door types while indicative is not predictive of installed results. I seem to recall a bunch of multi frequency test results for single doors, where they glued the door into a test frame.



Well! This all led me down some very interesting paths. I got the Rod Gervais book and man, you are NOT kidding that that book is good! Very practical and very detailed in the parts that mattered. Reading his 'doors' chapter confirmed the importance of seals (not that I doubted you) and steered me towards this thread:

http://www.gearslutz.com/board/studio-building-acoustics/875142-jhbrant-door-design-diy.html 


That site has a pretty terrible name, but it seems to be packed with acoustic experts. John H Brandt posted his PDF on making the Ultimate Studio Door and it even includes CAD drawings. It matches what Rod says in a lot of parts and deviates a little in some others. The thread contains the PDF as well as a discussion about building it.


I will start by saying that neither resource indicated any qualitative numbers on evaluating any particular door solution, but their practical advice may well override that. I'll summarize.


Rod prefers a single mass-loaded door to double "stock" solid core doors, although both are excellent. His door is a 1-3/4" solid core door (type doesn't matter) with a layer of 1/8" lead (8psf) and a "stepped" layer of plywood. The lead, alone, weighs some 160 lbs for a 36" door. It also costs somewhere in the $600-$800 range. The stepped layers allows for a "bank vault" style door seal. He strongly recommend a commercial door closer, since the very high weight of the door could absolutely cause injury for small children.


John also likes mass-loaded doors, but his design calls for two of them. He does not use a base solid core door but instead makes a door from scratch using plywood, 2x4s, and SAND. The design includes the bank vault door seals and commercial door closer.


Both also assert that the fact that the door frame couples the two walls has no noticeable effect on sound loss. That is, there is sound loss by the coupling, but not by enough that matters. More importantly, these doors are so heavy that it's imperative that they have a very solid frame (Rod's frame is made of 5/4 stock wood, rather than the typical 5/8" pine).


So what can I conclude from this? Well, nothing qualitatively. However, expert advice says that two mass-added doors is better than one mass-added door but that one mass-added door is better than two unaltered doors. No matter what, have excellent door seals, preferably in a bank vault style double seal.


----------



## xm15_owner

Hey fellow Gilbert resident check this window plug out.

Starting at this post.

http://www.avsforum.com/t/1468993/the-retirement-dream-home-theater/210#post_23740019 


I think bigmouthindc did a window plug in one of his builds but I can't find the link on my phone


Pete


----------



## granroth




> Quote:
> Originally Posted by *xm15_owner*  /t/1509173/soundproofing-master-thread/0_100#post_24177529
> 
> 
> Hey fellow Gilbert resident check this window plug out.
> 
> Starting at this post.
> 
> http://www.avsforum.com/t/1468993/the-retirement-dream-home-theater/210#post_23740019
> 
> 
> I think bigmouthindc did a window plug in one of his builds but I can't find the link on my phone



That's a great one, thanks! That thread has a lot of other great detail, too, so it's a great subscription in any case.


The only plug that I remember Big doing was a permanent one (walled over it). I could definitely have missed one, though.


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24177507
> 
> 
> He strongly recommend a commercial door closer.


The other advantage to a hydraulic door closer is you don't have to drill holes into the door for the door handle (little mass around mechanics) and latch (possibly where the seals are).

You put a vertical pull handle on one side with screws that don't go though the door, and nothing on the other side -- a combination that's obviously more air tight and even mass.


Heavy doors require, as you mentioned, heavy framing to hold them up. A warped wall or a warped door doesn't seal properly.

A 200 pound door that rips itself out of its frame and collapses is worse.

They also require hinges that can take the weight. Ball bearing hinges are popular.


> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24177507
> 
> 
> SAND.


Sand, in doors or walls, is good and bad, mostly bad.

It settles, which ends up causing the same kind of problem that NRC was worried about with insulation, a path around it.

It also is 'liquid', creating an outward force that'll be there forever, eventually breaking the door/wall at the bottom.

At resonance it liquefies, like Mexico City sand (soil) in an earthquake -- I've never seen STC measurements on this but I presume it's not a good thing.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24179655
> 
> 
> Sand, in doors or walls, is good and bad, mostly bad.
> 
> It settles, which ends up causing the same kind of problem that NRC was worried about with insulation, a path around it.
> 
> It also is 'liquid', creating an outward force that'll be there forever, eventually breaking the door/wall at the bottom.
> 
> At resonance it liquefies, like Mexico City sand (soil) in an earthquake -- I've never seen STC measurements on this but I presume it's not a good thing.



That is very interesting! I am unable to find a reference of dry sand liquefying, though -- the only references I'm seeing all refer to the water content of soil (e.g., like in clay) causing liquefaction of the sand at resonance. Presumably any sand used in a door would have minimal water content.


JH Brandt's design separates the sand into eight compartments of 13-3/4" x 17-3/8" x 1-1/2". Assuming a stated weight of dry sand being 100 lbs/cu ft, then each square would weigh 20.73lbs. I interpret the design to mean that the 2x2 frame + plywood is intended to each old 20 lbs. That seems well within the design limitations of 2x2 material. The entire door, then, would have a sand weight of 166 lbs.


Notably, that is very similar (maybe 20lbs more) than the sheet of lead that Gervais recommends. In fact, the end result of the two door constructions appear to be similar widths and very similar weights. The Gervais design would run upwards of $800 while the JH Brandt design would be far far less -- the sand would be between $10-15.


Completely ignoring any liquefaction concerns for the moment, it appears that the Brandt design is a far more economical way of achieving the same mass.


But let's not ignore liquefaction. In saying that I can't find references to it, I'm not in any way saying that I think you are wrong! I am now officially fascinated by the topic and would love to find out more.


----------



## BasementBob

Take concrete or steel.

(or Gervais's sheet lead)

Shape it into a column 8' tall and 1' diameter.

What happens?

It's so solid and unchanging that people make supports out of this stuff, even buildings thousands of feet tall.


Take play sand, or water.

Shape it into a column 8' tall and 1' diameter.

What happens?

The weight at the top pushes out the bottom. That downward force at the top, becomes a horizontal force near the bottom.

It's that horizontal force that has to be held in check.

That horizontal force is proportional to the height of the sand above it.

That horizontal force is there every moment of every day, forever.

With a hollow wooden door, that shrinks and contracts with every change of heat and humidity, is being reacted upon by this sand force, but unlike a floor which contracts back to the same place, the door is being held apart by the sand force, until the next expansion contraction phase, until eventually it splits and the sand pours out.

With a concrete block wall, with sand (not grout or poured concrete in the block holes), the same sort of thing happens. Its less force than freezing water, but its still there.


Seismic shaking can transform water-saturated sand into a liquid mass that will not support heavy loads such as buildings. This phenomenon, called liquefaction, causes much of the destruction associated with some earthquakes. Mexico City, for example, rests on the ancient lakebed of Lake Texcoco, which is a large basin filled with liquefiable sand and ground water. In the Mexico City earthquake of 1985, the wet sand beneath tall buildings liquefied and most of the 10,000 people who died were in buildings that collapsed as their foundations sank into liquefied sand.


hydrokinectic fusion (example by humor)
http://www.oocities.org/timessquare/dungeon/3459/watertrick.html


----------



## granroth

Those are very good points. I've now done more research on the topic and have, indeed, come across quite a few cases of people who build sand-filled doors and ran into the same issues as you describe are inevitable.


I did see at least one reference to building such a door but sealing everything with poly, first. The idea is that even when the wood expands, the poly will keep the sand from leaking. I don't see how that would solve the issue you bring up about the sand settling each time the wood expands, though. But let's look at how much the wood could expand. If we assume that we are using dimensional lumber made from Douglas Fir, then the expansion coefficient is 0.00267. If we assume a maximum moisture change of 10% throughout the year, then a 1-1/2" piece would expand a maximum of 0.04" or 1/25" -- roughly halfway between 1/16" and 1/32". In other words, not a lot. Not a lot is not nothing, though. If the sand was able to settle enough 1/25" every year, then it would take only about 6 years to expand by 1/4"; likely enough to cause structural problems. Hmm...


Okay, so you mention concrete and there are definitely concrete filled doors. Concrete is even denser than sand is similarly inexpensive (relatively speaking). It absolutely does not have the same issues with settling that sand will, since it's incredibly rigid. So if you made the same wood frame and then lined the cavities with poly (concrete is very wet and essentially stays wet forever), the wood would definitely be strong enough to hold it up and the poly would keep it from rotting from inside.


Now to brainstorm some potential problems. Concrete is rigid, but it does expand and contract. It does so mostly based on temperature, though, and the temperature in a house tends to be relatively stable. I wouldn't expect that the concrete would "move" all that much. The wood will still expand and contract, based largely on humidity. The concrete won't settle so it's just an issue of "gaps" -- which aren't big enough to cause any issues.


What are your thoughts on that? I haven't seen any examples (yet) of using concrete to fill cavities in a wood frame door (the doors are invariably steel). What else am I missing?


----------



## ECAV

Great thread here, I would like to hear more regarding the concrete door. What was the out come?


----------



## BasementBob

One would have to do something about the door handle,

but here's one way to do a concrete door.
http://www.sportsmansteelsafes.com/nbc_vault_doors.htm 
http://www.americanbombshelter.com/blast-door-single-leaf.html 

The steel door, with openings at the top, is shipped empty

and concrete poured in after its installed with a crane.

1400lbs Empty. 2500 Filled with local Concrete.



Steel fire doors are a lot lighter (up to around a mere 300 pounds), often filled with honeycomb or insulation. I thought there were some that were filled with a gypsum or grout or concrete like substance, but I can't find any today except from China.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24190128
> 
> 
> One would have to do something about the door handle,
> 
> but here's one way to do a concrete door.
> http://www.sportsmansteelsafes.com/nbc_vault_doors.htm
> http://www.americanbombshelter.com/blast-door-single-leaf.html
> 
> The steel door, with openings at the top, is shipped empty
> 
> and concrete poured in after its installed with a crane.
> 
> 1400lbs Empty. 2500 Filled with local Concrete.
> 
> 
> Steel fire doors are a lot lighter (up to around a mere 300 pounds), often filled with honeycomb or insulation. I thought there were some that were filled with a gypsum or grout or concrete like substance, but I can't find any today except from China.



Yeah, the option of buying a steel door and filling it with concrete is definitely a thing. As your links show, most seem to be concerned with security. I did find a few references to "normal" sized steel doors that can be concrete filled.


I think the outstanding question, though, is if it's possible to make a _wood-frame_ concrete-filled door. It would be very similar in theory to the sand-filled door, but since the concrete does not move (practically), it shouldn't have the same drawbacks. I went into a little more detail a couple posts above.


----------



## BasementBob

Density

MDF (medium density fiberboard) : 830 kg/m3

Concrete : 2,242 kg/m3

Lead : 11,350 kg/m3


----------



## granroth

Okay, so here's my thoughts on how you might construct a pretty massive wood-frame concrete-filled door. This is assuming a 32" x 80" door.


First, start with a layer of 1/4" ply then Green Glue then a layer of 3/4" MDF. On the bottom of this is an automatic door seal (I spec'ed a Zero International partial mortise).

 


Then, create a wood frame using 2x4s and 2x4s ripped in half (1-1/2" x 1-5/8", accounting for the width of the saw blade). This creates 8 cavities. Line the cavities with poly film and fill them with concrete. Let the concrete cure for at least a week.

 


Add another layer of poly and then a layer of 1/4" ply capped with a slightly smaller layer of 3/4" MDF.

 


Before getting to the specs, I wanted to cover a couple points. The slightly smaller layer of MDF is intended to create a "bank vault" effect, with staggered door seals. This double seal should do a fantastic job of blocking any air leakage. The Green Glue is important because mass without damping only covers half the battle. A quote from Ted White from another thread:


> Quote:
> Originally Posted by *Ted White*  /t/1294101/sound-resistant-doors/0_100#post_19568922
> 
> 
> The issue is more than just the mass, as a damping of that mass would improve things as well. So the combo of mass + damping would yield great results.
> 
> 
> 
> This assumes things are sealed up very well. The seals are always the weak link.



The 1/4" ply is there simply because this door is already quite thick. As I write that, I realize that it would make more sense to use two layers of 1/2" MDF than 1/4" Ply + 3/4" MDF. It would be more dense and damping works best with layers that have the same mass and density, anyway.


So what are we looking at?


This door is 3-1/2" thick (roughly twice the width of a standard door) and is massive. How massive?


Assume that MDF is 49 lbs cu ft; Plywood is 32 lbs cu ft; concrete is 133 lbs ct ft; and Douglas fir studs are 31 lbs cu ft. There are 0.731 cu ft of plywood, 2.122 cu ft of MDF, 0.662 cu ft of wood, and 1.56 cu ft of concrete. Do the calculations and you have a door that weighs *355 lbs!*


(Actually, it would be slightly more than that if you replace the plywood with MDF)


Is that enough?


Well, JH Brandt suggests that the door must have at least as much (and preferably) mass as your walls. If you assume that you have double walls with two layers of 5/8" drywall on each side and further assume that the insulation has negligible mass; the studs add only a little; and drywall is 2.2 lbs sq ft, then we have a mass of 8.8 lbs sq ft for the walls. Round up to 9 lbs, factoring in the studs.


Our door is 32" x 80", which is 17.8 sq ft. If we want our door to have at least as much mass as our walls, then it would need to be 17.8 x 9 = 160 lbs.


Our actual door is more than TWICE that massive. When you consider that it is also damped and fully sealed, then it's hard to imagine that this door wouldn't do a fantastic job of sound proofing.


Maybe too good, actually. Overkill is sometimes good, but exceeding the mass by that much might not be justified. That's a pretty extreme door.


I also have NO idea if it would actually work, since I haven't seen it done.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24192689
> 
> 
> Density
> 
> MDF (medium density fiberboard) : 830 kg/m3
> 
> Concrete : 2,242 kg/m3
> 
> Lead : 11,350 kg/m3



Heh, every single place that I've seen density numbers of materials have different numbers for everything. I'm honestly not even sure what people are measuring, if all measurements are different.


Anyway, lead is clearly far more massive than concrete, which is quite a bit more massive than MDF. Price definitely comes into play.


Let's see... a 32x80 door (like my concrete door example, above) is 17.8 sq ft. If I by that much 1/8" lead at $26 sq ft and 8 lbs sq ft, then I paid $463 for 142 lbs. But only 1/8" thick.


Assuming concrete is 133 lbs cu ft, then we'd need 1.068 cu ft to hit the same weight. Lead is 710 lbs cu ft, so the layer would have to be just over 5 times thicker or around 3/4" thick. That would cost around $10.


Assuming MDF is 47 lbs cu ft, then we'd need 3.021 cu ft. We'd need a layer 15 times thicker than lead, so 1-7/8" rounded to 2" thick. That'd be roughly two layers of 3/4" plus one 1/2". With the going price of MDF around here, the cost for 142 lbs would be (math math math) $55.


To sum up:


Concrete - 3/4" thick; $10

Lead - 1/8" thick; $463 (46x concrete)

MDF - 2" thick; $55 (5x concrete; 1/8x lead)


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24193348



Lead and MDF are also naturally flat, and handle flex problems forever without thought.



How do you guarantee:

a) no air gaps (triple leaf effect)

b) no flex problems (rattling piece of broken rock).


Possible remedies:


a) an excessive amount of PL Premium glue, all over the concrete and final wood layer. You can't use anything compressible like soft foam because that'll be a triple leaf effect. But anything rigid that fills the gap due to any inconsistency in the 'concrete' pour flush/level will be fine. If the gap were larger (1+ inches) I'd recommend expanding foam to couple the leaves, but I presume we're talking about errors and dips and possibly even stones, on the magnitude of 4mm.


b) Doors flex a lot. They flex by opening/twisting. They flex by impact. They warp/expand/contract by humidity and gravity. Even carrying it to install it it'll flex.

Concrete isn't good at flex. Concrete is often filled with rebar in three directions or jacketed by steel to avoid flex.

Perhaps if you drove screws through your wood, bed-of-nails style, every square inch, within 5mm of the depth of the cavity, so that the concrete would have something to hang on to.

2 1/4 inch screws, fully threaded (no shank). Perhaps drywall screws due to their wide thread. Although normally with concrete you'd want galvanized or the blue ones for concrete, here I don't think there are moisture or electrical problems (both of which contribute to rust), although there's still the intrinsic concrete alkalinity.

Just to be paranoid, you might throw in a bag of those glass fiber things (rebar replacement).



When you're talking about concrete, I presume you're talking about non-shrinking grout (e.g. Quikrete).

Or a self leveling and non-shrinking like Loctite® Fixmaster® Fast Set Grout.

In both cases it may take several applications to build it up, allowing time for each layer to fully set.



I don't think you need to worry about poly from a moisture point of view. Concrete in the ground wicks moisture and wood needs to be protected from that, but this door is suspended in the air -- it'll dry to the room's moisture within a few days. While its wet some types of wood would swell.

On the other hand, this guy did something similar, and used poly
http://www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=12664&start=105


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24193348
> 
> 
> JH Brandt suggests that the door must have at least as much (and preferably) mass as your walls.


Door same mass per square foot as walls. Sounds good to me.


By 'same' I mean: not larger, not much less.


----------



## BasementBob

Some comments on sand. Note 'avare' is a good fella.
http://www.gearslutz.com/board/studio-building-acoustics/291823-filling-hollow-door.html 



Two big acoustic doors

- 850,000 lb., 40’ x 60’ x 2’ concrete filled acoustical door

- 166,000 lb swing door with pneumatic seals, tested to 165 db at 35 and 50 Hz
http://www.appliedhandling.com/doors/specialty/


----------



## BasementBob

Here's a fella that poured concrete into the recess of a door
http://www.avsforum.com/t/1189103/the-take2-theater-design-build-thread/30


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24194048
> 
> 
> Here's a fella that poured concrete into the recess of a door
> http://www.avsforum.com/t/1189103/the-take2-theater-design-build-thread/30



I did see that earlier and even added it to the summary posts at the top of this thread. Curiously, though, I never correlated the "leveling compound" with "concrete". They are essentially the same, though, so I'm not sure what I was thinking.


So, cool, we do have a couple examples of concrete filled doors in the real world. At least in the Take2 case, it was a much thinner layer than the above plan, but the concept is the same. Neither builder appears to be active now, which is unfortunate, since I'd be very curious to see how they have held up over the past 3-4 years.


----------



## granroth

Where, exactly, does "sealing" fit in with regards to sound proofing? I'm talking about sealing the electrical outlets with putty; cracks with caulk; doors with auto-closers; etc. These are all very clearly recommended steps... but what are they specifically doing?


I ask from the perspective of the "four elements of soundproofing", as laid out by @Ted White and summarized in the first post of this thread. To wit, they are:

Decoupling
Adding Mass
Damping
Absorbing


Is there a fifth element called "Sealing" and, if so, where does it lie relative importance? If it's part of one of the existing elements, then which one and why?


----------



## BIGmouthinDC

A crack has no mass. Filler up.


----------



## granroth




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/0_100#post_24242495
> 
> 
> A crack has no mass. Filler up.



That makes sense. If you assume that air -- as a reference level -- has no mass, then adding caulk or putty or similar would increase it infinitely.


But that's just relatively speaking; the actual amount of mass added by sealing products is pretty minimal compared to what we are typically referring to by "adding mass". If we think about caulking the seam between the bottom plate of a wall and the floor and weighed the new bottom plate, I think we'd find that the additional weight from the caulk would be completely dwarfed by even the possible differences in the type of bottom plate used (pressure treated, douglas fir, whitewood, etc). Further, I don't recall ever reading about differences in mass, when it comes to sealing products.


So like I said, it does make sense that sealing is also adding mass, but considering the outsize impact that sealing has for such a little amount of product, I have a hard time reconciling that that's all that's going on.


----------



## BasementBob

Granroth:



BIGmouthinDC is correct when he answered your question about which of the four types of soundproofing would apply to holes, in that the answer is mass.


But your analysis is going the wrong way. The important part is not: adding mass to the wall relative to the walls mass.


The mass is what's used to resist the transfer of sound. If there's a path without resistance, then that's a significant transmission path.


If you have a source room (with a stereo), and a quiet room (with a bed),

and a wall of 100ft^2 between them that's 3' of solid concrete,

and there are no other flanking paths (ceiling/floor -- fiction but I'm simplifying),

and the stereo is played at 80dB at frequency F,

and the wall stops 90dB at frequency F,

then the sound heard in the quiet room is -10dB at frequency F, and -10dB you probably can not hear.


Now open up a six inch square hole in that wall connecting the two rooms.

So 99.5 ft ^2 is transmitting -10dB,

and that 0.25 ft^2 hole is transmitting 80dB.


Now let's convert that to energy, and back to dB.

-10dB * 99.5 = 0.1 * 99.5 = 9.95

80dB * 0.25 = 100000000 * 0.25 = 25,000,000

Add them together, 9.95 + 25,000,000 = 25,000,009.95

and divide by the total wall area 25,000,000 / 100 = 250,000

Which gives us 54dB at frequency F in the quiet room.

Which you will definitely hear.

(my math/physics are probably a little bit off in a couple of ways, but the idea is to add the energy)


Now, instead of a single 6"x6" hole, let's have that solid concrete wall, hovering in the air the way drywall attached to studs might, with a gap all the way around it that's the same area. The sort of gap around the edge of drywall that one might fill with acoustical caulking (because the building moves over time).

The 4 edges of the wall are 40' in length (10' x 10' wall). So a 0.1 inch gap all the way around would total over a 6" x 6" hole's area.

Same rules apply as the previous paragraph -- lots of noise goes through.

Technically it's a little lower than this, because the air in that tiny gap has more resistance/impedance than the single 6" x 6" hole.


Now fill that edge gap with acoustical caulking. That caulking is not a lot of mass relative to the 3' thick concrete wall, but its coupled with the massive wall, providing resistance/impedance to the sound wave. The actual relationship here is complex, but it's a lot more than air.


NRC had some statements about having electrical boxes back to back.

Brian has some interesting measurements about the effects of having electrical boxes back to back, and offset by a stud, and with and without putty packs -- as I recall back-to-back electrical boxes weren't as bad as he was expecting, but separating them and putty packs did help.


Of course you knew all that instinctively from experience -- I just gave you a little dB energy math, and asked you to think of a big hole as a long crack. When it's noisy outside, you close the window.


----------



## granroth

That was a very helpful post, Bob! I'll admit that I'm very familiar with the "long crack == big hole" scenario, as it's a very prevalent concept in heat transfer (insulation, etc). However, with regards to heat transfer, the hole needs to be plugged specifically because of the convective qualities of the air. Caulking will help a tiny bit with conductive heat transfer, but it's so little that it's not worth mentioning compared to the convective heat transfer savings.


The example may be the same but the reasons, it seems, are completely different. Sound doesn't travel convectively at all (that I know of) so there's no savings there. It's always about conductivity with sound.


Now if we look at the suggestion that a long gap is _strictly_ equivalent to a square hole, then I'd have a hard time swallowing that at face value. One could then imagine that the 6x6 hole was covered over with a 1/4" layer of caulk to be truly equivalent, and then a comparison of energy through that wall and that hole would show a drop in energy transfer compared to an empty hole, but since caulk has relatively low mass/density, I'd assume the drop would not be very significant.


Therefore, we'll treat the gap to hole analogy as a _logical_ comparison to indicate the scope of the problem. But in reality, the caulk is _extending_ the already massive wall (or door or whatever) and so it's impact is outsized.


If I interpreted all that right, then we're right on the same page.


----------



## BIGmouthinDC

Just to add an almost trivial part to this discussion, 5/8 firecode Drywall is about .027 lbs per cubic inch. USG brand acoustical caulk is .0519 in the tube. So relatively speaking caulk holds it own in the mass faceoff.


----------



## 30peppered

*Question:* This soundproofing neophyte could use some sage advice from the Grand Masters. Here's the skinny: we bought a home with a mostly finished basement apartment with 7 foot ceilings in said apt. Due to some incredibly poor workmanship in framing, we needed to open up half of the basement ceiling to reinforce floor joists.


1) To improve soundproofing, I am planning on adding R13 to the 2x8 floor joists then hanging 5/8 Quiet Rock. With no room for hat channel, does this make sense?


2) The primary basement bedroom is directly below a bathroom with tile flooring. With this bedroom ceiling currently open, does the installation of mass loaded vinyl prior to Quiet Rock add value?


3) The remaining basement ceiling with sheetrock intact is below a living area with hardwood laminate flooring. It will cut into the 7 ft ceiling height, but I was considering adding Quiet Rock here with green glue as a decoupler?


Any help is greatly appreciated~


----------



## joshp14

If using first layer OSB and second layer drywall, does one still need to worry about hitting the studs and channel with screws when hanging that second layer?


----------



## BasementBob




> Quote:
> Originally Posted by *30peppered*  /t/1509173/soundproofing-master-thread/30#post_24252023
> 
> 
> 7 foot ceilings in said apt. Due to some incredibly poor workmanship in framing, we needed to open up half of the basement ceiling to reinforce floor joists.
> 
> 
> 1) To improve soundproofing, I am planning on adding R13 to the 2x8 floor joists then hanging 5/8 Quiet Rock. With no room for hat channel, does this make sense?


Sounds like the best you can do.

Given that you have 2x8 floor joists (probably can't take more weight -- ask an engineer), as suggested by

the joists were probably damaged and presumably somewhat sistered as much as you're willing/able, and

a 7 foot ceiling (which eliminates lots of options) with building code limitations on required minimum height.


You might want to flip through these for ideas:
http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr219/rr219.pdf 
http://www.nrc-cnrc.gc.ca/ctu-sc/files/doc/ctu-sc/ctu-n35_eng.pdf 
http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir811/ir811.pdf 


> Quote:
> Originally Posted by *30peppered*  /t/1509173/soundproofing-master-thread/30#post_24252023
> 
> 
> 2) The primary basement bedroom is directly below a bathroom with tile flooring. With this bedroom ceiling currently open, does the installation of mass loaded vinyl prior to Quiet Rock add value?


Generally speaking, mass loaded vinyl is a waste of money. Just buy more drywall.


> Quote:
> Originally Posted by *30peppered*  /t/1509173/soundproofing-master-thread/30#post_24252023
> 
> 
> 3) The remaining basement ceiling with sheetrock intact is below a living area with hardwood laminate flooring. It will cut into the 7 ft ceiling height, but I was considering adding Quiet Rock here with green glue as a decoupler?


Green Glue is CLD (constrained layer damping -- absorbs sound by stretching and converting it to heat), not a decoupler.

Quiet Rock and Green Glue are mutually exclusive. If you're using Green Glue just use drywall. If you're using Quiet Rock then green glue is a waste of money. Quiet Rock has metal and CLD in it.


hmm. I haven't been to the Quiet Rock website in a couple of years. I see they now sell 1-3/8” thick Quiet Rock.


----------



## granroth




> Quote:
> Originally Posted by *joshp14*  /t/1509173/soundproofing-master-thread/0_100#post_24252809
> 
> 
> If using first layer OSB and second layer drywall, does one still need to worry about hitting the studs and channel with screws when hanging that second layer?



I'd be about 90% certain that the answer is that you can screw the second layer of drywall in anywhere, since you are using OSB. Curiously, though, I haven't tracked down anybody saying that _explicitly_. There's a lot of suggestions to that effect, though.


See some of the later posts in this thread: Does OSB seem all that less dense? . The strong implication is that they are installing the drywall without having to worry about screw placement.


But yeah, I'd like to get direct confirmation of that as well. The only non-ambiguous examples I've heard all center around attaching internal components and structures, not the drywall itself.


----------



## granroth




> Quote:
> Originally Posted by *30peppered*  /t/1509173/soundproofing-master-thread/0_100#post_24252023
> 
> *Question:* This soundproofing neophyte could use some sage advice from the Grand Masters. Here's the skinny: we bought a home with a mostly finished basement apartment with 7 foot ceilings in said apt. Due to some incredibly poor workmanship in framing, we needed to open up half of the basement ceiling to reinforce floor joists.
> 
> 
> 1) To improve soundproofing, I am planning on adding R13 to the 2x8 floor joists then hanging 5/8 Quiet Rock. With no room for hat channel, does this make sense?



The Soundproofing Company has a pretty good page on this topic and show several solutions:

Soundproof a Ceiling 


None of them will directly fit your situation, but if you combine some ideas, you can come up with a good approximation of some solutions. Some thoughts:


1. You might consider adding another layer of 5/8" drywall to the floor, between the joists, sandwiching Green Glue between the floor and drywall. This will give you some mass and damping, but without intruding on the ceiling height below

2. If you can spare another 5/8", then it would be a LOT cheaper to go with two layers of 5/8" Type X drywall with Green Glue, than a layer of Quick Rock. The performance would be very similar.


----------



## cw5billwade




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24176464
> 
> 
> Thank you for asking this question, because I'm going to have to do the _exact_ same thing in my theater. In my case, it's not a basement, but it is still two very large windows that cannot be permanently covered.
> 
> 
> The best build thread on a window plug that I've seen so far is in the Dark Knight Theater thread. Here's a link to the post with some details: The Dark Knight Theater - Window Plug Details Post
> 
> 
> I'm still searching for even more details on pros/cons and possibly other options, if they exist.


Check out my window plug http://www.avsforum.com/t/1468993/the-retirement-dream-home-theater/210#post_23740019


----------



## cw5billwade




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24193348
> 
> 
> Okay, so here's my thoughts on how you might construct a pretty massive wood-frame concrete-filled door. This is assuming a 32" x 80" door.
> 
> 
> First, start with a layer of 1/4" ply then Green Glue then a layer of 3/4" MDF. On the bottom of this is an automatic door seal (I spec'ed a Zero International partial mortise).
> 
> 
> 
> 
> Then, create a wood frame using 2x4s and 2x4s ripped in half (1-1/2" x 1-5/8", accounting for the width of the saw blade). This creates 8 cavities. Line the cavities with poly film and fill them with concrete. Let the concrete cure for at least a week.
> 
> 
> 
> 
> Add another layer of poly and then a layer of 1/4" ply capped with a slightly smaller layer of 3/4" MDF.
> 
> 
> 
> 
> Before getting to the specs, I wanted to cover a couple points. The slightly smaller layer of MDF is intended to create a "bank vault" effect, with staggered door seals. This double seal should do a fantastic job of blocking any air leakage. The Green Glue is important because mass without damping only covers half the battle. A quote from Ted White from another thread:
> 
> The 1/4" ply is there simply because this door is already quite thick. As I write that, I realize that it would make more sense to use two layers of 1/2" MDF than 1/4" Ply + 3/4" MDF. It would be more dense and damping works best with layers that have the same mass and density, anyway.
> 
> 
> So what are we looking at?
> 
> 
> This door is 3-1/2" thick (roughly twice the width of a standard door) and is massive. How massive?
> 
> 
> Assume that MDF is 49 lbs cu ft; Plywood is 32 lbs cu ft; concrete is 133 lbs ct ft; and Douglas fir studs are 31 lbs cu ft. There are 0.731 cu ft of plywood, 2.122 cu ft of MDF, 0.662 cu ft of wood, and 1.56 cu ft of concrete. Do the calculations and you have a door that weighs *355 lbs!*
> 
> 
> (Actually, it would be slightly more than that if you replace the plywood with MDF)
> 
> 
> Is that enough?
> 
> 
> Well, JH Brandt suggests that the door must have at least as much (and preferably) mass as your walls. If you assume that you have double walls with two layers of 5/8" drywall on each side and further assume that the insulation has negligible mass; the studs add only a little; and drywall is 2.2 lbs sq ft, then we have a mass of 8.8 lbs sq ft for the walls. Round up to 9 lbs, factoring in the studs.
> 
> 
> Our door is 32" x 80", which is 17.8 sq ft. If we want our door to have at least as much mass as our walls, then it would need to be 17.8 x 9 = 160 lbs.
> 
> 
> Our actual door is more than TWICE that massive. When you consider that it is also damped and fully sealed, then it's hard to imagine that this door wouldn't do a fantastic job of sound proofing.
> 
> 
> Maybe too good, actually. Overkill is sometimes good, but exceeding the mass by that much might not be justified. That's a pretty extreme door.
> 
> 
> I also have NO idea if it would actually work, since I haven't seen it done.


It took 3 men to carry my window plug up the steps from the garage. Better build that in place!







Check out stockmonkey200's door
http://www.avsforum.com/t/1314492/desert-sunset-theater-build/210#post_20588441


----------



## cw5billwade




> Quote:
> Originally Posted by *joshp14*  /t/1509173/soundproofing-master-thread/30#post_24252809
> 
> 
> If using first layer OSB and second layer drywall, does one still need to worry about hitting the studs and channel with screws when hanging that second layer?





> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24256979
> 
> 
> I'd be about 90% certain that the answer is that you can screw the second layer of drywall in anywhere, since you are using OSB. Curiously, though, I haven't tracked down anybody saying that _explicitly_. There's a lot of suggestions to that effect, though.
> 
> 
> See some of the later posts in this thread: Does OSB seem all that less dense? . The strong implication is that they are installing the drywall without having to worry about screw placement.
> 
> 
> But yeah, I'd like to get direct confirmation of that as well. The only non-ambiguous examples I've heard all center around attaching internal components and structures, not the drywall itself.


I was told by Ted White to hit the hat channel for the second layer. the weight of both sheets of materiel will be too much for the channel given the amount of screws you put in the first layer. You buy drywall screws for the metal channel in 2 lengths 1 1/2" for OSB layer and 2" for DW layer. Just use chalk and snap a line where your channel is on the OSB as you go and same for the Drywall. Comes in handy later when doing soffits and columns to also hit the channel. The more weight you have in the channel the better!


----------



## granroth




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/0_100#post_24258835
> 
> 
> Check out my window plug http://www.avsforum.com/t/1468993/the-retirement-dream-home-theater/210#post_23740019



Yep, your window plug is in the 'Notable Soundproofing Threads and Links' post (second post of this thread). I love it because it's such an extreme example!


----------



## granroth




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/0_100#post_24258891
> 
> 
> It took 3 men to carry my window plug up the steps from the garage. Better build that in place!
> 
> 
> 
> 
> 
> 
> 
> Check out stockmonkey200's door
> http://www.avsforum.com/t/1314492/desert-sunset-theater-build/210#post_20588441



Thanks, I updated the the Notable Links. That series of posts goes into a great level of practical detail.


----------



## granroth




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/0_100#post_24259003
> 
> 
> I was told by Ted White to hit the hat channel for the second layer. the weight of both sheets of materiel will be too much for the channel given the amount of screws you put in the first layer. You buy drywall screws for the metal channel in 2 lengths 1 1/2" for OSB layer and 2" for DW layer. Just use chalk and snap a line where your channel is on the OSB as you go and same for the Drywall.



Interesting! I guess the thinking is that X number of 1-1/2" drywalls screws can only hold Y lbs of weight and the combined total of OSB+DW exceeds that?


> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/0_100#post_24259003
> 
> 
> Comes in handy later when doing soffits and columns to also hit the channel. The more weight you have in the channel the better!



Mentioning soffits and columns, though, does directly conflict with my understanding of using OSB in the first place. The major reason stated for using OSB has always been that you can attach things like soffits and columns wherever you want and not have to worry about hitting the channels. If hitting the channels is still worthwhile, then there are _almost_ no benefits to using OSB as the first layer!


----------



## 30peppered

Thank you, I appreciate the feedback. I'm going with GG and 5/8 rock between joists after looking at the soundproofing link. You guys are great, thanks for the help~


----------



## BasementBob




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/60#post_24259003
> 
> 
> 
> I was told by Ted White to hit the hat channel for the second layer. the weight of both sheets of materiel will be too much for the channel given the amount of screws you put in the first layer. You buy drywall screws for the metal channel in 2 lengths 1 1/2" for OSB layer and 2" for DW layer. Just use chalk and snap a line where your channel is on the OSB as you go and same for the Drywall. Comes in handy later when doing soffits and columns to also hit the channel. The more weight you have in the channel the better!



Re the chalk line -- put marks on the perpendicular surfaces indicating where the channel is before you put the drywall up. (if it's a wall then the perpendicular surfaces the right angle walls; if it's a ceiling then the perpendicular surfaces would be the walls). This makes it easy/obvious/quick/idiot-proof to do a chalk line.


Re putting screws into the channel. Reminds me of the 1981 Hyatt Regency walkway collapse. The nuts were designed to hold a certain amount of weight, namely the entire walkway full of people jumping up and down to the music. But instead of running a single strong rod all the way down (original design), they used half length rods (actual construction). This meant that the upper deck nuts were holding double the weight, which they were not engineered to take, resulting in 111 immediate deaths, 3 more deaths a few days later, and 219 injuries.









from http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/60#post_24261387
> 
> 
> Interesting! I guess the thinking is that X number of 1-1/2" drywalls screws can only hold Y lbs of weight and the combined total of OSB+DW exceeds that?



I would imagine that it's a question of compressibility.


Steel is great under tension. Concrete is good under compression.

Imagine a twist tie. Tie a 1 pound weight to one end, and pull on the other end, and the 1 pound weight lifts. Now hold that twist tie vertically, and balance a 1 pound weight on the top -- the twist tie bends and the weight falls. Steel is great under tension, but lousy under compression.

Imagine a hollow cinder block (the kind with two holes, that round these parts they make public schools out of). Park a car on top of it, no problem. Tie a rope through one end of the cinder block, and another rope thorough the other hole down to the car, making the cinder block a chain link, and use a crane to lift the upper rope, and the cinder block snaps in two and the car falls. Concrete is great at compression, but lousy under tension.

(this compression tension bit is how rebar works in concrete floors and bridges, and why you put rebar at the bottom of the concrete floor because that's the part that stretches -- and stretching is tension, whereas the top of the floor is under compression when there is load)


Think of the shape of a screw. Its not the thread that holds the drywall in place, but the head of the screw compressing the gypsum.


Think of a screw driven into drywall. Now pull on that screw with 100 pounds of force, and the screw rips right out. That's because gypsum is lousy under tension.


Drive that same screw into steel, and the steel screw itself is great under tension, the screw head is acting on the drywall keeping the drywall under compression. How many screws have you seen made out of concrete, that are under tension load.


----------



## KNKKNK




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/60#post_24262639
> 
> 
> 
> Snip.....
> 
> 
> Think of a screw driven into drywall. Now pull on that screw with 100 pounds of force, and the screw rips right out. That's because gypsum is lousy under tension.
> 
> 
> Drive that same screw into steel, and the steel screw itself is great under tension, the screw head is acting on the drywall keeping the drywall under compression. How many screws have you seen made out of concrete, that are under tension load.



A few thoughts..


In this situation the "weak link" in the Clip/Channel/OSB/DW stack up is the pullout (tension) of the screw in the Very Thin (.018) 25 ga. channel. With an pull out under tension (ceiling) of ~ 130 lbs, (if using 20 ga channel the pullout jumps to ~ 280lbs.) Compared to wood (pine/fur) at approximately 3x this value.


These numbers were average ultimate's and did not include a safety factor, which would drop the operational values to ~ 60lbs of tension for the ceiling. Thus the recommendation for hitting the channels when installing the second layer if screw spacing is done per code.


Under shear (walls) the pull out of the screw from the channel is naturally higher (>500 lbs for 25ga) since the force is vertical and less of a concern than the ceiling. Oddly enough the shear values for 20 ga were lower than the 25 ga, I assume because some bending of the thinner channel happens before failure in this axis.


> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/30#post_24256979
> 
> 
> I'd be about 90% certain that the answer is that you can screw the second layer of drywall in anywhere, since you are using OSB. Curiously, though, I haven't tracked down anybody saying that _explicitly_. There's a lot of suggestions to that effect, though.
> 
> 
> See some of the later posts in this thread: Does OSB seem all that less dense? . The strong implication is that they are installing the drywall without having to worry about screw placement.
> 
> 
> But yeah, I'd like to get direct confirmation of that as well. The only non-ambiguous examples I've heard all center around attaching internal components and structures, not the drywall itself.



Now consider the pullout force of a #6 screw in 5/8 OSB is actually higher than it is in the channel at ~ 270 lbs. You are able to attach internal components securely with a osb/dw stack up but the weak link is again the number of screws holding the layers in the channel.. Personally if I wasn't going to hit the channel on the second layer I would double up on the screws in the first layer. Im talking about the overall attachment of the panels here and not necessarily the seams.. I don't believe it is necessary that the seams need to hit the channel on the second layer particularly if you used OSB on the first.


I would think that most people who have screwed OSB into hat channel will tell you that you need to press the panel to the channels to secure it, and you can not rely on the screw to pull it tight.. more times than not the screw will strip in the channel if your not pressing on the panel, over-driving the screw Ie.. trying to set the head into the OSB will also cause the screw to strip in the channel. This is just one indicator of the lower pull out force of the screw/channel compared to conventional framing.


Drive a screw into a piece of hat channel you'll be surprised how easily you can pull it out with a pair of pliers.


----------



## cw5billwade




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/60#post_24261387
> 
> 
> Interesting! I guess the thinking is that X number of 1-1/2" drywalls screws can only hold Y lbs of weight and the combined total of OSB+DW exceeds that?
> 
> Mentioning soffits and columns, though, does directly conflict with my understanding of using OSB in the first place. The major reason stated for using OSB has always been that you can attach things like soffits and columns wherever you want and not have to worry about hitting the channels. If hitting the channels is still worthwhile, then there are _almost_ no benefits to using OSB as the first layer!


that is correct but it is best is to plan your soffits to hit a hat channel. I knew I wanted 12" deep soffits so I added an additional Hat channel in that location. Also since I snapped a chalk line where the hat channel was when the soffit was perpendicular I put the screw on the line. you can tell a difference when the screw hits channel and just OSB it is just not as firm in OSB only. That being said there were manny times on the second layer of drywall a piece did not end on a channel do to over lapping the edges. Then the OSB is really great. same with my coffers most of them did not hit channel. For the columns I just screwed where ever I needed to.


----------



## cw5billwade




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/60#post_24261327
> 
> 
> Yep, your window plug is in the 'Notable Soundproofing Threads and Links' post (second post of this thread). I love it because it's such an extreme example!


I updated the thread prior to the window plug to better explain how I did the window frame and sill to keep them decoupled.


----------



## cw5billwade




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/60#post_24262616
> 
> 
> Re the chalk line -- put marks on the perpendicular surfaces indicating where the channel is before you put the drywall up. (if it's a wall then the perpendicular surfaces the right angle walls; if it's a ceiling then the perpendicular surfaces would be the walls). This makes it easy/obvious/quick/idiot-proof to do a chalk line.


Yes I put the piece 6 inch from corner than snapped a line across it centered on the hat channel then slide piece into place and screwed it in. Next piece snap line etc. Same with dry wall. then you always know where the channel is.


----------



## cw5billwade




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/60#post_24262639
> 
> 
> I would imagine that it's a question of compressibility.
> 
> 
> Steel is great under tension. Concrete is good under compression.
> 
> Imagine a twist tie. Tie a 1 pound weight to one end, and pull on the other end, and the 1 pound weight lifts. Now hold that twist tie vertically, and balance a 1 pound weight on the top -- the twist tie bends and the weight falls. Steel is great under tension, but lousy under compression.
> 
> Imagine a hollow cinder block (the kind with two holes, that round these parts they make public schools out of). Park a car on top of it, no problem. Tie a rope through one end of the cinder block, and another rope thorough the other hole down to the car, making the cinder block a chain link, and use a crane to lift the upper rope, and the cinder block snaps in two and the car falls. Concrete is great at compression, but lousy under tension.
> 
> (this compression tension bit is how rebar works in concrete floors and bridges, and why you put rebar at the bottom of the concrete floor because that's the part that stretches -- and stretching is tension, whereas the top of the floor is under compression when there is load)
> 
> 
> Think of the shape of a screw. Its not the thread that holds the drywall in place, but the head of the screw compressing the gypsum.
> 
> 
> Think of a screw driven into drywall. Now pull on that screw with 100 pounds of force, and the screw rips right out. That's because gypsum is lousy under tension.
> 
> 
> Drive that same screw into steel, and the steel screw itself is great under tension, the screw head is acting on the drywall keeping the drywall under compression. How many screws have you seen made out of concrete, that are under tension load.



More like you put about 21 screws per 4x8 sheet which holds the weight of the OSB no issues. Hat channel is thin. If you screw to tight the channel will lose and screw just spins and pops back out. It took a few until I learned the pressure required and when to stop screwing to prevent it from popping the channel. So given the 21 screws holding the OSB now add the weight of the dry wall without hitting the channel and the channel will lose. Always best to hit the channel when you can. I had some drywall edges where I had to just hit the OSB because it did not hit a channel but that is 5 screws out of the 20 so no biggie.


----------



## cw5billwade




> Quote:
> Originally Posted by *KNKKNK*  /t/1509173/soundproofing-master-thread/60#post_24264165
> 
> 
> A few thoughts..
> 
> 
> In this situation the "weak link" in the Clip/Channel/OSB/DW stack up is the pullout (tension) of the screw in the Very Thin (.018) 25 ga. channel. With an pull out under tension (ceiling) of ~ 130 lbs, (if using 20 ga channel the pullout jumps to ~ 280lbs.) Compared to wood (pine/fur) at approximately 3x this value.
> 
> 
> These numbers were average ultimate's and did not include a safety factor, which would drop the operational values to ~ 60lbs of tension for the ceiling. Thus the recommendation for hitting the channels when installing the second layer if screw spacing is done per code.
> 
> 
> Under shear (walls) the pull out of the screw from the channel is naturally higher (>500 lbs for 25ga) since the force is vertical and less of a concern than the ceiling. Oddly enough the shear values for 20 ga were lower than the 25 ga, I assume because some bending of the thinner channel happens before failure in this axis.
> 
> Now consider the pullout force of a #6 screw in 5/8 OSB is actually higher than it is in the channel at ~ 270 lbs. You are able to attach internal components securely with a osb/dw stack up but the weak link is again the number of screws holding the layers in the channel.. Personally if I wasn't going to hit the channel on the second layer I would double up on the screws in the first layer. Im talking about the overall attachment of the panels here and not necessarily the seams.. I don't believe it is necessary that the seams need to hit the channel on the second layer particularly if you used OSB on the first.
> 
> 
> I would think that most people who have screwed OSB into hat channel will tell you that you need to press the panel to the channels to secure it, and you can not rely on the screw to pull it tight.. more times than not the screw will strip in the channel if your not pressing on the panel, over-driving the screw Ie.. trying to set the head into the OSB will also cause the screw to strip in the channel. This is just one indicator of the lower pull out force of the screw/channel compared to conventional framing.
> 
> 
> Drive a screw into a piece of hat channel you'll be surprised how easily you can pull it out with a pair of pliers.


+1


----------



## granroth

I want to talk about sealants a bit. We've already established in this thread that sealants are essentially a part of the damping process, but haven't really discussed what kind of sealants are necessary. The most common suggestion is to use a dedicated acoustic caulk like SilenSeal. But does that do a testably better job than "normal "caulk"? Here's a quote from @Ted White from a different thread:


> Quote:
> Originally Posted by *Ted White*  /t/1450185/understanding-sound-damping-with-green-glue/#post_22804701
> 
> 
> Sealant primarily seals for air penetration. Let's establish that.
> 
> 
> No lab has ever, nor will likely ever, test such a nuance, so we can mentally spin this for years.
> 
> 
> 15 years ago, people used fiberglass instead of damping compound in a similar application and sealant was used at the edge of the drywall.
> 
> 
> When this technique was adapted using damping compound, the use of sealant at the edge of the drywall was maintained. The thought at the time was that the sealant helped to bond the system together, allowing the floor being treated to act more as a single layer, rather than many sections.
> 
> 
> I simply don't believe that happens to any significant extent, and because we don't promote products that don't have a clearly defined advantage, we don't promote sealant use any longer in this specific application. I've thought about this for years, have yet to see any data or theory that refutes my position, so we don't advocate the sealant, and are in the process of pulling the sealant reference from our illustrations.
> 
> 
> Keep in mind we sell sealant, and we are not recommending it in this application. Certainly no harm in using it.



And in the same thread, comes the suggestion that standard "50 year caulk" works just as well:


> Quote:
> Originally Posted by *tlogan6797*  /t/1450185/understanding-sound-damping-with-green-glue/#post_22795268
> 
> 
> Unless something has changed in the, ah, umm, SEVEN years since I've been working on my room, regular old 50-year caulk works as well as "acoustic sealant."



But like I said, the majority of talk about products like SilenSeal is that it's necessary and worth the extra cost (at least twice, based on some quick research).


What are people's thoughts on that? Is there some solid reasoning or evidence that suggests that the dedicated acoustic sealants are worth the extra money?


----------



## BasementBob

50-year-caulk

is

acoustic sealant.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24312974
> 
> 
> 50-year-caulk
> 
> is
> 
> acoustic sealant.



Okay. It's not advertised as such. I was looking at DAP Dynaflex 230, which claims to be permanently flexible and with a 50 year guarantee. Nowhere in any of their product descriptions do they mention its use as an acoustic sealant: http://www.dap.com/product_details.aspx?BrandID=14&SubcatID=3 


I say that, because products like SilenSeal, QuietSeal, and Quiet Zone are _specifically_ sold as being an acoustic sealant... and with a price to match.


I feel like I'm missing a key bit of info, here. What is it?


----------



## brwsaw

My contractor used PL400 between the layers of 5/8" drywall without discussing it with me.

I'd assume this is the exact opposite of what you want.

Please clarify.

I'd add I'm now considering a third layer and two tubes green glue per sheet.


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/60#post_24313140
> 
> 
> I was looking at DAP Dynaflex 230, which claims to be permanently flexible and with a 50 year guarantee. Nowhere in any of their product descriptions do they mention its use as an acoustic sealant: http://www.dap.com/product_details.aspx?BrandID=14&SubcatID=3


I don't know about that one.

I usually look for "acoustical" or "butyl".

The cheapest used to be "USB Acoustical Sealant" .


An old thread, listing a bunch of caulk available at the time:
http://www.avsforum.com/t/765365/who-makes-acoustical-caulk#post_9123992


----------



## BasementBob




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/60#post_24313313
> 
> 
> My contractor used PL400 between the layers of 5/8" drywall without discussing it with me.
> 
> I'd assume this is the exact opposite of what you want.


I vaguely remember some experiments about this -- using glue to increase the stiffness of the wall.

I don't recall if it lowered the coincidence dip frequency (not good), or made no difference whatsoever (waste of money).

I think there was a theoretical drop in coincidence dip frequency, and a drop of about 2 STC points in STC50-STC60 walls, when gluing a wall with a traditional adhesive (PL Premium, Liquid Nails, contact cement).

In any event I don't think it's a crisis.


Green Glue is much better (good), because green glue lowers the resonance dip and coincidence dip amplitude, via damping.


----------



## brwsaw




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/60#post_24313682
> 
> 
> I vaguely remember some experiments about this -- using glue to increase the stiffness of the wall.
> 
> I don't recall if it lowered the coincidence dip frequency (not good), or made no difference whatsoever (waste of money).
> 
> I think there was a theoretical drop in coincidence dip frequency, and a drop of about 2 STC points in STC50-STC60 walls, when gluing a wall with a traditional adhesive (PL Premium, Liquid Nails, contact cement).
> 
> In any event I don't think it's a crisis.
> 
> 
> Green Glue is much better (good), because green glue lowers the resonance dip and coincidence dip amplitude, via damping.



Well, crisis or not the drywall is up so it is what it is.

All things considered I just want to get into the room.


----------



## cw5billwade

I went through two cases of acoustical caulk purchased from the building supply company drywall division my builder used. The running joke during my build if we did not cut something as accurate as we would like was "nothing that caulk wouldn't fix"
http://www.avsforum.com/t/1468993/the-retirement-dream-home-theater/30#post_23281085 
http://s629.photobucket.com/user/cw5billwade/media/theater/20130505_114741.jpg.html  

you can see front side of tube in this shot
http://s629.photobucket.com/user/cw5billwade/media/theater/20130516_125119.jpg.html  

I also insured that my drywall and OSB on the walls were sitting on the pink 1/8” thick roll of insulation designed to go under the wall plate to decouple the floor from the walls. Which I then trimmed after the drywall was in and then caulked between floor and drywall. I also caulked every hole that a wire came through just not shown here. These wires actually went into the stage so never really entered the room so to speak but I still caulked them.
http://s629.photobucket.com/user/cw5billwade/media/theater/20130527_200025.jpg.html  

I also caulked below in the garage. Basically if there was a crack or hole there was caulk in it. If I drilled any size hole for some CAT 6 or 12 GA or speaker wire caulk from both sides. I caulked between the sheets of OSB on the walls, ceiling and flooring. I actually ran a line of caulk in the grove of the second layer of 3/4" T&G flooring as seen in the link below. Everything and anything I did I put in the caulk. For the price I figured why not. Did it help I don’t know but I do know the sound proofing in my room is outstanding. Just have to finish the door.
 

Someone asked me in my build about sound proofing my floor since I am on second floor here is my summary
http://www.avsforum.com/t/1468993/the-retirement-dream-home-theater/330#post_24276518


----------



## cgott42

Amazing thread, thanks for your work - much appreciated. TU


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24313651
> 
> http://www.avsforum.com/t/765365/who-makes-acoustical-caulk#post_9123992



Oh, sweet! Tons of great info in your post and also in the rest of that thread.


Let me summarize: when we refer to acoustical caulk, we are mostly referring to caulk that will not shrink over time. This is where the "50 year caulk" comes into play -- those types of caulk are guaranteed to not shrink for 50 years, which is as good as it's going to get. Why don't we want it to shrink? Because if it does, then now we've lost the entire advantage of caulking in the first place, since there is now a gap where there wasn't before! There's nothing really magical about "acoustical caulk" other than the ability to not shrink.


I'm going to quote this post, because it's right to the point and is far more persuasive than I could ever be:


> Quote:
> Originally Posted by *Brian Ravnaas*  /t/765365/who-makes-acoustical-caulk/0_100#post_10271828
> 
> 
> Tremco Acoustic sealant is generally available locally and is really flexible, gooey, oozy, stretchy, and all of those. Its solvent based and harder to work with as its tough to squeeze out of the tubes. From a theoretical-properties standpoint, its probably the best widely available acoustical sealant. Its 6 bucks or so in 29 oz tubes here.
> 
> 
> 
> The USG sealant is easier to work with and water based and generally a little cheaper. Other sealants are available as well in both solvent and water based, i certainly am not intimately familiar with them all and could not say "best, next best, worst, etc."
> 
> 
> 
> a lot of 50 year caulks are more flexible than a lot of water based "acoustical sealants", and in general latex sealants do contain the heavy fillers that are advantageous when covering large cracks, etc.
> 
> 
> 
> Sealants can, if their properties are right, add a bit of damping to a wall. Not enough to matter much, just a tiny bit at the coincidence dip, which for theater construction shouldn't be the primary concern. In a wall with even the tiniest dab of Green Glue, this small amount of damping doesn't mean anything because the GG supplies much more than any caulk to hope to.
> 
> 
> 
> On walls where drywall is screwed right up to the studs, the flexibility of the sealant won't have much effect on the behavior at all because the edge of the drywall is already rigidly constrained by the screws.
> 
> 
> 
> On walls - clips and resilient channel - where one edge of the wall is "free" to move, a more flexible sealant may (or may not, i've never seen a test to outline this) have advantages.
> 
> 
> 
> The most important thing is that you seal the wall. I can't imagine any situation where i'd be happier with 1 bead of an esoteric (often just repackaged name-brand stuff with a new label) sealant -vs- 3 of something cheap. Better yet, 5 of something really cheap.
> 
> 
> 
> A seal is 10^90th important, but how one attains it on the vast majority of walls is far less important.
> 
> 
> 
> GGCos recommendations are just based on our experiences in field and lab tests and permusing what precious little data we have ever found. USG once compared their sealant to a very ideal putty type material, and found essentially no difference save at the high frequency end of things at the coincidence dip.



Later on, Brian says "I don't feel that all of the acoustical sealants sold necessarily have any advantage over normal old boring caulks available everywhere" and finishes with "You folks can hold me to that when the day comes that GGCo releases a sealant.". I find that a little funny because doesn't GGCo produce SilenSeal? After Brian sold it, likely.


Anyway, part of my reasons for being so curious about it (other than being a very curious fellow by nature) is that acoustical caulk seemed to be so much more expensive than "normal" caulk. Bob, your post showed that that's not necessarily true. I did some searches for OSI SC-175 and discovered that Home Depot is selling cases online for 23 cents per ounce. That's _half_ the cost of the DAP caulk I linked to earlier. Not bad at all!


----------



## granroth




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/0_100#post_24315043
> 
> 
> I went through two cases of acoustical caulk purchased from the building supply company drywall division my builder used. The running joke during my build if we did not cut something as accurate as we would like was "nothing that caulk wouldn't fix"



I've often said, "the world is built on caulk and shims." Heh.


> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/0_100#post_24315043
> 
> 
> Someone asked me in my build about sound proofing my floor since I am on second floor here is my summary
> http://www.avsforum.com/t/1468993/the-retirement-dream-home-theater/330#post_24276518



That's great! That goes really well with the above discussion on soundproofing a floor from below. You are nailing down how to do it when you have access above.


----------



## brwsaw

I'm curious about something you might be able to answer.

My local supply guy asked me to consider using drywall in the T bar instead of the panels.

While considering it I though about the potential for drywall dust falling once installed and wondered about using an acoustic caulk around each edge to seal the seams (lift the panel, caulk around the topside of the lip, set the panel back down, tape all pieces first if necessary).

I'm pretty sure I don't want to go with the drywall in the T bar option (5/8" drywall is about a third of the cost and weighs more) but am still wondering about the potential of the acoustic sealant between the T bar and ceiling tile.

Is it worth while and would you do it? If you were in my position (not being able to hang drywall from the ceiling) which would you have installed?


----------



## BasementBob

brwsaw:


By 't bar' I presume you mean ceiling t-bar, used to hang acoustic ceiling tiles.


I don't know of anyone who's tried to do soundproofing with t-bar.


I'd be concerned that:

- the t-bar isn't strong enough for drywall. Home Depot's are probably not designed for that kind of weight. If it didn't break outright, the wire holding it up might unravel. There is t-bar on the market that's designed for drywall, usually thicker and I think with nail mounts rather than wire ties holding it up.

- to get the drywall up there, you need a bit of room around the drywall. Seems to me that air gap, and the steel t-bar itself, would allow noise to go through, negating much of the benefit of the drywall from a sound transmission loss point of view.


I'm reminded of the rule of thumb in the sound isolation world: "if you're inventing it, it's probably wrong."

Stick with what people with hundred million dollar research labs have tested and approved, and do it that way. If you're going to put drywall on the ceiling, screw it and green glue it. (maybe with room-in-a-room, or RSIC-1 clips)


If your t-bar panels are mostly (80% of them) light acoustic panels (possibly with R13 fluffy fiberglass above a rigid fiberglass panel) for absorption reasons, and you have a couple of drywall reflector panels for different acoustic reasons, that's one thing. But if your doing this for soundproofing, I'd stick with 4'x8' drywall panels and something traditional to hold them up with -- but you intimated that you're unable to do that for some reason.


The traditional reasons for going with t-bar is for

- acoustical absorption, and/or

- access to what's above the t-bar (pipes/wires/hvac, shut off valves, junction boxes), and/or

- quick installation


----------



## brwsaw

Yep and yep.

Low ceiling, heavy foot steps above, plumbing etc.

I've been told drywall is used in commercial installations in t-bar grids.

I'm set against it, was curious about the potential benefits of adding the acoustic caulk.

I will have 2 air gaps, 1 x 2" above the t-bar and 1 x 3" between batts of 3" insulation.

Sound proof is not possible, less sound transfer was the goal.

I measured the sound transfer between all the rooms before we installed the insulation and will re run the same tests after the T bar is installed.

It just has to be better than it was.

For another $100 bucks, if it would make any difference what so ever I would just do it (all edges, all tiles). No difference, I won't bother.

Now my next room will be much larger/taller and will be a room with in a room.

For now I'm stuck with the room I am fondly calling the "penalty box", when the wife says to go away, nuff said...gone.


----------



## cw5billwade




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/60#post_24318521
> 
> 
> I'm curious about something you might be able to answer.
> 
> My local supply guy asked me to consider using drywall in the T bar instead of the panels.
> 
> While considering it I though about the potential for drywall dust falling once installed and wondered about using an acoustic caulk around each edge to seal the seams (lift the panel, caulk around the topside of the lip, set the panel back down, tape all pieces first if necessary).
> 
> I'm pretty sure I don't want to go with the drywall in the T bar option (5/8" drywall is about a third of the cost and weighs more) but am still wondering about the potential of the acoustic sealant between the T bar and ceiling tile.
> 
> Is it worth while and would you do it? If you were in my position (not being able to hang drywall from the ceiling) which would you have installed?


If you are looking for sound proofing this guy is not telling you correct information and apparently does not know what he is talking. check the information on soundproofingcompany.com. Whisper clips or the cheaper IB-1 clips like I used with hat channel and 5/8" DW/GG/DW or OSB/GG/DW like I used is the recommended practice. If you have a lower ceiling you can put braces between the rafters so that the clips and hat channel are installed on the braces running parallel to the rafters with the hat channel now 1/4" lower than the rafter vise 2". save you some height but not sure it is worth it unless 7' or lower ceiling.


----------



## brwsaw

It really comes down to I don't trust the clips with the weight of two layers of drywall (if we're doing it, it would be doubled up)

Just picture you're sitting in your room half cut watching your favorite bomb run or gun fight and bammm you're in the scene, literally.

T bar goes up in 2 days.


----------



## BIGmouthinDC

I have yet to hear of a single incident of the failure of a clup and channel ceiling. Just follow the recommended spacing.


If I was at home I would post the picture of Ted White hanging between two clips.


The probability of being killed in a car accident is far greater than the drywall failing. T bar is not engineered for the weight of drywall.


----------



## granroth

BIG must be referring to this:











(From http://www.avsforum.com/t/1464536/beam-and-pole-interruptus-not-bigmouthindc-and-nygiantsfan23-launch-the-rawlinsway-theater/#post_23320844 )


----------



## brwsaw

Its all good. Thanks though.

T bars paid for and will be onsite tomorrow.

Next time.


----------



## granroth

So if you're definitively going with T-bars and acoustic ceiling tile, then it's an interesting question if sealing the edges with acoustic caulk would make an appreciable difference. I'm far from an expert (as is evidenced in this thread), so I'm going to just surmise out loud.


Ceiling tiles hang loose in the t-bar, traditionally. During a movie with any decent sound (especially loud bass), the t-bar will vibrate like mad. I can attest that when I fired up a subwoofer in the very un-controlled space of my living room, every single picture and hanging item in the room buzzed with every "boom" -- the vibration was very obvious.


Presumably the ceiling tile won't "buzz", due to the material it's made of. But it will still vibrate and I'm wondering if that vibration will cause the t-bar to vibrate even more. It makes sense that that vibration would allow air to pass and air loss == sound propagation.


Now let's assume you lay down a bed of acoustic caulk and set the ceiling tile in it. This essentially creates a damping layer right there and seals it from any air loss. I'd be very surprised if it didn't do anything, since it's creating a sealed and dampened layer that wasn't there before.


The question that I can't begin to answer is how much of a difference it would make. Would it be noticeable? No idea.


----------



## brwsaw

Yep.

Still hung up.

It would be a pile of work at awkward angles but the idea has a tiny bit of potential.

Were painting the tile and had planned on painting the t bar as well.

I'm now thinking the t bar should stay white just in case.

The fire rated tile weighs quite a bit. I doubt I have to worry about vibrations with my current subs. I actually hope your right though, that's one problem I'd be happy to have.

I'll know in about a week, I don't see placing my equipment any sooner.


----------



## cw5billwade

Are you putting R19 insulation between the joists? prior to installing the tile? That would help as well.


----------



## brwsaw

I had a layer of Safe and Sound installed tight to the sub floor and had a second layer added at the bottom of the 9 1/2 joist. I'd stressed the importance of the gap between the batts and the guys really came through.

I was being realistic when we started, knowing it wouldn't be sound proof. I'm hoping for 50% reduction but don't think we'll get there. Another week or so and I'll know.

FWIW the main goal wasn't to stop sound going up so much as it was to stop it from effecting the weight bearing wall down the middle of the home. This would travel through the entire home. I think the two insulated walls with the 2-3" average air gap should work pretty well here.


----------



## dsteak

Is there such a thing as overdoing it? I'm not sure how to ask the question specifically, but my builder wants to cover all of my walls (screen wall, side walls, and rear walls) with a Whisper Walls system and ceiling treatments. Inside the walls and ceiling I already have Dynil installed. Will these a create a "too dead" environment?


----------



## BasementBob




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/90#post_24324300
> 
> 
> I had a layer of Safe and Sound installed tight to the sub floor and had a second layer added at the bottom of the 9 1/2 joist. I'd stressed the importance of the gap between the batts and the guys really came through.


One layer of batts probably would have been fine.


----------



## brwsaw

I know, but for the cost and time involved I figured it shouldn't hurt either.

The biggest consideration is I was hoping to stop the direct foot fall sound a bit, another reason I didn't want drywall on the ceiling ( sound transfer through the joist).

I'd agree with a bit more home work and a bit more planning the suspended clipped ceiling would have been way better.


----------



## BasementBob




> Quote:
> Originally Posted by *dsteak*  /t/1509173/soundproofing-master-thread/90#post_24324922
> 
> 
> Is there such a thing as overdoing it? I'm not sure how to ask the question specifically, but my builder wants to cover all of my walls (screen wall, side walls, and rear walls) with a Whisper Walls system and ceiling treatments. Inside the walls and ceiling I already have Dynil installed. Will these a create a "too dead" environment?



Some poor guesses:


I presume that Dynil is 'Mass Loaded Vinyl'. Most times that's placed behind drywall, for sound transmission (room to room noise). I have a feeling you didn't put it behind drywall.


Whisper Walls remind me of the "Owens Corning Basement Finishing System". The Owens is R11 insulation everywhere, which is both not deep enough and too much area, giving two types of home theatre acoustical problems (dead at mid/high frequencies, still has room modes).


If your Whisper Walls are just absorption, then that would the same kind of bad as Owens. If you mix absorption, reflection, and diffusive behind, *or in front of*, those panels in the correct proportions and at the correct places, then that's better. Whisper Walls absorption seems to come in various thicknesses, the max being 2". I don't know if you can have a 2" air gap behind that, which would help, but it looks to me that they flush screw it to the wall -- it might be better to screw it to studs to get some more depth behind it.

The absorption coefficients for the 2" system are at
http://www.whisperwalls.com/testing_gs/pdf/Acoustical_-_Type_A_-_WhisperSpan_2_inch.pdf 

I don't see absorption coefficients for just the fabric only, without insulation.


What's he doing on the ceiling? More Whisper Ceiling ?


I vaguely remember a design where the walls from floor to 1' below ear level were covered in absorption, and a ring 1' below ear level to the ceiling were reflective. Might have been one of Denis Erskine's.


Nonetheless its better than carpet.


----------



## dsteak

Yes, Dynil is the same stuff they put in car doors. It's behind my dry wall, stapled to the joists. The goal was to stop as much sound from traveling upstairs (from the basement) as possible and to block the furnace noise coming from the other side of the basement. The room is sealed off with sliding doors that have been acoustically treated, but...


The room is somewhat echo-y as you can hear reverberations when speaking, whistling, etc. It's also rather small, 13x16x7.5. He wants to use 1" thick. In between the 60" wide fabric wrapped whisper panels would be a 2" wood panel to mount sconces on, and wooden flutter echo treatments in place of acoustic backing. On the ceiling he wants to put a 6'x4' acoustic treatment (cloud) front center, between the center channel and the listening positions.


Would I just be better off with strategically placed Acoustic Treatments than doing the entire room floor to ceiling? I have to read more about absorption, reflection, and diffusion.


Thanks so much for the response, I really appreciate it.


----------



## rabindu

We're building a new house, and I have the good fortune of being "allowed" a 24x18x12 media/family room. I'm planning to go the distance building a room within a room with hat channel/green glue/DD/ separate HVAC run. The problem is, along the perimeter wall, my wife wants windows! Not big windows, but she insists on some natural light. How am I going to accomplish a high STC rating if I have 2-3 gaping holes in all my hard work? I've tried researching all over the net, but I can't seem to find anything that isn't about blocking sound out. I'm not concerned about outside noise coming in. I want to prevent the theater noise from getiing to the rest of the house. Is this a solvable problem? Thanks, in advance, for any advice.


----------



## granroth




> Quote:
> Originally Posted by *rabindu*  /t/1509173/soundproofing-master-thread/100_100#post_24334792
> 
> 
> We're building a new house, and I have the good fortune of being "allowed" a 24x18x12 media/family room. I'm planning to go the distance building a room within a room with hat channel/green glue/DD/ separate HVAC run. The problem is, along the perimeter wall, my wife wants windows! Not big windows, but she insists on some natural light. How am I going to accomplish a high STC rating if I have 2-3 gaping holes in all my hard work? I've tried researching all over the net, but I can't seem to find anything that isn't about blocking sound out. I'm not concerned about outside noise coming in. I want to prevent the theater noise from getiing to the rest of the house. Is this a solvable problem? Thanks, in advance, for any advice.



To start, if you are doing a true room-within-a-room, then there's no need for hat channel. The interior walls already give the coupling that the hat channel and clips would accomplish -- and they do a better job of it, too.


Dealing with windows (that must remain windows) in a theater is relatively common. The two ways that they are typically dealt with is to either hang thick drapes or to create a window plug.


Thick drapes are surprisingly effective for how simple they are. If your primary concern is not incoming noise but outgoing noise leaking back into the house, then drapes might be all that you need. The sound is already going to be muted quite a bit by the distance outside and the little extra damping done by the drapes might be good enough.


That said, the drapes themselves do not have a great STC rating. For that, you're going to need to create a custom "plug" for the window. See post 2 in this thread for a couple links to building your own plug: Notable Soundproofing Threads and Links . There is also a small discussion on the topic in this thread starting at post 31.


The advantage of a plug is that it offers fantastic sound proofing, while still being removable when you aren't watching a movie.


----------



## rabindu

Really..........that's some good info about the hat channel. Thank you. As for the ceiling, they would still be required? Or would you think floating joists would be the better way to go?


----------



## granroth

If you have room for floating joists, then they are definitely the way to go. And no, hat channels would not be necessary on the ceiling, either.


Think of it this way. The goal for 'inner walls and ceilings' and for channels and clips are the same. In both cases, they are breaking the most reactive sound paths and forcing the sound to convert to another form to get to the next stage in the construction. This takes energy, which reduces the volume of the sound as it goes. Clips work by "buffering" the vibrations through a non-rigid layer.


BUT, it's not a perfect system, since there is still a physical connection between the drywall and the studs. It's a pretty decent connection, as far as physical connections go... but still a connection.


Compare that to a room-within-a-room with inner walls and floating joists. Now, there is NO connection between the inner solid membrane and the outer layer of studs. No connection is always going to trump a decent connection.


----------



## rabindu

Seems completely logical. Would I still do the double drywall with green glue?


----------



## granroth

Yes. Doing the floating walls and ceiling takes care of the Decoupling part of soundproofing, but it doesn't address the other three pillars -- namely Mass, Damping, and Absorption. All four factors need to be addressed to truly achieve the best results.


Double drywall with Green Glue in between covers both Mass and Damping. The dual layers create more Mass while the Green Glue creating a Damping layer.


I strongly suggest reading the two "Essential" links listed in the first post of this thread:


Advice from Anthony Grimani (PMI) - Soundproofing 101: How to Keep Your Home Theater Quiet 

Advice from Ted White (Soundproofing Company) - 4 Elements of Soundproofing 


Both are far better writers than me and know the subject inside and out. These are very readable articles, too. I guarantee that you'll learn tons!


----------



## rabindu

Thank you.


----------



## sonaps




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/90#post_24335002
> 
> 
> To start, if you are doing a true room-within-a-room, then there's no need for hat channel. The interior walls already give the coupling that the hat channel and clips would accomplish -- and they do a better job of it, too.



I've seen several others combine both room-within-a-room and clips and channel; here's one BIG worked on:  

(from: http://www.avsforum.com/t/1437336/fall-frenzy-curve-frenzy-man-of-steel-theater-you-pick-bigmouthindc-hits-the-road-again-destination-columbus-indiana )


If there's no benefit why are they doing it?


Don't most double stud walls end up using IB-3 clips, or the like, to connect the top wall plate to the joists above or to the other wall? If so, wouldn't the clips and channel then help to further decouple that connection? It seems like a true "room-within-a-room" wouldn't benefit from clips and channels, so I have to assume that many of the builds using both methods are not true rooms-within-rooms, but have some other connections they are trying to decouple.


----------



## granroth




> Quote:
> Originally Posted by *sonaps*  /t/1509173/soundproofing-master-thread/100_100#post_24340917
> 
> 
> I've seen several others combine both room-within-a-room and clips and channel; here's one BIG worked on:
> 
> (from: http://www.avsforum.com/t/1437336/fall-frenzy-curve-frenzy-man-of-steel-theater-you-pick-bigmouthindc-hits-the-road-again-destination-columbus-indiana )
> 
> 
> If there's no benefit why are they doing it?



I've wondered the same thing. My assumption, based on reading the entire build thread, is that it was an example of a local company doing overkill. @BIGmouthinDC occasionally stops by and maybe he can give more details on the "why".


> Quote:
> Originally Posted by *sonaps*  /t/1509173/soundproofing-master-thread/100_100#post_24340917
> 
> 
> Don't most double stud walls end up using IB-3 clips, or the like, to connect the top wall plate to the joists above or to the other wall? If so, wouldn't the clips and channel then help to further decouple that connection? It seems like a true "room-within-a-room" wouldn't benefit from clips and channels, so I have to assume that many of the builds using both methods are not true rooms-within-rooms, but have some other connections they are trying to decouple.



Hmm... that's an interesting thought. Yes, most double stud walls I've seen are connected to the joists using some kind of isolation clips. Having channels and clips on the walls could possibly make sense in increasingly the decoupling effect with the ceiling.


That's definitely something that I can't give a definitive answer to. Hopefully somebody with a bit more knowledge on this particular subject will step in.


----------



## BIGmouthinDC

Rule one, in this Home Theater hobby there is no such thing as OVERKILL. Only a diminishing return on your investment. The average theater can skip the clips and channel on the side walls it the framing is truely decopled from the start. and if the walls aren't common with other rooms where sound management is crucial.


----------



## granroth

Where are some good build threads with staggered stud walls?


The conventional wisdom has decoupling methods ranked in this order: double walls, staggered studs, clips and channels. There are a number of build threads with double walls and loads of threads with clips and channels. I've yet to find any detailed thread with staggered studs. The closest I've come is a couple threads where one wall is staggered stud... but the main decoupling seems to be clips and channels in those ones.


What am I missing?


----------



## panino


I'm still in the planning stage of my room.  I'd like to be able to isolate some of the walls with clips and/or DD w/ GG, but a few of the other walls, including the ceiling will be problematic.  Is there any use in soundproofing some of the walls but not the entire room?  Or is this just a waste of time.  In other words will I get any benefit from a partial room isolation or do I need to isolate all the walls and ceiling?


----------



## Tom Bley




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/90#post_24345362
> 
> 
> Where are some good build threads with staggered stud walls?
> 
> 
> The conventional wisdom has decoupling methods ranked in this order: double walls, staggered studs, clips and channels. There are a number of build threads with double walls and loads of threads with clips and channels. I've yet to find any detailed thread with staggered studs. The closest I've come is a couple threads where one wall is staggered stud... but the main decoupling seems to be clips and channels in those ones.
> 
> 
> What am I missing?



I am using a staggered stud wall for the left side and front wall of my ht room. I don't have a build thread. I've been very slow at building the basement. The electric is happening now. I'm the only one in the house and the shared walls will be a bar and guest room.

I forgot to mention the walls are decoupled from the floor joists above.


----------



## BIGmouthinDC

Staggered stud walls built by typical contractors and DIYers are coupled to the ceiling joists and floor above and sound will be transferred, if you go with staggered studs use the framing isolation techniques or clips and channel. Otherwise you will be disappointed in your soundproofing efforts.


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/80_40#post_24345414
> 
> 
> I'm still in the planning stage of my room.  I'd like to be able to isolate some of the walls with clips and/or DD w/ GG, but a few of the other walls, including the ceiling will be problematic.  Is there any use in soundproofing some of the walls but not the entire room?  Or is this just a waste of time.  In other words will I get any benefit from a partial room isolation or do I need to isolate all the walls and ceiling?



doing a partial job will produce partial results it would be impossible to predict your results it could be 10-50% as effective. If you would be happy with a 10% result just do a couple of walls.


----------



## granroth




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/100_100#post_24345414
> 
> 
> I'm still in the planning stage of my room.  I'd like to be able to isolate some of the walls with clips and/or DD w/ GG, but a few of the other walls, including the ceiling will be problematic.  Is there any use in soundproofing some of the walls but not the entire room?  Or is this just a waste of time.  In other words will I get any benefit from a partial room isolation or do I need to isolate all the walls and ceiling?





> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/100_100#post_24346690
> 
> 
> Staggered stud walls built by typical contractors and DIYers are coupled to the ceiling joists and floor above and sound will be transferred, if you go with staggered studs use the framing isolation techniques or clips and channel. Otherwise you will be disappointed in your soundproofing efforts.



These are related, in my case. I tried to soundproof the shared wall between two bedrooms a couple years ago. I created a staggered stud wall on a 2x6 plate and filled it with insulation. I didn't decouple it from the ceiling; didn't double up the drywall; didn't do any damping; and didn't treat the ceiling or shared hallway wall.


The end result is as if I didn't do anything at all. I mean, if you play a sound on one side of the wall and listen carefully on the other side of the wall, then yeah, you can tell that it's muted a _little_. But who cares, because that sound is as clear as day coming from every other direction. And honestly, the staggered studs on their own didn't help as much as I thought they would, either.


So I can attest from personal experience that doing a partial job can be essentially as effective as doing no soundproofing at all AND that the benefits of staggered studs is essentially nullified if you connect it right to the ceiling joists.


BTW, panino, the keyword that governs your experience is going to be "flanking." As in, the sound issues you'll have are due to flanking. There's lots of really good info on that online (starting with the two "Essential" links in the first post of this thread).


----------



## panino


Thanks, I will do some more research on it.  Sounds like my decision is going to end up - nothing at all.  I have too many "connection points" throughout my room that would need to be decoupled.  I would essentially have to gut the entire room (already finished) and redo all the framing.  Room within and room would be a solution, but I'm limited on space.  I think I'm just going to have to live with sound isolation issues this time around.  Maybe in my next, "dream" theater. 









 

Thank you for your advice.


----------



## granroth




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/100_100#post_24350202
> 
> 
> Thanks, I will do some more research on it.  Sounds like my decision is going to end up - nothing at all.  I have too many "connection points" throughout my room that would need to be decoupled.  I would essentially have to gut the entire room (already finished) and redo all the framing.  Room within and room would be a solution, but I'm limited on space.  I think I'm just going to have to live with sound isolation issues this time around.  Maybe in my next, "dream" theater.



Yeah, building a theater can definitely be an expensive endeavor and gutting a finished room to re-do it doesn't always sit well with significant others or with budgets. BUT... don't necessarily think that space will be your limiting factor. You can do some great things in a small amount of space. Witness some of the theaters in this thread: Small Theater Build Threads . Notably, the Theater for Hobbits is in a 10x10 space!


With those in mind, think about the possibility of using clips and channel with a couple layers of 5/8" drywall (Green Glue in between). That'll subtract 2-7/8" from the room height and 5-3/4" from the room width. Those may not be egregious numbers, especially when you see what can be done in small spaces.


Basically what I'm saying is that cost and effort will likely be more of a limiting factor than space


----------



## panino


Yeah the wall to wall space isn't so much a concern as the ceiling.  My ceiling is dropped due to numerous pipes and ducts, bringing it to 7' 10".  I would definitely have to consider moving HVAC and pipes into soffits (more cost) as I can't go much lower on the ceiling to get the isolation I'd need.  I think I'll try to come up with a budget to gut and redo the room... see where I end up.  If it is doable I'll definitely pursue it.  If it's not... well then better settle for what I have over a divorce.  









 

I know this has so many variables, but any idea what the average cost to restructure a room (~23' x 13') would be (e.g. reframe with staggered studs, DD, GG, clips, etc..)?


----------



## granroth




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/100_100#post_24350655
> 
> 
> Yeah the wall to wall space isn't so much a concern as the ceiling.  My ceiling is dropped due to numerous pipes and ducts, bringing it to 7' 10".  I would definitely have to consider moving HVAC and pipes into soffits (more cost) as I can't go much lower on the ceiling to get the isolation I'd need.  I think I'll try to come up with a budget to gut and redo the room... see where I end up.  If it is doable I'll definitely pursue it.  If it's not... well then better settle for what I have over a divorce.



If the pipes and ducts are spread out over the width, then yeah, that could take some money to relocate. If they tend to accumulate in one place (the center of the room, perhaps), then you might consider creating a channel for them and "floating" the rest of the ceiling around it. That could give you some extra ceiling height everywhere but where the pipe/duct channel is.


> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/100_100#post_24350655
> 
> 
> I know this has so many variables, but any idea what the average cost to restructure a room (~23' x 13') would be (e.g. reframe with staggered studs, DD, GG, clips, etc..)?



Funny that you mention that now, as there is an active thread talking about exactly that: Dedicated Theater Costs Questions 


In particular, I'm going to quote from Big:


> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1517158/dedicated-theater-costs-questions/0_100#post_24341878
> 
> 
> The extra cost for soundproofing materials of a modest size theater.
> 
> 
> Green Glue
> 
> Isolation clips and channel
> 
> Putty pads
> 
> Acoustical caulk
> 
> Backer boxes
> 
> Heavy door
> 
> Flex duct connections for the HVAC
> 
> Two layers of 5/8 firecode drywall instead of the crap 1/2 inch lightweight they are shoving down our throats because it is cheaper to ship from the plant.
> 
> Insulation all walls and ceiling
> 
> 
> all together will run about $3000-3500 over a cheaply built standard residential construction


----------



## cgott42




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/30#post_24243808
> 
> 
> Granroth:
> 
> 
> 
> BIGmouthinDC is correct when he answered your question about which of the four types of soundproofing would apply to holes, in that the answer is mass.
> 
> 
> But your analysis is going the wrong way. The important part is not: adding mass to the wall relative to the walls mass.
> 
> 
> The mass is what's used to resist the transfer of sound. If there's a path without resistance, then that's a significant transmission path.
> 
> 
> If you have a source room (with a stereo), and a quiet room (with a bed),
> 
> and a wall of 100ft^2 between them that's 3' of solid concrete,
> 
> and there are no other flanking paths (ceiling/floor -- fiction but I'm simplifying),
> 
> and the stereo is played at 80dB at frequency F,
> 
> and the wall stops 90dB at frequency F,
> 
> then the sound heard in the quiet room is -10dB at frequency F, and -10dB you probably can not hear.
> 
> 
> Now open up a six inch square hole in that wall connecting the two rooms.
> 
> So 99.5 ft ^2 is transmitting -10dB,
> 
> and that 0.25 ft^2 hole is transmitting 80dB.
> 
> 
> Now let's convert that to energy, and back to dB.
> 
> -10dB * 99.5 = 0.1 * 99.5 = 9.95
> 
> 80dB * 0.25 = 100000000 * 0.25 = 25,000,000
> 
> Add them together, 9.95 + 25,000,000 = 25,000,009.95
> 
> and divide by the total wall area 25,000,000 / 100 = 250,000
> 
> Which gives us 54dB at frequency F in the quiet room.
> 
> Which you will definitely hear.
> 
> (my math/physics are probably a little bit off in a couple of ways, but the idea is to add the energy)
> 
> 
> Now, instead of a single 6"x6" hole, let's have that solid concrete wall, hovering in the air the way drywall attached to studs might, with a gap all the way around it that's the same area. The sort of gap around the edge of drywall that one might fill with acoustical caulking (because the building moves over time).
> 
> The 4 edges of the wall are 40' in length (10' x 10' wall). So a 0.1 inch gap all the way around would total over a 6" x 6" hole's area.
> 
> Same rules apply as the previous paragraph -- lots of noise goes through.
> 
> Technically it's a little lower than this, because the air in that tiny gap has more resistance/impedance than the single 6" x 6" hole.
> 
> 
> Now fill that edge gap with acoustical caulking. That caulking is not a lot of mass relative to the 3' thick concrete wall, but its coupled with the massive wall, providing resistance/impedance to the sound wave. The actual relationship here is complex, but it's a lot more than air.
> 
> 
> NRC had some statements about having electrical boxes back to back.
> 
> Brian has some interesting measurements about the effects of having electrical boxes back to back, and offset by a stud, and with and without putty packs -- as I recall back-to-back electrical boxes weren't as bad as he was expecting, but separating them and putty packs did help.
> 
> 
> Of course you knew all that instinctively from experience -- I just gave you a little dB energy math, and asked you to think of a big hole as a long crack. When it's noisy outside, you close the window.



Thanks -

I can see a difference viewing it as mass:

Namely - if you were calking a gap in a shower wall - (from what I know) there's no benefit to get the caulk deep into the crack - as long as it totally seals the outside water is stopped.

However with soundproofing - if the caulk is providing mass then this would not suffice - i.e. you'd want to get the caulk to get deep into the full 5/8" depth of the crack.

Using the calc above with a 0.1" length gap equating to a single 6" x 6" hole , if this gap is just surface caulked so the caulk goes 1/4" deep. That would only provide 40% of the mass, leaving 60% w/o mass - i.e. the equivalent of approx. 4.5" x 4.5" hole

Is that correct?


Thanks - so if we view caulk in terms of mass - then the more the better - i.e. Where there is a gap between sheets - you can caulk so the gap is covered from the outside view - i.e. if there was water


----------



## mtbdudex

There is a lot of great info here, exchanges, etc.

I formally nominate this as a sticky here in the Dedicated Theater Design & Construction forum, I will also "report" this post to the mods to put it on their radar for sticky status.

>>click on the flag to report, and pop-up comes up, select other and type in there

Please others do same so it becomes a sticky and the collective AVS knowledge base for Soundproofing.

[edit] that was Quick, congrats on sticky status.


[edit]

sticky request submission


----------



## Tfleming675




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/90#post_24325040
> 
> 
> One layer of batts probably would have been fine.



I used one layer with a three inch gap between the floor and the insulation. I will also have a gap between the drop ceiling and the insulation.


----------



## BIGmouthinDC

Why a drop ceiling? not a good choice for soundproofing.


----------



## Tfleming675




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/120#post_24363135
> 
> 
> Why a drop ceiling? not a good choice for soundproofing.



Understood. Working with some constraints. Need access to the ceiling for mechanical and like the flexibility. I am using tiles that have a .7 NRC and a 40 CAC. I have the insulation with lot's of room for air as well. I also removed the cold air return and put sounds baffles of the HVAC runs.


If drywall with green glue etc being a 10 on a scale of 1 to 10 I am hoping my setup will be around 6 or 7.


Thoughts?


----------



## Tfleming675

Here is the "muffler" I was referring to.


----------



## brwsaw

I need to say my painted drop ceiling and double safe and sound in the floor joist worked really well.

Just 2.0 so far.


Subs on, still about half as loud what it was. That's before I play around with placement, volume etc.


----------



## cgott42




> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/120#post_24351158
> 
> 
> Thanks -
> 
> I can see a difference viewing it as mass:
> 
> Namely - if you were calking a gap in a shower wall - (from what I know) there's no benefit to get the caulk deep into the crack - as long as it totally seals the outside water is stopped.
> 
> However with soundproofing - if the caulk is providing mass then this would not suffice - i.e. you'd want to get the caulk to get deep into the full 5/8" depth of the crack.
> 
> Using the calc above with a 0.1" length gap equating to a single 6" x 6" hole , if this gap is just surface caulked so the caulk goes 1/4" deep. That would only provide 40% of the mass, leaving 60% w/o mass - i.e. the equivalent of approx. 4.5" x 4.5" hole
> 
> Is that correct?
> 
> 
> Thanks - so if we view caulk in terms of mass - then the more the better - i.e. Where there is a gap between sheets - you can caulk so the gap is covered from the outside view - i.e. if there was water



Put differently, if caulking is to provide mass (instead of gaps), then why don't people caulk each layer? Caulking 1 layer (e.g. the outer) would still leave the missing mass just the same on the inner layers.

If the purpose it to prevent air flow - then I understand how 1 layer would suffice, but if it's mass ...


----------



## cw5billwade

I did caulk each layer as discussed earlier in this thread post # 84
http://www.avsforum.com/t/1509173/soundproofing-master-thread/60#post_24315043


----------



## cgott42




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/120#post_24375757
> 
> 
> I did caulk each layer as discussed earlier in this thread post # 84
> http://www.avsforum.com/t/1509173/soundproofing-master-thread/60#post_24315043


Many do so, (myself included) however from what I've read on the format it's not standard - with many just caulking the outer layer. It would seem strange for someone to put on 2 -3 layers of mass, and only caulk (complete the mass) the outer layer - it'd be like putting up a layer of sheet rock with a hole in it.. i.e. if the benefit that cauling provides would appear to be non material - then why caulk at all, So if caulking it would seem that all layers need to be caulked i.e IF (capitalized for emphasis) it's correct that the ONLY function of caulking is to provide mass - this widespread practice would seem very strange. (or just misinformed)


----------



## cw5billwade

to caulk or not to caulk that is the question


----------



## panino




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/90#post_24345362
> 
> 
> Where are some good build threads with staggered stud walls?
> 
> 
> The conventional wisdom has decoupling methods ranked in this order: double walls, staggered studs, clips and channels. There are a number of build threads with double walls and loads of threads with clips and channels. I've yet to find any detailed thread with staggered studs. The closest I've come is a couple threads where one wall is staggered stud... but the main decoupling seems to be clips and channels in those ones.
> 
> 
> What am I missing?


 

So I'm considering biting the bullet and just ripping out all my drywall (*cringes*) in order to more properly soundproof my room.  I will likely end up going with staggered studs with DD & GG on the walls and a clip/channel system with DD & GG on the ceiling. 

 

I guess the question I have is...

Two of the walls abut the concrete foundation.  As there is no other room to worry about on these sides, I initially thought that isolating the wall via staggered studs from the ceiling joists should be enough.  After thinking a bit more into this, I wondered if potential flanking noise passing through these walls could be a concern and if I should go ahead and also utilize DD & GG on these walls as well?  Is it standard to also use DD & GG on walls abutting concrete or is this unnecessary?


----------



## BIGmouthinDC

staggered studs as a technique *does not* isolate a wall from the ceiling, Isolated framing does, build a normal frame one inch short and attach the top plate with IB3 clips. You can do this on all exterior walls facing a foundation but please don't skp the DD and GG it is important to contain the sound on all sides.


If you want to use existing framing, then clips and channel are required to isolate the wall.


----------



## panino


I was planning for staggered studs with isolation brackets to fully decouple the wall.  I figured not only would this provide me with a better isolation than clips and channel, but also maybe save me an inch or so of lost wall space given the dimensions of the staggered studs vs the combo of the clip and channel.  I just wasn't sure how important the DD & GG was on the foundation walls.  You have answered my question.  Thanks again Big!


----------



## panino


Regarding ceiling isolation...  I have a low ceiling 7'10", so I'd like to preserve as much height as possible.  The ceiling is dropped with underlying 2x4 framing to support the existing drywall.  Raising the ceiling isn't an option, so I'll have to keep it dropped.  I was planning on using clips and channel to isolate the ceiling and then the standard DD & GG.  However, I was wondering if I could remove the dropped 2x4 "joists" and replace them after isolating them from the remainder of the ceiling with IB-3 brackets.  I could then drywall and GG right to these isolated dropped joists?  The advantage would be less loss of ceiling height (no longer needing the depth of the channel and clip) and I could now screw into a potentially sturdier surface (e.g. wood rather than the channel).  I've thought about using between joist blocking with the clips and channel to alleviate the height loss, but the brackets seem like a sturdier option if this is possible.  Any thoughts?


----------



## brwsaw




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/120#post_24379016
> 
> 
> Regarding ceiling isolation...  I have a low ceiling 7'10", so I'd like to preserve as much height as possible.  The ceiling is dropped with underlying 2x4 framing to support the existing drywall.  Raising the ceiling isn't an option, so I'll have to keep it dropped.  I was planning on using clips and channel to isolate the ceiling and then the standard DD & GG.  However, I was wondering if I could remove the dropped 2x4 "joists" and replace them after isolating them from the remainder of the ceiling with IB-3 brackets.  I could then drywall and GG right to these isolated dropped joists?  The advantage would be less loss of ceiling height (no longer needing the depth of the channel and clip) and I could now screw into a potentially sturdier surface (e.g. wood rather than the channel).  I've thought about using between joist blocking with the clips and channel to alleviate the height loss, but the brackets seem like a sturdier option if this is possible.  Any thoughts?



I'm more curious than anything...

What are your goals for the room? Is it for 2.0 listening, full out HT?


----------



## cw5billwade




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/120#post_24379016
> 
> 
> Regarding ceiling isolation...  I have a low ceiling 7'10", so I'd like to preserve as much height as possible.  The ceiling is dropped with underlying 2x4 framing to support the existing drywall.  Raising the ceiling isn't an option, so I'll have to keep it dropped.  I was planning on using clips and channel to isolate the ceiling and then the standard DD & GG.  However, I was wondering if I could remove the dropped 2x4 "joists" and replace them after isolating them from the remainder of the ceiling with IB-3 brackets.  I could then drywall and GG right to these isolated dropped joists?  The advantage would be less loss of ceiling height (no longer needing the depth of the channel and clip) and I could now screw into a potentially sturdier surface (e.g. wood rather than the channel).  I've thought about using between joist blocking with the clips and channel to alleviate the height loss, but the brackets seem like a sturdier option if this is possible.  Any thoughts?


what do you mean dropped by underlying 2x4 framing support. A PIC would help?


----------



## panino




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/120#post_24379449
> 
> 
> 
> what do you mean dropped by underlying 2x4 framing support. A PIC would help?


 

I can post a picture/schematic later when I get home from work.  Essentially the ceiling without HVAC, wires, ducting etc... would be 9' high finished.  With all these obstacles in the way, a finished/drywalled drop ceiling was installed bringing the height down to 7'10".  The ceiling drywall is attached to a 2x4 framework that in turn is attached to the joists above.  Sort of like old school strapping that was installed across the joists to attach drywall to, but the strapping is horizontally laid 2x4s suspended a foot lower by additional vertical 2x4s attached to the joists.  Hopefully this paints a better picture, but I will post a pic and diagram (pix are always better in my opinion).

 

The idea is to decouple this 2x4 framing from the joists, negating the need for clips/channels and providing a more solid and likely stronger surface to attach stuff to.

 

 


> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/120#post_24379389
> 
> 
> 
> I'm more curious than anything...
> 
> What are your goals for the room? Is it for 2.0 listening, full out HT?


 

 Full HT, starting with 5.1 but wiring for 7.1.


----------



## cw5billwade

Are most of the mechanicals around the edges where you could do soffits or are they scattered everywhere? It would be nice if you could relocate them to the edges and raise the center of the room. Seems like a waste of space the way it was done.


----------



## panino




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/120#post_24380512
> 
> 
> Are most of the mechanicals around the edges where you could do soffits or are they scattered everywhere? It would be nice if you could relocate them to the edges and raise the center of the room. Seems like a waste of space the way it was done.


 

Unfortunately ALL of the guts of the house run straight down the middle of the room (HVAC, waste line, gas, electric, water, ethernet and coax lines).  These take up a lot of room.. might be hard to squeeze them all in reasonable sized soffits on the sides even if I did move them.  The bigger problem is my Cat5 runs... every room in the house is hard wired with Cat5 line, most of which run through here and they didn't exactly leave much slack when they ran them.  Might be hard to move these lines.

 


> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/120#post_24379449
> 
> 
> 
> what do you mean dropped by underlying 2x4 framing support. A PIC would help?


 

Picture (of inside drop ceiling - taken through one of the can lights) and diagram (forgive my grade-school x-section sketch) as promised!



 

On the left is the current drop set up: above floor is dark brown, joists medium brown, drop ceiling construction using 2x4s light brown, drywall is white.

On the right is my crazy proposed decoupling scheme: decouple part of the drop ceiling framing and insert something like RSIC-DC04 brackets.  I can preserve the ceiling height this way by not having to take up extra room with a clip and channel system that would be needed to span under the ducting.

 



 

Thoughts?  Do I need a straightjacket?


----------



## brwsaw




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/120#post_24382254
> 
> 
> Unfortunately ALL of the guts of the house run straight down the middle of the room (HVAC, waste line, gas, electric, water, ethernet and coax lines).  These take up a lot of room.. might be hard to squeeze them all in reasonable sized soffits on the sides even if I did move them.  The bigger problem is my Cat5 runs... every room in the house is hard wired with Cat5 line, most of which run through here and they didn't exactly leave much slack when they ran them.  Might be hard to move these lines.
> 
> 
> 
> Picture (of inside drop ceiling - taken through one of the can lights) and diagram (forgive my grade-school x-section sketch) as promised!
> 
> 
> 
> 
> On the left is the current drop set up: above floor is dark brown, joists medium brown, drop ceiling construction using 2x4s light brown, drywall is white.
> 
> On the right is my crazy proposed decoupling scheme: decouple part of the drop ceiling framing and insert something like RSIC-DC04 brackets.  I can preserve the ceiling height this way by not having to take up extra room with a clip and channel system that would be needed to span under the ducting.
> 
> 
> 
> 
> 
> Thoughts?  Do I need a straightjacket?



I'd be very tempted to have a new shallower and wider duct installed.

Everything would need to be considered for potential replacement or relocation to make it worth while.

The 2x2s supporting weight above my head would bother me.

Its going to be expensive...


----------



## panino




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/120#post_24382311
> 
> 
> 
> I'd be very tempted to have a new shallower and wider duct installed.
> 
> Everything would need to be considered for potential replacement or relocation to make it worth while.
> 
> The 2x2s supporting weight above my head would bother me.
> 
> Its going to be expensive...


Shallow wider duct is an idea.  Of course I'd still have to relocate pipes and wire that lie on the sides anyway... as you said... "expensive".  I don't know HVAC very well, but a shallower duct would likely also make quite a bit more noise (more wall turbulence), especially with the amount of airflow going through this main duct.

 

If I went with the "decoupling the drop ceiling framing strategy", being a formerly trained engineer, I like to er on the side of over rather than underdoing any structural support.  Especially when it's my own noggin underneath it all.  I'd probably replace those flimsy 2x2s with something much more substantial and more of them.  I've thought about sandwiching the inside of several of the joists in key stress locations with 2x6s or 2x8s, attaching 2x4s to these reinforced joists via lag bolts and then run them down to the decoupler at the ceiling.  This would hold a tremendous amount of weight.  The weakest link in this setup would be the decoupling bracket itself.

 



 

Obviously I wouldn't do this for every single joist 24" OC, but this still might be overkill and overexpensive. 









 

I guess the other alternative is I slap on clips and channel and lose what... 2" or so of my ceiling 









 

I wonder if it would look bad if I had one big soffit in the center with higher ceilings on the sides... hmm prob bad idea.


----------



## brwsaw




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/120#post_24382525
> 
> 
> 
> Shallow wider duct is an idea.  Of course I'd still have to relocate pipes and wire that lie on the sides anyway... as you said... "expensive".  I don't know HVAC very well, but a shallower duct would likely also make quite a bit more noise (more wall turbulence), especially with the amount of airflow going through this main duct.
> 
> 
> If I went with the "decoupling the drop ceiling framing strategy", being a formerly trained engineer, I like to er on the side of over rather than underdoing any structural support.  Especially when it's my own noggin underneath it all.  I'd probably replace those flimsy 2x2s with something much more substantial and more of them.  I've thought about sandwiching the inside of several of the joists in key stress locations with 2x6s or 2x8s, attaching 2x4s to these reinforced joists via lag bolts and then run them down to the decoupler at the ceiling.  This would hold a tremendous amount of weight.  The weakest link in this setup would be the decoupling bracket itself.
> 
> 
> 
> 
> 
> Obviously I wouldn't do this for every single joist 24" OC, but this still might be overkill and overexpensive.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I guess the other alternative is I slap on clips and channel and lose what... 2" or so of my ceiling
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I wonder if it would look bad if I had one big soffit in the center with higher ceilings on the sides... hmm prob bad idea.



There are inexpensive products for use on the outsides of the ductwork.

What size are the floor joists?


----------



## panino




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/120#post_24382728
> 
> 
> 
> There are inexpensive products for use on the outsides of the ductwork.
> 
> What size are the floor joists?


Joists are I believe 12"... I'd have to measure.


----------



## granroth




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/100_100#post_24375757
> 
> 
> I did caulk each layer as discussed earlier in this thread post # 84
> http://www.avsforum.com/t/1509173/soundproofing-master-thread/60#post_24315043





> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/100_100#post_24375814
> 
> 
> Many do so, (myself included) however from what I've read on the format it's not standard - with many just caulking the outer layer. It would seem strange for someone to put on 2 -3 layers of mass, and only caulk (complete the mass) the outer layer - it'd be like putting up a layer of sheet rock with a hole in it.. i.e. if the benefit that cauling provides would appear to be non material - then why caulk at all, So if caulking it would seem that all layers need to be caulked i.e IF (capitalized for emphasis) it's correct that the ONLY function of caulking is to provide mass - this widespread practice would seem very strange. (or just misinformed)



My understanding of caulking all gaps vs mudding them was in terms of ease of use. That is, if you are going to be covering your theater in fabric anyway, then it's easier to caulk all seams than to mud.


However, my further understanding is that it's still preferable to mud all seams if you have the time. My back of the envelope calculations indicate that standard Sheetrock joint compound (not the lightweight stuff) is almost exactly the same density as 5/8 Type X drywall (~50 lbs pcf). Plus mud is dirt cheap. So it makes sense to me to mud all joints that can be mudded and caulk those that remain.


But back to the original premise, that if caulk is ONLY about mass, then not caulking the "internal" seams would indeed be strange. I don't think it's that simple, though. Caulking is worthwhile as mass mostly in relation to the alternative of there being no mass.


Okay, here's my thinking. At its core, soundproofing is all about stopping or minimizing vibrations. Air vibrates very easily and, as such, sound can travel along air pathways with very little energy loss. It doesn't need to be a straight line, either. If the air _can_ make it around a solid object in any way possible, then those sound vibrations in that air will make that same path with little volume drop. If there isn't an uninterrupted path for air, then there's going to be energy transfer in each phase change and the sound volume will drop significantly compared to an unimpeded path.


That's where caulk primarily comes in. It fills up a gap with some mass, which may or may not be a lot relative to the other solid objects (it turns out it is), but is definitely _extremely_ massive compared to air. Therefore, there would be no need to fill in an entire air gap, since the energy has already been significantly damped by the initial mass layer. That's not to say it wouldn't do anything -- I like to say such a thing would be "overkill" but Big likes to say that it's just "diminishing returns."


So now let's look at seams in inner layers of drywall. The air pockets there are pretty tiny but, more importantly, are sealed in by the other layers of drywall. Therefore, there's no uninterrupted pathway for the air to flow and vibrations to follow. There will already have been a notable energy drop just by the first layer (and Green Glue). And again, yes, it makes sense to me that sealing those seams would reduce the vibration even more... but see above for "overkill" vs "diminishing returns."


All that said, I am going to mud the internal layers in my theater, since it's not _that_ much work (doesn't need to be pretty since it'll never be visible) and even if it's diminished returns, it's still a return.


----------



## BasementBob

granroth:


See post #81's first pic, for mud/tape and caulk locations.


BTW, the reason the room side layer is horizontal is it hides the seams from the eye -- according to room painters.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/0_100#post_24313651



Right! I meant to talk about these at the time, but got distracted.


Let's contrast the Zig Zag description with the Soundproofing Company's Soundproofing Tip: Ceiling to Wall Seam Intersection . They also recommend a zig-zag pattern BUT, crucially, they differ by saying "Note that we want solid drywall to drywall contact. Don’t try and leave a gap." That makes sense to me... why would leaving a gap be preferable in this case?


Both recommendations say to use acoustical caulk. I'm not seeing the advantage of using that over normal drywall mud in any drywall-to-drywall seams, though. Both have roughly the same density and both should seal any air gaps for the long term.


Also, what is the thinking behind using mud only if a drywall seam has recessed edges but caulk, otherwise. Simply aesthetics (no bulge) or is there another reason?


----------



## BIGmouthinDC

I disagree with BB's diagram of drywall on the wall, You end up with butt joints which are harder to tape and make disappear. You can reverse the sequence or just do all the panels vertically and stagger the seams.


----------



## BasementBob

Granroth:

re post #151


Think about what is required to get acoustical sealant into the vertical gap in:

 


If it's a big ceiling you might get away with coating one or two edges of the drywall with acoustical sealant, but odds are you'll have gaps that it gets scraped off for one reason or another, and once its up there's nothing you can do about it. But the problem isn't with the first piece where you have oodles of room -- its the last piece of ceiling drywall where your tolerance is so small you're guaranteed to scrape off the goop (acoustical sealant) as you put it in place.

In a closet or narrow up/down soffit spot such as near an overhead pipe/duct or I-beam/joist, you might have to coat three edges or even four. There's no way to lift drywall with four edges covered in goop without scraping it off on the walls on the way up.

Similarly, you might be able to do the ceiling, but you can't also do the floor -- one side or the other, you'll be scraping the goop off by putting the close fit drywall in place.

That said, sealant is kind of sticky, and you might get away with running the goop in the corner before putting the drywall into it, and hoping it'll squeeze into the gap rather than uselessly as most of it ends up behind the large flat side of the drywall sheet -- not remotely optimal, but better than having it scrape off on the walls.


There's also some drying possible with acoustical sealant -- but if you have lots of it, it will stretch nicely. A quarter inch, is about optimal.

Note that too much gap doesn't work at all, within a few months the sealant will fall off one edge or another -- that's why the backer rod has to be in there so the sealant is 1/4" deep as well as tall -- acoustical sealant lasts really well in 1/4 inch gaps. (the backer rod provides no soundproofing of itself, its just there to keep the acoustical sealant optimal)



The acoustical sealant is for where cracks in mud/tape tend to appear -- look at your own house, I'll bet you'll see more cracks in corners than on long walls. There's more movement in corners than in long walls.



So my (Rod's) drawings are acoustically and 'structurally' sound -- 'structurally' used here to mean it'll last.

They're also much easier for tired stupid helpers to put up without creating failure.


FYI, my two drawings were based on some writings of Rod Gervais, and were subsequently modified a few times until Rod Gervais approved them. The second one for example is named 'zigzag4.gif'. That's because he rejected 'ziggaz1.gif', 'ziggaz2.gif', 'ziggaz3.gif' which matched his post, but not what he understood.


If someone can get Brian to look at this and say Rod is wrong, I'll accept it. But no one else from the soundproofing company trumps Rod in my opinion.


----------



## Gnaw em Gophs

Hoping someone can settle a debate I'm having. I have already framed wall 1" from basement foundation. My good friend does spray foam insulation. My thought is to move wall 2" off foundation, spray 1" with foam, 1" gap, pink fluffy for stud cavity and isolate wall from floor joists above with clips. He thinks should leave studs as is, spray foam to fill gap and 1/2" into stud cavity and then use fluffy for rest of stud cavity and clips for joists above. He thinks foam will stop sound by stopping studs from vibrating. Either way we'd also use DD+GG. Any thoughts?


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## BIGmouthinDC

don't listen to your friend, he may know foam, but he doesn't understand mechanical isolation in the context of soundproofing. Stopping rattles can often mean transferring the vibration to something else.


----------



## granroth




> Quote:
> Originally Posted by *Gnaw em Gophs*  /t/1509173/soundproofing-master-thread/100_100#post_24395743
> 
> 
> Hoping someone can settle a debate I'm having. I have already framed wall 1" from basement foundation. My good friend does spray foam insulation. My thought is to move wall 2" off foundation, spray 1" with foam, 1" gap, pink fluffy for stud cavity and isolate wall from floor joists above with clips. He thinks should leave studs as is, spray foam to fill gap and 1/2" into stud cavity and then use fluffy for rest of stud cavity and clips for joists above. He thinks foam will stop sound by stopping studs from vibrating. Either way we'd also use DD+GG. Any thoughts?



Nope. Honestly, this isn't even really a debate in the classic sense -- your friend is just completely wrong. So wrong, in fact, that I'm genuinely curious where he even got the impression that sound vibrations work that way. Ask! I want to know.










The method you describe is pretty much the standard way to do this, so stay the course.


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## BasementBob

All foam is rigid. It can be used to couple two leaves together if there's a triple leaf problem.


There's open cell foam and closed cell foam. Open cell has some sound absorptive abilities like fluffy fiberglass pink. Closed cell is a better insulator and a vapor barrier. Basements, and most foam installers, usually use closed cell foam to give a thermal break and vapor barrier.


Using both foam and fluffy may move the condensation point out between the two, and create mold there. Here in chilly Canada the rule is vapor barrier on the room side of the insulation, which is usually at the drywall -- but closed cell foam without fluffy is its own vapor barrier which is fine by itself. Mold is worse than noise pollution. Two vapor barriers (one closed cell foam on the concrete, and another 6mil poly at the drywall), is worse again. If you use both foam and fluffy fiberglass, ensure that whatever you make the wall out of is moisture and mold proof, and that any moisture has some place to go.


If the top plate of your stud wall is attached (touching and nailed) to the bottom of the joists, then your decoupling isn't complete anyway and you'll get so much flanking through that path that foam connecting the concrete wall to the studs probably isn't going to make much difference.

If you're using wall sway braces with neoprene isolator pads on your top plate (and thus the top plate not touching joists or wall), then coupling the studs to the concrete wall with foam would be a mistake.

If your stud top plate is free (not attached to anything, and no sway braces) you may be violating building code -- which is a nice way of saying your walls may move enough that the ceiling may separate or fall.

If you use clips both on the ceiling and the studs, then it doesn't matter if your studs are coupled to the concrete wall with foam or coupled to the joists.


If you use clips on the ceiling, but not on the studs, then you want the studs decoupled as much as possible -- which means no foam attaching to both the concrete wall and studs.


If your foam guy can do one inch of foam on the concrete and not touch the studs, he's a real artist at it. More likely he'll accidentally hit the studs in some bits, and you'll take a drywall saw and separate the foam off the studs.


If I were building a basement for living, I'd use closed spray foam without fluffy -- lots of closed spray foam.

If I were building a basement for theatre, I'd skip the spray foam completely, just use 3"+ fluffy and vapor barrier.


If you must use both foam and fluffy, use as little fluffy as possible. You don't need much fluffy to get the most soundproofing benefit, and the less thermal insulation the fluffy provides the more likely the condensation point will be inside the closed cell foam somewhere which is just fine. For example, 3" of closed cell foam, 1" air gap, 1" fluffy in the studs, would be fine just about anywhere.


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## Phrehdd

I am going to have to read far more in this particular thread as it is proving very educational for my next project.


In the meanwhile, I have a situation that perhaps some folks here would be able to give me some options, guidance or sites to read up on to help with a particularly troubling scenario -


I live in a rented flat that has AC units on the roof. They not only make "air noise" I can hear in my flat but also mechanical noise which for me is far worse. Since I cannot really open up the walls, is there any treatments that can be done to the interior walls and ceiling that are also cost effective? The noise and vibration often kills some of my music and movie experience and afterwards culminates into going to bed with the sound of a "dishwasher" above my head and down the walls and then some (including the flat below me having its air circulator making my floor slightly vibrate along with noise it creates0.


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## BIGmouthinDC

they do make rubber isolation pads for mechanical equipment which might help a little bit, it is hard to know without looking at the AC units. As far as treating your flat, it would probably be cheaper to move. That is the beauty of renting. In the mean time get a good pair of surround headphones.


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## Gnaw em Gophs

Thanks BIG, granroth and BB. Helpful.


----------



## Phrehdd




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/150#post_24396691
> 
> 
> they do make rubber isolation pads for mechanical equipment which might help a little bit, it is hard to know without looking at the AC units. As far as treating your flat, it would probably be cheaper to move. That is the beauty of renting. In the mean time get a good pair of surround headphones.



I suppose you are correct about moving (a serious consideration). I admit being frustrated to be recipient of these noises without any recourse and was hoping there was a possible way to add some dampening or absorbing material that didn't cost a fortune. Thanks for the "move out" suggestion as it is honest and logical.


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## BIGmouthinDC

Phrehdd, your description of the problem leads me to believe you could spend several thousand dollars on materials and labor to tame the noise you hear and still not have a guarantee that you will be happy with the result.


----------



## Phrehdd




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/150#post_24399211
> 
> 
> Phrehdd, your description of the problem leads me to believe you could spend several thousand dollars on materials and labor to tame the noise you hear and still not have a guarantee that you will be happy with the result.



I am sure you are correct. - A rather frustrating matter for anyone to pay rent and continue with the level of noise. Sadly, I am sure there is little legal recourse (as opposed to doing internal fixes myself). Again, thanks for the honest and straight forward response. I'll just say when the place is quiet I get a great deal of joy out of my equipment whether watching movies or playing 2 channel and multi-channel music. In the meanwhile, I'll read through all these posts to get some ideas for what I guess will most likely in the near future be my new residence.


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## marvoroberts


Changing the direction of conversation for a brief moment please?

 

Unlike the current discussion problem I have a *below ground* and separate from my house (below the patio) basement area made of concrete blocks without any chance of sound interference from anywhere - I even have a solid fireproof door!

 

My question is given that the whole room is made out of concrete blocks and my projector will be in a separate projection media 'room', what sort of Soundproofing should I be considering. I realise that most of the discussions in this thread relate to 'wood or stick built' houses and apologise in advance if I am out of order. I am located in Cornwall, England where everything is made from Granite! Also I am going to put in a sub floor to run the cables and electrics through and I will be raising the back area so I can get in two rows of seats?

 

I intend to plaster the screen wall and paint it with an appropriate paint once I have chosen a projector. I do have to insert a ceiling so any advice or guidance will be much appreciated. I am intending to post the whole design and build process in the Forum but as I am at the pre-design stage I thought I would get all my ducks in a row before being given a lecture in my mistakes before I start by the likes of BigMouthinDC (Jeff Parkinson)

 

In anticipation - Many thanks


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## BIGmouthinDC

sounds interesting, I suspect your biggest problem will be sound quality rather than sound proofing. I imagine that currently the room is very reverberant with all the hard parallel surfaces.


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## marvoroberts


The actual Room dimensions of the Theatre seating is 20 ft by 12 ft with a finished ceiling height of 7ft 4 inches (6.11 x , 3.76 x 2.25 metres) I have attached a  preliminary layout which might help explain.. Any thoughts will be much appreciated. 

As for the sound... I ha ve decided to go down the 2:1 Audio route using some very impressive Event Opals which are Active Studio Monitors being driven either by an Oppo 105D or via my HTPC.


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## cw5billwade

My question is what is above the room and how is that constructed. Poured concert slab making it truly a bunker or is it conventional floor joists? If standard joists with a room above you will have the flanking issues to the rooms upstairs. It that space is your attic you will still have the flanking to the rooms beside and behind the theater. That would need to be addressed.


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## marvoroberts


Hi there cw5billwade - The construction of the ceiling / roof is of Pre stressed Concrete T Beams in-filled with concrete Blocks with a poured layer on top of waterproof concrete. I have attached a few Photos below to help one understand the problem.. 

 



The top picture is  a close up of the T Beam infilled with the concrete block.

The second is a view of the room scheduled for converting into a Home Theatre as per the earler post. The photo below shows a view of the conservatory which sits above and on the concrete T beam floor. The Theatre is below the Patio which is highlighted.


----------



## elmerfudII

We bought a higher end house that was built in 2008. We bought the house a year ago and renovated the main and upper floors. Its now time to start planning and building the media room area


One thing we've learned living in the house is that sound from the basement is easily heard on the main floor. There is no way that we could use a media room in the basement the way it is without it being noisy on the main floor. Basically we need a way to soundproof the ceiling in the basement.


The basement is fully framed, dry walled and painted. The media room area is nothing more than walls, ceiling and floor at this point. Its just a big room with no screen, lighting, carpet, etc. We intend to make some significant changes in the room.


The basement has 9 foot ceilings with 1/2" lightweight drywall on them. The main floor has good quality 3/4" plywood underlay covered with brazilian cherry hardwood. There is no rug anywhere on the main floor. The floor joists are about 16" tall. There is no insulation between them.


So... is there an easy way to soundproof the basement ceilings without ripping them out and starting over ?


Is it better to tear out the existing ceiling and insulate between the joists and then put up an isolated ceiling or leave the existing ceiling in place and put up a sub ceiling and insulate between the two ceilings ?


Thanks


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## BasementBob

marvoroberts:


Years ago I got some theatre projection room glass (optically perfect glass for projecting an image through).

I don't remember where I got it from. It was 6"x6" (15cm x 15cm).

With your projector in a different room, you'll probably want something similar to put into the wall behind your seating -- for soundproofing reasons to reduce the noise of the projector or anything else you might have in the media room (such as a PS3-bluray with a noisy fan).


----------



## BasementBob

marvoroberts:


I'd start with the concept of a noise floor [e.g. 25db(A) to 35db(A), or NC rating]. If the room is quiet enough, you won't be turning the volume up to hear the quiet bits which would otherwise be masked by noise (signal-to-noise ratio of 70dB is fair, 80dB is preferred, 95dB is more expensive). Where the noise floor is, is a design decision to be made (NC 100 noise floor is really cheap [paper bag], NC 5 noise floor is extremely expensive [demolish your house and start over]). If you're practically deaf, and play everything loud all the time, you can also have a higher noise floor.

The THX ratings are something like: "The steady-state theatre noise floor should preferably be below NC25, with NC30 the worst case acceptable. Intermittent increased noise floors should not exceed NC35."


How quiet is the room now? Can you hear aircraft, bus/truck traffic, hvac/plumbing/dishwasher? Put a boom box (portable CD player) on a chair on the patio, and measure the sound loss. Put a subwoofer in the basement, and measure the sound in the room to determine the transmission loss through the fire door. If the sound transmission loss is already high enough to knock the central heating blower's basement noise under your noise floor, then that's great.


If you put a subwoofer into the room and play it loud [90db @20-70hz], can you hear it in your house, particularly the bedrooms? Do the kitchen dishes rattle? Do the neighbours hear it?


If you can't hear outside noise, and the outside can't hear you, then you're already done soundproofing, except for hvac (which is both a noise transmission conduit, and a source of wind/blower noise).


In otherwords, measure what you have now, then engineer what you're going to do to fix it. If the diagnosis is that you're already fine, then do naught.


----------



## cw5billwade




> Quote:
> Originally Posted by *marvoroberts*  /t/1509173/soundproofing-master-thread/150#post_24401219
> 
> 
> Hi there cw5billwade - The construction of the ceiling / roof is of Pre stressed Concrete T Beams in-filled with concrete Blocks with a poured layer on top of waterproof concrete. I have attached a few Photos below to help one understand the problem..
> 
> 
> The top picture is  a close up of the T Beam infilled with the concrete block.
> 
> The second is a view of the room scheduled for converting into a Home Theatre as per the earler post. The photo below shows a view of the conservatory which sits above and on the concrete T beam floor. The Theatre is below the Patio which is highlighted.





> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/150#post_24402631
> 
> 
> marvoroberts:
> 
> 
> I'd start with the concept of a noise floor [e.g. 25db(A) to 35db(A), or NC rating]. If the room is quiet enough, you won't be turning the volume up to hear the quiet bits which would otherwise be masked by noise (signal-to-noise ratio of 70dB is fair, 80dB is preferred, 95dB is more expensive). Where the noise floor is, is a design decision to be made (NC 100 noise floor is really cheap [paper bag], NC 5 noise floor is extremely expensive [demolish your house and start over]). If you're practically deaf, and play everything loud all the time, you can also have a higher noise floor.
> 
> The THX ratings are something like: "The steady-state theatre noise floor should preferably be below NC25, with NC30 the worst case acceptable. Intermittent increased noise floors should not exceed NC35."
> 
> 
> How quiet is the room now? Can you hear aircraft, bus/truck traffic, hvac/plumbing/dishwasher? Put a boom box (portable CD player) on a chair on the patio, and measure the sound loss. Put a subwoofer in the basement, and measure the sound in the room to determine the transmission loss through the fire door. If the sound transmission loss is already high enough to knock the central heating blower's basement noise under your noise floor, then that's great.
> 
> 
> If you put a subwoofer into the room and play it loud [90db @20-70hz], can you hear it in your house, particularly the bedrooms? Do the kitchen dishes rattle? Do the neighbours hear it?
> 
> 
> If you can't hear outside noise, and the outside can't hear you, then you're already done soundproofing, except for hvac (which is both a noise transmission conduit, and a source of wind/blower noise).
> 
> 
> In otherwords, measure what you have now, then engineer what you're going to do to fix it. If the diagnosis is that you're already fine, then do naught.


I think Ted at sound proofing company said that concrete was very good at transmitting sound waves far and wide i.e. my flanking comment. Now that we know you have a bunker it may make it worse than better. For sure I cannot answer this but I think the tests Basement Bob mentioned are worth a try. I am just wondering if putting insulation or ridged fiber board between your concrete T beams would help? Correct me your height is already limited so room in room is out?


----------



## cw5billwade




> Quote:
> Originally Posted by *elmerfudII*  /t/1509173/soundproofing-master-thread/150#post_24401709
> 
> 
> Is it better to tear out the existing ceiling and insulate between the joists and then put up an isolated ceiling or leave the existing ceiling in place and put up a sub ceiling and insulate between the two ceilings ?
> 
> 
> Thanks


I think this is the only way to go but you can reuse the DW you take down if you are careful in the demo. Use two layers with green glue in between make sure you only use 1 1/4” screws on first layer and 1 3/4” screws on second layer or you will couple it to your hard wood above. R 19 in the ceiling joist than IB-1 clips, hat channel, and two layers of 5/8" DW with GG You will need to decouple the walls as well. Sound proofing is an all or wasted your money doing half kind of thing.


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/160_40#post_24403152
> 
> 
> but you can reuse the DW you take down if you are careful in the demo.



This is something I would need to see to believe. IMHO drywall is one of the cheapest building materials and not worth the time trying to remove each piece intact.


----------



## granroth




> Quote:
> Originally Posted by *elmerfudII*  /t/1509173/soundproofing-master-thread/100_100#post_24401709
> 
> 
> The basement has 9 foot ceilings with 1/2" lightweight drywall on them. The main floor has good quality 3/4" plywood underlay covered with brazilian cherry hardwood. There is no rug anywhere on the main floor. The floor joists are about 16" tall. There is no insulation between them.
> 
> 
> So... is there an easy way to soundproof the basement ceilings without ripping them out and starting over ?
> 
> 
> Is it better to tear out the existing ceiling and insulate between the joists and then put up an isolated ceiling or leave the existing ceiling in place and put up a sub ceiling and insulate between the two ceilings ?



You actually have quite a few options. Yes, one of the options is to just drywall over the existing ceiling (with Green Glue) and that will help a little. You're going to get a lot more bang for the buck if you take that (very cheap) layer of drywall down, though. Here's a good lineup of treatments that you can do, along with how effective they are: How to Soundproof a Ceiling 


But the fact that you have 9 ft ceilings brings up another possibility. If you don't have a lot of stuff between the joints (pipes, HVAC, etc), then you always create a set of "floating" joists in between. That is, you would create an interior set of walls that don't touch the outside walls and then put new joists resting ONLY on those walls. They would be between your current joists and dropped down by an inch or so. That's the absolute gold standard for sound insulation, and it would only cost you a few inches.


Some details here: Building a Room Within a Room


----------



## granroth




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/100_100#post_24403429
> 
> 
> This is something I would need to see to believe. IMHO drywall is one of the cheapest building materials and not worth the time trying to remove each piece intact.



Seconded. I'm a big proponent of "deconstruction" as opposed to "demolition" and reuse and recycle as much as I can. But I draw the line at drywall. I attempted to save it during my first major renovation and the found that while yes, it is theoretically possible to save some of the drywall (mostly if it's screwed and not nailed), it's not even CLOSE to worth it. Those panels would need to be ~$100 each to justify the hours you'd waste dealing with them.


----------



## elmerfudII




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/150#post_24403429
> 
> 
> This is something I would need to see to believe. IMHO drywall is one of the cheapest building materials and not worth the time trying to remove each piece intact.



You guys are right that drywall is cheap, but the labor to put it up, tape it, sand it and paint it certainly isn't ! Having just done a whole bunch of small drywall jobs in the house, its a major pain to hire people to do drywall.


Having said all that, I think you guys are right that the ceiling needs to come down.


----------



## marvoroberts


Hi there cw5billwade

I have attached a cross section of this basement project - you can see that the basement has been constructed as a complete stand alone structure. It is free standing and has lose pea gravel and polystyrene insulation on all four walls to take away any water etc. Have a look see and then maybe we can agree as to how one should proceed.

 

As for noise transmission - All I can say is that if I tied you up and locked you in the basement I doubt you would ever be heard. We are talking about 300mm of blockwork and insulation all round....

On top of the patio have a basalt tile system which sit on plastic feet to allow the rain to permeate to the waterproof membrane (Paint and then  

 

 

concrete screed) So there will not be any transmission of sound downwards. The only potential area for sound coming into the theatre is the MVHR (Mechanical Ventilation and Heat Recovery / Air Conditioning). But I have done a sound test and on the low setting I can not hear the fan which is isolated by a flexible insulated baffle.

 

So all up I am pretty happy about the sound proofing. What really interests me is given that I have to build the floor I would like to know what treatment I can incorporate in the design to deaden any potential unwanted sound /echo coming from the speakers.


----------



## cw5billwade




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/150#post_24403429
> 
> 
> This is something I would need to see to believe. IMHO drywall is one of the cheapest building materials and not worth the time trying to remove each piece intact.


LOL I know but I did say CAREFUL!


----------



## cw5billwade

marvoroberts:

It really is a bunker then. I need one of them at my house but for tornados. I think that standartd building practices for the floor using presure treated lumber for the riser and stage if you build tem is all you need check Stockmonkey200's Desert Sunset Theater build. he did a really good job documenting his floor during his build. Then check out the Acoustical Treatments Master Thread , . you will diffently need som deading from reverberation.


----------



## cw5billwade

a few recent build with treatments
7channelfreak's College Park's 4K Cinema 
Spaceman-theater-build 

dlbek used a profisional to do his treatments dlbeck's The Savoy 

I treated my front and rear wall so far my thread is in signature. Also check most of the builds that BIGmouthinDC builds he documents everything very well.


----------



## Conspiracy*

Soundproofing is all or nothing...


Heres my idea, which I'll later update with pics.

The footfall noice from upstairs is rediculous. I am going to tear out my existing ceiling to get access to my joists. I plan on using GG and a single layer of drywall against my subfloor between the joists, filling the joists with r19, then single layer of drywall again.


Do you think my efforts will be wasted?


What if I isolate the area of my ceiling with the worst noise issues, and double up the drywall there, but leave the rest untreated? Could that help?


Thanks,


----------



## marvoroberts


Conspiracy* Would it not be much cheaper and more effective to shoot the blighters? Or maybe use headphones?


----------



## Conspiracy*

Shooting them would leave me awfully lonely. I am not a fan of headphones either


----------



## elmerfudII

Anyone have comments on isolating the sound from ceiling speakers ?


Our house sound system is wired for ceiling speakers in several rooms on the main floor. The problem is that when you use them, it creates a lot of sound on the second floor. Any ideas on minimizing this ?


Would the "canned" ceiling speakers be a lot better than the "open" ceiling speakers ?


Would closing off the joist space on either side of the speaker and insulating it, like a speaker cabinet, help ?


Would installing a regular bookshelf speaker (non rear ported, enclosure and all) into the ceiling instead of a ceiling speaker be better ?


Any and all thoughts on this topic will be greatly appreciated !


----------



## ctviggen




> Quote:
> Originally Posted by *Conspiracy**  /t/1509173/soundproofing-master-thread/180#post_24418679
> 
> 
> Soundproofing is all or nothing...
> 
> 
> Heres my idea, which I'll later update with pics.
> 
> The footfall noice from upstairs is rediculous. I am going to tear out my existing ceiling to get access to my joists. I plan on using GG and a single layer of drywall against my subfloor between the joists, filling the joists with r19, then single layer of drywall again.
> 
> 
> Do you think my efforts will be wasted?
> 
> 
> What if I isolate the area of my ceiling with the worst noise issues, and double up the drywall there, but leave the rest untreated? Could that help?
> 
> 
> Thanks,



Your efforts will mainly be wasted. You still have a path for sound to travel from the subfloor, to the joists, and to the drywall (on the ceiling). I did insulation and 1/2 inch drywall, and every time my daughters used a marble on the ceramic floor above, I could easily hear it. You need to install some type of isolation to break that path.


----------



## Conspiracy*

I suppose someone out there has done testing on half measures? The soundproofing company's website certainly doesn't thing it's an all or nothing approach, they have at least five different options from least effective to most effective on their site.


----------



## blazar

For a ceiling we did a combination of air, mass loaded vinyl, foam insulation ... Its pretty darn good but not perfect. Sound getting out of the room is more of an issue than sound getting in.


----------



## elmerfudII




> Quote:
> Originally Posted by *blazar*  /t/1509173/soundproofing-master-thread/180#post_24430555
> 
> 
> For a ceiling we did a combination of air, mass loaded vinyl, foam insulation ... Its pretty darn good but not perfect. Sound getting out of the room is more of an issue than sound getting in.



I'd love to hear the details !


----------



## blazar

Well in order from the ceiling to the floor (bedroom above):


1.Wood trim on the ceiling (to help add shape/design and mild diffusion effect).

2. Then sheetrock

3. Gap of air

4. Foam insulation (because we just happened to be using on exterior walls and i could add it inexpensively... Has some midrange and treble absorbtion at best). This is open cell foam btw. Soft foam technically.

5. Then the wood boards above the joists.

6. In the room we put down a layer of mass loaded vinyl.

7. Finally the 1/2 inch thick (i think) wood floor.

8. For what its worth there is also a rug in the room to reduce foot fall noise.


We could have gone with green glue and another layer of sheetrock i suppose but i had already spent massive amounts of money on this square footage... For example the hydronic heated floor (no sound, dust free way to heat the room).


----------



## cw5billwade




> Quote:
> Originally Posted by *Conspiracy**  /t/1509173/soundproofing-master-thread/180#post_24429860
> 
> 
> I suppose someone out there has done testing on half measures? The soundproofing company's website certainly doesn't thing it's an all or nothing approach, they have at least five different options from least effective to most effective on their site.


Agreed they do have the 5 different approaches to treating the ceiling and floor above but that is just talking about the foot fall noise to the room below. Or the sound from the music/movie to the room above. You also have to consider the room below if you are putting two layers of DW with Green Glue then cut holes in it for your can lighting and you do not put the backer boxes in then you wasted your money on the extra layer of DW and GG because now the sound will just go straight through the hole. You also need to consider how the walls are done in the room below. If all you do is the ceiling and nothing to the walls than flanking noise will occur. Think of sound proofing as an envelope. You want it sealed so you need to do the walls ceiling and floor of your room. Anywhere you have something coming in or out of the room like HVAC or lighting needs to be addressed as well or the sound escape the envelope.


----------



## Conspiracy*




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/180#post_24434260
> 
> 
> Agreed they do have the 5 different approaches to treating the ceiling and floor above but that is just talking about the foot fall noise to the room below. Or the sound from the music/movie to the room above. You also have to consider the room below if you are putting two layers of DW with Green Glue then cut holes in it for your can lighting and you do not put the backer boxes in then you wasted your money on the extra layer of DW and GG because now the sound will just go straight through the hole. You also need to consider how the walls are done in the room below. If all you do is the ceiling and nothing to the walls than flanking noise will occur. Think of sound proofing as an envelope. You want it sealed so you need to do the walls ceiling and floor of your room. Anywhere you have something coming in or out of the room like HVAC or lighting needs to be addressed as well or the sound escape the envelope.



I get what you're saying so let me clarify. I don't care about noise getting out of the room. There is not much noise getting into the room other than the footfall. The footfall is what is bothering me. I'm thinking of doing drywall up agains the subfloor, r19, then clips/channel, then drywall. I am getting a solid core door, with something to block the sound going underneath.


----------



## granroth




> Quote:
> Originally Posted by *Conspiracy**  /t/1509173/soundproofing-master-thread/100_100#post_24435616
> 
> 
> I get what you're saying so let me clarify. I don't care about noise getting out of the room. There is not much noise getting into the room other than the footfall. The footfall is what is bothering me. I'm thinking of doing drywall up agains the subfloor, r19, then clips/channel, then drywall. I am getting a solid core door, with something to block the sound going underneath.



Yeah, that'll go a long way. That solution has Decoupling, Absorption, and Mass. Add another layer of drywall with Green Glue and you have Damping, too, which brings all four elements of sound proofing into play.


What I don't know is if it's decoupled enough. That is, if you treat the ceiling but not the walls, then you'll need to be aware of flanking noise that travels down the studs in the walls from the floor above. I'm not all that certain how much of an impact that will make. Perhaps a bit, based on the comments from Erskine in this thread: How to Soften Footfall Noise


----------



## cw5billwade




> Quote:
> Originally Posted by *Conspiracy**  /t/1509173/soundproofing-master-thread/180#post_24435616
> 
> 
> I get what you're saying so let me clarify. I don't care about noise getting out of the room. There is not much noise getting into the room other than the footfall. The footfall is what is bothering me. I'm thinking of doing drywall up agains the subfloor, r19, then clips/channel, then drywall. I am getting a solid core door, with something to block the sound going underneath.


So SPC Ceiling Solution 4 from Sound Proofing Company How to sound proff a ceiling but with one layer of DW vise the 2 in the description? http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/ 
 

Don't forget the backer boxes on the lights then. For the extra couple pails of GG and cost of DW I would do the 2 layers like the Picture above if it were me. So it would be Sub Floor/GG/DW/R13/Clips and channal/DW/GG/DW


----------



## ArturW

Hello,

I'm in process of finishing my basement (TV room). I've been researching soundproofing options for a while and my head is already spinning. The walls are concrete with 2x4 framing in front and some insulation in between. This is finished, I'm not touching it.


I'm left with the ceiling. I want to limit noises going up and I am not concerned with noises coming from above. The subfloor and joists are exposed. I'm considering installing green glue between the joists as on the image in post #194 above. Will this offer any benefit in my case (limit noises going UP)? One layer vs two layers? The reason I'm considering this is that the ceiling is already below 7' and 2 layers of drywall and green glue are most likely not an option, decoupled or not.


I''m considering decoupling the ceiling (using recessed clips) with a single layer of .. preferably not drywall (I hate working with drywall + other finishing concerns in this particular case). Will plywood (mdf?) be much worse than drywall and is it even worth decoupling a single layer of anything? Is spending money on the ceiling worth if the will stay the way they are right now? They are attached to the rest of the framing above, after all.


For insulation I have plenty of "pink stuff" available. I've been considering ultratouch or maybe roxul but I'm not sure if the gain would be significant over regular fiberglass insulation.


I'm prepared to spend some money, but I don't want to go crazy either, especially if the benefits would be small.


I'd be happy to hear opinions and possible solutions for my room from the more experienced forum members. The room will most likely be generating some frequencies below 100hz too.


Thank you


Artur W.


----------



## granroth




> Quote:
> Originally Posted by *ArturW*  /t/1509173/soundproofing-master-thread/100_100#post_24439815
> 
> 
> I'm left with the ceiling. I want to limit noises going up and I am not concerned with noises coming from above. The subfloor and joists are exposed. I'm considering installing green glue between the joists as on the image in post #194 above. Will this offer any benefit in my case (limit noises going UP)? One layer vs two layers? The reason I'm considering this is that the ceiling is already below 7' and 2 layers of drywall and green glue are most likely not an option, decoupled or not.
> 
> 
> I''m considering decoupling the ceiling (using recessed clips) with a single layer of .. preferably not drywall (I hate working with drywall + other finishing concerns in this particular case). Will plywood (mdf?) be much worse than drywall and is it even worth decoupling a single layer of anything? Is spending money on the ceiling worth if the will stay the way they are right now? They are attached to the rest of the framing above, after all.
> 
> 
> For insulation I have plenty of "pink stuff" available. I've been considering ultratouch or maybe roxul but I'm not sure if the gain would be significant over regular fiberglass insulation.



Always think of the four elements of soundproofing - Decoupling, Mass, Damping, and Absorption (in roughly that order, arguably). Green Glue is a damping layer, but it absolutely requires mass on both sides to be effective. That is, just installing Green Glue on the subfloor between the joists wouldn't be enough -- you'd need to add at least one more layer of some kind of mass (drywall, OSB, plywood, etc). That will give you Mass and a little bit of Damping, but doesn't do anything for Decoupling.


In fact, that'd be your biggest issue, since you would still have a direct pathway for sound to travel through your joists. You might think of it in terms of having one solid opening of a foot or so wide where sound can directly travel to the floor above. Practically speaking, I think you'd see that the added Mass and Damping would help with footfall noise (noise coming down) but only marginally helping with outgoing noise.


To really get your bang for the buck, you'd need to Decouple those joists. A layer of clips plus a layer of plywood or OSB (which would be close enough to the performance of drywall to not make much difference) would cover that. Another layer of Mass with some Green Glue would help even more, but now we're looking at a notable loss in ceiling height.


I will say that I'm not sure what you mean by "recessed clips", especially in the context of sound proofing. The clips would need to be "resilient" (have a moveable layer, essentially) to be usable for decoupling.


----------



## blazar

I also did orange can foam insulation (fireproof) in the holes in the lighting fixtures so that I could reduce the vibrations of the cans themselves during bass playback.


Now nothing rattles up there! This

Might help soundproofing also.


----------



## Chuck Miller

Here's a quick and basic question. I'm just starting to build my theater in the basement. I'm in the process of planning my soundproofing measures, but here is my very first question. From a soundproofing standpoint, does it matter whether I frame with wood vs. metal studs? Any advantages/disadvantages of either approach?


Cheers!


Chuck


----------



## BIGmouthinDC

It matters more if you isolate the top plate, I like the grip that isolation clips/brackets get in wood more than metal.


----------



## blazar

Metal studs seems overkill and also are harder to work with if there is a framing mistake. Hard to cut into metal if mods to the room ever needed to be done.


If you are buulding a new house, be sure to spray your frame (the first three feet of the studs from the ground) with an anti termite mineral like BoraCare... Cheap,nontoxic and you never have to worry about termites.


You can buy the stuff on ebay usually.


----------



## ArturW




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/180#post_24439970
> 
> 
> [..] you'd need to add at least one more layer of some kind of mass (drywall, OSB, plywood, etc). That will give you Mass and a little bit of Damping, but doesn't do anything for Decoupling.
> 
> 
> [..]Practically speaking, I think you'd see that the added Mass and Damping would help with footfall noise (noise coming down) but only marginally helping with outgoing noise.
> 
> 
> [..]
> 
> I will say that I'm not sure what you mean by "recessed clips", especially in the context of sound proofing.



Thank you for quick reply. I'm not sure if I got it right. So using green glue with a layer (or two) of drywall etc between the joists will help me only marginally with the outgoing noise? If that's the case I will probably skip this part and save some money and work. When I said "recessed clips" I meant specifically the low profile GenieClip LB3. I used wrong words









Will the fact that the walls are not decoupled in any way minimize the effect of the decoupled ceiling in any significant way?


----------



## granroth




> Quote:
> Originally Posted by *Chuck Miller*  /t/1509173/soundproofing-master-thread/100_100#post_24440135
> 
> 
> Here's a quick and basic question. I'm just starting to build my theater in the basement. I'm in the process of planning my soundproofing measures, but here is my very first question. From a soundproofing standpoint, does it matter whether I frame with wood vs. metal studs? Any advantages/disadvantages of either approach?



Metal studs are mildly better than wood from an isolation standpoint IF you are building a single wall. If you are doing a double wall, then any advantage is lost.


Here is an excellent thread talking about the subject, with actual numbers: Wood Studs vs Light Gauge Steel Studs . That thread has solid info by Rod Gervais. Rod is essentially an acoustic god (for all practical purposes) so assume anything he says is gospel barring _very_ convincing evidence to the contrary.


----------



## granroth




> Quote:
> Originally Posted by *ArturW*  /t/1509173/soundproofing-master-thread/200_100#post_24440615
> 
> 
> Thank you for quick reply. I'm not sure if I got it right. So using green glue with a layer (or two) of drywall etc between the joists will help me only marginally with the outgoing noise? If that's the case I will probably skip this part and save some money and work. When I said "recessed clips" I meant specifically the low profile GenieClip LB3. I used wrong words
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Will the fact that the walls are not decoupled in any way minimize the effect of the decoupled ceiling in any significant way?



Using GG with DW between the joists gives marginal improvement on outgoing ONLY if you are not decoupling. That is, you'll have made a serious dent in the sound that would have traveled through those spaces, but it would have been almost entirely nullified by the huge amount of sound coming directly through the studs.


But it sounds like you _are_ going to decouple the ceiling, in which case you are largely removing the joists as a direct sound path. At this point, you need to start thinking of mass and damping (and absorption to some degree). Ideally you'd do the majority of mass and damping on the "bottom" of the clips, so that the sound is lessened even before it gets to the decoupled joists, but that might be an issue with your ceiling height. In that case, your best bet for mass and damping is on the subfloor between the joists. Since the direct path of the joists is gone, the effect of the treatment between the studs could actually be audible.


----------



## elmerfudII

Anyone have ideas for isolating the sound from ceiling speakers (installed after the drywall is in) from the floor above ?


I've revisited the situation and come to the conclusion that the speakers do need to be installed in the ceiling.


Would a steel ceiling speaker enclosure like this help ?

http://www.amazon.com/Bogen-Recessed-Enclosure-Cone-Type-Loudspeakers/dp/B0013KJ0WU/ref=sr_1_fkmr0_1?ie=UTF8&qid=1393996263&sr=8-1-fkmr0&keywords=enclosed+ceiling+speaker+bogen 


Put a sound absorber over and around it ?


----------



## blazar

Next time I have the privelege to build another house and the land is inexpensive, I am going to just build the room off the side of the house with a hall or something separating the room from the rest of the house. Was considering building a hall all the way around the media room (to get a room within a room effect. Maybe do a library, bar area, media rack/closet or other stuff in the hall around the room. This would help isolate sound coming in and out most of the time.


It seems like this approach would solve a lot

of issues that we commonly face.


----------



## ArturW

Granroth, thank you for your responses. I think now I have a reasonable plan for soundproofing my basement.


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *elmerfudII*  /t/1509173/soundproofing-master-thread/200_40#post_24440964
> 
> 
> Anyone have ideas for isolating the sound from ceiling speakers (installed after the drywall is in) from the floor above ?
> 
> 
> I've revisited the situation and come to the conclusion that the speakers do need to be installed in the ceiling.
> 
> 
> Would a steel ceiling speaker enclosure like this help ?
> 
> http://www.amazon.com/Bogen-Recessed-Enclosure-Cone-Type-Loudspeakers/dp/B0013KJ0WU/ref=sr_1_fkmr0_1?ie=UTF8&qid=1393996263&sr=8-1-fkmr0&keywords=enclosed+ceiling+speaker+bogen
> 
> 
> Put a sound absorber over and around it ?



If you choose your ceiling speakers carefully your job is half done. There are vendors that make in wall/ceiling speakers in totally sealed enclosures. Others fire the sound out the back of the speaker as well as the front. I would grab with the sealed then install them inside backer boxes just like recessed lights. If you go the backless route you need to be careful in selecting a backer design that has the volume intended by the speaker designer.


I don't think much of the Bogen steel enclosure as a strategy.


----------



## cw5billwade




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/180#post_24439970
> 
> 
> I will say that I'm not sure what you mean by "recessed clips", especially in the context of sound proofing. The clips would need to be "resilient" (have a moveable layer, essentially) to be usable for decoupling.


this you install the blocking so that the IB-1 clip and hat channel just clears the floor joist. Then you put the 2 layers of DW and GG


----------



## cw5billwade




> Quote:
> Originally Posted by *ArturW*  /t/1509173/soundproofing-master-thread/180#post_24440615
> 
> 
> Thank you for quick reply. I'm not sure if I got it right. So using green glue with a layer (or two) of drywall etc between the joists will help me only marginally with the outgoing noise? If that's the case I will probably skip this part and save some money and work. When I said "recessed clips" I meant specifically the low profile GenieClip LB3. I used wrong words
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Will the fact that the walls are not decoupled in any way minimize the effect of the decoupled ceiling in any significant way?





> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/180#post_24440960
> 
> 
> Using GG with DW between the joists gives marginal improvement on outgoing ONLY if you are not decoupling. That is, you'll have made a serious dent in the sound that would have traveled through those spaces, but it would have been almost entirely nullified by the huge amount of sound coming directly through the studs.
> 
> 
> But it sounds like you _are_ going to decouple the ceiling, in which case you are largely removing the joists as a direct sound path. At this point, you need to start thinking of mass and damping (and absorption to some degree). Ideally you'd do the majority of mass and damping on the "bottom" of the clips, so that the sound is lessened even before it gets to the decoupled joists, but that might be an issue with your ceiling height. In that case, your best bet for mass and damping is on the subfloor between the joists. Since the direct path of the joists is gone, the effect of the treatment between the studs could actually be audible.


From sound proffing company link above you start with decoupled DW then DW/GG/DW then between joists


----------



## cw5billwade

Also do not forget the backer boxes for your lighting or all your efforts are wasted


----------



## cw5billwade




> Quote:
> Originally Posted by *ArturW*  /t/1509173/soundproofing-master-thread/180#post_24439815
> 
> 
> Hello,
> 
> I'm in process of finishing my basement (TV room). I've been researching soundproofing options for a while and my head is already spinning. The walls are concrete with 2x4 framing in front and some insulation in between. This is finished, I'm not touching it.
> I would still consider doing the GG and another layer of DW on the walls. I am sure it is the 1/2” light weight crap so a layer of 5/8” will be beneficial. If you decide to do this (highly recommended) do the first layer of DW or 1/2” OSB or 1/2" plywood on the ceiling first. Run acoustical caulk around the edges. Then put the second layer of 5/8” on the wall more acoustical caulk around the edges. Then the second layer of 5/8” DW ceiling. If you do this you will have more of a seal in the corners. Just because the wall is not decoupled does not mean all is lost. .
> 
> 
> I'm left with the ceiling. I want to limit noises going up and I am not concerned with noises coming from above. The subfloor and joists are exposed. I'm considering installing green glue between the joists as on the image in post #194 above. Will this offer any benefit in my case (limit noises going UP)? One layer vs two layers? The reason I'm considering this is that the ceiling is already below 7' and 2 layers of drywall and green glue are most likely not an option, decoupled or not.
> 2 layers of course are the best but there is a lot of effort check this thread http://www.avsforum.com/t/1442340/the-stonewater-cinema-build-thread/240#post_22887842
> 
> 
> I''m considering decoupling the ceiling (using recessed clips) with a single layer of .. preferably not drywall (I hate working with drywall + other finishing concerns in this particular case). Will plywood (mdf?) be much worse than drywall and is it even worth decoupling a single layer of anything? Is spending money on the ceiling worth if the will stay the way they are right now? They are attached to the rest of the framing above, after all.
> To save space I would use the IB-1 clips on the blocking like above and then 1/2" OSB or plywood for first layer then GG and 5/8" DW. Insure all layers are staggered. If going to the effort to decouple than you need to add the mass. Do not forget the backer boxes for the fixtures! You build and install them before the DW goes up so need this planed in advance.
> 
> 
> For insulation I have plenty of "pink stuff" available. I've been considering ultratouch or maybe roxul but I'm not sure if the gain would be significant over regular fiberglass insulation.
> pink
> 
> I'm prepared to spend some money, but I don't want to go crazy either, especially if the benefits would be small.
> 
> 
> I'd be happy to hear opinions and possible solutions for my room from the more experienced forum members. The room will most likely be generating some frequencies below 100hz too.
> 
> 
> Thank you
> 
> 
> Artur W.


Bottom line two layers of decoupled ceiling with R19 is by far the best bang for the buck. Time and money wise I would do this prior to doing the DW and GG in between the joist directly to the sub floor. If time and money is not in play then of course do both. Again I would do a layer of 5/8” on the walls with GG. I cannot blame you for not tearing it out. I sounds like it is built with insulation decoupled from the concrete so I think you will be ok just adding another layer.


----------



## elmerfudII




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/180#post_24443816
> 
> 
> Also do not forget the backer boxes for your lighting or all your efforts are wasted



Details, please.


----------



## cw5billwade




> Quote:
> Originally Posted by *elmerfudII*  /t/1509173/soundproofing-master-thread/210#post_24444873
> 
> 
> Details, please.


BIG help I did all my light fixtures in my Soffit and Coffer so I do not have pics of backer boxes


----------



## ArturW

Thanks, cw5billwade, for your comments. I did't think about ceiling lights yet and I'll have to take that into account. If I decide to get the 5 gallon bucket of green glue vs the tubes, what's the best way to apply it?


----------



## blazar




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/180#post_24443816
> 
> 
> Also do not forget the backer boxes for your lighting or all your efforts are wasted



I made this mistake...


----------



## cw5billwade

I found som Pics of backer Boxes

BIG made in the Ohio build http://www.avsforum.com/t/1377216/bigmouthindc-travels-to-ohio-to-help-build-a-dennis-erskine-designed-space#post_21301386 

Summer Fun http://www.avsforum.com/t/1421716/bigmouthindc-summer-fun-just-10-minutes-down-the-parkway#post_22252394 


from sumer fun build


> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1421716/bigmouthindc-summer-fun-just-10-minutes-down-the-parkway#post_22252394
> 
> 
> Green Glue backer boxes


----------



## cw5billwade

How to hang backer boxes


If on wood or OSB for first layer from bethesda build
http://www.avsforum.com/t/1310984/bethesda-build/150#post_20234072 


> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1310984/bethesda-build/150#post_20234072
> 
> 
> Jesto and I did a little work after he got home from work. We put up a 5/8 piece of plywood and some backer boxes in the projector mount location. It will get covered by the second layer of 5/8 drywall.
> 
> 
> The sheet is 48x32 inches.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here is a shot of Jesto at work,
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> we'll put some caulk around the Romex, the hole fits an old work box and a Panamax surge protector.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> We'll stick a bulk cable face plate over this hole also jamb some insulation up in there.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> We are now 100% ready for the drywall crew.


----------



## cw5billwade

if room in room from ohio build
http://www.avsforum.com/t/1377216/bigmouthindc-travels-to-ohio-to-help-build-a-dennis-erskine-designed-space#post_21301386 


If on clips and channel you can see the 2 boxes mounted using 2x2 suported on the channel
http://www.avsforum.com/t/1421716/bigmouthindc-summer-fun-just-10-minutes-down-the-parkway#post_22257465


----------



## BIGmouthinDC




----------



## cw5billwade

thanks Big hope you don't mid me quoting you from your other threads here.


----------



## panino

Anyone do backer boxes for wall sconces? Or better yet is there a good way to surface mount them so as to keep the room's "shell" intact? Assuming of course not putting them in columns.


----------



## ellisr63

Wouldn't it be easier to just make a soffit after the walls and ceiling are done, and then just seal the hole the wires are going into the soffit through?


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/200_40#post_24448462
> 
> 
> thanks Big hope you don't mid me quoting you from your other threads here.



not at all, saves me the time.


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/200_40#post_24449389
> 
> 
> Wouldn't it be easier to just make a soffit after the walls and ceiling are done, and then just seal the hole the wires are going into the soffit through?



The Bacon race theater is lit entirely with a perimeter of downward soffit lights, and ones bouncing off the screen, click in my signature. The soffit was built after the room was drywalled and the hole for the electrical wire was caulked.


----------



## blazar

There are some great new bulbs out there like long tube 2700k cfl bulbs which you can mount behind a moulding. Then you can brighten the room a LOT when not watching a movie. You get good color indirect lighting this way. We did this in the game room in our house and it looks great.


Also the new CREE led bulbs look great as far as longevity, brightness, color temp. I put 24 bulbs around the perimeter of our media room and they look phenomenal.


----------



## cw5billwade

I also built my soffits inside my sealed room. All of the electrical, speakers and other wiring and HVAC came into my room in the soffits. My wire then runs through the soffits for the lighting in my coffers and down the columns for speakers and sconce lighting. I did have some electrical and my front speakers come into the room in my stage.

HVAC
http://s629.photobucket.com/user/cw5billwade/media/theater/20130609_094159.jpg.html  
 
 

electrical and speakers
http://s629.photobucket.com/user/cw5billwade/media/theater/20130615_132458.jpg.html  

electrical CAT6 and HDMI for projector
 

stage


----------



## elmerfudII

No chance of me using backer boxes on the main floor unless I want to rip out all the ceiling drywall.


The best I can do is get ceiling speakers that are enclosed and put some insulation around them via the cutout hole.


----------



## afrost1


I am looking into soundproofing solutions for a shared wall between a two-story RV garage and a living unit on a limited budget and after gleaning all the knowledge I could from the wisdom on this and other sites, I think I have narrowed it down to two options. I would love some feedback or any anecdotal evidence to support either option. 

 

This all got started because we got a bid for Aircrete which was $2700, and we wanted to make sure we'd be happy with it since that's a lot more than we wanted to spend initially.

 

The shared wall is a 2x6 stud wall with fiberglass insulation, 39' long and ~16' high and on one side is a large garage filled with gym equipment, a drumkit, a boombox and a TV. The garage and first floor of the house sit on a shared slab, and there is a shared attic but the joists run lengthwise in the garage so they don't track over the shared wall into the living space. Our goal is to reduce the sound transmission to a level where we can use the garage for music and TV and maybe drums and it will be a tolerable white noise, and an imperceptible sound transmission of conversations or TV at a low volume. There will be short-term tenants in the living space, and eventually the garage may be turned into another living space.

 

The downstairs living area currently shares the garage wall in the bathroom, entryway and hall (where there is a door we will eliminate). The garage side has wooden paneling on the lower half of the walls, so about 8ft up. It also connects to another smaller 2 car garage under the upstairs, but we care less about sound coming into this 2nd garage (unless it travels up through the floor). The upstairs living area shares a wall with the garage in a bedroom, a bathroom, and the kitchen/living room. Currently the drywall is off in the bathroom and partially off in the kitchen.

 

After reading all of the articles on soundproofing sites mentioned in this thread and looking at a lot of test data and costs, we have it narrowed down to two options.

 

*Option 1: *Add green glue and a 2nd layer of 5/8" drywall to the upstairs bedroom, downstairs entryway and hallway where the door will be eliminated, adding insulation in old door space. We would not do the bathroom because we can't move the fixtures on that wall.

 

Add a layer of MLV to the kitchen and bathroom, then hang 5/8" drywall. The air gaps will be sealed with acoustical caulk as well. We would do this instead of green glue and more drywall because we have plumbing and outlets we cannot move to accommodate the extra depth. In this area we would also wrap putty on the electrical boxes and maybe replace the two heating ducts that go into the garage with flexible insulated ducting.

 

This option would cost ~$1200 before labor costs.

 

*Option 2:* On the garage side we would frame in another wall but 2x4 instead of 2x6, about an inch away from the existing wall. We would wrap the electrical outlets with putty from this side and probably make the two heat vents flexible (we like having the garage heated, so we cannot eliminate them). We would then add insulation, hang 5/8" drywall, add green glue, then hang more 5/8" drywall.

 

This option would cost ~$1200 before labor costs for basic R13 fiberglass in the new wall, and about $1400 if we used Roxul Safe n sound int he new wall. Labor costs will certainly be more than option 1, but we haven't priced that yet.

 

*Some of my questions:*

 

If we go with option 1, is the MLV in the kitchen and bath even worth it? It's about $550 dollars of the cost and it seems like the STC isn't all that great... We would love to do green glue and more drywall, but we don't have the space.

 

If we build the free-standing second wall but don't put on any green glue or a 2nd layer of drywall, does anyone have a guess as to what the STC would be? It could save us a lot of money to maybe add the green glue and 2nd layer of drywall at a later time.

 

If we pony up the cash to build the 2nd stud wall and add the 2 layers of drywall with green glue between, how much is flanking noise likely to be an issue considering that they share an attic (which is insulated with Roxul, can't remember how much--maybe R15 or 19?) but the joists don't run over the shared wall?

 

If we build a 2nd stud wall, should the spacing be 24" OC if we can do it that way? Our current studs are 16" OC and I have to check into what code is in this area.

 

If we build a 2nd stud wall and insulate, is it worth the ~$300 difference to use Roxul Safe n Sound instead of R13 fiberglass in the new wall?

 

Has anyone used or heard of Aircrete? I can't find much on it other than a few mentions of an STC of "up to 50," and that doesn't seem that encouraging...

 

 

 

Thanks in advance for any feedback. This forum, and specifically this thread, has been enormously helpful already and is such a wealth of knowledge on soundproofing issues, even for us non-HT geeks


----------



## granroth




> Quote:
> Originally Posted by *afrost1*  /t/1509173/soundproofing-master-thread/200_100#post_24457119
> 
> *Option 2:* On the garage side we would frame in another wall but 2x4 instead of 2x6, about an inch away from the existing wall. We would wrap the electrical outlets with putty from this side and probably make the two heat vents flexible (we like having the garage heated, so we cannot eliminate them). We would then add insulation, hang 5/8" drywall, add green glue, then hang more 5/8" drywall.
> 
> 
> This option would cost ~$1200 before labor costs for basic R13 fiberglass in the new wall, and about $1400 if we used Roxul Safe n sound int he new wall. Labor costs will certainly be more than option 1, but we haven't priced that yet.
> 
> *Some of my questions:*
> 
> 
> If we build the free-standing second wall but don't put on any green glue or a 2nd layer of drywall, does anyone have a guess as to what the STC would be? It could save us a lot of money to maybe add the green glue and 2nd layer of drywall at a later time.
> 
> 
> If we pony up the cash to build the 2nd stud wall and add the 2 layers of drywall with green glue between, how much is flanking noise likely to be an issue considering that they share an attic (which is insulated with Roxul, can't remember how much--maybe R15 or 19?) but the joists don't run over the shared wall?
> 
> 
> If we build a 2nd stud wall, should the spacing be 24" OC if we can do it that way? Our current studs are 16" OC and I have to check into what code is in this area.
> 
> 
> If we build a 2nd stud wall and insulate, is it worth the ~$300 difference to use Roxul Safe n Sound instead of R13 fiberglass in the new wall?



I would absolutely go with Option 2 -- it's not even close, in my mind. You're always going to have more bang for the buck if you can decouple, add mass, and dampen an ENTIRE wall, vs just segments of a wall. The only way I'd consider treating the living space is if you didn't have access to the garage space... which you do.


You could try building the wall with only one layer of drywall and see what kind of effect is has. If it's not good enough, then add another layer of drywall with Green Glue after. The latter solution would definitely be better, but the specifics of your situation make it hard to predict if it's necessary.


Make sure that you remove the existing drywall and paneling on the 2x6 wall, if you go with option 2! If you don't, then you will create a "triple leaf" scenario, which will actually makes things worse.


I don't know how much flanking noise you'll get in the shared attic. I'm really hoping that some of the true experts can comment on that, since I'm going to be in a similar situation in the not too distant future.


Spacing the wall at 24" OC is preferable if you are allowed to, since there are fewer "easy" pathways for the sound to go through. It's up to your local building code.


I've never seen any evidence that buying something like Safe n Sound is worth it over regular fiberglass. That is, it apparently _does_ make a difference, but it's so slight and so easily negated by other factors that the extra cost is almost never worth spending. Most of the experts recommend to use the cheapest fiberglass you can get.


You might also consider accomplishing your decoupling by using clips and channels instead of a second wall. It will likely be a bit more expensive BUT might be easier to pull off from a building code perspective.


----------



## ellisr63

I don't know if your garage is like ours, but on the side that joins the house they have OSB, and then a layer of drywall. We are going to add a layer of drywall with GG separating them on that wall, rather than try and remove the drywall plus OSB wall. We will then build a second 2x4 wall with a 1-3" gap between the old wall and the new one... layer of OSB, GG, and then drywall for the other 3 walls.


----------



## BIGmouthinDC

just a heads up that what you describe sounds like it may be prone to triple leaf effect. Not an expert on that science but I know enough that this may qualify. What that means is it may work against you for certain frequencies.


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/210#post_24457921
> 
> 
> just a heads up that what you describe sounds like it may be prone to triple leaf effect. Not an expert on that science but I know enough that this may qualify. What that means is it may work against you for certain frequencies.


I might be wrong but I don't think it will be a triple leaf effect... I have stripped the drywall off of all the walls and ceiling except for the one that has the drywall/OSB. If I understand correctly... If I left the drywall on,and then built another wall it would be triple leaf effect, correct? I most likely just didn't explain it completely.


----------



## BIGmouthinDC

I was thinking layer of DW inside the house, then the layer of OSB and DW in the garage, lastly the new wall? or is the OSB and drywall facing inside the house?


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/210#post_24458605
> 
> 
> I was thinking layer of DW inside the house, then the layer of OSB and DW in the garage, lastly the new wall? or is the OSB and drywall facing inside the house?



The house has one layer of drywall on the inside and on the garage side of the wall... it is as follows... OSB, and drywall. If we add another layer of drywall with GG in between the new layer it is still a double leaf isn't it? I am assuming it is done this way as a firewall, but I don't know for sure. When I looked at the GG website I thought it would still be a double leaf wall.


----------



## BIGmouthinDC

some diagrams of triple leaf here:

http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/210#post_24460849
> 
> 
> some diagrams of triple leaf here:
> 
> http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/


Ours is a double leaf according to the pictures as we only have one cavity in the wall. We are just adding one layer of drywall to the existing wall with GG. The rest of our walls are double stud walls like this siding- OSB- fiberglass insulation- cavity (between walls of about 3")- fiberglass insulation- OSB-GG-Drywall.


----------



## ellisr63

What will happen if a double wall construction is used and you use too thick of insulation and it touches the other walls insulation? Will it reduce it to a single wall setup?


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/200_100#post_24466321
> 
> 
> What will happen if a double wall construction is used and you use too thick of insulation and it touches the other walls insulation? Will it reduce it to a single wall setup?



I believe that the TRUE answer to this is that this is never part of any approved testing framework so no verified answers exist. There was a discussion on a similar topic to this early on in this thread ( Link ) but that aspect of the question was never fully answered.


Based on my further reading, the impression I got was that as long as the insulation wasn't overly compressed, that it wouldn't couple the walls. Fluffy insulation isn't a very good sound conductor. If, however, you _stuff_ insulation in, then yes, it can create a pretty decent vibration path.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/210#post_24467751
> 
> 
> I believe that the TRUE answer to this is that this is never part of any approved testing framework so no verified answers exist. There was a discussion on a similar topic to this early on in this thread ( Link ) but that aspect of the question was never fully answered.
> 
> 
> Based on my further reading, the impression I got was that as long as the insulation wasn't overly compressed, that it wouldn't couple the walls. Fluffy insulation isn't a very good sound conductor. If, however, you _stuff_ insulation in, then yes, it can create a pretty decent vibration path.



I just called the Soundproofing Company and they said no problem since it is not a hard surface. Whew that was a close one as I thought I was going to have to rip all the walls back down.


----------



## brwsaw




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/90#post_24323176
> 
> 
> Yep.
> 
> 
> I doubt I have to worry about vibrations with my current subs. I actually hope your right though, that's one problem I'd be happy to have.



I lied, I don't want rattles/vibrations any more.

Good news is it didn't become noticeable until I co located two sucky subs in the left rear corner.

Bad news the 4 subs in their current arrangement sounds really nice. -10 on the receiver but an almost natural/low rumble in your chest.


----------



## osufhall


Has anybody ever heard of this company?

 

http://soundproofwindows.com/cs1_stop_traffic_noise.html

 

I have a couple large windows that removing creates some issues and I would like to leave in place. Some of the testimonies are def. compelling, of course the source has to be considered since it is all coming from the companies website.


----------



## panino


I'm planning on running some 3/4" ENT conduit from my theater room (soundproofed) directly through the wall into an adjacent AV closet (not soundproofed).  Does anyone know of a means of "plugging" the conduit once the cables are run to insulate it and prevent sound leakage?  I want to be able to easily remove whatever insulation I use so that I can rerun cables as need be, so something permanent like acoustic caulk would not work.  Is there any type of removable foam or fluffy insulation worthwhile to put in it?  Or is plugging the conduit unnecessary?


----------



## BIGmouthinDC

I had some issues with conduit leaking sound and we stuffed the ends with tightly packed fiberglass insulation and that did the trick, I was hearing all this sound in the equipment room until we stuffed the ends.


----------



## granroth




> Quote:
> Originally Posted by *osufhall*  /t/1509173/soundproofing-master-thread/200_100#post_24477810
> 
> 
> Has anybody ever heard of this company?
> 
> http://soundproofwindows.com/cs1_stop_traffic_noise.html
> 
> 
> I have a couple large windows that removing creates some issues and I would like to leave in place. Some of the testimonies are def. compelling, of course the source has to be considered since it is all coming from the companies website.



No, I hadn't heard of them. Their claims of STC 48 with that kind of construction seems plausible, though. They are creating a Mass-Air-Mass partition and using laminated glass for one end (which has a damping factor). It's possible.


You might consider a removable window plug, though. It's be a lot cheaper and would likely do a much better job of soundproofing.


----------



## Reefdvr27

I am deciding if I should do double drywall and green glue or Genie Clips?


My question is if you do Genie Clips, do you still need to double drywall and green glue.


----------



## Chuck Miller

Yes. The Soundproofing Co. Recommends double 5/8" drywall on clips. The clips decouple; the DD and GG absorb. You need both. If you haven't talked with them I recommend you do. Also their recommended clips are much less costly than Genie or Whisper Clips.


Cheers!


Chuck


----------



## cw5billwade

yes either way you use DW/GG/DW

I used OSB on my first layer OSB/GG/DW


----------



## Reefdvr27




> Quote:
> Originally Posted by *Chuck Miller*  /t/1509173/soundproofing-master-thread/240#post_24494547
> 
> 
> Yes. The Soundproofing Co. Recommends double 5/8" drywall on clips. The clips decouple; the DD and GG absorb. You need both. If you haven't talked with them I recommend you do. Also their recommended clips are much less costly than Genie or Whisper Clips.
> 
> 
> Cheers!
> 
> 
> Chuck


Thanks Chuck and Bill,


What if I was to just do the clips and resilient bar and just 5/8". Would still be better than just plain old sheet rock right? Just looking for easier options.


----------



## cw5billwade

First you want Dry Wall furring channel (hat channel) not resilient bar. Unless that is something unique to the Genie Clips. I used IB-1 Clips from the Sound Proofing Company. I am not sure what you mean by easier? It is not hard to apply the GG on the back of DW and if you can hang one sheet of DW than it is not going to be any harder to hang a second layer. Just snap a line where the channels are on the sheet prior to applying the GG so you know where to screw. Earlier I think someone posed the difference between one sheet, two sheets and two sheets with GG. At the end of the day you will have decoupling with one sheet but not the mass or damping so you are eliminating two of the four elements of sound proofing.


----------



## Reefdvr27




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/240#post_24494790
> 
> 
> First you want Dry Wall furring channel (hat channel) not resilient bar. Unless that is something unique to the Genie Clips. I used IB-1 Clips from the Sound Proofing Company. I am not sure what you mean by easier? It is not hard to apply the GG on the back of DW and if you can hang one sheet of DW than it is not going to be any harder to hang a second layer. Just snap a line where the channels are on the sheet prior to applying the GG so you know where to screw. Earlier I think someone posed the difference between one sheet, two sheets and two sheets with GG. At the end of the day you will have decoupling with one sheet but not the mass or damping so you are eliminating two of the four elements of sound proofing.


I was just looking at your theater build pics and it looked like you used resilient bars for you hat channels?


Anyway, I am just confused with all this. I am not doing the job and I have to come up with the plan for all this stuff. I have to tell the builder what I want. I don't really know if he is familiar with this process or not . I gotta get with him tonight and discuss it. I discussed double drywall and GG, but I was not going to do the clips.


----------



## granroth

If you do an image search for "resilient channel", then you'll notice that they all have holes in them. Those holes are critical for resilient channels to work. Resilient channels are made to be screwed directly into the studs, without any clips at all. They work, but nowhere near as well as the other decoupling options. They are largely not worth the money.


Hat channel, now, is solid all the way around. It is not inherently a soundproofing component at all and is designed to be screwed directly into the studs. Never do this! In a soundproofing context, hat channel is designed to be inserted into clips that provide the decoupling from the studs. This setup is considered far superior to the stock resilient channels and is strongly recommended.


As far as what option you should go with... it 100% depends on what kind of performance you want out of the wall. Discarding the decoupling option and just doubling up on 5/8" drywall with Green Glue would give you a wall of roughly STC 52 (assuming wood studs 24" O.C.) Add insulation and you get another couple points. Decouple it with clips and channel and you get a few more. Is it worth it? It entirely depends on how much soundproofing you want.


Soundproofing can be a rather involved topic and there are soooo many ways that it can underperform based on your expectations. You could have a double wall with insulation, double layers of DW + GG on each side and assume you'll get a drop of 60 or so DBs... but if you have the walls coupled to the joists or if joints aren't sealed or if there's a door that's not properly done... well, you might not get anywhere near that in real world use.


I'm going to be bluntly honest here -- unless your contractor is well versed in soundproofing (a good hint of that is if he asks a lot of questions about your performance expectations during your meetings), there's a better than average chance that the end solution won't fit your expectations, unless your expectations are pretty low. There are just too many ways to screw it up compared to how few ways there are to do it right. Doing it right _requires_ that either your contractor or you be very well versed in soundproofing.


The links in the first post of this thread are very easy to read and contains tons of valuable info. They are a great start towards making you the knowledgable party in your contractor-client relationship. This thread and AVS Forum in general are also there to help you along.


----------



## Reefdvr27




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/240#post_24496028
> 
> 
> If you do an image search for "resilient channel", then you'll notice that they all have holes in them. Those holes are critical for resilient channels to work. Resilient channels are made to be screwed directly into the studs, without any clips at all. They work, but nowhere near as well as the other decoupling options. They are largely not worth the money.
> 
> 
> Hat channel, now, is solid all the way around. It is not inherently a soundproofing component at all and is designed to be screwed directly into the studs. Never do this! In a soundproofing context, hat channel is designed to be inserted into clips that provide the decoupling from the studs. This setup is considered far superior to the stock resilient channels and is strongly recommended.
> 
> 
> As far as what option you should go with... it 100% depends on what kind of performance you want out of the wall. Discarding the decoupling option and just doubling up on 5/8" drywall with Green Glue would give you a wall of roughly STC 52 (assuming wood studs 24" O.C.) Add insulation and you get another couple points. Decouple it with clips and channel and you get a few more. Is it worth it? It entirely depends on how much soundproofing you want.
> 
> 
> Soundproofing can be a rather involved topic and there are soooo many ways that it can underperform based on your expectations. You could have a double wall with insulation, double layers of DW + GG on each side and assume you'll get a drop of 60 or so DBs... but if you have the walls coupled to the joists or if joints aren't sealed or if there's a door that's not properly done... well, you might not get anywhere near that in real world use.
> 
> 
> I'm going to be bluntly honest here -- unless your contractor is well versed in soundproofing (a good hint of that is if he asks a lot of questions about your performance expectations during your meetings), there's a better than average chance that the end solution won't fit your expectations, unless your expectations are pretty low. There are just too many ways to screw it up compared to how few ways there are to do it right. Doing it right _requires_ that either your contractor or you be very well versed in soundproofing.
> 
> 
> The links in the first post of this thread are very easy to read and contains tons of valuable info. They are a great start towards making you the knowledgable party in your contractor-client relationship. This thread and AVS Forum in general are also there to help you along.


Thanks for a good detailed post. It was very helpful and useful info.










I am not building a beautiful theater like some of the theaters in this thread. I am more or less building a media/theater room. One row of chairs, front stage and fixed screen, just some place for me to go and get away. I am not doing columns or fancy trim work or fabric walls etc.. I am just doing a plain room with nice treatments like acoustic panels and corner traps. It will be a beautiful room when I am done, but I am just getting the basic room done and will plan on future upgrades. Unfortuantly there is some construction that has to be done to the room and that is going to eat up some money that could be used. I also have to add a heating a cooling unit and that is going to be in the neighborhood of $5K. I have to do this as the room has no way to hook up to my HVAC units. We looked at other options and a ductless heat pump/AC unit was the best option. I also have to remove 9 windows and reframe the windows and reside the exterior of the house. Little things like this are killing me. This is why I am looking for a simpler way to sound proof. I have been searching thread after thread on here and some people are saying it is not worth it to double drywall and others say it is a must. I am going to have a sit down with the builder before we go, he is a perfectionist and is probably one of the best guys around. I am lucky to have him do this. I say things and he finishes the sentence, things like that. So it can be done right. I just have to educate myself so I know what is right and what I want done.


Again Thanks for the info and future help. I believe I am going to start my thread and get some helpful advise.


I am attaching a pic of what I want my room to look like


----------



## cw5billwade

Reefdvr I like the name I am PADI certified and did many dives of off Hawaii. I really love it but my Asthma from my vacations in Iraq and Afghanistan prevents me from doing that now. Now I just Snorkel but that takes a few puffs of my inhaler to do so. O well back to our discussion. Pm me if you want to discuss this sport further


If you contact the Sound Proofing Company mentioned many times on this thread and talk to them and tell them what you are doing they will determine the needs if you purchase the clips and green glue from them they will provide you with detailed instructions that the contractor will understand (may even provide it ahead of time). I knew nothing about sound proofing 13 months ago! There is so much information on their web site.


----------



## cgott42




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread#post_24171842
> 
> 
> There's single doors: wood hollow core, steel hollow core, wood solid core, steel fire door (aka steel hollow core, thicker steel, filled with insulation, often with better seals), custom door, professional acoustical doors.
> 
> There's double doors: communicating doors (aka tandem doors, width of the double stud wall) , airlock doors (one man room), and lobby doors (a real room).
> 
> ...
> 
> Doors are remarkably sensitive to the seals they have, so a simple study of door types while indicative is not predictive of installed results. I seem to recall a bunch of multi frequency test results for single doors, where they glued the door into a test frame.



Given that the soundproofing of the door is very sensitive to the sealing (small gaps let a lot of sound out) What about the door jambs - i.e. I am thinking of a solid core door + a 1x1 frame filled with insulation + DW+GG+DW. However isn't all the layers of DW,GG on the door a waste if it's surrounded by 1" of door jamb to easily transmit the sound - what do people do as every inch of the room is covered in 3 layers of DW +GG on top of the wood joists to prevent the wood joists from transmitting sound - and here on the door jamb is a clear path?


----------



## granroth




> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/200_100#post_24498634
> 
> 
> Given that the soundproofing of the door is very sensitive to the sealing (small gaps let a lot of sound out) What about the door jambs - i.e. I am thinking of a solid core door + a 1x1 frame filled with insulation + DW+GG+DW. However isn't all the layers of DW,GG on the door a waste if it's surrounded by 1" of door jamb to easily transmit the sound - what do people do as every inch of the room is covered in 3 layers of DW +GG on top of the wood joists to prevent the wood joists from transmitting sound - and here on the door jamb is a clear path?



The door frame isn't a big contributor to sound leakage. I'll quote from Rod Gervais' excellent book "Home Recording Studio: Build It Like the Pros", emphasis added by me:


> Quote:
> I’ll let you know right now that this is one place I don’t worry about maintaining the separation of wall assemblies with the frames, even when using totally separated assemblies. When it comes to carrying a door that might weight well over 300 pounds (if you build them like I do), or even standard solid core doors, you do not want your door frame attached to a stud that can move over the years. As I noted above, *tests have proven that a through jamb does not effectively lessen the total isolation value of a wall assembly to any great degree.* So don’t worry about any minuscule amount of isolation you may lose. Just build the frame straight through the cavity.
> 
> 
> I would also recommend against using the standard 5/8" jambs that are typically used with pre-hung doors, because the jambs will not hold up against the weight of the “super door” assembly. Often, neither will a standard hinge. Use 5/4 stock lumber for your frames; 3/4" pine is fine for door stops. Then use a variety of special seals to make this baby airtight.



If you are still worried about it (and I wouldn't be -- Rod is a world class soundproofing expert and if he's fine with it, so am I), then you could just cut a 1/4" kerf in the jamb and fill it in with backer rod and acoustic caulk (as recommended by Ted White). That'll definitely keep it decoupled... but as Rod said, you likely won't notice the difference in noise and you might end up with a wobbly door.


----------



## cgott42




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/240#post_24500586
> 
> 
> The door frame isn't a big contributor to sound leakage. I'll quote from Rod Gervais' excellent book "Home Recording Studio: Build It Like the Pros", emphasis added by me:
> 
> If you are still worried about it (and I wouldn't be -- Rod is a world class soundproofing expert and if he's fine with it, so am I), then you could just cut a 1/4" kerf in the jamb and fill it in with backer rod and acoustic caulk (as recommended by Ted White). That'll definitely keep it decoupled... but as Rod said, you likely won't notice the difference in noise and you might end up with a wobbly door.


thanks, so to make sure I got it correct:

1.25" door jambs from stock lumber (is this OK?)

, screwed in directly to the wall studs

+ 3/4" pine for the door stops (is this OK?).

re: the door itself - is this a good strategy: solid core door (like this ?) +3/4" pine frame around the back with hollow cavity filled with insulation + DW+GG+DW on back - or should I do without the insulation gap, and just have Door+GG+DW+GG+DW?



what do most people (that aren't spending the big $$$ on sound proofing doors) do? Ted's website mentions using pre-hung interior doors - which would imply nothing added to it (as the add'l layers won't close on the prehung jambs) - unless I'm missing something - this would seem to be a big gap as the entire room covered in DW+GG+DW+GG+DW and this 3'x6' spot w/just a single piece (albeit 1.75" thick - making it as thick as the DW+GG+DW+GG+DW - but no damping.)


----------



## kmhvball


I am in the planning stages of my Home Theater build, and the 'doors' are still a big question for me.   I have been working with a gentleman and he is proposing using communicating doors, spread by (at least) 3" air space.  The doors he is proposing are 1/4" Laminated Glass doors.  He says using two of those in a communicating door fashion will get in the mid-50's STC rating.

 

I wondered if anyone had used something like this, or, if anyone had attached a full size laminated glass 'sheet' to a solid core door?   I would think that might improve the STC further from a 'mass' perspective if nothing else.  I have looked around on the forum some, and most of the 'do it yourself' doors don't seem to reference laminated glass, mostly multiple MDF sheets, etc.   

 

Thanks,


Kevin


----------



## cgott42




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/240#post_24500586
> 
> 
> The door frame isn't a big contributor to sound leakage. I'll quote from Rod Gervais' excellent book "Home Recording Studio: Build It Like the Pros", emphasis added by me:
> 
> If you are still worried about it (and I wouldn't be -- Rod is a world class soundproofing expert and if he's fine with it, so am I), then you could just cut a 1/4" kerf in the jamb and fill it in with backer rod and acoustic caulk (as recommended by Ted White). That'll definitely keep it decoupled... but as Rod said, you likely won't notice the difference in noise and you might end up with a wobbly door.



Also what about the hole for the door knob - it seems like a real compromise of sound containment having a 2" hole bored straight through the door. What do people do?


----------



## granroth




> Quote:
> Originally Posted by *kmhvball*  /t/1509173/soundproofing-master-thread/200_100#post_24502498
> 
> 
> I am in the planning stages of my Home Theater build, and the 'doors' are still a big question for me.   I have been working with a gentleman and he is proposing using communicating doors, spread by (at least) 3" air space.  The doors he is proposing are 1/4" Laminated Glass doors.  He says using two of those in a communicating door fashion will get in the mid-50's STC rating.
> 
> 
> I wondered if anyone had used something like this, or, if anyone had attached a full size laminated glass 'sheet' to a solid core door?   I would think that might improve the STC further from a 'mass' perspective if nothing else.  I have looked around on the forum some, and most of the 'do it yourself' doors don't seem to reference laminated glass, mostly multiple MDF sheets, etc.



The communicating doors you describe sound a lot like a window and Rod talks about that in some detail in his "Home Record Studio: Build It Like the Pros" book (and if it seems like I bring that book up a lot, it's because that book is pure gold when it comes to soundproofing).


First, laminated glass is absolutely the way to go. The plastic layer in between the glass layers has a damping effect similar what Green Glue gets you with drywall. It's the only glass that's worth using in soundproofing applications.


Second, having communicating doors that are properly sealed and have laminated glass will definitely give an STL similar to, say, a solid core door.


HOWEVER, your gentlemen's quote of a mid-50s STC for that combination seems a bit high. The problem is mostly with the thickness of the glass. 1/4" is very very thin and simply doesn't have enough mass to have the same impact that a wall will have. As a point of comparison, the Overly Door Company sells extremely expensive acoustic doors with ratings of up to STC 55. Those doors have special steel frames and use laminated glass sheets of 1/2" and 3/4" thicknesses! Two sheets of 1/4" glass simply can't hold a candle to that amount of mass... and with all that, they still have "only" STC 55.


Here's a quote from Rod on how thick is enough:


> Quote:
> Remember the basics—it’s all about mass. That doesn’t change just because the material changes. For example, if you have two layers of 5/8" drywall on each side of your wall, then the mass = 2×2.625 psf (per layer) or 5.25 psf of mass (on each side of the wall) for the drywall. Standard plate glass (annealed) weighs 1.64 psf for glass 1/8" thick. Thus, a 3/8" piece of annealed weighs 4.92 psf (a little light), so you need a piece of 1/2" for one side and 3/4" for the other. Thus, the glass weights will be 6.56 psf and 9.84 psf, respectively.



Laminated glass has damping qualities that plate glass doesn't, but it weighs roughly the same. Therefore, your two pieces of 1/4" glass would have 6.56psf, compared to the typical 10.25psf you'd see on the walls (and the 21psf found in the Overly door).


As far as attaching the glass to a solid core door, I assume you mean instead of drywall or MDF? Maybe for decorative purposes? It certainly wouldn't be as effective as either drywall or MDF as both have more mass. It would be at least somewhat effective, though, so if that's the look you want, then it could be okay.


----------



## granroth




> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/200_100#post_24503816
> 
> 
> Also what about the hole for the door knob - it seems like a real compromise of sound containment having a 2" hole bored straight through the door. What do people do?



Here's what JH Brandt has to say about that in his "Building Studio Doors" PDF (linked in the second post of this thread):


> Quote:
> I recommend the mortised type of lockset [..], if you can get them. Buy commercial grade. They are much easier to seal. If not, you can use the standard, round hole, drilled through lockset. But care must be taken to seal the lockset. A poorly sealed lockset/handle alone can ruin the isolation provided by a good heavy door.
> 
> 
> Seal the lockset by purchasing some thin closed cell foam - like gasket material. Lay your door handle on the sheet and draw around it. Cut it out like a gasket & poke holes where the lever shaft will be,
> 
> insert into handle and install on the door. Don’t use caulk, as it will 'gum up the works'.



So yes, if you really want the ultimate soundproof door, then you'll want a mortised lockset since there are no holes that go all the way through. However, since we are talking about a relatively small opening, if you properly seal it, then it would probably be "good enough". It is notable to me that Rod doesn't talk about the door hardware at all (other than a commercial door closer and commercial hinges) in his book.


----------



## cgott42

How about this for a door http://www.homedepot.com/p/Steves-Sons-36-in-x-80-in-Composite-Unfinished-Flush-Interior-Door-Slab-Q68FHFCNAC99/100086151 ?


Btw - great thread and kudos on creating it.


----------



## granroth

I'm going to talk about mass a little bit, since it comes up pretty often. Most of what follows is me regurgitating what the experts say, plus a few innocuous thoughts of my own.


Sound always wants to "escape" via the weakest link in your soundproofing chain. One of the biggest differences in your room is often going to be the relative mass found in the various components of the room. Sound will want to escape through whatever part of the room has the least amount of mass. As such, you will want to go to some amount of effort to keep the amount of mass for all parts of your room as comparable as possible.


The two weakest links tend to be either the ceiling or the door (or windows), as people often forget about the former and don't do enough for the latter. If you have a double wall each with double layers of drywall and an average mass of 8.8 pounds per square foot (psf) and then install a 1 3/8" solid core door at only 3.5psf, then you will absolutely be leaking sound through that door -- and quite a bit.


So the goal is to calculate what your mass is in your walls and then match that (or get as close as possible) in all of the other components.


Let's start with some density figures. Unfortunately, density varies quite a bit based on the specific product you buy. There is a range for all types of materials. 5/8" Type X drywall tends to be between 2.2psf and 2.8psf. I'm going to go with 2.2psf mostly because that's what USG gives in their SHEETROCK product data sheet.


Solid core doors vary by type and by thickness. Assume 4.5psf for a 1-3/4" solid core door.


3/4" MDF varies massively. I've seen figures as low as 2.3psf and as high as 3.2psf. I just weighed a sheet of 97"x49" 3/4" MDF I bought from Home Depot and its 85.3lbs gives us 2.585psf.


3/4" OSB also varies quite a bit., with a range that overlaps the MDF range. I happen to have some sheets of that, too, and their 76.8lbs comes to 2.4psf.


3/4" Ply tends to be around 2.3psf. Same variability as above.


1/8" laminated glass is 1.64psf.


With that in mind, if you have a wall with double layers of 5/8" drywall on both sides, then your mass is 2.2*4 = 8.8psf


A solid core door by itself has just under half that amount of mass. Two of them in an airlock configuration gives us 9psf, which is enough on its own to match the walls. If you only have one door, then adding a sheet of 3/4" MDF to it gives you 7.1psf. Closer. Add another sheet of 5/8" drywall and you have 9.3psf. For instance, you could have a sheet of drywall, then Green Glue, then the 1-3/4" solid core door, and then a slightly smaller sheet of 3/4" MDF in a "bank vault" format. That'll match up with the mass (and damping) in your walls nicely.


Windows are tougher. If you have a "normal" dual pane window, then you're looking at two sheets of glass at 3.28psf. You'll need to create a plug with another 5.5psf to match the walls. Make the plug with a couple layers of MDF and maybe a layer of drywall, and there you go (3.28 + (2*2.585)+2.2 = 10.65psf). Note that this might not be perfectly accurate since a window implies an exterior wall and those walls can definitely have higher mass than your interior wall of 8.8psf.


Anyway, there are more factors than just mass (decoupling often is more important overall), but it absolutely matters and the previous bits were some thoughts on how to work with it.


----------



## granroth




> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/200_100#post_24505454
> 
> 
> How about this for a door http://www.homedepot.com/p/Steves-Sons-36-in-x-80-in-Composite-Unfinished-Flush-Interior-Door-Slab-Q68FHFCNAC99/100086151 ?



The general advice I've seen is that all solid core doors (as opposed to all wood doors) are close enough to the same as to make no difference. So yeah, that one looks good.


Curious, that door is 3.95psf, which differs quite a bit from the 4.5psf quote I found for a "typical" solid core door. I'm not sure what to make of that...


----------



## thestoneman

I've done a lot of reading on soundproofing and I'm trying to get the best overall results. Clips/channel, DD & GG will give me the desired effect, but will lower my ceiling to a level I would like to avoid. I am therefore looking for the best results without losing ceiling height. I don't need an A+ result (total sound isolation)...I'll take a B- (very tolerable levels of sound escaping to 1 floor above and complete sound isolation from 2 floors above)



Can I overcompensate with added layers of Roxul (I have 12" joists)?


Will eliminating the RSIC clips render the DD/GG a waste of time and money?


Would adding a 3/8" thick neoprene strip along the joist give me a similar result as the RSIC clips or is all about the points of contact...not the material making the contact?



I will sacrifice the height in my media room if the RSIC, DD, GG, Roxul is the only way to get SIGNIFICANT soundproofing, but if the clips only take me from a B- to the A+...I'll take the B-.


----------



## BIGmouthinDC

Just checking to be sure you are aware of the method of running the clips and channel parallel to the joists and only give up 1/2 of an inch extra.


----------



## granroth




> Quote:
> Originally Posted by *thestoneman*  /t/1509173/soundproofing-master-thread/200_100#post_24505510
> 
> 
> I've done a lot of reading on soundproofing and I'm trying to get the best overall results. Clips/channel, DD & GG will give me the desired effect, but will lower my ceiling to a level I would like to avoid. I am therefore looking for the best results without losing ceiling height. I don't need an A+ result (total sound isolation)...I'll take a B- (very tolerable levels of sound escaping to 1 floor above and complete sound isolation from 2 floors above)



As Big mentioned, it's possible to use clips and lose only 1/2". See this post above for details: Post #208 


> Quote:
> Originally Posted by *thestoneman*
> 
> Can I overcompensate with added layers of Roxul (I have 12" joists)?



No. Absorption does the least amount of soundproofing of the four primary elements (Decoupling, Mass, Damping, Absorption). It does help, but generally only after you've decoupled and added mass.


> Quote:
> Originally Posted by *thestoneman*
> 
> Will eliminating the RSIC clips render the DD/GG a waste of time and money?



No. Mass and damping both play a big role in soundproofing, independent of decoupling. You're only losing 1/2", though, so if money is not the problem, then I'd strongly suggest using the clips.


----------



## thestoneman




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/240#post_24505697
> 
> 
> Just checking to be sure you are aware of the method of running the clips and channel parallel to the joists and only give up 1/2 of an inch extra.



I think I know what you are referring to. I would need to attach the clips to recessed blocking between the joists? This might be the answer. Currently I have nothing between my joists and was going to run blocking anyway to stiffen the floor above.



...and thanks granroth for your input. I am so glad I asked...I feel a lot better about what I need to do moving fwd.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/240#post_24505490
> 
> 
> I'm going to talk about mass a little bit, since it comes up pretty often. Most of what follows is me regurgitating what the experts say, plus a few innocuous thoughts of my own.
> 
> 
> Sound always wants to "escape" via the weakest link in your soundproofing chain. One of the biggest differences in your room is often going to be the relative mass found in the various components of the room. Sound will want to escape through whatever part of the room has the least amount of mass. As such, you will want to go to some amount of effort to keep the amount of mass for all parts of your room as comparable as possible.
> 
> 
> The two weakest links tend to be either the ceiling or the door (or windows), as people often forget about the former and don't do enough for the latter. If you have a double wall each with double layers of drywall and an average mass of 8.8 pounds per square foot (psf) and then install a 1 3/8" solid core door at only 3.5psf, then you will absolutely be leaking sound through that door -- and quite a bit.
> 
> 
> So the goal is to calculate what your mass is in your walls and then match that (or get as close as possible) in all of the other components.
> 
> 
> Let's start with some density figures. Unfortunately, density varies quite a bit based on the specific product you buy. There is a range for all types of materials. 5/8" Type X drywall tends to be between 2.2psf and 2.8psf. I'm going to go with 2.2psf mostly because that's what USG gives in their SHEETROCK product data sheet.
> 
> 
> Solid core doors vary by type and by thickness. Assume 4.5psf for a 1-3/4" solid core door.
> 
> 
> 3/4" MDF varies massively. I've seen figures as low as 2.3psf and as high as 3.2psf. I just weighed a sheet of 97"x49" 3/4" MDF I bought from Home Depot and its 85.3lbs gives us 2.585psf.
> 
> 
> 3/4" OSB also varies quite a bit., with a range that overlaps the MDF range. I happen to have some sheets of that, too, and their 76.8lbs comes to 2.4psf.
> 
> 
> 3/4" Ply tends to be around 2.3psf. Same variability as above.
> 
> 
> 1/8" laminated glass is 1.64psf.
> 
> 
> With that in mind, if you have a wall with double layers of 5/8" drywall on both sides, then your mass is 2.2*4 = 8.8psf
> 
> 
> A solid core door by itself has just under half that amount of mass. Two of them in an airlock configuration gives us 9psf, which is enough on its own to match the walls. If you only have one door, then adding a sheet of 3/4" MDF to it gives you 7.1psf. Closer. Add another sheet of 5/8" drywall and you have 9.3psf. For instance, you could have a sheet of drywall, then Green Glue, then the 1-3/4" solid core door, and then a slightly smaller sheet of 3/4" MDF in a "bank vault" format. That'll match up with the mass (and damping) in your walls nicely.
> 
> 
> Windows are tougher. If you have a "normal" dual pane window, then you're looking at two sheets of glass at 3.28psf. You'll need to create a plug with another 5.5psf to match the walls. Make the plug with a couple layers of MDF and maybe a layer of drywall, and there you go (3.28 + (2*2.585)+2.2 = 10.65psf). Note that this might not be perfectly accurate since a window implies an exterior wall and those walls can definitely have higher mass than your interior wall of 8.8psf.
> 
> 
> Anyway, there are more factors than just mass (decoupling often is more important overall), but it absolutely matters and the previous bits were some thoughts on how to work with it.



Are you adding the MDF to both sides of the door or are you talking about just to one side of the door to get those ratings?


----------



## kmhvball

How do I think about a mass vs dampening trade off?


Let's say there was 1/4" drywall, would it be better to use two sheets of 1/4" drywall with green glue/ dampening in between or a single theoretical 3/4" sheet?


This gets back to the laminated glass having both a mass number and also a dampening effect based on the inner layer. The notion being maybe a single 1/4" laminated glass sheet actually might deliver a greater total benefit than a larger mass structure with out similar dampening.


Maybe a factor like 1 x mass/psF x 1.Z where the Z represents a multiplier effect of dampening in the mass comparison equation.


I realize this paints an either / or scenario and many times in practice it is a both scenario (I.e. Add green glue then a MDF/ drywall sheet), but wasn't sure how to think of the dampening benefit in the context of a mass calculation.


I appreciate you sharing your thoughts and insights!


----------



## kmhvball

The website specifications seem strange...assembled depth 1.75", but door thickness 1.375". I would think for a slab door, those would be the same. If I do the psF on the 1.375, it is closer to 5. Not sure about the 4.5, although I have seen qualitative statements that a slab door weighs more than a door that has a design cut into it, so maybe that contributes to the difference?


----------



## cgott42




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/240#post_24505505
> 
> 
> The general advice I've seen is that all solid core doors (as opposed to all wood doors) are close enough to the same as to make no difference. So yeah, that one looks good.
> 
> 
> Curious, that door is 3.95psf, which differs quite a bit from the 4.5psf quote I found for a "typical" solid core door. I'm not sure what to make of that...



thanks before I go out and buy it and have cut to size. Please confirm :

(a) given that my *actual opening size is 38" x 78.5"* - and the actual width of the door jambs are 1" - *what size should the door slab be cut to?*






(b) Also - being that we add layers on top of the door slab - is there a benefit to getting a prehung door? Woudln't the add'l layers require moving the door stop, and the add'l weight be too much for the door jambs/hinges?

2Q's I think I know but to be sure:

(c) I assume I should not get it "bored" - but instead cut my own holes just what's needed for the door handle


----------



## cw5billwade




> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/240#post_24498634
> 
> 
> Given that the soundproofing of the door is very sensitive to the sealing (small gaps let a lot of sound out) What about the door jambs - i.e. I am thinking of a solid core door + a 1x1 frame filled with insulation + DW+GG+DW. However isn't all the layers of DW,GG on the door a waste if it's surrounded by 1" of door jamb to easily transmit the sound - what do people do as every inch of the room is covered in 3 layers of DW +GG on top of the wood joists to prevent the wood joists from transmitting sound - and here on the door jamb is a clear path?


My door jamb is decoupled like Mario did with his build he has detaled instructions. I did not. http://www.avsforum.com/t/1208912/the-cinemar-home-theater-construction-thread/1680#post_21945030


----------



## ellisr63

My friend has several solid core wood doors and metal doors... How do I decide which is better for soundproofing? I have heard that metal is better but then I have heard that wood is better. I am planning on adding a layer of MDF (on the HT side) to whatever door I use.


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/200_100#post_24507290
> 
> 
> Are you adding the MDF to both sides of the door or are you talking about just to one side of the door to get those ratings?



In my example, there was only the one sheet of MDF, in a "bank vault" style. See this post for an example of what that might look like (ignoring the sand part): Post 44 


It's decently common to add more than one panel of MDF to a door, though -- the more the better, for the most part. There are some very good links to building doors in the second post of this thread.


> Quote:
> Originally Posted by *kmhvball*  /t/1509173/soundproofing-master-thread/200_100#post_24507486
> 
> 
> How do I think about a mass vs dampening trade off?



I'm actually not sure. All of the tests I've seen compared equal amounts of mass either with damping or without. I don't recall any tests that compared smaller amounts of mass with damping compared to larger amounts of mass. I'm not going to guess, either, since acoustic results are often not intuitive and only lab tests really matter in the end.


> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/200_100#post_24509301
> 
> 
> My friend has several solid core wood doors and metal doors... How do I decide which is better for soundproofing? I have heard that metal is better but then I have heard that wood is better. I am planning on adding a layer of MDF (on the HT side) to whatever door I use.



Steel, if has a solid core of some sort. The door is all about mass, and since steel weighs significantly more than wood, it's going to have the edge. It's no coincidence that commercial acoustic doors are nearly always made of steel.


----------



## granroth




> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/200_100#post_24507554
> 
> 
> thanks before I go out and buy it and have cut to size. Please confirm :
> 
> (a) given that my *actual opening size is 38" x 78.5"* - and the actual width of the door jambs are 1" - *what size should the door slab be cut to?*



A typical rough opening for a normal 36" door would be 38" x 82-1/2". This is an extra 2" for the width and an extra 2-1/2" for the height. The actual door will typically be 3/8" skinnier than the advertised size, though, so that it can swing shut without binding. That is, a 36x80 door will really be 35-5/8"x80". This all assumes a typical 5/8" jamb, which gives a total of 3/4" of shimming room (and an additional just over an inch of space on the bottom for the flooring).


We're talking about 1" jambs, though, so the recommended rough size for a 36x80 door would be 38-3/4" x 83". Since your opening is already set, then working backwards would mean a door of 34-7/8" x 75-1/2" (if my math is right).


One thing to keep in mind -- the rough opening has those tolerances because it assumes the frame will likely not be truly plumb and level. If yours is, then you probably get away with less shimming room and can add maybe 1/2" to each dimension.


> Quote:
> Originally Posted by *cgott42*
> 
> (b) Also - being that we add layers on top of the door slab - is there a benefit to getting a prehung door? Woudln't the add'l layers require moving the door stop, and the add'l weight be too much for the door jambs/hinges?



If you have a full thickness MDF slab on the "outside", then yes, the door stop will need to move. If you do it bank vault style, then you'll just be creating another inner door stop in addition to the original. Honestly, I think most people who create mass-added doors make their own jambs, too. The additional weight will surely be too much for the hinges it comes with -- those can sometimes be swapped out for commercial ball bearing hinges of the same size.


I am curious where you are getting the door jamb thickness of 1" if you are talking about pre-hung doors. Most that I've seen use 5/8" jambs. Also, most pre-hung doors have 3-1/2" hinges, which are slightly harder to come by in commercial ball bearing form.


SO... if you really want to go whole-hog on the door, then I'd recommend skipping the pre-hung variants and make your own jamb. Warning: it's not at all easy. See this earlier post for a link to a very detailed example on making a custom jamb.


> Quote:
> Originally Posted by *cgott42*
> 
> (c) I assume I should not get it "bored" - but instead cut my own holes just what's needed for the door handle



Yep, most doors I've bought that didn't come with the hardware also required you to bore your own holes. At least that part is easy.


----------



## blazar

I got lucky with a doormaker nearby and i was able to design the whole thing with him with plenty of lead time.


On a side note, double doors look great and make moving furniture and big equipment easier but are harder to soundproof without specialty products/manufacturing.


----------



## ellisr63

If I get 2 solid core steel doors... separated by a 4' space (hallway), and attach 3/4" MDF on both sides of 1 door, and the inner side of the other (with screws and GG) I should be set correct? I would be sealing the doors too.


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/200_100#post_24510064
> 
> 
> If I get 2 solid core steel doors... separated by a 4' space (hallway), and attach 3/4" MDF on both sides of 1 door, and the inner side of the other (with screws and GG) I should be set correct? I would be sealing the doors too.



Absolutely! In fact, in Rod's book, he says that if you're going to go with communicating doors, then you don't need to the extra mass. Both doors just need to be very well sealed (automatic door bottoms; gaskets; etc). Having another layer of MDF plus GG just kicks it up a notch.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/270#post_24510416
> 
> 
> Absolutely! In fact, in Rod's book, he says that if you're going to go with communicating doors, then you don't need to the extra mass. Both doors just need to be very well sealed (automatic door bottoms; gaskets; etc). Having another layer of MDF plus GG just kicks it up a notch.



Thanks, I wasn't sure if a 4' long hallway would still qualify as communicating doors.


----------



## granroth

Sure. In fact, it's not uncommon for theaters with more space to have a vestibule of sorts -- an air lock room, if you will. It has benefits beyond just the doors, too, since the room can be treated itself.


But that does bring up a necessary point. If the hallway space between the two doors isn't treated, then you have essentially created a weak link in your chain where sound can escape. It definitely will lessen the impact of your second door.


Mind you, even having one properly sealed steel door with MDF+GG gives pretty kick-ass soundproofing, so absolutely anything you do beyond that is just incremental gravy.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/270#post_24510444
> 
> 
> Sure. In fact, it's not uncommon for theaters with more space to have a vestibule of sorts -- an air lock room, if you will. It has benefits beyond just the doors, too, since the room can be treated itself.
> 
> 
> But that does bring up a necessary point. If the hallway space between the two doors isn't treated, then you have essentially created a weak link in your chain where sound can escape. It definitely will lessen the impact of your second door.
> 
> 
> Mind you, even having one properly sealed steel door with MDF+GG gives pretty kick-ass soundproofing, so absolutely anything you do beyond that is just incremental gravy.


Thanks,

The hallway will be treated just like the rest of the room... Except that the water heater and furnace are in a cubby hole along the one wall and will only have standard drywall. I am looking at the possibility of a steel door of some sort to completely enclose the cubby hole.


----------



## thestoneman

I had some duct work done today and had it wrapped in Reflectix (the silver bubble wrap). Is this effective at dampening sound? I am doing clips, DD & GG, but I'm concerned about the register.


----------



## redjr




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/90#post_24323176
> 
> 
> Yep.
> 
> Still hung up.
> 
> It would be a pile of work at awkward angles but the idea has a tiny bit of potential.
> 
> Were painting the tile and had planned on painting the t bar as well.
> 
> I'm now thinking the t bar should stay white just in case.
> 
> The fire rated tile weighs quite a bit. I doubt I have to worry about vibrations with my current subs. I actually hope your right though, that's one problem I'd be happy to have.
> 
> I'll know in about a week, I don't see placing my equipment any sooner.



brwsaw -


I know what you're faced with. I'll have to read thru the thread more to see how your situation worked out for you. I'm still back on page 2 or 3!







I've decided to put up an acoustic tile ceiling as well. But then my space will be use as a multi-purpose office/audio/movie/tv room. I'm taking every step I can for mass and damping, but not total isolation or soundproofing. I want to achieve a very damped/dead room which I should be able to achieve with the construction measures I've taken. Since I will be using t-bar system for the ceiling, I've thought about this very question: Could I supplement the ceiling mass with 2' x 2' squares of 5/8" DW on top of the thick tiles? I don't know for sure, nor have I read anyone that's done it, but I may give it a try. I think if the L -shaped wall angle is secured better than normal, the grid spacing tight and the wires supporting the t-bar is reinforced, it just may work. It would certainly add a significant amount of extra mass to the ceiling. I may give it a try when the time comes. I think you could also prepare/cover the edges of the drywall with tape of some kind to avoid DW dust. But I think that would be minimal. My sub-woofers won't rattle the tiles anyway.










Rick


----------



## redjr




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/90#post_24345362
> 
> 
> Where are some good build threads with staggered stud walls?
> 
> 
> The conventional wisdom has decoupling methods ranked in this order: double walls, staggered studs, clips and channels. There are a number of build threads with double walls and loads of threads with clips and channels. I've yet to find any detailed thread with staggered studs. The closest I've come is a couple threads where one wall is staggered stud... but the main decoupling seems to be clips and channels in those ones.
> 
> 
> What am I missing?



What's even more interesting is that it appears from many of the build pictures here there are a lot of basement walls using 24" centers! I thought that was a strict no-no, if you wanted mass? My front wall is alternating 6" studs on 8" centers. With a large 2x10 in the middle for mounting my 120 lb 65" plasma. The interior of the wall will be either R19 weaved horizontally across the width of the wall -- from floor to ceiling. DD on both sides with some form of acoustic sealant. Granted I'm not floating that wall or DW, but if its mass alone doesn't damp and absorb a lot of sound I will be surprised - all other measures notwithstanding.


Rick


----------



## ellisr63




> Quote:
> Originally Posted by *redjr*  /t/1509173/soundproofing-master-thread/270#post_24526034
> 
> 
> What's even more interesting is that it appears from many of the build pictures here there are a lot of basement walls using 24" centers! I thought that was a strict no-no, if you wanted mass? My front wall is alternating 6" studs on 8" centers. With a large 2x10 in the middle for mounting my 120 lb 65" plasma. The interior of the wall will be either R19 weaved horizontally across the width of the wall -- from floor to ceiling. DD on both sides with some form of acoustic sealant. Granted I'm not floating that wall or DW, but if its mass alone doesn't damp and absorb a lot of sound I will be surprised - all other measures notwithstanding.
> 
> 
> Rick



II was told that by going with 24" on center (double wall) spacing the walls would flex more and that that was good.


----------



## granroth




> Quote:
> Originally Posted by *redjr*  /t/1509173/soundproofing-master-thread/200_100#post_24526034
> 
> 
> What's even more interesting is that it appears from many of the build pictures here there are a lot of basement walls using 24" centers! I thought that was a strict no-no, if you wanted mass? My front wall is alternating 6" studs on 8" centers. With a large 2x10 in the middle for mounting my 120 lb 65" plasma. The interior of the wall will be either R19 weaved horizontally across the width of the wall -- from floor to ceiling. DD on both sides with some form of acoustic sealant. Granted I'm not floating that wall or DW, but if its mass alone doesn't damp and absorb a lot of sound I will be surprised - all other measures notwithstanding.



No! Studs make for terrible mass. They simply aren't dense enough. Plus, to makes things worse, their rigidity makes them near ideal sound conductors. The more studs you have in the wall, the more easily conductive paths you've made for the sound. In fact, quite a bit of soundproofing is finding ways to work around the fact that you have to use studs in the first place.


To be blunt, if you find any notable amount of sound proofing from that wall, it'll be mostly in spite of the studs, not because of them. The absorption from your R19 might be mildly worse than R13 based on how cramped your wall is going to be, but it should still help if not too tightly packed. The double drywall with acoustic sealant will help the most, and the fact that the studs are staggered is definitely better than if they went straight through. Flanking might still be a huge issue if you have a direct connection with that wall to the ceiling.


----------



## brwsaw




> Quote:
> Originally Posted by *redjr*  /t/1509173/soundproofing-master-thread/270#post_24525945
> 
> 
> brwsaw -
> 
> 
> I know what you're faced with. I'll have to read thru the thread more to see how your situation worked out for you. I'm still back on page 2 or 3!
> 
> 
> 
> 
> 
> 
> 
> I've decided to put up an acoustic tile ceiling as well. But then my space will be use as a multi-purpose office/audio/movie/tv room. I'm taking every step I can for mass and damping, but not total isolation or soundproofing. I want to achieve a very damped/dead room which I should be able to achieve with the construction measures I've taken. Since I will be using t-bar system for the ceiling, I've thought about this very question: Could I supplement the ceiling mass with 2' x 2' squares of 5/8" DW on top of the thick tiles? I don't know for sure, nor have I read anyone that's done it, but I may give it a try. I think if the L -shaped wall angle is secured better than normal, the grid spacing tight and the wires supporting the t-bar is reinforced, it just may work. It would certainly add a significant amount of extra mass to the ceiling. I may give it a try when the time comes. I think you could also prepare/cover the edges of the drywall with tape of some kind to avoid DW dust. But I think that would be minimal. My sub-woofers won't rattle the tiles anyway.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Rick



I'm not sure how the tiles would hold up with the extra weight. The 1/2" are garbage, bowing under their own weight.Seems to me its the ceiling were the lighter tile was used that vibrates.

We had planned on using thicker tiles through out and when the time came to put them up they no longer had enough in stock. The 2 week wait was a deal breaker and I wanted in the room asap.

I'm considering ripping out the lighter tiles and replacing them with the same 5/8" fire rated tile in the front half of the room.

We did consider the 5/8" drywall in the grid but decided against it. To many unknowns.

I didn't think my subs would rattle the ceiling then I started experimenting with placement. With 2 at the front, 1 per side of the room, and a pair stacked in the rear corner they sound very nice, with a natural chest rumble similar to when you're singing aloud, but the ceiling bar itself vibrates/whistles like blade of grass or sheet of paper at the lowest notes. Not a lot but enough to want to do something about it.


----------



## redjr




> Quote:
> Originally Posted by *brwsaw*  /t/1509173/soundproofing-master-thread/270#post_24528503
> 
> 
> I'm not sure how the tiles would hold up with the extra weight. The 1/2" are garbage, bowing under their own weight.Seems to me its the ceiling were the lighter tile was used that vibrates.
> 
> We had planned on using thicker tiles through out and when the time came to put them up they no longer had enough in stock. The 2 week wait was a deal breaker and I wanted in the room asap.
> 
> I'm considering ripping out the lighter tiles and replacing them with the same 5/8" fire rated tile in the front half of the room.
> 
> We did consider the 5/8" drywall in the grid but decided against it. To many unknowns.
> 
> I didn't think my subs would rattle the ceiling then I started experimenting with placement. With 2 at the front, 1 per side of the room, and a pair stacked in the rear corner they sound very nice, with a natural chest rumble similar to when you're singing aloud, but the ceiling bar itself vibrates/whistles like blade of grass or sheet of paper at the lowest notes. Not a lot but enough to want to do something about it.


Seems to me that if you took extra precaution when installing them, and had a perfect square with the t-bars and cross members, the DW should sit just fine. This is of course no one disturbs the balance of the entire ceiling. I don't think the weight would be that big of an issue provided the whole structure is installed with extra reinforcement, and no one is doing gymnastics in the room.







I for sure won't have 6 sub-woofers, only 2.







I think someone mentioned in a post that you can get reinforced t-bar for special purposes when using heavier tiles than a typical home. I had not heard of that before.


Rick


----------



## tcjohnsson

I recently purchased a 55-year old duplex home and decided to gut the entire house and start fresh. The exterior, foundation and roof are in great shape; basically very solid bones on this home (previous owner followed textbook preventative maintenance). However, the sound from upstairs/downstairs passes through as if there is almost nothing between them. You can hear people talking (transfers through as an audible murmur) from above when below and the other way around. The footfall noise is horrendous. The original ceiling material on the first floor ceiling is this flimsy compressed sugar cane product known as "canec". I ripped all of it clean revealing joists (no insulation) which are oddly 2 x 5 1/2" dimensional lumber (this is an old house). The upstairs has hardwood floor that is screwed DIRECTLY onto the joists - no subfloor, plywood, nothing. Just hardwood on top of the joists.


Neither the upstairs or downstairs will have a real home theater system (I know both the tenants that will be moving in) but I want to be able to provide them a noise-free environment that can be afforded with my budget of about $7,000. The goal here isn't to make the upstairs and downstairs virtually soundproof but rather just make it so it's tolerable so they can both exist within the same structure and not kill each other. The concern here is only the floor/ceiling area and not walls. Since the entire home is gutted sans interior wall framing, I can tackle this floor/ceiling partition from both above and below as they are both accessible (no ceiling or flooring installed yet).


As mentioned, I currently have 2 x 5 1/2" dimensional lumber that sits directly below the hardwood flooring on the second floor at 16" OC. The area I am working with includes 3 bedrooms, 2 bathrooms and a kitchen/living area (both upstairs and down); total coverage is roughly 1,400 SF. This is what I plan to do:


1) Install 2 x 12" joists to stiffen up the floor above (2 x 5.5" dimensional lumber isn't going to meet the structural requirements of today's building code and will likely flex like crazy). These joists will be fastened directly to the side of the existing 2 x 5.5" joists and will butt up against the wood flooring above. Basically the 2 x 12 and 2 x 5.5 joists will be sitting next to each other. However, the 2 x 12 will obviously stick down 6" more than the 2 x 5.5" joist and that leads me to what I want to do next...


2) Install 5/8" drywall to the underside of the 2 x 5.5" joist. I will also install a 2 x 4 alongside the 2 x 12 so that the drywall can have two sides to screw into. Basically, the drywall will be cut into 14" strips and placed between the joists, center of the 2 x 12" vertically which is smack in between the wood flooring and the finished ceiling drywall


3) Install R19 fiberglass batts between the 5/8" drywall and the flooring above (obviously done before #2 where the drywall is screwed in place)


4) Install RC-1 Pro Resilient Channel perpendicular to the 2 x 12" wood joists at 24" OC


5) Install 5/8" drywall over the RC-1 Pro channel.


6) Install R19 fiberglass batts between the two sheets of 5/8" drywall


Now from the floor above -


7) Install Hush Step 5/32" rubber underlayment directly over the wood flooring (which is attached directly to the original 2 x 5.5" joists). This is the best footfall noise reducer I could find on-island (I live in Honolulu, HI)


8) Install either OSB, plywood or cement board directly over the Hush Step rubber underlayment. Any advice on which one is the best option? I don't like plywood as it's hard to keep perfectly flat which may mean I will need some screws to keep it down in areas where it exhibits crowns or valleys... which would short circuit the floating material.


9) Install waterproof resilient flooring (Allure) over the OSB, plywood or cement board


Allure doesn't recommend installing underlayment directly under the floor because excessive flexing can damage/crack the plastic-based material it's comprised of (they actually recommend against it). That is why I am putting the Hush Step padding beneath the OSB/ply/cement board so the potential for flex is reduced significantly.


Some of you may be wondering why I am putting a piece of drywall in the center of the 12" joist as it's quite labor intensive. I figured the extra mass can't hurt and allowing for TWO air spaces and TWO layers of R19 fiberglass that each has its own air space above the fiberglass is always better even if the joist is coupling directly with the floor above (hoping the RC channel helps there). Also, I am a recessed lighting nut. I can't do a project unless my ceiling looks like swiss cheese. Lighting is huge for me; I'm installing about 50 each 4" cans in the 1,400 SF of ceiling I'm working with). That extra layer of drywall should help reduce the transmission through the cans even if just a little. Soffits for all those cans would require significantly more work and will blow my $7K budget out of the water.... not to mention drop the ceiling another 6" in many areas.


While my first pick for the underlayment directly below the Allure flooring would be cement board... I am worried that I may be overdoing it with the weight. I'll have 1 1/4" of drywall mass already weighing down the floor.


I'm hoping all this work will have a sizable impact on noise transmission but want to make sure I'm not totally out of line here (which I may be). Any advice is MUCH appreciated


----------



## FortKnUX


I have existing room in the basement that I am converting to HT.  The size of the room is 12.5'x21' located at the corner of the basement which is completely below grade.  2 sides of the room are part of the concrete foundation (picture is attached) sprayed with 3" of hard foam insulation then 2x4 studs then 1/2" DW.  The other 2 walls are just Roxul insulation sandwiched between two 1/2" DWs separated by 2x4s studs.  The ceiling is also filled with Roxul and covered with 1/2" DW.  The question is how to better soundproof the room without taking too much of its width and height (every inch counts)?  The walls will have another layer of 1/2" finished plywood for esthetics below chairrail moldings and 1/4" finished plywood above covered with an inch of sound dampening panels.  I am not trying to completely deaden the sound but trying to find a compromise.  I don't mind hearing the sound in other rooms of the basement but would prefer less distraction above the HT room (which is my living room).  I was thinking of putting another layer of DW+GG on the ceiling.  As to the walls I am thinking of 1/2" plywood + GG + 1/2"DW + GG.


----------



## cw5billwade

FortKnUX your room has everything but the decoupling. It sounds like your plan will make a difference but if hard wood above you will still have foot fall as it travels through the floor joist to your drywall. We have carpet upstairs and in my living room it sounds like a heard of elephants when the grand kids get to running. Do not forget to put backer boxes on your light fixtures. A 1/34" solid core door will help as well. As BIGmounthinDC pointed out most 1/2 DW on the market today is light weight. You can afford 1/4" can't you? Just get the 3/4" Fire Proof DW. Short of tearing down all of the DW and decoupling the ceiling and interior walls your plan will make it better but not perfect.


----------



## FortKnUX




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/270#post_24537602
> 
> 
> FortKnUX your room has everything but the decoupling. It sounds like your plan will make a difference but if hard wood above you will still have foot fall as it travels through the floor joist to your drywall. We have carpet upstairs and in my living room it sounds like a heard of elephants when the grand kids get to running. Do not forget to put backer boxes on your light fixtures. A 1/34" solid core door will help as well. As BIGmounthinDC pointed out most 1/2 DW on the market today is light weight. You can afford 1/4" can't you? Just get the 3/4" Fire Proof DW. Short of tearing down all of the DW and decoupling the ceiling and interior walls your plan will make it better but not perfect.


 

thanks cw5billwade.  I am planning to replace existing 48"wide 1-3/4" double doors with a single 36" 1-3/4" flush slab and will use acoustical jamb seal kit with automatic door bottom. Decoupling will take too much of the ceiling space.  If I have people sitting in the living room are mostly elderly and quiet, so it's actually other way around I am looking to dampen HT sound in the room above as much as I can. I can see how LFE can be an issue here.


----------



## granroth




> Quote:
> Originally Posted by *tcjohnsson*  /t/1509173/soundproofing-master-thread/200_100#post_24535080
> 
> 
> [snip]
> 
> 
> 1) Install 2 x 12" joists to stiffen up the floor above (2 x 5.5" dimensional lumber isn't going to meet the structural requirements of today's building code and will likely flex like crazy). These joists will be fastened directly to the side of the existing 2 x 5.5" joists and will butt up against the wood flooring above. Basically the 2 x 12 and 2 x 5.5 joists will be sitting next to each other. However, the 2 x 12 will obviously stick down 6" more than the 2 x 5.5" joist and that leads me to what I want to do next...
> 
> 
> 2) Install 5/8" drywall to the underside of the 2 x 5.5" joist. I will also install a 2 x 4 alongside the 2 x 12 so that the drywall can have two sides to screw into. Basically, the drywall will be cut into 14" strips and placed between the joists, center of the 2 x 12" vertically which is smack in between the wood flooring and the finished ceiling drywall
> 
> 
> 3) Install R19 fiberglass batts between the 5/8" drywall and the flooring above (obviously done before #2 where the drywall is screwed in place)
> 
> 
> 4) Install RC-1 Pro Resilient Channel perpendicular to the 2 x 12" wood joists at 24" OC
> 
> 
> 5) Install 5/8" drywall over the RC-1 Pro channel.
> 
> 
> 6) Install R19 fiberglass batts between the two sheets of 5/8" drywall



There are some good ideas here and at least one that will undo nearly all of the good. First, by all means sister some larger joists to the existing ones -- that will do wonders for the upper floor stiffness. You may not need 2x12s, though -- check with your local building codes. In fact, this is one area where I'd recommend getting the right permits, to make sure everything is done right. Re-doing a room for a theater is one thing but redoing the structure of a house is quite another.


Next, though, do NOT under any circumstances put that layer of drywall on the 2x6s. It will make things worse, not better. What happens is that you'll have three layers of mass with layers of air in between -- a Mass-Air-Mass-Air-Mass setup. That's called a "triple leaf" and it will actually reduce your sound proofing, not increase it. See this page for the reasons why: http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ 


A far better solution is to take those pieces of drywall and attach them to the floor above between the joists. Apply some Green Glue as a damping layer and you'll increase your STL even more.


Using RC-1 is a decent start for decoupling, but it could be far better without spending too much more, if you use resilient clips and normal hat channel. Resilient channel has a bad reputation for quality and often won't give you the soundproofing that hope to get out of it. Using clips and channel is a much more sure bet.


What I'd do is this:


1. Add at least two layers of drywall to the underside of the floor, preferably with Green Glue in between as a damping (not adhesive) layer

2. Install R-19 insulation loosely between the joists

3. Install isolation clips and hat channel on the bottoms of the 2x12s

4. Add two layers of drywall to the channels, preferably with Green Glue in between


The numbers of layers of drywall can vary, as well as using Green Glue or not (they will all make a big difference, but it depends on how much soundproofing you want vs your budget).


For pictures, see this article: http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/ Your best bet is STL Ceiling Solution 4 or 5


----------



## granroth




> Quote:
> Originally Posted by *FortKnUX*  /t/1509173/soundproofing-master-thread/200_100#post_24537718
> 
> 
> thanks cw5billwade.  I am planning to replace existing 48"wide 1-3/4" double doors with a single 36" 1-3/4" flush slab and will use acoustical jamb seal kit with automatic door bottom. Decoupling will take too much of the ceiling space.  If I have people sitting in the living room are mostly elderly and quiet, so it's actually other way around I am looking to dampen HT sound in the room above as much as I can. I can see how LFE can be an issue here.



You can decouple with as little as 1/2" "wasted" space ( Post 208 ). That's not typically something that would be even noticeable in terms of ceiling height loss.


----------



## artur9




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/270#post_24539220
> 
> 
> What I'd do is this:
> 
> 
> 1. Add at least two layers of drywall to the underside of the floor, preferably with Green Glue in between as a damping (not adhesive) layer
> 
> 2. Install R-19 insulation loosely between the joists



I want to make sure I understand this as I'm planning something similar.


Cut drywall into widths that match the distance between the joists.

Put a layer of green glue on the drywall.

Then, from underneath, attach the drywall onto the subflooring(?). Add another layer possibly. Does the green glue hold the drywall onto the subfloor?

Then put R19/SafeNSound between the joists.


Any terminology above that is wrong is from my lack of understanding.


----------



## ellisr63




> Quote:
> Originally Posted by *artur9*  /t/1509173/soundproofing-master-thread/270#post_24541476
> 
> 
> I want to make sure I understand this as I'm planning something similar.
> 
> 
> Cut drywall into widths that match the distance between the joists.
> 
> Put a layer of green glue on the drywall.
> 
> Then, from underneath, attach the drywall onto the subflooring(?). Add another layer possibly. Does the green glue hold the drywall onto the subfloor?
> 
> Then put R19/SafeNSound between the joists.
> 
> 
> Any terminology above that is wrong is from my lack of understanding.



Grren glue doesn't actually glue it... You need to use sheetrock screws to hold it as you normally would.


----------



## granroth




> Quote:
> Originally Posted by *artur9*  /t/1509173/soundproofing-master-thread/200_100#post_24541476
> 
> 
> I want to make sure I understand this as I'm planning something similar.
> 
> 
> Cut drywall into widths that match the distance between the joists.
> 
> Put a layer of green glue on the drywall.
> 
> Then, from underneath, attach the drywall onto the subflooring(?). Add another layer possibly. Does the green glue hold the drywall onto the subfloor?
> 
> Then put R19/SafeNSound between the joists.



Green Glue is very inaptly named as it is not an adhesive. You attach the drywall to the subfloor using drywall screws or cleats. Otherwise, yes, you have the right idea.


I will say this -- there does appear to be different schools of thought on how exactly to deal with this situation. Cutting the drywall into widths that are exactly the distance between the joists and attaching them using screws is definitely the most common option and is likely what you should do. However, there is a school of thought that goes a bit overboard, and might be worth considering if you want every last bit of diminishing returns.


In that case, you cut your drywall 1/2" smaller than the inter-joist distance and center it in the space. This leaves a 1/4" gap all the way round. This gap is filled first with 3/8" backer rod and then sealed with a 1/4" bead of acoustic caulk. This decouples the added drywall mass from the joists without losing notable mass. Then, rather than affixing the drywall to the subfloor using screws (and thus coupling them to the subfloor), you can create cleats that are attached to the joists and just press the drywall up against the subfloor.


I honestly don't know that this would make any measurable difference and I don't completely see the point of the cleats... but it has been done that way and so I'm offering up that option.


----------



## tcjohnsson




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/270#post_24539220
> 
> 
> There are some good ideas here and at least one that will undo nearly all of the good. First, by all means sister some larger joists to the existing ones -- that will do wonders for the upper floor stiffness. You may not need 2x12s, though -- check with your local building codes. In fact, this is one area where I'd recommend getting the right permits, to make sure everything is done right. Re-doing a room for a theater is one thing but redoing the structure of a house is quite another.
> 
> 
> Next, though, do NOT under any circumstances put that layer of drywall on the 2x6s. It will make things worse, not better. What happens is that you'll have three layers of mass with layers of air in between -- a Mass-Air-Mass-Air-Mass setup. That's called a "triple leaf" and it will actually reduce your sound proofing, not increase it. See this page for the reasons why: http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/
> 
> 
> A far better solution is to take those pieces of drywall and attach them to the floor above between the joists. Apply some Green Glue as a damping layer and you'll increase your STL even more.
> 
> 
> Using RC-1 is a decent start for decoupling, but it could be far better without spending too much more, if you use resilient clips and normal hat channel. Resilient channel has a bad reputation for quality and often won't give you the soundproofing that hope to get out of it. Using clips and channel is a much more sure bet.
> 
> 
> What I'd do is this:
> 
> 
> 1. Add at least two layers of drywall to the underside of the floor, preferably with Green Glue in between as a damping (not adhesive) layer
> 
> 2. Install R-19 insulation loosely between the joists
> 
> 3. Install isolation clips and hat channel on the bottoms of the 2x12s
> 
> 4. Add two layers of drywall to the channels, preferably with Green Glue in between
> 
> 
> The numbers of layers of drywall can vary, as well as using Green Glue or not (they will all make a big difference, but it depends on how much soundproofing you want vs your budget).
> 
> 
> For pictures, see this article: http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/ Your best bet is STL Ceiling Solution 4 or 5



Thank you Granroth! I appreciate you bringing me up to speed on the triple leaf effect; 100% counter-intuitive I must admit but if that's what the data/tests yield, I'd better make some changes. Unfortunately I already installed quite a few of the 2 x 4s parallel and onto the side of the 2 x 12 joists about halfway between the top and bottom of the joist. Should I remove them? I'm about 1/2 complete with that scope. Will having the 2 x 4 attached to the 2 x 12 create more "resonance" or other issues as I've essentially decreased the volume of the airspace? Getting that piece of drywall to attach directly under the floorboards will be a little more difficult but not impossible with the 2 x 4s in place. Removing them wouldn't be too much work but I guess having that additional stiffness added to the 2x12 can't hurt from a floor rigidity standpoint. Either way, please let me know if I should remove them.


The building is fully permitted and the structural engineer required the 2 x 8 to make the floor (and house) rigid and support the load above; the clear span is about 14'-15'. 2 x 8s would have worked but I wanted the extra depth to accomplish what I thought was a better soundproofing solution so I went with 2 x 12s. Ceilings were already 9' so going to 8'6" wasn't a big deal. Because of cost and timing constraints (I have to get this entire project wrapped up in 6 weeks so the tenant can move in) I will stick with the RC channel but thank you for your recommendation on the clips+hat channel. Based on my forum perusing, I understood that would be a better solution but the clips aren't readily available on island and installation time would increase because of the increased degree in difficulty.


I've spent the last 2 hours searching for a company that carries something similar to Green Glue (nobody on Oahu carries GG) but have found nothing. You would think that on an island with 1 million people and living in such close quarters, the product would be more popular and available. If you have any other recommendations to an alternative to GG between the drywall and floorboards (perhaps installing the HUSH STEP 5/32 rubber mat between the drywall and the floorboards?), please let me know. Maybe I'd be better served by adding more mass onto the floor above? It's a lot easier to add mass above and I won't need screws as they can simply float on each other. I could pile layers of hardipanel, plywood, OSB, even thermal boards onto the floor that is currently unfinished. Thank you again for your advice. It's much appreciated.


----------



## granroth




> Quote:
> Originally Posted by *tcjohnsson*  /t/1509173/soundproofing-master-thread/200_100#post_24541874
> 
> 
> Thank you Granroth! I appreciate you bringing me up to speed on the triple leaf effect; 100% counter-intuitive I must admit but if that's what the data/tests yield, I'd better make some changes. Unfortunately I already installed quite a few of the 2 x 4s parallel and onto the side of the 2 x 12 joists about halfway between the top and bottom of the joist. Should I remove them? I'm about 1/2 complete with that scope. Will having the 2 x 4 attached to the 2 x 12 create more "resonance" or other issues as I've essentially decreased the volume of the airspace? Getting that piece of drywall to attach directly under the floorboards will be a little more difficult but not impossible with the 2 x 4s in place. Removing them wouldn't be too much work but I guess having that additional stiffness added to the 2x12 can't hurt from a floor rigidity standpoint. Either way, please let me know if I should remove them.



That should be fine. In fact, rigid cross members are often a required elements of floor joists in a lot of areas, so quite a few soundproofed floors have them to no great detriment.


> Quote:
> Originally Posted by *tcjohnsson*  /t/1509173/soundproofing-master-thread/200_100#post_24541874
> 
> 
> The building is fully permitted and the structural engineer required the 2 x 8 to make the floor (and house) rigid and support the load above; the clear span is about 14'-15'. 2 x 8s would have worked but I wanted the extra depth to accomplish what I thought was a better soundproofing solution so I went with 2 x 12s. Ceilings were already 9' so going to 8'6" wasn't a big deal. Because of cost and timing constraints (I have to get this entire project wrapped up in 6 weeks so the tenant can move in) I will stick with the RC channel but thank you for your recommendation on the clips+hat channel. Based on my forum perusing, I understood that would be a better solution but the clips aren't readily available on island and installation time would increase because of the increased degree in difficulty.



Yep. Just be careful when using the RC-1 to not allow the screw to go all the way to the joist and it'll be fine. It's tempting sometimes to think that there is either the One True Way or No Way, but a lot of soundproofing is just using what you have available and if that gets you the amount of STL that you want, then who's to say that that was the wrong way to go.


> Quote:
> Originally Posted by *tcjohnsson*  /t/1509173/soundproofing-master-thread/200_100#post_24541874
> 
> 
> I've spent the last 2 hours searching for a company that carries something similar to Green Glue (nobody on Oahu carries GG) but have found nothing. You would think that on an island with 1 million people and living in such close quarters, the product would be more popular and available. If you have any other recommendations to an alternative to GG between the drywall and floorboards (perhaps installing the HUSH STEP 5/32 rubber mat between the drywall and the floorboards?), please let me know. Maybe I'd be better served by adding more mass onto the floor above? It's a lot easier to add mass above and I won't need screws as they can simply float on each other. I could pile layers of hardipanel, plywood, OSB, even thermal boards onto the floor that is currently unfinished. Thank you again for your advice. It's much appreciated.



I honestly don't know how well the rubber mat would work as a damping material. Brian Ravnaas, the creator of Green Glue, talked a little bit about alternatives here: Alternatives to Green Glue . TL;DR - simple roofing tar paper does an okay job and better than using nothing.


Adding mass always helps, but only linearly. You don't get the big jumps in performance that you do when using Green Glue. The Green Glue company has a PDF on exactly this topic, with data to back up their assertions:
Green Glue Vs Extra Drywall . In short, yes, adding more layers of mass will absolutely help and if you have it available for no extra cost, then by all means use it. Just don't count on getting the same results as if you used Green Glue and you'll be good to go.


----------



## BIGmouthinDC

Just a note on Green Glue, while people will say it's not a glue that is correct. You can't press something in place and expect it to stay even after waiting overnight. BUT, you wait 30 days and you better not need to get the two surfaces apart, it is not coming apart. I've had to undo some green glue surfaces in my day and it is nearly impossible, The material breaks before the bond will separate.


----------



## ellisr63

How do I deal with the gap between the 2 walls (double wall construction) as it is right next to our hallway entrance way to the HT? Do I get rubber matting and attach it across the gap and then seal it with caulk and maybe 2x4s to keep it tight against the walls?


----------



## granroth

Can you draw a picture or mock up something in Sketchup to describe your situation? I'm having a hard time visualizing what that gap would look like in the context you describe.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/300#post_24543453
> 
> 
> Can you draw a picture or mock up something in Sketchup to describe your situation? I'm having a hard time visualizing what that gap would look like in the context you describe.


 http://s1065.photobucket.com/user/ellisr63/media/floorlayout2_zps2fcaab38.jpg.html  

This is my floor layout of the inner walls... To the left I drew a line where the outer wall is, and the gap between the 2 walls. The first door is on the outer wall ... If I had a 2nd door right next to the first door there would be an air gap that could be caulked but the 2nd door is actually 5' away. If you were to walk through the outer door (into the theater), and look immediately to the right you would see the air gap between the old wall and the new inner wall. How do I seal that part off from the hallway? Does this make more sense now? The area that is a red scribble is the air gap.


tia,

Ron


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/300_100#post_24543482
> 
> 
> This is my floor layout of the inner walls... To the left I drew a line where the outer wall is, and the gap between the 2 walls. The first door is on the outer wall ... If I had a 2nd door right next to the first door there would be an air gap that could be caulked but the 2nd door is actually 5' away. If you were to walk through the outer door (into the theater), and look immediately to the right you would see the air gap between the old wall and the new inner wall. How do I seal that part off from the hallway? Does this make more sense now? The area that is a red scribble is the air gap.



I was hoping that an actual expert would chime in before now, since this is a bit out of my league. I'm not even close to an expert but rather somebody who has rather voraciously read everything he could find on soundproofing and is decent at applying use cases to known soundproofing patterns with proven results. Honestly, your case doesn't fit any solid pattern that I know, and so I can't at all confidently predict your results.


IF there was a door in the space you have labeled 'ENTRANCE', then that would be a pretty typical pattern. You just create a solid door jamb in that opening that bridges the two walls and caulk all openings. You could also cut a 1/4" (or so) right down the middle of the jamb to decouple the two sides and caulk that. The experts say that that likely isn't worth it.


If there is NOT a door in that space, then I'm not actually certain that either of those sides of double walls will work as well as you'd hope. Sound will be escaping willy-nilly through the space above the '2ND ROW PLATFORM' since that's not a double wall and simply bypassing the double wall entirely. The upper bit showing a double wall, in this case, may actually be useless. I say "may" because, again, I'm a bit out of my league.


I will say this. If the entrance remains open, then it doesn't matter very much what you use to seal the gap between the two walls. Even drywall shouldn't couple them in any significant way (based on the analysis of door jambs).


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/300#post_24546747
> 
> 
> I was hoping that an actual expert would chime in before now, since this is a bit out of my league. I'm not even close to an expert but rather somebody who has rather voraciously read everything he could find on soundproofing and is decent at applying use cases to known soundproofing patterns with proven results. Honestly, your case doesn't fit any solid pattern that I know, and so I can't at all confidently predict your results.
> 
> 
> IF there was a door in the space you have labeled 'ENTRANCE', then that would be a pretty typical pattern. You just create a solid door jamb in that opening that bridges the two walls and caulk all openings. You could also cut a 1/4" (or so) right down the middle of the jamb to decouple the two sides and caulk that. The experts say that that likely isn't worth it.
> 
> 
> If there is NOT a door in that space, then I'm not actually certain that either of those sides of double walls will work as well as you'd hope. Sound will be escaping willy-nilly through the space above the '2ND ROW PLATFORM' since that's not a double wall and simply bypassing the double wall entirely. The upper bit showing a double wall, in this case, may actually be useless. I say "may" because, again, I'm a bit out of my league.
> 
> 
> I will say this. If the entrance remains open, then it doesn't matter very much what you use to seal the gap between the two walls. Even drywall shouldn't couple them in any significant way (based on the analysis of door jambs).



There will be a door but it is on the outer wall (to the left in between the door opening I added to the drawing).So the hallway is sealed off from the outside world with a door on each end of the hall. The 2nd row platform does have a wall (the hallway wall), and we have the platform integrated into the double wall on the back and left side. The walls are bolted to the concrete slab (as is the sub floor), and the entire sub floor, and platform are stuffed with fiberglass.Does this make the problem more clear?


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/300_100#post_24546770
> 
> 
> There will be a door but it is on the outer wall (to the left in between the door opening I added to the drawing).So the hallway is sealed off from the outside world with a door on each end of the hall. The 2nd row platform does have a wall (the hallway wall), and we have the platform integrated into the double wall on the back and left side. The walls are bolted to the concrete slab (as is the sub floor), and the entire sub floor, and platform are stuffed with fiberglass.Does this make the problem more clear?



Oh, good! That's a much better plan that I was fearing you had










In this case, the solution is to create a door frame that spans both walls and closes off the gap between them. A typical pre-hung door frame is 4-1/2" wide to accommodate a 3-1/2" stud and then two layers of 1/2" drywall. In this case, you'll either create a door frame from scratch or have the door manufacture create the frame to your specs.


To calculate the size, just add up the size of the drywall + studs + air gap + studs + drywall. If we hypothetically say you had two layers of 5/8" drywall on the outside of the double wall, an air gap of 1", and a single layer of 5/8" drywall on the jamb support on the other end, then we'd have: 2*(5/8) + 3-1/2 + 1 + 3-1/2" + 5/8 = 9-7/8"


The door would either be on the inside of the larger frame, if it swung in, or on the outside if it swung out.


This is very commonly done with double walls and you could be rest assured that it would perform like expected.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/300#post_24550205
> 
> 
> Oh, good! That's a much better plan that I was fearing you had
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> In this case, the solution is to create a door frame that spans both walls and closes off the gap between them. A typical pre-hung door frame is 4-1/2" wide to accommodate a 3-1/2" stud and then two layers of 1/2" drywall. In this case, you'll either create a door frame from scratch or have the door manufacture create the frame to your specs.
> 
> 
> To calculate the size, just add up the size of the drywall + studs + air gap + studs + drywall. If we hypothetically say you had two layers of 5/8" drywall on the outside of the double wall, an air gap of 1", and a single layer of 5/8" drywall on the jamb support on the other end, then we'd have: 2*(5/8) + 3-1/2 + 1 + 3-1/2" + 5/8 = 9-7/8"
> 
> 
> The door would either be on the inside of the larger frame, if it swung in, or on the outside if it swung out.
> 
> 
> This is very commonly done with double walls and you could be rest assured that it would perform like expected.


Thanks, now I am not so worried.


----------



## Tfleming675




> Quote:
> Originally Posted by *FortKnUX*  /t/1509173/soundproofing-master-thread/270#post_24537718
> 
> 
> thanks cw5billwade.  I am planning to replace existing 48"wide 1-3/4" double doors with a single 36" 1-3/4" flush slab and will use acoustical jamb seal kit with automatic door bottom. Decoupling will take too much of the ceiling space.  If I have people sitting in the living room are mostly elderly and quiet, so it's actually other way around I am looking to dampen HT sound in the room above as much as I can. I can see how LFE can be an issue here.



This essentially my room layout. I spent a lot of time trying to figure out what to do in my room. I finally settled on 5/8" drywall with res channel around the room with Roxul insulation. For the ceiling i used acoustic ceiling tiles with Roxul and an air space between the tiles and the ceiling and the Roxul and the floor above. I did not want to loose the space and flexibility for my ceiling. I also used a solid core door.


Now, this is not perfect and many people will tell you all of the reasons why I am wrong to do this. However, I can now say that I am perfectly happy with the results in "real" world testing. I can be in the theatre with the sound blasting and you can not hear it upstairs at all with the exception of the LFE and this is only minor. As soon as you open the door it get's very loud. I do not hear foot fall, however, if kids are jumping on the floor that I can still hear when I am in the theatre with the door open and no movie playing.


For me the problem was solved with these measures on budget, with all of the flexibility I need. In order to get more sound proofing than I have I would have to spend a massive amount more to get only a marginal gain. Of course it depends on your own needs.


----------



## FortKnUX


Quick question, is it Ok to use 5/8 drywall for backer boxes?


----------



## granroth




> Quote:
> Originally Posted by *Tfleming675*  /t/1509173/soundproofing-master-thread/300_100#post_24550814
> 
> 
> Now, this is not perfect and many people will tell you all of the reasons why I am wrong to do this. However, I can now say that I am perfectly happy with the results in "real" world testing..



If you are happy with the results, then nobody can tell you that you're wrong at all! The entire goal of soundproofing is NOT to get to some abstract external standard but rather to get to whatever YOU are happy with. Since you achieved that, your method was a resounding success.


That said, your solution might not be very generalizable to other people. There are scant few tests done using a suspended ceiling with acoustic ceiling tiles and so it's very hard to predict what will happen when a solution involving them is used. For most people that don't have a limitation of keeping those tiles, a much more well known (and thoroughly tested) solution would be to attach a couple layers of drywall to the ceiling joists via clips and channels. That will definitely work better than a suspended ceiling solution.


But again, that's not to say that your solution is inferior if it gave you the results you wanted. The "classic" model just gives more of a chance for other people to hit their own personal targets.


----------



## granroth




> Quote:
> Originally Posted by *FortKnUX*  /t/1509173/soundproofing-master-thread/300_100#post_24551191
> 
> 
> Quick question, is it Ok to use 5/8 drywall for backer boxes?



Use _only_ drywall, or use it as the inner layer instead of cement board. If the latter, then yes.


If the former, then I can't say I've ever seen that done. Maybe it could work. A good backer box has a decent amount of mass; is well sealed; is fire rated; and holds together long term. If you build the box with drywall by gluing the pieces together (can't screw or nail on the edge), then it would certainly fit the first three, but I don't know about the longitivtiy. Specifically, how well would it work with the glue on the edges over time? No idea.


Is there a reason not to just make it using OSB or MDF as the outer layer?


----------



## Tfleming675




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/300#post_24553213
> 
> 
> If you are happy with the results, then nobody can tell you that you're wrong at all! The entire goal of soundproofing is NOT to get to some abstract external standard but rather to get to whatever YOU are happy with. Since you achieved that, your method was a resounding success.
> 
> 
> That said, your solution might not be very generalizable to other people. There are scant few tests done using a suspended ceiling with acoustic ceiling tiles and so it's very hard to predict what will happen when a solution involving them is used. For most people that don't have a limitation of keeping those tiles, a much more well known (and thoroughly tested) solution would be to attach a couple layers of drywall to the ceiling joists via clips and channels. That will definitely work better than a suspended ceiling solution.
> 
> 
> But again, that's not to say that your solution is inferior if it gave you the results you wanted. The "classic" model just gives more of a chance for other people to hit their own personal targets.



I would agree with all of your comments. I certainly know that their are other methods that would provide a higher level no question. This forum has been very valuable for me to vet all of the various options.


----------



## artur9




> Quote:
> Originally Posted by *Tfleming675*  /t/1509173/soundproofing-master-thread/300#post_24550814
> 
> 
> For the ceiling i used acoustic ceiling tiles with Roxul and an air space between the tiles and the ceiling and the Roxul and the floor above.



So you ended up with an airspace between the tiles and the Roxul and another airspace between the Roxul and the floor?


----------



## granroth




> Quote:
> Originally Posted by *artur9*  /t/1509173/soundproofing-master-thread/300_100#post_24553728
> 
> 
> So you ended up with an airspace between the tiles and the Roxul and another airspace between the Roxul and the floor?



FWIW, acoustic tests have shown that it doesn't matter at all where the insulation is situated in an air cavity. So Roxul+Air, Air+Roxul, and Air+Roxul+Air are all the same.


----------



## Tfleming675




> Quote:
> Originally Posted by *artur9*  /t/1509173/soundproofing-master-thread/300#post_24553728
> 
> 
> So you ended up with an airspace between the tiles and the Roxul and another airspace between the Roxul and the floor?



Correct, I have acoustic tiles that have a high CAC and NRC rating with about 3 inches of air between the tiles before the Roxul (R22) and and then another few inches between that and the floor above. I am not saying this is perfect but for what it cost and level of effort I am very happy with this solution. I was not going for the 99 percent solution in my case. I am amazed by how quite it is on the main floor with my SC-65 cranked.


----------



## slapface


Wondering if I could get some advice. I am developing a room in my basement to be my office space. My child's room is directly above. I want to add some soundproofing to help decrease the transfer of sound between the two rooms. I'm not aiming for silence. Just cutting down on the transfer of sound. I cannot do the walls, just the ceiling. I know this is not ideal, but I am hoping that doing the ceiling will be better than doing nothing.

 

With that said, I hope you can help answer a few questions. I have been reading the forum and have taken much of your comments into consideration. Thank you. You have been a big help. I just need to nail down these few outstanding questions and I will be on my way to finishing my room.

 

Ceiling specs:

12' x 8.5'

Joists on 16" centers

No lighting or holes in ceiling (ignore the wiring in pic)

 

Soundproofing layers:

1. R-19 Ultra Touch blue jeans insulation in the bays

2. ISOMax Sound Isolation Clips

3. 20 Gauge Hat Channel on 16" centers

4. 3/4" OSB tongue and grove with 1/4" gap to wall, acoustic caulk to seal gap

5. Green Glue

6. 5/8" Dry Wall with 1/4" gap to wall, acoustic caulk to seal gap

 

My questions are:

1) How many ISOMax clips should I use? They are rated at 36 lbs max load and 48" on center max spacing. I want to have more than the minimum to make sure the ceiling doesn't fall down.

 

2) How should the clips be laid out considering my studs are 16" on center?

 

3) Do I screw the second layer (drywall) to the hat channel or the first layer (OSB)?

 

4) What is the screw pattern for each layer?

 

5) What is the right amount of Green Glue to apply between the two layers? GG website says 1 to 3 tubes per 4' x 8' sheet of dry wall. 

 

Thank you!


----------



## BIGmouthinDC

If you are interested in reducing foot fall noise from above, I would attach drywall and green glue directly to the underside of the floor boards as the first step . Two layers. I've seen it (heard it) work wonders.


On clip spacing always ask the vendor. Each brand is different, I know Ted White at Soundproofingcompany.com will help you with the clips he sells.


Why are you using OSB? what are you planning on hanging from the ceiling? Otherwise use two layers of 5/8 DW


----------



## slapface


Hi Big. My contractor recommended using OSB because it has a different material makeup than the dry wall. He said using different materials helps to break up the sound. We also sided with OSB because we thought we could screw the second layer (dry wall) directly into it. Although I am confused at to how to attached the second layer - to the first layer or the hat channel.

 

I will consider using two layers of dry wall instead of OSB. I will also consider adding the extra layers under the floor boards. Is this what you're describing?


----------



## BIGmouthinDC

yes, that is the method but you can do two layers under the floor boards.


----------



## kmhvball




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/300#post_24558395
> 
> 
> yes, that is the method but you can do two layers under the floor boards.


I am planning on doing one of each ceiling/ under-sub floor construction in two different rooms... for my theater room, I am planning to do two layers of drywall/ GG under the OSB/floor boards, but in another section of my basement... a bedroom, which happens to be under our master bedroom, I plan to do a single layer.   The flooring above both of these rooms is the same - hardwood over OSB sub-floor.  

 

In both basement rooms, my tentative plan to use insulation, clips & hat channel, a layer of OSB + GG + layer of 5/8" drywall.  

 

In the 'bedroom', I really don't plan on hanging anything on the ceiling other than a ceiling fan... Would I be better off simply with two 5/8" drywall layers vs the OSB/Drywall on the ceiling?  I worry some about the drywall contractors and thought an OSB layer would maybe be easier for them to apply the 2nd layer of drywall to.

 

So, although it is going to be awhile till I am at that point, at some point, from a 'noise entering room from above' perspective, I'll have some qualitative (I don't have quantitative measuring devices) assessment of the difference between different methods.   I might have some slight difference in 'flanking' noise as well, but hopefully that won't be too major.


----------



## BIGmouthinDC

Slapface, OSB is fine just harder to work with and I only use it if there is a need to hang extensive ceiling finishing details. If your guy wants to use it, make him happy.


----------



## cw5billwade

.


> Quote:
> Originally Posted by *slapface*  /t/1509173/soundproofing-master-thread/300#post_24558206
> 
> 
> Hi Big. My contractor recommended using OSB because it has a different material makeup than the dry wall. He said using different materials helps to break up the sound. We also sided with OSB because we thought we could screw the second layer (dry wall) directly into it. Although I am confused at to how to attached the second layer - to the first layer or the hat channel.
> 
> 
> I will consider using two layers of dry wall instead of OSB. I will also consider adding the extra layers under the floor boards. Is this what you're describing?





> Quote:
> Originally Posted by *kmhvball*  /t/1509173/soundproofing-master-thread/300#post_24559154
> 
> 
> In the 'bedroom', I really don't plan on hanging anything on the ceiling other than a ceiling fan... Would I be better off simply with two 5/8" drywall layers vs the OSB/Drywall on the ceiling?  I worry some about the drywall contractors and thought an OSB layer would maybe be easier for them to apply the 2nd layer of drywall to.


Regardless of what you hang both layers need to hit the hat channel. I just snapped the location of the hat channel on the first layer as I hang them. Easy to then put the second layer in place and snap a line so you hit the channel. Use 1 ¼” metal drywall screws for first layer and 1 ½” for second layer. The OSB is if you are then hanging thins latter like the projector or in my case soffits, columns and coffers. For standard bedroom construction just use the drywall. I am glad I did OSB in my theater


----------



## ellisr63




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/300#post_24568431
> 
> 
> .
> 
> 
> Regardless of what you hang both layers need to hit the hat channel. I just snapped the location of the hat channel on the first layer as I hang them. Easy to then put the second layer in place and snap a line so you hit the channel. Use 1 ¼” metal drywall screws for first layer and 1 ½” for second layer. The OSB is if you are then hanging thins latter like the projector or in my case soffits, columns and coffers. For standard bedroom construction just use the drywall. I am glad I did OSB in my theater


So even if your first layer is OSB, you need to hit the hat channel for the drywall layer? I would have thought that if you use OSB for the first layer you could shoot the drywall screws anywhere on the second layer except where the clips are.


----------



## cw5billwade




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/300#post_24568559
> 
> 
> So even if your first layer is OSB, you need to hit the hat channel for the drywall layer? I would have thought that if you use OSB for the first layer you could shoot the drywall screws anywhere on the second layer except where the clips are.


This was discussed earlier the first layer gets its screws into the channel. The sheer force on the channel is now the weight of the DW or OSB divided by the number of screws. You will find while installing the first layer especially if it is OSB there is a sweet spot between tight enough and too tight which pops the screw back out of the channel. If first layer is DW this is reduced since the screw will divot the DW before popping the channel. OSB does not divot and will pop the channel. Let’s say you just put a screw part way into the channel for a test without DW or OSB you can easily get some pliers or something and rip it back out. If you add the additional weight of the second layer to the project and do not hit the channel than all the weight of both layers are now on the same number of screws. If you hit the channel on the second layer than all the weight is dispersed across the channels making it stronger. You use shorter screws on the first layer so they do not short out the clips. I would not want to be in there if you did not hit the channels when it all comes down. I even planed and added an additional channel where my Soffit and Coffers where so I could hit them as well. This may have been over kill but is what is recommended on the Sound Proofing Company Web site so I did it. When you attach the ladders for the soffit to the ceiling you can tell a difference when it just hit OSB and it hit the Channel. It synched the ladder tighter to the ceiling if that makes sense. Now if you miss a row because two sheets of DW come together between the channels that will not hurt anything. The convenience of the OSB is that later when doing columns, soffits, coffers, chair molding, crown and anything else that would normally be nailed to the studs now has something to fasten to.


----------



## ellisr63

Makes sense now.


----------



## cgott42

*Is the mass the 2nd/outer door (in an outer room outside theater door setup) critical to sound containment?*


I have a solid core door opening to my HT, this door is surrounded by a 4'x8' "room"/ hallway outside of my HT - with doors on both sides of this hallway.

I bought this MDF door to open to the hallway

see pic - the decorative part can be either glass or MDF. I happen to like the look of the glass better - though I know that drops the mass. Is this an issue - being that it's an outer door - or is the purpose of this door just to create an airlock and mass is not much of a factor?


thx


----------



## brwsaw

I'm admiring the irony in successfully sound proofing my room.

I can't enjoy my equipment unless I'm in the room.

Glad it worked out though.


----------



## blazar




> Quote:
> Originally Posted by *FortKnUX*  /t/1509173/soundproofing-master-thread/300#post_24551191
> 
> 
> Quick question, is it Ok to use 5/8 drywall for backer boxes?



I think the most people would say to use MDF and make box made with wood screws and wood glue. This is how I am currently building my new subwoofer boxes for in-wall use.


----------



## granroth




> Quote:
> Originally Posted by *cgott42*  /t/1509173/soundproofing-master-thread/300_100#post_24582239
> 
> *Is the mass the 2nd/outer door (in an outer room outside theater door setup) critical to sound containment?*
> 
> 
> I have a solid core door opening to my HT, this door is surrounded by a 4'x8' "room"/ hallway outside of my HT - with doors on both sides of this hallway.
> 
> I bought this MDF door to open to the hallway
> 
> see pic - the decorative part can be either glass or MDF. I happen to like the look of the glass better - though I know that drops the mass. Is this an issue - being that it's an outer door - or is the purpose of this door just to create an airlock and mass is not much of a factor?
> 
> 
> thx



According to the Gervais book, he recommends a mass-loaded door if you have a single door and just normal non-mass-added solid core doors if you go the airlock style. That implies that you'd be fine with a door like that as the outer door.


I don't know that I would extrapolate that all to say that the mass isn't much of a factor, though. The reason that you need to add mass to a single door is because the mass of a standard solid core door doesn't equal the mass of both sides of the wall that it's on. The reason you don't need to add mass to two solid core doors is because their combined mass is roughly equivalent to a wall's.


For instance, if we assume that a wall with double layers of 5/8" drywall on both sides (four total layers) has a mass of 8.8pcf and a single solid core door has a mass of 4.5pcf, then it's clear that just one door isn't going to be enough. If you have two of them, though, then we're looking at 9pcf as-is, without doing anything extra, and that's right about where the wall is. Your door, then, won't be the weak spot.


In your case, your second door would have a few stripes where the mass wasn't the same. In fact, if the glass was just a single pane of 1/8" non-laminated float glass (very possible), then you're looking at roughly 1.6pcf wherever the glass is. This is notably lighter than the rest of the door and so it will absolutely be a weak point.


How much of a weak point? I don't know -- that's out of my comfort area. You would be talking about a combined (with the first door) density of roughly 5.1pcf, which isn't terrible. If you really cared, you might consider beefing up the first door to nullify the importance of the second.


----------



## cgott42

Thanks, I like the lookofthedoor, I,ll go with it, and if necessary beef up the mass on the inner door asyou said, thx!


----------



## bigbadbob

Anybody ever try these: http://www.cascadeaudio.com/commercial_residential/speaker_and_lighting_enclosures.htm 


claim an NRC of .75 and STC of 17


RG


----------



## BIGmouthinDC

stc of 17 is pretty whimpy


----------



## bigbadbob

I thought the same thing Big but just thought I would throw it out there. I was looking at building some out of mdf and cement board as you did and stumbled on these.

RG


----------



## mtf612

So I am totally new to room treatment. I started getting interested because I want to reduce noise exiting my theater room and entering into the rest of the house. I understand that this would be quite invasive and/or costly, and so it has become less of a focus. So, instead, I am trying to tighten up the acoustics with the hope of perhaps lowing the volume just a tad for everyone else in the family on Halo night. My plan at this point is to buy foam tape for the single door frame as well as a noise isolating door sweep (anyone have a recommendation?)


In addition, I am looking to purchase twelve 3" 1'x1' wedge tiles and one large 3" 6'x4' wedge tile. I am looking to print out my favorite album covers on fabric and use pins to attach them to the foam. I figure this would be aesthetically pleasing while not disrupting the utility of the wedges. Would this work? I am worried about what cloth to use - obviously a high density fiber will render the foam wedges totally useless, so I'm looking to find a place to print that has something very thin to print on. Again any tips would be awesome.



Would this all make any noticable difference in acoustics? What about volume reduction for the rest of the house? The room is about 12x12x12 with carpeted rugs.

Looking for a cheap non-invasive solution as I will be moving within a couple of years


----------



## brwsaw




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/300#post_24554339
> 
> 
> FWIW, acoustic tests have shown that it doesn't matter at all where the insulation is situated in an air cavity. So Roxul+Air, Air+Roxul, and Air+Roxul+Air are all the same.



Roxul(against the floor) + Air + Ruxol (at the bottom of the joist)+ Air + 5/8" fire rated tile worked for very nicely for me.


No ceiling / canlights.


----------



## granroth




> Quote:
> Originally Posted by *mtf612*  /t/1509173/soundproofing-master-thread/300_100#post_24597640
> 
> 
> So I am totally new to room treatment. I started getting interested because I want to reduce noise exiting my theater room and entering into the rest of the house. I understand that this would be quite invasive and/or costly, and so it has become less of a focus. So, instead, I am trying to tighten up the acoustics with the hope of perhaps lowing the volume just a tad for everyone else in the family on Halo night. My plan at this point is to buy foam tape for the single door frame as well as a noise isolating door sweep (anyone have a recommendation?)



Be a little careful about referring to soundproofing and acoustics or room treatment in the same breath. They are related topics but they are not the same. Soundproofing a room will not help the acoustics (in fact, it'll make them worse in some ways) while acoustic treatments will make a room sound better, but will not soundproof it to any measurable degree.


Sealing a door will absolutely help. if it's done with a solid core door, then you will have essentially removed the door as a weak point, since it would likely perform better than your walls.


A solid recommendation for an automatic door sweep would be a model from Zero International. I hesitate to say a specific model because they have a number and they tend to cover various use cases.


> Quote:
> Originally Posted by *mtf612*
> 
> In addition, I am looking to purchase twelve 3" 1'x1' wedge tiles and one large 3" 6'x4' wedge tile. I am looking to print out my favorite album covers on fabric and use pins to attach them to the foam. I figure this would be aesthetically pleasing while not disrupting the utility of the wedges. Would this work? I am worried about what cloth to use - obviously a high density fiber will render the foam wedges totally useless, so I'm looking to find a place to print that has something very thin to print on. Again any tips would be awesome.



Check out this thread for tons of great info on making aesthetically pleasing panels: DIY Custom Printed Movie Poster Acoustic Panels 


> Quote:
> Originally Posted by *mtf612*
> 
> IWould this all make any noticable difference in acoustics? What about volume reduction for the rest of the house? The room is about 12x12x12 with carpeted rugs.
> 
> Looking for a cheap non-invasive solution as I will be moving within a couple of years



Placed properly, the acoustic tiles will absolutely make a very noticeable difference in sound quality in your room -- it's a definite WOW factor. It won't help with sound reduction for the rest of the house by any measurable amount, though. I see those tiles marketed as "soundproofing" tiles every so often and that's just wrong.


Properly sealing your door should make a difference. How much of a difference can't be predicted, though, since there are so many other factors that can come into play. It's entirely possible that your biggest noise leakage component is completely unrelated to the door and so sealing it won't appear to do anything. You won't know until you try.


----------



## ellisr63

I was just reading this article , and found this statement interesting "The amount of absorption in the cavity has a significant effect on the sound transmission ‐ the 

greater the fraction of the cavity filled with absorption, the higher the sound transmission loss. The sound transmission loss continues to increase with increasing thickness of the absorptive material. With the cavity half‐filled with absorptive material, the sound transmission loss was 

about 5 dB less  than that obtained by filling the cavity completely. ‐ the greater the fraction of the cavity filled with absorption, the higher the sound transmission loss. ". If I am understanding this correctly by filling the cavity with insulation you are increasing the effectiveness of the soundproofing. This also makes me wonder about what would happen with a double wall construction if you fill the whole cavity with insulation versus having a gap.


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/300_100#post_24601189
> 
> 
> I was just reading this article , and found this statement interesting "The amount of absorption in the cavity has a significant effect on the sound transmission ‐ the
> 
> greater the fraction of the cavity filled with absorption, the higher the sound transmission loss. The sound transmission loss continues to increase with increasing thickness of the absorptive material. With the cavity half‐filled with absorptive material, the sound transmission loss was
> 
> about 5 dB less  than that obtained by filling the cavity completely. ‐ the greater the fraction of the cavity filled with absorption, the higher the sound transmission loss. ". If I am understanding this correctly by filling the cavity with insulation you are increasing the effectiveness of the soundproofing. This also makes me wonder about what would happen with a double wall construction if you fill the whole cavity with insulation versus having a gap.



Ah.. it turns out that this was the second question asked in this thread. Start here and read the next four or five posts: Post #10 


The TL;DR is that when they talk about a "cavity", they are not referring to the space between the walls, but rather the space between the studs within a wall... so filling that gap will not help by any measurable amount.


FWIW, I tried asking a related question here and elsewhere that I never got a solid answer to -- does filling the gap _hurt_ performance. That is, it's well established that it doesn't help soundproofing, but I haven't found any definitive proof on whether or not it would actually make things worse.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/330#post_24601222
> 
> 
> Ah.. it turns out that this was the second question asked in this thread. Start here and read the next four or five posts: Post #10
> 
> 
> The TL;DR is that when they talk about a "cavity", they are not referring to the space between the walls, but rather the space between the studs within a wall... so filling that gap will not help by any measurable amount.
> 
> 
> FWIW, I tried asking a related question here and elsewhere that I never got a solid answer to -- does filling the gap _hurt_ performance. That is, it's well established that it doesn't help soundproofing, but I haven't found any definitive proof on whether or not it would actually make things worse.



When we were doing our walls we did our studs on 24" centers (inner walls)... When I went to get the insulation for it I found out that it was for at least a 6" stud and we had 2x4s. I called the Soundproofing Company and was told not to worry about the insulation touching the outer wall insulation as it was not dense enough to link the 2 together. I just found this article to be very interesting and it seemed to me to reinforce that it was not a problem to worry about and actually made me think that it might be better to do. BTW, the link I provided has a lot of excellent articles on everything for Studios (it is very good reading IMO). I guess we will see if it does hurt the STC rating on my room when it is completed. My thinking on this is I am doing the best that I can and that it will still be better than maybe 75% of the HT rooms people build, as I have read that even some of the Pro built HT rooms are not built properly when using clips and channels. If I can reduce sound by 50-60db I will be very happy.


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/300_100#post_24601244
> 
> 
> When we were doing our walls we did our studs on 24" centers (inner walls)... When I went to get the insulation for it I found out that it was for at least a 6" stud and we had 2x4s. I called the Soundproofing Company and was told not to worry about the insulation touching the outer wall insulation as it was not dense enough to link the 2 together. I just found this article to be very interesting and it seemed to me to reinforce that it was not a problem to worry about and actually made me think that it might be better to do. BTW, the link I provided has a lot of excellent articles on everything for Studios (it is very good reading IMO). I guess we will see if it does hurt the STC rating on my room when it is completed. My thinking on this is I am doing the best that I can and that it will still be better than maybe 75% of the HT rooms people build, as I have read that even some of the Pro built HT rooms are not built properly when using clips and channels. If I can reduce sound by 50-60db I will be very happy.



Well, that's good to hear that the guys at the Soundproofing Company aren't concerned about fiberglass bridging the gap. I strongly suspected that that was the case, but it's nice to hear confirmation. I'm going to be doing a tiny bit of that in my own build, so that eases my mind a bit.


An yeah, JH Brandt has some excellent stuff on his website. He's also very active on a few forums. I'd say that JH Brandt and Rod Gervais are the two most prolific and helpful tier-one acoustic experts out there now, so anything that they say I essentially take as gospel truth. They do sometimes leave some notable gaps in their descriptions of things, though, and it's not always clear to non-experts if the gaps are due to things that don't matter or if it's something that they expect us to know! The whole semantics about a "cavity" is one of those gaps. Handily, this is the age of the Internet and so we can simply ask for clarification and get it


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/330#post_24599921
> 
> 
> Soundproofing a room will not help the acoustics



That's not quite right.


Soundproofing lowers the masking noise from outside the room. In addition to lowering car traffic and walking traffic and plumbing noises through the walls/ceiling, it should include lowering the HVAC noise. And equipment should be placed so that it's soundproofed as well, again lowering the masking noise from their fans.


With a lower noise floor (NR rating) -- or to say the same thing another way, a lack of masking noise -- you don't have to constantly be turning the volume up and down [up so you can understand the voices, and down because it hurts], because the effective dynamic range of the room is increased so you can still hear the quiet bits. That's an obvious acoustic benefit.


There are two lesser side effects of this:

a) acoustically - because you don't have to turn up the volume, you can play everything at a lower volume and still hear it, and the loud parts won't be excessive, such loud parts which may damage your hearing, affecting the future perceived acoustic quality, and

b) soundproofing - because you don't have to turn up the volume, you won't be surprised by a loud part, and being quieter reduces the amount of noise outside the room. _


On a related note, running a jackhammer in your basement to break up the entire floor, so that you can build a floating room to get 3 more STC points, isn't going to help if you loose 3 dB sensitivity in your ears as a result, and after the room is built you have to turn the volume up to compensate._


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/330#post_24601222
> 
> 
> does filling the gap _hurt_ performance.


No, provided the insulation doesn't couple the leaves.

If you're using fluffy fiberglass pink, its pretty much impossible to couple the leaves.

If you're using open cell foam, its fairly easy to couple the leaves.


I think you're probably fine even with rigid rockwool touching both leaves, but I don't recall an experiment for walls about it. The reason I think it's probably fine, is because some people use rigid rockwool to float a room on top of. (the rockwool becomes the 'spring') It's not as good as an engineered material (Solymer, or springs like Kinetics or those in Galaxy), and I'm not sure if it lasts more than a couple decades, but it used to be done.


----------



## granroth




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/300_100#post_24601798
> 
> 
> That's not quite right.
> 
> 
> Soundproofing lowers the masking noise from outside the room. In addition to lowering car traffic and walking traffic and plumbing noises through the walls/ceiling, it should include lowering the HVAC noise. And equipment should be placed so that it's soundproofed as well, again lowering the masking noise from their fans.
> 
> 
> With a lower noise floor (NR rating) -- or to say the same thing another way, a lack of masking noise -- you don't have to constantly be turning the volume up and down [up so you can understand the voices, and down because it hurts], because the effective dynamic range of the room is increased so you can still hear the quiet bits. That's an obvious acoustic benefit.
> 
> 
> There are two lesser side effects of this:
> 
> a) acoustically - because you don't have to turn up the volume, you can play everything at a lower volume and still hear it, and the loud parts won't be excessive, such loud parts which may damage your hearing, affecting the future perceived acoustic quality, and
> 
> b) soundproofing - because you don't have to turn up the volume, you won't be surprised by a loud part, and being quieter reduces the amount of noise outside the room. _
> 
> 
> On a related note, running a jackhammer in your basement to break up the entire floor, so that you can build a floating room to get 3 more STC points, isn't going to help if you loose 3 dB sensitivity in your ears as a result, and after the room is built you have to turn the volume up to compensate._



That's quite true -- the intro post to this thread even brings up that crucial point, so thank you for clarifying that.


I do want to expand a bit on what I said, though, since it was clearly incomplete and not very well worded... but I think there might be an important point hiding in there.


We almost always think of soundproofing a room and acoustically treating a room as two very separate things (even though they are both technically all about acoustics) since they address completely different aspects of sound. You soundproof to reduce sound leakage in and out and to lower the noise floor in the treated space. You acoustically treat a room to control reflections and flutter and ringing and all the fun stuff like that. Put another way, soundproofing keeps sound waves from leaving or entering the treated space and acoustic treatments treat the sound waves that are already in the space. Those are complementary but non-overlapping concerns.


If you think of it in that way, then it follows that soundproofing can actually make the sound in the room (temporarily) WORSE.


Okay, I started thinking about this after watching a Home Theater Geeks podcast with Keith Yates (HTG#197). Keith has some very strong opinions on various acoustic topics that he shared in that episode and one of his more jarring ones was here: Home Theater Geeks 197: How low can you go? - 20:08 . In this section, he refers to people who soundproof a room as being "misguided souls". Why? Well, he's talking about the differences in sound levels for various modes on a seat by seat basis. In a room with massive walls, defined as two or three layers of drywall or concrete, then you might see differences on a seat by seat basis of up to 50dB. That is, you might hear the sound at 100dB in one seat but that same sound is only 50dB in the next seat over.


This is necessarily going to be worse the more soundproofed a room is. In a non-soundproofed room, a lot of the sound waves "escape" the room -- if they aren't there, then they can't be reflecting and causing any standing waves or nulls or anything of the sort. The more you soundproof a room, the more the waves will reflect in the room, and the more problems you are going to have.


Bass, in particular, is going to be notably worse. This is because the high energy and wide frequencies of lower frequencies are tougher to control in a small room than higher frequencies. If you have a room that puts up no real barriers to bass, then a lot of that energy will escape and you won't need to control it.


So that was my intended point -- that the more you soundproof a room, the more the sound being generated in the room is going to reflect in itself and the worse it is all going to sound as a result (until you acoustically treat the room).


Thoughts?


----------



## kmhvball


I had an idea on electric wiring which, I wondered what people's thoughts were on it.... this may well have been discussed already, but thought I would throw out there anyway.

 

I am doing my walls & ceiling with OSB, then green glue, then 5/8" drywall.  

On my wall's, I'll likely be doing some fabric frames/ acoustic panels, but plan to mount electric onto some 4/4" x something materials (maybe 2 sheets of 1/2" MDF made into a 'flattish' column).  I am leaning towards a new LED 'recessed' light that mounts in a shallow depth box, i.e., no backer box - just a normal circular mounting box.

 

So, my thought is stubbing out the electric wire through the OSB, putting an electric box on - screwed into the OSB for support, and then adding the drywall, and in the case of walls with 1" column'ish' type mounting.  In the case of the ceiling doing very shallow depth boxes.  This minimizes the 'hole' in the structure, and only requires then filling the one small penetration with acoustic caulk vs putty pads, etc.

 

Here are some pictures of what I am considering:

 

First, stub electric wire through OSB...  

 

 

Put wire through box... 

 

Then mount box itself onto OSB.. 

 

Then put drywall on... 

 

 

Obviously not pictured is the ~ 1" deep solid column like material (may be horizontal strips vs vertical columns, but either way).  I would think if mounting fabric panels, this could still be done, but I would need to put structural support around the electric box for the fabric to attach to anyway.

 

Any thoughts on whether this would help reduce sound transmission?   I was also thinking this then also gets around the need to 'build out' the electric box based on depth of the wall, so, 2 birds with one stone type of idea.

 

Thanks for your thoughts!


----------



## ellisr63




> Quote:
> Originally Posted by *kmhvball*  /t/1509173/soundproofing-master-thread/330#post_24611352
> 
> I had an idea on electric wiring which, I wondered what people's thoughts were on it.... this may well have been discussed already, but thought I would throw out there anyway.
> 
> I am doing my walls & ceiling with OSB, then green glue, then 5/8" drywall.
> 
> On my wall's, I'll likely be doing some fabric frames/ acoustic panels, but plan to mount electric onto some 4/4" x something materials (maybe 2 sheets of 1/2" MDF made into a 'flattish' column).  I am leaning towards a new LED 'recessed' light that mounts in a shallow depth box, i.e., no backer box - just a normal circular mounting box.
> 
> So, my thought is stubbing out the electric wire through the OSB, putting an electric box on - screwed into the OSB for support, and then adding the drywall, and in the case of walls with 1" column'ish' type mounting.  In the case of the ceiling doing very shallow depth boxes.  This minimizes the 'hole' in the structure, and only requires then filling the one small penetration with acoustic caulk vs putty pads, etc.
> 
> Here are some pictures of what I am considering:
> 
> 
> First, stub electric wire through OSB...
> 
> 
> 
> Put wire through box...
> 
> 
> 
> Then mount box itself onto OSB..
> 
> 
> 
> Then put drywall on...
> 
> 
> 
> Obviously not pictured is the ~ 1" deep solid column like material (may be horizontal strips vs vertical columns, but either way).  I would think if mounting fabric panels, this could still be done, but I would need to put structural support around the electric box for the fabric to attach to anyway.
> 
> 
> Any thoughts on whether this would help reduce sound transmission?   I was also thinking this then also gets around the need to 'build out' the electric box based on depth of the wall, so, 2 birds with one stone type of idea.
> 
> 
> Thanks for your thoughts!



Are you going to caulk the hole the wire goes through before you put the box on? I think it would be ok if you do for acoustics (but I am not an electrician)... I have seen some pictures where the clay sheets were put on the inside of the outlet boxes to shield for fire too. I would think as long as there is no way for the air or or noise to escape through the outlet you would be ok.


----------



## BIGmouthinDC

I've been bringing wires into the theater for some time and caulking around them with acoustical caulk. Yes it does help with soundproofing. Behind the screen wall you can mount a surface mounted box, no problem. In the open theater I often stick the outlets in the side of columns. On the side least visible.


----------



## kmhvball




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/330#post_24611573
> 
> 
> 
> Are you going to caulk the hole the wire goes through before you put the box on? I think it would be ok if you do for acoustics (but I am not an electrician)... I have seen some pictures where the clay sheets were put on the inside of the outlet boxes to shield for fire too. I would think as long as there is no way for the air or or noise to escape through the outlet you would be ok.


 

 


> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/330#post_24611596
> 
> 
> I've been bringing wires into the theater for some time and caulking around them with acoustical caulk. Yes it does help with soundproofing. Behind the screen wall you can mount a surface mounted box, no problem. In the open theater I often stick the outlets in the side of columns. On the side least visible.


 

I will definitely be using Caulk for these boxes & along other locations.  I'll likely use OSI SC175, as I think it maintains its' flexibility, and is less expensive than 'labeled' acoustic sealant.  My understanding & Hope is that this works essentially just as well as long as I don't get something that turns rigid.

I am about to place my order with Ted White/John Hile, likely today, for 6, 5 gallon tubs, some sound clips, door sill/surround, etc.   There is~ $2,500 I didn't have in my original budget.... darn this Forum for educating me (at least a little bit!).   I guess better $2,500 now than having to re-do it later.    That of course, is before the actual doors & extra drywall/osb layers and installation.   I hope it all works out!!!


----------



## panino




> Quote:
> Originally Posted by *kmhvball*  /t/1509173/soundproofing-master-thread/330#post_24612372
> 
> 
> 
> I will definitely be using Caulk for these boxes & along other locations.  I'll likely use OSI SC175, as I think it maintains its' flexibility, and is less expensive than 'labeled' acoustic sealant.  My understanding & Hope is that this works essentially just as well as long as I don't get something that turns rigid.


 

I've been using OSI SC-175 on my build.  Planning on caulking the hell out of every little peep hole I see.  I can't attest to its effectiveness vs other acoustic sealants out there, but the stuff that has already "cured" for a few weeks is solid enough to hold in place, but you can bend it and it does remain flexible.  Seems like it should do the trick.


----------



## ellisr63

I have been using 40year caulk from Ace Hardware (store brand)... I hope it lasts 20 years.


----------



## granroth




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/300_100#post_24615208
> 
> 
> I've been using OSI SC-175 on my build.  Planning on caulking the hell out of every little peep hole I see.  I can't attest to its effectiveness vs other acoustic sealants out there, but the stuff that has already "cured" for a few weeks is solid enough to hold in place, but you can bend it and it does remain flexible.  Seems like it should do the trick.



Yep, OSI SC-175 is definitely a good one. There was a discussion about acoustic caulk on the first page of this thread. I tried to summarize the discussion here: Acoustic Caulk Summary 


Basically, any caulk advertised as "50 year guarantee" will be fine. Also, expect it to cost _less_ than lots of caulk sold at the big box stores -- that was a surprise to me.


While I'm at it -- there was also a discussion on the proper way to use caulk in a theater. The actual start was on the first page, but I re-started the thread (with great drawing by BasementBob) here: Proper Caulking Technique


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/330#post_24615590
> 
> 
> Yep, OSI SC-175 is definitely a good one. There was a discussion about acoustic caulk on the first page of this thread. I tried to summarize the discussion here: Acoustic Caulk Summary
> 
> 
> Basically, any caulk advertised as "50 year guarantee" will be fine. Also, expect it to cost _less_ than lots of caulk sold at the big box stores -- that was a surprise to me.
> 
> 
> While I'm at it -- there was also a discussion on the proper way to use caulk in a theater. The actual start was on the first page, but I re-started the thread (with great drawing by BasementBob) here: Proper Caulking Technique



Do you think the 40 year would be good too?


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/300_100#post_24615608
> 
> 
> Do you think the 40 year would be good too?



Don't take anything I'm about to say as the gospel truth -- depend on somebody like @BasementBob for that.


BUT, let's look at that caulk gives us and what makes acoustical caulk "acoustical". Caulk's purpose in a theater environment is to block airflow from traveling from a treated space to an untreated space. It essentially adds mass to an area where there previous was none (a gap of some sort). For it to really work, it needs to completely fill the gap, or else air will still be able to travel back and forth and sound will travel along with it.


Any caulk will fill in a reasonable sized gap and so from that perspective, any caulk would do.


Alas, that would be a short-sighted view. Regular caulk will eventually become hard and when it does, it will invariably shrink or crack. So if you fill in a gap fully with normal caulk, it may stay full for some amount of time, but it will eventually shrink or crack and air will get through.


50 year caulk is named thus because it gives a 50 year guarantee against shrinking or cracking. That's likely going to be the life of the theater, and so it's essentially "lifetime" caulk. Since it'll remain pliable and fully filling the gap for the foreseeable future, we call it acoustical caulk.


So now let's look at 40 year caulk. If it's giving you a 40 year guarantee against shrinking or cracking then yes, I'd call that acoustical caulk as well. That is, it'll keep that gap filled for likely as long as you have the theater.


But... I'm not going to guarantee that. The reason why is because you have to be a little suspicious why it has a 40 year guarantee rather than a 50 year one. That seems like an odd distinction to make. It could just be my paranoid nature, though.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/330#post_24615815
> 
> 
> Don't take anything I'm about to say as the gospel truth -- depend on somebody like @BasementBob for that.
> 
> 
> BUT, let's look at that caulk gives us and what makes acoustical caulk "acoustical". Caulk's purpose in a theater environment is to block airflow from traveling from a treated space to an untreated space. It essentially adds mass to an area where there previous was none (a gap of some sort). For it to really work, it needs to completely fill the gap, or else air will still be able to travel back and forth and sound will travel along with it.
> 
> 
> Any caulk will fill in a reasonable sized gap and so from that perspective, any caulk would do.
> 
> 
> Alas, that would be a short-sighted view. Regular caulk will eventually become hard and when it does, it will invariably shrink or crack. So if you fill in a gap fully with normal caulk, it may stay full for some amount of time, but it will eventually shrink or crack and air will get through.
> 
> 
> 50 year caulk is named thus because it gives a 50 year guarantee against shrinking or cracking. That's likely going to be the life of the theater, and so it's essentially "lifetime" caulk. Since it'll remain pliable and fully filling the gap for the foreseeable future, we call it acoustical caulk.
> 
> 
> So now let's look at 40 year caulk. If it's giving you a 40 year guarantee against shrinking or cracking then yes, I'd call that acoustical caulk as well. That is, it'll keep that gap filled for likely as long as you have the theater.
> 
> 
> But... I'm not going to guarantee that. The reason why is because you have to be a little suspicious why it has a 40 year guarantee rather than a 50 year one. That seems like an odd distinction to make. It could just be my paranoid nature, though.


If it lasts 30 years I will be happy.


----------



## BIGmouthinDC

Just a factoid, for a period of time, the God Father of Green Glue (TW) was shipping the OSI product instead of the Green Glue branded product, can't remember why. I used it and it works just like nearly every other acoustical caulk, I've also used "Sheetrock" brand.


----------



## granroth

On that note, I'd say that the other creator of Green Glue is Brian Ravnaas and he even talks about OSI vs dedicated acoustical sealants back in 2007:


> Quote:
> Originally Posted by *Brian Ravnaas*  /t/765365/who-makes-acoustical-caulk/0_100#post_10271906
> 
> 
> The advantage of an "acoustical sealant" is permanent flexiblity, so that the seals don't fail when building shift a bit, or the film doesn't just degrade over time and stop sealing.
> 
> 
> I don't feel that all of the acoustical sealants sold necessarily have any advantage over normal old boring caulks available everywhere in this regard (though some certainly may), and with the exception noted above about resilient edges of walls (an additional such case might be if the wall is floated on some type of resilient layer such as that sold by Kinetics), the properties of the sealant become less important than ensuring that a good seal exists.
> 
> 
> Truly, for a normal wood stud wall bolted to whatever surface is below, it is just that a good seal exists that is important, except perhaps from a longevity standpoint.
> 
> 
> You folks can hold me to that when the day comes that GGCo releases a sealant.


----------



## panino




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/330#post_24615973
> 
> 
> 
> If it lasts 30 years I will be happy.


 

I'd be happy with 20-30 years. I too, like granroth wonder why some of these companies are only guaranteeing 40 years instead of 50?  More importantly is who is actually still around to test, let alone remember to test the caulk they stuck on 50 years ago to make sure it lasts that long?  I wonder if this is a bit of a marketing ploy... sorta like 7 minute abs or "my amplifier goes to 11".


----------



## ellisr63

It would be interesting to see if they actually honor the 50 year warranty too. I am retired so 20-30 years is more than enough for me... I think.


----------



## BIGmouthinDC

those warranties only cover the cost of the original material. So if you paid $5 that will be like a nickel in 2064


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/330#post_24618804
> 
> 
> those warranties only cover the cost of the original material. So if you paid $5 that will be like a nickel in 2064


If they even honored it... In California a lifetime warranty is only 5 years. I don't know how they would look at a 40 or 50 year warranty on a $5 product. I have a feeling the warranty would not even be worth pursuing. So basically we are at the mercy of the manufacturer to be telling us the truth, rather than just marketing it as a 40 year or 50 year product. I don't have a whole lot of faith in relying on a Company to be honest about a product to last 40-50 years. I think the number crunchers are counting on A: you don't live that long, B: They won't be around anymore making that product in 40-50 years.


----------



## panino


After a lot of thought I've decided to quit my current job and start manufacturing 51 year caulk and just take over the entire caulking industry.


----------



## ellisr63




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/330#post_24619049
> 
> 
> After a lot of thought I've decided to quit my current job and start manufacturing 51 year caulk and just take over the entire caulking industry.


There ya go!







I think I would up it a few years for marketing though.


----------



## cw5billwade

I go on a 11 day cruise and come back to a lot of good discussion


----------



## BasementBob




----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/330#post_24602419
> 
> 
> Thoughts?



Ok, some thoughts...


Certainly walls/ceilings/floors have absorption coefficients. And from a Sabine Equation point of view there's a lot of surface area -- all available area is walls/ceiling/floor -- so walls really add up, thin walls being incredibly dominant absorbers.


Absorption Coefficients

Simple wall {1/2" drywall, 3.5" studs without insulation, 1/2" drywall).

125hz: .30

500hz: .10

1000hz: .05

2000hz: .04

4000hz: .07

8000hz: .09


Solid Concrete Wall, 8" thick

125hz: .01

500hz: .01

1000hz: .01

2000hz: .02

4000hz: .02

8000hz: .02


Lots of absorption coefficients for walls on the internet.


Technically walls combine absorption and transmission into getting sound out of the room (anything staying in would be reflection), but from an energy point of view I suspect that transmission might be significantly smaller.


Let's say you have a pretty good wall STC67 with 20dB of transmission loss at 50hz. That wall is transmitting 1% of the energy that's hitting it, with 99% being either reflected or absorbed.
http://www.bobgolds.com/RT60/rt60.htm 


But the biggest absorption, and the biggest issue, isn't on a 125hz-8000hz coefficient chart, it's at F0, wall resonance.

It would be better if that happened to be at a problem room mode, but it never is.

Worst case is it sucks so much life out of near F0 that you can't compensate for it with speakers -- at least in the Holy Grail That Isn't Actually As Good As Anyone Really Wants sense of the 'flat frequency response' at all seats.


Its better to have walls with resonance lower than you're going to be listening to, or at least as low as possible, and then use more predictable broadband absorption to deal with the other issues such as room modes.


> Quote:
> Fo=170/sqrt of m*d,
> 
> where
> 
> Fo is the resonant frequency in hZ,
> 
> m = surface density of the panel in lb/sq ft, and
> 
> d = depth of air space in inches.
> 
> 
> for example, 5/8 drywall with a 3.5" air gap works out to around 60 hZ - with no insulation inside, this peak will be only about an octave wide; with insulation, it should broaden out to around 2-3 octaves usable, with its peak about 20% less than without insulation.


----------



## pyrodex

Few questions:


I saw in this thread or another (can't remember) the debate about the OSB/DW vs DW/DW and it was reported as negligible difference. I saw the benefit is for mounting and screwing straight into the OSB and I would assume you would use screws small enough to not puncture the OSB but enough to provide support on mounting elements such as soffits or speakers. Correct? What size and type of screws can people recommend in this setup if OSB is used?
I have a hardwood floor kitchen above my theater and have seen the recommendations of putting GG/DW/GG/DW on the subfloor between the joists and wondered if anyone could recommend the best screws and sizes for that mounting?
What are the best screws to mount the OSB to the channels?
My theater room is three full wall concrete and then a normal wall. I've heard about floating a wall from reading here if it isn't load barring but if it is load barring the staggered stud method is preferred correct?
On the wall that isn't concrete would it be recommended to do sound channels on both sides since that wall could bleed into the other basement spaces?
For the three remaining concrete walls I assume I would build a floating wall and then attach them to the ceiling joists with clips for just merely support right?
For the three concrete walls living in the south (Georgia) I would assume I putting XPS closed cell between the concrete and the studs w/insulation would be the ideal wall setup to prevent mold etc?
Not sure if this is sound proofing or not but since the floor is concrete would people recommend a subfloor such as dricore knowing I will have carpet as the final product?


Thanks in advance, I have so many questions swirling in my head.


----------



## BIGmouthinDC

if you are using clips and channel your screws can actually pass through the OSB 7/8 of an inch, the height of the furring channel and you have won't have any concerns about hitting a stud or joist. Just be sure you don't have any wires or pipes hanging proud of the framing.


When attaching OSB and Drywall to channel use fine thread drywall screws designed for light weight metal, I use 1 1/4 on the first layer 2 inches on the second irregardless if it is OSB or DW. Personally I like the Grabber brand screws.


On attaching drywall under the subfloor assuming you are attaching 5/8 drywall and the subfloor is at least 3/4 thick I would not use anything longer than a 1 3/8 screw. To be really safe just use 1 1/4. You don't want to grab hold of the actual wood floors above as some day you may want to replace them.


----------



## granroth

I'm not going to comment on anything that requires knowledge of your local building code (vapor barriers and the like) nor anything BIG touched on. The rest...


> Quote:
> Originally Posted by *pyrodex*  /t/1509173/soundproofing-master-thread/300_100#post_24625048
> 
> 
> My theater room is three full wall concrete and then a normal wall. I've heard about floating a wall from reading here if it isn't load barring but if it is load barring the staggered stud method is preferred correct?



If you have four existing walls, then any wall you build is NOT going to be load bearing. Therefore, that doesn't come into play. If you are going to replace a load bearing wall, then you'll want to get a structural engineer to draw up a plan for the new wall. If the new recommended wall would be 2x6 based, then might as well do a staggered stud wall. Otherwise, staggered stud is typically only used if space and cost are both a huge concern.


> Quote:
> Originally Posted by *pyrodex*  /t/1509173/soundproofing-master-thread/300_100#post_24625048
> 
> 
> On the wall that isn't concrete would it be recommended to do sound channels on both sides since that wall could bleed into the other basement spaces?



By sound channels, I'm assuming clips and channels. In that case, no, you only need to do one side. You could do both, but it would almost surely not be worth the cost per performance. The point of the clips and channels is to decouple the mass layer (drywall) from the studs. Since your drywall is only connected to the channels (and caulked all the way around), there should be minimal sound "bleed" ("flanking").


> Quote:
> Originally Posted by *pyrodex*  /t/1509173/soundproofing-master-thread/300_100#post_24625048
> 
> 
> For the three remaining concrete walls I assume I would build a floating wall and then attach them to the ceiling joists with clips for just merely support right?



Yes.


If you are going to do floating walls for three of the four, and if you can spare another 3-1/2", then you might consider doing a floating wall on the fourth wall, as well. In that case, you'd have a "room-in-a-room", which is the gold standard for soundproofing (compared to clips+channels or staggered stud).


----------



## ellisr63

I just found this http://www.shop3m.com/3m-fire-barrier-sealant-cp-25wb-5-gallon-pail.html?WT.ac=US_EnterpriseCatalog_98040053815 ... Too bad it is so much more expensive. I do wonder if it actually is better STC wize though.


----------



## ellisr63

Has anyone ever tried putting the putty pads inside the outlet instead of on the outside?
http://www.fireus.co.uk/fireus-puttypads.html 


I ask this because we have one outlet that is going to be a major pain to do if we have to do it on the outside.


----------



## ellisr63

I found this in another forum and I wonder if this would help on fluffy fiberglass too ... "Before stuffing the sound panels with Rockwool, I highly recommend picking up some PVA Solution (PolyVinyl Alchohol) to spray on the Rockwool panels to keep the fibers from floating around your studio and into your lungs. I've heard Rockwool Fibers are harmless but I wasn't taking any chances. Oh yeah, PVA is typically used to release fiberglass panels from molds.


A gallon of PVA was more than enough to cover front, backs and sides 40+ rockwool panels I cut. A 10 to 1 ratio of water to Rockwool is a standard amount but I went with a 3 to 1 just to make sure I got a thick film on the sheets. I just mixed it in a typical spray bottle but I guess you could use one of those weed sprayer pump deals if you wanted."


----------



## BasementBob




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/360#post_24627448
> 
> 
> Has anyone ever tried putting the putty pads inside the outlet instead of on the outside?



Don't do that.


The purpose of the metal receptacle outlet box is so that if a live wire comes lose from the receptacle (female plug), the bare copper will contact the grounded metal box and throw the circuit breaker, preventing a fire.


There's also a specification for how many current carrying conductors and devices you can put into a receptacle metal box, to give enough air around to allow for safety when the parts themselves overheat due to overload or close to tolerance wattage loading. If you put too much stuff in there, you get a fire.


----------



## BasementBob




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/360#post_24627418
> 
> 
> I just found this http://www.shop3m.com/3m-fire-barrier-sealant-cp-25wb-5-gallon-pail.html?WT.ac=US_EnterpriseCatalog_98040053815 ... Too bad it is so much more expensive. I do wonder if it actually is better STC wize though.



Don't use fire barrier sealant when you want acoustical sealant. (Nor vice versa)


----------



## ellisr63




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/360#post_24627727
> 
> 
> Don't do that.
> 
> 
> The purpose of the metal receptacle outlet box is so that if a live wire comes lose from the receptacle (female plug), the bare copper will contact the grounded metal box and throw the circuit breaker, preventing a fire.
> 
> 
> There's also a specification for how many current carrying conductors and devices you can put into a receptacle metal box, to give enough air around to allow for safety when the parts themselves overheat due to overload or close to tolerance wattage loading. If you put too much stuff in there, you get a fire.


I have the plastic outlet box... Would it still be a problem?


----------



## BasementBob




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/360#post_24627483
> 
> 
> I found this in another forum and I wonder if this would help on fluffy fiberglass too ... "Before stuffing the sound panels with Rockwool, I highly recommend picking up some PVA Solution (PolyVinyl Alchohol) to spray on the Rockwool panels to keep the fibers from floating around your studio and into your lungs. I've heard Rockwool Fibers are harmless but I wasn't taking any chances. Oh yeah, PVA is typically used to release fiberglass panels from molds.
> 
> 
> A gallon of PVA was more than enough to cover front, backs and sides 40+ rockwool panels I cut. A 10 to 1 ratio of water to Rockwool is a standard amount but I went with a 3 to 1 just to make sure I got a thick film on the sheets. I just mixed it in a typical spray bottle but I guess you could use one of those weed sprayer pump deals if you wanted."



Rockwool fibers tend to be quite large, compared to asbestos, and are safe.

They become safer still when they are encased in something, like drywall or other fire resistant material like fabric GoM (Gilford of Maine FR701).

Only bare insulation in air ducts needs to be coated, and for that I'd buy purpose built stuff, rather than spraying something onto it.


----------



## BasementBob




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/360#post_24627734
> 
> 
> I have the plastic outlet box... Would it still be a problem?



Plastic outlet boxes don't have the "instant short" feature, but at least they're electrical insulators rather than conductors. As long as your building code allows them for that use, they're fine.


A plastic electrical box will have more space for electrical conductors than metal boxes. Plastic outlet boxes still have a maximum number of 'conductors' (conductors = wires + devices) you can put into them, and around here electrical code probably wouldn't include putty. The plastic boxes are usually made larger than the metal ones, because plastic is less able to handle the heat of max wattage load circuits -- so a little more air around everything balances things out.


Typically, lately, residential is plastic and commercial is metal. If using metal conduit, then metal boxes are required. The metal boxes require grounding, which is more work, in addition to being metal which is a more expensive material too -- which is why plastic is becoming popular (saves time, money).


Personally, I'm fond of metal boxes, even in residential.


Plastic, from a soundproofing point of view, might be more air tight all by itself. Similarly, on an outside wall (receptacle inside the house) there's less chance of a draft with a plastic receptacle.


As for putty, I've never seen anyone put putty on the inside of a receptacle box. Soundproofing, and building a fire safe home, is not something to experiment with. Find the way the experts do it, and copy. That's my opinion.

(If you find a putty manufacturer that shows putting putty inside the plastic receptacle box; and a local electrical inspector that says putting putty inside a lightly filled receptacle box is fine; then fine. Maybe.)


----------



## ctviggen




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/360#post_24627781
> 
> 
> Plastic outlet boxes don't have the "instant short" feature, but at least they're electrical insulators rather than conductors. As long as your building code allows them for that use, they're fine.
> 
> 
> A plastic electrical box will have more space for electrical conductors than metal boxes. Plastic outlet boxes still have a maximum number of 'conductors' (conductors = wires + devices) you can put into them, and around here electrical code probably wouldn't include putty. The plastic boxes are usually made larger than the metal ones, because plastic is less able to handle the heat of max wattage load circuits -- so a little more air around everything balances things out.
> 
> 
> Typically, lately, residential is plastic and commercial is metal. If using metal conduit, then metal boxes are required. The metal boxes require grounding, which is more work, in addition to being metal which is a more expensive material too -- which is why plastic is becoming popular (saves time, money).
> 
> 
> Personally, I'm fond of metal boxes, even in residential.
> 
> 
> Plastic, from a soundproofing point of view, might be more air tight all by itself. Similarly, on an outside wall (receptacle inside the house) there's less chance of a draft with a plastic receptacle.
> 
> 
> As for putty, I've never seen anyone put putty on the inside of a receptacle box. Soundproofing, and building a fire safe home, is not something to experiment with. Find the way the experts do it, and copy. That's my opinion.
> 
> (If you find a putty manufacturer that shows putting putty inside the plastic receptacle box; and a local electrical inspector that says putting putty inside a lightly filled receptacle box is fine; then fine. Maybe.)



You can put putty on the outside of boxes, typically. I used to like metal boxes, but if you've ever had to redo boxes once they're installed, plastic is easy, whereas metal would be brutal. For instance, I've cut out a ton of plastic boxes (to run more wires into the box or go from a single gang to a dual gang), and I can easily cut the plastic boxes with a dremel tool. I don't have to cut drywall (unless I'm increasing the box's size). A metal box? I think you'd have to cut drywall or it'd take a long, long time to drill though the box.


I'll give you an example, which I did this weekend. You have a switch on a wall as you enter a room, where the switch controls a switched outlet. You want to add a ceiling fan/light combo instead. You rewire so the power goes to the switch location and the outlet is no longer switched. You cut the drywall to go from one to two gangs, then carefully cut out the plastic box so that you don't cut or damage the wires. You run the 12/3 or 14/3 from the new box to the ceiling fan box (that you also just installed), and wire everything up. I've done this at least 5 times in two different houses. If you had a metal box, this process would take much longer.


----------



## ellisr63




> Quote:
> Originally Posted by *BasementBob*  /t/1509173/soundproofing-master-thread/360#post_24627781
> 
> 
> Plastic outlet boxes don't have the "instant short" feature, but at least they're electrical insulators rather than conductors. As long as your building code allows them for that use, they're fine.
> 
> 
> A plastic electrical box will have more space for electrical conductors than metal boxes. Plastic outlet boxes still have a maximum number of 'conductors' (conductors = wires + devices) you can put into them, and around here electrical code probably wouldn't include putty. The plastic boxes are usually made larger than the metal ones, because plastic is less able to handle the heat of max wattage load circuits -- so a little more air around everything balances things out.
> 
> 
> Typically, lately, residential is plastic and commercial is metal. If using metal conduit, then metal boxes are required. The metal boxes require grounding, which is more work, in addition to being metal which is a more expensive material too -- which is why plastic is becoming popular (saves time, money).
> 
> 
> Personally, I'm fond of metal boxes, even in residential.
> 
> 
> Plastic, from a soundproofing point of view, might be more air tight all by itself. Similarly, on an outside wall (receptacle inside the house) there's less chance of a draft with a plastic receptacle.
> 
> 
> As for putty, I've never seen anyone put putty on the inside of a receptacle box. Soundproofing, and building a fire safe home, is not something to experiment with. Find the way the experts do it, and copy. That's my opinion.
> 
> (If you find a putty manufacturer that shows putting putty inside the plastic receptacle box; and a local electrical inspector that says putting putty inside a lightly filled receptacle box is fine; then fine. Maybe.)


I guess we might have to make a mdf box then as the outlet is in the subfloor with the floor being concrete, and the wire is stapled to the 2x4s already. I don't know how we could put the clay pad on the backside with out removing either the wires or the staples after the OSB is removed. The only other solution I can think of is to pull the outlet box, seal the hole with the wires coming out and have the outlet above the floor enclosed in a table between the chairs..


----------



## BIGmouthinDC

remove the staples, what happens behind the subfoor stays behind the subfloor. Secure the romex to the bottom of the subloor.


----------



## panino


I may have missed this in my search of this long thread, but does anyone have an actual STC value for fluffy insulation, say R19?  I'm trying to figure out how much it will change my ceiling (OSB/GG/drywall) if I leave as is with air cavity above or add R19.  My initial understanding was that the fluffy stuff didn't really provide more than a few points of STC?


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/360#post_24628113
> 
> 
> remove the staples, what happens behind the subfoor stays behind the subfloor. Secure the romex to the bottom of the subloor.



We were able to lift it up enough to put 2 clay pads on it.


----------



## granroth




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/300_100#post_24649225
> 
> 
> I may have missed this in my search of this long thread, but does anyone have an actual STC value for fluffy insulation, say R19?  I'm trying to figure out how much it will change my ceiling (OSB/GG/drywall) if I leave as is with air cavity above or add R19.  My initial understanding was that the fluffy stuff didn't really provide more than a few points of STC?



The amount of sound reduction you'll get by adding insulation varies quite a bit, based on a lot of other factors. I've never seen insulation tested on its own, since it's performance is so highly coupled with the overall wall assembly. That means that to really determine how it'll work in your case, you need to find a rated wall assembly that matches yours.


The most accurate and highly cited research on the topic of sound reduction in wall assembly was done by the NRC-CNRC. This is their most cited doc: Gypsum Board Walls: Transmission Loss Data . It contains HUNDREDS of wall assemblies, all throughly documented and tested.


It's notable that with so many hundreds of variations of walls, they have at most 10 examples of walls with no insulation at all. That's because adding insulation to a wall is just an obvious step and so it makes little difference to test a wall without it. That is, almost nobody creating a wall with soundproofing in mind will do so without insulation -- it's one of the most base elements.


Still, here's an example of two staggered stud walls that are otherwise identical, save that one has no insulation (TL-93-254, page 314) and the other has R-19 (TL-93-249, page 274). The former wall has a rating of STC 41, while the latter has a rating of STC 50. That's a huge increase!


There is very little difference between R-13 and R-19 insulation in most applications. . Jump to page 278 and 279 with tests TL-93-255 and TL-93-256. The former uses 190mm fiberglass (R-19) while the latter uses 90mm (R-13), both in an otherwise identical staggered stud setup. There was no difference in STC rating between the two thicknesses of insulation (STC 48).


As a very slight digression, you may have noticed that TL-93-255 and TL-93-274 both use R-19 in a staggered stud wall, yet one has STC 48 and the other STC 50. What gives? This is one of the reasons that the NRC does so many tests -- the dominate difference in those tests is the density of the drywall. Note I didn't say thickness or type of drywall -- they both use single layers of 5/8" Type X drywall. But even then, one of the sheets (maybe different brands?) was more dense than the other, and that difference in density was enough to cause an increase (or drop) of 2.


One final note -- that increase of 9 with the addition of insulation was highly specific to that case. Other tests I've seen comparing "plain" 2x4 stud walls (nothing special) to the same assembly with R-13 insulation showed an increase between 4 and 5. YMMV.


No matter what, it'll always make sense to use some insulation.


----------



## panino

No matter what, it'll always make sense to use some insulation.[/quote]



That is what I assumed, but it is nice to have some sense of how much improvement I'm getting. Thanks for your guidance and thanks for the link! That is a wealth of information. Too bad they didn't also test combinations using OSB as well as GG.


----------



## granroth

I've seen a few builds with wall-in-wall construction that use IB-3 clips (or similar) to tie the walls together, but do so in a decoupled fashion. I just finished framing my own inner walls and I get the need for some support, since those walls move a lot more than you'd think. Using IB-3 clips would go a long way to keeping them plumb and square, but without compromising the decoupling.


BUT... are they actually necessary in the long run? That is, the IB-3 clips could certainly come in handy during construction, but once the multiple layers of drywall (or OSB) are installed, wouldn't that create enough rigidity to negate the need for any other supports?


----------



## jjslegacy




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/360#post_24660422
> 
> 
> I've seen a few builds with wall-in-wall construction that use IB-3 clips (or similar) to tie the walls together, but do so in a decoupled fashion. I just finished framing my own inner walls and I get the need for some support, since those walls move a lot more than you'd think. Using IB-3 clips would go a long way to keeping them plumb and square, but without compromising the decoupling.
> 
> 
> BUT... are they actually necessary in the long run? That is, the IB-3 clips could certainly come in handy during construction, but once the multiple layers of drywall (or OSB) are installed, wouldn't that create enough rigidity to negate the need for any other supports?



I personally wouldn't rely on just drywall holding my walls straight and supported. Lots of factors there. 2 layers of drywall is quite strong but what's going to keep them straight while you do the install? What if a piece on the ceiling is too long and pushes the wall out a bit?



edit - didn't realize this was room with in a room - never mind my babbling


----------



## kmhvball




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/360#post_24660422
> 
> 
> I've seen a few builds with wall-in-wall construction that use IB-3 clips (or similar) to tie the walls together, but do so in a decoupled fashion. I just finished framing my own inner walls and I get the need for some support, since those walls move a lot more than you'd think. Using IB-3 clips would go a long way to keeping them plumb and square, but without compromising the decoupling.
> 
> 
> BUT... are they actually necessary in the long run? That is, the IB-3 clips could certainly come in handy during construction, but once the multiple layers of drywall (or OSB) are installed, wouldn't that create enough rigidity to negate the need for any other supports?


I think you need something to attach the vertical walls to the 'horizontal' ceiling structure for support.   Maybe if you had a wall which the two adjoining edge walls 'pinned' against the main structure that would work.

 

I have seen two types of clips, one, the IB-3, which can be used to attach the vertical wall to the ceiling/sub-floor, or in the case of a basement, to the 'concrete' wall.   I have also seen different clips which 'connect' two parallel, double wall's together.  In my application, where I have the 2, 2x4 parallel walls- I am using IB-3s on the top of each of those to support the wall vertically.    I debated IB-3s on one wall and then attaching the two walls together with the other type of clip, but opted not to go that route simply to have fewer 'types' of clips to deal with.


----------



## KNKKNK




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/360#post_24660422
> 
> 
> I've seen a few builds with wall-in-wall construction that use IB-3 clips (or similar) to tie the walls together, but do so in a decoupled fashion. I just finished framing my own inner walls and I get the need for some support, since those walls move a lot more than you'd think. Using IB-3 clips would go a long way to keeping them plumb and square, but without compromising the decoupling.
> 
> 
> BUT... are they actually necessary in the long run? That is, the IB-3 clips could certainly come in handy during construction, but once the multiple layers of drywall (or OSB) are installed, wouldn't that create enough rigidity to negate the need for any other supports?



With a true Room within a Room , The clips might "help" during construction but definitely are not needed long term.. . particularly if your first layer is OSB.... use a long 2x4 that can span from your top to bottom plate at an angle across several studs to hold your wall square while your get your first couple sheets in the corners nailed up..


The sheeting will keep your walls from racking, and the joists will keep them from spreading.... think of your house.. or the shed in your back yard, that see's 100 mph winds... structurally what your building is no different! You may want a few Simpson H 2.5's here or there to "assist" keeping your walls plumb when your putting the joists on (since you hate toe nailing







) .. but again with no lateral forces or uplift considerations even that's not needed.


----------



## granroth




> Quote:
> Originally Posted by *KNKKNK*  /t/1509173/soundproofing-master-thread/300_100#post_24663016
> 
> 
> The sheeting will keep your walls from racking, and the joists will keep them from spreading.... think of your house.. or the shed in your back yard, that see's 100 mph winds... structurally what your building is no different! You may want a few Simpson H 2.5's here or there to "assist" keeping your walls plumb when your putting the joists on (since you hate toe nailing
> 
> 
> 
> 
> 
> 
> 
> ) .. but again with no lateral forces or uplift considerations even that's not needed.



Ah... I hadn't thought of the "whole house" angle. That's quite true, and exactly what I was looking for. My thought process was more along the lines of all of the bookcases I've built. They all exhibited both rack and shear when they only had a bare skeleton, but enclose all but one side of the "box" and those are rock solid.


And yeah, I'm definitely going to use strongties where it makes my job easier


----------



## panino


The entrance to my theater will be french doors.  I know what you are all going to say.. "get rid of the french doors and go with a single door".  Already thought about it and I'm intent on making the french doors work.  The question I have is, does anyone have a recommendation on a set of door seals and automatic door bottoms that I should go with?  I've looked through Zero International's site and there are so many to choose from.

 

I'm planning on sealing the point where both doors meet with an astragal and seal, adhesive seal around the frames, and automatic door bottoms on both doors.  The doors are only 1 3/8" thick, but are solid core.  I'll probably completely mortise the door bottoms into the doors, so I'll need a set that is rather thin.  I need recommendations on which seals and door bottoms to use for this.


----------



## BIGmouthinDC

came across this PDF yesterday, Page 12 has their recommended setup for double doors.


Be aware that the components will probably cost more than the door.

http://www.zerointernational.com/images/products/SoundControlBrochure.pdf


----------



## panino




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/360#post_24665143
> 
> 
> came across this PDF yesterday, Page 12 has their recommended setup for double doors.
> 
> 
> Be aware that the components will probably cost more than the door.
> 
> http://www.zerointernational.com/images/products/SoundControlBrochure.pdf


 

That's great info.  Thanks Big!  Based on the recommended setup though you are definitely right... the components will cost more than the door, and those are some serious components.

 

If I'm looking at that extravagant of a setup I think I'll probably forgo that level of soundproofing.  I want to try and maintain the "french door look", not make it look like the entrance to a biohazard facility.  







   I'll probably go with adhesive or kerf seals on the jamb, maybe a door sill/sweep instead of auto door bottoms, and an astragal with seal.  I'll get some minimal isolation, but it certainly won't be close to complete.  I know these doors will definitely be the weakest link in the entire room, but since my theater is in the basement I'm not horribly concerned with noise leakage through the doors even with some flanking.  I'm not expecting to have much noise in the adjoining rooms in the basement either that would interfere with my theater experience.

 

Has anyone done a theater with french doors that can tell me their thoughts?


----------



## VolkerH.

What do you folks do with the nails sticking through the sub floor ? If I wanna go with GG + DW between the joists I assume I have to clip them off ?!


----------



## ellisr63




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/390#post_24667769
> 
> 
> What do you folks do with the nails sticking through the sub floor ? If I wanna go with GG + DW between the joists I assume I have to clip them off ?!


Cut them off or hammer/bend them flat.


----------



## BIGmouthinDC

I tried cutting once, now I hammer.


----------



## BIGmouthinDC

Tomorrow the press release hits the wire. but I want to give everyone a heads up. I have developed an insulation with Green Goo dampening agent coating on each fiber. The result is sound absorption at a level previously unheard of for an insulation.


----------



## granroth

Interesting! Are you willing to go into more detail before the press release?


----------



## Reefdvr27




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/390#post_24667874
> 
> 
> Tomorrow the press release hits the wire. but I want to give everyone a heads up. I have developed an insulation with Green Goo dampening agent coating on each fiber. The result is sound absorption at a level previously unheard of for an insulation.


Wow, look forward to hearing about this!


----------



## BIGmouthinDC

More here:

http://www.avsforum.com/t/1017460/roxul-sound-proofing-opinion/80_40#post_24667165


----------



## panino




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/390#post_24667874
> 
> 
> Tomorrow the press release hits the wire. but I want to give everyone a heads up. I have developed an insulation with Green Goo dampening agent coating on each fiber. The result is sound absorption at a level previously unheard of for an insulation.


 

Hehe... awesome.  I love the green insulation!  It is almost glowing.


----------



## panino


Similarly, I've just found a way to bind green glue with sand.  No more filling stages with boring quikrete play sand.  I'm thinking of calling it Sandgreena, not to be confused with the drink with a similar name.


----------



## btinindy




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/390#post_24667874
> 
> 
> Tomorrow the press release hits the wire. but I want to give everyone a heads up. I have developed an insulation with Green Goo dampening agent coating on each fiber. The result is sound absorption at a level previously unheard of for an insulation.



Very interesting. In my head I am envisioning batts of this in a tightly compressed plastic wrapping and when you cut them open it would look like the Hulk transforming. Maybe some naming potential in there somewhere.


----------



## BasementBob




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/390#post_24667874
> 
> 
> Green Goo


Nice to see something out of Area 69 put to good use.


----------



## granroth

I'm trying to think of how this could work, as an actual product. This is just me thinking out loud.


Fiberglass insulation works for sound proofing largely in the same way it works for heat. The fiberglass has millions of tiny "bubbles" of air trapped in the fibers. In the case of heat, it needs to transfer to each bubble individually and gets massively slowed down in the process. This constant shifting also loses a lot of energy into the fibers in the process. Sound works somewhat similarly in that it can't easily travel over the fibers so it needs to travel from bubble to bubble. Just like in the heat case, a lot of the energy is simply lost in those transfers. It has the dual effect of losing energy (absorption) and slowing down the result (not sure what that'd be called).


Now let's say we coat all the fibers with a damping material. It would be something heavy, but perpetually flexible. This would likely cover a large amount of the bubbles and essentially make the fiberglass useless as insulation (unless the damping material had its own heat insulating properties). Would the additional damping ability replace or exceed the inherent absorption ability in the fiberglass that we're losing? I'd think that this new product wouldn't really compete in the same space as fiberglass and rock-wool at the like but would instead compete with products like MLV.


Perhaps this wouldn't be cost effective. In fact, one might say that the fiberglass would be a bit superfluous and why not just apply that damping compound directly to another substrate. Like say drywall. And then just sandwich that damping agent between the sheets of drywall.


----------



## panino




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/390#post_24672543
> 
> 
> 
> 
> Perhaps this wouldn't be cost effective. In fact, one might say that the fiberglass would be a bit superfluous and why not just apply that damping compound directly to another substrate. Like say drywall. And then just sandwich that damping agent between the sheets of drywall.


 

Or you could just fill all of your wall cavities with Sandgreena (patent pending).


----------



## ellisr63




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/390#post_24673397
> 
> 
> Or you could just fill all of your wall cavities with Sandgreena (patent pending).


Filling the wall cavities with sand I think would be the best, but I don't think it would work 2 well with wood framing and drywall. If you had cinder block walls and was building a new inner room with cinder blocks then I say the sand would be the way to go.


----------



## ellisr63

Just got back from my local Electrical Supply house, and wanted to pass on my find... I picked up Acoustical Putty Pads for 99 cents each! I was paying around $5 each for the fire rated ones, and this is a nice savings.







They are grey and appear to be the same size and thickness as the Hilti fire rated ones... Just no odor.


----------



## Chuck Miller

That is a great find. Can you share the brand and at what store you bought them? I wouldn't be lucky enough for it to be a nationwide big box store, I suppose.


Thanks,


Chuck


----------



## ellisr63




> Quote:
> Originally Posted by *Chuck Miller*  /t/1509173/soundproofing-master-thread/390#post_24676993
> 
> 
> That is a great find. Can you share the brand and at what store you bought them? I wouldn't be lucky enough for it to be a nationwide big box store, I suppose.
> 
> 
> Thanks,
> 
> 
> Chuck


I don't know the brand as he went back in the warehouse and brought back the 4 pieces I needed.... They look just like the 3M ones. Here is the place I got them from... http://www.bayshoresupply.com/ 

I would think you could order them from them.


----------



## Chuck Miller

Thanks for the info. I'll see if I can get in touch with them.


Chuck


----------



## ellisr63

I just looked at the invoice... Dottie 68 sound barrier pad $.912 each. Even less than I thought!










I just looked them up and they are not clay... They are a formulation of rubber. I think they will seal but I don't think you get the mass of the clay. Here is some info on them. http://www.cesco.com/b2c/product/478609


----------



## panino




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/390#post_24677158
> 
> 
> I just looked at the invoice... Dottie 68 sound barrier pad $.912 each. Even less than I thought!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I just looked them up and they are not clay... They are a formulation of rubber. I think they will seal but I don't think you get the mass of the clay. Here is some info on them. http://www.cesco.com/b2c/product/478609


 

Looks like you can get them for a similar, but slightly higher price off Amazon (if you're willing to buy 100 of em)!

http://www.amazon.com/L-H-Dottie-68-Insulating-100-Pack/dp/B001UKH5FM


----------



## Conspiracy*




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/390#post_24667769
> 
> 
> What do you folks do with the nails sticking through the sub floor ? If I wanna go with GG + DW between the joists I assume I have to clip them off ?!



Question of the day. I would assume that hammering wouldn't give the most flush results, but if BIG says he hammers, then they'll get hammered.


----------



## brwsaw




> Quote:
> Originally Posted by *Conspiracy**  /t/1509173/soundproofing-master-thread/390#post_24685474
> 
> 
> Question of the day. I would assume that hammering wouldn't give the most flush results, but if BIG says he hammers, then they'll get hammered.



Pretty sure he meant hammer them to break them off.


----------



## BIGmouthinDC

Nope bend them over. you can try to cut them, but in my experience you will revert to the hammer.


----------



## ellisr63




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/390#post_24677550
> 
> 
> Looks like you can get them for a similar, but slightly higher price off Amazon (if you're willing to buy 100 of em)!
> http://www.amazon.com/L-H-Dottie-68-Insulating-100-Pack/dp/B001UKH5FM


We tried them out and they worked fine... The only downside is you don't get the mass of the fire rated clay ones.


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/390#post_24685920
> 
> 
> Nope bend them over. you can try to cut them, but in my experience you will revert to the hammer.


A lot of them when you bend them over will break right off anyway too.


----------



## jjslegacy

I used a dremel with a metal cutting disc - worked well and quickly but I only had two bays to do not an entire ceiling


----------



## Conspiracy*




> Quote:
> Originally Posted by *jjslegacy*  /t/1509173/soundproofing-master-thread/390#post_24686680
> 
> 
> I used a dremel with a metal cutting disc - worked well and quickly but I only had two bays to do not an entire ceiling



ya I've got approx 1000 sq feet to hammer flat. Who knows what they were doing above, going crazy with the heavy duty stapler thats what.


----------



## VolkerH.

So I continued reading through Sound proofing and deadening threads and I think I just missed the apex because I think I just forgot what I need to do.


My HT room is in the basement, under the dining room. The DR has wood flooring nailed to the subfloor (hence my nail removal question above). I have free sight to the subfloor from below. A few ducts run between the joists, heat and returns as well as a few water pipes and sewer pipes in the back corner.

The back of my room is open to the stairway leading upstairs and also in the back is a screen door leading in my office space.


I want to achieve 2 things (in priority)


A. I would like to have the feeling that I walk into a 'silent' room, something that makes me feel the outside noises are subdued. Like when entering a movie theater from a tile hallway... Heavy carpet, heavy curtain, sound seems to move slower...


B. I want to reduce the noise escaping from the room, but that has a lower priority.


So I read about decoupling, insulation, double drywall, green glue, sound strips etc.


Will that help me with achieving A. ?


----------



## Conspiracy*




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/390#post_24693819
> 
> 
> So I continued reading through Sound proofing and deadening threads and I think I just missed the apex because I think I just forgot what I need to do.
> 
> 
> My HT room is in the basement, under the dining room. The DR has wood flooring nailed to the subfloor (hence my nail removal question above). I have free sight to the subfloor from below. A few ducts run between the joists, heat and returns as well as a few water pipes and sewer pipes in the back corner.
> 
> The back of my room is open to the stairway leading upstairs and also in the back is a screen door leading in my office space.
> 
> 
> I want to achieve 2 things (in priority)
> 
> 
> A. I would like to have the feeling that I walk into a 'silent' room, something that makes me feel the outside noises are subdued. Like when entering a movie theater from a tile hallway... Heavy carpet, heavy curtain, sound seems to move slower...
> 
> 
> B. I want to reduce the noise escaping from the room, but that has a lower priority.
> 
> 
> So I read about decoupling, insulation, double drywall, green glue, sound strips etc.
> 
> 
> Will that help me with achieving A. ?



Yes. To achieve the "silent" room effect you're going to want to maximize your Decoupling (Channel and clips), Mass (double drywall), Dampening (Green Glue), and Absorption (Insulation).


----------



## blazar

I like the idea of a cinderblock room for isolation... But the ceiling gets pricey...


----------



## granroth




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/400_100#post_24693819
> 
> 
> So I continued reading through Sound proofing and deadening threads and I think I just missed the apex because I think I just forgot what I need to do.
> 
> 
> My HT room is in the basement, under the dining room. The DR has wood flooring nailed to the subfloor (hence my nail removal question above). I have free sight to the subfloor from below. A few ducts run between the joists, heat and returns as well as a few water pipes and sewer pipes in the back corner.
> 
> The back of my room is open to the stairway leading upstairs and also in the back is a screen door leading in my office space.
> 
> 
> I want to achieve 2 things (in priority)
> 
> 
> A. I would like to have the feeling that I walk into a 'silent' room, something that makes me feel the outside noises are subdued. Like when entering a movie theater from a tile hallway... Heavy carpet, heavy curtain, sound seems to move slower...
> 
> 
> B. I want to reduce the noise escaping from the room, but that has a lower priority.
> 
> 
> So I read about decoupling, insulation, double drywall, green glue, sound strips etc.
> 
> 
> Will that help me with achieving A. ?



Yes and no. A lot of the "feeling" that you are referring to actually has to do with acoustics more than sound proofing. That is, when you are in an acoustically treated room, the echos and flutters and the rest are all taken care of and all you hear is the intended sound. Being in an acoustically treated room even makes having conversations a joy.


If you _only_ acoustically treat your room, though, then you are still going to have to fight with the sound floor. That is, an exclusively acoustically treated room will do almost nothing to prevent noise from escaping OR (critically) from entering the room.


Soundproofing a room alone will not give you that feeling of subdued sound, like you describe. In fact, it partially will do the opposite. So many of the sounds that might have normally escaped the room will be reflected back, making the noise slightly more chaotic and "bright". What it is doing, though, is reducing the amount of sound coming into the room so that the only noise that is heard, is noise that you are generating (one way or another).


That's why the combination of soundproofing and acoustic control is ideal. Each brings a critical part to the puzzle and each complements the other. If you soundproof _and_ acoustically treat your room, then you get both the drastic reduction of the sound floor and removal of errant sounds as well as the "smooth" feeling you get from the sound that is in the room.


----------



## cw5billwade




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/390#post_24693819
> 
> 
> So I continued reading through Sound proofing and deadening threads and I think I just missed the apex because I think I just forgot what I need to do.
> 
> 
> My HT room is in the basement, under the dining room. The DR has wood flooring nailed to the subfloor (hence my nail removal question above). I have free sight to the subfloor from below. A few ducts run between the joists, heat and returns as well as a few water pipes and sewer pipes in the back corner.
> 
> The back of my room is open to the stairway leading upstairs and also in the back is a screen door leading in my office space.
> 
> 
> I want to achieve 2 things (in priority)
> 
> 
> A. I would like to have the feeling that I walk into a 'silent' room, something that makes me feel the outside noises are subdued. Like when entering a movie theater from a tile hallway... Heavy carpet, heavy curtain, sound seems to move slower...
> 
> 
> B. I want to reduce the noise escaping from the room, but that has a lower priority.
> 
> 
> So I read about decoupling, insulation, double drywall, green glue, sound strips etc.
> 
> 
> Will that help me with achieving A. ?


Except for the foot fall traffic on the hard wood floor that is where adding the GG/DW/GG/DW to the bottom of sub floor comes in. If no one is ever in the dining room than that may not be a priority. Also you forgot the R19 in the joist above and R13 in the walls. Once we had the insulation in my room done I was surprised at the difference it made prior to the first piece of Dry Wall going up.


----------



## artur9

My laundry room is above my home theatre. Bad choice on the part of the previous owners, if you ask me.


That leads to all kinds of problems. Washer/dryer noise through ducting, etc.


But what concerns me most is something highlighted after "an incident" in which the laundry room got flooded. The water came through the ductwork onto the basement ceiling.


My question: Any way to combine waterproofing and soundproofing? Before this, I was thinking of using QuietRock on the basement "ceiling" (first floor subflooring) because of the convenience. But now I'm concerned about what would happen in case the laundry room gets flooded again. I see that as a "when" type of event, not an if.


In a sense, wondering about using green board instead of regular drywall. Or something like that.


----------



## BIGmouthinDC

You are thinking about this problem backwards. I'd first start this project in the laundry room itself, it is probably small and a manageable project. you could add damping and mass to the floor above. Then you want to think about making the floor itself watertight and add a drain to catch the overflow and direct it down the drain pipe hidden out of sight. They sell pans you can place under the washer or you can construct the floor like a shower stall.


----------



## artur9




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/420#post_24697141
> 
> 
> You are thinking about this problem backwards. I'd first start this project in the laundry room itself, it is probably small and a manageable project. you could add damping and mass to the floor above.



Sorry, not following you here. Add mass and damping to the laundry room floor? Wouldn't that be equivalent to adding mass and damping to the basement ceiling?


> Quote:
> Originally Posted by *BIGmouthinDC*
> 
> Then you want to think about making the floor itself watertight and add a drain to catch the overflow and direct it down the drain pipe hidden out of sight.They sell pans you can place under the washer or you can construct the floor like a shower stall.



It wasn't the washer that caused the flooding but rather the utility sink. So I think redoing the flooring to drain somewhere more appropriate is the first step, with added soundproofing?


----------



## panino




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/420#post_24696645
> 
> 
> 
> Except for the foot fall traffic on the hard wood floor that is where adding the GG/DW/GG/DW to the bottom of sub floor comes in. If no one is ever in the dining room than that may not be a priority. Also you forgot the R19 in the joist above and R13 in the walls. Once we had the insulation in my room done I was surprised at the difference it made prior to the first piece of Dry Wall going up.


 

I second that.  In fact, just finished putting up R19 in my ceiling joists today.  No GG/DW due to obstruction limitations and I haven't even done the insulation on the walls yet.  But as cw5billwade said, I can already hear a small but noticeable difference in noise from the room above (which is hardwood flooring).  Can't wait to see how it will sound once I get the ceiling up and finished.


----------



## kmhvball


I am looking at alternatives to traditional Recessed lights & large penetrations/ backer boxes.  Below are images of how I am thinking of using the 'new'ish" Halo Surface mount lights to reduce sound transmission.  These are recessed lights that fit in a traditional look, they are 3,000 K color temperature, and have a CRI (Color Rendering Index) of 90 (or an option of 80).  These are either 4" or 6".

 

This first photo, is the 3 layers of MDF (or could be OSB/ cement board, not sure which is best), which will be behind the two layers of 5/8" drywall (i.e., between room envelope & ceiling above).  The two 'rear'/top layers have only a small hole in them for the electric wire penetration.   The 3rd board is 3/4" in my case because the electric box I have is 2" deep. 



 

This next picture is a profile view of these three pieces pressed together, with Green Glue (some of my 6, 5 gallon buckets from the soundproofingcompany.com). 

 



 

 

This next picture shows them 'attached' to the drywall, I am imagining screwing them through the drywall before putting the drywall up, and as the drywall is being lifted into place, running the wire down through the small holes. 



 

Here are pictures of the box I plan to use, and a few pictures of the light itself: 

 



 

 

These next two pictures are 'theoretically' the electric box installed in 2 layers of 5/8" drywall (of course, with GG).   I say 'theoretically', because, all I have on hand is a small 1/2" drywall piece, so, I used a 3/4" MDF piece... the combined width of these being 10/8ths = 2 layers of 5/8" drywall.  So, bear with the lack of correct materials, but the measurements are the same.



 



 

 

 

 

This next picture shows what the light would look like as it were being wired & ready to be installed, this shows how 'shallow' the light is. 

 



 

 

 

 

The final picture is the light after installation, when mounted flush with the ceiling.

 



 

 

 

This whole sequence obviously is more labor & material intensive than simply using Putty Pads.   Of course, the 'labor' isn't horrible, I cut my boards very roughly/quickly 8" x 8", unlike a backer box which needs to be somewhat 'square', these are pancaked together so precision isn't a huge deal.  A hole saw then used to cut out the hole to mount the box in.

 

I would also use acoustic caulk in the holes & around the box to provide that extra bit of sound sealing. 

 

Do you think this would be much better than Putty Pads, or yield a very similar result?  Obviously, not going to waste my time if there isn't much benefit.

 

Also, the 4" and 6" lights are the same mounting options.   I have seen many, many, of the theaters using 4", I have always wondered if that was simply a better aesthetic look choice, or if it was to 'minimize' the size of the penetration in the ceiling.    I am somewhat leaning towards 3, 4" lights at my screen, and then using 6" lights (ever so slightly brighter capability) over the seating areas.   These of course will all be dimmable/zoned (likely Grafik Eye QS).


----------



## nirvy111

I haven't read through this thread because I couldn't be bothered but I have a straight up question anyway if anyone cares to answer it. Will a room within a room design(done properly of course) in a double garage eliminate bass leakage from a single 12-15" subwoofer(something like the HSU VTF15 for example) played at high-ish volumes?


I've have seen a couple of youtube videos of drum kit musicians using the room within a room design inside garages and I wasn't entirely convinced it was completely effective, surprisingly there was still a good amount of sound leakage (around 50db measured standing outside on the drive way), mind you drum kits are extremely loud so it's kind of hard to gauge how a home theatre subwoofer would fair under the same conditions, which is why I ask the question..


I would consider building a room with a room if it meant I could install a large subwoofer and not have the neighbours hear it, as it stands I cannot do this, my theatre room is only acoustically treated well enough for the mids and highs and some minor bass sound from my bookshelf speakers. A large subwoofer in my room without further heavy acoustic treatment would be a no go unfortunately.


I guess another question would be, how much bass leakage can you get away with before your neighbours start to hear it?(they're ~ 30 feet away)


----------



## cw5billwade




> Quote:
> Originally Posted by *kmhvball*  /t/1509173/soundproofing-master-thread/420#post_24699280
> 
> 
> I am looking at alternatives to traditional Recessed lights & large penetrations/ backer boxes.  Below are images of how I am thinking of using the 'new'ish" Halo Surface mount lights to reduce sound transmission.  These are recessed lights that fit in a traditional look, they are 3,000 K color temperature, and have a CRI (Color Rendering Index) of 90 (or an option of 80).  These are either 4" or 6".
> 
> 
> This first photo, is the 3 layers of MDF (or could be OSB/ cement board, not sure which is best), which will be behind the two layers of 5/8" drywall (i.e., between room envelope & ceiling above).  The two 'rear'/top layers have only a small hole in them for the electric wire penetration.   The 3rd board is 3/4" in my case because the electric box I have is 2" deep.
> 
> 
> 
> 
> This next picture is a profile view of these three pieces pressed together, with Green Glue (some of my 6, 5 gallon buckets from the soundproofingcompany.com).
> 
> 
> 
> 
> 
> 
> This next picture shows them 'attached' to the drywall, I am imagining screwing them through the drywall before putting the drywall up, and as the drywall is being lifted into place, running the wire down through the small holes.
> 
> 
> 
> 
> Here are pictures of the box I plan to use, and a few pictures of the light itself:
> 
> 
> 
> 
> 
> 
> 
> These next two pictures are 'theoretically' the electric box installed in 2 layers of 5/8" drywall (of course, with GG).   I say 'theoretically', because, all I have on hand is a small 1/2" drywall piece, so, I used a 3/4" MDF piece... the combined width of these being 10/8ths = 2 layers of 5/8" drywall.  So, bear with the lack of correct materials, but the measurements are the same.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This next picture shows what the light would look like as it were being wired & ready to be installed, this shows how 'shallow' the light is.
> 
> 
> 
> 
> 
> 
> 
> 
> The final picture is the light after installation, when mounted flush with the ceiling.
> 
> 
> 
> 
> 
> 
> 
> This whole sequence obviously is more labor & material intensive than simply using Putty Pads.   Of course, the 'labor' isn't horrible, I cut my boards very roughly/quickly 8" x 8", unlike a backer box which needs to be somewhat 'square', these are pancaked together so precision isn't a huge deal.  A hole saw then used to cut out the hole to mount the box in.
> 
> 
> I would also use acoustic caulk in the holes & around the box to provide that extra bit of sound sealing.
> 
> 
> Do you think this would be much better than Putty Pads, or yield a very similar result?  Obviously, not going to waste my time if there isn't much benefit.
> 
> 
> Also, the 4" and 6" lights are the same mounting options.   I have seen many, many, of the theaters using 4", I have always wondered if that was simply a better aesthetic look choice, or if it was to 'minimize' the size of the penetration in the ceiling.    I am somewhat leaning towards 3, 4" lights at my screen, and then using 6" lights (ever so slightly brighter capability) over the seating areas.   These of course will all be dimmable/zoned (likely Grafik Eye QS).


I think it is going to work just insure that you use acoustic caulk at the wire penetration and a nice amount between the box and MDF. Great idea really. I used similar lights in my coffers. This may be the new standard.


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *nirvy111*  /t/1509173/soundproofing-master-thread/400_40#post_24699826
> 
> 
> I haven't read through this thread because I couldn't be bothered but I have a straight up question anyway if anyone cares to answer it. Will a room within a room design(done properly of course) in a double garage eliminate bass leakage from a single 12-15" subwoofer(something like the HSU VTF15 for example) played at high-ish volumes?
> 
> 
> I've have seen a couple of youtube videos of drum kit musicians using the room within a room design inside garages and I wasn't entirely convinced it was completely effective, surprisingly there was still a good amount of sound leakage (around 50db measured standing outside on the drive way), mind you drum kits are extremely loud so it's kind of hard to gauge how a home theatre subwoofer would fair under the same conditions, which is why I ask the question..
> 
> 
> I would consider building a room with a room if it meant I could install a large subwoofer and not have the neighbours hear it, as it stands I cannot do this, my theatre room is only acoustically treated well enough for the mids and highs and some minor bass sound from my bookshelf speakers. A large subwoofer in my room without further heavy acoustic treatment would be a no go unfortunately.
> 
> 
> I guess another question would be, how much bass leakage can you get away with before your neighbours start to hear it?(they're ~ 30 feet away)



A single HSU sub is a walk in the park for some of the theaters documented here. If you build following *ALL* four principles of Mass, Isolation, Dampening and Absorption to create a bunker in your house, your neighbors will ask when are you going to finish your theater long after you've already ruined your hearing.


----------



## cw5billwade




> Quote:
> Originally Posted by *nirvy111*  /t/1509173/soundproofing-master-thread/420#post_24699826
> 
> 
> I haven't read through this thread because I couldn't be bothered but I have a straight up question anyway if anyone cares to answer it. Will a room within a room design(done properly of course) in a double garage eliminate bass leakage from a single 12-15" subwoofer(something like the HSU VTF15 for example) played at high-ish volumes?
> 
> 
> I've have seen a couple of youtube videos of drum kit musicians using the room within a room design inside garages and I wasn't entirely convinced it was completely effective, surprisingly there was still a good amount of sound leakage (around 50db measured standing outside on the drive way), mind you drum kits are extremely loud so it's kind of hard to gauge how a home theatre subwoofer would fair under the same conditions, which is why I ask the question..
> 
> 
> I would consider building a room with a room if it meant I could install a large subwoofer and not have the neighbours hear it, as it stands I cannot do this, my theatre room is only acoustically treated well enough for the mids and highs and some minor bass sound from my bookshelf speakers. A large subwoofer in my room without further heavy acoustic treatment would be a no go unfortunately.
> 
> 
> I guess another question would be, how much bass leakage can you get away with before your neighbours start to hear it?(they're ~ 30 feet away)


If you use all the sound proofing principals like I did and also use some acoustic principals like base traps the LF will get through a little bit but will never make it to the neighbors. My theater is over the Garage and anywhere in the house you cannot here LF except the master bedroom which is at the bottom of the steps so a straight line from the theater door. You really cannot hear it just feel it. And that was playing the Man of Steel which is a nonstop base fest at reference. I have two 12” subs with 500 W plate Amps Running a Denon X-4000. At this time I had yet even put the door knob on or the weather stripping around the door jamb. I still need to install an automatic door seal on the bottom. The door is the biggest offender in my theater but even standing in the Billiard room which is right outside the theater door now that I have the weather stripping and a door knob with it closed you can hear the base but more like distant thunder. (and I run my subs hot +6DB from where the Denon sets them.


Just doing room in room (decoupling) without doing the other 3 sound proofing tenants I do not think it will work as well.


----------



## nirvy111

Thanks for the replies. I'm still wondering why the decoupled garage studio room I watched on youtube couldn't sufficiently deaden a drum kit. Either the room wasn't done right or drum kits are just too freaken loud. But from what I could tell the room was done to spec and I know the guy spent quite a bit of money on it. That's not to say it didn't make a big difference, it did, but it was still leaking too much sound in my opinion.


----------



## cw5billwade

again the door is the weakest link. Also if the garage already has a finished wall which most do you are getting triple leaf effect which is worse than nothing at all. Not telling you to rip the DW off garage this would not work because the house needs to be sealed from the garage due to CO2 and that is what the DW in the garage is doing. The exterior walls (walls not connected to the house) of the garage you can and should take the DW down so that you can put R13 in that wall and at least avoid the triple leaf there. I would leave the garage door there but I would seal it ( water proof) stud it like a wall and then put R13 in it as well.


----------



## stockmonkey2000




> Quote:
> Originally Posted by *nirvy111*  /t/1509173/soundproofing-master-thread/420#post_24699826
> 
> 
> I haven't read through this thread because I couldn't be bothered but I have a straight up question anyway if anyone cares to answer it. Will a room within a room design(done properly of course) in a double garage eliminate bass leakage from a single 12-15" subwoofer(something like the HSU VTF15 for example) played at high-ish volumes?
> 
> 
> I've have seen a couple of youtube videos of drum kit musicians using the room within a room design inside garages and I wasn't entirely convinced it was completely effective, surprisingly there was still a good amount of sound leakage (around 50db measured standing outside on the drive way), mind you drum kits are extremely loud so it's kind of hard to gauge how a home theatre subwoofer would fair under the same conditions, which is why I ask the question..
> 
> 
> I would consider building a room with a room if it meant I could install a large subwoofer and not have the neighbours hear it, as it stands I cannot do this, my theatre room is only acoustically treated well enough for the mids and highs and some minor bass sound from my bookshelf speakers. A large subwoofer in my room without further heavy acoustic treatment would be a no go unfortunately.
> 
> 
> I guess another question would be, how much bass leakage can you get away with before your neighbours start to hear it?(they're ~ 30 feet away)



50 db is pretty quiet really. So if a drum kit is playing fairly close, that is a decent amount of attenuation. 50 db is about the background noise level of an office environment. 50 db would not bother the neighbors at all.


----------



## cw5billwade

My Samsung dishwasher is one of the quietest on the market and at 49db I do not even have to raise the sound on the TV when it is running. It is in the bar separating the two rooms.


----------



## nirvy111




> Quote:
> Originally Posted by *stockmonkey2000*  /t/1509173/soundproofing-master-thread/420#post_24700641
> 
> 
> 50 db is pretty quiet really. So if a drum kit is playing fairly close, that is a decent amount of attenuation. 50 db is about the background noise level of an office environment. 50 db would not bother the neighbors at all.



So if I was measuring 50 or so db of low bass out on my driveway then my neighbours who are less than 30 feet away wouldn't hear that? And importantly they wouldn't here at 2am when I usually watch movies?


----------



## stockmonkey2000

50db is nothing to worry about, at 30 feet away it would diminish even further especially outside. Pick up a SPL Meter and measure 50dba, - not much to worry about at all. Decibels are logarithmic so 100 db is not twice as loud as 50db. 100 DB is 10,000 times louder than 50db.


----------



## stockmonkey2000




> Quote:
> Originally Posted by *nirvy111*  /t/1509173/soundproofing-master-thread/420#post_24700944
> 
> 
> So if I was measuring 50 or so db of low bass out on my driveway then my neighbours who are less than 30 feet away wouldn't hear that? And importantly they wouldn't here at 2am when I usually watch movies?



One more thing - the lower the bass, the less sensitive the human ear is to it. As you go lower and lower in frequency, you need higher and higher db levels to perceive a sound as loudly.


----------



## nirvy111




> Quote:
> Originally Posted by *stockmonkey2000*  /t/1509173/soundproofing-master-thread/420#post_24700999
> 
> 
> One more thing - the lower the bass, the less sensitive the human ear is to it. As you go lower and lower in frequency, you need higher and higher db levels to perceive a sound as loudly.



O.k thanks.


----------



## chidave

Hi all


I'm not sure if this is the correct place to put this information BUT it should help anyone building a home theater in an old multiunit building ( such as the ones we have in Chicago). It's research by the Canadians in response to reducing the noise BETWEEN floor. I hope I didn't screw this thread up and if I did I apologize, I just wanted to give something back to all the great people ( on AVS in general) who have helped me out over the years.


Below the floor

http://www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/90246.htm 


the surface of the floor

http://publications.gc.ca/collections/Collection/NH18-22-90-247E.pdf 


Chidave


----------



## ellisr63

Question: I was going to do 1 layer OSB and 1 layer of Drywall with Green glue in between, but now i think I am just going to do the 2 layers of drywall with green glue for the ceiling. If I do it this way do both layers of drywall need the screws through the hat channel, or do I just need to be concerned with the first layer hitting the channel? I am anticipating the sheetrock screws being about 12-16" apart on the second layer.


----------



## BIGmouthinDC

one, two, three layers of OSB/Plywood/DW hit the channel on all three layers. Otherwise all the weight of the ceiling is only held up by the few screws on the first layer.


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/420#post_24705630
> 
> 
> one, two, three layers of OSB/Plywood/DW hit the channel on all three layers. Otherwise all the weight of the ceiling is only held up by the few screws on the first layer.


Do you also hit other areas, or only the channels? Do you just use regular sheet rock screws or do you need sheet metal screws for going through the hat channel?


----------



## BIGmouthinDC

You can hit other areas if you need to flatten an edge, secure a backer box or it just gives you a good feeling. I use 2 inch Grabber brand screws designed for light gauge metal on the second layer.


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/420#post_24705772
> 
> 
> You can hit other areas if you need to flatten an edge, secure a backer box or it just gives you a good feeling. I use 2 inch Grabber brand screws designed for light gauge metal on the second layer.


Are these a drywall screw that has a tip that self taps metal, or just a normal drywall screw from Grabber?


----------



## BIGmouthinDC

I can make any drywall screw self tapping, you just push on it and hold the trigger, seriously,


----------



## Chuck Miller




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/420#post_24706375
> 
> 
> I can make any drywall screw self tapping, you just push on it and hold the trigger, seriously,



I second that. I've been framing with steel studs and have used the "self tapping" ones that specifically say they are for steel studs. I've also used other drywall screws that I have laying around. Interesting that I stopped using the self-tappers because they didn't hold as well. They bit into the metal OK, but wouldn't tighten up and recess into the surface of the drywall like regular DW screws do. And the regular screws seemed to bite just as well into the steel studs. I won't be using those self-tappers anymore and I've got a lot more drywall to hang!


Cheers!


Chuck


----------



## BasementBob

[this is an "I don't know what I'm talking about" post. Just a thought]


> Quote:
> Originally Posted by *kmhvball*  /t/1509173/soundproofing-master-thread/420#post_24699280
> 
> 
> Below are images of how I am thinking of using the 'new'ish" Halo Surface mount lights to reduce sound transmission.  These are recessed lights that fit in a traditional look, they are 3,000 K color temperature, and have a CRI (Color Rendering Index) of 90 (or an option of 80).  These are either 4" or 6".



With regular pot lights, even insulation rated lights, I'd be worried about fire with that setup. One of the reasons people make pot light boxes out of drywall and not wood is because drywall is a fire stop, and being made out of gypsum stone the drywall simply won't burn. (Or more accurately, they're made out of MDF with an inner layer of drywall.)


I looked these Halo pot lights up, and I see they're LED lights. So they're probably 6 times cooler.

Some of them, although not this version I think, have a foam seal to prevent air flow, which is good for draft prevention but not great for heat venting.



MDF supports unpiloted ignition at 270 C (518 F), other woods as low as 200C (392 F). I believe heavier woods like Western Larch take longer to catch fire, but I've seen experimental results that go both ways.


One way to find out if the wood will burn at a given temperature is to put it into an oven -- although intentionally starting a fire in your kitchen sounds kinda bad, as opposed to a scientist doing exactly the same with a cheap purchased home stove in an empty all concrete properly vented and sprinklered room.


Another way to go would be to build one potlight system, shove it inside a plastic bag of rockwool insulation on a hot summer day, put it outside and plug it in for 8 hours, then quickly take it apart and see if the wood has burn marks or is too hot to touch.


Perhaps you've already done something similar. You built one, how hot was it? Did the electrical box blue plastic deform?


Make sure they're clean: no dust. Wood dust burns at alarmingly low temperatures, and becomes a piloted ignition source.


----------



## theirishgonzo

ok my queston I have 4 18 in subs powered by 4,000 wats the olny complaint I get when watching a movie is it shakes the entire house I de-coupled the subs bolting them to the concrete floor and I have the best Rockwell sound inslation in the walls is there anything I can do to cutdown on the shakeing that is not expencive this is all in the basement


----------



## granroth




> Quote:
> Originally Posted by *theirishgonzo*  /t/1509173/soundproofing-master-thread/400_100#post_24708868
> 
> 
> ok my queston I have 4 18 in subs powered by 4,000 wats the olny complaint I get when watching a movie is it shakes the entire house I de-coupled the subs bolting them to the concrete floor and I have the best Rockwell sound inslation in the walls is there anything I can do to cutdown on the shakeing that is not expencive this is all in the basement



To start, even the best insulation is going to do only a little when it comes to sound control. Of the four pillars of sound-proofing -- decoupling, mass, damping, absorption -- absorption (the insulation) does the least. Which isn't to say it does nothing... but it's mostly in concert with the other three. But even then, insulation does little for bass.


Also, bolting the subwoofer to anything isn't decoupling -- you can't get much more "coupled" than something bolted to the floor. For most things, it likely wouldn't matter since concrete is quite good at stopping lots of frequencies (it's very massive). It does matter for subwoofers, though, as concrete tends to be very good at transferring the low frequencies. That is, by directly coupling the subwoofers to the floors, you may well have created a more direct conduit for the low frequencies to travel across the floor and up the foundation.


Okay... so what will work? Mass and decoupling. Bass is the hardest part of sound to control, since there is so much energy in those waves and the waves are so large. Still, with enough mass and big enough air gaps, you should be able to substantially reduce the impact of your subwoofers.


Start by decoupling the subwoofer from your floor. Putting it on dedicated isolation pads might work (don't have personal experience with those). You could also create a platform for the subwoofer and fill it with sand.


After that, you'd need to treat your walls and ceilings. Yes, both are needed. If you treat just the ceilings, then the sound will just out-flank your efforts by traveling up the walls. Creating a room-in-a-room is the gold standard, but if you don't have the space, then using clips and channels also works well. That will give you your decoupling. Inner walls works substantially better than clips+channels for bass, though, since you can dedicate more air space to mix -- the lower the frequency, the more air space it needs to effectively work.


Then, add mass and damping. A minimum of two layers of 5/8" Type X drywall with a layer of Green Glue in the middle. Three layers would be even better.


That will go a long way towards containing your subwoofer.


----------



## BasementBob




> Quote:
> Originally Posted by *theirishgonzo*  /t/1509173/soundproofing-master-thread/420#post_24708868
> 
> 
> ok my queston I have 4 18 in subs powered by 4,000 wats the olny complaint I get when watching a movie is it shakes the entire house I de-coupled the subs bolting them to the concrete floor and I have the best Rockwell sound inslation in the walls is there anything I can do to cutdown on the shakeing that is not expencive this is all in the basement



Four things


#1) direct vibration. This is where the subwoofer actually shakes the framing directly. Denis Erskine used to put subwoofers on a front stage. That front stage was sitting on top of Acoustik Mat which decoupled/damped some of the communicated vibration without triple leafing it, and the stage was filled with sand to reduce its vibration by increasing its mass.


I see that there's a 'Serenity Mat' now,
http://www.soundproofingcompany.com/soundproofing-products/soundproofing-floor-underlay/serenity-mat-flooring-underlay/ 

which according to this page
http://www.soundproofingcompany.com/soundproofing-articles/flooring-protecting-a-concrete-slab/ 

"Serenity Mat Underlay installed on a concrete slab will effectively shield against coincidence frequencies of concrete"


#2) but with 4000 watts, a lot of that transmission is still going to be a ton of airborne sound, in addition to direct vibration. This sound energy is literally expanding and contracting the room -- putting pressure on all the walls, floor, ceiling, doors, etc; and that's going through. Floating the front stage isn't going to help with that. For that you need soundproofing. All the usual rules for soundproofing, nothing new there. Since you have an existing room, perhaps there's some part of the room's soundproofing that's dramatically worse/weaker than the others, that can also be fixed (see image below).


#3) turn it down #1: Having a remote 'off switch' for the subwoofers. There are a lot of movies that can be pleasantly watched without 1hz to 50hz content. If you're not making the noise that goes through walls, then little noise goes through the walls.


#4) turn it down #2: high pass filter. Some receivers have a "Night" button or 'high pass filter' ability, which basically turns the subwoofers way down.



[humor]

"the four pillars of sound-proofing"

Putting the 4 subwoofers up on 4 pillars, isn't going to help, unless the pillars are 500' high.


----------



## VolkerH.

Thanks cw5billwade, conspiracy* and granroth for your responses !

Yes I meant to list the R19 as well, already bought a few rolls. Thanks for pointing out the acoustic treatment. I will certainly try out a few things and see when I can stop









.


----------



## ClemsonJeeper

In my build, I am not planning on any soundproofing. However, someone had mentioned that in their untreated dedicated HT, the majority of sound escapes through the AC supplies in the room. He recommended it would be worthwhile to at least building dead vents for the supplies going into the room if nothing else.


Is this the case? Should I look into pulling some of the ceiling down to hang dead vents for the supplies? How much do you think it would actually help out with sound coming out of the theater considering I'm not doing anything else?


----------



## granroth




> Quote:
> Originally Posted by *ClemsonJeeper*  /t/1509173/soundproofing-master-thread/400_100#post_24713498
> 
> 
> In my build, I am not planning on any soundproofing. However, someone had mentioned that in their untreated dedicated HT, the majority of sound escapes through the AC supplies in the room. He recommended it would be worthwhile to at least building dead vents for the supplies going into the room if nothing else.
> 
> 
> Is this the case? Should I look into pulling some of the ceiling down to hang dead vents for the supplies? How much do you think it would actually help out with sound coming out of the theater considering I'm not doing anything else?



Ductwork can, indeed, be a major conduit for sound. It's definitely not the major factor in most cases, though. It would be the limiting factor mostly in cases where you have a duct that directly connects two rooms that are otherwise not connected at all. For instance, I have a "trunk" duct in my house that connects all of the rooms on one side of the house. You can _clearly_ hear what is happening (in very low voices) in the far room from within the nearest room via the ducts -- even though you wouldn't normally hear that noise at all.


But that's a specific case that's unlikely to be similar to ductwork in most households.


If you are just referring to rooms that are adjoining, then your common (untreated) walls will be a FAR bigger source of sound leakage than the ductwork. In fact, the total amount of sound escaping the room in all directions will dwarf the sound in the ducts.


That is, if you were going to pull down the ceiling to hang dead vents, then you would likely see a bigger impact by replacing the ceiling with two layers of 5/8 Type X with Green Glue in between, plus some insulation. Oh, and do the dead vent, too.


----------



## ellisr63

We have 2 6" ducts for our HVAC in our HT room and I was thinking of going with 50' of 8" ducting zig zagged along the ceiling behind out AT screen and then exiting to our return for the house... Will that do, or do I need to do a muffler?


----------



## ClemsonJeeper




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/450#post_24715941
> 
> 
> Ductwork can, indeed, be a major conduit for sound. It's definitely not the major factor in most cases, though. It would be the limiting factor mostly in cases where you have a duct that directly connects two rooms that are otherwise not connected at all. For instance, I have a "trunk" duct in my house that connects all of the rooms on one side of the house. You can _clearly_ hear what is happening (in very low voices) in the far room from within the nearest room via the ducts -- even though you wouldn't normally hear that noise at all.
> 
> 
> But that's a specific case that's unlikely to be similar to ductwork in most households.
> 
> 
> If you are just referring to rooms that are adjoining, then your common (untreated) walls will be a FAR bigger source of sound leakage than the ductwork. In fact, the total amount of sound escaping the room in all directions will dwarf the sound in the ducts.
> 
> 
> That is, if you were going to pull down the ceiling to hang dead vents, then you would likely see a bigger impact by replacing the ceiling with two layers of 5/8 Type X with Green Glue in between, plus some insulation. Oh, and do the dead vent, too.



Thanks for the response. Yeah, sounds like there will be minimal gain by doing just the dead vents. I'm trying to avoid pulling the ceiling completely.


----------



## granroth




> Quote:
> Originally Posted by *ClemsonJeeper*  /t/1509173/soundproofing-master-thread/400_100#post_24716446
> 
> 
> Thanks for the response. Yeah, sounds like there will be minimal gain by doing just the dead vents. I'm trying to avoid pulling the ceiling completely.



You could actually get a notable bang for the buck without pulling the ceiling at all -- just add another layer of 5/8 Type X to your existing layer all around (with Green Glue in between, preferably). Get a good quality solid core door and make sure it seals when it closes. That'll make a notable difference.


But yeah, pulling the ceiling and decoupling and then adding insulation would go a LOT farther. It's all what your goals are and what you're willing to do ;-)


----------



## VolkerH.

So I was able to fire up my system for the first time in 'normal' viewing mode and found that the sound is carried all the way from the basement to the kids rooms on the second floor through the heating vents and the returns. They don't originate in my HT room but they pass through. For now I'm working with R19 and will try to cover the ducts. From there everything is still to be decided. I was thinking another layer of R19 but 90degress off, covered by PolyIso panels. Anything to avoid working with DW


----------



## ellisr63




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/450#post_24723304
> 
> 
> So I was able to fire up my system for the first time in 'normal' viewing mode and found that the sound is carried all the way from the basement to the kids rooms on the second floor through the heating vents and the returns. They don't originate in my HT room but they pass through. For now I'm working with R19 and will try to cover the ducts. From there everything is still to be decided. I was thinking another layer of R19 but 90degress off, covered by PolyIso panels. Anything to avoid working with DW


How are you going to deal with keeping the room heated or cooled if you cover the vents?


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/440_40#post_24723304
> 
> 
> Anything to avoid working with DW



This is your tragic flaw in logic, Superior soundproofing is a result of a balanced approach of Mass, Dampening. Isolation and Absorption. Two layers of DW with Green Glue dampening agent, hung on a clip and channel isolation system for the walls and ceiling should get the job done. Sounds like you have the insulation part (Absorbtion) completed Drywall is your mass in the equation.


----------



## VolkerH.




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/450#post_24723335
> 
> 
> How are you going to deal with keeping the room heated or cooled if you cover the vents?


There are no vents terminating in the room. Only ducts leading through the ceiling in that room which terminate in the second floor.

For heating needs (during winter) I might relay on a space heater. For the summer I might be ok with the temp. The basement stays cool. Though I don't have much data yet,we just bought the place.


----------



## VolkerH.




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/450#post_24723530
> 
> 
> This is your tragic flaw in logic, Superior soundproofing is a result of a balanced approach of Mass, Dampening. Isolation and Absorption. Two layers of DW with Green Glue dampening agent, hung on a clip and channel isolation system for the walls and ceiling should get the job done. Sounds like you have the insulation part (Absorbtion) completed Drywall is your mass in the equation.


Is that to keep noise out, to keep noise in (which I'm after) or both ?


----------



## ClemsonJeeper




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/450#post_24716566
> 
> 
> You could actually get a notable bang for the buck without pulling the ceiling at all -- just add another layer of 5/8 Type X to your existing layer all around (with Green Glue in between, preferably). Get a good quality solid core door and make sure it seals when it closes. That'll make a notable difference.
> 
> 
> But yeah, pulling the ceiling and decoupling and then adding insulation would go a LOT farther. It's all what your goals are and what you're willing to do ;-)



Is that really a noticeable difference? I've read people's threads who have done double drywall without decoupling and were less than impressed with the results. I'd consider sticking a layer of 5/8 over the existing drywall with GG if it actually would make a reasonable difference.


----------



## granroth




> Quote:
> Originally Posted by *ClemsonJeeper*  /t/1509173/soundproofing-master-thread/400_100#post_24723736
> 
> 
> Is that really a noticeable difference? I've read people's threads who have done double drywall without decoupling and were less than impressed with the results. I'd consider sticking a layer of 5/8 over the existing drywall with GG if it actually would make a reasonable difference.



Double drywall with GG all around will give you an STC 5 increase. That's absolutely noticeable. BUT the devil is in the details. You could go with double drywall all around and then not address the door and see essentially no difference. Sound always finds the easiest pathway and if a flanking path exists, then it'll take it. That STC 5 increase is lost with a standard hollow core door or even a solid core one with no seals.


STC 5 is noticeable, but it's not groundbreaking. Doing the full decoupling + insulation + double drywall + GG (and treating the door) will make a MASSIVE difference.


Honestly, I wouldn't ever do just the drywall, since the added expense and effort to do it all up right isn't significantly more (relatively speaking). That's me, though


----------



## granroth




> Quote:
> Originally Posted by *VolkerH.*  /t/1509173/soundproofing-master-thread/400_100#post_24723589
> 
> 
> Is that to keep noise out, to keep noise in (which I'm after) or both ?



Soundproofing always works both ways.


----------



## ellisr63

How do you deal with a bundle of wires (cat5 and rg6) entering a double walled HT? Do you just cut a big hole, and use clay pads to seal it off from the back side?


----------



## panino




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/450#post_24733347
> 
> 
> How do you deal with a bundle of wires (cat5 and rg6) entering a double walled HT? Do you just cut a big hole, and use clay pads to seal it off from the back side?



Depends on how many wires. I drilled 1/4 to 1/2 inch holes and stuffed the cables through them. I made the holes only as big as needed and then after the wires were through sealed the hole and around the wires with acoustic caulk.


----------



## ellisr63




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/450#post_24733864
> 
> 
> Depends on how many wires. I drilled 1/4 to 1/2 inch holes and stuffed the cables through them. I made the holes only as big as needed and then after the wires were through sealed the hole and around the wires with acoustic caulk.


So we have around 20 wires... Would it be best to drill 20 holes that are just big enough, then run each wire individually, and then clay or caulk each hole?


----------



## panino




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/450#post_24733982
> 
> 
> 
> So we have around 20 wires... Would it be best to drill 20 holes that are just big enough, then run each wire individually, and then clay or caulk each hole?


 

Why so many wires?   You could easily squeeze several of them through each 1/4" hole and then you might be able to get away with only drilling a small series of holes.  Personally I wouldn't make 20 separate holes if you can avoid it.  That's like turning your wall into swiss cheese.  Another option is to run something like ENT conduit (3/4" or bigger) through the wall, caulk the gap between conduit and wall, and then plug the conduit after the wires are through.  This way you can still remove or run new wires through the conduit later if needed.  However, I should probably defer to someone else on the forum who has actually run this many wires into their HT through one spot.


----------



## ellisr63




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/450#post_24734078
> 
> 
> Why so many wires?   You could easily squeeze several of them through each 1/4" hole and then you might be able to get away with only drilling a small series of holes.  Personally I wouldn't make 20 separate holes if you can avoid it.  That's like turning your wall into swiss cheese.  Another option is to run something like ENT conduit (3/4" or bigger) through the wall, caulk the gap between conduit and wall, and then plug the conduit after the wires are through.  This way you can still remove or run new wires through the conduit later if needed.  However, I should probably defer to someone else on the forum who has actually run this many wires into their HT through one spot.


We have a 24 port switch and it will be in the HT room most likely... If we put it in a different room then we would have around 10 cat 5 cables to exit the room to the switch. The only other option I can think of is to get a small gigabit switch and let it connect to the 24 port one, but I don't like having a bunch of them to have to setup. My concern with a big hole is you will only be sealing the outer edge of the wires, and sound could leak through between the wires. Another option I thought of was to mount a patch panel in the wall, but then I am looking at a big hole that is plugged by a piece of metal with a bunch of ports... Which I think would mean even more leakage.


----------



## artur9

For experimental purposes, I took 2 16x48x3 Roxul SafeNSound panels and placed them between the drop ceiling and a duct/vent directly above my home theater area. It made quite a lot of difference so I'm looking forward to doing all the joists with renewed optimism.


----------



## panino




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/450#post_24734145
> 
> 
> 
> We have a 24 port switch and it will be in the HT room most likely... If we put it in a different room then we would have around 10 cat 5 cables to exit the room to the switch. The only other option I can think of is to get a small gigabit switch and let it connect to the 24 port one, but I don't like having a bunch of them to have to setup. My concern with a big hole is you will only be sealing the outer edge of the wires, and sound could leak through between the wires. Another option I thought of was to mount a patch panel in the wall, but then I am looking at a big hole that is plugged by a piece of metal with a bunch of ports... Which I think would mean even more leakage.


 

Just thinking outside of the box here.  I wonder if you could use something like a foam cable entry box (e.g. http://www.blackbox.com/Store/Detail.aspx/Elite-QuietCab-Cable-Entry-Box/QCE%C4%82CEB ), used in server/pc equipment storage cabs.  Maybe there is a way to incorporate a foam cable entry box into the wall or even into a backer box on your wall's entry point.  It would probably be fairly easy to seal/caulk the edges of one of these cable entry boxes and the foam would prevent the sound leakage around the cables as they would all be laid out flat.  I have no experience with this nor do I know if it would even work, but just a thought.  Other option I guess is drill a bunch of small holes and putty pad or caulk as previously discussed.


----------



## SimpleTheater




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/450#post_24734145
> 
> 
> We have a 24 port switch and it will be in the HT room most likely... If we put it in a different room then we would have around 10 cat 5 cables to exit the room to the switch. The only other option I can think of is to get a small gigabit switch and let it connect to the 24 port one, but I don't like having a bunch of them to have to setup. My concern with a big hole is you will only be sealing the outer edge of the wires, and sound could leak through between the wires. Another option I thought of was to mount a patch panel in the wall, but then I am looking at a big hole that is plugged by a piece of metal with a bunch of ports... Which I think would mean even more leakage.


_In cases where one wants the ability to make temporary connections between rooms the solution is to install some PVC pipe fittings through the wall and use what plumbers call a “Tee – Wye” fitting with a threaded “clean out” on each end. This series of fittings can be “force fitted” into the wall with foam insulation or secured with silicone. Each side would have a hand tightened plastic plug so you can see what you are doing (straight line view through the wall with the plug removed) while passing the wires through, but the wires themselves would actually be going the indirect route via the “leg” of the wye section. After the wires are in place one need only stuff some foam rubber into the open pipe ends then screw the caps back on to minimize any direct sound transfer. These two fittings need not be directly connected to each other inside the wall and can have a small gap between them to keep the sound / vibration transfer to a minimum. The whole idea is just to have a sealed but neat looking access port between the two sides._
http://www.sweetwater.com/insync/running-wires-through-sound-proof-walls/


----------



## ellisr63

I am ordering my door seals, and I am not sure which to get.


Should I get this one... http://www.tmsoundproofing.com/Door-Seal-Self-Adhesive.html 


or this one... http://www.tmsoundproofing.com/Door-Seal-Self-Adhesive-Batwing-style.html 


I am also trying to decide between these 2 auto door seals...
http://www.tmsoundproofing.com/heavy-duty-automatic-door-bottom-soundproof.html 


or this one...
http://www.tmsoundproofing.com/Heavy-Duty-High-Sound-Automatic-Door-Bottom.html 



Should I get a threshold too? http://www.tmsoundproofing.com/Utility-Door-Threshold-1-4-Height.html 

We have 2 solid core doors separated by 6' and the hallway is more of a ramp like you see in the theaters... We will have carpet once you cross the first threshold. Outside of the first door is flagstone.


----------



## ClemsonJeeper

I'm flip flopping on soundproofing. After being in someones soundproofed theater this past weekend, I'm flopping more back towards going for it.


Right now, the room is finished on 3 sides with 1/2 drywall + ceiling. I'd obviously have to pull all this down to get to the studs.


2 of the walls (the back of the room and the right of the room ) are up against concrete foundation. The left wall is shared with a bathroom and the main rec room. The front wall I have already torn out since I am moving it back 2 feet and building a stage / false wall for speakers behind.


My concerns are room width. As it is now with the 1/2" finished drywall, the room is 11'11". My chairs are 3x fusion escapes which sit at about 98" wide or so, so that gives me a little under 2 feet (22.5") on each side for passage to the rear row. This is tight but acceptable for me given the room size. However if I add on clips + dd + gg, this removes 2 3/8" on each side of clearance (if my math is correct) so now I'm down to 20" on each side -- even more cramped.


Any suggestions with this?


I've thought about tearing down the right foundation wall and rebuilding it with IB3 clips mounting to blocking to the joists. I'd only be doing one of the foundation walls because I'm not length constrained - just width constrained). I think this would save me on the clip installation of 1 5/8 on the wall so that would just be 2 layers of 5/8 DW. So that would only add 3/4" on the right side of the room. The left side I am stuck using whisper clips because it is sharing a bathroom + rec room finished wall. If I go this route this means I will only be losing 3 1/8" width (2 3/8" for WhisperClips + DD + GG and 0.75 for DD+GG on the IB3 wall).


Does all this math sound right?


Some questions then. When framing a IB3 wall, how do you do it properly (any tips/tricks)? I obviously want to build the wall shorter than normal so it barely reaches the joists and I use the clips to attach to joists (or to blocking between joists)? How do I connect the framed walls side by side to existing framed walls that are attached to the joists?


Also with respect to using a double layer of drywall or using a first layer of 5/8 osb then 5/8 drywall - why do people do this? Is it recommended? Which is more difficult to install?


When hanging drywall, do you start on the ceiling or walls? I'm guessing I will need to build backer boxes for any penetrations in the drywall (I'm likely going to sink my surrounds into the wall some to save on them sticking out into the room sofar). How do you attach the backer boxes to your drywall shell?


With respect to HVAC, there are two runs that go the width of the room that feed the room above. Do I need to treat these? I also have 2 supplies and no return into the room. My HVAC unit is in the unfinished area behind my screen wall, so its relatively easy access. I'm also planning on adding soffits after the drywall shell goes up so I can pretty easily run a return to the rear of the room in the soffit (maybe even turn a portion of the entire soffit into a return as Jeff suggested). Either way - I have to penetrate the drywall shell to get the return in there - how do you go about doing that in a soundproofed sort of way?


More questions, with a serenity mat. Would you only use it + OSB underneath a stage where big subs would be sitting?


Lots of questions - hope people can help!


----------



## cw5billwade




> Quote:
> Originally Posted by *ClemsonJeeper*  /t/1509173/soundproofing-master-thread/450#post_24746962
> 
> 
> I'm flip flopping on soundproofing. After being in someones soundproofed theater this past weekend, I'm flopping more back towards going for it.
> 
> 
> Right now, the room is finished on 3 sides with 1/2 drywall + ceiling. I'd obviously have to pull all this down to get to the studs.
> 
> 
> 2 of the walls (the back of the room and the right of the room ) are up against concrete foundation. The left wall is shared with a bathroom and the main rec room. The front wall I have already torn out since I am moving it back 2 feet and building a stage / false wall for speakers behind.
> 
> no need for clips here if you can decouple the studs from the ceiling joists. Just two layers with GG.
> 
> 
> My concerns are room width. As it is now with the 1/2" finished drywall, the room is 11'11". My chairs are 3x fusion escapes which sit at about 98" wide or so, so that gives me a little under 2 feet (22.5") on each side for passage to the rear row. This is tight but acceptable for me given the room size. However if I add on clips + dd + gg, this removes 2 3/8" on each side of clearance (if my math is correct) so now I'm down to 20" on each side -- even more cramped.
> 
> correct math but agian only on one side
> 
> 
> I've thought about tearing down the right foundation wall and rebuilding it with IB3 clips mounting to blocking to the joists. I'd only be doing one of the foundation walls because I'm not length constrained - just width constrained). I think this would save me on the clip installation of 1 5/8 on the wall so that would just be 2 layers of 5/8 DW. So that would only add 3/4" on the right side of the room. The left side I am stuck using whisper clips because it is sharing a bathroom + rec room finished wall. If I go this route this means I will only be losing 3 1/8" width (2 3/8" for WhisperClips + DD + GG and 0.75 for DD+GG on the IB3 wall).
> 
> per Sound Proffing Company IB-1 clips will work just as good as the Whisper and save you money and about 1/2"
> 
> 
> Some questions then. When framing a IB3 wall, how do you do it properly (any tips/tricks)? I obviously want to build the wall shorter than normal so it barely reaches the joists and I use the clips to attach to joists (or to blocking between joists)? How do I connect the framed walls side by side to existing framed walls that are attached to the joists?
> 
> start as close to the corner as you can i.e. first floor joist and then every 48" along the wall. leave about 1' between top of wall and floor joist
> 
> 
> Also with respect to using a double layer of drywall or using a first layer of 5/8 osb then 5/8 drywall - why do people do this? Is it recommended? Which is more difficult to install?
> 
> I did OSB so I could then mount my columns, soffits, coffers, projector and the like this gives you something to screw them into without having to hit a channel. Also same with the trim just hit it with a brad nailer and call it a day.
> 
> 
> When hanging drywall, do you start on the ceiling or walls? I'm guessing I will need to build backer boxes for any penetrations in the drywall (I'm likely going to sink my surrounds into the wall some to save on them sticking out into the room sofar). How do you attach the backer boxes to your drywall shell?
> 
> ceiling first layer insure it does not tuch any studs then walls back to ceiling than walls
> 
> 
> With respect to HVAC, there are two runs that go the width of the room that feed the room above. Do I need to treat these?
> 
> If you are using clips on the ceiling I think I would use R13 under the HVAC line and R19 every where else
> 
> 
> I also have 2 supplies and no return into the room. My HVAC unit is in the unfinished area behind my screen wall, so its relatively easy access. I'm also planning on adding soffits after the drywall shell goes up so I can pretty easily run a return to the rear of the room in the soffit (maybe even turn a portion of the entire soffit into a return as Jeff suggested). Either way - I have to penetrate the drywall shell to get the return in there - how do you go about doing that in a soundproofed sort of way?
> 
> penetrate in the soffits then stuff around the HVAC with R19 or what every you have then the soffits are also DW/GG/DW same with the supplies check my thread
> 
> 
> More questions, with a serenity mat. Would you only use it + OSB underneath a stage where big subs would be sitting?
> 
> did not use it no help here
> 
> 
> Lots of questions - hope people can help!


----------



## ClemsonJeeper




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/450#post_24748859
> 
> 
> no need for clips here if you can decouple the studs from the ceiling joists. Just two layers with GG.



Cool. This is what I'm going to do. Tear down the two framed foundation walls, and rebuild using IB3 clips.


> Quote:
> per Sound Proffing Company IB-1 clips will work just as good as the Whisper and save you money and about 1/2"



Cool. I ended up going with WhisperClips since everyone here seems to recommend them. I'm not too too concerned with 1/2". (I say that now).


> Quote:
> start as close to the corner as you can i.e. first floor joist and then every 48" along the wall. leave about 1' between top of wall and floor joist



John @ TSG also said I should do 24 on center studs which should be plenty so it minimizes the amount of transfer points even though its decoupled. Think this would still be sturdy enough to hang 5/8 OSB + 5/8 Drywall?


> Quote:
> I did OSB so I could then mount my columns, soffits, coffers, projector and the like this gives you something to screw them into without having to hit a channel. Also same with the trim just hit it with a brad nailer and call it a day.



Yeah this is my plan. I'm likely only going to be doing soffits (no columns, coffers, etc). But I like the idea of just hanging the OSB and it being more rigid.


> Quote:
> ceiling first layer insure it does not tuch any studs then walls back to ceiling than walls



How far off the studs do I need to set the ceiling? My guess would be 1 1/4" off the studs that are decoupled (since there are no clips) and that leaves room for the OSB + Drywall + GG. Then on the single wall with clips, leave 2 7/8 for the clip + osb + drywall + gg? This way I leave enough room for all the hardware + osb + drywall and then I when I do the walls I should be able to just install it butting up to the ceiling layer?


> Quote:
> If you are using clips on the ceiling I think I would use R13 under the HVAC line and R19 every where else



Yeah just going to do insulation in the ceiling and maybe change from rigid lines to flex ducts.


> Quote:
> penetrate in the soffits then stuff around the HVAC with R19 or what every you have then the soffits are also DW/GG/DW same with the supplies check my thread



Won't this still transmit a ton of sound back into the HVAC system?


Thanks for the help! Got my clips ordered and should be here saturday. Busy gutting the room right now.


----------



## cw5billwade




> Quote:
> Originally Posted by *ClemsonJeeper*  /t/1509173/soundproofing-master-thread/450#post_24749877
> 
> 
> 
> John @ TSG also said I should do 24 on center studs which should be plenty so it minimizes the amount of transfer points even though its decoupled. Think this would still be sturdy enough to hang 5/8 OSB + 5/8 Drywall?
> should be fine being in bonus room mine were 24" on cneter
> 
> 
> How far off the studs do I need to set the ceiling? My guess would be 1 1/4" off the studs that are decoupled (since there are no clips) and that leaves room for the OSB + Drywall + GG. Then on the single wall with clips, leave 2 7/8 for the clip + osb + drywall + gg? This way I leave enough room for all the hardware + osb + drywall and then I when I do the walls I should be able to just install it butting up to the ceiling layer?
> I think you are over thinking it. On the decoupled walls (IB-3 clips next to concrete) you need between 1/8” and 1/4" away from 2x4 since your first layer on the wall will be screwed to 2x4. on whisper clip side just as long as it extends past the channel and does not touch the 2x4. You want the wall layer to butt up to the ceiling then caulk the cracks
> 
> 
> Yeah just going to do insulation in the ceiling and maybe change from rigid lines to flex ducts.
> 
> Won't this still transmit a ton of sound back into the HVAC system?
> if these lines are for main house I would not change them as flex will reduce air flow and your HVAC is designed with the current hard lines. I would leave them. As for the sound transmission like I said I would put R13 or even some ridged insulation like roxel between them and the OSB layer and R19 stapled to the rest of the floor joists.
> 
> 
> Thanks for the help! Got my clips ordered and should be here saturday. Busy gutting the room right now.


----------



## ellisr63

We have our dryer ducting that will be running along the floor in a soffit in our HT room... Is it sufficient to stuff the soffit with insulation, and double drywall it or should we use 4" insulated HVAC flex ducting?


----------



## BIGmouthinDC

Dryer ducting that runs in concealed spaces should be metal to reduce the chance of a fire being spread via the duct. It also needs to be sturdy enough to withstand the insertion and operation of a lint clean-out brush along the entire route. Try to avoid tight bends. You could add damped mass to the outside of the duct to minimize sound transfer, Like Dynamat Extreme. You can add some insulation, and while I think Fiberglass is OK to be on the safe side you could surround it with Roxul.


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/450#post_24779074
> 
> 
> Dryer ducting that runs in concealed spaces should be metal to reduce the chance of a fire being spread via the duct. It also needs to be sturdy enough to withstand the insertion and operation of a lint clean-out brush along the entire route. Try to avoid tight bends. You could add damped mass to the outside of the duct to minimize sound transfer, Like Dynamat Extreme. You can add some insulation, and while I think Fiberglass is OK to be on the safe side you could surround it with Roxul.


Sounds good. The only tight bend will be the 90 degree it has to do when it comes out of the wall to go into the soffit. We will stick with the whole run being metal, and I will lookinto dynamat or something similar to see how expensive it will be... Otherwise I will go with insulation, and double drywall with green glue.


----------



## BIGmouthinDC

Take a look at this bend:

http://www.dryer-ell.com/welcome_dryerell.htm


----------



## ellisr63

Thanks


> Quote:
> Originally Posted by *BIGmouthinDC*  /t/1509173/soundproofing-master-thread/480#post_24779230
> 
> 
> Take a look at this bend:
> 
> http://www.dryer-ell.com/welcome_dryerell.htm


Thanks, I will see how much room we have to do it that way. I wish the dryer vent could go through the floor as it would give us more room for the curve.


----------



## granroth

A soundproof sliding barn door?


I wonder if it's possible to make a reasonably decent soundproof door in a sliding barn door form. The key problem would be the seals, since those type of doors are typically completely loose on the sides and bottoms and only hanging off of rollers on the top. Having it being even remotely soundproof would require it to somehow seal itself when it was shut.


Has this ever been done? If so, what are the details?


An example:


----------



## panino




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24783486
> 
> 
> A soundproof sliding barn door?
> 
> 
> I wonder if it's possible to make a reasonably decent soundproof door in a sliding barn door form. The key problem would be the seals, since those type of doors are typically completely loose on the sides and bottoms and only hanging off of rollers on the top. Having it being even remotely soundproof would require it to somehow seal itself when it was shut.
> 
> 
> Has this ever been done? If so, what are the details?


 

Definitely haven't done this, but it sounds like a fun challenge.  What about designing the track so that as the door slides closed it also makes the door come a little closer to the door frame/jamb? e.g. a track not quite parallel to the door frame.  Sort of like a wedge effect  Incorporating some seals along the door frame near the casing would then engage the door as it slides closed and wedges a little closer to the frame.  As for the bottom of the door, you could probably install an automatic door bottom that would engage when the door hits the end of the track.  Those doors are pretty heavy... the weight of the door should theoretically keep it quite snug against the seals once they are touching.

 

Are you actually building one of these?


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24783486
> 
> 
> A soundproof sliding barn door?
> 
> 
> I wonder if it's possible to make a reasonably decent soundproof door in a sliding barn door form. The key problem would be the seals, since those type of doors are typically completely loose on the sides and bottoms and only hanging off of rollers on the top. Having it being even remotely soundproof would require it to somehow seal itself when it was shut.
> 
> 
> Has this ever been done? If so, what are the details?
> 
> 
> An example:


I think you could do it if you put seals all around the door opening and then put a crank type door mechanism that pulled the door in tight as it sealed it... Maybe similar to this but going from side to side. http://s1065.photobucket.com/user/ellisr63/media/door_zpse9a5329d.jpg.html


----------



## granroth




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/400_100#post_24801877
> 
> 
> Definitely haven't done this, but it sounds like a fun challenge.  What about designing the track so that as the door slides closed it also makes the door come a little closer to the door frame/jamb? e.g. a track not quite parallel to the door frame.  Sort of like a wedge effect  Incorporating some seals along the door frame near the casing would then engage the door as it slides closed and wedges a little closer to the frame.  As for the bottom of the door, you could probably install an automatic door bottom that would engage when the door hits the end of the track.  Those doors are pretty heavy... the weight of the door should theoretically keep it quite snug against the seals once they are touching.



Hmm... that's an idea. The fact that they weigh so much also makes me think of a modified idea -- what if I put gaskets all the way around the door opening and then assume that whoever opens or closes the door will do so by essentially pulling it "out", first. That is, the door essentially acts like a pendulum since it pivots only on the top rail. If you have to pull it away from the wall slightly just to move it, then that could "disengage" it from the gaskets.


Using an auto door bottom is an interesting idea, as well.


> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/400_100#post_24801877
> 
> 
> Are you actually building one of these?



Well, I am absolutely going to be building a sliding barn door for the outer door of my theater. It's a WAF requirement. Given that hard requirement, I'm trying to think of a way that I could also make it as soundproof as possible -- just as extra gravy. This'll all be after most of the rest of the theater is done, though (still months and months away).


----------



## granroth




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/400_100#post_24802045
> 
> 
> I think you could do it if you put seals all around the door opening and then put a crank type door mechanism that pulled the door in tight as it sealed it... Maybe similar to this but going from side to side. http://s1065.photobucket.com/user/ellisr63/media/door_zpse9a5329d.jpg.html



Heh, yeah, something like this could potentially work... but there's NO WAY I could get that to fly with my wife. She wants it to look just like a barn door and the farther I deviate from that, the more likely it ain't gunna happen.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24802345
> 
> 
> Heh, yeah, something like this could potentially work... but there's NO WAY I could get that to fly with my wife. She wants it to look just like a barn door and the farther I deviate from that, the more likely it ain't gunna happen.


What if you made it like a barn door... But when it slides into position the track moves it closer to seal it? We wanted a rustic look on ours, and we did this... http://s1065.photobucket.com/user/ellisr63/media/OurHTdoor_zps5d85f0c4.jpg.html


----------



## panino




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24802345
> 
> 
> 
> Heh, yeah, something like this could potentially work... but there's NO WAY I could get that to fly with my wife. She wants it to look just like a barn door and the farther I deviate from that, the more likely it ain't gunna happen.


 

 

 

What about something like this, but you can mount the barn door on the front of the metal door?


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24783486
> 
> 
> A soundproof sliding barn door?
> 
> 
> I wonder if it's possible to make a reasonably decent soundproof door in a sliding barn door form. The key problem would be the seals, since those type of doors are typically completely loose on the sides and bottoms and only hanging off of rollers on the top. Having it being even remotely soundproof would require it to somehow seal itself when it was shut.
> 
> 
> Has this ever been done? If so, what are the details?
> 
> 
> An example:


I think if you bend the top bar to make the door move closer to the door opening you could do it. It would look 100% like a sliding barn door ... It would just slide in to seal the opening when shut.


----------



## granroth




> Quote:
> Originally Posted by *panino*  /t/1509173/soundproofing-master-thread/400_100#post_24804315
> 
> 
> 
> 
> What about something like this, but you can mount the barn door on the front of the metal door?



Hah! Yeah, I refer to the main theater door that'll be built as a "bank vault" style door (multiple layers), but doing so almost seems like an insult compared to the real thing!


----------



## cw5billwade




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24802344
> 
> 
> Well, I am absolutely going to be building a sliding barn door for the outer door of my theater. It's a WAF requirement. Given that hard requirement, I'm trying to think of a way that I could also make it as soundproof as possible -- just as extra gravy. This'll all be after most of the rest of the theater is done, though (still months and months away).


I saw a build where they bought a sliding door that did just that it snaped into place at the end of the track I just can't find it now. I think the door came that way nothing they had to jurry rig. I will look some more.


----------



## granroth




> Quote:
> Originally Posted by *cw5billwade*  /t/1509173/soundproofing-master-thread/400_100#post_24810353
> 
> 
> I saw a build where they bought a sliding door that did just that it snaped into place at the end of the track I just can't find it now. I think the door came that way nothing they had to jurry rig. I will look some more.



Yeah, I may be thinking of the same one. Was it a false bookcase or something?


Thing is, I read so many build threads that they all run together and I don't know if something happened recently or five years ago


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24811646
> 
> 
> Yeah, I may be thinking of the same one. Was it a false bookcase or something?
> 
> 
> Thing is, I read so many build threads that they all run together and I don't know if something happened recently or five years ago


There was a guy in Sweden that did a sliding door, but his was like a vault door and it was like 12" thick. He had a custom latch mechanism on it too... I am not sure if that is the one you are thinking of or not.


----------



## granroth

This was the one I was thinking of: http://www.avsforum.com/t/1339780/another-erskine-designed-masterpiece-if-i-dont-screw-it-up/400_100#post_24424843 


And the video of the mechanism in action:





I don't think I'd be able to use that mechanism as-is, since it opens "in" and I need one that opens "out". Plus, it's intended for hidden doors. And it's $900 for the mechanism alone! HOWEVER, the close-up at 25 seconds gives me the idea that what I need is TWO tracks and I can do roughly the same but in reverse. This would almost surely work if I learn better metal working skills than I currently have.


----------



## cw5billwade




> Quote:
> Originally Posted by *ellisr63*  /t/1509173/soundproofing-master-thread/480#post_24812512
> 
> 
> There was a guy in Sweden that did a sliding door, but his was like a vault door and it was like 12" thick. He had a custom latch mechanism on it too... I am not sure if that is the one you are thinking of or not.





> Quote:
> Originally Posted by *granroth*  /t/1509173/soundproofing-master-thread/480#post_24812762
> 
> 
> This was the one I was thinking of: http://www.avsforum.com/t/1339780/another-erskine-designed-masterpiece-if-i-dont-screw-it-up/400_100#post_24424843
> 
> 
> And the video of the mechanism in action:
> 
> 
> 
> 
> 
> I don't think I'd be able to use that mechanism as-is, since it opens "in" and I need one that opens "out". Plus, it's intended for hidden doors. And it's $900 for the mechanism alone! HOWEVER, the close-up at 25 seconds gives me the idea that what I need is TWO tracks and I can do roughly the same but in reverse. This would almost surely work if I learn better metal working skills than I currently have.


Yea I think that was it. But you should be able to mount it on either side either pushing out of the theater or pushing into the theater. It just depends where you want the rails. It looks like he hid it behind a reclaimed wood facade and sort of made it into a pocket.


----------



## kmhvball

Well, I last night I made my 12 'backer boxes', which maybe I would call more of a 'Backer Sandwich", it took about an hour in total... This relates back to Post 427/29 (&448)

I ended up with this configuration:
3/4" MDF Solid with Green Glue
5/8" Drywall Solid w Green Glue
3/8" Drywall w/ Hole w Green Glue
3/8" Dyrwall w/ Hole 

I used this based on the concern expressed about Fire hazard, figuring the fire-rated drywall would be the way to go - and frankly, much easier to 'cut' that as well, so, doing it again - I probably would do two layers of the 5/8" solid Drywall. 

Then with the two ceiling layers of 5/8" drywall, the box depth will match my ceiling depth with my 'backer' boxes.

Here are the parts in there individual piece forms...









Here are the parts with Green Glue applied... "Learning", I applied the GG to the 'fronts', defined as the part on the Theater side vs the 'ceiling/subfloor' side of the MDF, 5/8" Drywall, and the 3/8" Drywall... This meant when I did the 5/8" drywall 'all over', the 3/8" light box 'hole' had GG all over. So, to do it again, I would put the GG on the 'theater side' of the two 3/8" drywall layers, and the theater side of the 5/8" drywall layer..










Here is what the 'final' product looks like. These will be installed onto the subfloor side of the drywall in the correct locations before the Drywall is lifted into place. The circle at the top is the Surface Mount LED light.










We'll see how this all works out.


----------



## SteveS78

I have a contractor finishing my basement currently. He quoted me to put sound proofing in the ceiling. It was going to be a special sound proofing material that they use in recording studios. They tried installing it but apparently it wasn't staying put in my ceiling, so they decided to go with 10 inches of the standard pink fiber insulation, which he said they also use for sound proofing depending on the circumstance. 

My question is, is this a sufficient sound proofing material that will do the same job as the specific sound proofing material? Or is this not good for what I need?


----------



## cw5billwade

Standard pink fiberglass insulation is sll you need insure the drywall is decoupled wit clips and hat channel and use backer boxes on all light fixtures


----------



## SteveS78

cw5billwade said:


> Standard pink fiberglass insulation is sll you need insure the drywall is decoupled wit clips and hat channel and use backer boxes on all light fixtures


Dude, I am not the person doing the work. I have a contractor doing it for me. I am at work everyday when they are at my house, doing everything. So I only check out what they have done each day when I get home after 5:30.

Why do these other things you mentioned need to be done? I am just paying for sound proofing material and the labor to put it in. I do not feel comfortable telling these guys how to do their job, especially since I am not even there when they are working on it.

Thanks for the help!


----------



## ClemsonJeeper

SteveS78 said:


> Dude, I am not the person doing the work. I have a contractor doing it for me. I am at work everyday when they are at my house, doing everything. So I only check out what they have done each day when I get home after 5:30.
> 
> Why do these other things you mentioned need to be done? I am just paying for sound proofing material and the labor to put it in. I do not feel comfortable telling these guys how to do their job, especially since I am not even there when they are working on it.
> 
> Thanks for the help!


Because for quality soundproofing you need to attack the problem from multiple angles. One of which is decoupling your drywall from the studs/joists.

I don't think you will be too happy with the results of just stuffing insulation into all the walls and calling it a day. Will it help? Yes, compared to a hollow wall it might absorb a little sound. I guess it depends on your end goal.

If they haven't dry walled yet, then clips + channel is a relatively inexpensive thing to add at this point. Just make sure when they only put screws into the channel and don't hit studs.


----------



## SteveS78

Would you need to do the same thing (decoupling) if the special sound proofing material was installed up there as opposed to the stanard pink fiber insulation? You would need to do that either way?

Thanks


----------



## kmhvball

I suggest checking out the soundproofingcompany web-site. They discuss the 4 elements of sound proofing:
1) De-coupling (i.e., the clips & Channel)
2) Mass (i.e., 2 layers of 5/8" Drywall on the ceiling/walls)
3) Dampening (i.e., a material called Green Glue used between Drywall layers)
4) Absorption (i.e., insulation type material)

Absorption is the least impactful. The data suggests no particular forms of insulation, whether pink fluffy insulation, or 'sound studio insulation' is much better than others.

If you truly want good sound reduction, you need to use all 4 parts of the equation. If you want 'better than nothing', then adding insulation is an improvement - but not a whole lot. 

Depends what your goals/objectives are of the space.


----------



## ClemsonJeeper

SteveS78 said:


> Would you need to do the same thing (decoupling) if the special sound proofing material was installed up there as opposed to the stanard pink fiber insulation? You would need to do that either way?
> 
> Thanks


It all depends on your soundproofing goals. No amount of "special soundproofing material" in a wall is going to accomplish what taking multiple steps toward soundproofing will do.

Most people on here will do:

1) Decoupling
2) Damping
3) Mass
4) Absorption

Some good reading is at http://www.soundproofingcompany.com/soundproofing101/4-elements-of-soundproofing-for-construction/

If the people building your room are telling you that just putting some "special soundproofing material" or insulation in the walls will get you a totally soundproofed room, then you need to get a second opinion.


Edit: just saw kmhvball's post above mine.. beat me to it.


----------



## cw5billwade

what they said don't let them take your money saying they are soundproofing the ceiling. $400 for insulation and labor to install is all I would pay if that is all they are doing.


----------



## granroth

SteveS78 said:


> I have a contractor finishing my basement currently. He quoted me to put sound proofing in the ceiling. It was going to be a special sound proofing material that they use in recording studios. They tried installing it but apparently it wasn't staying put in my ceiling, so they decided to go with 10 inches of the standard pink fiber insulation, which he said they also use for sound proofing depending on the circumstance.
> 
> My question is, is this a sufficient sound proofing material that will do the same job as the specific sound proofing material? Or is this not good for what I need?


It's important to note that there are no realistic magic bullets with soundproofing. Okay, yeah, maybe a 6 foot thick solid concrete wall would be a single soundproofing component that would fit the bill on its own... but short of that, you're going to need to combine several elements to get a worthwhile effect.

Without knowing what the "special sound proofing material" is, it's not possible to say what effect it would have nor what an alternative would be. It could contribute to mass, damping, or absorption (or some combination), all of which could have different alternatives. I can say that that material alone would not have soundproofed your room. At best, it would have reduced the sound level of transferred noise by some number of decibels for certain frequencies -- but not all, and likely not to the level that you'd prefer.

Standard pink fiberglass insulation is, indeed, a common soundproofing component. It works as an absorption agent. Like the aforementioned special soundproofing material, it will reduce the sound level of a range of (mostly higher) frequencies. Depending on how it was installed, it could also contribute towards acoustically controlling sound inside of the room (a separate topic). Really, it's great stuff and it's why it's used so commonly.

BUT, it should only be considered one part of a soundproofing strategy and a relatively minor one at that.


----------



## SteveS78

Thanks for the info guys. I called my contractor today and brought this up to him. He said they had installed the decoupled clips eith metal channels on some homes before with some mixed results. They had some homes where this was done, and there was an annoying squeaking sound to go along with it. He did however get a price for me for adding the decoupled clips and channel. He quoted me $350 for doing that to the TV side of the basement. Which is the portion they insulated for me.

One thing I would like to note. I am not really looking for a professional level recording studio caliber bit of sound proofing where the room being constructed becomes basically a sound vacuum and literally nothing gets out soundwise. All I am really trying to accomplish is not waking up our 1 year old daughter after 8 or 9 pm when she is asleep while we are trying to watch a movie in the basement. Keep in mind, we live in a 2 story home, all bedrooms are on the 2nd floor and the basement is of course below ground meaning there is one floor between the basement and the bedrooms which helps.

Will what I am doing be sufficient for that?


----------



## granroth

SteveS78 said:


> Thanks for the info guys. I called my contractor today and brought this up to him. He said they had installed the decoupled clips eith metal channels on some homes before with some mixed results. They had some homes where this was done, and there was an annoying squeaking sound to go along with it. He did however get a price for me for adding the decoupled clips and channel. He quoted me $350 for doing that to the TV side of the basement. Which is the portion they insulated for me.
> 
> One thing I would like to note. I am not really looking for a professional level recording studio caliber bit of sound proofing where the room being constructed becomes basically a sound vacuum and literally nothing gets out soundwise. All I am really trying to accomplish is not waking up our 1 year old daughter after 8 or 9 pm when she is asleep while we are trying to watch a movie in the basement. Keep in mind, we live in a 2 story home, all bedrooms are on the 2nd floor and the basement is of course below ground meaning there is one floor between the basement and the bedrooms which helps.
> 
> Will what I am doing be sufficient for that?


Clips and channels absolutely go a long way towards reducing sound travel. You do need to be a little careful about what materials are used as well as how it's done. For instance, some contractors like to use resilient channel assuming it's the same thing and it's simply not.

Will that be sufficient for your purposes? I really hate to say it, but we simply can't predict that. Stopping the propagation of sound waves requires an integrated solution since all the parts work together and can, non-ideally, work against each other. For instance, if you concentrate all efforts on one wall, then that will likely ignore the flanking paths that sound can take through the other walls and the ceiling. The sound will absolutely be reduced, but possibly not by as much as you'd want. The amount of sound reduction is specific to your house and the perception of "enough" is highly personal.

I'd strongly recommend reading the first post to this thread: Soundproofing Master Thread - Post 1 since it gives an overview of the elements you'd be looking at. In particular, I STRONGLY recommend reading the linked articles because they are truly excellent and describe things far better than I could. In fact, I'll link to them here, too:

Advice from Anthony Grimani (PMI) - Soundproofing 101: How to Keep Your Home Theater Quiet
Advice from Ted White (Soundproofing Company) - 4 Elements of Soundproofing

They are not at all long and cram tons of essential knowledge in one place. If you have time, then start reading some of the articles here: Soundproofing 101. That'll fill in some gaps.


----------



## SteveS78

How low would my ceiling be lowered if I choose to decouple it from the joists?


----------



## kmhvball

SteveS78 said:


> How low would my ceiling be lowered if I choose to decouple it from the joists?


There are several ways to do this... if you use Sound Clips & Hat Channel... I think there are two ways... 

The first way is about 2 1/8" lower.. you attach clips directly to sub-floor joist, and run hat channel perpendicular.

The second way, is more labor intensive, but you could likely do for about 1" lower... you would have to install 2x4 cross bracing 'up' in between the joists with teh bottom edge of the cross-bracing about 1" HIGHER than the bottom edge of the Joist. Then, when you install the 'clip', the 1 1/8" deep clip, only 1/8" extends beyond the joist bottom. Then it is just the 7/8" hat channel depth.

I have seen other applications where people install entire new Joists in between their existing joist. This could likely be as little as 1/4" lower, but requires somwhere to rest the joists on (i.e., if building room within room, you would have the 'new walls', which the joist could rest on). If I am not mistaken, the guy who started this thread may be doing this method - you might take a look at his build (Ganroth, I think it is called the Phoenix Build).


----------



## SteveS78

Thanks for the info. Does it make a difference as to what is above my basement in terms of making this decision? Right above where the screen and speakers will be is our family/great room that has a cathedral ceiling. Nothing is above that. The bedrooms are above the unfinished area of the basement with a floor in between of course. The floor of the family/great room is carpet and the kitchen is also directly above part of the finished area, just a little bit to the right of where the screen and speakers will be. It has a plastic laminate floor. Hopefully those surfaces (carpet and laminate) will help a little bit with sound.

I just looked last night, the pink R13 Owens Corning insulation is in the walls and they have stuffed that same insulation VERY thickly (10 inches) between the joists. It looks very sufficient. Its so thick its almost busting out in a few spots. Haha. Also, he just insulated the ceiling area above the speakers and screen. The area to the right of that is going to be a play area for the kids (just an open area), and I have chosen not to insulate that. I am sure some sound would escape there. We also have a stairway that already has a finished drywalled ceiling with the door to the upstairs. I am sure some sound would escape there too.


----------



## Nightlord

SteveS78 said:


> How low would my ceiling be lowered if I choose to decouple it from the joists?


Depends on how you do it. If you run new decoupled joists from the side walls, you can manage fractions of an inch depending on how accurate/brave you are with the measurements. Myself I lost about an inch, but I also went for more drywall layers than originally.


----------



## kmhvball

kmhvball said:


> There are several ways to do this... if you use Sound Clips & Hat Channel... I think there are two ways...
> 
> The first way is about 2 1/8" lower.. you attach clips directly to sub-floor joist, and run hat channel perpendicular.
> 
> The second way, is more labor intensive, but you could likely do for about 1" lower... you would have to install 2x4 cross bracing 'up' in between the joists with teh bottom edge of the cross-bracing about 1" HIGHER than the bottom edge of the Joist. Then, when you install the 'clip', the 1 1/8" deep clip, only 1/8" extends beyond the joist bottom. Then it is just the 7/8" hat channel depth.
> 
> I have seen other applications where people install entire new Joists in between their existing joist. This could likely be as little as 1/4" lower, but requires somwhere to rest the joists on (i.e., if building room within room, you would have the 'new walls', which the joist could rest on). If I am not mistaken, the guy who started this thread may be doing this method - you might take a look at his build (Granroth, I think it is called the Phoenix Build).


I must have been sleepy... the Clip + Hat Channel is 1 1/8" drop if installed directly on floor joist.

Doing the Cross Bracing, you run the channel parallel to floor joist, and the recommended gap is 1/2". So, you 'gain' 5/8" for that extra labor/ time & material. I think doing a room within a room, could likely even bring that 1/2" lower.


----------



## onyxbfly

SteveS78 said:


> How low would my ceiling be lowered if I choose to decouple it from the joists?


If you decouple your ceiling with hat channel and clips and use double dry wall with green glue your ceiling will be lowered by 2".


----------



## ctviggen

Nightlord said:


> Depends on how you do it. If you run new decoupled joists from the side walls, you can manage fractions of an inch depending on how accurate/brave you are with the measurements. Myself I lost about an inch, but I also went for more drywall layers than originally.


Isn't each layer of fire-rated drywall 5/8 inch thick? If you had two layers, you'd be at 1-1/4 inches, and that's with no clearance from the ceiling. Add half an inch for clearance, and you're at about 2 inches lost.


----------



## granroth

Okay, let's start with a "typical" ceiling consisting of one sheet of 1/2" drywall directly screwed or nailed into the joists. That's our baseline.

Let's now replace that 1/2" drywall with 5/8" Type X drywall. Net loss is 1/8" and it gives us marginally better soundproofing.

Let's add another sheet of 5/8" Type X drywall. Now we have Joist + 5/8" DW + 5/8" DW, giving us a net loss of 3/4". The soundproofing is now notably better than the baseline.

Why not add a layer of Green Glue in between the drywall? The thickness of the material shouldn't change in any easily measurable way (save using a micrometer) but the sound reduction will be noticeably better than even the standard double layer.

But now we'll kick it up a notch and decouple, in addition to adding mass. This is where the true bang for the buck kicks in.

The least amount of lost vertical space would be to create floating joists between your existing ones -- but this does assume that you also have floating walls (a "room within a room" construction method). You'll lose around 9" in each dimension for width and length of the room. In theory, you could create your new joists and new walls to be maybe 1/8" below your existing joists. That would give you a net loss of 7/8". That would assume some pretty straight existing joists, though, and that's not been my experience. It's probably safer to assume around 1/4" clearance, which creates a net loss of 1". This will be your close-to-ultimate soundproofing solution (and not just for the ceiling).

You could get a similar amount of lost vertical space by offsetting clips and channels into the existing joists using blocking. See this illustration from the Soundproofing Company:










This gives you roughly identical vertical loss as the floating joist solution. It has very similar soundproofing capabilities to the floating joist solution, albeit costing a bit more and not addressing the walls or flanking.

If all that seems to finicky, then the standard solution is to use 7/8" clips and channels with the two layers of 5/8" Type X drywall (and Green Glue). Net loss there is 1-5/8". It has the same excellent soundproofing abilities as the "blocking" solution, but far easier to install and only giving up a maximum of 5/8" more.


----------



## Nightlord

ctviggen said:


> Isn't each layer of fire-rated drywall 5/8 inch thick? If you had two layers, you'd be at 1-1/4 inches, and that's with no clearance from the ceiling. Add half an inch for clearance, and you're at about 2 inches lost.


We only have 1/2 inch drywall here (12 or 13mm ) afaik, and I've never heard of it being fire-rated or not. But most of all, I had a layer of wooden beams perpendicular to the joists in the original ceiling that I didn't do now, so I saved a little space.


----------



## ctviggen

Nightlord said:


> We only have 1/2 inch drywall here (12 or 13mm ) afaik, and I've never heard of it being fire-rated or not. But most of all, I had a layer of wooden beams perpendicular to the joists in the original ceiling that I didn't do now, so I saved a little space.


Sounds good. This is fire rated drywall:

Article about fire rated drywall

It's commonly used for sound transmission since it's heavier than normal 1/2 inch drywall. The 1/2 inch is about 1.6 pounds/ft^2 (square foot) and the 5/8 inch is 2.2 pounds/ft^2. A 4x8 foot sheet of 1/2 inch is about 51 pounds while the 5/8 inch is 70 pounds. I was used to carrying the fire rated, 5/8 inch stuff around, then picked up a 1/2 inch sheet and couldn't believe how light it was.


----------



## Wolverine22

Does anyone have a suggestion for how to attach a baffle wall to a soundproofed room with clips and hat channel on the walls and ceiling? If I attach it to the hat channel will it cause a problem with room acoustics?
Thanks


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## smuggymba

I have a media room in a completed house (studs and drywall). What are my options of soundproofing the media room? 

Can I just put another layer of drywall on top of existing drywall using super glue? My room is 12ft so I don't want to lose too much of width.

Do I have to remove the current drywall to use the clips solutions?


----------



## granroth

smuggymba said:


> I have a media room in a completed house (studs and drywall). What are my options of soundproofing the media room?
> 
> Can I just put another layer of drywall on top of existing drywall using super glue? My room is 12ft so I don't want to lose too much of width.
> 
> Do I have to remove the current drywall to use the clips solutions?


Using clips absolutely requires removing your current drywall. Putting clips on top of drywall creates a "triple leaf" effect, which would make things notably WORSE rather than better.

If removing the current drywall isn't an option, then yes, installing another layer of drywall will make a difference. Get 5/8" Type X (fire rated) drywall; apply a layer of Green Glue to the back; and screw it into the studs on top of the existing drywall. That'll be notably better than what you have now.

But... if space is the primary issue and not cost or effort, then I'd strongly recommend removing the existing drywall. It's probably 1/2", which is quite a bit worse than 5/8" Type X. With the drywall down, you can also put in R-13 insulation between the studs. Then, you can also install clips and channels, which won't take up a huge amount of space (and could take up even less if you recess some support baffles -- see a few posts above this). The combination of all that would be worlds better than just adding one layer of drywall + GG.


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## AeroA1

*SPL vs Loudness*

What is measured by instruments is SPL [Sound Pressure Level, 0db = 0.0002 dynes per square CM, usually defined at 1kHz.]. Loudness is what we perceive by hearing, and it is not at all linear with SPL. To confuse the two is a serious mistake.

0.0 dBspl can be heard only by the most sensitive ear in an anechoic chamber.

The logarithmic dB scale relative to power is approximately as follows. 3dB is twice and 10 dB is 10 times. And, for example, 13 dB is 20 times, etc.

On a quiet day the average SPL outside might be 40 dB.

An SPL of 110 dB is considered the threshold of pain, and anything much above that [eg, rock concert] can risk damage to hearing.

A quoted post [somewhere herein] gives the range of sound on a soundtrack as ranging from 22 dB to 105 dB, and I'm pretty sure this is SPL, but was confused with 'Loudness'.

A lot of lab tests have been run on a persons perceived loudness, eg, Fletcher-Munson curves, since modified, as it's a complicated problem to quantify. So to avoid a lot of physics involving air temp and density, sound frequency, etc, I use the following rules of thumb.

3 dB increase in SPL is about the smallest change a person can reliably detect.

And a 10 dB SPL increase is what it takes for the sound to be perceived as twice as loud. YMMV.

When listening to music, I use the "Vacuum Cleaner Rule". If I am vacuuming my home theater whilst listening to music and I can still hear the vacuum cleaner, I turn up the volume.

Still, you should avoid SPLs above 110 - 113 dB. If it starts to hurt or go non-linear, turn off the vacuum cleaner and readjust.

Bill Wood
AeroA1


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## AeroA1

kmhvball said:


> There are several ways to do this... if you use Sound Clips & Hat Channel... I think there are two ways...
> 
> The first way is about 2 1/8" lower.. you attach clips directly to sub-floor joist, and run hat channel perpendicular.
> 
> The second way, is more labor intensive, but you could likely do for about 1" lower... you would have to install 2x4 cross bracing 'up' in between the joists with teh bottom edge of the cross-bracing about 1" HIGHER than the bottom edge of the Joist. Then, when you install the 'clip', the 1 1/8" deep clip, only 1/8" extends beyond the joist bottom. Then it is just the 7/8" hat channel depth.
> 
> I have seen other applications where people install entire new Joists in between their existing joist. This could likely be as little as 1/4" lower, but requires somwhere to rest the joists on (i.e., if building room within room, you would have the 'new walls', which the joist could rest on). If I am not mistaken, the guy who started this thread may be doing this method - you might take a look at his build (Ganroth, I think it is called the Phoenix Build).


Sir,

I am not sure this is the place to post this but the problem I have in my HT is air conditioner noise, mostly mechanical rather than due to air flow. Short of turning it off, I can't figure any solution. I can treat the inside of flow tunnels/ducts, but with what and it's a fairly short run.

I've considered a diffusing effect by taking the air output [the source of the noise] and splitting it into maybe 3 paths [I have a little room, but not much] with some sound absorbent material on the inside surfaces - or something. Any effect on air flow must be considered.

Any thoughts world be appreciated.

Bill Wood
AeroA1


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## kmhvball

I am not real familiar with options, but using a Dead Vent might be an option, where you snake around flex duct in a 'box' (either outside the theater or in the soffit)... the 'snaking around' will likely require a larger diameter than you currently have as it reduces the air flow. 

I went a different route all together and installed a Mini-Split AC/Heating unit, so, I didn't do too much research on the incoming air supply sounds.


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## granroth

AeroA1 said:


> I am not sure this is the place to post this but the problem I have in my HT is air conditioner noise, mostly mechanical rather than due to air flow. Short of turning it off, I can't figure any solution. I can treat the inside of flow tunnels/ducts, but with what and it's a fairly short run.
> 
> I've considered a diffusing effect by taking the air output [the source of the noise] and splitting it into maybe 3 paths [I have a little room, but not much] with some sound absorbent material on the inside surfaces - or something. Any effect on air flow must be considered.


The gold standard solution for this is to create a Dead Vent as kmhvball mentioned. Here's a very good description of what that entails: http://www.soundproofingcompany.com/soundproofing101/the-dead-vent/

That link also talks about some of the concepts that that solution encompasses. I'm guessing that a dead vent might not be a feasible solution for you, so the next level is to look at the other aspects of the above design.

In particular, you'll ideally want to eliminate straight runs as much as possible and to essentially force the sound waves to run into absorptive paths. Using flex duct in a "snake" pattern running through insulation accomplishes this very well. The flex duct also eliminates vibration noises that can travel though rigid ductwork.

If using rigid (mostly straight) ductwork is required, then you can get decent results by lining the ducts with "duct board". Rigid ducts tend to be custom sized on installation, though, so there's a good chance that you won't have the space to work with.

(More dead vent discussion can be found here: http://www.avsforum.com/forum/19-de...-construction/1327968-soundproof-ducting.html)


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## cgott42

I have a HT in the basement, I'm not concerned with sound leaking into the other part of the basement, I just want to make sure it doesn't get upstairs. 

In particilar the LFE. The wall I made separating the HT from the rest of the basement is a double wall - with approx. 9" of space in between (i.e. 3.5" for each 2x4 (filled with R-13) + 2" of air gap.)

I'd like to have the air from the rest of the basement be the "supply" for air into the HT. I have an 8" in line fan (also is 8" in length).

Can I simply bore an 8" hole near the floor from the HT out to the basement, and just rest the fan there?

What would this do to my sound isolation?


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## granroth

cgott42 said:


> I have a HT in the basement, I'm not concerned with sound leaking into the other part of the basement, I just want to make sure it doesn't get upstairs.
> 
> In particilar the LFE. The wall I made separating the HT from the rest of the basement is a double wall - with approx. 9" of space in between (i.e. 3.5" for each 2x4 (filled with R-13) + 2" of air gap.)
> 
> I'd like to have the air from the rest of the basement be the "supply" for air into the HT. I have an 8" in line fan (also is 8" in length).
> 
> Can I simply bore an 8" hole near the floor from the HT out to the basement, and just rest the fan there?
> 
> What would this do to my sound isolation?


That's a 50sq in hole that you'd put through the wall, so a handy way to approximate the effect would be to open your door about 1/2" and play a movie. Does your open door leak enough noise to concern you? If no, then putting the fan in-line will likely be fine.

If it does concern you after your test, then you'll want to use that in-line fan in a "dead vent". You'll need two of them -- one for supply and one for return. See the post right above yours for some links on that very topic.


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## cgott42

granroth said:


> That's a 50sq in hole that you'd put through the wall, so a handy way to approximate the effect would be to open your door about 1/2" and play a movie. Does your open door leak enough noise to concern you? If no, then putting the fan in-line will likely be fine.
> 
> If it does concern you after your test, then you'll want to use that in-line fan in a "dead vent". You'll need two of them -- one for supply and one for return. See the post right above yours for some links on that very topic.


Thanks, I tried it and they couldn't hear anything upstairs!
Thx


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## cgott42

I saw on the Ted's site instructions for the dead vent. In it he recommends putting a PVC pipe to go through the cavity of the wall to "contain the sound as it travels through the stud wall" (instead of regular metal duct), 








however right afterwards he says it's ok to put a 16"x 16" flare - Why wouldn't this allow sound to escape as the metal flare has a large part of it in the cavity?
Thanks - just trying to understand this better


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## cw5billwade

Because of the DW/GG/DW that your muffler is made out of. You are just looking at a slice of the top view at the room entry (or exit if return) the exit to the adjacent room is 6-8 foot inside the muffler that is insulated and sound does not like making bends. The entire muffler is DW/GG/DW so that is where the sound proofing is since you made a hole in the room's envelope.


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## cgott42

cw5billwade said:


> Because of the DW/GG/DW that your muffler is made out of. You are just looking at a slice of the top view at the room entry (or exit if return) the exit to the adjacent room is 6-8 foot inside the muffler that is insulated and sound does not like making bends. The entire muffler is DW/GG/DW so that is where the sound proofing is since you made a hole in the room's envelope.


Why doesn't sound go up the wall (through flare transition) before ever getting into the muffler?


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## granroth

cgott42 said:


> Why doesn't sound go up the wall (through flare transition) before ever getting into the muffler?


To make sure I'm following you, you are saying that sound could get past the initial two layers of drywall in the theater by going into the 16" x 16" opening and then radiate upwards through the stud bay, between the drywall on the theater side and the dead vent on the other side. I suppose it could also radiate out to the sides, eventually bypassing the dead vent entirely.

Yeah, that is an alternate sound path. I haven't heard any indication that it's a notable one, though. You're going to have the wall sealed, so the sound can't travel through moving air. The wall boards are dense making it difficult for the sound to travel "up" it. That means it'll be traveling via the insulation and doing so at some 90 degree angles. That'll absolutely dampen the sound quite a bit.

I don't know that there are any empirical tests showing exactly how much of an impact all that has. I do know that from an anecdotal standpoint, the dead vent is used quite often and has a great reputation for working very well. That suggests that the sound loss is minimal.

Perhaps @TedWhite or @BasementBob would pop in and give their expert advice on the topic (not sure if 'mentions' work in this version of the forum)...


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## cgott42

granroth said:


> To make sure I'm following you, you are saying that sound could get past the initial two layers of drywall in the theater by going into the 16" x 16" opening and then radiate upwards through the stud bay, between the drywall on the theater side and the dead vent on the other side. I suppose it could also radiate out to the sides, eventually bypassing the dead vent entirely.
> 
> Yeah, that is an alternate sound path. I haven't heard any indication that it's a notable one, though. You're going to have the wall sealed, so the sound can't travel through moving air. The wall boards are dense making it difficult for the sound to travel "up" it. That means it'll be traveling via the insulation and doing so at some 90 degree angles. That'll absolutely dampen the sound quite a bit.
> 
> I don't know that there are any empirical tests showing exactly how much of an impact all that has. I do know that from an anecdotal standpoint, the dead vent is used quite often and has a great reputation for working very well. That suggests that the sound loss is minimal.
> 
> Perhaps @TedWhite or @BasementBob would pop in and give their expert advice on the topic (not sure if 'mentions' work in this version of the forum)...



Yep that's what I mean, so if the between wall and dead vent loss is negligible m then likewise PVC would not be needed either
Again, just trying to understand


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## BasementBob

cgott42 said:


> Why doesn't sound go up the wall (through flare transition) before ever getting into the muffler?



Two thoughts:


#1 ) The muffler area is a six sided box with two holes, one for air in, and one for air out.


#2 ) The linear slot vent diffuser is flush with the drywall, but the drywall will be stronger if there are sill framing (horizontal 2x4's, the same size as the studs, blocking the vertical wall cavity, flush with the top and bottom of the drywall cut out for the linear slot vent diffuser. A side effect of this is that it will stop some of the sound from going up the wall. The sill framing can be lined with duct liner on the airflow side.


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## Potatogod93

Often in build threads I see soundproofing compared to a fishtank as sound leaks like water. I have to question this analogy because the sound that is stopped from passing won't flow to a leak point the same way water will, right? It makes it seem like if everything isn't done perfectly then it will not work. 

This leads me to my question. I am trying to gather information for my build of which I am close to starting and on soundproofingcompany.com solutions #4 and #5 is what I was considering doing with my proposed space. However, I will not be able to do this over the entire room; 2 joists have HVAC runs, 1 has a water pipe that I think I will be able to work around and then the back of the room has a HVAC trunk i have to contend with. Without being able to do a solution #4 or #5 to then entire room would it still help me with most of the room done that way or should I just do more of something along the lines of #3 ?


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## AlphaCentaurus

I would like to know you opinion...

what would be the most efficient soudproofing for the money?

I would like to achieve a reasonable level.

I was thinking insulation between studs, 2 gypsum with green glue...samething for ceiling.

is Green Glue expensive?

My theater will be 8' x 15' x 23'


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## kmhvball

Potatogod93 said:


> This leads me to my question. I am trying to gather information for my build of which I am close to starting and on soundproofingcompany.com solutions [URL=http://www.avsforum.com/forum/usertag.php?do=list&action=hash&hash=4]#4 [/URL] and [URL=http://www.avsforum.com/forum/usertag.php?do=list&action=hash&hash=5]#5 [/URL] is what I was considering doing with my proposed space. However, I will not be able to do this over the entire room; 2 joists have HVAC runs, 1 has a water pipe that I think I will be able to work around and then the back of the room has a HVAC trunk i have to contend with. Without being able to do a solution [URL=http://www.avsforum.com/forum/usertag.php?do=list&action=hash&hash=4]#4 [/URL] or [URL=http://www.avsforum.com/forum/usertag.php?do=list&action=hash&hash=5]#5 [/URL] to then entire room would it still help me with most of the room done that way or should I just do more of something along the lines of #3 ?


I assume you are referring to #4 & #5 of the "Ceiling" soundproofing... 

Part of the benefit from #4 /#5 , i.e., drywall on the sub-floor, is that it helps with sound coming 'into' the theater. I would think that having it in most areas would help the footfall in those areas. I had a few similar issues, so, I went with #5 for my theater room. I did pull out the hard metal hvac pipes, and replace with Flex Conduit, which allowed me to place it on those sub-floors, and the flex conduit is suppose to help with sound getting upstairs as well. 

I went with #4 in a downstairs bedroom, which is directly below my master bedroom. 

The drywall on the sub-floor is on, the clips & channel are hung, and Drywall is supposed to start tomorrow. 

Net, I HOPE it works... I'll tell myself it does regardless!!


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## BasementBob

Potatogod93 said:


> Often in build threads I see soundproofing compared to a fishtank as sound leaks like water. I have to question this analogy because the sound that is stopped from passing won't flow to a leak point the same way water will, right? It makes it seem like if everything isn't done perfectly then it will *not work*.


 
It would be more accurate to say that a $100,000 soundproofing job with a small defect, may be less effective than a $10,000 soundproofing job with no defects.
By way of example, there was a recording studio that was made out of two very thick six sided prefab concrete rooms, one inside the other mounted on precisely engineered springs. A broom handle fell between the two, bridging the gap, and what had been a 100dB separation dropped to a 50dB separation. They removed the broom handle and isolation was restored. 
In our world, the most common example is shorting clips (resilient bars or acoustic hangers, where the mounting screws go right through the clips and into the stud), when installed by contractors who don't actually know why they're doing it or what attention to detail is required.


----------



## granroth

AlphaCentaurus said:


> I would like to know you opinion...
> 
> what would be the most efficient soudproofing for the money?
> 
> I would like to achieve a reasonable level.
> 
> I was thinking insulation between studs, 2 gypsum with green glue...samething for ceiling.
> 
> is Green Glue expensive?
> 
> My theater will be 8' x 15' x 23'


The bang for your buck levels of soundproofing goes in this order (IMO): Decoupling, Mass, Absorption, Damping

Doubling up on drywall is adding Mass. Insulation between studs is adding Absorption. Putting Green Glue between the drywall adds Damping. So far, so good.

But you're missing Decoupling, which is going to give you far greater gains than Absorption (alone) and Damping. You'd need two buckets of Green Glue for a theater your size, which would run you about $550 (give or take, depending on where you get it from and where you live). If money needs to be strictly budgeted for this, then I'd spend the money decoupling the room before I'd spend it damping the drywall.

Personally, I'd strongly suggest doing all four elements to truly repeat the benefits of them all working together. If you do drop one, then drop the Green Glue and spend that money decoupling the walls and ceiling.


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## BasementBob

granroth said:


> If you do drop one, then drop the Green Glue and spend that money decoupling the walls and ceiling.


 
Can you dig up two STL charts to verify that assertion ? (two walls of same mass and approximately same size cavity, one decoupled but no green glue, the other with green glue but no decoupling, and possibly a third with both decoupling and green glue)
Green Glue is pretty good at reducing the resonance dip, which may be more important than other factors.
[I don't recall off hand the STL chart's values for these specific situations]


----------



## granroth

It is very difficult coming up with comprehensive tests comparing Green Glue with the rest of the components. The NRC didn't test it at all, likely because their tests pre-dated Green Glue. I'm also a little loath to directly compare STL numbers when we don't know if the tests were done in compatible ways. Still...

The Green Glue company did a comparison of Green Glue vs resilient channel (along with one using Green Glue + resilient channel) here: http://www.greengluecompany.com/sites/default/files/Green_Glue_Vs_Resilient_Channel_1.pdf

DW+DW + 2x4 w/ Insl + Resilient Channel + DW + DW = STL 55
DW + GG + DW + 2x4 w/ Insl + DW + GG +DW = STL 52

Those numbers don't tell the full story because decoupled rooms, as you say, will have a dip at the low frequencies and that can make a perceptible difference. That comparison is odd, regardless, since it assumes a double layer of DW on the "outside" of the room, which is rarely done with home theaters. I would guess (with no proof) that the STL value of only one layer of GG would be notably lower.

Also, they are comparing against resilient channel, which while inexpensive, is thoroughly frowned upon in the modern soundproofing realm. Clips + Channel are touted as the way to go for low profile decoupling. Here's an example of that in play: http://www.acousticalsolutions.com/test-results-for-whisper-clip

DW + 2x4 w/ Insl + Clip + Channel + DW + DW = STL 61

That test doesn't show the expected notable drop in the low frequencies, though, which is a little odd.

On a less controversial note, let's look at the NRC test TL-93-271, with a double stud wall configuration: http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir693/ir693.pdf

DW + 2x4 w/ Insl + air gap + 2x4 w/ Insl + DW + DW = STL 62

A double stud wall gives the best performance, with the lowest cost... if you do the work yourself and don't mind losing the most space of all options. If I'm answering the "bang for your buck" question (independent of other factors), then I'll suggest a double stud wall setup nearly every time.

Of course, I've LOVE to see numbers for this setup:

DW + 2x4 w/ Insl + air gap + 2x4 w/ Insl + DW + *GG* + DW = STL ???


----------



## BasementBob

Granroth:
I was looking for the STC charts (TL graph 80hz to 5000hz, with unofficial data from 25hz to 10khz), not the single STC numbers.


Any comparisons would best be done from Green Glue's website's Test Data. (although if no pairs were available there, I would have been happy with NRC charts for the corresponding result)


The best pair I could find there were:
Report OL08-0324.pdf
aka "5/8" Drywall 
5/8" Drywall 
Wood 2" x 4" Studs // 16" o/c 
Green Glue Clip + Hat Channel
R19 Fiberglass
5/8" Drywall 
5/8" Drywall"
on http://www.greengluecompany.com/tes...tid=All&field_test_data_page_products_tid=159


vs


Report OL05-1049.pdf
aka "5/8" Drywall 
Green Glue Compound (2 tubes/sheet)
5/8" Drywall 
Wood 2" x 4" Studs // 24" o/c 
R13 Fiberglass 
5/8" Drywall 
Green Glue Compound (2 tubes/sheet)
5/8" Drywall"
on
http://www.greengluecompany.com/tes...tid=All&field_test_data_page_products_tid=158


which should be two fairly similarly priced walls (same drywall, same wood studs),
a) one with green glue and thinner insulation and thinner wall cavity, vs
b) one without greenglue but with clips and more insulation and thicker wall cavity


and the difference is huge at 100hz (11dB difference, namely 26dB vs 37dB) in the bass in favour of the clip wall.
The coincidence dip at 2500hz on the clip wall isn't important, given the transmission loss of that wall is still over 60dB between 500hz and 5000hz.




But as expected, the clips have a deeper resonance dip. If you scroll down to the unofficial results, 31.5hz to 63hz:
clips: @31hz 25dB, @40hz 17dB, @50hz 20dB, @63hz 29dB, @80hz 35dB
green: @31hz 27dB, @40hz 24dB, @50hz 26dB, @63hz 21dB, @80hz 23dB

If you open each report PDF, and scroll down to page 2 in each, the graphs are difficult to compare as graphs, but the right hand chart of frequency and transmission loss is easy to compare.




My conclusion is
a) if the home theater builder is elderly and watches a lot of drama (loudest 63hz to 2khz), then the clip wall is best
b) if the home theatre builder is young and watches a lot of action movies (loud 20hz to 50hz), then the green glue wall might be a better choice.


----------



## granroth

Bob, I'm never going to argue with you when it comes to recommendations related to acoustics since you have forgotten more than I'll ever know... but that doesn't mean I won't raise a few points 

The wall assembly that I'd like to compare to OL05-1049 would be the NRC TL-93-283. It also uses double layers of 5/8 Type X (16mm) on both sides and has the studs 24" OC (610mm), but is a double wall. It has an overall STC of 69 compared to the Green Glue wall's overall of 55. Indeed, if you look at the upper frequencies, the double wall destroys the Green Glue wall with differences @ 500Hz of 70dB to 58dB all the way up to @ 5000Hz of 91.5dB to 70dB.

But right, those are all upper frequencies and Green Glue shines in the lower frequencies. Unfortunately, the NRC doesn't show the unofficial values so I had to run them through Wolfram Alpha. That gave me a best fit linear curve of 0.253741 x+15.0635. I'm assuming linear if only because the graph certainly looks linear at that point. Yeah, that could very well be a bad assumption. Anyway, if we add these results to the set so far:

clips: @31hz 25dB, @40hz 17dB, @50hz 20dB, @63hz 29dB, @80hz 35dB
green: @31hz 27dB, @40hz 24dB, @50hz 26dB, @63hz 21dB, @80hz 23dB
double: @31hz 23dB, @40hz 25dB, @50hz 27dB, @63hz 32dB, @80hz 37dB

So the linear curve calculation @31hz is lower than even the clips, which seems highly unlikely. I can't say I'd trust that the curve is that accurate at two clicks past the last measured data point. @40hz (one click) and @50hz (measured), it's still mildly in the lead. Above that and it's solidly in the lead.

And one final thing -- I still don't think that OL05-1049 is representative of what you'd see in a typical home theater. It assumes double drywall plus Green Glue on the OUTSIDE of the theater. I'm sure there are some theaters that have done that but, honestly, in all of the many theaters I've seen here on AVS Forum, I can't remember a single one that did. Plus cost-wise, we're now looking at $1100 or so for Green Glue. If that's now my budget, then I'd look at doing double walls or clips+channel PLUS one layer of Green Glue... which is the canonical example of what most people do use and are loving.


----------



## BasementBob

granroth said:


> Bob, I'm never going to argue with you when it comes to recommendations related to acoustics since you have forgotten more than I'll ever know


We're all but babes in the lap of Brian R @ Green Glue, and others.
And I'm not an expert. I merely spent a few years sitting at the internet feet of giants, some during the years they figured things out themselves with preliminary research, and buying every book they recommended.




granroth said:


> but that doesn't mean I won't raise a few points


 Good.




granroth said:


> green: @31hz 27dB, @40hz 24dB, @50hz 26dB, @63hz 21dB, @80hz 23dB
> clips: @31hz 25dB, @40hz 17dB, @50hz 20dB, @63hz 29dB, @80hz 35dB
> double: @31hz 23dB, @40hz 25dB, @50hz 27dB, @63hz 32dB, @80hz 37dB
> 
> 
> So the linear curve calculation @31hz is lower than even the clips, which seems highly unlikely.


Green, narrowest between two leafs, resonance dip around 63hz. (flipping through NRC should say if that's normal)
Clips, mid distance between two leafs, resonance dip around 40hz
Double, largest distance between two leafs, resonance dip around 31hz.


I'd bet there are more than a few theatres with green glue on the outside leaf of walls.
I'd bet there are few theatres with green glue on the floor above.
Ted White would have instinctive stats better than my guess.


I never really thought of soundproofing from a $ point of view, within $ reason, since integration difficulty and engineering tend to dominate my planning.
I thought of it as an engineering problem. How much TL at which frequencies do you need, and then which of the NRC walls/ceilings would accomplish that -- invariably followed by a reduction in required TL because it's impractical for some reason or another to build the first choice assembly and a revisit to the NRC charts to find a nth choice assembly that is acceptable (or flanking limitations making more 'wall' a waste).


----------



## AlphaCentaurus

Tanks a lot for all this info.

Since I would like to save space I would not do a double wall...I would like to, but space is more important to me.

A tought about this solution: DW + GG + DW + 2x4/insulation + DW (for interior walls) becuse I thinks it is the most efficient, simple to construct and saves the most space.

Sure GG is not cheap, but double walls too since you double all 2x4 and need clips to fix them to trusts...

I looked at the Green Glue site and the vibration absorbtion is excellent.

Opinions, comments and your experience is so valuable to me so I don't make an error while building.


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## kmhvball

AlphaCentaurus said:


> Since I would like to save space I would not do a double wall...I would like to, but space is more important to me.
> 
> A tought about this solution: DW + GG + DW + 2x4/insulation + DW (for interior walls) becuse I thinks it is the most efficient, simple to construct and saves the most space.


In Ceiling Installs when people want to save space and still decouple, they used Blocking between the Joists, and you can add Clips & Channel for as little as 1/4" additional space. I haven't seen reference to this in walls, but seems like it might work. The consideration might be to the impact on the insulation and if adequate space is still available. 

Another option. is a 2x6 Top & Bottom Plates, and staggering 2x4' vertical studs (one stud on 'left' of plate, the next stud on 'right' of plate, and repeated.) This takes another 2" of space and provides some decoupling benefits.


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## AlphaCentaurus

Yes staggered walls are an option but low frequency vibration is not manages well since coupled by the 2x6..I think 
If Green Glue is too expensive I'll go with channels and clips...maybe this way use only one DW ?

DW + channel/clips + 2x4/w insulation + DW (interior walls)


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## granroth

BasementBob said:


> [...]
> By way of example, there was a recording studio that was made out of two very thick six sided prefab concrete rooms, one inside the other mounted on precisely engineered springs. A broom handle fell between the two, bridging the gap, and what had been a 100dB separation dropped to a 50dB separation. They removed the broom handle and isolation was restored.


This is a great example of a small defect making a huge impact on the overall effectiveness of a soundproofing strategy and why the details absolutely matter. Is this particular case detailed somewhere where I can see the specifics? After hearing that story, I find myself worried about the decision I made constructing my theater door.

This is from Gervais' book:



Rod Gervais (Home Recording Studio - Build it Like the Pro - p93) said:


> I’ll let you know right now that this is one place I don’t worry about maintaining the separation of wall assemblies with the frames, even when using totally separated assemblies. ... As I noted above, tests have proven that a through jamb does not effectively lessen the total isolation value of a wall assembly to any great degree. So don’t worry about any minuscule amount of isolation you may lose. Just build the frame straight through the cavity.


With that in mind, I created a door jamb that was between 3/4" and 1-1/4" thick and spanned both of my decoupled walls -- it's one piece and screwed into both walls. I felt pretty good about that.

But now let's apply the lesson of the recording studio you refer to. A broom handle bridged the gap between the two walls and resulted in a 50dB drop in separation. Wouldn't my door jamb be even more of a bridge than a loose broom handle? If a broom handle can result in a 50% drop, then maybe a solidly attached bridge would result in even more!? That wouldn't be "minuscule" by any measure.

So... to ease my worried mind, I'm trying to track down specifics on both this recording studio example as well as what tests show that through jambs are okay.


----------



## BasementBob

granroth said:


> With that in mind, I created a door jamb that was between 3/4" and 1-1/4" thick and spanned both of my decoupled walls -- it's one piece and screwed into both walls.


 
If your 'decoupled walls', are mounted on the same floor below, or mounted to the same 'floor above' (aka ceiling joists) possibly even with isolation clips (sway brace) you were supposed to use, then Rod's advice is correct (as it always is) and I've heard it verified elsewhere. 




If you made your room with a floated floor (engineered by a professional using pucks or springs), and free ceiling, and even the ductwork has flexable duct connectors, then I've often considered making airlock/companionway doors without the jamb crossing between the two, but having a quarter inch separation, and fabric covering the walls and ceiling of the companionway and carpet covering the 'floor' portion. If any of the walls are outside walls, then it's not immediately obvious where to put vapor barrier (obviously not at the door as that won't be an outside wall, but as you go around the room). Some have used rubber seals around gaps like this.




As for the studio
please see
http://www.galaxystudios.com/about-us/


specifically




> So, we started to look for highly-qualified industrial builders. This is how we met with Eric Desart of the Gerber Group and later on Gerrit Vermeir, professor at the Universty of Leuven, already renowned authorities in their fields of expertise. They explained our wishes were far beyond anything that had been achieved until then. Nevertheless we believed it was worth trying. They developed industrial solutions to achieve the unheard insulation value of plus 100 dB between 2 rooms, with a visual connection and a distance between the units not exceeding more than 60 cm


 
and


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## granroth

BasementBob said:


> If your 'decoupled walls', are mounted on the same floor below, or mounted to the same 'floor above' (aka ceiling joists) possibly even with isolation clips (sway brace) you were supposed to use, then Rod's advice is correct (as it always is) and I've heard it verified elsewhere.


So it's really the extreme lengths that Galaxy Studios went through that required that all components work flawlessly together, thus allowing a simple connection to make a drastic impact? Maybe I can look at it from the perspective that my shared slab floor that spans the walls already conducts a massive amount of sound and so from a percentage point of view, the spanning jambs barely register?

(and, indeed, whilst the entire theater and attached house is on the same slab, my theater ceiling is on floating joists completely disconnected from the rest of the house)


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## granroth

*Applying Putty Pads*

Putty pads are a very typical way to seal off outlet boxes and are part of many a theater build. Curiously, though, the instructions I found for using them were sparse at best and non-existent at worst. I got the impression that it should be "obvious" how to install them. Well... it wasn't for me, and it might not be for others. I finally got a method that worked well for me after maybe four outlet boxes and figured that I'd describe that method here.

I make no guarantee that this is the "right" way to do it. In fact, if I'm clearly doing something wrong, don't hesitate to correct me.

*Baseline*

My outlet boxes are standard Carlon single-gang adjustable boxes, which are somewhat ubiquitous in this application. I needed 1-1/4" clearance for the two layers of 5/8" drywall that will be installed soon.

The putty pads came from the Soundproofing Company at roughly $5 each. That's a pretty standard price for these. I don't see any brand name associated with them. Hilti makes their own brand of putty pads, which may be available locally in some areas. You may need to buy them in sets of 20, though, which can get expensive. The putty pads I used had a plastic release sheet on each side. Hilti pads appear to be individually packaged. I've seen some suggestions that using readily available "duct seal putty" (found at the big box stores) can also work for quite a bit less money, but I didn't try that.

*Optional Step*

I didn't see this step anywhere, but I noticed that a single square putty pad would leave one side of my outlet extension (the part that extends past the stud) completely uncovered. That may not matter, but since there is physically enough material to cover the entire thing, I made a little effort to do so.

I started by cutting of just over an inch of the putty pad, while it was still covered by the plastic on both sides:










I then removed the plastic from both sides of my cut-off hunk and wrapped it around the extension, making sure to primarily cover the "other" side that won't be covered by the main pad. The pad is quite sticky and moldable, so it easily adheres to the box:










*Applying the Putty Pad*

Covering a three-dimensional object with a two-dimensional pad would normally mean bunching up the pad in the corners quite a bit. I got around this by cutting some slits in the pad to allow me to go around the corners easier. The slits are roughly the depth of the outlet box in and the width of the outlet box high... but I just eyeballed it, since it's not critically important:










That was done with both sides of the plastic still on. I immediately followed this by removing the plastic from one side. I then pressed the pad against the side of the outlet box away from the stud, so that the pad was flush with the front of the box:










This is the time to remove the remaining plastic! Yes, it'll make the manipulating it a lot stickier than if you kept the plastic on, but in my experience with my first guinea pig boxes, it was extremely difficult to remove the plastic once the pad was molded in place.

The top and bottom are simply folded over and pressed in place. The back is also mostly just folded over. The tricky part is to them take the remaining flaps and to mold them into the holes in the back of the box:










The most important part of all of this is to make sure that the cable entrance into the outlet box is fully covered. I accomplished this by wrapping the putty around the cables first, and then pushing the hole mess up into the hole. It covers it up very well:










You may note the exposed area on the bottom of the outlet box. I'm pretty sure that doesn't matter. It is notable that the putty wasn't as stretchy as I thought it would be, based on a video I saw for the Hilti pads. They do stretch a little, but not a lot so don't count on that.

And that's it. I tested the outlets by shining a powerful flashlight from below, behind, and above the box and looked for any light to show through. I also shined it into the box and looked for any light leakage coming out the back. I'm glad I took this step because three of my earlier boxes did have some tiny holes that weren't visible at a glance but were clearly there with the light. Fixing those was easily done by just molding the putty over the discovered holes.

Have fun!


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## BasementBob

Granroth:


a) Shouldn't you apply the putty about half an inch (or 1-1/4" in your case) from the front edge to allow for 1/2 drywall to be flush with the box ?
b) Shouldn't you be wrapping the boxes on five sides first, and then nailing them to the wall ?


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## granroth

BasementBob said:


> Granroth:
> 
> 
> a) Shouldn't you apply the putty about half an inch (or 1-1/4" in your case) from the front edge to allow for 1/2 drywall to be flush with the box ?
> b) Shouldn't you be wrapping the boxes on five sides first, and then nailing them to the wall ?


Yeah, this is what I'm talking about with inadequate instructions. The Soundproofing Company installation PDF does, indeed, show a photo of a box that appears to not only have the gap for the drywall but also have the nails on the outside of the putty. But their own (very sparse) instructions that follow seem to contradict the photo, mostly in step 3:

_3. Starting at side of the box, align the Putty Pad to *front edge of box* and *overlap onto the stud*._

"Front edge" implies no gap and "overlap onto the stud" implies that it's already installed.

I am pretty sure that you don't apply the putty pads before installation not only because I've never seen any instructions or video or photos that stated that (save the one Soundproofing company photo), but also because having used it, I don't think it'd be physically possible.

As far as the gap, though, that one did throw me for a loop for awhile and I'm still not 100% sure about it. In the end, I found some tip online that explicitly suggested even bunching the putty around the front a little bit so that when you put the drywall over it, it compresses it and creates a tight seal from behind. That could suggest putting it back a little and not completely to the edge. Not sure. I guess I'll find out when I install the drywall! I'll update my post with some observations after the drywall goes up and I see how it acts.


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## cw5billwade

Yea you want to trim the DW for a close fit and the putty pads actually wrap up the DW then you use accoustical caulk from the front side. You would have to put a DW strip a little taller than your boxes (not 4x8 sheet) so you could manage this.


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## cw5billwade

Doing it your way actually makes the hole in the DW bigger to accommodate the putty pad you want the smallest hole possible. I have seen folks use putty pads in the box as well.


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## granroth

cw5billwade said:


> Yea you want to trim the DW for a close fit and the putty pads actually wrap up the DW then you use accoustical caulk from the front side. You would have to put a DW strip a little taller than your boxes (not 4x8 sheet) so you could manage this.


and



cw5billwade said:


> Doing it your way actually makes the hole in the DW bigger to accommodate the putty pad you want the smallest hole possible. I have seen folks use putty pads in the box as well.


Hmm... that makes sense. My plan was to cut the hole in the first layer of drywall pretty tight to the putty, so that it even shaves it down just a tad. The next hole would be very slightly bigger and the gap between the drywall hole's edges and the outlet would be filled with caulk.

But yeah, that would result in less drywall (less mass) than a solution that was tighter to the box.

So maybe I can peel the putty back to the stud; cut each layer of drywall to within 1/16 of the outlet box (if possible); and apply a bead of caulk around the box each time. I do wonder what the caulk in the second layer would be backed with -- would it have a tendency to sag, with only more caulk backing it up?


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## cw5billwade

When I did mine there is enough of the gypsm (sp) from the cut edges of the drywall around the box and the hair line gaps to get the caulk in there It is going to stay. Some people get the little foam things they put on water proof outlets and back the outlet cover with them so that is another layer. If putting putty in the box wait until after the inspection (LOL) 

The picture above was my billard room wall that is between my theater. Don't forget the outlet boxes in the adjoining rooms. I didn't have any holes in my theater walls.


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## plissken99

I am about to start a basement build, need to soundproof the ceiling as much as possible. I'm already planning to use those z-clips(?), a double layer of 5/8ths drywall with green goo in between. What insulation can I put between the beams for the highest bang to buck ratio?


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## BasementBob

plissken99 said:


> What insulation can I put between the beams for the highest bang to buck ratio?


Roxul rockwool, Owens Corning fiberglass pink, even that blue jean stuff. If foam it must be open cell with lab tested sound absorption coefficients.
I'm fond of Roxul Safe n Sound, but it doesn't matter.
Any thickness. As long as the sound goes through it (no path around it), it's fine. 2" to 4" is fine.


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## granroth

plissken99 said:


> I am about to start a basement build, need to soundproof the ceiling as much as possible. I'm already planning to use those z-clips(?), a double layer of 5/8ths drywall with green goo in between. What insulation can I put between the beams for the highest bang to buck ratio?


If looking ONLY at the best bang for your buck, then nothing can touch the cheapest 3.5" thick R-13 fiberglass batt insulation you can find. You can often get it for notably less than the big box stores by finding insulation suppliers on Craigslist. It's far far less than the other options.

There are solutions beyond that that will give you better performance, but there's going to be some level of diminishing returns for any other solution. Many do find that increasing their insulation thickness to 5.5" thick R-19 is worth the money, but unless you have "free" insulation, it's usually not worth increasing beyond that.

Actual test data (quite readable, though): http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir766/ir766.pdf


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## plissken99

I think the Roxul stuff will be a nice middle ground. I calculated around $500 worth of it from Home Depot to do the whole job, and I know there are insulation suppliers around where I can likely get it cheaper. The main goal is to stop as much sound as I can from reaching the bedrooms. It is a 2 story house, plus the basement and all bedrooms are on the 2ns floor. So that plus 2 layers of 5/8ths drywall with green goo should do nicely.


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## Dizzy49

Great pics with the putty pads.

Is there a similar guide with pics for decoupling 2x4 frame wall from the ceiling? An Idiots guide would be perfect in the case 

We will be adding wood frame walls 1" in from the concrete walls (concrete walls all around in this room). We'll be using clips/channel for the ceiling. The walls and ceiling will have UltraTouch insulation and two layers of drywall with green glue between.

plissken99, I'm also going to try to put some green glue and a layer of drywall between the joists. I'm going to try one layer, see how it is, and then add a second. I'm doing a small "test" room before I tackle the theater so I can do some practical testing and work out kinks.

At the most, my ceiling would have: GG + DW + GG + DW + UltraTouch (R19 Denim stuff) + Clips/Channel + DW + GG + DW

I'm going a bit overboard since we have wood floors above, and my wife's office is directly above the small room (aka my office) She teaches dance, so she often has the music cranked up and is working out choreography and it generates a lot of noise. We often have music battles, but my speakers are louder


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## cw5billwade

Just use the IB-3 clips to your ceiling joists every 48" for your wall. On the wall parallel to the joist you will have to put nailers in for the clips.

My wall is not against concert but the principle is sill the same. I attached IB-3 clip to the existing wall but you can see the nailer I installed for the IB-1 clips and channel I could have just as easy attached to the nailer which is what you would do.


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## mhutchins

Regarding outlet boxes - I am planning a 3-layer wall with OSB/GG/DW/GG/DW. Would it be possible to mount the outlet box to the OSB before the other layes go up? In this way there would be less of a chance for creating flanking paths to the studs.

I was thinking something like this could be attached with the flange against the face of the OSB and a small block could be glued/nailed to the backside so the side flange could be attached for a stiffer mount. Then putty pads, of course. What do you think?










Otherwise, what do you do for an outlet whose face may be 2-3" proud of the underlying stud?

Mike


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## ClemsonJeeper

Those adjustable boxes are nice for DD+GG directly on studs, but if you add in another layer of drywall or add clips+channel, I found they won't reach through completely.

I plan on using something like this:

http://www.amazon.com/Arlington-Electrical-Outlet-Extender-1-Gang/dp/B000GAQE9A/ref=pd_sxp_f_pt

to extend out the boxes that don't quite lay right.


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## mhutchins

Yah, I looked at flanged boxes, but I was worried the flanges would cause the cover plate to not seal firmly against the drywall. Is this a problem or am I worrying about nothing?

Would these flanged outlets work with a fabric wall if you built a small wooden frame surrounding the outlet to mount the outlet to the frame so it is rigid and sits flush with the fabric?

Mike


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## cw5billwade

they wood work like that but you would have to check local codes.


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## cgott42

I used 2x12 wood to create the walls for a dead vent. If I put a single 5/8" DW and GG between the DW and the 2x12 wood - will the GG work as well as if I had put it between 2 sheets of DW?

The reason that I ask is that I think the 2x12 + 1 sheet of DW gives me enough mass - so I'd rather put the GG between the wood and DW (and if necessary add another sheet of DW for add'l mass) - but this will save me from making a trip to Lowes to get the DW.

thx


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## cw5billwade

normaly just MDF/GG/DW or OSB/GG/DW so 2x12/gg/DW will be fine no need for 2 layers


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## thestoneman

*Soundproofing emergency!!*

My drywall guy put up drywall without insulation! 

In his defense, the wall is not a foundation/exterior wall. It is decoupled and will have DD/GG. 

I am concerned about losing this line of defense...AND I already have the insulation!

Should I tear out the drywall? He didn't put in that much of the wall.


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## ChldsPlay

So if one had to choose between only doing sound proofing or only doing acoustic treatments, which would be the most beneficial?


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## granroth

thestoneman said:


> My drywall guy put up drywall without insulation!
> 
> In his defense, the wall is not a foundation/exterior wall. It is decoupled and will have DD/GG.
> 
> I am concerned about losing this line of defense...AND I already have the insulation!
> 
> Should I tear out the drywall? He didn't put in that much of the wall.


Insulation adds a couple more points to the STL rating. Whether or not they are needed depends entirely on what kind of soundproofing you require. If your requirements matched a score that required the insulation then yes, absolutely pull the drywall and install it. If your requirements do not need it... then I'd just let it be.

FWIW, the decoupling, mass, and damping make a much bigger impact than the absorption that drywall supplies (although decoupling does work somewhat better with insulation due to its effect of "widening" the gap, air flow wise).


----------



## granroth

ChldsPlay said:


> So if one had to choose between only doing sound proofing or only doing acoustic treatments, which would be the most beneficial?


In general, acoustic treatments will always win out, since quite a few people do have treated theaters without a lick of soundproofing and are happy with the results.

Your mileage my vary, though! The entire point of soundproofing is to simultaneously lower the noise floor in the theater and to keep the noise from the theater from bothering others. If your normal environment is noisy, then you may find yourself having to raise the volume of your movies to an uncomfortable degree to hear everything. No acoustic treatments will help at that point. Likewise, if you find that you have to keep the volume lower than you'd prefer because of disruptions with neighbors/kids/others than acoustic treatments won't help there, either.

But if you live out in the boonies where there is no real ambient noise and no amount of noise that you make will matter and you don't have kids, then soundproofing would be somewhat pointless.

Personally, I don't see it as an either/or case. The soundproofing gets my theater's sound floor low enough that I can choose what volume I'm comfortable with and still hear even the quietest scenes, while acoustic treatments will ensure that the sound is delivered as it is intended (also helping to keep one volume level for the entire dynamic range of the movie).


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## plissken99

Quick question. Between 2 layers of drywall and roxul sound insulation, which helps block high frequencies and which blocks low ones?


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## BasementBob

granroth said:


> Insulation adds a couple more points to the STL rating.



The insulation in the wall acts as damping, increasing the resonance frequency's transmission loss.


It shifts the mass-spring-mass system to a lower resonance frequency
It dampens sound waves transmitted through the wall
It dampens lateral standing sound waves in the cavity of the wall.


Note: overfilling with rockwool (aka stonewool) reduces STC. Overfilled defined as fully filled and then stuffing in 10% more.


Here's an interesting tidbit:




> In a speaker cabinet adding damping gives a virtual 1.2 (20%) volume increase.
> Easy measurable in an impedance graph.
> 
> Modes etc are effectively suppressed, especially as you can easily put damping material in the velocity max of the standing wave.
> 
> OK,
> Best results are when you loosely fill the cavity and when you clad the walls of the box with foam or 703 like stuff.
> When you have a standing wave you put a (double) piece of foam (PUR-foam, melamine) in the velocity max.
> Stuffing to much to dense absorption in the box will effectively make the box smaller.
> You see the resonance shift upwards.
> With walls I always learned to use a 60 % filling of loosely stuff, but I don't did research on this myself.
> The stuffing will influence air stiffness causing lower fs and suppress modes storing energy.


----------



## BasementBob

plissken99 said:


> Quick question. Between 2 layers of drywall and roxul sound insulation, which helps block high frequencies and which blocks low ones?


Absorbers cause transmission loss on the order of 0.5 of energy
Walls cause transmission loss on the order of 10,000,000 of energy (70 dB).
Thus absorbers make lousy STC devices by themselves, whereas even a single layer of drywall has an easily perceptible sound transmission loss.


Drywall/stone reflect sound, particularly high frequency.
Wool absorbs sound, particularly high frequency.
Thus if you're trying to get rid reflected sound within the room, drywall would be a poor choice, and wool (glasswool/fiberglass, stonewool/rockwool, open cell foam) would be a good choice.




If you mean instead of individual components, the wall system of {drywall, insulation, drywall}, then the drywall stops most of the high frequency transmission of sound energy through the wall, and the three of them {drywall, insulation, drywall} are a system that together reduces low frequency transmission through the wall.


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## plissken99

Right I was speaking in terms of keeping sound from bugging the rest of the house. Sounds indeed like all the above is a good idea.


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## cw5billwade

thestoneman said:


> My drywall guy put up drywall without insulation!
> 
> In his defense, the wall is not a foundation/exterior wall. It is decoupled and will have DD/GG.
> 
> I am concerned about losing this line of defense...AND I already have the insulation!
> 
> Should I tear out the drywall? He didn't put in that much of the wall.


earlyer in this thread there were some good charts. I know that based on the charts you want to rip it out and put R13 in both of thoes walls. If sound containment is what you want then you need to do it. Even if both walls have DW/GG/DW you are loseing a lot of the dampening


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## thestoneman

cw5billwade said:


> earlyer in this thread there were some good charts. I know that based on the charts you want to rip it out and put R13 in both of thoes walls. If sound containment is what you want then you need to do it. Even if both walls have DW/GG/DW you are loseing a lot of the dampening


I want as much sound containment as possible, but it's not critical. Considering I just have to rip out a bit of drywall, I am going to do it right. Otherwise, I will have done all the other sound abatement procedures for naught. 

Thanks for the feedback everyone.


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## ChldsPlay

granroth said:


> In general, acoustic treatments will always win out, since quite a few people do have treated theaters without a lick of soundproofing and are happy with the results.
> 
> Your mileage my vary, though! The entire point of soundproofing is to simultaneously lower the noise floor in the theater and to keep the noise from the theater from bothering others. If your normal environment is noisy, then you may find yourself having to raise the volume of your movies to an uncomfortable degree to hear everything. No acoustic treatments will help at that point. Likewise, if you find that you have to keep the volume lower than you'd prefer because of disruptions with neighbors/kids/others than acoustic treatments won't help there, either.
> 
> But if you live out in the boonies where there is no real ambient noise and no amount of noise that you make will matter and you don't have kids, then soundproofing would be somewhat pointless.
> 
> Personally, I don't see it as an either/or case. The soundproofing gets my theater's sound floor low enough that I can choose what volume I'm comfortable with and still hear even the quietest scenes, while acoustic treatments will ensure that the sound is delivered as it is intended (also helping to keep one volume level for the entire dynamic range of the movie).


Well, I'm not really worried about the neighbors, or anyone else in the house. I'm more concerned about the sound coming into the room. The primary concerns would be people running around upstairs and the HVAC system in the next room when it kicks on. How effective can sound isolation be if you just attack the ceiling and the wall leading to that adjoining room (The other walls are along the foundation)?


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## cw5billwade

sound has a tendency to go around things it is called flanking so if you were not going to do the walls on the concret the sound will just go around all your efferts on the ceiling and the other wall. If your plan is to stud and DW the concret walls then just decouple them with some IB-3 clips add R13 and do the DW/GG/DW. 5/8" fire proof not 1/2" light weight.


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## pitviper33

Here's a topic I've seen very little discussion on in this thread. I'll copy granroth's asking format from early in the thread.


*Question:* How efficient is the transfer of sound energy between a slab of concrete and the air? Are there recommended soundproofing treatments for a concrete floor?


Obviously concrete transfers mechanical vibrations very well. So if you have an air compressor running over on one side of the basement, that sound will easily carry through the floor into your theater room. But does that transfer still happen efficiently if the source of the noise is airborne? (I'm assuming that there are no speakers resting on the floor to supply mechanical vibration.) Asked another way, does sound inside your theater flank around your isolated walls through an untreated concrete slab to the rest of the house? If so, what treatments have been evaluated to lessen this effect?


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## BasementBob

pitviper33 said:


> *Question:* How efficient is the transfer of sound energy between a slab of concrete and the air? Are there recommended soundproofing treatments for a concrete floor?


Some people cut the concrete slab to decouple it. (possibly with a Concrete K Saw)
As for if that's Building Code approved in your area (e.g. water table concern), or if you'd caulk the joint with acoustic caulk or silicone, I don't know.


You can cut around the furnace, or you can cut around the theatre. Generally, cutting around the theatre is preferred for both ways (into and from the theatre). And many central air conditioner's have drains that go through the slab somewhere near the furnace.


I don't have any stats on the effectiveness. There is still some flanking transmission through the earth under the slab, but that's less.


Sometimes the transmission through whatever is under the slab is strange. I'm thinking of an example where the theatre sound couldn't be heard in the house next door, but it could be heard the house the other side of it, because the bedrock curved touching the two houses where the noise was generated and heard, but dipped under the house in the middle.




Other possibilities include
a) building a floating floor. Another concrete pad raised on pucks or springs, or (not both),
b) covering the home theatre floor in acoustic-mat (a kind of heavy rubber pad).
c) and of course ignoring it.


In the case of (a) and (b), the stud walls would be built on top of the floating floor or on top of the acoustic mat respectively. In the case of acoustic mat, bolts from the wall base plate through the mat to the concrete slab would also be isolated with rubber and washers.


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## pitviper33

The odd sound transmission through the earth is interesting. In the scenario you mention, I wonder how the homeowner receiving the noise ever figured out its source.


BasementBob said:


> Other possibilities include
> a) building a floating floor. Another concrete pad raised on pucks or springs, or (not both),
> b) covering the home theatre floor in acoustic-mat (a kind of heavy rubber pad).
> c) and of course ignoring it.
> 
> 
> In the case of (a) and (b), the stud walls would be built on top of the floating floor or on top of the acoustic mat respectively. In the case of acoustic mat, bolts from the wall base plate through the mat to the concrete slab would also be isolated with rubber and washers.


 In my particular case, I intend to build a floating floor within the theater anyway. I plan to do this for the sake of tactile response, which was sorely missing from my last basement theater. For that purpose an OSB subfloor on a 2x4 frame resting on foam isolators should be sufficient. (That's my thought. I'm open to suggestions.) My question was mainly wondering whether I also needed a floating floor in my infinite baffle subwoofer's backspace for the sake of noise isolation. I already intended to have that backspace within my double walled space. I had been thinking that I would have the floating floor within the interior walls. Would it be better to build the floating floor all the way out to the outer walls and rest the interior walls on it?


----------



## BasementBob

pitviper33 said:


> In my particular case, I intend to build a floating floor within the theater anyway. I plan to do this for the sake of tactile response, which was sorely missing from my last basement theater. For that purpose an OSB subfloor on a 2x4 frame resting on foam isolators should be sufficient. (That's my thought. I'm open to suggestions.) My question was mainly wondering whether I also needed a floating floor in my infinite baffle subwoofer's backspace for the sake of noise isolation. I already intended to have that backspace within my double walled space. I had been thinking that I would have the floating floor within the interior walls. Would it be better to build the floating floor all the way out to the outer walls and rest the interior walls on it?


 
Time for a diagram, or three. Ball's in your court.


Short answer to your last question -- probably. My first concern is: Depends on how thick sound path through the floated floor to the furnace room is. If the 'thickness' consists of a single layer of OSB that can be seen from the furnace if you put a mirror on the concrete slab beside a 'foam isolator', whereas your walls were going to be double stud walls with double layer's of 5/8" drywall with green glue, then nope.


BTW, pucks and springs are engineered (I think there's an exception that comes in sheets with the pucks amongst fiberglass, but usually they're engineered). The companies that manufacture them will ask you all the right questions, hand it off to their engineer to do the math, who will tell you how many and what type to buy and give instructions on how to install them.
This differs from e.g. floating the floor on rigid rockwool or acoustic-mat.


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## BasementBob

The numbers below are not representative of any particular room in existence -- so don't go thinking ALL slabs are 30dB, when few of them would be. 
The diagram is presented only as an example of dB addition (adding several dB values), and the idea of flanking -- at least how I think of both concepts.
(The gif was first created back around 2004 I think. Old stuff.)


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## pitviper33

Rereading my last post... it didn't make much sense. I did a poor job of describing my space.


I will have a medium sized theater space (about 17'x30'x9.5') on a concrete floor. That entire space will be soundproofed. The ceiling with clips and channels, some of the walls double stud and some of the walls single stud spaced from concrete block foundation walls. All of it with double drywall and green glue. Within that soundproofed space, the room is divided into three sections. Those are an equipment/projection room at the back, the main theater space, and space behind the baffle wall at the front. The dividing walls between the three sections are single stud, single layer of drywall. The main theater space will have some kind of floating floor. The question is whether the space in front of the baffle wall and the equipment room also need some treatment on the floor. They are still on the "noisy side" of the soundproofed walls, though the high frequency content will be somewhat attenuated by the dividing walls within the space. The low frequency content will be at full intensity in these areas.


The image you posted is helpful. Though the numbers aren't real, it at least suggests that once soundproofing techniques are applied to the walls and ceiling, a concrete floor might have the potential to become the weakest link for noise getting in or out.


As for how exactly I'll float the floor, I've been struggling to find much information on how that should be done for even tactile response. Maybe it's just a matter of using the wrong search terms. If you could point me in the direction of some information on the subject, or even just name one of these puck and spring companies, it would be much appreciated.


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## BasementBob

pitviper33 said:


> I will have a medium sized theater space (about 17'x30'x9.5') on a concrete floor. That entire space will be soundproofed. The ceiling with clips and channels, some of the walls double stud and some of the walls single stud spaced from concrete block foundation walls. All of it with double drywall and green glue. Within that soundproofed space, the room is divided into three sections. Those are an equipment/projection room at the back, the main theater space, and space behind the baffle wall at the front. The dividing walls between the three sections are single stud, single layer of drywall. The main theater space will have some kind of floating floor. The question is whether the space in front of the baffle wall and the equipment room also need some treatment on the floor. They are still on the "noisy side" of the soundproofed walls, though the high frequency content will be somewhat attenuated by the dividing walls within the space. The low frequency content will be at full intensity in these areas.



I take that to mean something like this


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## BasementBob

pitviper33 said:


> As for how exactly I'll float the floor, I've been struggling to find much information on how that should be done for even tactile response. Maybe it's just a matter of using the wrong search terms. If you could point me in the direction of some information on the subject, or even just name one of these puck and spring companies, it would be much appreciated.


 

Prior post I mentioned Acoustik-mat as an isolator.
People used to put rigid rockwool under floating floors. It lasts quite a while.

http://www.auralex.com/sound_isolation_uboat/sound_isolation_uboat.asp
http://audioundone.com/studio-floors


Kinetics RIM pucks and springs
http://www.kineticsnoise.com/arch/pdf/rim.pdf
http://www.kineticsnoise.com/hvac/fds.html
http://www.kineticsnoise.com/arch/lsm.html
http://www.bobgolds.com/HomeTheatreDesign/OLD/Bob03Room2bb.JPG
http://www.kineticsnoise.com/products.html
http://www.gearslutz.com/board/atta...spring-types-floating-concrete-floors-rim.jpg


"Neoprene" and ethylene propylene diene monomer (EPDM) pucks. 
from http://www.earsc.com/HOME/engineering/TechnicalWhitePapers/Vibration/index.asp?SID=61


And possibly the most important
http://www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=8173&start=0


There might be something here at AVS about floating floors too. Certainly more relevant to our darn subwoofers.


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## pitviper33

BasementBob said:


> I take that to mean something like this


 Yeah, exactly. Nice job on the diagram! The only difference between what you drew and what I had in mind is the connection you questioned, between the baffle walls and the ceiling. My thought was for those walls to not penetrate the soundproofed space by going through the drywall. They would be free standing walls, tied into studs on the sides and resting on the concrete floor, stopping at the ceiling drywall. I thought I'd replace the top layer of drywall with OSB in the ceiling in that area, and I'd screw them in. But those connections wouldn't take any vertical load. They'd just add some stiffness to the wall if somebody decided to lean on it or something. If I instead move the base of those walls up to on top of the floor treatment as you've suggested, I'll have to think about how that affects their stiffness compared to being on the concrete as I'd expected.


I'll review the links in your second post. Thanks a lot!


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## cw5billwade

I think Mario and Stockmonkey did what you are asking in their builds. Stockmonkey also had a frount IB chamber like you want check out his build and ask questions there.


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## BasementBob

pitviper33 said:


> I'll review the links in your second post. Thanks a lot!


 
re Floating Floors:
a) Beware resonance, where sound actually gets louder through the floor. If you're using pucks or springs, then you need a floating concrete slab above them because you need a resonance under 10 hz or so, and a wood deck just isn't going to get you there.
b) by the time you decide to float a floor, it's time to stop asking questions on an internet forum and hire an expert to design the space for you. Otherwise, odds are good you'll design something else that will negate the benefit of a floating floor. 


Personally I might google through AVS for Dennis Erskine talking about Acoustik-mat and I might try that the way I drew it, but I'd up the weight by using 2 layers of MDF sandwiching a layer of drywall on the floor instead of 2 layers of OSB, with green glue once. Dennis, alone, seems really fond of Acoustik-mat for certain applications like isolating subwoofer stages filled with sand. I'd want to do the math, and maybe an accelerometer experiment, to figure out what the resonance would be -- neither of which I know how to do right this moment. But by the time you're up to springs and pads, it's time to wander over to real pro's (not your local contractor, and not me) to design the entire shell for you.


If you haven't already, consider picking up a copy of "Home Recording Studio, Build it like the Pros" by Rod Gervais. Pg 44 through 46 in the first edition talk a bit about floating floors, including the 'probably not' suggestion, and there's lots more useful information in that book too.


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## BasementBob

pitviper33 said:


> Yeah, exactly. Nice job on the diagram! The only difference between what you drew and what I had in mind is the connection you questioned, between the baffle walls and the ceiling. My thought was for those walls to not penetrate the soundproofed space by going through the drywall. They would be free standing walls, tied into studs on the sides and resting on the concrete floor, stopping at the ceiling drywall. I thought I'd replace the top layer of drywall with OSB in the ceiling in that area, and I'd screw them in. But those connections wouldn't take any vertical load. They'd just add some stiffness to the wall if somebody decided to lean on it or something. If I instead move the base of those walls up to on top of the floor treatment as you've suggested, I'll have to think about how that affects their stiffness compared to being on the concrete as I'd expected.


 
For your middle walls, since what you're trying to do basically is building an I-beam, just an idea, perhaps skip the OSB up there and instead replace the top plate with a horizontally mounted 2x12 LVL. Set the height so that the first layer of drywall butts against the low side of the LVL, and the 2nd layer of ceiling drywall goes under it and screws into it.. Another alternative is to use a 2x4 top plate, with a steel I-beam bolted to the top of it, and a 2x4 bolted to the top of that, which would be plenty stiff.


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## BasementBob

cw5billwade said:


> I think Mario and Stockmonkey did what you are asking in their builds. Stockmonkey also had a frount IB chamber like you want check out his build and ask questions there.



Yes, definitely ask people who've done it before.
I see at Stockmonkey's thread, page 9, that he used Delta-FL and Subfloor, between walls mounted on the slab. That's probably great for a basement (moisture, warmth, usual basement issues), which might be the primary and dominant consideration. But from a resonance point of view, I don't know.


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## pitviper33

cw5billwade said:


> I think Mario and Stockmonkey did what you are asking in their builds. Stockmonkey also had a frount IB chamber like you want check out his build and ask questions there.


On your suggestion, I just found both of their builds. Thanks for pointing me to them.


BasementBob said:


> re Floating Floors:
> a) Beware resonance, where sound actually gets louder through the floor. If you're using pucks or springs, then you need a floating concrete slab above them because you need a resonance under 10 hz or so, and a wood deck just isn't going to get you there.
> b) by the time you decide to float a floor, it's time to stop asking questions on an internet forum and hire an expert to design the space for you. Otherwise, odds are good you'll design something else that will negate the benefit of a floating floor.


Actually, after reading through the johnsayers thread you pointed me to before, I'm a little more comfortable with the idea that flanking through the concrete floor isn't a big deal. The book you recommend is quoted in the first post saying as much. That pretty much answers the question that I came here to ask.


This is good news for me, in that my floating floor design can focus entirely on what was its primary purpose all along: tactile response. It can be built completely within the soundproofed space and only where seating is located, so it doesn't need to affect my soundproofing plan at all. The bad news for me is that there's even less information out there about this goal than there is about soundproofing (or not) a concrete slab. This thread isn't the place for that topic, so I can take that discussion elsewhere.


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## BasementBob

pitviper33 said:


> Actually, after reading through the johnsayers thread you pointed me to before, I'm a little more comfortable with the idea that flanking through the concrete floor isn't a big deal. The book you recommend is quoted in the first post saying as much.


Sounds good to me. (i.e. I'm comfy you've made a good decision)


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## ChldsPlay

So what is my best bet for mitigating sound from the adjacent utility room and sounds from upstairs without doing full isolation? What "little" can I do to get the most results?


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## panino

I've already posted this in my theater thread, but decided to repost the question here so I can get a broader expert opinion on this soundproofing issue.

I'm about to build my screenwall. Since the stage is essentially sitting free from the walls to isolate any sound transmission, should I also decouple it from the ceiling when I build the screen wall? I would think the answer is yes, but I don't think I've seen any build on here that has done that. Everyone seems to just run posts from the stage floor straight up to the ceiling with no decoupling brackets. I would imagine there would be some transmittal of sound, especially low frequencies, into the ceiling this way, but maybe it is negligible?


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## Nightlord

panino said:


> I've already posted this in my theater thread, but decided to repost the question here so I can get a broader expert opinion on this soundproofing issue.
> 
> I'm about to build my screenwall. Since the stage is essentially sitting free from the walls to isolate any sound transmission, should I also decouple it from the ceiling when I build the screen wall? I would think the answer is yes, but I don't think I've seen any build on here that has done that. Everyone seems to just run posts from the stage floor straight up to the ceiling with no decoupling brackets. I would imagine there would be some transmittal of sound, especially low frequencies, into the ceiling this way, but maybe it is negligible?


If the stage is decoupled, I'd prefer to run the posts clear in front of it if possible. If not possible I'd try to decouple at the top.


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## cw5billwade

a few IB3 clips may work but the base may get the screen wall shaking LOL. Not much surface contact on the minimualist wall to ceiling not sure it will matter much


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## granroth

panino said:


> I've already posted this in my theater thread, but decided to repost the question here so I can get a broader expert opinion on this soundproofing issue.
> 
> I'm about to build my screenwall. Since the stage is essentially sitting free from the walls to isolate any sound transmission, should I also decouple it from the ceiling when I build the screen wall? I would think the answer is yes, but I don't think I've seen any build on here that has done that. Everyone seems to just run posts from the stage floor straight up to the ceiling with no decoupling brackets. I would imagine there would be some transmittal of sound, especially low frequencies, into the ceiling this way, but maybe it is negligible?


There is a huge difference between the stage and the screenwall, though, and it has everything to do without how much surface area is in contact with the decoupled shell (walls and ceiling). A stage will have a pretty massive footprint pressed against the walls, if there is no gap, and this will result in a lot of energy being transferred to the walls. A screenwall, on the other hand, has a pretty negligible footprint on the ceiling resulting in pretty big drop in how much energy will be transferred.

I wish I had some numbers, but I can't find any anywhere.

That said, I was asking earlier about "through" door jambs versus disconnected ones especially since in one very specialized case, something as simple as a broom handle bridging outer and inner walls resulted in a staggering drop in soundproofing effectiveness. BasementBob gave a very good answer for that but, never being satisfied leaving well enough alone, I asked Rod Gervais directly. His response is _excellent_ : Rod Gervais Answer

Seriously, I'd recommend that everybody read that, since even his anecdotes are golden.

Anyway, the very very simplified answer (very simplified. very!) is that while the true reason is that the specific details matter a lot, there is a big element related to how much surface contact we are talking about. A through door jamb is touching the two walls in only a small footprint, compared to how much contact a non-decoupled wall would have between the layers of drywall or even the amount of contact that a concrete slab has on both decoupled walls.

That principle applies to the decoupled screenwall question, I think.


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## panino

granroth said:


> There is a huge difference between the stage and the screenwall, though, and it has everything to do without how much surface area is in contact with the decoupled shell (walls and ceiling). A stage will have a pretty massive footprint pressed against the walls, if there is no gap, and this will result in a lot of energy being transferred to the walls. A screenwall, on the other hand, has a pretty negligible footprint on the ceiling resulting in pretty big drop in how much energy will be transferred.
> concrete slab has on both decoupled walls.





cw5billwade said:


> a few IB3 clips may work but the base may get the screen wall shaking LOL. Not much surface contact on the minimualist wall to ceiling not sure it will matter much



Thanks guys for the advice! Even though my screenwall probably won't qualify as "minimalist" when done, I'll try to work towards decreasing the footprint where it touches the ceiling and side walls as much as possible. Hopefully this will be enough that my ceiling won't start shaking when the woofer goes woof.


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## granroth

*Caulk PLUS tape/mud in corners?*

The canonical procedure for sealing a theater includes applying a bead of acoustic (50yr) caulk in all corners. This includes wall to ceiling; wall to wall; and wall to floor.

My understanding based on many photos of other theaters, including those designed by "name" designers, is that even though the corners are caulked, they must _also_ be taped and mudded, like normal.

Can somebody confirm? Or say why not?


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## BasementBob

Granroth:

I don't paint caulk (except on windows).

The floor always has floorboards instead.


The ceiling can have trim instead.


For the wall to wall corner, just the traditional:
https://www.youtube.com/watch?feature=player_embedded&v=cr-vImEx3UM
https://www.youtube.com/watch?feature=player_embedded&v=4TM8dZ1lJmo


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## cw5billwade

Drywall guy was not happy where I called a big gap they needed to mud


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## granroth

cw5billwade said:


> Drywall guy was not happy where I called a big gap they needed to mud


I assume you meant "where I CAULKED a big gap they needed to mud". Did they say why he cared at all?


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## Dizzy49

granroth said:


> The canonical procedure for sealing a theater includes applying a bead of acoustic (50yr) caulk in all corners. This includes wall to ceiling; wall to wall; and wall to floor.
> 
> My understanding based on many photos of other theaters, including those designed by "name" designers, is that even though the corners are caulked, they must _also_ be taped and mudded, like normal.
> 
> Can somebody confirm? Or say why not?


I am also curious on if corners needs to be caulked AND taped/mudded.


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## Dizzy49

I have a question regarding the wiring. In the pics I have seen of soundproof installs, the insulation is right against the drywall.

I have my inner walls 1" from the existing walls. Can I run my wires in that 1" space, or should I run them through the studs like normal? If I run them through the studs, how should I try to position the wire and the insulation? Should I try to push the wire back so the insulation lays on top so it's flush with the studs as best I can? Or put the insulation behind the wire and use the wire to help hold the insulation in?


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## BasementBob

Mud & 'Tape'

If the gap is larger than 1/8" then paper tape might not last. If the gap is 3/8" and something touches the paper, it'll poke right through. If the wall moves, and it will, the rigid paper tape will rip.
The second youtube video in post #605 shows using plastic corner bead instead of paper tape.


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## BasementBob

Dizzy49 said:


> In the pics I have seen of soundproof installs, the insulation is right against the drywall.


Yes, that's normal. You want the transmitted sound to go through the insulation to reduce wall resonance



Dizzy49 said:


> I have my inner walls 1" from the existing walls. Can I run my wires in that 1" space


Sure. But remember that wall wires have to be fastened (stapled) within 12" of every termination (outlet, switch, etc) and every few feet depending upon local building code (unless going through studs horizontally in which case the cable should be at least 1.25" from the nailing edge which is usually the middle of the stud).


Dizzy49 said:


> or should I run them through the studs like normal?


Normal is best -- nice and predictable for future renovators, and tends to last.


Dizzy49 said:


> If I run them through the studs, how should I try to position the wire and the insulation? Should I try to push the wire back so the insulation lays on top so it's flush with the studs as best I can? Or put the insulation behind the wire and use the wire to help hold the insulation in?


That's one way. The way I do it is to take the 4"thick insulation, and cut a horizontal line into the insulation about 2" deep where the horizontal wire goes, and then push the insulation into place. Thus the face of the insulation is not cut, and there's little force on the wire, and the wire holds the insulation in place a bit. Alternatively you can cut insulation to fit above the wire, and then insulation to fit below the wire, and if you've cut it correctly you won't be able to see the wire because the upper and lower insulation touch and cover the wire.


----------



## marysue007

*Soundproofing basement, insulation, beadboard, ventilation issue*

I am soundproofing my basement. We installed R 14 insulation,, flush with the bottom of the joists, and have applied the first layer of 5/8" drywall. I plan on using soundproofing caulk between the panels, and then doing greenglue and a second layer of 5/8" drywall. I want to finish with beadboard on the ceiling. I am wondering:

1. If I could just do the beadboard finish rather than doing the second layer of drywall and then the beadboard, going with the greenglue method on the beadboard. I know the idea is to increase mass, but I've no clue how the mass of beadboard compares with drywall.

2. Do I need to be worried about air flow issues with the insulation, drywall, drywall, beadboard layers? The basement does not have moisture issues overall, but I'm not sure how adding all that insulation and drywall and then beadboard will trap heat or breathe. Most of the upstairs is old hardwood, with some rugs and the master is carpeted.

Any help would be greatly appreciated!


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## granroth

marysue007 said:


> I am soundproofing my basement. We installed R 14 insulation,, flush with the bottom of the joists, and have applied the first layer of 5/8" drywall. I plan on using soundproofing caulk between the panels, and then doing greenglue and a second layer of 5/8" drywall. I want to finish with beadboard on the ceiling. I am wondering:
> 
> 1. If I could just do the beadboard finish rather than doing the second layer of drywall and then the beadboard, going with the greenglue method on the beadboard. I know the idea is to increase mass, but I've no clue how the mass of beadboard compares with drywall.
> 
> 2. Do I need to be worried about air flow issues with the insulation, drywall, drywall, beadboard layers? The basement does not have moisture issues overall, but I'm not sure how adding all that insulation and drywall and then beadboard will trap heat or breathe. Most of the upstairs is old hardwood, with some rugs and the master is carpeted.
> 
> Any help would be greatly appreciated!


I assume you are referring to using soundproofing (acoustic) caulk in the corners and not actually _between_ the panels. Caulk would do very little between panels.

How close the beadboard would compare to 5/8" Type X drywall depends entirely on what type of material it is as well as how thick it is. Most beadboard I've seen is 1/8" thick, and so it wouldn't even remotely compare to the drywall. If it was close to 5/8" thick, then it could be okay. The details matter.

You shouldn't have to worry about air flow issues in that sense. Houses aren't designed with air leaks in mind, so blocking them can only help. That said, if you have central heating or cooling that depends on the return air flow going under a door and you seal the door... then you might have issues keeping the room conditioned without an explicit return vent.


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## Brian Fineberg

ok question...

If I am building in an unfinished basement from scratch (totally framing the room) if I use isolation brackets from the floor joists...will I need the Whisper clips and Hat channel for the drywall or can I eliminate that part of the project since the walls will be decoupled from the above floor anyhow...

thanks in advance!!


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## kmhvball

Brian Fineberg said:


> ok question...
> 
> If I am building in an unfinished basement from scratch (totally framing the room) if I use isolation brackets from the floor joists...will I need the Whisper clips and Hat channel for the drywall or can I eliminate that part of the project since the walls will be decoupled from the above floor anyhow...
> 
> thanks in advance!!


As long as the walls don't touch any other walls (i.e., foundation walls, or shared wall with another room)... then you wouldn't need Clips & Channel on the walls.

If you are using existing sub-floor joists for the ceiling, you would need them for the ceiling still. If you are creating an alternate joist ceiling, resting on the 'new' walls, then you wouldn't need it for the ceiling either.

I had three foundation walls, so, just framed those walls ~ 1" from the concrete wall. My 4th wall, I did 2, 2x4 parallel walls to decouple them. Net, not clips & channel needed.

My ceiling, I did use the existing subfloor joists - so, I added Clips & Channels there.


----------



## Brian Fineberg

awesome! thanks for the reply!!

so for the right foundation wall, build the frame out from the concrete 1" then use clips and hat channel for the ceiling

then for screenwall just frame with clips for the floor joists

left wall would need clips and channels

rear wall just celing joist channels?

this seems like its going to save me a bunch of money...I am really excited now!! thank you for the insight!!


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## smuggymba

3 walls of my media room are on the outside and only one is common to other rooms.

For sound isolation/proofing - Can I just sound proof one wall i.e. the one common with the game room? Will that help or should we target all walls + ceiling?


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## cw5billwade

smuggymba said:


> 3 walls of my media room are on the outside and only one is common to other rooms.
> 
> For sound isolation/proofing - Can I just sound proof one wall i.e. the one common with the game room? Will that help or should we target all walls + ceiling?


if you are concerd with not having sound elsewhere than you need to do all the above. Are we talking about basment or in a bonus room. It makes a huge differance. If bonus check out my build.


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## smuggymba

cw5billwade said:


> if you are concerd with not having sound elsewhere than you need to do all the above. Are we talking about basment or in a bonus room. It makes a huge differance. If bonus check out my build.


It's a dedicated media room 11.5 X 21 on the second floor.


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## cw5billwade

smuggymba said:


> It's a dedicated media room 11.5 X 21 on the second floor.


Ok I am trying to wrap my head around 3 detached walls on second floor. But being on second fllorr you want to do sound proffing on all f walls floor and ceiling. Other wise the sound will flank via the attic to the rest of second floor and via the floor to the first floor. I am really happy how my sound proffing turned out but I went the extra mile.


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## smuggymba

cw5billwade said:


> Ok I am trying to wrap my head around 3 detached walls on second floor. But being on second fllorr you want to do sound proffing on all f walls floor and ceiling. Other wise the sound will flank via the attic to the rest of second floor and via the floor to the first floor. I am really happy how my sound proffing turned out but I went the extra mile.


It's a room on top of a porch..so outer 3 walls have bricks...one wall is on the inside.

My room is 11.5 wide so I don't want to take away 1ft or so that might be needed for clips/channels. extra drywall layer etc. How much would it cost to rip down all the drywall (which is free since I'll do it), and then do the clip/channel thing and extra layer of drywall/greenglue?


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## cw5billwade

maybe a picture or drawing than. sounds sort of like a bonus room over a garage. are the brick walls you mention full 2nd floor height or do you have knee walls like a bonus room. I would think if the later than I would just put a second layer of 5/8" fire proof drywall with Green Glue on thoes 3 walls as they are already decoupled from the main house and already most likly have insulation in them. You may want to remove the drywall on the ceiling and do clips and channel though to de couple from the attic space unless it is not shared with the house than just do another layer of 5/8" DW and GG. for the joining wall to the house I would take off the dry wall in the theater sided and do a second decoupled wall insoluate both walls and 2 layers of DW/GG/DW I would add a layer of DW on the game room side with GG. I think this will give you a nice room. replace the door with a 1 3/4" solid core door.


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## cw5billwade

cost for my sound proofing materiels less DW was about $3k that was for a 19x23' room


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## Brian Fineberg

for my ceiling (in an unfinished basement) I have quite a few pipes (water drain and feed) that are hung from the joists...my question is how will i run channel and clips if these are protruding doen? will I have to get them moved (big expense added)

you can see them in this pic:


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## cw5billwade

normaly a soffit is used to hid things like this


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## Brian Fineberg

cw5billwade said:


> normaly a soffit is used to hid things like this



yes but some of these things run in the middle of the room


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## cw5billwade

you just like a challenge don't you! from the picture it looked closer tothe back. If they are supply lines it would not be difficult to raise them intothe joist area the drain on the other had requires more thought. I think a fewfolks on here have had plumbers do it all for about $300 or so but you wouldhave to get a few estimates. Make a brand new tread with the title help me move my plumbing for sound proffing or something like that and give good measurments. You will get a lot of help that way!!!


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## Brian Fineberg

thank you!!!


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## DallasMike

you guys go to the extreme. I love it!


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## granroth

Brian Fineberg said:


> for my ceiling (in an unfinished basement) I have quite a few pipes (water drain and feed) that are hung from the joists...my question is how will i run channel and clips if these are protruding doen? will I have to get them moved (big expense added)


If you are okay with losing a few inches, then here are two options:

Option 1: Sister some new wider joists to your existing ones, so that the ceiling level is now below those pipes. Attach the clips to the sistered joists and go from there.

Option 2: Built a room-in-a-room, with floating joists between your existing joists. You'd lose slightly less ceiling height (likely not noticeable depending on how you would do the chips in the other options) but would lose more space on the walls


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## Brian Fineberg

granroth said:


> If you are okay with losing a few inches, then here are two options:
> 
> Option 1: Sister some new wider joists to your existing ones, so that the ceiling level is now below those pipes. Attach the clips to the sistered joists and go from there.
> 
> Option 2: Built a room-in-a-room, with floating joists between your existing joists. You'd lose slightly less ceiling height (likely not noticeable depending on how you would do the chips in the other options) but would lose more space on the walls


I like the sister joist idea....would I just nail them to the sides of the existing joists? just hanging a few inches below? I am not overly concerned with losing an inch r two from the ceiling height...


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## granroth

Brian Fineberg said:


> I like the sister joist idea....would I just nail them to the sides of the existing joists? just hanging a few inches below? I am not overly concerned with losing an inch r two from the ceiling height...


Yes. If you have a drop bigger than a couple of inches, then I'd use a 2x6 or 2x8, but otherwise even nailing/screwing a 2x4 to the sides of the existing joists would work.

Here's a very good article on doing precisely this using steel studs. Download the (free) PDF: http://www.finehomebuilding.com/how-to/articles/leveling-an-old-ceiling.aspx

The guy uses steel studs because they are lighter and straighter than wood studs. I'm not entirely certain that those would be strong enough to support a couple layers of 5/8" drywall, though.


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## Brian Fineberg

perfect...thank you!


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## smuggymba

I have a finished media room. If I were to take down the existing drywall for sound proofing, how much extra inches will I have to give away on each side?

Just trying to see how much space will be gone that will affect screen size and seating arrangement. It's 11.5 X 21 room.


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## BasementBob

granroth said:


> otherwise even nailing/screwing


Nail/bolt & PL-glue, not Nail/screw. Screws aren't likely up to the necessary sheer force required for sistered joists, but consult your local building code to be sure.


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## Brian Fineberg

BasementBob said:


> Nail/bolt & PL-glue, not Nail/screw. Screws aren't likely up to the necessary sheer force required for sistered joists, but consult your local building code to be sure.



my father in law is a builder so he will know all the codes etc...He probably would know about the sister joists as well...just figure I would ask here from those who are soundproofing experts


----------



## granroth

BasementBob said:


> Nail/bolt & PL-glue, not Nail/screw. Screws aren't likely up to the necessary sheer force required for sistered joists, but consult your local building code to be sure.


Well... it depends on what the purpose of the sistered joists are for. Yeah, when you typically sister a joist, you are doing so to strengthen the existing joist for some reason. I've done that to span a longer gap and to decrease the deflection under a load point. In those cases, I've done a three tiered approach:

Step 1: Glue those joists together
Step 2: Insert some 1/2" lag bolts every couple of feet
Step 3: Pound in 16d or 20d every couple of inches

In those cases, I passed inspection easily.

But in this case, the sistered joists aren't for structural support at all. They will not affect the stiffness or load capacity of the existing joists in any important way. They only exist as a way of dropping the ceiling down a couple of inches and provide solid support for the drywall.

The only code I'd assume would come into play would be the load bearing capacity with respects to the drywall. That article/PDF I linked to suggested using steel studs with screws with the expectation that it would do just fine to hold up typical drywall (which may well be 5/8"). Whether it could hold up two layers is an unknown to me, but certainly 2x4s or 2x6s could. And I would be very surprised if screws weren't enough for this specific requirement.

I am not a building inspector. Never take what I say as gospel truth.


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## granroth

smuggymba said:


> I have a finished media room. If I were to take down the existing drywall for sound proofing, how much extra inches will I have to give away on each side?
> 
> Just trying to see how much space will be gone that will affect screen size and seating arrangement. It's 11.5 X 21 room.


It absolutely depends on what level of soundproofing you want to get to; how much money you are willing to spend; and how much space you are willing to give up. The short version is you'd lose between 1/4" all the way up to 9-1/2" with quite a few gradients in between, all depending on your constraints.

I did some sample calculations in this post to give you some ideas about space vs performance vs price tradeoffs: Soundproofing Master Thread - Post 517

Let me know if you want some specific ideas based on your personal constraints.


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## BasementBob

granroth said:


> But in this case, the sistered joists aren't for structural support at all.


To me "sistering" is always structural.
What you're talking about I call"leveling strapping", sometimes done with 2x4's or even 1x3's, lately being done with steel"C" studs/joists because they're either straight or obviously broken. Strapping is often done perpendicular to the joists all under the joists, but here the strapping is done parallel to the joists attached to their sides.

If sistering isn't needed structurally, then Ted White's room-in-a-room technique, with joists supported only by inner room walls with the new 'room ceiling' joists between but not touching the pre-existing floor joists, does the same leveling, with better decoupling.


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## Brian Fineberg

The room in a room...how are the walls supported? If they are not tying into the ceiling?


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## granroth

Brian Fineberg said:


> The room in a room...how are the walls supported? If they are not tying into the ceiling?


The Soundproofing 101 page on this goes into pretty decent detail: Building a Room Within a Room

I'll try to describe it slightly differently.

Picture a typical framed out room, where you have a ceiling made up of structural joists and then stud walls that are nailed directly to the joists (or to ladders between the joists if the walls are parallel).

Now picture an exterior shed/barn/garage/etc that is only one room. In that case, you'd first make the four stud walls and then rest the joists directly on those walls. The four stud walls you created become the load bearing ones for the ceiling. It's a standalone structure/room just with those walls and ceiling resting on the wall top plates.

Step three -- take that standalone shed/barn/room and place it inside of your first room. BAM -- you have a room in a room, with both the exterior and interior rooms independent of each other.

In a simple case, you could just have the inner room's joists be underneath the outer room's joists. That's a waste of space, though, so a better way is to just offset the inner wall's joists so that they are in between the outer wall's joists. In that case, your inner room ceiling could be up to maybe 1/2" from the outer ceiling (probably not closer due to wood expansion and contraction). in your specific case, you'd just build the inner room walls to be just below the pipes.

The inner room will have a tendency to want to rack until it is fully sheathed. Some people get around this by attaching the inner walls to the outer joists using damped clips (IB-3 and the like). This keeps the rooms decoupled but removes some of the inner wall racking.

A room in a room is the gold standard for a soundproofed room, but it does require more space. In particular, for each wall, you'll lose roughly 1/2" - 3/4" for the space between the walls and then another 3-1/2" or more for the inner framed wall. I assume that a room in a room design will lose at least 8" in each width and length dimension in a room.


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## BasementBob

Ted White's :






















Note: building code's requirements for room in a room may include earthquake stabilizers (WIL or WCL sway braces), or mineral wool firestops.
I've always wondered if using a first 'drywal' layer of 3/4" plywood would do a better job than sway braces, and it makes screwing the inner 2nd layer of actual firestopping 5/8" drywall really idiot proof (none of that "missed the stud" with the 2nd layer) -- when was the last time a wooden box collapsed due to an earthquake or bit of wind.


A common issue with existing 2x8 floor joists is the blocking must not be removed.


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## BasementBob

BTW, there are variations on clip mountings that can be used to level a ceiling -- at a loss of a bit of ceiling height.
There's http://www.pac-intl.com/smart_clip.htm (usually combined with RISC-1 on the walls)
and for larger un-level-ness there's http://www.kineticsnoise.com/arch/icw.html
or mason industries WHR ceiling hangers (wire suspended ceilings), or their HDSM style.


Leveling a ceiling makes drywalling easier (e.g. less mudding trying to make it look flat) -- but more importantly makes everything else you do within the room easier, such as mounting cabinets.


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## mhutchins

BasementBob said:


> Ted White's :


Great drawings!!

Can the ceiling joists for the interior room be smaller than the overhead floor joists?? After all, they are not supporting a floor or any live loads, and are only called upon to support a few layers of drywall, soffits and whatever lights and other accessories you end up hanging from the ceiling. I would think 2x6 would be sufficient for smaller spans, maybe even 15' or more, but I haven't checked any span tables...

Mike


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## granroth

mhutchins said:


> Can the ceiling joists for the interior room be smaller than the overhead floor joists?? After all, they are not supporting a floor or any live loads, and are only called upon to support a few layers of drywall, soffits and whatever lights and other accessories you end up hanging from the ceiling. I would think 2x6 would be sufficient for smaller spans, maybe even 15' or more, but I haven't checked any span tables...


No, definitely use the span tables are else your drywall will be deflecting a lot more than you would like. A stud grade Douglas Fir 2x6 spaced 24" O.C. would only support 8'-1" according to this calculator:

http://www.awc.org/calculators/span/calc/timbercalcstyle.asp

Grade does matter quite a bit. But even select grade 2x6s spaced 16" O.C. can't handle a 12' span.


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## kmhvball

granroth said:


> A stud grade Douglas Fir 2x6 spaced 24" O.C. would only support 8'-1" according to this calculator:
> 
> http://www.awc.org/calculators/span/calc/timbercalcstyle.asp
> 
> Grade does matter quite a bit. But even select grade 2x6s spaced 16" O.C. can't handle a 12' span.


I would think 2x6", for 16" O.C. for 12' span would work, see attached illustration - of course, depends on type of wood (around my area, spruce-pine-fir are the popular woods). I believe this would fit the 'ceiling joist' member type, given no load of people/ furniture, etc. to support. This shows a Dead Load of 10 lbs/ square foot, and a 'dead load' would be what is assessed given only supporting a constant load of drywall. I did a single quick google search, that says 5/8" Drywall is ~ 2.3 psf, so, even with a triple layer would be 6.9 psf, then add a bit of weight for G.G. I would think the 10 lbs/ sf is achievable.










Even if it is technically enough, I might still lean towards 2x8s.. for one, just a peace of mind, and for two.. my Perception is 2x8s tend to be straighter.


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## cw5billwade

Brian Fineberg said:


> http://s19.photobucket.com/user/bcf...9-4655-95C5-0EEA4F10346A_zps5s6f3pq8.jpg.html


Guys don't forget the Op has HVAC running the entire length down the one side. How would you do room in a room with that limitation?


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## BasementBob

cw5billwade said:


> Guys don't forget the Op has HVAC running the entire length down the one side. How would you do room in a room with that limitation?


I moved my hvac runs, forced and return, over four feet to get them out of the way. I moved the furnace a couple feet, and the hot water tank about 8 feet.


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## Brian Fineberg

BasementBob said:


> I moved my hvac runs, forced and return, over four feet to get them out of the way. I moved the furnace a couple feet, and the hot water tank about 8 feet.


How much did that cost?


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## BasementBob

Brian Fineberg said:


> How much did that cost?


I replaced my furnace and air conditioner the same time, so I don't really know. Same crew came in and did it all in one day. Well, actually two days but that's a different story.


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## dmbandtimmy

This is an awesome thread. I'll post pictures of my space tomorrow. Walls are already drywalled and it's old construction. I mainly just want to dampen the noise that goes up stairs and vice versa. 

My plan is to use hat channel and insulation. However, I'm not sure of all of the materials I need. Does anyone have experience with hat channel?


----------



## granroth

dmbandtimmy said:


> This is an awesome thread. I'll post pictures of my space tomorrow. Walls are already drywalled and it's old construction. I mainly just want to dampen the noise that goes up stairs and vice versa.
> 
> My plan is to use hat channel and insulation. However, I'm not sure of all of the materials I need. Does anyone have experience with hat channel?


Working backwards, yes, using clips and channels is an extremely common way of accomplishing the decoupling aspect of soundproofing. Here's a good primer:

Soundproofing 101: Channel with Clips

Note, though, that it's always "clip and channels" and never just channels. Just using hat channels without the clips will do absolutely nothing productive.

Then, you said that the walls are already drywalled. If you will be applying clips and channels to the ceiling then it MUST NOT be already drywalled. If it is, then the drywall must be removed. Failing to do this will result in a "triple leaf" effect, which will actually make everything far worse, rather than making it better.

One thing to keep in mind if you will only treat the ceiling and not touch the walls -- sound has a nasty habit of "flanking" your best efforts. Yes, a treated ceiling will stop a good amount of sound, but if the walls remain as-is, then more sound may transmit up through them to the upper floors than you would expect. Another good primer on that subject:

Soundproofing 101: Flanking


----------



## thestoneman

Was in my "sound proof" room last night looking around and I was able to hear sound from the kitchen above. It was pretty faint, but definitely audible. Does this mean there were mistakes made somewhere?

I did use 1/2"/GG/1/2", but did use clips and channel w/ R13.


----------



## kmhvball

AXLCMT said:


> Just wrote this all up and then lost it.  Here it goes for the second attempt...
> 
> 
> I performed a search on this thread for the words "behind the screen", hoping to find any posts with regards to my need to know if I should put Base Trapping (most likely OC703 unless you guys suggest a cheaper alternative to save me some ???) *BEHIND* my *SOLID* Screen (not acoustically transparent/fabric).
> 
> I planned on buying Base Trapping for the entire front screen wall, plus the sides of the room up until "ear height" and the Cotton Batting from the "ears up".
> 
> So the question is, is it the "law of diminishing return" with regards to putting "base trapping/OC703" *BEHIND* the* SOLID* Screen if I am base trapping the entire screen wall???
> 
> I know that if you have an "acoustically transparent screen" you automatically put base trapping behind the screen, but what about for a solid screen?
> 
> I hope your answers are "no" to save me some $$$ when it comes to base trapping square footage. My screen is 160" 2.35:1 Jamestown 1.2 gain.
> 
> Thanks.


I think your questions are really about "Acoustics" vs soundproofing,.... there is another Sticky thread for acoustics (http://www.avsforum.com/forum/19-de...5432-acoustical-treatments-master-thread.html)...

My only slightly informed opinion, would be if you don't have an AT screen, then treating immediately behind the screen wouldn't do much good as the screen will reflect sound before it gets to the wall. Of course, on the 'outside edges' of the screen, a corner bass trap could be helpful (although, with a 160" screen, maybe you don't have outside edges!!!).


----------



## kmhvball

thestoneman said:


> Was in my "sound proof" room last night looking around and I was able to hear sound from the kitchen above. It was pretty faint, but definitely audible. Does this mean there were mistakes made somewhere?
> 
> I did use 1/2"/GG/1/2", but did use clips and channel w/ R13.


Is your last sentence supposed to be "I did use 1/2"/GG/1/2", but did NOT use clips and channel w/ R13"??

Typically methodology would be 2 layers of Type X 5/8" Drywall vs 1/2", particularly if it is the new 'lightweight' 1/2", many use R-19 in ceiling/floor joists. 

Not using Clips & Channel definitely reduces effectiveness as you are then not providing the Decoupling benefit, one of the major sound reduction improvement avenues. .

Additionally, you don't reference your walls, but if you didn't do anything on walls, you can have flanking issues.

Then, depending on if there are air ducts/returns, and how you managed them, that could contributed.

Finally... the efforts of most on this forum for Sound Proofing aren't to 100% eliminate sound, but to 'reduce' sound transmission. So, if your sound is based on someone using a Blender upstairs; high heels walkign on hard wood, etc., some sound transmission will occur.


----------



## AXLCMT

kmhvball said:


> I think your questions are really about "Acoustics" vs soundproofing,.... there is another Sticky thread for acoustics (http://www.avsforum.com/forum/19-de...5432-acoustical-treatments-master-thread.html)...
> 
> My only slightly informed opinion, would be if you don't have an AT screen, then treating immediately behind the screen wouldn't do much good as the screen will reflect sound before it gets to the wall. Of course, on the 'outside edges' of the screen, a corner bass trap could be helpful (although, with a 160" screen, maybe you don't have outside edges!!!).


Post deleted!!!!! Oops!!!!


----------



## thestoneman

kmhvball said:


> Is your last sentence supposed to be "I did use 1/2"/GG/1/2", but did NOT use clips and channel w/ R13"??
> 
> Typically methodology would be 2 layers of Type X 5/8" Drywall vs 1/2", particularly if it is the new 'lightweight' 1/2", many use R-19 in ceiling/floor joists.
> 
> Not using Clips & Channel definitely reduces effectiveness as you are then not providing the Decoupling benefit, one of the major sound reduction improvement avenues. .
> 
> Additionally, you don't reference your walls, but if you didn't do anything on walls, you can have flanking issues.
> 
> Then, depending on if there are air ducts/returns, and how you managed them, that could contributed.
> 
> Finally... the efforts of most on this forum for Sound Proofing aren't to 100% eliminate sound, but to 'reduce' sound transmission. So, if your sound is based on someone using a Blender upstairs; high heels walkign on hard wood, etc., some sound transmission will occur.


I did decouple all walls and the ceiling. I was merely pointing out that I "skimped" on the drywall by not using 5/8".

I have a single duct, but it is not rigid. The sound did not seam to be transmitting through the duct. 

I should also point out that a completely soundproof room was never my goal. I wanted to greatly reduce the sound transmission, which I think I have, but hearing the sounds I heard last night begged the question, "should I be able to hear cabinets slamming at all, let alone faintly?"


----------



## dmbandtimmy

granroth said:


> Working backwards, yes, using clips and channels is an extremely common way of accomplishing the decoupling aspect of soundproofing. Here's a good primer:
> 
> Soundproofing 101: Channel with Clips
> 
> Note, though, that it's always "clip and channels" and never just channels. Just using hat channels without the clips will do absolutely nothing productive.
> 
> Then, you said that the walls are already drywalled. If you will be applying clips and channels to the ceiling then it MUST NOT be already drywalled. If it is, then the drywall must be removed. Failing to do this will result in a "triple leaf" effect, which will actually make everything far worse, rather than making it better.
> 
> One thing to keep in mind if you will only treat the ceiling and not touch the walls -- sound has a nasty habit of "flanking" your best efforts. Yes, a treated ceiling will stop a good amount of sound, but if the walls remain as-is, then more sound may transmit up through them to the upper floors than you would expect. Another good primer on that subject:
> 
> Soundproofing 101: Flanking



Awesome, thank you for the reply and good reads. My ceiling isn't drywalled, but the walls are. I'll take a picture after I get back from the gym and will post it. I hope to have my framer in next week to get started with the framing and resilient channel with clips. I'll need to order them ASAP. Is the website you post a good source for it? Thanks!!


----------



## dmbandtimmy

dmbandtimmy said:


> Awesome, thank you for the reply and good reads. My ceiling isn't drywalled, but the walls are. I'll take a picture after I get back from the gym and will post it. I hope to have my framer in next week to get started with the framing and resilient channel with clips. I'll need to order them ASAP. Is the website you post a good source for it? Thanks!!


Here is a picture of one side of the basement. It's about 1900 sq ft. I plan on putting a movie type area on the other side and this side will be for my pool table and foosball table. There is a bath and bed off to the right. 

This is how the entire basement is finished. I just bought it and the prior owners did the basement themselves and didn't do a bang up drywall job. 

Will I still be able to use channel and clips in this situation?


----------



## dmbandtimmy

dmbandtimmy said:


> Here is a picture of one side of the basement. It's about 1900 sq ft. I plan on putting a movie type area on the other side and this side will be for my pool table and foosball table. There is a bath and bed off to the right.
> 
> This is how the entire basement is finished. I just bought it and the prior owners did the basement themselves and didn't do a bang up drywall job.
> 
> Will I still be able to use channel and clips in this situation?


Sorry. I the file I attached was too big. Here it is


----------



## granroth

thestoneman said:


> I did decouple all walls and the ceiling. I was merely pointing out that I "skimped" on the drywall by not using 5/8".
> 
> I have a single duct, but it is not rigid. The sound did not seam to be transmitting through the duct.
> 
> I should also point out that a completely soundproof room was never my goal. I wanted to greatly reduce the sound transmission, which I think I have, but hearing the sounds I heard last night begged the question, "should I be able to hear cabinets slamming at all, let alone faintly?"


Yes, possibly.

I did a few quick tests slamming a few cabinet doors (very satisfying, by the way) and measured how loud it was. They ranged from roughly 80dBC to 90dBC, depending on how forcefully I slammed them. The 80dBC peak was just swinging them shut, without any notable force. Cabinets are apparently decently loud!

A typical room like yours done with 5/8" Type X instead of 1/2" can be expected to have an STC rating of maybe 55 or so (tons of factors, which can ease that up or down). That doesn't mean that it'll reduce the incoming sound by 55 dB, though, since it's a weighted scale.

But let's say that it is reducing the incoming cabinet door slams a good 50 dBC on the frequencies that matter. In that case, the sound would still be at 30 dBC in your theater. That's definitely audible.

And yeah, using 1/2" instead of 5/8" Type X will make a difference. The NRC links in the first couple of posts to this thread have tests comparing the two, if you want to track them down.


----------



## granroth

dmbandtimmy said:


> Awesome, thank you for the reply and good reads. My ceiling isn't drywalled, but the walls are. I'll take a picture after I get back from the gym and will post it. I hope to have my framer in next week to get started with the framing and resilient channel with clips. I'll need to order them ASAP. Is the website you post a good source for it? Thanks!!


Yes, the founder of the Soundproofing Company is Ted White, who used to be extremely active here on AVS Forum (and still stops by every now and then). He's a very pragmatic guy and has a wealth of knowledge about soundproofing to fit any need and budget.

Definitely call and not email, though. Ted or John will want to go through your soundproofing plan to make sure that you will be happy with what they sell you.


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## granroth

dmbandtimmy said:


> Here is a picture of one side of the basement. It's about 1900 sq ft. I plan on putting a movie type area on the other side and this side will be for my pool table and foosball table. There is a bath and bed off to the right.
> 
> This is how the entire basement is finished. I just bought it and the prior owners did the basement themselves and didn't do a bang up drywall job.
> 
> Will I still be able to use channel and clips in this situation?


Heh, funny, that attachment was upside down when I looked at it and it confused the heck out of me 

In short, yes, you could absolutely use clips and channels (not "resilient channel", btw -- it's not the same thing and resilient channel can be notably worse) on the ceiling in this case, and it would make a notable difference in sound transfer to the upper floor. You may need to move the ductwork, though, unless you framed a smaller room that avoided them.

Here's my biggest piece of advice: don't rush this. You have a wonderful space down there but given your specific requirements and budget, there is an almost infinite number of possibilities on how you could create a theater in that space. Spend some time browsing through the build threads here and see what kind of theater you really want.

Maybe what you'll eventually discover is that all you really want is a media room where you can watch some TV and movies on a TV. Maybe then it's not worth doing any decent soundproofing. Or could be that you fall in love with the idea of a having a much more elaborate theater where you create a room-within-a-room with full acoustic treatments and 11.2 speakers and the whole nine yards. In that case, just doing clips and channels might not be near enough for your needs.


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## thestoneman

granroth said:


> Yes, possibly.
> 
> I did a few quick tests slamming a few cabinet doors (very satisfying, by the way) and measured how loud it was. They ranged from roughly 80dBC to 90dBC, depending on how forcefully I slammed them. The 80dBC peak was just swinging them shut, without any notable force. Cabinets are apparently decently loud!
> 
> A typical room like yours done with 5/8" Type X instead of 1/2" can be expected to have an STC rating of maybe 55 or so (tons of factors, which can ease that up or down). That doesn't mean that it'll reduce the incoming sound by 55 dB, though, since it's a weighted scale.
> 
> But let's say that it is reducing the incoming cabinet door slams a good 50 dBC on the frequencies that matter. In that case, the sound would still be at 30 dBC in your theater. That's definitely audible.
> 
> And yeah, using 1/2" instead of 5/8" Type X will make a difference. The NRC links in the first couple of posts to this thread have tests comparing the two, if you want to track them down.


I was really trying to maximize the ceiling height so I made the call the go w/ 1/2". Probably shouldn't have let the 1/8" of mass go. 

I will note that the difference from where it was prior to closing in is staggering. I could easily hear casual conversation before. Now, only higher volume sounds are barely audible...and likely coming from the open threshold (solid core door not in yet).


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## dmbandtimmy

granroth said:


> Heh, funny, that attachment was upside down when I looked at it and it confused the heck out of me
> 
> In short, yes, you could absolutely use clips and channels (not "resilient channel", btw -- it's not the same thing and resilient channel can be notably worse) on the ceiling in this case, and it would make a notable difference in sound transfer to the upper floor. You may need to move the ductwork, though, unless you framed a smaller room that avoided them.
> 
> Here's my biggest piece of advice: don't rush this. You have a wonderful space down there but given your specific requirements and budget, there is an almost infinite number of possibilities on how you could create a theater in that space. Spend some time browsing through the build threads here and see what kind of theater you really want.
> 
> Maybe what you'll eventually discover is that all you really want is a media room where you can watch some TV and movies on a TV. Maybe then it's not worth doing any decent soundproofing. Or could be that you fall in love with the idea of a having a much more elaborate theater where you create a room-within-a-room with full acoustic treatments and 11.2 speakers and the whole nine yards. In that case, just doing clips and channels might not be near enough for your needs.


That's exactly what I want, a media room. I'd still like to have decent sound proofing so that people upstairs can't hear much from downstairs and the other way around. I'll give that company a call tomorrow as I'd like to get started on this ASAP. Thanks for the solid!


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## cw5billwade

dmbandtimmy said:


> That's exactly what I want, a media room. I'd still like to have decent sound proofing so that people upstairs can't hear much from downstairs and the other way around. I'll give that company a call tomorrow as I'd like to get started on this ASAP. Thanks for the solid!


Then you want 2 layers of 5/8" DW/GG/DW directly to sub floor above (cut strips of DW GG and screw directly to the sub floor then GG and 2nd layer of DW)(insure first layer the screws are short enough they do not go through the sub floor). Put R19 into the floor joists and use clips and channel with 2 layers of 5/8" DW/GG/DW for ceiling. Use backer boxes for all of the lighting and insure HVAC is treated as well. After the first layer of the ceiling DW is up you want to put GG/5/8" DW layer on your curent walls then the second layer on the ceiling.


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## Reefdvr27

Well I finished my theater and sat down with my wife and we watched my first movie which was EOT and a half hour later the police came and asked me to turn it down. I have been playing bass heavy movies for years and nobody has ever said a thing. I move one room over and now I get a complaint. 

I used quiet rock and Roxul and thought that would be just fine as I did not care about sound in the house. Is there anyway I can sound proof the outside? If I took down the siding and add more layers of plywood and any kind of acoustical panels with it? This really sucks when I asked the guy next door to come over and tell me if he could hear the theater, but instead he just calls the cops. I am so pissed off now a years worth of work and waiting and now the room just sits there.


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## pitviper33

Reefdvr27 said:


> Well I finished my theater and sat down with my wife and we watched my first movie which was EOT and a half hour later the police came and asked me to turn it down. I have been playing bass heavy movies for years and nobody has ever said a thing. I move one room over and now I get a complaint.
> 
> I used quiet rock and Roxul and thought that would be just fine as I did not care about sound in the house. Is there anyway I can sound proof the outside? If I took down the siding and add more layers of plywood and any kind of acoustical panels with it? This really sucks when I asked the guy next door to come over and tell me if he could hear the theater, but instead he just calls the cops. I am so pissed off now a years worth of work and waiting and now the room just sits there.


Wow that sucks. I don't have any advice to offer, but I feel for you. It must be heart breaking. I hope you can get some kind of arrangement worked out with your neighbor to avoid the expense and time of soundproofing modifications. Good luck.


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## Reefdvr27

pitviper33 said:


> Wow that sucks. I don't have any advice to offer, but I feel for you. It must be heart breaking. I hope you can get some kind of arrangement worked out with your neighbor to avoid the expense and time of soundproofing modifications. Good luck.


 Nope, there will be no working anything out. All of my neighbors are aholes. The guy who I think called has a race car with open headers and reeves the car all the time, but that is ok. Not to mention his Harley at 6 am. Like I said Paybacks are going to sting. I would never call the cops on anybody with out talking first. I put up with allot of noise because everybody is guilty of it time to time, but this is hitting a guy below the belt.


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## BasementBob

Reefdvr27 said:


> now the room just sits there.


The easiest thing you can do short term while you figure out what to really do is to find a way to reduce the bass. A high pass filter (crossover) to the mains, with the subwoofers turned off. (or headphones)
A variation is to watch movies without a lot of bass content. Dramas not action. 1970s television shows on DVD
Any wall, including what you have right now, is much more effective at soundproofing at high frequencies than low frequencies


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## granroth

Reefdvr27 said:


> Well I finished my theater and sat down with my wife and we watched my first movie which was EOT and a half hour later the police came and asked me to turn it down. I have been playing bass heavy movies for years and nobody has ever said a thing. I move one room over and now I get a complaint.
> 
> I used quiet rock and Roxul and thought that would be just fine as I did not care about sound in the house. Is there anyway I can sound proof the outside? If I took down the siding and add more layers of plywood and any kind of acoustical panels with it? This really sucks when I asked the guy next door to come over and tell me if he could hear the theater, but instead he just calls the cops. I am so pissed off now a years worth of work and waiting and now the room just sits there.


Oof! That's rough. I remember you asking some questions on this thread before you started your build and, at the time, you clearly didn't anticipate any issues with neighbors so this kind of response is definitely going to be disheartening.

I will say that IF you had mentioned that you are a fan of bass heavy movies AND that you have close neighbors, then you certainly would have gotten a stronger response of the inadequacy of QuietRock and insulation. Containing LFE is the hardest part of soundproofing and there are no easy fixes. As you are seeing, just using a simple layer like that does very very little for LFE.

Bob's suggestion of just reducing your LFE output or watching them quieter is the best short term solution. Long term, you'd have to spend a decent amount of money and possibly undo some of your existing work in order to hit your newly refined goals.

To combat LFE, you'll need lots more mass and to also decouple your walls. You can get away with not decoupling, but it would require even more egregious amounts of mass.

No kind of acoustical panel will help you in any meaningful way. Adding more layers of OSB will help, especially if you apply Green Glue in between the layers. I'm not sure what local codes would say about decoupling the outside wall, so that might not be an option. Doing it on the inside would require ripping up your QuietRock, which would be no fun at all.

I strongly suggest you give Ted and John and The Soundproofing Company a call to discuss some options.


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## cw5billwade

Reefdvr27 said:


> Well I finished my theater and sat down with my wife and we watched my first movie which was EOT and a half hour later the police came and asked me to turn it down. I have been playing bass heavy movies for years and nobody has ever said a thing. I move one room over and now I get a complaint.
> 
> I used quiet rock and Roxul and thought that would be just fine as I did not care about sound in the house. Is there anyway I can sound proof the outside? If I took down the siding and add more layers of plywood and any kind of acoustical panels with it? This really sucks when I asked the guy next door to come over and tell me if he could hear the theater, but instead he just calls the cops. I am so pissed off now a years worth of work and waiting and now the room just sits there.


I think we should point anyone who has a question on whether sound proofing is worth the expense and effort to you.

Also they do make a siding that has insulation in it I was looking at that when I built my house. It is like R9 or something. Refresh my memory did you close in the windows. If not I would look at doing that as well. Get rid of all the holes in the room would go a long way. Check my window plug but if you are going to put insulated siding on the exterior I would eliminate the windows all together.

Do another layer of 5/8” DW and GG all around. I would consider decoupling the ceiling though. Maybe some base traps in all four corners as well.


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## Mfusick

I can't believe I've never seen this thread. Is that possible ?


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## Nightlord

Mfusick said:


> I can't believe I've never seen this thread. Is that possible ?


No


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## smuggymba

Hello Guys,

I was planning on sound proofing my media room but had to drop the idea because of cost. 

Still considering using a serenity mat on the floor to prevent any vibrations from the subs etc. Will that do any good? can I just use serenity mat and place pad/carpet over it?

Thx


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## granroth

smuggymba said:


> I was planning on sound proofing my media room but had to drop the idea because of cost.
> 
> Still considering using a serenity mat on the floor to prevent any vibrations from the subs etc. Will that do any good? can I just use serenity mat and place pad/carpet over it?


Probably not. Serenity Mat (and Acoustik Mat and the like) are primarily ways of introducing decoupling and perhaps some constrained layer damping on the floor. Both require an upper layer of something rigid and with mass, like OSB. Using it with just carpet would do _something_ but I don't know that there's any tests to show the results. You'd need to call the Soundproofing Company to see if they have any product-specific advice related to that.

Putting down Serenity Mat + OSB + Carpet would absolutely do some good, but maybe not as much as you'd like. Soundproofing really needs to be done as a cohesive whole to be truly effective. Quite a bit of sound would still flank around all that and travel to the downstairs via your walls. I mean, you would absolutely be blocking some amount of the sound with the floating floor -- just not as much as you might otherwise expect.


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## smuggymba

granroth said:


> Probably not. Serenity Mat (and Acoustik Mat and the like) are primarily ways of introducing decoupling and perhaps some constrained layer damping on the floor. Both require an upper layer of something rigid and with mass, like OSB. Using it with just carpet would do _something_ but I don't know that there's any tests to show the results. You'd need to call the Soundproofing Company to see if they have any product-specific advice related to that.
> 
> Putting down Serenity Mat + OSB + Carpet would absolutely do some good, but maybe not as much as you'd like. Soundproofing really needs to be done as a cohesive whole to be truly effective. Quite a bit of sound would still flank around all that and travel to the downstairs via your walls. I mean, you would absolutely be blocking some amount of the sound with the floating floor -- just not as much as you might otherwise expect.


Thanks granroth.


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## Reefdvr27

cw5billwade said:


> I think we should point anyone who has a question on whether sound proofing is worth the expense and effort to you.
> 
> Also they do make a siding that has insulation in it I was looking at that when I built my house. It is like R9 or something. Refresh my memory did you close in the windows. If not I would look at doing that as well. Get rid of all the holes in the room would go a long way. Check my window plug but if you are going to put insulated siding on the exterior I would eliminate the windows all together.
> 
> Do another layer of 5/8” DW and GG all around. I would consider decoupling the ceiling though. Maybe some base traps in all four corners as well.


Thanks BIll. I have plans here, it is just going to take a while. I was looking at Mass loaded Vinyl. I thought maybe if I took the siding down and added that and another layer of OSB, that it will help cut down the sound. Yes, I left two windows in and now wish I did not. I think in the end I am going to get a dumpster and rip it all out and start over again. It will probably cost about $4k to fix it, but I want to be sure it will work. Somebody told me even decoupling the walls would not stop bass from going out of the walls. If anybody has a game plan for how to stop big bass, I am all ears.


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## kmhvball

Reefdvr27 said:


> If anybody has a game plan for how to stop big bass, I am all ears.


Uh, turn off your Amp, that is sure to stop big bass! Not a good solution, I know... Get a really nice pair of Headphones... darn it, another bad solution.

Call the Soundproofing Company and get their Recommendation... best real answer I can come up with.


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## Nightlord

Reefdvr27 said:


> Well I finished my theater and sat down with my wife and we watched my first movie which was EOT and a half hour later the police came and asked me to turn it down. I have been playing bass heavy movies for years and nobody has ever said a thing. I move one room over and now I get a complaint.


Pity you didn't put all that effort into the original room. Unfortunately this is the kind of thing that can happen.... i'm very sorry to hear it, I had to tear my original one built in 9months for a 2 year rebuild to get proper soundproofing, weighing in at +6 tons or so and costing me way too much extra, so I feel you pain.


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## Nightlord

Reefdvr27 said:


> If anybody has a game plan for how to stop big bass, I am all ears.


Big bass needs big mass. Start thinking in tons...


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## granroth

Reefdvr27 said:


> ... It will probably cost about $4k to fix it, but I want to be sure it will work. Somebody told me even decoupling the walls would not stop bass from going out of the walls. If anybody has a game plan for how to stop big bass, I am all ears.


I am a huge proponent of community advice, DIY design, and the whole nine yards... but in this case, I think you really need to get a pro to create a solution for you. I don't say that lightly, but your case is an excessively difficult one.

You have a case where you play your movies so loud that the sound gets to your neighbor at a high enough volume that he can legitimately lodge a noise complaint against you. Just knocking a few dB off of that will likely not be anywhere near enough. And you're right that bass is very hard to stop. 

All of the standard soundproofing solutions that you could try would help quite a bit and reduce the outgoing sound by a notable amount. Probably not enough, though. And I can't imagine that you'd want to rip out everything and pump in more money only to not have that work, either.

So really, spend some of that money on a pro to get you a design that you can be confident will absolutely work in your specific case.


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## Reefdvr27

kmhvball said:


> Uh, turn off your Amp, that is sure to stop big bass! Not a good solution, I know... Get a really nice pair of Headphones... darn it, another bad solution.
> 
> Call the Soundproofing Company and get their Recommendation… best real answer I can come up with.


 I am talks with them now about sound proofing. I have thought about headphones, but it is hard when I just bought a brand new pair of JTR full range 215's with 4 single 8 surrounds and two ported SI 18" HST subs. 



Nightlord said:


> Pity you didn't put all that effort into the original room. Unfortunately this is the kind of thing that can happen.... i'm very sorry to hear it, I had to tear my original one built in 9months for a 2 year rebuild to get proper soundproofing, weighing in at +6 tons or so and costing me way too much extra, so I feel you pain.


 The reason I did not do it from the start is that I could not find anyone to do it. I mean I guess I could have done it, but I am not a builder. Quiet rock was the easiest solution. Also I have had big bass in my house for years with no complaints. Now I moved out to my theater which was somewhat treated for sound and I am not even using subs. I bought full range speakers that put out big bass, but not compared to what I did have. 



granroth said:


> I am a huge proponent of community advice, DIY design, and the whole nine yards... but in this case, I think you really need to get a pro to create a solution for you. I don't say that lightly, but your case is an excessively difficult one.
> 
> You have a case where you play your movies so loud that the sound gets to your neighbor at a high enough volume that he can legitimately lodge a noise complaint against you. Just knocking a few dB off of that will likely not be anywhere near enough. And you're right that bass is very hard to stop.
> 
> All of the standard soundproofing solutions that you could try would help quite a bit and reduce the outgoing sound by a notable amount. Probably not enough, though. And I can't imagine that you'd want to rip out everything and pump in more money only to not have that work, either.
> 
> So really, spend some of that money on a pro to get you a design that you can be confident will absolutely work in your specific case.


 Well the plan now is to take out the two windows I had left in and fix that all up for the time being. That will be the first step. I have talked to a couple of neighbors and nobody will own up to calling cops. So that means it is the guy that is the furthest from me which makes no sense. I have been watching movies at night still, but I have been watching at half of what I would normally listen at. As I said I hope taking out the windows will help a bit till I can get the room ripped out and refinished. I am just going to do clips DW>GG>DW and a double exterior door. Ted thinks this will be good and help keep the cops away.


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## kmhvball

Sorry to hear about your plans to have to 're-do' the theater... I am still stuck in the process of doing it once, I can't imagine having to largely restart. At least you have some awesome speakers/subs when it is ready to go at full sound level!


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## cory_bowman70

This is my first post, so I'm not sure if this is the correct thread. If it isn't I apologize.

I'm planning several remodeling projects on my home and I've used these forums as a great source of knowledge and ideas. Now I'm hoping to get some feedback on one of my projects.

The previous owner of my home removed an interior partition wall between two smaller bedrooms to create one larger bedroom. I have a 2yr old daughter and a new baby on the way, so we're looking to convert this larger bedroom back into two smaller bedrooms. (See Drawing #1 )

My goals is to isolate the sound between each bedroom as much as possible. The existing walls/floors/ceiling are fairly new (5yrs) and will remain intact. We will however be replacing the two windows and exterior door(s) to the patio as part of this project. (See Drawing #2 )

My challenge is trying to minimize the width of the new wall, while still providing adequate sound isolation. I'm thinking of creating a double stud wall, but turning the studs 90 deg so the face of the stud is parallel to the drywall. I plan to use rubber sill isolators between the existing floor/bottom plate and the ceiling/top Plate. Double 5/8" and Green Glue on each side. Staggered Drywall Seams and Acoustic sealant on all the edges. (See Drawing #3 )

I think this gets me the most benefit in the least amount of space. My primary objective is to allow my future baby to sleep in one room, while we are reading books to our daughter before bedtime. If that baby is asleep I want to minimize the chance of waking him/her.

One big question I have is around the flooring. The room currently has hardwood flooring. I was planning on building the new wall directly over the existing flooring, but now I'm wondering if I should cut a channel in the finish flooring to build the new wall on the subfloor so that any foot traffic will not be transmitted to the other room through the hardwood..

Any feedback would be greatly appreciated, and apologies if this is in the wrong place.

Thanks
Cory


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## pitviper33

cory_bowman70 said:


> This is my first post, so I'm not sure if this is the correct thread. If it isn't I apologize.


No worries Cory. You're in the right place. Welcome to the forums! 

I'm not one of the soundproofing experts here, but I'm sure one of them will chime in with some help soon. The good news I see is that you aren't trying to stop high amplitude, low frequency sounds. I'd think that makes achieving adequate results much easier, even with a few sacrifices that would be viewed as cutting corners in a theater application.

What I will mention is that I have some experience with thin walls using sideways studs. If you plan ahead, you can probably get a standard door casing to work after the double drywall. But be forewarned that these skinny walls aren't without downsides. The biggest downside I ran into was that any electrical work you need to do in that wall in the future will be a total nightmare.


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## granroth

cory_bowman70 said:


> My challenge is trying to minimize the width of the new wall, while still providing adequate sound isolation. I'm thinking of creating a double stud wall, but turning the studs 90 deg so the face of the stud is parallel to the drywall. I plan to use rubber sill isolators between the existing floor/bottom plate and the ceiling/top Plate. Double 5/8" and Green Glue on each side. Staggered Drywall Seams and Acoustic sealant on all the edges. (See Drawing #3 )


I don't know that I'd recommend using an alternate building style. If space is a concern, then you'd be better served by doing either a staggered stud wall or a single wall with clips and channels on both sides. Both would be mildly wider than your proposed wall, but far more structurally acceptable.



> My primary objective is to allow my future baby to sleep in one room, while we are reading books to our daughter before bedtime. If that baby is asleep I want to minimize the chance of waking him/her.
> 
> One big question I have is around the flooring. The room currently has hardwood flooring. I was planning on building the new wall directly over the existing flooring, but now I'm wondering if I should cut a channel in the finish flooring to build the new wall on the subfloor so that any foot traffic will not be transmitted to the other room through the hardwood..


Well, soundproofing is all about setting a goal and finding the solution that can meet that goal. In your case, your goal is to mute or dampen voice and foot traffic. You're presumably not going to be installing an 18" subwoofer in your daughter's bedroom. In that case, your wall solution (as-is or built closer to a recognized code) would be more than adequate. In fact, it's entirely possible that your voice would be completely inaudible in the other room, if only going through the wall.

Your main issues will be the flanking paths. There are two primary ones -- vents and doors. If you have ducts that connect the two rooms, then sound will absolutely travel through those between the rooms. Likewise, if you have standard hollow core doors with .75" gaps on the bottom, then your voice will absolutely go out one door and in the other.

To mitigate those factors, make sure your ducts are adequately separated, so there's not a direct path between the rooms. Then, get solid core doors to start. If noise is still getting through at an unacceptable rate, then you can consider sealing them. That can even be a temporary thing, which could be removed at nighttime or so.


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## Reefdvr27

kmhvball said:


> Sorry to hear about your plans to have to 're-do' the theater... I am still stuck in the process of doing it once, I can't imagine having to largely restart. At least you have some awesome speakers/subs when it is ready to go at full sound level!


 Well in my mind what I had to do to get this room refitted for a theater was a lot of work. To go in and take out the sheetrock and re install it is not that big of a deal. I am going to try a few things first and see if that helps, if not, back to 101. The only thing I am worried about is, now that I have had the room some of the luster has worn off, I hope I can get motivation to finish is a quickly manner. 

Here are a few pics of the finished room with my speakers. I have the new JTR 215's which are incredible along with a pair of ported SI HST 18" subs. I also have a pair of PSA Triax's, will decide which subs I will use when I am at that point. 

http://www.avsforum.com/forum/19-de...1-shoreline-theater-build-4.html#post28458593


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## cgott42

I've finished my soundproofing, my walls are a 2x DW+GG and decoupled via whisper clips attached to ceiling joists - I want to hang my surround speakers (Def tech 8080dp) by screwing in a screw and hanging the speaker directly on the screw.
Can I screw into a wall stud on this decoupled wall or should I make sure to avoid studs and screw into the DW w/anchor?


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## granroth

cgott42 said:


> I've finished my soundproofing, my walls are a 2x DW+GG and decoupled via whisper clips attached to ceiling joists - I want to hang my surround speakers (Def tech 8080dp) by screwing in a screw and hanging the speaker directly on the screw.
> Can I screw into a wall stud on this decoupled wall or should I make sure to avoid studs and screw into the DW w/anchor?


No, never screw anything into the studs other than the clips. Screwing the hangers directly on the studs will short-circuit your decoupling efforts. Probably not by a lot and maybe not even noticeable... but it's hard to predict, and why risk it?

An anchor might work, especially if you seal any excess hole it makes. I believe the canonical way of doing it, though, is to screw into the channels. That maintains your decoupling and doesn't introduce an unnecessarily big hole into your drywall (depending on the size of the anchor).


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## cgott42

Sorry - I wasn't clear - my wall is a wood frame attached to the ceiling via whisper clips. My question is if it's OK to attach the screw into the wall frame (since it's ultimately detached from the house joists via the whisper clips) or since there's no possible 100% decoupling- it's best to ptu the screw into the DW (w/an anchor) since it's further removed from the chain to the house joist (or if that's unneccessary overkill)?

thx!


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## plissken99

So I'm about to frame the basement. Guy I know has a big roll of "sound barrier" which one strip goes under the bottom floor beam and another over the top. The idea is it decouples the walls so lfe can't travel up and into the house. Anyone know if it'll make a huge difference or not?


----------



## granroth

cgott42 said:


> Sorry - I wasn't clear - my wall is a wood frame attached to the ceiling via whisper clips. My question is if it's OK to attach the screw into the wall frame (since it's ultimately detached from the house joists via the whisper clips) or since there's no possible 100% decoupling- it's best to ptu the screw into the DW (w/an anchor) since it's further removed from the chain to the house joist (or if that's unneccessary overkill)?


Ah, okay. I've never heard of a wall referred to as a "wood frame", so that threw me.

Yes, screw directly into the studs since that entire assembly is decoupled. A speaker hanging on the wall has no opportunity to re-couple the wall to something else. Using an anchor would not do any better and might actually create a very minor leakage problem.


----------



## granroth

plissken99 said:


> So I'm about to frame the basement. Guy I know has a big roll of "sound barrier" which one strip goes under the bottom floor beam and another over the top. The idea is it decouples the walls so lfe can't travel up and into the house. Anyone know if it'll make a huge difference or not?


There's no such thing as a "sound barrier" that can be applied as a strip to bottom or top plates. Sounds like snake oil to me.

In general, there is no easy solution for containing LFE. Any solution that claims that some thin substrate will make any appreciable difference is almost surely peddling nonsense.


----------



## plissken99

"Sound Barrier" is just the name of the product apparently. 

Obviously no one thing stops lfe, this just might be another thing to help that effort. Why is everyone in this section so stand-offish?


----------



## granroth

Hmm... since I was the one that replied, I have to assume that my reply was stand-offish? If it was, then it certainly wasn't intentional, nor do I quite see what you are seeing. C'est la vie.


----------



## cw5billwade

plissken99 said:


> "Sound Barrier" is just the name of the product apparently.
> 
> Obviously no one thing stops lfe, this just might be another thing to help that effort. Why is everyone in this section so stand-offish?


Do you have a link? It may be ok on the floor (better than nothing) but I would still decouple the top with IB-3 clips or something.


----------



## ClemsonJeeper

cgott42 said:


> Sorry - I wasn't clear - my wall is a wood frame attached to the ceiling via whisper clips. My question is if it's OK to attach the screw into the wall frame (since it's ultimately detached from the house joists via the whisper clips) or since there's no possible 100% decoupling- it's best to ptu the screw into the DW (w/an anchor) since it's further removed from the chain to the house joist (or if that's unneccessary overkill)?
> 
> thx!


How is your wall decoupled from the ceiling with whisper clips? I thought that Whisper clips are for hanging drywall hat channel that you then screw drywall to. Do you mean you decoupled the wall from the ceiling using IB-3 brackets?

If so, then yes, you can screw directly into the studs at that point (assuming your drywall is screwed directly to the studs as well)


----------



## paries

*using 2 sided foam tape instead green glue*

*Question:* Has anyone used doubleside foam tape between the drywall instead of the green glue.. 
I am building my room that i would like to soundproof as much as possible.
My plan is to double drywall.

I have two questions.

1) I was planning on doing the double drywall and using the green glue between the panels, but someone suggested using 2 sided foam tape instead which would be considerably cheaper. Is this a viable/cheaper option?? 

2) does 5/8 verses 1/2 make a big difference?

thanks for your comments


----------



## mvanmeter

*Reducing Train Noise?*

I have a condo in Chicago that backs up to an elevated train line - the line is about 30 feet off the ground, and 30 feet from the property. My unit is on the first floor of a 3 story, 6 unit (2 per floor) 105-year old building, with a block basement, and brick walls on all other floors, framed inside with 2x4 studs and drywall . I'm trying to turn the back room into a city-dwellers version of a home theater, and as such don't expect complete quiet (it's open to the hallway/kitchen, so that's impossible), but would like to minimize the train noise (you don't feel it, you definitely hear it). I was thinking of ripping down the drywall on the two outside facing walls in that room, re-insulating (currently has blown-in insulation), then putting up drywall clips before attaching two sheets of 5/8" drywall with green glue in between. There are two windows in the space, on angled walls (think half a hexagon) - double paned, vinyl clad. Was going to put black-out curtains over those to reduce noise/light. Current sound level when trains go by is 70-75 decibels, with most of the noise in the 200-1K Hz range. Is there anything else I can do to reduce the noise, i.e. adding mass-loaded vinyl on the studs before I put in the drywall etc? 

Any help would be appreciated - hope to start tear out this weekend!

Mike


----------



## granroth

paries said:


> *Question:* Has anyone used doubleside foam tape between the drywall instead of the green glue..
> I am building my room that i would like to soundproof as much as possible.
> My plan is to double drywall.
> 
> I have two questions.
> 
> 1) I was planning on doing the double drywall and using the green glue between the panels, but someone suggested using 2 sided foam tape instead which would be considerably cheaper. Is this a viable/cheaper option??
> 
> 2) does 5/8 verses 1/2 make a big difference?
> 
> thanks for your comments


1. I've never heard of the suggestion to replace Green Glue with foam tape. The only 2 sided foam tape I'm aware of is very narrow (like this), so I'm not sure how it would be possible to completely blanket the wall with it. Seems like it would be very expensive to get that many rolls. In general, foam isn't serving the same purpose as Green Glue, either, so I'd be dubious without any proof that it would work similarly. I am curious what the reasoning behind the suggestion is.

2. 5/8" absolutely makes a big difference compared to 1/2". Check out the NRC research links at the beginning of this thread. They conducted extensive tests using various sizes of drywall (among many other variations). The TL;DR is that 5/8" is definitely worth it.


----------



## granroth

mvanmeter said:


> I have a condo in Chicago that backs up to an elevated train line - the line is about 30 feet off the ground, and 30 feet from the property. My unit is on the first floor of a 3 story, 6 unit (2 per floor) 105-year old building, with a block basement, and brick walls on all other floors, framed inside with 2x4 studs and drywall . I'm trying to turn the back room into a city-dwellers version of a home theater, and as such don't expect complete quiet (it's open to the hallway/kitchen, so that's impossible), but would like to minimize the train noise (you don't feel it, you definitely hear it). I was thinking of ripping down the drywall on the two outside facing walls in that room, re-insulating (currently has blown-in insulation), then putting up drywall clips before attaching two sheets of 5/8" drywall with green glue in between. There are two windows in the space, on angled walls (think half a hexagon) - double paned, vinyl clad. Was going to put black-out curtains over those to reduce noise/light. Current sound level when trains go by is 70-75 decibels, with most of the noise in the 200-1K Hz range. Is there anything else I can do to reduce the noise, i.e. adding mass-loaded vinyl on the studs before I put in the drywall etc?


Clip and channel mounted double layers of 5/8" drywall with Green Glue will do a fantastic job against that type of noise, so you're well on your way. After those walls go up, your primary concern will be flanking -- does the sound go around your walls to intrude in some other fashion?

The obvious flanking method will be your windows. I suggest that you start with black-out curtains and see (hear) what kind of difference it makes. If it's good enough, then stop there. If too much sound is still intruding, then consider making some window plugs to match the same density as your walls. There are a couple of window plugs described in the beginning of this thread.

As far as using MLV... I'm not aware of people using both MLV and Green Glue. In general, use of MLV really went down with the advent of Green Glue since the latter did a better job at less cost. Adding MLV in your case might still help, but it seems like it would be overkill.


----------



## cgott42

granroth said:


> Ah, okay. I've never heard of a wall referred to as a "wood frame", so that threw me.
> 
> Yes, screw directly into the studs since that entire assembly is decoupled. A speaker hanging on the wall has no opportunity to re-couple the wall to something else. Using an anchor would not do any better and might actually create a very minor leakage problem.


thx


----------



## paries

granroth said:


> 1. I've never heard of the suggestion to replace Green Glue with foam tape. The only 2 sided foam tape I'm aware of is very narrow (like this), so I'm not sure how it would be possible to completely blanket the wall with it. Seems like it would be very expensive to get that many rolls. In general, foam isn't serving the same purpose as Green Glue, either, so I'd be dubious without any proof that it would work similarly. I am curious what the reasoning behind the suggestion is.
> 
> 2. 5/8" absolutely makes a big difference compared to 1/2". Check out the NRC research links at the beginning of this thread. They conducted extensive tests using various sizes of drywall (among many other variations). The TL;DR is that 5/8" is definitely worth it.


granroth-->"I am curious what the reasoning behind the suggestion is."
The idea is that the foam tape creates an air gap between the two pieces of drywall. The person i was talking to suggested 4 or 5 vertical strips per panel the entire length

Thanks


----------



## granroth

paries said:


> granroth-->"I am curious what the reasoning behind the suggestion is."
> The idea is that the foam tape creates an air gap between the two pieces of drywall. The person i was talking to suggested 4 or 5 vertical strips per panel the entire length


Oh, no!!  You never want an air gap between the piece of drywall. That will create something called a "triple leaf effect", which will make your soundproofing notably WORSE rather than better. This PDF explains it pretty well: http://www.greengluecompany.com/sites/default/files/Understanding_theTriple_Leaf_Effect.pdf

The takeaway is this -- if you create a trip leaf in your wall assembly, then you will reduce the soundproofing capability of that wall by a significant percent. You want to avoid that situation like the plague!


----------



## BasementBob

Triple leaf, probably similar to the previous post's PDF, but a little older:http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm


----------



## gdc123

Based on what I see from soundproofing company I am planning to use IB3 brackets for my outside walls that are next to concrete to decouple the wall from the joist and create a double wall. I will have one wall that will be done with clips and channels and is not decoupled from the joist. 

My question is when framing the outside wall you typically attach the end studs to to the joining wall. In this case I would be attaching my decoupled wall to a wall that is not. Should I use the IB-4 bracket to make that connection or is there another method that I have not seen at this point?


----------



## cw5billwade

Is it an elevated train or on the ground. I would think aif on the ground a lot of the noise is comming via the ground into the basement then up through the floor. is the basement community property?


----------



## Potatogod93

gdc123 said:


> Based on what I see from soundproofing company I am planning to use IB3 brackets for my outside walls that are next to concrete to decouple the wall from the joist and create a double wall. I will have one wall that will be done with clips and channels and is not decoupled from the joist.
> 
> My question is when framing the outside wall you typically attach the end studs to to the joining wall. In this case I would be attaching my decoupled wall to a wall that is not. Should I use the IB-4 bracket to make that connection or is there another method that I have not seen at this point?


Based off what I've been told this week by Ted from Soundproofing co is that you only need to IB-3 clip the walls on the interior of the room. The walls next to concrete need to be an inch away from the concrete but they can tie into wall joists with a normal bolt. If would only need to be the interior walls next to a double wall that needs to get IB-3 clipped to the joist. 

As far as the second part since those two walls are part of the inside shell and decoupled from the other walls I think it is fine to couple them together.


----------



## gdc123

cw5billwade said:


> Is it an elevated train or on the ground. I would think aif on the ground a lot of the noise is comming via the ground into the basement then up through the floor. is the basement community property?



It's a house with a basement, my kids rooms are right above the theater.. I am the most worried about sound going up while they are sleeping.. I plan to decouple and insulate the ceiling to.


----------



## kmhvball

gdc123 said:


> Based on what I see from soundproofing company I am planning to use IB3 brackets for my outside walls that are next to concrete to decouple the wall from the joist and create a double wall. I will have one wall that will be done with clips and channels and is not decoupled from the joist.
> 
> My question is when framing the outside wall you typically attach the end studs to to the joining wall. In this case I would be attaching my decoupled wall to a wall that is not. Should I use the IB-4 bracket to make that connection or is there another method that I have not seen at this point?





Potatogod93 said:


> Based off what I've been told this week by Ted from Soundproofing co is that you only need to IB-3 clip the walls on the interior of the room. The walls next to concrete need to be an inch away from the concrete but they can tie into wall joists with a normal bolt. If would only need to be the interior walls next to a double wall that needs to get IB-3 clipped to the joist.
> 
> As far as the second part since those two walls are part of the inside shell and decoupled from the other walls I think it is fine to couple them together.


I used IB-3 clips at the Top of my walls bordering the Concrete Walls, so they were decoupled from the Floor Joists. I did not 'attach' anything to the exterior wall, just the IB-3 clips to the floor joist.

I would think if you had one wall that was de-coupled, and attached it to another wall that was coupled, you would want to use some sort of isolation clip to avoid flanking. I am not sure I exactly follow the question though.


----------



## Potatogod93

kmhvball said:


> I used IB-3 clips at the Top of my walls bordering the Concrete Walls, so they were decoupled from the Floor Joists. I did not 'attach' anything to the exterior wall, just the IB-3 clips to the floor joist.
> 
> I would think if you had one wall that was de-coupled, and attached it to another wall that was coupled, you would want to use some sort of isolation clip to avoid flanking. I am not sure I exactly follow the question though.


No, you're right, but what I was trying to tell him is if both walls are a decoupled piece of the inside shell then they should be ok to couple together. As long as its not coupling back to the outside room as a room within a room.

I think my first part I said needs clarification, though. I was told that I did not need IB-3 Clips on the walls next to the concrete walls in the basement. I should ask him why though before I order it may be a misunderstanding on my part.


----------



## cw5billwade

mvanmeter said:


> I have a condo in Chicago that backs up to an elevated train line - the line is about 30 feet off the ground, and 30 feet from the property. My unit is on the first floor of a 3 story, 6 unit (2 per floor) 105-year old building, with a block basement, and brick walls on all other floors, framed inside with 2x4 studs and drywall . I'm trying to turn the back room into a city-dwellers version of a home theater, and as such don't expect complete quiet (it's open to the hallway/kitchen, so that's impossible), but would like to minimize the train noise (you don't feel it, you definitely hear it). I was thinking of ripping down the drywall on the two outside facing walls in that room, re-insulating (currently has blown-in insulation), then putting up drywall clips before attaching two sheets of 5/8" drywall with green glue in between. There are two windows in the space, on angled walls (think half a hexagon) - double paned, vinyl clad. Was going to put black-out curtains over those to reduce noise/light. Current sound level when trains go by is 70-75 decibels, with most of the noise in the 200-1K Hz range. Is there anything else I can do to reduce the noise, i.e. adding mass-loaded vinyl on the studs before I put in the drywall etc?
> 
> Any help would be appreciated - hope to start tear out this weekend!
> 
> Mike





cw5billwade said:


> Is it an elevated train or on the ground. I would think aif on the ground a lot of the noise is comming via the ground into the basement then up through the floor. is the basement community property?





gdc123 said:


> It's a house with a basement, my kids rooms are right above the theater.. I am the most worried about sound going up while they are sleeping.. I plan to decouple and insulate the ceiling to.


Sorry @gdc123 I was asking that to @mvanmeter


----------



## cw5billwade

Potatogod93 said:


> No, you're right, but what I was trying to tell him is if both walls are a decoupled piece of the inside shell then they should be ok to couple together. As long as its not coupling back to the outside room as a room within a room.
> 
> I think my first part I said needs clarification, though. I was told that I did not need IB-3 Clips on the walls next to the concrete walls in the basement. I should ask him why though before I order it may be a misunderstanding on my part.


you difently want IB3 Clips on the walls next to the concret other wise the wall is not decoupled from the rest of the house. I think there was a misunderstanding.


----------



## cw5billwade

gdc123 said:


> Based on what I see from soundproofing company I am planning to use IB3 brackets for my outside walls that are next to concrete to decouple the wall from the joist and create a double wall. I will have one wall that will be done with clips and channels and is not decoupled from the joist.
> 
> My question is when framing the outside wall you typically attach the end studs to to the joining wall. In this case I would be attaching my decoupled wall to a wall that is not. Should I use the IB-4 bracket to make that connection or is there another method that I have not seen at this point?


This is what I would do unless you just build a second decoupled wall (double wall) which would be superior and less expensive then clips and channel. Then they can conect to it since all 4 walls now have IB3 clips seperating them from the joists. You only give up about 3" that way. Look at my rear wall in my build. it was so much easier then the other 3 walls which had clips and channel.


----------



## gdc123

cw5billwade said:


> This is what I would do unless you just build a second decoupled wall (double wall) which would be superior and less expensive then clips and channel. Then they can conect to it since all 4 walls now have IB3 clips seperating them from the joists. You only give up about 3" that way. Look at my rear wall in my build. it was so much easier then the other 3 walls which had clips and channel.



I would like to build a second wall but I have some pipes and electrical that were ran outside the joist along that wall which is a support wall. I would have to come out about 9 inches to be able to get a good connection to the joist with the IB3. Could I build the second wall and use IB4 and skip the IB3 or do I need that connection to the joist?

Looking at your build I did not see the IB3 attached to the joist but instead the other all looks like I might be able to build a second wall after all.

I plan to use the IB2 EXT to drop the ceiling past those pipes.

It does sound like the best way to secure the decoupled wall to the coupled all is the IB4.


----------



## cw5billwade

gdc123 said:


> I would like to build a second wall but I have some pipes and electrical that were ran outside the joist along that wall which is a support wall. I would have to come out about 9 inches to be able to get a good connection to the joist with the IB3. Could I build the second wall and use IB4 and skip the IB3 or do I need that connection to the joist?
> 
> Looking at your build I did not see the IB3 attached to the joist but instead the other all looks like I might be able to build a second wall after all.
> 
> I plan to use the IB2 EXT to drop the ceiling past those pipes.
> 
> It does sound like the best way to secure the decoupled wall to the coupled all is the IB4.


yes you can use IB-3 clip and conect it to the load bearing wall and since it and the front and back walls are all decoupled you can nail or screw it directly to them. Make thoes walls 1" short load bearing wall. I think that is a good plan. A way to handle the plumbing is in a soffit that is decoupled much the same way you could nail the bottom of the soffit frame directy to your wall since it is decoupled and the top part of the soffit frame (toward middle of room) could be following one of the ceiling joist and use IB3 clips. If that is too wide then you could just put nailers between the joist where the IB3 Clips go (i.e. every 48"). Is that what you meant by IB4 clips?

I hope that makes sence


----------



## gdc123

cw5billwade said:


> yes you can use IB-3 clip and conect it to the load bearing wall and since it and the front and back walls are all decoupled you can nail or screw it directly to them. Make thoes walls 1" short load bearing wall. I think that is a good plan. A way to handle the plumbing is in a soffit that is decoupled much the same way you could nail the bottom of the soffit frame directy to your wall since it is decoupled and the top part of the soffit frame (toward middle of room) could be following one of the ceiling joist and use IB3 clips. If that is too wide then you could just put nailers between the joist where the IB3 Clips go (i.e. every 48"). Is that what you meant by IB4 clips?
> 
> I hope that makes sence


Thanks for the help, I will need to make the inner wall about 2 inches shorter in order to be under the pipes in that location. The IB4 is a little different then the IB3, but from your pics I think either would work. Then I will use the IB2ext to match the ceiling height with the inner wall height..


----------



## cw5billwade

you sure you want to lose 2" on entire ceiling?


----------



## gdc123

I have a deep poured basement I have just under nine feet to work with..


----------



## Brian Fineberg

Quick question. I'm starting my build soon. Unfinished basement. I would want to start with the ceiling correct? Use clips and channels dd + gg. THEN build the wall frames an inch from foundation? With those frames put into the existing ceiling? Am I right in this?


----------



## cw5billwade

Brian Fineberg said:


> Quick question. I'm starting my build soon. Unfinished basement. I would want to start with the ceiling correct? Use clips and channels dd + gg. THEN build the wall frames an inch from foundation? With those frames put into the existing ceiling? Am I right in this?


First you frame wall using IB-3 clips decoupled from the floor joist. Then clips and channel on ceiling. You do the first layer of DW on ceiling then first layer on walls. Then second layer with green glue on ceiling then walls. I used OSB on my first layer. Insure you use 5/8" DW


----------



## ClemsonJeeper

Brian Fineberg said:


> Quick question. I'm starting my build soon. Unfinished basement. I would want to start with the ceiling correct? Use clips and channels dd + gg. THEN build the wall frames an inch from foundation? With those frames put into the existing ceiling? Am I right in this?


Nope.

Frame the room fully first. For walls on cement foundation, put them 1" from the foundation and 1" from the joists. Use IB3 brackets to attach the walls to the joists (follow specifications on spacing of brackets). 

Once all walls are framed, hang clips + channels where needed (ceiling and any walls that aren't decoupled from the house). 

After that, hang drywall on ceiling first, then walls, then acoustic caulk where the ceilings meet the walls and the corners of the walls, as well as the floor to wall gaps. Then hang ceiling + GG, then walls again with GG. Then caulk all gaps again.


----------



## Brian Fineberg

Thanks to both of you!! Not sure why I had a brain fart like that


----------



## cw5billwade

Brian Fineberg said:


> Thanks to both of you!! Not sure why I had a brain fart like that


No issue we are here to help


----------



## Brian Fineberg

So I emailed the guys at soundproofing. But my room will be 13x15 with one standard door. How many IB3's will I need for the framing


----------



## cw5billwade

Each wall will have one on each end and every 48 inches


----------



## Brian Fineberg

So that sounds like 16 brackets correct?
How much are they per bracket?


----------



## gdc123

5.30 plus shipping is what I was told yesterday.


----------



## BasementBob

cw5billwade said:


> Each wall will have one on each end and every 48 inches


Aren't they rated by weight: effective only over a certain lower weight, and under a certain max weight, per hanger
Usually calculated by weight per square foot of whatever you're hanging on them. (n layers of drywall, cabinets, etc)
The easy way to 'calculate' it, is usually to email the people you're buying them from, giving them the room dimensions (length, width, height), the intent (walls only, ceiling only, walls and ceiling), and how much drywall (one sheet of 5/8" and one sheet of 1.5" QuietRock 545 and one grounded copper mesh layer)


----------



## BasementBob

QuietRock Installation Instructions
http://www.quietrock.com/download.php?file=95.pdf


Also has putty packs, and caulking/backer instructions.


----------



## Brian Fineberg

They replied one every 4-5 linear feet. And more in a doorway


----------



## Knd

*Soundproofing ceiling on single story house*

Is it necessary to soundproof the ceiling of a theater room in a one story house that will have R-38 insulation above?


----------



## cw5billwade

BasementBob said:


> Aren't they rated by weight: effective only over a certain lower weight, and under a certain max weight, per hanger
> Usually calculated by weight per square foot of whatever you're hanging on them. (n layers of drywall, cabinets, etc)
> The easy way to 'calculate' it, is usually to email the people you're buying them from, giving them the room dimensions (length, width, height), the intent (walls only, ceiling only, walls and ceiling), and how much drywall (one sheet of 5/8" and one sheet of 1.5" QuietRock 545 and one grounded copper mesh layer)


 Just going by what the instructions said. One in each corner and ever 48" so his 15' Wall would require 5 IB3 Clips.


Brian Fineberg said:


> They replied one every 4-5 linear feet. And more in a doorway


I didn't mention each side of door because he is dong clips and channel on that wall. If you were doing room in room or double wall then yes 1 on each side of door.


----------



## mvanmeter

granroth said:


> Clip and channel mounted double layers of 5/8" drywall with Green Glue will do a fantastic job against that type of noise, so you're well on your way. After those walls go up, your primary concern will be flanking -- does the sound go around your walls to intrude in some other fashion?
> 
> The obvious flanking method will be your windows. I suggest that you start with black-out curtains and see (hear) what kind of difference it makes. If it's good enough, then stop there. If too much sound is still intruding, then consider making some window plugs to match the same density as your walls. There are a couple of window plugs described in the beginning of this thread.
> 
> As far as using MLV... I'm not aware of people using both MLV and Green Glue. In general, use of MLV really went down with the advent of Green Glue since the latter did a better job at less cost. Adding MLV in your case might still help, but it seems like it would be overkill.


I haven't seen the sound present in any other areas than the drywall and windows, so will definitely have to get window plugs or look at a more expensive option like soundproofwindows.com. I see what you're saying about the MLV - might skip that to cut down costs. One other question around the insulation in the walls - given the age of the building, it's not the best insulated, and I worry that simple r-13 won't help much. Was debating using spray-in insulation, but I've read on here that could cause more sound transmission, rather than decrease it? Would a better solution be 1" foil-faced figid foam, sealed around the edges with good stuff, then r-13 batt over it?



cw5billwade said:


> Is it an elevated train or on the ground. I would think aif on the ground a lot of the noise is comming via the ground into the basement then up through the floor. is the basement community property?


The train is elevated, about 25 feet in the air, and connected to the concrete in alley via a steel frame. The basement is community property, though I have requested permission to at least insulate the floor joists, since right now the basement is open to my sub-floor.


----------



## cw5billwade

mvanmeter said:


> I haven't seen the sound present in any other areas than the drywall and windows, so will definitely have to get window plugs or look at a more expensive option like soundproofwindows.com. I see what you're saying about the MLV - might skip that to cut down costs. One other question around the insulation in the walls - given the age of the building, it's not the best insulated, and I worry that simple r-13 won't help much. Was debating using spray-in insulation, but I've read on here that could cause more sound transmission, rather than decrease it? Would a better solution be 1" foil-faced figid foam, sealed around the edges with good stuff, then r-13 batt over it?
> 
> no regular R13 is better than blown in for Sound but not for R value. R15 can go into a 2x4 stud wal and is a little denser that is how I dind my house when we built it. If you are taking DW down then I would do the R15.
> 
> The train is elevated, about 25 feet in the air, and connected to the concrete in alley via a steel frame. The basement is community property, though I have requested permission to at least insulate the floor joists, since right now the basement is open to my sub-floor.


Then I would do the DW strips with GG on the sub floor if they let you Subfloor/GG/DW/GG/DW between each floor joist.


----------



## Brian Fineberg

what should I do with the control panel? can I just attached it to the decoupled wall (built 1" from foundation)? is that even possible?


----------



## granroth

Brian Fineberg said:


> what should I do with the control panel? can I just attached it to the decoupled wall (built 1" from foundation)? is that even possible?


Yes, they can be attached to the decoupled wall (unless your local code forbids that for potential reasons that totally escape me). It wouldn't be pretty, though.

Maybe create a top-level thread for this question on how best to hide control panels inside of a theater? You might get some creative answers from people that wouldn't necessarily be looking in a soundproofing thread.


----------



## Brian Fineberg

few more questions...

What do you screw the second layer into? where should the screws be located?

is there somthing to seal off plates such as Electrical and light switches?

How about can Lighting how do you soundproof those holes?

thsi is alot to ingest especialy the closer I get to actually pulling this off....as far as my elctrical box, I think there is enought play in the wires to attach it directky INSIDE my bunker...


----------



## cw5billwade

1. When you put the first layer up you snap a line where your studs are for decoupled wall and the hat channels for the walls and ceiling using clips. Then using a slightly longer screw you hit the studs for the decoupled walls and the channel with the screw. on the Clips and channel never make the screw to long so it doesn't hit the clip and stud below the channel.

2. putty pads. but most build columns and soffits to run everything in so as to not make holes in the sound envelope

3. backer boxes. 

All have been discussed in this thread


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## Brian Fineberg

than you! Im sure they did I guess I should use the search, but its not very user friendly...thanks again!


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## cw5billwade

don't forget to put putty pads on the room on the other side of the walls outlets


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## Brian Fineberg

does the other side of the framed wall need to be drywalled?


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## cw5billwade

if there is a room on the other side yes if next to the concret then that would be triple leaf so no. In my 2nd floor bonus room I did not put dry wall on the other side of my knee walls. but there is no place for the sound that does escape to go.


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## Brian Fineberg

ok. Well initially the wall that will divide the HT from the rest of the basement wont be drywalled (that will happen when we finish the rest fo the basement off)


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## cw5billwade

that should be ok in the interm. It would be a good test to do before and after on DW on that wall. I used double layer of 5/8" DW on my Billard room wall.


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## granroth

Brian Fineberg said:


> than you! Im sure they did I guess I should use the search, but its not very user friendly...thanks again!


I accept some of the blame for that  I saw how pointless search was on the Acoustical Master Thread and so I resolved that as the Soundproofing Master Thread grew, I'd keep an updated index in the first few posts. Alas, the thread got away from me and I was never able to keep up... and since, I haven't found the time to go back and retrofit the index.

As-is, Google is your best bet for searching the thread.


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## tommylicious

how much of a difference do clips make when added to double drywall with green glue in between?


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## cw5billwade

the clips and channel are what decouple the drywall from the studs. without them then the studs will vibrate with the drywall transmiting sound to the floor joist above.


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## granroth

tommylicious said:


> how much of a difference do clips make when added to double drywall with green glue in between?


A lot. In fact, I tend to think of it as decoupling along with the addition of more drywall plus Green Glue, rather than doubled drywall plus decoupling. That is, the decoupling is more important and makes more of an impact so that's the basis -- everything else just builds on that.

Look at the beginning of this thread for the link to the NRC PDF. There are a ton of example of specific wall assemblies that show how their STC values rate.

In general, if you require a certain level of soundproofing, then find the STC value that you need and build the wall that provides that.


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## Fatshaft

Here's what I learned with my soundproofing my room.
I have hat channels on my ceiling with DD and GG.








I have 3 walls of foundation...again DD and GG.

4th wall has Hat channels with DD and GG. other room on the other side
















Riser and front stage are completely sand filled
















My room is completely sealed.

I can scream on top of my lungs and NOBODY will hear me upstairs (Love this )
This is what the bass does upstairs my room. 
















Just wanting you to keep in mind that the BASS portion will have NO RESPECT for soundproofing [/URL]


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## Brian Fineberg

awesome pics!! thanks it offers a glimpse t help explain.

I am a little concerned about bass now...hmmmm


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## ch1sox

Fatshaft, that's a crazy video with the table! Is that directly above your theater? 

I'm planning for my build and I'm worried about how much sound will transfer through the floor directly above the theater. In your video it seems like your speakers/subs must have been blasting! If you watch a movie can you hear much sound travel through the floor besides the bass? I've been planning for months and plan to use double drywall, green glue and clips/channel. I'm also going to add a layer or two of drywall directly below the subfloor. I'm just hoping this is enough to watch movies at a reasonable level and not disturb anyone directly above. I'm not worried about the bass because in the late evening I can always turn that down.


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## cw5billwade

Fatshaft said:


> Here's what I learned with my soundproofing my room. My room is completely sealed.
> I can scream on top of my lungs and NOBODY will hear me upstairs (Love this )
> This is what the bass does upstairs my room.
> 
> Just wanting you to keep in mind that the BASS portion will have NO RESPECT for soundproofing


Did you do two layers of DW/GG between floor joists? Also what is the ceiling insolation R19?


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## cw5billwade

ch1sox said:


> Fatshaft, that's a crazy video with the table! Is that directly above your theater?
> 
> I'm planning for my build and I'm worried about how much sound will transfer through the floor directly above the theater. In your video it seems like your speakers/subs must have been blasting! If you watch a movie can you hear much sound travel through the floor besides the bass? I've been planning for months and plan to use double drywall, green glue and clips/channel. I'm also going to add a layer or two of drywall directly below the subfloor. I'm just hoping this is enough to watch movies at a reasonable level and not disturb anyone directly above. I'm not worried about the bass because in the late evening I can always turn that down.


you have to realize how much woffage Fat Shaff has LOL and he likes it loud


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## Fatshaft

Brian Fineberg said:


> awesome pics!! thanks it offers a glimpse t help explain.
> 
> I am a little concerned about bass now...hmmmm


Glad to help...
Just wanting people to know that if you play loud, the bass will travel through pretty much anything!



ch1sox said:


> Fatshaft, that's a crazy video with the table! Is that directly above your theater?


Yes



> I'm planning for my build and I'm worried about how much sound will transfer through the floor directly above the theater. In your video it seems like your speakers/subs must have been blasting!


You have no idea ! In the video the volume is at 10DB OVER reference volume.



> If you watch a movie can you hear much sound travel through the floor besides the bass? I've been planning for months and plan to use double drywall, green glue and clips/channel. I'm also going to add a layer or two of drywall directly below the subfloor. I'm just hoping this is enough to watch movies at a reasonable level and not disturb anyone directly above. I'm not worried about the bass because in the late evening I can always turn that down.


Ok here's the deal...
Once all done...DD Hat Channel GG insulation between the joists...at reference volume (105DB) you WON'T hear mid to high frequencies.
If a movie is playing all you'll hear are some rumbles (Bass) anything above (voices) you will NOT hear.
Action movies, you'll hear whatever your subs are doing but it isn't loud...It really is acceptable upstairs.
If you're watching a chick flick...you won't even know there's a movie playing downstairs.

Keep in mind, I pretty sure most people think I'm crazy as I listen to movies with peaks over 130DB's. (Bass)
Nothing will stop the bass with the amount of subs I have. (I need a concrete bunker)

This is despite my subs being on a completely sand filled riser, a completely sand filled stage of which none are touching any of the walls.
My stage and riser are ONLY touching the ground and are about 8 inches from the ground with sand in between the sub and ground!

Again, if you listen at NORMAL levels you'll be VERY impressed how good the sound is contained within the theater room.



cw5billwade said:


> Did you do two layers of DW/GG between floor joists? Also what is the ceiling insolation R19?


Yes R19 above.
No DW/GG between the floor joists.

We are planing to redo the floors upstairs and once there I will re-enforce my flooring.
It might be a waist of energy IMO, cause I simply just have too much bass to contain.


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## cw5billwade

Fatshaft said:


> We are planing to redo the floors upstairs and once there I will re-enforce my flooring.
> It might be a waist of energy IMO, cause I simply just have too much bass to contain.


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## ch1sox

Good to hear Fatshaft. I just find it amazing how much sound is stopped by using two pieces of drywall with GG attached to clips/channel.


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## granroth

That is a fantastic video for illustrating just how difficult it can get to contain bass! I have some videos of picture frames on walls buzzing but nothing can top a table skittering across the floor 

If you follow Fatshaft's original post about this a couple years ago, there's a link to this thread, which is excellent:

http://www.avsforum.com/forum/19-de...ound-theater-how-contain-low-frequencies.html

Essentially you have Dennis and Ted opining on ways of containing bass at 30Hz, 20Hz, and even 10Hz. The TL;DR is that it's impractical for anybody with a theater not a concrete bunker to contain 10Hz and difficult to contain 20Hz. For 30Hz or so, then you're looking at a decoupled wall (should be doing that anyway) and 3 or 4 layers of drywall rather than the customary 2.


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## MVG

Dear enthousiasts!

after a lot of reading around on the forum this will be my first post, because since i've read a lot about soundproofing AND IB subwoofers over here and the cult I just can't let it rest to ask you about something that is on my mind for 2 days now. Used search engine and reading IB faq etc etc..

Here it goes:
let's assume i've the situation i will build my hometheater in the garage at the back of my yard (free standing building/not attached to the house). 

It is made out of concrete and brick walls and is not isolated yet. Since i have to insulate (thermal) it for having a nice warm space and all i am planning to soundproof it also so that neigbours will not hear anything. And for the purpose of having a whisper quet room for myself. This garage has a wooden attic. An attic i could build an IB subwoofer in. The roof is angled. So i am thinking to keep the attic and place the new ceiling right under the existing floor joists (decoupled of course)

My question, when i am done soundproofing the walls, ceiling and floor etc, i will have an acoustically sealed room. And then if I make a hole in the ceiling for an IB sub (using a manifold) will I just have done all the soundproofing for nothing? Because the hole will be the weak link? Like electrical outlets that are not sealed properly. In other words, I am having the idea that making holes for IB subs is ruining the soundproofing of the room.

Could someone explain me something about this? Since I have read about IB subs it is hard to stop thinking about haha.

Please ignore any improper written language, i'm Dutch ;-)


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## pitviper33

I'm not one of the soundproofing experts in here, so maybe one of those guys can chime in with his perspective. But I do have some experience with IB subwoofers. The manifold itself shouldn't be a very big leak path. Typical manifold construction is 1.5" thick solid wood. This is somewhat similar to the solid core doors often recommended for soundproof rooms, and I'd expect it to perform similarly. The bigger leak path is probably the surface of the driver itself.


But let me make sure you understand this part. An infinite baffle subwoofer is just as loud in its backspace as it is in your room. So with the design you've described, you aren't keeping the bass inside the room at all. If your goal in soundproofing is to keep your room's noise floor low, this isn't a problem. But if your goal was to save the neighbors and your main house from hearing the sounds of your theater, using an IB subwoofer with a non-soundproofed backspace is a huge hole in that plan.


----------



## MVG

pitviper33 said:


> I'm not one of the soundproofing experts in here, so maybe one of those guys can chime in with his perspective. But I do have some experience with IB subwoofers. The manifold itself shouldn't be a very big leak path. Typical manifold construction is 1.5" thick solid wood. This is somewhat similar to the solid core doors often recommended for soundproof rooms, and I'd expect it to perform similarly. The bigger leak path is probably the surface of the driver itself.
> 
> 
> 
> But let me make sure you understand this part. An infinite baffle subwoofer is just as loud in its backspace as it is in your room. So with the design you've described, you aren't keeping the bass inside the room at all. If your goal in soundproofing is to keep your room's noise floor low, this isn't a problem. But if your goal was to save the neighbors and your main house from hearing the sounds of your theater, using an IB subwoofer with a non-soundproofed backspace is a huge hole in that plan.


Thank you for the good info on that! I was alreeds thinking about that, but indeed assumed wrongly that that would not be à big problem sinds i have read sometimes that the backwave did not was à problem... Was keeping in mind that it probably would be à problem but hoping it was not.. In that case, if i insist on THE ib sub, i would have to soundproof THE attic and thus backspace also.. This was the initial plan until i read about ib subs à week ago  my acoustic and soundproofing consultant advised me to just get rid of THE attic (if i can miss the storage space) and follow THE line of THE roofing with soundproofing so that we Could build à huge basstrap in de angeled roof and also have à high ceiling.

I am still à year away of building THE theater, richt now we are remodelling THE entire house . Entirely à diy project thus takes some time. 

I am hoping to build à dream theater just once. (had à small ht room in our previous house but want to take THE new room to THE next level) i do not have lots of experience with subwoofers but reading about ib subwoofers makes me curious. THE new room Will be roughly 3000 cubic feet. Will 2 manifolds with 2 15 or 18 inch drivers be sufficiënt? Or is an ib just for THE real bassheads, and since i do not Only watch action and sic fi movies etc (and are not experienced with subs) are "normal" SUbs that Will play down to under 20hz also be fatastic? 

I realise that is THE wrong thread for ib SUbs but since you gave me à response and have experience with IB SUbs i thought i Will just ask  i just dont want to build à complete room, be happy for à year or So and than rip down à ceiling, build à backspace and build an IB anyway.

Excuses for typos, iPad...


----------



## pitviper33

MVG said:


> Thank you for the good info on that! I was alreeds thinking about that, but indeed assumed wrongly that that would not be à big problem sinds i have read sometimes that the backwave did not was à problem... Was keeping in mind that it probably would be à problem but hoping it was not.. In that case, if i insist on THE ib sub, i would have to soundproof THE attic and thus backspace also.. This was the initial plan until i read about ib subs à week ago  my acoustic and soundproofing consultant advised me to just get rid of THE attic (if i can miss the storage space) and follow THE line of THE roofing with soundproofing so that we Could build à huge basstrap in de angeled roof and also have à high ceiling.
> 
> I am still à year away of building THE theater, richt now we are remodelling THE entire house . Entirely à diy project thus takes some time.
> 
> I am hoping to build à dream theater just once. (had à small ht room in our previous house but want to take THE new room to THE next level) i do not have lots of experience with subwoofers but reading about ib subwoofers makes me curious. THE new room Will be roughly 3000 cubic feet. Will 2 manifolds with 2 15 or 18 inch drivers be sufficiënt? Or is an ib just for THE real bassheads, and since i do not Only watch action and sic fi movies etc (and are not experienced with subs) are "normal" SUbs that Will play down to under 20hz also be fatastic?
> 
> I realise that is THE wrong thread for ib SUbs but since you gave me à response and have experience with IB SUbs i thought i Will just ask  i just dont want to build à complete room, be happy for à year or So and than rip down à ceiling, build à backspace and build an IB anyway.
> 
> Excuses for typos, iPad...


Sorry for the slow reply. I had family in for the holiday weekend.

I love IB, though I sold my previous setup with my last house. It's just so much "cleaner" sounding than anything else I've heard. And the ELF reproduction is hard to give up once you've experienced it. I'm hooked. I've already got drivers ready for my next theater, which will come together in the same time frame as yours. My plan is for the subwoofer backspaces to be within the soundproofed envelope.

As for how significant the backspace leakage will be, that's a little hard to quantify. My last setup was in a noisy, densely packed, suburban environment with a highway nearby. In that environment, at about 10dB below reference, the bass was audible but not "loud" at my property line 75 feet away. My hope and assumption was that it didn't make it through the walls of my neighbor's house at a level loud enough to be noticed. I can't really confirm that, but I never got complaints. (In truth, even if it bothered them it might not have been easy to identify my property as the source.)

How close is your house to your theater building? Because they're separated, I'd think your soundproofing demands are lessened anyway if the goal is keeping it quiet inside the house. Really though, it's probably not that much more effort to just include the attic in your soundproofed envelope. Then there's no worry. On the other hand, if your focus is keeping outside noise out of your room, you probably don't have much to worry about.


----------



## cw5billwade

MVG said:


> Thank you for the good info on that! I was alreeds thinking about that, but indeed assumed wrongly that that would not be à big problem sinds i have read sometimes that the backwave did not was à problem... Was keeping in mind that it probably would be à problem but hoping it was not.. In that case, if i insist on THE ib sub, i would have to soundproof THE attic and thus backspace also.. This was the initial plan until i read about ib subs à week ago  my acoustic and soundproofing consultant advised me to just get rid of THE attic (if i can miss the storage space) and follow THE line of THE roofing with soundproofing so that we Could build à huge basstrap in de angeled roof and also have à high ceiling.
> 
> I am still à year away of building THE theater, richt now we are remodelling THE entire house . Entirely à diy project thus takes some time.
> 
> I am hoping to build à dream theater just once. (had à small ht room in our previous house but want to take THE new room to THE next level) i do not have lots of experience with subwoofers but reading about ib subwoofers makes me curious. THE new room Will be roughly 3000 cubic feet. Will 2 manifolds with 2 15 or 18 inch drivers be sufficiënt? Or is an ib just for THE real bassheads, and since i do not Only watch action and sic fi movies etc (and are not experienced with subs) are "normal" SUbs that Will play down to under 20hz also be fatastic?
> 
> I realise that is THE wrong thread for ib SUbs but since you gave me à response and have experience with IB SUbs i thought i Will just ask  i just dont want to build à complete room, be happy for à year or So and than rip down à ceiling, build à backspace and build an IB anyway.
> 
> Excuses for typos, iPad...


Look up 2 builds stockmonkey200 and pimp my gerage they may be able to help monkey had IB in basement it was built in sound envelope pimp my gerage is a good detached gerage build


----------



## MVG

pitviper33 said:


> Sorry for the slow reply. I had family in for the holiday weekend.
> 
> I love IB, though I sold my previous setup with my last house. It's just so much "cleaner" sounding than anything else I've heard. And the ELF reproduction is hard to give up once you've experienced it. I'm hooked. I've already got drivers ready for my next theater, which will come together in the same time frame as yours. My plan is for the subwoofer backspaces to be within the soundproofed envelope.
> 
> As for how significant the backspace leakage will be, that's a little hard to quantify. My last setup was in a noisy, densely packed, suburban environment with a highway nearby. In that environment, at about 10dB below reference, the bass was audible but not "loud" at my property line 75 feet away. My hope and assumption was that it didn't make it through the walls of my neighbor's house at a level loud enough to be noticed. I can't really confirm that, but I never got complaints. (In truth, even if it bothered them it might not have been easy to identify my property as the source.)
> 
> How close is your house to your theater building? Because they're separated, I'd think your soundproofing demands are lessened anyway if the goal is keeping it quiet inside the house. Really though, it's probably not that much more effort to just include the attic in your soundproofed envelope. Then there's no worry. On the other hand, if your focus is keeping outside noise out of your room, you probably don't have much to worry about.


No need for saying sorry, i'm patient and i still have time enough on my hand. Also need to worry more about the current remoddeling of our house according to my wife ;-) (instead of watching on the hometheater forums) 

I am already gratefull that you guys are willing to share some information! So thank you for that!

The ELF (is ultra low frequency?) is hard to missed once experienced you say.. I once experienced a dual SVS PB13 ultra set up, and that was very nice, I think i know what you mean by that feeling. I felt it in de scene from the film Pulse.. Also very clean playing set up that was..

Once i heard a svs pb12 -2 ulra, it made my hairs vibrate during a scene from Monsters Inc. (where Sully makes the electricity blast out) this is the kind of thing I would like to acchieve.. With ''normal'' subs i would have to watch at SVS ultra 13 I guess? For the price of 1 SVS ultra I could build also a nice IB system I think. 

But have to find out if IB is what i need/want. Maybe i'm the kind of guy that is already satisfied with dual svs pb2000 or something similar. It is a pity there are very few IB builds in the Netherlands. 

My house is about 40 meters/131 feet away from the garage. The neighbours houses are behind that garage, and 65 feet behind/right side from the garage is some sort of eldery home, so i would have to keep that in mind..

Behind the garage there's a driveway/street, which is shared with other people, so just outside the back of the garage is also my property line.

I think i must come to know if IB is the thing for me, but reading about it makes me very curious I must say  The hairshaking/throuser flapping stuff I experienced at others had made me wanting this at home also, but i also like a clean bass. It's not just the chestpound en big bad bass i am looking for. I've heard some SVS set ups, and some Velodyne set ups, I prefer the (ported) SVS slightly more. But the clean sound of a Velodyne DD18 also made a good impression. But these subs are in the higher leage, and i am convinced that one will have to have a dual or even 4 sub set up to have the best result, and buying 2 SVS/JL/Velo of the higher range series is something I do not want to do, and even if I do, my wife and wallet will stop me from thinking about that 

Guess I will also soundproof the eventual backspace (the attic) like was first intended. I will remove the attic, soundproof entire room, and if and IB is the thing for me, i will place an attic as backspace.

Nice to hear you are hooked! And already have the drivers! Looking forward to see some building, i for myself have still a long way to go!

Thank you for your info and help!


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## MVG

cw5billwade said:


> Look up 2 builds stockmonkey200 and pimp my gerage they may be able to help monkey had IB in basement it was built in sound envelope pimp my gerage is a good detached gerage build


Thanks! I've seen the stockmonkey thread and bookmarked  A very nice build btw!

pimp my garage i'll search for it, thank you! It is now clear that i will have to include the IB in the sound envelope. That is good to know, and thus according to my initial plans.

It is nice to look and see lot of beautiful builds out here! Lots of information, in this thread alone! And the other threads also!

Thanks!


----------



## jer181

Brian Fineberg said:


> So I emailed the guys at soundproofing. But my room will be 13x15 with one standard door. How many IB3's will I need for the framing


Hey Brian,

An off topic question for this thread... your room is almost the same dimensions as mine will be, except longer 27'. What size screen are you going with? I will also have another XS30 pounding away


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## BasementBob

The 1/2 inch drywall that my local Home Depot sells is now "30% lighter". 

Since soundproofing is a function of mass -- keep your eye on the density figures when looking at NRC wall's sound transmission loss graphs.


"1/2" SHEETROCK UltraLight gypsum panels are the lightest drywall panels on the market. Weighing up to 30% lighter than traditional 1/2" drywall they are easier to carry and install. 4x8, 39.2 Lbs."
1/2" SHEETROCK Mold Tough gypsum panels 4'x8', 60.8 Lbs.
5/8" SHEETROCK Firecode Core (Type X) Drywall Gypsum Panel, 4' x 8', 71.81 Lbs.
5/8" SHEETROCK UltraLight FIRECODE 30 Drywall Gypsum Panel, 4 ft. x 8 ft., 61 Lbs.


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## pitviper33

MVG said:


> The ELF (is ultra low frequency?)


FYI: ELF is the frequency range from 3-30Hz. Technically, the frequency range titles apply to electromagnetic waves rather than pressure waves. But the units are the same, so they can be reasonably applied to pressure waves too. It just provides a shortcut for describing the very low content that is missing from many subwoofer installations.
http://en.wikipedia.org/wiki/Radio_spectrum#By_frequency


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## MVG

pitviper33 said:


> FYI: ELF is the frequency range from 3-30Hz. Technically, the frequency range titles apply to electromagnetic waves rather than pressure waves. But the units are the same, so they can be reasonably applied to pressure waves too. It just provides a shortcut for describing the very low content that is missing from many subwoofer installations.
> http://en.wikipedia.org/wiki/Radio_spectrum#By_frequency




Thanks! If i have any questions about it in the future i'll check out the good threads about it! Sorry for the offtopic guys!


----------



## granroth

BasementBob said:


> The 1/2 inch drywall that my local Home Depot sells is now "30% lighter".
> 
> Since soundproofing is a function of mass -- keep your eye on the density figures when looking at NRC wall's sound transmission loss graphs.
> 
> 
> "1/2" SHEETROCK UltraLight gypsum panels are the lightest drywall panels on the market. Weighing up to 30% lighter than traditional 1/2" drywall they are easier to carry and install. 4x8, 39.2 Lbs."
> 1/2" SHEETROCK Mold Tough gypsum panels 4'x8', 60.8 Lbs.
> 5/8" SHEETROCK Firecode Core (Type X) Drywall Gypsum Panel, 4' x 8', 71.81 Lbs.
> 5/8" SHEETROCK UltraLight FIRECODE 30 Drywall Gypsum Panel, 4 ft. x 8 ft., 61 Lbs.


Yep, SHEETROCK has been advertising their UltraLight panels for a couple of years, now. The last time I bought 1/2" sheets, that was all HD had in stock. I didn't have any problems finding full weight 5/8" Type X, although that might vary per store.


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## Brian Fineberg

Fatshaft said:


> Here's what I learned with my soundproofing my room.
> I have hat channels on my ceiling with DD and GG.
> 
> 
> 
> 
> 
> 
> 
> 
> I have 3 walls of foundation...again DD and GG.
> 
> 4th wall has Hat channels with DD and GG. other room on the other side
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Riser and front stage are completely sand filled
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> My room is completely sealed.
> 
> I can scream on top of my lungs and NOBODY will hear me upstairs (Love this )
> This is what the bass does upstairs my room.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Just wanting you to keep in mind that the BASS portion will have NO RESPECT for soundproofing



the 3 walls of foundation n, did you build the walls 1" away from them?[/URL]


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## Fatshaft

Brian Fineberg said:


> the 3 walls of foundation n, did you build the walls 1" away from them?


Yes of course,
Ted @ soundproofing.com helped me tremendously when I built my room.

I also did not have the amount of bass I have now when I built my room.
Knowing what I know today, I would put 4 layers of DW if I ever re-do my room


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## Brian Fineberg

haha.

did it ever contain your bass? even when you had less woofage?


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## Fatshaft

Yes it did for 2 obvious reasons...
I had less woofage and less power which equals to less SPL so less shaking.
Of course adding more woofage and more power equals more SPL/shaking 

If people have just one sub and normal power than there shouldn't be any problems.

That's why i say if you want to contain more bass you need more mass.
more bass equals WAY more mass needed.

when I built my room, having known this I would've put at least 4 layers of DW.
Maybe next time


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## Brian Fineberg

I have two psa xs30's. I am going dd + gg hopefully that's enough to keep the bass from going up two levels in the house to the bedrooms


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## granroth

*Is using two layers the wrong advice?*

Bass is one area where I _really_ wish there was more published research on how to contain it. There is a massive amount of research done on wall types as it pertains to STC... but STC only goes down to 125 Hz and quite a bit of sound proofing problems come from frequencies below that. So where are the readily available tests that show the efficiencies of various wall constructions when it comes to a solid 50 Hz signal? As far as I know, there's no such thing.

What we're left with is rules of thumb. But even those aren't strong enough, I think.

Basically, the general advice for soundproofing is to go with two layers of 5/8" Type X drywall with Green Glue in between. There are lots of tests that show how effective that is in various wall assemblies and what they tend to show is that adding another layer of drywall will do very little.

*BUT!!* Those tests aren't even looking at LFE. It's as if the rule of thumb advice is assuming that you aren't going to have subwoofers. We're building _theaters_, here! Of course there are going to be subwoofers! Rather than being an afterthought, dealing with bass should be a primary concern.

So I'm now thinking that the generic advice of two layers of DW isn't going to cut it. Maybe the rule of thumb should _start_ with *three* layers and suggest that you use four if you're going to be a bass head.

What do y'all think? Is advising on using two layers of drywall a carryover from past times or do you think it's still a valid starting point even now?


----------



## BasementBob

Two layers allows constrained layer damping. Ted White was so disappointed with 2 layers of drywall alone, he funded the startup www.soundproofingcompany.com
(Although I'm not sure if you mean two leafs -- there's something to be said for a single leaf of 2' thick concrete.)

There are mathematical predictions of what should be happening at lower frequencies,
and there are accelerometer measurements of the walls vibrations at low frequencies, which must indicate the non-flanking sound going through it.

BTW, have you seen Paul Woodlock's mixing room? 5 layers of 5/8" drywall on the inside. I believe his last drywall layer is supported by five inch wood screws. His room was floated on engineered pucks. His MDF floor with router-ed channels for electrical wires was interesting. You might remember his door. He doesn't mix squat under 30hz.

A willingness to put up two layers of 5/8" drywall per leaf is where you begin to be able to post questions about soundproofing.


----------



## granroth

BasementBob said:


> Two layers allows constrained layer damping. Ted White was so disappointed with 2 layers of drywall alone, he funded the startup www.soundproofingcompany.com
> (Although I'm not sure if you mean two leafs -- there's something to be said for a single leaf of 2' thick concrete.)
> 
> There are mathematical predictions of what should be happening at lower frequencies,
> and there are accelerometer measurements of the walls vibrations at low frequencies, which must indicate the non-flanking sound going through it.
> 
> BTW, have you seen Paul Woodlock's mixing room? 5 layers of 5/8" drywall on the inside. I believe his last drywall layer is supported by five inch wood screws. His room was floated on engineered pucks. His MDF floor with router-ed channels for electrical wires was interesting. You might remember his door. He doesn't mix squat under 30hz.
> 
> A willingness to put up two layers of 5/8" drywall per leaf is where you begin to be able to post questions about soundproofing.


Yeah, I'm definitely referring to the number of layers of drywall on a presumably already decoupled wall (room-in-room or clips+channel). I'm also assuming a damping layer of Green Glue since that's proven to help.

Mathematical predictions might help, but I do find empirical tests to be more easily applied to real world construction. That is, most mathematical predictions I've seen of physical phenomena will point you in the right direction, but will often vary wildly from real world results.

Ted gives his usual stellar advice, but he's definitely one of those that advocates using just two layers of drywall for most people. Many people get that advice from him (including myself) even after knowing that there will be subwoofers involved. I'm starting to think that maybe that advice needs to be updated. More and more it's looking like two layers just won't cut it for anybody that's wanting to do proper soundproofing with bass and not just the higher frequencies.

But is it pointless? You mentioned Woodlock's 5 layers of drywall in a completely decoupled room but suggest that even he can't suppress sub-30Hz frequencies?


----------



## BasementBob

granroth said:


> More and more it's looking like two layers just won't cut it for anybody that's wanting to do proper soundproofing with bass and not just the higher frequencies.


As you pass two layers and green glue, you start to get to the point where other things are dominant like doors and flanking.



granroth said:


> You mentioned Woodlock's 5 layers of drywall in a completely decoupled room but suggest that even he can't suppress sub-30Hz frequencies?


Paul Woodlock is a musician who plays instruments you might find in an orchestra in the year 1700s (strings, woodwinds, brass, the occasional kettle drum, and voice). I meant to suggest the stuff he works with doesn't have less than 30hz content. His room might be effective at low frequencies, which is useful for street noise, but he's not working with those frequencies. 

This is his door: http://www.bobgolds.com/PaulsDoor/home.htm 

This is his construction thread (130 pages of posts), including the Sylomer EDPM pucks he used, and lots of pictures: http://forum.studiotips.com/viewtopic.php?f=1&t=107 

Here's the gist about his floor:



PaulWoodlock said:


> A floating floor is a mass-spring-mass system ( MSM ) Underfloor and floating floor are the masses, while the 'rubber' inbetween is the spring.
> This MSM system has a resonant frequency. At the resonant frequency you'll amplification and not decoupling. The key is to design so the resonant frequency is 2 to 4 octaves below the lowest frequency you want to isolate. So 30 Hz you're looking at 7.5Hz to 15Hz resonant frequency.
> I designed my floating floor ( with much help from Eric - THANKS ERIC!! [Eric Desart, designer of Galaxy Studios springs, and first to describe wool corner chunks (acoustic corner traps) on the internet spawning an entire industry of mail order treatments deeper than 3 inches] ) with a resonant frequency of around 10Hz. This meant a block thickness of 50mm. Even 25mm block thickness I couldn't' get close to what I needed. Other advice is to make the floated floor as heavy as possible.
> Have a look at this Excellent site. http://www.earsc.com/HOME/engineering/TechnicalWhitePapers/Vibration/index.asp?SID=61
> This will teach you how it all works. [Yeah right -- doable, but it wasn't easy the first time I looked at it. Easier to have the manufacturer do the calcs for you, which as I recall Paul did to confirm his math.]


Paul Woodlock's is about as far I think as any amateur can DIY.

Home Recording Studio Build It Like The Pros by Rod Gervais, is usually what I recommend, both as a book, and a level of effort that is likely of success.


----------



## granroth

BasementBob said:


> As you pass two layers and green glue, you start to get to the point where other things are dominant like doors and flanking.


Yeah, that's the dominant rule of thumb that most people who care about such things go by. I've heard many times that anything more than than two layers very quickly gets into the law of diminishing returns. Indeed, if you look at all of the tests done of wall assemblies for STC, that appears to be very true.

*BUT* I haven't seen any evidence that this advice takes into account bass! Where are the tests that show the same steep drop-off of increased efficacy after two layers when a sweep of 10Hz to 100Hz is run?

The problem, I think, is that it costs a lot of money to run a controlled test on a wall assembly and there likely won't be enough payback if your target market is only theaters and studios. Organizations like the NRC and companies like Green Glue need to really focus on shared living areas like apartments since that's where the money (and regulations) are -- and in those cases, STC is a very good measurement since it's unlikely that you'll be encountering low frequencies on a regular basis.

Maybe some ad-hoc tests could be done by people building their theaters in real time. For instance, if you're building a theater with three or more layers of drywall, then run some tests after each layer and compare the differences. It won't be completely accurate since Green Glue takes some weeks to really do its thing, but it'll be a start...


----------



## btinindy

I am in the preliminary planning stages of a theater build. I will have three foundation walls for the theater, but the ceiling is my largest concern. I too have been trying to research and figure out what the best way is to contain the bass in that room. 

Just thinking out loud, what about building a box around a sub with a mic and measuring gear at a fixed position and measuring the level with each layer built around the box? I have a uxl18 sitting around right now that I would be willing to try this on if others thought this would yield anything worthy or meaningful. 


BT1


----------



## BasementBob

granroth said:


> *BUT* I haven't seen any evidence that this advice takes into account bass! Where are the tests that show the same steep drop-off of increased efficacy after two layers when a sweep of 10Hz to 100Hz is run?
> 
> The problem, I think, is that it costs a lot of money to run a controlled test on a wall assembly and there likely won't be enough payback if your target market is only theaters and studios. Organizations like the NRC and companies like Green Glue need to really focus on shared living areas like apartments since that's where the money (and regulations) are -- and in those cases, STC is a very good measurement since it's unlikely that you'll be encountering low frequencies on a regular basis.


I think it's more accurate to say:
- they (NRC, GreenGlue) publish tests for which there is good science. The NRC and Orfield and Riverbank facilities are only certified down to a certain frequency, and beyond that the facility itself has flanking issues so large that they make test results below that frequency progressively awful. That said, they do publish unofficial results down under 80hz. For example, here's one down to 31.5 hz: here (scroll down to Appendix B, and note the possible resonance frequency near 40 hz). 
- or to say the same thing another way, even with a multi million dollar government funding, it's hard to stop bass.


----------



## granroth

btinindy said:


> I am in the preliminary planning stages of a theater build. I will have three foundation walls for the theater, but the ceiling is my largest concern. I too have been trying to research and figure out what the best way is to contain the bass in that room.
> 
> Just thinking out loud, what about building a box around a sub with a mic and measuring gear at a fixed position and measuring the level with each layer built around the box? I have a uxl18 sitting around right now that I would be willing to try this on if others thought this would yield anything worthy or meaningful.


I asked a very similar question near the beginning of this thread:



granroth said:


> *Question:* What are the prevailing opinions on the validity of small scale soundproofing tests?
> 
> I'm wondering if it's possible to perform some small scale tests to compare various soundproofing methods. I'm not even remotely suggesting that any small scale tests would even start to approach the reliability of a full lab test... but would they be at least a little useful?
> 
> The biggest reason I'm thinking that maybe they wouldn't be at all valid is because I'm 99% certain that small scale tests absolutely won't work for comparing acoustical treatment plans. Acoustical treatments are designed to work with specific wave lengths and so the actual size of a room matters a lot.
> 
> But is that true for soundproofing? If all I'm going to test is an overall DB drop, then would a small scale test at least approximate a result?


And Bob's answer at the time:



BasementBob said:


> Quote:Originally Posted by *granroth*
> 
> I'm wondering if it's possible to perform some small scale tests to compare various soundproofing methods. I'm not even remotely suggesting that any small scale tests would even start to approach the reliability of a full lab test... but would they be at least a little useful?
> 
> 
> Yes.
> Brian once did an experiment like this:
> Most of the noise through a wall is at resonance, and resonance can be tested with a small 1'x1' piece of material and an accelerometer.
> As I recall, he used it to give him a better idea of what to build full scale and test in a real testing facility.
> 
> But resonance in a 2 leaf wall, is because of the leaf-air-leaf system, I'm not sure how to test that small scale off hand.
> 
> I think he even mused how to, although I don't know if he ever got around to it, make his own testing facility with thin concrete walls to test gypsum walls approximately.
> Quote:Originally Posted by *granroth*
> 
> But is that true for soundproofing? If all I'm going to test is an overall DB drop, then would a small scale test at least approximate a result?
> 
> No.
> Just good quick hints of what to really test; of what might give good results.


Now I was specifically thinking about testing such things as gaps between walls and how much insulation to use and such. Apparently that won't work small scale.

Would testing layers of drywall to combat bass work in small scale? Is it different enough that it might make sense? Bob, any opinion here?

Thinking out loud... a big problem would definitely be flanking unless the box was constructed to completely enclose the subwoofer. That is, the floor would need to be build identically to the walls and ceiling of the box.

Since mass is what nominally matters, that makes me wonder if it refers to mass as a "per square inch" perspective or as a whole. Would a wall that is 10'x10' have less bass absorption capability than one that is 20'x10' since the latter has far more overall mass? If the total mass matters, then a small scale test can't work at all since it has so much less total mass than a true wall. If it's per square inch, then the size doesn't matter.

But here's my actual thought -- do it!! Sometimes you don't know how something will work until you try it. Maybe the learned opinion would be that, indeed, small scale would do nothing. But maybe you run some tests and you see a huge difference with each layer of drywall. That'd be a useful bit of data, regardless.


----------



## btinindy

That is what I am thinking. My thought was just to install the sub on the floor as I plan to install it (pad and carpet on top of plywood). Build a box (5 sided) to sit over the sub and then add layers to the box. While the absolute data may not be overly useful because of scale the relative data of each layer should give me some indication of how to proceed. 


BT1


----------



## granroth

Moving this quote to this thread, since it'll likely be a more searched thread in the long term and this info is golden.



TMcG said:


> Granroth - You are dead-on with your statements with the exception that three damped layers has been tested. In fact, it is addressed in the IB-3 clips installation manual. Extensive testing has also been done by Saint Gobain and the Canadian building code organizations on the matter (primarily for noise transmission from foot fall traffic in multi-family dwellings), none of the results I could find in a pinch (translation - I don't ever use web bookmarks )
> 
> Two layers is effective for the upper bass frequencies. The third layer gives you significant damping down to 40Hz, especially in the critical 40Hz-80Hz range that shakes upstairs coffee tables.


If you do find those results, let me know and I'll add them to the index.

BasementBob earlier linked to a WhisperClips test that had non-certified measurements down to 31.5Hz. What is notable to me is that with two layers of drywall (no Green Glue) it only has a transmission loss of 28dB at 80hz and it gets notably worse as the frequency goes down. 28dB doesn't seem very good at all. If you're playing a movie with your subwoofer pumping 90dB (not uncommon, I believe) than everybody outside of the theater is hearing your sub at 60dB and higher. That's pretty noticeable.

I found this Green Glue paper where they compare using Green Glue vs extra drywall: http://www.greengluecompany.com/sites/default/files/Green Glue Vs Extra Drywall.pdf. They muddy the waters a little by not always comparing apples to apples, but what really stands out to me is how little of a difference more layers is making. Even three layers of DW on each side of the wall plus GG in between each is only marginally better than two layers, even without Green Glue (when it comes to bass).

Based on these results, I'm starting to think that while two layers of DW+GG won't cut it for bass, then neither will three layers. Or four.

Those results that show significant damping down to 40Hz would be _very_ appreciated right about now 



TMcG said:


> But I also think there is a limitation to the design of the IB-3 clips which Fatshaft (and many others) used on his ceiling. Although *somewhat* decoupled, the connection to the structure is being overwhelmed by the low frequency energy it is trying to limit getting through. In other words, the LFE in his system just kicks too much a$$ and he would have had to use better decoupling products that can dissipate more vibration energy. The PAC RSIC-1 would have been a better clip to start with because of the Neoprene, but even then I think the LFE energy would be too much. Kinetics Noise Control makes a really sweet IsoMax Resilient clip that has a ton of neoprene to absorb the energy, but even then I would have cause for pause. I believe there's also some fault to the recommended construction technique of ceiling / wall / ceiling / wall for the layers.
> 
> I prefer a different method in both construction and product. I will install all three wall layers with offsetting seams and with 5/8" OSB (or ply) as the first layer. So it's 5/8" OSB / GG / 5/8" drywall / GG / 5/8" drywall. All of this is tied directly into a decoupled wall structure, so something like Serenity Mat (rubber underlayment) on the floor under the sill plate and decoupled at the top by building the wall short and using either the IB-3 bracket, or I prefer the Kinetics Noise Control CWCA Wall decoupling bracket which has significantly more decoupling and vibration isolation through 1.5" of Neoprene. Pictures of my previous install HERE.
> 
> I will use the same three layers for the ceiling construction, but prefer a spring loaded or suspension approach (product) to absorb the energy. It's one thing for the LFE energy to find its way through a handful of hard connection points as in Fatshaft's install, but it's another thing entirely when you are asking for LFE energy to lift hundreds of pounds of damped mass as part of a isolated and suspended ceiling structure. In my last theater I used Kinetics Noise Control ICW Wood Frame Ceiling hangers. They were great, but a bit of a pain to install because of the Cold Rolled Steel "C" channel you have to use before attaching the resilient channel. If you wanted the best performance, then these are your brackets, but they were pricey (about $20-$30 each if I recall correctly).
> 
> This time around I am using the Kinetics Noise Control WAVE Hanger. Significantly less expensive and a much easier installation with less materials while still maintaining a very low profile and giving you a true suspension ceiling that is fully deflected under load. Considering the main 2-story foyer of our home is right above the theater and it is covered with hardwoods, it will be important to me to get the best possible isolation for my ceiling.
> 
> Hope this helps.


Yeah, I point to Fatshaft's video mostly as an extreme example of what can happen. The total amount of energy there definitely eclipses most theaters and the walls physically attached to the ceiling joists also creates notable flanking paths, which also make the affect of just the drywall less clear.

Focusing more on more robust decoupling in the form of suspension is a very interesting idea! The standard advice says that only more mass will really combat bass, but your explanations on the spring effect is very compelling.

When it comes time to build your new theater, do you think you could run some tests in between each layer of drywall? It wouldn't be directly applicable to anybody not using similar suspension techniques as you BUT as long as those remain a constant, you'd at least see what kind of difference just the increases in mass make.


----------



## BasementBob

granroth said:


> If you're playing a movie with your subwoofer pumping 90dB (not uncommon, I believe) than everybody outside of the theater is *hearing* your sub at 60dB and higher. ... Even three layers of DW on each side of the wall plus GG in between each is only marginally better than two layers


Two things to look into:
1. Sound loudness curves. So they might not hear it; but they might feel it, or hear the dishes rattle.
2. The rule-of-thumb is a doubling of mass gives an increase of 6dB of soundproofing. So moving from 2 layers of drywall to 3 layers, could be as much as a 3dB(?) increase, but not more.


----------



## TMcG

granroth said:


> When it comes time to build your new theater, do you think you could run some tests in between each layer of drywall? It wouldn't be directly applicable to anybody not using similar suspension techniques as you BUT as long as those remain a constant, you'd at least see what kind of difference just the increases in mass make.


Glad you found the info helpful. I posted a follow-up with links in Beast's thread, FYI.

I've never made measurements before, but I would be willing to do it....I just need you to tell me what hardware I need and software. I assume you are talking about some sort of calibrated USB mic and REW software, but let me know if you are thinking of something different.

I've already passed getting a good base line, though, because I've added two layers of 5/8" with Green Glue in between the ceiling joists of the theater. Moving forward I can measure the impact of insulation then all three layers progressively. Heck, I'll even perform the test 30 days later after the Green Glue has reached its fully-cured potential!


----------



## Jacob B

*Advice on hardwood floor laying technique*

Hi,
I would like some advice on what the best way to lay my black oak hardwood floor in my dedicated Home Theater.

I have sound proofed the room as described in this *post*.

Quoting from the post, "_Finally, I had another contractor lay a double 5/8"OSB floor with green glue, on top of a 10 mm rubber matt I bought from an Italian company called Isogomma. Underneath the the rubber matt were the original wooden pine boards.
Underneath the pine boards is a large cavity - 8" high - and then the house's original flat roof made out of roofing felt. 
Update December 5, 2014: I just accepted an offer from a contractor to fill out the 8" cavity with paper wool_"

So, the question is how to lay the 15 mm oak floor. It is a multi-layer/laminated parquet floor with two plywood layers and a 3.6 mm oak layer on top, and with tongue and groove.
Charcoal Oak from Soldidfloor










*I see three options:*
*1)* Glue it directly to the double OSB w/ GG underfloor with specialized glue. The parquets/panels are also glued to each other in the tongue and groove.









*2)* Green glue it directly to the double OSB w/ GG underfloor. The parquets/panels will be glued to each other in the tongue and groove with standard tongue and groove glue. 










*3)* Lay it floating on a 1/8 to 1/4" subfloor, on the double OSB w/ GG.

6 mm soft board









or (3 mm)









or 2 mm kork:









*My goal *is to optimize sound proofing, as well as the acoustical character of the floor.

Thanks


----------



## flyfishingnitin

*Need advice on soundproofing a narrow basement home theater room*

Hello folks,

I need help making the right compromises for a narrow basement room for a home theater. 

Attached is a picture and a layout of the room. The room itself is

11'6" wide without any framing on the exterior walls 
23'6" long with electrical panel on one end
7'6" from the concrete floor to the ceiling joists

The basement is 70% below grade with cinderblock walls from the thirties.

My biggest concern is the narrowness of the room. If I add conventional soundproofing/soundtreatment on all sides, then it gets even narrower.

What compromises can I make to keep the room width to the max?
- Sound proof just the wall along the staircase
- Sound proof the ceiling with hat channel + DD + GG

Any suggestions and pointers greatly appreciated. Also, please feel free to point me to other posts and builds on this forum that tackled a similar situation.

Thanks a ton!


----------



## genofive0

flyfishingnitin said:


> *Need advice on soundproofing a narrow basement home theater room*
> 
> Hello folks,
> 
> I need help making the right compromises for a narrow basement room for a home theater.
> 
> Attached is a picture and a layout of the room. The room itself is
> 
> 11'6" wide without any framing on the exterior walls
> 23'6" long with electrical panel on one end
> 7'6" from the concrete floor to the ceiling joists
> 
> The basement is 70% below grade with cinderblock walls from the thirties.
> 
> My biggest concern is the narrowness of the room. If I add conventional soundproofing/soundtreatment on all sides, then it gets even narrower.
> 
> What compromises can I make to keep the room width to the max?
> - Sound proof just the wall along the staircase
> - Sound proof the ceiling with hat channel + DD + GG
> 
> Any suggestions and pointers greatly appreciated. Also, please feel free to point me to other posts and builds on this forum that tackled a similar situation.
> 
> Thanks a ton!


Although my room is not as narrow as yours I am dealing with a 12' wide room after talking with ted from the sound proofing co we came to the ideal. That clips and channel on the ceiling with DD and GG would be my best option followed by DD and GG on the walls as not to narrow the room anymore then necessary. After weighing all options for me the width of the room was a big concern. it out weighed the complete sound proof options I can deal with some sound loss as the family mostly watches together.


----------



## granroth

flyfishingnitin said:


> *Need advice on soundproofing a narrow basement home theater room*
> 
> Hello folks,
> 
> I need help making the right compromises for a narrow basement room for a home theater.
> [SNIP]


It's very important for anybody looking to soundproof their room to first establish what their requirements are, but it's doubly important if you have "non standard" rooms or needs. That is, the generic advice tends to focus on a specific type and size of home theater with an assumption on what kind of soundproofing you'd expect. If you have such a theater and you follow the advice, then you're golden.

But if your theater has hard limits in certain areas (in your case, both width and height), then the generic advice no longer works. Now it's extremely important to learn what your specific needs are, in order to try and come up with a solution that might fit those needs.

So... off the top of my head:

1. Are there noisy external sources clearly audible in the basement (e.g., loud neighbors, trains, trucks, etc)?
2. What is the ambient noise level in the basement now? What do you want it to be in the theater when you're done?
3. Do you plan on watching movies where sound escaping would be a big problem (e.g., baby trying to sleep, etc)?
4. Are you a bass fanatic? Plan on having eight 18" subwoofers? More?


----------



## Brian Fineberg

Ok so for me:

1) no
2) 38db. It's higher when the hvac is on. I would like it to remain at 38db
3) yes. But for a sleeping wife. The babies sleep through anything
4) yes. But I will only ever have my dual xs30's

My room will be 13'x16'x8' but that's before framing and dd


----------



## kmhvball

flyfishingnitin said:


> *Need advice on soundproofing a narrow basement home theater room*
> 
> Hello folks,
> 
> I need help making the right compromises for a narrow basement room for a home theater.
> 
> Attached is a picture and a layout of the room. The room itself is
> 
> 11'6" wide without any framing on the exterior walls
> 23'6" long with electrical panel on one end
> 7'6" from the concrete floor to the ceiling joists
> 
> The basement is 70% below grade with cinderblock walls from the thirties.
> 
> My biggest concern is the narrowness of the room. If I add conventional soundproofing/soundtreatment on all sides, then it gets even narrower.
> 
> What compromises can I make to keep the room width to the max?
> - Sound proof just the wall along the staircase
> - Sound proof the ceiling with hat channel + DD + GG
> 
> Any suggestions and pointers greatly appreciated. Also, please feel free to point me to other posts and builds on this forum that tackled a similar situation.
> 
> Thanks a ton!


I think Granroth's questions are critical, to know what to do - need to know the objectives. 

Another question I would have, is what your Speaker plans are... generically meaning, in-wall, in-ceiling, or 'on-wall'. If In-Wall, that then narrows down your options for what to do with the framing.

As posted in your thread by BigmouthininDC... I would consider metal studs. You might need to look at weight capability (i.e., can you hang two sheets of drywall on it)...

But if I think about the narrows


Air Gap + Stud + 1st Layer DW+ 2nd Layer DW
1" +3.5" + .625" + .625" = 5.75" x 2 side walls = 11.5" Traditional Stud
0.5" +1.625" + 0.5" + .625" =3.25" x 2 side walls = 6.5"

The air gap is usually the space between the studs & exterior walls... I think you could minimize this with limited impact. 

The narrowest steel stud I think is 1 5/8", a fair bit smaller than a 2x4". Again, worth checking if it can handle the weight of two layers of sheeting (OSB or Drywall). 

I chose to use my 1st layer on my wall as 1/2" OSB vs 5/8" Drywall. I am doing fabric panels, so, the ability to attach those anywhere into 'wood' vs worrying about find an attachment point was important. I then did Green Glue, and a 5/8" layer of Drywall.

Of course, if you want 'in wall' speakers, the above won't achieve that for you. I think I saw 2.5" steel studs... so, 2.5" steel stud + 0.5" air gap + 0.5" drywall + .625" drywall might get you deep enough for in-walls. 

I used clips & channels, which I ran perpendicular to my joists, but if you want to save ~1", you add blocking and run them parallel to the joists. My main ceiling height was 8'8", so, I wasn't supper concerned about that 1".


----------



## jimim

I'm getting rest to drywall in a few weeks and fear is startng to set in. Right now 2 of my walls are double stud walls. The other two ar staggered stud. All are decoupled from joists above. I'm also doing clips and channel on ceiling. Plan is osb and the dw with green glue. I'm starting to get worried bout some room penetrations.

I have putty pads for the outlet boxes my speaker conduit connect to on the walls. My plan for the projector outlet box and conduit fo wires was putty pads and chalk the seams but I found pics of big us g backer boxes for the conduit and outlet box in one build. Schools I be doing the same vs putty pads?

Also regarding chalked seams. I planned on chalk g all osb layer seams and that's it. Che dw layer would be just mud. Am I correct?

Also where walls meet ceiling and wall meets walls should I butt the osb and dw layers as close as pebble to keep seams as small as possible. I have reD in places they should be 1/4 inch and chalked but didn't see why that would be needed if I can get joints close. Chi know floor should be up 1/4".

Thanks a lot. My fear is I am missing something before I close up. Call have is in joint mufflers for runs as long as I was able.c front supplies are at least 12 feet in length protected in 3 layers with green glue and rear returns are in 4 feet coffins but these runs will also be in doubled layer dw'ex soffits inside room. So I know I'm good there.

Thanks,
Jimi


----------



## cw5billwade

1st layer is ceiling You want to keep the ceiling OSB about 1/4" or less from the studs. Then do the wall keeping about 1/8" from ceiling OSB caulk all cracks


----------



## jimim

cw5billwade said:


> 1st layer is ceiling You want to keep the ceiling OSB about 1/4" or less from the studs. Then do the wall keeping about 1/8" from ceiling OSB caulk all cracks


Thanks! So no chalk second layer right.

Also is putty pads enough for my projector outlet? Ci was going to use a 2x4 with the box attached and screwed to osb, put putty pad on and then throw it up there and attach to channel. Or should I be doing full backer boxes? Should my two inch conduit have a backer box that I'm using for my wire runs? On my walls I'm only usng putty pads. I never thought about getting crazy and doing backer boss but now I'm worrying.

Thanks,
Jm


----------



## cw5billwade

Mud and tape are fine. There are levels of sound proofing. No holes in the envelope would be best followed by backer boxes. Putty pads provide some level of protection.


----------



## jimim

cw5billwade said:


> Mud and tape are fine. There are levels of sound proofing. No holes in the envelope would be best followed by backer boxes. Putty pads provide some level of protection.


ThNks agan. So it just comes down to how fa down the rabbit hole kinda. So I just have to make a decision on if it's going to make that big of a difference. 

Thanks again.

Jm


----------



## cw5billwade

jimim said:


> ThNks agan. So it just comes down to how fa down the rabbit hole kinda. So I just have to make a decision on if it's going to make that big of a difference.
> 
> Thanks again.
> 
> Jm


Correct that is why I went the route of Soffits, Coffers and columns. All of the wires AC and Low Voltage coming into my theater enter through them the Soffits are also built with 2 layers of OSB/DW stuffed with pinkstuff. Some of the AC comes in through the stage and riser. That way you have an additional layer of protection. Hard to do in a basement build with limited ceilings but I am on second floor with 10’ in front and 9’ over riser. My HVAC comes into the soffits and is stuffed around the flex duct with pink stuff. The weak link in my build is the door. I still need to seal it and do some other measures.


----------



## jimim

cw5billwade said:


> Correct that is why I went the route of Soffits, Coffers and columns. All of the wires AC and Low Voltage coming into my theater enter through them the Soffits are also built with 2 layers of OSB/DW stuffed with pinkstuff. Some of the AC comes in through the stage and riser. That way you have an additional layer of protection. Hard to do in a basement build with limited ceilings but I am on second floor with 10’ in front and 9’ over riser. My HVAC comes into the soffits and is stuffed around the flex duct with pink stuff. The weak link in my build is the door. I still need to seal it and do some other measures.


Thanks again. I think I did a good job with my hvav. There in in mufflers for long distances so I know I'm good there. In the room the soffit will be double dw forcthe additional flex so good there. My door I'm not worried about. My buddy's shop is in charge of that. My weakest link right now is my two decoupled walls that are staggered vs double and me using putty pads for my penetrations of conduit boxes bs backer boxes. 

Jim


----------



## cw5billwade

jimim said:


> Thanks again. I think I did a good job with my hvav. There in in mufflers for long distances so I know I'm good there. In the room the soffit will be double dw forcthe additional flex so good there. My door I'm not worried about. My buddy's shop is in charge of that. My weakest link right now is my two decoupled walls that are staggered vs double and me using putty pads for my penetrations of conduit boxes bs backer boxes.
> 
> Jim


hope it is not to late but a good practice with the putty pads is to not have the outlets or what ever from one room in the same stud cavity as the other room. hope that makes since. @granroth did outlets with putty pads in his build and I think he did a good job. phoenix-theater-build-thread


----------



## jimim

cw5billwade said:


> hope it is not to late but a good practice with the putty pads is to not have the outlets or what ever from one room in the same stud cavity as the other room. hope that makes since. @granroth did outlets with putty pads in his build and I think he did a good job. phoenix-theater-build-thread


Thanks. Yup I have a putty pad for an outlet on the other side of the theatre wall. I remembered. Lol. It's for a tv monitor for my rack so I can monitor settings while outside the room. No ther walls have outlet boxes so good there. I'm going to have to play with the putty pads. So do I wrap right to the edge of the box or stay back the 1.25 inch cause of drywall? Couldn't see what others decided? I didn't use adjustable boxes. I used a regular box with a .75 extension ring to give me the 1.25". 

I know all sides expect the side that touches the stud gets wrapped but again not sure if I run the pad to the edge of box or hold it back a bit. 

Thanks,
Jim


----------



## granroth

jimim said:


> Thanks. Yup I have a putty pad for an outlet on the other side of the theatre wall. I remembered. Lol. It's for a tv monitor for my rack so I can monitor settings while outside the room. No ther walls have outlet boxes so good there. I'm going to have to play with the putty pads. So do I wrap right to the edge of the box or stay back the 1.25 inch cause of drywall? Couldn't see what others decided? I didn't use adjustable boxes. I used a regular box with a .75 extension ring to give me the 1.25".
> 
> I know all sides expect the side that touches the stud gets wrapped but again not sure if I run the pad to the edge of box or hold it back a bit.
> 
> Thanks,
> Jim


I described the step-by-step installation in this post: Post 552. I did change the end result a bit by scoring the putty pad back the width of the drywall. That's described in more detail in this post: Putty Time


----------



## jimim

granroth said:


> I described the step-by-step installation in this post: Post 552. I did change the end result a bit by scoring the putty pad back the width of the drywall. That's described in more detail in this post: Putty Time


Ok thanks man. Ya I saw the first set of instructions but didn't know u changed it then. Just read that. Thanks for that link.

I'm feeling a bit better now about using the putty pads vs backer boxs. Just have to keep things tight and clean. 

I have to decide weather to chalk the final layer though. I just don't think I can be neat enough for when they go in and mud and tape. That's whAt I'm worried about. I know I will chalk the whole first layer, but like I said I'm worried about those wall to wall seams and. Idling to wall seams on second layer. 

Is it worth it. That's kinda the next thing to make my mind up about.

Jimi


----------



## Brian Fineberg

What's cheaper?

2 - layers of 5/8 drywall

Or

1 layer of osb + 1 layer of 5/8 drywall


----------



## Jacob B

Jacob B said:


> Hi,
> I would like some advice on what the best way to lay my black oak hardwood floor in my dedicated Home Theater.
> 
> I have sound proofed the room as described in this *post*.
> 
> Quoting from the post, "_Finally, I had another contractor lay a double 5/8"OSB floor with green glue, on top of a 10 mm rubber matt I bought from an Italian company called Isogomma. Underneath the the rubber matt were the original wooden pine boards.
> Underneath the pine boards is a large cavity - 8" high - and then the house's original flat roof made out of roofing felt.
> Update December 5, 2014: I just accepted an offer from a contractor to fill out the 8" cavity with paper wool_"
> 
> So, the question is how to lay the 15 mm oak floor. It is a multi-layer/laminated parquet floor with two plywood layers and a 3.6 mm oak layer on top, and with tongue and groove.
> Charcoal Oak from Soldidfloor
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *I see three options:*
> *1)* Glue it directly to the double OSB w/ GG underfloor with specialized glue. The parquets/panels are also glued to each other in the tongue and groove.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *2)* Green glue it directly to the double OSB w/ GG underfloor. The parquets/panels will be glued to each other in the tongue and groove with standard tongue and groove glue.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *3)* Lay it floating on a 1/8 to 1/4" subfloor, on the double OSB w/ GG.
> 
> 6 mm soft board
> 
> 
> 
> 
> 
> 
> 
> 
> 
> or (3 mm)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> or 2 mm kork:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *My goal *is to optimize sound proofing, as well as the acoustical character of the floor.
> 
> Thanks


I am bumping my post in hope for comments

Any advise would be warmly welcome 

Cheers,
Jacob


----------



## granroth

Brian Fineberg said:


> What's cheaper?
> 
> 2 - layers of 5/8 drywall
> 
> Or
> 
> 1 layer of osb + 1 layer of 5/8 drywall


Two layers of drywall will nearly always be the less expensive option, but it will vary by your local suppliers. In my case, I can get 5/8" Type X drywall for about $12 a 4x8 sheet and 5/8" (19/32") OSB for $14/sheet.

Hmm.. that's less than when I sourced it out earlier this year. Back then, there was roughly a $5 difference per sheet and I couldn't justify the extra $130 it would add to my costs. Still, even with that, I was being penny-wise and pound-foolish. Not doing OSB as the first layer was one of my notable mistakes in my theater that if I could go back in time, I'd definitely change.


----------



## Brian Fineberg

granroth said:


> Two layers of drywall will nearly always be the less expensive option, but it will vary by your local suppliers. In my case, I can get 5/8" Type X drywall for about $12 a 4x8 sheet and 5/8" (19/32") OSB for $14/sheet.
> 
> Hmm.. that's less than when I sourced it out earlier this year. Back then, there was roughly a $5 difference per sheet and I couldn't justify the extra $130 it would add to my costs. Still, even with that, I was being penny-wise and pound-foolish. Not doing OSB as the first layer was one of my notable mistakes in my theater that if I could go back in time, I'd definitely change.


Why would you say it's a mistake?

If it's only 2$ difference in my state. I will definitely do osb as first layer


----------



## granroth

Brian Fineberg said:


> Why would you say it's a mistake?


There's actually a decent discussion on the benefits of using OSB at the beginning of this thread: Post 5

In my case, I miss the flexibility of being able to screw wherever I wanted. Yes, that has already come into play, even with just the second layer. It's going to come into play even more now that I'm onto my soffit.

And then there is the ease of cutting it. I recognize that most people find drywall easier to cut ("score and snap") but I really suck at it. Give me a circular saw + guide and a jig-saw and I can get very accurate cuts out of OSB. I've never gotten the hang out of accurate cuts on drywall.


----------



## mtbdudex

Query:
How incrementally effective are putty pads over a good air tight sealed blue box with silicone?

Example of what I did for my HT:
Install blue box's, route wire, staple wire secure per code so no wiggle.
Side corners not used I apply silicone inside/outside, corners used I also apply silicone both sides of box wires to seal, let dry 24 hours. 
Used the white>clear upon dry to confirm 100% dry before proceeding, that's the negative of this you need to plan ahead/wait till silicone cure before proceeding.
Cost wise 1 tube silicone can easily do an entire HT, $4.50 
I use a popsicle stick to get the silicone good deep, apply liberally

Install drywall, vacuum then seal edge to drywall with silicone, get it down deep and good.

Inside view showing 4 corners sealed. Airtight is key here.
No leakage, no sound path....









End result: (these are for speaker boxes, I did same for my 120v boxes.)












granroth said:


> Putty pads are a very typical way to seal off outlet boxes and are part of many a theater build. Curiously, though, the instructions I found for using them were sparse at best and non-existent at worst. I got the impression that it should be "obvious" how to install them. Well... it wasn't for me, and it might not be for others. I finally got a method that worked well for me after maybe four outlet boxes and figured that I'd describe that method here.
> 
> I make no guarantee that this is the "right" way to do it. In fact, if I'm clearly doing something wrong, don't hesitate to correct me.
> 
> *Baseline*
> 
> My outlet boxes are standard Carlon single-gang adjustable boxes, which are somewhat ubiquitous in this application. I needed 1-1/4" clearance for the two layers of 5/8" drywall that will be installed soon.
> 
> The putty pads came from the Soundproofing Company at roughly $5 each. That's a pretty standard price for these. I don't see any brand name associated with them. Hilti makes their own brand of putty pads, which may be available locally in some areas. You may need to buy them in sets of 20, though, which can get expensive. The putty pads I used had a plastic release sheet on each side. Hilti pads appear to be individually packaged. I've seen some suggestions that using readily available "duct seal putty" (found at the big box stores) can also work for quite a bit less money, but I didn't try that.
> 
> *Optional Step*
> 
> I didn't see this step anywhere, but I noticed that a single square putty pad would leave one side of my outlet extension (the part that extends past the stud) completely uncovered. That may not matter, but since there is physically enough material to cover the entire thing, I made a little effort to do so.
> 
> I started by cutting of just over an inch of the putty pad, while it was still covered by the plastic on both sides:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I then removed the plastic from both sides of my cut-off hunk and wrapped it around the extension, making sure to primarily cover the "other" side that won't be covered by the main pad. The pad is quite sticky and moldable, so it easily adheres to the box:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Applying the Putty Pad*
> 
> Covering a three-dimensional object with a two-dimensional pad would normally mean bunching up the pad in the corners quite a bit. I got around this by cutting some slits in the pad to allow me to go around the corners easier. The slits are roughly the depth of the outlet box in and the width of the outlet box high... but I just eyeballed it, since it's not critically important:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> That was done with both sides of the plastic still on. I immediately followed this by removing the plastic from one side. I then pressed the pad against the side of the outlet box away from the stud, so that the pad was flush with the front of the box:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This is the time to remove the remaining plastic! Yes, it'll make the manipulating it a lot stickier than if you kept the plastic on, but in my experience with my first guinea pig boxes, it was extremely difficult to remove the plastic once the pad was molded in place.
> 
> The top and bottom are simply folded over and pressed in place. The back is also mostly just folded over. The tricky part is to them take the remaining flaps and to mold them into the holes in the back of the box:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The most important part of all of this is to make sure that the cable entrance into the outlet box is fully covered. I accomplished this by wrapping the putty around the cables first, and then pushing the hole mess up into the hole. It covers it up very well:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You may note the exposed area on the bottom of the outlet box. I'm pretty sure that doesn't matter. It is notable that the putty wasn't as stretchy as I thought it would be, based on a video I saw for the Hilti pads. They do stretch a little, but not a lot so don't count on that.
> 
> And that's it. I tested the outlets by shining a powerful flashlight from below, behind, and above the box and looked for any light to show through. I also shined it into the box and looked for any light leakage coming out the back. I'm glad I took this step because three of my earlier boxes did have some tiny holes that weren't visible at a glance but were clearly there with the light. Fixing those was easily done by just molding the putty over the discovered holes.
> 
> Have fun!





BasementBob said:


> Granroth:
> 
> 
> a) Shouldn't you apply the putty about half an inch (or 1-1/4" in your case) from the front edge to allow for 1/2 drywall to be flush with the box ?
> b) Shouldn't you be wrapping the boxes on five sides first, and then nailing them to the wall ?


----------



## mtbdudex

Door handle 101 on HT doors.

Going for sealed here, is there any door handle brand/type or am I over thinking this and any door handle is "ok" enough?
Non-locking.

I just installed my "BFD" Big Frickin Door (4 foot wide), it's solid core and heavy.

My brother came over this morning and helped me install the door, boy is it big and heavy!!! 
(Yea - that's him and he's a ham at times.....)

Big door allows epic sporting events viewing and playing games in the rec area, while door shut then quiet in the HT and outside the HT. 
Solid core door, not hollow. For now I'm not adding more mass inside, will wait/see if I desire, the DD + GG as others have done.
I'll be adding 4th and 5th hinges, just wanted to get it installed.
Will spray the door/windows sealant between to keep airtight, install wood trim 1 side, apply sealant to gap, let dry 24 hours, apply trim other side.
Full 3 sided perimeter seal + auto door bottom seal will also be added.

btw can I say it was a really good feeling to see the door open nicely all 180 degrees and still perfectly level to carpet all the way.







.









Not soundproofing related, but safety related.....
That door opens 180 degrees, and closes that full distance....anyone see some hydraulic shock absorbers for the open the door hard swing kid?
Also the slam the door shut kid?
Possible this? Seems adjustable
http://www.stanleydoorclosers.com/index.asp?Mode=D3550


> *Delayed Action* - Optional
> The D-3550DA / D-3551DA Series Door Closers are equiped with a seperate hydraulic valve adjustment to delay the closing speed from 180 to 70 degrees of door opening range.





















> *Introduction*
> The model D3550 Series is Stanley’s most versatile Door Closer. The reduced body profile provides ease of installation on light duty applications. In addition the R-14 Silicon Aluminum construction provides dependable performance under heavy loads associated with high use institutional applications. The D3550 Closer accommodates a variety of standard and heavy-duty arm applications.
> 
> *Features*
> *Fully Hydraulic Checking*
> Controls the door through the entire opening and closing cycles by providing adjustable backcheck upon opening and adjusting general and latch speeds through the closing cycle.
> *
> 
> 
> 
> 
> 
> 
> 
> *
> (1) opening swing, no checking
> (2) backcheck
> (3) general speed
> (4) latch speed


Just kills the look from outside the HT in the rec room.....


----------



## BasementBob

mtbdudex:
I don't know the answer to your question "How incrementally effective are putty pads over a good air tight sealed blue box with silicone"),
but I can tell you that putty packs add mass and damping there.


----------



## BasementBob

mtbdudex:
Door Handles:


From a soundproofing point of view, the best door handle is no latch, no knob, but instead to use:
- hydraulic door closer (this is used to actually close the door -- must be strong enough to press the door into seals)
- horizontal bar (universal symbol of push me) on the push side
- vertical bar (universal symbol of pull me) on the pull side

Doing this means there's no hole through the door for sound to go through.


----------



## cw5billwade

granroth said:


> Two layers of drywall will nearly always be the less expensive option, but it will vary by your local suppliers. In my case, I can get 5/8" Type X drywall for about $12 a 4x8 sheet and 5/8" (19/32") OSB for $14/sheet.
> 
> Hmm.. that's less than when I sourced it out earlier this year. Back then, there was roughly a $5 difference per sheet and I couldn't justify the extra $130 it would add to my costs. Still, even with that, I was being penny-wise and pound-foolish. Not doing OSB as the first layer was one of my notable mistakes in my theater that if I could go back in time, I'd definitely change.


Not sure why you never listen to me


----------



## mtbdudex

Thx Bob, my door has hole in it already, so knowing that "best" handle for soundproof noise leakage containment is....

Putty backers.....When I look at the total surface area of walls, then the .001% blue box occupies, and the small incremental increase putty has on sound containment (outside of air leakage, as assumption is sealed via silicone), my gut feel is not worth the incremental cost. 

Via Mikes brain/thumb interface, LLAP


----------



## BasementBob

mtbdudex said:


> Putty backers.....When I look at the total surface area of walls, then the .001% blue box occupies, and the small incremental increase putty has on sound containment (outside of air leakage, as assumption is sealed via silicone), my gut feel is not worth the incremental cost.


 
You may have come to the right conclusion for the wrong reasons, although (a) might agree with you. 


Even a tiny hole can let a lot of sound through it.


But I think your conclusion is right nonetheless because:
a) NRC (Canada's National Research Council), and Brian R of GreenGlue, each did a bunch of tests on the effects of having electrical boxes in the same wall cavity between the same pair of studs, and with or without insulation -- and the differences were measurable but minor. So putty will have a minor benefit on things that are already minor.
b) Granroth will probably add his own thoughts, but from what I've seen he did the putty packs but his door is letting orders of magnitude more sound energy through than the walls so whatever effect his putty packs might have had they're so minor as to not be measurable. i.e. His putty probably has a minor benefit on things that are utterly irrelevant.
c) HVAC


The best way, from a soundproofing point of view, to do electrical outlets is not to put them through the drywall, but to surface conduit mount the electricity perhaps behind horizontal molding, and put the actual outlets in the in-the-room columns.


----------



## BasementBob

mtbdudex said:


> my door has hole in it already, so knowing that "best" handle for soundproof noise leakage containment is....


 
I was thinking Plastic Wood and you mentioned your intent of additional layers.


Hmm. Zero International doesn't sell door handles/latches. (they do sell flood water systems, and radioactive protection systems)


----------



## granroth

BasementBob said:


> You may have come to the right conclusion for the wrong reasons, although (a) might agree with you.
> 
> Even a tiny hole can let a lot of sound through it.
> 
> But I think your conclusion is right nonetheless because:
> a) NRC (Canada's National Research Council), and Brian R of GreenGlue, each did a bunch of tests on the effects of having electrical boxes in the same wall cavity between the same pair of studs, and with or without insulation -- and the differences were measurable but minor. So putty will have a minor benefit on things that are already minor.
> b) Granroth will probably add his own thoughts, but from what I've seen he did the putty packs but his door is letting orders of magnitude more sound energy through than the walls so whatever effect his putty packs might have had they're so minor as to not be measurable. i.e. His putty probably has a minor benefit on things that are utterly irrelevant.
> c) HVAC
> 
> The best way, from a soundproofing point of view, to do electrical outlets is not to put them through the drywall, but to surface conduit mount the electricity perhaps behind horizontal molding, and put the actual outlets in the in-the-room columns.


The whole "orders of magnitude" aspect of soundproofing is something that isn't covered enough, IMO. Similarly -- bang for the buck.

There are a bunch of proven techniques and products that will absolutely contribute to reducing sound transference in and out of the theater. They tend to not be compared to each other in terms of just how much of a punch they will have, though. As in, maybe you spend $1000 on one product, but its effect is utterly _dwarfed_ by another aspect of the theater to the point that it's only measurable with sensitive instruments and not at all subjectively.

I do think my theater is a good example of this, especially pertaining to my door. I spent the $1000 on Green Glue, but I'm pretty sure that if I don't shore up my (already pretty beefy) door, then that investment will not have any real world benefits. That is, the amount of sound energy absorbed by the Green Glue compared to just the walls isn't even noticeable compared to how much sound is getting out via the door.

That's where orders of magnitude really comes in. Just completely making up numbers, let's pretend that:

Decoupling = 1000x
Mass = 100x
Damping = 10x
Sealing = 1x

If we know this type of thing, then we can say that maybe going all-in on making sure the entire theater is sealed tight as a drum wouldn't be worth it until after you properly handled all of the other more impactful types first.


----------



## ck3545

cw5billwade said:


> Not sure why you never listen to me


Is there a notable difference using osb as the first layer vs drywall? I realize it would be easier putting the second layer up since you can just screw to the osb rather trying to find the channel but I thought drywall was denser and would give you better soundproofing. Could be wrong, definitely wouldn't be the first time.


----------



## BasementBob

granroth said:


> Two layers of drywall will nearly always be the less expensive option, but it will vary by your local suppliers. In my case, I can get 5/8 inch Type X drywall for about $12 a 4x8 sheet and 5/8 inch (19/32 inch) OSB for $14/sheet.


I see on craigslist there's 50 sheets of OSB for $1 per sheet. A gone out of business sale or something.


----------



## BasementBob

ck3545 said:


> Is there a notable difference using osb as the first layer vs drywall? I realize it would be easier putting the second layer up since you can just screw to the osb rather trying to find the channel but I thought drywall was denser and would give you better soundproofing. Could be wrong, definitely wouldn't be the first time.


Several people have put OSB as a first, or middle layer. As long as the mass per square foot is the same, it's my understanding that it doesn't make much difference. So, a 1/4 inch layer of OSB is much worse than 5/8 inch of drywall; but a 5/8 inch of OSB (density 640 kg / m^3) is the same mass per square foot as 1/2 inch of drywall (800 kg / m ^3). OSB being 80% of the density of drywall, and different other properties. The nail holding strength of drywall is pretty awful, whereas OSB is much better. Plywood is better still at holding nails and is stronger, but its may be less dense again (e.g. 450 kg / m ^ 3; or 56% of the density of drywall). Usually drywall is a cheaper than OSB, and a lot cheaper than plywood. Drywall is much better as a fire stop.

If you've got studs you're screwing into, then the OSB allows you to screw anywhere, although screwing into a stud is always stronger (remember the Hyatt Regency walkway collapse 1981). If you've got hat channel, you still have to watch where you put the screws even with OSB, lest ye short the channel by screwing the drywall into a stud.


----------



## cw5billwade

Even with OSB and drywall you still must hit the chanel. You do not want twice the weight hanging on half the screws. Sometimes an edge of the drywall does not line ip with a chanel it is ok to screw only to the I SB then. Just snap lines on every layer where the channel. 1st layer uses shorter screws


----------



## ck3545

BasementBob said:


> Several people have put OSB as a first, or middle layer. As long as the mass per square foot is the same, it's my understanding that it doesn't make much difference. So, a 1/4 inch layer of OSB is much worse than 5/8 inch of drywall; but a 5/8 inch of OSB (density 640 kg / m^3) is the same mass per square foot as 1/2 inch of drywall (800 kg / m ^3). OSB being 80% of the density of drywall, and different other properties. The nail holding strength of drywall is pretty awful, whereas OSB is much better. Plywood is better still at holding nails and is stronger, but its may be less dense again (e.g. 450 kg / m ^ 3; or 56% of the density of drywall). Usually drywall is a cheaper than OSB, and a lot cheaper than plywood. Drywall is much better as a fire stop.
> 
> If you've got studs you're screwing into, then the OSB allows you to screw anywhere, although screwing into a stud is always stronger. If you've got hat channel, you still have to watch where you put the screws even with OSB, lest ye short the channel by screwing the drywall into a stud.


Makes sense, thanks for the information. I was planning on running two sheets of 5/8 drywall so per your info of the osb being the same density as 1/2 drywall I will stick with the original plan. Plus it will be a little cheaper, not much since it is only about a $2.00 difference per sheet here.


----------



## ck3545

cw5billwade said:


> Even with OSB and drywall you still must hit the chanel. You do not want twice the weight hanging on half the screws. Sometimes an edge of the drywall does not line ip with a chanel it is ok to screw only to the I SB then. Just snap lines on every layer where the channel. 1st layer uses shorter screws


This is one of those ahh ha moments, didn't even think about the weight.


----------



## BasementBob

cw5billwade said:


> You do not want twice the weight hanging on half the screws.





ck3545 said:


> This is one of those ahh ha moments, didn't even think about the weight.


I don't recall any stories of drywall falling off the walls. Lots and lots of nail pops though.
The only story I recall of drywall falling was off a ceiling. The builder had used glue to put up the drywall (no screws), and an entire sheet fell on someone's head while they were sitting at their computer.
But as for 'twice the weight on half the screws', I always recall what happened at the Hyatt Regency walkway collapse 1981. The falling walkways killed 114 and injured a further 216 people. At the time, it was the deadliest structural collapse in U.S. history. The two elevated walkways, one on the second floor and the other at the forth floor, were supported by threaded rods from the ceiling. In the original design, approved by the engineers, a single rod went from top to bottom. But as built, a shorter rod went from the ceiling to the forth floor, and then a separate rod was used from a different part of the forth floor down to support the second floor walkway. This meant that the nut holding up the forth floor was now not only holding up the forth floor walkway, but also the second floor walkway, doubling the load on the nut. It also meant that the structure of the forth floor walkway was not only holding up the people on it, but also the entire weight of the second floor walkway, and it wasn't designed for that either. This new design was barely adequate to support the dead load weight of the structure itself, much less the added weight of the spectators. On the evening of July 17, 1981, approximately 1,600 people gathered in the atrium to dance, second-level walkway held approximately 40 people and an additional 20 on the fourth level. The threaded rod connection failed, and the fourth-floor walkway collapsed onto the second-floor walkway. Both walkways then fell to the lobby floor below, resulting in 111 deaths at the scene and 219 injuries.

http://upload.wikimedia.org/wikipedia/commons/2/29/HRWalkway.svg


----------



## cw5billwade

ck3545 said:


> Makes sense, thanks for the information. I was planning on running two sheets of 5/8 drywall so per your info of the osb being the same density as 1/2 drywall I will stick with the original plan. Plus it will be a little cheaper, not much since it is only about a $2.00 difference per sheet here.


Never us 1/2" anything. Use the 5/8 OSB (19/32) and 5/8 fire rated heavy stuff DW with green glue sandwich


----------



## cw5billwade

I am glade I went with OSB


----------



## ck3545

cw5billwade said:


> Never us 1/2" anything. Use the 5/8 OSB (19/32) and 5/8 fire rated heavy stuff DW with green glue sandwich


Wasn't planning on 1/2, was just referring to basementbob stating 5/8 osb being the same density as 1/2 drywall. I would definitely rather use osb, hate working with drywall. I see that your theater is on the second floor, mine will as well since we don't do basements in oklahoma. What did you do with the floor in the theater? Also did you do anything with the ceiling on the first floor? Looking over the soundproofing company website what they show for the first floor ceiling is insane especially with the open floor concept. If the theater was centered over a specific room or the garage it would be ok but that is easier said than done.


----------



## granroth

ck3545 said:


> Wasn't planning on 1/2, was just referring to basementbob stating 5/8 osb being the same density as 1/2 drywall. I would definitely rather use osb, hate working with drywall.


Then use OSB. Yes, it's true that 5/8" OSB doesn't have the same mass as 5/8" Type X drywall and yes, because it has different stiffness, Green Glue isn't quite as effective. It's crucial to keep in mind that those are _relative_ differences that don't necessarily translate into meaningful differences in the end result.

Ted White, of Soundproofing Company fame, has gone on record as saying that the differences between using 5/8" OSB and 5/8" drywall as the first layer are _negligible_ from a soundproofing perspective. Indeed, many people have gone that route and I've heard no complaints afterwards.

I have heard complaints from people that went with two layers of drywall and wished they had used a layer of OSB. I am one of them! I kick myself on a regular basis for not using OSB, since it would have made quite a few things that followed easier.


----------



## cw5billwade

ck3545 said:


> Wasn't planning on 1/2, was just referring to basementbob stating 5/8 osb being the same density as 1/2 drywall. I would definitely rather use osb, hate working with drywall. I see that your theater is on the second floor, mine will as well since we don't do basements in oklahoma. What did you do with the floor in the theater? Also did you do anything with the ceiling on the first floor? Looking over the soundproofing company website what they show for the first floor ceiling is insane especially with the open floor concept. If the theater was centered over a specific room or the garage it would be ok but that is easier said than done.


I added a second layer of 3/4" T&G OSB on the floor with green glue. Since my theater is over a garage it is not an issue. My cars do enjoy the base on some of the louder scenes though. If I were over another room I would have done the floating floor like seen on SoundProffingCompany with the serinty mat. I was debating on it but decided not to since over garage. Couldn't justify the expence. If it is not to late and this is a new build have them put R19 in between the floors.


----------



## mtbdudex

ellisr63 said:


> I am ordering my door seals, and I am not sure which to get.
> 
> Should I get this one... http://www.tmsoundproofing.com/Door-Seal-Self-Adhesive.html
> 
> or this one... http://www.tmsoundproofing.com/Door-Seal-Self-Adhesive-Batwing-style.html
> 
> I am also trying to decide between these 2 auto door seals...
> http://www.tmsoundproofing.com/heavy-duty-automatic-door-bottom-soundproof.html
> 
> or this one...
> http://www.tmsoundproofing.com/Heavy-Duty-High-Sound-Automatic-Door-Bottom.html
> 
> 
> Should I get a threshold too? http://www.tmsoundproofing.com/Utility-Door-Threshold-1-4-Height.html
> We have 2 solid core doors separated by 6' and the hallway is more of a ramp like you see in the theaters... We will have carpet once you cross the first threshold. Outside of the first door is flagstone.


What door and threshold seal did you end up installing?
How did it go? Post some picts if not already.
I'm ready to order mine and going thru similar thoughts as you.


----------



## d_c

cw5billwade said:


> Just use the IB-3 clips to your ceiling joists every 48" for your wall. On the wall parallel to the joist you will have to put nailers in for the clips.
> 
> My wall is not against concert but the principle is sill the same. I attached IB-3 clip to the existing wall but you can see the nailer I installed for the IB-1 clips and channel I could have just as easy attached to the nailer which is what you would do.


I have existing side walls connected to the ceiling next to the concrete basement walls. I can tear them to the studs or tear them all the way out and rebuild them as shown in the pics above. If I will be building new side walls is doing this method above different than using clips and channel on my existing wall? Would clips and channel be used also on the side walls in the photos above?

Edit:
I found the answer- 



cw5billwade said:


> First you frame wall using IB-3 clips decoupled from the floor joist. Then clips and channel on ceiling. You do the first layer of DW on ceiling then first layer on walls. Then second layer with green glue on ceiling then walls. I used OSB on my first layer. Insure you use 5/8" DW


1" from the ceiling joist, 1" from the concrete walls, ib3 on the end of each wall and every 48"



ClemsonJeeper said:


> Nope.
> 
> Frame the room fully first. For walls on cement foundation, put them 1" from the foundation and 1" from the joists. Use IB3 brackets to attach the walls to the joists (follow specifications on spacing of brackets).
> 
> Once all walls are framed, hang clips + channels where needed (ceiling and any walls that aren't decoupled from the house).
> 
> After that, hang drywall on ceiling first, then walls, then acoustic caulk where the ceilings meet the walls and the corners of the walls, as well as the floor to wall gaps. Then hang ceiling + GG, then walls again with GG. Then caulk all gaps again.



So, my only question would be: Would clips and channel be used also on the side walls if I build them 1" short and decouple them with ib3 clips?


----------



## granroth

d_c said:


> So, my only question would be: Would clips and channel be used also on the side walls if I build them 1" short and decouple them with ib3 clips?


If your side walls are completely disconnected from the exterior walls, then there is no need for clips and channels. The inner walls will give you the decoupling that you need. Clips and channels are needed only if you have a single set of walls.

Or ceiling, for that matter. If you have an inner set of walls but still one ceiling, then you'll want to use clips and channels on that and attach your decoupled walls to the joists using IB-3 or similar.


----------



## cw5billwade

d_c said:


> I have existing side walls connected to the ceiling next to the concrete basement walls. I can tear them to the studs or tear them all the way out and rebuild them as shown in the pics above. If I will be building new side walls is doing this method above different than using clips and channel on my existing wall? Would clips and channel be used also on the side walls in the photos above?
> If you tare the drywall off you can just use the clips and channel to decouple the wall. If you want to take the wall down and use IB-3 brackets on them then your comment below applies. Either way will be fine. IB-3 route is cheaper since you will be reusing the curent framing materiel and only require about 4 IB-3 brackets compare to a dozen or so IB-1 clips and channel.
> Edit:
> I found the answer-
> 
> 
> 
> 1" from the ceiling joist, 1" from the concrete walls, ib3 on the end of each wall and every 48"
> 
> 
> 
> 
> So, my only question would be: Would clips and channel be used also on the side walls if I build them 1" short and decouple them with ib3 clips?


what Granoth stated is corect IB-3 or clips and channel not both.


----------



## d_c

Great, thanks guys. I spent the whole day reading the entire thread and now I have a plan.


----------



## mtbdudex

Q on the side seals and bottom seal:
How did you install the side jamb seal and door bottom seal so there was no slight gap in the corner where the door bottom seal swings into contact?


----------



## KanosWRX

mtbdudex said:


> Q on the side seals and bottom seal:
> How did you install the side jamb seal and door bottom seal so there was no slight gap in the corner where the door bottom seal swings into contact?


That gap on the left and right of the bottom seal is where the door stop/jam touches the door to prevent it from swinging through. You would have to cut out part of the side seals so it doesn't interfere with the bottom seal when shut. If everything lines up there shouldn't be any gaps/holes.


----------



## Tnedator

KanosWRX said:


> That gap on the left and right of the bottom seal is where the door stop/jam touches the door to prevent it from swinging through. You would have to cut out part of the side seals so it doesn't interfere with the bottom seal when shut. If everything lines up there shouldn't be any gaps/holes.


I assume if you go with a fully mortised version that it goes from one end of the door to the other, and doesn't have the same gaps on each side. Correct?


----------



## kmhvball

Hmmm... good question... I am doing the Zero International seals all the way around, I wonder if I should cut the 'side' jamb stops 'short', so, the bottom is the full width, right up to the side jamb??


----------



## cw5billwade

seems to me the door stop has the sound striping and goes to the floor so why would you do that? That is why the picture has the bottom seal short to accomindate the door stops which are already isolated. If you look at the directions for the zero international door stops that is how you install them top to bottom and cut the bottom seal to fit. no issue.


----------



## kmhvball

Okay, I haven't looked at the instructions yet - but that makes sense, particularly for me since I have the 'all round the door' seals.


----------



## mtbdudex

I'm asking because I can't grasp it clearly with the pictures given, if people have these installed please post a pict will help others. Fwiw I just ordered mine.


Via Mikes brain/thumb interface, LLAP


----------



## kmhvball

Here is a picture of the all over door bottoms, I probably should have looked through my documentation before my original post!


----------



## mtbdudex

So the rubber seal extends slightly past the metal by 1/16" or so each side? 
To give a slight interference fit for positive seal?
Yea, just tell me I'm over-thinking the details .....

Via Mikes brain/thumb interface, LLAP


----------



## granroth

This conversation about the seals just now made me realize that I installed my bottom seal on the wrong side of the door! 

Okay, so the automatic door bottoms are cut to fit the width of the door and the rubber gasket on the bottom is the full width. This is an extreme closeup of the non-pin side of one:










Note that there is a gap between the door and the jamb, and a resulting gap between the seal and the jamb. This is necessary or else the door won't close!

This isn't supposed to be a problem because you'll have full length vertical stops on the outswing side of the jamb that the door will press against. Here's an attempt to show the door pressed into the stops on the other side:










Literally as I took that picture I realized that my door bottom was on backwards. If it was on the outswing side of the door, then the side gasket will overlap not only the door but also the metal part of the door bottom and the gasket. That is, there will be a complete seal in that corner.

I put mine on the inswing side of the door and so I have a tiny gap that goes from the side of the door to under the door and out. Oops. Good thing I was already planning on putting another layer of stops and gaskets!


----------



## RMcNeil213

What would be my best option of soundproofing in a rented home? I can't exactly put up drywall and tear apart the walls so i'm looking for something I can externally hang and whatnot to avoid vibration going into the other rooms as much as possible. I have the CM9's with the CMC2 Center and the CM Sub from BnW in a 10x11 room on the 2nd floor. I've been looking into acoustic panels but from what i researched they don't soundproof but just help with the acoustics of the speakers. I already planned to lay the floor with padding and carpet but not sure on the type i should lay down. Any help is really appreciated.


----------



## granroth

RMcNeil213 said:


> What would be my best option of soundproofing in a rented home? I can't exactly put up drywall and tear apart the walls so i'm looking for something I can externally hang and whatnot to avoid vibration going into the other rooms as much as possible. I have the CM9's with the CMC2 Center and the CM Sub from BnW in a 10x11 room on the 2nd floor. I've been looking into acoustic panels but from what i researched they don't soundproof but just help with the acoustics of the speakers. I already planned to lay the floor with padding and carpet but not sure on the type i should lay down. Any help is really appreciated.


Man, I hate to be the bearer of bad news, but if you are renting, then there's not really all that much that you can do to make a substantial impact in soundproofing. The key problem is that the cornerstone of sound reduction is _mass_ -- the more, the better. If you don't have the mass to begin with, then it's difficult to make any of the other touchstones, like decoupling or damping.

You might have some luck hanging something like mass loaded vinyl, which would give you mass and damping, but more than likely the amount of money you'd have to spend to make a substantive difference would not be worth it. MLV is not cheap and you'd need a lot of it.

One high bang-for-buck thing that you likely could do is replace the door with a solid-core model, and then make sure it is sealed when you're watching a movie. A hollow core door with gaps around is a very big vector for escaping noise, since it offers up very little resistance. A sealed solid-core door would make a noticeable difference.

Now... I'm going to leave this for last, since 99% of people renting won't consider it. But if you are willing to completely repair the room when you leave AND are willing to spend the money, then ripping down the drywall and putting up clips+channel with double layer DW and Green Glue would make a massive difference. You may need to rip it all out and replace it with regular drywall afterwards, though. Unless, that is, you work with your landlord and convince her that you're improving the room and that she can get those improvements for nothing when you're gone.


----------



## Potatogod93

Soffit Coupling questions

My soffit plan calls for a soffit at the front and back of my room to hide two I-Beams. The front of the room will be the width of the room about 1 1/2 feet long and the soffit in the back of the room will also be the width of the room, but about 4 feet long. My walls are decoupled using IB-3 clips and the double wall practice. My soffits I am planning to just bolt into the floor joists above and then the drywall will be decoupled with IB-1 clips and 7/8 furring channel. My question is how to put the soffit into the other walls. Simple thing would be build as normal and couple the soffit to the wall. Ted has told me this could create some conduction but by his wording I am not sure if it would create enough conduction to worry about? 

My other option as I see it would be put IB-1 clips and channel for the connections at the side and back wall connections.


----------



## marjamar

I have to ask a question. If I isolate sound vibration to the drywall by using hat channel and clips, it would seem to me the drywall will vibrate more, not less as there is less holding it and less mass, then if fastened directly to the framing and framing to the house structure. If this is correct (I suppose it has to be), the coupled transfer points (screws in the clips) would have to be receiving a much stronger level of vibration then as well. This localized, higher level of vibration would then radiate stronger at these points then, I would suppose. Is it possible then to actually have a greater amount of this vibration to transfer better from these areas to surrounding objects close to the source of this vibration? It just seems to me these localized points of extreme vibration could in fact cause more sound to reach outside of the theater in certain areas where this vibration can reach closer objects outside the theater area itself. 

Maybe a stupid question, but I am in the process of installing right now, and my limited amount of knowledge here is troubleing me.

Thanks.

-Rodger


----------



## LeBon

The way I think of it is that the clips and channel reduce conduction of the sound waves through the structure. and allow the drywall to vibrate, which dissipates the sound energy. The sandwich of drywall and Green Glue use mass (of the drywall) and damping (the Green Glue) to dissipate the sound energy in the wall.

But don't forget that keeping outside sounds out (reducing the noise floor) is equally, if not more important.


----------



## Potatogod93

Well I am still planning on clips and channel for the drywall on the soffit. My question is more so for the points of contact between the soffit framing and the wall framing? As if vibrations are conducted through the soffit frame to the wall frame to the drywall and vice versa (as the DDw/GG on the walls is not decoupled as the walls are using the double wall w/ IB-3 clip method of decoupling).


----------



## cw5billwade

if the DW is screwed to the non decoupled studs then the vibrations will make its way through the entire house. The IB-3 clips for double wall and the Clips and channel for non double wall, ceiling, and soffits keep the sound vibrations from the vibrating the studs they are attached to (floor Joist)


----------



## marjamar

Well my son suggested d/l'ing an app on my iPhone to read vibration. I did and did a few tests, but it was non-conclusive. Told my son to d/l one on his android and we tried that. This particular app or perhaps the android (Samsung S3) was far more sensitive and we actually did get good enough readings for comparison.

To preface this a bit... I had found the hat channel at home depot here in town. Unfortunately, no place around here had clips. Looking closely at what the clips were from the manufactures website, I got the greatest impression that the most they would do is use a single screw point instead of 2 and perhaps allow even a bit more vibration to happen without transferring as much of it to the screw by way of the clipping system holding the channel. So, what I did was buy alot of 1" felt pads from home depot and stuck one pad under each screw point between the channel and the stud/joist. This held the channel about 1/8" away from the framing and allowed the channel to vibrate very well when tapped. So much so in fact, I really felt this was really going to allow the drywall to vibrate even more then it would normally. So, my concerns over this is what led me to my first post here and my continued experimenting with the phone apps.

So, what I did find using the android vibration sensor app was that tapping a stud a few feet away from the phone setting on a joined stud transfered the tapping vibration about 3 times as high as tapping a channel fasted firmly to the stud. Fastening the channel using the felt pads transfered about 6 times the vibration to the sensor. Now these taps were either directly on the stud, or directly on the fastened channel (either directly to a stud, or through a felt pad and to the stud). Taps were repeated at different places, testing all 3 connecting methods. In each and every case, the readings were almost identical in their relative values to one another.

So, again what this means to me is, vibration will transfer more readily for some reason though felt/screw contacts to framing then if the channel is fastened directly to the framing. The highest transfer is through the framing itself. The unresolved quiestion in my mind is, when drywall is fastened to the channel, would less sound be transfered by the channel fastend directly to the studs, or with the channel fastend though the felt pads/screws to the studs?

I simply do not know the answer, but since I need to keep this build going, I made a choice and decided to fasten the channel directly to the studs/joist. I do know this will be better then putting the drywall directly to the stus, which is what I was going to do a couple days back.

-Rodger


----------



## cw5billwade

that is because the screw coupled the Hat channel to the stud. Does not matter you had felt or not the channel was short curcited to the stud. I used the IB-1 clips in the last image the first two images are whisper clips which are better but cost 2.5 x as much. go to sound proofiing company's web site for mor information. Also you do not attach to every stud and there is intervial spacing to consider.


----------



## marjamar

Thanks for the info and helps.

Decided to continue the build without clips or felt pads. The level of sound leaving this basement has been getting progressively better with the more insulation and drywall I have been adding in both the theater area and in the bathroom and sauna. I'm pretty sure using these hat connectors for the drywall in the theater will bring incoming/outgoing sound to a reasonable enough level to be happy with it. Looking at how far I have come in this build and how far I yet to go, I just have to limit the start/stop sequences or it will no doubt become a never ending story. My hope is to have all of it done within another 2 months max, as I have house guests coming in from out of state for a visit in mid to late April. I'd like to have them enjoy what's been done, not wish it were done to enjoy it.

Here's a couple pics to show where I am with the build.

So, on with the show!

Thanks again.

-Rodger


----------



## cw5billwade

@marjamar do you have your projector shooting down on that angled shelf in the soffit? I ask because I assume you are then using the keystone setting to get a square image. If so this will not work later if you decide to get a better projector or a lens sled. Most projectors can not use keystone in auto format or 3D.


----------



## marjamar

cw5billwade said:


> @marjamar do you have your projector shooting down on that angled shelf in the soffit? I ask because I assume you are then using the keystone setting to get a square image. If so this will not work later if you decide to get a better projector or a lens sled. Most projectors can not use keystone in auto format or 3D.


Good to know, appreciate it. At this point, I will keep it like it is. If and when I need to buy another projector, I will make sure it has some way to square the picture to the screen. 

Thanks for the info.

-Rodger


----------



## cw5billwade

marjamar said:


> Good to know, appreciate it. At this point, I will keep it like it is. If and when I need to buy another projector, I will make sure it has some way to square the picture to the screen.
> 
> Thanks for the info.
> 
> -Rodger


Before you seal up the soffit you may want to make it so that the shelf can also be taken out and put back in flat that will be more flexible down the road


----------



## marjamar

cw5billwade said:


> Before you seal up the soffit you may want to make it so that the shelf can also be taken out and put back in flat that will be more flexible down the road


It will have a door in it. The whole concession area (the whole rear of the theater) will have custom built in cabinetry. That alone will take me about a month or so to build. Thanks to all the input.

-Rodger


----------



## cw5billwade

Start a build thread we can move the conversation there


----------



## marjamar

I actually did that before posting here. Here's the link: http://www.avsforum.com/forum/19-de...-just-hello-new-home-theater-diy-builder.html

Thanks.

-Rodger


----------



## Jacob B

Jacob B said:


> Hi,
> I would like some advice on what the best way to lay my black oak hardwood floor in my dedicated Home Theater.
> 
> I have sound proofed the room as described in this *post*.
> 
> Quoting from the post, "_Finally, I had another contractor lay a double 5/8"OSB floor with green glue, on top of a 10 mm rubber matt I bought from an Italian company called Isogomma. Underneath the the rubber matt were the original wooden pine boards.
> Underneath the pine boards is a large cavity - 8" high - and then the house's original flat roof made out of roofing felt.
> Update December 5, 2014: I just accepted an offer from a contractor to fill out the 8" cavity with paper wool_"
> 
> So, the question is how to lay the 15 mm oak floor. It is a multi-layer/laminated parquet floor with two plywood layers and a 3.6 mm oak layer on top, and with tongue and groove.
> Charcoal Oak from Soldidfloor
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *I see three options:*
> *1)* Glue it directly to the double OSB w/ GG underfloor with specialized glue. The parquets/panels are also glued to each other in the tongue and groove.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *2)* Green glue it directly to the double OSB w/ GG underfloor. The parquets/panels will be glued to each other in the tongue and groove with standard tongue and groove glue.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *3)* Lay it floating on a 1/8 to 1/4" subfloor, on the double OSB w/ GG.
> 
> 6 mm soft board
> 
> 
> 
> 
> 
> 
> 
> 
> 
> or (3 mm)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> or 2 mm kork:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *My goal *is to optimize sound proofing, as well as the acoustical character of the floor.
> 
> Thanks


I would really like some comments from the experts in this thread  
Thanks,
Jacob


----------



## ScottOsb

marjamar said:


> Thanks for the info and helps.
> 
> Decided to continue the build without clips or felt pads. The level of sound leaving this basement has been getting progressively better with the more insulation and drywall I have been adding in both the theater area and in the bathroom and sauna. I'm pretty sure using these hat connectors for the drywall in the theater will bring incoming/outgoing sound to a reasonable enough level to be happy with it. Looking at how far I have come in this build and how far I yet to go, I just have to limit the start/stop sequences or it will no doubt become a never ending story. My hope is to have all of it done within another 2 months max, as I have house guests coming in from out of state for a visit in mid to late April. I'd like to have them enjoy what's been done, not wish it were done to enjoy it.
> 
> Here's a couple pics to show where I am with the build.
> 
> So, on with the show!
> 
> Thanks again.
> 
> -Rodger


Just a quick note. I didn't want to pay the expense of special clips either. Found an alternative by using concrete expansion joints, which is rubber about 3/8" x 4" x 5' long. Sliced into 2" pieces with a chop saw. Screwed it into the studs with 1 drywall screw in the center of it. Hat channel was screwed to the stud with the rubber under it, using screws with rubber washers on them. Worked good so far for me.


----------



## granroth

ScottOsb said:


> Just a quick note. I didn't want to pay the expense of special clips either. Found an alternative by using concrete expansion joints, which is rubber about 3/8" x 4" x 5' long. Sliced into 2" pieces with a chop saw. Screwed it into the studs with 1 drywall screw in the center of it. Hat channel was screwed to the stud with the rubber under it, using screws with rubber washers on them. Worked good so far for me.


Interesting. My first reaction would be to assume that using a setup like that wouldn't work at all like you're expecting it to. The goal of clips is to decouple the drywall from the studs and the setup as described isn't decoupled at all.

But maybe it would be better than nothing, though, since if you had the channel directly screwed to the studs, then you'd have not only the screw transmitting vibrations through, but you'd also have the edges of the channel doing the same. Inserting a rubber piece between them will still have the vibrations going through the screw, but now the vibrations from the edges of the channel are damped.

I'd be very curious to see what kind of difference that makes. My guess is that the vibrations through the screw would be so dominant that you wouldn't even notice the lack of vibrations from the edges. That's just a guess, though -- I'd love to see some tests that quantified the results.


----------



## marjamar

The felt pad idea could have worked as it did absolutely let the hat channel freely vibrate. The method I used to test it showed this, almost like a tuning fork freely vibrates when struck. My fear was that this free vibration may somehow allow the drywall to vibrate so much from sound waves that it would be louder then if dampened by a firmer contact between the studs/joist and the channel. 

The one thing I thought of, but didn't take the time to test was to load the channel with drywall and then test the felt pad connections. I would have to had built a small framework of channel/pads and mounted some drywall to it to test this and just didn't want to spend the time doing it. Maybe some people reading this would like to test further. Might be the best way to connect hat channel and no one is using it.

-Rodger


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## manfrog

Any thoughts on these clips? It would be for walls not ceilings (as per their suggestion on site) http://www.soundproofing.org/infopages/as1.htm












Gives some flexibility on the distance from hat channel face back to stud. DW could be min 7/8" off or more. Pretty inexpensive as well. 


Thanks!


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## cw5billwade

manfrog said:


> Any thoughts on these clips? It would be for walls not ceilings (as per their suggestion on site) http://www.soundproofing.org/infopages/as1.htm
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Gives some flexibility on the distance from hat channel face back to stud. DW could be min 7/8" off or more. Pretty inexpensive as well.
> 
> 
> Thanks!


when I went from the stock bushings and spring isolators to neoprene on my Mustang suspension I felt a whole lot more road noise and vibrations from the motor as a result. They do look like a good solution though. The second picture on that site shows how to use these clips with existing Drywall which would cause triple leaf and defeat the entire process. I wonder how much advise you can trust from a company that is making a blatant sound proofing no no like triple leaf? My IB-1 Clips from Sound Proofing Company were about the same price.


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## manfrog

cw5billwade said:


> when I went from the stock bushings and spring isolators to neoprene on my Mustang suspension I felt a whole lot more road noise and vibrations from the motor as a result. They do look like a good solution though. The second picture on that site shows how to use these clips with existing Drywall which would cause triple leaf and defeat the entire process. I wonder how much advise you can trust from a company that is making a blatant sound proofing no no like triple leaf? My IB-1 Clips from Sound Proofing Company were about the same price.


 


haha..yeah I noticed that as well...though they do have a line under that states _*"Call us to discuss what to do about the "Resonant Chamber" created."*_ So they are calling out it out. I think they are saying if you don't want to rip (or can't rip) down drywall then this is an option. Maybe they have an "solution" to the triple leaf. No clue and I don't have an answer myself. 


You happy with the IB1? I was looking at them as well due to the price and I seem to recall BigMouthDC stating pretty similar to more expensive clips. I am not going for a full bunker style soundproofing but want to make a decent effort at it. Budget is always a concern as $$$ can be spent elsewhere


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## cw5billwade

manfrog said:


> haha..yeah I noticed that as well...though they do have a line under that states _*"Call us to discuss what to do about the "Resonant Chamber" created."*_ So they are calling out it out. I think they are saying if you don't want to rip (or can't rip) down drywall then this is an option. Maybe they have an "solution" to the triple leaf. No clue and I don't have an answer myself.
> 
> 
> You happy with the IB1? I was looking at them as well due to the price and I seem to recall BigMouthDC stating pretty similar to more expensive clips. I am not going for a full bunker style soundproofing but want to make a decent effort at it. Budget is always a concern as $$$ can be spent elsewhere


Yes I am happy with IB-1 I still need to sound proof the door as that is my current weak link. The ULF at near reference still escapes though. As mentioned earlier and in other threads It would take the bunker stile Beast mode 3 layers of Drywall etc to contain that stuff.


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## pitviper33

Anybody know what happened to the soundproofing company (www.soundproofingcompany.com)? Their site appears to be down.


----------



## manfrog

cw5billwade said:


> Yes I am happy with IB-1 I still need to sound proof the door as that is my current weak link. The ULF at near reference still escapes though. As mentioned earlier and in other threads It would take the bunker stile Beast mode 3 layers of Drywall etc to contain that stuff.



Yeah the LF battle is one I will have to accept due to budget and not wanting a bunker on my main floor 


Thanks for the thoughts on the IB-1's...have to look at again.


I will need to look up the details of what you exactly did to combat the sound and see if there are any other tips I can pickup


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## granroth

marjamar said:


> The felt pad idea could have worked as it did absolutely let the hat channel freely vibrate. The method I used to test it showed this, almost like a tuning fork freely vibrates when struck. My fear was that this free vibration may somehow allow the drywall to vibrate so much from sound waves that it would be louder then if dampened by a firmer contact between the studs/joist and the channel.


Ah, I missed your first post about this. Weird.

Anyway, decoupling isn't so much about allowing or restricting the ability of the drywall or hat channel to vibrate but rather to reduce the amount of vibration that transmits to external surfaces. Double walls work even though the drywall is directly screwed into one wall with no channels or clips at all -- that's because there is a physical gap between the walls that prevents the vibrations from going any further than that first wall. Proper clips and channel work the same way by allowing the drywall and outer part of the clips to vibrate but drastically reducing the vibrations that get to the studs. This is done by having no rigid connection between the drywall+channel and the stud, since the screw is on the other side of the springy part.

The problem with putting a felt pad or rubber pad underneath the channel but still screwing directly from the channel into the stud is that you've made a very rigid connection between the drywall+channel and stud. The channel might be more disconnected than if it was directly resting on the stud, but the vibrations are still going travel very efficiently through the screw.

I mentioned earlier that I don't know of any tests that were done where a channel was partially damped like this but there are enough stories of rigidly connecting surfaces absolutely ruining soundproofing efforts to suggest that it very likely wouldn't help as much as one would like it to.


----------



## granroth

cw5billwade said:


> Yes I am happy with IB-1 I still need to sound proof the door as that is my current weak link. The ULF at near reference still escapes though. As mentioned earlier and in other threads It would take the bunker stile Beast mode 3 layers of Drywall etc to contain that stuff.


And honestly, I'm not convinced that three layers is enough, either. Everything I've read by the experts says that adding a third layer of drywall might get you another 3dB of attenuation. LFE at near reference would still be plenty loud, even damped by 3dB!


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## granroth

pitviper33 said:


> Anybody know what happened to the soundproofing company (www.soundproofingcompany.com)? Their site appears to be down.


It's up right now: http://www.isitdownrightnow.com/soundproofingcompany.com.html


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## xjagox

*Treating an outswinging door*

I just got around to installing the perimeter seals on my door. I did some highly unscientific testing (run a tablesaw and stereo in the room and listen from outside), and was disappointed in the amount of higher frequency noise that seems to make it through the door assembly. *Caveat*: _The room isn't fully sealed up inside yet- one soffit is only single drywall and not caulked tightly..._

It could be some flanking issue, but the worst of the sound _seems_ to come through the door jambs/seals. It would seem to me that the jambs themselves would be a pretty weak point in this kind of an outswing door setup since a piece of 1x poplar is really the only thing between the theater and the outside room (and the internal framing of the wall, which it is fastened to to make matters worse. 

I'm thinking maybe I at least need a layer of GG/MDF or something to cover the exposed jambs in the future? Anyone else have experience with a similar setup

Here is a diagram of my construction and a couple of pictures of the hinge side for reference:


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## granroth

xjagox said:


> I just got around to installing the perimeter seals on my door. I did some highly unscientific testing (run a tablesaw and stereo in the room and listen from outside), and was disappointed in the amount of higher frequency noise that seems to make it through the door assembly. *Caveat*: _The room isn't fully sealed up inside yet- one soffit is only single drywall and not caulked tightly..._
> 
> It could be some flanking issue, but the worst of the sound _seems_ to come through the door jambs/seals. It would seem to me that the jambs themselves would be a pretty weak point in this kind of an outswing door setup since a piece of 1x poplar is really the only thing between the theater and the outside room (and the internal framing of the wall, which it is fastened to to make matters worse.
> 
> I'm thinking maybe I at least need a layer of GG/MDF or something to cover the exposed jambs in the future? Anyone else have experience with a similar setup


Pretty much all of the experts I've read or talked to have said that a door jamb has very little impact on the soundproofing of a door. It seems very unlikely that that'll be your weak point in this case.

How are you determining that it's coming through the seals? Are you sure that it actually is sealing tight?

You _might_ just have unrealistic expectations for the performance of that door. I know I did when I created mine. Mine is similar to yours except that I added a second layer of MDF with another layer of Green Glue. I was told that I could maybe expect an STC 38 (give or take) from that door, if it was properly sealed (I have a tiny gap in one corner).

So if we assume your door performs at roughly STC 35 and your table saw is running at 85 dB, then you might be hearing sounds at roughly 50dB on the other side of the door. Maybe slightly higher since STC doesn't work exactly like that. That's not loud, but is very clearly audible.


----------



## xjagox

granroth said:


> Pretty much all of the experts I've read or talked to have said that a door jamb has very little impact on the soundproofing of a door. It seems very unlikely that that'll be your weak point in this case.
> 
> How are you determining that it's coming through the seals? Are you sure that it actually is sealing tight?


Just a guess that it is the seal/jamb area based on listening. I understand that locating sound by ear is tough, but it definitely seems to be the door in general that is the weak spot (and the ductwork to the rooms upstairs, which is in the unsealed soffit that I mentioned). I'm pretty positive that the seals are nice and tight everywhere.



> You _might_ just have unrealistic expectations for the performance of that door. I know I did when I created mine. Mine is similar to yours except that I added a second layer of MDF with another layer of Green Glue. I was told that I could maybe expect an STC 38 (give or take) from that door, if it was properly sealed (I have a tiny gap in one corner).
> 
> So if we assume your door performs at roughly STC 35 and your table saw is running at 85 dB, then you might be hearing sounds at roughly 50dB on the other side of the door. Maybe slightly higher since STC doesn't work exactly like that. That's not loud, but is very clearly audible.


Yeah, IIRC I measured it with a dB meter app on my phone and got ~85dB about a foot from the saw, ~75dB outside with the door open, and ~50dB outside with the door closed. Maybe I just need to wait until the room is fully sealed and take some better measurements with a microphone before feeling let down at all.


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## ScottOsb

granroth said:


> Interesting. My first reaction would be to assume that using a setup like that wouldn't work at all like you're expecting it to. The goal of clips is to decouple the drywall from the studs and the setup as described isn't decoupled at all.
> 
> But maybe it would be better than nothing, though, since if you had the channel directly screwed to the studs, then you'd have not only the screw transmitting vibrations through, but you'd also have the edges of the channel doing the same. Inserting a rubber piece between them will still have the vibrations going through the screw, but now the vibrations from the edges of the channel are damped.
> 
> I'd be very curious to see what kind of difference that makes. My guess is that the vibrations through the screw would be so dominant that you wouldn't even notice the lack of vibrations from the edges. That's just a guess, though -- I'd love to see some tests that quantified the results.


I think I missed spoke. The drywall is screwed to the hat channel, but not over a stud. So I think the isolation is there because of the rubber washers on the screws in combination with the rubber pads. I'm no expert, just trying to get it done before my wife finds out the costs


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## granroth

ScottOsb said:


> I think I missed spoke. The drywall is screwed to the hat channel, but not over a stud. So I think the isolation is there because of the rubber washers on the screws in combination with the rubber pads. I'm no expert, just trying to get it done before my wife finds out the costs


Oh, okay! Just so I have the full picture; the drywall is screwed to the hat channel and the rubber is screwed to the stud -- how is the hat channel attached to the rubber?


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## granroth

xjagox said:


> Yeah, IIRC I measured it with a dB meter app on my phone and got ~85dB about a foot from the saw, ~75dB outside with the door open, and ~50dB outside with the door closed. Maybe I just need to wait until the room is fully sealed and take some better measurements with a microphone before feeling let down at all.


Doors and windows are nearly always the weak links in any soundproofing solution. Short of creating a second communicating door, I don't know that there's a lot you could do to your existing door without spending a lot of money (e.g., putting an 1/8" sheet of lead would definitely help... and cost north of $500). Your best bet might be to accept the sound loss into the rest of the basement and count on most of the sound not making it to the upstairs/living area.

I'll say this, too... I think a lot of people (certainly I was one of them) come into soundproofing thinking that it will do a lot more than it can do with limited budgets. I had this fantasy that I could be playing a movie "loudly" in the theater and somebody just outside the door wouldn't be able to hear it at all. That's "soundproof" to me. But let's think of what that means. A "loud" movie is going to be somewhere around 85dB or more, but let's stick with 85dB to not make the job even harder than it is. "Inaudible" is highly context sensitive to the local environment since it's going to be a sound level that is below ambient level. Nevertheless, I've notice that a recognizable sound (not white noise) will still be audible even if it's at the ambient noise level, since you will pick out those frequencies. So if ambient is 30dB, then we're really shooting or 20dB to be coming out of the theater.

85dB to 20dB is a 65dB loss. That is doable (barely) from a wall perspective with double walls and double or triple drywall on BOTH sides. You can't get there if you're only treating the theater side. You can buy doors with STC 65, but now we're well into the thousands of dollars. I'm not sure how you'd DIY a door like that.

And after all that, you still haven't addressed LFE or bass. STC only measures higher frequencies and cuts off completely at 125Hz. I've seen firsthand how unimpeded LFE is as it rampages through your best soundproofing efforts.

One of these days I'm going to write up a "cautionary note" in the first couple of posts in this thread just to level-set expectations. With a reasonable budget and space you can certainly make a very notable impact on sound intrusion and loss but it will not be an awe-inspiring amount.


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## ScottOsb

granroth said:


> Oh, okay! Just so I have the full picture; the drywall is screwed to the hat channel and the rubber is screwed to the stud -- how is the hat channel attached to the rubber?


I ran screws through the hat channel into the stud with the rubber under it. The screws have rubber washers on them, ie. roofing screws for metal roofs. So the hat channel is sandwiched between the rubber washers and the rubber on the studs. Seems to work OK so far.


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## granroth

ScottOsb said:


> I ran screws through the hat channel into the stud with the rubber under it. The screws have rubber washers on them, ie. roofing screws for metal roofs. So the hat channel is sandwiched between the rubber washers and the rubber on the studs. Seems to work OK so far.


Now THAT's interesting! There's a possibility of a short-circuit where the head of the screw securing the hat channel touches the back of the drywall... but I wonder how much that'd matter.

This seems like an ingenious DIY attempt to create a less expensive decoupling solution.

That said, I can't say that I'd ever recommend this procedure (even though it sounds potentially slick) due to the lack of rigorous testing. The devil is in the details when it comes to soundproofing solutions and for every step done right, there are a billion possible ways to do that step wrong. Your solution could be just as effective as much more expensive solutions, but without testing you'd never know.

Still, nice job thinking outside the box


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## ScottOsb

granroth said:


> Now THAT's interesting! There's a possibility of a short-circuit where the head of the screw securing the hat channel touches the back of the drywall... but I wonder how much that'd matter.
> 
> This seems like an ingenious DIY attempt to create a less expensive decoupling solution.
> 
> That said, I can't say that I'd ever recommend this procedure (even though it sounds potentially slick) due to the lack of rigorous testing. The devil is in the details when it comes to soundproofing solutions and for every step done right, there are a billion possible ways to do that step wrong. Your solution could be just as effective as much more expensive solutions, but without testing you'd never know.
> 
> Still, nice job thinking outside the box


The screws are on the two legs of the hat channel so the drywall won't touch them. If it's not perfect, I'm in the middle of 5 acres in Wyoming, I can't imagine the neighbors complaining too much


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## mtbdudex

pitviper33 said:


> Anybody know what happened to the soundproofing company (www.soundproofingcompany.com)? Their site appears to be down.





granroth said:


> It's up right now: http://www.isitdownrightnow.com/soundproofingcompany.com.html


[edit - my order placed with http://www.tmsoundproofing.com/door-soundproofing.html , not Ted Whites company, as his product only goes to 36" wide door and I've got 48" wide door]
Hmmmm, I placed my order on 1/15/2015 for door perimiter seals and auto bottom seal.
I've had emails with "Rachel" then "Toby", and 2 promises they'd ship end of week 1/30 then 2/6, and still not shipped.

>>Be careful when placing your order here, http://www.tmsoundproofing.com/door-soundproofing.html , ask about their delivery lead times, I'm giving them 1 more week before I cancel and call VISA to make sure refund is there.


----------



## granroth

mtbdudex said:


> [edit - my order placed with http://www.tmsoundproofing.com/door-soundproofing.html , not Ted Whites company, as his product only goes to 36" wide door and I've got 48" wide door]
> Hmmmm, I placed my order on 1/15/2015 for door perimiter seals and auto bottom seal.
> I've had emails with "Rachel" then "Toby", and 2 promises they'd ship end of week 1/30 then 2/6, and still not shipped.
> 
> >>Be careful when placing your order here, http://www.tmsoundproofing.com/door-soundproofing.html , ask about their delivery lead times, I'm giving them 1 more week before I cancel and call VISA to make sure refund is there.


Hrm. When I made my order last year, it definitely took a bit, but it was coming directly from the factory, so they didn't have control over that. Did take them 4 days to tell me that their "quick ship" item wasn't in stock at all.


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## LeBon

granroth said:


> Hrm. When I made my order last year, it definitely took a bit, but it was coming directly from the factory, so they didn't have control over that. Did take them 4 days to tell me that their "quick ship" item wasn't in stock at all.


My drop seal and jamb seals, purchased from Ted White's company, were drop-shipped from Zero International. But they arrived as promised.


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## mtbdudex

I'll look into zero to see if they have for 48" door, I'm guessing yes.

[edit]
My seals are shipping Monday with delivery by Wednesday! So weekend of Feb-21st I'm installing them.

btw; for those that order solid core doors and want to give their door side hinges a little more screw depth for max strength:
(from my HT build thread)
Added longer screws to the door side hinges also







.









Factory door side screw length .. .. .. .. .. .. .. .. . I wanted same pitch and fully threaded....these not work







.







.
Had these in my stock from other project







.







.









I found # 8 x 1" black sheet metal screw is exactly same pitch and inner/outer dia as the hinge screw, so I used those.
Now the door side hinges grab 33% stronger, I'm not worried at all about failure there.










Via Mikes brain/thumb interface, LLAP


----------



## thetman

I have a question I hope someone has some knowledge of. of course budget is an issue so basically I am looking at two options. what would be better for soundproofing. 2 layers of 1/2 inch or one layer of 5/8. I know the one layer would be cheaper to install but not sure if there will be a big difference between the two options. I am more concerned about keeping outside sounds from entering than than having the movie room sounds enter into the rest of the house. Also the walls will be plastered-not sure it makes a difference or not.


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## Brian Fineberg

Question. How far down do clips and channel come from the floor joists above? I have a few pipes that stick out from flush from the above floor joists. I am wondering if they need to be moved or if the clips/channels will be enough clrarance. Thanks!


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## granroth

thetman said:


> I have a question I hope someone has some knowledge of. of course budget is an issue so basically I am looking at two options. what would be better for soundproofing. 2 layers of 1/2 inch or one layer of 5/8. I know the one layer would be cheaper to install but not sure if there will be a big difference between the two options. I am more concerned about keeping outside sounds from entering than than having the movie room sounds enter into the rest of the house. Also the walls will be plastered-not sure it makes a difference or not.


This isn't something that needs to be guessed at, since there has been extensive research on quite a few wall types. It can be found in this PDF: http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir761/ir761.pdf

There are quite a few other variables other than how thick the drywall is and how many layers. If you have a single wall made of 2x4 (90mm) wood studs that are spaced 16" O.C (406mm) and you're using mineral fiber insulation, then you can compare these two:

G16_WS90(406)_MFB90_G16 (TL-93-157) = STC 34
G13_WS90(406)_MFB90_2G13 (TL-93-167) = STC 35

The top is 1 layer of 5/8" drywall (G16) + wood studs 16" O.C (WS90(406)) + mineral fiber insulation (MFB90) + 1 layer of 5/8" drywall (G16)

The bottom is 1 layer of 1/2" drywall (G13) + wood studs 16" O.C (WS90(406)) + mineral fiber insulation (MFB90) + 2 layer of 1/2" drywall (2G13)

The difference is 1 STC, which is likely not noticeable.

Look at some of the other configurations, though. If you're willing to give up a little space, then for very little amount of money, you can have staggered studs or double walls, both of which will give HUGE gains.

Really, your best bet is to decide what kind of sound attenuation you want, then search for that in IR-761. Calculate how much it would cost to build that. If too much, then re-adjust your expectations and re-search. Keep doing that until you find the maximum sound attenuation for your budget.

(Note, if you aren't metric proficient, then: 13mm = 1/2", 16mm = 5/8", 90mm = 3-1/2", 406mm = 16", 610mm = 24")


----------



## thetman

granroth said:


> This isn't something that needs to be guessed at, since there has been extensive research on quite a few wall types. It can be found in this PDF: http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir761/ir761.pdf
> 
> There are quite a few other variables other than how thick the drywall is and how many layers. If you have a single wall made of 2x4 (90mm) wood studs that are spaced 16" O.C (406mm) and you're using mineral fiber insulation, then you can compare these two:
> 
> G16_WS90(406)_MFB90_G16 (TL-93-157) = STC 34
> G13_WS90(406)_MFB90_2G13 (TL-93-167) = STC 35
> 
> The top is 1 layer of 5/8" drywall (G16) + wood studs 16" O.C (WS90(406)) + mineral fiber insulation (MFB90) + 1 layer of 5/8" drywall (G16)
> 
> The bottom is 1 layer of 1/2" drywall (G13) + wood studs 16" O.C (WS90(406)) + mineral fiber insulation (MFB90) + 2 layer of 1/2" drywall (2G13)
> 
> The difference is 1 STC, which is likely not noticeable.
> 
> Look at some of the other configurations, though. If you're willing to give up a little space, then for very little amount of money, you can have staggered studs or double walls, both of which will give HUGE gains.
> 
> Really, your best bet is to decide what kind of sound attenuation you want, then search for that in IR-761. Calculate how much it would cost to build that. If too much, then re-adjust your expectations and re-search. Keep doing that until you find the maximum sound attenuation for your budget.
> 
> (Note, if you aren't metric proficient, then: 13mm = 1/2", 16mm = 5/8", 90mm = 3-1/2", 406mm = 16", 610mm = 24")


thanks for this, lots of info on this to digest. Unfortunately I've already lost some room width due to a redesign on the floor plan ( its a whole addition plus house reno). If it was just one room then no problem but the budget is spread thin throughout the project. But the walls are 2x6 and insulated. I know I can't due a complete over the top soundproofing job- but just trying to do a bit more than the norm. I will be getting estimates later next week not the board installation-so I'll take it from there and maybe I can at least double up and have 2 layers of 5/8. we'll see. So many spots to soundproof though as everyone knows. outlets, doorways. heating ducts, recessed lights- the list goes on.


----------



## checkbit

Need advice from experienced members on this one. Ive searched the forum and internet for some thoughts on my type of situation to no avail.

Im finishing a room above an unattached garage to be used as general purpose/media room. I like to listen to movies and music at high volume. My issue is this: All walls are exterior walls and there are 4 windows in the room. The insulation is open cell spray foam. Im ready for drywall. My goal is to limit the amount of sound that I expose the neighbors to, I know I have many options here (resilient channel, multiple layers of drywall etc.), but I have narrowed it down to 2 options (I won't go into my reasoning to keep the post shorter), spend the money on Soundbreak XP drywall or just say screw it and just use 5/8" type X drywall. My thought is that the soundbreakXP would probably be of minimal value because of the windows. 

What do you guys think?


----------



## BasementBob

"Gold Bond® BRAND 5/8" *SoundBreak® XP®* Gypsum Board with Sporgard™* has an acoustically enhanced, high density fire resistant Type X gypsum core encased in a heavy, abrasion and mold/mildew/moisture resistant, 100% recycled, National Gypsum PURPLE® paper on both sides. Used in the construction of high rated STC wall assemblies, this 5/8" thick gypsum board consists of *a layer of viscoelastic damping polymer sandwiched* between two pieces of high density mold resistant gypsum board , providing constrained layer damping."
-- http://www.nationalgypsum.com/products/Product.aspx?ProductID=2353


----------



## checkbit

BasementBob said:


> "Gold Bond® BRAND 5/8" *SoundBreak® XP®* Gypsum Board with Sporgard™* has an acoustically enhanced, high density fire resistant Type X gypsum core encased in a heavy, abrasion and mold/mildew/moisture resistant, 100% recycled, National Gypsum PURPLE® paper on both sides. Used in the construction of high rated STC wall assemblies, this 5/8" thick gypsum board consists of *a layer of viscoelastic damping polymer sandwiched* between two pieces of high density mold resistant gypsum board , providing constrained layer damping."
> -- http://www.nationalgypsum.com/products/Product.aspx?ProductID=2353


Thanks for the reply BasementBob. I am familiar with the product and know what it does. My quandry is determining whether my room, having 4 windows, will negate the sound dampening effect of the more expensive SoundBreakXP drywall. SoundBreak is $80 a board and regular type X is about $10 a board.


----------



## LeBon

checkbit said:


> ...My quandry is determining whether my room, having 4 windows, will negate the sound dampening effect of the more expensive SoundBreakXP drywall. SoundBreak is $80 a board and regular type X is about $10 a board.


The short answer is "Yes". You need to plug (or remove) the windows, and treat all 6 surfaces of the room. IMHO, SoundBreak is not cost-effective, compared to 2 layers of 5/8 Type X with clips, channel and Green Glue.


----------



## Brian Fineberg

LeBon said:


> The short answer is "Yes". You need to plug (or remove) the windows, and treat all 6 surfaces of the room. IMHO, SoundBreak is not cost-effective, compared to 2 layers of 5/8 Type X with clips, channel and Green Glue.


Can you just build the wall (1" off) and dd/gg over it?


----------



## granroth

checkbit said:


> Need advice from experienced members on this one. Ive searched the forum and internet for some thoughts on my type of situation to no avail.
> 
> Im finishing a room above an unattached garage to be used as general purpose/media room. I like to listen to movies and music at high volume. My issue is this: All walls are exterior walls and there are 4 windows in the room. The insulation is open cell spray foam. Im ready for drywall. My goal is to limit the amount of sound that I expose the neighbors to, I know I have many options here (resilient channel, multiple layers of drywall etc.), but I have narrowed it down to 2 options (I won't go into my reasoning to keep the post shorter), spend the money on Soundbreak XP drywall or just say screw it and just use 5/8" type X drywall. My thought is that the soundbreakXP would probably be of minimal value because of the windows.
> 
> What do you guys think?


Since Soundbreak XP is roughly 8x the cost of a normal sheet of 5/8" Type X, then I assume that budget isn't the concern as much as space is. That is, you cannot afford to give up the 1-1/4" from dual layers of the normal stuff.

Let's start from the top, though. Two layers of 5/8" Type X drywall with Green Glue in between would absolutely work better than one layer of Soundbreak XP (or QuietRock or equivalent) at less than half the cost. You would lose 1-1/4" of space.

One layer of Soundbreak XP or QuietRock would work better than one layer of normal 5/8" Type X. Rough guestimate is STC ~50 for the specialized solution vs STC ~40 for the normal one. That is a noticeable difference. Is that (roughly) 10 dB worth 8x the cost? Could be, depending on your constraints.

Now on to the windows. Whenever you build a soundproof shell, you theoretically start with the assumption that your shell has the same sound attenuation capabilities. If you know that your walls and ceiling are STC 50, then you start there. Every intrusion into that shell will lower the effectiveness by some amount that is somewhere in between the capabilities. If you have four windows at STC 27 (average for dual pane windows), then your room's effectiveness is going to be somewhere between STC 27 and 50 -- which one it's closer to depends on a lot of factors, but one big one is the total square footage of each solution.

What this does mean, though, is that if you leave the windows as-is, then your overall rating for the room is going to be lower for "normal" drywall than for specialized drywall... but those windows did take a huge chunk out of the advantage of paying mega-bucks for specialized drywall. It might not be worth the cost anymore, if it was before.

BUT!!! Don't leave the windows as-is! The way to combat this problem is to identify your weak points (windows and doors, mostly) and increase their sound attenuation until it matches the rest of the room. You do this by matching the same mass as the wall (and hopefully damping and decoupling, but that's not always possible). In the case of your windows, create four window plugs that have equivalent mass as the rest of the walls and make sure you insert the plugs whenever you listen to anything loud. In that case, you'll have your STC 50 (or better) everywhere and you maintain the capability of the wall.

There are links to several window plugs in the second link in this thread.


----------



## checkbit

Granroth, exactly the information I was looking for! Thanks!


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## cw5billwade

check my build thread for my window plugs. Also remember you will need to treat the floor since currently you only have 1 sheet of 3/4" T&G. I did another layer of 3/4" T&G with Green Glue. The savings from doing to sheets of 5/8" fire rated DW with Green Glue on walls and ceiling will more than pay for an additional layer or 2 of 3/4" T&G on the floor and clips and channel. If spending the money do it right once and done. Even though you have spray foam yo will still want to put R19 above the ceiling of the garage and the media rooms for added density.


----------



## ch1sox

Brian Fineberg said:


> Question. How far down do clips and channel come from the floor joists above? I have a few pipes that stick out from flush from the above floor joists. I am wondering if they need to be moved or if the clips/channels will be enough clrarance. Thanks!


Depends on which clips you're using. I believe some are as small as 1 1/8" or as much as 1 5/8". Some clips even have extension clips to drop them about 4 inches. They cost a little more though.


----------



## granroth

ch1sox said:


> Depends on which clips you're using. I believe some are as small as 1 1/8" or as much as 1 5/8". Some clips even have extension clips to drop them about 4 inches. They cost a little more though.


Ah, missed the original question for this.

Yeah, normally people are asking how to minimize the clearance of the clips and not expand them!  The answer is in the 1/8" to 1/4" range, btw.

For maximized clearance, then 1-5/8" is the typical size of Whisper Clips. If more clearance is needed, then I suggest just adding blocking to achieve the correct height -- far cheaper than any extension clip.


----------



## Brian Fineberg

Sorry. Is there a guide to adding blocking. I'm thinking I MAY need to do this. Unless I can move up the drain pipe in the picture:


----------



## DefelRadar

I'm currently in the design phase of my basement HT and I want to make sure I have some assumptions correct. 
My HT room is 11'9" W x 20' 8" L x 9' H

I am slightly concerned about the width of the room.

3 of the walls are foundation/concrete walls. For the concrete walls I was planning on building a metal stud with the following specs:

Air Gap + Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness 
1 + 1.625 + 0.59375 + 0.625 = 3.84375 
I don't know if 2.5" fiberglass insulation is available or if Rigid foam would help at all for the wall. Anyone have an idea?
connect to ceiling joists with IB-3 brackets 

My next question involves the 4th wall which 6' 7" of the existing wall is shared by the laundry room. 
The other 14' of the wall does not exist yet and would be a new build.

I had two thoughts on this either do the Laundry wall with IB-1 clips

Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness 
1.3125 + 0.59375 + 0.625 = 2.53125 
Insulate with fiberglass R15 connect to ceiling joists with IB-3 brackets 

or do the Laundry wall with a Staggered Stud configuration.

Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness 
1 + 0.59375 + 0.625 = 2.21875 
Insulate with fiberglass R15 connect to ceiling joists with IB-3 brackets 

The last 14' or so if that wall would need to be built but I guess I could offset the 14' wall slightly so it wouldn't have to match up perfectly with the current laundry room wall. This would help where the room narrows to 10' 4" (if the wall was straight across)

Lastly the ceiling would be decoupled with IB-1 clips or by some form of blocking and IB-1 clips to lower the ceiling slightly to get under some piping.
I've attached a drawing to help illustrate my thoughts.

Thanks for everyone's help and advice!


----------



## granroth

Brian Fineberg said:


> Sorry. Is there a guide to adding blocking. I'm thinking I MAY need to do this. Unless I can move up the drain pipe in the picture:


The best guides will be ones related to applying strapping to a ceiling to level it for drywall. There's a lot of them. The concept is identical. You'd essentially be attaching some kind of 2-by material (depending on how far down you need to go) perpendicularly to your joists and then attaching the clips to those strips.

Another option is a stylistic one -- maybe consider creating a coffered ceiling and just hiding the drain pipe in one of the coffer ridges. You're likely going to be putting a soffit around the ductwork, right? Presumably another one on the other side to balance it out? A coffered ceiling between them would look slick.


----------



## granroth

DefelRadar said:


> I'm currently in the design phase of my basement HT and I want to make sure I have some assumptions correct.
> My HT room is 11'9" W x 20' 8" L x 9' H
> 
> I am slightly concerned about the width of the room.
> 
> 3 of the walls are foundation/concrete walls. For the concrete walls I was planning on building a metal stud with the following specs:
> 
> Air Gap + Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness
> 1 + 1.625 + 0.59375 + 0.625 = 3.84375
> I don't know if 2.5" fiberglass insulation is available or if Rigid foam would help at all for the wall. Anyone have an idea?


If you are suggesting the rigid foam for insulation purposes (it is a foundation wall after all), then yes, that's a great way to get a decent amount of insulation in a small amount of space. It does a terrible job of soundproofing, though, and isn't at all a replacement for fluffy fiberglass or similar from an absorption point of view.

I'm assuming that "skinny" fiberglass is available, since the existing fiberglass insulation in my (block) house is roughly 2" thick. It had to come from somewhere 



DefelRadar said:


> connect to ceiling joists with IB-3 brackets
> 
> My next question involves the 4th wall which 6' 7" of the existing wall is shared by the laundry room.
> The other 14' of the wall does not exist yet and would be a new build.
> 
> I had two thoughts on this either do the Laundry wall with IB-1 clips
> 
> Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness
> 1.3125 + 0.59375 + 0.625 = 2.53125
> Insulate with fiberglass R15 connect to ceiling joists with IB-3 brackets
> 
> or do the Laundry wall with a Staggered Stud configuration.
> 
> Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness
> 1 + 0.59375 + 0.625 = 2.21875
> Insulate with fiberglass R15 connect to ceiling joists with IB-3 brackets
> 
> The last 14' or so if that wall would need to be built but I guess I could offset the 14' wall slightly so it wouldn't have to match up perfectly with the current laundry room wall. This would help where the room narrows to 10' 4" (if the wall was straight across)
> 
> Lastly the ceiling would be decoupled with IB-1 clips or by some form of blocking and IB-1 clips to lower the ceiling slightly to get under some piping.
> I've attached a drawing to help illustrate my thoughts.
> 
> Thanks for everyone's help and advice!


As far as staggered studs vs clips go -- the clips may give a slightly better result than staggered studs, but if space is that much of an issue and you think you can gain some space that way, then it likely won't be enough to be worth it.


----------



## Brian Fineberg

granroth said:


> The best guides will be ones related to applying strapping to a ceiling to level it for drywall. There's a lot of them. The concept is identical. You'd essentially be attaching some kind of 2-by material (depending on how far down you need to go) perpendicularly to your joists and then attaching the clips to those strips.
> 
> Another option is a stylistic one -- maybe consider creating a coffered ceiling and just hiding the drain pipe in one of the coffer ridges. You're likely going to be putting a soffit around the ductwork, right? Presumably another one on the other side to balance it out? A coffered ceiling between them would look slick.


Awesome. Thanks for the suggestion. To answer your question. Yep. I'll be putting a soffit around that duct work (don't need to replace it with flexi duct?) and a maching one in the opposite side and the front and back

Coffered isn't a bad ide. We shall see

He blocking method sounds like a simpler (and cheaper) plan though


----------



## cw5billwade

Brian I would do a double wall back at the laundry room. I know it takes more space but do you really want to hear the washer spining in the middle of a movie? DW/GG/OSB/2x4/1"air gap/2x4/DW/DW both areas of 2x4 wall has R15 in them. That is what I did on my rear wall.


----------



## Brian Fineberg

granroth said:


> The best guides will be ones related to applying strapping to a ceiling to level it for drywall. There's a lot of them. The concept is identical. You'd essentially be attaching some kind of 2-by material (depending on how far down you need to go) perpendicularly to your joists and then attaching the clips to those strips.
> 
> Another option is a stylistic one -- maybe consider creating a coffered ceiling and just hiding the drain pipe in one of the coffer ridges. You're likely going to be putting a soffit around the ductwork, right? Presumably another one on the other side to balance it out? A coffered ceiling between them would look slick.





cw5billwade said:


> Brian I would do a double wall back at the laundry room. I know it takes more space but do you really want to hear the washer spining in the middle of a movie? DW/GG/OSB/2x4/1"air gap/2x4/DW/DW both areas of 2x4 wall has R15 in them. That is what I did on my rear wall.


Are you talking to me? My laundry room is on the floor above


----------



## cw5billwade

My Bad got you mixed up @DefelRadar


----------



## cw5billwade

DefelRadar said:


> I'm currently in the design phase of my basement HT and I want to make sure I have some assumptions correct.
> My HT room is 11'9" W x 20' 8" L x 9' H
> 
> I am slightly concerned about the width of the room.
> 
> 3 of the walls are foundation/concrete walls. For the concrete walls I was planning on building a metal stud with the following specs:
> 
> Air Gap + Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness
> 1 + 1.625 + 0.59375 + 0.625 = 3.84375
> I don't know if 2.5" fiberglass insulation is available or if Rigid foam would help at all for the wall. Anyone have an idea?
> connect to ceiling joists with IB-3 brackets
> 
> My next question involves the 4th wall which 6' 7" of the existing wall is shared by the laundry room.
> The other 14' of the wall does not exist yet and would be a new build.
> 
> I had two thoughts on this either do the Laundry wall with IB-1 clips
> 
> Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness
> 1.3125 + 0.59375 + 0.625 = 2.53125
> Insulate with fiberglass R15 connect to ceiling joists with IB-3 brackets
> 
> or do the Laundry wall with a Staggered Stud configuration.
> 
> Stud + 1st layer OSB + 2nd layer Drywall = Total Thickness
> 1 + 0.59375 + 0.625 = 2.21875
> Insulate with fiberglass R15 connect to ceiling joists with IB-3 brackets
> 
> The last 14' or so if that wall would need to be built but I guess I could offset the 14' wall slightly so it wouldn't have to match up perfectly with the current laundry room wall. This would help where the room narrows to 10' 4" (if the wall was straight across)
> 
> Lastly the ceiling would be decoupled with IB-1 clips or by some form of blocking and IB-1 clips to lower the ceiling slightly to get under some piping.
> I've attached a drawing to help illustrate my thoughts.
> 
> Thanks for everyone's help and advice!


 I would do a double wall back at the laundry room. I know it takes more space but do you really want to hear the washer spining in the middle of a movie? DW/GG/OSB/2x4/1"air gap/2x4/DW/DW both areas of 2x4 wall has R15 in them. That is what I did on my rear wall.


----------



## Brian Fineberg

Brian Fineberg said:


> Sorry. Is there a guide to adding blocking. I'm thinking I MAY need to do this. Unless I can move up the drain pipe in the picture:


How do I go about that hvac duct?

For the screen wall which goes perpendicuL to what you see and in front of the hvac and water heater do I just frame around the ductwork. And dd/gg the ceiling and walls but not the ductworks? Then build a dd/gg soffit around the ductwork sales with caulking?

Trying to wrap my head around this. 

Thanks


----------



## mikepos

Hey guys, I don't want to be a nerd or a killjoy but regarding insulation on the basement concrete walls keep in mind that 9.36. (energy efficiency) of the building code of Canada requires a minimum R-value, off the top of my head R-22 depending on the climate zone you're in, which translates to a slightly thicker 2x6 batt or rigid insulation of varied thickness depending on type (extruded is better, the fibrey one not the bead board).


----------



## granroth

Brian Fineberg said:


> How do I go about that hvac duct?
> 
> For the screen wall which goes perpendicuL to what you see and in front of the hvac and water heater do I just frame around the ductwork. And dd/gg the ceiling and walls but not the ductworks? Then build a dd/gg soffit around the ductwork sales with caulking?


There is an area where there's more than one "right" answer, so it's hard to give a specific recommendation. In general, you'll want to seal off the ductwork due to the amount of noise that'll bring the theater. That implies that there'll be a sealed dd/gg soffit around it.

Now, one way to do that is to fully seal off the room, including the ceiling above the ducts and the wall behind it and then build the soffit inside of the soundproofed shell. That would, indeed, do a better job of overall soundproofing, from the perspective of sound coming in and out of the room. It's notably tricker to do when you have tight clearances, though.

Another option is to frame out the soffit around the ducts to be part of the room framing itself. You then wrap the dd/gg with clips around the entire thing and the soffit becomes an integral part of your wall and ceiling. You essentially will no longer have a rectangular room. That will give you the same sound attenuation from the ducts, but will be mildly less effective for inside/outside sound movement.

On a related note, most screen walls assume an acoustically transparent screen with speakers behind them. Is that what you were thinking? If so, I wonder if that furnace and water heater might be overly intrusive while watching a movie...


----------



## granroth

mikepos said:


> Hey guys, I don't want to be a nerd or a killjoy but regarding insulation on the basement concrete walls keep in mind that 9.36. (energy efficiency) of the building code of Canada requires a minimum R-value, off the top of my head R-22 depending on the climate zone you're in, which translates to a slightly thicker 2x6 batt or rigid insulation of varied thickness depending on type (extruded is better, the fibrey one not the bead board).


Not a killjoy at all! The standard recommendation for building a theater is to get the proper permits for it and get it inspected, from a safety, resale, and insurability point of view. In the U.S., insulation requirements are done at the local code enforcement level, which may be as local as a city or may be a county. Sometimes states have codes.

For example, AZ (my state) does not follow any energy codes and leaves it to the LCE. In my case, that's the city, which does require minimum insulation for all new construction (R-13 for walls, nothing for basements if you have one). In MA, by way of contrast, the code requirements come at the state level and you need to follow the 2012 variant. That means R-20 for walls and R-15 to R-19 for basements (depending on factors).

There's also possible requirements for slab insulation and then there's always the omnipresent vapor barrier requirements... and it goes on and on.

We tend to gloss over code requirements in this thread if only because they do vary so much and the assumption is that you'll cover that with your building inspector.


----------



## Brian Fineberg

granroth said:


> There is an area where there's more than one "right" answer, so it's hard to give a specific recommendation. In general, you'll want to seal off the ductwork due to the amount of noise that'll bring the theater. That implies that there'll be a sealed dd/gg soffit around it.
> 
> Now, one way to do that is to fully seal off the room, including the ceiling above the ducts and the wall behind it and then build the soffit inside of the soundproofed shell. That would, indeed, do a better job of overall soundproofing, from the perspective of sound coming in and out of the room. It's notably tricker to do when you have tight clearances, though.
> 
> Another option is to frame out the soffit around the ducts to be part of the room framing itself. You then wrap the dd/gg with clips around the entire thing and the soffit becomes an integral part of your wall and ceiling. You essentially will no longer have a rectangular room. That will give you the same sound attenuation from the ducts, but will be mildly less effective for inside/outside sound movement.
> 
> On a related note, most screen walls assume an acoustically transparent screen with speakers behind them. Is that what you were thinking? If so, I wonder if that furnace and water heater might be overly intrusive while watching a movie...


Thanks for the reply. To answer your question the "end" of te room will not have the water heater etc in it. Thy will be behind the shell. The actual screen wall (false at wall) will be 2' in front of the shell wal. Sorry for the confusion on that. 

I don't inderstand what you mean about the room not being rectangular. Won't that be the same no matter how I frame or drywall the soffit?

I guess I will do like you said and frame the soffit as part of the walls (dd/gg)

Thank you!


Edit: where are you located?


----------



## granroth

Brian Fineberg said:


> I don't inderstand what you mean about the room not being rectangular. Won't that be the same no matter how I frame or drywall the soffit?


Er.. yeah, I wasn't making sense at all there. I meant that if you soundproofed the walls, then your soundproof shell would have three sides (not counting the floor) but if you wrapped the duct, then it would have five sides (still not counting the floor). Here's two quick mockups -- the red part is the dd/gg "shell" in each:



















Visually the two rooms would look identical. You'd still put dd/gg on the upper mockeup (the green part), but the soffit is technically in the room's shell already so what that's doing is just blocking the HVAC duct noise and not the whole of the exterior noise.



> Edit: where are you located?


Gilbert AZ, close to downtown. Are you in AZ?


----------



## Brian Fineberg

Ahh that's what I thought. Really no difference between the two. Just logistics. Thanks for pics!

No im in RI. I saw you posted code for MA so I thought maybe you were local to me


----------



## Brian Fineberg

Brian Fineberg said:


> Sorry. Is there a guide to adding blocking. I'm thinking I MAY need to do this. Unless I can move up the drain pipe in the picture:


Ok another question. Currently the "supply" to the area I will be building is simply a vent cut into the hvac line if you look closely it's the white vent on the top left. How do I go about sound proofing that? Do I cover it up then build another soundproofed supply by cutting into the hvac

I have no clue about hvac stuff so all the help I can get is appreciated


----------



## granroth

Brian Fineberg said:


> Ok another question. Currently the "supply" to the area I will be building is simply a vent cut into the hvac line if you look closely it's the white vent on the top left. How do I go about sound proofing that? Do I cover it up then build another soundproofed supply by cutting into the hvac
> 
> I have no clue about hvac stuff so all the help I can get is appreciated


Oof.. that can get complicated. One option is to determine how satisfied you are with the current setup from a comfort point of view as well as a noise point of view. If both are fine, you might consider just leaving it mostly as-is. I would only do that if you are putting the shell behind the ductwork, though, as this would be punching a hole through it.

If it's not cutting it from either a comfort or noise perspective, then you will want to branch off from the main duct and develop a custom solution. By coincidence, I actually started a thread some months ago talking about various HVAC aspects that are relevant to this discussion: Theater HVAC - Dead Vents vs Zones vs Mini Splits

If there's one takeaway from that, it's that you should separate the "comfort" part of HVAC with the "noise" part. Almost nothing is out of bounds for a dedicated DIYer, but HVAC has so many variables that it can come close. Your best bet is to dictate your comfort requirements to an HVAC contractor and have them do all that work and then handle the noise element yourself.

TL;DR - you'll want to get the air speed below 300 linear feet per minute at every grille, by increasing the cross-section surface area of the duct work.


----------



## Brian Fineberg

So I could essentially use that supply vent (to regulate temp) Then build a dead vent return to an adjacent room? I could always extend that vent into the adjacent floor joist cavity and sound proof it along the way and have it exhaust on the ceiling of the Ht

Does that sound like it could work?


----------



## Brian Fineberg

My major issue is currently he basment is freezing in be winter. (In not too worried about heat in the summer the basement stays cool)

So a dead vent doesn't help with the warming issues

How about a muffler for inside a joist? For the supply?

Somthing like this
http://www.avsforum.com/forum/19-dedicated-theater-design-construction/1533361-hidden-bethesda-family-theater-2.html

My question. Is how do I cover the current hole for the vent there now and create a new hole for the flex duct to go into the joist cavity?


----------



## mtbdudex

panino said:


> The entrance to my theater will be french doors. I know what you are all going to say.. "get rid of the french doors and go with a single door". Already thought about it and I'm intent on making the french doors work. The question I have is, does anyone have a recommendation on a set of door seals and automatic door bottoms that I should go with? I've looked through Zero International's site and there are so many to choose from.
> 
> I'm planning on sealing the point where both doors meet with an astragal and seal, adhesive seal around the frames, and automatic door bottoms on both doors. The doors are only 1 3/8" thick, but are solid core. I'll probably completely mortise the door bottoms into the doors, so I'll need a set that is rather thin. I need recommendations on which seals and door bottoms to use for this.


panino - how did you tackle your french doors?
My brother inlaw has them, just your basic interior french doors not solid core, and was thinking to upgrade his for more effective soundproofing.


----------



## mtbdudex

*kmhvball
*How did this turn out for you?

Seems like instead of can lights for middle ceiling lighting this should be the direction, for those that want easier soundproofing than backer boxes.



kmhvball said:


> Well, I last night I made my 12 'backer boxes', which maybe I would call more of a 'Backer Sandwich", it took about an hour in total... This relates back to Post 427/29 (&448)
> 
> I ended up with this configuration:
> 3/4" MDF Solid with Green Glue
> 5/8" Drywall Solid w Green Glue
> 3/8" Drywall w/ Hole w Green Glue
> 3/8" Dyrwall w/ Hole
> 
> I used this based on the concern expressed about Fire hazard, figuring the fire-rated drywall would be the way to go - and frankly, much easier to 'cut' that as well, so, doing it again - I probably would do two layers of the 5/8" solid Drywall.
> 
> Then with the two ceiling layers of 5/8" drywall, the box depth will match my ceiling depth with my 'backer' boxes.
> 
> Here are the parts in there individual piece forms...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here are the parts with Green Glue applied... "Learning", I applied the GG to the 'fronts', defined as the part on the Theater side vs the 'ceiling/subfloor' side of the MDF, 5/8" Drywall, and the 3/8" Drywall... This meant when I did the 5/8" drywall 'all over', the 3/8" light box 'hole' had GG all over. So, to do it again, I would put the GG on the 'theater side' of the two 3/8" drywall layers, and the theater side of the 5/8" drywall layer..
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here is what the 'final' product looks like. These will be installed onto the subfloor side of the drywall in the correct locations before the Drywall is lifted into place. The circle at the top is the Surface Mount LED light.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> We'll see how this all works out.


----------



## kmhvball

My theater room is still Work in Progress... so, don't know for sure how they'll work out yet.

My original plan, i.e., the comment above the last photo was:
"These will be installed onto the subfloor side of the drywall in the correct locations before the Drywall is lifted into place. "

Instead, I mounted them to joists with IB-3 clips, and then drywallwers cut them out like a normal light. They didn't do this particularly well, so, I am a bit concerned the flat part of the backer box won't be lying flat against the drywall. Net, if I were to do it again, I would definitely mount them before lifting the drywall up, which would ensure they are flush. I would probably even put green glue on the front face of the backer sandwich.

If I ever do another theater and can't put these types of lights in soffits 'inside the shell', I would do this again vs building full backer boxes. Building these with each layer being drywall (vs any MDF), is a very fast to make and doesn't require much precision.

I still have to put acoustic caulk around the boxes themselves and in the electric wire hole penetration.

Another thought... 
There are several versions of these "Surface Mount" LED lights, and I would look at what kind of dimmers they are compatible with before choosing the light itself. I used these same lights through-out my basement, and also bought those "Adorne" light switches/ dimmers (the version advertised as CFL/LED compatible). It so happens those dimmers aren't compatible with these particular LED lights I chose, so, I might only be dimming down to 60-70% of light output vs the advertised light floor of something like 10%. This now has me concerned about my theater lighting plan - I thought of using Grafik Eye, and now not sure that is compatible with these lights. Also, other popular options - Vizia RF+, Maestro, etc., don't seem to be compatible either. So, my 'mistake' in my opinion - was buying a light with limited compatibility with dimmers. I THINK (although haven't looked much at them) the Cree version of these are compatible with a much broader range of dimmers. 

I'll take a picture of how they look in the ceiling as of now (light not installed) and a picture of my basement/installed one's and post, hopefully tomorrow.


----------



## mtbdudex

^^ Thx for feedback Kevin. I did my HT in 2007 before I learned about the fine details of soundproofing, my cans overhead do leak spl's ....

I'm thinking in late 2016 how to re-do the overhead lighting to improve soundproofing in the center ceiling area w/o a total teardown, what you did I might be able to use as a retrofit...


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## kmhvball

This thread http://www.avsforum.com/forum/19-de...n-construction/1517771-recessed-lighting.html was started by Ted White, and he was thinking that using this type of light, with as little as Putty Pads might be effective. I don't know if anyone has executed it that way or not, but using those would be even less invasive than what I did to an existing ceiling structure. 

If you are tearing out existing cans, then 'less invasive' probably doesn't matter much. Cutting drywall is quite simple, so, making these backer sandwiches is quite easy, so, I would probably go that route if I were doing it, but thought I would share this thread in case it interests you.


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## mtbdudex

DIY double door seals, has it been done in this thread?
Documented with data?

I was adding my bought alum track door seals and decided to re-do the door stop from 7/16" to 3/4" and add a EPDM tape attach bulb seal along 3 sides as shown below.

I simply ripped existing 1" x 4" stock, took both good edges, ripped those to 1 5/8" initially, then to 1 3/8" for final cut.
I stained them last night to match, tonight I will install and hopefully take some REW readings with just door stop, then add the alum track door seals and take readings, then remove that and add the EPDM tape attach bulb seal and take readings, then add the alum track door seals for final double seal readings.
This will show pure DIY and pure store bought, then double seal.

Auto door bottom also will be added along the way, I have it also.

Mark-up shows what I'm doing:
I'm setting the new 3/4" depth door stops 1/8" gap from the door per spec sheet, as door is pressed against the shut plate.
EPDM seal bought for that range of gap along handle/top side, the hinge side it's a really small gap so I got the thinnest for that.









These are for 1/8 - 5/16 gap, I'm setting a 1/8 gap, as long as the total reaction force does not make closing efforts too much I should be ok. If so, then I can downsize to the skinniest one.



















Here's the before pictures:
















.


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## panino

mtbdudex said:


> panino - how did you tackle your french doors?
> My brother inlaw has them, just your basic interior french doors not solid core, and was thinking to upgrade his for more effective soundproofing.


First off... I wasn't as particular about getting my doors 100% soundproofed (if there is such a thing). I just wanted "good". Your situation may be different. My doors are solid core, so that helps quite a bit. I originally planned on door sweeps, gaskets, and an astragal where the doors meet to seal up the small air gap between both doors. I ended up most of the way there. I installed a carpet divider to provide a nice smooth surface for a door sweep to contact and then installed a door sweep, rather than automatic door bottoms. I lined all edges of the door frame with 1/2" self-adhesive gasket. Since I custom made my frames, I made the stops a bit wider to accommodate the larger 1/2" gasket. 

I did not put an astragal on the doors yet. I figured I'd give it awhile and see if I thought I'd need it. There is a noticeable air gap (~1/16") between both doors, so some sound obviously leaks through. However, being that my theater is in the basement and there is no one in sight to disturb this hasn't posed a problem and the leakage seems pretty minimal. In fact, I can have a movie playing fairly loud and it can barely be heard at the top of the basement steps. I can't hear it at all on the level above. Given this, I'm fairly happy with the way my soundproofing turned out and I'll probably forgo an astragal or any further soundproofing of the doors.

Although you could definitely go with more insulating (albeit more expensive) hardware and seals, this is what I used:
Carpet divider: http://www.tmhardware.com/Carpet-Divider-Rubber-2.5.html
Pemko door sweeps: http://www.tmhardware.com/Door-Sweep-1.188-Aluminum-Casing-with-.69-Triple-Vinyl-Fin.html
Zero Intl door gasket: http://www.tmhardware.com/Adhesive-Weatherstrip-5-Wide-Silicone-or-Intumescent-Teardrop.html


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## dan webster

I realize this may have been discussed here before. I just finished building a wall and installing a exterior metal door at the bottom of my basement stairs going into my theater. Before this the whole area was open . This certainly has made a significant difference in reducing much of the sound from traveling up the stairs. I have never been too concerned with soundproofing my basement theater up until now. I used roxul safe and sound in the wall and added another layer to my existing insulated drop ceiling . Except for the very low base i am satisfied with the results except for the door. I feel it is the weak point and am considering adding some mass to it. From my research here i was thinking about 2 sheets of 1/2 " mdf with green glue between them screwed to the inside of the metal door and possible another gasket around the door jam to better seal the mdf. I would appreciate any other thoughts or feedback.


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## mtbdudex

What's inside your exterior metal door?
I doubt it's wood/particle board/ mdf, rather a foam core? Good insulator but weak for attaching thru via a coarse screw.
If so, how to secure your added mdf sheets? 
Bolt thru all the way both sides of door would work but not look nice.


Via Mikes brain/thumb interface, LLAP


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## granroth

dan webster said:


> I realize this may have been discussed here before. I just finished building a wall and installing a exterior metal door at the bottom of my basement stairs going into my theater. Before this the whole area was open . This certainly has made a significant difference in reducing much of the sound from traveling up the stairs. I have never been too concerned with soundproofing my basement theater up until now. I used roxul safe and sound in the wall and added another layer to my existing insulated drop ceiling . Except for the very low base i am satisfied with the results except for the door. I feel it is the weak point and am considering adding some mass to it. From my research here i was thinking about 2 sheets of 1/2 " mdf with green glue between them screwed to the inside of the metal door and possible another gasket around the door jam to better seal the mdf. I would appreciate any other thoughts or feedback.


If it's a traditional steel exterior door, then it'll be filled with foam -- not a very good door from a soundproofing perspective. If it's hollow, though, then you have some options. The best soundproofed doors are actually steel doors that are filled with concrete or some other similarly ultra-dense material. If yours is hollow, then drilling some holes in it and filling it with concrete or, better yet, sand, would make for an extremely heavy but very sound resistant door.

Your next best bet is to actually replace that door with a solid-core one. Believe it or not, the interior solid-core doors are actually better from a sound proofing perspective than an exterior door. You can typically get one for $200 or so.

If you're sticking with that door, then adding the MDF with Green Glue plus sealing off the entire thing with gaskets would definitely help quite a bit and well worth the time to do it! I'd glue that first layer of MDF on the door with PL-375 or similar. Screws can keep things aligned, but I don't know how much I'd trust _just_ screws long-term -- the glue will go a long way.


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## jackforceus

*Soundproofing questions*

Hello experts,
You might have answered these questions thousand times. I tried to read the threads but there were several suggestions and I couldn't really understand how to use them for my requirements.Sorry...
I have attached the picture of my unfinished basement room that I'm planning to use as a home theater. Its going to be a open home theater and I would like to do my best to contain sound going into the first floor. Two sides and a half sides are concrete. The room width is w - 178 * L - 240 with a 9 ft ceiling height

Can you please advice me with the following questions?
1). What kind of sound insulation do I need for walls, ceiling and floor?
2). What all the materials do I need to purchase and where to purchase them?
3). I was thinking most of Low frequency tries to escape through the ceiling, so having a good sound insulation for ceiling would cover the sound issues?
4). I would like this room to be a sitting room as well as home theater if needed. Planning to have a fireplace, shelves etc. Will pull the projector screen if we want to watch something. Would that work?
4). How much big of a screen size can I have?
Thanks a lot..


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## granroth

jackforceus said:


> Hello experts,
> You might have answered these questions thousand times. I tried to read the threads but there were several suggestions and I couldn't really understand how to use them for my requirements.Sorry...
> I have attached the picture of my unfinished basement room that I'm planning to use as a home theater. Its going to be a open home theater and I would like to do my best to contain sound going into the first floor. Two sides and a half sides are concrete. The room width is w - 178 * L - 240 with a 9 ft ceiling height
> 
> Can you please advice me with the following questions?
> 1). What kind of sound insulation do I need for walls, ceiling and floor?
> 2). What all the materials do I need to purchase and where to purchase them?
> 3). I was thinking most of Low frequency tries to escape through the ceiling, so having a good sound insulation for ceiling would cover the sound issues?
> 4). I would like this room to be a sitting room as well as home theater if needed. Planning to have a fireplace, shelves etc. Will pull the projector screen if we want to watch something. Would that work?
> 4). How much big of a screen size can I have?
> Thanks a lot..


To be honest, you may be an ideal candidate for a theater designing service. You can get a pretty decent plan for under $1000 and it would be money well spent if time is precious.

Alternatively, check out the Home Theater Book (http://thehometheaterbook.com/) which for only $80 will give you a very solid basis of home theater knowledge that you can then build on with more specific questions. It's not quite as quick as paying for a design service, but still requires many many MANY hours less time than finding it all out directly on AVS.


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## Harish Gangidi

I'm new to AVS forms. I'm building a new home and a dedicated home theatre(15.10 by 19.6). I am interested about sound proofing my theatre. When inquired about the pricing he said its 400 but i don't know what kind of material is he using to do it. Do you guys know if this is typically the price? will it do any better ?


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## granroth

Harish Gangidi said:


> I'm new to AVS forms. I'm building a new home and a dedicated home theatre(15.10 by 19.6). I am interested about sound proofing my theatre. When inquired about the pricing he said its 400 but i don't know what kind of material is he using to do it. Do you guys know if this is typically the price? will it do any better ?


Unfortunately, just quoting a price means absolutely nothing at all. It could mean, say, the price of the double layer of drywall (which would absolutely help some) or it could mean some overpriced piece of foam that did nothing. It certainly doesn't include the cost of Green Glue, if that comes into play.

The thing is -- soundproofing is all about the details. Every little detail counts if you want to get the most bang for your buck. So even if your builder tells you at a high level what the $400 buys you, it doesn't mean that it would actually be worth $400 unless we could know the specific details of how that solution would be implemented.

That said... no, $400 rarely or never will get a soundproofing solution. It can pay for one element of a larger solution.


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## ch1sox

Harish Gangidi said:


> I'm new to AVS forms. I'm building a new home and a dedicated home theatre(15.10 by 19.6). I am interested about sound proofing my theatre. When inquired about the pricing he said its 400 but i don't know what kind of material is he using to do it. Do you guys know if this is typically the price? will it do any better ?


A lot of contractors don't fully understand soundprooing principles. They usually just throw insulation in the wall and call it soundproofed.

You'll want to start reading some articles over at soundproofingcompany.com http://www.soundproofingcompany.com/soundproofing101/

Once you've done that you'll need to determine how important it is to you to soundproof. Keep in mind, your weakest link will effect your result. Weakest link such as a door, stairs, vents, etc. Think of it like a fish bowl. If the tank (theater) has a hole, water (sound) is going to leak.

Make sure you do all walls, ceiling and floor. If it's a basement on a concrete slab then the floor can be skipped. If you don't do the walls, sound will flank through the walls and go up or down to the other floors. 

The two most important factors are decoupling and mass. When you decouple you build double stud walls with floating joists or use metal channels attached to clips which are attached to the wall studs and ceiling joists. Here's an example of the clips: http://www.soundproofingcompany.com/...solation-clip/ The drywall then attaches to the channel. You want to use 5/8" type x drywall. The more mass, the better. It's recommended to double the 5/8" drywall with staggered seams. If room height is a concern with the clips, you can install the clips/channel to where the ceiling would only be 1/2" inch below the ceiling joists. 

To help with cavity resonance you can use pink fiberglass insulation. 

If you want to do more, you would than use green glue or something similar between the two pieces of drywall. Keep in mind it's not actually glue. It doesn't harden which allows the drywall to flex. 

There is also the issue of ceiling lights. Any lights need to have backer boxes. If you don't use backer boxes than you'll have created a swiss cheese ceiling for sound to travel through. You may also want to treat any supply/return vent that opens into the room. If you have done all this than you should do the outlets as well by using puddy pads or duct seal.

You can read more in depth about these principles at soundproofingcompany.com.

...therefore $400 is more than likely not enough.


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## Brian Fineberg

just an fyi from personal experience. My father inlaw built houses for 35 years (lives in one he built entirely..and 2 others) and he thinks roxul safe and sound is a soundproofing solution.

they know nothing of true soundproofing...so only trust what you read here


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## cw5billwade

I was going to say read this entire thread. My Room 19x23 just for sound proofing materiels i.e. IB1 Clips to decouple rear wall IB3 Clips and hat channel for other 3 walls and ceiling, 5 ea 5 gallon buckets of green glue. 2 cases of acustical caulk 28oz builder size all ran around $3000 this did not include the R19 in ceiling R15 in walls Dry wall and OSB and stick materiel 2x4s 2x8s and 2x12s which builder privided and rooled into cost of house.


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## Brian Fineberg

Yeah soundproofing ain't cheap. That's why under our personal circumstances (and it not being 100% required to be isolated and more a luxury) we opted to not go the soundproof route


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## jer181

I am just in the process of developing my basement and putting a theater down stairs. I want to know if I have to sound proof (2 layers of 5/8" drywall, green glue,clips and channel) the whole area, or if just the roof and side walls backing onto another room would suffice? The other walls are around surrounded by the concrete foundation.


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## ch1sox

jer181 said:


> I am just in the process of developing my basement and putting a theater down stairs. I want to know if I have to sound proof (2 layers of 5/8" drywall, green glue,clips and channel) the whole area, or if just the roof and side walls backing onto another room would suffice? The other walls are around surrounded by the concrete foundation.


It would be easier to see if you had a quick sketch of the area, but generally if the walls are attached to the ceiling joists, than you need to do those as well. If the floor is on a giant concrete slab than than you can skip that. Don't forget other things like vents, stairs, outlets, etc.


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## kmhvball

I think you would still want to do double drywall and green glue, but don't need clips and channel as long as toy atttach vertical wall to floor jousts with an ib3 clip... and the framed wall should be ~1" off the concrete wall


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## KanosWRX

jer181 said:


> I am just in the process of developing my basement and putting a theater down stairs. I want to know if I have to sound proof (2 layers of 5/8" drywall, green glue,clips and channel) the whole area, or if just the roof and side walls backing onto another room would suffice? The other walls are around surrounded by the concrete foundation.


My room had three sides that were foundation walls, the back wall was to the other part of the basement. I did a double wall for the wall between that room and my home theater. It was 2 sheets 5/8 with green glue, stud with insulation, 1" air gap, then stud with insulation then one layer of 5/8" drywall. The walls next to the foundation I just built a few inches from the foundation and stuffed insulation in, then double drywall and green glue. No clips or channels anywhere except for the ceiling, which is also double drywall and green glued.


----------



## mtbdudex

Now that my HT 4ft door is installed and sealed, I'm tackling the next weak link in my soundproofing, the AV rack back access doors.

AV rack in HT room, backside has doors in adjoing rec room for easy access. (yes, cable organization / management is on bucket list also)







.









I'm looking for thoughts/feedback/other ideas.

I've already applied a seal to 1 door, it did help with sound escaping less, but 2 things are obvious:
1) low bass just passes thru that basic 3/4" MDF door, so I need to add more mass to it, I've got lots of MDF was thinking to glue two 3/4" pieces to the inside as sandwich for 2.25" thick
2) The doors needs a better shut mechanism, those roller pull catch not up to good pull against the seals.

So, adding more mass is desirable, I don't have any tubes of GG, is there "similar" damping material at HD/Lowes or I need to buy 1 tube of GG?









Hinges and roller ball catch currently installed, plus basic seal from Home Depot.







.









I'm using this seal 

















Now, getting a good door close/seal, those roller catch don't have good grab power, so I'm thinking to add 1-2 of these to each door:
http://www.rockler.com/friction-door-catch


> Great for RV and other mobile cabinet applications! Simple to install, easy to use.
> Plastic strike is captured by receiving sleeve and holds the door firmly in place, even when being jostled.












doing a search on "door catch" in rockler I've looked at other catch's, but the one above seems the simplest and hopefully the most "grabbing" power
http://www.rockler.com/mini-latch-automatic-spring-catch
http://www.rockler.com/safe-push-touch-latches-select-size-and-color
http://www.rockler.com/quick-latch-automatic-spring-catch


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## Mfusick

Magnets


----------



## granroth

mtbdudex said:


> 2) The doors needs a better shut mechanism, those roller pull catch not up to good pull against the seals.


I'll second Mike's suggestion -- rare earth magnets. That's assuming that you want a hidden mechanism, since all of your examples are in that direction.

If you want to be absolute sure on the seal, then some sort of lever based mechanical connection would work best. There are any number cabinet latches or sliding bolts or similar that would suffice. They install on the outside of the door so there's no sound intrusion and they won't close at all until you push the door into the seal.

But yeah, they're very visible. Although this combination lock and sliding bolt looks pretty slick: http://www.amazon.com/Combi-Bolt-CB2000-BLACK-Sliding-Bolt-Lock/dp/B000I66TTW/



mtbdudex said:


> So, adding more mass is desirable, I don't have any tubes of GG, is there "similar" damping material at HD/Lowes or I need to buy 1 tube of GG?


I've seen alternatives to quite a few standard soundproofing components... but never for Green Glue. Curious, now that I think about it. Why are there no Green Glue competitors?


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## Apgood

granroth said:


> I'll second Mike's suggestion -- rare earth magnets. That's assuming that you want a hidden mechanism, since all of your examples are in that direction.
> 
> If you want to be absolute sure on the seal, then some sort of lever based mechanical connection would work best. There are any number cabinet latches or sliding bolts or similar that would suffice. They install on the outside of the door so there's no sound intrusion and they won't close at all until you push the door into the seal.
> 
> But yeah, they're very visible. Although this combination lock and sliding bolt looks pretty slick: http://www.amazon.com/Combi-Bolt-CB2000-BLACK-Sliding-Bolt-Lock/dp/B000I66TTW/
> 
> 
> 
> I've seen alternatives to quite a few standard soundproofing components... but never for Green Glue. Curious, now that I think about it. Why are there no Green Glue competitors?


There is quietglue pro, but it's hard to get at the moment I believe because they are working on a new formulation. Supplier here in oz said at least 2 months before they get new stock.


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## ch1sox

@mtbdudex Menards has green glue by the tube.
@granroth QuietGlue Pro is a competitor to green glue. It's just most people on this forum menton Green Glue. Kinetics also makes a product and there's another product from another company I saw on youtube, but I forget who it was.


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## granroth

Interesting!! I had not heard of QuietGlue Pro before, but it looks like it's a very solid competitor to Green Glue. THIS THREAD has links to whitepapers and rebuttals and the like that all indicate that QuietGlue Pro is at least as good as Green Glue and maybe better (depending on who you talk to).

It's definitely less expensive. In my quick searching, I see it for at least $40 less for a 5 gallon bucket ($199/bucket at ATS Acoustics). The cost savings may be even more dramatic for the individual tubes.

Sweet.


----------



## carterth

*Soundproofing for music rehearsal/media room?*

Hi folks,

First of all, this thread and forum have been really helpful for this total newbie to soundproofing. I wanted to bounce some ideas off you all before I end up sinking a bunch of money into my first attempt at doing this right.

A little background: my wife and I are moving into a very small duplex where we will occupy the top floor (about 400 sq ft) and rent out the bottom floor. The wife is a classical pianist and a night owl, and works best when she can practice any hour of night, hence the need for soundproofing. We've looked into renting commercial/office space to let her practice, but that has been a no-go due to high rent and distance so we want to make it work at home. Given the general lack of space in the unit, we are making one room into a music studio/media/living room, with a grand piano and speaker system setup (she likes to "play along" with recordings which requires very high volume levels). 

The home is a Washington, DC rowhouse built in the 50's. The room in question has one party wall of plaster-covered brick, with the interior walls I assume being plaster over studs (no drywall as far as we can tell). A closet sticks out about a foot into one corner of the room. The wall opposite the party wall has about a foot of ductwork sticking out from the ceiling. There is one window facing the rear of the property across from the wall with the closet. There's also one standard light fixture on the ceiling in the center of the room.

We have to do the best we can to soundproof the floor (to avoid making our tenant hate us) and the party wall (to avoid making our neighbor hate us). Soundproofing the interior walls would be great since I'd bet enough sound leaks out into the hallway/kitchen to annoy the neighbor on the other side as well. We've budgeted a few thousand dollars to do this before we move, so while I'm sure we can't find a 100% perfect solution, we need the most bang for our buck. What we probably DON'T have money to do (unfortunately) is remove the plaster and do "re-construction" the right way, with multiple layers of drywall, decoupling, putty pads, etc.

Our current thoughts based on internet research are the following:
- For the walls (including around the ductwork), put up a layer of drywall on top of the plaster (5/8 or 1 inch) with Green Glue in between (3 tubes per sheet), then noiseproofing sealant around all edges, outlets, fixtures, etc.
- For the floor, add the following on top of the current laminate: eggshell foam/some other product with air pockets, mass-loaded vinyl sheets, rebond carpet pads, then regular carpet on top.
- Layers of thick blackout curtains in front of the window
- Replace door with solid-core door with weatherstripping

Any thoughts on whether this is cost-effective, or likely to be effective period, would be much appreciated. In particular, I haven't been able to find any information on whether putting drywall/Green Glue over plaster works as well as putting it over existing drywall. Would I need a second layer of drywall so the GG is between surfaces of the same density (essentially creating a "Green Glue sandwich" over the plaster), rather than right on the plaster? I do need to avoid losing too much floor space since sq footage is so tight in this unit to begin with.

Thanks very much.,
Tom in DC


----------



## mtbdudex

ch1sox said:


> @mtbdudex Menards has green glue by the tube.
> @granroth QuietGlue Pro is a competitor to green glue. It's just most people on this forum menton Green Glue. Kinetics also makes a product and there's another product from another company I saw on youtube, but I forget who it was.


Thx, I see it for $15/28oz tube online....
http://www.menards.com/main/buildin...ue-noiseproofing-compound-28-oz/p-1725463.htm
There is a Menards I-96 by Wixom road being finished just now, I'll order 2 tubes for my AV 2 doors and my HT 4ft wide door.


----------



## granroth

carterth said:


> Hi folks,
> 
> First of all, this thread and forum have been really helpful for this total newbie to soundproofing. I wanted to bounce some ideas off you all before I end up sinking a bunch of money into my first attempt at doing this right.
> 
> A little background: my wife and I are moving into a very small duplex where we will occupy the top floor (about 400 sq ft) and rent out the bottom floor. The wife is a classical pianist and a night owl, and works best when she can practice any hour of night, hence the need for soundproofing. We've looked into renting commercial/office space to let her practice, but that has been a no-go due to high rent and distance so we want to make it work at home. Given the general lack of space in the unit, we are making one room into a music studio/media/living room, with a grand piano and speaker system setup (she likes to "play along" with recordings which requires very high volume levels).
> 
> The home is a Washington, DC rowhouse built in the 50's. The room in question has one party wall of plaster-covered brick, with the interior walls I assume being plaster over studs (no drywall as far as we can tell). A closet sticks out about a foot into one corner of the room. The wall opposite the party wall has about a foot of ductwork sticking out from the ceiling. There is one window facing the rear of the property across from the wall with the closet. There's also one standard light fixture on the ceiling in the center of the room.
> 
> We have to do the best we can to soundproof the floor (to avoid making our tenant hate us) and the party wall (to avoid making our neighbor hate us). Soundproofing the interior walls would be great since I'd bet enough sound leaks out into the hallway/kitchen to annoy the neighbor on the other side as well. We've budgeted a few thousand dollars to do this before we move, so while I'm sure we can't find a 100% perfect solution, we need the most bang for our buck. What we probably DON'T have money to do (unfortunately) is remove the plaster and do "re-construction" the right way, with multiple layers of drywall, decoupling, putty pads, etc.
> 
> Our current thoughts based on internet research are the following:
> - For the walls (including around the ductwork), put up a layer of drywall on top of the plaster (5/8 or 1 inch) with Green Glue in between (3 tubes per sheet), then noiseproofing sealant around all edges, outlets, fixtures, etc.
> - For the floor, add the following on top of the current laminate: eggshell foam/some other product with air pockets, mass-loaded vinyl sheets, rebond carpet pads, then regular carpet on top.
> - Layers of thick blackout curtains in front of the window
> - Replace door with solid-core door with weatherstripping
> 
> Any thoughts on whether this is cost-effective, or likely to be effective period, would be much appreciated. In particular, I haven't been able to find any information on whether putting drywall/Green Glue over plaster works as well as putting it over existing drywall. Would I need a second layer of drywall so the GG is between surfaces of the same density (essentially creating a "Green Glue sandwich" over the plaster), rather than right on the plaster? I do need to avoid losing too much floor space since sq footage is so tight in this unit to begin with.


Working backwards...

Yes, Green Glue or QuietGlue Pro will still effectively work as a damping agent between drywall and plaster. It is often inserted between sheets of dissimilar materials with varying densities and properties and still is effective.

I would be a little leary of some of your internet sources for soundproofing info if eggshell foam plays any role in their recommendation. Eggshell foam is one of those products that get touted a lot by people that don't know what they are talking about and rarely perform at the level that is suggested. I'm not saying that it can't play any role... but especially for soundproofing, I can't imagine any role where it would matter.

I haven't seen any indication that more than 2 tubes per sheet has any notable impact on its effectiveness. You might just be wasting money at that point.

The steps that you list will absolutely have a measurable effect on sound escaping from and intruding into your space. But here's where I deliver the bad news. It will almost surely not be even close to the level that you want and/or expect it to be.

Most of the people who do haphazard levels of soundproofing have generic goals of wanting to lower the sound floor by some unspecified amount or maybe be able to play a movie at reference where it's only a little loud directly outside of the theater. In those general cases, using random elements of soundproofing even in unproven configurations will give noticeable results and you can rest happy.

But it doesn't sound like you are in a situation like that. In your case, you almost surely REQUIRE a specific level of sound attenuation and even more so, sound attenuation at specific levels for specific frequencies. Instruments like a grand piano are incredibly loud across a wide band of frequencies.

Let's make up some base assumptions. Your wife playing at _pp_ would be at 70 dB and at _fff_ at 100 dB. In order to not disturb your tenant and neighbors at 2am, you'll likely need to attenuate that down to 30dB. From a broad perspective, you'd need a soundproofing solution with an STC 40 rating at the low end and up to STC 70 at the high end. It's actually more complicated than that since STC is measuring a very specific frequency band that might not correspond to the frequency range that your wife plays. But let's use this for an example.

Your ad-hoc soundproofing method might approach STC 40 if the rest of the building is taking up some of the slack. That is, your door will not hit STC 40 on its own with just being solid-core with weatherstripping -- you'd need some other mitigating factors that are already existing in the building to knock it down a few more dB. That'll take care of the case where your wife is playing very very softly.

When she needs to bang out some Tchaikovsky and needs that STC 70... well, your solution won't even come a little bit close. Not even in the same universe. If you're getting STC 40 then your tenant still hears 60dB which is _very_ audible, especially when trying to sleep!

So what can you do? Nothing ad-hoc. Hitting STC 70 requires a lot of very specialized techniques and it needs to be done exactly right. It's absolutely time to call in a professional. It won't be cheap and it'll almost surely take away more space.

My suggestion? This might be anathema to a classically trained pianist, but maybe consider using a keyboard with headphones at night and restrict the loud playing during the day?!


----------



## Nuieve

Can someone give me quick answers to the following questions: I've been reading on insulation for the last week, hours and hours, read lots of articles about different wall construction techniques... and still feel lost in the woods... basically my questions are these:

1. Is there a major difference in going with double walls
- each insulated with 3" gap in between vs
- one insulated with only 1" gap in between
*by gap I mean distance between ends studs, not layers of sheetrock... it gets confusing... so U_U (U is stud with insulation in it and _ is air gap between them in question)

2. I can't afford Golden Glue, and I can't get those hat channels locally, so I won't be using them. Will simple doubling of drywall help any or is it not worth it and I should stick with just one layer? 
I read conflicting reports, most articles recommend double-drywalling, but never specify if they mean using them with Golden Glue or not. Others that do mentions Golden Glue, say doublelayering drywall without it is useless.


----------



## granroth

Nuieve said:


> Can someone give me quick answers to the following questions: I've been reading on insulation for the last week, hours and hours, read lots of articles about different wall construction techniques... and still feel lost in the woods... basically my questions are these:
> 
> 1. Is there a major difference in going with double walls
> - each insulated with 3" gap in between vs
> - one insulated with only 1" gap in between
> *by gap I mean distance between ends studs, not layers of sheetrock... it gets confusing... so U_U (U is stud with insulation in it and _ is air gap between them in question)


There is no real practical difference between the two, based entirely on the gap distance. Anywhere from a 1/2" to 1" gap is pretty typical. This translates to a Mass to Mass distance of 7-1/2" to 8" (since it's not from stud to stud that matters but from drywall to drywall).

I do believe there is a technical difference in the frequency that the wall resonates at (wider gap equals lower resonant frequency) but it's not going to be enough to matter at a practical level since a 8" gap is already well into LFE territory.

There _will_ be a measurable difference if you insulate only one side vs both sides. Definitely insulate both sides. Adding insulation essentially acts like it's widening the distance.

You can get real numbers by looking at the tests done by the NRC group in Canada. There's a link to their PDFs at the beginning of this thread.



Nuieve said:


> 2. I can't afford Golden Glue, and I can't get those hat channels locally, so I won't be using them. Will simple doubling of drywall help any or is it not worth it and I should stick with just one layer?
> I read conflicting reports, most articles recommend double-drywalling, but never specify if they mean using them with Golden Glue or not. Others that do mentions Golden Glue, say doublelayering drywall without it is useless.


You don't need hat channels if you'll be doing double walls (unless for the ceiling, if you don't have floating joists). And doubling up the drywall without using a damping agent like Green Glue or QuietGlue Pro will _absolutely_ still help! Doubling the mass will add 6dB of additional soundproofing to the structure. 6dB is perceived as "twice as loud", so it's pretty significant.

Damping agents definitely have their place, but it's after the biggest "bang for the buck" components like decoupling and adding mass.


----------



## BasementBob

Nuieve said:


> Will simple doubling of drywall help any or is it not worth it and I should stick with just one layer?


 
When the mass of a barrier is doubled, the isolation quality (or STC rating) increases by approximately 4-6 dB.


----------



## Nuieve

Thanks guys!!!

So if I do insulate both walls (which I'm gonna do now), do I have to increase the gap between the walls (studs) extra couple inches? Is the distance filled with insulation considered "air" or "not air"? I know that it's important to have plenty of "air" in between the "mass", but I'm not sure if padding the 2nd wall requires moving the wall away to compensate. 

Sorry for asking stupid or obvious questions, I want to be 100% sure I'm not doing something profoundly stoopid.


----------



## VolkerH.

I meant to ask if i would get a benefit of double drywall with a green glue layer when already going double wall (with filler) but I think I gave myself the answer on that as I want to convert part of the outer wall into DVD storage. So yes, double DW it is on the inside. 
So let me ask the remaining question. 
For the ceiling (HT space is in the basement 14'x10' and 8' high), if I plan to put double DW on the ceiling, is there a benefit to mount the DW on a suspended 2x3 framework that mimics a double wall vs. going with hat channels ? For the suspended frame I'm not sure if I can simply support it only laying on the inner walls, it might sag. What method of suspending it from the ceiling joists would be acceptable/available ? Long screws that leave room between the 2 layers ? Chains to hang the frame work ? Any other method ?


----------



## granroth

Nuieve said:


> So if I do insulate both walls (which I'm gonna do now), do I have to increase the gap between the walls (studs) extra couple inches? Is the distance filled with insulation considered "air" or "not air"? I know that it's important to have plenty of "air" in between the "mass", but I'm not sure if padding the 2nd wall requires moving the wall away to compensate.


Insulation is considered "air" in a "mass air mass" scenario. The distance that matters if from the inside drywall layer(s) to the outside drywall layer(s).

Actually, from a practical point of view, you can think of insulation as "super air"  What air brings to the table here is the reduction of the resonant frequency of the wall and insulation (acting as an absorber) also has the effect of reducing the resonant frequency. Combine the two and you essentially combine their benefits to decrease that frequency more than either of the solutions on their own.


----------



## granroth

VolkerH. said:


> For the ceiling (HT space is in the basement 14'x10' and 8' high), if I plan to put double DW on the ceiling, is there a benefit to mount the DW on a suspended 2x3 framework that mimics a double wall vs. going with hat channels ? For the suspended frame I'm not sure if I can simply support it only laying on the inner walls, it might sag. What method of suspending it from the ceiling joists would be acceptable/available ? Long screws that leave room between the 2 layers ? Chains to hang the frame work ? Any other method ?


Any loosely suspended ceiling like that would absolutely sag with two layers of drywall. That's heavy stuff! You'd need to add quite a bit of rigid support... and then you've completely coupled your frame to the ceiling joists, so might as well save a few inches and attach the drywall to the joists directly.

If you don't want to use clips and channels (likely cost reasons?) then are you able to use floating joists? If your joist bays have enough space, then just lay some new joists in between them and resting only on the inner walls. You'd lose maybe 3/4" or 1" of space but it would be completely decoupled at a fraction of the cost of clips and channels.


----------



## Nuieve

granroth said:


> Insulation is considered "air" in a "mass air mass" scenario. The distance that matters if from the inside drywall layer(s) to the outside drywall layer(s).
> 
> Actually, from a practical point of view, you can think of insulation as "super air"  What air brings to the table here is the reduction of the resonant frequency of the wall and insulation (acting as an absorber) also has the effect of reducing the resonant frequency. Combine the two and you essentially combine their benefits to decrease that frequency more than either of the solutions on their own.


Thank you. 

So I will have:
2x5/8 drywall layers
2x4 studs with R13 insulation 
1" air gap
2x4 studs with R13 insulation 
2x5/8 drywall layers

Like in here:










Please let me know if that's NOT what I want to do. Otherwise I assume I'm good to go.


----------



## granroth

Nuieve said:


> So I will have:
> 2x5/8 drywall layers
> 2x4 studs with R13 insulation
> 1" air gap
> 2x4 studs with R13 insulation
> 2x5/8 drywall layers
> 
> Like in here:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Please let me know if that's NOT what I want to do. Otherwise I assume I'm good to go.


Yep, looks good. You can predict your performance by looking in the NRC IR-761 PDF for wall assembly TL-93-269 (2G16_WS90(406)_GFB90_AIR25_WS90(406)_GFB90_2G16) which is exactly your proposed wall if you have the studs 16" O.C. It achieves an STC 67 rating, which is excellent.

IR-761, btw, is here: NRC-CNRC IR-761 (PDF)


----------



## Nuieve

granroth said:


> Yep, looks good. You can predict your performance by looking in the NRC IR-761 PDF for wall assembly TL-93-269 (2G16_WS90(406)_GFB90_AIR25_WS90(406)_GFB90_2G16) which is exactly your proposed wall if you have the studs 16" O.C. It achieves an STC 67 rating, which is excellent.
> 
> IR-761, btw, is here: NRC-CNRC IR-761 (PDF)


Thank you!


----------



## Ben Ayr

Hi there,

I'm not building a home theater, but in the last few days that I've been researching soundproofing and noise treatment it seems like this forum has some of the most knowledgable people out there.

I have an unusual building I've been working on that is Quonset shaped (semi-circle) using 24" center bent steel pipe as studs/joists covered in corrugated sheet metal. I wasn't really thinking ahead to noise treatment or I would have done some things differently but now that I'm at this stage I've been trying to figure out what I can do.
Was going to post a picture but apparently I can't on my first post.

I enclosed the end using an array of windows (3.2mm glass) framed in cedar. Obviously this is terrible for keeping sound out, but that's hindsight. There are also skylight boxes attached to the pipe at the top to let some light in so I guess sound will be flanking through those as well.The only real noise I'm interested in getting rid of is the road about 1/8 mile away that gets some loud trucks going down it. 

I don't know if RC1 will be effective on the curve of the wall because I will have to bend gypsum board over it, probably compressing the springiness of it and not hanging well. I'm considering RC2 channel as furring but there don't appear to be any STC ratings on it. Alternatively I could run hat channel but I don't have the budget to outfit the whole space in sound clips so it would only be to add air/insulation space rather than decouple. So one of my questions would be, do you think that RC2 would outperform unclipped hat channel in any way? Would I achieve some small level of decoupling by using the RC2? I'm aware of the convoluted history of RC1 and its untested offspring.

The pipe "studs" only give me about an inch and a half, part of which is taken up by the spray foam. I could add a thin layer of fiberglass over that, then RC or hat channel for furring to give me another 1/2" or 7/8". Bend some gypsum onto it, leaving the option of going back and green gluing another thin sheet of gypsum as my budget allows. 

Will any of this have any worthwhile effect or will the sound flanking through the front/skylights make it completely pointless? Not sure if it helps, but the front isn't facing the roadway and I live in a forested area. 

Rather than attempting to decouple at all would I be better off putting my money into a damping compound and fastening the gypsum directly to the pipe?

Any insight or opinions welcome. I've been reading a good bit on your forum, but what I'm working with is a bit distant from a typical wood framed wall.

Thanks much.

Ben

Additional info: My goal would be to get this space quiet enough to record some music in. I could probably filter out the lower frequencies to a degree, but I'm worried about the road noise.


----------



## genofive0

Ben Ayr said:


> Hi there,
> 
> I'm not building a home theater, but in the last few days that I've been researching soundproofing and noise treatment it seems like this forum has some of the most knowledgable people out there.
> 
> I have an unusual building I've been working on that is Quonset shaped (semi-circle) using 24" center bent steel pipe as studs/joists covered in corrugated sheet metal. I wasn't really thinking ahead to noise treatment or I would have done some things differently but now that I'm at this stage I've been trying to figure out what I can do.
> Was going to post a picture but apparently I can't on my first post.
> 
> I enclosed the end using an array of windows (3.2mm glass) framed in cedar. Obviously this is terrible for keeping sound out, but that's hindsight. There are also skylight boxes attached to the pipe at the top to let some light in so I guess sound will be flanking through those as well.The only real noise I'm interested in getting rid of is the road about 1/8 mile away that gets some loud trucks going down it.
> 
> I don't know if RC1 will be effective on the curve of the wall because I will have to bend gypsum board over it, probably compressing the springiness of it and not hanging well. I'm considering RC2 channel as furring but there don't appear to be any STC ratings on it. Alternatively I could run hat channel but I don't have the budget to outfit the whole space in sound clips so it would only be to add air/insulation space rather than decouple. So one of my questions would be, do you think that RC2 would outperform unclipped hat channel in any way? Would I achieve some small level of decoupling by using the RC2? I'm aware of the convoluted history of RC1 and its untested offspring.
> 
> The pipe "studs" only give me about an inch and a half, part of which is taken up by the spray foam. I could add a thin layer of fiberglass over that, then RC or hat channel for furring to give me another 1/2" or 7/8". Bend some gypsum onto it, leaving the option of going back and green gluing another thin sheet of gypsum as my budget allows.
> 
> Will any of this have any worthwhile effect or will the sound flanking through the front/skylights make it completely pointless? Not sure if it helps, but the front isn't facing the roadway and I live in a forested area.
> 
> Rather than attempting to decouple at all would I be better off putting my money into a damping compound and fastening the gypsum directly to the pipe?
> 
> Any insight or opinions welcome. I've been reading a good bit on your forum, but what I'm working with is a bit distant from a typical wood framed wall.
> 
> Thanks much.
> 
> Ben
> 
> Additional info: My goal would be to get this space quiet enough to record some music in. I could probably filter out the lower frequencies to a degree, but I'm worried about the road noise.


Wow this sounds like a headache. But I can assure you came to the right place I know the people here can help you get what you are trying to do done. with that said the level you can achieve and or cost could be an issue. Honestly I would wait until some of the more experienced guys chime in. I know a drawing or dimensions would help them understand what your working with. Best of luck and welcome


----------



## Ben Ayr

genofive0 said:


> Wow this sounds like a headache. But I can assure you came to the right place I know the people here can help you get what you are trying to do done. with that said the level you can achieve and or cost could be an issue. Honestly I would wait until some of the more experienced guys chime in. I know a drawing or dimensions would help them understand what your working with. Best of luck and welcome


Thanks. I was trying to post a picture but it won't let you on your first five posts. This is the address but it filters it if I have the http or image tags on there.

i1095.photobucket.com/albums/i473/Ben_Ayers/image.jpg1.jpg

Last thing I did was spray foam, thus the mess.

I hear you on the headache part. Also understand if there are too many factors involved for anyone to give a good answer. Feel free to throw any ideas at me though.


----------



## genofive0

Ben Ayr said:


> Thanks. I was trying to post a picture but it won't let you on your first five posts. This is the address but it filters it if I have the http or image tags on there.
> 
> i1095.photobucket.com/albums/i473/Ben_Ayers/image.jpg1.jpg
> 
> Last thing I did was spray foam, thus the mess.
> 
> I hear you on the headache part. Also understand if there are too many factors involved for anyone to give a good answer. Feel free to throw any ideas at me though.


Here is the picture posted for you  Honestly it does not look as bad as I imagined I would think that your goals could be achieved. The sky lights will for sure be a weak point for sound escaping.


----------



## Ben Ayr

Thanks for posting that. I should also mentioned I've partitioned a 5'x10' area for a bathroom by anchoring a 2x6 stud wall to the concrete pad. If all else fails I might be able to isolate this small area enough to work in. I still have an exterior wall there but I can afford to lose a little more space and put in hat channel with clips. There is still the question of whether the act of bending drywall over it will put too much stiffness in the clipped hat channel and prevent it from functioning as a spring. 

As far as the skylights go I'm curious if applying the VibraDamp pads that IsoStore sells for metal pipe might work to dampen some of the vibration in the pipe around where I've screwed into them and keep more of the sound from transferring into the woodwork... I may be misunderstanding some fundamental physics here though. If I had a do over I'd decouple them but I really don't want to rip those things out.


----------



## granroth

Ben Ayr said:


> Hi there,
> 
> I'm not building a home theater, but in the last few days that I've been researching soundproofing and noise treatment it seems like this forum has some of the most knowledgable people out there.
> 
> I have an unusual building I've been working on that is Quonset shaped (semi-circle) using 24" center bent steel pipe as studs/joists covered in corrugated sheet metal. I wasn't really thinking ahead to noise treatment or I would have done some things differently but now that I'm at this stage I've been trying to figure out what I can do.
> Was going to post a picture but apparently I can't on my first post.
> 
> I enclosed the end using an array of windows (3.2mm glass) framed in cedar. Obviously this is terrible for keeping sound out, but that's hindsight. There are also skylight boxes attached to the pipe at the top to let some light in so I guess sound will be flanking through those as well.The only real noise I'm interested in getting rid of is the road about 1/8 mile away that gets some loud trucks going down it.
> 
> I don't know if RC1 will be effective on the curve of the wall because I will have to bend gypsum board over it, probably compressing the springiness of it and not hanging well. I'm considering RC2 channel as furring but there don't appear to be any STC ratings on it. Alternatively I could run hat channel but I don't have the budget to outfit the whole space in sound clips so it would only be to add air/insulation space rather than decouple. So one of my questions would be, do you think that RC2 would outperform unclipped hat channel in any way? Would I achieve some small level of decoupling by using the RC2? I'm aware of the convoluted history of RC1 and its untested offspring.
> 
> The pipe "studs" only give me about an inch and a half, part of which is taken up by the spray foam. I could add a thin layer of fiberglass over that, then RC or hat channel for furring to give me another 1/2" or 7/8". Bend some gypsum onto it, leaving the option of going back and green gluing another thin sheet of gypsum as my budget allows.
> 
> Will any of this have any worthwhile effect or will the sound flanking through the front/skylights make it completely pointless? Not sure if it helps, but the front isn't facing the roadway and I live in a forested area.
> 
> Rather than attempting to decouple at all would I be better off putting my money into a damping compound and fastening the gypsum directly to the pipe?
> 
> Any insight or opinions welcome. I've been reading a good bit on your forum, but what I'm working with is a bit distant from a typical wood framed wall.
> 
> Thanks much.
> 
> Ben
> 
> Additional info: My goal would be to get this space quiet enough to record some music in. I could probably filter out the lower frequencies to a degree, but I'm worried about the road noise.


If I'm bluntly honest, this forum has a number of knowledgeable people but not very many true experts. I have done enough reading on soundproofing to know more than most people and can regurgitate well known and tested solutions, as well as extrapolate how well some closely related solutions might work... but I'm far from an expert. An expert is one that could come up with very specific and very unique solutions to non-standard cases, as well as have a much deeper understanding of "why" things work the way they work. There are a few experts still on AVS, but I've found that the majority tend to be on sites like GearSlutz (unfortunate name, but well stocked with acoustic experts).

That's my way of saying that your situation is absolutely unique and you'd be well served by hiring an expert to give you a solid plan. In particular, consider somebody like Rod Gervais.

But you wanted opinions so here's a few of mine 

RC2 isn't that far removed from RC1 from a soundproofing perspective. Both may work marginally better than directly attaching the drywall to a stud, but likely by not enough to make it worth doing. Since your building is insulated with spray foam, you might actually create a triple-leaf situation if you use any kind of hat channel. I'm not 100% sure of that, though.

In general, I never say that sound flanking will make other soundproofing measures completely pointless, because every little bit does help. What I do say is that flanking will absolutely reduce the expected performance of your other solutions and if those treatments are expensive, it might make them not work doing from a "bang for the buck" perspective.

Indeed, your bank of windows and skylights will produce a pretty substantial flanking opportunity for sound. Windows can work inside of studios and the like, but they usually are thicker than normal and are laminated. Windows that are energy efficient are not necessarily that good from a sound reduction perspective. For "normal" windows, your best bet is to usually find a way of covering them with more massive assemblies when you need the sound reduction.

In your case, it might be worthwhile to frame out a "room in a room" studio that is detached from the outside shell and can be designed to be soundproofed from the start. For instance, if you want a recording studio, then maybe just the actual recording booth needs to be properly treated while the mastering room could get away with a little more sound intrusion.

GearSlutz (really hate that name) is much more focused on studios than AVS, so again, that might be a good resource to check out. Check out the Studio Building Forum there.


----------



## Ben Ayr

granroth said:


> If I'm bluntly honest, this forum has a number of knowledgeable people but not very many true experts. I have done enough reading on soundproofing to know more than most people and can regurgitate well known and tested solutions, as well as extrapolate how well some closely related solutions might work... but I'm far from an expert. An expert is one that could come up with very specific and very unique solutions to non-standard cases, as well as have a much deeper understanding of "why" things work the way they work. There are a few experts still on AVS, but I've found that the majority tend to be on sites like GearSlutz (unfortunate name, but well stocked with acoustic experts).
> 
> That's my way of saying that your situation is absolutely unique and you'd be well served by hiring an expert to give you a solid plan. In particular, consider somebody like Rod Gervais.
> 
> But you wanted opinions so here's a few of mine
> 
> RC2 isn't that far removed from RC1 from a soundproofing perspective. Both may work marginally better than directly attaching the drywall to a stud, but likely by not enough to make it worth doing. Since your building is insulated with spray foam, you might actually create a triple-leaf situation if you use any kind of hat channel. I'm not 100% sure of that, though.
> 
> In general, I never say that sound flanking will make other soundproofing measures completely pointless, because every little bit does help. What I do say is that flanking will absolutely reduce the expected performance of your other solutions and if those treatments are expensive, it might make them not work doing from a "bang for the buck" perspective.
> 
> Indeed, your bank of windows and skylights will produce a pretty substantial flanking opportunity for sound. Windows can work inside of studios and the like, but they usually are thicker than normal and are laminated. Windows that are energy efficient are not necessarily that good from a sound reduction perspective. For "normal" windows, your best bet is to usually find a way of covering them with more massive assemblies when you need the sound reduction.
> 
> In your case, it might be worthwhile to frame out a "room in a room" studio that is detached from the outside shell and can be designed to be soundproofed from the start. For instance, if you want a recording studio, then maybe just the actual recording booth needs to be properly treated while the mastering room could get away with a little more sound intrusion.
> 
> GearSlutz (really hate that name) is much more focused on studios than AVS, so again, that might be a good resource to check out.


Thanks for your input. I'll see what I can do about plugging the windows and maybe check over on GearSlutz. (Yeah, terrible name.)I've read some of the stuff over there and it seems like they have some good people. On a different note, do you know if Ted White is still in the business? I read a lot of his old posts on this forum but trying to access his website (the sound company) gives me a 503. Maybe it's just temporarily down. He was the only one I saw selling the IB-1 clips and I was curious how they compare to RSIC-V.


----------



## granroth

Ben Ayr said:


> Thanks for your input. I'll see what I can do about plugging the windows and maybe check over on GearSlutz. (Yeah, terrible name.)I've read some of the stuff over there and it seems like they have some good people. On a different note, do you know if Ted White is still in the business? I read a lot of his old posts on this forum but trying to access his website (the sound company) gives me a 503. Maybe it's just temporarily down. He was the only one I saw selling the IB-1 clips and I was curious how they compare to RSIC-V.


Yeah, their site seems to be a bit flaky lately. I don't know what's going on with that.

I suggest calling on Monday. Both Ted and John are _far_ more responsive over the phone than they are over email. 1-800-397-8791


----------



## BasementBob

When
http://www.soundproofingcompany.com/
fails, try the older
http://www.greengluecompany.com/


----------



## granroth

BasementBob said:


> When
> http://www.soundproofingcompany.com/
> fails, try the older
> http://www.greengluecompany.com/


Hmm... I know Ted co-founded the Green Glue company but I didn't think he was with them anymore. Probably left when they sold it to Saint-Gobain?


----------



## jimim

granroth said:


> Yep, looks good. You can predict your performance by looking in the NRC IR-761 PDF for wall assembly TL-93-269 (2G16_WS90(406)_GFB90_AIR25_WS90(406)_GFB90_2G16) which is exactly your proposed wall if you have the studs 16" O.C. It achieves an STC 67 rating, which is excellent.
> 
> IR-761, btw, is here: NRC-CNRC IR-761 (PDF)


I was reading this over. How do you figure what ur soundproofing transmission level if ur walls are different. Like 2 of mine are staggered stuf. One is double stud and the other is a regular stud wall cause the other side is the outside concrete 12 inch pour. 

I'm all double 5/8 inside with green glue and outside is 1/2 single layer. 

So am I pretty much at 50 at least?


----------



## marlon1925

Finally started my dedicated HT project after more than a year of saving money.

I am from Butuan City, Philippines and my HT room is 23'L X 15'W X 9.8'H. It is located on the 2nd floor of the three-storey house extension being built.

I was reading some posts about soundproofing and acoustic treatment but unfortunately most of the materials are either not available here or too expensive. 

While browsing google I found this local company offering Polyurethane Insulation @ USD 18 per square meter (2 inches thick, still waiting for the quote for 4-inch thick). I also found a rock wool supplier. 

I hope I can get help from you guys as this will be my first project. I only learn about home theaters through this forum and I am very much thankful for those who contributed and shared their works here.

Any comment about this product?

Soundproofing for Your Home


After the application of Polyurethane Insulation, Is it okay to use ordinary plywood for my wall? Do I still need to install bass traps, etc?

Between the two options below which is better?

1. Rockwool, or
2. Polyurethane insulation

What difference will it make if I get 60kg density or 80kg density should I choose rock wool?

The more dense the better?


----------



## granroth

jimim said:


> I was reading this over. How do you figure what ur soundproofing transmission level if ur walls are different. Like 2 of mine are staggered stuf. One is double stud and the other is a regular stud wall cause the other side is the outside concrete 12 inch pour.
> 
> I'm all double 5/8 inside with green glue and outside is 1/2 single layer.
> 
> So am I pretty much at 50 at least?


Alas, soundproofing components aren't additive or subtractive like that. You can't really take a bunch of STC values and combine them into another overall value without testing the structure as a whole directly.

In your case, you will find that the effectiveness of your walls will depend on where your frame of reference is. Each of your walls will reduce the noise at a different level and so you'll hear sounds at different levels when you're on the opposite sides of each wall. Your ceiling, as a shared reference to all four walls, will have a huge impact on that as well, since sound can escape from there and travel to any direction where you are.

You _might_ be able to figure out your own STC rating of your space, in the direction that matters to you. Just play a pink noise and measure the frequency curve of that with the microphone placed by the tested wall inside of the room and then run the same test with the microphone outside of the wall. I believe you then compare the results to the published set of STC curves and the one that matches the closest is your STC rating.

I'll admit that I'm not 100% certain on that procedure since I haven't found many (or any) references to finding out your own STC ratings. It should be possible, though.


----------



## granroth

marlon1925 said:


> Finally started my dedicated HT project after more than a year of saving money.
> 
> I am from Butuan City, Philippines and my HT room is 23'L X 15'W X 9.8'H. It is located on the 2nd floor of the three-storey house extension being built.
> 
> I was reading some posts about soundproofing and acoustic treatment but unfortunately most of the materials are either not available here or too expensive.
> 
> While browsing google I found this local company offering Polyurethane Insulation @ USD 18 per square meter (2 inches thick, still waiting for the quote for 4-inch thick). I also found a rock wool supplier.
> 
> I hope I can get help from you guys as this will be my first project. I only learn about home theaters through this forum and I am very much thankful for those who contributed and shared their works here.
> 
> Any comment about this product?
> 
> Soundproofing for Your Home
> 
> 
> After the application of Polyurethane Insulation, Is it okay to use ordinary plywood for my wall? Do I still need to install bass traps, etc?
> 
> Between the two options below which is better?
> 
> 1. Rockwool, or
> 2. Polyurethane insulation
> 
> What difference will it make if I get 60kg density or 80kg density should I choose rock wool?
> 
> The more dense the better?


It's important to note the distinction between "soundproofing" and "acoustical treatments". While soundproofing is technically a type of acoustic treatments, the differences in how materials work for their intended purposes are enough that we think of them as completely separate fields.

I say this because bass traps are effective as an acoustic treatment, but do nothing worthwhile from a soundproofing perspective. Rock wool can be used as an absorption layer for soundproofing, but it's usually more cost effective to use standard fiberglass (if code allows). Density doesn't come into play with soundproofing, but can matter quite a bit for acoustic treatments.

Polyurethane is effective in the sense that it does a good job of sealing air leaks (one of the things that makes it so great for insulation), but it's absolutely not worth doing from a strictly soundproofing perspective. That is, if you need the insulation factor for heating/cooling, then absolutely use spray foam since it does a stellar job of that. But don't assume it'll provide anything useful for soundproofing. You can get the same level of air seal by just constructing the room with air infiltration in mind and liberally applying caulk, at a tiny fraction of the cost of spray foam.

The products used for soundproofing don't necessarily need to be that different or that different in price for different parts of the world. Forget about Green Glue or QuietGlue Pro or similar damping agents if they aren't available -- they are effective, but not strictly essential. Instead, focus on the triad of Decoupling, Mass, and Absorption.

You can Decouple without special materials by just building an inner "floating" wall separate from your external wall. You can add Mass by just adding more layers of whatever sheet material you use (still drywall/sheet rock/gypsum board?). Absorption can be either rock wool (if required) or plain fiberglass.

The first couple of posts in this thread have links that describe all of this. Just ignore any component that isn't available in your area and focus on the general techniques.


----------



## marlon1925

granroth said:


> It's important to note the distinction between "soundproofing" and "acoustical treatments". While soundproofing is technically a type of acoustic treatments, the differences in how materials work for their intended purposes are enough that we think of them as completely separate fields.
> 
> I say this because bass traps are effective as an acoustic treatment, but do nothing worthwhile from a soundproofing perspective. Rock wool can be used as an absorption layer for soundproofing, but it's usually more cost effective to use standard fiberglass (if code allows). Density doesn't come into play with soundproofing, but can matter quite a bit for acoustic treatments.
> 
> Polyurethane is effective in the sense that it does a good job of sealing air leaks (one of the things that makes it so great for insulation), but it's absolutely not worth doing from a strictly soundproofing perspective. That is, if you need the insulation factor for heating/cooling, then absolutely use spray foam since it does a stellar job of that. But don't assume it'll provide anything useful for soundproofing. You can get the same level of air seal by just constructing the room with air infiltration in mind and liberally applying caulk, at a tiny fraction of the cost of spray foam.
> 
> The products used for soundproofing don't necessarily need to be that different or that different in price for different parts of the world. Forget about Green Glue or QuietGlue Pro or similar damping agents if they aren't available -- they are effective, but not strictly essential. Instead, focus on the triad of Decoupling, Mass, and Absorption.
> 
> You can Decouple without special materials by just building an inner "floating" wall separate from your external wall. You can add Mass by just adding more layers of whatever sheet material you use (still drywall/sheet rock/gypsum board?). Absorption can be either rock wool (if required) or plain fiberglass.
> 
> The first couple of posts in this thread have links that describe all of this. Just ignore any component that isn't available in your area and focus on the general techniques.


Thanks a lot sir, that was fast! Appreciate it.

Among the choices to add mass, which one is most cost-effective sir?

I think I need to read more about decoupling 

Again, thanks a lot sir!


----------



## jimim

granroth said:


> Alas, soundproofing components aren't additive or subtractive like that. You can't really take a bunch of STC values and combine them into another overall value without testing the structure as a whole directly.
> 
> In your case, you will find that the effectiveness of your walls will depend on where your frame of reference is. Each of your walls will reduce the noise at a different level and so you'll hear sounds at different levels when you're on the opposite sides of each wall. Your ceiling, as a shared reference to all four walls, will have a huge impact on that as well, since sound can escape from there and travel to any direction where you are.
> 
> You _might_ be able to figure out your own STC rating of your space, in the direction that matters to you. Just play a pink noise and measure the frequency curve of that with the microphone placed by the tested wall inside of the room and then run the same test with the microphone outside of the wall. I believe you then compare the results to the published set of STC curves and the one that matches the closest is your STC rating.
> 
> I'll admit that I'm not 100% certain on that procedure since I haven't found many (or any) references to finding out your own STC ratings. It should be possible, though.


so does doing walls diff ways make things possible worse or broken? i mean all of our ceilings are diff than most of our walls if we ddin't use clip and channels all around for the walls like ceiling?

i'm starting to get freaked out by all this. maybe i should have done clips and channel all around vs staggered stud. 

jim


----------



## granroth

marlon1925 said:


> Among the choices to add mass, which one is most cost-effective sir?


Multiple layers of drywall (sometimes called sheet rock, plaster board, wallboard, or gypsum board). We use 5/8" drywall in the US, but it's almost surely going to be 16mm where you are.


----------



## granroth

jimim said:


> so does doing walls diff ways make things possible worse or broken? i mean all of our ceilings are diff than most of our walls if we ddin't use clip and channels all around for the walls like ceiling?
> 
> i'm starting to get freaked out by all this. maybe i should have done clips and channel all around vs staggered stud.


Oh, no, I'm not saying that having different wall construction makes things _worse_ -- I'm saying that it just makes it difficult to determine what your overall effectiveness really is.

Your ceiling _could_ be problematic if it's not decoupled and is attached to your otherwise decoupled walls. That would re-couple those walls to some extent and you'd absolutely have flanking issues.

I stress "could" because it's all going to be highly dependent on your personal needs. It sounds like you are done with the room construction. Are you happy with the results? Then who cares if it's not truly ideal. Do you have some specific requirements or concerns? The precise details absolutely matter, then.


----------



## jimim

granroth said:


> Oh, no, I'm not saying that having different wall construction makes things _worse_ -- I'm saying that it just makes it difficult to determine what your overall effectiveness really is.
> 
> Your ceiling _could_ be problematic if it's not decoupled and is attached to your otherwise decoupled walls. That would re-couple those walls to some extent and you'd absolutely have flanking issues.
> 
> I stress "could" because it's all going to be highly dependent on your personal needs. It sounds like you are done with the room construction. Are you happy with the results? Then who cares if it's not truly ideal. Do you have some specific requirements or concerns? The precise details absolutely matter, then.


no i don't know how it's going to be yet cause the door isn't on. i did everything the right way i guess. my walls are decoupled from the ceiling joist with the ib clips. my ceiling is also clips and channels off the joists. all my walls are doubled up with green glue and either double stud or stasggered like i said.im just worried when i add the door i'm going to be dissapointed. without the door on now i swear the foot falls from the first floor above which is carpet is more boomy. but again the door isnt on yet.

i made sure my 2 backer boxes on side walls are properly built. i addressed all outlet boxes with putty pads. i built joist mufflers in the joists for hvac. the hvac in the room is also in double drywalled soffits built after drywall.

jim


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## ronny31

I must be blind or something, but there is no mention of what in Norway is named "sponplate". In America it would be designated high density particle board as far as I can tell, we use HDF for shorthand in Norway to distinguish it from MDF even though its technically wrong. But we use very little of the actual HDF so its allowed here, no one here will confuse high density particle board for actual HDF if they say they are going to build with HDF. 
High density particle board (or lets call it HDP) has these specs: (well the floorboard versions we're interested in anyway) 22x620x2420mm and 700 kg/m³. So About 23.1kg a piece, 3.29 lbs per square foot (1.44 square meter a piece, some overlap due to the interconnecting shape). In Norway (the most expensive country in the world, just about), not counting VAT, its about 17.15 USD a piece, just over one USD per square foot. Should be cheaper in the US. 
Bending strength: 16 MPa (22mm)
Modulus (longitudinally): 2550 MPa
Heat-Conduction Ability: Lambda p = 0.12 W / mK
Transverse Tensile Strength: 0.4 Mpa 
We use it for everything, especially car stereos and enclosures in general. The stuff is so stiff that with glue and minimal amounts of extra reinforcement can get it similar to tapping concrete in hardness. If you tap it a clear high pitch sound is given (this is of course stopped by for example rockwool/glasswool, or acoustic mats). 
What do you think?


----------



## hendry98

I have couple of questions, and hopefully someone can help here.

1- is there a minimum fiberglass thickness to be used above the DD & GG in the ceiling? can i use double faced fiberglass insulation also?
2- is combining MDF 4/8 & Drywall 5/8 is good compared to double 5/8 Drywalls?
3- i am thinking of doing fiber optics starfield ceiling (where they cut small holes for the fiber optics), so does it impact the soundproofing? 

Thanks in advance


----------



## ronny31

hendry98 said:


> I have couple of questions, and hopefully someone can help here.
> 
> 1- is there a minimum fiberglass thickness to be used above the DD & GG in the ceiling? can i use double faced fiberglass insulation also?
> 2- is combining MDF 4/8 & Drywall 5/8 is good compared to double 5/8 Drywalls?
> 3- i am thinking of doing fiber optics starfield ceiling (where they cut small holes for the fiber optics), so does it impact the soundproofing?
> 
> Thanks in advance


3. yes this will cut down on the amount of soundproofing (presumably you can have more material without this in the way), but you don't have neighbors above you nor noisy cars. If you're out for maximum SPL you can't get away with this, but if you're OK with losing 0.1db to this go ahead. 
2. I'd look into HDP as described above, its not soft enough to bend according to the roof curvature but you can hang a billion pounds of drywall on it. I've been part of hanging three whole sheets of drywall and that's enough for me to never go near the stuff again, the other guys here will have to sell the benefits of drywall at all versus HDP. 
1. Depends, more is always better in terms of keeping sound inside and keeping outside sound outside. Even a sheet of paper on a concrete roof, will add something to the total db inside given a powerful enough stereo. But the power of the stereo decides how much is right. If you have the stereo, throw it in there and test it, that gives a nice eyeball mark for how much can be needed.


----------



## granroth

ronny31 said:


> I must be blind or something, but there is no mention of what in Norway is named "sponplate". In America it would be designated high density particle board as far as I can tell, we use HDF for shorthand in Norway to distinguish it from MDF even though its technically wrong. But we use very little of the actual HDF so its allowed here, no one here will confuse high density particle board for actual HDF if they say they are going to build with HDF.
> High density particle board (or lets call it HDP) has these specs: (well the floorboard versions we're interested in anyway) 22x620x2420mm and 700 kg/m³. So About 23.1kg a piece, 3.29 lbs per square foot (1.44 square meter a piece, some overlap due to the interconnecting shape). In Norway (the most expensive country in the world, just about), not counting VAT, its about 17.15 USD a piece, just over one USD per square foot. Should be cheaper in the US.
> Bending strength: 16 MPa (22mm)
> Modulus (longitudinally): 2550 MPa
> Heat-Conduction Ability: Lambda p = 0.12 W / mK
> Transverse Tensile Strength: 0.4 Mpa
> We use it for everything, especially car stereos and enclosures in general. The stuff is so stiff that with glue and minimal amounts of extra reinforcement can get it similar to tapping concrete in hardness. If you tap it a clear high pitch sound is given (this is of course stopped by for example rockwool/glasswool, or acoustic mats).
> What do you think?


Interesting. The issue may well be that it's so rare that I don't even know where I could get it, much less how much it would cost. Hardboard (high density fiberboard) is readily available, but it's typically limited to thicknesses of 1/8". I do have "particle board" on hand, but it's absolutely not as dense as drywall so I'm assuming that it's not high density.

I just did a search for "sponplate" and nope, I've never seen anything like that before. It does look pretty slick, though, and sounds like a great alternative to drywall, if it's available! 

Drywall is touted as the standard mostly due to its ubiquity and how inexpensive it is.


----------



## granroth

hendry98 said:


> 1- is there a minimum fiberglass thickness to be used above the DD & GG in the ceiling? can i use double faced fiberglass insulation also?


Not really. More is better than less, to a point. If I remember correctly, you get measurable improvement up to around 4" thickness and then there's just incremental small gains after that.

I'm not familiar with double-faced insulation. It shouldn't make a difference from a soundproofing perspective, in any event.



hendry98 said:


> 2- is combining MDF 4/8 & Drywall 5/8 is good compared to double 5/8 Drywalls?


3/4" MDF? That's give-or-take equivalent -- the double drywall case still has the edge, but I don't imagine it would be noticeable. 1/2" MDF is notably less dense.

MDF is a curious material to use on walls and ceilings. Is this for a soffit or similar?



hendry98 said:


> 3- i am thinking of doing fiber optics starfield ceiling (where they cut small holes for the fiber optics), so does it impact the soundproofing?


Yep. I'm not aware of any published data on just how much it would matter, though, so I can't say if it'd be notable or not.


----------



## ronny31

granroth said:


> Drywall is touted as the standard mostly due to its ubiquity and how inexpensive it is.


Probably. But Sanway amps are becoming ubiquitous as well, and they weren't.


----------



## granroth

ronny31 said:


> Probably. But Sanway amps are becoming ubiquitous as well, and they weren't.


Yeah, there are quite a few AV related components, materials, and techniques that were very common for awhile and then just drifted away... replaced by something new that worked better.

I'll be honest, that sponplate looks better than drywall in every way that matters to me. I would love to give it a try. Alas, I'm wondering if it even exists in the US, much less is readily available.


----------



## VolkerH.

I was going 'sponplate sponplate what does that remind me off' till it hit me. Spanplatte in German. It was more readily available from local wood shops and therefore my dads goto material. I can't tell if I ever saw this kind of particle board at Home Depot etc in the 13 years I live here. Or I saw it but just didn't think about it.


----------



## hendry98

granroth said:


> 3/4" MDF? That's give-or-take equivalent -- the double drywall case still has the edge, but I don't imagine it would be noticeable. 1/2" MDF is notably less dense.
> 
> MDF is a curious material to use on walls and ceilings. Is this for a soffit or similar?


I will not have soffit or something similar.

this is for my false ceiling actually, "MDF 0.5" + GG + Drywall 5/8"

i was planning to have 3/4" MDF, but it looks pretty hard to deal with in the ceiling. so we went with MDF 0.5" since we have around 25 sheets extra which we could use in my HT.

Do you think i would get similar results compared to DD? or at least closer to DD approach?


----------



## marlon1925

*LF: Staggered Studs*

Has anyone here tried installing Staggered Studs? Share link of build please


----------



## ronny31

marlon1925 said:


> Has anyone here tried installing Staggered Studs? Share link of build please


http://www.soundproofingcompany.com/soundproofing101/staggered-stud-wall-construction/

Don't know of any project threads, but there's definitely an effect. Though the effect is lessened by the fact that the studs still transmit vibrations at both ends into the wall, which transmits it to the other wall, even though both sides of the wall have their own studs. If there is a rubber mat between the end of each stud and the bottom and top, then the effect is much greater. Same goes if you add rubber to space the material you lay on the wall from the studs (this can lose some db over simply making a really strong wall, but its much quieter). There's also a greater effect if the space between each stud is halved over the example shown in the link, but this means the wall has to be pretty much twice as thick in order to fit any meaningful amount of rockwool/glasswool.


EDIT: Here's a list of all-wood types and their performances: 
http://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/3_Wood_Strength/3_Wood_Strength.htm 
It would be wonderful if we could fill in the prices per cubic foot or cubic meter of these things, then we could make a list of price/performance ratio of all the wood types, next to HDP and MDF and drywall etc. performance being how little noise they let through. How much is let through is decided by weight and specific hardness, and a tiny bit because of the bending strength. Specific hardness and weight is good for when db is to be contained (that's why DB drag cars are made from concrete), soft material with high weight is good for when you just care about the db escaping, but don't really care about maintaining high db, since some sound will get absorbed by the soft material.
PS: Don't know how accurate these numbers are, could be taken out of the air.


----------



## granroth

hendry98 said:


> I will not have soffit or something similar.
> 
> this is for my false ceiling actually, "MDF 0.5" + GG + Drywall 5/8"
> 
> i was planning to have 3/4" MDF, but it looks pretty hard to deal with in the ceiling. so we went with MDF 0.5" since we have around 25 sheets extra which we could use in my HT.
> 
> Do you think i would get similar results compared to DD? or at least closer to DD approach?


I actually measured some samples of sheet goods in this post: Thoughts on Mass. Extrapolating on those numbers, I'd guess that 1/2" MDF might have a density of about 1.7 lbs/sq ft. MDF is very slightly less dense than drywall, so your ceiling would be the rough equivalent to a 1/2" Drywall + 5/8" Drywall.

No, it won't give you the same performance. Mass does play a big role in soundproofing and having less has a direct impact on the abilities of the partition.

BUT!! Maybe it won't matter to you. Do you have a specific soundproofing goal that you are trying to hit? If you don't, then maybe you would be happy with a lessened solution, if only because you don't know what a more robust solution would sound like. Having a ceiling like yours absolutely will make a meaningful difference compared to not treating the ceiling at all. It may well be enough.

Just don't fall into the trap of thinking "I want to be able to play movies at reference level and not hear one peep out of it if I'm standing just outside the room." That ain't happening with your room. Think "I want to play movies pretty loud in my theater and have it not be quite so loud in the rest of the house" and yeah, you'll absolutely do that!


----------



## granroth

marlon1925 said:


> Has anyone here tried installing Staggered Studs? Share link of build please


If anybody does find one, then let me know since I haven't found any. As I mentioned in the "links" section of this thread, it seems that most people that have the space for staggered studs will go with a double wall and those that don't have the space go with clips and channel. Staggered studs is often the odd man out.



ronny31 said:


> http://www.soundproofingcompany.com/soundproofing101/staggered-stud-wall-construction/
> Don't know of any project threads, but there's definitely an effect. Though the effect is lessened by the fact that the studs still transmit vibrations at both ends into the wall, which transmits it to the other wall, even though both sides of the wall have their own studs. If there is a rubber mat between the end of each stud and the bottom and top, then the effect is much greater. Same goes if you add rubber to space the material you lay on the wall from the studs (this can lose some db over simply making a really strong wall, but its much quieter). There's also a greater effect if the space between each stud is halved over the example shown in the link, but this means the wall has to be pretty much twice as thick in order to fit any meaningful amount of rockwool/glasswool.


Do you have any data or research showing that rubber mats or pads will increase the effect of staggered stud walls? I've seen some suggestions that those do absolutely nothing and I'm wondering if that's just one of those AV myths that tend to stick around with no hard data to back them up, just because they "make sense". I'd love to see some proof that they really do work, though!



ronny31 said:


> EDIT: Here's a list of all-wood types and their performances:
> http://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/3_Wood_Strength/3_Wood_Strength.htm
> It would be wonderful if we could fill in the prices per cubic foot or cubic meter of these things, then we could make a list of price/performance ratio of all the wood types, next to HDP and MDF and drywall etc. performance being how little noise they let through. How much is let through is decided by weight and specific hardness, and a tiny bit because of the bending strength. Specific hardness and weight is good for when db is to be contained (that's why DB drag cars are made from concrete), soft material with high weight is good for when you just care about the db escaping, but don't really care about maintaining high db, since some sound will get absorbed by the soft material.
> PS: Don't know how accurate these numbers are, could be taken out of the air.


Hmm... I don't know how helpful that chart is for determining appropriateness for soundproofing materials. The factor that is most important by a huge margin is density, and density isn't even listed there. I haven't seen any evidence that hardness makes any meaningful difference for soundproofing. For instance, sand isn't hard at all, but it's extreme density (and viscous nature) makes it a wonderful soundproofing component. Various hardwoods have very high Janka ratings but they are typically pointless if you're trying to limit sound from entering or escaping a room.


----------



## ronny31

granroth said:


> Do you have any data or research showing that rubber mats or pads will increase the effect of staggered stud walls? I've seen some suggestions that those do absolutely nothing and I'm wondering if that's just one of those AV myths that tend to stick around with no hard data to back them up, just because they "make sense". I'd love to see some proof that they really do work, though!


Its used all the time in computers, servers and cars. Also lots of home stereo systems, by having rubber feet between the floor and the speakers, causing less vibration to propagate through the floor into stuff that can make audible vibrations. The engine in your car is kept separate from the chassis with rubber so that the chassis don't act like a tuning fork for the frequencies the engine create. In most buildings it is not used because most buildings don't have a car engine equivalent shaking things up, but with a single 12" Pioneer 1000W rms I managed to shake the walls sufficiently to make glass and dishes in the upstairs floor sound like Ace Ventura delivering a fragile package. Adding rubber between the floor, walls and roof wasn't an option, so I had to just add rubber under the subwoofer enclosure. 
Precisely how much effect there is, you'd have to dig up, I haven't found much. The effect is higher the more one face of the rubber can move in relation to the other side, so thick stubby bits is better than thin mats, tons of soft stubby bits is better than a few hard rubber bits, and so on. Optimum sound-proof room would give the same effect as having a room inside a room, floating in Zero G with no contact between the inside wall and the outside wall, with a vacuum in-between. We can't have vacuums unless at great cost so in our realistic version we'd have air between the layers, and also rubber bricks spaced out so that the weight of the room doesn't just squash the ones under the floor until the inside floor essentially transmits all its vibrations to the outside floor. This is achieved by having the weight of the roof taken by the outside roof through rubber bricks or elastic bands, the wall being held above the floor by the rubber in the wall, the floor being held by the bricks under the floor. Then you'd want to limit weight you put on that floor to maximize effect. The stronger the inside wall in this scenario is, the more db is contained in the desired location, and the more effective the acoustic separation and sound absorbing effect of the inside and outside wall, the more db is lost but not released into the next room. 



granroth said:


> Hmm... I don't know how helpful that chart is for determining appropriateness for soundproofing materials. The factor that is most important by a huge margin is density, and density isn't even listed there. I haven't seen any evidence that hardness makes any meaningful difference for soundproofing. For instance, sand isn't hard at all, but it's extreme density (and viscous nature) makes it a wonderful soundproofing component. Various hardwoods have very high Janka ratings but they are typically pointless if you're trying to limit sound from entering or escaping a room.


"Specific gravity — the weight of a volume of wood divided by the weight of the same volume of water."
Hardness reflects sound, keeping it in the theater, soft stuff absorbs sound, losing db but not adding echo. Basic DB drag 101 in acoustic physics. You want as much hardness as you possibly can, then for sound quality you want to add just enough absorbing surfaces for each of the frequencies. Adding more absorbing surfaces beyond that point essentially makes the theater into an open area with no walls, making it incredibly difficult to fill with sound.


----------



## Scott27

I'm in the process of designing a new home and have yet to start talking to the architect about sound proofing a room for home theatre use. My question is, if starting with a new build, what is the optimal way to sound proof walls and ceiling (will be single story residence)? Is a double stud wall with a floating ceiling what I should be aiming for?


----------



## cw5billwade

need more information like is the theater going to be on first floor 2nd floor or basement. A Room in a room is the best aproach if done properly.


----------



## ronny31

Scott27 said:


> I'm in the process of designing a new home and have yet to start talking to the architect about sound proofing a room for home theatre use. My question is, if starting with a new build, what is the optimal way to sound proof walls and ceiling (will be single story residence)? Is a double stud wall with a floating ceiling what I should be aiming for?


Have a chat with a guy who specifically designs sound-proof rooms. An architect isn't the right man for that bit of the job. I'd wager it involves some concrete walls and perhaps even concrete roof and then an appropriate amount of sound-absorbing material to avoid the sound bouncing around too much. Check with the architect whether what the sound-guy comes up with is up to code.

PS: as with most gardens in suburbia, don't have one if you possibly can. Fill it with house or at least make the house such that you can eventually fill the whole property with one building as much as possible (so you can build more house onto the house without the roof going the wrong way). When have you ever driven through a suburb and seen someone out in the front yard just having a BBQ or something? People have an innate resistance to being out in a front-yard because its so open towards people they don't really know. Better to have inside area, even inside gardens, or at least a backyard of reasonable size. But a backyard is either too cold or too warm, too dry or too wet, since no AC. 900 hours nouveau architecture course completed, congratulations.


----------



## btran33

Hi All:
I'm planing to add a dedicate home theater room in my basement and want to soundproof the room as much as possible (or in my case as much as the budget could allow!) Anyway, the basement currently has drop ceiling with R19 between joins. My question is should I keep the drop ceiling or install drywall ceiling with soundproofing clips? The reason I thought the drop ceiling would be good is that it is already "decoupling" from the joins and would be as good as soundproofing clips. What do you think?
Thank you,
Bao Tran


----------



## hendry98

granroth said:


> I actually measured some samples of sheet goods in this post: Thoughts on Mass. Extrapolating on those numbers, I'd guess that 1/2" MDF might have a density of about 1.7 lbs/sq ft. MDF is very slightly less dense than drywall, so your ceiling would be the rough equivalent to a 1/2" Drywall + 5/8" Drywall.
> 
> No, it won't give you the same performance. Mass does play a big role in soundproofing and having less has a direct impact on the abilities of the partition.
> 
> BUT!! Maybe it won't matter to you. Do you have a specific soundproofing goal that you are trying to hit? If you don't, then maybe you would be happy with a lessened solution, if only because you don't know what a more robust solution would sound like. Having a ceiling like yours absolutely will make a meaningful difference compared to not treating the ceiling at all. It may well be enough.
> 
> Just don't fall into the trap of thinking "I want to be able to play movies at reference level and not hear one peep out of it if I'm standing just outside the room." That ain't happening with your room. Think "I want to play movies pretty loud in my theater and have it not be quite so loud in the rest of the house" and yeah, you'll absolutely do that!


You are absolutely right, my target is not 100%, if i can reach 85%, then i am happy, and if it can stop the sound from getting in, then i will be more than happy. i am not pretty much concerned about sound going out. This room is in the third floor, surrounded with rooms like stores, my living room. and above me is the roof!

my targets:

1- minimize the sound coming from the roof like foot steps, or from wash machines .etc.
2- rigid ceiling and does not rattle at all!


initially, i had 1 layer of 0.5" drywall + RC & insulation, but it can rattle in certain frequencies which i could not accept.

so i went to re-do my ceiling with the new setup (mdf + drywall + GG), and 2" wooden frames + 3-4" insulation.


----------



## Scott27

cw5billwade said:


> need more information like is the theater going to be on first floor 2nd floor or basement. A Room in a room is the best aproach if done properly.


Its a single story residence, and we generally don't have basements in Australia, so there will be nothing above or below it.


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## marlon1925

*Staggered Studs Wall*



granroth said:


> If anybody does find one, then let me know since I haven't found any. As I mentioned in the "links" section of this thread, it seems that most people that have the space for staggered studs will go with a double wall and those that don't have the space go with clips and channel. Staggered studs is often the odd man out.
> 
> 
> 
> Do you have any data or research showing that rubber mats or pads will increase the effect of staggered stud walls? I've seen some suggestions that those do absolutely nothing and I'm wondering if that's just one of those AV myths that tend to stick around with no hard data to back them up, just because they "make sense". I'd love to see some proof that they really do work, though!
> 
> 
> 
> Hmm... I don't know how helpful that chart is for determining appropriateness for soundproofing materials. The factor that is most important by a huge margin is density, and density isn't even listed there. I haven't seen any evidence that hardness makes any meaningful difference for soundproofing. For instance, sand isn't hard at all, but it's extreme density (and viscous nature) makes it a wonderful soundproofing component. Various hardwoods have very high Janka ratings but they are typically pointless if you're trying to limit sound from entering or escaping a room.


Finally found a build using staggered studs wall Jijims Take 2! Build


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## granroth

ronny31 said:


> Its used all the time in computers, servers and cars. Also lots of home stereo systems, by having rubber feet between the floor and the speakers, causing less vibration to propagate through the floor into stuff that can make audible vibrations. The engine in your car is kept separate from the chassis with rubber so that the chassis don't act like a tuning fork for the frequencies the engine create. In most buildings it is not used because most buildings don't have a car engine equivalent shaking things up, but with a single 12" Pioneer 1000W rms I managed to shake the walls sufficiently to make glass and dishes in the upstairs floor sound like Ace Ventura delivering a fragile package. Adding rubber between the floor, walls and roof wasn't an option, so I had to just add rubber under the subwoofer enclosure.
> Precisely how much effect there is, you'd have to dig up, I haven't found much. The effect is higher the more one face of the rubber can move in relation to the other side, so thick stubby bits is better than thin mats, tons of soft stubby bits is better than a few hard rubber bits, and so on. Optimum sound-proof room would give the same effect as having a room inside a room, floating in Zero G with no contact between the inside wall and the outside wall, with a vacuum in-between. We can't have vacuums unless at great cost so in our realistic version we'd have air between the layers, and also rubber bricks spaced out so that the weight of the room doesn't just squash the ones under the floor until the inside floor essentially transmits all its vibrations to the outside floor. This is achieved by having the weight of the roof taken by the outside roof through rubber bricks or elastic bands, the wall being held above the floor by the rubber in the wall, the floor being held by the bricks under the floor. Then you'd want to limit weight you put on that floor to maximize effect. The stronger the inside wall in this scenario is, the more db is contained in the desired location, and the more effective the acoustic separation and sound absorbing effect of the inside and outside wall, the more db is lost but not released into the next room.


The issue I have with the suggestion that rubber will have any notable impact on transmission loss with regards to walls is that I've seen no indication that that is the case, yet have seen multiple references to how it is not the case. Yes, rubber is used very commonly and very effectively in smaller and far lighter entities. It is also often used as a membrane underneath plywood or similar to make a disconnected floating floor. It works in those cases.

But we're talking specifically about walls and while your suggestions sound like they could be true, I have never seen anything that indicates that they are. I would absolutely love if you had any evidence at all that rubber can work in that way effectively.



ronny31 said:


> "Specific gravity — the weight of a volume of wood divided by the weight of the same volume of water."
> Hardness reflects sound, keeping it in the theater, soft stuff absorbs sound, losing db but not adding echo. Basic DB drag 101 in acoustic physics. You want as much hardness as you possibly can, then for sound quality you want to add just enough absorbing surfaces for each of the frequencies. Adding more absorbing surfaces beyond that point essentially makes the theater into an open area with no walls, making it incredibly difficult to fill with sound.


Hard surfaces absolutely bounce back higher frequencies and so mitigating or controlling them is essential to having a great sounding room... but we're not talking about room acoustics so much as sound transmission loss and hardness plays a much smaller role in that case. For instance, say you had a room with walls made of 1/16" thick steel. The walls would be incredibly hard (much harder than any wood or normal sheet goods product) and the room would echo like crazy, but it would also leak noise like a sieve. All but the highest frequencies would just pass through like it wasn't there.

So it's not so much "hard vs soft" surfaces but "dense vs thin/light". The key for all soundproofing techniques is to reduce the energy of the sound waves (by converting them to heat) as much as possible. If the sound wave strikes a less-dense surface, even if it's very hard, then a significant amount of the energy of that wave will be in the surface, making it vibrate and pass along that wave to whatever is on the other side. If the surface is very dense, though, then it requires a LOT of energy to vibrate it and so quite a bit of the wave's energy is lost as heat.


----------



## BasementBob

granroth said:


> So it's not so much 'hard vs soft' surfaces but 'dense vs thin/light'. The key for all soundproofing techniques is to reduce the energy of the sound waves (by converting them to heat) as much as possible. If the sound wave strikes a less-dense surface, even if it's very hard, then a significant amount of the energy of that wave will be in the surface, making it vibrate and pass along that wave to whatever is on the other side. If the surface is very dense, though, then it requires a LOT of energy to vibrate it and so quite a bit of the wave's energy is lost as heat.


Replace 'dense' with 'massive' everywhere in that paragraph, and it would be correct.
A piece of paper is dense, about the same density of sheet of plywood -- but a piece of paper wouldn't stop much sound, whereas a more massive sheet of plywood would.
The rule is, as you know: doubling the mass of a wall gives an increase of 3-5 dB in STC.
Doubling the density while quartering the mass, would result in a soundproofing loss.


----------



## BasementBob

ronny31 said:


> Its used all the time in computers, servers and cars. Also lots of home stereo systems, by having rubber feet between the floor and the speakers, causing less vibration to propagate through the floor into stuff that can make audible vibrations. The engine in your car is kept separate from the chassis with rubber so that the chassis don't act like a tuning fork for the frequencies the engine create. In most buildings it is not used because most buildings don't have a car engine equivalent shaking things up, but with a single 12' Pioneer 1000W rms I managed to shake the walls sufficiently to make glass and dishes in the upstairs floor sound like Ace Ventura delivering a fragile package. Adding rubber between the floor, walls and roof wasn't an option, so I had to just add rubber under the subwoofer enclosure.


Any solution using rubber results in a mass-spring-mass (M-S-M) system, which has a resonance frequency.
Lots of machines vibrate within a higher frequency range, which is so far above M-S-M resonance that using rubber as a sound isolator is relatively easy.
Home theatres, especially those with sub 20hz subwoofers, tend to hit the frequencies which resonance would happen. The good news is that your house probably has a M-S-M of its own, and you might have lucked out with a M-S-M-S-M system that doesn't rattle the dishes.




ronny31 said:


> Optimum sound-proof room would give the same effect as having a room inside a room, floating in Zero G with no contact between the inside wall and the outside wall, with a vacuum in-between.


 
That might be doable. There's a very large all concrete room that they suck all the air out of for experiments -- including the famous feather and canon ball drop which did have both of them hit the floor at the same time. So you could do that as an outer shell. Then get someone from NASA (not the electric boat company because they're overqualified) to build you a metal shell that can handle 10000 foot pressure inside and vacuum outside, and a life support system {NC 5 system for air/O2/CO2, heat/cool for people/equipment, toilet}. Mount the NASA shell on magnetic levitation. Use fail safe vents on the outer structure to return the air pressure to normal in the event of a power failure. Movie goers would enter the NASA shell three hours before the movie to await the vacuum being generated, then the movie would start. I have no idea what that would cost -- but you could lean forward and complain to the front row people that their hearts were beating too loudly for you to enjoy the subtleties of the movie sound track.


----------



## ronny31

granroth said:


> For instance, say you had a room with walls made of 1/16" thick steel. The walls would be incredibly hard (much harder than any wood or normal sheet goods product) and the room would echo like crazy, but it would also leak noise like a sieve. All but the highest frequencies would just pass through like it wasn't there.


This is a fallacy. The weight of the proposed thickness steel is 2.55lbs per square foot and at that thickness have less bending strength than a HDP wall (I eyeball that it would at least). Therefore, it would almost certainly sound like a gong with the proposed steel, but this does not make the argument true. 

The goal of a good room for a stereo or surround system is maximum sound levels for maximum headroom in all frequencies. To reach this prerequisite the room pretty much has to be a concrete bunker with no sound being absorbed by the walls, but instead reflected by the walls. No energy given to the speakers should escape the room. 
Then the second prerequisite is that the room is acoustically good, so its possible to EQ a stereo to get a flat response with the desired low levels of echo across the spectrum. To do this you add acoustic elements like bass traps, sound absorbing materials and sound diffusers. In the appropriate amount and configuration so as to get an acoustic masterpiece. 
If you try to do it differently, and instead incorporate sound-absorbing elements in the wall, ceiling and floor design itself, for example in the form of soft walls with sand. Then you will have parts of your acoustic list of features, which you can't change later. If you happen to have a large dip in db on a particular frequency band because too much db is absorbed by the walls, floor and ceiling, then you can't remove absorbing materials and gain db in that frequency spectrum. You're stuck trying to correct it with having more headroom from the sound system in that exact frequency band.


----------



## granroth

ronny31 said:


> This is a fallacy. The weight of the proposed thickness steel is 2.55lbs per square foot and at that thickness have less bending strength than a HDP wall (I eyeball that it would at least). Therefore, it would almost certainly sound like a gong with the proposed steel, but this does not make the argument true.
> 
> The goal of a good room for a stereo or surround system is maximum sound levels for maximum headroom in all frequencies. To reach this prerequisite the room pretty much has to be a concrete bunker with no sound being absorbed by the walls, but instead reflected by the walls. No energy given to the speakers should escape the room.
> Then the second prerequisite is that the room is acoustically good, so its possible to EQ a stereo to get a flat response with the desired low levels of echo across the spectrum. To do this you add acoustic elements like bass traps, sound absorbing materials and sound diffusers. In the appropriate amount and configuration so as to get an acoustic masterpiece.
> If you try to do it differently, and instead incorporate sound-absorbing elements in the wall, ceiling and floor design itself, for example in the form of soft walls with sand. Then you will have parts of your acoustic list of features, which you can't change later. If you happen to have a large dip in db on a particular frequency band because too much db is absorbed by the walls, floor and ceiling, then you can't remove absorbing materials and gain db in that frequency spectrum. You're stuck trying to correct it with having more headroom from the sound system in that exact frequency band.


Well sure, but now we're talking about two completely different things. You are referring to acoustic treatments to make the room sound better; I'm referring to soundproofing components to maximize sound transmission loss between the inside and outside of the theater. Those are two completely different goals with completely different treatments. It's why there are separate Soundproofing Master Threads and Acoustical Treatments Master Threads


----------



## ronny31

granroth said:


> Well sure, but now we're talking about two completely different things. You are referring to acoustic treatments to make the room sound better; I'm referring to soundproofing components to maximize sound transmission loss between the inside and outside of the theater. Those are two completely different goals with completely different treatments. It's why there are separate Soundproofing Master Threads and Acoustical Treatments Master Threads


I do not see how this is two different things. By keeping every single db inside the room you by definition keep it from going to the next room, and vice versa. Only if you obtain this goal by stacking sandbags behind some mdf then you stop the db in the middle of the wall instead of inside the home cinema. Then you need a bigger more expensive home cinema, and more sound deadening to keep the noise in, and so forth. The sound-deadening thread could be a how-to build a 4 inch fiberglass reinforced concrete wall, ceiling and floor. Because absorbing the sound with drywall or even HDP would be considered an acoustic treatment.


----------



## cgott42

Q - My HT is located in the basement below the dining room of the first floor (which is adjacent to the kitchen and front entrance).
My HT room is fully decoupled + DW+GW+DW. It does a great job of sound containment with all but the "good" LFE scenes played at reference level. Particularly it gives some rumble to the dining room and areas mentioned above. (so my current solution is to lower the sub level during hours people are in these rooms). My wife is looking to redo the dining room floor, so I was thinking about using this as an opportunity to get rid of that rumbling.
i.e. the plan was to buy click together bamboo flooring (like this) directly on top of the existing hardwood floor. However for Sound Containment, I was thinking of the following options, and wondering your thoughts on comparatively, and absolutely how much each would help the LFE containment :


simply putting green glue between the new floor and the existing hardwood floor
putting GG + a 3/8" layer (5/8" if I can fit it) of DW under the existing hardwood floor
cutting some holes (strips) in the existing hardwood + subflooring to get to the ceiling of the HT, and stuffing more pink fluffy insulation in it (as currently the cavity of the ceiling which I'm guessing is 9-12" deep, has about 3" of insulation (maybe 6", I may have stuffed the additional r13 batt in (but in some places I needed to compress it to fit , due to cross supports in the cavity ) - Obviously this would add complexity to the project, so I'd like to avoid, but it the gap at the top of the cavity is creating a big problem, and is necessary to fix, I can do it.
What do you think?


----------



## ronny31

Depends on where the bass is coming through. If its the floor then for bass stopping I'd consider some polished slate stone with electric heating cables (marvelous to walk on). But it can also be that the wall transmits sound from the first floor to the second floor, so a slate floor could not give much of an effect without adding to the walls. But at this point its going to perhaps be easier and cheaper to redo the cinema room walls and ceiling. Please do some checking to figure out the direction the bass is taking. Are the enclosures vibrating, transmitting vibrations to the floor? Then making more solid (massive) enclosures could be warranted. Or is the bass purely vibrating the walls and ceiling in the cinema? If so the walls and ceiling might need more mass and/or less give when you push against it (for stopping bass the wall should ring like a bell if a sound is given at all, if you hit it, not sound like a gong). 
To give more accurate help, figure this out: If you put your ear on the bottom of a glass and rest it towards the surfaces in your cinema and upstairs what place has the most sound? Draw the room and mark down perceived sound levels from 1 to 5 in the different locations.


----------



## granroth

cgott42 said:


> Q - My HT is located in the basement below the dining room of the first floor (which is adjacent to the kitchen and front entrance).
> My HT room is fully decoupled + DW+GW+DW. It does a great job of sound containment with all but the "good" LFE scenes played at reference level. Particularly it gives some rumble to the dining room and areas mentioned above. (so my current solution is to lower the sub level during hours people are in these rooms). My wife is looking to redo the dining room floor, so I was thinking about using this as an opportunity to get rid of that rumbling.
> i.e. the plan was to buy click together bamboo flooring (like this) directly on top of the existing hardwood floor. However for Sound Containment, I was thinking of the following options, and wondering your thoughts on comparatively, and absolutely how much each would help the LFE containment :
> 
> 
> simply putting green glue between the new floor and the existing hardwood floor
> putting GG + a 3/8" layer (5/8" if I can fit it) of DW under the existing hardwood floor
> cutting some holes (strips) in the existing hardwood + subflooring to get to the ceiling of the HT, and stuffing more pink fluffy insulation in it (as currently the cavity of the ceiling which I'm guessing is 9-12" deep, has about 3" of insulation (maybe 6", I may have stuffed the additional r13 batt in (but in some places I needed to compress it to fit , due to cross supports in the cavity ) - Obviously this would add complexity to the project, so I'd like to avoid, but it the gap at the top of the cavity is creating a big problem, and is necessary to fix, I can do it.
> What do you think?


Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.

In general, the more mass, damping, and space you can add, the better it'll be. Can you add a 6ft concrete ceiling? That would work. No? What, are you not committed to this?!

Kidding, of course...  If you're not developing a commercial studio or theater, then bass reduction will always be a compromise and trying to get "good enough"

So with that in mind:

1. Putting green glue between the new floor would help (more damping in addition to the new mass); GG tends to amplify the effects of the additional mass. Bamboo flooring doesn't have a significant amount of mass, though, so I'm not sure how much it'd help overall. I love bamboo flooring, btw (installed it in my house) but not necessarily from a soundproofing perspective.

2. Instead of drywall, consider putting cement board, like you might put under tile. A 1/2" sheet of cement board (like DUROCK) has about 3lbs / sq ft, which is quite a bit more than even 5/8" drywall. It is harder to work with, though.

3. Adding more insulation may not help enough to matter. There's a steep cut-off in effectiveness after about 3 or 4 inches. Still, there are some improvements and it does have the effect of "widening" the space, which should help with bass. I just don't know that it would be worth the extra effort.


----------



## cgott42

granroth said:


> Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.
> 
> In general, the more mass, damping, and space you can add, the better it'll be. Can you add a 6ft concrete ceiling? That would work. No? What, are you not committed to this?!
> 
> Kidding, of course...  If you're not developing a commercial studio or theater, then bass reduction will always be a compromise and trying to get "good enough"
> 
> So with that in mind:
> 
> 1. Putting green glue between the new floor would help (more damping in addition to the new mass); GG tends to amplify the effects of the additional mass. Bamboo flooring doesn't have a significant amount of mass, though, so I'm not sure how much it'd help overall. I love bamboo flooring, btw (installed it in my house) but not necessarily from a soundproofing perspective.
> 
> 2. Instead of drywall, consider putting cement board, like you might put under tile. A 1/2" sheet of cement board (like DUROCK) has about 3lbs / sq ft, which is quite a bit more than even 5/8" drywall. It is harder to work with, though.
> 
> 3. Adding more insulation may not help enough to matter. There's a steep cut-off in effectiveness after about 3 or 4 inches. Still, there are some improvements and it does have the effect of "widening" the space, which should help with bass. I just don't know that it would be worth the extra effort.



Thanks, looks like I'll try to add concrete board - and not add the insulation (glad - wasn't looking forward to cutting the subfloor) - note all LFE that comes through - only comes through directly above the HT room, and not that much, so I'm hoping this will take it the extra yard.
2 Q's:
(a) Do I add GG to the Concrete board
(b) with the concrete board it will make the floor level above the bottom of the front door (hallway adjacent to dining room is front entrance). In addition, if I do these areas, it'll be a good 2" above the current hardwood in the rest of the first floor (which doesn't need to be replaced) - any ideas ?


----------



## granroth

cgott42 said:


> Thanks, looks like I'll try to add concrete board - and not add the insulation (glad - wasn't looking forward to cutting the subfloor) - note all LFE that comes through - only comes through directly above the HT room, and not that much, so I'm hoping this will take it the extra yard.
> 2 Q's:
> (a) Do I add GG to the Concrete board
> (b) with the concrete board it will make the floor level above the bottom of the front door (hallway adjacent to dining room is front entrance). In addition, if I do these areas, it'll be a good 2" above the current hardwood in the rest of the first floor (which doesn't need to be replaced) - any ideas ?


GG works best between two surfaces that are the same, but it still works well with dissimilar surfaces. If you got the GG from Ted, then your best is to call him for his opinion. GG is used frequently between OSB and drywall so it make sense to me that it'd be at least as effective between plywood and concrete board.

In houses that I've been in with offset floor heights, they tended to use a transition strip that eases the edge and then cut the door down so that it clears the higher floor.

I'm going to have a higher floor in a future home improvement and my plan is to just chamfer the higher flooring over several inches to ease it down to the same height as the lower one. I haven't done it yet, though, so I can't comment on how effective it'll be


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## VolkerH.

So I think I got my route planned for my room in the basement (10'x14'x8'), double 5/8"DW with GG on ceiling. Double 2x4 walls on 2 sides with single 5/8" DW on the inside and outside. The other 2 sides are outside walls (concrete) that are already covered with a single layer DW. 
But what just dawned on me, once I have the door in, and a heavy curtain in front, I will have likely not much of an air movement. The room had no AC/heat, it was open on 1 side and had a folding door with slots on the other. So far even in the winter time it wasn't to bad there and blankets worked so I wasn't thinking about heating. Though I have a little heater I can plug in. If the projector isn't heating enough already  The rack is outside the room. For cooling I would have put in my Dyson fan who would be very quiet on low setting. 
But all that would not help with fresh air. 
While I likely wouldn't suffocate during a 2 hour movie, I'm wondering how bad the air gets with 4 people watching a 2 hour race ? 
Did I just plan to seal my room pretty tight and now I have to punch vents in it ?


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## ronny31

granroth said:


> Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.


Well, yes, and no. Just adding hanging mass with no structural strength would be a very difficult way of keeping low frequency db inside a room. I think the most helpful article I can link to is this: 
http://en.wikipedia.org/wiki/Sound_transmission_class 
At the bottom there is a list of typical wall options and their STC. 
This pdf also has some options and their measured STC: http://www.vibrationdata.com/tutorials/RD066.pdf 



VolkerH. said:


> So I think I got my route planned for my room in the basement (10'x14'x8'), double 5/8"DW with GG on ceiling. Double 2x4 walls on 2 sides with single 5/8" DW on the inside and outside. The other 2 sides are outside walls (concrete) that are already covered with a single layer DW.
> But what just dawned on me, once I have the door in, and a heavy curtain in front, I will have likely not much of an air movement. The room had no AC/heat, it was open on 1 side and had a folding door with slots on the other. So far even in the winter time it wasn't to bad there and blankets worked so I wasn't thinking about heating. Though I have a little heater I can plug in. If the projector isn't heating enough already  The rack is outside the room. For cooling I would have put in my Dyson fan who would be very quiet on low setting.
> But all that would not help with fresh air.
> While I likely wouldn't suffocate during a 2 hour movie, I'm wondering how bad the air gets with 4 people watching a 2 hour race ?
> Did I just plan to seal my room pretty tight and now I have to punch vents in it ?


I have tried (not very hard) to find vents that allow keeping db inside and then being able to provide fresh air occasionally, but I haven't found any. Just the regular plastic stuff that leak db like a hole in the wall. If you try to keep the noise from the rest of the house, more so than the neighbors, then just having vents out of the house would be preferable to having vents into the other rooms. Vents to the outside have to be high up (presumably the air outside is cooler and falls down to the floor then, pushing warm air out, like a room being filled with water).


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## granroth

ronny31 said:


> Well, yes, and no. Just adding hanging mass with no structural strength would be a very difficult way of keeping low frequency db inside a room. I think the most helpful article I can link to is this:
> http://en.wikipedia.org/wiki/Sound_transmission_class
> At the bottom there is a list of typical wall options and their STC.
> This pdf also has some options and their measured STC: http://www.vibrationdata.com/tutorials/RD066.pdf


No.

STC is a pointless rating when it comes to LFE since it starts at 125Hz and LFE is defined as being from 20Hz to 120Hz. There is no overlap between STC and LFE at all. Therefore, the STC rating of a wall or ceiling tells you _nothing_ of the ability to stop the transmission of bass.

STC can still be a decent measure of the soundproofing capacity of a wall in the sense that there are no other single number standards that are commonly communicated. If you want the canonical list of those values for the biggest arrays of wall construction types, then it's best to go to the source and just download the pdf for IR-761 done by the NRC-CNRC. Link is in the second post in this thread.

Also, no, when soundproofing you are not _primarily_ trying to keep sound "inside" of the room. What you are mostly doing is converting the sound energy into heat inside of the partition. Yes, some of the sound waves will be reflected back and anything reflected back is, by definition, not leaving the room... but that's only a small percentage of the total sound energy. The vast majority is dissipated in the wall/ceiling itself.


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## granroth

VolkerH. said:


> But all that would not help with fresh air.
> While I likely wouldn't suffocate during a 2 hour movie, I'm wondering how bad the air gets with 4 people watching a 2 hour race ?
> Did I just plan to seal my room pretty tight and now I have to punch vents in it ?


If the room is sealed tight, then yeah, it'll start getting "stuffy" feeling in the room during long movies. It won't be anywhere near bad enough to suffocate you or anything even close to that, but it likely will be noticeable, especially since that's a relatively small room.

Definitely don't just punch vents in it, though!! You have a couple of options:

If you don't want to do any kind of construction, then consider the very low-tech option and just have an intermission in any multi-hour movie or show and open the door to air out the room. 

If you are willing to do some construction, then the canonical solution for this is a "dead vent". This is pretty commonly done. Details here: http://www.soundproofingcompany.com/soundproofing101/the-dead-vent/

Basically, you are "punching a vent" through the wall, but it's done in such a way that sound cannot bypass your existing soundproofing efforts. You get the fresh air without the reduction in sound transmission loss.


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## ronny31

granroth said:


> No.
> 
> STC is a pointless rating when it comes to LFE since it starts at 125Hz and LFE is defined as being from 20Hz to 120Hz. There is no overlap between STC and LFE at all. Therefore, the STC rating of a wall or ceiling tells you _nothing_ of the ability to stop the transmission of bass.


http://www.acoustiblok.com/PDF/Acoustiblok-Sound-Reduction-Wall-Assemblies.pdf
Page 15, 8 inch concrete block with standard wall on both sides. About twice as good at stopping bass than all the non-concrete stuff in IR-761 (the best bass transmission design in IR-761 is 25db I think, spent 20 minutes scrolling through to see if I found out what was best in that regard but got bored). 
When DB drag car builders make panels to stop bass transmission they hammer on it with something, then if they hear something they reinforce it. Then they repeat until they no longer manage to transmit any bass through it. And what they always end up with is a concrete panel. You need concrete to stop bass. To stop bass without concrete you'll need half spacing studs and double 22mm high density variable particle size particle board akin to the stuff Scandinavians use for floors. And even then concrete is much better. Even just thin fiber reinforced poured concrete and then a normal wall at both sides (with some rockwool or something to stop high frequencies). Am I the first on this forum to advocate the use of concrete to stop bass transmission or something? With the amount of resistance and general lack of response to my points in favor to responding to the next guy who mentions drywall, I'd certainly think so. 

EDIT: Come to think of it, why should I argue otherwise? Maybe I'll just let you be happy with drywall combos in respect to bass transmission. Then I won't come across as an a-hole in my effort to argue otherwise.


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## granroth

ronny31 said:


> http://www.acoustiblok.com/PDF/Acoustiblok-Sound-Reduction-Wall-Assemblies.pdf
> Page 15, 8 inch concrete block with standard wall on both sides. About twice as good at stopping bass than all the non-concrete stuff in IR-761 (the best bass transmission design in IR-761 is 25db I think, spent 20 minutes scrolling through to see if I found out what was best in that regard but got bored).
> When DB drag car builders make panels to stop bass transmission they hammer on it with something, then if they hear something they reinforce it. Then they repeat until they no longer manage to transmit any bass through it. And what they always end up with is a concrete panel. You need concrete to stop bass. To stop bass without concrete you'll need half spacing studs and double 22mm high density variable particle size particle board akin to the stuff Scandinavians use for floors. And even then concrete is much better. Even just thin fiber reinforced poured concrete and then a normal wall at both sides (with some rockwool or something to stop high frequencies). Am I the first on this forum to advocate the use of concrete to stop bass transmission or something? With the amount of resistance and general lack of response to my points in favor to responding to the next guy who mentions drywall, I'd certainly think so.
> 
> EDIT: Come to think of it, why should I argue otherwise? Maybe I'll just let you be happy with drywall combos in respect to bass transmission. Then I won't come across as an a-hole in my effort to argue otherwise.


Any resistance you are getting is mostly because your responses are a curious mix of being very helpful; somewhat misleading; or outright wrong. You clearly think you know a lot about soundproofing, but it seems like a lot of your background info is either wrong or is right but in ways that you don't understand.

This response is an example of where you start off 100% right and but then start subtly veering off.

First, you are 100% correct that concrete is a fantastic way to stop bass! I've never heard anybody say otherwise. As I mentioned earlier, stopping bass means tons of mass, plus ideally damping and space. Concrete works so well with bass because it is very dense and so has a ton of mass for the amount of space it occupies. There are elements that are even better (lead and sand, for two quick examples) but all other alternatives are either prohibitively expensive or are difficult to work with in a construction capacity. So concrete is king when it comes to bass.

So why isn't it concrete block recommended more often around here? Because this is a primarily US-central forum and concrete block is relatively uncommon in homes here. Most homes in the US are "stick" homes, made with 2x construction. Drywall is recommended so pervasively because it gives a reasonable amount of mass for relatively low cost.

Yes, it certainly sounds like the sponplat (high density panels) would be even better. I'd love to try the stuff myself. As far as I know, it doesn't exist in the US. Until it does, drywall is the best _compromise_ (performance for price + availability + workability).

Now, there is arguably an even better solution than drywall for bass that is still doable and that's concrete backer board. I suggested that in a previous post. The problem with concrete backer board is that it's notably harder to work with than drywall and is about double the cost.

But I want to quibble with your response, nonetheless, because you are pointing to a bunch of wall assemblies that do work well with bass and are implying that their STC rating has something to do with that. It doesn't. Even with those examples (several of which are IR-761 assemblies, btw), you can clearly see that the STC value has little to no relation to the wall's performance under 125Hz. Also, you mention "half spacing studs"... I'm not 100% certain what you mean by that. If you mean just spacing them closer together (8" spacing, perhaps) then no, that won't help from a soundproofing perspective. If anything, that would make things worse, since you are now doubling the amount of transmission paths for the sound waves to travel on. Halving the number of studs (going to 24" O.C., if code allows) does work, since it reduces the number of pathways.


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## ronny31

granroth said:


> Any resistance you are getting is mostly because your responses are a curious mix of being very helpful; somewhat misleading; or outright wrong. You clearly think you know a lot about soundproofing, but it seems like a lot of your background info is either wrong or is right but in ways that you don't understand.
> 
> This response is an example of where you start off 100% right and but then start subtly veering off.
> 
> First, you are 100% correct that concrete is a fantastic way to stop bass! I've never heard anybody say otherwise. As I mentioned earlier, stopping bass means tons of mass, plus ideally damping and space. Concrete works so well with bass because it is very dense and so has a ton of mass for the amount of space it occupies. There are elements that are even better (lead and sand, for two quick examples) but all other alternatives are either prohibitively expensive or are difficult to work with in a construction capacity. So concrete is king when it comes to bass.
> 
> So why isn't it concrete block recommended more often around here? Because this is a primarily US-central forum and concrete block is relatively uncommon in homes here. Most homes in the US are "stick" homes, made with 2x construction. Drywall is recommended so pervasively because it gives a reasonable amount of mass for relatively low cost.
> 
> Yes, it certainly sounds like the sponplat (high density panels) would be even better. I'd love to try the stuff myself. As far as I know, it doesn't exist in the US. Until it does, drywall is the best _compromise_ (performance for price + availability + workability).
> 
> Now, there is arguably an even better solution than drywall for bass that is still doable and that's concrete backer board. I suggested that in a previous post. The problem with concrete backer board is that it's notably harder to work with than drywall and is about double the cost.
> 
> But I want to quibble with your response, nonetheless, because you are pointing to a bunch of wall assemblies that do work well with bass and are implying that their STC rating has something to do with that. It doesn't. Even with those examples (several of which are IR-761 assemblies, btw), you can clearly see that the STC value has little to no relation to the wall's performance under 125Hz. Also, you mention "half spacing studs"... I'm not 100% certain what you mean by that. If you mean just spacing them closer together (8" spacing, perhaps) then no, that won't help from a soundproofing perspective. If anything, that would make things worse, since you are now doubling the amount of transmission paths for the sound waves to travel on. Halving the number of studs (going to 24" O.C., if code allows) does work, since it reduces the number of pathways.


I have no idea how to argue this in the most efficient way possible, I just throw spaghetti at the concrete wall as I invent arguments. I'll try again. Lets involve some good old basic physics. 
When the subwoofer element moves in and out the air pressure differences from 120db are tiny across a square inch. Its 20 Pa, or 0.00290075475 pounds per square inch. But across an entire drywall in the bits between each stud it adds up to meaningful numbers. 120db on a 24 by 108 inch section experiences 7.5 pounds in air pressure difference (either from peak to bottom spread across the surface or peak to centerline and then another 7.5 pounds to the bottom, I'm not sure which, I wager its the first). If its 20hz then this pressure difference gets time to act for 1/40th of a second outwards, and 1/40th of a second inward (not going into the whole thing about how it experiences lower average pressure because its a sine wave etc). The higher you go up in frequency the less time this pressure difference has time to act on the surface. Experiencing less actual movement as you go up in frequency. The excursion of the speaker elements also go down as you increase frequency, so largely the movement of the walls go down as you increase in frequency because the time the pressure difference has to act on the wall in each wave goes down. Thus lowering the amount of movement actually imparted on the wall. Total PSI the wall experiences can go up though in higher frequencies, due to the speaker being able to move more air combined per second, reaching higher db. 

Then we begin going into areas where the materials themselves can transmit vibrations internally which for low frequencies largely does not matter. Whereas on high frequencies you can tap a railroad piece and hear the noise far away by putting your ear to the steel, you can't do this with lower frequencies. Partly because we're terrible at hearing low frequencies but partly because materials only want to transmit certain frequencies in this way. 
This pressure difference over time and area is the reason you see largely no decrease in low frequency sound transmission by adding more and more drywall layers and rockwool/glasswool. It may be more weight, but the PSI is still the same across the same area with the same spacing between studs. That is why I suggest half space studs, which simply is to have half the spacing between studs. In regards to bass transmission, its guaranteed to lower it. Then the same 120db is just 3.75 pounds on a given surface that can move much less (movement of panel with smallest side being 24 inches can move much more than panel with shortest side being 12 inches, measured in air displaced by movement, given the proportionally halved force. You can test it by putting X weight on a 2 by 4 and then cutting it and the weight in half and measuring how much it deflects each time). Higher frequencies will probably be affected negatively by half space studs, but high frequencies can be dealt with with drywall and insulation. 
But, how much does concrete get affected by pressure differences in the air? Very little. We know that with even very thin concrete, the wall can take the given PSI over 1/40th of a second with an immeasurable amount of movement because the give in the wall is simply much less than the given PSI will impart, no matter how long the PSI is given to act upon the wall. You can push against a drywall for a second and then impart pretty much the maximum amount of movement it will take without breaking, whereas if you lean towards a concrete wall the amount it will move is much much much smaller. So even if you have 1 hertz with 100 pounds of pressure differences peak to peak across the entire concrete wall, it will still move immeasurably small amounts. However, if you have 400 hertz and 120db, you'll begin throwing a lot of sound through the concrete, since you're nearing the frequencies the concrete can transmit well internally. 
Hence I put forth the STC rating of assemblies that included concrete because we know the bass transmission is better with concrete than without it. There's a reason things that don't move are said to be "set in stone/concrete". 

*(number from random guy on internet says 120db is 20 Pa, sue him if it isn't correct)

Excuse me for not having a degree in efficient arguing about the sound dampening effect of concrete on the internet.

EDIT: Let me flesh out that bit about the 24 inch side versus 12 inch side movement amount. Lets have a 12 by 12 inch wall section and a 24 by 24 inch. There's studs at all sides, and drywall on both sides. When a certain psi is allowed to act on the wall on one side, it imparts motion in the wall, displacing an amount of air, which pushes against the other drywall sheet. The movement is proportional to the give in the sheet, and the give is lowered by reducing the dimensions of the sheets. Thus, less volume of air is moved, less movement is imparted on the next wall. The amount of air displaced in section 24x24 is more than four times as large as the amount of air displaced in section 12x12. Note the "more than". 4 sections of 12x12 would have less surface movement combined than one 24x24 sheet. The reason being the movement imparted by air pressure on a sheet wants to resemble a part of a sphere, and they have more volume to surface area the bigger the sphere is. Impart 1x force on 24x24 area and you get a displacement volume well over 4 times the displacement volume of an area of 12x12 being subjected to x/4 force. So even disregarding the fact that materials themselves tend to move less with lower lengths, its going to move less air if we cut the size of the sheet sections. Not to mention, you'll have some more parts of the wall that has studs behind it, where it won't move at all, only imparting sound internally.


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## cgott42

granroth said:


> GG works best between two surfaces that are the same, but it still works well with dissimilar surfaces. If you got the GG from Ted, then your best is to call him for his opinion. GG is used frequently between OSB and drywall so it make sense to me that it'd be at least as effective between plywood and concrete board.
> 
> In houses that I've been in with offset floor heights, they tended to use a transition strip that eases the edge and then cut the door down so that it clears the higher floor.
> 
> I'm going to have a higher floor in a future home improvement and my plan is to just chamfer the higher flooring over several inches to ease it down to the same height as the lower one. I haven't done it yet, though, so I can't comment on how effective it'll be





granroth said:


> Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.
> 
> In general, the more mass, damping, and space you can add, the better it'll be. Can you add a 6ft concrete ceiling? That would work. No? What, are you not committed to this?!
> 
> Kidding, of course...  If you're not developing a commercial studio or theater, then bass reduction will always be a compromise and trying to get "good enough"
> 
> So with that in mind:
> 
> 1. Putting green glue between the new floor would help (more damping in addition to the new mass); GG tends to amplify the effects of the additional mass. Bamboo flooring doesn't have a significant amount of mass, though, so I'm not sure how much it'd help overall. I love bamboo flooring, btw (installed it in my house) but not necessarily from a soundproofing perspective.
> 
> 2. Instead of drywall, consider putting cement board, like you might put under tile. A 1/2" sheet of cement board (like DUROCK) has about 3lbs / sq ft, which is quite a bit more than even 5/8" drywall. It is harder to work with, though.
> 
> 3. Adding more insulation may not help enough to matter. There's a steep cut-off in effectiveness after about 3 or 4 inches. Still, there are some improvements and it does have the effect of "widening" the space, which should help with bass. I just don't know that it would be worth the extra effort.



Thanks - , are the joists between floors strong enough to handle the load. Currently, I have 3 layers of 5/8" DW on the ceiling in the basement HT, hanging from hatchannel + clips attached to joists. If I add the Durock on the top of the joists (i.e. flooring of 1st floor dining room above HT) would that be too much weight?


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## ronny31

Judging by the silence in regards to my last post, I assume I have managed to make it make sense to you why concrete stops bass. Anything that recreates the abilities of concrete will work to the same effect. Tighter space between studs, stiffer materials, gluing materials together to make a thicker laminate (use epoxy for wood v wood laminate), reinforcing the material, etc. Tiles also contain bass quite well, hardwood, etc. Get creative. 
On the subject of high density variable density particle board (aka HDP), I'm sure there are similar products in the states. It probably goes under different nicknames. Shop around, ask for really stiff particle boards and fiber boards.


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## granroth

cgott42 said:


> Thanks - , are the joists between floors strong enough to handle the load. Currently, I have 3 layers of 5/8" DW on the ceiling in the basement HT, hanging from hatchannel + clips attached to joists. If I add the Durock on the top of the joists (i.e. flooring of 1st floor dining room above HT) would that be too much weight?


That's impossible to say for sure. I'd say "probably" since joists tend to be engineered to handle quite a bit of live load and, as a result, typically handle huge amounts of dead load (like flooring and ceiling and furniture and the like).

But I need to stress that I'm not a structural engineer and I won't pretend to be one. That's one area where I hired out help for my otherwise very DIY theater -- I don't mess around with the house structure!

If you have reason to be concerned, then definitely hire an engineer. It doesn't have to be for a full sealed plan or anything. I paid an engineer $200 for his opinion (and a sketch on a piece of drywall hanging around) for a question I had when building an addition. I didn't need a plan; I just needed his expert advice on whether my plan was reasonable or not.


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## granroth

ronny31 said:


> Judging by the silence in regards to my last post, I assume I have managed to make it make sense to you why concrete stops bass.


Heh, no, it's more that I haven't had time to read your post yet.

That said, I did do some more reading on stiffness as it related to LFE and it appears that I was wrong in thinking that mass matters the most in that case. You're absolutely right that stiffness is the dominant factor in those cases!

I'll be reading your post and responding appropriately tomorrow (or Tuesday at the latest)


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## cgott42

granroth said:


> That's impossible to say for sure. I'd say "probably" since joists tend to be engineered to handle quite a bit of live load and, as a result, typically handle huge amounts of dead load (like flooring and ceiling and furniture and the like).
> 
> But I need to stress that I'm not a structural engineer and I won't pretend to be one. That's one area where I hired out help for my otherwise very DIY theater -- I don't mess around with the house structure!
> 
> If you have reason to be concerned, then definitely hire an engineer. It doesn't have to be for a full sealed plan or anything. I paid an engineer $200 for his opinion (and a sketch on a piece of drywall hanging around) for a question I had when building an addition. I didn't need a plan; I just needed his expert advice on whether my plan was reasonable or not.


thanks, are there *any structural engineers* around that can comment - if the joists can safely hold (a) 3 layers of 5/8" DW on the bottom (i.e ceiling of basement HT room) + soffit running along the joists consisting of (2x10 wood + (b) 5/8" DW on each side of the soffit)+ (c) on top of the soffits (i.e. the floor of the 1st floor room above the HT) - the durock + bamboo flooring.)? Size of the room is approx 14x24
Joists go across the 14' span

thx


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## ronny31

cgott42 said:


> thanks, are there *any structural engineers* around that can comment - if the joists can safely hold (a) 3 layers of 5/8" DW on the bottom (i.e ceiling of basement HT room) + soffit running along the joists consisting of (2x10 wood + (b) 5/8" DW on each side of the soffit)+ (c) on top of the soffits (i.e. the floor of the 1st floor room above the HT) - the durock + bamboo flooring.)? Size of the room is approx 14x24
> 
> thx


If there is a structural engineer here he'll need to know if the joists go across the 14 foot span or the 24 foot span.


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## cgott42

ronny31 said:


> If there is a structural engineer here he'll need to know if the joists go across the 14 foot span or the 24 foot span.


thanks, I updated the post
Joists go across the 14' span


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## cw5billwade

cgott42 said:


> thanks, are there *any structural engineers* around that can comment - if the joists can safely hold (a) 3 layers of 5/8" DW on the bottom (i.e ceiling of basement HT room) + soffit running along the joists consisting of (2x10 wood + (b) 5/8" DW on each side of the soffit)+ (c) on top of the soffits (i.e. the floor of the 1st floor room above the HT) - the durock + bamboo flooring.)? Size of the room is approx 14x24
> 
> thx


Not sure on enginering but why is no one talking about serenity mat from sound proffing company .com. Serenity mat with a layer of 3/4" T&G then the bamboo would be their recomendation.


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## granroth

cw5billwade said:


> Not sure on enginering but why is no one talking about serenity mat from sound proffing company .com. Serenity mat with a layer of 3/4" T&G then the bamboo would be their recomendation.


From a foot-fall perspective, yes. Do they say that it'll help from a bass containment from the floor below perspective? I believe that that's the primary concern here.


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## granroth

cgott42 said:


> thanks, are there *any structural engineers* around that can comment - if the joists can safely hold (a) 3 layers of 5/8" DW on the bottom (i.e ceiling of basement HT room) + soffit running along the joists consisting of (2x10 wood + (b) 5/8" DW on each side of the soffit)+ (c) on top of the soffits (i.e. the floor of the 1st floor room above the HT) - the durock + bamboo flooring.)? Size of the room is approx 14x24
> Joists go across the 14' span
> 
> thx


I'm not aware of any structural engineers on AVS... and if they were here, it might be dangerous professionally for them to go on the record without doing a study. I only got the engineer who gave me an opinion to give me his opinion (and not a full sealed plan) by promising to not tell anybody that the advice came from him!

If you want to figure out some safe limits on your own, then start here: http://www.engineeringtoolbox.com/floor-joists-span-d_1479.html

The Engineering Toolbox is a treasure trove of fascinating engineering info. If you want to understand more on what those terms all mean, then this is a great intro: http://www.awc.org/technical/spantables/tutorial.php

One thing you'll see is that the normal accepted "dead load" of a floor is 10psf. Most span tables assume this and vary only on the "live load". The dead load is the weight of the materials on the floor. In your case, you have 3 * 5/8 DW @ 2.2psf + plywood @ 2psf + durock @ 3.0psf + weight of bamboo flooring (2psf?) = 13.6psf. Oops. Most span tables might not be applicable to you.

I'm not saying you can't have a floor that has a dead load of more than 10psf, but I am saying that you might not find any pre-computed span tables that would tell you what you need to know if that weight is exceeded.


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## granroth

ronny31 said:


> I have no idea how to argue this in the most efficient way possible, I just throw spaghetti at the concrete wall as I invent arguments. I'll try again. Lets involve some good old basic physics.
> When the subwoofer element moves in and out the air pressure differences from 120db are tiny across a square inch. Its 20 Pa, or 0.00290075475 pounds per square inch. But across an entire drywall in the bits between each stud it adds up to meaningful numbers....
> 
> [snip long interesting stuff]


First, thank you for this info. It definitely got me thinking enough to do some independent research and realize that I was wrong about mass vs stiffness when it comes to low frequency transmission loss. I love being proven wrong since that's always a prelude to me learning something new... which I love doing! 

I found two pages in particular that talked about this in usable ways:

http://wiki.naturalfrequency.com/wiki/Sound_Transmission

http://personal.inet.fi/koti/juhladude/soundproofing.html

What I glean from all this is that the "mass law", which dictates that doubling the mass will increase the transmission loss by 6dB, is only effective between the wall's resonance frequency and its critical/coincidence frequency. On both extremes, it's stiffness that becomes the dominant property. Since the coincidence effect tends to be pretty high, that doesn't come into play with talking about containing bass.

A wall's resonance frequency matters quite a bit, which is why most wall assemblies are designed to push that frequency as low as possible. Decoupling, mass, damping, and absorption ALL decrease the resonance frequency. That'll only go so low, though. You typically try to get it to 80Hz or under on the assumption that it doesn't matter at that point.

Er... but it does. If you are trying to contain LFE, then you absolutely want it lower than that.

So the problem with all this is that even though I have found confirmation that this effect appear to be true, I still have not found a substantial amount of further info on the subject. The dominant recommendation for LFE containment is still "mass and more mass". I also have a hard time reconciling this with rated wall assemblies. For instance, it makes sense that if stiffness matters most that doubling the amount of studs would help for bass containment... yet, check out these two walls from IR-761:

TL-93-283
2G16_WS90(610)_GFB90_AIR25_WS90(610)_GFB90_2G16
STC 69
50Hz 26.7
63Hz 31.8
80Hz 36.6
100Hz 39.5

TL-93-269
2G16_WS90(406)_GFB90_AIR25_WS90(406)_GFB90_2G16
STC 67
50Hz 24.7
63Hz 25.4
80Hz 32.2
100Hz 39.1

Those are two double drywall, double wall, fiberglass insulation walls. The only difference between the two is that the former one has the studs spaced at 24" O.C. (610mm) while the latter is at 16" O.C. (406mm). Notice that the wall with the wider spacing not only does better from an overall STC rating but also does better at all of the bass frequencies down to 50Hz. If stiffness matters more, then why wouldn't the 406mm wall perform better?

Unless it's because the resonant frequency of those walls is below 50Hz? I don't see the normal "dip" in either wall's graph that you'd expect to see at that point. So if the mass law still holds true up until the resonant frequency, then stiffness might not yet come into play.

Anyway, it's all very interesting. I have some questions posted on GearSlutz about this on the hopes that some of their resident experts will comment.


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## ronny31

granroth said:


> Those are two double drywall, double wall, fiberglass insulation walls. The only difference between the two is that the former one has the studs spaced at 24" O.C. (610mm) while the latter is at 16" O.C. (406mm). Notice that the wall with the wider spacing not only does better from an overall STC rating but also does better at all of the bass frequencies down to 50Hz. If stiffness matters more, then why wouldn't the 406mm wall perform better?


Good question. When I made the remark I didn't think about the fact that drywall works in essentially being no actual structural strength, whereas adding studs tries to add structural strength. Drywall is even separated from the studs in HTs so no actual screw goes from the drywal directly into the stud. Bass however works in the completely opposite way, when you stop it. Then you try to add as much structural connectivity as possible. 
To explain the results of shorter stud spacing on drywall: Vibration with 24" stud spacing isn't entirely across the entire width of the sheet in all frequencies. Page 15 here shows three different frequencies and how an air duct vibrates in those frequencies: 
http://www.ece.uvic.ca/~bctill/papers/numacoust/Cummings_2001.pdf 
With 24 inch spacing certain frequencies will vibrate in the entire length of the drywall, and some frequencies will make the wall want to vibrate in several bits like figure B and C. Figure A shows 2 portions, top and bottom half, figure B shows more portions, figure C shows even more portions. It seems the drywall moves more with shorter spans than longer spans, in light of the evidence. 
But with other materials, when you stop bass, you do it by reducing the movement in the boards by strengthening them. Because if you want to strengthen a HDP wall then you half stud space the wall and thus you can glue the sheets to twice as much surface half as far apart. In addition to twice as many screws which pull the sheets against the studs properly, allowing the glue to get a proper bond, and the joints fit into each other, which is also glued. Adding studs in this fashion is extremely effective at adding structural strength. Lowering the total movement across frequencies because its stronger. 
Drywall disintegrates if not for some cardboard, and can't be screwed tight against the studs like anything with proper structural properties. For all intents and purposes it hangs there as if it was hung in two strings from the ceiling, then lightly held towards the studs by some screws. The joints don't interconnect, and it can't really be glued effectively to the studs (its cardboard against wood). 
With HDP even if there are added frequencies that the wall respond to, it will be sufficiently stronger as to still have less bass transmission. Though at higher frequencies, this will probably be reversed. HDP is extremely stiff, when its tapped it can ring as if you're trying to make a Marimba. But its so strong this can be negated by adding yet more strength, and eventually just some foam material when the frequencies become high enough for foam to effectively stop. With HDP you can do all kinds of tricks. You can epoxy it, you can triangulate, you can make it bend slightly across a surface. Bending the sheet slightly in one axis makes it tense up, and two axis bends are even better (bend and slight twist). You can also put it under point-tension by compressing bits. When reinforcing HDP speaker enclosures we add a stud from side to side with glue and a screw or two. But we can also add a slightly too short stud in the middle between two sides we want to reinforce, then we add glue and screw into it from the outside, forcing the center of those two sides to become concave. For even more added strength we can add longer studs around the shorter one, with more shorter studs around them again, when we screw into the shorter studs the HDP sheet compresses against the longer studs and reaches to the shorter studs. With complex combinations of long and short studs we can get really high tension on every square inch of the HDP. Can also add slight imperfections in the straightness of the pieces, so when we screw the HDP to it (with glue on all connected bits) we add natural tension. We can staple in addition to screw to limit how much the material relaxes over time. Can also glue HDP and wood to various large surfaces (essentially like gluing ceramic tiles to the surfaces, the ceramic tile will add weight to the surface and if its bigger than the section trying to vibrate it won't let it vibrate beause ceramic is ultra-stiff, essentially its a tiny triangle effect). We can also add smaller and smaller reinforcements, a bunch of tiny dimension reinforcements all split up the surfaces and hinder vibrations significantly with this level of structural bonding between the wooden bits. Triangles in triangles and tension upon tension and gluing like crazy, sometimes even with epoxy all over and even some glassfiber gussets to ensure the HDP doesn't relax its shape at some point. With some work we can come darn close to the strength and vibrational specifications of concrete. Translated to houses its easier to just do concrete, but \|\|\|\|\| triangles shape on studs and gluing fiberboard to the studs with tightly packed screws and adding tension to the boards and so forth will all help make less low frequency sounds pass through. But this is large areas, a 40x60x50cm speaker enclosure is one thing, a 240x500cm wall is quite another, and will require tons of tricks. I'm not even sure fiberboard is strong enough to get near HDP or concrete performance in this respect. Various split up stone slabs would certainly help, like ceramic tiles and slate stone, since the pieces themselves don't want to vibrate like the sheet materials. But unless you're essentially making a 5 inch thick fiberglass composite wing as your wall, concrete is likely to be easier. The only limit to strength you can have with HDP, other wood types and composites, is the span of each surface. If you have a sheet, you can even think in three dimensions. You divide a sheet into four Tetrahedrons. Then you divide each Tetrahedron into more Tetrahedrons, and then so and so on, only limit is how small you can go. If you build a wall with a core of glassfiber tetrahedons held together with epoxy it would be extremely light and strong. If you go small enough you can get concrete strength from a 1 inch sheet, and let almost no bass through. To let even less bass through you'd add another sheet, and so forth. 
To get maximum bass stopping power without simply doing a five foot thick lead wall its really about trying to push the resonance frequency up, that's what these Tetrahedrons would do. The opposite just isn't possible, really, with bass. We could try to hang like 10 inch thick drywall sheets, or even just make structurally sound drywall ourselves with plaster and fibers like the bad old days. But it would be better to bring out the portland cement and build a brick house, then throw up a sheet rock combination built specifically to stop high frequencies. I just have yet to come across anything that works as well as strengthening, in terms of stopping bass. 

If you insist on using drywall however, I'd say you'd have to use half space studs with double glued composite wood sheets underneath HT-style spaced drywall. Then the drywall stops HF and the stiffer wood stops LF. Or that's the idea anyway, if the wood is stiff enough with only half spacing studs and no tricks I rather doubt if there isn't HDP to use. 

PS: Why would anyone strengthen enclosures that much? Because enclosure vibrations is energy given from the amp that isn't db. There's always some HDP left around, and wood glue, and a cup of epoxy costs nothing compared to the amp and speaker and so forth.


----------



## cw5billwade

granroth said:


> From a foot-fall perspective, yes. Do they say that it'll help from a bass containment from the floor below perspective? I believe that that's the primary concern here.


this is the recommendation remember if it stops foot fall it should help reduce base as we are talking MASS


----------



## ronny31

cw5billwade said:


> this is the recommendation remember if it stops foot fall it should help reduce base as we are talking MASS


Splitting the wood up like that instead of having a really thick glulam sheet by gluing them together, I think is a mistake. It would practically be concrete with 3 layer glulam glued and screwed directly to the studs. But it seems they're only thinking about stopping common noise like footsteps and talking and so forth, not music from a huge stereo (where there's tons of bass).


----------



## cgott42

granroth said:


> That's impossible to say for sure. I'd say "probably" since joists tend to be engineered to handle quite a bit of live load and, as a result, typically handle huge amounts of dead load (like flooring and ceiling and furniture and the like).
> 
> But I need to stress that I'm not a structural engineer and I won't pretend to be one. That's one area where I hired out help for my otherwise very DIY theater -- I don't mess around with the house structure!
> 
> If you have reason to be concerned, then definitely hire an engineer. It doesn't have to be for a full sealed plan or anything. I paid an engineer $200 for his opinion (and a sketch on a piece of drywall hanging around) for a question I had when building an addition. I didn't need a plan; I just needed his expert advice on whether my plan was reasonable or not.





granroth said:


> I'm not aware of any structural engineers on AVS... and if they were here, it might be dangerous professionally for them to go on the record without doing a study. I only got the engineer who gave me an opinion to give me his opinion (and not a full sealed plan) by promising to not tell anybody that the advice came from him!
> 
> If you want to figure out some safe limits on your own, then start here: http://www.engineeringtoolbox.com/floor-joists-span-d_1479.html
> 
> The Engineering Toolbox is a treasure trove of fascinating engineering info. If you want to understand more on what those terms all mean, then this is a great intro: http://www.awc.org/technical/spantables/tutorial.php
> 
> One thing you'll see is that the normal accepted "dead load" of a floor is 10psf. Most span tables assume this and vary only on the "live load". The dead load is the weight of the materials on the floor. In your case, you have 3 * 5/8 DW @ 2.2psf + plywood @ 2psf + durock @ 3.0psf + weight of bamboo flooring (2psf?) = 13.6psf. Oops. Most span tables might not be applicable to you.
> 
> I'm not saying you can't have a floor that has a dead load of more than 10psf, but I am saying that you might not find any pre-computed span tables that would tell you what you need to know if that weight is exceeded.


Thanks for the info! It seems from what you're saying that before adding any new flooring I'm already at 10.6psf (=6.6psf DW + 2psf plywood + 2psf existing floor) + the weight of the soffit, so I'm already over the 10psf safe point. So I think durock is out . And I can just add another layer of bamboo flooring over the existing hardwood floor. being so, should I GreenGlue the 2 layers together - will that make a noticeable impact to what I have?


----------



## granroth

cw5billwade said:


> this is the recommendation remember if it stops foot fall it should help reduce base as we are talking MASS


Hmm... Serenity Mat and the like are well known to absorb high energy mechanical vibrations like those coming from footfalls. I haven't seen those type of vibrations described as low frequency, though. It's entirely possible that Serenity Mat would work for bass absorption as well, but again, I'm not thinking of any recommendations that claim that.

A call to Ted would likely clear that up


----------



## granroth

cgott42 said:


> Thanks for the info! It seems from what you're saying that before adding any new flooring I'm already at 10.6psf (=6.6psf DW + 2psf plywood + 2psf existing floor) + the weight of the soffit, so I'm already over the 10psf safe point. So I think durock is out . And I can just add another layer of bamboo flooring over the existing hardwood floor. being so, should I GreenGlue the 2 layers together - will that make a noticeable impact to what I have?


My recommendation is to call Ted at the SoundProofing Company and chat with him or John. 

Thing is, they are the experts on Green Glue and can absolutely tell you what kind of impact using it will have in your case. Also, Bill may be right in recommending Serenity Mat in this case. Ted/John would know about that, too. I think you can answer a lot of your questions with one phone call.


----------



## granroth

ronny31 said:


> ... when you stop bass, you do it by reducing the movement in the boards by strengthening them.


Okay, so it turns out that I'm not quite as wrong as I thought I was and you're not quite as right as you thought you were 

I started a thread on GearSlutz, __HERE__, where I engaged some of the top acoustic experts to comment on the 'mass vs stiffness' issue.

In particular, I was very interested in Rod Gervais' opinion on the topic since he mentioned in his book "Home Recording Studio: Build it Like the Pros" this (emphasis added):



Rod Gervais said:


> ...Thus, although sound isolation for higher frequencies is relatively easy to obtain, isolation for lower frequencies is much more difficult to achieve.
> 
> To truly understand this, you would need to look at (and understand) how mass, stiffness, and damping come together to affect an assembly....
> 
> *At lower frequencies (roughly 10–20 Hz), sound transmission tends to depend mostly on how stiff the assembly is.*


I consider Rod one of the foremost experts in this topic in the world, so it was his quote that flipped me onto the side of thinking that stiffness mattered more than mass for low frequencies. The other articles then "confirmed" this.

But it turns out that I mis-read this as well as mis-read the other articles that talked about the importance of stiffness! In fact, it's not so much stiffness that matters as the *INVERSE* of stiffness -- or flexibility / floppyness!! 

All of the comments I got in that (hopefully still ongoing) thread are excellent so I strongly suggest reading them. The TL;DR is that mass can still play a dominant role in LFE but you need a lot of it to matter. If you don't have enough mass (and it's hard to get enough), then the dominant factor then becomes the rigidity of the material, with "looser" materials doing a better job than stiffer ones. That's why having fewer studs with more space between them (thus creating a more flexible wall) actually does better when tested.

This is all fascinating stuff!


----------



## ronny31

granroth said:


> Okay, so it turns out that I'm not quite as wrong as I thought I was and you're not quite as right as you thought you were
> 
> I started a thread on GearSlutz, __HERE__, where I engaged some of the top acoustic experts to comment on the 'mass vs stiffness' issue.
> 
> In particular, I was very interested in Rod Gervais' opinion on the topic since he mentioned in his book "Home Recording Studio: Build it Like the Pros" this (emphasis added):
> 
> I consider Rod one of the foremost experts in this topic in the world, so it was his quote that flipped me onto the side of thinking that stiffness mattered more than mass for low frequencies. The other articles then "confirmed" this.
> 
> But it turns out that I mis-read this as well as mis-read the other articles that talked about the importance of stiffness! In fact, it's not so much stiffness that matters as the *INVERSE* of stiffness -- or flexibility / floppyness!!
> 
> All of the comments I got in that (hopefully still ongoing) thread are excellent so I strongly suggest reading them. The TL;DR is that mass can still play a dominant role in LFE but you need a lot of it to matter. If you don't have enough mass (and it's hard to get enough), then the dominant factor then becomes the rigidity of the material, with "looser" materials doing a better job than stiffer ones. That's why having fewer studs with more space between them (thus creating a more flexible wall) actually does better when tested.
> 
> This is all fascinating stuff!


It makes sense that really massive flexible surfaces can stop bass if there's just enough space between studs. But the drywall and stuff which contains the sound is like a thick layer of paint, in terms of how useful it is for the structural strength of the house. With this method you build a house, with all the cost that incurs. Then you build something inside it in order to contain the sound. I bet its cheaper and easier (thus less work and wages to pay) to build a house that contains sound, if that is the goal from the start. 
But I'm probably biased, I come from db drag environment where its important that you are able to move the creation you want to contain db inside, so weight plays a factor. In a house weight sometimes don't play a factor at all (but it does play a factor in some cases, like second floor HTs, and someone has to lift it all to the wall and so forth). 

In light of the new information I am actually quite confident I can figure out a more cost-effective way to sound dampen. Especially if one is allowed to design the house from scratch. I'm going to mull over it for a while. Some ideas spring to mind.


----------



## cw5billwade

ronny31 said:


> Splitting the wood up like that instead of having a really thick glulam sheet by gluing them together, I think is a mistake. It would practically be concrete with 3 layer glulam glued and screwed directly to the studs. But it seems they're only thinking about stopping common noise like footsteps and talking and so forth, not music from a huge stereo (where there's tons of bass).


below is the perfered method for ceilings but his theater is already built so no way to ad 2 more layers of DW between the studs. So the next best thing is to treat it at the source. Since he is puting in new floring anyway.





granroth said:


> Hmm... Serenity Mat and the like are well known to absorb high energy mechanical vibrations like those coming from footfalls. I haven't seen those type of vibrations described as low frequency, though. It's entirely possible that Serenity Mat would work for bass absorption as well, but again, I'm not thinking of any recommendations that claim that.
> 
> A call to Ted would likely clear that up


there are many insitance of folks puting serenity mat under their stage to stop tranmission of the base vibrations to the floor from the subs sitting on the stage. I talked to Jon about it and was considering it but man that stuff is expensive. In the if I had it to do over frount I would have used the serenity mat and 2 more layers of OSB with GG on my floor. I only used one layer of OSB and GG on the sub floor. I figured I was over a garage so why bother. I can really hear the base in the garage and still hear the garage door open in the theater.


----------



## BasementBob

Stiffness.

An optimum wall is one with the lowest resonance frequency and highest coincidence frequency, and largest sum TL across all frequencies.

Think of a drum. If you tension/stiffen the membrane the resonance frequency goes up, but the mass doesn't change.
Same with a wall.

Under the resonance freq of the construction you have stiffness control meaning the whole construction is trying to move in phase but can't because it is suspended one way of the other by gravity, or mechanically. So here you see better TL than at resonance.
Stiff constructions have the disadvantage they have higher res freqs than less stiff constructions of the same kind and mass, so TL will drop.
25 mm of MDF is stiffer than 2 x 12.5 mm NOT glued or screwed totally together, as the two plates can be moved a bit by sound causing friction and turning sound into heat. GG can amplify this behaviour. reducing coincidence.
Stiffness of a construction should not be confused with the stiffness controlled region as the latter just means the construction is mechanically fixed at the boundary and thus moves less easy than the whole construction would move if there would be no resistance at the boundary.
A speaker cone can move relatively freely until at large excursion it reaches the limit of the suspension.
-- Bert Stoltenborg

The coincidence dip may be shifted up or down the frequency range by altering stiffness, boundary conditions and changing thickness of the material. For example, if two layers of material such as wallboard are glued firmly together, they behave like a single thick layer with an associated lowering of the coincidence frequency. If the layers are only held together loosely (with screws for example) so that they can slide over each other to some extent during bending motions, then the coincidence frequency does not move to lower frequencies and the friction between the layers can introduce some extra energy losses, giving higher transmission loss near coincidence. 
-- http://personal.inet.fi/koti/juhladude/soundproofing.html










For more on the coincidence dip see
http://www.bobgolds.com/GlueOrScrew/home.htm

Below, 
a) is a given wall, and
b) is a stiffer wall

Notice how the coincidence frequency drops, and the resonance frequency goes up.










Although a few movies might have energy in the 10hz to 20hz region, they all have energy in the 50hz to 100hz region.
In the below, notice how the stiffer wall reduces TL at the common frequencies.










I believe Dennis Erskine was fond of rigid gluing drywall to the studs (to reduce potential rattle).
I don't recall Dennis recommending to glue drywall to drywall, which would have made the wall stiffer.

Brian Ravnass did some lab experiments gluing with rigid adhesives.
note: a rigidly bonded panel is 4 times stiffer than 2 non-bonded panels.










The mechanical structure (Stud spacing, panel stiffness) plays a strong role in resonance location. 
As I recall, Brian Ravnass also did some experiments with having studs at 48 inches (1200mm), 24 inches (600mm), and 16 inches (400mm) and lab measured that a more flexible wall is a better wall than a stiff wall, but not a lot. In lab measurements with gypsum double stud walls, the resonance dip is locatable in the just below the lab's confidence region.

if you want to build (really effective) isolated construction - you really need to stress the isolated side of the equation..... and when it comes to bearing assemblies (and the ceilings bearing on those assemblies) the capacity for adequate structural support (and the various building codes that come into play in that regard) then takes control.
The building codes (at least here in the states) do not allow the use of 2x4 framing for structural support placed on 24 inch centers........ they max out at 16 inch. If you want 24 inch centers you are then driven to 2x6.
-- Rod Gervais, here

In any event, the stiffness discussion is mostly moot. Most North American homes will use two 13mm layers of drywall, most home theatres interested in sound proofing will use four layers of 16mm drywall, and professional installations will use concrete. Each of these has been well thought out by people more knowledgeable than I, and use materials that are the cheapest bang (or 'lack of bang') for the buck. Or to say the same thing another way, see the common constructions in books like 'Noise Control In Buildings' by Harris, choose a TL you can live with, and build it as per the tested example. Or to say the same thing yet another way, due to cost if you end up using concrete to get the needed mass, its stiffness is already predetermined.


----------



## ronny31

BasementBob said:


> Below,
> a) is a given wall, and
> b) is a stiffer wall
> 
> Notice how the coincidence frequency drops, and the resonance frequency goes up.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> (...)
> In any event, the stiffness discussion is mostly moot. Most North American homes will use two 13mm layers of drywall, most home theatres interested in sound proofing will use four layers of 16mm drywall, and professional installations will use concrete. Each of these has been well thought out by people more knowledgeable than I, and use materials that are the cheapest bang (or 'lack of bang') for the buck. Or to say the same thing another way, see the common constructions in books like 'Noise Control In Buildings' by Harris, choose a TL you can live with, and build it as per the tested example. Or to say the same thing yet another way, due to cost if you end up using concrete to get the needed mass, its stiffness is already predetermined.


I think there's potential for improvement. Lay those two walls at the same wall and you get much better performance. But crucially, I think there's some tricks the average house designer isn't using in HT designs. In light of the new knowledge about stiffness and "floppiness" in terms of sound transmission, I'm drawing up something I think may be better, and perhaps cheaper.


----------



## gdc123

Have a question about this opening around the ducting.. I am going to add a soffit after sheet rock do I need to close this off with a soffit inside a soffit? 

Or will the outer soffit be enough. It will be isolated from the joist and double layer with green glue around it.


----------



## JRock3x8

apologies if this is already mentioned in this thread - didn't have time to read the whole thing...

what is the relative performance of normal construction? 2 sheets of drywall flush on 2x4's?


----------



## KanosWRX

gdc123 said:


> Have a question about this opening around the ducting.. I am going to add a soffit after sheet rock do I need to close this off with a soffit inside a soffit?
> 
> Or will the outer soffit be enough. It will be isolated from the joist and double layer with green glue around it.


Should be fine just building a soffit around it normally like you said, no need for a double soffit. I had duct work in my Home Theater, just built the soffit around it using IB3 brackets to isolate it, then put up the DD+GG.


----------



## granroth

JRock3x8 said:


> apologies if this is already mentioned in this thread - didn't have time to read the whole thing...
> 
> what is the relative performance of normal construction? 2 sheets of drywall flush on 2x4's?


I'm assuming you mean:

1/2" DW + Studs 16" O.C + 1/2" DW

That is, only one layer of 1/2" drywall on each side of the wall and no insulation in between.

STC 34

That increases to STC 35 is you have the studs 24" O.C. (plus will handle low frequencies better).


----------



## gdc123

KanosWRX said:


> Should be fine just building a soffit around it normally like you said, no need for a double soffit. I had duct work in my Home Theater, just built the soffit around it using IB3 brackets to isolate it, then put up the DD+GG.



Thanks for the input.. I did forget to say that I am putting can lights into the soffit and do not plan to use backer boxes. I will fill the cavity with isolation. Will the opening around that duct cause an issue with sound. The space next to this room is just a storage room but the joist are exposed in that area which has an office above it.


----------



## KanosWRX

gdc123 said:


> Thanks for the input.. I did forget to say that I am putting can lights into the soffit and do not plan to use backer boxes. I will fill the cavity with isolation. Will the opening around that duct cause an issue with sound. The space next to this room is just a storage room but the joist are exposed in that area which has an office above it.


Well I guess it comes down to if you want the best possible solution and want to go that extra mile. I have two lights in one of my soffits that I didn't build backer boxes for, and I also have ducts that don't have backer boxes around all of them. But I did put insulation around all of them like you plan on doing. What I am doing though is putting acoustic sealant in any gaps or holes between the lights and hvac registers and the drywall. The can lights are sealed, just not heavy duty with backer boxes, like the hvac duct work. In the end I think it's still a good enough solution, but if your going for that 95-100% solution then you would want to build backer boxes for everything.


----------



## nonstopdoc1

Can anyone comment on relative cost and effectiveness of various approaches, "room within a room" vs staggered studs vs clips for a 15' x 20' room considering everything else the same??


----------



## granroth

nonstopdoc1 said:


> Can anyone comment on relative cost and effectiveness of various approaches, "room within a room" vs staggered studs vs clips for a 15' x 20' room considering everything else the same??


In short:

A room within a room is the most effective and adds very little cost to the project (compared to other methods). Its downside is that it will take a minimum of 8" from each dimension.

Clips and channel is very nearly as effective as double walls and results in the least amount of space lost (a couple inches, typically). It's downside is that it's far more expensive than the alternatives.

Staggered studs are pretty decent performers and use less space than double walls but more than clips. They're more rarely used, since double walls are quite a bit more effective if you can spare a few more inches and clips are also far more effective if you can spare the money.

Clips are extremely common since, well, theaters are typically pretty expensive luxury rooms anyway but space is often at a premium. The cost of clips is often worth it, then. Double walls are the choice if you can give up a few more inches; want the absolute best isolation; and want to save a few bucks. Keep in mind that you'll need to either "float" your joists or still use clips for the ceiling, if you go the double wall route.


----------



## cw5billwade

gdc123 said:


> Have a question about this opening around the ducting.. I am going to add a soffit after sheet rock do I need to close this off with a soffit inside a soffit?
> 
> Or will the outer soffit be enough. It will be isolated from the joist and double layer with green glue around it.


 I think that if you use the IB3 clips and frame out a box completly around the duct work and then do the DW/GG/DW on both sides and bottom of it along with the ceiling and walls then build the soffits internal to the room matching up to this already built box in the corner. That way there is no direct conection to the duct area where sound could travel up the soffit and escape. Hope that makes sence.


KanosWRX said:


> Should be fine just building a soffit around it normally like you said, no need for a double soffit. I had duct work in my Home Theater, just built the soffit around it using IB3 brackets to isolate it, then put up the DD+GG.





gdc123 said:


> Thanks for the input.. I did forget to say that I am putting can lights into the soffit and do not plan to use backer boxes. I will fill the cavity with isolation. Will the opening around that duct cause an issue with sound. The space next to this room is just a storage room but the joist are exposed in that area which has an office above it.


Just box it in like above and it will be part of the sound envolope then build the soffits up to it no leaks


----------



## JRock3x8

granroth said:


> I'm assuming you mean:
> 
> 1/2" DW + Studs 16" O.C + 1/2" DW
> 
> That is, only one layer of 1/2" drywall on each side of the wall and no insulation in between.
> 
> STC 34
> 
> That increases to STC 35 is you have the studs 24" O.C. (plus will handle low frequencies better).


So just to be clear if my theater is running at 80db, outside the room the noise heard would be 46db? Double drywall adds another 20 and green glue adds another 20? Or was that whisper clips that added the 20?

Am i thinking about this correctly? How far am I off?


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## KanosWRX

JRock3x8 said:


> So just to be clear if my theater is running at 80db, outside the room the noise heard would be 46db? Double drywall adds another 20 and green glue adds another 20? Or was that whisper clips that added the 20?
> 
> Am i thinking about this correctly? How far am I off?


STC isn't a direct correlation to DB drop. It's a different measurement. Also STC stops measuring before the low frequencies really come into play, so LFE will pass through more then what they say. The most I have really seen for walls is around STC 65. That's a double wall system with insulation, 1" air gap and 5/8" heavy DD+GG. Granted you could get maybe a few more STC going with mor drywall, but it's diminishing returns at that point. You have stopped most of the high freq already, it's the low you have to worry about.


----------



## PAPutzback

granroth said:


> In short:
> 
> A room within a room is the most effective and adds very little cost to the project (compared to other methods). Its downside is that it will take a minimum of 8" from each dimension.
> 
> Clips and channel is very nearly as effective as double walls and results in the least amount of space lost (a couple inches, typically). It's downside is that it's far more expensive than the alternatives.
> 
> Staggered studs are pretty decent performers and use less space than double walls but more than clips. They're more rarely used, since double walls are quite a bit more effective if you can spare a few more inches and clips are also far more effective if you can spare the money.
> 
> Clips are extremely common since, well, theaters are typically pretty expensive luxury rooms anyway but space is often at a premium. The cost of clips is often worth it, then. Double walls are the choice if you can give up a few more inches; want the absolute best isolation; and want to save a few bucks. Keep in mind that you'll need to either "float" your joists or still use clips for the ceiling, if you go the double wall route.


Are Clips and channel really that expensive compared to adding an entire room within a room? 
I am in the process of finishing my basement and want to know what the best "Bang for the Buck" soundproofing technique is? Not including the insulation in the equation since I already plan on doing that.

I don't want to lose anymore space with staggered walls. I am willing to give up the space required for some sort of resilient channel, clips or a second layer of drywall with Green glue.


----------



## granroth

JRock3x8 said:


> So just to be clear if my theater is running at 80db, outside the room the noise heard would be 46db? Double drywall adds another 20 and green glue adds another 20? Or was that whisper clips that added the 20?
> 
> Am i thinking about this correctly? How far am I off?


KanosWRX already addressed the fact that STC doesn't directly equate to dB drop. But I also want to add that you can't simply add a specific amount of dB drop (or STC points) for any given component of a solution. That is, just using Green Glue will not net another 20 dB attenuation, nor will clips. It may sound pedantic, but it's very important to understand that a soundproofing solution works as a WHOLE rather than as a sum of the parts. Just using Green Glue on a wall might net practically no improvement at all whereas if it's used in a properly done (and tested) wall, then it might contribute to that wall having a 20dB improvement.

Put another way, don't necessarily think you can mix and match items and expect to get any kind of predictable results. The only predictable results (within reason) are the previously tested full-wall solutions. Build it exactly like specified and you can be assured that your results will be in the ballpark of theirs. Differ on any element and who knows? Maybe it'll be fine. Maybe it'll be catastrophically worse.


----------



## granroth

PAPutzback said:


> Are Clips and channel really that expensive compared to adding an entire room within a room?
> I am in the process of finishing my basement and want to know what the best "Bang for the Buck" soundproofing technique is? Not including the insulation in the equation since I already plan on doing that.
> 
> I don't want to lose anymore space with staggered walls. I am willing to give up the space required for some sort of resilient channel, clips or a second layer of drywall with Green glue.


If you aren't willing to lose the space for a double wall and are willing to spend the money on clips, then your choice is made!

Double walls are absolutely the best bang for the buck and by quite a large margin. If you assume a 15x20x8 room then we're looking at $1100-$1200 worth of clips (assuming a clip every 5 sq ft @ $6/clip). Building an inner wall with 2x4 studs and it'll cost you maybe $150. It's almost a factor of 10 difference!

This is assuming that you'll still do double layers of drywall in either case. Arguably adding a second layer of 5/8" drywall would be the least amount of money spent on a soundproofing solution, but it won't give you the same gains as a decoupled solution would. Few people would do a decoupled solution without also using at least two layers of drywall.

I'd consider Green Glue or QuietGlue Pro as being something you'd use to eek out that little extra performance after you've already decoupled, added mass, and added insulation. Costs can wildly vary with GG but most people will pay at least $600-$700 to do a typical room and some pay notably more.

*IF* money is too tight for clips and *IF* the space loss of double or staggered walls is unacceptable *THEN* GG with double drywall will definitely work better than just drywall, but I'd hesitate to use words like "bang for the buck" with it.


----------



## PAPutzback

Thanks for the response. I think insulation, GG and double drywall is the way to go. I am not looking to "SoundProof" as much as I am looking to hopefully cut the sound down a bit. 

When I get new flooring upstairs, do you think adding a sheet of the mass loaded Vinyl is worthwhile?


----------



## cw5billwade

PAPutzback said:


> Thanks for the response. I think insulation, GG and double drywall is the way to go. I am not looking to "SoundProof" as much as I am looking to hopefully cut the sound down a bit.
> 
> When I get new flooring upstairs, do you think adding a sheet of the mass loaded Vinyl is worthwhile?


if this is built in a basement then just get the IB3 clips for the walls. IB-3 clips are every corner and then every 48" on the walls so that is not to many. Make the walls 1" from any exterior walls. then either do floating ceiling joist on the decoupled walls or just use the IB-1 clips and channel like I did on my ceiling. IB-1 clips which are about $3 will need to be put on floor joist every 48" but in a diagonal pattern. Check the sound proffing company web sit for more information.  Later you can decide if you want to build another wall outside the theater or just put 2 layers of DW/GG/DW on both sides of the decoupled wall with pink stuff in between. If you do not decouple the ceiling no need to decouple the walls as this will short cirucit your effort.

on the floor also there are some good information on their web site check both floor and ceiling facts one thing folks do is use GG to put strips of DW between the floor joists. They use serenity mat on the floor above I am not sure what the differance between that and MLV is I think the serenity is rubber based it is just for mass then you float your OSB on top that then your hard wood or what ever.


----------



## cgott42

granroth said:


> Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.
> 
> In general, the more mass, damping, and space you can add, the better it'll be. Can you add a 6ft concrete ceiling? That would work. No? What, are you not committed to this?!
> 
> Kidding, of course...  If you're not developing a commercial studio or theater, then bass reduction will always be a compromise and trying to get "good enough"
> 
> So with that in mind:
> 
> 1. Putting green glue between the new floor would help (more damping in addition to the new mass); GG tends to amplify the effects of the additional mass. Bamboo flooring doesn't have a significant amount of mass, though, so I'm not sure how much it'd help overall. I love bamboo flooring, btw (installed it in my house) but not necessarily from a soundproofing perspective.
> 
> 2. Instead of drywall, consider putting cement board, like you might put under tile. A 1/2" sheet of cement board (like DUROCK) has about 3lbs / sq ft, which is quite a bit more than even 5/8" drywall. It is harder to work with, though.
> 
> 3. Adding more insulation may not help enough to matter. There's a steep cut-off in effectiveness after about 3 or 4 inches. Still, there are some improvements and it does have the effect of "widening" the space, which should help with bass. I just don't know that it would be worth the extra effort.





cgott42 said:


> Q - My HT is located in the basement below the dining room of the first floor (which is adjacent to the kitchen and front entrance).
> My HT room is fully decoupled + DW+GW+DW. It does a great job of sound containment with all but the "good" LFE scenes played at reference level. Particularly it gives some rumble to the dining room and areas mentioned above. (so my current solution is to lower the sub level during hours people are in these rooms). My wife is looking to redo the dining room floor, so I was thinking about using this as an opportunity to get rid of that rumbling.
> i.e. the plan was to buy click together bamboo flooring (like this) directly on top of the existing hardwood floor. However for Sound Containment, I was thinking of the following options, and wondering your thoughts on comparatively, and absolutely how much each would help the LFE containment :
> 
> 
> simply putting green glue between the new floor and the existing hardwood floor
> putting GG + a 3/8" layer (5/8" if I can fit it) of DW under the existing hardwood floor
> cutting some holes (strips) in the existing hardwood + subflooring to get to the ceiling of the HT, and stuffing more pink fluffy insulation in it (as currently the cavity of the ceiling which I'm guessing is 9-12" deep, has about 3" of insulation (maybe 6", I may have stuffed the additional r13 batt in (but in some places I needed to compress it to fit , due to cross supports in the cavity ) - Obviously this would add complexity to the project, so I'd like to avoid, but it the gap at the top of the cavity is creating a big problem, and is necessary to fix, I can do it.
> What do you think?


Just a status update, thanks to all for the info given (namely to decouple new floor and add lots of mass and call Ted White re: structural integrity and Serenity Mat). I called Ted, he didn't want to say if the joists would hold the 3 layers of DW underneath the joists (ceiling of HT) + the add'l weight above - he recommended that I look up though it sounded as if it would hold explaining that the weight is spread and live load vs. dead load. Of course, I looked it up e.g. here and don't know enough to figure it out. I also checked the dining room above the HT - checking the walls vs. floor and confirmed that the walls are fine, and the vibration is coming from the floor.
Also in regards to the serenity mat - someone here wasn't sure if it would be helpful - Ted said that it would as it serves to decouple - so he suggested putting down the Serenity Mat and then 2 layers of plywood with GG between them (laid perpendicular to each other, and screwed together, without screwing into the serenity mat), and then new flooring on top of this. I plan on buying the Serenity Mat + GG from Ted and I can let you know how it went (waiting on final decision on flooring first).
any help on understanding the Span Tables would be appreciated.


----------



## granroth

PAPutzback said:


> When I get new flooring upstairs, do you think adding a sheet of the mass loaded Vinyl is worthwhile?


Not usually. The pros say that MLV is typically only worthwhile if you are using it in a limp mass mode. If it's going to be sandwiched between other rigid surfaces, then using a damping compound like Green Glue or QuietGlue Pro will pretty much always perform better and cost less. MLV is one of the notably more expensive soundproofing components available so it needs to be used in cases where only it would work, for it to be worthwhile.

If you still have access to the underside of the floor, then Bill's suggestion of putting strips of DW with GG in between the joists is the best bang for the buck in that case.



cw5billwade said:


> on the floor also there are some good information on their web site check both floor and ceiling facts one thing folks do is use GG to put strips of DW between the floor joists. They use serenity mat on the floor above I am not sure what the differance between that and MLV is I think the serenity is rubber based it is just for mass then you float your OSB on top that then your hard wood or what ever.


I'm still not convinced that serenity mat will be effective as a mass-based soundproofing component. I've never seen it used in that way. It's always used as a way of combating mechanical vibrations, such as foot fall traffic or even bass. I see it as a decoupling mechanism more than a mass mechanism.

I could be completely wrong but, again, I don't recall ever seeing it in the context of a mass unit.


----------



## granroth

cgott42 said:


> any help on understanding the Span Tables would be appreciated.


I need to stress again that you really should be contacting a structural engineer about this. It's one thing if soundproofing advice or implementation isn't up to snuff -- at worst it'll just be louder than you prefer. Not even remotely life and death. If advice about a structural matter is wrong, then it absolutely can be life and death! 

IF your floor was clearly over-engineered or you weren't even remotely close to the limits, then I'd feel more comfortable making proclamations based off of published span tables and such. Your floor is definitely closer to the edge than that, though. Close enough that the details very much matter.

So... find a local structural engineer and ask if he can just give you an off-the-record opinion and not a full sealed plan. Some might not. You'll almost surely find one who will... you might have to have him come out for an estimate (officially) and then just pay him cash for the opinion. That couple-hundred dollars opinion would be worth every penny from a peace of mind perspective!


----------



## cgott42

granroth said:


> Not usually. The pros say that MLV is typically only worthwhile if you are using it in a limp mass mode. If it's going to be sandwiched between other rigid surfaces, then using a damping compound like Green Glue or QuietGlue Pro will pretty much always perform better and cost less. MLV is one of the notably more expensive soundproofing components available so it needs to be used in cases where only it would work, for it to be worthwhile.
> 
> If you still have access to the underside of the floor, then Bill's suggestion of putting strips of DW with GG in between the joists is the best bang for the buck in that case.
> 
> 
> 
> I'm still not convinced that serenity mat will be effective as a mass-based soundproofing component. I've never seen it used in that way. It's always used as a way of combating mechanical vibrations, such as foot fall traffic or even bass. I see it as a decoupling mechanism more than a mass mechanism.
> 
> I could be completely wrong but, again, I don't recall ever seeing it in the context of a mass unit.


Ted also explained it as a means of decoupling, the plywood was for mass


----------



## cgott42

granroth said:


> I need to stress again that you really should be contacting a structural engineer about this. It's one thing if soundproofing advice or implementation isn't up to snuff -- at worst it'll just be louder than you prefer. Not even remotely life and death. If advice about a structural matter is wrong, then it absolutely can be life and death!
> 
> IF your floor was clearly over-engineered or you weren't even remotely close to the limits, then I'd feel more comfortable making proclamations based off of published span tables and such. Your floor is definitely closer to the edge than that, though. Close enough that the details very much matter.
> 
> So... find a local structural engineer and ask if he can just give you an off-the-record opinion and not a full sealed plan. Some might not. You'll almost surely find one who will... you might have to have him come out for an estimate (officially) and then just pay him cash for the opinion. That couple-hundred dollars opinion would be worth every penny from a peace of mind perspective!


Thanks, I needed to hear that, I think i'll heed your advice. Though kinda worried about getting someone who when he hears that I have 3 layers of 5/8" drywall hanging there already will flip out.
Also, do they need to gain any access to the joists? last thing I want to is open a hole.


----------



## granroth

cgott42 said:


> Also, do they need to gain any access to the joists? last thing I want to is open a hole.


Not if you know the exact details -- joist size; length; support points; type of bracing; etc.


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## cgott42

granroth said:


> Not if you know the exact details -- joist size; length; support points; type of bracing; etc.


Unfortunately all I know is the joist size, length.
What will they need to do?


----------



## jackforceus

*Soundproofing questions*

I'm planning to finish my basement with a home theater. For the sound proofing solution, I'm planning to use
Roxul (Safe 'n' Sound), Db-3, Drywall, Green Glue, Another drywall.

Is it good enough to isolate most of the sound or do I need to nessarily go with the hat channel / RSIC clips? Am I compromising by not going with the hat channel / RSIC? Please advice


----------



## granroth

cgott42 said:


> Unfortunately all I know is the joist size, length.
> What will they need to do?


At this point, we're well out of my area of expertise.  Give a couple engineers a call and see what they say!


----------



## granroth

jackforceus said:


> I'm planning to finish my basement with a home theater. For the sound proofing solution, I'm planning to use
> Roxul (Safe 'n' Sound), Db-3, Drywall, Green Glue, Another drywall.
> 
> Is it good enough to isolate most of the sound or do I need to nessarily go with the hat channel / RSIC clips? Am I compromising by not going with the hat channel / RSIC? Please advice


That's impossible to say without knowing what your goals are. There is no such thing as an objective "good enough" since "good enough" is going to 100% depend on how much sound attenuation an individual wants. A 20dB dip at the mid to high frequencies might be enough for some people, but might not even be remotely close to others.

Also, what's the thinking behind using DB-3?


----------



## jackforceus

Thanks For the response.

http://www.homedepot.com/p/Unbranded-dB-3-48-in-x-8-ft-Acoustical-Barrier-DB348X96BX/100663624

- I have heard decent reviews who have installed db3 for their home theaters. Not sure it will be 100% helpful, but my thoughts being adding a layer of sound proof material could dampen the sound
- My goal is not hear any Low frequency sound coming from the subs (that bothered me a lot on my previous home theater where I didn't install any sound proofing)
- The room is 22 ft * 15 ft with 9ft ceining
- Do I need to insulate my floor as well?

Does this help?


----------



## BasementBob

DB-3 is Mass Loaded Vinyl (MLV).

Installation can be seen in here on YouTube.

MLV is more expensive per pound than drywall.


----------



## jackforceus

- Am I in the right path with Roxul, Db3, Drywall / GG / Drywall? 
- Should I remove the Db3 and just go with Roxul, Drywall / GG / Drywall?
- Should I go with Hat channel, RSIC, Roxul, Drywall / GG / Drywall?

I would like to avoid hat channel, RSIC if that doesn't compromise sound isolation. Are there any other recommendations? 

Thanks


----------



## ckronengold

Neophyte soundproofing question here (apologies in advance). 

I've got a basement media room that had a drop ceiling already installed. I'm trying to figure out a short term (re: cheap, now, better) and long term strategy (when the wife is done spending money in the rest of the house) to try and contain the sound leakage. 

I'm wondering how much improvement I'll get if I stuff the joists with good quality pink stuff. Right now its about 1/4 filled with crappy 20 year old insulation. 

I also want to replace the drop ceiling. Was wondering if you can go with 1 layer of drywall at first, and then green glue a second layer on later, or if thats just a ridiculous idea. 

I think I can gain about 4-5" by ditching the drop ceiling.

Probably worth mentioning that the wife is getting a new kitchen, knocking down a few walls, and making the whole first floor one big, open room, including a new floor. While reading the SoundProofingCompany's website, I saw the solution that included adding drywall and greenglue under the subfloor, and going to discuss that immediately with her and our contractor. Hopefully I can tackle the problem from the floor side as well as from the basement ceiling side.


----------



## granroth

jackforceus said:


> Thanks For the response.
> 
> http://www.homedepot.com/p/Unbranded-dB-3-48-in-x-8-ft-Acoustical-Barrier-DB348X96BX/100663624
> 
> - I have heard decent reviews who have installed db3 for their home theaters. Not sure it will be 100% helpful, but my thoughts being adding a layer of sound proof material could dampen the sound
> - My goal is not hear any Low frequency sound coming from the subs (that bothered me a lot on my previous home theater where I didn't install any sound proofing)
> - The room is 22 ft * 15 ft with 9ft ceining
> - Do I need to insulate my floor as well?
> 
> Does this help?


As Bob mentioned, DB-3 is essentially mass loaded vinyl (MLV) and, as such, is more suited for places where the flexibility is needed. That's why it's so popular in automotive sound control as well as adding mass to irregularly shaped structures. It's almost never worth it if you can instead use something like drywall with Green Glue, since the combination of the two will outperform MLV and at notably less cost. Since you're already doing double drywall plus Green Glue, I'd just skip the DB-3.

But... if your goal is to not hear low frequency effects (LFE) from the subs, then you may very well be disappointed with the results of your efforts. LFE is notoriously difficult to fully tamp down. Really, the only thing that is guaranteed to work is a thick solid concrete wall.

Even then, though, it does depend on how loud you play movies and what level the subs are at. If you're hitting 105 dB at 20Hz, then yeah, it'll be a problem if you don't have a lot of mass in play. If you're typically above 50hz or so and maybe at only 80-90dB, then you have a chance.

The key is you are missing the decoupling part of the soundproofing. Please read the first post in this thread and the two main introduction links in there. That will give you a very solid basis for how this all works.

At the very high level, soundproofing is most effective in the following order : Decoupling, Mass, Damping, Absorption. You can create a solution using just Mass and below, but you're giving up a LOT of the attenuation by skimping on the Decoupling. That's what the clips and channel (or staggered studs or double walls) will give you.

But really, start with the intro to this thread. I think it'll answer some of your questions and possibly give you some new ones that you didn't think of.


----------



## granroth

ckronengold said:


> Neophyte soundproofing question here (apologies in advance).
> 
> I've got a basement media room that had a drop ceiling already installed. I'm trying to figure out a short term (re: cheap, now, better) and long term strategy (when the wife is done spending money in the rest of the house) to try and contain the sound leakage.
> 
> I'm wondering how much improvement I'll get if I stuff the joists with good quality pink stuff. Right now its about 1/4 filled with crappy 20 year old insulation.
> 
> I also want to replace the drop ceiling. Was wondering if you can go with 1 layer of drywall at first, and then green glue a second layer on later, or if thats just a ridiculous idea.
> 
> I think I can gain about 4-5" by ditching the drop ceiling.
> 
> Probably worth mentioning that the wife is getting a new kitchen, knocking down a few walls, and making the whole first floor one big, open room, including a new floor. While reading the SoundProofingCompany's website, I saw the solution that included adding drywall and greenglue under the subfloor, and going to discuss that immediately with her and our contractor. Hopefully I can tackle the problem from the floor side as well as from the basement ceiling side.


First, yes, you can absolutely put up one layer of drywall now and then put up another layer with Green Glue or QuietGlue Pro at a later time. The only real advantage to doing it all at once is the fact that you only need to deal with the (prodigious) mess and expense of finishing once, instead of twice. Plus getting the benefits of the soundproofing now rather than later, I guess.

Loosely filling the joists with newer fiberglass batts will help a little, since I see some gaps and such now. It won't help a lot, though. Insulation tends to be the most effective when used in concert with more mass and damping (and decoupling). That is, adding the insulation will help a little; doing that with one layer of drywall with help a lot more; doing that with two layers of drywall and a damping compound will help even more (a lot more).

I think you're on the right track by reading the Soundproofing Company website. That has a lot of excellent detail and an especially good page on ceiling soundproofing. That will do a better job than me in detailing what your options are.


----------



## jackforceus

granroth said:


> As Bob mentioned, DB-3 is essentially mass loaded vinyl (MLV) and, as such, is more suited for places where the flexibility is needed. That's why it's so popular in automotive sound control as well as adding mass to irregularly shaped structures. It's almost never worth it if you can instead use something like drywall with Green Glue, since the combination of the two will outperform MLV and at notably less cost. Since you're already doing double drywall plus Green Glue, I'd just skip the DB-3.
> 
> But... if your goal is to not hear low frequency effects (LFE) from the subs, then you may very well be disappointed with the results of your efforts. LFE is notoriously difficult to fully tamp down. Really, the only thing that is guaranteed to work is a thick solid concrete wall.
> 
> Even then, though, it does depend on how loud you play movies and what level the subs are at. If you're hitting 105 dB at 20Hz, then yeah, it'll be a problem if you don't have a lot of mass in play. If you're typically above 50hz or so and maybe at only 80-90dB, then you have a chance.
> 
> The key is you are missing the decoupling part of the soundproofing. Please read the first post in this thread and the two main introduction links in there. That will give you a very solid basis for how this all works.
> 
> At the very high level, soundproofing is most effective in the following order : Decoupling, Mass, Damping, Absorption. You can create a solution using just Mass and below, but you're giving up a LOT of the attenuation by skimping on the Decoupling. That's what the clips and channel (or staggered studs or double walls) will give you.
> 
> But really, start with the intro to this thread. I think it'll answer some of your questions and possibly give you some new ones that you didn't think of.


Thanks a lot Granroth. Very helpful. I'll certainly read through
As I understand, Roxul, Hat channel, RSIC, DW / GG / DW would be the best combination from your input.

Questions:
- Different folks use different insulation. Is there an insulation that you would recommend over roxul?
- How about floor insulation? Should I run any layer of sheet under the carpet?


----------



## granroth

jackforceus said:


> - Different folks use different insulation. Is there an insulation that you would recommend over roxul?
> - How about floor insulation? Should I run any layer of sheet under the carpet?


Generally speaking, the best bang for the buck with insulation is the standard batts of fiberglass ("pink fluffy"). There are mild differences between the types, but not typically enough to notice or to justify the cost difference.

As far as floor insulation goes, don't think of it has insulation when it comes to soundproofing. Actual floor insulation tends to be rigid foam based, which is excellent for reducing heat transfer but pretty terrible for sound attenuation.

If you want the next level of soundproofing, then yeah, you can absolutely float your floors. You'd use a product like Serenity Mat and then put a layer or layers of OSB or plywood over that and then your normal flooring (carpet or such) on top. This has been proven to be very effective.

I will say, though, that with soundproofing, the devil is in the details. It's very easy to screw up one step in the process or implement a solution slightly wrong and get far worse results than you expect. I mention that because when you're getting into the realm of floating a floor, then you're into a much higher cost tier and are searching for a top-notch solution. At this level, you're spending a lot of money to eek out the final bit of gains. If it's not done exactly right, though, then you'll not get the extreme levels of performance you paid for and that extra money is wasted.

So what I'm saying is that if you're looking for the highest level of soundproofing solution, then you absolutely should hire a professional. Anything else would likely be wasting money.


----------



## ckronengold

granroth said:


> First, yes, you can absolutely put up one layer of drywall now and then put up another layer with Green Glue or QuietGlue Pro at a later time.
> 
> Loosely filling the joists with newer fiberglass batts will help a little, since I see some gaps and such now. It won't help a lot, though. Insulation tends to be the most effective when used in concert with more mass and damping (and decoupling).
> 
> I think you're on the right track by reading the Soundproofing Company website. That has a lot of excellent detail and an especially good page on ceiling soundproofing.


Thanks! Spoke w our contractor, since they started demo yesterday. Explained what I wanted to accomplish, and what I thought we needed to do. 

I'm leading towards Solution #4 (GreenGlue & Drywall under the subfloor) to get started. http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/

The contractor can do the work under the subfloor, and we can tackle the ceiling in the basement theater area later. But as long as the floors are up, it makes sense to tackle the under-floor components. I don't think the wife would let me rip up the new floor.


----------



## ivanny04

*Building a sound proof box to block very low frequencies*

*I am working on aproject and have questions about sound proofing. I want to build a rectangular box, withinside dimensions of about 27 x 24 inches x 5 ft, and make it sound proof. My main goal would be to make it block out "sound" that is around8 - 200 Hz. I understand the lower endof that is below the range of human hearing. I'd also be somewhat concernedabout frequencies above 20 KHz.*

*It had beensuggested to me that I do something like first build a box out of 1/2 inchplywood - with the desired outside dimensions. The bottom would be covered with about 1 to 2 inches of sand, at anangle. On top of that would be a pieceof plywood leaving a gap of about 3 inches on all 4 sides. Then another 1 to 2inches of sand, at an opposite angle. *

*I'd then build ashell with the desired inside dimensions, with sides that are parallel to thesides of the outer box, to rest on top of that layer of sand, with a gap of 3inches on all 4 sides. I'd then placesheets of plywood in between the internal shell and outer box, at angles,filling the gaps all the way around with more sand.

*
*So, I'd end up withan inner shell, a layer of sand, sheets of plywood at slightly different angles to the walls of theshell, another layer of sand, and then the outer box.*

*The theory as itwas explained to me was that sound will travel through two walls that haveparallel surfaces more easily than two walls that have surfaces that are atslight angles to each other. The sand furtherattenuates the sound because the sound waves hit each sand particle, which thentransfers that energy to a neighboring sand particles, but slightlyattenuated. *

*It was suggested tome that sand would be better suited to block out the very low frequencies thatI wish to block.*

*Assuming this makessense ... would it be best to use very fine grain sand, or larger grain of sand? Would there be a better type ofmaterial to use besides plywood ?*


----------



## granroth

ivanny04 said:


> I am working on a project and have questions about sound proofing. I want to build a rectangular box, with inside dimensions of about 27 x 24 inches x 5 ft, and make it sound proof. My main goal would be to make it block out "sound" that is around 8 - 200 Hz. I understand the lower end of that is below the range of human hearing. I'd also be somewhat concerned about frequencies above 20 KHz.


I'd like to start from the top -- it's not physically possible to make a truly sound proof box. Rather, you are looking for a solution that reduces the transmission loss of specific frequencies at given input levels to some desired output level.

That may sound like I'm splitting hairs, but it's not. If whatever you are using to generate the noise is only outputting 50dB and you only need to attenuate it to 30dB, then quite a few solutions will be "sound proof". But if you're generating 20Hz tones at 120dB and need to get it down to 20dB... the nothing you described will come even a little bit close to being "sound proof".

So to start, what will be your input levels and what are your desired output levels?


----------



## ivanny04

granroth said:


> I'd like to start from the top -- it's not physically possible to make a truly sound proof box. Rather, you are looking for a solution that reduces the transmission loss of specific frequencies at given input levels to some desired output level.
> 
> That may sound like I'm splitting hairs, but it's not. If whatever you are using to generate the noise is only outputting 50dB and you only need to attenuate it to 30dB, then quite a few solutions will be "sound proof". But if you're generating 20Hz tones at 120dB and need to get it down to 20dB... the nothing you described will come even a little bit close to being "sound proof".
> 
> So to start, what will be your input levels and what are your desired output levels?




I should have specified that I am NOT generating the "sound" - it is outside of my control, and I want a 'space' that is as free of that sound as is possible. I do not wish to attenuate it by any specific amount, other than as much as possible, without spending a fortune.


----------



## granroth

ivanny04 said:


> I should have specified that I am NOT generating the "sound" - it is outside of my control, and I want a 'space' that is as free of that sound as is possible. I do not wish to attenuate it by any specific amount, other than as much as possible, without spending a fortune.


I'll admit that I cannot visualize what your enclosure looks like, so I won't directly comment on it. As for whether or not it'll work to your level of expectations -- sure, since you don't really have any set expectations. It is possible that you have some internal unvoiced expectations that are unrealistic for such a small enclosure, though. Impossible to say.

I will comment on a few of the _general_ premises, though.

Sand works very well with low frequencies. The more, the better. It works even better than concrete, which is the typical material used for bass attenuation. It is hard to work with, though, as it is practically guaranteed to leak or spill over time. You do need a lot of it to make a very notable difference.

Putting the walls on angles will do very little for soundproofing. Angled walls can do wonders for scattering sound inside of an acoustically controlled space, but when trying to stop sound waves (especially low frequency ones), the wall will vibrate just as much as if it was perpendicular to the sound. The one benefit of an angled wall is that you may end up having notably more mass behind part of the wall and that extra mass will absolutely help. It's not likely worth doing, though.

1/2" plywood isn't as good as quite a few other sheet goods when it comes to sound control. The key is that you want it as massive as possible. In general, drywall > MDF > plywood and thicker is always better than thinner.


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## BasementBob

granroth said:


> 1/2 inch plywood isn't as good as quite a few other sheet goods when it comes to sound control.


and

1/2 inch plywood isn't as good as drywall when it comes to *fire* control. It's good as sheathing for bracing, such as with a cripple wall against earthquakes. And structurally able to screw things to the wall later.


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## ckronengold

granroth said:


> Generally speaking, the best bang for the buck with insulation is the standard batts of fiberglass ("pink fluffy"). There are mild differences between the types, but not typically enough to notice or to justify the cost difference.


Is there any real benefit to the Owens Corning QuietZone® Noise Control Solutions with PureFiber® Technology?? Or is that just a bunch of marketing voodoo for the same standard pink stuff? 

http://insulation.owenscorning.com/homeowners/renovation/products/quietzone/


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## granroth

ckronengold said:


> Is there any real benefit to the Owens Corning QuietZone® Noise Control Solutions with PureFiber® Technology?? Or is that just a bunch of marketing voodoo for the same standard pink stuff?
> 
> http://insulation.owenscorning.com/homeowners/renovation/products/quietzone/


Looks like marketing to me. They don't seem to publish any absorption coefficients that show a difference between it and the normal batts. Their listed wall assemblies also have pretty much the same rating as the tested assemblies with normal batts. They probably _are_ the same wall assemblies since I highly doubt that Owens-Corning paid for a full suite of laboratory tested walls and then didn't publish the detailed results. When you spend that kind of money, you're going to show it off!


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## ckronengold

Well, that changed quickly. After explaining in more detail and showing pictures of putting actual drywall between the joists, the contractor didn't think we'd be able to do it, given how much HVAC and plumbing is running through them. No reason to only seal off half the joists, I guess. 

We aren't ripping up the entire sub floor, either. So we're going to have to go with a Serenity Matt (or similar) over the sub floor and under the new floor. 

So now I'm faced with the choices that I was hoping to avoid. If I'm going to be forced (by the wife, at the contractors suggestion) that our best move is to stick with a drop ceiling, can anyone recommend the best drop ceiling tiles for noise reduction? Also, what would you stuff the joists with? Roxul S&S? Or something else? 

Maybe the best move is to bring in a sound specialist / home theater builder to weigh in with the contractor? 



ckronengold said:


> Thanks! Spoke w our contractor, since they started demo yesterday. Explained what I wanted to accomplish, and what I thought we needed to do.
> 
> I'm leading towards Solution #4 (GreenGlue & Drywall under the subfloor) to get started. http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/


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## mtbdudex

*x-ray solid slab sandwich door with lead in middle*

Sharing here, this morning I went to get x-rays for my 6 month post right side complete hip operation, healing is on track. 
My Titanium pieces are fusing nicely to the leg and hip bone 

While in the x-ray room with the door open I noticed how heavy/massive it is, 5 hinges and all.
It's a solid slab sandwich with lead in the middle! Veneer on both sides.
Did not get the whole door profile, but these edge views show the construction, I thought neat.
I told the tech I was "into" HT stuff and would it be ok for me to rap it with my fist to see how solid it felt, she said "sure", as I was there 7:30am 1st and basically empty office. Man it was rock solid dead THUD, no resonance.
Light rap, medium rap, and pretty heavy rap all came back as a THUD.







.









This does not show the hinge side, but the door was hanging in this huge steel thick frame - much more sturdy than your typical office steel frame, makes me wonder if for the ultimate HT soundproofing effort instead of using a wood frame this should be looked at.


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## BasementBob

mtbdudex: 
Reminds me of the Rod Gervais door -- {standard solid core door, sheet of 8 psf sheet lead, 3/4 inch plywood} -- with the lead and plywood being held back 1 inch on both sides and top for weather stripping.

[mentioned in his book 'Home Recording Studio Build it like the pros' and elsewhere]


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## ivanny04

Should haveexplained better perhaps.I am notgenerating any noise.There exists noisethat is not under my control.I have notmeasured, analyzed the noise.I feel itmore then I hear it.I want the insideof the box to be free of as much of the noise existing outside the box aspossible.


So, while one maymeasure the noise at XX, or whatever, I don't really care.The noise is there, I want to block as muchof it as possible.The fact that I feelit more then hear suggested to me it is mostly low frequency noise.


I hope that makemore sense.


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## ivanny04

*I want to block noise that is not under my control*

Should haveexplained better perhaps.I am notgenerating any noise. There exists noisethat is not under my control. I have notmeasured, analyzed the noise. I feel itmore then I hear it. I want the insideof the box to be free of as much of the noise existing outside the box aspossible.

So, while one maymeasure the noise at XX, or whatever, I don't really care. The noise is there, I want to block as muchof it as possible. The fact that I feelit more then hear suggested to me it is mostly low frequency noise.

I hope that makemore sense.


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## granroth

mtbdudex said:


> While in the x-ray room with the door open I noticed how heavy/massive it is, 5 hinges and all.
> It's a solid slab sandwich with lead in the middle! Veneer on both sides.





BasementBob said:


> mtbdudex:
> Reminds me of the Rod Gervais door -- {standard solid core door, sheet of 8 psf sheet lead, 3/4 inch plywood} -- with the lead and plywood being held back 1 inch on both sides and top for weather stripping.
> 
> [mentioned in his book 'Home Recording Studio Build it like the pros' and elsewhere]


That was my first thought, too. This is main part of it:










I priced out 8psf lead -- it would cost at least $500 and if ordered online, shipping would be brutal due to the 200lb weight of it.

Obviously very effective, though!



mtbdudex said:


> This does not show the hinge side, but the door was hanging in this huge steel thick frame - much more sturdy than your typical office steel frame, makes me wonder if for the ultimate HT soundproofing effort instead of using a wood frame this should be looked at.


Interesting thought. I'd assume the steel frame was there for structural reasons rather than acoustic ones, since the door is so heavy (500lbs or more, maybe?) My intuition is that the steel frame would be mildly to notably worse from a soundproofing aspect than a wood frame.
@BasementBob, what's your thoughts on steel frames vs wood frames?


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## BasementBob

granroth said:


> BasementBob: what's your thoughts on steel frames vs wood frames?


I don't recall any studies on the topic of steel vs wood door jambs (lots of studies/concerns on walls with steel studs vs wood studs). Concrete filled steel jambs can be quite strong and massive (google image 'residential vault door', and 'TankHead Blast Door' which is both massive and air tight), and might not even turn to dust due to open/close flexing.


I was looking at these the other day for something else, but I think they could hold up a door.
http://seblog.strongtie.com/wp-content/uploads/2014/12/Strong_Frame_SMF.jpg
http://seblog.strongtie.com/wp-content/uploads/2014/12/SMF-Install.jpg




granroth said:


> I priced out 8psf lead -- it would cost at least $500 and if ordered online, shipping would be brutal due to the 200lb weight of it


Then this post of mine here, about 2800 pound nuclear biological chemical blast doors, may be overkill from your perspective.


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## BasementBob

granroth said:


> Interesting thought. I'd assume the steel frame was there for structural reasons rather than acoustic ones


The primary reason for steel instead of wood there would be to prevent radiation from leaving the room. Wood is biologic, and won't stop radiation.
Then there's fire prevention (many hospitals have patients that can't run a 5 minute mile when the fire alarm goes off, so fire resistant materials are used), and steel can take gurney impacts better than wood. Within limits -- I think it was a wood door with steel/lead lining for example.
And lastly, something structural to hold up the door without warping. There's probably something behind that steel to take the weight, but the steel itself won't warp with changes in moisture, and no warping means no radiation gaps
If they happen to get any acoustic benefits from structure with excessive mass, my bet is that's mostly a pleasant side effect of other concerns. X-rays aren't that noisy, compared to MRI/CT-scan.


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## ronny31

BasementBob said:


> The primary reason for steel instead of wood there would be to prevent radiation from leaving the room. Wood is biologic, and won't stop radiation.
> Then there's fire prevention (many hospitals have patients that can't run a 5 minute mile when the fire alarm goes off, so fire resistant materials are used), and steel can take gurney impacts better than wood. Within limits -- I think it was a wood door with steel/lead lining for example.
> And lastly, something structural to hold up the door without warping. There's probably something behind that steel to take the weight, but the steel itself won't warp with changes in moisture, and no warping means no radiation gaps
> If they happen to get any acoustic benefits from structure with excessive mass, my bet is that's mostly a pleasant side effect of other concerns. X-rays aren't that noisy, compared to MRI/CT-scan.


he didn't suggest they use it for its acoustical properties, but that we can use the properties of such heavy doors for their acoustical properties. Or copy the properties with other materials.

FYI, X-rays travels in straight lines, so these doors don't have airtight seals, the lead just have to overlap the lead in the doorframe which overlaps with the lead or concrete in the wall.


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## pr0lab

Hello! 
A contractor insulated my outer walls so I can save energy during the winter using GreenFiber material (not entirely sure if this was the same exact product branding but the material looked identical). I asked him if it’s possible to insulate my ceiling using the same material to prevent the impact noise from the footsteps of my upstairs neighbors and he said that it’s possible and I will reach the desired outcome. I wanted to check if anybody had experience with this kind of insulation and whether it will actually solve my problem or impact noise from upstairs?


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## cgott42

I have a sound proof (decoupled DW+GG+DW+GG+DW) basement HT room in the basement, and a 1st floor dining room situated above it. I'm trying to keep the LFE which comes from some intense movie scenes from bothering those in the dining room above as part of a new flooring (for the dining room) project
On the soundproofing company's website it has 3 install options - one option has the serenity mat + plywood + GG + plywood below the new flooring.
For floating floor installs - it just recommends serenity mat + new flooring (i.e. w/o the plywood/GG sandwich).
Wouldn't the plywood/GG sandwich provide significant LFE blockage - i.e. not including it with the floating floor option - would result in significantly less blockage (unless the serenity mat itself is enough)? (I'd ask Ted, but figured I'd post here to discuss the theory , until I'm ready to buy )
Also , if I take a piece of the serenity mat, and stand above it - would that provide a test even before laying down the new floating flooring


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## ronny31

cgott42, we've established way long ago that stiffness works rather well on low frequencies. Plywood alone isn't really stiff. I'd go thick hardwood, then some sound absorbing mats and then laminate floor or whatever. That's if you already have good enough high frequency sound transmission loss. If you possibly could, laying a new concrete floor (like an inch or two thick in all) would be very effective to stop low frequencies. Could have some nice heating (and even cooling) cables in it and ceramic tiles or stone tiles. 
Lighter options, like just mats and GG and whatnot, is not effective for stopping low frequencies. Some here would argue it does stop low frequencies, but anything you put there stops a little bit, that does not make it good.


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## nonstopdoc1

1. Can Serenity Mat be used with carpet on a concrete floor?

2. Is carpet + serenity mat enough for soundproofing a concrete basement floor in a low ht basement(concrete to joist ht of 7'6")?

3. In a "room within room" construction, do you need double stud wall in addition to the exterior concrete wall or one interior wall separated from the outer exterior wall is sufficient?

Any advice is appreciated. Thanks!!


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## cgott42

ronny31 said:


> cgott42, we've established way long ago that stiffness works rather well on low frequencies. Plywood alone isn't really stiff. I'd go thick hardwood, then some sound absorbing mats and then laminate floor or whatever. That's if you already have good enough high frequency sound transmission loss. If you possibly could, laying a new concrete floor (like an inch or two thick in all) would be very effective to stop low frequencies. Could have some nice heating (and even cooling) cables in it and ceramic tiles or stone tiles.
> Lighter options, like just mats and GG and whatnot, is not effective for stopping low frequencies. Some here would argue it does stop low frequencies, but anything you put there stops a little bit, that does not make it good.


Yep, my high freq. stoppage is great, just the low freq shaking of the floor above the HT. My real Q is what's the minimum nec. to achieve my max. requirement. So before having a structural engineer come to see what the joists can handle, and then adding concrete, multiple layers of plywood (would OSB be better?) + GG or whatever it can handle- I want to first simply lay down the serenity mat, and then a single section of hardwood (or just a 4x8 plywood sheet)- (i.e. do I fee any rumbling on the floor below where I'm standing)- I want to know if this is a fair test of what the final effect would be or if it wont' be an accurate representation until the full hardwood flooring is put down?


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## granroth

nonstopdoc1 said:


> 1. Can Serenity Mat be used with carpet on a concrete floor?
> 
> 2. Is carpet + serenity mat enough for soundproofing a concrete basement floor in a low ht basement(concrete to joist ht of 7'6")?
> 
> 3. In a "room within room" construction, do you need double stud wall in addition to the exterior concrete wall or one interior wall separated from the outer exterior wall is sufficient?
> 
> Any advice is appreciated. Thanks!!


1. Best ask Soundproofing Company directly about that.

2. Asking if ANY solution is is "enough" is a meaningless question without specifying your precise requirements for soundproofing.

3. "room within a room" only refers to two decoupled parallel walls, so if you already have an exterior concrete wall, then that's one of the two walls. Just build a new decoupled in inside of that.


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## granroth

ronny31 said:


> cgott42, we've established way long ago that stiffness works rather well on low frequencies. Plywood alone isn't really stiff.


Well... no. Whereas the mass law doesn't really hold true at frequencies below the resonant frequency and stiffness starts to matter more, it's the INVERSE of stiffness that matters more. That is, you want "floppy mass" for the low frequencies. Or just have huge amounts of mass.

As far as I've been able to tell (or have been told by the acoustics pros), the only way to effectively stop frequencies below the resonant frequency is to use lots of concrete or sand. The direct question of if it's possible to get effective transmission loss of ULF in a "stick frame" residential home got an answer of "no" (essentially).


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## nonstopdoc1

granroth said:


> 1. Best ask Soundproofing Company directly about that.
> 
> 2. Asking if ANY solution is is "enough" is a meaningless question without specifying your precise requirements for soundproofing.
> 
> 3. "room within a room" only refers to two decoupled parallel walls, so if you already have an exterior concrete wall, then that's one of the two walls. Just build a new decoupled in inside of that.



Thanks for your reply. What would be a decent option for soundproofing a concrete floor in a low height basement?


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## LoudDad

nonstopdoc1 said:


> Thanks for your reply. What would be a decent option for soundproofing a concrete floor in a low height basement?


Why do you think you need to soundproof your concrete floor in a basement?
I have also considered this but it looks like most people don't bother.
Either just carpet and under pad or a subfloor for comfort.


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## nonstopdoc1

LoudDad said:


> Why do you think you need to soundproof your concrete floor in a basement?
> I have also considered this but it looks like most people don't bother.
> Either just carpet and under pad or a subfloor for comfort.



I have been reading this forum and the articles on soundproofing company. Everyone seem to agree that soundproofing HT is all or none project hence wondering if leaving concrete floor untreated would defeat the whole process of soundproofing rest of the walls and ceiling.


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## ronny31

I imagine the reason you soundproof the floor would be to prevent echoes, not much else. And also not having a cold floor all the time.


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## granroth

nonstopdoc1 said:


> I have been reading this forum and the articles on soundproofing company. Everyone seem to agree that soundproofing HT is all or none project hence wondering if leaving concrete floor untreated would defeat the whole process of soundproofing rest of the walls and ceiling.


This is a common misconception of soundproofing. It is NOT all or none -- if it were, then pretty much all soundproofing efforts in this forum would be useless, since none of us have the budget or space to truly go "all in". It's all compromises based on needs, budget, and space.

What is true is that if you have specific soundproofing requirements and you implement a solution that should fit those requirements, then you MUST do it properly and sweat the details or else you may not get the performance that you think you're going to get. An example would be if you needed a 65dB attenuation of the STC frequencies and so you build a wall with a STC 65 rating... but then have a door with a STC 20 rating. The end result is that you would not get STC 65 out of that wall, but rather some value between 20 and 65.

Now... I keep stressing the point the crucial first step of any soundproofing effort is first identifying what frequencies you want to stop and how much attenuation do you need. If you don't know what you want to target, then any "solution" is just throwing darts at a board and hoping that it'll somehow work.

So on to the idea of leaving a concrete floor untreated. See above -- it depends on what you are trying to do, and what the other solutions in place are. If you are in a basement and are not a bass-head, then treating the floor probably won't give you any benefits that would matter. If you are on shared floor with living space and will have notable amounts of bass, then yeah, treating the floors might have a place in your solution.


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## KanosWRX

Sound Proofing is far from all or nothing. When designing the sound proofing aspects for my home theater I first came to the realization unless I had tens of thousands of dollars to spend on the home theater I would have to make compromises. I probably ended up spending about 25k on mine including components. Not a lot compared to what others spend but still a good chunk of cash, I also hired a contractor to do most of the build. Anyways, I think as long as you follow the basics of what everyone says on these forums you will have a really well sound proofed room. Will you be able to listen at reference levels and not hear anything outside the room or upstairs, no... But most people can deal with some sound leakage. If you can't then step one, hire a professional and prepare to spend over 50k at least. So for most people aim for that 80-90% solution and you will be happy. Again do the basics, isolate all walls and ceilings with clips and channels or double studs where necessary. Do double drywall and green glue, fill all cavities with insulation, caulk seams where possible. I think those alone get you to the 80-90% solution. After that you get diminishing returns, for every dollar more you spend you get a little less sound proofing. In my case I can listen at sound levels higher than I personally care to listen at and can barely hear anything upstairs. If I listen at a loud, but acceptable level, then you can't hear anything upstairs. You can check out my build thread to see what I did. But like I said, for the majority of the people here, realize you don't need to do everything for a great sound proofed room, you will overwhelm yourself if you think you need to. Aim for that 80-90% if your on a low to normal budget like most people. If you have money to burn and want that 100% solution you need to get a professional in my opinion.


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## DougF

My contractor put a vertical PVC sewer pipe in the new construction 2 x 4 wall directly behind the prime listening position. The couch is to be flush against that wall. He says dry wall alone will eliminate sound. I dont buy it and am concerned that I will hear the water whenever its running. Moving the pipe or the seating isnt an option. And there is very little room between pipe and drywall. Any suggeations for thin material that can fit between pipe and drywall and minimize sound? 

Thanks


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## granroth

DougF said:


> My contractor put a vertical PVC sewer pipe in the new construction 2 x 4 wall directly behind the prime listening position. The couch is to be flush against that wall. He says dry wall alone will eliminate sound. I dont buy it and am concerned that I will hear the water whenever its running. Moving the pipe or the seating isnt an option. And there is very little room between pipe and drywall. Any suggeations for thin material that can fit between pipe and drywall and minimize sound?


First, you are absolutely right that one sheet of drywall is NOT stop the noise from a pipe like that. We have a pex water pipe in the walls of one our bedrooms and it's definitely audible when water is flowing. The pipe is in a fiberglass insulated section and covered with one sheet of 1/2" drywall.

So what can you do? The only thing I can think of that might work is adding more mass plus damping. At a minimum, two layers of 5/8" Type X drywall with Green Glue or QuietGlue Pro in between. A third layer might be justified.

I hesitate giving any real predictions, though, since I'm not aware of any published tests solving this particular problem.

You _may_ consider just having people not flush anything while you're watching a movie...


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## btinindy

It is a vertical section of pipe? Cast iron vertical risers are much quieter. I had a vertical section of pipe replaced with cast iron when we took the great room down to the studs and I can't hear when someone flushes or takes a shower upstairs. It won't last as long as the PVC, but will outlive me for sure!


BT1


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## BasementBob

The usual techniques for dealing with pipes are:
a) moving them at least a room away from the quiet room, and
b) wrapping them in mass loaded vinyl in the 1 pound per square foot to 2 pounds per square foot range. Combined with standard home theatre room construction {filling the surrounding cavity with insulation, and then the usual two layers of drywall on the room} it's not too bad. There are some pipe wraps (mass loaded vinyl) that have their own adhesive, and many more that require duct tape to hold them into place.There are some soundproofing pipe wraps that have a 1/2 inch foam decoupling layer, but I suspect that's a waste when combined with the 'standard home theatre room construction'.


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## mtbdudex

^^could you specially box and isolate that stud cavity with the pipe, floor to ceiling, think like a long backer box that gives mass and damping just there.....

This is std 2x4 construction, is the pipe 2" PVC or? 


Via Mikes brain/thumb interface, LLAP


----------



## pr0lab

pr0lab said:


> Hello!
> A contractor insulated my outer walls so I can save energy during the winter using GreenFiber material (not entirely sure if this was the same exact product branding but the material looked identical). I asked him if it’s possible to insulate my ceiling using the same material to prevent the impact noise from the footsteps of my upstairs neighbors and he said that it’s possible and I will reach the desired outcome. I wanted to check if anybody had experience with this kind of insulation and whether it will actually solve my problem or impact noise from upstairs?


anybody?


----------



## granroth

pr0lab said:


> Hello!
> A contractor insulated my outer walls so I can save energy during the winter using GreenFiber material (not entirely sure if this was the same exact product branding but the material looked identical). I asked him if it’s possible to insulate my ceiling using the same material to prevent the impact noise from the footsteps of my upstairs neighbors and he said that it’s possible and I will reach the desired outcome. I wanted to check if anybody had experience with this kind of insulation and whether it will actually solve my problem or impact noise from upstairs?


The short answer is "no, it won't solve your problem".

Absorption, be it from fluffy fiberglass or packed cellulose, does play an important role in sound attenuation but it's a comparatively minor one compared to such steps as decoupling and adding mass. You will rarely get a desired outcome by only adding absorption. Impact noise is one of the trickier sound problems to mitigate, too, so it takes more effort to really combat.

Ideally you'd tackle an impact noise problem by starting with the floor, but since that's your neighbor, that's almost surely not an option. That leaves treating the ceiling. This page does a great job of explaining the problem as well as detail a number of possible solutions: http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/


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## cgott42

Followup on prior post 


Quick summary of situation - (I have a HT in the basement , and soundproofed via decoupling (clips, hatchannels) and DW+GG+DW+GG - for walls and ceiling ). Works nicely, I can watch and not disturb anyone. One minor exception, is some intense LFE scenes cause a slight, but noticeable shaking in direct room directly above the HT (and some scenes cause the china to shake in the breakfront - not good for WAF ).
Identifying type of issue - flanking or direct vibration - I put my ears on the walls of the 1st Floor dining room and don't hear / feel anything, however when putting my ear to the floor - you can not on ly hear the intense LFE, but can feel things shake so that it vibrates my cheekbone resting on the floor) Direct transfer through joists (HT ceiling/dining room floor)
Call Ted - he recommended the serenity mat + Plywood+GG+Plywood. Before ordering checking w/structural engineer:
Call structural engineer - to confirm joists can handle the load (as recommended here)- he said he can tell me over the phone. so I gave him the info he wanted about the room (waiting on his response):
joists 16" O.C.
distance from girder (which joists rest on) to the concrete ~10.5', distance from girder to next girder = ~11'.9", distance from there to next concrete = ~13'4"
weight already on joists:
below - 5/8" (non light weight) DW x 3
above = subfloor + hardwood
Soffit = (2) 2x12 x 22' wood + DW; (2) 5/8" DW 10"x22' - _perhaps the soffit needs another layer of DW+GG (I figured the add'l mass of the solid wood vs. DW would compensate, and be OK w/ Wood + GG+DW)_
 
 
*pre-Test* - I found someone that had a little serenity mat left over from his job, so I put that on a section of the existing dining room floor and put a piece of plywood on that (so that it was completely resting on the serenity mat and no contact with the floor - as the serenity mat serves to decouple)- then played Batman Dark Knight 2 scene with bat bike chasing the joker who's blowing everything up, played at max. volume where I'd play it if I wanted the maximum enjoyment and didn't have to concern myself with anyone else)
Results pre-Test 1 - slightly less vibration, but still definitely noticeable (cheekbones still vibrates) - just slightly less so.
*Pre-Test 1b* - fold over the remaining serenity mat (not under the plywood) and rest it on top of the plywood - I didn't have enough to cover the full plywood on top, but covered about 4x3'), then put a 12"x12" piece of 9/16" OSB I had lying around on top of that. So above the joists I had: subfloor + existing (old) hardwood + serenity mat + wood + GG + wood (granted not the same as subfloor + existing (old) hardwood + serenity mat + wood + serenity mat + wood but worth testing). Again was still able to feel the vibrations, perhaps? less so, but still clear.
Any ideas, thoughts, suggestions?


----------



## ronny31

cgott42 said:


> Any ideas, thoughts, suggestions?


Hm, tiles not an option? The only way I know of to stop bass powerful enough to shake your cheekbones would need some more solid material than cheapo American building materials for throwing up homes asap for returning soldiers. See if there's some nearby db-drag events you can go to. Go to one of those, see how much effort and what they do to stop the bass escaping the cars. See if you find a car without sound dampening that make your cheekbones shake, then find a car with sound dampening with an equal power stereo that give the wanted level of sound dampening. Then see what they have done to achieve it. That should give you some idea of what is needed, and if its even feasible to achieve in your house. Cheekbone shaking bass isn't stopped by plywood and drywall unless you build an actual bunker with it.
EDIT: I see now that your cheekbone shakes when you rest your face against the floor, not when standing upright. That makes it slightly more feasible to accomplish with drywall and whatnot. But I fear you will probably need stone slates or ceramic tiles or a thin concrete floor with ceramic tiles. Or a bunch of Butyl mats like they use in the car world to stop vibrations in the roofs and all the big panels (essentially adds weight and some structural rigidity as well as being difficult for sound to travel through, being tough yet liquid).


----------



## ckronengold

I hate having to admit defeat, but I am going to have to live with my current HVAC in my basement ceiling, limiting my options. 

So I am going to be forced to keep my drop ceiling for a while longer than I had hoped. And so incremental improvement and 'doing the best with what you've got' is going to be my approach. 

I started looking at ceiling tiles from Roxul's Roxfon division (http://www.rockfon.com/u/website_product/19307/Rockfon® Sonar™ dB/) and was just reading about Ceilume http://www.ceilume.com/acoustical/StratfordNRC85/White/

Wondering if anyone has any other recommendations. I know they aren't going to solve my problem, but I'm still looking to minimize the amount of sound that is leaking through my ceiling. 

Similarly, I'm wondering about what to use for stuffing the ceiling. Curious if anyone has any experience or thoughts on SonicGuard drop ceiling insulation? http://www.ceilume.com/accessories/Soniguard/ 

Essentially, I know I'm barking up the wrong tree, but trying to figure out how to make the best of it, and would really appreciate any input or suggestions that aren't "two layers of 5/8" with Green Glue."


----------



## ctviggen

granroth said:


> The short answer is "no, it won't solve your problem".
> 
> Absorption, be it from fluffy fiberglass or packed cellulose, does play an important role in sound attenuation but it's a comparatively minor one compared to such steps as decoupling and adding mass. You will rarely get a desired outcome by only adding absorption. Impact noise is one of the trickier sound problems to mitigate, too, so it takes more effort to really combat.
> 
> Ideally you'd tackle an impact noise problem by starting with the floor, but since that's your neighbor, that's almost surely not an option. That leaves treating the ceiling. This page does a great job of explaining the problem as well as detail a number of possible solutions: http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/


I can attest to this. I added fiberglass between my ceiling joists for a ceiling in my family room and below a kitchen, but every time the kids did something on the tiles in the kitchen, it was as if they did the same thing in the family room. I had no decoupling and also did not put drywall attached to the subfloor. Impact noise traveled unabated through the floor.


----------



## HTownTheater

im curious what everyone's thoughts are on the following expectations.

this room is on the second floor, the walls on the left and right are attic space and have insulation but no drywall on the attic side, the front wall (screen wall) is an exterior wall insulated, and the back wall has the openings shown in the picture. the Back wall is about 2 feet deep and hollow dry wall both sides. Floor is over master bath and closet but not master bedroom.

I dont expect this room to be sound proof, i would like to cut the volume down heard throughout the house by half if not more. will closing in the arches, installing a solid door (safe and sound with seal kit) accomplish this? should i also have the wall filled with denim? 

appreciate any insight you might have as to if my expectations are in line or not...


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## cgott42

cgott42 said:


> Followup on prior post
> 
> 
> Quick summary of situation - (I have a HT in the basement , and soundproofed via decoupling (clips, hatchannels) and DW+GG+DW+GG - for walls and ceiling ). Works nicely, I can watch and not disturb anyone. One minor exception, is some intense LFE scenes cause a slight, but noticeable shaking in direct room directly above the HT (and some scenes cause the china to shake in the breakfront - not good for WAF ).
> Identifying type of issue - flanking or direct vibration - I put my ears on the walls of the 1st Floor dining room and don't hear / feel anything, however when putting my ear to the floor - you can not on ly hear the intense LFE, but can feel things shake so that it vibrates my cheekbone resting on the floor) Direct transfer through joists (HT ceiling/dining room floor)
> Call Ted - he recommended the serenity mat + Plywood+GG+Plywood. Before ordering checking w/structural engineer:
> Call structural engineer - to confirm joists can handle the load (as recommended here)- he said he can tell me over the phone. so I gave him the info he wanted about the room (waiting on his response):
> joists 16" O.C.
> distance from girder (which joists rest on) to the concrete ~10.5', distance from girder to next girder = ~11'.9", distance from there to next concrete = ~13'4"
> weight already on joists:
> below - 5/8" (non light weight) DW x 3
> above = subfloor + hardwood
> Soffit = (2) 2x12 x 22' wood + DW; (2) 5/8" DW 10"x22' - _perhaps the soffit needs another layer of DW+GG (I figured the add'l mass of the solid wood vs. DW would compensate, and be OK w/ Wood + GG+DW)_
> 
> 
> *pre-Test* - I found someone that had a little serenity mat left over from his job, so I put that on a section of the existing dining room floor and put a piece of plywood on that (so that it was completely resting on the serenity mat and no contact with the floor - as the serenity mat serves to decouple)- then played Batman Dark Knight 2 scene with bat bike chasing the joker who's blowing everything up, played at max. volume where I'd play it if I wanted the maximum enjoyment and didn't have to concern myself with anyone else)
> Results pre-Test 1 - slightly less vibration, but still definitely noticeable (cheekbones still vibrates) - just slightly less so.
> *Pre-Test 1b* - fold over the remaining serenity mat (not under the plywood) and rest it on top of the plywood - I didn't have enough to cover the full plywood on top, but covered about 4x3'), then put a 12"x12" piece of 9/16" OSB I had lying around on top of that. So above the joists I had: subfloor + existing (old) hardwood + serenity mat + wood + GG + wood (granted not the same as subfloor + existing (old) hardwood + serenity mat + wood + serenity mat + wood but worth testing). Again was still able to feel the vibrations, perhaps? less so, but still clear.
> Any ideas, thoughts, suggestions?


Finally got results from structural engineer - he said given the span between girder (about 10') it is safe to hold the current load - namely the (3 layers of 5/8" DW HT ceiling ) + the existing floor above the HT (plywood + hardwood flooring) - and I can add an add'l layer of plywood + hardwood flooring When I asked if I can add 2 layers of plywood (to green glue them) - he said no.
How much does the serenity mat weight differ from plywood towards my cap?
So my Q now is what to do?:


Green Glue new layer of plywood to existing (old) hardwood floor and put new flooring on top of that
Remove existing hardwood (yuch) and green glue old plywood to new plywood and add serenity mat then new flooring on top of that. (makes the most sense)
Any better options that you can think of ?


----------



## granroth

cgott42 said:


> Finally got results from structural engineer - he said given the span between girder (about 10') it is safe to hold the current load - namely the (3 layers of 5/8" DW HT ceiling ) + the existing floor above the HT (plywood + hardwood flooring) - and I can add an add'l layer of plywood + hardwood flooring When I asked if I can add 2 layers of plywood (to green glue them) - he said no.
> How much does the serenity mat weight differ from plywood towards my cap?
> So my Q now is what to do?:
> 
> 
> Green Glue new layer of plywood to existing (old) hardwood floor and put new flooring on top of that
> Remove existing hardwood (yuch) and green glue old plywood to new plywood and add serenity mat then new flooring on top of that. (makes the most sense)
> Any better options that you can think of ?


Honestly, neither of those options are likely to give you enough of an impact to justify their cost. LFE respects mass, mass, and more mass... and very little else. Green Glue helps a bit in the form of damping and Serenity Mat does so in in the form of decoupling, but again, neither makes a _significant_ different to LFE.

Since adding a lot more mass isn't in the cards, I suggest taking an alternate route.

That is, if the problem isn't the NOISE from LFE but rather the VIBRATIONS, then selectively attach the vibrating objects. For instance, if there are pictures on the walls then place little rubber strips behind them. If there are places in a china cabinet, then first try putting the shelves on rubber dampers and if that doesn't work, then put the plates themselves on rubber. The key is to find the things that make noise and give them the opportunity to move noiselessly.


----------



## ronny31

What granroth said. Though I have to point out that rigidity would remove significant amounts of low frequency db. In maximum db car builds everything is made to be as rigid as possible. The speaker enclosure is built to be rock solid, literally, and then what its placed on is made to be rock solid, the panels are made to be rock solid, and everything else besides is made stronger and heavier. 
To get this, there are things you can do besides changing the floor/ceiling. You don't want to get some heavy furniture to place somewhat evenly across the surface?  Simulates people standing on the car to limit roof movement for added db containment.


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## Blaine Morrissey

Anyone have good ideas to seal off a double door? I was debating between a full length threshold with a gasket running across the bottom. Or one of those automatic door bottoms where the gasket drops down when the door closes. My doors are solid oak and there is about a .5 inch gap between the bottom of the door and the tile. See the attached pic right now I am using some of those draft control door things but they have to go. 

I was thinking about these.....

http://www.tmhardware.com/Automatic-Door-Bottom-High-Sound-Surface-Mounted.html

or one of these.......I'd have to cut out a hole for the pin on the one door. 

http://www.tmhardware.com/Acoustic-Threshold-4-Aluminum-Latching-Panic-Exit-Design-with-Q-Lon-Seal-.25-H.html


----------



## cgott42

_thanks for the ideas/input_


granroth said:


> ...That is, if the problem isn't the NOISE from LFE but rather the VIBRATIONS, then selectively attach the vibrating objects. For instance, if there are pictures on the walls then place little rubber strips behind them. If there are places in a china cabinet, then first try putting the shelves on rubber dampers and if that doesn't work, then put the plates themselves on rubber. The key is to find the things that make noise and give them the opportunity to move noiselessly.


_Nice idea - although most of the noise is coming from the floor vibrating, and things on the wall seem to be fine, however part of the noise does come from dishes in the breakfront rattling - so I can add things to the shelf to stop that._


ronny31 said:


> What granroth said. Though I have to point out that rigidity would remove significant amounts of low frequency db. ...To get this, there are things you can do besides changing the floor/ceiling. You don't want to get some heavy furniture to place somewhat evenly across the surface?  Simulates people standing on the car to limit roof movement for added db containment.





ronny31 said:


> Hm, tiles not an option? ...I see now that your cheekbone shakes when you rest your face against the floor, not when standing upright. That makes it slightly more feasible to accomplish with drywall and whatnot. But I fear you will probably need stone slates or ceramic tiles or a thin concrete floor with ceramic tiles. Or a bunch of Butyl mats like they use in the car world to stop vibrations in the roofs and all the big panels (essentially adds weight and some structural rigidity as well as being difficult for sound to travel through, being tough yet liquid).


_Somewhat good news, my wife decided to go with tiles instead of hardwood/bamboo._
_So given that I currently have the existing subfloor + existing hardwood. and have OK to add another layer of plywood + hardwood. (I'm viewing this as a load budget that I have to work within, so I can redo if I keep within the budget)_
_How do redo to use tiles for better LFE containment?_

_I found the following table of weights for common building materials - given that I currently have_
_approx. 14.75 psi (3 layers of 5/8" DW + subfloor + Hardwood) adding an additional layer of plywood (~2.5psi) + hardwood (4 psi) = 21.25 total "budget"._
_so instead of adding plywood + hardwood, I can remove the existing hardwood (recoup 4psi to "spend") and replace with 7/16 cement backerboard (3psi) + ceramic tile (4.7 psi) , perhaps add plywood (~2.5psi) w/GG - or perhaps the serenity mat instead... just tossing out an idea - let me know what's the best use_


_Also FWIW, I already have the green glue and serenity mat (though I could resell if it's not nec. to recoup the $)_


----------



## ronny31

cgott42 said:


> _How do redo to use tiles for better LFE containment?_


Basically, in Norway we would use floor "sponplate" on top of the joists. They're really really solid, then just do the tiling plaster/concrete in a thin layer enough to get the tiles to stick well. To get more low frequency containment I would simply use two layers 22mm "sponplate" glued with epoxy (hardens properly) with large tiles on top. With high frequency sound transmission efforts on the ceiling underneath the floor the total sound transmission loss is always good, even on the low frequencies. The result with be practically 44mm concrete with tiles on top. But seeing as you guys don't have this form of sheet material (at least its difficult to find), I gather that you have to float your own thin concrete floor with glassfiber reinforcement netting, on top of whatever material is on top of the joists. Like a 1 inch concrete floor, then tiles on top. Tiles alone would work if you could laminate the right set of wooden material with something that hardens properly (like epoxy). But one layer plywood alone (or plywood with GG between) has too much give. The bigger the tiles the more they help (tiles themselves are very stiff). 
Surely there must be something equivalent to "sponplate" in the US, what else is used on top of the joists in floors in the US? Surely the plywood alone is so flexible its like walking in a bouncy castle?


----------



## homeowner2014

We recently hired a contractor to soundproof the ceiling of a bedroom. He removed the existing ceiling, used RSIC-V clips, 20 guage drywall furring channel and hung two layers of 5/8 drywall(lite weight, about 64 pounds per sheet). 


It significantly cut down sound but when someone walks can hear noise, probably from hat channel or something. It is similar to sound coming from floor squeak.


We do not know what went wrong. Really disappointed. Can anyone suggest any remedy.


----------



## granroth

homeowner2014 said:


> We recently hired a contractor to soundproof the ceiling of a bedroom. He removed the existing ceiling, used RSIC-V clips, 20 guage drywall furring channel and hung two layers of 5/8 drywall(lite weight, about 64 pounds per sheet).
> 
> It significantly cut down sound but when someone walks can hear noise, probably from hat channel or something. It is similar to sound coming from floor squeak.
> 
> We do not know what went wrong. Really disappointed. Can anyone suggest any remedy.


If it's specifically a squeak that you're hearing, then it is almost surely the channel and clip doing that. In that case, it's either going to be incorrect installation or bad clip(s). Your only remedy that I can think of is to redo the ceiling -- perhaps only the part that has the squeaky clips, though.

Here's another thread talking about this issue: http://www.avsforum.com/forum/19-de...ction/1100518-squeaky-rsic-v-clip-advice.html

As an aside, it's very curious that your contractor used light weight 5/8 drywall. I mean, if you're going to use two layers of 5/8, then why short circuit the results by using the light weight stuff? Strange.


----------



## nandkisham

*Decouple a Stage in second floor*

Hello, I am a newbie to the forum. Trying to build a dedicated HT on Second floor (converting from a media room) in a new house.

I have just completed the demo to increase the room from 13x17 to 13x22.5 (attic space)
I plan to go with a AT screen 

How do you truly decouple a stage on second floor? The joist in the extended floor potion are about 5" below the original subfloor. I have floated the new stage joist to rest on the subfloor base (2X4 on one side and hanging on LVL otherside. 
I have a new raised OSB for the stage. Should this be done after the sheet rock in the new section.

I plan to do DD with GG.

Any


----------



## cgott42

cgott42 said:


> _thanks for the ideas/input_
> 
> _Nice idea - although most of the noise is coming from the floor vibrating, and things on the wall seem to be fine, however part of the noise does come from dishes in the breakfront rattling - so I can add things to the shelf to stop that._
> 
> 
> 
> _Somewhat good news, my wife decided to go with tiles instead of hardwood/bamboo._
> _So given that I currently have the existing subfloor + existing hardwood. and have OK to add another layer of plywood + hardwood. (I'm viewing this as a load budget that I have to work within, so I can redo if I keep within the budget)_
> _How do redo to use tiles for better LFE containment?_
> 
> _I found the following table of weights for common building materials - given that I currently have_
> _approx. 14.75 psi (3 layers of 5/8" DW + subfloor + Hardwood) adding an additional layer of plywood (~2.5psi) + hardwood (4 psi) = 21.25 total "budget"._
> _so instead of adding plywood + hardwood, I can remove the existing hardwood (recoup 4psi to "spend") and replace with 7/16 cement backerboard (3psi) + ceramic tile (4.7 psi) , perhaps add plywood (~2.5psi) w/GG - or perhaps the serenity mat instead... just tossing out an idea - let me know what's the best use_
> 
> 
> _Also FWIW, I already have the green glue and serenity mat (though I could resell if it's not nec. to recoup the $)_


I just spoke with the engineer, and told him about my idea of removing the existing hardwood and replacing with 1/4" ceramic tile. He told me that (a) there's too much "deflection" (not sure what that means) for the tile and (b) that even if I remove the hardwood I'd be at risk by putting in tile. Based on my calc above I should be within the quota. I'm having trouble clarity and kinda get the impression that if I challenge him with my rough calc - he'll just snap back with a "do what you want, but you run the risk of it cracking" - which is good advice so long as he wasn't just being overly cautious to avoid putting in the time to think it through to get an accurate answer to how much I can add. - any ideas? (other than spending more $$ on another engineer). 

Also I'm wondering why my situation is any different from anyone else on the forum. Isn't (most) everyone putting 3 layers of 5/8" DW on the ceiling, and then loading the floor above with more than just a single layer of hardwood floor. My joists rest between the concrete foundation and girder 10' away and are spaced 16" o.c., and house built 1968 - all pretty standard, so wondering why other members would be able to support the load.

To complicate matters further, the wife is really into getting tile now - and won't appreciate me telling her that "btw, you know that black dungeon that you can't stand, which I spent a year away from you building, well now it's the reason why you can't get tiles in your dining room." Not to mention how she'll flip when she even hears the words "risk of floor cracking"...


----------



## pitviper33

cgott42 said:


> I just spoke with the engineer, and told him about my idea of removing the existing hardwood and replacing with 1/4" ceramic tile. He told me that (a) there's too much "deflection" (not sure what that means) for the tile and (b) that even if I remove the hardwood I'd be at risk by putting in tile. Based on my calc above I should be within the quota. I'm having trouble clarity and kinda get the impression that if I challenge him with my rough calc - he'll just snap back with a "do what you want, but you run the risk of it cracking" - which is good advice so long as he wasn't just being overly cautious to avoid putting in the time to think it through to get an accurate answer to how much I can add. - any ideas? (other than spending more $$ on another engineer).
> 
> Also I'm wondering why my situation is any different from anyone else on the forum. Isn't (most) everyone putting 3 layers of 5/8" DW on the ceiling, and then loading the floor above with more than just a single layer of hardwood floor. My joists rest between the concrete foundation and girder 10' away and are spaced 16" o.c., and house built 1968 - all pretty standard, so wondering why other members would be able to support the load.
> 
> To complicate matters further, the wife is really into getting tile now - and won't appreciate me telling her that "btw, you know that black dungeon that you can't stand, which I spent a year away from you building, well now it's the reason why you can't get tiles in your dining room." Not to mention how she'll flip when she even hears the words "risk of floor cracking"...


The deflection he's talking about isn't because of the static weight on the floor. He's talking about deflection from live loads. Basically he's saying your floor isn't stiff enough for tile. When you walk on it, dance on it, live on it, it flexes a little. Tile floors can't handle much flex without cracking. He's saying yours flexes a little too much.

Just as a reference point, here's a nice calculator. http://www.johnbridge.com/vbulletin/deflecto.pl
But don't trust the calculator more than you trust the engineer. The calculator makes a lot of assumptions. The engineer knows your house and knows which of those assumptions to make and which he can't. He might also be considering the type of tile you have in mind, which affects the allowable deflection.

Important note: Neither tile floors nor residential structures are my areas of expertise. This is just my current understanding, in hopes that it helps.


----------



## Apgood

By deflection he means when you have a live load (e.g. someone walking across the floor) there is too much movement in the floor for tiles. This is a common issue with timber floors. Even if you remove the timber flooring and put down fibre cement sheeting you'll get movement unless it is very thick, but the thick stuff is very heavy and the timber joists and bearers might not have the capacity bear the weight of the fc sheeting and tiles.
Normally the best thing for laying tiles is a suspended concrete floor and 2nd best is steel joists with thick fibre cement sheeting. 

If those aren't viable then you could look at reinforcing the joists and bearers with either steel plates or beams/ joists and then putting thick fc sheeting on top, but you'll need to refer to the local building code as to what they allow. Also you probably still get a bit of movement but so long as it's only 1-2mm you should be fine. Consideration also needs to be given to where the sheeting joins. It might be necessary to have movement joints at those points in the tiling.

A good engineer or builder should be able to advise you on these things.


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## ronny31

Hm, buy some soft bottom slippers and ear plugs for the people that walk upstairs from the "black dungeon".


----------



## cgott42

pitviper33 said:


> The deflection he's talking about isn't because of the static weight on the floor. He's talking about deflection from live loads. Basically he's saying your floor isn't stiff enough for tile. When you walk on it, dance on it, live on it, it flexes a little. Tile floors can't handle much flex without cracking. He's saying yours flexes a little too much.
> 
> Just as a reference point, here's a nice calculator. http://www.johnbridge.com/vbulletin/deflecto.pl
> But don't trust the calculator more than you trust the engineer. The calculator makes a lot of assumptions. The engineer knows your house and knows which of those assumptions to make and which he can't. He might also be considering the type of tile you have in mind, which affects the allowable deflection.
> 
> Important note: Neither tile floors nor residential structures are my areas of expertise. This is just my current understanding, in hopes that it helps.





Apgood said:


> By deflection he means when you have a live load (e.g. someone walking across the floor) there is too much movement in the floor for tiles. This is a common issue with timber floors. Even if you remove the timber flooring and put down fibre cement sheeting you'll get movement unless it is very thick, but the thick stuff is very heavy and the timber joists and bearers might not have the capacity bear the weight of the fc sheeting and tiles.
> Normally the best thing for laying tiles is a suspended concrete floor and 2nd best is steel joists with thick fibre cement sheeting.
> 
> If those aren't viable then you could look at reinforcing the joists and bearers with either steel plates or beams/ joists and then putting thick fc sheeting on top, but you'll need to refer to the local building code as to what they allow. Also you probably still get a bit of movement but so long as it's only 1-2mm you should be fine. Consideration also needs to be given to where the sheeting joins. It might be necessary to have movement joints at those points in the tiling.
> 
> A good engineer or builder should be able to advise you on these things.


Thanks also I forgot to mention, that the engineer hasn't actually come to the house, he just asked me to measure the distance between girders, spacing of joists, and age of home. So based on what you're both saying I guess he's figuring the deflection in the average home (my age) would require the thick fibre cement sheeting as you mention, and that he feels that would be too heavy of a "dead load" to bear given the 3 layers of DW below the joists??

Does that sound right? If so, it sounds like I'm back to hardwood and with a Q on what to do to stop the vibrations in the floor.
Also - he charged me $150 for the opinion (w/o coming to the house) - does that seem reasonable?


----------



## Apgood

Talk to your engineer about what options there are. You may still be able to have tiles if you reinforce the girders and joists to handle the extra load and reduce deflection to an acceptable amount, but it will almost certainly mean that ceiling in the room below will need to be removed first.
What options are available will depend on your local building code which your engineer should know.

Can't comment on his rate as I live in Australia.


----------



## cgott42

Apgood said:


> Talk to your engineer about what options there are. You may still be able to have tiles if you reinforce the girders and joists to handle the extra load and reduce deflection to an acceptable amount, but it will almost certainly mean that ceiling in the room below will need to be removed first.
> What options are available will depend on your local building code which your engineer should know.
> 
> Can't comment on his rate as I live in Australia.


thanks - but redoing the ceiling is not an option. :-(


----------



## marlon1925

*Help please*

Hi sirs,

I am planning to build a dedicated home theater in the newly constructed extension of my existing house.

All walls, floor and ceiling are concrete. I couldn't find hat channels and clips in the local shops so I am planning to just use woods for both ceiling and wall studs.

I would appreciate if someone could share a diagram how to isolate walls and ceiling from existing concrete walls and ceiling. 

Thanks a lot.


----------



## ronny31

marlon1925 said:


> Hi sirs,
> 
> I am planning to build a dedicated home theater in the newly constructed extension of my existing house.
> 
> All walls, floor and ceiling are concrete. I couldn't find hat channels and clips in the local shops so I am planning to just use woods for both ceiling and wall studs.
> 
> I would appreciate if someone could share a diagram how to isolate walls and ceiling from existing concrete walls and ceiling.
> 
> Thanks a lot.


Would be nice to see building blueprints. Depends a bit on dimensions and whatnot. You might not need any special sound-proofing in all walls, if there's a concrete wall all round the room and separating it from the rest of the house. Just some sound proofing in the wall that separates the HT from the house. If there's nothing above the HT you don't need much in the ceiling, and then the build is basically acoustic treatment to avoid an echoic concrete room sound. The concrete itself is excellent for keeping sound inside the room. What concrete is it, true concrete or ceramic Leca type? What windows, where, what doors, where? All these things affect where you'd want to put your sound proofing money.


----------



## marlon1925

ronny31 said:


> Would be nice to see building blueprints. Depends a bit on dimensions and whatnot. You might not need any special sound-proofing in all walls, if there's a concrete wall all round the room and separating it from the rest of the house. Just some sound proofing in the wall that separates the HT from the house. If there's nothing above the HT you don't need much in the ceiling, and then the build is basically acoustic treatment to avoid an echoic concrete room sound. The concrete itself is excellent for keeping sound inside the room. What concrete is it, true concrete or ceramic Leca type? What windows, where, what doors, where? All these things affect where you'd want to put your sound proofing money.


Thank you for your reply sir.

Im living in a subdivision near the main gate and the vehicles passing by causes noise. All walls are concrete, 4' CHB plus plastering. My proposed HT room is located on the 2nd floor of the 3-storey house extension being built now. From the ground a stairway is leading to the one and only door and there will be now windows. 

The room is 4.6M(W) X 7.4M(L) X 3M(H).


----------



## DarkNight15

Hi Guys, great information and helpful tips in this thread! I had posted this in another section but it might be better here. I just have a quick question. I'm in the early stages of planning a theater build. I have decided to build the theater inside a four car garage that I don't use, using room within a room method and am blessed with the amount of space I have at my disposal! The garage is detached from the house in the rear of our yard. It has been constructed with timber framing and weatherboard on the outside with a pitched roof to match the look of our house. My question is, because the framing is already present inside the garage is it just a case of filling the gaps with insulation followed by 2 inch gap, second frame>insulation covered in DD and GG?

I am aware I still need to use IB3 clips and other sound proofing techniques to sufficiently reduce noise. Or would it be better to add DD and GG between the already present joists in the wall to make soundproofing more effective? I'm not sure whether this would be of any benefit due to the drywall between wall joists not sitting flush against the existing weatherboards
Thanks


----------



## granroth

DarkNight15 said:


> Hi Guys, great information and helpful tips in this thread! I had posted this in another section but it might be better here. I just have a quick question. I'm in the early stages of planning a theater build. I have decided to build the theater inside a four car garage that I don't use, using room within a room method and am blessed with the amount of space I have at my disposal! The garage is detached from the house in the rear of our yard. It has been constructed with timber framing and weatherboard on the outside with a pitched roof to match the look of our house. My question is, because the framing is already present inside the garage is it just a case of filling the gaps with insulation followed by 2 inch gap, second frame>insulation covered in DD and GG?
> 
> I am aware I still need to use IB3 clips and other sound proofing techniques to sufficiently reduce noise. Or would it be better to add DD and GG between the already present joists in the wall to make soundproofing more effective? I'm not sure whether this would be of any benefit due to the drywall between wall joists not sitting flush against the existing weatherboards
> Thanks


A detached building will already give some level of soundproofing as-is, so you have a great start. If you have the room to do a full room-in-room method, then you have no need for clips and channels. Instead, just "float" your joists on the interior floating walls and you'll have a fully decoupled solution.

So yeah, just insulate between the bays of the existing framing, then add a gap, then create an interior frame that's also insulated, then two layers of drywall with Green Glue or QuietGlue Pro. Seal all joints with a 50-year caulk. Make sure all doors and windows are sealed tight while you're in there. Add as much mass as possible to the doors (and windows).

Beyond that, adding additional drywall and GG in between the existing wall frame will have only marginal improvements and not likely worth the cost. Plus, if it's not flush against the exterior siding, then yeah, you might actually make things somewhat worse by creating a triple leaf.

Sounds like you have the potential for a great space!


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## tcjohnsson

*Best soundproof wall assembly on limited space; new construction*

I'm in the process of designing a small 5-unit apartment building with small studio units for my employees. Each unit will have an integrated home theater. I understand the concept of diminishing returns on soundproofing investment but I am willing to spend a good chunk on soundproofing the 5 units (~$10-$15/SF budget). 

The issue is I have a _very _limited building footprint per unit to work with... so maximizing interior space is critical. I'd like to keep the entire wall assembly (between studio units) to no more than 5 or 6" in depth, if possible. Since space is a concern, double stud wall will not work for me. Staggered stud isn't really an option in such a shallow assembly. Currently looking at using 3 5/8" steel studs, R13 insulation, two layers of 1/2 drywall on both sides with GG sandwiched between all sheets (two tubes per sheet). This puts me at 5 5/8" thickness for all interior wall assemblies. GG's website states an impressive STC rating of 59 for this particular assembly. Using 5/8" drywall increases the STC rating to 61 but requires another 1/2" of floor space lost. 

Would adding resilient channel or sound clips+channel make a noticeable difference? Would going with a shallower stud and using either of these options improve the STC rating? Also, is wood a bad option? It will keep my cost down - all exterior walls are going to be constructed of wood. My understanding is the use of steel studs over wood partially reduces the additional value provided by resilient channel; this is why I'm considering using steel for interior non-load bearing walls. Does stud depth and resulting air cavity have a noticeable impact on the rating of the assembly; i.e. is 2 1/2" stud depth have a significant disadvantage to 3 1/2" stud depth? The STC ratings seem to reflect a significant difference for small 1/2" increases in wall cavity space. Please note that most of these walls will have plumbing (drains/vents, etc) and electrical inside of them. The only concern about using shallower studs (i.e. less than 3 1/2 studs) is that I need to source 50mm fiberglass; this material is not readily available in my area (R-13 is the shallowest). 

Also, any recommendations on the best floor assembly to reduce sound transmission and footfall noise are much appreciated. My architect is recommending I go with a standard wood joist system with pan and 2" concrete top layer. Cork mat and hardwood floor to go over the concrete top layer. I would then install R-19 insulation in the joist cavity and resilient channel perpendicular to the joist with 5/8 drywall ceiling to finish. Note that I will have a lot of holes in the ceiling for recessed lighting and recessed ceiling speakers so that would reduce the assembly's sound transmission effectiveness. Footfall noise and low frequency (bass from the sound systems) are the primary concern. I'm hoping the 2" of concrete with cork does a good job at addressing that. I would prefer to avoid using concrete entirely as the cost is significant (in addition to the pan and concrete, the structure needs to be beefed up to accommodate the additional weight) and there is some loss of ceiling height... but I am unsure of any other assembly that would address footfall noise and low frequency noise as effectively. I've heard GG sandwiched between two sheets of plywood can be effective but don't believe it gets close to that of 2" of concrete. 

Thank you in advance for any help.


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## ronny31

tcjohnsson said:


> I'm in the process of designing a small 5-unit apartment building with small studio units for my employees. Each unit will have an integrated home theater. I understand the concept of diminishing returns on soundproofing investment but I am willing to spend a good chunk on soundproofing the 5 units (~$10-$15/SF budget).
> 
> The issue is I have a _very _limited building footprint per unit to work with... so maximizing interior space is critical. I'd like to keep the entire wall assembly (between studio units) to no more than 5 or 6" in depth, if possible. Since space is a concern, double stud wall will not work for me. Staggered stud isn't really an option in such a shallow assembly. Currently looking at using 3 5/8" steel studs, R13 insulation, two layers of 1/2 drywall on both sides with GG sandwiched between all sheets (two tubes per sheet). This puts me at 5 5/8" thickness for all interior wall assemblies. GG's website states an impressive STC rating of 59 for this particular assembly. Using 5/8" drywall increases the STC rating to 61 but requires another 1/2" of floor space lost.
> 
> Would adding resilient channel or sound clips+channel make a noticeable difference? Would going with a shallower stud and using either of these options improve the STC rating? Also, is wood a bad option? It will keep my cost down - all exterior walls are going to be constructed of wood. My understanding is the use of steel studs over wood partially reduces the additional value provided by resilient channel; this is why I'm considering using steel for interior non-load bearing walls. Does stud depth and resulting air cavity have a noticeable impact on the rating of the assembly; i.e. is 2 1/2" stud depth have a significant disadvantage to 3 1/2" stud depth? The STC ratings seem to reflect a significant difference for small 1/2" increases in wall cavity space. Please note that most of these walls will have plumbing (drains/vents, etc) and electrical inside of them. The only concern about using shallower studs (i.e. less than 3 1/2 studs) is that I need to source 50mm fiberglass; this material is not readily available in my area (R-13 is the shallowest).
> 
> Also, any recommendations on the best floor assembly to reduce sound transmission and footfall noise are much appreciated. My architect is recommending I go with a standard wood joist system with pan and 2" concrete top layer. Cork mat and hardwood floor to go over the concrete top layer. I would then install R-19 insulation in the joist cavity and resilient channel perpendicular to the joist with 5/8 drywall ceiling to finish. Note that I will have a lot of holes in the ceiling for recessed lighting and recessed ceiling speakers so that would reduce the assembly's sound transmission effectiveness. Footfall noise and low frequency (bass from the sound systems) are the primary concern. I'm hoping the 2" of concrete with cork does a good job at addressing that. I would prefer to avoid using concrete entirely as the cost is significant (in addition to the pan and concrete, the structure needs to be beefed up to accommodate the additional weight) and there is some loss of ceiling height... but I am unsure of any other assembly that would address footfall noise and low frequency noise as effectively. I've heard GG sandwiched between two sheets of plywood can be effective but don't believe it gets close to that of 2" of concrete.
> 
> Thank you in advance for any help.


Dont know much about drywall, but I know something about concrete. 
Here's a profile view: 
_____
|x|___
|x|___
|x|___
|x|___
|x|___
x indicates stairwells, lines indicates solid steel reinforced concrete (except the left-most vertical line, which is normal wall, and the roof is normal wooden roof). Often used design in Norway. The main thing is to use solid doors with a small hallway for shoes and outer clothes (about two door widths or so, squared), with a somewhat decent door between the hallway and the apartment itself as well. Then little noise escapes out of the apartment. 
Bathroom goes against the concrete wall towards the stairwells, the HT outside that. Noise escaping out isn't as important. Livingroom+kitchen between HT+bathroom and bedrooms. Then you only need one concrete wall besides the ones pictured in profile above. Going through the appartment in the wall separating the bathroom and HT from the livingroom. Like this from above: 
_____ (normal wall not concrete)
|x|___ (concrete wall, bathroom, HT, with normal dividing wall, no one cares about HT noise while sitting on the crapper)
|x|
|x|
|x|___ (normal wall, not concrete. kitchen, livingroom, hallway, hallway doesn't need two layers concrete walls. 
|x|___ (normal wall, not concrete, bedrooms, separated by normal insulated wooden wall) 
The walls at the edge of the appartment don't go outside the concrete, but inside the concrete. Only the top layer of wooden boards that cover the walls actually cross the edge of the concrete floors. If the walls go outside the concrete the wall becomes a transmission line. Boards laid horisontally in overlapping way bottom to top. 
This design only requires 2 complete concrete walls that carry the load, with one column at the corner that has the largest span from the concrete load carrying walls (though some designs use a column at 2 or more corners). Its good for placing it above underground stuff, like a street or parking spaces or open cafe locale etc. 

Feel free to adjust it to your particular project.


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## granroth

tcjohnsson said:


> I'm in the process of designing a small 5-unit apartment building with small studio units for my employees. Each unit will have an integrated home theater. I understand the concept of diminishing returns on soundproofing investment but I am willing to spend a good chunk on soundproofing the 5 units (~$10-$15/SF budget).
> 
> The issue is I have a _very _limited building footprint per unit to work with... so maximizing interior space is critical. I'd like to keep the entire wall assembly (between studio units) to no more than 5 or 6" in depth, if possible. Since space is a concern, double stud wall will not work for me. Staggered stud isn't really an option in such a shallow assembly. Currently looking at using 3 5/8" steel studs, R13 insulation, two layers of 1/2 drywall on both sides with GG sandwiched between all sheets (two tubes per sheet). This puts me at 5 5/8" thickness for all interior wall assemblies. GG's website states an impressive STC rating of 59 for this particular assembly. Using 5/8" drywall increases the STC rating to 61 but requires another 1/2" of floor space lost.
> 
> Would adding resilient channel or sound clips+channel make a noticeable difference? Would going with a shallower stud and using either of these options improve the STC rating? Also, is wood a bad option? It will keep my cost down - all exterior walls are going to be constructed of wood. My understanding is the use of steel studs over wood partially reduces the additional value provided by resilient channel; this is why I'm considering using steel for interior non-load bearing walls. Does stud depth and resulting air cavity have a noticeable impact on the rating of the assembly; i.e. is 2 1/2" stud depth have a significant disadvantage to 3 1/2" stud depth? The STC ratings seem to reflect a significant difference for small 1/2" increases in wall cavity space. Please note that most of these walls will have plumbing (drains/vents, etc) and electrical inside of them. The only concern about using shallower studs (i.e. less than 3 1/2 studs) is that I need to source 50mm fiberglass; this material is not readily available in my area (R-13 is the shallowest).


Since you mentioned an architect, I'm assuming that this project will already be done under your local jurisdictions building code. If not, then it's imperative to check into that. I say that because quite a few jurisdictions have very specific requirements for multi-family properties and those often include requirements for soundproofing and fire protection between the units. If your local jurisdiction is like that, then your hands will be largely tied. If not, then you're free to implement all sorts of solutions.

Given that, yes, using clips+channel should make a notable difference since decoupling gives the biggest bang for the buck. That will definitely eat into your space, though, especially if losing 1/2" is so dear. Having a skinnier wall will definitely perform worse. I'm not sure what the end effect would be if you created skinnier walls and then used clips+channel to bring you back to just under 6". 

Honestly, a project like this with such specific and unusual requirements is precisely the type of project that benefits from a professional. Hire a pro that knows soundproofing and you'll get a customized solution that will absolutely work.


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## DarkNight15

granroth said:


> A detached building will already give some level of soundproofing as-is, so you have a great start. If you have the room to do a full room-in-room method, then you have no need for clips and channels. Instead, just "float" your joists on the interior floating walls and you'll have a fully decoupled solution.
> 
> So yeah, just insulate between the bays of the existing framing, then add a gap, then create an interior frame that's also insulated, then two layers of drywall with Green Glue or QuietGlue Pro. Seal all joints with a 50-year caulk. Make sure all doors and windows are sealed tight while you're in there. Add as much mass as possible to the doors (and windows).
> 
> Beyond that, adding additional drywall and GG in between the existing wall frame will have only marginal improvements and not likely worth the cost. Plus, if it's not flush against the exterior siding, then yeah, you might actually make things somewhat worse by creating a triple leaf.
> 
> Sounds like you have the potential for a great space!


Thanks heaps Granroth! That's a fantastic idea, I'll go with floating joists! Really appreciate your feedback


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## marlon1925

ronny31 said:


> Would be nice to see building blueprints. Depends a bit on dimensions and whatnot. You might not need any special sound-proofing in all walls, if there's a concrete wall all round the room and separating it from the rest of the house. Just some sound proofing in the wall that separates the HT from the house. If there's nothing above the HT you don't need much in the ceiling, and then the build is basically acoustic treatment to avoid an echoic concrete room sound. The concrete itself is excellent for keeping sound inside the room. What concrete is it, true concrete or ceramic Leca type? What windows, where, what doors, where? All these things affect where you'd want to put your sound proofing money.


This is the proposed layout of my ht room


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## jrref

I need some help, or advice, or opinions!
I live in an attached town home where my home theater is set up in my living room. One wall is common to my neighbor. The construction of the common wall is as follows:
5/8 inch sheet rock on both sides of a staggered wood studded wall, 16 inch on center with 6 inches of fiberglass insulation in between. The wall is about 9 inches in depth. While this construction is pretty good acoustically, the problem is that the top and bottom plates are common between the walls.


|X |
| |
| X|
| |
|X |
| |
| X|


| is 5/8 inch fireproof sheetrock
X is the 2x4 stud, staggered, 16 inch on center.
There is 6 inches of Pink fiberglass with no air gap between the studs.


The problem with this set up is that I could hear my neighbor if they are "hooting and hollering" while watching the game and I could barely hear the TV if it was loud. I never tested to see how much of my home theater sound he could hear but apparently I kept it low enough so it didn't bother him. I lived with this for many years keeping my sub very low and never played my stuff loud, until my neighbor went out and purchased a Sonos sound system for his music. The music from his Sonos speaker next to the common wall cut right through because he was playing it loud, all the way up at around 105 db as measured with my Radio Shack sound meter in his living room. Yep it sounded like he was at concert! Because I am on good terms with my neighbor, he let me adjust the Sonos settings by turning off the Dynamic Volume and lowering the bass quite a bit. I found that the Sonos-2 speaker has a bass reinforcement port which was vibrating the adjacent wall so bringing down the bass was a necessity.


Even with all the adjustments, I found that I would have to turn my TV up very loud when he was playing his music loud so I took the following steps:


1) I took down the sheet rock on my side of the common wall, removed all of the pink insulation.
2) I installed 3" Roxul Safe & Sound insulation in the cavities of the neighbors wall and another 3" in the cavities of my wall.
3) Also there remained a couple of inches of air gap in between. I think the total depth of the wall is about 9 inches.
4) I installed Quiet Puty over his and my electrical outlets in the wall.
5) I installed about 3 inches of Roxul Safe & Sound insulation at the top header of inside of the wall cavity to try to limit any transmitted sound going into the ceiling.
6) I replaced my sheet rock with Quiet Rock 5/8 inch with Quiet seal all around each sheet and in the seams, etc. I made everything as air tight as possible.


The results:
1) With my neighbors music playing 3/4 or less, I can't hear any sound. From 3/4 to 100%, full blast at 105 db in his living room, I can hear the music but its very low and about 45 -50 db on my side of the wall. If I have my home theater on, I can't hear his music but if it's totally quiet then you know it's on.
2) Even if he's having a party, I can't hear any speech unless they are yelling at the top of their lungs but it's barely audible.
3) The banging on the floor from dropping something or running I can still hear, no real change there but it doesn't happen much.


So while the sound proofing is vastly improved, i'm still experiencing the following:
1) I understand that it's very hard to limit the transmission of the bass and that if I had put a second layer of 5/8 sheet rock on my side, the greater mass would have helped but my neighbor has been cooperative and has lowered the bass so that's not really a problem.
2) In playing with his Sonos system it seems that when the volume on his side exceeds 80db that it starts to "overwhelm" the sound proofing capabilities of the wall because I start to hear frequencies in the mid range as well as the bass, but no higher frequencies.
3) When I was re-constructing the wall, with just the insulation installed, there wasn't much attenuation when testing before installing the Quiet Rock on my side which makes me believe that the insulation doesn't do too much but is part of the system overall.
4) I found from testing that I can play my home theater at pretty loud, around 80 db, and there is Zero sound heard on my neighbors side. If I turn it up, then the bass from the sub starts to cut through but apparently THERE IS SIGNIFICANTLY MORE SOUND PROOFING RESISTANCE FROM MY SIDE TO MY NEIGHBORS!


So my Question is, are these results typical? Was I expecting too much thinking I would have no sound transmission even when he's playing music at 105 db? From my description could I have done anything more, within reason of course? Why am I getting so much sound attenuation from my side to his and not vice versa? I have about 500 watts of home theater and he has 2 Sonos-2 speakers with no sub?


All I can come up with is that the sound from his side is making it into the frame of the wall and flanking over the top and bottom plates because all he has is one layer of 5/8 inch sheetrock where as on my side the Quiet Rock is preventing a lot of the sound from transmitting to the frame. I'm guessing that the only thing I could do at this point is to put a layer of Quiet Rock over the existing 5/8 inch sheet rock on my neighbors side. Also, one other thing, my neighbor's living room on the other side of the wall has very little acoustic suppressing material so it echo's a lot. All he has is a couple of leather couches, area rug, blinds but no curtains. Also during the summer if his windows are open I guess the sound pressure against the common wall is less so the transmitted sound is significantly less.


Any opinions, ideas, thoughts?
Thanks, in advance! John


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## granroth

jrref said:


> [snip]
> So my Question is, are these results typical? Was I expecting too much thinking I would have no sound transmission even when he's playing music at 105 db? From my description could I have done anything more, within reason of course? Why am I getting so much sound attenuation from my side to his and not vice versa? I have about 500 watts of home theater and he has 2 Sonos-2 speakers with no sub?


Your results are absolutely in line with any reasonable expectations on the performance of your system. To simplify matters, you can think of a wall as having a single sound attenuation value which is typically listed as an STC value. In reality, it's nowhere near that simple, but it's a good baseline for discussion. In your case, you have a moderately decoupled solution (staggered studs) with absorption and decent damping (the Quiet Rock). I haven't looked up the specs on that setup, but I'd guess it was somewhere in the STC 50 area (maybe better).

If it is doing STC 50, then we can roughly say that it's knocking 50dB off of whatever the source sound is. If your neighbor is rocking 105 dB, then you'll still hear 55 dB. That's not loud, but it's clearly audible.

If you don't want to hear your neighbor's 105 dB music, then you need to attenuate it down to your side's noise floor (or ambient noise). Let's say that's 30dB. That means you'd need a wall that can achieve 75 dB of sound reduction. That's quite a bit.

I honestly don't know what you could do right now to achieve that, given that you surely won't want to tear down the installed Quiet Rock. Adding another layer of Quiet Rock might give another 6dB of attenuation, which would be noticeable, but wouldn't completely solve your problem.


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## jrref

granroth said:


> Your results are absolutely in line with any reasonable expectations on the performance of your system. To simplify matters, you can think of a wall as having a single sound attenuation value which is typically listed as an STC value. In reality, it's nowhere near that simple, but it's a good baseline for discussion. In your case, you have a moderately decoupled solution (staggered studs) with absorption and decent damping (the Quiet Rock). I haven't looked up the specs on that setup, but I'd guess it was somewhere in the STC 50 area (maybe better).
> 
> If it is doing STC 50, then we can roughly say that it's knocking 50dB off of whatever the source sound is. If your neighbor is rocking 105 dB, then you'll still hear 55 dB. That's not loud, but it's clearly audible.
> 
> If you don't want to hear your neighbor's 105 dB music, then you need to attenuate it down to your side's noise floor (or ambient noise). Let's say that's 30dB. That means you'd need a wall that can achieve 75 dB of sound reduction. That's quite a bit.
> 
> I honestly don't know what you could do right now to achieve that, given that you surely won't want to tear down the installed Quiet Rock. Adding another layer of Quiet Rock might give another 6dB of attenuation, which would be noticeable, but wouldn't completely solve your problem.


Thanks for the feedback, I really appreciate it. Thinking back at all the research is did, even if I put up resilient channels or any of the other "exotic" methods, I really don't think I would have got significantly better results. If I had to go back in time a re-do it again, the only thing I might have done is put up 2 5/8 inch layers of sheetrock with green glue. I stayed away from this because of the difficulty of re-doing the floor and crown moldings, etc.. I think you are right, I really needed to get to an STC-60 or higher and the only way that was going to happen is with more mass. If I were to re-do everything, with my situation, would you have done it differently? I'm just curious. Thanks, John


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## granroth

jrref said:


> Thanks for the feedback, I really appreciate it. Thinking back at all the research is did, even if I put up resilient channels or any of the other "exotic" methods, I really don't think I would have got significantly better results. If I had to go back in time a re-do it again, the only thing I might have done is put up 2 5/8 inch layers of sheetrock with green glue. I stayed away from this because of the difficulty of re-doing the floor and crown moldings, etc.. I think you are right, I really needed to get to an STC-60 or higher and the only way that was going to happen is with more mass. If I were to re-do everything, with my situation, would you have done it differently? I'm just curious. Thanks, John


Right, you're essentially at the limits of a conventional (wood studs with drywall) wall assembly. You could get a few more dB attenuation if you also treated your neighbor's side (possibly even by adding layers on the inside of the drywall, between the studs).

Getting significantly better results would mean moving towards a much more massive solution, often involving lots of concrete. Also, flanking noise starts becoming a very noticeable part of the equation. That is, if you put a 8" thick concrete wall between your units but still had shared ceiling and floor joists (or shared slab), then your sound leakages will likely be coming through that point. Now we're looking at floating your floor and or ceiling.

In the end, I think you have some extremely high expectations since your solution sounds far better than what most people accomplish! If you can play a movie at 80-85dB (the typical SPL of most theaters) and your neighbor can't hear it, then that's awesome. If you can't hear your neighbors during a party unless they yell, then you're better than 99% of other townhome occupants. And if your only remaining issue is that the you can't damp your neighbor's 105dB noise completely... well, no reasonable person would expect that you could. 105dB is extraordinarily LOUD! That's a level that will cause permanent hearing loss if it's sustained long enough with no hearing protection. Your neighbor must be mostly deaf to be able to handle that volume for any extended period of time. You'd need an "overkill" solution to be able to handle that.


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## jrref

granroth said:


> Right, you're essentially at the limits of a conventional (wood studs with drywall) wall assembly. You could get a few more dB attenuation if you also treated your neighbor's side (possibly even by adding layers on the inside of the drywall, between the studs).
> 
> Getting significantly better results would mean moving towards a much more massive solution, often involving lots of concrete. Also, flanking noise starts becoming a very noticeable part of the equation. That is, if you put a 8" thick concrete wall between your units but still had shared ceiling and floor joists (or shared slab), then your sound leakages will likely be coming through that point. Now we're looking at floating your floor and or ceiling.
> 
> In the end, I think you have some extremely high expectations since your solution sounds far better than what most people accomplish! If you can play a movie at 80-85dB (the typical SPL of most theaters) and your neighbor can't hear it, then that's awesome. If you can't hear your neighbors during a party unless they yell, then you're better than 99% of other townhome occupants. And if your only remaining issue is that the you can't damp your neighbor's 105dB noise completely... well, no reasonable person would expect that you could. 105dB is extraordinarily LOUD! That's a level that will cause permanent hearing loss if it's sustained long enough with no hearing protection. Your neighbor must be mostly deaf to be able to handle that volume for any extended period of time. You'd need an "overkill" solution to be able to handle that.


Thanks for confirming this because I kept thinking that I could have done something better. As far as putting more sheet rock between the walls, from what I read, they want an air gap between for better isolation. As we were getting ready to put the quiet rock up I was looking at that. After all the insulation there was only an inch or two of space left so I decided not to go that route. But I did make everything as air tight as possible with all the materials I used. An interesting note: Before the soundproofing I could feel the wall vibrate when my neighbor was playing his music. After, no detectable vibration. The Quiet Rock is extremely dense and very heavy. When you knock on it compared to regular sheetrock, it's almost like you are knocking on concrete. It's a huge amount of mass. As per your comment about the music at 105 db, yep, you are exactly right, that is incredibly loud. So loud, especially on a Sonos system, that it sounds terrible and in my opinion is a ridiculous level to play music let alone the hearing damage. It's interesting that you mentioned that because on occasion i'll take to him and I have to repeat myself!


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## KanosWRX

I am surprised your friend can get 105db out of a Sonos system, but like you said must sound horrible at that level. I am surprised he isn't def yet. But maybe that's just the peeks and its normally at around 80db. Typically a reference level movie averages about 80db, but peeks to 105-115. I think you have done the most you can, minus adding drywall to his side and putting some green glue in between. In my HT I have two layers of 5/8 and green glue, isolated from other walls/joists with clips or double walls. Typically at 80db I can't hear much of anything but low frequencies upstairs. It's the bass that really gets me though, I have two Rythmik F12 subs, they shake the whole house now even with my sound proofing, just can't stop that vibration! Wife isn't happy about that, but I can turn the bass down some.


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## jrref

KanosWRX said:


> I am surprised your friend can get 105db out of a Sonos system, but like you said must sound horrible at that level. I am surprised he isn't def yet. But maybe that's just the peeks and its normally at around 80db. Typically a reference level movie averages about 80db, but peeks to 105-115. I think you have done the most you can, minus adding drywall to his side and putting some green glue in between. In my HT I have two layers of 5/8 and green glue, isolated from other walls/joists with clips or double walls. Typically at 80db I can't hear much of anything but low frequencies upstairs. It's the bass that really gets me though, I have two Rythmik F12 subs, they shake the whole house now even with my sound proofing, just can't stop that vibration! Wife isn't happy about that, but I can turn the bass down some.


Yes I was surprised too. I couldn't believe it. I think it's also getting some boost because it's in the corner of the room. When he has a party, he the speaker away from the corner and the db level drops dramatically. Sonos is a good system if you want music throughout your home but it's not meant to be played extremely loud or to replace a good AVR system. After doing some research I saw that Sonos originally had an output level from the device that could be adjusted but they removed it. This would have been great because we could have gone into the settings an "capped" the output level. Sonos has no low frequency containment, no equalizer, and no level limits to their system best I can tell with their latest software.


As for your sub problem, it won't solve the whole problem but SVS makes rubber feet that screw into the sub so it's "floating" dramatically reducing the vibration that the sub is sending to the floor. I put them on my sub and the surrounds near the common wall and to my ear the bass is tighter and there is less bass going through my floor to my neighbor.


Also another really good system is Audyssey's Low Frequency Containment (LFC) system where the bass frequencies that are most likely to transmit through the wall is lowered. I use it when it gets late and I still want to finish a movie without disturbing anyone. In doing a test with my sound meter in my neighbors unit, turning on the LFCon my AVR really makes a very noticeable difference in reducing the bass to a point where I can play my AVR fairly loud and very little is noticeable in my neighbors unit. It's pretty interesting so it's best to google Audyssey LFC to read up on the details. This kind of a system should be mandatory on all AVRs and sound systems and a lot of these disturbing neighbor problems would go away.


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## VTstang

I originally posted this in another thread but didn't get any replies. I am building a theater room in my basement which was built with Superior Walls Xi http://www.superiorwalls.com/products/xiwall.php. This manufactured wall has concrete studs (with rebar) encased in foam with galvanized stud facings (see link and/or attached photos).


I know that clips & channel are the preferred method for soundproofing (short of framing a room inside a room), but is it possible that my walls don't need decoupling since the studs are encased in foam? I just want to be sure before I spend a lot of time and money on decoupling.


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## jrref

VTstang said:


> I originally posted this in another thread but didn't get any replies. I am building a theater room in my basement which was built with Superior Walls Xi http://www.superiorwalls.com/products/xiwall.php. This manufactured wall has concrete studs (with rebar) encased in foam with galvanized stud facings (see link and/or attached photos).
> 
> 
> I know that clips & channel are the preferred method for soundproofing (short of framing a room inside a room), but is it possible that my walls don't need decoupling since the studs are encased in foam? I just want to be sure before I spend a lot of time and money on decoupling.



It's not the foam that's providing sound proofing, it's the concrete. The more mass the harder it is for sound to vibrate and pass through the wall which equals better sound proofing. Since you have concrete walls in a basement and i'm assuming that there is no living space or neighbors on the other side, what is going to bite you is the ceiling. Is there living space above? If so then you are going to need to install some sort of acoustic insulation like Roxul Safe and sound or something similar of your choosing and some sort of acoustic isolation system. Soundproofing a ceiling brings new challenges because you need to add mass and there are not too many products that will do that for a ceiling or float a ceiling below the ceiling, room in a room solution. I know that Quiet Rock and some of these sound isolation systems are not recommended for ceilings because they can sag over time. The only panel you can use on a ceiling that I know of is from National Gypsum called Sound Break XP. It's fire rated, mold resistant and the 5/8 inch version can be installed on a ceiling without the sag problem. It has virtually the same specs as 5/8 Quiet Rock but it's made in the US. I'm not an expert in soundproofing a ceiling so i'll leave the rest to the experts.


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## granroth

jrref said:


> Thanks forAs far as putting more sheet rock between the walls, from what I read, they want an air gap between for better isolation. As we were getting ready to put the quiet rock up I was looking at that. After all the insulation there was only an inch or two of space left so I decided not to go that route.


A clarification on "air gaps" -- that's not necessarily referring to actual air, per se. A wall with drywall + gap + drywall is creating a Mass-Spring-Mass system. This type of system has a natural resonance frequency, in which sound passes through very easily. If you have a small "spring" (the air gap), then the frequency will be decently high and you will likely notice the sound leakage at that point. When you increase the distance between the mass sections by enlarging the air gap/spring, then the resonance frequency drops. The goal is to get it to be below the frequency of any sound you'll be likely to play. That's difficult to do... but it is the goal.

The problem is that air alone can only go so far. That's where insulation comes into the play. One of the major ways that loose insulation works is by creating millions of tiny air pockets, which make it difficult for energy (thermal, usually) to travel along a conductive path. That slows down the energy transfer by quite a bit. That is, btw, the main purpose of insulation as far as thermal barriers go -- they slow down the transfer of heat more than they absorb it.

The ability for insulation with it's millions of air pockets to slow down thermal energy also works decently well for sound energy. Some of the energy is lost in the insulation itself, yes, but this slowing down of energy transfer has the effective end result as if you INCREASED the air pocket by quite a bit. Remember that increasing the width if the air gap lowers the resonant frequency, so essentially doing so in the form of insulation will also lower the resonance point.

So that's my somewhat long way of saying that when they refer to "air gaps", they are really saying "insulation-filled gaps", not literally air (usually).


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## granroth

VTstang said:


> I originally posted this in another thread but didn't get any replies. I am building a theater room in my basement which was built with Superior Walls Xi http://www.superiorwalls.com/products/xiwall.php. This manufactured wall has concrete studs (with rebar) encased in foam with galvanized stud facings (see link and/or attached photos).
> 
> I know that clips & channel are the preferred method for soundproofing (short of framing a room inside a room), but is it possible that my walls don't need decoupling since the studs are encased in foam? I just want to be sure before I spend a lot of time and money on decoupling.


jrref is correct that your issues aren't going to be related to the walls. A massive concrete wall is already going to do a great job of stopping sound. If you're underground, then some loose insulation and a layer of drywall and call your wall good. If that's above ground, then two layers of 5/8" Type X drywall + Green Glue or QuietGlue Pro and it'll rock.

With that out of the way, your weak points will be the ceiling and the door and any wall that's not poured concrete.

What you can do with them honestly depends on what your requirements are. What kind of sound levels will you be generating and what type of frequencies? Where will it be going that you want to dampen the noise? Are you more concerned of theater noise escaping or outside noise coming in?


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## VTstang

granroth said:


> jrref is correct that your issues aren't going to be related to the walls. A massive concrete wall is already going to do a great job of stopping sound. If you're underground, then some loose insulation and a layer of drywall and call your wall good. If that's above ground, then two layers of 5/8" Type X drywall + Green Glue or QuietGlue Pro and it'll rock.
> 
> With that out of the way, your weak points will be the ceiling and the door and any wall that's not poured concrete.
> 
> What you can do with them honestly depends on what your requirements are. What kind of sound levels will you be generating and what type of frequencies? Where will it be going that you want to dampen the noise? Are you more concerned of theater noise escaping or outside noise coming in?




I'm not really worried about sound escaping through the walls to the outside, but rather sound travelling up to the rest of the house. My concern is that sound will transfer from the concrete walls to the ceiling (and then on to the main floor). If I decouple the ceiling and not the walls, am I wasting my time and money on the ceiling? I know the answer is usually yes with wood framed walls because the sound will flank through the walls to the ceiling. Same thing with my concrete walls? I looked on the construction procedures for these walls and it appears as though the sill plate is bolted to the bare concrete bond beam which runs across the top of the concrete wall.


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## VTstang

jrref said:


> It's not the foam that's providing sound proofing, it's the concrete. The more mass the harder it is for sound to vibrate and pass through the wall which equals better sound proofing. Since you have concrete walls in a basement and i'm assuming that there is no living space or neighbors on the other side, what is going to bite you is the ceiling. Is there living space above? If so then you are going to need to install some sort of acoustic insulation like Roxul Safe and sound or something similar of your choosing and some sort of acoustic isolation system. Soundproofing a ceiling brings new challenges because you need to add mass and there are not too many products that will do that for a ceiling or float a ceiling below the ceiling, room in a room solution. I know that Quiet Rock and some of these sound isolation systems are not recommended for ceilings because they can sag over time. The only panel you can use on a ceiling that I know of is from National Gypsum called Sound Break XP. It's fire rated, mold resistant and the 5/8 inch version can be installed on a ceiling without the sag problem. It has virtually the same specs as 5/8 Quiet Rock but it's made in the US. I'm not an expert in soundproofing a ceiling so i'll leave the rest to the experts.


Ok, my understanding is that everyone installs insulation because it is relatively cheap, but the benefits are quite small, and certainly not a replacement for mass or decoupling. As you can see from my post immediately above, my concern is transfer of sound through the walls to the ceiling and onto the main floor. I agree with decoupling the ceiling and adding mass, but I'm trying to determine if that money and effort is wasted if I don't also decouple and add mass to the walls as well.


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## jrref

OK now after looking closer at the picture I can see the sill bolts at the top of the wall cavity. So this is a tough one because if you just sheetrock everything and leave nothing in the void, yes you will get some sound proofing from the foam but not a lot because it's rigid foam. Depending on how loud the audio is from your room will depend on how much is transmitted through the void, through the foam and up into the ceiling.


What you need to consider is the following, cheapest to most expensive:
1) Just sheet rock and leave the void empty and see what happens.
2) Sheetrock with 5/8 inch and fill the void with Roxul Safe & Sound or any other acoustic insulation of your choice.
3) Install a layer of 5/8 inch Quiet Rock or Sound Break and fill the void with Roxul Safe & Sound or any other acoustic insulation of your choice.


If it were me, because of the small surface area at the top of the inside of the wall, I would do #2 at a minimum. Why because the 5/8 inch sheetrock will add the mass that you need and although the acoustic insulation, as most people say, will not solve the problem on it's own, it does lower the resonance point and is an integral part of the sound proofing system. Sound proofing is many pieces all working together. I guarantee you that you will get more sound transmitted leaving the void empty than filling it with acoustic insulation. At the end of the day it looks like you are spending a considerable amount of money constructing the room so It's probably best to go the extra step and insure that you did everything to sound proof than to skimp and possibly find that you are having problems after the fact.


Also although i'm a fan of Roxul, the advantage of using it especially in the basement over any other type like fiberglass is that if you get any moisture over the years, the Roxul will not mold and will dry out and not loose it's effectiveness when the moisture dries. I hope this helps.


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## jrref

Here are some pictures of my wall replacement. Note that we sealed all of the wall outlets and used Quiet seal around all the seams of the sheetrock. Not pictured is the wall to ceiling transition. There is 5/8 inch sheetrock on both sides of the party wall in the ceiling with 3 inches of fiberglass insulation on either side. We left this "as is" so we didn't have to tear the ceiling apart but we filled the gap from the wall to the ceiling with 3 inches of Roxul which did noticeably help reduce the sound transmission into the bedroom above this area. This gave me approximately STC 50-55 based on sound meter readings. If the top and bottom plates were not common then the STC rating would have been a lot more. In my case this was a one for one replacement for the standard party wall but now has the added soundproofing and the Roxul provides additional fire rating and the Sound Break product is mold resistant. BTW the only reason why I used the Sound Break product because it is made here in the US and was significantly cheaper than Quiet Rock which is made in Canada and has basically the same ratings. Locally everyone uses Sound Break for homes, offices, etc so because of the quantity sold and manufactured locally, i'm guessing is why the price is cheaper.


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## jrref

jrref said:


> Here are some pictures of my wall replacement. Note that we sealed all of the wall outlets and used Quiet seal around all the seams of the sheetrock. Not pictured is the wall to ceiling transition. There is 5/8 inch sheetrock on both sides of the party wall in the ceiling with 3 inches of fiberglass insulation on either side. We left this "as is" so we didn't have to tear the ceiling apart but we filled the gap from the wall to the ceiling with 3 inches of Roxul which did noticeably help reduce the sound transmission into the bedroom above this area. This gave me approximately STC 50-55 based on sound meter readings. If the top and bottom plates were not common then the STC rating would have been a lot more. In my case this was a one for one replacement for the standard party wall but now has the added soundproofing and the Roxul provides additional fire rating and the Sound Break product is mold resistant. BTW the only reason why I used the Sound Break product because it is made here in the US and was significantly cheaper than Quiet Rock which is made in Canada and has basically the same ratings. Locally everyone uses Sound Break for homes, offices, etc so because of the quantity sold and manufactured locally, i'm guessing is why the price is cheaper.


Here is the last picture that didn't make it.


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## VTstang

jrref said:


> OK now after looking closer at the picture I can see the sill bolts at the top of the wall cavity. So this is a tough one because if you just sheetrock everything and leave nothing in the void, yes you will get some sound proofing from the foam but not a lot because it's rigid foam. Depending on how loud the audio is from your room will depend on how much is transmitted through the void, through the foam and up into the ceiling.
> 
> 
> What you need to consider is the following, cheapest to most expensive:
> 1) Just sheet rock and leave the void empty and see what happens.
> 2) Sheetrock with 5/8 inch and fill the void with Roxul Safe & Sound or any other acoustic insulation of your choice.
> 3) Install a layer of 5/8 inch Quiet Rock or Sound Break and fill the void with Roxul Safe & Sound or any other acoustic insulation of your choice.
> 
> 
> If it were me, because of the small surface area at the top of the inside of the wall, I would do #2 at a minimum. Why because the 5/8 inch sheetrock will add the mass that you need and although the acoustic insulation, as most people say, will not solve the problem on it's own, it does lower the resonance point and is an integral part of the sound proofing system. Sound proofing is many pieces all working together. I guarantee you that you will get more sound transmitted leaving the void empty than filling it with acoustic insulation. At the end of the day it looks like you are spending a considerable amount of money constructing the room so It's probably best to go the extra step and insure that you did everything to sound proof than to skimp and possibly find that you are having problems after the fact.
> 
> 
> Also although i'm a fan of Roxul, the advantage of using it especially in the basement over any other type like fiberglass is that if you get any moisture over the years, the Roxul will not mold and will dry out and not loose it's effectiveness when the moisture dries. I hope this helps.


Thanks for your feedback. I am planning on using insulation between the concrete studs because it is cheap and every little bit helps. I had discounted Roxul because the published numbers show it performs similarly to R-13, but I am concerned from a moisture perspective, so that may sway me to using Roxul. Beyond that, I was already planning on using OSB - GG - 5/8"DW. 


My main concern is whether I need to decouple the walls to recognize the benefits of decoupling the ceiling. The wall manufacturer states that if you hang anything heavy on the wall, you need to frame between the studs for extra support. I confirmed with the manufacturer that I don't need to add the extra framing just to add an extra OSB layer and GG. I probably will, however need to add the extra framing if I go clip and hat channel since the load will be carried over a much smaller number of attachment points. So, I would like to avoid decoupling if possible, but if renders the ceiling decoupling effort worthless, then I will go to the extra expense and effort to also decouple the walls. This is really my only remaining concern with the walls. Any thoughts? Thanks.


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## jrref

VTstang said:


> Thanks for your feedback. I am planning on using insulation between the concrete studs because it is cheap and every little bit helps. I had discounted Roxul because the published numbers show it performs similarly to R-13, but I am concerned from a moisture perspective, so that may sway me to using Roxul. Beyond that, I was already planning on using OSB - GG - 5/8"DW.
> 
> 
> My main concern is whether I need to decouple the walls to recognize the benefits of decoupling the ceiling. The wall manufacturer states that if you hang anything heavy on the wall, you need to frame between the studs for extra support. I confirmed with the manufacturer that I don't need to add the extra framing just to add an extra OSB layer and GG. I probably will, however need to add the extra framing if I go clip and hat channel since the load will be carried over a much smaller number of attachment points. So, I would like to avoid decoupling if possible, but if renders the ceiling decoupling effort worthless, then I will go to the extra expense and effort to also decouple the walls. This is really my only remaining concern with the walls. Any thoughts? Thanks.


Right so forget about the clips and channels in your case, the OSB and GG will work better. And if you are concerned about weight, you can also use Quiet Rock or Sound Break and it will work pretty close to the GG with a lot less labor and weight especially since its a basement wall. The walls and the ceiling systems will be independent. Either way you are good to go.


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## granroth

jrref said:


> 2) Sheetrock with 5/8 inch and fill the void with Roxul Safe & Sound or any other acoustic insulation of your choice.
> 3) Install a layer of 5/8 inch Quiet Rock or Sound Break and fill the void with Roxul Safe & Sound or any other acoustic insulation of your choice.


In general, it's rarely worth using Roxul or similar products from a strictly soundproofing perspective. The cheap "pink" fiberglass works just as well for absorption. Roxul and other mineral or rock wool products come into play if you need the additional fire rating or moisture resistance. So yeah, there are definite good reasons to use Roxul, but soundproofing on its own is not one of them.

I don't typically recommend either Quiet Rock or Sound Break since both are well overused. They are a great product to use IF you need a viscously damped drywall and only have 5/8" to work with. You pay an arm and a leg, but you get a very good performing drywall that's only 5/8" thick.

Most people can spare to lose another 5/8", though, and in that case, using two layers of 5/8" Type X drywall with either Green Glue or Quiet Glue Pro in between is a much better option. It works as good if not better than the commercial panels but it does so at a fraction of the cost. The only downside is that you'll lose 1-1/4" of room width (assuming two layers on both sides of a room).

I honestly don't know why Quiet Rock is so popular, since most people aren't that space constrained. Maybe they just don't know about the better alternatives?


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## granroth

VTstang said:


> My main concern is whether I need to decouple the walls to recognize the benefits of decoupling the ceiling. The wall manufacturer states that if you hang anything heavy on the wall, you need to frame between the studs for extra support. I confirmed with the manufacturer that I don't need to add the extra framing just to add an extra OSB layer and GG. I probably will, however need to add the extra framing if I go clip and hat channel since the load will be carried over a much smaller number of attachment points. So, I would like to avoid decoupling if possible, but if renders the ceiling decoupling effort worthless, then I will go to the extra expense and effort to also decouple the walls. This is really my only remaining concern with the walls. Any thoughts? Thanks.


Unfortunately, there is no clearly proven answer to your question. That is, as long as you stick with wall assemblies that have been thoroughly tested in a lab, you can be assured of reaching a desired sound attenuation threshold. If your wall assembly differs from the tested variants, then some amount of uncertainty comes into play. You could negatively affect the results by a non-noticeable amount all the way to a massive amount. It's all going to be a guess.

My guess is that it wouldn't be worth decoupling the concrete wall, even though the joists are bolted to the sill plate. Yes, it's true that there will be some flanking paths through that route that will by-pass the decoupled OSB/DW on the ceiling. HOWEVER, concrete is very massive and it does a fantastic job of absorbing sound energy. Most of the energy that is likely to travel up the wall and travel through the joists will be low frequency energy... and honestly, that's going to be hard to combat anyway. I would personally skip the clips and channels on the concrete wall unless you have VERY stringent requirements. It doesn't seem like you do.

It is absolutely still worth decoupling the ceiling, from the perspective of the sound energy that strikes the OSB/DW that is attached there.


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## VTstang

granroth said:


> Unfortunately, there is no clearly proven answer to your question. That is, as long as you stick with wall assemblies that have been thoroughly tested in a lab, you can be assured of reaching a desired sound attenuation threshold. If your wall assembly differs from the tested variants, then some amount of uncertainty comes into play. You could negatively affect the results by a non-noticeable amount all the way to a massive amount. It's all going to be a guess.
> 
> My guess is that it wouldn't be worth decoupling the concrete wall, even though the joists are bolted to the sill plate. Yes, it's true that there will be some flanking paths through that route that will by-pass the decoupled OSB/DW on the ceiling. HOWEVER, concrete is very massive and it does a fantastic job of absorbing sound energy. Most of the energy that is likely to travel up the wall and travel through the joists will be low frequency energy... and honestly, that's going to be hard to combat anyway. I would personally skip the clips and channels on the concrete wall unless you have VERY stringent requirements. It doesn't seem like you do.
> 
> It is absolutely still worth decoupling the ceiling, from the perspective of the sound energy that strikes the OSB/DW that is attached there.


Thanks to you and jrref. Its two for two on skipping clips and channel. I'm happy I can avoid spending an extra ~$1k in my build


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## VTstang

granroth said:


> Most people can spare to lose another 5/8", though, and in that case, using two layers of 5/8" Type X drywall with either Green Glue or Quiet Glue Pro in between is a much better option. It works as good if not better than the commercial panels but it does so at a fraction of the cost. The only downside is that you'll lose 1-1/4" of room width (assuming two layers on both sides of a room).


Do you or anyone else have an opinion on Quiet Glue Pro? I did a quick search and found discussions on Quiet Glue vs GG from 8 years ago saying the GG was superior, but I'm not sure if Quiet Glue Pro is a newer (improved) product. It appears as though Quiet Glue Pro is about 33% less for a 5 gallon pail, although this is comparing the published prices and there may be discounts off of list price for GG.


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## jrref

granroth said:


> In general, it's rarely worth using Roxul or similar products from a strictly soundproofing perspective. The cheap "pink" fiberglass works just as well for absorption. Roxul and other mineral or rock wool products come into play if you need the additional fire rating or moisture resistance. So yeah, there are definite good reasons to use Roxul, but soundproofing on its own is not one of them.
> 
> I don't typically recommend either Quiet Rock or Sound Break since both are well overused. They are a great product to use IF you need a viscously damped drywall and only have 5/8" to work with. You pay an arm and a leg, but you get a very good performing drywall that's only 5/8" thick.
> 
> Most people can spare to lose another 5/8", though, and in that case, using two layers of 5/8" Type X drywall with either Green Glue or Quiet Glue Pro in between is a much better option. It works as good if not better than the commercial panels but it does so at a fraction of the cost. The only downside is that you'll lose 1-1/4" of room width (assuming two layers on both sides of a room).
> 
> I honestly don't know why Quiet Rock is so popular, since most people aren't that space constrained. Maybe they just don't know about the better alternatives?


The reason why some people use Quiet Rock or Sound Break is for 1) As you said, they don't want to go beyond the 5/8 footprint of the existing wall and 2) Convenience regardless of the cost. These products are essentially 2 pieces of sheet rock with a substance similar to green glue in between adding up to 5/8 inch. The reason why green glue always wins is not because of the green glue itself but because you are adding an additional 5/8 layer of sheet rock which gives you more mass. I would guess if you purchased the 1.25 inch version of Quiet Rock that you would get very similar results as the green glue. As you said, the Big Plus with the green glue system is cost.


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## granroth

VTstang said:


> Do you or anyone else have an opinion on Quiet Glue Pro? I did a quick search and found discussions on Quiet Glue vs GG from 8 years ago saying the GG was superior, but I'm not sure if Quiet Glue Pro is a newer (improved) product. It appears as though Quiet Glue Pro is about 33% less for a 5 gallon pail, although this is comparing the published prices and there may be discounts off of list price for GG.


Green Glue has quite a bit more research to back up its claims, but there was at least one lab test done with Quiet Glue Pro floating around that showed very similar results to GG. I don't have a direct link right now. I haven't seen any compelling reason to think that the test results were fraudulent in any way, which suggests that QGP would be a good alternative.

Still, the well-tested nature of GG does make it more of a "sure thing".


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## jrref

granroth said:


> Green Glue has quite a bit more research to back up its claims, but there was at least one lab test done with Quiet Glue Pro floating around that showed very similar results to GG. I don't have a direct link right now. I haven't seen any compelling reason to think that the test results were fraudulent in any way, which suggests that QGP would be a good alternative.
> 
> Still, the well-tested nature of GG does make it more of a "sure thing".


Right I did see that report. The viscoelastic material in between the sheets is no mystery. It's characteristics are well known so whether you buy it in a tube, i.e. Green Glue or buy it pre-made with the sheetrock, the end result is pretty much the same if you have the same mass. Quiet Rock, Sound Break, and Green Glue all publish their test results and they are all pretty close given the same amount of mass. It's just that with Green Glue you are doing all the labor to create the "sheet rock sandwich" vs paying the price for it all made up. But again you have to install it correctly. In my case with the Sound Break, I had to put a bead of Quiet Seal Pro around each sheet of sound break to seal it so there were no air gaps. This stuff is just like Green Glue. By the time I was done, I used twice as much as they estimated because you want to seal everything in order to get a good seal and make it as air tight as possible.


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## VTstang

Here's another noise related question. I am getting ready to install a ducted mini split system for my theater room. I will be using flex duct in the theater room, but will be running rectangular duct up to the room. I am sourcing the rectangular duct transitions, elbows, and takeoffs from a local manufacturer, but want to buy the straight sections of rectangular duct from Lowes or HD to keep cost down. The problem is that it looks like the Lowes or HD duct is 28 or 30GA, while it looks like most fabricators use 26GA material. I'm wondering if going with 28 or 30GA material is inviting noise problems from the duct "oil canning" when the system turns on and off. Thoughts?


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## adrianwarland

*Dead vent : is it size or volume that matters?*

Hi

I'm building a drumming room not a HT, but the soundproofing requirements seem the same and I'm learning so much from the forum.

It will only be a 10'x6' division of a basement. To ventilate I was going to use dead vents, though am only using 4" flexduct as flow requirements are low and ventilation noise is not a problem (you won't hear it for the drumming). Now outside the room there is only 4' spare and specs state 2'x'2 box. Giving volume of about 2x2x6 (low ceiling) of 24 cube Ft. 

Q1. given the smaller duct size, would a 1'x4'x6' box be as effective(same volume).

Two of these would effectively be the width of the double stud wall I'm installing, so...

Q2. Would this induce triple leaf effect.

plan would be DD GG, 2x4, 1"gap, 2x4, single drywall, deadvent, DD GG. I would mount fan externally for easy access and because it will only be running when I am drumming.

Q3. Budget is tight (as usual) so given diminishing returns, would my assumption that GG 1 tube/board on both int/ext faces would be more effective than GG 2 tubes/board on just interior.

any advice welcome


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## VTstang

VTstang said:


> Here's another noise related question. I am getting ready to install a ducted mini split system for my theater room. I will be using flex duct in the theater room, but will be running rectangular duct up to the room. I am sourcing the rectangular duct transitions, elbows, and takeoffs from a local manufacturer, but want to buy the straight sections of rectangular duct from Lowes or HD to keep cost down. The problem is that it looks like the Lowes or HD duct is 28 or 30GA, while it looks like most fabricators use 26GA material. I'm wondering if going with 28 or 30GA material is inviting noise problems from the duct "oil canning" when the system turns on and off. Thoughts?


For anyone that might be interested: I went to a metal fabrication shop this morning and spoke with a fabricator. He said that 28-30GA is pretty thin and is likely to "oil can" when the system cycles. He said that they use some sort of reinforced (ribbed) metal to combat this problem (in addition to the thicker material). I asked for a price and it was $7 less than Lowes and $11 less than HD per 4ft section.


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## BasementBob

30 gauge ducts are economy or residential, and are often prefab.
24/26 gauge ducts are more commercial, and/or custom fabricated. Anything over 12 inch diameter I'd try this gauge. For much larger consider 22 gauge.
I know of a 30 gauge main trunk in a home, that gives duct banging issues ('oil can' pops) when the system cycles. Visitors say 'the house makes strange noises'


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## WorldCupUSA

*Need help soundproofing a concrete block wall*

Hi,
I share a party wall with an adjacent townhome. The party wall consists of 8" concrete masonry units (CMU). On my side, there are 1" thick wooden furring strips attached to the CMUs, and then 1/2" of drywall. 

I've been hearing TV sounds (mostly bass) coming through, along with sounds from conversations. The conversation sounds come through muffled, so I can't tell what the neighbors are saying. The neighbor says their TV isn't along the shared wall. I also hear impact noises like footsteps, but it's mainly the bass that keeps me from sleeping. This isn't really loud, thumping bass, but it's enough to make it hard to sleep.

Before embarking on a project with hat channels, green glue and extra drywall, I investigated a bit. It turns out, the builder did some odd things. Because there was only 1" between the drywall and concrete blocks, there wasn't enough room for standard-sized electrical boxes. So where there are electrical outlets, somebody punched a hole in the side of the concrete block. The electrical boxes are sitting inside the hollow cores of the CMUs. You shouldn't be able to see the cavities of the CMUs from the side, but I can.

I was surprised to find holes like this in the concrete blocks. I'm not sure if this is making things worse, but it seems to present an opportunity to try some things before moving on to green glue, etc. Would I benefit from stuffing or blowing some insulation into the cores of the concrete blocks (given that I have access to the cores)? Should I pull the electrical boxes out, and put putty pads around their backs? 

Looking ahead, if I took down my existing drywall in order to put up a hat channel and new drywall - can I attach that to my existing 1" thick furring strips, or do I need to put up proper studs? 

Hoping for some insights or ideas.


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## cyclonus99

*Feedback requested for sound proofing/isolation of media room*

Hi all:

I'm new to the forum and I am looking for feedback with regards to my media room/game room design for sound proofing and isolation. 

Below is my proposed design.

The blue walls indicate walls that would have to be decoupled via clips/channel and the red walls would be decoupled stud walls by default.

Here are some of my priorities and preferences:

1) I don't really listen at reference levels and I'm not a big fiend for LFE. I just want to be able to listen at a comfortably "loud" level.
2) I don't care about sound getting into adjacent rooms, like bedroom, office, etc, nor am I really all that concerned about sound escaping to the first floor.
3) My primary concern is sound getting to the 2nd floor at night when wife/kids may be sleeping. Most of the time I'd be watching movies with family during the day.
4) I am concerned about sound isolation though - at the moment, in the unfinished basement, I hear a fair amount of noise coming from the AC units outside as well as footsteps from the 1st level and stairwell. I want to keep said noise to a minimum.

My thoughts are, that I would decouple where I can (blue walls and ceiling via clips/channels and red walls via decoupled stud wall) + DD and Green Glue. I am also looking at sound proofing windows and screen door to keep out exterior noise. Also considering solid core door doors to the adjacent rooms, and solid core door + door jambs/stops at top of the stairs. Also considering backer boxes for any recessed lighting, putty for outlets, and also taking ductwork into consideration. 

I realize that the stairwell is a major weak point and conduit of noise all the way up to the second floor, especially LFE. I also realize the limitations of trying to sound proof an 'open floor design' like this, but keep in mind my priorities above.

Thoughts? Would it be a complete waste of money with the stairwell and open plan? Would some aspects be more bang for the buck than others?


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## cyclonus99

WorldCupUSA said:


> Would I benefit from stuffing or blowing some insulation into the cores of the concrete blocks (given that I have access to the cores)? Should I pull the electrical boxes out, and put putty pads around their backs?
> 
> Looking ahead, if I took down my existing drywall in order to put up a hat channel and new drywall - can I attach that to my existing 1" thick furring strips, or do I need to put up proper studs?
> 
> Hoping for some insights or ideas.


My guess would be the best solution here is to just put up a decoupled stud wall (maybe 1" from the concrete blocks), if you have the space to do so. In this stud wall, you can properly insulate and putty around the outlets and the holes in the concrete wall won't really matter.

If you can't do a stud wall, I'd put put channel on the furring strips and DD+GG over that. I'd also putty around the outlets so the noise doesn't seep in through them.

Other people more knowledgable than myself may have better ideas.


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## Finnster

Unwanted Sub resonance issue

My neighbors house is about 50' away and is getting sub noises from my system when their back doors ( double french doors across the back) are open. My wall is about a 90* angle to their home. I suspect the main culprit is 3 windows on my wall, 1 of which is 6'x4'. I am in the process of covering the main window with a large wooden Structure (think modern version of built-ins) that will be about 10" deep. I am hoping to avoid the best option of building a false wall, but this structure will cover a large portion of this wall and allow me to essentially fill the window space with insulation, then put a vinyl barrier and then another layer of baffle, which is really the effect of a false wall. I also will place bass traps and acoustic panels in key locations, I understand that this is more for internal affect but I hope it will help for external levels as well. 

If anyone has other suggestions other than building a false wall or covering the existing wall, Also, whats the best way to block noise on windows? Appreciate the help in advance.


----------



## jrref

Finnster said:


> Unwanted Sub resonance issue
> 
> My neighbors house is about 50' away and is getting sub noises from my system when their back doors ( double french doors across the back) are open. My wall is about a 90* angle to their home. I suspect the main culprit is 3 windows on my wall, 1 of which is 6'x4'. I am in the process of covering the main window with a large wooden Structure (think modern version of built-ins) that will be about 10" deep. I am hoping to avoid the best option of building a false wall, but this structure will cover a large portion of this wall and allow me to essentially fill the window space with insulation, then put a vinyl barrier and then another layer of baffle, which is really the effect of a false wall. I also will place bass traps and acoustic panels in key locations, I understand that this is more for internal affect but I hope it will help for external levels as well.
> 
> If anyone has other suggestions other than building a false wall or covering the existing wall, Also, whats the best way to block noise on windows? Appreciate the help in advance.


Bass is very tricky. I think the bass traps will help but you need to see if you are vibrating your structure. Since your neighbor is hearing the sub at 50 ft away, and i'm assuming that your structures are not connected then you have to be vibrating the structure which is then vibrating the outside air. It's same principal as when a car pulls up along side of you with subs in the trunk. What I would do first is do a little experimentation first such as put some heavy drapes over the offending windows and see if there is any change. You should also use a sound level meter and take a reading in your room and then outside the room. If you are seeing 100db in the room and you create a wall with an STC of 50 then you should see an approximate 50 db loss outside. Taking some initial readings will help you see the magnitude of the problem. But no matter what you do, it's not going to trap that sub 100%. I think you need to get something like a 3/4 quiet rock or sheetrock with green glue at this thickness. This is what studio's do. If you do some online research you will see that all of these soundproofing solutions are very challenged in the bass frequencies and the Only thing that will reduce the transmission is more mass in the wall. The more mass, the more energy it's going to take to vibrate the wall. Clips, channels, green glue, will all help but it's not going to be enough if your neighbor is being bothered at 50 feet away. Last resort is to turn your sub down a little  I hope this helps.


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## Finnster

THANKS! JRREf, great suggestions. I need to have a talk with them and maybe even put on a movie and hear it for myself. I have some real doubts on how loud it really is as I play movies at -15 to -20.I have 2x10 construction with foam injected walls. I was playing a couple like Jurassic Park when setting up the subs and I was playing it at about -10 but my windows on the side were open (not facing house but I am sure that doesn't help!) I have 2 FV15hps but they are so damn efficient you don't really need to blast them. Is there a sound meter you can recommend to test or can I just us any SPL?


----------



## jrref

Finnster said:


> THANKS! JRREf, great suggestions. I need to have a talk with them and maybe even put on a movie and hear it for myself. I have some real doubts on how loud it really is as I play movies at -15 to -20.I have 2x10 construction with foam injected walls. I was playing a couple like Jurassic Park when setting up the subs and I was playing it at about -10 but my windows on the side were open (not facing house but I am sure that doesn't help!) I have 2 FV15hps but they are so damn efficient you don't really need to blast them. Is there a sound meter you can recommend to test or can I just us any SPL?


Oh ok you didn't say the windows were open!  You should have just invited your neighbors in for popcorn then 


I like the Radio Shack sound meter but you can also use an app called Sound Meter. If you have an iPhone you can download it from the App Store. It's going to be good enough for you to take these measurements.


----------



## Finnster

jrref said:


> Oh ok you didn't say the windows were open!  You should have just invited your neighbors in for popcorn then
> 
> 
> LOL, Yeah I forgot about that but they weren't large ones... but yes, it certainly makes a difference I am sure. I am a good neighbor though and wouldn't want them to be bothered by my subs.
> 
> I like the Radio Shack sound meter but you can also use an app called Sound Meter. If you have an iPhone you can download it from the App Store. It's going to be good enough for you to take these measurements.


Yeah, there's always an app! Cheers and thanks again!


----------



## zim2411

Hi all,

I'd like some general advice regarding sound proofing. I'm currently looking at buying a house and initially I was set on a getting a single family home with a sizeable basement to build an ample home theater that won't annoy neighbors. Recently I found an end of group townhouse that's cheaper and in a location I want more than most of the single family homes I can afford, so I've been leaning that way. I'm just worried about the sound transmission to the neighboring house in the basement. I currently have two 15" MiniMarty subs powered by a Crown XLS 2500 and I play them loud, and as I understand it bass is the hardest to isolate.

The basement is currently finished and is 12' by 17', with a (roughly) 8' ceiling. One of the 12' walls is shared with the neighboring house, one 17' wall is internal to the house (has the doors and a cut out for a bar area now), and the other two walls are exterior walls. I believe the core of the party wall is concrete masonry but I don't know how the room itself was finished. 

I've been researching different techniques and was a little disappointed to find green glue + whisper clips aren't terribly effective against low bass frequencies. I thought I could just throw an extra layer of green glued drywall on the existing party wall but it seems like that won't do much. I know the room-within-a-room construction would be best, but could I sort of just use elements of that idea instead? Could I get away with just building a freestanding wall a 6-12 inches or so away from the existing party wall? Would I also need to float the ceiling with isolation clips to prevent flanking? What about the exterior wall next to it?

Basically if someone can just tell me "no that's a stupid idea, you'll never get good isolation, go for a single family house" or "yeah, it might work" that'd help a lot with my decision. The house is a good $20k cheaper than most of the single family houses I've checked out, so I'd be willing to throw some money towards isolation construction (maybe $5k total.)


----------



## jrref

zim2411 said:


> Hi all,
> 
> I'd like some general advice regarding sound proofing. I'm currently looking at buying a house and initially I was set on a getting a single family home with a sizeable basement to build an ample home theater that won't annoy neighbors. Recently I found an end of group townhouse that's cheaper and in a location I want more than most of the single family homes I can afford, so I've been leaning that way. I'm just worried about the sound transmission to the neighboring house in the basement. I currently have two 15" MiniMarty subs powered by a Crown XLS 2500 and I play them loud, and as I understand it bass is the hardest to isolate.
> 
> The basement is currently finished and is 12' by 17', with a (roughly) 8' ceiling. One of the 12' walls is shared with the neighboring house, one 17' wall is internal to the house (has the doors and a cut out for a bar area now), and the other two walls are exterior walls. I believe the core of the party wall is concrete masonry but I don't know how the room itself was finished.
> 
> I've been researching different techniques and was a little disappointed to find green glue + whisper clips aren't terribly effective against low bass frequencies. I thought I could just throw an extra layer of green glued drywall on the existing party wall but it seems like that won't do much. I know the room-within-a-room construction would be best, but could I sort of just use elements of that idea instead? Could I get away with just building a freestanding wall a 6-12 inches or so away from the existing party wall? Would I also need to float the ceiling with isolation clips to prevent flanking? What about the exterior wall next to it?
> 
> Basically if someone can just tell me "no that's a stupid idea, you'll never get good isolation, go for a single family house" or "yeah, it might work" that'd help a lot with my decision. The house is a good $20k cheaper than most of the single family houses I've checked out, so I'd be willing to throw some money towards isolation construction (maybe $5k total.)


The party wall in the basement is probably concrete but if you have dual subs and you play them loud then besides a room in a room you probably won't be able to attenuate the sound enough to your neighbors unit. From what you described, you are best off buying a single family house. If you buy the town home, the minute you start vibrating the structure with your subs, you are going to be driving your neighbors nuts. Sure there is a lot you can do but it probably won't be enough.


----------



## zim2411

jrref said:


> The party wall in the basement is probably concrete but if you have dual subs and you play them loud then besides a room in a room you probably won't be able to attenuate the sound enough to your neighbors unit. From what you described, you are best off buying a single family house. If you buy the town home, the minute you start vibrating the structure with your subs, you are going to be driving your neighbors nuts. Sure there is a lot you can do but it probably won't be enough.


Yeah, I had a feeling that's the answer I'd get. Thanks 

Are there resources available detailing room in a room construction with cost estimates?


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## jrref

zim2411 said:


> Yeah, I had a feeling that's the answer I'd get. Thanks
> 
> Are there resources available detailing room in a room construction with cost estimates?


Best to google for companies in you area. I live in a town home development similar to what you are considering and the construction is pretty good. I went ahead and sound proofed the party wall, did everything reasonably possible so i have a lot of experience in this area. The bottom line in your case is if you buy a home that shares a common wall or you have neighbors very close to you, you will be living with your neighbors. This means that you are going to have to be considerate with how much noise you make and at what times you make them. This includes parties, playing your home theater loud, etc, etc.. In other words, you will be restricted on what you can do and when. Also the town home development probably has an HOA or some other governing body which will help your neighbors enforce the bylaws and you won't be able to fight them so save yourself a lot of aggravation and but the single family home. Then you can do anything you want.


----------



## jcr159

Ok guys... Not through this whole thread yet, so apologize if this has been asked.

I'm in a new home and need to start planning for the new basement rec room/theater. (Not sure how the floor plan will lay out yet, still working on that part.)

But to my question... I haven't seen anything yet that talks about techniques to deal with blocking the sound from sewer pipes. Basically, in my basement, anytime someone showers or flushes, you hear a huge amount of noise from the water rushing down the main sewer pipe. It will end up in the ceiling after I finish the space, but not sure how to deal with it from a sound perspective.

I gather that the older cast iron was a lot quieter than the PVC that is used in my house.

Thoughts?
Thanks guys!
-j


----------



## Kressilac

jcr159 said:


> Ok guys... Not through this whole thread yet, so apologize if this has been asked.
> 
> I'm in a new home and need to start planning for the new basement rec room/theater. (Not sure how the floor plan will lay out yet, still working on that part.)
> 
> But to my question... I haven't seen anything yet that talks about techniques to deal with blocking the sound from sewer pipes. Basically, in my basement, anytime someone showers or flushes, you hear a huge amount of noise from the water rushing down the main sewer pipe. It will end up in the ceiling after I finish the space, but not sure how to deal with it from a sound perspective.
> 
> I gather that the older cast iron was a lot quieter than the PVC that is used in my house.
> 
> Thoughts?
> Thanks guys!
> -j


The sound is intermittent and usually not an issue while watching a movie. Most people tend to not get up during a movie without pausing the movie and the distraction is a few seconds if someone else in the family uses the bathroom while you are using the theater. I wouldn't worry about it. Insulate the area, make sure the walls don't touch the pipe and make sure the access panel isn't your weak link and you will likely dampen enough of the sound for it to not be noticeable when it is used. It certainly not worth the trouble to replace for something quieter when you'll have bigger issues with the AC vents and units in the basement. Plan to put those away from the theater as far as possible. It'll pay bigger dividends then worrying about the occasional flush.


My $.02 on the matter.


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## jrref

Kressilac said:


> The sound is intermittent and usually not an issue while watching a movie. Most people tend to not get up during a movie without pausing the movie and the distraction is a few seconds if someone else in the family uses the bathroom while you are using the theater. I wouldn't worry about it. Insulate the area, make sure the walls don't touch the pipe and make sure the access panel isn't your weak link and you will likely dampen enough of the sound for it to not be noticeable when it is used. It certainly not worth the trouble to replace for something quieter when you'll have bigger issues with the AC vents and units in the basement. Plan to put those away from the theater as far as possible. It'll pay bigger dividends then worrying about the occasional flush.
> 
> 
> My $.02 on the matter.


Yep besides trying to insulate the outside of the pipe which will not do much, the only other way to fix it is to change it over to cast iron.


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## ronny31

Just make sure the pipe is fastened properly with a piece of rubber or something between it and whatever its fastened to. Most noise is due to shaking plumbing as 20 lbs of water goes down. Does something for the longevity of the plumbing as well.


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## jrref

ronny31 said:


> Just make sure the pipe is fastened properly with a piece of rubber or something between it and whatever its fastened to. Most noise is due to shaking plumbing as 20 lbs of water goes down. Does something for the longevity of the plumbing as well.


I would do all these things to lessen the noise but you will always hear the water rushing through that pipe.


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## jcr159

bummer 

I was hoping the frequencies of the noise were high enough that something like an MLV with Closed Cell Foam wrap (similar to what you would do in a car door) might help...

Maybe the real issue, (and why cast iron helps), is that the mass you would need to make any real impact is impractical to add to the pipe exterior...

This product also claims to make improvements, but I don't trust them... 

http://www.soundproofcow.com/Quiet-Wrap-Pipe-Soundproofing-Wrap.html


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## jrref

jcr159 said:


> bummer
> 
> I was hoping the frequencies of the noise were high enough that something like an MLV with Closed Cell Foam wrap (similar to what you would do in a car door) might help...
> 
> Maybe the real issue, (and why cast iron helps), is that the mass you would need to make any real impact is impractical to add to the pipe exterior...
> 
> This product also claims to make improvements, but I don't trust them...
> 
> http://www.soundproofcow.com/Quiet-Wrap-Pipe-Soundproofing-Wrap.html


Foam, wrap, etc., will all help but don't expect the sound to vanish completely. Also the Quiet wrap looks interesting and it's cheap so I would give that a try.


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## nandkisham

*Floor Isolation -Acoustic / Serenity Mat*

I am in the early stages of my build -- floor.

I plan to do the sub-floor + 2 layers OSB with GG.

I am not concerned about the footfall noise but like to achieve reasonable floor isolation

What are some of the alternatives for Serenity/Acoustic Mats? 

Appreciate your suggestions


----------



## lovingdvd

granroth said:


>


What's the best way to secure the 2x4 blocking between the joists? I have I-beam joists 24" on center. The "web" part of the joist (if I'm using the term correctly, I'm referring to the part of the joist that runs perpendicular to the ceiling, not the flange on the top and bottom) is about 3/8" or 1/2" thick. Also in case you are wondering I cannot rest the 2x4 on the flange because the 2x4 wouldn't be high enough up the joists to give me the minimal 0.5" air gap I'm looking for like illustrated in this diagram. Thanks!


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## nandkisham

*Putty or backer boxes*

out of curiosity..? Has anyone tried backer boxes (MDF/Glue) for electrical outlets.

Code restrictions, cost?? pros/Cons


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## Ryan Hendry

lovingdvd said:


> What's the best way to secure the 2x4 blocking between the joists? I have I-beam joists 24" on center. The "web" part of the joist (if I'm using the term correctly, I'm referring to the part of the joist that runs perpendicular to the ceiling, not the flange on the top and bottom) is about 3/8" or 1/2" thick. Also in case you are wondering I cannot rest the 2x4 on the flange because the 2x4 wouldn't be high enough up the joists to give me the minimal 0.5" air gap I'm looking for like illustrated in this diagram. Thanks!


Hey lovingdvd. If you have I-beam joists that are simply particle board in between the top and bottom of the "I", you will not be able to use this method. The structural loads are only distributed by the top and bottom plate sections. Trying to distribute the weight in the middle sections will end with a structural failure.


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## lovingdvd

Ryan Hendry said:


> Hey lovingdvd. If you have I-beam joists that are simply particle board in between the top and bottom of the "I", you will not be able to use this method. The structural loads are only distributed by the top and bottom plate sections. Trying to distribute the weight in the middle sections will end with a structural failure.


Thanks Ryan. I appreciate the heads up! At this point I am planning to use Kinetics wave hangers secured directly to the bottom of the joists and decouple the walls with their CWCA clips. The room above the theater is a living room with 3/4" ply, pad and carpet. The main goal is to not disturb those in that room particularly with the LFE from the subs (two dual Seaton Submersive F2+ with two in-wall 15" subs). While at the same time prevent their footsteps from being heard in the theater. So the overall plan is to put 5/8" drywall with GG on the underside of the subfloor where I can and the use insulation, wave hangers with 20 gauge 7/8" hat channel, 5/8" ply, GG, and 5/8" dry wall.


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## Ryan Hendry

Hey, no problem. The Kinetics seems like a smart solution to what you are describing. Ceiling height is always a tricky and valuable thing.

Do you have a build thread going?


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## JAMN4IA

Just learned about the Kinetics system from your post. A quick search on the forums seems like there is some debaye. Has the system changed any over the years?


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## nandkisham

*TSC Mat on subfloor -Glue?*

Do we need to use glue under/over the TSC mat? I have seen few do this.

Subloor(OSB) + TSC Rubber Mat + OSB

If yes, should it be Green Glue or any other recommendations?

Regards,
NJ


----------



## LeBon

nandkisham said:


> Do we need to use glue under/over the TSC mat? I have seen few do this.
> 
> Subloor(OSB) + TSC Rubber Mat + OSB
> 
> If yes, should it be Green Glue or any other recommendations?
> 
> Regards,
> NJ


I used latex adhesive under and over the rubber mat (not Green Glue). I have seen @BIGmouthinDC give the name of the latex adhesive product, but I can't remember it.... "CRS Syndrome..."


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## BIGmouthinDC

Da5


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## nandkisham

BIGmouthinDC said:


> Da5


Thanks @LeBon, @BIGmouthinDC


----------



## BlueIsle

*Soundproofing plank-and-board walls*

I have an 'unstandard' wall configuration, given that I live in an older building, and I was hoping for some advice on how best to deal with it. 

I want to soundproof the wall between my unit and my neighbour's. When I made a hole in the drywall, I saw that the wall behind is "piece-sur-piece" (plank-and-board), essentially horizontal planks laid one on top of the other to create a solid wall with some small cracks at times between the planks. The drywall is supported on wood studs. 

It looks like I am dealing with a structural "triple-leaf" wall that I can't do much about. On my neighbour's side of this plank wall, I imagine he also has set of wood studs and drywall (no insulation in either air space). 

What I was thinking of doing was the following:

1. Reflexor membrane (or acoutiscal caulk or 3M tape) to seal the cracks in the plank-and-board wall. I am not sure which is better. Could the membrane create a tiny air space?

2. Pull back the studs to create a bigger air space (I am limited in how big of an airspace I can create... but I was hoping to install the new studs between 1/2 inch and 1 inch from the plank wall) and use 2 x 4 metal studs. 

3. Fill the air space with insulation. If the insulation touches the wall (or the membrane, as the case may be), is that an issue, or simply less cost effective?

4. Add two layers of drywall with Green Glue in between.

If I have a bit of extra space (an extra 1/2 inch or so), which is better, to add an extra layer of drywall, or to increase the size of the air cavity?

As well, in one of the two rooms adjoining my neighbour's unit, my neighbour added soundproofing. However, he didn't add any insulation in the walls and I believe he simply put up Sonopan on the existing wall and added a resilient channel and two layers of drywall (no Green Glue and no resilient clips). He has told me that this improved the situation a lot (I was not here before he did this) but I can still hear lower frequencies well and even his tv and voices mutely. I definitely get the sense of an echo (those empty air spaces) and since one of the air spaces was quite small (size of a resilient channel) the resonance point(s) is (are) probably around the type of lower frequency I really would prefer not to hear. 

Can you provide me with some feedback on my 'plan'. Is there anything additional I should consider?

As well, a couple of architects said that I should make sure the drywall doesn't touch the walls, ceiling or floor, even in the case of a decoupled separate wall, like I want to build here. Is that the case? I have also been told (by someone at Green Glue and another person who works for Sonopan) that I should fit the drywall normally, flush with the walls, ceiling and floor and apply acoustical caulk around the perimeter to seal any cracks, the energy between the interfaces not being great enough to be an issue (and this also allows the mass of the drywall to cover the surface as completely as possible). I'm inclined to go with the latter (flush with the walls). What is your experience? 

Any help would be greatly appreciated!

Thanks!


----------



## james27587

*need help with decoupling*

Good evening everyone.
I am getting ready to build my HT but I am lost when it comes to decoupling.
My basement room is 15x21 with 9ft ceiling. 2 walls are 10 inch poured concrete and above are joists with spaces (don't know what they called)
Now I am reading about clips and channels as well as room within a room.
So the questions are 
1)do I use clips with room within room construction ?
2)with all the crap in the joists I may have to attach drywall to the joists. Can I build secondary decoupled wall and still attach drywall to the ceiling ? It seems like I would be loosing the benefit of the decoupled walls. Am I wrong ?
3)when you build a room within a room, what are the secondary joists attached o ? Just the interior walls? Will that be strong enough?
4)With concrete floors, do I l need to treat the floors, subfloors etc ?
Thank you for all your help


James


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## ronny31

It would be easier if you scanned your building plans so we can see the configuration of the concrete walls, and the position of the HT room compared to the rest. More resources are put in some areas (the ceiling for one, if this is a basement with wood ceiling), and less in other areas.


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## PerryH

I looked through the thread. I did not see this, but I might have missed it.

Do people generally use the clips and/or double drywall on walls that have poured concrete or concrete block behind them or are those okay to leave alone?


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## granroth

PerryH said:


> I looked through the thread. I did not see this, but I might have missed it.
> 
> Do people generally use the clips and/or double drywall on walls that have poured concrete or concrete block behind them or are those okay to leave alone?


It depends on the level of sound isolation that you are after. Concrete walls will perform quite a bit better than standard stick walls, but they aren't magic. You can expect STC values in the 40s to maybe the low 50s with standard 8" thick concrete (the former typically with blocks and the latter typically with poured). If that's all the isolation you require, then you're golden!

But if you are wanting isolution in the STC 60 to 70 category, then you really need a double wall, with additional isolated mass. That'll bring it to the next level.

In general, though, it's typically not a big deal to create a "double wall" if you're working with concrete. That's because you aren't going to attach drywall or similar directly to the concrete and will have to have some sort of furring strips at the least. This will give you a gap and another set of mass. Increasing that gap and maybe creating an interior wall or adding clips isn't an unreasonable thing to do at this point.

BTW, I'm assuming here that you are referring to standalone buildings with concrete walls and not basements. Basements are their own category due to the soil behind the walls.


----------



## PerryH

Thanks,

Actually, I am asking with regard to basement walls. Two walls of my room are poured basement walls completed underground and already drywalled (the room was finished by the previous owner).


----------



## granroth

PerryH said:


> Thanks,
> 
> Actually, I am asking with regard to basement walls. Two walls of my room are poured basement walls completed underground and already drywalled (the room was finished by the previous owner).


Ah, okay. What comes into play there is going to be "flanking" noise. The two exterior walls will have close to perfect sound reduction... but that's likely not where you're wanting the isolation in the first place. You typically want the isolation in the direction of where people are -- e.g., upstairs or possibly elsewhere in the basement.

If you have a typical ceiling with joists resting on the foundation walls and then one layer of drywall on the joists, then you're going to have a notable amount of sound leakage above you. The exterior walls will literally do nothing in this case. The standard approach to rectify this is to perform the normal soundproofing methods on the ceiling, which include decoupling it (clips); adding mass (multiple layers of drywall) with damping (Green Glue); and adding absorption (insulation). That will have an inherent ability to attenuate the sound.

Alas, if you're wanting the highest levels of sound isolation, then flanking becomes a big part of this. What'll happen is that sound will travel up the exterior walls to your joists and then radiate up to the living areas from there. That sound path completely bypasses all of the soundproofing efforts you made on the ceiling. I'm not saying that your soundproofed ceiling does nothing -- it does quite a bit. I'm just saying that it won't be as complete a solution as you might think, because of the flanking paths.

So in that's where doing a complete soundproofing solution in the entire room makes sense. If the two exterior wall sides are decoupled and have additional mass, then you don't have the same easy and direct path for the sound to flank around. It bumps this all up to the next level.

Do you need all that? That 100% depends on what your goals are. If you just want it to be "quieter" (e.g., play a movie at 80dB and just barely hear it upstairs), then you can achieve that pretty easily without really sweating all of the minute details. If, though, you want to blast your movies with peaks over 100dB and you want even those scenes to be completely quiet (maybe a 70dB drop)... well, now every single detail matters. There are absolutely no shortcuts and no "maybe I could skip this step" bits.


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## lovingdvd

PerryH said:


> I looked through the thread. I did not see this, but I might have missed it.
> 
> Do people generally use the clips and/or double drywall on walls that have poured concrete or concrete block behind them or are those okay to leave alone?


This article may help: http://www.soundproofingcompany.com...orried-about-sound-heading-straight-upstairs/

Another reason to use clips and channels on foundation walls is if you are already doing that for other non-foundation walls in the room - because that way they will all surfaces will have the same resonance / acoustical characteristics.


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## cyclonus714

PerryH said:


> I looked through the thread. I did not see this, but I might have missed it.
> 
> Do people generally use the clips and/or double drywall on walls that have poured concrete or concrete block behind them or are those okay to leave alone?


Typically, with foundation walls, if they aren't drywalled over (ie they are unfinished), you'd build a stud wall with a small gap, like 1", away from the foundation wall to have it decoupled. 

If something is already decoupled, you don't need clips to decouple. Then you would DD/GG the decoupled stud wall.


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## ctviggen

cyclonus714 said:


> Typically, with foundation walls, if they aren't drywalled over (ie they are unfinished), you'd build a stud wall with a small gap, like 1", away from the foundation wall to have it decoupled.
> 
> If something is already decoupled, you don't need clips to decouple. Then you would DD/GG the decoupled stud wall.


Thanks for that. I had the same question. I will likely put some 2 inch foam panels on the foundation wall, though, then the gap, then the DD/GG wall.


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## jcr159

Ok, so I was just reading on Ted's site (http://www.soundproofingcompany.com/soundproofing-articles/watch-out-for-the-stairs/) about watching out for flanking in the stair case. I thought I had accounted for that with a heavy door with sealing jamb and sill, but it sounds like I'm fooling myself. 

I didn't see a recommendation from Ted on how to deal with the sound transmission from the stair case... Anyone have advice? I didn't see anything specifically mentioning that here..

thx!


----------



## granroth

jcr159 said:


> Ok, so I was just reading on Ted's site (http://www.soundproofingcompany.com/soundproofing-articles/watch-out-for-the-stairs/) about watching out for flanking in the stair case. I thought I had accounted for that with a heavy door with sealing jamb and sill, but it sounds like I'm fooling myself.
> 
> I didn't see a recommendation from Ted on how to deal with the sound transmission from the stair case... Anyone have advice? I didn't see anything specifically mentioning that here..


Well, his core advice is to not use the staircase as part of the room. As long as your room's walls are separate and don't physically touch the staircase, then you should be fine.

If the staircase is absolutely going to be part of the room... well, there's not a lot you can do. As he writes, there is a direct connection throughout the structure to guarantee an almost perfect flanking path. Your best bet would be to not try to incorporate the stairway but rather to create a separate inner wall with its own mass; damping; and decoupling that attempts to attenuate as much of the sound as possible before it gets to the stairway.


----------



## jcr159

Thanks @granroth, that's what I was afraid of... 

New house, and the plan is for a multipurpose room layout in the basement. Probably not an option to put the door at the bottom to seal up the space, so I wonder if I'd get any benefit from decoupling the ceiling/walls, and dd+gg all around if everything is going to flank through the staircase anyway.... Maybe I should just put a solid sealed door at the top of the staircase, and traditional walls and ceilings with 5/8 drywall and call it a day. 

It would be a lot easier and cheaper than multiple layers plus gg and backer boxes in the ceiling, and putty pads, etc, etc....

I sure can't think of a way to decouple the staircase without putting the door at the bottom(which allows the room to seal up separate from the staircase).


----------



## arcamm

Conflicting information;


I'm finishing a addition on my house. The downstairs is going to be my media room and the upstairs is my wife's sitting room. I like to listen to my music loud and I would prefer to stop as much of it as possible from going up through the floor. 


The ceiling construction is 2"x9.5" I beams, 3/4" t&g floor panel, 3/4" grooved panel for 1/2" radiant tubing and 1/2" floating engineered wood flooring.


I'm considering green gluing two layers of 5/8" drywall to the bottom of the floor, a batt of Roxal, one of the resilient clips and channel setups with 5/8" drywall. Does this sound like a good solution? I'm most concerned about sound going up.


The conflicting part is that one of trusted insulators, told me that he is seeing the home theater building companies (that he does a lot of work for) are just foaming the underside of the floor (two to three inches) od OC foam, adding a layer of insulation, then nailing up a layer of carpet padding, then 5/8" dry wall. Would this be a viable solution? 


Thanks


----------



## jrref

arcamm said:


> Conflicting information;
> 
> 
> I'm finishing a addition on my house. The downstairs is going to be my media room and the upstairs is my wife's sitting room. I like to listen to my music loud and I would prefer to stop as much of it as possible from going up through the floor.
> 
> 
> The ceiling construction is 2"x9.5" I beams, 3/4" t&g floor panel, 3/4" grooved panel for 1/2" radiant tubing and 1/2" floating engineered wood flooring.
> 
> 
> I'm considering green gluing two layers of 5/8" drywall to the bottom of the floor, a batt of Roxal, one of the resilient clips and channel setups with 5/8" drywall. Does this sound like a good solution? I'm most concerned about sound going up.
> 
> 
> The conflicting part is that one of trusted insulators, told me that he is seeing the home theater building companies (that he does a lot of work for) are just foaming the underside of the floor (two to three inches) od OC foam, adding a layer of insulation, then nailing up a layer of carpet padding, then 5/8" dry wall. Would this be a viable solution?
> 
> 
> Thanks


The OC foam is ok to add to the insulation But you are never going to stop the sound transfer until you add more mass to the ceiling. The more mass the more sound energy it takes to vibrate it. Simple physics. You can try all of the methods you want and they will all help but adding mass will give you the largest sound attenuation.

And BTW I would never put drywall over carpet padding because over time the carpet padding will deteriorate. Also you need to install a product that is made for the ceiling because over time some methods will cause the ceiling to sag. It's not like a wall. Whatever you install has to support it's own weight.


----------



## arcamm

Thanks John. I'm not interested in experimenting or redoing it in the future. I'll stick with what works. I'm supplying the labor, so it's strictly material cost. $800 for green glue and drywall or $500 for the foam. Small price to pay for something that works.


----------



## jrref

arcamm said:


> Thanks John. I'm not interested in experimenting or redoing it in the future. I'll stick with what works. I'm supplying the labor, so it's strictly material cost. $800 for green glue and drywall or $500 for the foam. Small price to pay for something that works.


That will work but although it only helps a little, I would just put Roxul in the ceiling. The foam will work but the Roxul is made for soundproofing so no matter what anyone says, I would do that with the green glue and you should be good to go. The only other thing you need to worry about is if your walls are sheetrock, you will get some flanking between the 2x4's in the wall to the ceiling structure. To fix that you would use green glue and sheetrock on the walls as well. The option you have is to do the ceiling, see how it goes and if it's not enough then do the green glue and another layer of 5/8 sheetrock over the existing drywall. Or you can just play your music a little lower lol that's the cheapest solution.


----------



## arcamm

The basement (media room) walls are Superior pre-cast walls. They are concrete covered with Styrofoam and metal studs for a nailing/screw surface.


----------



## edmunddante

*Help needed with ceiling treatment*

Hi Everyone,

New to the forum and have spent many hours researching how best to soundproof my ceiling. I am finishing 700 sqft of my basement for use as a rec room. It will have a media wall with 5.1 surround (dont listen to music crazy loud).

Ceiling height is low and every inch I can gain counts.

My original plan was to spray foam 2-3 inches to joist cavity, insulate with Roxul, resilient channel, and 5/8 drywall. 

Now that I am into the build I am struggling to get 78" with trim installed due to the ductwork bulkheads.

I would like advise on whether I can forgo the resilient channel and 5/8" drywall and install QuiteRock instead directly to the joists. What about adding GreenGlue directly to the joist before hanging Quit Rock? 

This will gain me a 1/2" of headroom under my bulkheads and ultimately get me 78" doors with full trim.

I will be using 2" led potlights that are retrofit but dont need an insulated box and will build MDF boxes if need be.

Any help is appreciated. Cheers!


----------



## jrref

edmunddante said:


> Hi Everyone,
> 
> New to the forum and have spent many hours researching how best to soundproof my ceiling. I am finishing 700 sqft of my basement for use as a rec room. It will have a media wall with 5.1 surround (dont listen to music crazy loud).
> 
> Ceiling height is low and every inch I can gain counts.
> 
> My original plan was to spray foam 2-3 inches to joist cavity, insulate with Roxul, resilient channel, and 5/8 drywall.
> 
> Now that I am into the build I am struggling to get 78" with trim installed due to the ductwork bulkheads.
> 
> I would like advise on whether I can forgo the resilient channel and 5/8" drywall and install QuiteRock instead directly to the joists. What about adding GreenGlue directly to the joist before hanging Quit Rock?
> 
> This will gain me a 1/2" of headroom under my bulkheads and ultimately get me 78" doors with full trim.
> 
> I will be using 2" led potlights that are retrofit but dont need an insulated box and will build MDF boxes if need be.
> 
> Any help is appreciated. Cheers!


You can use quietrock or green glue. You will get results very close to using channels and clips. If you use quiet rock check that the type that you are buying can be used on the ceiling. There has always been discussion of problems with longevity using channels and clips or anything else on the ceiling. I believe quietrock has a specific product for ceilings. National Gypsum has a product called SoundBreak XP which is similar to quietrock and can be used on the ceiling and is a lot cheaper.


----------



## kmhvball

edmunddante said:


> I would like advise on whether I can forgo the resilient channel and 5/8" drywall and install QuiteRock instead directly to the joists. What about adding GreenGlue directly to the joist before hanging Quit Rock?
> 
> This will gain me a 1/2" of headroom under my bulkheads and ultimately get me 78" doors with full trim.





jrref said:


> You can use quietrock or green glue. You will get results very close to using channels and clips.


I tend to disagree with this. 

I think quietrock vs two layers of 5/8" dw with green glue might be ball park same, but clips and channel serve to decouple vs a mass benefit.

Decoupling is key, as sound tends to move through solid structures. Clips and channel reduce transmission area substantially.

I basically only read a bunch on this, so, I have never conducted testing of my own. 

Others may perspective as well.


----------



## edmunddante

kmhvball said:


> I tend to disagree with this.
> 
> I think quietrock vs two layers of 5/8" dw with green glue might be ball park same, but clips and channel serve to decouple vs a mass benefit.
> 
> Decoupling is key, as sound tends to move through solid structures. Clips and channel reduce transmission area substantially.
> 
> I basically only read a bunch on this, so, I have never conducted testing of my own.
> 
> Others may perspective as well.


Thanks for the feedback. If my ceiling height allows I will go for the resilient channel and maybe add the quite rock or Soundbreak panels to get the best of both.

Thanks!


----------



## cw5billwade

you can put straps between the floor joist and then the clips and channel run parallel to the floor joist up inside look at Beasts build thread. That way you only need to give up 1/4 inch or so over the entire clip and channel depth of 2"

http://www.avsforum.com/forum/19-dedicated-theater-design-construction/1498937-beast-unleashed.html


----------



## jrref

Nothing is going to be better than adding mass. It's simple physics. The more mass, the more energy it is going to take to vibrate the barrier. Also do some research. From what I understand, combining methods such as channels and clips with quiet rock or green glue does not give a linear improvement. And you need to be careful because I've heard of clips and channels failing on ceilings when you add a lot of mass. You are best off using Quiet Rock or Green Glue and forget about the channels and clips or just use the channels and clips but not both.

So here's an example:
I live in a condo with a common wall. With music playing at 100db in my neighbors unit, after adding Roxul and 5/8 inch Quiet Rock, I measure about 50db on my side of the wall. Now if I add another 5/8 inch Quiet Rock on my side, will I get another 50db attenuation? No because the attenuation is not linear. If I had installed clips and channels and Quiet Rock would I do better than 50 db attenuation, Yes but it would probably be another 5-10db max, maybe. The reason why I say maybe is because some of the sound is flanking through the ceiling and the floor and its very difficult if not impossible to control that and the attenuation is not linear. It's kind of like adding more insulation to an already well insulated attic. You will get less benefit as you keep adding insulation beyond a certain point.

Just my opinion from using this stuff.


----------



## edmunddante

jrref said:


> Nothing is going to be better than adding mass. It's simple physics. The more mass, the more energy it is going to take to vibrate the barrier. Also do some research. From what I understand, combining methods such as channels and clips with quiet rock or green glue does not give a linear improvement. And you need to be careful because I've heard of clips and channels failing on ceilings when you add a lot of mass. You are best off using Quiet Rock or Green Glue and forget about the channels and clips or just use the channels and clips but not both.
> 
> So here's an example:
> I live in a condo with a common wall. With music playing at 100db in my neighbors unit, after adding Roxul and 5/8 inch Quiet Rock, I measure about 50db on my side of the wall. Now if I add another 5/8 inch Quiet Rock on my side, will I get another 50db attenuation? No because the attenuation is not linear. If I had installed clips and channels and Quiet Rock would I do better than 50 db attenuation, Yes but it would probably be another 5-10db max, maybe. The reason why I say maybe is because some of the sound is flanking through the ceiling and the floor and its very difficult if not impossible to control that and the attenuation is not linear. It's kind of like adding more insulation to an already well insulated attic. You will get less benefit as you keep adding insulation beyond a certain point.
> 
> Just my opinion from using this stuff.


I've done more research and if I put up the resilient and or clips I am concerned about shorting out the channel. It seems very likely to happen and there is a high failure rate. i also looked into quiet rock and it is not approved for ceilings.

I like the idea of putting up blocking between the joists to gain back the headroom though. That is a great idea!

I'm thinking two layers of 5/8" drywall with GG might be best approach.

I will look more into the Soundtrack.


----------



## lovingdvd

edmunddante said:


> I've done more research and if I put up the resilient and or clips I am concerned about shorting out the channel. It seems very likely to happen and there is a high failure rate. i also looked into quiet rock and it is not approved for ceilings.
> 
> I like the idea of putting up blocking between the joists to gain back the headroom though. That is a great idea!
> 
> I'm thinking two layers of 5/8" drywall with GG might be best approach.
> 
> I will look more into the Soundtrack.


I'm a bit confused - seems like you are saying you are weary of clips and channels holding up over time and then go on to say you are interested in putting blocking in the ceiling to gain the headroom with it. Am I not following?

I hadn't heard anything about the longevity of clips and channels, but then again that's not a question I thought to ask about - even though its a great one. I am leaning toward using Kinetics Wave Hangers which work a bit differently. There's a thread around here if you look for it. Because of the way they are designed I would think that they are less prone to failing (because the channel sits fully into the wave hanger as a "bracket") even if the other approach isn't really prone at all.


----------



## kmhvball

edmunddante said:


> I've done more research and if I put up the resilient and or clips I am concerned about shorting out the channel. It seems very likely to happen and there is a high failure rate. i also looked into quiet rock and it is not approved for ceilings.
> 
> I like the idea of putting up blocking between the joists to gain back the headroom though. That is a great idea!
> 
> I'm thinking two layers of 5/8" drywall with GG might be best approach.
> 
> I will look more into the Soundtrack.


I have heard/read of issues with resilient channel being more prone to errors and thus nor as optimal results. If you use clips and hat channel, there isn't really a risk of coupling with a misplaced screw.

If you are talking more, Ling term structural failure, I have never read about that.


----------



## jrref

edmunddante said:


> I've done more research and if I put up the resilient and or clips I am concerned about shorting out the channel. It seems very likely to happen and there is a high failure rate. i also looked into quiet rock and it is not approved for ceilings.
> 
> I like the idea of putting up blocking between the joists to gain back the headroom though. That is a great idea!
> 
> I'm thinking two layers of 5/8" drywall with GG might be best approach.
> 
> I will look more into the Soundtrack.


National Gypsum has a product called SoundBreak XP which is similar to quietrock and can be used on the ceiling and is a lot cheaper.


----------



## edmunddante

lovingdvd said:


> I'm a bit confused - seems like you are saying you are weary of clips and channels holding up over time and then go on to say you are interested in putting blocking in the ceiling to gain the headroom with it. Am I not following?
> 
> I hadn't heard anything about the longevity of clips and channels, but then again that's not a question I thought to ask about - even though its a great one. I am leaning toward using Kinetics Wave Hangers which work a bit differently. There's a thread around here if you look for it. Because of the way they are designed I would think that they are less prone to failing (because the channel sits fully into the wave hanger as a "bracket") even if the other approach isn't really prone at all.


Let me help clarify....

I am not worried about clips failing. But more worried that I will install it incorrectly! All it takes it one screw in the wrong place or mudding and taping the corners and all is compromised. Shorting=Fail.

I hadn't thought about installing the clips higher in the ceiling using blocking that is a great idea! But its a lot of work to block out all the joist cavities to make room for clips. More time + more money.

I agree long term there should be no problem wit the structure failing. The QuietRock website doesn't recommend their product on the ceiling because it can sag over time.

What I am trying to discern is whether to just go two lanes of drywall to the existing ceiling joists and forgo the channel.


----------



## cw5billwade

edmunddante said:


> Let me help clarify....
> 
> I am not worried about clips failing. But more worried that I will install it incorrectly! All it takes it one screw in the wrong place or mudding and taping the corners and all is compromised. Shorting=Fail.
> 
> I hadn't thought about installing the clips higher in the ceiling using blocking that is a great idea! But its a lot of work to block out all the joist cavities to make room for clips. More time + more money.
> 
> I agree long term there should be no problem wit the structure failing. The QuietRock website doesn't recommend their product on the ceiling because it can sag over time.
> 
> What I am trying to discern is whether to just go two lanes of drywall to the existing ceiling joists and forgo the channel.


Yes there is a huge difference over resilientchannel and Hat channel you want the hat channel with IB-1 clips that is what Iused. You can use the Whisper clips but John from sound proofing company saidthat for the money there was not that much of a performance gain. You insurethat you use different length drywall metal screws so that the screw will nevertouch a 2x4 even if you screw directly over one. Unlike drywall screw into woodwhere you need a good 1/2" or better to bite into the stud. You only need1/8" or so to bite into hat channel so the first layer a 1" screwwill be all you need and a 1 3/4" screw for the second layer. The screwwill never short out the system that way. About the corners if all the wallsand ceiling are decoupled then no issue with mud and tape in the corners atall. I have 5/8” OSB GG and Drywall with coffers and soffits screwed directlyinto the hat channel. You just need to plan for it and ad a extra channel wherethe weight of the soffit and coffer will be. They build hotels this way it isan industry standard so no need to worry about failure. you decouple the wals with IB3 Clips.


----------



## lovingdvd

I'm getting ready to build my dedicated theater room. First I have to do demolition on the existing room which has 1/2" drywall. I plan to use Kinetics wave hangers on ceiling and clips/channels on walls.

My original plan was to tear out out drywall. But instead I am thinking I should cut it out in strips between the joists. Then reuse it for the underside of the sub-floor above. I've heard some people say that adding drywall to the underside can help a little but generally not worth bothering with. But in this case I think it can help because part of the area above the theater has hardwood floors and footsteps are quite noticeable. And I'd like to be able to contain the bass as much as possible within the room.

So I thought I'd cut out the existing ceiling in slices running along the joists (24" by X, whatever is a manageable length). Then put those same slices up on the underside of the sub-floor. Its only 1/2" but better than nothing. This way I get some additional benefit of the extra mass on the ceiling, and also I have that much less drywall to dispose of. It also seems like an easier way to take the drywall off compared to just ripping it.

Questions:

1. Does this make sense?

2. I should put green-glue on this before putting it up? How much glue?

3. What type of screws and screw length? The subfloor is about 5/8" or 3/4" ply (I can't tell for sure but I think 3/4"_, drywall is 1/2". So maybe 3/4" screws? How far apart should each screw be? Keep in mind these will be lots of smaller pieces as I will likely cut them down in 24"x24" or 24"x36" strips, whatever is easiest.

Thanks!


----------



## kmhvball

lovingdvd said:


> I'm getting ready to build my dedicated theater room. First I have to do demolition on the existing room which has 1/2" drywall. I plan to use Kinetics wave hangers on ceiling and clips/channels on walls.
> 
> My original plan was to tear out out drywall. But instead I am thinking I should cut it out in strips between the joists. Then reuse it for the underside of the sub-floor above. I've heard some people say that adding drywall to the underside can help a little but generally not worth bothering with. But in this case I think it can help because part of the area above the theater has hardwood floors and footsteps are quite noticeable. And I'd like to be able to contain the bass as much as possible within the room.
> 
> So I thought I'd cut out the existing ceiling in slices running along the joists (24" by X, whatever is a manageable length). Then put those same slices up on the underside of the sub-floor. Its only 1/2" but better than nothing. This way I get some additional benefit of the extra mass on the ceiling, and also I have that much less drywall to dispose of. It also seems like an easier way to take the drywall off compared to just ripping it.
> 
> Questions:
> 
> 1. Does this make sense?
> 
> 2. I should put green-glue on this before putting it up? How much glue?
> 
> 3. What type of screws and screw length? The subfloor is about 5/8" or 3/4" ply (I can't tell for sure but I think 3/4"_, drywall is 1/2". So maybe 3/4" screws? How far apart should each screw be? Keep in mind these will be lots of smaller pieces as I will likely cut them down in 24"x24" or 24"x36" strips, whatever is easiest.
> 
> Thanks!


I don't know how much time it takes to cut nicely vs simply rip out, but in general it sounds like it would make sense to me. 

I did two layers of 5/8" DW, with GG on each layer, attached to my sub-floor. I have hardwood floor above the theater. I used about what looked like the same coverage of Green Glue as doing a whole board... in terms of about the same share of surface area covered with GG vs not covered. Certainly if you use 24" x 48", you would use more/piece than if you did 24" x 24" pieces. It wasn't an exact science for me.

I think most of my strips were 48" wide by the narrower dimension (mine were closer to 18" vs 24"). With 24" 'on center" floor joists, the space between the joists would be ~ 22.5". It might be worthwhile to try and keep them in the same rows you cut them out. My floor joists were all spaced a little differently, so, if you don't keep them straight - you might need to recut or have gaps.

I would think with 1/2" drywall and and least 1/2" plywood, I would be inclined to use 1" screws. I had 5/8" drywall and 3/4" subfloor plywood, and used 1 1/4" on my first layer, and 2" on my second layer. My theory was even if my 2" screws slightly penetrated through the sub-floor into the main flooring above, given I had wood flooring above - it didn't matter much. If I had some very thin flooring above the subfloor - maybe I would have been more concerned.


----------



## lovingdvd

kmhvball said:


> I don't know how much time it takes to cut nicely vs simply rip out, but in general it sounds like it would make sense to me.
> 
> I did two layers of 5/8" DW, with GG on each layer, attached to my sub-floor. I have hardwood floor above the theater. I used about what looked like the same coverage of Green Glue as doing a whole board... in terms of about the same share of surface area covered with GG vs not covered. Certainly if you use 24" x 48", you would use more/piece than if you did 24" x 24" pieces. It wasn't an exact science for me.


Thanks. Were you happy with the end result, as far as cutting the noise from footsteps in the hardwood floors? What did you do for your ceiling itself (beyond the double DW on the subfloor)?



> I would think with 1/2" drywall and and least 1/2" plywood, I would be inclined to use 1" screws. I had 5/8" drywall and 3/4" subfloor plywood, and used 1 1/4" on my first layer, and 2" on my second layer. My theory was even if my 2" screws slightly penetrated through the sub-floor into the main flooring above, given I had wood flooring above - it didn't matter much. If I had some very thin flooring above the subfloor - maybe I would have been more concerned.


I'd want the screws to have a good "bite" into the wood but not penetrate. With 1/2" DW and I'll call it 5/8" subfloor I'd say I'd be included to use 1" screws, I suppose.

Also I have metal ducts running in a few of those joists which will not be coming out, to bring air to the upstairs level. Would you recommend temporarily removing them so I can get to the subfloor for the DW+GG install and then put them back in? I'd be tempted to replace them with flex duct as long as it wouldn't cut down the airflow to the upstairs. A different HVAC until entirely will be used for the theater.


----------



## kmhvball

lovingdvd said:


> Thanks. Were you happy with the end result, as far as cutting the noise from footsteps in the hardwood floors? What did you do for your ceiling itself (beyond the double DW on the subfloor)?
> 
> 
> I'd want the screws to have a good "bite" into the wood but not penetrate. With 1/2" DW and I'll call it 5/8" subfloor I'd say I'd be included to use 1" screws, I suppose.
> 
> Also I have metal ducts running in a few of those joists which will not be coming out, to bring air to the upstairs level. Would you recommend temporarily removing them so I can get to the subfloor for the DW+GG install and then put them back in? I'd be tempted to replace them with flex duct as long as it wouldn't cut down the airflow to the upstairs. A different HVAC until entirely will be used for the theater.


On my ceiling itself, i did clips & channel, with two layers of 5/8" drywall, GG in between...and insulation above it.

Yes, I am quite pleased overall with my Sound Proofing efforts. I even have a giant 'hole' in my efforts where my electric panel is, and still am pleased with the result. I had a tentative plan to create a door/cover on the electric panel - but thus far, haven't found a need to do it.

Caveat - Yesterday I received the first of my two UXL-18" subwoofer drivers, so, haven't had any real bass to speak of, and since that is one of the largest offenders, I won't be surprised if I struggle to contain that. 

I had rigid HVAC supply piping in between my joists, and did as you say... pulled them out, put the DW on the sub-floor, and then replaced with Flex duct. I can't say that I noticed a difference in the upstairs HVAC performance, but that isn't to say there wasn't a difference, just for my personally - it was not noticeable. I think I read somewhere that flex pipe does reduce air flow somewhat, but not sure how much. I did not 'snake' the flex pipe around, I pulled it fairly tight as I didn't want to cause to much air flow obstruction. Part of my decision was that I had read the flex duct transmits less sound waves, so I viewed it as an additional part of my soundproofing plan. 

If my wife or daughter are up for it, which many times they aren't, I could have them walk in our master bedroom which has a single layer of DW on the subfloor (and same insulation, 2 layers DW on ceiling), and then walk in the theater with 2 layers of dw on the subfloor, and provide a qualitative assessment of whether I notice much difference. I have a 'sound meter' on my phone and could attempt to use it, but that would be fairly rough data.


----------



## arcamm

I've decided to go with the double 5/8" drywall Green Glued to the bottom of the subfloor, Roxal and clips with hat channel on my basement room ceiling. 


Next question is the ceiling joists are I-beams. The space between the webs is 15.75" and the Roxal batts are only 15.25" leaving a gap. Is this anything to worry about or should the Roxal be tight between the I-beams?


----------



## jrref

arcamm said:


> I've decided to go with the double 5/8" drywall Green Glued to the bottom of the subfloor, Roxal and clips with hat channel on my basement room ceiling.
> 
> 
> Next question is the ceiling joists are I-beams. The space between the webs is 15.75" and the Roxal batts are only 15.25" leaving a gap. Is this anything to worry about or should the Roxal be tight between the I-beams?


It has to be tight between the beams. You have two choices:
1) cut a .50 strip of roxul to make up the difference
2) see if you can get roxul safe and sound in 24 inches which they do have in their comfort batt.

Either way it will cost you more but you are only doing this once.


----------



## jrref

arcamm said:


> I've decided to go with the double 5/8" drywall Green Glued to the bottom of the subfloor, Roxal and clips with hat channel on my basement room ceiling.
> 
> 
> Next question is the ceiling joists are I-beams. The space between the webs is 15.75" and the Roxal batts are only 15.25" leaving a gap. Is this anything to worry about or should the Roxal be tight between the I-beams?


It has to be tight between the beams. You have two choices:
1) cut a .50 strip of roxul to make up the difference
2) see if you can get roxul safe and sound in 24 inches which they do have in their comfort batt.

Either way it will cost you more but you are only doing this once.


----------



## arcamm

jrref said:


> It has to be tight between the beams. You have two choices:
> 1) cut a .50 strip of roxul to make up the difference
> 2) see if you can get roxul safe and sound in 24 inches which they do have in their comfort batt.
> 
> Either way it will cost you more but you are only doing this once.




Thanks. I'm not worried so much about the cost if it means working or working better. Roxal has a product for steel studs that is 16.25 wide, but not carried by the local big box stores. If I can find it, it looks like the best way to go.


----------



## Waterboy77

arcamm said:


> I've decided to go with the double 5/8" drywall Green Glued to the bottom of the subfloor, Roxal and clips with hat channel on my basement room ceiling.
> 
> 
> Next question is the ceiling joists are I-beams. The space between the webs is 15.75" and the Roxal batts are only 15.25" leaving a gap. Is this anything to worry about or should the Roxal be tight between the I-beams?



I have been buying the 24" and cutting it cross wise to the width I need. there is a bit of waste at the end but there is always some where to stuff it


----------



## lovingdvd

jrref said:


> It has to be tight between the beams. You have two choices:
> 1) cut a .50 strip of roxul to make up the difference
> 2) see if you can get roxul safe and sound in 24 inches which they do have in their comfort batt.
> 
> Either way it will cost you more but you are only doing this once.


How much better is the Roxul at soundproofing compared to basic "R-something" fiberglass batting? Home Depot sells a 2'x4' of the Roxul for $58?


----------



## Waterboy77

lovingdvd said:


> How much better is the Roxul at soundproofing compared to basic "R-something" fiberglass batting? Home Depot sells a 2'x4' of the Roxul for $58?


Great reference data from Bob Gold
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## lovingdvd

*Triple leaf and double stud wall questions*

A few questions please:

1. I'm considering doing double stud walls in my room, with the inner wall decoupled from the ceiling. Since room width is limited, I'm planning to use 2x3 instead of 2x4 for the inner wall, with a 0.5" air gap and staggering the studs of the inner wall in case they should warp they will not touch the studs on the outer wall. The foundation walls are already framed 2x4 and insulated so I will keep those as is.

So going from the outside to the insider, the layers will be: foundation wall, 2x4 studs filled with insulation, 5/8" drywall layer, 0.5" air gap, 2x3 studs isolated from the ceiling (using Kinetics CWCA clips or equivalent so that the top of the plate is isolated from the ceiling joists), insulation inside the 2x3 studs, 5/8" OSB, green glue, 5/8" drywall.

Side note - the ceiling will be Kinetics Wave Hangers, and will be put in after the double stud wall (so that the ceiling sits within the walls, acoustically caulked but not otherwise touching.

Does that sound like a good plan?

2. I'm aware of the triple leaf effect and want to be sure to avoid it. The question is whether the outside concrete foundation wall counts as a "leaf"? If so, then I think what I described above would be a triple leaf issue. If the foundation wall does not count, then there are only two leafs. 

3. In my research on double stud walls I came across another of articles talking about the risk of moisture within the double wall system. Where I live the summers are around 80-100 degrees (sometimes up to 105) and the winters are usually in the 20s and 30s, sometimes warmer and sometimes much colder such as single digits and occasionally around zero or even below. Do I need to be concerned about moisture and if so, how should I address it?

Thanks!


----------



## RedStripe88

lovingdvd said:


> A few questions please:
> 
> 1. I'm considering doing double stud walls in my room, with the inner wall decoupled from the ceiling. Since room width is limited, I'm planning to use 2x3 instead of 2x4 for the inner wall, with a 0.5" air gap and staggering the studs of the inner wall in case they should warp they will not touch the studs on the outer wall. The foundation walls are already framed 2x4 and insulated so I will keep those as is.
> 
> So going from the outside to the insider, the layers will be: foundation wall, 2x4 studs filled with insulation, 5/8" drywall layer, 0.5" air gap, 2x3 studs isolated from the ceiling (using Kinetics CWCA clips or equivalent so that the top of the plate is isolated from the ceiling joists), insulation inside the 2x3 studs, 5/8" OSB, green glue, 5/8" drywall.
> 
> Side note - the ceiling will be Kinetics Wave Hangers, and will be put in after the double stud wall (so that the ceiling sits within the walls, acoustically caulked but not otherwise touching.
> 
> Does that sound like a good plan?
> 
> 2. I'm aware of the triple leaf effect and want to be sure to avoid it. The question is whether the outside concrete foundation wall counts as a "leaf"? If so, then I think what I described above would be a triple leaf issue. If the foundation wall does not count, then there are only two leafs.
> 
> 3. In my research on double stud walls I came across another of articles talking about the risk of moisture within the double wall system. Where I live the summers are around 80-100 degrees (sometimes up to 105) and the winters are usually in the 20s and 30s, sometimes warmer and sometimes much colder such as single digits and occasionally around zero or even below. Do I need to be concerned about moisture and if so, how should I address it?
> 
> Thanks!


You don't need the 5/8" drywall on the existing 2x4" wall in that configuration.

If you are able to decouple the 2x4" wall that is next to the foundation, you could avoid building the 2x3" wall and save some room width/length. Then you could install the OSB/GG/5/8" drywall on the 2x4 wall. 

The other alternative is to use clips/channel on the existing 2x4" wall which would also save you width/length versus the 2x3" wall with 0.5" air gap.


----------



## lovingdvd

RedStripe88 said:


> You don't need the 5/8" drywall on the existing 2x4" wall in that configuration.


Thanks. I didn't quote follow this. If I didn't have the 5/8" drywall on the existing 2x4" then it would just be studs.  Perhaps you thought I meant that I was going to add 5/8" to the existing wall next to the foundation? If so, sorry about that - just to clarify, I meant that I would strip out the 1/2" drywall on the foundation wall and replace it with 5/8".



> If you are able to decouple the 2x4" wall that is next to the foundation, you could avoid building the 2x3" wall and save some room width/length. Then you could install the OSB/GG/5/8" drywall on the 2x4 wall.


Doh! Why didn't I think of that?  Wow you just saved me a ton of work, I think. This saves me 4" of room width (3.5" from 2x4 depth plus 0.5 inch air gap). I'd still lose 4" from the back right side which is an interior wall, but 4" is a lot better than 8" if I had to do it on both sides.

So let me see if I have this straight. You are saying that I don't need to do a double stud wall against the foundation walls as long as I can decouple the top of the frame from the ceiling joists? So basically then I would tear out the existing 2x4 along the foundation walls, and rebuild it but have it stop before the ceiling joists, and use the CWCA or equivalent clips to attach the top plate to the joists, yes? 

If the answer above is Yes, the two follow up questions please:

1. Instead of ripping down all the 2x4 framing around the foundation, I'm wondering if it would be do-able to cut the existing stud wall down by a couple of inches, essentially reusing the entire wall. That may be harder to do since the framing is already up-right and in place, but it saves me on having to trash all the 2x4 foundation walls, haul it away, purchase new 2x4s and bring those materials in and build all new walls. Is that doable to try and reuse that framing or is it not going to be worth the trouble. Having never built a wall, ever, this is appealing as it would likely take me FAR longer to build these 2x4 walls then what it takes experienced folks.

2. There is one "jog out" in the back right side of the room. On the other side is a utility room with noisy stuff such as an HVAC unit, sump pump, and is also where I will put the equipment rack, dehumidifier and mini-split. So you can see why I need that to be well sound proofed... For this room I plan to do the double studded wall. Going from the utility room in toward the theater I'd have 5/8" DW, 2x3 (can't use a 2x4 here or otherwise there's no space to put 5/8" DW as the HVAC unit is 0.5" from the studs which don't currently have any DW on that side of the wall, insulation in the 2x3, 0.5" air gap, another 2x3 stud also filled with insulation and decoupled via CWCA clips, OSB, GG, 5/8". Do I have this right? So there are back to back 2x3 empty studs filled with insluation with a 0.5" air gap in between (and no DW or else it'll be triple leaf), yes?

3. Is it correct to assume that having the foundation walls done only decoupled without double stud and having this utility room wall done like this that it would not impact the room sonically due to different characteristics of the walls (they'd all be decoupled, but in the case around the utility room they'd be double studded).

4. The rear wall which has an interior room on the other side is also where the entrance will be (only choice). That wall is going to be huge with a double wall. Because I need 9.5" of depth for 15" in-wall custom subs Mark Seaton is building me.  So this means the rear wall is going to be about 10" deep on the inside, plus another 4" deep on the outside for the outter double studded wall. That's a 14" deep entrance way.  Any better way to handle the rear wall?



> The other alternative is to use clips/channel on the existing 2x4" wall which would also save you width/length versus the 2x3" wall with 0.5" air gap.


Yes. However in this case I think its a wash in terms of space. With approach 1 (decoupled walls on the foundation + double sided walls around the utility room) I only lose 4" in total, because no space is lost on the foundation side of the room and 4" is lost due to double studded 2x3 wall. With approach 2 (clips and channels everywhere) I still lose about 3-4" in total, as each side loses 1.5-2" due to clips and channels. Do I have this right?

Thanks!


----------



## lovingdvd

*Oops - am I creating a triple leaf problem with my star ceiling plans*

As I've been learning more about the triple leaf affect, it just dawned on me that my star ceiling plans may indeed create a triple leaf.

The current plan from ceiling of the theater going up to the floor in the room above is: 5/8" DW, GG, 5/8" OSB, hat channel, Kinetics Wave Hanger, insulation, 5/8" DW on underside of subfloor with GG.

So far so good. However here is where the issue may come in... My star ceiling plan is to get custom pre-made panels from FOSI. These panels are 3/4" ultralight MDF, with drilled holes for the fibers and fibers installed. These panels have 1" blocks on them for mounting so that when they are mounted to the ceiling there's a 1" gap for the fibers. This star ceiling will run virtually the entire ceiling, end to end in each direction, except for say a couple inches on each border. So now we have 3/4" ultralight MDF (leaf 1?), 1" air gap, 5/8" DW - GG, 5/8" OSB (together as leaf 2?), hat channel, Kinetics Wave Hanger, insulation, 5/8" DW on underside of subfloor with the subfloor now as leaf 3?

Does adding this star ceiling then create a triple leaf?  If it does it really messes up my plans for a star ceiling - any way around that?


----------



## RedStripe88

lovingdvd said:


> So let me see if I have this straight. You are saying that I don't need to do a double stud wall against the foundation walls as long as I can decouple the top of the frame from the ceiling joists? So basically then I would tear out the existing 2x4 along the foundation walls, and rebuild it but have it stop before the ceiling joists, and use the CWCA or equivalent clips to attach the top plate to the joists, yes?


Yes. The goal is to decouple the theater drywall from the rest of the house. If the foundation wall is decoupled from the ceiling joists, mission is accomplished. No double wall or clips and channel are needed.



lovingdvd said:


> 1. Instead of ripping down all the 2x4 framing around the foundation, I'm wondering if it would be do-able to cut the existing stud wall down by a couple of inches, essentially reusing the entire wall. That may be harder to do since the framing is already up-right and in place, but it saves me on having to trash all the 2x4 foundation walls, haul it away, purchase new 2x4s and bring those materials in and build all new walls. Is that doable to try and reuse that framing or is it not going to be worth the trouble. Having never built a wall, ever, this is appealing as it would likely take me FAR longer to build these 2x4 walls then what it takes experienced folks.


I'm guessing that a contractor would demo the current wall and build a new wall because the materials are less expensive than their time and they would charge you for the materials and disposal anyway. Plus, they can throw a simple stud wall together pretty quickly. I would probably try to cut the existing wall down by an inch or two if the existing construction doesn't make that prohibitively difficult. Might be tricky to cut the vertical studs level with a reciprocating saw.

That said, you don't have to trash all of the 2x4's if you rip down the wall and rebuild it. Just use a reciprocating saw to cut nails at the joints to save the existing studs.



lovingdvd said:


> 2. There is one "jog out" in the back right side of the room. On the other side is a utility room with noisy stuff such as an HVAC unit, sump pump, and is also where I will put the equipment rack, dehumidifier and mini-split. So you can see why I need that to be well sound proofed... For this room I plan to do the double studded wall. Going from the utility room in toward the theater I'd have 5/8" DW, 2x3 (can't use a 2x4 here or otherwise there's no space to put 5/8" DW as the HVAC unit is 0.5" from the studs which don't currently have any DW on that side of the wall, insulation in the 2x3, 0.5" air gap, another 2x3 stud also filled with insulation and decoupled via CWCA clips, OSB, GG, 5/8". Do I have this right? So there are back to back 2x3 empty studs filled with insluation with a 0.5" air gap in between (and no DW or else it'll be triple leaf), yes?


Yes. May be easier to put one layer of R-19 insulation that will fill the space in the two 2x3" stud walls. The insulation will not couple the 2 walls.



lovingdvd said:


> 3. Is it correct to assume that having the foundation walls done only decoupled without double stud and having this utility room wall done like this that it would not impact the room sonically due to different characteristics of the walls (they'd all be decoupled, but in the case around the utility room they'd be double studded).


I'm not the expert, but I don't think that construction will introduce problems. With 5/8" drywall/GG/OSB in the theater, you won't have much sound energy making the round trip from the theater through the wall and insulation and then back through the OSB/GG/5/8" drywall into the theater. If sound makes the round trip, I can't imagine you would be able to discern the difference in the sound energy based on the two construction methods.

But, I'll defer to others who may have tested this.



lovingdvd said:


> 4. The rear wall which has an interior room on the other side is also where the entrance will be (only choice). That wall is going to be huge with a double wall. Because I need 9.5" of depth for 15" in-wall custom subs Mark Seaton is building me.  So this means the rear wall is going to be about 10" deep on the inside, plus another 4" deep on the outside for the outter double studded wall. That's a 14" deep entrance way.  Any better way to handle the rear wall?


Sounds like you want the sub entirely hidden in the wall, and you want the rear wall flush with the front of subs, in other words no bump outs or columns? If so, the deep entrance way is difficult to avoid. You could probably come up with a design that makes it less tunnel like (e.g., first 8 inches one width, next 6 inches a bit wider/taller).

The most common approach I've seen is the use of columns to hide speakers/subs on the rear wall. Certainly easier than building out the entire wall. If you don't want the column to be too deep, you may be able to build a heavy duty backer box into the double wall so the sub is partially recessed in the backer box and partially hidden in the column.



lovingdvd said:


> Yes. However in this case I think its a wash in terms of space. With approach 1 (decoupled walls on the foundation + double sided walls around the utility room) I only lose 4" in total, because no space is lost on the foundation side of the room and 4" is lost due to double studded 2x3 wall. With approach 2 (clips and channels everywhere) I still lose about 3-4" in total, as each side loses 1.5-2" due to clips and channels. Do I have this right?


You can mix and match to minimize loss of space. Foundation walls decoupled, clips and channel on the ceiling and other walls.


----------



## kmhvball

lovingdvd said:


> A few questions please:
> 
> 3. In my research on double stud walls I came across another of articles talking about the risk of moisture within the double wall system. Where I live the summers are around 80-100 degrees (sometimes up to 105) and the winters are usually in the 20s and 30s, sometimes warmer and sometimes much colder such as single digits and occasionally around zero or even below. Do I need to be concerned about moisture and if so, how should I address it?
> 
> Thanks!


I believe the primary concern to to make sure if you have two layers of insulation, that only one is 'kraft faced'. On my existing foundation walls, the insulation was 'faced' as required. I hired the installation of insulation when I was building my basement, and when the people arrived they had 'faced' insulation, and they said that it couldn't be used 'as is' because if they used two different faced insulations, it could create moisture problems.

The ended up using the faced insulation on interior walls, and had to even rip the facing off some. 




lovingdvd said:


> So let me see if I have this straight. You are saying that I don't need to do a double stud wall against the foundation walls as long as I can decouple the top of the frame from the ceiling joists? So basically then I would tear out the existing 2x4 along the foundation walls, and rebuild it but have it stop before the ceiling joists, and use the CWCA or equivalent clips to attach the top plate to the joists, yes?
> 
> If the answer above is Yes, the two follow up questions please:
> 
> 1. Instead of ripping down all the 2x4 framing around the foundation, I'm wondering if it would be do-able to cut the existing stud wall down by a couple of inches, essentially reusing the entire wall. That may be harder to do since the framing is already up-right and in place, but it saves me on having to trash all the 2x4 foundation walls, haul it away, purchase new 2x4s and bring those materials in and build all new walls. Is that doable to try and reuse that framing or is it not going to be worth the trouble. Having never built a wall, ever, this is appealing as it would likely take me FAR longer to build these 2x4 walls then what it takes experienced folks.
> 
> Thanks!


If the walls against the foundation are Non-Load bearing (likely the case with a foundation wall next to it)... and they did a double top plate (i.e., 2 horizontal 2x4s on top of the vertical studs)... you might be able to 'notch' the top one under all the floor joists, thus decoupling the wall. You would then use a hanger of some sort (I used IB-3 clips) to anchor the wall to the floor joists. If the wall is touching the foundation wall, conventional wisdom would say it should be scooted off the wall. One of my walls, they put 1/2" polysterene sheeting on, and I pushed the stud wall up against in and have been pleased with it.

In terms of your rear wall being super deep... are you planning communicating entry doors? This really helps with sound escaping from the door opening. Having said that, with a sub-woofer in teh rear wall, I would certainly be concerned about the sound escaping from there - the 'backer box' strikes me as almost a requirement in that situation.


----------



## Waterboy77

I will be doing measurements with my db meter at each interval / layer of my "soundproofing". 
Short version of the story... I am only doing GG/DW/GG/DD on the underside of the subfloor between joists and only above theater area. Whole basement ceiling will get Ruxol.
Long version / more detail in my build thread

Any feedback on my technique from this POST would be greatly appreciated. Trying to avoid the inevitable "oh well you should have done XYZ" that always seems to happen 


I also have this posted in my thread but was thinking I might get more feedback here.




Waterboy77 said:


> I would like to test the before results of simulated foot fall. Here is what I am thinking for tonight / tomorrow morning
> Have my wife and or daughter walk heavily across the upstairs floor as I measure with my db meter below from MLP.
> This will give me a rough idea of the db to try to duplicate in a repeatable simulation.
> Then wrap a sledge hammer in a towel and drop from a set height and measure db below, vary height to "match" pervious measurement.
> Location of hammer drop to be directly above MLP
> 
> 
> THOUGHTS?
> 
> I want to get this done tonight so I can start installing GG / DW tomorrow
> Thanks


----------



## jrref

Waterboy77 said:


> I will be doing measurements with my db meter at each interval / layer of my "soundproofing".
> Sort version of the story... I am only doing GG/DW/GG/DD on the underside of the subfloor between joists and only above theater area. Whole basement ceiling will get Ruxol.
> Long version / more detail in my build thread
> 
> Any feedback on my technique from this POST would be greatly appreciated. Trying to avoid the inevitable "oh well you should have done XYZ" that always seems to happen
> 
> 
> I also have this posted in my thread but was thinking I might get more feedback here.


Sounds good, let us know what the results are.


----------



## trpltongue

All,

I'm dreaming about my eventual move back stateside and the return to my dedicated theater. I have installed hat channel and clips in the ceiling along with 2 layers of 5/8 drywall and green glue. However, now i want to do atmos. How would you tackle adding heavy ceiling speakers to an isolated ceiling without comprimising significantly on the height of the room? I have 9' ceilings now but there isn't much space for speakers to hang down without interferring with the projected image or hittting heads on the back row.


----------



## arcamm

Well that was sure fun! I got the two Green Glued layers of 5/8" dry wall up. 


Now a question about applying the sealant. Do I need to apply it to the seams that are tight against the I-beams and the second layer seams that are over the first layer of dry wall?


----------



## highhrider

Today the construction team is installing Quietrock 545THX to my walls with Greenglue sealant and Quietrock putty for the boxes. Insulation being used is Roxul safe and sound batts. My room size is 19x16.
Has anyone used these product?


----------



## jrref

arcamm said:


> Well that was sure fun! I got the two Green Glued layers of 5/8" dry wall up.
> 
> 
> Now a question about applying the sealant. Do I need to apply it to the seams that are tight against the I-beams and the second layer seams that are over the first layer of dry wall?


Yes, everything has to be air tight


----------



## jrref

highhrider said:


> Today the construction team is installing Quietrock 545THX to my walls with Greenglue sealant and Quietrock putty for the boxes. Insulation being used is Roxul safe and sound batts. My room size is 19x16.
> Has anyone used these product?


Yes, it's excellent!


----------



## warpedcore

Hey everyone,

Currently opening a large floatation therapy center where we planned on going all out for soundproofing in order to facilitate the most quiet space possible. Float tanks are essentially large basins filled with skin temperature neutral Epsom salt water (~1000lbs) that you float in; absence of sound, light and touch to help people relax, meditate, recover etc.

Obviously this requires a strong level of either soundproofing or ability to keep the facility extremely quiet.

My concern is that we've spent a fair bit of money, time and effort to put together ~60+ STC rated rooms and just as we've been putting up framing and drywall - I've come to the realization that our double stud setup might be compromised by the firewall/shared unit wall in between us and our neighbor - causing some form of _triple leaf effect_.

Rundown of our current setup and area of concern in bold:

- double studded (4") walls with double layer 5/8" drywall and green glue with R13.
- Air cavity of 10" between each room.
*- Air cavity of 6" from shared firewall/unit separator*
- 1-3/4" solid core doors with 1/2" MDF with GG on either side + Zero Int'l seals etc. (facing away from shared wall)
- Tanks are all on heavy-duty vibration pads and aren't touching any walls.

Assuming our commercial neighbors get noisy (slamming large doors & music) while we have customers, how much of a problem might that one shared wall (4" stud, 1/2" drywall, with minimal insulation) be if our studs are 6" away. We currently have 18" of space from drywall to drywall between each room but only 10" from our drywall to the first layer of shared wall drywall. It's also important to note that there is a big metal door attached on the other side of the wall that they seem to use quite often (we may offer to buy them a heavy-duty closer to reduce slamming/vibrations).

Am I just being over-cautious and thinking the sky is falling because of triple leaf horror stories? It just hit me today during construction that it's technical a triple leaf setup and wanted to verify with someone who might be able to guide us in the right direction.

Cheers!


----------



## BSHuff

I will admit I only made it through about 500 posts on this thread.. 

What is the thought on sound control on floors when adding attic theaters? I am in the research stage.... 

Basic idea, I have an unfinished attic that was designed as 'expandable' space when the house was built. So existing stair case, and studs and a clear span joists. The decking is advantec OSB. Under the floor is a finished bath and bedroom space (used as my daily work office) with crown molding. I really do not want to disturb much into the finished space below if I can avoid it as it is my occupation office space, unless it is something like adding a layer of drywall to existing. I see people sound proofing the ceiling when there is stuff above, what do you do when there is stuff below? 

I have down the standard recommendations for the walls and the 'in room' ceilings. What to do to the floor in a renovation type environment? Layers of floor OSB? Green Glue? Tile backer board with overlay OSB? Float OSB on top of some resilient foam? I don't really have a height restriction, so adding an inch or so will not be a major impact unless it is extreme. The finished floor will be padded carpet.


----------



## lovingdvd

arcamm said:


> Well that was sure fun! I got the two Green Glued layers of 5/8" dry wall up.


I can't tell if you were being sarcastic or not about it being fun...?  I'm about to embark on the same endeavor. What size are your joists (i.e. 16" on center)? What size lengths of drywall did you use to keep things manageable and how easy was it to do on your own? I am trying to picture whether its fairly easy or not to lift a piece overhead, hold it in place, and screw it by yourself. Thanks.


----------



## lovingdvd

highhrider said:


> Today the construction team is installing Quietrock 545THX to my walls with Greenglue sealant and Quietrock putty for the boxes. Insulation being used is Roxul safe and sound batts. My room size is 19x16.
> Has anyone used these product?


What are you doing for the ceiling isolation?



jrref said:


> Yes, it's excellent!


----------



## Waterboy77

lovingdvd said:


> I can't tell if you were being sarcastic or not about it being fun...?  I'm about to embark on the same endeavor. What size are your joists (i.e. 16" on center)? What size lengths of drywall did you use to keep things manageable and how easy was it to do on your own? I am trying to picture whether its fairly easy or not to lift a piece overhead, hold it in place, and screw it by yourself. Thanks.



I'm going to say extreme sarcasm. 
My wife and I just put up first layer in our basement on the weekend and I have to say of all the reno tasks that I have done it is the absolute worst one yet.
It is a 2 person job with out a doubt..... if you can do it by yourself your a better man that I am. 
We had to measure every 4' piece as the people that put it the joists obviously did not own a tape measure as they ranged from 14.5" - 18"


OVERHEAD WORK SUCKS


----------



## jjackkrash

I read through this thread and some linked build threads for about 8 hours last night. I am looking to convert an open room into a sealed and soundproofed dedicated room in the basement of an existing 3-story house. The floor is concrete slab on grade. One of my questions is whether I need some sort of raised floor to de-couple the floor from the studs along the wall. I am likely going to tear out all the sheetrock on the walls and ceiling and use the clips/rails I read about last night to decouple the walls and ceiling, but was not sure about what to do with the concert floor, if anything. Any thoughts?


----------



## jjackkrash

Waterboy77 said:


> I'm going to say extreme sarcasm.
> My wife and I just put up first layer in our basement on the weekend and I have to say of all the reno tasks that I have done it is the absolute worst one yet.
> It is a 2 person job with out a doubt..... if you can do it by yourself your a better man that I am.
> We had to measure every 4' piece as the people that put it the joists obviously did not own a tape measure as they ranged from 14.5" - 18"
> 
> 
> OVERHEAD WORK SUCKS



I DIY the vast majority of my projects, but concrete-finish work and overheard work are two things I don't mind paying someone else to help with.


----------



## granroth

warpedcore said:


> Currently opening a large floatation therapy center where we planned on going all out for soundproofing in order to facilitate the most quiet space possible. Float tanks are essentially large basins filled with skin temperature neutral Epsom salt water (~1000lbs) that you float in; absence of sound, light and touch to help people relax, meditate, recover etc.
> 
> Obviously this requires a strong level of either soundproofing or ability to keep the facility extremely quiet.
> 
> My concern is that we've spent a fair bit of money, time and effort to put together ~60+ STC rated rooms and just as we've been putting up framing and drywall - I've come to the realization that our double stud setup might be compromised by the firewall/shared unit wall in between us and our neighbor - causing some form of _triple leaf effect_.
> 
> [snip]


What you describe will encounter some form of the triple leaf effect, but since I've seen little info on gaps as wide as 6", I don't know how much of an effect is in play.

More to the point, if you have very strong requirements and have already spent a fair bit of money, then this forum is likely not the best place for the advice that you need. This forum is excellent for general advice and for DIY users with flexible requirements. If you need to hit a specific target and if you've invested the money, then you really need a acoustician that can devote some time to your very specialized needs.


----------



## granroth

jjackkrash said:


> I read through this thread and some linked build threads for about 8 hours last night. I am looking to convert an open room into a sealed and soundproofed dedicated room in the basement of an existing 3-story house. The floor is concrete slab on grade. One of my questions is whether I need some sort of raised floor to de-couple the floor from the studs along the wall. I am likely going to tear out all the sheetrock on the walls and ceiling and use the clips/rails I read about last night to decouple the walls and ceiling, but was not sure about what to do with the concert floor, if anything. Any thoughts?


It depends on what your requirements are. Concrete slabs will absolutely transmit some sound out -- the exact amounts depending largely on frequency. If you're in a basement then it matters far less than if you're on the same floor as the area that needs to be isolated. That is, if you're in an apartment/condo or the like and share a slab with neighbors, then the sound that'll travel along the slab likely matters quite a bit.

You absolutely can float your floor (isolating mat or springs + subfloor + regular flooring) and it's commonly done in high end theaters. It's not as commonly done in DIY theaters since it's really one of those things that gets into diminishing returns. If you've already created kick-ass walls and ceilings and doors and the like, then you could benefit from the floated floor. If you have any "weak spot" in the above, then the floating floor might not even be noticeable.


----------



## jjackkrash

granroth said:


> It depends on what your requirements are. Concrete slabs will absolutely transmit some sound out -- the exact amounts depending largely on frequency. If you're in a basement then it matters far less than if you're on the same floor as the area that needs to be isolated. That is, if you're in an apartment/condo or the like and share a slab with neighbors, then the sound that'll travel along the slab likely matters quite a bit.
> 
> You absolutely can float your floor (isolating mat or springs + subfloor + regular flooring) and it's commonly done in high end theaters. It's not as commonly done in DIY theaters since it's really one of those things that gets into diminishing returns. If you've already created kick-ass walls and ceilings and doors and the like, then you could benefit from the floated floor. If you have any "weak spot" in the above, then the floating floor might not even be noticeable.


Thanks. This helps a bunch. My goal is really to keep the bass out of the third floor where the bedrooms are so I can enjoy movies at night at a reasonably high volume. Right now I can't run the subs much all at night without consequences--if you know what I mean--and I figured the floor would fit into that diminishing-return realm. I'll still look into it a bit more, however. 

Thanks again.


----------



## nandkisham

*Communicating Doors - Jambs*

I am at the framing stage and would like to get visuals or some details around building communicating doors.

HT opens from the game room( not the ideal hallway kind of entrance) , I initially resisted the idea of 2 doors, but seriously considering it now..


----------



## kmhvball

nandkisham said:


> I am at the framing stage and would like to get visuals or some details around building communicating doors.
> 
> HT opens from the game room( not the ideal hallway kind of entrance) , I initially resisted the idea of 2 doors, but seriously considering it now..


A few very basic things:
1) typically from a framing perspective, you simply need two, parallel 2x4' walls. Mine were only separated by 1/2" - 1". 
- caveat - if you are planning a step/riser height entrance, then the framing for the door needs to be 'taller' to accomodate for the fact that the final 'floor' is higher (i.e., don't frame top of door at say 6'10" from concrete floor, if the bottom of door will be at 7" from concrete floor... door frame would then need to be 6'10" + 7").

2) typically one door opens out and one opens in... which might be a bit funny with a small step into the theater to have to open the door towards you (certainly, you can reach from the floor and open it, so, not a deal breaker)

I used an exterior door on the 'outer' side, so, I still have some 'seals' all the way around that door. I then used an interior door, and purchased the sound-proofing door seals for the theater side.

I briefly kicked around trying to figure out how to have both open the same direction, but didn't figure it out at the time. Now that I think a bit more about it, you could conceptually have two open the same direction... if both different widths & heights, but obviously sequence of opening would be limited. So, if you wanted the doors to open 'into' the theater.. your door on the theater side could be a larger door, say 36" wide x 8' tall. The door on the 'outside the theater side' would have to be smaller, say a traditional 32" x 6/8" door. Obviously, the large door has to be open before the small door can. The smaller door would only be able to open 'part way' (as the inner door frame would get in the way), or you would have to get special hinges to open much wider. I do know there are wide hinges available, just don't know how wide. Doesn't seem worth it to me, but thought I would throw it out there.

Post 216 on Page 8 of this thread, discusses making a 'super' single door. Not sure how effective it is vs communicating doors, but I think he is fairly happy with it.

http://www.avsforum.com/forum/19-de...361-salt-mine-dedicated-family-theater-8.html

If you look at later posts, I think it looks quite nice when it was completed.

Given the lay out of my theater, and how close the door is to my back bar (i.e., bar chairs have to be pushed fully forward against bar, for door to open) - in retrospect, I kind of which I had looked more at a 'super single door'. Although, having the double doors does consistently get comments from visitors as a bit of a 'wow' factor.


----------



## pitviper33

kmhvball said:


> I briefly kicked around trying to figure out how to have both open the same direction, but didn't figure it out at the time. Now that I think a bit more about it, you could conceptually have two open the same direction... if both different widths & heights, but obviously sequence of opening would be limited. So, if you wanted the doors to open 'into' the theater.. your door on the theater side could be a larger door, say 36" wide x 8' tall. The door on the 'outside the theater side' would have to be smaller, say a traditional 32" x 6/8" door. Obviously, the large door has to be open before the small door can. The smaller door would only be able to open 'part way' (as the inner door frame would get in the way), or you would have to get special hinges to open much wider. I do know there are wide hinges available, just don't know how wide. Doesn't seem worth it to me, but thought I would throw it out there.


You'd need to rig the knobs together somehow. Otherwise how will you get in? You can't open the small door unless the big door is already open.


----------



## jrref

For those of you who have used Green Glue or Quiet Rock with insulation in a room or common wall, when you are playing music pretty loud, around 80 db, can you hear anything on the other side of the wall?

I have sound proofed the common wall with my neighbor with Quiet Rock and Roxul safe and sound insulation, sealed all the outlets and used sealant around the sheetrock, etc... It's a staggered 2x4 wall. Both my and my neighbors side have 3 inches of Roxul safe and sound with about 3 inches of air space between. Although the wall is staggered, the plates on the top and bottom of the wall are common. When my neighbor plays his music at around 80 db, if it's dead silent on my side, I can just barley hear some of the low to mid bass if you listen for it. He doesn't have a sub. The problem on his side is that he doesn't have things like curtains, etc, to absorb sound so everything echo's on his side. I've done everything I can within reason to soundproof the wall and i'm trying to find out if this is normal and the job I did was good or should I hear zero on my side. When I tested the wall with a sound meter, i'm getting about 50-55 db reduction in sound with the soundproofing I did. BTW, I hear zero of the higher frequencies, talking, etc..

From what i'm reading we are not really "sound proofing" meaning no sound transmission but doing sound reduction with all these soundproofing methods.


----------



## granroth

jrref said:


> For those of you who have used Green Glue or Quiet Rock with insulation in a room or common wall, when you are playing music pretty loud, around 80 db, can you hear anything on the other side of the wall?


Yep

It's convenient to use a single number to describe how much sound attenuation we expect from a wall, but that's not really how noise propagation works. If we create a wall with a rating of STC 60, then we colloquially say that if we measure 80 dBA on one side, then we'll hear 20 dBA on the other. In reality, that's only going to be if the sound in question matches the STC curves -- e.g., is heavily weighted in the frequencies that STC is measuring. If there are significant frequencies outside of those frequencies, then those may be clearly audible.

Then there's the question if your partition is really getting the performance that you expect it to. All of the STC values described for specific wall assemblies are "in a perfect setting" lab result. Your real world results will always be at least slightly worse than those. And really, there are so many varied ways of sound to flank around your wall that for certain frequencies, your wall might not perform even close to what you expected.




jrref said:


> From what i'm reading we are not really "sound proofing" meaning no sound transmission but doing sound reduction with all these soundproofing methods.


Bingo! It's not realistically possible to truly "sound proof" any structure, short of putting said structure in space with a vacuum surrounding it. Even places like the Galaxy Studios that go to insane levels of soundproofing (6' thick concrete walls! Floating floors on massive springs!) still "only " achieve around a 100 dB attenuation. That means that if you're generating 120 dB in a room (absolutely possible with a live orchestra), then you'll hear somewhere around 20 dB outside of the room. Very quiet but definitely audible.

All we're trying to do when "sound proofing" is attenuating the frequencies that we'll be encountering to a level that's acceptable to us.


----------



## jrref

granroth said:


> Yep
> 
> It's convenient to use a single number to describe how much sound attenuation we expect from a wall, but that's not really how noise propagation works. If we create a wall with a rating of STC 60, then we colloquially say that if we measure 80 dBA on one side, then we'll hear 20 dBA on the other. In reality, that's only going to be if the sound in question matches the STC curves -- e.g., is heavily weighted in the frequencies that STC is measuring. If there are significant frequencies outside of those frequencies, then those may be clearly audible.
> 
> Then there's the question if your partition is really getting the performance that you expect it to. All of the STC values described for specific wall assemblies are "in a perfect setting" lab result. Your real world results will always be at least slightly worse than those. And really, there are so many varied ways of sound to flank around your wall that for certain frequencies, your wall might not perform even close to what you expected.
> 
> 
> 
> 
> Bingo! It's not realistically possible to truly "sound proof" any structure, short of putting said structure in space with a vacuum surrounding it. Even places like the Galaxy Studios that go to insane levels of soundproofing (6' thick concrete walls! Floating floors on massive springs!) still "only " achieve around a 100 dB attenuation. That means that if you're generating 120 dB in a room (absolutely possible with a live orchestra), then you'll hear somewhere around 20 dB outside of the room. Very quiet but definitely audible.
> 
> All we're trying to do when "sound proofing" is attenuating the frequencies that we'll be encountering to a level that's acceptable to us.


Thanks for the feedback. When I did this project I researched everything and meticulously installed the Roxul, sealed all the electrical and cable outlets with quiet putty, made sure to leave the air gap, went crazy installing the quiet rock and sealing everything. I'm not really sure what else I could have done. I can tell you that the quiet rock is very dense and when you knock on it, it's like cement! No matter how loud my neighbor plays his music, the wall doesn't feel like it's vibrating to the touch like it was before the soundproofing.

One interesting behavior I noticed is that there is more sound attenuation from my side to my neighbors than vice versa. I think it's because the sound hits his 5/8 inch sheetrock and some of that energy is transmitted to the 2x4 framing which flanks via the floor and ceiling. Sound coming from my side is attenuated by the quiet rock so much less energy is transmitted to the 2x4 framing. I think if I installed a layer of quiet rock over his 5/8 inch sheetrock on his side it might increase the sound attenuation from his side to mine quite a bit by reducing this energy transfer.


----------



## lovingdvd

Any idea how Quietrock would compare to three layers (OSB + Green Glue + 5/8" DW + Green Glu + 5/8" DW?


----------



## jrref

lovingdvd said:


> Any idea how Quietrock would compare to three layers (OSB + Green Glue + 5/8" DW + Green Glu + 5/8" DW?


No clue.


----------



## granroth

lovingdvd said:


> Any idea how Quietrock would compare to three layers (OSB + Green Glue + 5/8" DW + Green Glu + 5/8" DW?


The consensus is that Quietrock and DW+GG are comparable in performance, but with the DW+GG solution costing half as much and requiring almost 50% more thickness.

The company behind Green Glue did a comparison of 5/8" Quietrock vs 1/2" DW + GG + 1/2" DW and came to the conclusion that the GG solution won all categories hands down. Do a search for their "Green Glue vs factory damped panels" PDF.

In the real world, it appears that the difference between the two isn't noticeable.

So...

Use Quietrock if:
* You need every fraction of an inch space
* You are pressed for time and want to deal with only one panel
* You are willing the spend the extra money for either of the upper two reasons

Use DW + GG if:
* You are willing to give up maybe 1" or so in total room width and length
* You have the time to work with double the number of panels and applying the Green Glue
* You don't want to spend the extra money


----------



## AXLCMT

If I built a wall at the bottom of the stairs into the theater room (basement theater) and I need to insulate inside the wall with some kind of "r value"
pink insulation, what "r value" should I choose for insulation inside the wall? R13, R38? Does it matter the R value?


----------



## AXLCMT

If I built a wall at the bottom of the stairs into the theater room (basement theater) and I need to insulate inside the wall with some kind of "r value"
pink insulation, what "r value" should I choose for insulation inside the wall? R13, R38? Does it matter the R value?


----------



## granroth

AXLCMT said:


> If I built a wall at the bottom of the stairs into the theater room (basement theater) and I need to insulate inside the wall with some kind of "r value"
> pink insulation, what "r value" should I choose for insulation inside the wall? R13, R38? Does it matter the R value?


Don't think of it in terms of r-value but rather in "filling up your wall". That is, just build your wall and then get the proper thickness of fiberglass (or rockwool) batts to loosely fill it. R-value only measures resistance to heat transfer and that has no meaning from a soundproofing perspective.


----------



## AXLCMT

granroth said:


> Don't think of it in terms of r-value but rather in "filling up your wall". That is, just build your wall and then get the proper thickness of fiberglass (or rockwool) batts to loosely fill it. R-value only measures resistance to heat transfer and that has no meaning from a soundproofing perspective.


Thanks granroth! 

The only problem is that I have to leave some space for a Movie Poster LED 50" Insignia screen to let it's "heat" out via a vent I
plan on installing on the inside of the wall (the theater side will have the vent). See my link to my dedicated build thread in my signature to see what I mean.


----------



## Waterboy77

My results from one layer.... copied from my build thread

Thoughts?



Waterboy77 said:


> *Results of Base Line Tests*
> With everythingoff and no one home:
> MLP = 31db
> Just outsidetheater pocket doors = 32db
> Mid upstairsliving room = 30db
> 
> So pretty quiet ingeneral
> 
> At -10 on the AVRwith white noise track
> MLP = 81db
> Just outsidetheater pocket doors = 58db (-23)
> Mid upstairsliving room = 46db (-35)
> 
> At 0 on the AVRwith white noise track
> MLP = 88db
> Just outsidetheater pocket doors = 71db (-17)
> Mid upstairsliving room = 58db (-30)


*Results of One Layer Tests*
With everythingoff and no one home:
MLP = 31db
Just outsidetheater pocket doors = 35db
Mid upstairsliving room = 30db

At -10 on the AVRwith white noise track
MLP = 83db
Just outsidetheater pocket doors = 56db (-27)
Mid upstairsliving room = 43db (-40)

At 0 on the AVRwith white noise track
MLP = 89db
Just outsidetheater pocket doors = 69db (-20)
Mid upstairsliving room = 54db (-35)


So it looks like I have a 5db improvement from the addition of the one layer of GG/DW in the joists for sound escaping upstairs

I also redid the hammer drop but am only seeing a 2db drop from 72 to 70.... that was a little disappointing
Subjectively it was more "thud" like and did not seam to transfer the energy as far (HVAC did not rattle this time)

Next up second layer with more GG


----------



## jrref

Waterboy77 said:


> My results from one layer.... copied from my build thread
> 
> Thoughts?
> 
> 
> 
> *Results of One Layer Tests*
> With everythingoff and no one home:
> MLP = 31db
> Just outsidetheater pocket doors = 35db
> Mid upstairsliving room = 30db
> 
> At -10 on the AVRwith white noise track
> MLP = 83db
> Just outsidetheater pocket doors = 56db (-27)
> Mid upstairsliving room = 43db (-40)
> 
> At 0 on the AVRwith white noise track
> MLP = 89db
> Just outsidetheater pocket doors = 69db (-20)
> Mid upstairsliving room = 54db (-35)
> 
> 
> So it looks like I have a 5db improvement from the addition of the one layer of GG/DW in the joists for sound escaping upstairs
> 
> I also redid the hammer drop but am only seeing a 2db drop from 72 to 70.... that was a little disappointing
> Subjectively it was more "thud" like and did not seam to transfer the energy as far (HVAC did not rattle this time)
> 
> Next up second layer with more GG


Thanks but when you say one layer, what do you mean? Can you give us a little more detail?


----------



## Waterboy77

jrref said:


> Thanks but when you say one layer, what do you mean? Can you give us a little more detail?



Hi jrref, the one layer is comprised of green glue and 5/8" Type x drywall. I applied the GG to the drywall then screwed to the subfloor with 1 1/4" drywall screws
The second layer will be GG and same 5/8" drywall but with 2" screws


----------



## lovingdvd

Waterboy77 said:


> Hi jrref, the one layer is comprised of green glue and 5/8" Type x drywall. I applied the GG to the drywall then screwed to the subfloor with 1 1/4" drywall screws
> The second layer will be GG and same 5/8" drywall but with 2" screws


What is the subfloor material and its thickness?


----------



## Waterboy77

lovingdvd said:


> what is the subfloor material and its thickness?



3/4" osb


----------



## UK Dreamer

Since, AFAIK, a 6 decibel reduction would be a halving of the volume heard, a 5 decibel reduction is worthy.


I'd imagine the next layer won't have quite the same effect, since you're adding only (roughly) 50% of the mass already there, rather than doubling the mass, as your single layer did. You'd have to add 3 layers in total to get another 5 DB's - I think you'll be looking at 2-3 DB's reduction this time around - still worthwhile, as it'll reduce the sound by around 20-25% of it's current level. Making, in total, the perceived volume reduction to be around 35-40% of what it was originally.


And I'm assuming that since you're doing the stuff between the joists, the 'ceiling proper' hasn't been put in place yet, which will yield further improvements.


YMMV


----------



## Waterboy77

UK Dreamer said:


> Since, AFAIK, a 6 decibel reduction would be a halving of the volume heard, a 5 decibel reduction is worthy.
> 
> 
> I'd imagine the next layer won't have quite the same effect, since you're adding only (roughly) 50% of the mass already there, rather than doubling the mass, as your single layer did. You'd have to add 3 layers in total to get another 5 DB's - I think you'll be looking at 2-3 DB's reduction this time around - still worthwhile, as it'll reduce the sound by around 20-25% of it's current level. Making, in total, the perceived volume reduction to be around 35-40% of what it was originally.
> 
> 
> And I'm assuming that since you're doing the stuff between the joists, the 'ceiling proper' hasn't been put in place yet, which will yield further improvements.
> 
> 
> YMMV


Good points...... I hope there wrong and I get more reduction ..... but I doubt it. 
The 2-3 db is a good estimation as it will be roughly adding 50% more mass with the third layer.
The plan is to measure at each interval..... next up the second layer.... then insulation...... then drop ceiling 
yes I know drop ceilings are not ideal and is one of the reasons I wanted to try the 2 layers between joists


----------



## nandkisham

will there be any advantage in treating the living room drywall (exterior to HT) from inside for mass and dampening with additional DW/GG between studs?

Please see attached rough sketch, Living room is 2 storey height.


----------



## jrref

nandkisham said:


> will there be any advantage in treating the living room drywall (exterior to HT) from inside for mass and dampening with additional DW/GG between studs?
> 
> Please see attached rough sketch, Living room is 2 storey height.


No do not do that because you may change the resonance of the wall. Stick to the normal application.


----------



## kmhvball

nandkisham said:


> will there be any advantage in treating the living room drywall (exterior to HT) from inside for mass and dampening with additional DW/GG between studs?
> 
> Please see attached rough sketch, Living room is 2 storey height.


I know Brolic Beast did this in his theater.

I put the GG/DW/GG/DW on my sub-floor, which conceptually would be the same. I think there would be benefit... how much, no idea, but I have to believe it would be helpful.


----------



## UK Dreamer

jrref said:


> No do not do that because you may change the resonance of the wall. Stick to the normal application.





I disagree. Anything you can do to add mass, and damp, will improve sound attenuation. The change in resonant frequency of the wall is a good thing, as any lowering of the resonant frequency (which is what adding mass does) will improve the attenuation of the most commonly heard frequencies, with the exception being the far less common deep bass frequencies.

The reason why you may have limited success is more likely to be sound flanking, unless your extra drywall meets the structure running horizontally across. Say, the floor structure above the home theatre. Without that blocking, sound will travel up the cavity where it will meet the thinner, untreated, part of your living room wall, and you'll still have sound issues.

You could mitigate this by adding your own blocking across the top of your treatment, if none exists. Care would have to be taken that you don't undo any isolation efforts.

Hope that makes sense.


----------



## avnoob84

Great post. Thanks!


----------



## jrref

I live in a towne house with a common wall in the living room. Last year I took down the wall on my side and installed Roxul safe and sound, 3 inches in my neighbor's wall and 3 inches in my wall, sealed all the electrical outlets, left the 1 or 2 inch dead air space in between and then installed 5/8 quiet rock on my side. Sealed everything with Quiet Seal. The wall is staggered 2x4 construction which is good but it has a common top and bottom plate that i'm sure that i'm getting some flanking from.

The end result is that i'm getting about 50 - 55 db reduction in sound when my neighbor plays his music. The problem is that sometimes he plays it at 100 db, deafening, and although the level on my side is pretty low, it's still annoying at night when everything is quiet.

The question is, if I install another 5/8 Quiet Rock on my side, over the existing 5/8 Quiet Rock, I know it's not going to double the sound reduction but does anyone have a guess on the extra attenuation that I might expect. Doing this will increase the mass and the decoupling for sure but I have no clue on how much it would help. An alternative is to put a layer of 5/8 quiet rock on his side directly over his existing 5/8 inch sheetrock.

One thing I did discover is that there is better sound reduction from my side to his probably because the Quiet Rock is limiting the amount of sound energy transferring to the 2x4 structure and thus the structure of the wall as a whole.

Any ideas, suggestions, thoughts?

Thanks,
John


----------



## jrref

I live in a towne house with a common wall in the living room. Last year I took down the wall on my side and installed Roxul safe and sound, 3 inches in my neighbor's wall and 3 inches in my wall, sealed all the electrical outlets, left the 1 or 2 inch dead air space in between and then installed 5/8 quiet rock on my side. Sealed everything with Quiet Seal. The wall is staggered 2x4 construction which is good but it has a common top and bottom plate that i'm sure that i'm getting some flanking from.

The end result is that i'm getting about 50 - 55 db reduction in sound when my neighbor plays his music. The problem is that sometimes he plays it at 100 db, deafening, and although the level on my side is pretty low, it's still annoying at night when everything is quiet.

The question is, if I install another 5/8 Quiet Rock on my side, over the existing 5/8 Quiet Rock, I know it's not going to double the sound reduction but does anyone have a guess on the extra attenuation that I might expect. Doing this will increase the mass and the decoupling for sure but I have no clue on how much it would help. An alternative is to put a layer of 5/8 quiet rock on his side directly over his existing 5/8 inch sheetrock.

One thing I did discover is that there is better sound reduction from my side to his probably because the Quiet Rock is limiting the amount of sound energy transferring to the 2x4 structure and thus the structure of the wall as a whole.

Any ideas, suggestions, thoughts?

Thanks,
John


----------



## BasementBob

jjref:;
The rule of thumb is: doubling the mass of a wall, increases the isolation by 6dB, unless/until flanking dominates.


----------



## Waterboy77

Hello, below is the shorter version of post from my thread.......Hope someone finds this useful

The rest (installation and costs) can be found HERE

Test Results
Clause.... I am not a lab nor do I own high end measuring equipment... just a db meter for this measuring.
How I did the tests is covered in this post.










Hammer Drop 72 / 70 / 67

Calculations
I hope this is correct to do..... I took the bd at 0 (reference) and subtracted the OFF bd (eg. 88-31=57db in MLP) This gives me a base line with normal ambient sound removed
With no treatment I have a reduction from 57db to 28db = 29db
With one layer DW GG a reduction from 58db to 24db = 34db
With two layers DW GG a reduction from 58.2db to 22.5db = 35.7db

Therefore one layer reduced the sound 5 db and two 6.7 db
Hammer drop resulted in a 5 db reduction with two layers

My Conclusion
Subjectively I can hear a subtle difference as a result of adding the two layers, mostly in the hammer drop test and the whole ceiling doesn't "rattle" near as much. 
For sound leaving the basement the second layer (based on data / cost) does not seam to be worth it...... BUT....when doing the measurement in my living room I took out my ear plugs and I noticed that a significant amount of sound was coming from the stair well and some from heating vent. I did have the solid core pocket doors closed at the bottom of the stairs but the one side of the wall is not dry walled yet. 

My theory is that I have run into the situation where the amount of sound flanking from door and HVAC have over come the benefits of the second layer..... hopefully this will be improved when I have the wall drywall complete. I also plan on placing extra insulation around the HVAC areas I can.

So would I do it again.... YES.... for under $500 I have an improvement in lower noise floor and sound escaping
Is it as good as I hoped....NO.... but I really couldn't find any good data on just the DD/GG between the joist to have a sense of where it should be

Others may draw a different conclusion that I have and that's OK, I am open to comments


----------



## jrref

Waterboy77 said:


> Hello, below is the shorter version of post from my thread.......Hope someone finds this useful
> 
> The rest (installation and costs) can be found HERE
> 
> Test Results
> Clause.... I am not a lab nor do I own high end measuring equipment... just a db meter for this measuring.
> How I did the tests is covered in this post.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hammer Drop 72 / 70 / 67
> 
> Calculations
> I hope this is correct to do..... I took the bd at 0 (reference) and subtracted the OFF bd (eg. 88-31=57db in MLP) This gives me a base line with normal ambient sound removed
> With no treatment I have a reduction from 57db to 28db = 29db
> With one layer DW GG a reduction from 58db to 24db = 34db
> With two layers DW GG a reduction from 58.2db to 22.5db = 35.7db
> 
> Therefore one layer reduced the sound 5 db and two 6.7 db
> Hammer drop resulted in a 5 db reduction with two layers
> 
> My Conclusion
> Subjectively I can hear a subtle difference as a result of adding the two layers, mostly in the hammer drop test and the whole ceiling doesn't "rattle" near as much.
> For sound leaving the basement the second layer (based on data / cost) does not seam to be worth it...... BUT....when doing the measurement in my living room I took out my ear plugs and I noticed that a significant amount of sound was coming from the stair well and some from heating vent. I did have the solid core pocket doors closed at the bottom of the stairs but the one side of the wall is not dry walled yet.
> 
> My theory is that I have run into the situation where the amount of sound flanking from door and HVAC have over come the benefits of the second layer..... hopefully this will be improved when I have the wall drywall complete. I also plan on placing extra insulation around the HVAC areas I can.
> 
> So would I do it again.... YES.... for under $500 I have an improvement in lower noise floor and sound escaping
> Is it as good as I hoped....NO.... but I really couldn't find any good data on just the DD/GG between the joist to have a sense of where it should be
> 
> Others may draw a different conclusion that I have and that's OK, I am open to comments


This is interesting. I think we get more sound transmittal via flanking than we realize or want to accept because there isn't much we can do about it. I have a similar problem where after doing everything "text-book" with my common wall, I still get, in my opinion, too much sound when my neighbor plays his music at concert level volumes but in my case I felt it was worth the investment and results even though they were not 100%.


----------



## arcamm

lovingdvd said:


> I can't tell if you were being sarcastic or not about it being fun...?  I'm about to embark on the same endeavor. What size are your joists (i.e. 16" on center)? What size lengths of drywall did you use to keep things manageable and how easy was it to do on your own? I am trying to picture whether its fairly easy or not to lift a piece overhead, hold it in place, and screw it by yourself. Thanks.



As Waterboy said "extreme sarcasm". We used 5/8" drywall and snapped them in 14" (more or less) x 4' strips. My joists are 9.5" I beams, 16" oc. My room is 14.3'x20' with just under 9' high. One thing that really helped is that I have one of those $200 Tractor Supply scaffolds on wheels. That made a big difference having a platform to work off of. It would have been tougher with ladders. I also sprung for a $100 Rigid (Home Depot) correlated screw gun. It was worth it not having to hold up a board, load a screw and hold the drive. I could hold the board up and drive as many screws as I needed by myself. 



Waterboy77 said:


> I'm going to say extreme sarcasm.
> My wife and I just put up first layer in our basement on the weekend and I have to say of all the reno tasks that I have done it is the absolute worst one yet.
> It is a 2 person job with out a doubt..... if you can do it by yourself your a better man that I am.
> We had to measure every 4' piece as the people that put it the joists obviously did not own a tape measure as they ranged from 14.5" - 18"
> 
> 
> OVERHEAD WORK SUCKS



^^^ THIS!


My wife and I did this too. I was up on the scaffold with the screw gun, my wife applied the GG handed the board up to me, then handed me the screw gun once I had the board in place. Our system worked pretty good, but it still is something I don't want to do for a living. Our carpenters were a bit better than yours. The joists only varied by about a half inch. So we pre-cut three sizes of 4' boards. Before we started, I measured each space at both ends and the middle, so I had a list of what was needed for each space. Wasn't perfect, but it saved a bunch of re-cutting or large gapes.


----------



## arcamm

I had asked about the Roxal fitting into my spacing. My I beams are 16 oc but the space between the webs are 15.5". The Roxal for wooden studs are cut at 15.25", thus leaving a gap. I was advised this was not good. But Roxal makes bats for steel stud construction that are cut 16.25" wide. So they fit snug in the space.


We did the stair wall too.


Now if you think installing the drywall with Green Glue sucks..........


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## lovingdvd

Waterboy77 said:


> I'm going to say extreme sarcasm.
> My wife and I just put up first layer in our basement on the weekend and I have to say of all the reno tasks that I have done it is the absolute worst one yet.
> It is a 2 person job with out a doubt..... if you can do it by yourself your a better man that I am.
> We had to measure every 4' piece as the people that put it the joists obviously did not own a tape measure as they ranged from 14.5" - 18"
> 
> 
> OVERHEAD WORK SUCKS


I completely agree. We did two layers of 5/8" with GG on the ceiling and it was a grueling process. Doing the demolition while more labor intensive was easier work, if that makes sense. Anyway I'm still fairly early in the build and I think I can saw with some good confidence that doing the subfloor DW with two layers will turn out to be the most grueling part of the whole build out.


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## Amags

My future HT space is in the basement, but has a wood framed floor over full height crawl space as the house is set on a steep hillside. I've read a lot of the stage filled with sand vs. insulation dialogue here, but most of this conversation is geared toward concrete floors. What is the protocol for stages set on framed floors? My stage will be fairly narrow front to back as my room is less than 16' deep. Basically just deep enough for a sub and L and R fronts. Since the stage will not be a walking surface, but merely a platform for sub/speakers, I'm wondering if I could use RSIC clips and hat channel mounted to the floor deck (upside down) and then mount the stage frame to the hat channel to effectively decouple the stage from the floor. Does this sound reasonable? If not, what am I missing here?


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## granroth

Amags said:


> My future HT space is in the basement, but has a wood framed floor over full height crawl space as the house is set on a steep hillside. I've read a lot of the stage filled with sand vs. insulation dialogue here, but most of this conversation is geared toward concrete floors. What is the protocol for stages set on framed floors? My stage will be fairly narrow front to back as my room is less than 16' deep. Basically just deep enough for a sub and L and R fronts. Since the stage will not be a walking surface, but merely a platform for sub/speakers, I'm wondering if I could use RSIC clips and hat channel mounted to the floor deck (upside down) and then mount the stage frame to the hat channel to effectively decouple the stage from the floor. Does this sound reasonable? If not, what am I missing here?


Think of clips and channels like a spring that is extended. When sound waves strike the panel mounted to the channel (drywall, plywood, osb, etc) then the "spring" is pushed back a bit, absorbing quite a bit of the energy of the wave during the compression phase.

Now let's think of the clips and channels being attached upside down with the weight of the panels (stage in this case) pressing down. The "spring" is going to be fully compressed by default due to the weight of the stage. When the sound waves strike them then there's no compressing movement that can be made to dissipate the energy since it's already compressed. Ergo, it would do little to no decoupling.

As far as what the standard protocol is in your case... well, it's essentially like you are on the second floor. That's the scenario that most people building home theaters are in when they are dealing with a wood framed floor. In those cases, it was always very rare to fill the stage with sand. Rather, the stage was and is commonly just filled with insulation (so as to not create a resonating box).

What do decouple the stage with? Now we're into hearsay territory. Some people put rubber "pucks" or mats under the edge of the stage framing. Some just put the subs themselves on rubber mats (like the "Subdude" riser). Many of those people swear by those methods. Alas, concrete numbers showing the difference seem hard to come by. The manufactures of the isolating products put out numbers showing wonderful results, but I can't trust them. I'm not aware of anybody who has tested these products in the real world. It's at least possible that they work.

A lot of people do nothing special since they realize that sufficient bass/LFE will scoff at all of your attempts to suppress it. LFE respects limp mass and lots of it but not much of anything else. Decoupling and isolation are far more effective at the audible frequencies.


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## lovingdvd

Is anyone here using a joist muffler / backer box for the area where their diffuser meets the ceiling for their supplies and returns, in order to preserve the integrity of the ceiling isolation shell? Any pics? I have seen the design recommended by Ted and The Soundproofing Company, and am curious if there are other or similar approaches to consider. Thanks!


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## DarkNovaNick

I'm planning a house build and am researching ways to soundproof a room. I've read about double wall construction and how much that cuts down on noise transmission through the wall. I'm wondering, for part of my wall there is an adjacent room (laundry room) which is between the sound generating room and the rest of the house. Does having an adjacent room work similarly to a double stud wall, or is it better, or not as good for some reason? I'm wondering if I wouldn't have to do anything special for that part of the wall because there are already 2 2x4 walls that any sound would need to travel through in order to get out. Thanks.


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## kmhvball

DarkNovaNick said:


> I'm planning a house build and am researching ways to soundproof a room. I've read about double wall construction and how much that cuts down on noise transmission through the wall. I'm wondering, for part of my wall there is an adjacent room (laundry room) which is between the sound generating room and the rest of the house. Does having an adjacent room work similarly to a double stud wall, or is it better, or not as good for some reason? I'm wondering if I wouldn't have to do anything special for that part of the wall because there are already 2 2x4 walls that any sound would need to travel through in order to get out. Thanks.


So... if I have this right
- Sound generating room
- Laundry room (full size of sound room)
- rest of house you want to keep quite

If that is the case, then from a 'wall' perspective, the Laundry room does deliver on the benefit of a 'double wall'... assuming you don't care about the sound made in the Laundry room!

The big watch out though, would be the 'weak point' would be the door for the SOund generating room... doors are many times the weakest part of sound proofing.

Additionally, you would have some concern about the sound 'flanking' up through the ceiling, depending on what was above it. 

I might be tempted to do a staggered stud wall on the Laundry Room/ rest of house wall - just to aid a little more. In my theater room, I have an "AV CLoset" which is a 4' wide x 11' long room, and on the theater to AV Closet side is a single 2x4 wall... on the other side of the "AV Closet" and the room on the other side, I have a 2x6 wall with staggered studs. I didn't feel I needed a complete double wall over on that side.


----------



## DarkNovaNick

kmhvball said:


> So... if I have this right
> - Sound generating room
> - Laundry room (full size of sound room)
> - rest of house you want to keep quite
> 
> If that is the case, then from a 'wall' perspective, the Laundry room does deliver on the benefit of a 'double wall'... assuming you don't care about the sound made in the Laundry room!
> 
> The big watch out though, would be the 'weak point' would be the door for the SOund generating room... doors are many times the weakest part of sound proofing.
> 
> Additionally, you would have some concern about the sound 'flanking' up through the ceiling, depending on what was above it.
> 
> I might be tempted to do a staggered stud wall on the Laundry Room/ rest of house wall - just to aid a little more. In my theater room, I have an "AV CLoset" which is a 4' wide x 11' long room, and on the theater to AV Closet side is a single 2x4 wall... on the other side of the "AV Closet" and the room on the other side, I have a 2x6 wall with staggered studs. I didn't feel I needed a complete double wall over on that side.


Thanks for responding. Yes, to be clear I don't care about the sound made in the laundry room; I was assuming that if I'm watching a movie, the laundry won't be running at the same time! So it doesn't really matter the type of room, I'm just trying to find out if having that room there blocks sound about as well as a double wall would. The room does not extend the entire length of the sound generating room's wall so on the part of wall that does not have a room behind it, I was thinking about doing staggered studs there, but I'm trying to figure out if I can avoid doing that for the length of the wall that has the adjacent room. If so, then there isn't much shared wall that needs to be done in a special way.

I also wonder about how much sound a closet blocks. On another part of the wall I have a 2' deep closet planned. I wonder how much sound that closet blocks on that part of the wall.


----------



## HT Geek

*Excellent Paper Thoroughly Explaining De-Coupling for the Layman*

Sometimes, the best advice is found in unexpected places. I stumbled upon an outstanding paper written by Steve Thorburn: _Acoustical Considerations for Mixed-Use Wood-Frame Buildings__. _The intended audience are multi-family construction designers and architects, but his sound transmission and de-coupling advice is spot on and relevant to the HT world. It is an easy and thorough read that demystifies the core concepts behind decoupling.

Written in 2014, it's the best single document I've read so far (and I have read plenty, btw) that concisely explains the concepts of noise reduction, acoustic damping, TL, STC, drywall vs. plywood/OSB, insulation, flanking, sound proofing floors, ceilings, and walls in layman's terms. At 11 pages it is a beginner's overview, but it's all there! Thorman covers all the basics at a high level that is digestible by the average person. *

This document should be a sticky!* 

If this were the first explanation I'd ever read on sound proofing a room, it would have saved me hours scouring AVS, Googl'ing, and downloading multiple articles and specifications trying to understand what the heck everyone was talking about.

On the downside, Thorburn should have included a bibliography and he peppered a couple of opinions within the document that IMHO he should have left out. But this is too good of a resource. It is an excellent starting point for someone who's trying to nail down the basics of sound isolation.

I am well aware this information is 'out there' in various forms. For instance, Ted and John at SPC have outstanding documents on this subject on their website. The appeal of Thorburn's paper is all the information is wrapped into a *single *document.


----------



## granroth

HT Geek said:


> Sometimes, the best advice is found in unexpected places. I stumbled upon an outstanding paper written by Steve Thorburn: _Acoustical Considerations for Mixed-Use Wood-Frame Buildings__. _The intended audience are multi-family construction designers and architects, but his sound transmission and de-coupling advice is spot on and relevant to the HT world. It is an easy and through read that demystifies the core concepts behind decoupling.
> 
> Written in 2014, it's the best single document I've read so far (and I have read plenty, btw) that concisely explains the concepts of noise reduction, acoustic damping, TL, STC, drywall vs. plywood/OSB, insulation, flanking, sound proofing floors, ceilings, and walls in layman's terms. At 11 pages it is a beginner's overview, but it's all there! Thorman covers all the basics at a high level that is digestible by the average person. *
> 
> This document should be a sticky!*


Done. It's now listed in the "Essential Reading" section at the beginning of this thread.


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## amit916

There might be a red flag in my new HT build that I wanted to start in a few months...

HT is in the basement, but unfortunately, there's a bedroom (maybe a closet if I really push for it) on the opposite side of the front sound stage. Playing loud movies at night is probably unacceptable if my soundproofing efforts aren't effective.

How much sound proofing (from the lower frequencies, the subwoofers) can I realistically expect if all things go well? I'm talking about decoupling/mass/dampening. This is a new house so taking care of flanking paths is very doable at this moment along with addressing the bedroom itself and making those walls soundproof as well.


----------



## HT Geek

amit916 said:


> HT is in the basement, but unfortunately, there's a bedroom (maybe a closet if I really push for it) on the opposite side of the front sound stage. Playing loud movies at night is probably unacceptable if my soundproofing efforts aren't effective.
> 
> How much sound proofing (from the lower frequencies, the subwoofers) can I realistically expect if all things go well? I'm talking about decoupling/mass/dampening.


Amit,

I'm sure you'll get a number of opinions/responses here, but I'll give you mine anyway. 

I have a similar issue with my ongoing build. Though my HT is 2nd floor, with 3 exterior walls, the 1 interior wall is shared with a bedroom. Here are some of the concepts I'm employing to deal with this issue within a reasonable monetary and time budget:



Double stud wall w/air gap between it and structural wall
Floor rubber underlayment w/2 layers of OSB on top (separated by roofing felt)
6" air gap in front of OSB/drywall wall covering (toward the inside of the room)
4" thick fabric covered wall covering with Linacoustic & Roxul absorption

There are of course many other options. For instance, I could add a 3rd layer of drywall or I could have placed the 6" air gap behind the OSB/drywall, however I am planning to use some of that area as storage which means in my case the air gap must be forward or toward the inside of the room. 

Incidentally, I suspect if in your case the shared wall w/a bedroom is the front wall - where the L/C/R speakers are located - that you'll have an easier time with sound isolation versus if it were the rear wall that your main speakers are facing. That said, you may wish to consider which speakers you will use for your mains (if not already chosen), based at least in part on their radiation pattern. Point being that every speaker radiates sound differently and some radiate more to the rear than others. Though you mentioned LFE and that will certainly be a challenge to contain no matter what.

Best of luck and let us know how it goes. At least start your own build thread when you're ready!

Cheers.

David


----------



## granroth

amit916 said:


> There might be a red flag in my new HT build that I wanted to start in a few months...
> 
> HT is in the basement, but unfortunately, there's a bedroom (maybe a closet if I really push for it) on the opposite side of the front sound stage. Playing loud movies at night is probably unacceptable if my soundproofing efforts aren't effective.
> 
> How much sound proofing (from the lower frequencies, the subwoofers) can I realistically expect if all things go well? I'm talking about decoupling/mass/dampening. This is a new house so taking care of flanking paths is very doable at this moment along with addressing the bedroom itself and making those walls soundproof as well.


It's possible to do a pretty decent sound proofing job for non LFE (non subwoofers) in your case, since there isn't an opening that needs to be sealed between your theater and the bedroom/closet. A typical setup with double walls (or clips and channels) with enough mass and damping and you'd be able to play movies at reasonable levels even if somebody is in the next room. They will be able to hear it, but it'll be quiet and indistinct. A closet would help even more, so if you can swing that, that'd be ideal.

You will almost surely not get the LFE containment that you'd want in order to play loud while somebody is in the next room. Those low frequencies are _extremely_ difficult to contain and the cards are stacked against you by the fact that you share a floor and share a wall. They will pass through your wall only slightly reduced and will scoot along the shared basement slab like it's a custom pathway.

Putting a concrete and sand wall that's a couple feet thick between the rooms will make a notable difference. Some of that will definitely be negated by the slab flanking. Having a floating floor in one or both of the rooms will help, but I'm not entirely certain how much when it comes to LFE.

If you're willing to throw money at it then it _is_ possible to have effective LFE attenuation, but you'd need to hire a pro to design the entire system.

If you're not willing to fork out the money (and it would be a lot) then you might find yourself just turning down the subwoofers when watching a movie while somebody is sleeping next door.


----------



## artur9

jcr159 said:


> But to my question... I haven't seen anything yet that talks about techniques to deal with blocking the sound from sewer pipes. Basically, in my basement, anytime someone showers or flushes, you hear a huge amount of noise from the water rushing down the main sewer pipe.


I've got the same problem but the pipe is right above my wife's seat in the media room. There's almost no clearance between it and the drop ceiling so I think the quiet wrap previously mentioned will help (fingers-crossed).

I also have another problem that any suggestions would be welcome. I soundproofed about half the floor/ceiling with Roxul R23. That part works awesome as that half is below my office . But because I've reduced the sound from other parts of the flooring all the sound now seems to come from the stairwell that goes into the basement. In fact, if I put my ear on the wall of the stairwell in the upper floor's hall I can hear the TV pretty clearly.

Any ideas on what I can do to reduce that sound transmission? From reading this thread it doesn't seem as if there are many options other than adding a solid core door to the landing in the stairs. I hope I'm wrong about that.


----------



## New Bob

*Question about EPDM rubber in the walls? For damping...?*

I was thinking about using EPDM rubber roofing between a layer of 3/4" plywood and then a layer of 5/8" drywall on the ceiling and walls. It will be a room within a room construction. The rubber woud be in place of the Green Glue? Read somewhere on this site that a couple people had very good results that way.I 'm pretty sure they said that they doubled up on .045 EPDM rubber between the layers. Would like to hear some opinions on this!! Thank You in Advance


----------



## amit916

granroth said:


> It's possible to do a pretty decent sound proofing job for non LFE (non subwoofers) in your case, since there isn't an opening that needs to be sealed between your theater and the bedroom/closet. A typical setup with double walls (or clips and channels) with enough mass and damping and you'd be able to play movies at reasonable levels even if somebody is in the next room. They will be able to hear it, but it'll be quiet and indistinct. A closet would help even more, so if you can swing that, that'd be ideal.
> 
> You will almost surely not get the LFE containment that you'd want in order to play loud while somebody is in the next room. Those low frequencies are _extremely_ difficult to contain and the cards are stacked against you by the fact that you share a floor and share a wall. They will pass through your wall only slightly reduced and will scoot along the shared basement slab like it's a custom pathway.
> 
> Putting a concrete and sand wall that's a couple feet thick between the rooms will make a notable difference. Some of that will definitely be negated by the slab flanking. Having a floating floor in one or both of the rooms will help, but I'm not entirely certain how much when it comes to LFE.
> 
> If you're willing to throw money at it then it _is_ possible to have effective LFE attenuation, but you'd need to hire a pro to design the entire system.
> 
> If you're not willing to fork out the money (and it would be a lot) then you might find yourself just turning down the subwoofers when watching a movie while somebody is sleeping next door.


Haha, that paints an overly negative situation, yikes. I hope it's not too too bad. I talked to Ted (because I'll need to buy the supplies real soon) and he mentioned I should be fine and best case scenario I should (and will) use a double wall setup along with no special treatment on the floor. You mentioned flanking from the concrete slab, is that a really big issue and could it be addressed? I've read on a few threads that the floor should be the last thing to treat as you have the least amount to gain (in terms of soundproofing) from it.

Is there nothing I can do, in terms of having bass absorbers or something along that side (without killing the acoustics) Further treating the bedroom (though not much because I don't want to go around soundproofing every other room.) Or do bass absorbers/traps only attenuate and no necessarily negate the bass?


----------



## BasementBob

New Bob said:


> I was thinking about using EPDM rubber roofing between a layer of 3/4 inch plywood and then a layer of 5/8 inch drywall on the ceiling and walls. It will be a room within a room construction. The rubber woud be in place of the Green Glue? Read somewhere on this site that a couple people had very good results that way.I 'm pretty sure they said that they doubled up on .045 EPDM rubber between the layers. Would like to hear some opinions on this!! Thank You in Advance


 
I wouldn't use .045 (1.2mm) EPDM rubber roofing (between a layer of 3/4" plywood and then a layer of 5/8" drywall).
While it may have some viscoelastic and vibration dampening properties, I'm unsure about what frequencies it would be advantageous over, and more importantly disadvantageous over.

EDIT: a double/triple layer of it would probably be worse.


----------



## granroth

amit916 said:


> Haha, that paints an overly negative situation, yikes. I hope it's not too too bad. I talked to Ted (because I'll need to buy the supplies real soon) and he mentioned I should be fine and best case scenario I should (and will) use a double wall setup along with no special treatment on the floor. You mentioned flanking from the concrete slab, is that a really big issue and could it be addressed? I've read on a few threads that the floor should be the last thing to treat as you have the least amount to gain (in terms of soundproofing) from it.


I personally think most people massively overestimate how effective their soundproofing methods will be when it comes to LFE. Low frequency sound is insanely difficult to contain and really the only thing that truly works is lots of mass.

Let's take these two tested wall assemblies as examples.

The first is a wall with an STC 63 rating, made with clips and channels plus 2 x 5/8" drywall with Green Glue on both sides. The PDF is __HERE__. This is what the raw results look like per frequency:










It works very well for a large spectrum of frequencies, losing 62.4 dB at 500Hz and up to 73.7 dB at 5000Hz. You can go pretty loud at those frequencies and it'll reduce them to essentially ambient noise levels. But check out the frequencies under 125Hz. At 40Hz, for instance, that wall will only stop 17.1 dB. That means that if you're blasting a movie at 80 dB with LFE at 90 dB, then fully 73 dB is getting out of your theater. That's still pretty darn loud.

Let's look at another wall. This has an STC rating of 62 and is a staggered stud wall plus 2 x 5/8" drywall with Green Glue on both sides. PDF __HERE__. It's chart looks like so:










Same deal as the other one. Now we're up to 76.3 dB at 5000Hz... but it still only is stopping 19.7 dB at 40Hz. That's only marginally better than the other wall.

I don't have any testing data with Green Glue on hand for a double wall, but it'd likely be only a little bit better than a staggered stud wall. Maybe you'd get in the low 20s at 40Hz? That's just not very much when you're talking about soundproofing.

And that's the wall itself, independent of any flanking!

Concrete slabs are actually very massive and thus resist LFE better than most other materials. In particular, transducers like "ButtKickers" and the like won't work at all on concrete since you just can't make those vibrate with the amount of power that a transducer will generate. But... the rigidity of concrete does transmit LFE very well. That is, the sound waves will travel along the slab to the walls and such in other locations and vibrate those.

ALL THAT SAID, I don't have any hard numbers on any of that and, as such, I could be totally wrong!

Floors are indeed the last thing to treat but that's mostly because they can't be effectively treated without spending a lot of money (floating floors with springs, etc). Anything that you can do in a residential setting will have very little effect.



amit916 said:


> Is there nothing I can do, in terms of having bass absorbers or something along that side (without killing the acoustics) Further treating the bedroom (though not much because I don't want to go around soundproofing every other room.) Or do bass absorbers/traps only attenuate and no necessarily negate the bass?


Bass absorbers and traps and the like are good for reflections in the room but no, they actually stop the bass in any worthwhile capacity if you're talking about it coming in or out of the room.

My personal advice is to just soundproof to the best of your budget and abilities and then just test what kind of result there is for bass. Worst case is that it won't be as much as you'd like and then just don't run the subwoofers hot when somebody is sleeping in the other room.


----------



## ronny31

As is agreed upon earlier in this thread, there's mass and then there's rigidity for stopping low frequency sounds. Concrete works well for anyone that can use that. As does anything else really solid, bricks, scribe-fit logs, cemented stones, etc. Yes, such things are heavy, but you can hang a curtain of logs and have less effect than scribe-fit horizontal logs. At least when it comes to low frequencies. The wavelengths involved are very large, easily as large as an entire wall, floor or ceiling, so the pressure differences will try to move the entire wall, floor or ceiling, producing the same bass note on the other side from the movement of the wall, floor or ceiling. If you could have dual walls, floors and ceiling with a vacuum between them, that would eliminate a lot of bass. But its probably cheaper just to fill the gap with concrete.

PS: A very solid room is more easily filled with insane bass decibel.


----------



## granroth

ronny31 said:


> As is agreed upon earlier in this thread, there's mass and then there's rigidity for stopping low frequency sounds. Concrete works well for anyone that can use that. As does anything else really solid, bricks, scribe-fit logs, cemented stones, etc. Yes, such things are heavy, but you can hang a curtain of logs and have less effect than scribe-fit horizontal logs. At least when it comes to low frequencies. The wavelengths involved are very large, easily as large as an entire wall, floor or ceiling, so the pressure differences will try to move the entire wall, floor or ceiling, producing the same bass note on the other side from the movement of the wall, floor or ceiling. If you could have dual walls, floors and ceiling with a vacuum between them, that would eliminate a lot of bass. But its probably cheaper just to fill the gap with concrete.
> 
> PS: A very solid room is more easily filled with insane bass decibel.


To nit-pick a little, what was discussed and agreed upon earlier in this thread was that rigidity worked AGAINST low frequency containment -- that when we talk about mass, we're really ideally hoping for "limp mass".

Concrete tends to be the go-to medium for LFE containment because it is so dense that its mass works for us far far more than its rigidity works against us. And even more so, concrete is easy to work with; readily available; and inexpensive.

Something like sand would be better from a theoretical standpoint since it is even more dense and is far more "limp"... but sand is extremely difficult to work with in a wall setting and so it's not commonly done.


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## ronny31

For bass transmission, yes, limper is better, but not for containment. More containment means more db means you turn up the bass less (assuming you're trying to listen at a certain set level not just max bass volume). Thus ideally less bass going through the walls. A neat trick that is illegal in db-drag is to pressurize the room first, so all the surfaces are under tension already and will give in less. But you can do the same with choice cut of reinforcement and pretension techniques. Like adjusting the door to fit more snug against the door seal.


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## jrref

I agree, trying to contain LFE is nearly impossible in anything that's attached, period. Even with a 20 DB reduction at the low frequencies, if your playing at 80 to 100 db, your neighbors are not going to notice the 20 DB reduction. It's going to be too loud. And because they are mostly hearing the bass frequencies, totally annoying. For me I utilize the Audyssey LFE containment option on my Marantz equipment which does a great job of reducing the Low frequencies that penetrate the wall and turn it off if I know my neighbors are out or on vacation, etc.. After a while you really don't miss the crazy heavy wall penetrating bass. I wish that Audyssey LFE containment was available on every piece of sound gear because it really works. I can play my theater pretty loud without disturbing my neighbors, of course after reconstructing the common wall with Quiet Rock and Roxul acoustic insulation.


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## New Bob

*Iso Sill 1/4" rubber isolation question?*

I'm going to use Iso sill 1/4' rubber at the base of my theater wall to isolate them from the concrete floor. I was wondering if it would be beneficial to also use it on the top plate of the walls also to isolate the ceiling joist from the wall.( Room within a room construction).Or is there no real advantage to do so?


----------



## d_c

Any suggestions for treating a stairwell as mentioned above? I have the same situation. I can soundproof the whole ht area with the normal method, but have an open stairwell with a door at the top. Door at the bottom is not an option. I was thinking clips, channel gg/DD like the rest. Thoughts?


----------



## jcr159

d_c said:


> Any suggestions for treating a stairwell as mentioned above? I have the same situation. I can soundproof the whole ht area with the normal method, but have an open stairwell with a door at the top. Door at the bottom is not an option. I was thinking clips, channel gg/DD like the rest. Thoughts?


Really hoping we can get some help on this one... Starting to wonder how much effort I should make in the rest of the theater plan. i.e. - what point is there to puttying outlets, backer boxes for can lights level of detail if the staircase is going to negate all of the work.

I'll just save the time, effort and cost, and not bother with any of it... Might even go back to the plan for a drop ceiling for convenience and tell the family to get out of the house when I want to crush some crazy bass...


----------



## d_c

This stairwell really is the only tricky part though. I think that our best option will be to treat it just like the rest of the walls in the basement. I have a solid panel door that I will beef up with gg between two layers of 3/4" mdf, automatic door seals and bottom. The other idea I have for the stairwell ceiling is to build a large acoustic panel cloud out of 1x12 and r16 to help with any sound trapped. Carpeted stairs certainly couldn't hurt the benefit. I ran some bass sweeps before mass loading the ceiling between the studs with dd/gg and simply closing the door to the basement was huge - this was before the mass loading. I will measure again before drywall goes in.


----------



## amit916

jrref said:


> I agree, trying to contain LFE is nearly impossible in anything that's attached, period. Even with a 20 DB reduction at the low frequencies, if your playing at 80 to 100 db, your neighbors are not going to notice the 20 DB reduction. It's going to be too loud. And because they are mostly hearing the bass frequencies, totally annoying. For me I utilize the Audyssey LFE containment option on my Marantz equipment which does a great job of reducing the Low frequencies that penetrate the wall and turn it off if I know my neighbors are out or on vacation, etc.. After a while you really don't miss the crazy heavy wall penetrating bass. I wish that Audyssey LFE containment was available on every piece of sound gear because it really works. I can play my theater pretty loud without disturbing my neighbors, of course after reconstructing the common wall with Quiet Rock and Roxul acoustic insulation.


Sorry, just trying to understand better what you mentioned.

Your Audyssey LFE containment option tunes the sound to lessen the low frequency sound when you know your neighbors will be annoyed? And then you crank it back up when they are gone?

How do you feel about your overall sound? How often do you crank it up for fear of neighbors complaining?


----------



## jrref

amit916 said:


> Sorry, just trying to understand better what you mentioned.
> 
> Your Audyssey LFE containment option tunes the sound to lessen the low frequency sound when you know your neighbors will be annoyed? And then you crank it back up when they are gone?
> 
> How do you feel about your overall sound? How often do you crank it up for fear of neighbors complaining?


That's correct. When I know the neighbors are home I turn on Audyssey LFE containment, set to default of 4. When I know they are out, if I want to blast, I turn it off.

With I on, after a while you don't really miss the bass frequencies it is reducing and the overall sound, to me, is excellent. Best to read the white paper on Audyssey LFE containment to see the technical details of what it's actually doing. At a high level it is reducing the frequencies that travel through the wall the most.The bottom line is at it works.


----------



## amit916

jrref said:


> That's correct. When I know the neighbors are home I turn on Audyssey LFE containment, set to default of 4. When I know they are out, if I want to blast, I turn it off.
> 
> With I on, after a while you don't really miss the bass frequencies it is reducing and the overall sound, to me, is excellent. Best to read the white paper on Audyssey LFE containment to see the technical details of what it's actually doing. At a high level it is reducing the frequencies that travel through the wall the most.The bottom line is at it works.


Ah okay, I'll definitely have too look into that, Thanks.

Do you also have butt kickers to make up for that visceral feel of the bass?


----------



## jrref

amit916 said:


> Ah okay, I'll definitely have too look into that, Thanks.
> 
> Do you also have butt kickers to make up for that visceral feel of the bass?


No, just a regular sub.


----------



## BasementBob

jrref said:


> For me I utilize the Audyssey LFE containment option on my Marantz equipment which does a great job of reducing the Low frequencies that penetrate the wall and turn it off if I know my neighbors are out or on vacation, etc..


My old receiver used to do that with a convenient 'Night Mode' button on the remote. The new receiver has something similar, but it's buried in a menu and hard to remember let alone use. So I bought 'Noma Wireless Remote Switch with 3 Receivers' (remote control receptacle outlets, CanadianTire.ca Product# 52-8868-4 ), and plugged my subwoofers into those. I had tried a couple other brands of such remotes in 2014, one didn't work, and the other ran hot. Reviews suggest 52-8868-4 by Noma were terrible in 2011, but I bought two sets in 2015 and they're both fine.


----------



## jrref

BasementBob said:


> My old receiver used to do that with a convenient 'Night Mode' button on the remote. The new receiver has something similar, but it's buried in a menu and hard to remember let alone use. So I bought 'Noma Wireless Remote Switch with 3 Receivers' (remote control receptacle outlets, CanadianTire.ca Product# 52-8868-4 ), and plugged my subwoofers into those. I had tried a couple other brands of such remotes in 2014, one didn't work, and the other ran hot. Reviews suggest 52-8868-4 by Noma were terrible in 2011, but I bought two sets in 2015 and they're both fine.


This sounds like another good solution but the audyssey LFE containment doesn't turn off the sub, it just lowers and or eliminates the frequencies that tend to pass through a wall. Depending on your situation there are different levels that you can set it to. The result is that you still get good bass and overall good sound.


----------



## amit916

I've seen a few people do a new set of ceiling joists, while I've seen some go with the clips rout in how to decouple the ceiling... it's either one or the other right? I mean you wouldn't find yourself doing both because the goal is to decouple which both do. Also, would these new set of joists would have complete separation from the other set of joists?

Sounds like a strong possibility I might be able to weave a new set of joists in (which would the most useful in soundproofing). I've talked to my GC and made it known that the only way this works is if there's nothing up there (obstruction) otherwise it won't work and he assured me.

Along with a room within a room, I'm hoping this is enough along with clips and DD/GG will lead to satisfactory results.

(I really should just start my own build thread... I think have enough to go on and build one)


----------



## nandkisham

*Absorption*

Absorption Question


I have seen in few builds where the pink insulation is covered by a 'x'mil plastic.

Question:

1) Is it just to protect loose fibers from becoming airborne while the build process is on? or does it act as a barrier of some sort for temperature changes?
2) If so, does it apply to basement or above ground builds?


Regards


----------



## HT Geek

nandkisham said:


> Absorption Question
> 
> 
> I have seen in few builds where the pink insulation is covered by a 'x'mil plastic.
> 
> Question:
> 
> 1) Is it just to protect loose fibers from becoming airborne while the build process is on? or does it act as a barrier of some sort for temperature changes?
> 2) If so, does it apply to basement or above ground builds?





nandkisham said:


> Absorption Question
> 
> 
> I have seen in few builds where the pink insulation is covered by a 'x'mil plastic.
> 
> Question:
> 
> 1) Is it just to protect loose fibers from becoming airborne while the build process is on? or does it act as a barrier of some sort for temperature changes?
> 2) If so, does it apply to basement or above ground builds?


My understanding is there are 2 schools of thought on this:

1) In many portions of the USA, paper faced insulation is installed, with the kraft paper side almost always facing the inside of the home. The purpose is to keep moisture from leeching into your drywall. My rule-of-thumb is to use whatever the home builders in your area use. Here in Austin, the RoT is non-faced insulation. Per your profile, you seem to be near Houston. Perhaps yours may be paper-faced _out_ to keep the humidity outside (?). I don't know. I'd suggest you check in your walls when it's convenient, or ask a local builder/contractor.

2) If you're building a "room-within-a-room" or a completely interior room in the home will be your HT room, some folks install paper-faced insulation because it attenuates the low frequency signals better when compared to identical unfaced fiberglass insulation (see Bob Gold's absorption coefficients - scroll down to the "fluffy pink" section). The catch is - I believe this attenuation is coupled with a slight reflective property in the higher frequencies - though I could be wrong about that. What I know for sure is the unfaced insulation is more consistent with its damping properties across the STC spectrum (~125 to 4 or 5 khz) and the faced insulation is much less absorptive of high freqs versus the unfaced.

I'll illustrate with an example from Bob's site:


PRODUCT -- THICKNESS - MOUNTING -- 125HZ - 250HZ - 500HZ - 1000HZ - 2000HZ - 4000HZ - NRC
Unfaced ........ 3.5" R11 ........ on wall ..... 0.34 .... 0.85 .... 1.09 ..... 0.97 ..... 0.97 ..... 1.12 ...... 0.95
Paper Out ..... 3.5" R11 ........ on wall ..... 0.58 .... 1.11 .... 1.16 ..... 0.61 ..... 0.40 ..... 0.21 ...... 0.80

To re-cap, you could consider using paper faced insulation within your interior "room" walls. I would recommend that on exterior walls you follow your home builder's protocol.

Also, whether or not you get possibly unwanted reflections of higher freqs off the paper would (I suspect) be influenced by whether the paper was 'in' (source room side) or 'out', with the preferred method presumably facing it 'out'.... that would allow the pink fluffy to work its magic before the sound waves hit the paper and bounce back. But that is pure conjecture on my part. I'm not an expert on this issue. Hopefully, someone who's got a concrete view on the subject will chime in.


----------



## HT Geek

Waterboy77 said:


> Test Results
> Clause.... I am not a lab nor do I own high end measuring equipment... just a db meter for this measuring.
> How I did the tests is covered in this post.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hammer Drop 72 / 70 / 67
> 
> Calculations
> I hope this is correct to do..... I took the bd at 0 (reference) and subtracted the OFF bd (eg. 88-31=57db in MLP) This gives me a base line with normal ambient sound removed
> With no treatment I have a reduction from 57db to 28db = 29db
> With one layer DW GG a reduction from 58db to 24db = 34db
> With two layers DW GG a reduction from 58.2db to 22.5db = 35.7db
> 
> Therefore one layer reduced the sound 5 db and two 6.7 db
> Hammer drop resulted in a 5 db reduction with two layers


So thankful to you for posting your data. Regardless of your samples' limitations, we have a lot of subjective comments on the forum and not a lot of subjective comments + objective data, especially with regards to 'real' environments (i.e. someone's HT and home and not in a lab... though lab data is certainly indispensable, so are comments from those of us who've gone through the entire process already).

While subjective comments are most certainly welcome (at least to me), it's helpful when someone is able to explain their viewpoint correlated with real-world numbers. So, thanks again.


----------



## Waterboy77

HT Geek said:


> So thankful to you for posting your data. Regardless of your samples' limitations, we have a lot of subjective comments on the forum and not a lot of subjective comments + objective data, especially with regards to 'real' environments (i.e. someone's HT and home and not in a lab... though lab data is certainly indispensable, so are comments from those of us who've gone through the entire process already).
> 
> While subjective comments are most certainly welcome (at least to me), it's helpful when someone is able to explain their viewpoint correlated with real-world numbers. So, thanks again.


No problem, I also like data and had a tough time finding any just on the joist drywall installation.
Hopefully in the near future I will be expanding on this with the completion of the insulation in the ceiling


----------



## HT Geek

*caveat emptor*



granroth said:


> I personally think most people massively overestimate how effective their soundproofing methods will be when it comes to LFE. Low frequency sound is insanely difficult to contain and really the only thing that truly works is lots of mass.


^^^ What he said

Granroth's test references (and many others I've read) have me tending toward a conclusion that mass, air cavities, and insulation are the items doing the real work in damping LFE. So called 'damping' products (for lack of a better term coming to my mind atm), do have their place but they are not miracle workers. These products are (generally) far more effective in other (higher) frequency ranges (though there is certainly nothing wrong with a product that helps attenuate noise coming in or out of one's HT room period). In some cases these products may also aid LFE, but it's difficult to tell. There are also other options to mitigate LFE besides viscoelastic materials (e.g. Green Glue).



> Let's take these two tested wall assemblies as examples.
> 
> The first is a wall with an STC 63 rating, made with clips and channels plus 2 x 5/8" drywall with Green Glue on both sides....
> 
> Let's look at another wall. This has an STC rating of 62 and is a staggered stud wall plus 2 x 5/8" drywall with Green Glue on both sides....
> 
> I don't have any testing data with Green Glue on hand for a double wall, but it'd likely be only a little bit better than a staggered stud wall.


Relative to Granroth's comments above:

1) The


----------



## BasementBob

HT Geek said:


> So called 'damping' products (for lack of a better term coming to my mind atm), do have their place but they are not miracle workers.


The atypical products may work, but drywall & concrete are cheaper and work better, which is why professionals use them and labs test lots of combinations of them. Also, they don't decay and off gas contaminants that kill us, over time or in a fire, indeed have the nice side benefit that they are fire proof and fire isolating.
The atypical products, like mass loaded vinyl, work great in places you can't use drywall. Wrapping pipes for example.
As you said, the biggies are: {mass, air gap, insulation, green glue and other viscoelastics specifically designed for walls and with posted lab tests, and attention to detail avoiding flanking and shorting and tripling and ...}.

Interesting observations re no viscoelastic walls. By the way, when evaluating low frequency lab results you should be recalling that they're outside of the reliability range of the test building (flanking), and what you're looking for is where the resonance dip is in hz. Where the resonance dip is gives better clues as to what's happening above and below it, outside of the even the unreported lab test range.


----------



## nandkisham

*3/4 OSB instead of 5/8 as first layer*

Folks,

I am doing the channel + OSB + GG+ 5/8 DW.

Are there any concerns (good/bad) that you guys know of when using 3/4 OSB vs 5/8 OSB as a base layer?

Thoughts..

Regards,

NJ


----------



## HT Geek

nandkisham said:


> Are there any concerns (good/bad) that you guys know of when using 3/4 OSB vs 5/8 OSB as a base layer?


Yes. P.I.T.A. to install on the ceiling (i.e H-E-A-V-Y)!

Should be good result tho.


----------



## BasementBob

nandkisham said:


> I am doing the channel + OSB + GG+ 5/8 DW.
> 
> Are there any concerns (good/bad) that you guys know of when using 3/4 OSB vs 5/8 OSB as a base layer?



OSB, provided it's ok in your local building code, is fine from a soundproofing point of view.


The usual reason for OSB/wood as the first layer, is so that you can put screws in anywhere to hang stuff -- otherwise the OSB just costs more than corresponding drywall.
But with channel, willy nilly fastening might lead to shorting the channel.


----------



## HT Geek

BasementBob said:


> OSB, provided it's ok in your local building code, is fine from a soundproofing point of view.


Good point. I am doing OSB as 1st layer in my HT room and checked w/local code inspector. It is legal here, as long as you have fire-code compliant veneer (e.g. drywall) on the _inside_ of the room. Considering the fact my HT room is 2nd floor w/attic above, if a fire started outside that room it wouldn't matter what the room walls and ceiling were made of. Most of my attic already has 3/4" OSB flooring that the builder installed.

OP should double-check code tho. My recollection is NJ has a bit stricter compliance on some parts of the IRBC.


----------



## nandkisham

HT Geek said:


> Good point. I am doing OSB as 1st layer in my HT room and checked w/local code inspector. It is legal here, as long as you have fire-code compliant veneer (e.g. drywall) on the _inside_ of the room. Considering the fact my HT room is 2nd floor w/attic above, if a fire started outside that room it wouldn't matter what the room walls and ceiling were made of. Most of my attic already has 3/4" OSB flooring that the builder installed.
> 
> OP should double-check code tho. My recollection is NJ has a bit stricter compliance on some parts of the IRBC.


Thanks @HTGeek and @BasementBob.
@HTGeek, I am in Houston, TX. so, we should be ok. NJ is my initials. My concerns were more from a sound proofing perspective. with more mass, that should be ok too. I purchased a panel lift 

myLowes homestore doesn't stock 5/8 OSB anymore. Going for 3/4 OSB....

Can we just keep the 48" (Horizontal) and 24" (V) oc channel placement for this added weight?


----------



## nandkisham

HT Geek said:


> Good point. I am doing OSB as 1st layer in my HT room and checked w/local code inspector. It is legal here, as long as you have fire-code compliant veneer (e.g. drywall) on the _inside_ of the room. Considering the fact my HT room is 2nd floor w/attic above, if a fire started outside that room it wouldn't matter what the room walls and ceiling were made of. Most of my attic already has 3/4" OSB flooring that the builder installed.
> 
> OP should double-check code tho. My recollection is NJ has a bit stricter compliance on some parts of the IRBC.


Thanks @HTGeek and @BasementBob.
@HTGeek, I am in Houston, TX. so, we should be ok. NJ is my initials. My concerns were more from a sound proofing perspective. with more mass, that should be ok too. I purchased a panel lift 

myLowes homestore doesn't stock 5/8 OSB anymore. Going for 3/4 OSB....

Can we just keep the 48" (Horizontal) and 24" (V) oc channel placement for this added weight?


----------



## Ladeback

I have a question about using the whisper clips to decouple the sheet rock from the wall. Is it necessary to use them on concrete walls? I am slowly building my home theater in my basement and two of my walls are concrete where I am adding 1" of Styrofoam as a moisture/thermal barrier then sound insulation between the studs. Do I really need to decouple from the concrete walls? The room is under my main living room above so I am mostly worried about sound going up and I am not going to be doing much with that just yet. Would using the acoustic caulk and putty around the plastic outlet boxes help a lot too? Doing this on a budget and the extra clips and stuff really isn't in it.


----------



## kyloren

Try this out near the bottom. http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/

It would seem that LFE would be severely compromised while improving the higher ranges. Something to consider.


----------



## kmhvball

Ladeback said:


> I have a question about using the whisper clips to decouple the sheet rock from the wall. Is it necessary to use them on concrete walls? I am slowly building my home theater in my basement and two of my walls are concrete where I am adding 1" of Styrofoam as a moisture/thermal barrier then sound insulation between the studs. Do I really need to decouple from the concrete walls? The room is under my main living room above so I am mostly worried about sound going up and I am not going to be doing much with that just yet. Would using the acoustic caulk and putty around the plastic outlet boxes help a lot too? Doing this on a budget and the extra clips and stuff really isn't in it.


If you have a 2x4 Stud wall parallel to the concrete wall, then you don't need clips & channel, the space between the stud wall & concrete wall are your decoupling... They do suggest connecting the stud wall to the ceiling using IB3 type clips... one every 4 feet and on each side of a door.. makes building the wall & leaning it up easier since the intent is that the wall is shorter than the floor joists. 

I would definitely suggest clips & hat channel on the ceiling... I went with 2 layers of 5/8" DW on the subfloor (with GG on each layer) , insulation, clips & channel, and then 2 layers of 5/8" DW with GG in between. Other than LFE, quite good results.

I did two layers on the walls too... 1st layer OSB, and 2nd Layer DW... I stubbed my electric & low voltage wires out of the walls through small holes. I did then apply acoustical sealant around them as well.


----------



## HT Geek

nandkisham said:


> NJ is my initials.


:grin:



> Can we just keep the 48" (Horizontal) and 24" (V) oc channel placement for this added weight?


NJ,

You should be fine. 3/4" OSB is heavier than drywall, but not by much. You are talking about a ~13.5% increase over 5/8" drywall (2.3 psf vs 2.2 psf). If you are just putting up 1 layer 3/4" OSB + 1 layer 5/8" or 1/2" DW, it's a minimal variation in weight vs. 2x DW.

BTW, are you planning clips & channel on the ceiling? That's the one area I get nervous about with clips. Think about the same load as your walls, then add a projector, soffits, can lights, ceiling speakers, backer boxes, etc., plus fighting gravity directly on one axis. One small upside to OSB on the ceiling is a slight advantage in weight distribution (it's stiffness helps to reduce the ceiling load's deflection; plywood is even better).

Most clips are rated at 36 lbs. (a very few are 50+ lbs.). 36 lbs.= 6 square feet @ 6psf OR 4.5psf over 8 square feet (just 0.1 lbs. less than the psf of 2x 5/8" DW sheets). So, IMHO standard spacing with standard clips leaves you zero margin for additional weight. 

Let's say you have 1 layer 3/4" OSB + 1 layer 5/8" drywall + insulation. That's roughly 2.5 + 2.2 + 0.5-1.0 psf (lbs. per square foot) or 5.2-5.7 psf total of dead weight. Pad yourself a bit. Call it 6 lbs./sqft. Now if you add speakers, can lights, soffits, etc. you will need to take that into consideration as well (i.e. more weight), which means, obviously you will need more clips. Furthermore, you will want to be strategic with your ceiling clip placement, to avoid spots of unsupported weight that could cause non-uniform sagging. Common sense will get you 90% of the way there. A few brief math calculations will verify your instincts.

Here are some references that may be useful to you:
Plywood: Thickness and Weights, Nominal, Sanded

This is a decent resource for OSB vs. plywood weights.

The bottom line is 3/4" OSB is ~2.5 lbs./sqft, 5/8" DW is ~2.2 lbs./sqft.

You want this:










Not this:


----------



## HT Geek

Ladeback said:


> I have a question about using the whisper clips to decouple the sheet rock from the wall. Is it necessary to use them on concrete walls? I am slowly building my home theater in my basement and two of my walls are concrete where I am adding 1" of Styrofoam as a moisture/thermal barrier then sound insulation between the studs.


So, is there already a 1" air gap between your studs and the concrete wall?



> Do I really need to decouple from the concrete walls?


It depends. If you'd like sound from your HT room to travel through the wall to whatever its connected to, then no. If you don't want that to happen, then yes it's important that it be decoupled.

Could you put a thermal barrier on the inside of the studs and/or fill their cavities with faced fiberglass insulation? If you could do that and leave a 1" air gap between the stud wall and concrete wall, I believe that would be a better solution. 

Is moisture and/or humidity a concern for you? [You mentioned styrofoam as moisture/thermal barrier which is why I'm mentioning this here.] If so, Rockwool is another option as it is naturally resistant to absorbing water. Or you could install faced fiberglass insulation with the paper facing outward (toward the higher moisture content, if it's not an excessive issue). FYI, in my local market, Rockwool is 2x the cost of fiberglass insulation. 




> The room is under my main living room above so I am mostly worried about sound going up


Rightfully so!

If you do not de-couple your stud wall to the concrete wall, and if the concrete wall is in any way connected to your living room upstairs (e.g. common foundation), the sound will get up there. Just food-for-thought in reference to your 1st question above.




> Would using the acoustic caulk and putty around the plastic outlet boxes help a lot too?


Yes. Box of 20 ~100 (e.g., http://www.amazon.com/SpecSeal-SSP-Putty-Pads-Case/dp/B00SVH60MG/ref=sr_1_1?ie=UTF8&qid=1453854847&sr=8-1&keywords=putty+pads)

I can't tell from the picture for sure, but they look identical to 3M fire and acoustic pads I've used before that were slightly larger and thicker than QuietPutty pads (and cheaper).



> Doing this on a budget and the extra clips and stuff really isn't in it.


Understood. The best form of isolation is a double stud wall with floating ceiling. No clips, but requires lots of wood or steel studs & joists. In your situation, it sounds like decoupling the HT room ceiling will be a priority.

What are your room dimensions (LxWxH)? What is the ceiling in your HT room composed of? Is there a floor truss above it, wood beams, concrete, etc.? What are the other walls in your HT room composed of? And what is the sub-floor made of?


----------



## HT Geek

kmhvball said:


> connecting the stud wall to the ceiling using IB3 type clips...


@ Ladeback,

also RSIC-DC04 clips work; $5 is the cheapest advertised price I've ever seen. Not sure about $ on the IB3.


----------



## Ladeback

HT Geek said:


> So, is there already a 1" air gap between your studs and the concrete wall?
> 
> 
> 
> It depends. If you'd like sound from your HT room to travel through the wall to whatever its connected to, then no. If you don't want that to happen, then yes it's important that it be decoupled.
> 
> Could you put a thermal barrier on the inside of the studs and/or fill their cavities with faced fiberglass insulation? If you could do that and leave a 1" air gap between the stud wall and concrete wall, I believe that would be a better solution.
> 
> Is moisture and/or humidity a concern for you? [You mentioned styrofoam as moisture/thermal barrier which is why I'm mentioning this here.] If so, Rockwool is another option as it is naturally resistant to absorbing water. Or you could install faced fiberglass insulation with the paper facing outward (toward the higher moisture content, if it's not an excessive issue). FYI, in my local market, Rockwool is 2x the cost of fiberglass insulation.
> 
> 
> 
> 
> Rightfully so!
> 
> If you do not de-couple your stud wall to the concrete wall, and if the concrete wall is in any way connected to your living room upstairs (e.g. common foundation), the sound will get up there. Just food-for-thought in reference to your 1st question above.
> 
> 
> 
> 
> Yes. Box of 20 ~100 (e.g., http://www.amazon.com/SpecSeal-SSP-Putty-Pads-Case/dp/B00SVH60MG/ref=sr_1_1?ie=UTF8&qid=1453854847&sr=8-1&keywords=putty+pads)
> 
> I can't tell from the picture for sure, but they look identical to 3M fire and acoustic pads I've used before that were slightly larger and thicker than QuietPutty pads (and cheaper).
> 
> 
> 
> Understood. The best form of isolation is a double stud wall with floating ceiling. No clips, but requires lots of wood or steel studs & joists. In your situation, it sounds like decoupling the HT room ceiling will be a priority.
> 
> What are your room dimensions (LxWxH)? What is the ceiling in your HT room composed of? Is there a floor truss above it, wood beams, concrete, etc.? What are the other walls in your HT room composed of? And what is the sub-floor made of?


HT Geek, you have been very helpful. I forgot to mention that the wall I built parallel to the concrete wall also has about a 3.5" air gap between the 1" Styrofoam and the stud wall. I haven't built the second wall along the concrete yet. I do have another wall we have built to separate the HT from my storage area. the distance from that wall to the nearest concrete wall is about 13'. My stud walls are fastened into the the joist above and the floor below now, so there is no way adding clips there now. For now I am just going to go with one layer off 1/2" Sheetrock and add Rockwool insulation. It is about $15 to $20 more the fiberglass insulation. I may just insulate the one to the concrete first since I can get to the other at any time to add insulation if needed.

For the ceiling I am not doing anything at this time other then maybe adding Rockwool between the joist to see if that helps with sound first. 

My room I am building is going to be around 21'x25.5' when I am done, with the back wall opened to the rest of the basement for now. Not sure if I am going to add a wall there or not. If sound is a big issue for the wife then I will have to, but I want to make the area that connects with HT to be a bar/gaming area. I will try to upload some photos this weekend of the area.

Thank you for the help,

Doug


----------



## Ladeback

HT Geek said:


> So, is there already a 1" air gap between your studs and the concrete wall?
> 
> 
> 
> It depends. If you'd like sound from your HT room to travel through the wall to whatever its connected to, then no. If you don't want that to happen, then yes it's important that it be decoupled.
> 
> Could you put a thermal barrier on the inside of the studs and/or fill their cavities with faced fiberglass insulation? If you could do that and leave a 1" air gap between the stud wall and concrete wall, I believe that would be a better solution.
> 
> Is moisture and/or humidity a concern for you? [You mentioned styrofoam as moisture/thermal barrier which is why I'm mentioning this here.] If so, Rockwool is another option as it is naturally resistant to absorbing water. Or you could install faced fiberglass insulation with the paper facing outward (toward the higher moisture content, if it's not an excessive issue). FYI, in my local market, Rockwool is 2x the cost of fiberglass insulation.
> 
> 
> 
> 
> Rightfully so!
> 
> If you do not de-couple your stud wall to the concrete wall, and if the concrete wall is in any way connected to your living room upstairs (e.g. common foundation), the sound will get up there. Just food-for-thought in reference to your 1st question above.
> 
> 
> 
> 
> Yes. Box of 20 ~100 (e.g., http://www.amazon.com/SpecSeal-SSP-Putty-Pads-Case/dp/B00SVH60MG/ref=sr_1_1?ie=UTF8&qid=1453854847&sr=8-1&keywords=putty+pads)
> 
> I can't tell from the picture for sure, but they look identical to 3M fire and acoustic pads I've used before that were slightly larger and thicker than QuietPutty pads (and cheaper).
> 
> 
> 
> Understood. The best form of isolation is a double stud wall with floating ceiling. No clips, but requires lots of wood or steel studs & joists. In your situation, it sounds like decoupling the HT room ceiling will be a priority.
> 
> What are your room dimensions (LxWxH)? What is the ceiling in your HT room composed of? Is there a floor truss above it, wood beams, concrete, etc.? What are the other walls in your HT room composed of? And what is the sub-floor made of?


HT Geek, you have been very helpful. I forgot to mention that the wall I built parallel to the concrete wall also has about a 3.5" air gap between the 1" Styrofoam and the stud wall. I haven't built the second wall along the concrete yet. I do have another wall we have built to separate the HT from my storage area. the distance from that wall to the nearest concrete wall is about 13'. My stud walls are fastened into the the joist above and the floor below now, so there is no way adding clips there now. For now I am just going to go with one layer off 1/2" Sheetrock and add Rockwool insulation. It is about $15 to $20 more the fiberglass insulation. I may just insulate the one to the concrete first since I can get to the other at any time to add insulation if needed.

For the ceiling I am not doing anything at this time other then maybe adding Rockwool between the joist to see if that helps with sound first. 

My room I am building is going to be around 21'x25.5' when I am done, with the back wall opened to the rest of the basement for now. Not sure if I am going to add a wall there or not. If sound is a big issue for the wife then I will have to, but I want to make the area that connects with HT to be a bar/gaming area. I will try to upload some photos this weekend of the area.

Thank you for the help,

Doug


----------



## HT Geek

Ladeback said:


> I forgot to mention that the wall I built parallel to the concrete wall also has about a 3.5" air gap between the 1" Styrofoam and the stud wall.


Doug,

That 3.5" buffer is plenty of room. FYI, you can have the smallest of gaps, so long as when your inner wall is vibrated by sound it does not touch the neighboring surface (i.e. just enough to separate the HT room structure from neighboring structures; presuming one is building a room-within-a-room concept). Most folks recommend 1" because it avoids problems such as studs that are not perfectly straight.



> I haven't built the second wall along the concrete yet. I do have another wall we have built to separate the HT from my storage area. the distance from that wall to the nearest concrete wall is about 13'.


I'm a little confused by your comments above. By "second wall" are you referring to the next wall for your HT room (presumably that will be connected to your first wall)?




> My stud walls are fastened into the the joist above and the floor below now, so there is no way adding clips there now. For now I am just going to go with one layer off 1/2" Sheetrock and add Rockwool insulation. It is about $15 to $20 more the fiberglass insulation. I may just insulate the one to the concrete first since I can get to the other at any time to add insulation if needed.


You should plan on at least 2 layers of sheetrock. The more mass, the better (at stopping sound from entering/leaving a room). 5/8" is the gold standard. It is ~0.2psf heavier than 1/2" drywall. You mentioned before that you have a tight budget. 5/8 is nearly the same price as 1/2 drywall. Make sure you do not use the "lightweight" or "performance" drywall. You can skip the viscoelastic damping compound that is recommended between drywall layers (e.g. Green Glue or Quiet Glue Pro). You might be able to substitute something else such as #30 roofing felt to at least provide some other option, but please don't quote me on that... if you search in the forum you might find someone who has tried that... I have not... just tossing out alternative concepts that don't cost a lot of $$$$ such as Green Glue. But I'd say at least do 2 layers of sheetrock plus insulation. It's probably the cheapest of all the materials you need for the job, excluding screws.

Other thoughts... just because we don't have photos atm... are you thinking of sheet rocking your existing/1st wall before you put up the other walls? That would not be a good idea for a number of reasons. You need to get all the framing done first, then figure out where/how things such as electrical, low voltage, and speaker wire will be routed before you even put in the insulation.

MLV (Mass Loaded Vinyl) can be installed on the studs/joists prior to drywall, but I don't recommend it. The cons outweigh the benefits (difficult to handle/install, easily short-circuited, relatively expensive, not very effective). Put up a 3rd layer of drywall if you think 2 layers is not cutting the sound enough.

Am I correct in presuming this room is in your basement and the floor is concrete?

Are you planning to build a riser? A soffit?

Will you be viewing a TV or a projector screen?

Back to the framing, etc.... so, there are going to be trade-offs. If you have not done so already, stop your work and think hard about your starting goals. For example, you mentioned your concerns about noise emanating from your HT room to the room above. (btw, I say "starting goals" because I have learned that you will encounter challenges along your journey that cause you to stop and question your goals, and they may change for this reason as you work through the project)

Have you also considered the potential effect of the reverse, i.e. sound from the room above filtering into your dedicated HT room? Impact or footfall noise can be particularly difficult to mitigate, especially if there are hardwood floors in that room.

Regardless of which direction is an issue, if sound propagation through the HT ceiling is a big issue, you will have to make a significant effort to dampen or eliminate pathways that sound can travel back and forth. For example, walls directly attached to the joists above, which are directly attached to the sub-floor in the room above, will likely be a big headache for you. There are varying levels of extremism that you could go to. If you can't stand any noise in that room above, then you will need to take extreme measures. If you can tolerate some and/or are willing to turn down the volume at times in the HT room, you can take less extreme measures.

Since you've only done one wall so far, I know it sounds drastic but you ought to consider the pros and cons of removing it and replacing it with a de-coupled wall (via IB3 or RSIC-DC04 clips every 2-4 feet [distance depends on clip model & exact use] to provide structural integrity through a de-coupled connection to a neighboring structural stud wall and/or concrete wall). You could also consider framing the remaining walls and ceiling and then using clips and channels to isolate them, or maybe clip the ceiling but that is really overkill in your situation. Since you have the opportunity to build the walls the way you want them, using a double stud arrangement seems like the best bang-for-the-buck (and cheaper) route to me.

Could you build another wall inside the one you already built and use this new inner wall as your HT wall? Sort of start over on the wall but without tearing out your existing work? It's difficult to make suggestions like this without seeing a diagram and/or photos. If not, just working with what you've got right now... you could damp the space between the floors with as much drywall (mass) as you can shove in there plus some insulation to help reduce airborne noise. Just be aware that if the HT room walls and ceiling are physically connected to the floor joists above, you are going to get vibration and some sound transferred as a result (especially LFE or Low Frequency Emissions).

These are just a couple of many concepts that might be helpful for you to consider.




> For the ceiling I am not doing anything at this time other then maybe adding Rockwool between the joist to see if that helps with sound first.


As I mentioned above, it will help with airborne noise but your main nemesis is going to be the sound travelling through all that interconnected woodwork (joists, etc.). Imagine all those structural points in your home are electrical circuits. As yourself if you were to apply a current to any of the points in your HT room, would it travel up to the room above? Then try and determine how many of those "short circuit" points there are. One or two will not be a drastic issue for most people, but dozens will be.




> My room I am building is going to be around 21'x25.5' when I am done, with the back wall opened to the rest of the basement for now. Not sure if I am going to add a wall there or not. If sound is a big issue for the wife then I will have to, but I want to make the area that connects with HT to be a bar/gaming area. I will try to upload some photos this weekend of the area.


Sounds like it will be awesome when you're finished. 

A few other miscellaneous thoughts:

1. Don't frame in a perfectly square room. Square shaped rooms tend to amplify a problem involving reflected sound waves. You'll have less work taming any echos or related problems if your room is rectangular.

2. Think about egress in/out of the room. Where would you like to have the door/entrance? I'd suggest you don't put it on the same wall as the screen or TV.

3. Overall shape of your space, where the stairs will be relative to the sound waves bouncing around, etc.




> Thank you for the help,


My pleasure, and glad it's helpful. I tend to be verbose, so please let me know if I'm giving you TMI. 

I don't know everything but I have learned (and continue to learn) a lot from experience (mostly screwing things up and then figuring out how to fix them or live with them) and from many other contributors on AVS.

My #1 piece of advice is try to get a good grip on your true goals and desires, be realistic with yourself, and don't get discouraged when you determine something hasn't gone as you expected or you need to rip it out and do it over again. Then enjoy the journey. It's a huge project and it will take [a lot of] time. When you're done, all your friends (and wife) will be impressed.

This stuff gets overwhelming very quickly. Just focus on your walls and ceiling plan for now. Worry about other issues such as flanking noise after you get your rough plan figured out.


----------



## HT Geek

Ladeback said:


> the distance from that wall to the nearest concrete wall is about 13'.


Sounds like an excellent location for an A/V or rack room. If you have the space, consider an independent "room" for your A/V equipment, DVDs, etc.

If you search up Art's theater (w/photos) he did this and it's a great concept. Wish my home's layout would allow me to do the same.


----------



## amit916

I have a bedroom/closet on the other side (two wall) theater room... should the speakers be on the opposite side (furthest away but pointed in the direction of the bedroom) or should they be on the same wall (but pointed away)?

I've heard some people refer to subwoofers as omnidirectional... and since LFE is harder to contain, where would it be advisable to place my speakers and screen when it pertains to that bedroom?


----------



## HT Geek

amit916 said:


> I have a bedroom/closet on the other side (two wall) theater room... should the speakers be on the opposite side (furthest away but pointed in the direction of the bedroom) or should they be on the same wall (but pointed away)?
> 
> I've heard some people refer to subwoofers as omnidirectional... and since LFE is harder to contain, where would it be advisable to place my speakers and screen when it pertains to that bedroom?


I cannot answer your question definitively, but I'd say it would be worthwhile to look at a polar plot of your speakers, if you can find one. That would at least give you a good idea of what kind of emissions to expect behind the speaker cabinets, their strength, and frequency. That said, LFE is going to travel further - as you said.

You might also consider punching your room dimensions into a standing wave calculator (Excel version attached to this post). This site is also informative. At the opposite end of the spectrum is Bob's calculator (it looks plain-Jane... until you hit the calc button). Bob's conveniently converts between imperial and metric.

What type and amount of absorption were you planning for the wall opposite the speakers?

Have you considered a baffle wall?


----------



## HT Geek

nandkisham said:


> Can we just keep the 48" (Horizontal) and 24" (V) oc channel placement for this added weight?


Not sure which clip you are considering, but RSIC-1 tech spec attached for your convenience since it is more or less an industry standard. See pgs. 6-7 for max load and O.C. spacing requirements. There are some 16 O.C. scenarios.

It's possible the shear strength of double screw clips such as the Whisper Clip or Genie Clip may be a better fit for heavy loads. OTOH, they are also rated @ 36 lbs. max. Just saying logically you'd think 2 screws would be better than one, but I don't know. I also would not want to be the guinea pig tester who finds out. LOL. 

There are 48+ lb. clips (max I've seen is 144 lbs.), but many of them are for different applications such as suspended ceilings. I believe 36 lbs. shear force is standard for hat channel clips. You could of course always increase your clip density psf and that would solve the problem.


----------



## amit916

HT Geek said:


> I cannot answer your question definitively, but I'd say it would be worthwhile to look at a polar plot of your speakers, if you can find one. That would at least give you a good idea of what kind of emissions to expect behind the speaker cabinets, their strength, and frequency. That said, LFE is going to travel further - as you said.
> 
> You might also consider punching your room dimensions into a standing wave calculator (Excel version attached to this post). This site is also informative. At the opposite end of the spectrum is Bob's calculator (it looks plain-Jane... until you hit the calc button). Bob's conveniently converts between imperial and metric.
> 
> What type and amount of absorption were you planning for the wall opposite the speakers?
> 
> Have you considered a baffle wall?


Yes, currently I'm going over the idea of a baffle wall (I've seen at least one member here who's placed the 1099 inside a baffle wall. If it would help having a baffle wall on the same wall (it's not since it'll be double framed), then yes, I will strongly look into building one.

I'm curious, what the standing waves inside the room would mean for the bedroom on the other side?


----------



## HT Geek

amit916 said:


> Yes, currently I'm going over the idea of a baffle wall (I've seen at least one member here who's placed the 1099 inside a baffle wall. If it would help having a baffle wall on the same wall (it's not since it'll be double framed), then yes, I will strongly look into building one.


Proceed with caution if you do. For starters, I'd suggest consulting with Erich or Tux on the subject. I recall there is a resistor mod for the 1099 when behind or in front of a screen (I don't recall which). I don't know if that would be relevant but they may have some input on using the 1099 in a baffle. 

I'd also suggest a modicum of general research on baffle walls. They are easy to 'screw up' per se. For instance, the surface of the wall needs to be flat, padding/dampening in the right places around the speaker, etc. That being said, it's like almost everything you read here.... There are the ideal or reference methods, and then there are the methods that are 'good enough' for any particular person. Only you can determine your needs and associated reasonable level-of-effort that suits them.

I'm attaching a few documents on the subject to this post that may be worth a read.

And here are a few of the finer points I've collected over time (mostly from senior AVS members):


Ideally front [front of room] of speaker baffle should be flush with absorption
Baffle should not be significantly recessed into absorption.
You best have your speaker placement exact for proper listening and sound stage creation ... you're not moving them later
There is no standard, rule of thumb approach.
A poor baffle wall will do more damage to SQ than a good baffle wall will do to improve SQ (SQ = sound quality)
The key to getting the advantages of a baffle wall without creating other, non-fixable problems, is to know the speaker's performance (polar radiation plots for example) and design the baffle to that end. A baffle wall must take into account the space, the speaker and the goals you're trying to achieve. 

Dennis Erskine's tips on the subject:

 run stage to ceiling, wall to wall
 be very rigid
 allow no resonances in the cavity behind the wall
 be covered with 1" (sometimes more depending on speaker) of a black absorptive material (reduces reflections between the screen and the wall)
 have the speakers resiliently mounted to the baffle
 have no air gaps between the speaker body and the baffle wall
 have all front speakers including the front subs in the same continuous baffle
 The speakers themselves should be covered with black absorptive material with cut outs for the drivers

As you can see, it is not an undertaking for the faint-of-heart! 




> I'm curious, what the standing waves inside the room would mean for the bedroom on the other side?


Bit of a tangential thought on my part... perhaps if the wall in question landed in a null that might help you out. I don't know for sure that it would. Just a random thought that seemed worth mentioning.  I suspect it would be difficult to orchestrate in a useful fashion unless you happen to get lucky. OTOH, if limiting certain frequencies were a priority, you could consider it in your design plans (but best verify the concept with an acoustician first)!

Cheers.


----------



## jeremy_daniel

maybe someone can help me with this question I saw on the green glue website that the don't recommend green glue be used on 16" oc stud wall? Is it still possible to do, I built my back wall 16 oc my side wall is not built yet but my back and side wall which is an exisitng are both 16" oc any suggestions?


----------



## granroth

jeremy_daniel said:


> maybe someone can help me with this question I saw on the green glue website that the don't recommend green glue be used on 16" oc stud wall? Is it still possible to do, I built my back wall 16 oc my side wall is not built yet but my back and side wall which is an exisitng are both 16" oc any suggestions?


That's surely referring to the fact that you don't apply Green Glue directly to the studs. Rather, you apply Green Glue in between sheets of drywall (or other sheet goods).

16" OC walls is very common and is actually code in certain places.


----------



## HT Geek

jeremy_daniel said:


> maybe someone can help me with this question I saw on the green glue website that the don't recommend green glue be used on 16" oc stud wall? Is it still possible to do...?


Yes, that's not a problem. The only reason they suggest that is because you will get slightly better sound isolation with your studs as far apart as possible (i.e. 24" O.C.). Basically, there is just less wood to vibrate/transmit sound when the studs are further apart. I can't tell you the performance difference off the top-of-my-head, but it is slight.




granroth said:


> 16" OC walls is very common and is actually code in certain places.


Wouldn't surprise me, but if your local building code mirrors the IRBC (most do), 24" O.C. is permissible if the walls are not exterior. If this is a room-within-a-room, in most cases you can do 24" OC as the wall is not supporting the main structure.


----------



## amit916

HT Geek said:


> Proceed with caution if you do. For starters, I'd suggest consulting with Erich or Tux on the subject. I recall there is a resistor mod for the 1099 when behind or in front of a screen (I don't recall which). I don't know if that would be relevant but they may have some input on using the 1099 in a baffle.
> 
> I'd also suggest a modicum of general research on baffle walls. They are easy to 'screw up' per se. For instance, the surface of the wall needs to be flat, padding/dampening in the right places around the speaker, etc. That being said, it's like almost everything you read here.... There are the ideal or reference methods, and then there are the methods that are 'good enough' for any particular person. Only you can determine your needs and associated reasonable level-of-effort that suits them.
> 
> I'm attaching a few documents on the subject to this post that may be worth a read.
> 
> And here are a few of the finer points I've collected over time (mostly from senior AVS members):
> 
> 
> Ideally front [front of room] of speaker baffle should be flush with absorption
> Baffle should not be significantly recessed into absorption.
> You best have your speaker placement exact for proper listening and sound stage creation ... you're not moving them later
> There is no standard, rule of thumb approach.
> A poor baffle wall will do more damage to SQ than a good baffle wall will do to improve SQ (SQ = sound quality)
> The key to getting the advantages of a baffle wall without creating other, non-fixable problems, is to know the speaker's performance (polar radiation plots for example) and design the baffle to that end. A baffle wall must take into account the space, the speaker and the goals you're trying to achieve.
> 
> Dennis Erskine's tips on the subject:
> 
> run stage to ceiling, wall to wall
> be very rigid
> allow no resonances in the cavity behind the wall
> be covered with 1" (sometimes more depending on speaker) of a black absorptive material (reduces reflections between the screen and the wall)
> have the speakers resiliently mounted to the baffle
> have no air gaps between the speaker body and the baffle wall
> have all front speakers including the front subs in the same continuous baffle
> The speakers themselves should be covered with black absorptive material with cut outs for the drivers
> 
> As you can see, it is not an undertaking for the faint-of-heart!
> 
> 
> 
> 
> Bit of a tangential thought on my part... perhaps if the wall in question landed in a null that might help you out. I don't know for sure that it would. Just a random thought that seemed worth mentioning.  I suspect it would be difficult to orchestrate in a useful fashion unless you happen to get lucky. OTOH, if limiting certain frequencies were a priority, you could consider it in your design plans (but best verify the concept with an acoustician first)!
> 
> Cheers.


I spoke with Tux and he said that it would be fine without any changes, though there would be a dip... also it's a very daunting task to take in information, digest it, and then hope I don't screw up. It's definitely something I'm going to look into once the room is sealed up since I was always planning on doing a false wall with my screen. It's definitely something I'll have to dive head first in once the room is sealed and see if that's something I want.


----------



## HT Geek

amit916 said:


> I spoke with Tux and he said that it would be fine without any changes, though there would be a dip... also it's a very daunting task to take in information, digest it, and then hope I don't screw up. It's definitely something I'm going to look into once the room is sealed up since I was always planning on doing a false wall with my screen. It's definitely something I'll have to dive head first in once the room is sealed and see if that's something I want.


Good that you spoke with him. Also your approach is sound. You may not even notice the dip (or you might not care).

Agreed these projects are daunting. I find myself going down the rabbit hole quite often. It's difficult to stay on the task of building a room and not exploring any other side tracks (at least for me).


----------



## jeremy_daniel

granroth said:


> That's surely referring to the fact that you don't apply Green Glue directly to the studs. Rather, you apply Green Glue in between sheets of drywall (or other sheet goods).
> 
> 16" OC walls is very common and is actually code in certain places.


Sorry yea I knew it was glued to the sheet rock not the studs. I was just curious because of their site recomendation, but good to know


----------



## BasementBob

DIY experiment thought
On last week's Mythbusters, they were lifting up cars with a vacuum.
In the boxes they finally made, they made a mold affixed to the box for a rubber seal, and poured liquid rubber into it, and the next day removed the mold leaving a large rubber seal that obviously was incredibly sealed to the box.
I wonder if the same could be done with door seals, and if that would be better than say the GM Trunk seals.


----------



## erkq

I've got a question about using Green Glue is a residential (non-theater) application. We had Quietrock put in to separate a section of our home when remodeling. The baseboard hasn't been put back yet and sound comes through where the wall meets the floor. I was wondering if Green Glue could be used to secure the baseboard to the wall. Is GG effective if the materials aren't both drywall? Can you sandwich GG between quietrock and 3/4" wood (VGDF)? Also, Is there an acoustic caulk I can use to seal against the floor?

Thanks, guys. I also have a dedicated HT. Just didn't want y'all to think I was deprived.


----------



## erkq

I've got a question about using Green Glue is a residential (non-theater) application. We had Quietrock put in to separate a section of our home when remodeling. The baseboard hasn't been put back yet and sound comes through where the wall meets the floor. I was wondering if Green Glue could be used to secure the baseboard to the wall. Is GG effective if the materials aren't both drywall? Can you sandwich GG between quietrock and 3/4" wood (VGDF)? 

Can you use GG as an acoustic caulk? The GG joint would be lateral to the sound travel. Specifically, if I attempted to seal the baseboard to the floor with a bead of GG, would that be effective? The sandwich would then be between the bottom of the baseboard and the floor... 90 degrees to the usual orientation. If GG is not good in that situation, is there an acoustic caulk I can use to seal the baseboard against the floor?

Thanks, guys. I also have a dedicated HT. Just didn't want y'all to think I was deprived.


----------



## BasementBob

erkq said:


> I was wondering if Green Glue could be used to secure the baseboard to the wall.


No.
Usually one uses finishing nails, covered with white caulk, then painted.




erkq said:


> Is GG effective if the materials aren't both drywall?


Yes.




erkq said:


> Can you sandwich GG between quietrock and 3/4" wood (VGDF)?


Yes.



erkq said:


> Can you use GG as an acoustic caulk?


No.




erkq said:


> is there an acoustic caulk I can use to seal the baseboard against the floor?


Yes. 
Although it's the wall that should be sealed to the floor, rather than the baseboard. The baseboard is more cosmetic.


----------



## erkq

BasementBob said:


> No.
> Usually one uses finishing nails, covered with white caulk, then painted.
> 
> 
> 
> Yes.
> 
> 
> 
> Yes.
> 
> 
> No.
> 
> 
> 
> Yes.
> Although it's the wall that should be sealed to the floor, rather than the baseboard. The baseboard is more cosmetic.


I left your whole response because I like it! Thanks.

I ordered GG sealant. I hope to squirt it into the gaps between the wall and floor and then cover with baseboard. It's all I can do since this was a retrofit and the floor is continuous.

It's interesting to generate white noise on one side and take an SPL meter to the other. You can pass it over the wall and clearly see your problem spots. It lead me to the wall/floor joints.


----------



## granroth

BasementBob said:


> DIY experiment thought
> On last week's Mythbusters, they were lifting up cars with a vacuum.
> In the boxes they finally made, they made a mold affixed to the box for a rubber seal, and poured liquid rubber into it, and the next day removed the mold leaving a large rubber seal that obviously was incredibly sealed to the box.
> I wonder if the same could be done with door seals, and if that would be better than say the GM Trunk seals.


Interesting thought. Close the door, leaving a gap between it and the jamb. Put a mold around that gap, sealing it (mostly) in. Pour in the liquid rubber in the one place that's left open. Seal that spot. Wait for it to dry. Remove the mold. The end result might be a rubber seal that _perfectly_ fits the door.

Cost effective?

Maybe roofing rubber would work? Here is some for $72 a gallon: http://www.epdmcoatings.com/epdm-liquid-rubber-white-1-gallon.php

That covers 42 sq ft at 20mil thickness, or 120 cu inches.

A typical seal going around both sides and top of door would be maybe 1/2" x 1/2" by 190" long. That's just under 48 cu in of needed material. Add in a bottom stop and it's still only around 55 cu in, so even a half-gallon would be enough. A full gallon could do two communicating doors.

I'm not actually sure where you can even buy GM type k trunk seals anymore. It's historically gone for around a $1 a foot, though, and in 50 ft increments. So $50 < $72.

I sealed my door with regular exterior door weatherstripping (the one with the kerf) and that ran me roughly $15 for the dor.

So no, it's not going to be as cheap to use the liquid rubber, but you likely don't get as good of a seal with the pre-made products either.

Hrm. Definitely an interesting thought experiment.


----------



## jrref

erkq said:


> I've got a question about using Green Glue is a residential (non-theater) application. We had Quietrock put in to separate a section of our home when remodeling. The baseboard hasn't been put back yet and sound comes through where the wall meets the floor. I was wondering if Green Glue could be used to secure the baseboard to the wall. Is GG effective if the materials aren't both drywall? Can you sandwich GG between quietrock and 3/4" wood (VGDF)?
> 
> Can you use GG as an acoustic caulk? The GG joint would be lateral to the sound travel. Specifically, if I attempted to seal the baseboard to the floor with a bead of GG, would that be effective? The sandwich would then be between the bottom of the baseboard and the floor... 90 degrees to the usual orientation. If GG is not good in that situation, is there an acoustic caulk I can use to seal the baseboard against the floor?
> 
> Thanks, guys. I also have a dedicated HT. Just didn't want y'all to think I was deprived.


According to the Quietrock instructions, you are supposed to use Quietseal, around the perimeter of the Quietrock when you install it. I also then ran a bead of Quietseal along the seam between the floor and the bottom of the Quietrock then nailed the baseboard in. I guess GG sealant is similar to Quietseal and probably will work just fine.


----------



## HT Geek

*Yes, yes you can!*



erkq said:


> I've got a question about using Green Glue is a residential (non-theater) application. We had Quietrock put in to separate a section of our home when remodeling. The baseboard hasn't been put back yet and sound comes through where the wall meets the floor. I was wondering if Green Glue could be used to secure the baseboard to the wall.


Yes.

Green Glue is not an adhesive (i.e. you still need to nail it). You could use it between the baseboard and wall, but I'm not sure it would benefit you enough to make it worthwhile. 

First, hopefully you understand a little about what QuietRock is. It is 2 layers of 1/2" drywall with a viscoelastic material sandwiched in between. The product is assembled like this in the factory. It is allowed to cure (dry) and then shipped to various stores as a pre-assembled damped drywall product. So, although it does not utilize Green Glue, it is using a similar product. 

Now, to your concern.... First you need to determine (or estimate) why is the sound coming from that area? For instance, it's quite possible you are hearing flanking noise via the floor/floor joists. If that is the case then treating the area between the baseboard and wall is unlikely to help much - though it could help some.

it certainly would not hurt to use GG in the manner you've prescribed though. There's just the cost and time associated. As an intermediary step, I would suggest caulking where your QuietRock meets the floor or sub-floor with an acoustical caulk (GG is not a caulk). If the sound is coming from that area and slipping underneath the QueitRock, you should see an improvement with that step, before installing baseboard.

The more details you're able to provide about your circumstances, the more targeted responses you'll receive. For example, what floor of your home is this room on? Are there other living areas above, below, or beside it? What is the floor or sub-floor in the room? Is the floor finished? What other details might impact how sound travels into or out of this room?




> Is GG effective if the materials aren't both drywall? Can you sandwich GG between quietrock and 3/4" wood (VGDF)?


Yes and Yes.



> Can you use GG as an acoustic caulk?


Sort of but not recommended. It's more of a damping compound. If you are going to seal edges for example, I'd recommend using an acoustical caulk such as Green Glue Noiseproofing Compound (there are others you could use; e.g. Grabber makes a sound + smoke sealant that is cheap and works well).



> The GG joint would be lateral to the sound travel. Specifically, if I attempted to seal the baseboard to the floor with a bead of GG, would that be effective?


Sound bounces around, so while the source may be emanating from a direction that is lateral to your wall, that doesn't mean the sound is entering your room only laterally. That said, as stated above it will likely help; it just might not help much. You need to figure out how the unwanted sound is getting into your space. Sometimes, this requires trial and error. So, you may want to take the steps you've described but be prepared for disappointing results if the main source is flanking noise coming from elsewhere. Won't hurt though. Think of it as if you were trying to locate and plug multiple water leaks in your home. It takes time, investigation, and trial & error to sort it all out.




> The sandwich would then be between the bottom of the baseboard and the floor... 90 degrees to the usual orientation.


As long as you are making some sort of 'sandwich', use GG. If you're sealing edges such as floor plate to sub-floor, drywall edge, etc., use an acoustical caulk and not GG.



> If GG is not good in that situation, is there an acoustic caulk I can use to seal the baseboard against the floor?


See comments above. Use acoustical caulk.


----------



## erkq

jrref said:


> According to the Quietrock instructions, you are supposed to use Quietseal, around the perimeter of the Quietrock when you install it.
> ...





HT Geek said:


> Yes.
> 
> Green Glue is not an adhesive (i.e. you still need to nail it). You could use it between the baseboard and wall, but I'm not sure it would benefit you enough to make it worthwhile.
> ...


Terrific information, guys. I have some Quietseal on order.

I also have a sound meter and a white noise generator to track down the failure points. It's surprisingly effective!


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## lovingdvd

In a dedicated theather room I'm building I have decoupled the foundation walls and am going to use one layers of 5/8" OSB, green glue and one layer of 5/8" dry wall. For the ceiling I am using clips and channels with 5/8" OSB, GG and 5/8" dry wall. Although I frequently hear that people do the ceiling layer and the wall layer intertwined, I am planning to do the walls first, then put the ceiling inside the wall edge, and then caulk the small gap with acoustical seal. Has anyone done this and can it be just as effective as intertwining the wall and ceiling layers?


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## HT Geek

jrref said:


> According to the Quietrock instructions, you are supposed to use Quietseal, around the perimeter of the Quietrock when you install it. I also then ran a bead of Quietseal along the seam between the floor and the bottom of the Quietrock then nailed the baseboard in. I guess GG sealant is similar to Quietseal and probably will work just fine.


Yes, as in the diagram BasementBob mentioned.

QuietSeal, Grabber Smoke & Sound Sealant, Green Glue Sealant.... they are all similar. They perform the same function. 

Just be cautioned that it might not solve the problem to your satisfaction. If the root cause is flanking sound, it won't eliminate it. Still, it won't hurt either and may at least reduce the intensity of the sound.


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## HT Geek

lovingdvd said:


> ... can it be just as effective as intertwining the wall and ceiling layers?


The benefit of 'intertwining' as you put it, is largely to provide another layer of redundancy with respect to sound proofing and plugging any holes. 

Is your HT-room-to-be in the basement, 2nd floor, etc.??


----------



## kmhvball

lovingdvd said:


> I am planning to do the walls first, then put the ceiling inside the wall edge, and then caulk the small gap with acoustical seal. Has anyone done this and can it be just as effective as intertwining the wall and ceiling layers?


I don't know all the rationale, but in a 'normal drywall' situation, Drywallers hang the Ceiling first. I believe this is largely to a) help manage any gaps from walls that aren't perfectly straight, to enable finishing the seems a bit easier, and b) provide some extra support to the horizontal/drywall ceiling boards - as they then 'rest' on the vertical boards. I think if a board needs shaved a little to fit, and that is hidden by the vertical board, then it isn't as challenging to make look nice.

In terms of sound proofing, I would think the intertwined approach might be slightly better, as then there is solid mass that sound has to get through vs having only to get through acoustic sealant. If it is intertwined (either vertical, then horizontal, or horizontal then vertical), there are solid pieces of drywall that sound has to get through. I can't imagine it is all that big of a difference, but I would think at least a little less effective. This is simply my 'mind' thinking of logic vs anything I have read/seen, so, I could certainly be incorrect.


----------



## HT Geek

kmhvball said:


> I don't know all the rationale, but in a 'normal drywall' situation, Drywallers hang the Ceiling first. I believe this is largely to a) help manage any gaps from walls that aren't perfectly straight, to enable finishing the seems a bit easier, and b) provide some extra support to the horizontal/drywall ceiling boards - as they then 'rest' on the vertical boards. I think if a board needs shaved a little to fit, and that is hidden by the vertical board, then it isn't as challenging to make look nice.


Good points. Though, I'm thinking with multiple layers the order of installation should matter less (or not at all) provided those layers are alternated (i.e. ceiling - wall - ceiling - wall OR wall - ceiling - wall ceiling). To your other point, that alternation of layers is presumably what provides assurance that you're not relying on the caulk to stop sound penetration along the edges.


----------



## dtalamo

*Green Glue Tape & Mud 1st Drywall layer Question*

Would it hurt or help if I tape & mudd the first layer of drywall seams before applying Green Glue to the second layer of drywall? (I know its extra work but I already paid drywaller for tape & mudding the first layer of DW)

Thanks in advance!


----------



## HT Geek

dtalamo said:


> Would it hurt or help if I tape & mudd the first layer of drywall seams before applying Green Glue to the second layer of drywall?


No. In fact, you should do that; though you can skip the tape. 

Using acoustical caulk instead of mud would be even better, but not required/necessary.


----------



## bigathetank

Hi all, I have read a lot about what I should be doing in order to 'soundproof' as much as I can in my home theater room. It is new construction in the basement with the walls already built and is directly below the living room and 1st floor master (hence the reason for soundproofing as I need to dull the sound as much as possible so the 2 AM movies don't wake the wifey). With that said I am going to focus on the ceiling above. My plan at the moment is to double 5/8" drywall w/ Green Glue in between the joists adding mass to the sub-floor above (carpeted upstairs) as well as R-25 unfaced insulation in the joists. From there I would like to double 5/8" drywall w/ Green Glue with an optimistic hope of decoupling with clips and channels as well. My area I want to do this to has a nice 1" copper cold water pipe about 2 foot into the area I am working in. I hate to have someone come in and move the hot and cold water supply over 2 foot into where the metal I beam and waste pipe already are...So, the way that I see it is I would be able to do the double 5/8" drywall w/Green Glue along with the clip and channel method but that will most likely leave me with only one layer of drywall over that 1" copper pipe. That will be, what I see as my weakest link and "problem" area. Could I dampen above that area more to help compensate, seriously consider moving the existing hot/cold pipes, or any other suggestions you might have. I really don't want to do a bulkhead all the way out there as I think it will look pretty stupid. Please see attached my schematic for the area in question. One square = one foot and the color coding I just added for this dilemma are in the bottom right. I can also take pictures of the basement in that area and annotate them a bit if that helps as well.

Thanks so much in advance!

--Aaron


----------



## leadliner

bigathetank said:


> Hi all, I have read a lot about what I should be doing in order to 'soundproof' as much as I can in my home theater room. It is new construction in the basement with the walls already built and is directly below the living room and 1st floor master (hence the reason for soundproofing as I need to dull the sound as much as possible so the 2 AM movies don't wake the wifey). With that said I am going to focus on the ceiling above. My plan at the moment is to double 5/8" drywall w/ Green Glue in between the joists adding mass to the sub-floor above (carpeted upstairs). From there I would like to double 5/8" drywall w/ Green Glue with an optimistic hope of decoupling with clips and channels as well. My area I want to do this to has a nice 1" copper cold water pipe about 2 foot into the area I am working in. I hate to have someone come in and move the hot and cold water supply over 2 foot into where the metal I beam and waste pipe already are...So, the way that I see it is I would be able to do the double 5/8" drywall w/Green Glue along with the clip and channel method but that will most likely leave me with only one layer of drywall over that 1" copper pipe. That will be, what I see as my weakest link and "problem" area. Could I dampen above that area more to help compensate, seriously consider moving the existing hot/cold pipes, or any other suggestions you might have. I really don't want to do a bulkhead all the way out there as I think it will look pretty stupid. Please see attached my schematic for the area in question. One square = one foot and the color coding I just added for this dilemma are in the bottom right. I can also take pictures of the basement in that area and annotate them a bit if that helps as well.
> 
> Thanks so much in advance!
> 
> --Aaron


im building a theater room for a customer we are putting r-23 safe n sound in the joist bays, and using resilmount clips 3.65 ea i bought 200 of them. and 25 gauge hat track.with 1/2'' quiet rock. i would move the pipe and consider the quiet rock,imo only.


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## HT Geek

bigathetank said:


> My plan at the moment is to double 5/8" drywall w/ Green Glue in between the joists adding mass to the sub-floor above (carpeted upstairs). From there I would like to double 5/8" drywall w/ Green Glue with an optimistic hope of decoupling with clips and channels as well.


Aaron,

Why is that 'optimistic'? Sounds like a good plan so far.




> My area I want to do this to has a nice 1" copper cold water pipe about 2 foot into the area I am working in. I hate to have someone come in and move the hot and cold water supply over 2 foot into where the metal I beam and waste pipe already are...So, the way that I see it is I would be able to do the double 5/8" drywall w/Green Glue along with the clip and channel method but that will most likely leave me with only one layer of drywall over that 1" copper pipe.


If you use clips & channel then - depending on which model you use of course - you should be pushing the drywall layers ~1 5/8" or so off the joists. That ought to clear your pipe nicely. Can't you simply make a cut-out if necessary for your pipe (in the hat channel)? Is your pipe parallel to the ceiling joists?


----------



## bigathetank

leadliner said:


> im building a theater room for a customer we are putting r-23 safe n sound in the joist bays, and using resilmount clips 3.65 ea i bought 200 of them. and 25 gauge hat track.with 1/2'' quiet rock. i would move the pipe and consider the quiet rock,imo only.


I am also putting R-25 unfaced in the ceiling joists, I have no idea why I failed to mention that in the original post (will edit it now). I haven't gotten as far as quantity needed yet but that is a big area to cover. Thanks for the suggestions!

--Aaron


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## bigathetank

HT Geek said:


> Aaron,
> 
> Why is that 'optimistic'? Sounds like a good plan so far.
> 
> I wasn't sure about the decoupling part and if it would be all for not with just one layer of drywall below the pipe if I leave it there as is. (My thinking prior to your 2nd comment)
> 
> 
> If you use clips & channel then - depending on which model you use of course - you should be pushing the drywall layers ~1 5/8" or so off the joists. That ought to clear your pipe nicely. Can't you simply make a cut-out if necessary for your pipe (in the hat channel)? Is your pipe parallel to the ceiling joists?


So with the clips and hat channel, my initial drywall layer wouldn't interfere with the pipe and looks like I should go with the the IB-2 Sound Isolation clip with a 7/8" 25 gauge channel. I initially didn't think I would get that much distance out of the system. My pipe runs perpendicular to the joists so that works well for having solid runs throughout. That pipe is being held by shark bite hangers which adds additional distance greater than the 1 5/8". I just double checked and there is enough play in the pipe that moving it up that 3/8" or so will get me under the 1 5/8" clearance I need from the joist. Was thinking of using the 3/4" Polypropene hanger strap on each joist with some nominal 'padding' between the joist and the pipe to get my desired clearance. Any flaw in using that or should I go with the copper Milford Strap for durability?


----------



## HT Geek

bigathetank said:


> So with the clips and hat channel, my initial drywall layer wouldn't interfere with the pipe and looks like I should go with the the IB-2 Sound Isolation clip with a 7/8" 25 gauge channel. I initially didn't think I would get that much distance out of the system. My pipe runs perpendicular to the joists so that works well for having solid runs throughout. That pipe is being held by shark bite hangers which adds additional distance greater than the 1 5/8". I just double checked and there is enough play in the pipe that moving it up that 3/8" or so will get me under the 1 5/8" clearance I need from the joist. Was thinking of using the 3/4" Polypropene hanger strap on each joist with some nominal 'padding' between the joist and the pipe to get my desired clearance. Any flaw in using that or should I go with the copper Milford Strap for durability?


IB-2 clips are rated for both 7/8" and 1 1/2" furring channel. Although I believe virtually all AVS members who have used clips are using 7/8" channel, the main reason for that is to reduce ceiling height by the minimum necessary. In your case, you could use the 1 1/2" tall channel. Just remember to adjust your screw length accordingly (i.e. add 5/8" to recommended screw lengths for screws that will go into the hat channel/furring strips).

If you don't go with taller hat channel/furring channel.... I cannot comment on the use of polypropylene straps from experience, but I have used metal straps. Considering the vibrations inherent in a HT room, I'd suggest using metal clips because they are stronger but it may not matter.

It seems to me that either concept ought to work for you.


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## jcr159

HT Geek said:


> Considering the vibrations inherent in a HT room, I'd suggest using metal clips because they are stronger but it may not matter.



I'd second the metal straps comment... Not for the HT vibration factor, but more from a water hammer/pipe knocking perspective... I have an irrigation system, and washer that can generate a ton of vibration in the pipes when the valves close... Sometimes you don't hear it, but can still feel it in the pipes when fixtures open and close. 

Might not be an issue, but you never know when you might get some water hammer. 

just my .02...


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## Evoal83

So much great reading to do! So many ideas now!


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## bigathetank

HT Geek said:


> IB-2 clips are rated for both 7/8" and 1 1/2" furring channel. Although I believe virtually all AVS members who have used clips are using 7/8" channel, the main reason for that is to reduce ceiling height by the minimum necessary. In your case, you could use the 1 1/2" tall channel. Just remember to adjust your screw length accordingly (i.e. add 5/8" to recommended screw lengths for screws that will go into the hat channel/furring strips).
> 
> If you don't go with taller hat channel/furring channel.... I cannot comment on the use of polypropylene straps from experience, but I have used metal straps. Considering the vibrations inherent in a HT room, I'd suggest using metal clips because they are stronger but it may not matter.
> 
> It seems to me that either concept ought to work for you.



Sorry for the delayed response, been down and out with the flu. I do plan on using the 7/8" hat channel, are the metal clips you mention for reducing my copper pipe clearance like these? When you say metal straps I am confused as a contractor I spoke with told me to only use plastic so things don't corrode over time. I am wondering if that will still occur using copper straps associated with that link? I am also going to put some can lights in the area, wife insists, and will use BIG's construction from Page 8 of this thread to help buffer sound from those can lights.


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## HT Geek

bigathetank said:


> When you say metal straps I am confused as a contractor I spoke with told me to only use plastic so things don't corrode over time. I am wondering if that will still occur using copper straps associated with that link?


Well, here's the issue: you can bolt down metal clamps more securely without worry of snapping the plastic. Metal will bend before it breaks. Plastic, not so much (the bending is a fraction of what metal will bend). So you can torque those puppies down if it's metal, to ensure you don't get vibrations or other issues rocking it out over time.

Now - mind you - you don't want to over-torque anything. I'm just saying metal is more durable than plastic. Fact.

Regarding copper; I'd say use the cheapest metal strapping you can find that gets the job done. Copper is a soft metal. Of course, it will patina over time when exposed to moisture or humidity but you won't care about that and it's just cosmetic.

I do not understand your contractor's concern about corrosion. This isn't going to be in a humid or wet environment, right? The only thing I can think of that he/she may be thinking of is if you have a hot water pipe where you can get "sweat" around the pipe due to the temperature and humidity difference between the water inside the pipe vs. outside, though that would only be an issue if another surface was contacting the pipe's exterior very closely. BTW, plastic will also degrade over time (it becomes weaker), though not so much unless exposed to UV radiation (e.g. sunlight) or heat.

My vote is metal clamps. Use stainless steel if you're truly concerned with potential corrosion and longevity, though IMHO if you are worried about corrosion then you have bigger fish to fry! LOL. 

David


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## bombertodd

My room is 27x18.5x9. City inspectors said I have to outlets every 6 feet all the way around the room (no exceptions). This means I'll have 14 outlets. I was going to install DD and GG, I'm wondering how can prevent all the sound leakage with this many outlets?

How well do the putty pads on the back of the electrical boxes work?


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## ronny31

Every bloody 6 feet? Do the city inspectors own shares in an outlet-manufacturing plant or something? That can't possibly be the building code.


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## kmhvball

Around here, the code is each spot on the wall, has to be within 6 feet of an outlet... so conceptually can be spaced 12 foot apart... 

I did mine inside columns, so, only stubbed the wire out, filling the hole with acoustic caulk, and then surface mounted an electric box.


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## Waterboy77

bigathetank said:


> When you say metal straps I am confused as a contractor I spoke with told me to only use plastic so things don't corrode over time. I am wondering if that will still occur using copper straps associated with that link?


The use of dissimilar metals is known as Galvanic corrosion and should be avoided


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## HT Geek

Waterboy77 said:


> The use of dissimilar metals is known as Galvanic corrosion and should be avoided


True for metal on metal, but it also depends on what the materials are. Is the pipe metal? I must have missed that (or forgot). If so, Waterboy is correct in the sense you need to consider what the materials are made of (pipe vs. clamp). So, for example you would need to know if the clamp were copper, zinc, steel, etc. Same with the pipe. At least rough guess it.

Bigathetank, this is prolly all getting way more detailed than you need to worry about for your pipe, though all the response are poignant! Let us know what you decide to do.


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## bombertodd

ronny31 said:


> Every bloody 6 feet? Do the city inspectors own shares in an outlet-manufacturing plant or something? That can't possibly be the building code.


Yes every 6 feet. No space on the wall can be more than 3 feet from an outlet. New code in effect January 2016. Not too happy. 





kmhvball said:


> Around here, the code is each spot on the wall, has to be within 6 feet of an outlet... so conceptually can be spaced 12 foot apart...
> 
> I did mine inside columns, so, only stubbed the wire out, filling the hole with acoustic caulk, and then surface mounted an electric box.


I am thinking about having 2 or 3 openings for conduit. Then run conduit around the room and hide them with acoustic panels. Has anyone done or seen this?


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## HT Geek

bombertodd said:


> Yes every 6 feet. No space on the wall can be more than 3 feet from an outlet. New code in effect January 2016. Not too happy.


Blame Apple. And Xmas lighting.


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## HT Geek

bombertodd said:


> I am thinking about having 2 or 3 openings for conduit. Then run conduit around the room and hide them with acoustic panels. Has anyone done or seen this?


Yes, but what do you mean by, "openings" and "conduit?"

Just make sure you follow NEC guidelines (i.e., ICC International Residential Code Electrical Provisions; aka National Electrical Code or NEC) with regards to how you route wiring and secure the outlets themselves.

I'm not sure if there is any code prohibiting covering the outlets, but I am sure no inspector will visit your home looking for that by the time you have those panels up.


----------



## bombertodd

HT Geek said:


> Yes, but what do you mean by, "openings" and "conduit?"
> 
> Just make sure you follow NEC guidelines (i.e., ICC International Residential Code Electrical Provisions; aka National Electrical Code or NEC) with regards to how you route wiring and secure the outlets themselves.
> 
> I'm not sure if there is any code prohibiting covering the outlets, but I am sure no inspector will visit your home looking for that by the time you have those panels up.



I'll make an opening roughly an 1/8" bigger diameter than the conduit, and seal it with noiseproof sealant. From there I would run conduit to each electrical outlet like you might see in cinder block building or garage (surface mounting). It would look something like this but using PVC conduit instead:http://cdn.protoolreviews.com/wp-content/uploads/2015/11/electrical-wiring-quad-bend-770x472.jpg


I assume running conduit through the drywall in 3 locations would be much better than trying to seal 14 electrical boxes with puddy pads.


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## HT Geek

bombertodd said:


> I'll make an opening roughly an 1/8" bigger diameter than the conduit, and seal it with noiseproof sealant. From there I would run conduit to each electrical outlet like you might see in cinder block building or garage (surface mounting). It would look something like this but using PVC conduit instead:http://cdn.protoolreviews.com/wp-content/uploads/2015/11/electrical-wiring-quad-bend-770x472.jpg
> 
> I assume running conduit through the drywall in 3 locations would be much better than trying to seal 14 electrical boxes with puddy pads.


Now I understand what you were talking about! Pictures help a great deal. 

I'm not sure what you stand to gain though. Running conduit and putty pads are two different concepts. The putty pads prevent flanking paths via your electrical boxes. Conduit is primarily used to allow you the capability of running new wires after the wall coverings are up. Sometimes people also use conduit to tidy up their wiring, or separate high voltage (120v+) from low voltage (


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## HelmedHorror

Hey, quick question. If I'm building multiple rooms from scratch and have the ability to put dampened drywall (two sheets with Green Glue in between) on *both* sides of the wall (i.e. 4 sheets altogether), should I do that? Or will that create a triple leaf effect?


----------



## granroth

HelmedHorror said:


> Hey, quick question. If I'm building multiple rooms from scratch and have the ability to put dampened drywall (two sheets with Green Glue in between) on *both* sides of the wall (i.e. 4 sheets altogether), should I do that? Or will that create a triple leaf effect?


That's actually the recommended way! Most people don't do that just because of the increased cost plus the fact that typically the theater is the only new room.

Triple leaf comes into play when you have Mass + Air + Mass + Air + Mass. Insulation counts as Air in this scenario. So if you had:

DW + GG + DW + Stud Wall with Insulation + DW + GG + DW

That's Mass + Air + Mass since each the DW+GG+DW acts as one unit of mass.

Now if you created two walls and did it like so:

DW + GG + DW + Stud Wall with insulation + DW + GG + DW + Stud Wall with insulation + DW + GG + DW

Well, that's triple leaf since now we're looking at Mass + Air + Mass + Air + Mass


----------



## CrisTUFR

*Single-clip channel runs?*

I've mocked up my room to be built down to the last existing stud, and have been planning the placement of my clips and hat channels in advance.

Most of the room is fairly straightforward, however there were some awkward spots that I found. In particular, there are a few areas that appear to only fit a single clip.



In the above image, the lone clip at the right of the window opening would have a 3" overhang of the hat channel to the right of the clip, which doesn't seem ideal/correct.



In the above image, I think only a 1-2" piece of hat channel will fit into each of those clips, tops. Plus you have the 2nd layer of drywall to worry about, with no easy way to avoid the 1st screw.



And in this final image above, you can see that I really can't put any clips on the right-hand side of the window! I may just run drywall to the window itself here, and skip on trimming it out altogether.

I would really appreciate any guidance/advice that you folks can provide for dealing with these sorts of situations.

Thanks in advance!


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## HT Geek

Since this topic can be a little confusing to many folks, I'll add to Granroth's comments a bit.



granroth said:


> Triple leaf comes into play when you have Mass + Air + Mass + Air + Mass. Insulation counts as Air in this scenario....
> 
> Now if you created two walls and did it like so:
> 
> DW + GG + DW + Stud Wall with insulation + DW + GG + DW + Stud Wall with insulation + DW + GG + DW
> 
> Well, that's triple leaf since now we're looking at Mass + Air + Mass + Air + Mass


This is why placing drywall directly over existing drywall can be problematic. This is a common question when someone wants to remodel an existing room into a dedicated and (more) sound-proofed room. At times, folks get confused about why they can't slap another layer of drywall onto an existing wall, and then put an air gap + stud wall + more drywall.

Even though the drywall and studs are attached and therefore partially act as a single mass at the points where they are directly connected, the 'leaf' effect pertains to where the air gap is between the studs and where you have the drywall. For the sake of understanding the concept, think of the drywall being suspended and as if the studs weren't there. 

Let's say you have an existing standard wood stud wall between two rooms: DW + Stud Wall + DW

If you built another stud wall attached to it, you create a triple-leaf effect - as Granroth described (DW+SW+DW+SW+DW). This can happen when someone doesn't want to demo one side of their existing drywall, and makes the mistake of building another stud wall attached to it. This creates 3 'masses' (3 walls), thus the 'triple leaf' reference. This could look like _DW + Stud Wall + DW + DW + Stud Wall + DW_ OR _DW + Stud Wall + DW + Stud Wall + DW_. It doesn't matter. Same issue (per Granroth's post... _Mass/Air/Mass/Air/Mass_).

However, if you just attached another sheet of drywall or viscoelastic glue (such as Green Glue) + drywall to either side (or both sides) of that existing wall, you're fine (that is, _DW+DW - Stud Wall - DW+DW_ is OK) because there is still only one air cavity and only 2 'leafs.'

Incidentally, this scenario still creates a triple-leaf effect: _DW + Stud Wall + DW *+ 1" Air Gap +* DW + Stud Wall + DW_

The inner walls are too close together with such a small air gap, which is not enough to separate the walls to avoid creating the effect of a solid mass in the middle leaf. If it did work, most people would not demo their existing room before putting up another stud wall. 

It works in a _DW + Stud Wall + Air Gap + Stud Wall + DW_ arrangement because there are only 2 masses at work. Each section of DW + Studs creates a single 'mass.' The purpose of the small air gap is to break the connection between the sections of mass, thereby interrupting and slowing down the transfer of sound energy between the wall masses. 

Now, when you read about sound proofing on this forum, you will read about several concepts of sound mitigation. The wall structures we're talking about should utilize two of them: mass and the air gap that helps reduce sound transmission through dis-association or disconnection of the materials that are transmitting the sound waves.

One final point. The reason for a 1" air gap recommendation is to allow for slight inconsistencies in the proximity of the inner wall to the outer wall. Most dimensional lumber is not completely straight. You could use a 1/4" gap if you could be certain all your studs were perfectly straight, perfectly level, and that the wood would not move during settlement after construction. As long as there is a gap, it doesn't matter how big it is provided you're using the methods described herein.


----------



## HT Geek

CrisTUFR said:


> I've mocked up my room to be built down to the last existing stud, and have been planning the placement of my clips and hat channels in advance.
> 
> Most of the room is fairly straightforward, however there were some awkward spots that I found. In particular, there are a few areas that appear to only fit a single clip.
> 
> 
> 
> In the above image, the lone clip at the right of the window opening would have a 3" overhang of the hat channel to the right of the clip, which doesn't seem ideal/correct.
> 
> 
> 
> In the above image, I think only a 1-2" piece of hat channel will fit into each of those clips, tops. Plus you have the 2nd layer of drywall to worry about, with no easy way to avoid the 1st screw.


I am by no means an expert on clips & channel, so hopefully someone who is will weigh in.  You might consider pinging @BIGmouthinDC on this forum. He has a lot of experience installing clip systems.

That said, my thoughts on the two images/sections above are could you simply put up both layers of wall material along the wall perpendicular to the corner, such that they cover that area? You're talking just over 1 1/4" thick if you use 2x 5/8" thick material + a viscoelastic material (e.g. Green Glue) in between. I'll bet you end up with around 1/8" gap. You could fill that gap with acoustic caulk, sand it, etc. and I bet no one will notice.

Besides, are you certain you won't accomplish that anyway given the protrusion from your studs that is created by using the clips & channel to begin with? Looking at the walls perpendicular to the window walls, when you install clip & channel on the perpendicular walls and then run your 2x layers of wall covering, where will that put the ends of your wall covering? Won't it extend more or less to covering the stud next to the window where the single clip is to begin with??? I can't tell for sure looking at your diagrams.



> And in this final image above, you can see that I really can't put any clips on the right-hand side of the window! I may just run drywall to the window itself here, and skip on trimming it out altogether.


So, what is your plan for the windows? Are you going to have windows in your room, plug them, etc.?

In the last pic, I don't see why you can't simply run the drywall on the wall perpendicular to the window wall right up to the edge as if the window was not there.

Some other thoughts - overall - it's not ideal, but consider furring strips attached to the original studs that would provide the necessary offset. You could use small pieces of 2x4 or similar material. It would of course compromise your sound proofing to some extent but since those areas are exterior walls it might not be a big deal to you... perhaps. Depends on how anal you want to be regarding sound proofing. If you have OCD tendencies like me, you might not want to do that. 

btw, are you covering those windows? If so, just run the channel across the window opening.


----------



## CrisTUFR

HT Geek said:


> That said, my thoughts on the two images/sections above are could you simply put up both layers of wall material along the wall perpendicular to the corner, such that they cover that area? You're talking just over 1 1/4" thick if you use 2x 5/8" thick material + a viscoelastic material (e.g. Green Glue) in between. I'll bet you end up with around 1/8" gap. You could fill that gap with acoustic caulk, sand it, etc. and I bet no one will notice.


The good news is that the left-hand side of that door to the bathroom is not yet framed, so I have the flexibility to leave it as you see it (a 2'6" opening) or tighten it up a further 2" to get space for a slightly less sad looking trim around the door. Still, it appears that your idea could work. I'll have to see where I end up once that opening is actually framed in.



> Besides, are you certain you won't accomplish that anyway given the protrusion from your studs that is created by using the clips & channel to begin with? Looking at the walls perpendicular to the window walls, when you install clip & channel on the perpendicular walls and then run your 2x layers of wall covering, where will that put the ends of your wall covering? Won't it extend more or less to covering the stud next to the window where the single clip is to begin with??? I can't tell for sure looking at your diagrams.


The tricky part here is that the hat channel will likely come to an end before that point in the case of the first, larger window, causing this extension to "float". I fear that the drywall installer might end up shorting out the sheetrock directly into the wood frame of the window out of habit. 

Even still, that's not a tiny chunk to just be hanging in the air, which seems like a bad idea to me. Then again, I have little experience with the practical matters here.



> So, what is your plan for the windows? Are you going to have windows in your room, plug them, etc.?


Since the _primary_ use of this space is for my office, I am hoping to maximize the natural light coming in. I'm not overly concerned with sound leaking out of the house, and will attack that issue only if it becomes a problem down the road (using removable panels, etc.) I only have neighbors on either side of me, and when I asked in the past nobody said they recall hearing instruments being played before…



> In the last pic, I don't see why you can't simply run the drywall on the wall perpendicular to the window wall right up to the edge as if the window was not there.


Yeah, it might just work out that way. I'll have to do some thinking about how it lines up in that specific spot, as my sketchup model is not yet 100% matching up with the depth of whatever clip I end up with (so we could lose/gain up to 1/4").



> Some other thoughts - overall - it's not ideal, but consider furring strips attached to the original studs that would provide the necessary offset. You could use small pieces of 2x4 or similar material. It would of course compromise your sound proofing to some extent but since those areas are exterior walls it might not be a big deal to you... perhaps. Depends on how anal you want to be regarding sound proofing. If you have OCD tendencies like me, you might not want to do that.


I want to be as anal as possible since this will be a very large expense (~535sqft of isolated space) and would not want to diminish performance due to any small oversights.

Thanks for the ideas thus far! Keep 'em comin'! 

Chris


----------



## HT Geek

CrisTUFR said:


> The good news is that the left-hand side of that door to the bathroom is not yet framed, so I have the flexibility to leave it as you see it (a 2'6" opening) or tighten it up a further 2" to get space for a slightly less sad looking trim around the door. Still, it appears that your idea could work. I'll have to see where I end up once that opening is actually framed in.


Chris,

Sounds like you are getting a good handle on the problem.

Just one more thought: consider the impact of strategically placed 2x6 studs. May or may not be useful, but be sure to examine this option if you are talking about a 2" space, since that's the diff in breadth between a 2x4 and 2x6. 

Let us know how it turns out.  

David


----------



## CrisTUFR

HT Geek said:


> Sounds like you are getting a good handle on the problem.


I'm good at *sounding* like that, huh? 



> Just one more thought: consider the impact of strategically placed 2x6 studs. May or may not be useful, but be sure to examine this option if you are talking about a 2" space, since that's the diff in breadth between a 2x4 and 2x6.


Good plan, but unfortunately (and maybe fortunately in other spots?) the majority of existing framing is already done, mostly with 2x6s. Only the 1 stud in the drawing by the bathroom door (to complete the opening) doesn't already exist. Here's a cropped, current shot of the inside of the bathroom looking out:



The sketchup model is a stud-for-stud reproduction of the existing structure for the most part, so I'm painted into a corner here, so to speak. 

Chris


----------



## BasementBob

HT Geek said:


> DW + Stud Wall + DW *+ 1 inch Air Gap +* DW + Stud Wall + DW


How do you build that? One of those innermost DW is hard to screw to the 2x4s. The quadruple leaf wall is 'fun' to build.

http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm


----------



## HT Geek

BasementBob said:


> How do you build that? One of those innermost DW is hard to screw to the 2x4s. The quadruple leaf wall is 'fun' to build.
> 
> http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm


I've never heard of anyone building one (but I have no doubt that someone, somewhere has done so). I surmise you'd need to build the inner wall in sections (outer drywall layer + studs, then move into place, secure sole plate and top plate, then attach inner layer of wall covering). That would be 'fun' indeed. The thought had not occurred to me that this would be a quadruple leaf, but I see that now.

Regardless, my point was that you don't want to do that for a HT room as it is counter-productive. 

Incidentally, I hadn't seen that page on Bob's site. Thanks for pointing it out.


----------



## HelmedHorror

Just to clarify, do I not use corner beads whatsoever if I'm decoupling a wall with clips? I instead use acoustic sealant and mud & tape that?


----------



## BasementBob

HT Geek said:


> I've never heard of anyone building one (but I have no doubt that someone, somewhere has done so).


The way they do it for the lab test, indeed for most lab tests, is to build the wall(s) separately, and then move the wall into the test gap (sort of a empty doorway) on testing day. Thus one would build {DW, studs, DW} as one wall, and {DW, studs, DW} as another wall, and on testing day move {DW, studs, DW} into the test gap and seal the edges, and then move {DW, studs, DW} of the 'another wall' also into the same test gap and seal the edges.
But in real construction, you don't usually pick up a pre-built wall and move it into place. As far as I know, that's the only way to do this -- one of those {DW, studs, DW} has to be built elsewhere and moved into place. An idiotically complicated chore, given the amazingly counterproductive soundproofing return on a dollar for a quadleaf wall.


----------



## HelmedHorror

I'm trying to justify spending nearly $2000 on furring channel & clips for my 415sqft room (1300sqft drywall) when resilient channel would cost me less than $300.

The clips are $3.50 each (the cheapest 1-piece clip the distributor had) and the furring channel is $12.55 per 12-feet.

Resilient channel, on the other hand, is only $3.51 per 12-feet.

Is the benefit of clips & furring vs resilient channel really worth a 7x the price?


----------



## granroth

HelmedHorror said:


> I'm trying to justify spending nearly $2000 on furring channel & clips for my 415sqft room (1300sqft drywall) when resilient channel would cost me less than $300.
> 
> The clips are $3.50 each (the cheapest 1-piece clip the distributor had) and the furring channel is $12.55 per 12-feet.
> 
> Resilient channel, on the other hand, is only $3.51 per 12-feet.
> 
> Is the benefit of clips & furring vs resilient channel really worth a 7x the price?


There is a notable amount of research showing the efficacy of resilient channel when installed properly, yet clips and channels dominate that market now even at a massively increased price. The reason is the "when installed properly" part. What was discovered over time is that resilient channel was very often NOT installed properly and thus had no appreciable soundproofing benefit. Clips and channels, on the other hand, are very close to foolproof (or as close as reasonably possible).

So what people found was that you could spend $300 but end up with absolutely *no* benefit from it whatsoever or spend $2000 on a solution that is essentially guaranteed to work.

Now IF you are doing it yourself and IF you know exactly what you are doing and IF you are positive that you can do it correctly, then it does seem like the resilient channel could work for you as a budget option. There are far too many "ifs" in that to ever generically recommend the resilient route, though.


----------



## HelmedHorror

granroth said:


> There is a notable amount of research showing the efficacy of resilient channel when installed properly, yet clips and channels dominate that market now even at a massively increased price. The reason is the "when installed properly" part. What was discovered over time is that resilient channel was very often NOT installed properly and thus had no appreciable soundproofing benefit. Clips and channels, on the other hand, are very close to foolproof (or as close as reasonably possible).
> 
> So what people found was that you could spend $300 but end up with absolutely *no* benefit from it whatsoever or spend $2000 on a solution that is essentially guaranteed to work.
> 
> Now IF you are doing it yourself and IF you know exactly what you are doing and IF you are positive that you can do it correctly, then it does seem like the resilient channel could work for you as a budget option. There are far too many "ifs" in that to ever generically recommend the resilient route, though.


I could only find one objective testing of the STC reduction from improperly installed resilient channel. I can't link because I have


----------



## BasementBob

Re resilient channel, vs clips (e.g PAC RSIC-1), vs double stud.

I haven't looked in a decade, but in lab tests, the rubber damped clips used to routinely outperform resilient channel. They decouple the wall surface from the structure, which building code may require to be rigidly mounted to the rest of the house. The decoupling, since it's a max-weight calculation to get them into their max spring region (mass-spring-mass), also reduces the post-install ability to hang shelves and projectors.

The problem with both resilient channel and clips is that they raised the low frequency resonance, which isn't great from a home theatre point of view. They're positively great in board rooms and commercial hotels. i.e. resilient and clips get good STC ratings.

To my mind, the best of worlds {mounting things later, total isolation including low frequency, mid-price-range before concrete} is still the double stud wall and room-in-a-room. 

Resilient or clips -- you should probably be home to watch the drywall layers being installed. Because people who don't know what they're doing short these things without even realizing what they've done. If they leave garbage in the wall that might fall on the wall or the channel, or don't use a technique that's obviously going to put the screws in the right places etc, or you're unwilling to step in and tell a crew to take drywall down and do it again, this might not be for you.

Whereas a double stud wall is just normal construction, and doesn't require you to be home to watch them install it.

Nonetheless, these are only guidelines -- whatever the accredited lab reports say, trumps.


----------



## HelmedHorror

Thanks. Also, in my location, 5/8" drywall is exactly twice the cost of 1/2" drywall. So, all else being equal, which has better sound isolation: 5/8"(x1) or 1/2"(x2)? I checked Greenglue's website's test results but I can't find an apples-to-apples comparison of double 1/2" vs. single 5/8.


----------



## BasementBob

HelmedHorror said:


> Thanks. Also, in my location, 5/8" drywall is exactly twice the cost of 1/2" drywall. So, all else being equal, which has better sound isolation: 5/8"(x1) or 1/2"(x2)? I checked Greenglue's website's test results but I can't find an apples-to-apples comparison of double 1/2" vs. single 5/8.


 
That's easy. 


Soundproofing rule of thumb: Which weighs more? Double the mass = about 6dB more isolation. Note: not all 1/2 drywall is the same density.


Cost rule of thumb: it's not just the cost of materials, but cost of installation. 5/8" drywall may be twice the cost per panel of 1/2" drywall, but if you can lift it then it's half the panels to install. If you're hiring someone that can double the installation costs.
That's why Quietrock can be cost effective. Quietrock is heavy/dense pre-viscoelastic-ed panels up to 1-3/8” thick. *QuietRock* 545 has a _*layer*_ of _*steel*_ in the panel (reducing wifi/cell, adding sheer). For fun: http://www.quietrock.com/sites/default/files/NRC-TLA-05-043.pdf which is about as much as one can do without going to concrete, or doing a Paul Woodlock.


----------



## HelmedHorror

Thanks, and yeah I intend to install them myself with a family member, not just to save on labour costs but because I don't trust an ordinary drywall crew not to mess up on a soundproofing project.

Also, another way I was wondering if I could save money is with the three concrete walls that aren't attached to any other room in the building. Here's a picture (taken before the studs were put in)



Spoiler















The floor above has other occupants, but as you can see there are two concrete walls to the outdoors and another concrete wall to the left (barely visible in the pic).

Is it safe to just put a single layer of non-decoupled drywall and then go all-out on the single wall that separates this room from the upstairs? (so, on that one wall: clips+furring with double 5/8" + GG on _both_ sides of the studs) or would that be pointless and wasteful if the other three walls aren't treated similarly?

I should probably mention that low frequency bass noise isn't a huge concern here. And I'm actually more worried about noise from the occupants upstairs bothering _me_ than I am about _my_ noise bothering _them_. I mostly use headphones anyway, and likewise the other occupants upstairs don't produce any loud bass noise either (I know because I've lived with them for years), just conversation noise and dogs barking and doing the dishes and so on. I'm just very particular about blocking those kinds of noises out.

I hope that gives a better sense of my particular goals here  Maybe I'm wayyy overestimating just how much soundproofing I need to keep out ordinary household noise from one floor above, since most of what I've read on the topic of soundproofing has been focused on loud bass-heavy home theatre setups in particular, I think.

Thanks


----------



## HT Geek

BasementBob said:


> Soundproofing rule of thumb: Which weighs more? Double the mass = about 6dB more isolation. Note: not all 1/2 drywall is the same density.


True, but the rule of thumb on drywall weight is 2.0 psf for 1/2" gypsum drywall and 2.2 psf for 5/8" gypsum drywall. So, you only gain +10% mass by using 5/8" drywall. If the mathematical gain on damping is linear (I have no idea if it is or not), you lose what? 0.6db if you use 2x 1/2" DW vs. 2x 5/8" DW? I'd say if you are hauling the DW yourself then you have to weigh (pun intended) the benefits vs. the trouble.

Understood there are some variants: QuietRock as Bob points out has various versions (some >1" thick), and you have standard Type C/X/etc. The weight also varies slightly depending on the manufacturer. But when planning, one ought to use those standard weights in one's calcs. Just don't use the "lightweight" stuff!

FWIW, QuietRock 525 is 3.1 psf @ 5/8" thick. I have not seen it for sale locally, so I can't comment on its cost vs. standard DW.



> Cost rule of thumb: it's not just the cost of materials, but cost of installation. 5/8" drywall may be twice the cost per panel of 1/2" drywall, but if you can lift it then it's half the panels to install. If you're hiring someone that can double the installation costs.
> That's why Quietrock can be cost effective. Quietrock is heavy/dense pre-viscoelastic-ed panels up to 1-3/8” thick


How is 5/8" vs. 1/2" going to result in 1/2 the panels to install? There is no guarantee the labor will be less (tho I agree it's likely the case). FWIW, where I live, materials costs are 1/2" DW ~$9/4x8 panel, 5/8" ~$10, and QR 1 3/8" w/glue sandwich ~$43 per 4x8 panel! I could buy almost 5x 1/2" panels for the same price. 

QuietRock may not be cheaper to install if you're just doing 2x normal DW panels of either thickness. OTOH, if you're paying $200 for a case of Green Glue and using 2 tubes per sheet, that raises your cost as well obviously (vs. QuietRock cost) by $33/DW sheet. If you are planning on 2 tubes GG per DW sheet + 2 sheets of 1/2" or 5/8" DW, you may find QuietRock is cheaper.

If you hire an installer for QR, make sure they've worked with it before. Aside from the extra weight, the panels are notorious for getting damaged during transport and/or installation (compared to accidental damage from non-QR panels).

From a materials perspective, there are other potential advantages to using multiple layers of drywall vs. a single layer of QuietRock, such as the fact if only one layer of QR is used for example, you have a significantly higher risk of cracks or seams allowing sound through. If you miss a spot with mud/sealant for instance, there isn't another layer on top to cover it up. When overlapping multiple layers of DW, you mitigate that risk substantially.


----------



## HT Geek

HelmedHorror said:


> Thanks. Also, in my location, 5/8" drywall is exactly twice the cost of 1/2" drywall.


Geez. Where do you live??? That's crazy. Is 5/8" required in all areas by local code?


----------



## HT Geek

BasementBob said:


> *QuietRock* 545 has a _*layer*_ of _*steel*_ in the panel (reducing wifi/cell, adding sheer).


Didn't read the PDF, but if my memory is correct, QR-545 weighs about 6.5 psf (~210 lbs. for a 4x8 panel)! Heavy is an understatement.


----------



## BasementBob

HT Geek said:


> How is 5/8 inch; vs. 1/2 inch; going to result in 1/2 the panels to install?


He wrote: 5/8"(x1) or 1/2"(x2)
The x2 means there's half the panels to install.


----------



## HelmedHorror

HT Geek said:


> Geez. Where do you live??? That's crazy. Is 5/8" required in all areas by local code?


I'm not sure. I live in Ontario like BasementBob; maybe he has some idea why 5/8" is so much more expensive? Also, the only 5/8" Home Depot has is the "UltraLight" stuff. 

Anybody have any thoughts on my last post's questions?


----------



## HT Geek

BasementBob said:


> He wrote: 5/8"(x1) or 1/2"(x2)
> The x2 means there's half the panels to install.


My bad! I either missed that part of his original post or forgot.


----------



## ragingmain

Hello Gentlemen
I will be building a staggered stud floor. the current joist are 2x10s and I will be putting 2x8s 16" on center between them. They will be raised 1" above the old joist to decouple from the ceiling below. Obviously this part is to help minimize the impact noise from above. I also plan on putting rubber matting between the underlayment and floor. 

My theater is directly below my bedroom and I am looking to minimize the transmitted noise from below. I have read just about every post and came across this from 2004 and I noticed this quote

"sound DOES NOT pass through walls. it vibrates the walls, which vibrate the air on the other side. hence it's new sound (if you want to look at it that way) on the other side of your wall, not sound that passed through."

I have an enourmous supply of mineral wool batts, heavy stuff used in power industry and the rubber matts.
Here is my dilemma. I can add lots of mass to the air cavity between the new floor and the ceiling using the wool batts. What I am concerned about is defeating the decoupling if the mineral wool is in contact with the old and new joists. I can get an unlimited supply rubber so I actually thought about wrapping each of the joists to help add mass and dampen the sound wave. I could also add mass to each of old joist just by attaching more wood to each one ensuring it doesn't touch the ceiling below.

Adding either a second layer of drywall or resilient clips/channels to the existing ceiling is not an option. The best I can get is to build the staggerd stud floor.

Please help.
Thanks in advance for any help.


----------



## HT Geek

ragingmain said:


> Hello Gentlemen
> I will be building a staggered stud floor. the current joist are 2x10s and I will be putting 2x8s 16" on center between them. They will be raised 1" above the old joist to decouple from the ceiling below.


I presume you meant the new joists will be 1" _below_ the old ones (??)



> Here is my dilemma. I can add lots of mass to the air cavity between the new floor and the ceiling using the wool batts. What I am concerned about is defeating the decoupling if the mineral wool is in contact with the old and new joists.


I can't imagine that would be an issue, provided you do not compress the insulation. Of course, mineral wool is more dense than the standard 'pink fluffy' insulation, but I don't see that being a big deal. You just don't want to squish it in there. Nearly everyone uses insulation in their walls/ceilings. You need a rigid contact to conduct sound well, such as a solid object (e.g. wood, concrete, nails, etc.).



> I can get an unlimited supply rubber so I actually thought about wrapping each of the joists to help add mass and dampen the sound wave. I could also add mass to each of old joist just by attaching more wood to each one ensuring it doesn't touch the ceiling below.


I would think you're better off applying your energy elsewhere. As long as there is an air gap to the old joists, you are good-to-go in terms of that issue. However, how are you attaching the new joists that are staggered relative to the old ones? Are you de-coupling them?


----------



## ragingmain

HT Geek said:


> I presume you meant the new joists will be 1" _below_ the old ones (??)


No. see the attached pic



HT Geek said:


> I can't imagine that would be an issue, provided you do not compress the insulation. Of course, mineral wool is more dense than the standard 'pink fluffy' insulation, but I don't see that being a big deal. You just don't want to squish it in there. Nearly everyone uses insulation in their walls/ceilings. You need a rigid contact to conduct sound well, such as a solid object (e.g. wood, concrete, nails, etc.).


Good to know. I was concerned the mineral wool could be considered rigid.



HT Geek said:


> I would think you're better off applying your energy elsewhere. As long as there is an air gap to the old joists, you are good-to-go in terms of that issue. However, how are you attaching the new joists that are staggered relative to the old ones? Are you de-coupling them?


Yes, see the pic


----------



## HT Geek

ragingmain said:


> No. see the attached pic


Hmm. Let's take a couple of steps back, 'cause I'm not visualizing the whole picture. 

Is the home theater room existing?

You mentioned working on isolating the floor above the HT room. The pic you posted does not demonstrate how the new joists that are raised above the old joists would be supported. What is going to structurally support each set of joists?

Are you proposing leaving the HT room as is and raising the floor of the room above it, by installing 2x8 joists into a cavity that currently has 2x10 joists?

If I understand some of your other statements correctly, you will also add a rubber underlayment between the finished floor and subfloor of the room above the HT room, and adding mass to the inside of the HT room ceiling is not an option. 

Is that all correct?

Are you planning to remove the existing finished floor and subfloor in the room directly above the HT room? That might sound like a dumb question, but I'm attempting to ascertain that you are indeed accessing the entire floor/ceiling cavity only via the floor of the room above the HT room, if I understand your scenario correctly.


----------



## ragingmain

HT Geek said:


> Hmm. Let's take a couple of steps back, 'cause I'm not visualizing the whole picture.
> 
> Is the home theater room existing?
> 
> You mentioned working on isolating the floor above the HT room. The pic you posted does not demonstrate how the new joists that are raised above the old joists would be supported. What is going to structurally support each set of joists?
> 
> Are you proposing leaving the HT room as is and raising the floor of the room above it, by installing 2x8 joists into a cavity that currently has 2x10 joists?
> 
> If I understand some of your other statements correctly, you will also add a rubber underlayment between the finished floor and subfloor of the room above the HT room, and adding mass to the inside of the HT room ceiling is not an option.
> 
> Is that all correct?
> 
> Are you planning to remove the existing finished floor and subfloor in the room directly above the HT room? That might sound like a dumb question, but I'm attempting to ascertain that you are indeed accessing the entire floor/ceiling cavity only via the floor of the room above the HT room, if I understand your scenario correctly.


You are absolutely correct on all points.
The existing headers will be supporting the new joists.


----------



## HT Geek

ragingmain said:


> You are absolutely correct on all points.
> The existing headers will be supporting the new joists.


Will the existing 2x10's continue to be supported by the same headers?

What prompted you to consider accessing the floor/ceiling cavity via the floor above, instead of the ceiling below? I'm guessing you figured it's easier for some reason to tear out the 2nd floor subfloor and re-do it versus the ceiling in the HT room, which might require new lower height walls to accomplish your goal.

Seems like a creative solution to me, but probably more work than most people would want! Perhaps you surmised this to be the lesser of two evils that will accomplish your goal (e.g. versus tearing out your walls and ceiling in your HT room and rebuilding the walls to a shorter height to allow a completely isolated ceiling; OR perhaps you are severely height constrained in the HT room).


----------



## HT Geek

ragingmain said:


> The existing headers will be supporting the new joists.


Have you considered removing the subfloor and installing Joist Isolators on the existing joists instead of installing new joists?

Several companies sell them. HERE is an example.


----------



## ragingmain

HT Geek said:


> Have you considered removing the subfloor and installing Joist Isolators on the existing joists instead of installing new joists?
> 
> Several companies sell them. HERE is an example.





HT Geek said:


> Will the existing 2x10's continue to be supported by the same headers?
> 
> What prompted you to consider accessing the floor/ceiling cavity via the floor above, instead of the ceiling below? I'm guessing you figured it's easier for some reason to tear out the 2nd floor subfloor and re-do it versus the ceiling in the HT room, which might require new lower height walls to accomplish your goal.
> 
> Seems like a creative solution to me, but probably more work than most people would want! Perhaps you surmised this to be the lesser of two evils that will accomplish your goal (e.g. versus tearing out your walls and ceiling in your HT room and rebuilding the walls to a shorter height to allow a completely isolated ceiling; OR perhaps you are severely height constrained in the HT room).


Due to the design of my living room I had to hang all of my speakers from the ceiling. the WAF doesnt like clutter  I also have a projector, which hangs from the ceiling. The speakers are direct coupled to my master bedroom 

We are redoing the upstairs and the floors are not level. We are tearing out the subfloor/underlayment to put down new flooring. The impact noise in our house is HORRIBLE. All the floors squeak etc etc. Instead of trying to shore up/level the existing stuff I figured I will kill two birds with one stone. Prevent impact noise and HT transmission and level/silience my upstairs flooring.

I have not considered the joist isolators. What is the STC as compared to the staggered joists? If it is comparable I will consider those. 
Thanks again for all your help


----------



## ragingmain

So I found this post from 2005 and now I am still confused about whether or not to fill the cavity

Quote:
Originally posted by JCameron
Brian,

As always you are a wealth of info...now I just need a little help to make sure my translation is correct...

Are you telling me that having a 6inch gap in the wall is better than 4? This is what I have accomplished with my staggered studs. If I do double drywall with green glue, tightly packed insulation, then double drywall with green glue...do I have a winner? I do understand your statement about the gap potentially causing an increase in the "spring effect". I just want to make sure you are not saying that my extra space in there is making matters worse.

Thanks again in advance!
extra space is two thumbs up, for the reasons bob gave

1. the stagg studs decouple
2. the extra air space (Assuming the wall is decoupled) lowers resonance, which has sort of a cascading series of positive benefits

as much air space as possible


----------



## HT Geek

ragingmain said:


> I have not considered the joist isolators. What is the STC as compared to the staggered joists? If it is comparable I will consider those.


Glad you shared your details. It helps paint the picture.

I don't recall viewing data of STC (or TL) of a staggered stud floor, nor the joist isolators for that matter. It was just an idea to save you some labor & would be better than what you have currently. If you are hell-bent on reducing TL then I'd say you're better of sticking to your plan.

I can't see how joist isolators could be equal to or better than decoupling with different joists.

If you have not done so already, I suggest reading the attached document published by NRC's Institute for Research in Construction (IRC) by A.C.C. Warnock (c) 1999. It is right on point for your need and discusses impact noise through floors.

Some other thoughts:
* Doubling your sub-floor layer will help reduce sound transmission to/from the HT room below
* Using 2x OSB or Plywood that is 1/2 thickness generally yields slightly better TL and STC; be sure to overlap your seams. For example use 2x 13mm versus 1x 25mm sheets


----------



## HT Geek

ragingmain said:


> So I found this post from 2005 and now I am still confused about whether or not to fill the cavity
> 
> Quote:
> Originally posted by JCameron
> Brian,
> 
> As always you are a wealth of info...now I just need a little help to make sure my translation is correct...
> 
> Are you telling me that having a 6inch gap in the wall is better than 4? This is what I have accomplished with my staggered studs. If I do double drywall with green glue, tightly packed insulation, then double drywall with green glue...do I have a winner? I do understand your statement about the gap potentially causing an increase in the "spring effect". I just want to make sure you are not saying that my extra space in there is making matters worse.
> 
> Thanks again in advance!
> extra space is two thumbs up, for the reasons bob gave
> 
> 1. the stagg studs decouple
> 2. the extra air space (Assuming the wall is decoupled) lowers resonance, which has sort of a cascading series of positive benefits
> 
> as much air space as possible


They're just saying a larger air gap is better than a smaller air gap (i.e. in this case 6" vs. 4"), not that insulation material should not be used in the air cavity.

Regarding insulation materials, I can tell you that it is documented in a number of lab tests that having any sort of loosely packed insulation material between wood studs _does_ reduce STC further when compared with no insulation material or open air. And as odd as it may sound, Roxul or Rock Wool qualifies as "loosely packed" provided it is not compressed. Even though it is more 'solid' than say fiberglass insulation, it is porous enough for sound to pass through. So, it essentially slows down sound transmission without being solid enough to act as a rigid object and therefore transmitter or amplifier. If you are skeptical, please see the link at the end of this post.

It is a bit of an 'apples to oranges' comparison with regards to comparing wood walls vs. wood floors, but the principles are the same. They both have wood 'beams' so to speak that when not decoupled facilitate most of the sound energy transfer from one surface to another. 

I'll try and dig up some floor lab test references for you. In the meantime, you can more easily find evidence that supports using insulation materials in walls versus not, such as these comparative lab tests for example: TL-93-089 vs. TL-93-083/087/088 [24" O.C. wood studs w/RC on 1 side]

Also, with floors it is well worth using rubber or similar materials to help dampen sound in addition to decoupling. Consider something like THIS, where you have a rubber mat as part of your subfloor. That should also help significantly with footfall noise; I'm not so sure about impact but it certainly wouldn't make it worse!

There are alternatives to Serenity Mat, and you can find substantially cheaper similar alternatives (e.g., I paid about 1/2 the price for a similar product on clearance from another source). However, based on your original comments it sounds like you could get a similar product for free or very cheap. If you have flexibility with your new floor height, please take full advantage of that fact!

Now, regarding your previous question on staggered vs. joint isolators, to be clear on that point... decoupling the joists will always be better because the joist isolators do not truly decouple, they simply damp the vibrations better than not having them.

Here is a resource relevant to insulation materials' data on sound dampening that you may find interesting: http://bobgolds.com/AbsorptionCoefficients.htm


----------



## ragingmain

Holy Crap. That is a lot of info to digest.
Thanks again for all of your help =)
I will let you know how it goes.


----------



## HelmedHorror

Anyone know what to do when installing resilient channel on ceiling trusses that are 12" apart?

Clark Dietrich says to install RC at 16" OC when trusses are 24" apart and to install RC at 24" OC when trusses are 16" apart. Nothing about 12" though. Following the pattern, though, I would guess that means I ought to install them 36" OC?

And no, I wasn't the one to put the trusses 12" apart


----------



## BasementBob

HelmedHorror said:


> Anyone know what to do when installing resilient channel on ceiling trusses that are 12" apart?
> 
> Clark Dietrich says to install RC at 16" OC when trusses are 24" apart and to install RC at 24" OC when trusses are 16" apart. Nothing about 12" though. Following the pattern, though, I would guess that means I ought to install them 36" OC?
> 
> And no, I wasn't the one to put the trusses 12" apart


 
Contact a structural engineer.
An engineered truss can be a complicated system -- and if you load it in the wrong place, or weaken a part, failure is catastrophic, sudden, and cascading. 


2x10's are joists. And the simplest for connecting channel to. The easiest way is contact the manufacturer for their instructions. Some manufacturers will do the load/placement calculations for you -- but for the most part it's linear, so if you see some weight per unit channel just maintain that ratio to stay in the mass-spring-mass effective range. 
If you're worried about the span being too weak to support the weight of drywall, consider sistering or room-in-a-room.


I-joists (aka engineered wood joist) are another kettle of fish, in between the two.


----------



## Livin

I have read a lot of threads and done a lot of searches but still not sure the best bang for the effort (not really a $ issue) for a multipurpose room so you help/experience is HIGHLY appreciated.

I'm turning my finished basement room into a multipurpose/media room and have a few issues I want to greatly reduce without tearing out all the drywall

1) Ceiling:
I don't want the mess/expense of tearing out the ceiling and I'm not modifying the walls (other than some treatments).
While in the basement, when not playing a video/music I can clearly hear sounds/voices, chairs moving across the floor, kids jumping ,etc 
We have a mix of wood, tile walkway & laundry room, and living room carpeted above. The basement ceiling is insulated with white batts of something encapsulated in perforated plastic(?)

Question:
Would I see a lot of improvement adding a layer of 5/8" drywall attached with Green Glue to the 1/2" Dryawall already on the ceiling? I don't expect silence but if I can reduce the sound by ~3x that would be great. Kids talking translates into about 40-60db in the basement, where moving chairs, jumping on the floor, etc hits up to 70-80DB.

2) Wall with Furnace:
One wall to the media room has the furnace. The wall is small (approx 4x8 w/ a 28" door) tearing out the drywall in this case is fine but if I can avoid even better. I will be replacing the door with a solid core and threshold drop to block sound from under the door escaping. Furnace is not super loud but is noticeable when watching TV/Movies (notice level is about 40db from the Furnace - with hollow core door)
The orig owners didn't insulate that wall and the furnace is only 1" away from the wall studs on facing the furnace (no drywall on the furnace side) so no easy way to access the inside of the wall, I could slip ~1" board between the wall studs and the furnace. Anything non-rigid would be a lot harder to get in.

Questions:
What is a cost effective way to reduce the sounds and slight vibration (not audible) transmitted through and into that wall?
Should I do DD/GG or QuietRock? I cannot take up more than another 1" or 2" of space into the room since it is next to the entrance door.
Other options???

3) HVAC main ducts
These run on the right side of the room - where the ceiling drops from 9' to 8'.
Only 1" between the studs and the metal duct. There is not much noise or vibration transmitted but I was thinking about adding some insulation a little for R value and a little for just ensuring I block the little sound and vibration that is there.

Questions:
What is better Roxul or Denium insulation? 
I get airflow noise on the Supply side - is there an easy way to reduce air noise from the registers?


Thanks for the help and pointers!


----------



## HT Geek

Livin said:


> I have read a lot of threads and done a lot of searches but still not sure the best bang for the effort (not really a $ issue) for a multipurpose room so you help/experience is HIGHLY appreciated.
> 
> I'm turning my finished basement room into a multipurpose/media room and have a few issues I want to greatly reduce without tearing out all the drywall


Livin,

What are your goals and what are your constraints? The more specific you can be, the more on point to your needs others' responses will be.

I'll start out by saying the end result is directly proportional to the amount of effort you put in to this project. IMHO, if you are looking for significant improvements in external sound reduction (which it sounds like you are), then if you are not willing to put in considerable effort I would suggest you don't change anything. To wit: installing a solid core door is going to be a pointless endeavor unless you also make substantial changes to other parts of the room.

Now, that said....



> 1) Ceiling:
> I don't want the mess/expense of tearing out the ceiling and I'm not modifying the walls (other than some treatments).


Personally, I don't think that's a big deal - in general - when it comes to the ceiling. Many people don't want to deal with the ceiling. You will of course get much better results by putting a concerted effort into damping it, but you can get good results (certainly better than what you have now) by adding additional layers of drywall to your existing ceiling.

Impact and flanking noises are common problems in basement HT rooms, and much of that comes through the ceiling. So, if you don't decouple it and only damp it, your results won't be as good (but they may be acceptable to you and would certainly be an improvement to your current situation).

However, with regards to your walls.... see below.



> The basement ceiling is insulated with white batts of something encapsulated in perforated plastic(?)


Sounds like insulation and the plastic is there to hold it in place. If it were along an exterior surface it would likely be a vapor barrier, but you shouldn't have a vapor barrier with an interior partition.



> Question:
> Would I see a lot of improvement adding a layer of 5/8" drywall attached with Green Glue to the 1/2" Dryawall already on the ceiling? I don't expect silence but if I can reduce the sound by ~3x that would be great. Kids talking translates into about 40-60db in the basement, where moving chairs, jumping on the floor, etc hits up to 70-80DB.


"A lot" is a subjective term. IMHO, in your case you'll see a mild improvement, but you will still hear those noises. If it were me, adding a single layer of 1/2" or 5/8" drywall + GG - under your circumstances - would not satisfy my interest in better sound proofing. Now, if you added 2 layers and installed staggered studs in the walls, you'd get a better result and if I were you, I'd probably call that good enough.



> 2) Wall with Furnace:
> One wall to the media room has the furnace. The wall is small (approx 4x8 w/ a 28" door) tearing out the drywall in this case is fine but if I can avoid even better. I will be replacing the door with a solid core and threshold drop to block sound from under the door escaping. Furnace is not super loud but is noticeable when watching TV/Movies (notice level is about 40db from the Furnace - with hollow core door)
> The orig owners didn't insulate that wall and the furnace is only 1" away from the wall studs on facing the furnace (no drywall on the furnace side) so no easy way to access the inside of the wall, I could slip ~1" board between the wall studs and the furnace. Anything non-rigid would be a lot harder to get in.


If you are averse to drywall work, why not contract it out?

If you can come up with a solid plan and pay someone to do the drywall walls and ceiling work for you, I believe you'll be much happier in the end. You'd still need to consider if you or someone else would construct clips & channel and/or staggered/double studs, etc. If you are willing to do those things yourself (and the demo of existing drywall), you can save yourself mucho $$$ in labor costs, if that is important to you.

The fact that you are in this forum and asking these questions indicates you have a strong desire to make this project happen.



> Questions:
> What is a cost effective way to reduce the sounds and slight vibration (not audible) transmitted through and into that wall?
> Should I do DD/GG or QuietRock? I cannot take up more than another 1" or 2" of space into the room since it is next to the entrance door.
> Other options???


That would help. It sounds like your best bet would be to move the furnace at least a few inches, to allow you more options in isolating its noises from your HT room. It may be worth calling a HVAC contractor and getting a free estimate. It may not be very costly, especially relative to other items and looking at it from the standpoint of sound proofing per $ spent.



> 3) HVAC main ducts
> These run on the right side of the room - where the ceiling drops from 9' to 8'.
> Only 1" between the studs and the metal duct. There is not much noise or vibration transmitted but I was thinking about adding some insulation a little for R value and a little for just ensuring I block the little sound and vibration that is there.


Are you going to build a soffit? If so, you may be able to hide or envelope that duct in the process. If not, again it's worth consulting with an HVAC contractor about options to relocate it.



> Questions:
> What is better Roxul or Denium insulation?


I suggest you search the forum for 'Roxul', 'rock wool', and 'denim insulation.' You will find a variety of opinions. There is some controversy over the use of denim insulation since it contains boron as a fire retardant. In airborne form, boron can be irritating to sensitive individuals. That said, if your interior walls are properly fire and draft stopped, that should be a non-issue once your walls are covered with drywall, etc.



> I get airflow noise on the Supply side - is there an easy way to reduce air noise from the registers?


Where is the noise coming from? Your air registers in your room? If so, it's likely due to the proximity of your room to the HVAC unit. 

You need to slow down the velocity of the air flow. There are a number of ways to do this. Again, if you search the AVS forum you'll find a number of discussions on the subject. Briefly, in your case you could use dampers (but you may still find the noise to be too loud if the velocity is very high), or you could extend the length of the run into your HT room using round, insulated flexible ducts. Or perhaps you might need a combination of the two. And again, I'd suggest consulting with a competent HVAC installer with a lot of experience. They could address all 3 of these issues and then you'd have enough information to decide if you want to tackle those concerns and if so, would you DIY or hire a pro.

That's my $0.02.


----------



## HT Geek

Livin said:


> What is better Roxul or Denium insulation?


One more thought on this subject.... Denim insulation will give you arguably the best performance in sound attenuation.

Check out Bob Gold's TL figures.

I'm attaching an Excel sheet (Excel 2007) that I put together some time ago that will make your comparison process easier. On the right side of the sheet, you'll find 15 different insulating products ranked by order of best (rank 1) to worst (rank 15) in terms of sound absorption and cost per square foot.

The top 3 products based on sound attenuation or absorption are Bonded Logic Denim and Roxul Safe'n'Sound. You really can't go wrong with any of those three.

That said, the scope of this data is a bit deceptive in the sense there is not a huge difference in appreciable attenuation (to the human ear) between the best and the worst performers. If you want really good attenuation then you will need a lot of air space and a lot of dense material. In a 3.5" thick wood stud wall, the differences (between materials) are not huge. Still, there are differences. You also need to consider the cost. Denim insulation is ~3x the cost of fiberglass 'pink fluffy,' but it does not provide 3x the sound attenuation.


----------



## HelmedHorror

Does anyone know (or can intelligently speculate) if 1/2" gypsum (40lb sheets) on resilient channel (16" o.c.) can safely mount an upper kitchen cabinet onto? (i.e. on the wall just below the ceiling.) I know RC can withstand up to three sheets of 5/8" gypsum but I haven't been able to find any info on whether it can withstand this sort of shear force (is that the right term?) especially if the cabinets are screwed into the gypsum and not the studs behind.

If not, I might have to just forgo RC on this particular wall and just use it on the other walls in my HT (it's a bachelor suite, so everything's kinda in one room.)


----------



## BasementBob

HelmedHorror said:


> Does anyone know (or can intelligently speculate) if 1/2" gypsum (40lb sheets) on resilient channel (16" o.c.) can safely mount an upper kitchen cabinet onto? (i.e. on the wall just below the ceiling.) I know RC can withstand up to three sheets of 5/8" gypsum but I haven't been able to find any info on whether it can withstand this sort of shear force (is that the right term?) especially if the cabinets are screwed into the gypsum and not the studs behind.
> 
> If not, I might have to just forgo RC on this particular wall and just use it on the other walls in my HT (it's a bachelor suite, so everything's kinda in one room.)


You could ask the manufacturer for their opinion, but
the problem isn't the cabinets but what you put into them.
The way resilient channel works is a mass-spring-mass system. There's always an optimal weight that can be hung on a spring where the spring moves most efficiently. Consider a ball point pen spring, and hang a concrete block on it -- much too heavy for such a little spring, and the spring will stretch out and not spring at all. Consider a spoon placed upon a car shocks spring -- much to light to compress the spring into its working range.
If you're hanging picture frames, or anything else of constant weight, then its just a question of doing the math to figure out how many resilient channels per vertical distance.
But with a cupboard, there's a big difference between the weight of an empty cupboard, and one that's full of dinner plates. If the cabinets were always empty, then it's just math.
And there's the dynamic load, pulling on the screws in the resilient channel, whenever its loaded or unloaded.

If the manufacturer disagrees, then fine. If the difference in weight on a single channel (cabinets are mostly hung by a single top run of screws) is 10% of the load of the drywall on a single channel, then fine. But my instinct is that if you want to put up a kitchen cabinet, then I think that's contrary to the science behind how resilient channels are meant to work, by getting the hung weight into the optimum weight range for the spring (the resilient channel) -- because the weight isn't going to be constant. Or to put the same thing another way, wherever there are going to be kitchen cabinets don't hang them on resilient channel there.


----------



## HT Geek

HelmedHorror said:


> Does anyone know (or can intelligently speculate) if 1/2" gypsum (40lb sheets) on resilient channel (16" o.c.) can safely mount an upper kitchen cabinet onto? (i.e. on the wall just below the ceiling.) I know RC can withstand up to three sheets of 5/8" gypsum but I haven't been able to find any info on whether it can withstand this sort of shear force (is that the right term?) especially if the cabinets are screwed into the gypsum and not the studs behind.
> 
> If not, I might have to just forgo RC on this particular wall and just use it on the other walls in my HT (it's a bachelor suite, so everything's kinda in one room.)


I'll add a few thoughts to Bob's great summary above.


By manufacturer, I'm presuming Bob was referring to the RC manufacturer. That is whom I'd consult with first.
If your cabinet supports attaching via more than one horizontal row of screws, you will increase the number of RC channels you can screw it into, thus increasing its stability
If the cabinet(s) will be used in the capacity of a kitchen cabinet, it's probably a bad idea to hang it on RC in general since you'll have variable weights in there that could change over time and between owners/users.
Another issue is with RC you are limited in terms of your screw length, since you do not want to pierce the channel when attaching items to the RC; in contrast, with a stud wall attachment of a cabinet you may use longer/wider screws to help support more weight
If heavy objects were placed toward the front (opening) of the cabinet, they would increase the pull-out force placed on the screws; given the fact you'd need to use shallower screws than normal (to use the RC appropriately), this would not be good

I don't believe your idea is completely out of the question. However, it would require careful planning and realistic evaluation of weights, screw sizes and lengths, screw position, etc. You should also consider the fact you are not likely to reside in that home forever, and how might a future owner use the cabinet(s)? Could you expose yourself to potential liability in the future?

IMHO, Bob's assessment is right on. You'd be better off excluding that area from the RC. If you're concerned about noise abatement there, consider alternatives such as multiple layers of drywall. Just be sure you can still attach screws of an appropriate length to hold up the cabinets (i.e. appropriate length = meeting manufacturer's minimum recommended length of screw penetration into wall studs).


----------



## Josiah88

This is an exciting time for me. I'm getting ready to finish the basement in a few weeks and am currently in the planning process. I have quite a few questions about how I should tackle this. The basement used to be a workshop. The area is 21 feet long, 11 feet wide, and 8 feet high. What I need to know is if I should worry about decoupling on the walls or if I should focus on the ceiling. The walls are made out of concrete. Is there any way I can soundproof the ceiling along with the ducts? How should I do it? I've finally decided on Roxul Safe N' Sound. Still having a hard time settling on a drywall. Do I need acoustic drywall for the walls as well? Thank you so much for taking the time to read this!


----------



## HT Geek

Josiah88 said:


> This is an exciting time for me. I'm getting ready to finish the basement in a few weeks and am currently in the planning process. I have quite a few questions about how I should tackle this. The basement used to be a workshop. The area is 21 feet long, 11 feet wide, and 8 feet high.


Is that your total basement size, or your proposed HT room size? BTW, I'm presuming you are talking about converting this area into a Home Theater room. Is that presumption correct or do you have a different goal in mind?

For a HT room, that is a very narrow space (11 feet).

Are your room dimensions uniform across the entire space? Based on your photos, I suspect they are not.



> What I need to know is if I should worry about decoupling on the walls or if I should focus on the ceiling.


Generally speaking, both. However, if that area you describe is your ENTIRE basement then obviously walls may be of lesser concern to you in theory. And that's a canned answer based on not knowing/understanding your goals. What are your goals - in terms of managing sound coming into or exiting your home theater environment?



> The walls are made out of concrete.


Even concrete will conduct sound. The more massive the concrete is, the less sound it conducts from one side to another. Unfortunately, many homes' concrete is not that massive. Relatively speaking. If you want to know exactly how much YOUR concrete wall will reduce sound transmission, you can do the math if you like.



> Is there any way I can soundproof the ceiling along with the ducts?


Yes.



> How should I do it?


Very carefully.


JK.  

You'll find many opinions on this forum, but in a nutshell think of your HT room as a cocoon. You want to isolate potentially noisy elements such as HVAC ducts from your cocoon. 

Based on your photos, I'm surmising moving those ducts is not an option, so you'll need to think of ideas to work around them. A common method is to build a soffit into your HT room plans and enclose your HVAC ducts in said soffit. Doing so gives you some options to both hide and quiet the ducts.

Lowering the ceiling to conceal the ducts is another common solution.

Unfortunately, in your case you'd be facing dual headwinds in regards to either: 1) your ceiling is relatively low starting out; and 2) your room is rather narrow (which makes the concept of a soffit more likely to appear awkward).




> I've finally decided on Roxul Safe N' Sound.


Ok. Good product, but honestly I think you are putting the cart in front of the horse based on your comments/questions. IMHO, that ought to be a low priority concern for you atm since you don't seem to have a comprehensive plan (yet). Roxul is a very good product. I almost used it myself, but in my case (as an example), 'pink fluffy' won out simply on cost alone (less than 1/2 of Roxul).



> Still having a hard time settling on a drywall. Do I need acoustic drywall for the walls as well?


I've never heard of "acoustic" drywall. Where have you heard of this? Sounds like marketing Bravo Sierra.

There are various thicknesses of drywall. Thicker = better when it comes to attenuating sound entering or leaving a home theater.

Take a step back and first consider your primary goals (e.g. watch movies at insane volumes; not disturb people next door/room above/etc., and your primary constraints (e.g. budget, room size).

What are you trying to accomplish??? Do you have a budget? If you could be clear in responding to questions above and rank your goals, that would help greatly with receiving targeted responses.


----------



## powersquad

Hi Folks,

I live in New Zealand and will start building my dream home in few months time with a dedicated cinema. I am looking at serenity mat alternative available in the country locally. I have found a product that is made out of crumb rubber. Below are it's real life photos. Can someone please tell me if this is what serenity mat looks like in person? I can't find a really close up photo of serenity mat to confirm myself.

Thanks


----------



## Josiah88

I do apologize and appreciate your response, HT Geek.  It's a very interesting house and basement to begin with. I'm rather new to the whole forum experience and hope many will forgive my lack of knowledge in that regard. This will in fact be a home theater and I do understand that it is a fairy narrow space to begin with. Unfortunately, this is the best I've got at the moment. I am trying to keep sound contained and am trying not to spend more than $2,000 - $3,000. If I need to spend more, then so be it.

My goal is to have a room that I can watch movies in without disturbing anyone above me. I have made peace with the fact that this room will not be acoustically perfect. I do understand that the imaging and soundstage will be imperfect.

You do have very good assumptions, by the way.  The only other room is where the circuit breaker is located and the water heater. The stairs and the room above are carpeted.

As for the drywall, I was thinking of something like QuietRock for the ceiling. Perhaps there is a better cost effective alternative.

You are right. I definitely need a better game plan. I admit that I'm getting a little ahead of myself.


----------



## d_c

Just want to get any pros and cons from you guys of this decision I think I have finally made. I have added dd/gg between my ceiling joists, but have decided to NOT use clips/channel/OSB/gg/dw to finish the rooms walls and ceilings. Here's why -

In the HT space:
1 - there are doorways to a bathroom, bedroom, garage
2 - an opening to the stairwell up (door at top, can't add one to the bottom) 
3 - a fireplace that will be within the room (sealing issue around the rock)
4 - HVAC within the area of the HT (another door)
5 - I can't close the room off for a single door "dedicated" space

The original plan was to follow the standard soundproofing methods for a dedicated room, but I think that there are so many areas for the sound to escape from this large room even after all these steps that it wouldn't be worth the extra money and enormous amount of extra time trying to decouple the whole space. I think it might all be done with little improvement. The Soundproofing company guy (John?) advised that there are too many obstacles from having the stairwell and other rooms alone. He advised that adding mass like I have done is probably the only thing I can do to that would have real benefit. Maybe I should follow this advice and not waste my time with it? He could sell me products but advised against, so that has worth...

Thoughts please?


----------



## HelmedHorror

BasementBob said:


> Spoiler
> 
> 
> 
> You could ask the manufacturer for their opinion, but
> the problem isn't the cabinets but what you put into them.
> The way resilient channel works is a mass-spring-mass system. There's always an optimal weight that can be hung on a spring where the spring moves most efficiently. Consider a ball point pen spring, and hang a concrete block on it -- much too heavy for such a little spring, and the spring will stretch out and not spring at all. Consider a spoon placed upon a car shocks spring -- much to light to compress the spring into its working range.
> If you're hanging picture frames, or anything else of constant weight, then its just a question of doing the math to figure out how many resilient channels per vertical distance.
> But with a cupboard, there's a big difference between the weight of an empty cupboard, and one that's full of dinner plates. If the cabinets were always empty, then it's just math.
> And there's the dynamic load, pulling on the screws in the resilient channel, whenever its loaded or unloaded.
> 
> If the manufacturer disagrees, then fine. If the difference in weight on a single channel (cabinets are mostly hung by a single top run of screws) is 10% of the load of the drywall on a single channel, then fine. But my instinct is that if you want to put up a kitchen cabinet, then I think that's contrary to the science behind how resilient channels are meant to work, by getting the hung weight into the optimum weight range for the spring (the resilient channel) -- because the weight isn't going to be constant. Or to put the same thing another way, wherever there are going to be kitchen cabinets don't hang them on resilient channel there.





HT Geek said:


> Spoiler
> 
> 
> 
> I'll add a few thoughts to Bob's great summary above.
> 
> 
> By manufacturer, I'm presuming Bob was referring to the RC manufacturer. That is whom I'd consult with first.
> If your cabinet supports attaching via more than one horizontal row of screws, you will increase the number of RC channels you can screw it into, thus increasing its stability
> If the cabinet(s) will be used in the capacity of a kitchen cabinet, it's probably a bad idea to hang it on RC in general since you'll have variable weights in there that could change over time and between owners/users.
> Another issue is with RC you are limited in terms of your screw length, since you do not want to pierce the channel when attaching items to the RC; in contrast, with a stud wall attachment of a cabinet you may use longer/wider screws to help support more weight
> If heavy objects were placed toward the front (opening) of the cabinet, they would increase the pull-out force placed on the screws; given the fact you'd need to use shallower screws than normal (to use the RC appropriately), this would not be good
> 
> I don't believe your idea is completely out of the question. However, it would require careful planning and realistic evaluation of weights, screw sizes and lengths, screw position, etc. You should also consider the fact you are not likely to reside in that home forever, and how might a future owner use the cabinet(s)? Could you expose yourself to potential liability in the future?
> 
> IMHO, Bob's assessment is right on. You'd be better off excluding that area from the RC. If you're concerned about noise abatement there, consider alternatives such as multiple layers of drywall. Just be sure you can still attach screws of an appropriate length to hold up the cabinets (i.e. appropriate length = meeting manufacturer's minimum recommended length of screw penetration into wall studs).


Would it be safe to screw the cabinets to the stud instead of the RC? I realize that would mostly short-circuit the acoustic resilience of the wall, but the alternative would be not putting RC anyway...


----------



## powersquad

Any one that has seen serenity mat in person please comment on below links post?

http://www.avsforum.com/forum/19-de...ndproofing-master-thread-49.html#post42400769


----------



## steveurban

*Some questions*

had to hire


----------



## HT Geek

powersquad said:


> Hi Folks,
> 
> I live in New Zealand and will start building my dream home in few months time with a dedicated cinema. I am looking at serenity mat alternative available in the country locally. I have found a product that is made out of crumb rubber. Below are it's real life photos. Can someone please tell me if this is what serenity mat looks like in person? I can't find a really close up photo of serenity mat to confirm myself.


AFAIK, the key is to use a rubber-type of product. All similar products I've seen contain recycled rubber, but I doubt it matters if it's recycled or not. I believe the point is that rubber serves well for what you are trying to accomplish. I wouldn't sweat it too much. Look for a product that is 3/8" (9.5mm), 1/2" (12.5mm), or thicker.








Photo of Serenity Mat from the Sound Proofing Company's website.








Photo of product very similar to what I used.

There's not a huge difference in outward appearance between them. They are both manufactured from recycled rubber. The version I purchased was cheaper (1/2), which is why I bought it. YMMV.


----------



## HT Geek

Josiah88 said:


> I do apologize and appreciate your response, HT Geek.  It's a very interesting house and basement to begin with. I'm rather new to the whole forum experience and hope many will forgive my lack of knowledge in that regard. This will in fact be a home theater and I do understand that it is a fairy narrow space to begin with. Unfortunately, this is the best I've got at the moment. I am trying to keep sound contained and am trying not to spend more than $2,000 - $3,000. If I need to spend more, then so be it.


Not trying to sound daft here, but is 2-3k your entire budget, i.e. including equipment? Or is that your budget for the room improvements?



> My goal is to have a room that I can watch movies in without disturbing anyone above me. I have made peace with the fact that this room will not be acoustically perfect. I do understand that the imaging and soundstage will be imperfect.
> 
> You do have very good assumptions, by the way.  The only other room is where the circuit breaker is located and the water heater. The stairs and the room above are carpeted.
> 
> As for the drywall, I was thinking of something like QuietRock for the ceiling. Perhaps there is a better cost effective alternative.


How tall are those HVAC ducts? That looks to be your biggest challenge atm, me thinks. 

In one of your photos there is a gray square in the lower left corner. What is that?

Is there anything in the ceiling of this room that must always be accessible from this room? I can't tell if you might have anything up there that would qualify as requiring access (i.e. you cannot cover with drywall and forget about it).

If you want to do this on the cheap (relatively speaking), I would be thinking about sound isolation from the ceiling/floor above, and how to deal with those ducts. I'd say you also would need to do a room-within-a-room by creating a double stud wall all the way around. Right now it looks like you just have block walls. The upside is it accomplishes several things at once: a) drop the ceiling to create an air gap, add insulation, and double drywall; b) run ceiling joists across your new inner stud walls to support 'a'; c) hide the HVAC ducts. The tricky part would be figuring out how to hide the HVAC ducts and still run joist across the width of the room. You would normally be ok with 2x6's for a 10' to 11' span, but you could get away with sistered 2x4's, 18" O.C. if you wanted to save 2" in height (I did the math and it works with 2x 1/2" or 5/8" drywall and no soffit - which you won't have since your ceiling is too short). Downside would be losing ~9" of room width and higher lumber cost and more time sorting lumber (at least if you pick your own boards like I did, to make sure the ones you get are straight).

You could create a soffit of sorts to hide the HVAC, but it would run your room length and be awkward. Perhaps make a few feet of the ceiling all that same lower height where you'd place your TV or screen to make it a bit less awkward. Once the lights are off/dimmed, the effect would not be as bad.

So, my thinking from what I can see in your photos... if I were you... would be to drop that ceiling down to hide the HVAC ducts. By building double-stud walls on the side that could support new ceiling joists and substituting sistered 2x4's instead of 2x6 joists, you could save a couple of inches. Unfortunately, you're still talking about 1" air gap + 3.5" tall joists + ?" HVAC duct height. That's all without considering the floor. If the main part of your ceiling would drop below 7' then technically you would be below the 7' 6" minimum ceiling height per code. However, you may be able to get an exemption from your municipality if you successfully argue that in order to make that space "habitable," this is what is required due to the presence of the HVAC ducts, and moving them would place an unreasonable burden on the homeowner when there isn't a safety issue in play. Another option would be don't get it inspected (or you may be lucky and your jurisdiction might not require it for your situation).



> You are right. I definitely need a better game plan. I admit that I'm getting a little ahead of myself.


Not at all! You're doing the smart thing by asking lots of questions.


----------



## HT Geek

d_c said:


> Just want to get any pros and cons from you guys of this decision I think I have finally made. I have added dd/gg between my ceiling joists, but have decided to NOT use clips/channel/OSB/gg/dw to finish the rooms walls and ceilings. Here's why -
> 
> In the HT space:
> 1 - there are doorways to a bathroom, bedroom, garage
> 2 - an opening to the stairwell up (door at top, can't add one to the bottom)
> 3 - a fireplace that will be within the room (sealing issue around the rock)
> 4 - HVAC within the area of the HT (another door)
> 5 - I can't close the room off for a single door "dedicated" space
> 
> The original plan was to follow the standard soundproofing methods for a dedicated room, but I think that there are so many areas for the sound to escape from this large room even after all these steps that it wouldn't be worth the extra money and enormous amount of extra time trying to decouple the whole space. I think it might all be done with little improvement. The Soundproofing company guy (John?) advised that there are too many obstacles from having the stairwell and other rooms alone. He advised that adding mass like I have done is probably the only thing I can do to that would have real benefit. Maybe I should follow this advice and not waste my time with it? He could sell me products but advised against, so that has worth...
> 
> Thoughts please?


I tend to agree with John and with your assessment. At some point, it's not worth the effort. We all have our thresholds; it sounds like you've reached yours. No argument from me. You do have a lot of headwinds, it seems.

That said, I'll offer a few suggestions in case they cross your mind in the future. None will mute a source of interference, but all would mitigate it:

Multiple points of egress: replace hollow core with solid core doors and thick gaskets around jambs
Bottom of stairwell: hang a thick, padded curtain across doorway
HT room door: Use a solid core door and damp it with drywall on HVAC room side + thick gaskets on jambs

I'm not sure if you've considered a room-within-a-room concept by using double stud walls. That in conjunction with thicker door jambs and potentially adding inner doors could also go a long way to mitigate sound leakage, if you are willing to consider that route.


----------



## HT Geek

HelmedHorror said:


> Would it be safe to screw the cabinets to the stud instead of the RC? I realize that would mostly short-circuit the acoustic resilience of the wall, but the alternative would be not putting RC anyway...


Yes. When cabinets are installed, that's how they are secured to the wall (by screwing fasteners into a stud). Actually, in some cases there is a back-plate which is screwed into the stud and the cabinets connect to the back-plate, but you get the point: the load bearing apparatus is secured into studs.

And yes, you could screw through the RC and into the studs to hang your cabinets but as you pointed out it would short-circuit your RC (though not necessarily to the point of being too detrimental, depending on how many short-circuits and your needs).

What I would suggest is this: run your RC to within 1" longitudinally along the wall relative to where you want your kitchen cabinets (i.e. leave gap between edge of cabinet and where RC begins). When you hang the drywall on your RC, leave a 1/4" gap between drywall and the cabinets (might want to install the cabinets first, then drywall on the RC). Install furring strips where the cabinets will be placed. Secure the furring strips to the studs and run the furring perpendicular to the studs (this will allow the furring strips to serve as a "back support" of sorts, so the back of your cabinets are not resting on air). Determine where your screws in the cabinets will hit the studs and make sure you have a small block of wood or another furring strip for the screws to dig into before they dig into the stud. Mount your cabinets so their back touches the furring strips and the screws still go into the studs. The trick is: 1) make sure the furring strip thickness matches the offset to your walls created by the RC and X layers of drywall next to them so the cabinets are flush in depth as you'd like; and 2) ensure you add the depth of the furring strips to your screw length for your cabinets (i.e. use longer screws to account for the furring strip depth).

If you want to get a little more fancy, allocate a portion of the furring strip depth for a rubber mat such as Serenity Mat (some kind of rubber product to help pad/deaden the vibrations a bit to/from the cabinets).

Forgive me if you already answered this question, but would the RC be installed over existing drywall?


----------



## Brymo

Hello!

During my build I had to special order some insulation. Because of the wait time I ordered a little more than I measured for to be safe. 

As things change and modify, I now have two bags of Roxul Acoustic Batts and 16 Rockboard 80 boards. 

What are some ideas and uses for my extra? I've been stuffing and laying insulation wherever I can. 

I wanted to hear your thoughts from more experienced builders. 

Thank you!


----------



## HT Geek

Brymo said:


> I now have two bags of Roxul Acoustic Batts and 16 Rockboard 80 boards.
> 
> What are some ideas and uses for my extra? I've been stuffing and laying insulation wherever I can.


What size are the batts? Are these the AFB's, Safe 'n' Sound, etc.? Did you already add fire stopping and draft stopping?

The Rockboard 80 is very dense. Bass traps, perhaps. You could attach it to the inside of your door, make fabric panels that hide it on the walls, etc. Lots of potential uses. 

I would imagine the Rockboard would make a good fabric covered absorber if you need any on your walls or ceiling. Have you performed REW (or similar testing) around your room or worked with a pro to locate problem areas and frequencies???


----------



## Brymo

HT Geek said:


> What size are the batts? Are these the AFB's, Safe 'n' Sound, etc.? Did you already add fire stopping and draft stopping?
> 
> The Rockboard 80 is very dense. Bass traps, perhaps. You could attach it to the inside of your door, make fabric panels that hide it on the walls, etc. Lots of potential uses.
> 
> I would imagine the Rockboard would make a good fabric covered absorber if you need any on your walls or ceiling. Have you performed REW (or similar testing) around your room or worked with a pro to locate problem areas and frequencies???


They are AFB I believe one bag is 80sq, so total of 160sq left over. 

I already have bass traps in the front. I made 60% of the walls are fabric covered panels of Rockboard 80. Hiding on the ceiling covered in black is my first choice. Behind the doors are a good idea. I was thinking of putting in new solid core doors. What else would I want to look for? I'm having to replace three doors as they are those cheap hallow core ones. 

I was also thinking of putting the AFB in my utility closet just because I had extra. 

Thanks for the reply!


----------



## DarkNovaNick

*Best bang-for-the-buck for ceiling?*

I'm building a new house and am thinking about doing some sort of sound-reducing on the ceilings of the bedrooms below the main level. I realize that for good soundproofing you need decoupling, however, I don't want to spend the money and time to use clips and everything as this isn't a theater, I'm just trying to reduce the sound somewhat from the room above. For walls I know that the best bang-for-the-buck is simply to double-drywall. Of course not as good as more thorough approaches, but it helps.

So for a ceiling, are there any methods that help reduce the sound somewhat without spending a lot of money? Would it be helpful to put R-19 fiberglass between the joists? Or would double-drywall on the ceiling be better? Or both? I'm having trouble finding data about ceiling noise reduction. Thanks.


----------



## JRock3x8

There are two types of roxul insulation. There is an R 23 which says comfort bat on the outside and then there is an R 16 which says safe and sound on the outside. Does the R 23 do the same soundproofing job that the R 16 does?


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## HT Geek

DarkNovaNick said:


> ... So for a ceiling, are there any methods that help reduce the sound somewhat without spending a lot of money? Would it be helpful to put R-19 fiberglass between the joists? Or would double-drywall on the ceiling be better? Or both?


Yes. In a nutshell, do both.

Now, the caveats.  

If you are trying to address a particular issue, such as impact noise (think of high heels on a hardwood floor above you), then you need to take the sound dampening in a particular direction to address a particular problem. That said, I get where (I believe) you're coming from: you want to muffle the transmission of sound between rooms as much as possible with the least amount of complexity, and apply it to your entire home. So, in that case yes your proposal makes sense. 

I'll just add to be sure not to overly compress the insulation. In general, R19 should work well between floors but not inside 2x4 walls (use R13 or R15).

You didn't mention walls, but you might also want to consider using 2x6 wall studs if that is an option. You'd need your architect to spec that in the plans. That would allow you to use thicker insulation in the walls and the deeper air cavity would also help slightly in and of itself. 




> I'm having trouble finding data about ceiling noise reduction. Thanks.


NRC-Canada probably has the most comprehensive data on the subject. It is one of very few resources with data on sound proofing floors/ceilings. I've seen a few other resources on the subject, but the names escape me atm. 

Anyhow, I've attached a paper by Warnock from 1999 (_Controlling the Transmission of Impact Sound through Floors_). It may be useful to you and is relatively short in length.


----------



## DarkNovaNick

HT Geek said:


> Yes. In a nutshell, do both.


Thank you for your helpful response. Yes, I realize that reducing impact noise (the low frequencies) requires much more intensive work in order to do well, and for these rooms I'm not going to worry too much about that as I don't want to make things overly complicated to build. For reducing other noise in general (like say voices between the floors), do you know how much of a factor insulation is compared to the double-drywall? I ask because I would view adding insulation as like level 1: cheap and easy to add, no real changes needed in how the room is built. Adding a 2nd layer of drywall is level 2: the ceiling electrical boxes need to be shifted, longer screws are needed, etc. Not really that complicated but a little bit more so. So would just adding insulation do nothing, is the double-drywall really what would cut down the noise? Or would just insulation help somewhat and double-drywall would improve things more? Thanks.


----------



## healthnut

DarkNovaNick said:


> Thank you for your helpful response. Yes, I realize that reducing impact noise (the low frequencies) requires much more intensive work in order to do well, and for these rooms I'm not going to worry too much about that as I don't want to make things overly complicated to build. For reducing other noise in general (like say voices between the floors), do you know how much of a factor insulation is compared to the double-drywall? I ask because I would view adding insulation as like level 1: cheap and easy to add, no real changes needed in how the room is built. Adding a 2nd layer of drywall is level 2: the ceiling electrical boxes need to be shifted, longer screws are needed, etc. Not really that complicated but a little bit more so. So would just adding insulation do nothing, is the double-drywall really what would cut down the noise? Or would just insulation help somewhat and double-drywall would improve things more? Thanks.



I have a similar situation as you, and have done some research. What I plan to do is fill in all joints and seams with acoustical caulk, add 3/4 MDF cut to size between the joists, and add about 4" of SafeNSound sound to the cavity. I believe this will give me the best results with the least effort.


Sent from my iPhone using Tapatalk


----------



## healthnut

I wonder if I could get some input on a home theater ceiling project. I had a dropped ceiling which I took out due to noise leakage in the ceiling above. Originally I had planned to add 5/8 drywall between the joists, but am consisting 3/4 MDF board now, which is quite a bit more expensive. Is it worth the premium? (I still plan to install double drywall with furring channel and isolation clips)


Sent from my iPhone using Tapatalk


----------



## HT Geek

DarkNovaNick said:


> ... do you know how much of a factor insulation is compared to the double-drywall? I ask because I would view adding insulation as like level 1: cheap and easy to add, no real changes needed in how the room is built.


I'll share my personal experience on this front. After I recently added the inner layer of insulation to my HT room build in-progress (double stud wall), it was remarkable how much "deader" my room sounded just doing that - with no wall coverings yet. YMMV, but after the 2nd layer (total 7" thick insulation), I could no longer hear any sound from the adjacent bedroom and reflected noises from downstairs (2nd floor theater) were diminished dramatically. And that's in a room with no wall coverings and also no door. So, personally I am sold on using [loose-fill fiberglass] insulation based on that experience alone.



> Adding a 2nd layer of drywall is level 2: the ceiling electrical boxes need to be shifted, longer screws are needed, etc. Not really that complicated but a little bit more so.


It's not as difficult as one might imagine. The easiest route - that I've found - is to use Carlon adjustable depth gang boxes. Home Depot and Lowes both sell them in single and dual gang sizes, Amazon carries 1 thru 4 gang sizes, and I'm sure you could find them at electrical supply stores as well (or your contractors could). They will run you ~$70 for a box of 16 single/double gang or abut the same $ for a box of 10 in the 3/4 gang size. Think it over and guesstimate how this would add to your home-building cost along with using 2x drywall.

Carlon makes 2 sizes of each: standard depth and deeper boxes. Make sure you get the deeper ones (e.g. 34 cu. in. versus 21 cu. in. single gang). They don't need to be adjusted until after the walls are up, which is a bonus. There are also plastic slots that can be inserted into normal gang boxes to yield a similar effect. The adjustable boxes I'm referring to have a Philips head screw on one side that pushes the box frame inward or outward. They reach out at least 2 inches, if not more, when fully extended. The only downside is cost. Make sure the installer realizes there are screw/nail holes on both the front and side of the units, so they remain in place if/when adjusted.

Carlon adjustable boxes are the most common you'll find, and are usually blue. 











Arlington makes them a bit better (note the tab on the end of the screw that ensures it stays in place - see photo), but are almost always considerably more expensive than the Carlon boxes. Arlington boxes are typically gray colored. The Arlington boxes also use thicker plastic, FWIW.











Compare Arlington (above) to the Carlton boxes (below). Comparing these 2 pics you can see the differences in material thickness and design, and why the Arlington boxes are superior. That said, they are also more $ as previously mentioned.














> So would just adding insulation do nothing, is the double-drywall really what would cut down the noise? Or would just insulation help somewhat and double-drywall would improve things more? Thanks.


Double-drywall will have a more pronounced effect, especially with regards to lower frequencies. If you use a visco-elastic compound in between (e.g. Green Glue, Quiet Glue Pro), you will notice even more significant reductions in sound at all levels. The visco-elastic compounds have a greater effect at reducing noise in the mid to high frequency ranges (versus low), though most people use them for their sound damping qualities at low frequencies (still works very well, but not as big a difference in TL (Transmission Loss) as the mid and high freqs).

Reducing low frequency transfer is mostly an effect of adding mass and decoupling. Insulation tends to have a greater impact on mid to higher frequency noises (e.g. people talking). It won't do much for you at lower frequencies, though some types (notably cotton batting and rock wool) are more effective at all frequencies vs. loose fiberglass (e.g. pink fluffy). The reason most people don't use them is cost (2.5-4x the cost of the cheapo fiberglass insulation). You are generally better off simply adding more fiberglass insulation (less cost), unless you have space constraints and are willing to pay 2.5-4x the cost for a marginal improvement. Some people are.


Food-for-thought, here's another idea for you: consider adding 1st layer of 1/2" or 5/8" OSB and then 1 layer 1/2" or 5/8" drywall over it. Doing so will allow you to tack a nail or screw nearly anywhere in your home. Check with your building inspection dept. first, but they ought to allow it. Code only requires the interior wall to by gypsum or another fire resistant material. 1/2"-5/8" OSB should cost virtually the same as 1/2-5/8" drywall in most parts of the country.


----------



## HT Geek

healthnut said:


> Is it worth the premium? (I still plan to install double drywall with furring channel and isolation clips)


I cannot say from experience, but I would think probably not given the fact sound will still travel around the joist cavities. Might be easier/faster to cut and put in place though (vs. drywall).

Why do you want to place mass in the joist cavities to begin with?


----------



## HT Geek

Brymo said:


> They are AFB I believe one bag is 80sq, so total of 160sq left over.


And what thickness?



> I was thinking of putting in new solid core doors. What else would I want to look for? I'm having to replace three doors as they are those cheap hallow core ones.


Steel doors are another option. Make sure you understand if a prospective door is truly "solid" core. At times, the door industry has some (IMHO) odd definitions of vocabulary.  Steel doors in particular may actually be hollow inside or filled with various materials. Personally, I favor the look and feel of the solid wood doors more.

You could also look at exterior doors, which are slightly thicker (and heavier) than interior doors. And don't forget how the size of jambs, etc. will be impacted by using thicker doors. 

If you have a double stud wall, it will give you some creative license with regards to how think you want to make it (presuming a single door and not a double/communicating door setup).


----------



## HT Geek

healthnut said:


> What I plan to do is fill in all joints and seams with acoustical caulk, add 3/4 MDF cut to size between the joists, and add about 4" of SafeNSound sound to the cavity. I believe this will give me the best results with the least effort.


Pls ignore my last comment above. I just saw your other post (excerpted here), which answers my question.


----------



## HT Geek

JRock3x8 said:


> There are two types of roxul insulation. There is an R 23 which says comfort bat on the outside and then there is an R 16 which says safe and sound on the outside. Does the R 23 do the same soundproofing job that the R 16 does?


I have not seen NRC specs on R-23 Roxul, but I can tell you when comparing the same R-values that Safe'n'Sound is superior to Comfort Batt with respect to attenuating sound. That doesn't answer your question directly, but point is with what we are concerned with, Safe'n'Sound is superior to Comfort Batt, when comparing identical thicknesses.


----------



## HT Geek

DarkNovaNick said:


> ... For reducing other noise in general (like say voices between the floors), do you know how much of a factor insulation is compared to the double-drywall? I ask because I would view adding insulation as like level 1: cheap and easy to add, no real changes needed in how the room is built. Adding a 2nd layer of drywall is level 2: the ceiling electrical boxes need to be shifted, longer screws are needed, etc. Not really that complicated but a little bit more so. So would just adding insulation do nothing, is the double-drywall really what would cut down the noise? Or would just insulation help somewhat and double-drywall would improve things more? Thanks.


I can't say from personal experience with regards to floor/ceiling and using insulation vs double drywall, re: voices. I can tell you it worked well for me between walls, but not until it was 7" thick.

In your shoes, I'd be inclined to do both. You could opt to do just the insulation now, and add a 2nd layer of drywall later on if warranted (but it would be a pain to add the insulation later on). If you add insulation, I'd fill as much of that space with it as you can.


----------



## Brymo

HT Geek said:


> And what thickness?
> 
> 
> 
> Steel doors are another option. Make sure you understand if a prospective door is truly "solid" core. At times, the door industry has some (IMHO) odd definitions of vocabulary.  Steel doors in particular may actually be hollow inside or filled with various materials. Personally, I favor the look and feel of the solid wood doors more.
> 
> You could also look at exterior doors, which are slightly thicker (and heavier) than interior doors. And don't forget how the size of jambs, etc. will be impacted by using thicker doors.
> 
> If you have a double stud wall, it will give you some creative license with regards to how think you want to make it (presuming a single door and not a double/communicating door setup).


AFB is 2" thick.

I went out this past weekend to look at doors. I found some 1 3/4 thick solid wood doors. Very heavy. I was leaning towards the thicker and heavier doors. They are a flat slab, no designs, but doesn't mean I couldn't create my own. 

Thank you for the reply!


----------



## lovingdvd

Is there a Roxul "Safe" product, versus the "Safe and Sound" - and if so, how is it different?


----------



## HT Geek

Brymo said:


> AFB is 2" thick.


You might consider posting in the classifieds, or on CraigsList. The AFB batts are perfect for fire stopping and draft stopping. I opted for stuffing fiberglass insulation into those crevices, simply because I had extra on-hand, but I would have preferred AFB's.

If you have the time and patience one can assemble quite a few parts for HT room construction this way. For instance, most of the Green Glue I've purchased was via CraigsList or EBay (at significant discounts).


----------



## healthnut

I'm in the process of rebuilding my home theater basement ceiling using acoustic caulk, 3/4 MDF board, hat channel and isolation clips with 2 layers of 5/8 drywall and Green Glue. Can I expect greater low bass impact in the home theater space, since it is being contained much better with these changes?


----------



## HT Geek

lovingdvd said:


> Is there a Roxul "Safe" product, versus the "Safe and Sound" - and if so, how is it different?


Not that I'm aware of. An abbreviation for Safe 'n' Sound, perhaps?


----------



## lovingdvd

I will likely have 12-18" of insulation on the front wall, behind the baffle wall. And also several inches of insulation in strategic places along the walls and rear wall, behind acoustical transparent material (fake walls). I'm not keen on having unfaced insulation exposed to the room like this. Is there some sort of mesh / netting material I can cover the insulation with, that will help keep the fibers contained and in-place over the years, without causing some sort of reflection barrier, undoing some of the purpose of having the absorption there in the first place?


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## HT Geek

lovingdvd said:


> I will likely have 12-18" of insulation on the front wall, behind the baffle wall. And also several inches of insulation in strategic places along the walls and rear wall, behind acoustical transparent material (fake walls). I'm not keen on having unfaced insulation exposed to the room like this. Is there some sort of mesh / netting material I can cover the insulation with, that will help keep the fibers contained and in-place over the years, without causing some sort of reflection barrier, undoing some of the purpose of having the absorption there in the first place?


You have several options. 


Unfaced fiberglass insulation
Rock wool insulation
Recycled cotton batt insulation
Paper faced fiberglass insulation
OC 703 or 705 (OC = "Owens Corning"); rigid insulation
Roxul Rockboards (40/60/80); rigid insulation similar to OC 703/705
Use insulation mesh

First, you'll want to cover the insulation with something. At the very least, it's normally going to be acoustic fabric. I have not tried that (yet) with unfaced fiberglass insulation myself, but enough people on this forum have tried it that hopefully one of them will respond to your query on their experience. My strong suspicion is you shouldn't have any issues covering unfaced fiberglass insulation. As long as the insulation is not disturbed, it does not shed fibers. I know this from experience laying insulation. That said, wind can count as "disturbing." 

If you want to use mesh, I suggest something like this 1/4" netting. It is common in newer home construction industry when you have insulation packed tightly inside a wall, and the laborers don't want it to fall out before the drywall goes up; such as in a garage that doesn't have drywall or garage doors on it yet. You don't want the insulation falling down or getting blown out of the walls, so you staple this stuff in there tightly. It does a great job. There are also adhesive versions if that suits your fancy.

At 12-18" thick, Roxul or rock wool will get very expensive. For thinner applications though (e.g. 4" or less), you should seriously consider it. OC 703/705 is another good bet, but it is again another level up in price and can be difficult to acquire without paying exorbitant shipping fees.


----------



## lovingdvd

HT Geek said:


> You have several options.
> 
> 
> Unfaced fiberglass insulation
> Rock wool insulation
> Recycled cotton batt insulation
> Paper faced fiberglass insulation
> OC 703 or 705 (OC = "Owens Corning"); rigid insulation
> Roxul Rockboards (40/60/80); rigid insulation similar to OC 703/705
> Use insulation mesh
> 
> First, you'll want to cover the insulation with something. At the very least, it's normally going to be acoustic fabric. I have not tried that (yet) with unfaced fiberglass insulation myself, but enough people on this forum have tried it that hopefully one of them will respond to your query on their experience. My strong suspicion is you shouldn't have any issues covering unfaced fiberglass insulation. As long as the insulation is not disturbed, it does not shed fibers. I know this from experience laying insulation. That said, wind can count as "disturbing."
> 
> If you want to use mesh, I suggest something like this 1/4" netting. It is common in newer home construction industry when you have insulation packed tightly inside a wall, and the laborers don't want it to fall out before the drywall goes up; such as in a garage that doesn't have drywall or garage doors on it yet. You don't want the insulation falling down or getting blown out of the walls, so you staple this stuff in there tightly. It does a great job. There are also adhesive versions if that suits your fancy.
> 
> At 12-18" thick, Roxul or rock wool will get very expensive. For thinner applications though (e.g. 4" or less), you should seriously consider it. OC 703/705 is another good bet, but it is again another level up in price and can be difficult to acquire without paying exorbitant shipping fees.


Thanks so much for that very detailed explanation. I appreciate that. I will likely need to use pink fluffy for this - as it will be a 15' wall that's about 8' high and covering that with 12-18" is gonna get expensive otherwise (even with pink fluffy that will add up). I will check out that mesh netting you linked to. Any idea what material that is made out of? I wonder if it would act as a reflector for high frequencies or absorb everything just like pink fluffy without this mesh in front of it?

A friend of mine suggested using landscaping fabric like this: http://www.homedepot.com/p/Scotts-4...PIPHorizontal1_rr-_-206684961-_-203074619-_-N . Any idea how that would do? The main thing with any of these fabrics is that I don't want any fiberglass fibers to float off the insulation if when air blows by it.

Also on a different note - what do you guys recommend for the densest, most soundproofing material per inch in thickness? I have a very noisy utility room wall adjacent to my theater. I'll have clips and channels on that wall with double layer DW + GG on the theater side (no room on the other side of the studs for DW or any additional thickness as it backs up to a HVAC unit right up to it) and I want to put insulation inside its stud cavities - so I only have 3.5" of depth for the insulation. What would be the best insulating material to use for that? Thanks!


----------



## HT Geek

lovingdvd said:


> Thanks so much for that very detailed explanation. I appreciate that. I will likely need to use pink fluffy for this - as it will be a 15' wall that's about 8' high and covering that with 12-18" is gonna get expensive otherwise (even with pink fluffy that will add up). I will check out that mesh netting you linked to. Any idea what material that is made out of? I wonder if it would act as a reflector for high frequencies or absorb everything just like pink fluffy without this mesh in front of it?


It's plastic (polypropylene) and weighs ~6 lb./100 sq. ft., so it's light. The squares are 1/4" x 1/4" holes. It shouldn't be reflective of sound. You could use a version with larger squares if you are concerned about that.




> A friend of mine suggested using landscaping fabric like this: http://www.homedepot.com/p/Scotts-4...PIPHorizontal1_rr-_-206684961-_-203074619-_-N . Any idea how that would do?


The link is broken for me. That looks like an URL tied to your Web browser's session, so it won't work for other folks. No matter, deer netting will work as well. They are all lightweight. I'd make sure it's not too rigid (i.e. don't use metal netting or very thick plastic).

You might be able to use a type of landscaping fabric I've seen that I believe is made of paper by-products. I don't know what it is called, but the version I've seen was lightweight and had no holes. It might be a better solution in your case, though I'm not certain of its ability to hold up a vertical surface well such as your insulation. If you stapled it well, you may be fine with that. Might be worth experimenting with if you are so inclined, before you buy a whole bunch of anything.



> The main thing with any of these fabrics is that I don't want any fiberglass fibers to float off the insulation if when air blows by it.


With 1/4" hole netting and acoustic fabric covering it, you should be in good shape. And you need to have a significant breeze to stir it up. Your A/C running, etc. should not be a problem presuming you're not aiming a supply vent directly in front of your insulation and it's uncovered.

Now, I understand where you're coming from though. I have kids and I personally have asthma, so I am sensitive to this stuff as well. Plus, who wants glass fibers in their lungs? 

I suggest you also research the other options I mentioned, relative to air quality. For instance, there is some controversy around cotton batt products because they are mixed with boron (fire retardant). Really, any insulation is going to have airborne hazards under some circumstances. You may also want to read a given manufacturer's instructions or installation guidelines and consider how far you might deviate from them (if at all).

Long term, there is very little if any relevant scientific data on whether or not exposure to fiberglass or rockwool insulation is carcinogenic. The International Agency for Research on Cancer (IARC) declared both to be "possibly carcinogenic" in 1988 and 1991 respectively, however that was so long ago and both product types have been so widely used since then that you'd think IARC ought to conduct another test or two. Processing and packaging of those products has changed significantly since then. For example, virtually any fiberglass insulation you buy today will be free of formaldehyde, but that was not the case in 1988.

There are clearly lung irritation issues with both products, but what is the chance of that happening? It's greater with fiberglass because it's easier to 'stir up' the fibers and dust. Rockwool is denser and unless you are cutting it, produces much less mess during installation, and once installed is even less likely to shed anything.

You may consider a combination of fiberglass in the rear/behind where people would be potentially exposed, and rockwool up front. I'd still use some type of netting though to further limit the possibility of airborne particles.




> Also on a different note - what do you guys recommend for the densest, most soundproofing material per inch in thickness? ... I only have 3.5" of depth for the insulation. What would be the best insulating material to use for that? Thanks!


Check out Bob's sound absorption coefficients of insulation.

It's going to boil down to how much $ you are willing to spend and how much you really want the absolute best solution. There really is not a huge difference in perceived sound reduction between the cheapest (loose fiberglass) and most expensive (probably 3" OC 705). Compare that with Bonded Logic R-13, toward the bottom of the page (which is a recycled cotton product), and 3" Roxul RXL 80, which is an 8 lb./cu. ft. very dense rockwool product.

If you could squeeze 4" in there, you could do even better with the OC and Roxul products, but don't force it in there/compress it. If only have the room between 2x4 studs, stick with 3.5" or 3" depth.


----------



## jrref

lovingdvd said:


> Thanks so much for that very detailed explanation. I appreciate that. I will likely need to use pink fluffy for this - as it will be a 15' wall that's about 8' high and covering that with 12-18" is gonna get expensive otherwise (even with pink fluffy that will add up). I will check out that mesh netting you linked to. Any idea what material that is made out of? I wonder if it would act as a reflector for high frequencies or absorb everything just like pink fluffy without this mesh in front of it?
> 
> A friend of mine suggested using landscaping fabric like this: http://www.homedepot.com/p/Scotts-4...PIPHorizontal1_rr-_-206684961-_-203074619-_-N . Any idea how that would do? The main thing with any of these fabrics is that I don't want any fiberglass fibers to float off the insulation if when air blows by it.
> 
> Also on a different note - what do you guys recommend for the densest, most soundproofing material per inch in thickness? I have a very noisy utility room wall adjacent to my theater. I'll have clips and channels on that wall with double layer DW + GG on the theater side (no room on the other side of the studs for DW or any additional thickness as it backs up to a HVAC unit right up to it) and I want to put insulation inside its stud cavities - so I only have 3.5" of depth for the insulation. What would be the best insulating material to use for that? Thanks!


Just another opinion, the pink fluffy is fiberglass. Even with the covering over it, you are going to get some fiberglass fibers coming off it in certain situations so this is a great health reason to use Roxul. Roxul will be much less likely to shed and if it does, it's made from rock and slag which is less likely to get caught in you lungs. You are spending all this money on DW+GG and clips and channels, etc.. I don't think the extra cost for Roxul will be that great compared to the entire project.


----------



## bigathetank

HT Geek said:


> True for metal on metal, but it also depends on what the materials are. Is the pipe metal? I must have missed that (or forgot). If so, Waterboy is correct in the sense you need to consider what the materials are made of (pipe vs. clamp). So, for example you would need to know if the clamp were copper, zinc, steel, etc. Same with the pipe. At least rough guess it.
> 
> Bigathetank, this is prolly all getting way more detailed than you need to worry about for your pipe, though all the response are poignant! Let us know what you decide to do.



Back in action and working in the basement this week. The hot water pipe is copper and I have decided to go with copper tube straps which will get me the additional clearance that I need after the clips and hat channel go in. I am having 55 pieces of 5/8" Type X drywall delivered Wednesday AM which will go up against the current sub floor (2 layers of drywall) with GG between everything. I have been waiting on Menards to do their 11% rebate on all their stuff which they now have going on. 13.07 per 28 oz. tube looks like a pretty good get based on prices I have seen on other sites. After I get all that fun stuff done I am going to have some HVAC work done. Would it be best to have the flexible ducting coming from the supply duct and to the return duct? It seems that the insulating materials around it will do well/better for deterring sound transmission than that of typical duct work. Please tell me if my idea is flawed and/or something else I can do other than soundproof caulk around existing duct work. I am even thinking of changing the existing duct work to the flexible duct material for the above rooms (living room and MBR/MBath). As always, your thoughts are most appreciated!


----------



## HT Geek

bigathetank said:


> Back in action and working in the basement this week. The hot water pipe is copper and I have decided to go with copper tube straps which will get me the additional clearance that I need after the clips and hat channel go in.


That's great. So, no issues. 



> I am having 55 pieces of 5/8" Type X drywall delivered Wednesday AM which will go up against the current sub floor (2 layers of drywall) with GG between everything. I have been waiting on Menards to do their 11% rebate on all their stuff which they now have going on. 13.07 per 28 oz. tube looks like a pretty good get based on prices I have seen on other sites.


I hope for your sake that someone else is schlepping it into your home. Many building supply firms will do that for free, provided you spend enough $ with them on a given job.

That is a good deal on GG.



> After I get all that fun stuff done I am going to have some HVAC work done.


Why not get the HVAC work done _before _the DW goes up???



> Would it be best to have the flexible ducting coming from the supply duct and to the return duct?


I hope you don't mean that literally. You know that you don't ever want to directly connect your supply and return ducts, right??? That would create a loop and you'd never be able to heat/cool your home!




> It seems that the insulating materials around it will do well/better for deterring sound transmission than that of typical duct work.


Yes. Correct.



> Please tell me if my idea is flawed and/or something else I can do other than soundproof caulk around existing duct work. I am even thinking of changing the existing duct work to the flexible duct material for the above rooms (living room and MBR/MBath).


IMHO, anywhere you can change it to flex duct, do it. There is no appreciable difference in performance (if anything, it ought to be better from an insulation perspective). Plus it would help reduce sound transmission to/from room(s) above.


----------



## bigathetank

HT Geek said:


> That's great. So, no issues.
> 
> I hope for your sake that someone else is schlepping it into your home. Many building supply firms will do that for free, provided you spend enough $ with them on a given job.
> 
> That is a good deal on GG.
> 
> Why not get the HVAC work done _before _the DW goes up???
> 
> I hope you don't mean that literally. You know that you don't ever want to directly connect your supply and return ducts, right??? That would create a loop and you'd never be able to heat/cool your home!
> 
> Yes. Correct.
> 
> IMHO, anywhere you can change it to flex duct, do it. There is no appreciable difference in performance (if anything, it ought to be better from an insulation perspective). Plus it would help reduce sound transmission to/from room(s) above.



I am the one and only getting it from point A to point B. Cutting it in the 14 1/4" x 8' pieces in the garage and then tossing (gently of course) into the window wells and then into the basement from there. Going to stock up on the GG, my Menards only has 35 tubes in stock (only going with 1 tube per 4x8 sheet for the deadening of the sub floor) so going to have to hit up a few more. This is the GG/DW/GG/DW being pushed up against the existing subfloor, from soundproofing site 'best ceiling solution', so keeping the ductwork out of the way as much as possible. Correct on not making the loop between return and supply.  I'm contracting the HVAC out but have read about conflicting views/DIYer's where the move to flexible ducting reduces airflow quite a bit so was thinking of the flexible ducting the last 5-6 feet only?
How often should I screw the layers to the subfloor? 8 screws per 14 1/4 x 8' piece? Going with 1 1/4" screws...any difference between the fine and coarse thread...figure I will go with coarse thread since I will be working above my head and want it to grip ASAP.

Thanks in advance!


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## Waterboy77

bigathetank said:


> I am the one and only getting it from point A to point B. Cutting it in the 14 1/4" x 8' pieces in the garage and then tossing (gently of course) into the window wells and then into the basement from there.


I also did you cutting in the garage, but given the builder did not appear to own a tape measure, I measured each cavity before cutting. Some were 3/4" difference over 12 feet
We did 4 foot pieces and still found them a little awkward especially when there were things in the way.... and still a two person job.... personally I did not even entertain the idea of handling an 8 footer 




bigathetank said:


> How often should I screw the layers to the subfloor? 8 screws per 14 1/4 x 8' piece? Going with 1 1/4" screws...any difference between the fine and coarse thread...figure I will go with coarse thread since I will be working above my head and want it to grip ASAP.


Double check your subfloor thickness to make sure you don't push a screw through the floor.
On a 4 foot long piece I did 5 rows of 3
Fine of course is dependant on what you are screwing into.... fine for steel and coarse for wood.... so yup coarse 
You will want longer screws for your second layer


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## HT Geek

bigathetank said:


> I am the one and only getting it from point A to point B. Cutting it in the 14 1/4" x 8' pieces in the garage and then tossing (gently of course) into the window wells and then into the basement from there.


Ah, I see. I was not visualizing you were talking about applying the DW sandwich to the sub-floor _above_.



> ... have read about conflicting views/DIYer's where the move to flexible ducting reduces airflow quite a bit so was thinking of the flexible ducting the last 5-6 feet only?


Yes, but I don't believe it is a significant drop if the flex duct is installed properly. For instance, it is important to ensure it is stretched so that it is as smooth as possible on the inside, and properly supported so that any bends do not exceed the duct diameter.

That said, square/rectangular ducts allow greater airflow than circular ducts. I've attached a cheat sheet to this post that you may find useful in making some rough calculations.



> How often should I screw the layers to the subfloor? 8 screws per 14 1/4 x 8' piece? Going with 1 1/4" screws...any difference between the fine and coarse thread...figure I will go with coarse thread since I will be working above my head and want it to grip ASAP.


Coarse screws into wood, fine into metal.

I would personally use 16 screws minimum - 1 screw per foot on both sides along the length of those 8' pieces.

Don't forget to use acoustic caulk to seal any gaps around the edges (there will be some for sure).


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## HT Geek

Waterboy77 said:


> You will want longer screws for your second layer


He could make a sandwich in the garage/room, and then put it up. I've not gone this route, but may be worth considering if he has a helping hand.


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## Waterboy77

HT Geek said:


> He could make a sandwich in the garage/room, and then put it up. I've not gone this route, but may be worth considering if he has a helping hand.


He could.... but an 8 foot long x 14" wide 5/8" drywall sandwich would be pretty heavy......But I hate working overhead 


I also invested in a drywall rasp.... works great for getting the pieces to fit tight to the joists


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## bigathetank

Waterboy77 said:


> I also did you cutting in the garage, but given the builder did not appear to own a tape measure, I measured each cavity before cutting. Some were 3/4" difference over 12 feet
> We did 4 foot pieces and still found them a little awkward especially when there were things in the way.... and still a two person job.... personally I did not even entertain the idea of handling an 8 footer
> 
> Double check your subfloor thickness to make sure you don't push a screw through the floor.
> On a 4 foot long piece I did 5 rows of 3
> Fine of course is dependant on what you are screwing into.... fine for steel and coarse for wood.... so yup coarse
> You will want longer screws for your second layer


Going to 'try' the 8 foot sections first, built myself a 'T-bar' to hold up other end of drywall...probably waste of time but thought since I had the lumber I would try it. If it doesn't work, then cut down to 4 footers in the basement...hauling as 8' gives me 1/2 the number of trips. 
Subfloor is 3/4" plus that 5/8" so I went with 1 1/4" coarse thread and then 1 5/8 for the 2nd layer (3/4 + 5/8 + 5/8). My thought on less screws for first layer was it was getting screwed again. Cost of screws are a drop in bucket, just going for less overhead work for myself. Does it need to be screwed that well for the GG to achieve maximum effectiveness?


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## bigathetank

Waterboy77 said:


> He could.... but an 8 foot long x 14" wide 5/8" drywall sandwich would be pretty heavy......But I hate working overhead
> 
> 
> I also invested in a drywall rasp.... works great for getting the pieces to fit tight to the joists


Picked up the drywall rasp while I was out. Bought 2 different Menards out of GG tubes so a rasp was pocket change. Does GG or the acoustical sealant have a 'shelf life' as I saw acoustical sealant from 2011 so I passed on that box??


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## HT Geek

bigathetank said:


> My thought on less screws for first layer was it was getting screwed again.


True. Earlier I was thinking of total # of screws holding it up.


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## Waterboy77

bigathetank said:


> Going to 'try' the 8 foot sections first, built myself a 'T-bar' to hold up other end of drywall...probably waste of time but thought since I had the lumber I would try it. If it doesn't work, then cut down to 4 footers in the basement...hauling as 8' gives me 1/2 the number of trips.
> Subfloor is 3/4" plus that 5/8" so I went with 1 1/4" coarse thread and then 1 5/8 for the 2nd layer (3/4 + 5/8 + 5/8). My thought on less screws for first layer was it was getting screwed again. Cost of screws are a drop in bucket, just going for less overhead work for myself. Does it need to be screwed that well for the GG to achieve maximum effectiveness?


I tend to over engineer things.  
There is al lot of weight that is really only being held by the head of the screw.




bigathetank said:


> Picked up the drywall rasp while I was out. Bought 2 different Menards out of GG tubes so a rasp was pocket change. Does GG or the acoustical sealant have a 'shelf life' as I saw acoustical sealant from 2011 so I passed on that box??


http://www.greengluecompany.com/faq, says 1 year but if stored properly longer....


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## bigathetank

Well, all the drywall is cut into the proper widths, going to slide them down to basement tomorrow so I can get my garage back. So I feel pretty good about the drywall in between the joists, next step (after HVAC) will be for me to install the clips and hat channel for the ceiling. Looking around it seems that 24" OC is the proper distance (along with runs near the edges) for the ceiling when doing 2 layers of 5/8" DW correct? I am probably only going to do some soundproofing on one wall (clips and channel and 2 layers of DW/GG) that is right underneath our MBR and bath and call it day. Already have 2" R-10 Foamular glued to all the concrete foundation (for insulating purpose not soundproofing), then 2x4 walls which will also be filled with R-13...is doing one wall a waste of $$$? The other walls aren't an issue as they aren't under the MBR or Bath. That is the only reason I am soundproofing in the first place is to keep as much noise out of MBR for late night movie watching while the wife attempts to sleep. Is my thinking flawed? The entire ceiling will be done and the common wall directly beneath the MBR/BA.

Thanks in advance!!


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## arcamm

I glued two layers of 5/8" dry wall with GG between the joists in my addition, added Roxal, iso-clips and 5/8" drywall. I've very pleased with the results. I've tested it with my sound system and at moderate volumes, the only sound I can hear upstairs is coming up the stairs, through the dinning room and into the room above the media room. And that is with three doors open. Well worth all the effort!


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## Livin

arcamm said:


> I glued two layers of 5/8" dry wall with GG between the joists in my addition, added Roxal, iso-clips and 5/8" drywall. I've very pleased with the results. I've tested it with my sound system and at moderate volumes, the only sound I can hear upstairs is coming up the stairs, through the dinning room and into the room above the media room. And that is with three doors open. Well worth all the effort!


You only hung one layer of drywall but two layers against the underlayment? Why did you choose that vs the opposite?


----------



## bigathetank

arcamm said:


> I glued two layers of 5/8" dry wall with GG between the joists in my addition, added Roxal, iso-clips and 5/8" drywall. I've very pleased with the results. I've tested it with my sound system and at moderate volumes, the only sound I can hear upstairs is coming up the stairs, through the dinning room and into the room above the media room. And that is with three doors open. Well worth all the effort!


That's great to hear, as the effort and expense that I am going through/will go through is a lot in hoping that my efforts are 'worth' it. Ultimately, if the WAF is high then it's a win!! Still a long ways to go. Did you space your iso clips 24" OC and did you stagger them or line them up on your joists? I am going to address my basement door but figure that is the easiest of things to do, already solid oak so just need to take care of area beneath it.

Thank you!


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## Gouie

I don't mean to disrupt the conversation but do have a quick question. I know these aren't the easiest questions to answer, just looking for general opinions. I will be installing clips/channel/DD&GG for all walls and the ceiling. What I hadn't considered is adding density to the above sub floor. The more I read the more I see folks going this route. In addition to my other efforts would you suggest that I add the mass to the sub floor? It is not too late for me as all I have done to this point is insulate the ceiling.


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## HT Geek

Gouie said:


> I will be installing clips/channel/DD&GG for all walls and the ceiling. What I hadn't considered is adding density to the above sub floor. The more I read the more I see folks going this route. In addition to my other efforts would you suggest that I add the mass to the sub floor? It is not too late for me as all I have done to this point is insulate the ceiling.


I'd say it's dependent on what is above your HT room and what your goals are.


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## Gouie

Kitchen directly above with tile flooring. I recognize that complete isolation is near impossible but I would like to keep a conversation going in the kitchen while the theatre is in use. 

Is adding mass to the sub floor a pretty common practice?


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## bigathetank

Gouie said:


> Kitchen directly above with tile flooring. I recognize that complete isolation is near impossible but I would like to keep a conversation going in the kitchen while the theatre is in use.
> 
> Is adding mass to the sub floor a pretty common practice?


I don't know how common a practice it is, but for the cost of it with my ceiling joists open, I figure I might as well. I have carpeting above where I am 'soundproofing' so footfall noise wasn't all that important, I just wanted another line of defense for sound going up as MBR is directly above the rear portion of my theater area and above the bar.

--A


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## KanosWRX

I have a kitchen above my HT with hardwood up there. I will say you can still hear foot steps (faint little thuds) every now and then so if you want to go all the way and make it as sound proof as possible you would have to probably add extra mass to that floor. That said, once I start playing a movie I don't hear anything


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## arcamm

Livin said:


> You only hung one layer of drywall but two layers against the underlayment? Why did you choose that vs the opposite?



From everything I've read (mostly here), the key is getting mass against the sub-floor. I figured I could always add a second layer of drywall to the ceiling, but no way to the subfloor. When I installed my iso-clips, I made sure I installed enough to support a second layer if I were to ever add it.



bigathetank said:


> That's great to hear, as the effort and expense that I am going through/will go through is a lot in hoping that my efforts are 'worth' it. Ultimately, if the WAF is high then it's a win!! Still a long ways to go. Did you space your iso clips 24" OC and did you stagger them or line them up on your joists? I am going to address my basement door but figure that is the easiest of things to do, already solid oak so just need to take care of area beneath it.
> Thank you!



I went 24" OC and lined them up on the joists. I wanted to make sure I had enough to add a second layer of 5/8" if ever needed. It helped that I found an opened box of Iso-clips on ebay for almost half price.


My only regret is that I forgot to take any pictures of the track after we finished it before the drywall went in.


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## healthnut

I have the same type of project and am adding 3/4" MDF board to the subfloor, followed with 2 3" layers of SafeNSound. I"m adding Green Glue to the MDF board and following with 2 layers of 5/8 drywall with more Green Glue, as well as hat channel and ISO clips. I also used the Green Glue Noiseproofing caulk in all joints and seams on the subfloor before applying the MDF boards and also sealing around the MDF boards with more of the noise proofing caulk. This should all provide plenty of mass and damping.


Sent from my iPhone using Tapatalk


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## Gouie

healthnut said:


> I have the same type of project and am adding 3/4" MDF board to the subfloor, followed with 2 3" layers of SafeNSound. I"m adding Green Glue to the MDF board and following with 2 layers of 5/8 drywall with more Green Glue, as well as hat channel and ISO clips. I also used the Green Glue Noiseproofing caulk in all joints and seams on the subfloor before applying the MDF boards and also sealing around the MDF boards with more of the noise proofing caulk. This should all provide plenty of mass and damping.
> 
> 
> Sent from my iPhone using Tapatalk




That's a lot of added weight, any structural concerns?


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## healthnut

Gouie said:


> That's a lot of added weight, any structural concerns?




The subfloor is 3/4" and the joists are 2x10's, I'm not anticipating any issues with the added weight. Floor upstairs is much more stable, no more creaks when walking on it. I have a Sonos system which is set to halfway volume upstairs and couldn't hear it all in the basement, when before, it's sounded almost as though it was in the same room. Only when set to maximum was it audible, and that's before adding any insulation or drywall. So far, it's working out well.


----------



## Gouie

Thanks, the first hand experience is very helpful. I'm going to drop the insulation and go ahead with drywall and green glue.


----------



## Livin

healthnut said:


> I have the same type of project and am adding 3/4" MDF board to the subfloor, followed with 2 3" layers of SafeNSound. I"m adding Green Glue to the MDF board and following with 2 layers of 5/8 drywall with more Green Glue, as well as hat channel and ISO clips. I also used the Green Glue Noiseproofing caulk in all joints and seams on the subfloor before applying the MDF boards and also sealing around the MDF boards with more of the noise proofing caulk. This should all provide plenty of mass and damping.
> 
> 
> Sent from my iPhone using Tapatalk


I'm not 100% following...

Did you attach GG/MDF to floor underlayment, plus clips&channel plus DW/GG/DW? 

Why MDF and not 2xDW attached to the underlayment?


----------



## healthnut

Livin said:


> I'm not 100% following...
> 
> Did you attach GG/MDF to floor underlayment, plus clips&channel plus DW/GG/DW?
> 
> Why MDF and not 2xDW attached to the underlayment?




MDF is very good for suppressing vibrations, which is why it's used in speaker cabinets. More expensive, certainly. It's also a good deal denser, so adds more mass than drywall would. I recognize, however, there are limits to how far mass and damping can take you, and that isolation is the single most important soundproofing principle, so the hat channel and isolation clips will be most important.


----------



## Livin

healthnut said:


> MDF is very good for suppressing vibrations, which is why it's used in speaker cabinets. More expensive, certainly. It's also a good deal denser, so adds more mass than drywall would. I recognize, however, there are limits to how far mass and damping can take you, and that isolation is the single most important soundproofing principle, so the hat channel and isolation clips will be most important.


Interestingly (retail price) ... 
1/2" cement board ($20 sheet), 80 lbs 
1/2" DW ($10 sheet), 38.4 lbs 
5/8" DW ($12 sheet), 70 lbs 
3/4" MDF ($30 sheet), 80 lbs 
7/16" OSB ($10 sheet), 46lbs

... Is cement board is a better cost for the same mass as MDF?

... Does $20 of OSB may outperform both $30 of MDF and cement board? 

... For $30, Two layers of 5/8 DW weighs 140lbs vs one 3/4 MDF weight of 80 lbs... Seems like DW wins for adding mass per dollar

onto my real question... 

Is it better to add more mass between the joists, or do a ceiling with 5/8" DW/GG/DW?

I'm tearing out the current ceiling and planning to do a low profile install of the clips, to preserve as much ceiling height as possible. 
The double hung drywall will likely be a lot more labor costs since I can put the DW in the joists myself. 
I'm not redoing the walls, so no clips there, just standard walls. 

Thx for the help


----------



## healthnut

I'm not a soundproofing expert, but I can say definitively that the DW/GF/DW will do a lot more for you in soundproofing than added mass. I heard about a study that was done in an attempt to eliminate audibly a 20 HZ tone using mass only. It required 4 feet of concrete buried under 10 feet of earth to eliminate it. Structural isolation is required for soundproofing because vibrations travel from structure to structure unless steps likes hat channel, isolation clips, and double layers of drywall connected only to the hat channel and isolated from the adjoining structure are taken.
Interesting survey of the weight of different materials, but it doesn't take into account their properties. Weight is important, but MDF specifically surprises vibration, so that's why it's used in speaker enclosures (btw, bamboo is even better, but also a lot costlier). It can be useful to use different types of materials to surpress sound, and leave an air gap between. 


Sent from my iPhone using Tapatalk


----------



## BasementBob

healthnut said:


> MDF is very good for suppressing vibrations, which is why it's used in speaker cabinets. More expensive, certainly. It's also a good deal denser, so adds more mass than drywall would.


 
re speaker cabinets. One can't use drywall, it would shatter and break. One can't use concrete, too heavy. Plastic is too light. Of the various woods, MDF has mass and stiffness and doesn't warp or split, and its relatively inexpensive. Here the stiffness isn't important from a vibration absorption point of view nor from a resonance point of view, but merely to give something unmoving at the largest number of frequencies for the speaker cone to push off of. Increasing cabinet rigidity is always a good thing.

re walls. MDF is far more expensive than drywall, and not much of a difference from a soundproofing point of view if the density per square foot is the same. MDF, being wood, has an advantage over drywall in that you can screw things into it anywhere, and its structural strength gives lateral twisting earthquake strength to walls. MDF, being wood, has a disadvantage over drywall in that it is not a firestop and emits formaldehyde offgasssing.

Note: I'm pretty good with soundproofing theory. I'm not anyone's 'go to guy' for speaker cabinet design, although I know a couple who are pretty good.


----------



## BasementBob

healthnut said:


> DW/GF/DW


DW is usually drywall.
GF is usually glass fiber (aka fluffy fiberglass pink).
Did you mean something different here?


----------



## BasementBob

healthnut said:


> eliminate audibly a 20 HZ tone using mass only. It required 4 feet of concrete buried under 10 feet of earth to eliminate it. Structural isolation is required for soundproofing because vibrations travel from structure to structure unless steps likes hat channel, isolation clips, and double layers of drywall connected only to the hat channel and isolated from the adjoining structure are taken


Certainly 4 feet of concrete buried under 10 feet of earth would do significant suppression of transmission through it of a 20hz tone.
However hat channel and isolation clips, will not affect a 20hz tone's transmission through a wall at all.


----------



## healthnut

BasementBob said:


> Certainly 4 feet of concrete buried under 10 feet of earth would do significant suppression of transmission through it of a 20hz tone.
> However hat channel and isolation clips, will not affect a 20hz tone's transmission through a wall at all.




If you were trying to prevent low bass from resonating the floor above a theater room, would not hat channel and isolation clips at least minimize transmission between adjoining structures? If not, is there some better strategy, or would you say nothing can be done?


----------



## HT Geek

healthnut said:


> I'm not a soundproofing expert, but I can say definitively that the DW/GF/DW will do a lot more for you in soundproofing than added mass.


Placing your Girl Friend (GF) in between 2 sheets of drywall will likely improve isolation to some extent, but you will encounter an increase of in-wall flanking noise. It may also introduce undesirable vibrations into your HT room, such as loud banging.


----------



## healthnut

HT Geek said:


> Placing your Girl Friend (GF) in between 2 sheets of drywall will likely improve isolation to some extent, but you will encounter an increase of in-wall flanking noise. It may also introduce undesirable vibrations into your HT room, such as loud banging.




Ha! Lol!! Typo, should have been GG, for Green Glue.


----------



## Gouie

HT Geek said:


> Placing your Girl Friend (GF) in between 2 sheets of drywall will likely improve isolation to some extent, but you will encounter an increase of in-wall flanking noise. It may also introduce undesirable vibrations into your HT room, such as loud banging.


Thanks for that, a much needed smile on a Friday afternoon.


----------



## Livin

Guys,
I'm tearing out my existing ceiling and planning to do a low profile install of the clips - to preserve as much ceiling height as possible. 

For clips I'm looking at using either...
1) IB-1 on blocking (IB1 clips mounted to blocking) : http://www.avsforum.com/content/type/61/id/387266/ ~1.75 each + 2x4 wood cost + more labor
or
2) RSIC-1-LOW PROFILE clip: http://www.pac-intl.com/rsic1-low-profile.html ~$6.50 ea
or
3) IB-2 EXT clip : http://www.soundproofingcompany.com...proofing-clips/ib-3-ext-sound-isolation-clip/ ~6.50 ea (TMS version is $5.50 ea)

... any reason to do one vs the others?


My biggest goal is to reduce footfall noise from above (chairs moving, balls bouncing on the wood floor, etc)
- I'm not redoing the walls, so no clips there, just standard walls. 

Where is my money better spent...

1) Between the joists, GG/DW/GG/DW + Clips/Channel with 1 layer of 5/8 DW? 
vs
2) Between the joists, GG/DW + Clips/Channel with DW/GG/DW?

#2 above will be slightly less material costs but #2 's additional labor costs might be significant - basically paying the drywall guy to do 2x the work.

thanks for the help!


----------



## HT Geek

Livin said:


> Guys,
> I'm tearing out my existing ceiling and planning to do a low profile install of the clips - to preserve as much ceiling height as possible.
> 
> For clips I'm looking at using either...
> 1) IB-1 on blocking (IB1 clips mounted to blocking) : http://www.avsforum.com/content/type/61/id/387266/ ~1.75 each + 2x4 wood cost + more labor
> or
> 2) RSIC-1-LOW PROFILE clip: http://www.pac-intl.com/rsic1-low-profile.html ~$6.50 ea
> or
> 3) IB-2 EXT clip : http://www.soundproofingcompany.com...proofing-clips/ib-3-ext-sound-isolation-clip/ ~6.50 ea (TMS version is $5.50 ea)
> 
> ... any reason to do one vs the others?
> 
> 
> My biggest goal is to reduce footfall noise from above (chairs moving, balls bouncing on the wood floor, etc)
> - I'm not redoing the walls, so no clips there, just standard walls.
> 
> Where is my money better spent...


You ought to be able to find the RSIC-1 and IB-2 EXT for around $4.85-$5.50 per clip when purchased in bulk. And that is with minimal search effort. If you are patient, you could encounter significantly cheaper solutions on EBay or Craigslist from folks selling excess inventory or leftovers.

However, if you want low profile, I'd be inclined to go with the IB-1. It's very low profile and dirt cheap @ around $2/clip. Sure, it's not *quite* as good as the IB-2 and RSIC-1 (no rubber), but it still isolates and that is the key.

So, the IB-1 would seem to solve 2 important issues: ceiling height & cost. 

I would cross out the IB-2 EXT. Your other two options seem better suited to your scenario.

OTOH, you might be able to float a new set of joists using the IB-2 EXT clips, but that's impossible to say for sure without seeing what you have to work with in terms of the ceiling joists. Plus you'd then have the cost of the ceiling joist hangers.


----------



## Livin

HT Geek said:


> You ought to be able to find the RSIC-1 and IB-2 EXT for around $4.85-$5.50 per clip when purchased in bulk. And that is with minimal search effort. If you are patient, you could encounter significantly cheaper solutions on EBay or Craigslist from folks selling excess inventory or leftovers.
> 
> However, if you want low profile, I'd be inclined to go with the IB-1. It's very low profile and dirt cheap @ around $2/clip. Sure, it's not *quite* as good as the IB-2 and RSIC-1 (no rubber), but it still isolates and that is the key.
> 
> So, the IB-1 would seem to solve 2 important issues: ceiling height & cost.
> 
> I would cross out the IB-2 EXT. Your other two options seem better suited to your scenario.
> 
> OTOH, you might be able to float a new set of joists using the IB-2 EXT clips, but that's impossible to say for sure without seeing what you have to work with in terms of the ceiling joists. Plus you'd then have the cost of the ceiling joist hangers.


I have 10" I-Joists (I-beam made from wood) so I was thinking I could either add the blocking and use the IB-1 to keep the DW only 1/2" gap from the joists, or use the RSIC-1 Low Profile or IB-2 Ext to serve the same purpose, just without needing the blocking. Basically a tad bit less work than blocking with IB-1. In hopes to find the RSIC-1 Low Profile or IB-2 Ext on ebay for less... maybe $3 each or so if I get lucky.


What do you think on best spent money (given labor for #2 will be nearly 2x cost of #1)... 

1) Between the joists, GG/DW/GG/DW + Clips/Channel with 1 layer of 5/8 DW? 
vs
2) Between the joists, GG/DW + Clips/Channel with DW/GG/DW?


thx for the input!


----------



## hatlesschimp

I asked my builder to give me 16mm fyrcheck plaster but has come back saying they want to add a 2nd sheet of normal plaster all the way round on top so there will be two layers of 10mm plaster. He said its the same acoustically and will look better because the normal plaster sheets are longer so there will be less joins plus its lighter for the plasterer to handle. What do you think?

I asked for fyrchek because its apparently acoustically the same as soundchek. 

Here is my Theatre plan. Cheers


----------



## TheNecromancer

Yet another soundproofing question.

From what I've gathered, in soundproofing it's kind of all or nothing. So I was prepared to do clips, ddw, GG, backer boxes etc. After taking measurements I'm facing the reality that my small room can not afford to give up the extra inches on the side walls. I've got only 12'8" to work with. I wanted two rows of 3 seats and even if I use the not as nice 96" wide as you can see there is little room left to walk past.

So given the side walls can at most be drywall + whatever I place in the wall, is it still beneficial to use clips, GG and DDW on the ceiling? Or is this now a waste as the drywall is fastened directly to the walls? 

This is a basement room with MBR just above and to the side.


----------



## mongldroid

*Neighborhood Garage Studio Sound Reduction (Quietrock vs Channel vs Double Drywall)*

Hello, I have read a lot of good info on this forum about sound reductions/sound proofing and would like a few opinions on my specific set up. I have included a map showing the studio and my neighbors with the distance between them.

BACKSTORY
I am moving in to a 22x16ft space behind the garage at my grandparents to help care for them while I finish university. I plan to make it a studio

MISSION
To create a satisfactory sound reduction in my new jam space so my band can practice without ANY possibility of neighbor complaints. I prolly don't need to soundproof completely but do not want any neighbors hearing me in their homes or barely outside. 

STATUS
The walls are currently sitting with exposed studs and insulation ready to take a next step

QUESTION
I am wondering what the necessary minimum is to accomplish this is based on my specific needs:

Here is what is spinning in my head:

1. Would just double 5/8" drywall with acoustic glue between work well enough? (Cheapest)
2. Do I need quietrock? Locally sold for $50 a sheet.
3. I have almost completely ruled out things like genie clips and channel as quietrock is calculating to the same cost (around $1000 without ceiling)
4. Are there better options in the same budget range these days?


----------



## HT Geek

Livin said:


> I have 10" I-Joists (I-beam made from wood) so I was thinking I could either add the blocking and use the IB-1 to keep the DW only 1/2" gap from the joists,....


Ok. Now I see where you're going with the concept.

So, if you've got 10" I-Joists, have you contemplated a lowered ceiling (room-within-a-room style) instead of clips & channel in your room? It would be the absolute best ceiling isolation method. If your joists are all parallel, it seems to me that would be your best bet. You could still dampen between the joists if you like.

How long are the current joists? Do they run lengthwise? I don't recall your room size, but if so that would likely complicate the concept but it's not impossible to do. 




> 1) Between the joists, GG/DW/GG/DW + Clips/Channel with 1 layer of 5/8 DW?
> vs
> 2) Between the joists, GG/DW + Clips/Channel with DW/GG/DW?


#2 for sure. You want the larger mass enveloping your sound stage. Whatever you place in the joist cavities will not envelope; it will simply dampen sound travelling through that space.


----------



## HT Geek

mongldroid said:


> I am moving in to a 22x16ft space behind the garage at my grandparents to help care for them while I finish university.


Very noble of you. Just sayin'. 



> MISSION
> To create a satisfactory sound reduction in my new jam space so my band can practice without ANY possibility of neighbor complaints. I prolly don't need to soundproof completely but do not want any neighbors hearing me in their homes or barely outside.
> 
> STATUS
> The walls are currently sitting with exposed studs and insulation ready to take a next step
> 
> QUESTION
> I am wondering what the necessary minimum is to accomplish this is based on my specific needs:
> 
> Here is what is spinning in my head:
> 
> 1. Would just double 5/8" drywall with acoustic glue between work well enough? (Cheapest)
> 2. Do I need quietrock? Locally sold for $50 a sheet.
> 3. I have almost completely ruled out things like genie clips and channel as quietrock is calculating to the same cost (around $1000 without ceiling)
> 4. Are there better options in the same budget range these days?


First, just to be clear: it's viscoelastic damping compound, not glue.

#1 and 2 are very similar if you're talking about QuietRock ES. At that price, I hope you are not. Which QuietRock model is it? 545, perhaps?

If you are comparing the proverbial apples-to-apples (e.g. sheetrock + damping compound vs. QuietRock ES + damping compound), there isn't a lot of variation. QR ES + Quiet Glue (the company's viscoelastic damping product) provides very good damping, but it's not going to be worthwhile to most people versus normal sheetrock + Green Glue/Quiet Glue/etc. Even though QR ES is heavier than standard Type X drywall (2.6 lbs./sq. ft. vs. 2.2 lbs./sq. ft.), when one takes a comprehensive look at the publicly available lab test results, there's not a huge benefit to choosing the QR ES drywall under most circumstances. That said, QR ES is in the top 10 of tested combinations, based on STC (but that also means a number of non-QR combinations hit similar performance levels).

If you are talking about QR model 545, that's a different beast. QR-545 weight is roughly equivalent to 3x sheets of Type-X drywall (~6.7lbs./sq ft versus ~6.6lbs./sq ft + damping compound weight of 3 sheets Type X sheetrock). This makes a good case for the QuietRock from a weight (mass) viewpoint, however to assess the benefits in sound absorption between the two you'd need to compare lab reports. I have not seen any (yet) on QuietRock 545. I'm sure there are some out there, but I haven't bothered to look to date because I'm not interested in lugging around drywall sheets that weigh >214 lbs. per 4x8 sheet.

Anyhow, point is there are multiple varieties of QuietRock. 

#3... QuietRock and double-drywall are focused on mass. Clips & Channel products are all about physically de-coupling surfaces. They deaden sound transmission using different principles. In an ideal setting, you want to use both methods (along with a couple of others as well) to attack your sound transmissions on multiple fronts, for greater effectiveness in total damping.

If you are thinking of an either/or approach, I'd suggest focusing on mass as a priority. That's just my personal opinion. Others may have different thoughts on that subject.


#4... Are you primarily interested in attenuating low or high frequencies? Or both equally?


----------



## HT Geek

TheNecromancer said:


> From what I've gathered, in soundproofing it's kind of all or nothing.


That's how the experts generally view it. However, if you - like most people - don't have an unlimited budget, space, etc., you've got to be practical as well. IMHO, much depends on why you want to sound proof a space to begin with. The 'why' should help you narrow down what is reasonable from a level-of-effort perspective, along with other variables of course (but I'd start there).



> So I was prepared to do clips, ddw, GG, backer boxes etc. After taking measurements I'm facing the reality that my small room can not afford to give up the extra inches on the side walls. I've got only 12'8" to work with. I wanted two rows of 3 seats and even if I use the not as nice 96" wide as you can see there is little room left to walk past.
> 
> So given the side walls can at most be drywall + whatever I place in the wall, is it still beneficial to use clips, GG and DDW on the ceiling? Or is this now a waste as the drywall is fastened directly to the walls?
> 
> This is a basement room with MBR just above and to the side.


Do you anticipate playing loud volumes of music/movies when someone is trying to sleep in the MBR?

In your case I would recommend clips & channel on all 5 sides (4 walls+ceiling) or staggered studs for the walls + C&C ceiling, with DD/GG. You won't lose much room on the sides (you'll end up with ~12' width, which is plenty for a good HT room).


----------



## HT Geek

hatlesschimp said:


> I asked my builder to give me 16mm fyrcheck plaster but has come back saying they want to add a 2nd sheet of normal plaster all the way round on top so there will be two layers of 10mm plaster. He said its the same acoustically and will look better because the normal plaster sheets are longer so there will be less joins plus its lighter for the plasterer to handle. What do you think?


Are you asking if we believe 2x 10mm plaster is as good as 1x16mm plaster relative to sound proofing?

I'd say yes, for two reasons. First, it's thicker/heavier. Second, the 2nd layer will (presumably) overlap the 1st layer seams and that will help prevent sound leakage.

Now, all that said.... if you are having new construction done then you ought to be able to dictate what they are using in terms of which product. If not, hire a different general contractor. But more importantly, you're at an opportune point to introduce some other concepts that would help greatly dampen sound emanating into or out of your theater room (e.g. thicker wall studs such as 2x6 vs. 2x4 studs, staggered stud system to de-couple the theater walls, double plaster layer ceiling, viscoelastic damping compound between plaster layers, etc.).


----------



## granroth

TheNecromancer said:


> From what I've gathered, in soundproofing it's kind of all or nothing.


That's an extremely common misinterpretation of soundproofing pitfalls but one that I see as being almost completely false.

The problem comes in with the concept of "flanking" and/or "getting what you paid for". Say you put up three layers of drywall with Green Glue on clips and then left a standard door in the center of the wall. If you paid the money to have that solution installed _expecting_ a drop of 70 dB and only got 40 dB due to the door flanking then you will likely be very disappointed and think along the terms of all or nothing.

But what's forgotten in that is that the overall solution would actually make a very marked difference in sound transference well beyond what the wall would do without said treatment. It's not what you'd hope for but it's not "nothing".

So I approach this from the perspective that as long as you go into this with *realistic expectations* then you can do any "level" of soundproofing that your budget and willingness can handle and you'll be very happy with the results.


----------



## Livin

Odd question for acoustic experts and gurus... 

Many designs call for adding mass to between joints and DW is usually the material used. 

What about using asphalt roof shingles or rolls ?... Shingles weigh a ton and aren't that expensive per lb. Plus, asphalt sheets, like the original dynamat, was what old timers used to damp sound in car audio way back when. 

Or

Cement Board which weights slightly more than DW but is thinner. If cost were the same as DW, would you use the cement board ? 

Thoughts?


----------



## HT Geek

Livin said:


> Odd question for acoustic experts and gurus...
> 
> Many designs call for adding mass to between joints and DW is usually the material used.
> 
> What about using asphalt roof shingles or rolls ?... Shingles weigh a ton and aren't that expensive per lb. Plus, asphalt sheets, like the original dynamat, was what old timers used to damp sound in car audio way back when.
> 
> Or
> 
> Cement Board which weights slightly more than DW but is thinner. If cost were the same as DW, would you use the cement board ?
> 
> Thoughts?


Some folks here have used cement boards. It's commonly used in backer boards. So, I don't see any issues with that. I'd suggest 1/2".

I would not recommend roof shingles for a variety of reasons. First and foremost, the odor. Another reason... not very rigid; awkward to secure overhead - such as between joists. Just a couple of quick thoughts. My recollection (may be wrong... I have not worked in 12v auto industry for several years - but I used to), is the original dynamat was not a bunch of shingles. Cars are also not airtight (re: odor).


----------



## HT Geek

granroth said:


> That's an extremely common misinterpretation of soundproofing pitfalls but one that I see as being almost completely false....
> 
> So I approach this from the perspective that as long as you go into this with *realistic expectations* then you can do any "level" of soundproofing that your budget and willingness can handle and you'll be very happy with the results.


^^^^^ What he said. More clearly explained than my previous comment.

Bottom line: set realistic expectations based on your requirements; then build to that spec - whatever that entails - but don't forget there are multiple demons at play. It boils down to mitigating directional and flanking sounds - both entering and exiting the HT room.


----------



## kmhvball

Livin said:


> Cement Board which weights slightly more than DW but is thinner. If cost were the same as DW, would you use the cement board ?
> 
> Thoughts?


 Simply for ease of cutting and screwing through, I would do drywall... around here it is cheaper too, but guess that isn't the case for you.

Performance wise, if greater mass, might be better... not worth it in my opinion though


----------



## Superman07

Our HVAC can be a bit on the loud side. It's better since we had the system replaced the other year, but if you're in the room it's adjacent to (HVAC is really in a closet with double vented doors) it's loud, or if you're upstairs with the main TV and speakers the air return is the loud part.

Any quick and relatively cheap ways to deaden the sound? Attached a few quick picks.


----------



## TheNecromancer

*Theater room door*

I came across an exterior door that I really like at a great price and wondered if being that it's exterior it's 1 3/4" and made of Fiberglass with a polyurethane foam core along with weatherstripped would it be comparable to a solid wood interior door?


----------



## snailpail

Hi guys, I have a quick question about soundproofing walls. In my condo if you put your ear to the wall you can hear the neighbors in the unit above or below you. 

Whats an ez way to block that kind of sound transfer.

I recently soundproofed the ceiling with rockwool, clips, channel, double dw and greenglue. Cut away the tops of the old wall to get a new install seal on the studs. Then decided to remove the old drywall and install new drywall (the 30% lighter stuff..) before the second layer of ceiling dw to acheive the step effect.

I haven't mudded it yet though and was wondering if I should remove the new wall panels and use SoundBlock mlv (sold at home depot) on the studs first, then reinstall the panels. Or is there an easier way to do it?


----------



## HT Geek

snailpail said:


> I haven't mudded it yet though and was wondering if I should remove the new wall panels and use SoundBlock mlv (sold at home depot) on the studs first, then reinstall the panels. Or is there an easier way to do it?


First off, don't do that. MLV on walls is only marginally useful and that's in a lab. It is very difficult to get it installed correctly, and by correctly I mean where you will reap a gain in the real world. Just don't do it. It is not worth the cost, effort, and time for a high chance of very little to no value.



> Hi guys, I have a quick question about soundproofing walls. In my condo if you put your ear to the wall you can hear the neighbors in the unit above or below you.
> 
> Whats an ez way to block that kind of sound transfer.
> 
> I recently soundproofed the ceiling with rockwool, clips, channel, double dw and greenglue. Cut away the tops of the old wall to get a new install seal on the studs.


More details/a little clearer explanation would be helpful. For example, did you install your DD+GG/clips & channel on top of your existing ceiling drywall? Or did you strip your ceiling down to the studs first?



> Then decided to remove the old drywall and install new drywall (the 30% lighter stuff..) before the second layer of ceiling dw to acheive the step effect.


I don't understand what you mean by that exactly. Could you elaborate? Are you talking about the walls, the ceiling???

BTW, the 'lighter stuff' drywall is counter-productive to sound isolation/damping. You want the heavier drywall.


----------



## HT Geek

Superman07 said:


> Our HVAC can be a bit on the loud side. It's better since we had the system replaced the other year, but if you're in the room it's adjacent to (HVAC is really in a closet with double vented doors) it's loud, or if you're upstairs with the main TV and speakers the air return is the loud part.
> 
> Any quick and relatively cheap ways to deaden the sound? Attached a few quick picks.


Hate to say this, but from the looks of it, I can't imagine a quick fix. Ideally, when the old unit was removed if you could have either a) relocated the unit elsewhere ($$$$) or b) slapped up double layers of drywall on the ceiling and walls of that room ($), which would have helped a lot with the exception of the adjacent room. As you mentioned, the door is vented. I'm sure there is a reason it's vented. And obviously, that will allow more sound to escape into the adjacent room.

I'd say at this point you would need to think about whether not its realistic to add at least a single layer of drywall to those bare studs (it doesn't have to look pretty, just be functional) and perhaps expand the size of the closet so that you have room to sound-proof around the unit. Another thought would be to create a fresh-air path (vent) from another part of the house or the outside - depending on why the door is vented and your climate. You'd want to consult with an HVAC expert on that issue.


----------



## HT Geek

TheNecromancer said:


> I came across an exterior door that I really like at a great price and wondered if being that it's exterior it's 1 3/4" and made of Fiberglass with a polyurethane foam core along with weatherstripped would it be comparable to a solid wood interior door?


I'm not a door expert, but I can tell you that mass/weight is primarily what you're going after with the door itself. To get good sound-proofing of and around the door you'll need to add additional mass to it (e.g. MDF) and most of all make sure areas in and around the door frame are designed/treated to minimize flanking noise.

A number of folks on AVS have used exterior doors as you've described.


----------



## Superman07

HT Geek said:


> Hate to say this, but from the looks of it, I can't imagine a quick fix. Ideally, when the old unit was removed if you could have either a) relocated the unit elsewhere ($$$$) or b) slapped up double layers of drywall on the ceiling and walls of that room ($), which would have helped a lot with the exception of the adjacent room. As you mentioned, the door is vented. I'm sure there is a reason it's vented. And obviously, that will allow more sound to escape into the adjacent room.
> 
> I'd say at this point you would need to think about whether not its realistic to add at least a single layer of drywall to those bare studs (it doesn't have to look pretty, just be functional) and perhaps expand the size of the closet so that you have room to sound-proof around the unit. Another thought would be to create a fresh-air path (vent) from another part of the house or the outside - depending on why the door is vented and your climate. You'd want to consult with an HVAC expert on that issue.


Thanks for the feedback. I think the doors are vented for code. I was hoping to put something over the vents and leave a 1-2" gap to allow airflow, but block noise, but I expect that isn't allowed.

I'll look into adding some drywall at the top. Might be possible to added some padding on the air return feed too (to the right that I didn't take a picture of). Is there duct padding that is code rated?


----------



## Livin

snailpail said:


> Hi guys, I have a quick question about soundproofing walls. In my condo if you put your ear to the wall you can hear the neighbors in the unit above or below you.
> 
> Whats an ez way to block that kind of sound transfer.
> 
> I recently soundproofed the ceiling with rockwool, clips, channel, double dw and greenglue. Cut away the tops of the old wall to get a new install seal on the studs. Then decided to remove the old drywall and install new drywall (the 30% lighter stuff..) before the second layer of ceiling dw to acheive the step effect.
> 
> I haven't mudded it yet though and was wondering if I should remove the new wall panels and use SoundBlock mlv (sold at home depot) on the studs first, then reinstall the panels. Or is there an easier way to do it?


I'm about to tear out my current ceiling and do what you did... Hope it's worth it? 

A few questions... 

Did the new ceiling greatly improve the footfall and voices from above? 

Can you post a diagram showing what you did when you removed the wall tops and added a seal? and the step effect? 

Thx


----------



## HT Geek

Superman07 said:


> Thanks for the feedback. I think the doors are vented for code. I was hoping to put something over the vents and leave a 1-2" gap to allow airflow, but block noise, but I expect that isn't allowed.
> 
> I'll look into adding some drywall at the top. Might be possible to added some padding on the air return feed too (to the right that I didn't take a picture of). Is there duct padding that is code rated?


Yes, you need some kind of airflow around the unit.

Padding... that's a loaded question.  Depends on what you are trying to accomplish, what type of 'padding' you are referring to exactly, and where/how it would be installed. That said, there are insulated products designed to wrap around ductwork if that is what you're talking about. The issue is using them in a manner that is allowed. What I'd suggest is that you first figure out what you're trying to accomplish, then look for products that could facilitate your goal(s), and then before you purchase or install anything dig through your local building codes. HVAC has a whole bunch of codes that apply to it: everything from gas line pressure testing to routing your ducts between floors. One thing I believe it doesn't cover (oddly) is how to seal your duct connections and registers from leaking all over the place, nor does it cover similar issues such as preventing constriction of flex duct (two issues that ought to be very important to every homeowner).

Quick thought: make sure any padding or sound-proofing you are thinking of installing will be secured so that it can't move easily. In your case, with limited access space that might be a challenge. This is something that can easily trip up folks when getting fire-code inspections for insulation. If it can conceivably move or fall out of position on its own, it's a fail. That may not impact you now, but consider whether or not a home inspector could flag it when you are in the process of selling your home sometime down the road.


----------



## El Kay

*Condo Soundproofing Question*

I get a lot of airborne and structural noise through the party wall in my condo's bedroom that is shared with the neighbor's bedroom wall. My condo is only 508 square feet so space is an issue. 

I've taken the drywall down on this wall and discovered there are two rows of steel studs, but they have been laterally "strapped" together with pieces of drywall. The condo corp told me I am not allowed to remove these straps. I understand having these is bad for soundproofing so I am trying to figure out a way to work around these to still de-couple the wall to try and reduce all the structural noise (the wall shakes every time the neighbors open and close their bedroom door, or when they jump on their bed that is pressed against the wall). I can also hear all conversations, music, TV etc. 

I am debating between sound clips or resilient channel and wondering if anyone has any advice about which is better. I then plan to use green-glue between two layers of drywall. 

One other complicating factor is there is a bulkhead at the top of the wall that contains a duct running parallel to the wall - see pictures. I'm not sure if I should use the rc/sound clips around this area as well. 

Any advice would be great!


----------



## HT Geek

El Kay said:


> I get a lot of airborne and structural noise through the party wall in my condo's bedroom that is shared with the neighbor's bedroom wall. My condo is only 508 square feet so space is an issue.
> 
> I've taken the drywall down on this wall and discovered there are two rows of steel studs, but they have been laterally "strapped" together with pieces of drywall. The condo corp told me I am not allowed to remove these straps. I understand having these is bad for soundproofing so I am trying to figure out a way to work around these to still de-couple the wall to try and reduce all the structural noise (the wall shakes every time the neighbors open and close their bedroom door, or when they jump on their bed that is pressed against the wall). I can also hear all conversations, music, TV etc.
> 
> I am debating between sound clips or resilient channel and wondering if anyone has any advice about which is better. I then plan to use green-glue between two layers of drywall.
> 
> One other complicating factor is there is a bulkhead at the top of the wall that contains a duct running parallel to the wall - see pictures. I'm not sure if I should use the rc/sound clips around this area as well.


El Kay,

Don't presume your condo association has _carte blanche_ to tell you what you can and can't do with your walls and ceiling. I've dealt with them regarding insurance claims and you'd be amazed at what they tell homeowners - things that have no basis in fact or law - and can even get homeowners in legal trouble. They have a tendency toward knee-jerk reactions to owners that they can't do things, but it's not uncommon for associations to be incorrect. Most of the time, you're not getting an educated opinion from them; you're getting either another condo owner who is freaked out you will do something that either lowers their property value or increases their HOA dues, OR you get a low level bureaucrat in a management organization who is clueless and trained to say 'no' to everything.

Now, stepping off my soap box.... First question is, what is the purpose of that drywall "strap?" And btw, drywall is not a strapping material. So, it's really not a strap. It's a piece of drywall. If you're talking about the small square piece at the ceiling area in photo # 1 , based on pure conjecture - and looking at your photos - I would venture it's purpose is one of 3 things: 1) fire blocking for some reason; 2) covering up a hole (possibly related to # 1); or 3) concealing or correcting a mistake made by the builder. I could be wrong. Take my comments for what they're worth. If you're talking about the drywall strips along the studs (vertically), I can only imagine those had something to do with securing the drywall on the wall - perhaps providing more surface area for drywall screws if there were drywall panels butt-jointed there (?). That's the only thing I can think of - admittedly I'm not intimately familiar with steel studs. I just have experience with idiot condo associations. 

That said, I don't believe it matters in the long run. My vote is you do clips & channel on the ceiling. You can do that and leave the mystery drywall "strap(s)" in place. And yes, you can and should use the clips & channel around the bulkhead as well.

Given your vibration issues, your best bet would really be an independent stud wall. However, given your abode's size, I'm presuming you'd prefer not to sacrifice 6" or so of interior space. Therefore, if you use clips, consider using a clip & channel layout that would support _three _layers of drywall, in case after you've roughed in 2 layers you are still bothered by the vibration/noise from the neighbors. I would think you'd be OK with 2 layers on the ceiling.


----------



## jrref

El Kay said:


> I get a lot of airborne and structural noise through the party wall in my condo's bedroom that is shared with the neighbor's bedroom wall. My condo is only 508 square feet so space is an issue.
> 
> I've taken the drywall down on this wall and discovered there are two rows of steel studs, but they have been laterally "strapped" together with pieces of drywall. The condo corp told me I am not allowed to remove these straps. I understand having these is bad for soundproofing so I am trying to figure out a way to work around these to still de-couple the wall to try and reduce all the structural noise (the wall shakes every time the neighbors open and close their bedroom door, or when they jump on their bed that is pressed against the wall). I can also hear all conversations, music, TV etc.
> 
> I am debating between sound clips or resilient channel and wondering if anyone has any advice about which is better. I then plan to use green-glue between two layers of drywall.
> 
> One other complicating factor is there is a bulkhead at the top of the wall that contains a duct running parallel to the wall - see pictures. I'm not sure if I should use the rc/sound clips around this area as well.
> 
> Any advice would be great!


Those straps as you call them are there to add strength to the metal studs in the wall and yes that's bad for soundproofing. If I were you, I would build another wall in front of the existing wall, fill it with Roxul, use a single layer of 5/8 Quiet Rock and call it a day. If you do this you MUST leave an air gap of at least an inch beween the walls. Anything else you do will attenuate the noise but not as much as a separate floating wall. The only other thing you need to be aware of is that you and your neighbor share common floor and ceiling plates so you are going to get some flanking noise via that path and there is no way to get rid of that.


----------



## El Kay

HT Geek said:


> El Kay,
> 
> Don't presume your condo association has _carte blanche_ to tell you what you can and can't do with your walls and ceiling. I've dealt with them regarding insurance claims and you'd be amazed at what they tell homeowners - things that have no basis in fact or law - and can even get homeowners in legal trouble. They have a tendency toward knee-jerk reactions to owners that they can't do things, but it's not uncommon for associations to be incorrect. Most of the time, you're not getting an educated opinion from them; you're getting either another condo owner who is freaked out you will do something that either lowers their property value or increases their HOA dues, OR you get a low level bureaucrat in a management organization who is clueless and trained to say 'no' to everything.
> 
> Now, stepping off my soap box.... First question is, what is the purpose of that drywall "strap?" And btw, drywall is not a strapping material. So, it's really not a strap. It's a piece of drywall. If you're talking about the small square piece at the ceiling area in photo # 1 , based on pure conjecture - and looking at your photos - I would venture it's purpose is one of 3 things: 1) fire blocking for some reason; 2) covering up a hole (possibly related to # 1); or 3) concealing or correcting a mistake made by the builder. I could be wrong. Take my comments for what they're worth. If you're talking about the drywall strips along the studs (vertically), I can only imagine those had something to do with securing the drywall on the wall - perhaps providing more surface area for drywall screws if there were drywall panels butt-jointed there (?). That's the only thing I can think of - admittedly I'm not intimately familiar with steel studs. I just have experience with idiot condo associations.
> 
> That said, I don't believe it matters in the long run. My vote is you do clips & channel on the ceiling. You can do that and leave the mystery drywall "strap(s)" in place. And yes, you can and should use the clips & channel around the bulkhead as well.
> 
> Given your vibration issues, your best bet would really be an independent stud wall. However, given your abode's size, I'm presuming you'd prefer not to sacrifice 6" or so of interior space. Therefore, if you use clips, consider using a clip & channel layout that would support _three _layers of drywall, in case after you've roughed in 2 layers you are still bothered by the vibration/noise from the neighbors. I would think you'd be OK with 2 layers on the ceiling.


Condo associations are the worst! Complete nightmare having to go through them for everything. The straps are in picture 2 - the picture loaded sideways unfortunately so it's a bit hard to see. They go laterally attaching each of the studs in my unit to each of the studs in the 2nd row (the neighbor's). The condo association had their engineer look at the drawings (the builder included the straps in the original construction drawings) and their purpose is to "reinforce the studs as they would be be too flimsy on their own." 

I actually only own from the back of the drywall in to the unit so I can't modify anything behind the drywall without the association's approval. 

And yes, I'd love to be able to build an independent wall, but there really isn't any space 

Are you suggesting doing the entire ceiling? I hadn't planned on touching the ceiling... just the shared wall. My contractor is a big fan of using resilient channel, but he doesn't like clips for some reason. Is there a big difference?

Thanks for your help so far!


----------



## HT Geek

El Kay said:


> The condo association had their engineer look at the drawings (the builder included the straps in the original construction drawings) and their purpose is to "reinforce the studs as they would be be too flimsy on their own."


Since when does any condo association have an 'engineer' on staff? Are we talking about a Thomas The Tank Engine engineer or a structural engineer? Personally, I don't know of any certified structural engineers that would sign off on plans for structural supports made of drywall, and I've never heard of a condo association hiring an on-staff structural engineer. Why would they need one? Is your building regularly falling apart or being remodeled? Sounds like B.S. to me.




> I actually only own from the back of the drywall in to the unit so I can't modify anything behind the drywall without the association's approval.


Ok. So, that is the meat of the issue then in reality. Though this begs the question, how would they know if you did modify that 'strap'? Just sayin'.

Is there more than one of those drywall connectors? The photo looks like it's just in the corner. Anyway, the point of it seems to be someone decided those studs should be connected. Using clips & channel, you'll get around that concern so that would make it essentially a non-issue anyway.




> And yes, I'd love to be able to build an independent wall, but there really isn't any space


For some reason I thought you were also planning to do the ceiling, but I may have mixed up your scenario with someone else's. Sorry! If you have sound transmission issues via the ceiling, you could apply the same techniques we are discussing for your walls. No need to if you don't want to though. Just keep in mind you may still get some flanking noise via your ceiling/wall connection if the ceiling is not also decoupled.



> Are you suggesting doing the entire ceiling? I hadn't planned on touching the ceiling... just the shared wall. My contractor is a big fan of using resilient channel, but he doesn't like clips for some reason. Is there a big difference?


Yes. Clips are more work. 

Seriously, there are several reasons many contractors don't use clips & channel. Primarily, because they are more labor, which means higher cost to the customer, which turns off many customers, which means the contractor loses business. Translation: don't offer it. Another big reason is lack of familiarity and clips & channel installs are simply more complex, regardless of cost and time. Material costs are also a multiple (for c&c vs. RC).

From a sound-proofing perspective, clips are better for a couple of reasons. First, they introduce a greater physical separation between the wall stud and whatever you're attaching to the channel. RC is attached directly to the studs. It's a subtle difference, but essentially the part that you screw your decoupled drywall into is - with clips and channel - separated by a 2nd layer of materials as compared with resilient channel.

Here is RC:

STUD
RC
DRYWALL

and here is clips & channel:

STUD
CLIP
CHANNEL
DRYWALL

I hope that helps clarify. The additional layer of separation attenuates sound transmission better. Furthermore, most clips have a rubber base where it attaches to the stud, and that helps dampen sound even further (the cheapo clips don't but nearly all of the clips do have the rubber base).

RC is not terrible. It used to be terrible, but the current (2nd) generation of RC has gotten past the class action lawsuits. It is a viable product for some circumstances (but not recommended for yours). Another factor is that >1 layer of drywall on RC starts to become dicey. RC is typically not rated for more than 2 layers of drywall max, and sometimes just one. You should double-check with the manufacturer if you go with RC and before you try and attach 2 layers of drywall + GG to RC.

Also, do your homework on steel gauge of either RC or hat channel. Verify what your contractor is going to install is rated for your intended use. Trust but verify.


----------



## snailpail

HT Geek said:


> First off, don't do that. MLV on walls is only marginally useful and that's in a lab. It is very difficult to get it installed correctly, and by correctly I mean where you will reap a gain in the real world. Just don't do it. It is not worth the cost, effort, and time for a high chance of very little to no value.
> 
> 
> 
> More details/a little clearer explanation would be helpful. For example, did you install your DD+GG/clips & channel on top of your existing ceiling drywall? Or did you strip your ceiling down to the studs first?
> 
> 
> 
> I don't understand what you mean by that exactly. Could you elaborate? Are you talking about the walls, the ceiling???
> 
> BTW, the 'lighter stuff' drywall is counter-productive to sound isolation/damping. You want the heavier drywall.


 I stripped it down to the joists and removed the strapping.


Then I installed the Roxsul, clips and channel.


Then cut away the top 4 inches of the wall where it meets the ceiling, all the way around the room and installed the first layer of ceiling drywall so that the edges were flush with the framing. And caulked it.


Then, demo'd the walls and hung new drywall flush with the new ceiling. Caulked it.


Then applied green glue to the second layer of ceiling drywall and installed that and caulked that.


----------



## snailpail

Livin said:


> I'm about to tear out my current ceiling and do what you did... Hope it's worth it?
> 
> A few questions...
> 
> Did the new ceiling greatly improve the footfall and voices from above?
> 
> Can you post a diagram showing what you did when you removed the wall tops and added a seal? and the step effect?
> 
> Thx


I didn't add a seal, I just installed the drywall flush to the framing and caulked it with soundproof caulk. Then added the walls. Then the 2nd layer of ceiling drywall. That created what's referred to as the step effect along the corner joints.


The footfall is reduced significantly, but not perfect, more on that in a minute. Everything else is absolutely silent. It was silent with one layer of drywall. I just added the second layer to get rid of some of the deflection sound I was getting. Deflection is when the ceiling moves downward like a speaker. I guess my joists are soft wood. Pine probably. Should have reinstalled a few strips of strapping between the channels to add stiffness. Hindsight is 20/20.


Also, I would have installed sheets of drywall right to the bottom of the subfloor to block and absorb the impact noise. That's actually the first thing you should do if you decide to do the project. Hope that helps. Good luck.


----------



## HT Geek

jrref said:


> If I were you, I would build another wall in front of the existing wall, fill it with Roxul, use a single layer of 5/8 Quiet Rock and call it a day. If you do this you MUST leave an air gap of at least an inch beween the walls.


An inch is not the minimum. There really is no minimum, other than there needs to be a physical separation. An inch is touted as the standard because it allows a sufficient margin-of-error for most installations. The vast majority of wood studs are not particularly straight across 8, 9, or 10 foot lengths; the exception being engineered wood studs and beams. I wouldn't want less than a 1/4" gap when said-and-done, as there may be movement or deflection after the walls are up. Point is you can get away with


----------



## El Kay

jrref said:


> Those straps as you call them are there to add strength to the metal studs in the wall and yes that's bad for soundproofing. If I were you, I would build another wall in front of the existing wall, fill it with Roxul, use a single layer of 5/8 Quiet Rock and call it a day. If you do this you MUST leave an air gap of at least an inch beween the walls. Anything else you do will attenuate the noise but not as much as a separate floating wall. The only other thing you need to be aware of is that you and your neighbor share common floor and ceiling plates so you are going to get some flanking noise via that path and there is no way to get rid of that.


Thanks for the input! Unfortunately I don't have the space to build another wall in front of the wall, otherwise this is the method I would use. My condo is only 508 square feet, so losing that much space wouldn't be good for resale... and would mean the end of my bed would touch the wall, if it would even fit at all.


----------



## El Kay

HT Geek said:


> Since when does any condo association have an 'engineer' on staff? Are we talking about a Thomas The Tank Engine engineer or a structural engineer? Personally, I don't know of any certified structural engineers that would sign off on plans for structural supports made of drywall, and I've never heard of a condo association hiring an on-staff structural engineer. Why would they need one? Is your building regularly falling apart or being remodeled? Sounds like B.S. to me.
> 
> Lol... the property management company they hired does apparently actually have an engineer they use.
> 
> 
> 
> Ok. So, that is the meat of the issue then in reality. Though this begs the question, how would they know if you did modify that 'strap'? Just sayin'.
> 
> Ya, i've thought about this a lot... they likely wouldn't unless someone down the road opened the wall up.
> 
> Is there more than one of those drywall connectors? The photo looks like it's just in the corner. Anyway, the point of it seems to be someone decided those studs should be connected. Using clips & channel, you'll get around that concern so that would make it essentially a non-issue anyway.
> 
> Yes there are 2 per stud... so lots!
> 
> 
> 
> For some reason I thought you were also planning to do the ceiling, but I may have mixed up your scenario with someone else's. Sorry! If you have sound transmission issues via the ceiling, you could apply the same techniques we are discussing for your walls. No need to if you don't want to though. Just keep in mind you may still get some flanking noise via your ceiling/wall connection if the ceiling is not also decoupled.
> 
> I wasn't planning on doing the ceiling. One issue i noticed when I was there today is the bulkhead goes all the way around the room at the top of each wall... so if i did use the clips on the part above the shared wall, it would be lower than the rest of the bulkhead. So it's do the entire thing or nothing. Not sure I can afford to do the whole thing tho
> 
> Yes. Clips are more work.
> 
> Seriously, there are several reasons many contractors don't use clips & channel. Primarily, because they are more labor, which means higher cost to the customer, which turns off many customers, which means the contractor loses business. Translation: don't offer it. Another big reason is lack of familiarity and clips & channel installs are simply more complex, regardless of cost and time. Material costs are also a multiple (for c&c vs. RC).
> 
> From a sound-proofing perspective, clips are better for a couple of reasons. First, they introduce a greater physical separation between the wall stud and whatever you're attaching to the channel. RC is attached directly to the studs. It's a subtle difference, but essentially the part that you screw your decoupled drywall into is - with clips and channel - separated by a 2nd layer of materials as compared with resilient channel.
> 
> Here is RC:
> 
> STUD
> RC
> DRYWALL
> 
> and here is clips & channel:
> 
> STUD
> CLIP
> CHANNEL
> DRYWALL
> 
> I hope that helps clarify. The additional layer of separation attenuates sound transmission better. Furthermore, most clips have a rubber base where it attaches to the stud, and that helps dampen sound even further (the cheapo clips don't but nearly all of the clips do have the rubber base).
> 
> RC is not terrible. It used to be terrible, but the current (2nd) generation of RC has gotten past the class action lawsuits. It is a viable product for some circumstances (but not recommended for yours). Another factor is that >1 layer of drywall on RC starts to become dicey. RC is typically not rated for more than 2 layers of drywall max, and sometimes just one. You should double-check with the manufacturer if you go with RC and before you try and attach 2 layers of drywall + GG to RC.
> 
> Also, do your homework on steel gauge of either RC or hat channel. Verify what your contractor is going to install is rated for your intended use. Trust but verify.


Thanks for this advice! I will talk to my contractor about using clips and find out what model he is planning on.


----------



## Livin

snailpail said:


> I didn't add a seal, I just installed the drywall flush to the framing and caulked it with soundproof caulk. Then added the walls. Then the 2nd layer of ceiling drywall. That created what's referred to as the step effect along the corner joints.
> 
> 
> The footfall is reduced significantly, but not perfect, more on that in a minute. Everything else is absolutely silent. It was silent with one layer of drywall. I just added the second layer to get rid of some of the deflection sound I was getting. Deflection is when the ceiling moves downward like a speaker. I guess my joists are soft wood. Pine probably. Should have reinstalled a few strips of strapping between the channels to add stiffness. Hindsight is 20/20.
> 
> 
> Also, I would have installed sheets of drywall right to the bottom of the subfloor to block and absorb the impact noise. That's actually the first thing you should do if you decide to do the project. Hope that helps. Good luck.


What benefit does the step effect have? 

I have iJoists... Does adding some cross bracing benefit me? 
I'm planning to use 2x4 on the top of the horizontal part of the iJoists as the blocks for the clips so I can reduce height loss. I'm thinking the blocks 2x4s will add some stiffness (reduce flex)... Am I correct? Worth doing? 

Thx


----------



## snailpail

Livin said:


> What benefit does the step effect have?
> 
> I have iJoists... Does adding some cross bracing benefit me?
> I'm planning to use 2x4 on the top of the horizontal part of the iJoists as the blocks for the clips so I can reduce height loss. I'm thinking the blocks 2x4s will add some stiffness (reduce flex)... Am I correct? Worth doing?
> 
> Thx


I'm not an expert on the subject, I'm just passing along what I've learned by researching my project. But that sounds like it would add stiffness if you mean joist to joist. Prolly should pre-drill everything too so you dont crack the joists.

The step effect helps block sound leakage by sealing the corners with layers of mass.


----------



## jimmyaz

Hey guys, 

I have recently upgraded my sound system, including the subwoofer, so thing has been getting louder around the house.

My home theater located in the front of the house next to the garage. One wall is tie to the laundry room, the other one tie to the garage. The access is open 6x6ft open (tie to the Foyer), which I have put up some thick curtain. I have been up in my attic and my cellulose insulation has settle quite a bit, now only about 6-7inches deep. Also, there's no insulation in the wall that's tie to the laundry room. 

I was thinking maybe because the low R values on the attic over this room and the empty wall is letting extra sound to the rest of the house. Also, it's 3degrees hotter than the rest of the house most of the time. I was wondering if I add more cellulose on the attic, would it help? What about the wall? should I fill this with cellulose as well?

Or it won't matter what I do to them wall/attic if I don't put up a door to seal the 6x6 open?

thanks


----------



## HT Geek

jimmyaz said:


> My home theater located in the front of the house next to the garage. One wall is tie to the laundry room, the other one tie to the garage. The access is open 6x6ft open (tie to the Foyer), which I have put up some thick curtain. I have been up in my attic and my cellulose insulation has settle quite a bit, now only about 6-7inches deep. Also, there's no insulation in the wall that's tie to the laundry room.
> 
> I was thinking maybe because the low R values on the attic over this room and the empty wall is letting extra sound to the rest of the house. Also, it's 3degrees hotter than the rest of the house most of the time. I was wondering if I add more cellulose on the attic, would it help? What about the wall? should I fill this with cellulose as well?
> 
> Or it won't matter what I do to them wall/attic if I don't put up a door to seal the 6x6 open?


Well, answers to questions like yours are always complicated by the fact there are many details related to sound transmission & building construction, plus your interpretation of "quiet" vs. "loud", etc. That said, here are my thoughts on your best bets to _improve _your current situation (in order of effectiveness where 1 = best/most important):

1. Shrink your opening. Ideally, install a solid wood door and make the remainder a wall. Make sure the door is solid. You'll also need gaskets all around. The best types include self-sealing door bottoms. You can find information about these and door sealing in general elsewhere on the AVS forum. Heavy curtains are good (what you have), but appropriately sealed solid doors are better.

2. Consider upgrading your walls in your HT room to double stud, staggered stud walls, or clips & channel. You ought to at least install some insulation in that shared wall that is not insulated. It won't be a tremendous improvement, but it should be noticeable. Use fiberglass insulation (batts), not the blown-in cellulose. If you want even better performance, use rockwool or a similar product (mineral wool). However, if you are cost conscious, the fiberglass insulation will do well at 1/2 the price (or less) than a rockwool product. I suggest not using blown in cellulose because it makes a mess. I hate that stuff (i.e. I'm biased). 

3. Regarding your attic insulation: depending on your climate, 6-7" is very little. Actually, I'd say virtually any climate that is going to give you under-performance. It likely won't do much for diminishing sound transmission, but adding to that ought to improve your comfort.


----------



## Death Dream

What clips and furring channel is everyone using? I see a few different variations on the clips and it only looks like Menards is carrying the channel in my area (http://www.menards.com/main/buildin...4426600961-c-5695.htm?tid=5781668379242191787).


----------



## HT Geek

kmhvball said:


> Simply for ease of cutting and screwing through, I would do drywall... around here it is cheaper too, but guess that isn't the case for you.
> 
> Performance wise, if greater mass, might be better... not worth it in my opinion though


^^^ After building 6 backer boxes for Atmos speakers out of cement board, I agree wholeheartedly. Not worth the trouble.


----------



## HT Geek

Death Dream said:


> What clips and furring channel is everyone using? I see a few different variations on the clips and it only looks like Menards is carrying the channel in my area (http://www.menards.com/main/buildin...4426600961-c-5695.htm?tid=5781668379242191787).


There's a small variety. The most important point is to use clips & channel versus resilient channel (RC). That said... the 'channel' part you ideally want to source locally. I believe 25 gauge steel 'hat channel' is the standard.

The clips are the part that you can find different variations and sources, depending on your needs/preferences. I'd say it mostly boils down to cost and clip design. The biggest cost differential is whether or not there is a rubber or foam isolation on the clip itself. The 'el cheapo' clips (~$2 USD per clip) do not have any rubber or foam on them. Next there is the question of one screw attaching the clip to the hat channel, or two screws? The '2 screw' variants typically cost more.

Finally, there is the design... but presuming you're talking about standard shapes and not L-shape, etc. then what I described above - from what I've seen - is about it.

Now, all that's my personal opinion ... and let me say that I have ZERO experience installing these clips, but I have read a heckuvalot about them on AVS, and researched their cost, etc. for some time. LOL. 

Your best bet is to pick out what you think you want and ask pointed/specific questions here on those item(s).


----------



## hatlesschimp

I have sound proofing batts in my walls and ceiling and 2 layers of 10mm plaster. What else can I do to add to the sound proofing and also prevent reflections inside the room. Thanks lads.


----------



## kmhvball

Death Dream said:


> What clips and furring channel is everyone using? I see a few different variations on the clips and it only looks like Menards is carrying the channel in my area (http://www.menards.com/main/buildin...4426600961-c-5695.htm?tid=5781668379242191787).


I used the cheapest ones from the soundproofingcompany.com... with unlimited budget, Ted recommended their Whisper clips, but if I had to make budget choices, he said going with cheaper clips would be the first change he would recommend. YMMV.


----------



## snailpail

Death Dream said:


> What clips and furring channel is everyone using? I see a few different variations on the clips and it only looks like Menards is carrying the channel in my area (http://www.menards.com/main/buildin...26600961-c-5695.htm?tid=5781668379242191787).


RSIC-1's and 25 gauge hat channel. Got them from Kamco.
https://www.kamcoboston.com/
Dana Wallboard is another good place for drywall stuff.
http://www.danawallboard.com/


----------



## Sundodger

I am in the planning stages of a basement home theater and am planning on a fair amount of soundproofing so I don't wake the kids. Planning to decouple walls from joists and for the ceiling I will try to do 5/8 DD/GG; hat channel and insulation (plus backer boxes for lights and 2 ceiling speakers). 

In the current setup I won't have a door separating the room from the stairs leading to the main floor (there will be thin doors in the hall upstairs). Will the lack of a basement door just wipe out any soundproofing I'm trying to accomplish? Obviously not ideal, but there would be a bit of distance up the stairs, down the hall, to the bedrooms...

Thoughts? (I can start a separate thread if appropriate).

Thanks!


----------



## HT Geek

hatlesschimp said:


> I have sound proofing batts in my walls and ceiling and 2 layers of 10mm plaster. What else can I do to add to the sound proofing and also prevent reflections inside the room. Thanks lads.


In no particular order:


3rd layer of plaster (i.e. more mass)
Strategically placed sound absorbing/reflecting/dispersing foam pads (requires audio analisys)
Acoustically transparent fabric on the walls, masking insulation, duct liner, or other sound-absorbing material
Turn the volume lower


----------



## HT Geek

Sundodger said:


> Will the lack of a basement door just wipe out any soundproofing I'm trying to accomplish?


Short answer: YES

Longer answer: Don't do it. The door will be a weak spot in general, no matter what you do. However, _a door_ is better than _no door_. Without a door, you will provide a conduit for sound to exit your HT room, and for sound outside your room to enter it.

To put it in perspective for you, I'm in the midst of constructing my HT room and there currently is no door. My walls are double-stud, and 2nd layer of drywall is up on most wall surfaces and most of the ceiling. When you're in the room, you'd almost think there was no sound proofing. Sure, the room is much more "dead" than it used to be, but you also still hear sounds from outside the room quite clearly. Having a 30 sq. ft. hole in one wall does not help sound proofing (3' x 10' ceiling atm). 

You WILL regret it if you don't plug that hole with a heavy door.


----------



## Sundodger

HT Geek said:


> Short answer: YES
> 
> You WILL regret it if you don't plug that hole with a heavy door.


Thanks, I think that confirms what I already knew. Now I just need to figure out to either configure it so the door doesn't swing out over the top of the stairs, or create a small landing in the basement closed off by a door. That would make it tough to move furniture in and out, but maybe doable. 

I should probably SketchUp my layout and start a new thread for more suggestions.

Thanks!


----------



## pacmanprince

Hello,

The door to my bedroom doesn't exactly fit the doorway, and has a small gap at the bottom from the floor where a lot of sound leaks out. I was wondering if I could get something of custom dimensions (basically a 3d rectangular shaped foam or something like that) which I will then affix to the bottom of the door with some 3M or something of that nature to "fill in" that gap. Do you guys know where/what I could get something to help my situation? Thanks for any help.


----------



## HT Geek

pacmanprince said:


> Hello,
> 
> The door to my bedroom doesn't exactly fit the doorway, and has a small gap at the bottom from the floor where a lot of sound leaks out. I was wondering if I could get something of custom dimensions (basically a 3d rectangular shaped foam or something like that) which I will then affix to the bottom of the door with some 3M or something of that nature to "fill in" that gap. Do you guys know where/what I could get something to help my situation? Thanks for any help.


For a "low tech" solution, you could do as you described. You ought to be able to find something suitable at one of the big box hardware stores.

A "higher tech" option would be to look into some suppliers such as Zero Noise.


----------



## pacmanprince

HT Geek said:


> For a "low tech" solution, you could do as you described. You ought to be able to find something suitable at one of the big box hardware stores.
> 
> A "higher tech" option would be to look into some suppliers such as Zero Noise.


Thanks! I contacted them


----------



## donktard

I have a room (wooden cabin) approximately 18' x 10.5' x 6.5'
What would be my best options regarding some solid soundproofing? Decoupling is obviously out of the question.
I plan to listen at reference levels, I don't mind sharing some bass with neighbors but I would still prefer a decent sound isolation, as much as its possible with room of such dimensions.
I should also mention, although heigh (6.5") is an issue, I can isolate ceiling from topside (attic).


----------



## HT Geek

donktard said:


> I have a room (wooden cabin) approximately 18' x 10.5' x 6.5'
> What would be my best options regarding some solid soundproofing? Decoupling is obviously out of the question.
> I plan to listen at reference levels, I don't mind sharing some bass with neighbors but I would still prefer a decent sound isolation, as much as its possible with room of such dimensions.
> I should also mention, although heigh (6.5") is an issue, I can isolate ceiling from topside (attic).


Donk,

I see you're in Croatia. Beautiful country. 

Now, to your HT.... we need to first establish some details of your scenario.



Is this a single-room wood cabin that will be a dedicated listening room, or is this a portion of a larger structure?
Is the interior currently finished? Is 6' 6" your finished floor to ceiling height, or unfinished floor to ceiling, etc.? BTW, I don't have any issues with metric personally if that is easier for you. 
Is your interior a perfect rectangle? Is it currently empty? Unfinished?
Can you post some photos? That would certainly help. For instance, the first time I read your post, I pictured what we would call here in the States a Log Cabin, but that might not be the case. 
What are your aspirations with regards to this room?


----------



## donktard

HT Geek said:


> Donk,
> 
> I see you're in Croatia. Beautiful country.
> 
> Now, to your HT.... we need to first establish some details of your scenario.
> 
> 
> 
> Is this a single-room wood cabin that will be a dedicated listening room, or is this a portion of a larger structure?
> Is the interior currently finished? Is 6' 6" your finished floor to ceiling height, or unfinished floor to ceiling, etc.? BTW, I don't have any issues with metric personally if that is easier for you.
> Is your interior a perfect rectangle? Is it currently empty? Unfinished?
> Can you post some photos? That would certainly help. For instance, the first time I read your post, I pictured what we would call here in the States a Log Cabin, but that might not be the case.
> What are your aspirations with regards to this room?


Hi,

Thank you. It surely is. Have you ever been to Croatia?

1. It pretty much looks like this (but this one is not mine, will post pictures tomorrow)
http://www.njuskalo.hr/image-bigger...ra-drvena-kuca-preseljenje-slika-24643073.jpg
with one significant difference. When you enter through door (same placement like on picture), first you enter a porch, wide as a cabin, about 2 feet long, and then you enter the main room. So basically, its a single structure.

2. Yeah, we can do metrics. Room size is 6 x 3.5 x 2.1 meters. Now this is tricky (pictures tomorrow ), on ceiling there is a long beam that travels across largest room dimension (6m). That wooden beam is at 2.1 m height. The rest of the ceiling is actually somewhat higher...between 2.4-2.7 m.
Floor is covered in laminate, but i think below it is either dirt or concrete...so theoretically I could dig it up somewhat if i want more height. Inside walls are covered in layer of plaster (10cm thick wood beams).
3. It is a very very old cabin (>50 years) and is currently used for storage for bunch of my old mans junk he never uses. It has electricity.
5. Well, I want to turn it into a nice movie theater, reference levels, projector, surrounds, atmos (if possible because height), 2-4 subs, up to 6 seats. And possibly, but not necessarily it could double as a critical listening (control) room for some amateur studio stuff.


----------



## HT Geek

donktard said:


> Hi,
> 
> Thank you. It surely is. Have you ever been to Croatia?


No, but it's on my bucket list! A good friend of mine just returned from visiting family in Croatia, so I have seen many photos!



> 1. It pretty much looks like this (but this one is not mine, will post pictures tomorrow)
> http://www.njuskalo.hr/image-bigger...ra-drvena-kuca-preseljenje-slika-24643073.jpg
> with one significant difference. When you enter through door (same placement like on picture), first you enter a porch, wide as a cabin, about 2 feet long, and then you enter the main room. So basically, its a single structure.
> 
> 2. Yeah, we can do metrics. Room size is 6 x 3.5 x 2.1 meters. Now this is tricky (pictures tomorrow ), on ceiling there is a long beam that travels across largest room dimension (6m). That wooden beam is at 2.1 m height. The rest of the ceiling is actually somewhat higher...between 2.4-2.7 m.
> Floor is covered in laminate, but i think below it is either dirt or concrete...so theoretically I could dig it up somewhat if i want more height. Inside walls are covered in layer of plaster (10cm thick wood beams).
> 3. It is a very very old cabin (>50 years) and is currently used for storage for bunch of my old mans junk he never uses. It has electricity.
> 5. Well, I want to turn it into a nice movie theater, reference levels, projector, surrounds, atmos (if possible because height), 2-4 subs, up to 6 seats. And possibly, but not necessarily it could double as a critical listening (control) room for some amateur studio stuff.


Ok. That's more like it.... 

So, I suspect moving the center cross-beam is out-of-the-question. It would be good if your roof remained intact, eh? 

Is your ceiling open? Is it an exposed beam and then the roof? Or is there a ceiling across the structure at the 2.1 meter height?

I don't see any particular reason to remove your existing floor. You probably should consider removing the 'porch' as you described it (presuming an interior feature) to provide more room. The more width you can free up, the more sound deadening materials you can add!

What are you thinking of using to add mass to the walls and/or ceiling? More mass will do a better job of dampening sound from travelling into or out of your theater. 

What is the range for your budget, and how much work do you plan to do yourself vs. pay others?

What are your minimum requirements for "success" and what is your dream vision, relative to sound-proofing? I know you already gave some direction, but what is your dream?

If you add wall material, would it be plaster? In the U.S., you probably know we predominantly use gypsum board ("drywall") though occasionally plaster is used.

Photos will help alot.


----------



## donktard

HT Geek said:


> No, but it's on my bucket list! A good friend of mine just returned from visiting family in Croatia, so I have seen many photos!
> 
> 
> 
> Ok. That's more like it....
> 
> So, I suspect moving the center cross-beam is out-of-the-question. It would be good if your roof remained intact, eh?
> 
> Is your ceiling open? Is it an exposed beam and then the roof? Or is there a ceiling across the structure at the 2.1 meter height?


Nice. Make sure to ask me for recommendations for places to visit. 

Now, onto the business. Here are the photos.
Currently it looks like something out of a horror movie which coincidentally would be a great HT theme.
First, some thoughts. Removing interior wall would be ideal. Not sure if its structurally important but from the looks of it, the outer wall, the one with many windows can hold his own.
Then all those windows would be removed and sealed. That would also be more expensive option, but I have to look into some of the unexpected expenses I am predicting for this job.
Regarding soundproofing the ceiling. I would make the ceiling wall flush with the lowest beam, so all sounproofing material goes above it and in attic if necessary.



HT Geek said:


> I don't see any particular reason to remove your existing floor. You probably should consider removing the 'porch' as you described it (presuming an interior feature) to provide more room. The more width you can free up, the more sound deadening materials you can add!


Current floor has to be removed, its pretty terrible. Carpet on top is a must. 



HT Geek said:


> What are you thinking of using to add mass to the walls and/or ceiling? More mass will do a better job of dampening sound from travelling into or out of your theater.


I have no clue. Thats why I am asking here hehe. Is mass the primary isolator, or is it the combination of materials/layers I should be using? And also how thick mass are we talking about?
In my house, the layers I know of are: brick (the big one with lots of holes), glassfiber (prob 2"), wood paneling, plus whatever is on outside. It makes a pretty good job of containing loud noises in and out when i go crazy with music/movies.



HT Geek said:


> What is the range for your budget, and how much work do you plan to do yourself vs. pay others?


Undetermined yet. But as a rule of thumb if i job is too complex or too time consuming I pay someone else to do it. 



HT Geek said:


> What are your minimum requirements for "success" and what is your dream vision, relative to sound-proofing? I know you already gave some direction, but what is your dream?


You ask specifically for soundproofing? If that is the case, my goal is pretty much not to have noise complaints from neighbors while listening at reference-near reference levels. While nearest neighbor is 30-50 meters away (and noone complained yet), I have tenants that are positioned much closer (10-15m away). During day no-one will be bothered, but it would still be decent to contain 100% of upper and mid range and most of the upper bass. And ideally, I'd prefer to watch anything anytime without disturbing those tenants that are closest, and given my schedule I am often awake until 04:00 in the morning and could sometimes decide to take an hour or two to see a movie or tv show.



HT Geek said:


> If you add wall material, would it be plaster? In the U.S., you probably know we predominantly use gypsum board ("drywall") though occasionally plaster is used.


I suppose so. Whatever it is, I know that on top of it I am placing serious amount of acoustic treatments.


----------



## HT Geek

donktard said:


> Now, onto the business. Here are the photos.


Looks like quite a project you have on your hands. 



> Currently it looks like something out of a horror movie which coincidentally would be a great HT theme.


Yeah. I think this is gonna be an awesome transformation when you're done; especially if you leave the outside appearance as-is. 



> First, some thoughts. Removing interior wall would be ideal. Not sure if its structurally important but from the looks of it, the outer wall, the one with many windows can hold his own.


I can't tell from your photos if the wall between the interior "porch" and the main part of the structure is load-bearing or not. That is something you should investigate prior to ripping it out.



> Then all those windows would be removed and sealed. That would also be more expensive option, but I have to look into some of the unexpected expenses I am predicting for this job.


Based on what I can see, it appears to me you could remove the frame on the inside, but you would still need to cover and sound-proof the windows. In other words, some effort and cost will be required either way (whether you remove the windows and seal the space or not). The upside to leaving the windows there is the building could be converted back in the future if desired (though I can't imagine why anyone would want to; lol).



> Regarding soundproofing the ceiling. I would make the ceiling wall flush with the lowest beam, so all sounproofing material goes above it and in attic if necessary.


Makes sense, though I personally find those old wood beams to be quite beautiful. You could consider leaving them exposed, for a bit of a rustic effect.

Speaking of the attic, is there access to it from the ground floor (inside the building)? What are your plans for the attic?



> Current floor has to be removed, its pretty terrible. Carpet on top is a must.


Ok. Well, carpet & pad on concrete is straightforward/easy.



> I have no clue. Thats why I am asking here hehe. Is mass the primary isolator, or is it the combination of materials/layers I should be using? And also how thick mass are we talking about?


Essentially, you want both. Mass is required to attenuate low frequency emissions (LFE). Multiple layers of different materials helps to attenuate mid and high frequency emissions. For example, the reason multiple layers of wallboard/drywall/plaster are recommended for sound-proofing is you're getting both qualities: multiple layers + mass. It used to be common to see recommendations for 1/2" and 5/8" layers of drywall for example, because the theory was different wall thicknesses would have slight (but useful) variations in the frequency range where each provided the best damping. And in fact - technically - that is true. However, since most people are concentrating on controlling LFE, generally speaking the recommendation now is typically for multiple layers of 5/8" drywall.

In your case, there is no point in decoupling your walls and ceiling, since your room is essentially the entire structure (with the exception of the attic).

You can find all sorts of advice on sound-proofing materials and techniques if you peruse this forum, but at a basic level I'd suggest 2x layers of plaster/drywall type of material + 1" thick Linacoustic (or similar product) to absorb some of HF bouncing off the walls. It's normally placed from the floor up to around ear-height when seated (but that said... please look around the forum... you should perform you own research when you get the point of interior sound-proofing above and beyond the wall covering).



> ... I have tenants that are positioned much closer (10-15m away). During day no-one will be bothered, but it would still be decent to contain 100% of upper and mid range and most of the upper bass. And ideally, I'd prefer to watch anything anytime without disturbing those tenants that are closest, and given my schedule I am often awake until 04:00 in the morning and could sometimes decide to take an hour or two to see a movie or tv show.


I would start with 2 layers of interior wall material (minimum thickness 13mm each), then crank up a test with speakers and see what you think of noise outside the structure.

Another area to think about is your door. It is always a weak spot with regards to HT rooms. You should look into options for sealing around the door, such as some beefy gaskets. There is a company called Zero Noise. Their website is worth looking through. Even if you don't order from them (shipping may be prohibitive), you can get some good ideas from there.


----------



## donktard

HT Geek said:


> Based on what I can see, it appears to me you could remove the frame on the inside, but you would still need to cover and sound-proof the windows. In other words, some effort and cost will be required either way (whether you remove the windows and seal the space or not). The upside to leaving the windows there is the building could be converted back in the future if desired (though I can't imagine why anyone would want to; lol).


I'd rather just remove them and replace with wooden beams...or couple of nice looking soundproofed windows.



HT Geek said:


> Makes sense, though I personally find those old wood beams to be quite beautiful. You could consider leaving them exposed, for a bit of a rustic effect.


While I like them too, I prioritize sonic quality of a room. Therefore I will definitely treat first reflections on walls and ceiling and possibly deaden a room further (like dead front end), once I look into it a bit more.
It would be amazing if I could place wooden diffusers up there to maintain the rustical feel, but that would then leave the problem of soundproofing the ceiling unsolved.
Unless you meant only to leave longest beam exposed and soundproof rest of the ceiling above it.



HT Geek said:


> Speaking of the attic, is there access to it from the ground floor (inside the building)? What are your plans for the attic?


I think there is but you need a ladder to get there. Sealing the ceiling would seal that too. I currently have no plans for attic, but any project up there would also require replacing those wooden boards outside and fixing roof if necessary.



HT Geek said:


> I would start with 2 layers of interior wall material (minimum thickness 13mm each), then crank up a test with speakers and see what you think of noise outside the structure.


I was thinking of taking subwoofer there while in its current state and crank it up to see if whole cabin falls apart. 



HT Geek said:


> Another area to think about is your door. It is always a weak spot with regards to HT rooms. You should look into options for sealing around the door, such as some beefy gaskets. There is a company called Zero Noise. Their website is worth looking through. Even if you don't order from them (shipping may be prohibitive), you can get some good ideas from there.


Yeah, I see another nasty expense there. Door might need to be custom made. Its actually one of the reasons for NOT removing porch...therefore I'd have double door to seal that off properly.

Thanks for all the help. Will definitely open a thread once i start working on it


----------



## healthnut

Hello all: I'm in the process of soundproofing my basement theater room. I'm using double layers of 5/8 drywall on walls that adjoin other rooms, plus the ceiling (along with isolation clips and green glue). Is it necessary to use a double layer of drywall on walls that lead to the outside? If I can use a single layer, it would save some labor and materials, thanks for any input. 


Sent from my iPhone using Tapatalk


----------



## HT Geek

healthnut said:


> Is it necessary to use a double layer of drywall on walls that lead to the outside?


Short answer: YES

Longer answer: The typical focus there is to isolate your room from outside noise. Have you ever sat in a quiet room with an exterior wall, with construction going on nearby (outside)? 

If your room is in a walk-up basement, you may actually be ok with just 1 layer. If it's an above-grade room then I'd say a 2nd layer is mandatory. 

Another way of looking at it is, why skimp on that one wall after you've gone to so much trouble for the other walls and ceiling?


----------



## kmhvball

healthnut said:


> Is it necessary to use a double layer of drywall on walls that lead to the outside?


Yes... 

I asked the same question when I was doing my basement theater... 2 1/2 walls were exterior walls. In addition to HTGeek's thoughts, the other thing I heard a lot, was that this could also create significant 'Flanking' noise. This is where noise works its way around any way it can... so, gets out the single layer drywall, which is likely also adjacent to an interior wall at some point... and makes it's way through there.

As mentioned, you have done some of the most expensive pieces (clips/ channel/ ceiling)... I would definitely not risk it by skimping on the last little bit.


----------



## healthnut

HT Geek said:


> Short answer: YES
> 
> 
> 
> Longer answer: The typical focus there is to isolate your room from outside noise. Have you ever sat in a quiet room with an exterior wall, with construction going on nearby (outside)?
> 
> 
> 
> If your room is in a walk-up basement, you may actually be ok with just 1 layer. If it's an above-grade room then I'd say a 2nd layer is mandatory.
> 
> 
> 
> Another way of looking at it is, why skimp on that one wall after you've gone to so much trouble for the other walls and ceiling?




Thanks, not the answer I wanted but the answer I needed!


Sent from my iPhone using Tapatalk


----------



## healthnut

kmhvball said:


> Yes...
> 
> I asked the same question when I was doing my basement theater... 2 1/2 walls were exterior walls. In addition to HTGeek's thoughts, the other thing I heard a lot, was that this could also create significant 'Flanking' noise. This is where noise works its way around any way it can... so, gets out the single layer drywall, which is likely also adjacent to an interior wall at some point... and makes it's way through there.
> 
> As mentioned, you have done some of the most expensive pieces (clips/ channel/ ceiling)... I would definitely not risk it by skimping on the last little bit.




Appreciate your insights: 2 layers all 'round it is!


Sent from my iPhone using Tapatalk


----------



## HT Geek

donktard said:


> I'd rather just remove them and replace with wooden beams...or couple of nice looking soundproofed windows.
> 
> While I like them too, I prioritize sonic quality of a room. Therefore I will definitely treat first reflections on walls and ceiling and possibly deaden a room further (like dead front end), once I look into it a bit more.
> It would be amazing if I could place wooden diffusers up there to maintain the rustical feel, but that would then leave the problem of soundproofing the ceiling unsolved.
> Unless you meant only to leave longest beam exposed and soundproof rest of the ceiling above it.


I was thinking you could leave the longest beam and smaller lateral beams exposed, with sound-proofing in between them. You could also add another layer of soundproofing on the attic floor. I was thinking of it from a cosmetic standpoint. From an audio standpoint, they certainly ought to break up reflections from the ceiling, but the effect they would have is unknown (at least to me). Another issue is of course headroom, and you could gain a few cm by filling in the cavities up to the point they are all level with the main beam, as you'd suggested earlier in this thread.



> I think there is but you need a ladder to get there. Sealing the ceiling would seal that too. I currently have no plans for attic, but any project up there would also require replacing those wooden boards outside and fixing roof if necessary.


Based on the photos, it looks like there is an attic access at one end of the exterior of the building, but again requiring a ladder. You could retain that access point so that you can still get into the attic somehow.



> Yeah, I see another nasty expense there. Door might need to be custom made. Its actually one of the reasons for NOT removing porch...therefore I'd have double door to seal that off properly.


Yes, I agree that's a good idea as well. I was thinking about that when I wrote my last reply, but left it off as the room is not that wide to begin with. But to your point, it would allow a double-door effect. Now that I think about this some more, you could also use some of that space to recess your A/V rack; essentially recess it into a portion of the interior 'porch.' Just seal off a small area, ideally at the rear of the room.

You also mentioned the possibility of a dead vent. I can only imagine that working if you still have the front porch area to use as part of the dead vent.

This reminds me, have you thought about HVAC? Is there any HVAC system in the building right now? If not, what type of system are you planning to use?




> Thanks for all the help. Will definitely open a thread once i start working on it


Awesome. I'm sure that will be a popular thread, because your starting point is so unique!


----------



## donktard

HT Geek said:


> I was thinking you could leave the longest beam and smaller lateral beams exposed, with sound-proofing in between them. You could also add another layer of soundproofing on the attic floor. I was thinking of it from a cosmetic standpoint. From an audio standpoint, they certainly ought to break up reflections from the ceiling, but the effect they would have is unknown (at least to me). Another issue is of course headroom, and you could gain a few cm by filling in the cavities up to the point they are all level with the main beam, as you'd suggested earlier in this thread.


Acoustically speaking, middle beam seems like pain in the ass to me, since I like to sit in the middle (obviously ), it will definitely reflect portion of a sound in an unwanted manner. As for the rest, yeah, I expect acoustical chaos up there, pretty hard to predict. It might be a good idea, if not too complicated, to soundproof just sidewalls and leave ceiling untreated. Then, get speakers in, make measurements and if it looks poor then build the ceiling as originally planned.




HT Geek said:


> Based on the photos, it looks like there is an attic access at one end of the exterior of the building, but again requiring a ladder. You could retain that access point so that you can still get into the attic somehow.


Yep. I recall its chaos up there, not flat floor but beams all around too (not sure really, been up there like 5 years ago ).




HT Geek said:


> Yes, I agree that's a good idea as well. I was thinking about that when I wrote my last reply, but left it off as the room is not that wide to begin with. But to your point, it would allow a double-door effect. Now that I think about this some more, you could also use some of that space to recess your A/V rack; essentially recess it into a portion of the interior 'porch.' Just seal off a small area, ideally at the rear of the room.
> 
> You also mentioned the possibility of a dead vent. I can only imagine that working if you still have the front porch area to use as part of the dead vent.
> 
> This reminds me, have you thought about HVAC? Is there any HVAC system in the building right now? If not, what type of system are you planning to use?


I'd definitely prefer wider room because of soundstage. And wall to wall 21:9 projector screen 
If you are talking about hvac system with those metal ducts or something like that, we don't use that in typical household. I would probably just put in a common air conditioning device somewhere on wall.
One thing I will definitely need is some nice security system.



HT Geek said:


> Awesome. I'm sure that will be a popular thread, because your starting point is so unique!


Hope so. Aiming for HT of the month award.


----------



## HT Geek

donktard said:


> If you are talking about hvac system with those metal ducts or something like that, we don't use that in typical household. I would probably just put in a common air conditioning device somewhere on wall.


Yes, I was anticipating a duct-less system, like this.


----------



## thrillcat

QUESTION:

Redoing my ceiling in the theater, going to be adding some lights. The fixtures I have are NOT IC compliant, and require 3" clearance from insulation. I'm going to build backer boxes for the fixtures, do I still need to leave 3" clearance, or can it live with less clearance without insulation?

Thanks~!


----------



## HT Geek

thrillcat said:


> QUESTION:
> 
> Redoing my ceiling in the theater, going to be adding some lights. The fixtures I have are NOT IC compliant, and require 3" clearance from insulation. I'm going to build backer boxes for the fixtures, do I still need to leave 3" clearance, or can it live with less clearance without insulation?
> 
> Thanks~!


Disclaimer: I hesitate to give you advice on that which goes against the manufacturer's instructions.

Alright, now here's my 2 cents FWIW:


Check for UL listing on your light fixtures (normally sticker is inside the housing); look up the standard and you can see what the actual limits are
If not UL listed, go with manufacturer's rec
That's 3" from insulation; other materials, you should be able to get closer to it
Use cement board on the inside of the backer boxes; 1/4" thick is sufficient; caulk any gaps with fire-rated caulk
I would leave at least 1" around the widest portion of the luminary

If I were you, I'd build a backer box with interior minimum 1" clearance all the way around between any part of the luminary and the cement board. You can use 1/2" thick MDF for your box structure, to keep it as small as possible.

Now, build yourself a test box. Make sure the box is sealed. Put one of the lights inside it, hook up power, flip the box over with the light pointing down (you can stand your backer box on some scrap wood to get it a bit off the floor). 

Ideally, before you start the test drill a small hole and drop a remote-sensor thermometer in there and hook it up to an appropriate display (e.g. some multi-meters have this capability and even come with thermometers). Seal the holes (caulk, etc.; something that you can remove later).

Make sure you are using the same bulb you plan to use in your HT room.

Leave the light on for an hour.

Check the temperature. If it's >140 degrees F, you may need more clearance inside your box.

Try and monitor the luminary while conducting the test. The tell-tale sign that it's too hot is if the light flickers off and on, or shuts off completely. If you see that, you know that plan won't work for sure. 

If the box gets too hot, build another one with 2" clearance and try again. Repeat with 3" clearance if necessary.

Your other option is to just go and buy IC rated fixtures.

Now, let me tell you a little bit about my similar experience....


I bought re-model 4" can lights for my HT (still under construction)
Manufacturer claimed Air-Tight but not IC
I looked at the UL stickers inside the lamps... guess what? IC rated.
I looked up the UL section... it basically said if IC rated then IC, otherwise 1" clearance
The manufacturer is some Chinese company (shocker!); I've never been able to find documentation (merchant didn't have any and now does not carry same model... go figure)

I am keeping 1" clearance from my luminaries to anything combustible, except for the MDF they're about to be attached to. LOL. I'll be using 35w LED's.


----------



## HT Geek

thrillcat said:


> ... I'm going to build backer boxes for the fixtures, do I still need to leave 3" clearance, or can it live with less clearance without insulation?....


Or you could follow this guy's instructions.... [Note: One reason I'm not fond of most home inspectors....]


----------



## thrillcat

HT Geek said:


> Disclaimer: I hesitate to give you advice on that which goes against the manufacturer's instructions.
> 
> Alright, now here's my 2 cents FWIW:
> 
> 
> Check for UL listing on your light fixtures (normally sticker is inside the housing); look up the standard and you can see what the actual limits are
> If not UL listed, go with manufacturer's rec
> That's 3" from insulation; other materials, you should be able to get closer to it
> Use cement board on the inside of the backer boxes; 1/4" thick is sufficient; caulk any gaps with fire-rated caulk
> I would leave at least 1" around the widest portion of the luminary
> 
> If I were you, I'd build a backer box with interior minimum 1" clearance all the way around between any part of the luminary and the cement board. You can use 1/2" thick MDF for your box structure, to keep it as small as possible.
> 
> Now, build yourself a test box. Make sure the box is sealed. Put one of the lights inside it, hook up power, flip the box over with the light pointing down (you can stand your backer box on some scrap wood to get it a bit off the floor).
> 
> Ideally, before you start the test drill a small hole and drop a remote-sensor thermometer in there and hook it up to an appropriate display (e.g. some multi-meters have this capability and even come with thermometers). Seal the holes (caulk, etc.; something that you can remove later).
> 
> Make sure you are using the same bulb you plan to use in your HT room.
> 
> Leave the light on for an hour.
> 
> Check the temperature. If it's >140 degrees F, you may need more clearance inside your box.
> 
> Try and monitor the luminary while conducting the test. The tell-tale sign that it's too hot is if the light flickers off and on, or shuts off completely. If you see that, you know that plan won't work for sure.
> 
> If the box gets too hot, build another one with 2" clearance and try again. Repeat with 3" clearance if necessary.
> 
> Your other option is to just go and buy IC rated fixtures.
> 
> Now, let me tell you a little bit about my similar experience....
> 
> 
> I bought re-model 4" can lights for my HT (still under construction)
> Manufacturer claimed Air-Tight but not IC
> I looked at the UL stickers inside the lamps... guess what? IC rated.
> I looked up the UL section... it basically said if IC rated then IC, otherwise 1" clearance
> The manufacturer is some Chinese company (shocker!); I've never been able to find documentation (merchant didn't have any and now does not carry same model... go figure)
> 
> I am keeping 1" clearance from my luminaries to anything combustible, except for the MDF they're about to be attached to. LOL. I'll be using 35w LED's.


Thank you! Will investigate further tonight!


----------



## HT Geek

thrillcat said:


> QUESTION:
> 
> Redoing my ceiling in the theater, going to be adding some lights. The fixtures I have are NOT IC compliant, and require 3" clearance from insulation. I'm going to build backer boxes for the fixtures, do I still need to leave 3" clearance, or can it live with less clearance without insulation?
> 
> Thanks~!


Apologies on spamming you here, but it took me a few minutes to dig up this old but poignant resource (circa 2000).

You may wish to read the article before you conduct any tests, as it may answer your questions/be enough info to satisfy your concerns.


----------



## healthnut

I would add that LED lights run far cooler than incandescencents and overheating them within a backer box is much less problematical.


Sent from my iPhone using Tapatalk


----------



## HT Geek

healthnut said:


> I would add that LED lights run far cooler than incandescencents and overheating them within a backer box is much less problematical.


Agreed. Should be a non-issue. 

Most of the LED lights now have auto-shut off @ 60°C, and the A/C wire should be 90°C+ rated.

OP wanted to know if he can circumvent the manufacturer's requirements on air-space around the luminary. I'd bet he'll be fine but it seems wise to perform a bench-test first and see how it performs.


----------



## Broke EF

Quick question for you guys. How effective would it be to run a piece of drywall on an angle from the bottom of a joist to the top of the one next to it? A friend sent me a pic of that asking if it was any good, we are pretty sure its only the drywall, nothing in the space behind it. I am no expert, but it seems like if it was that easy a lot of you guys here would do something similar. So how effective could something like that actually be?


Thanks,
Sean


----------



## kmhvball

Broke EF said:


> Quick question for you guys. How effective would it be to run a piece of drywall on an angle from the bottom of a joist to the top of the one next to it? A friend sent me a pic of that asking if it was any good, we are pretty sure its only the drywall, nothing in the space behind it. I am no expert, but it seems like if it was that easy a lot of you guys here would do something similar. So how effective could something like that actually be?
> 
> 
> Thanks,
> Sean


I would think this would likely create a triple leaf effect, which actually decreases effectiveness. Triple leaf is when there are three separate 'masses' with air space separating the masses. If you have the theater ceiling DW (Double DW with GG), that is 'one mass', the 'angled DW' becomes a second 'mass' as it isn't directly connected, and then the OSB subfloor (and flooring above), is a 3rd mass... thus, possible triple leaf effect. I have seen most of this in the context of three parallel masses vs an angle, but I would personally steer clear of it.

The 'gold standard' of sorts, is putting Green Glue & DW (an a second GG & DW layer) directly on the sub-floor, flat against the OSB sub-floor. This is a 'single mass'... the flooring above/osb sub-floor/GG-DW/GG-DW are all virtually 'one piece'... The theater ceiling construction is then a second mass... so, only two 'masses', and thus, no triple leaf effect.


----------



## Broke EF

kmhvball said:


> I would think this would likely create a triple leaf effect, which actually decreases effectiveness. Triple leaf is when there are three separate 'masses' with air space separating the masses. If you have the theater ceiling DW (Double DW with GG), that is 'one mass', the 'angled DW' becomes a second 'mass' as it isn't directly connected, and then the OSB subfloor (and flooring above), is a 3rd mass... thus, possible triple leaf effect. I have seen most of this in the context of three parallel masses vs an angle, but I would personally steer clear of it.
> 
> The 'gold standard' of sorts, is putting Green Glue & DW (an a second GG & DW layer) directly on the sub-floor, flat against the OSB sub-floor. This is a 'single mass'... the flooring above/osb sub-floor/GG-DW/GG-DW are all virtually 'one piece'... The theater ceiling construction is then a second mass... so, only two 'masses', and thus, no triple leaf effect.


Thanks for the response! Judging from the photo he shared it looks like they were going with that angled drywall then just regular old drywall against the joist under that. All of which seems pretty ineffective at best to me.

I did tell him, and show him the standard practice and said that if something like what he sent was effective I doubt everyone would do so much more work for the standard setup.

Also, just to clarify, no OSB in this house! It is about 140 years old, built by his great grandfather and stayed in the family. He bought it from his Mom recently and gutted it down to the studs to modernize all of the HVAC, plumbing, and electrical. He must have seen that pic somewhere and was asking if it was actually useful. You can follow his house on instagram at thehouseonwood.


Sean


----------



## HT Geek

Broke EF said:


> How effective would it be to run a piece of drywall on an angle from the bottom of a joist to the top of the one next to it? A friend sent me a pic of that asking if it was any good, we are pretty sure its only the drywall, nothing in the space behind it.


Sean,

In general, I'd second what Kmhvball stated. However, you left out details (though based on your follow-up post it sounds like Kmhvball may be on the right track in terms of envisioning what you're talking about).

A photo would go a long way to be sure we all understand the question thoroughly. Or a diagram. For instance, when you say "joist," are you talking about a ceiling joist? If so, what is above the ceiling joist?

If the scenario is a 2nd floor room with an attic above it, the issues Kmhvball mentioned ought to be less pronounced, but I agree with him there's very little point in taking your suggested approach even if that's the case. Your friend's approach is more likely to cause problems vs. fix them. 

What is his rationale behind the proposed drywalling method? What is he trying to accomplish and why did he arrive at that concept? Is there some reason he can't do 2x layers of drywall on the ceiling? Even without GreenGlue, QuietGlue, etc., the extra mass would be helpful. What are the joists made of and what are their dimensions? Which floor of the house? What is above/below the room?


----------



## Broke EF

HT Geek said:


> Sean,
> 
> In general, I'd second what Kmhvball stated. However, you left out details (though based on your follow-up post it sounds like Kmhvball may be on the right track in terms of envisioning what you're talking about).
> 
> A photo would go a long way to be sure we all understand the question thoroughly. Or a diagram. For instance, when you say "joist," are you talking about a ceiling joist? If so, what is above the ceiling joist?
> 
> If the scenario is a 2nd floor room with an attic above it, the issues Kmhvball mentioned ought to be less pronounced, but I agree with him there's very little point in taking your suggested approach even if that's the case. Your friend's approach is more likely to cause problems vs. fix them.
> 
> What is his rationale behind the proposed drywalling method? What is he trying to accomplish and why did he arrive at that concept? Is there some reason he can't do 2x layers of drywall on the ceiling? Even without GreenGlue, QuietGlue, etc., the extra mass would be helpful. What are the joists made of and what are their dimensions? Which floor of the house? What is above/below the room?



Again, thank you for the response.

Because it was posted on instagram, its not really easy to get a pic to post. This was the best I could do.

This was the one he sent me









And this was the next photo









Both of these photos are from down.to.the.studs on instagram.

So this is NOT my friends house, just a photo that he found and sent over to me asking how effective that method is. I don't have any of the details you are asking about for the pictures posted. As far as my friends house all of those details vary pretty greatly depending on where in the house we are talking about. Some are 2x10 (actually 2" x 10", not like current 2x10's) with just a layer of hardwood above. I don't believe there is any subfloor anywhere, but I would have to clarify. For the third floor he is replacing the 2x4's with 2x10's so that the floor is more stable/usable. I was up there when it was just the hardwood over 2x4 and it was a bit too bouncy for my taste 

Like I said, he hasn't done anything yet. He was more curious if that would be effective since it would be very easy for him to do at the current stage. He can just as easily do drywall with GG or something similar, but that is a lot of time and cost to do the whole house like that vs just throwing up some drywall on an angle.


Sean


----------



## HT Geek

Thanks. That helps. 

If he's seriously considering that route, your best bet is to get input from one of the audio or sound-proofing experts such as Bryan Pape (bpape)or Ted White (Ted White).

Generally speaking, I wouldn't do it. I'd go with the validated concept of 2x drywall sheets, or a material combo such as OSB+Drywall, and I'd also focus on the sub-floor for any room(s) above it.


----------



## amit916

When building a room within a room, the obvious goal is to not mechanically link the framing of the theatre to the framing of the rest of the house. However, since both are connected to the concrete foundation, what's the consensus on having the framing of the theater right against the short wall of concrete? 

Not the 10 foot wall mind you, but there is a foot of concrete where the floor was dropped, and the sill plate of the load bearing wall sits ontop of. I'll go and take pictures to illustrate my question. If I jut it up against that short wall, I still have 2.5 inches of space between both frames.

Also, what do people do about vapor barriers underneath frame? Am I to apply acoustic sealant to the vapor barrier? Or is it useless at that point... basically how do you work around that 6mm vapor barrier underneath the frame?

Pics:



>


----------



## HT Geek

amit916 said:


> When building a room within a room, the obvious goal is to not mechanically link the framing of the theatre to the framing of the rest of the house. However, since both are connected to the concrete foundation, what's the consensus on having the framing of the theater right against the short wall of concrete?


Amit,

I appreciate you going to the trouble to upload pictures. It makes it much clearer with regards to your question.

Ideally, you want a small separation from the concrete wall. However, your concrete wall is so short, if you don't have separation... it's not end of the world. That said, I would suggest you start framing your "room within a room" ~3.5" from the stud walls shown, so that you're 'inside' wall is off the concrete. 



> Also, what do people do about vapor barriers underneath frame? Am I to apply acoustic sealant to the vapor barrier? Or is it useless at that point... basically how do you work around that 6mm vapor barrier underneath the frame?


In the U.S., ordinarily pressure-treated lumber is used in place of a barrier+kiln dried wood. In your case, as you mentioned there is a barrier but this is actually a _moisture_ barrier, not a vapor barrier. Concrete will allow moisture to pass through it, but wood doesn't like moisture, which is why the barrier was placed there by your builder. Technically, a physical moisture barrier should provide superior protection vs. treated wood.

When adding new wall framing for a room-within-a-room build out, if it's in a basement (which your future room obviously is), you need to follow the same rules. In your case, I would do what the builder did. Get yourself some good 6mm poly sheeting to place under the framing. Basically, replicate what your home builder did. Your best will likely be a building supply store (i.e. not the big box stores such as Home Depot... though Menard's is better than most from what I've heard, if you have any nearby).

You may also need a vapor barrier up against any exterior walls (or you might not if they're de-coupled). For that, you should consult your local building codes to determine what is recommended for below-grade exterior walls.


----------



## ncabw

I'm rebuilding my house and have a soundproofing question. I was thinking of adding DD with GG in between the floor joist for better sound proofing in my theater/game room. The framing of the house is done and I have a lot of extra Rim Joist. They are about 1" thick. Could i just put this between the joist? From what i understand the best soundproofing has to do with adding mass. So maybe this would help.

Thanks


----------



## HT Geek

ncabw said:


> I'm rebuilding my house and have a soundproofing question. I was thinking of adding DD with GG in between the floor joist for better sound proofing in my theater/game room. The framing of the house is done and I have a lot of extra Rim Joist. They are about 1" thick. Could i just put this between the joist? From what i understand the best soundproofing has to do with adding mass. So maybe this would help.


Actually, the best soundproofing methods have to do with de-coupling first, mass second. Combining both is ideal.

That aside, I'm a bit confused by your post. Are you considering applying DD/GG combo vertically to the rim joists, between each of the floor joists?


----------



## ncabw

I was going to cut strips of drywall and screws them between the the joist to the floor above. Then add GG and then another piece of drywall. 

Then for the theatre ceiling I was going to use resilient channel and then DD with GG.


----------



## amit916

HT Geek said:


> Amit,
> 
> I appreciate you going to the trouble to upload pictures. It makes it much clearer with regards to your question.
> 
> Ideally, you want a small separation from the concrete wall. However, your concrete wall is so short, if you don't have separation... it's not end of the world. That said, I would suggest you start framing your "room within a room" ~3.5" from the stud walls shown, so that you're 'inside' wall is off the concrete.
> 
> 
> 
> In the U.S., ordinarily pressure-treated lumber is used in place of a barrier+kiln dried wood. In your case, as you mentioned there is a barrier but this is actually a _moisture_ barrier, not a vapor barrier. Concrete will allow moisture to pass through it, but wood doesn't like moisture, which is why the barrier was placed there by your builder. Technically, a physical moisture barrier should provide superior protection vs. treated wood.
> 
> When adding new wall framing for a room-within-a-room build out, if it's in a basement (which your future room obviously is), you need to follow the same rules. In your case, I would do what the builder did. Get yourself some good 6mm poly sheeting to place under the framing. Basically, replicate what your home builder did. Your best will likely be a building supply store (i.e. not the big box stores such as Home Depot... though Menard's is better than most from what I've heard, if you have any nearby).
> 
> You may also need a vapor barrier up against any exterior walls (or you might not if they're de-coupled). For that, you should consult your local building codes to determine what is recommended for below-grade exterior walls.


Sweet, thanks so much. That's what I ended up doing. Leaving about an inch or so off the concrete. With that done, I can start worrying about the supply/returns. Contractor thought I was out of my mind to ask for something bigger than 4 inch flex ducts (one return/one supply). Finally caved and gave me 8 inch supply and return to the outside. He assured me that cycling it with the outside will work just as well though advised I get a heater.

Now I'm a little concerned about door... my two door openings have almost a 4-6 inch (I'll have to measure to get a precise reading) gap between them. At this point I imagine it's communicating doors or bust. Do I just leave that cavity open? I imagine going through all that trouble only to couple the two door frames would do a lot of harm.


----------



## HT Geek

amit916 said:


> With that done, I can start worrying about the supply/returns. Contractor thought I was out of my mind to ask for something bigger than 4 inch flex ducts (one return/one supply). Finally caved and gave me 8 inch supply and return to the outside. He assured me that cycling it with the outside will work just as well though advised I get a heater.


I'm confused by your statements above. Are you planning to circulate fresh air only, like a dead vent? Or will you install a mini-split HVAC system? Bringing unconditioned air into your HT room is generally unadvised. The exhaust may not be an issue, but you will bring humidity into the room (when present) from the outside. It also can create a flanking path for sound in/out of the theater, depending on how your ducts are routed and what they're made of (i.e. metal vs. flex). 

What is your rationale for not simply adding a trunk from your HVAC system to the room? It's just as much work.




> Now I'm a little concerned about door... my two door openings have almost a 4-6 inch (I'll have to measure to get a precise reading) gap between them. At this point I imagine it's communicating doors or bust. Do I just leave that cavity open? I imagine going through all that trouble only to couple the two door frames would do a lot of harm.


You're talking about space between the original door framing and where you will create a new door frame in your double-stud wall setup, correct? There are a number of possible solutions. The best route is to use a custom-made frame. If you DIY it, you will want to take your time and verifying measurements and making sure you fully understand all the parts. It's not a huge amount of work, just a bit detailed. Or you could get a millwork company to make one for you. In the case of the latter, you would need to provide them with a drawing (can be a rough one) with accurate dimensions of your opening, so they can figure out the details for you.

The most important thing to keep in mind with a custom door frame is sound will leak out around the door unless you use specially designed door seals - such as those produced by Zero Noise. You will need to factor the size/dimensions of these seals into your other door frame measurements. Standard door framing practices will not produce the desired result in sound containment.


----------



## amit916

I was planning on using flex duct and running it in a soffit with a duct boot. So I imagine flanking would be similar to if I had done the same but hooked it up to the HVAC in the rest of the house.

He was adamant that I would not be able to use that big of a duct if I had connected it to the HRV that the rest of the house was connected to.

To be honest, he wasn't even taking into account how many people or how much heat would be generated in this room. Which has me a bit wary about what he's thinking.

EDIT: Adding more info, the rest is connected to a HRV. The specialist told us that he wouldn't be able to do more than 4 or 5 inch ducts from that to the theatre room. I can't tell if he meant in terms of pressure or capacity.

EDIT EDIT: Or am I totally thinking about it in the wrong way. Allow him to size the duct to the theatre but I size the transition to a larger size (essentially let him calculate the volumetric needs) By using a larger size, I slow down the river in the open area which then opens into a duct boot.


----------



## HT Geek

amit916 said:


> I was planning on using flex duct and running it in a soffit with a duct boot. So I imagine flanking would be similar to if I had done the same but hooked it up to the HVAC in the rest of the house.


Generally speaking, that should be the case, yes.



> He was adamant that I would not be able to use that big of a duct if I had connected it to the HRV that the rest of the house was connected to.
> 
> To be honest, he wasn't even taking into account how many people or how much heat would be generated in this room. Which has me a bit wary about what he's thinking.
> 
> EDIT: Adding more info, the rest is connected to a HRV. The specialist told us that he wouldn't be able to do more than 4 or 5 inch ducts from that to the theatre room. I can't tell if he meant in terms of pressure or capacity.


Could be either one, or both. Did he say anything about reaching a point where your system would require a larger capacity unit due to adding on your HT room? 

Higher CFM (volume) into a room can only happen with either a larger duct and/or higher velocity. If he meant your system's velocity would drop off to a point that he thought would be insufficient, that could be a good thing for a HT room, since in this case you want a lower velocity so that would be a good thing.

My suspicion is he's thinking the issue is both capacity and velocity, unless as I said he was simply thinking the velocity would be too low. HVAC technicians have tables for FPM (velocity in the U.S.) and they tend to think it's a problem when the figures don't reach those levels _or higher_, but as I said we want lower FPM in the case of a dedicated HT room.




> EDIT EDIT: Or am I totally thinking about it in the wrong way. Allow him to size the duct to the theatre but I size the transition to a larger size (essentially let him calculate the volumetric needs) By using a larger size, I slow down the river in the open area which then opens into a duct boot.


That would solve noise and velocity issues, but not capacity (CFM) into the room. Starting with a 5" wide duct you won't get much air through (CFM).

How many 5" register vents are we talking about? If more than 1, do they feed off a larger trunk? What is the diameter of the flex duct coming off the air handler to your room, before it splits into 1 or more registers? Was his suggestion 5" for that?

You also need to ensure there is equal air pushed in (supply) and pulled out (return), so the pressure in the room is equalized. This is particularly true with an isolated, sound-proofed room that is designed to be as air-tight as possible.

BTW, a mini-split system would solve all these issues. Food for thought.


----------



## HT Geek

amit916 said:


> EDIT: Adding more info, the rest is connected to a HRV. The specialist told us that he wouldn't be able to do more than 4 or 5 inch ducts from that to the theatre room. I can't tell if he meant in terms of pressure or capacity.


What do you anticipate will be the cubic volume of the room when completed? Or alternatively, what do you anticipate will be it's completed dimensions?


----------



## amit916

HT Geek said:


> Could be either one, or both. Did he say anything about reaching a point where your system would require a larger capacity unit due to adding on your HT room?


He never directly said it, but he hinted a few times that it was too small for what I wanted to do. However, I'm going to give him a call and ask him how much air he was planning on supplying the room. If I'm happy with the amount, then it's just a matter of figuring out how to slow that supply down. That should be down to duct size in the theatre right? Changing the duct size near the end of the run should not have any ill repercussions.



HT Geek said:


> Higher CFM (volume) into a room can only happen with either a larger duct and/or higher velocity. If he meant your system's velocity would drop off to a point that he thought would be insufficient, that could be a good thing for a HT room, since in this case you want a lower velocity so that would be a good thing.
> 
> My suspicion is he's thinking the issue is both capacity and velocity, unless as I said he was simply thinking the velocity would be too low. HVAC technicians have tables for FPM (velocity in the U.S.) and they tend to think it's a problem when the figures don't reach those levels _or higher_, but as I said we want lower FPM in the case of a dedicated HT room.
> 
> 
> 
> 
> That would solve noise and velocity issues, but not capacity (CFM) into the room. Starting with a 5" wide duct you won't get much air through (CFM).
> 
> How many 5" register vents are we talking about? If more than 1, do they feed off a larger trunk? What is the diameter of the flex duct coming off the air handler to your room, before it splits into 1 or more registers? Was his suggestion 5" for that?


His suggestion was just 1. So one 5" return, one 5" supply. Currently I'm not sure because he was merely doing a walk through as our framing had just been completed.



HT Geek said:


> You also need to ensure there is equal air pushed in (supply) and pulled out (return), so the pressure in the room is equalized. This is particularly true with an isolated, sound-proofed room that is designed to be as air-tight as possible.
> 
> BTW, a mini-split system would solve all these issues. Food for thought.


A mini-split air conditioning unit? Maybe it's the end of a long day, but I don't quite follow. An split AC unit would replace the need for any return and supplies? (sneak edit, just realised how dumb I sound. Of course there needs to be fresh air lol)



HT Geek said:


> What do you anticipate will be the cubic volume of the room when completed? Or alternatively, what do you anticipate will be it's completed dimensions?


Currently, it's sitting at 163" x 294" x 108". Approx 3000 cubic feet. Minus riser and stage, it should settle down to around 2750.


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## HT Geek

amit916 said:


> He never directly said it, but he hinted a few times that it was too small for what I wanted to do. However, I'm going to give him a call and ask him how much air he was planning on supplying the room. If I'm happy with the amount, then it's just a matter of figuring out how to slow that supply down. That should be down to duct size in the theatre right? Changing the duct size near the end of the run should not have any ill repercussions.


Reducing air velocity is a matter of spreading out the area over which the air travels before it enters the room. You can do this with a larger/wider face opening, longer duct work, or going to wider flex duct before it enters the room. Many people use a combination of the above, depending on whatever constraints you have in your room. HOWEVER....



> His suggestion was just 1. So one 5" return, one 5" supply....
> 
> ... Currently, it's sitting at 163" x 294" x 108". Approx 3000 cubic feet. Minus riser and stage, it should settle down to around 2750.


FWIW, I suggest you find another HVAC person. This guy doesn't understand what you're trying to accomplish.

First off, a single 5" supply for 3,000 cubic feet is way too small (IMHO). A 5" round flex duct will transfer 80 CFM. That works out to 4,800 cubic feet per hour or 1.75 room changes per hour. Way too little. I would bet you will feel like the room is stuffy with that little air flow. The recommended range is 6-10 room changes per hour. So, to get that level you would need ~16,500 cubic feet per hour at a minimum, or 275 CFM. You would need a 9" duct to reach that level (9" flex duct = 300 CFM).

HVAC technicians are accustomed to looking up desirable CFM values based on the use-case scenario of a given room, but as you may imagine, HT rooms are not on that list. 

They're also typically trying to get the airflow to some particular velocity (often 600 FPM or higher). If you tell them you want velocity below 250 FPM, that could make a difference in their suggestion if they can figure out the math. However, I think it's easier to just tell them you want 300 CFM airflow and you don't give a crap about the velocity (FPM)!

Then it's just a question of them calculating if the load on the system is capable of providing that CFM level, in conjunction with the demands on it in other parts of the home. If this is a brand new home, chances are good that your HVAC system is undersized to begin with (hate to tell you that... but it is a common problem with home builders).




> A mini-split air conditioning unit? Maybe it's the end of a long day, but I don't quite follow. An split AC unit would replace the need for any return and supplies?


It may have a supply and return (depends on type). It's basically a small, self-contained HVAC unit where the evaporator and air handler are a single unit. They can be ductless (requires a fairly obtrusive wall mounted unit) or ducted (more sophisticated units).

They are designed for smaller spaces. Very common in Europe. Mitsubishi is prolly the most well known brand.


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## HT Geek

One more thing... if velocity becomes a problem... install an in-line fan: problem solved.


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## amit916

HT Geek said:


> One more thing... if velocity becomes a problem... install an in-line fan: problem solved.


Sweet, thanks for all the help, been spending all day with this and I felt like I was like running around in circles. You've been an immense help today.

If money was no option, I think using a separate HRV combined with a ductless AC split would be the best way to go about this. Most likely will rough in the AC and then tackle the Ventilation part of HVAC first.

The HRV will take care of fresh air, while the AC will act to cool and dehumidify.


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## rhodesj

What's the difference in performance between clips/channel and a floating joist ceiling? Particularly at attenuating bass? I think it'd be a lot easier to do clips on my ceiling, but would consider joists if the gains were large enough.


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## wingm8

Hello All,

I'm debating the sound-proofing measures that would be wise for my room. I have a build thread, but I haven't updated it in a long time (Diablo Theater).

My theater room has a window and a large french door that goes to a patio under the deck. The theater is under the living room.









Room Pictures:
Looking towards window and doors:








Looking towards screen location with room entrance at right:









I'm not too concerned about sound reaching the bedrooms since the theater is on the opposite site of the house. Sound going directly upstairs and outside is more of a concern as well as sound coming in (not too worried about that though, very quiet neighborhood). If some sound goes upstairs, I'm not too worried, since I'll be in the theater anyway. The theater is partially subterranean, which might help some with the sound reaching the neighbors. The wall facing the neighbors two walls (one 2x4 wall and then a wall that is 2x6 on top of a block wall). That should help cut down sound transmission I hope.

I was thinking originally of doing DD+GG on the ceiling, but many experts here have stated a half-way solution is no solution at all. I'm not sure that going all-in on the soundproofing will even be worth it with the window and large french door anyway. Can someone let me know their thoughts on my situation?

Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).









Thanks!


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## healthnut

The most critical element in sound proofing is isolation, so I'd suggest isolating the theater ceiling with hat channel and isolation clips, following by DD and green glue. The only superior method I'm aware of is specially designed sound proofing springs, which I would assume are prohibitively expensive. Best of luck!


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## kmhvball

wingm8 said:


> I'm not too concerned about sound reaching the bedrooms since the theater is on the opposite site of the house. Sound going directly upstairs and outside is more of a concern as well as sound coming in (not too worried about that though, very quiet neighborhood). If some sound goes upstairs, I'm not too worried, since I'll be in the theater anyway. The theater is partially subterranean, which might help some with the sound reaching the neighbors. The wall facing the neighbors two walls (one 2x4 wall and then a wall that is 2x6 on top of a block wall). That should help cut down sound transmission I hope.
> 
> I was thinking originally of doing DD+GG on the ceiling, but many experts here have stated a half-way solution is no solution at all. I'm not sure that going all-in on the soundproofing will even be worth it with the window and large french door anyway. Can someone let me know their thoughts on my situation?
> 
> Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).
> 
> Thanks!


I think it looks like a Triple Leaf situation. It looks like there is plywood/some type of sheet product, between the 2x6 wall and the added 2x4 wall. When you add drywall to the outer sides of the 2x6 and 2x4 walls, you'll have 'three masses'... the two outer drywall, and then the inner plywoodish looking sheet. Is that sheeting required as part of the 'Sheer wall'? Could it be on the other side of the 2x6? I did a layer of OSB & a layer of DW on my walls... so, maybe it it could be on the other side and needs to be plywood/OSB, that could just be the first layer.

In my current house basement, I have three different 'ceiling' structures:
1) Theater room: GG/DW/GG/DW on sub-floor, insulation, clips & channel, DW/GG/DW on the ceiling

2) Basement BR (under Master BR): GG/DW, insulation, clips & channel, DW/GG/DW on ceiling

3) balance of basement: Insulation, Clips & Channel, single DW

I do think that even in the balance of basement, that I get a 'benefit', in terms of both limiting some sound going up, and definitely from sound above coming into that area. I even have an open stair well from 1st floor into the basement, and still feel I get some benefit from this very basic effort. I am comparing to my old house, where I didn't have any insulation or clips/channel, and could hear footsteps & the tv from above a lot more.

Certainly the windows/french doors (into theater and out side) will compromise sound containment, but I would still be inclined to do what you can. My electric panel is on my theater front wall, and therefore there is a large 'hole' in my soundproofing, and I am still VERY pleased with my soundproofing efforts. So, if you are looking for "Perfection", maybe it is all or none... but my $0.02, having done a single effort at sound proofing (i.e., not a lot of experience), is that you can still get benefit by doing some.


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## HT Geek

wingm8 said:


> I'm not too concerned about sound reaching the bedrooms since the theater is on the opposite site of the house. Sound going directly upstairs and outside is more of a concern as well as sound coming in (not too worried about that though, very quiet neighborhood).


Do your neighbors use lawnmowers, have dogs, occasional parties outside, drive a motorcycle, etc.??? They may not be as quiet as you think. 




> If some sound goes upstairs, I'm not too worried, since I'll be in the theater anyway. The theater is partially subterranean, which might help some with the sound reaching the neighbors. The wall facing the neighbors two walls (one 2x4 wall and then a wall that is 2x6 on top of a block wall). That should help cut down sound transmission I hope.


Those concrete block walls will be good for your neighbors but bad for you; they will reflect sound back into the room. Furthermore, sound will behave differently along the portion where the concrete block is not present (on same walls).



> I was thinking originally of doing DD+GG on the ceiling, but many experts here have stated a half-way solution is no solution at all. I'm not sure that going all-in on the soundproofing will even be worth it with the window and large french door anyway. Can someone let me know their thoughts on my situation?


I would do clips and channel on the ceiling at a minimum. You can deal with the french door and window most efficiently by sealing them off when you soundproof the room (if that is an option), or using a plug in the case of the window. Your best bet would be to build an inner stud wall in front of them to give you plenty of space for isolation. Another (perhaps more efficient) option would be clips & channel.

Everyone's situation is unique, and their tolerance for extra effort and budget is unique, and their desired outcome. That said, I would definitely do clips and channel on the ceiling as a minimum. Any basement theater really needs that or you're going to have sound transmission in both directions (from whatever is going on above into the theater room and from inside the HT room out). The flooring and framing above your room will conduct sound all over, not just up and down. Sound travels remarkably well across wood studs.

Now, in my case I have a 2nd floor HT room above my garage and with an attic above the room. For my ceiling, I chose to do OSB+DD in the middle and a DD soffit around the perimeter. I chose not to use clips and channel and secure my room-within-a-room double stud walls to the ceiling joists. It was a calculated decision based on cost, effort, and perceived gain of using clips versus not using them. Time will tell if it was a wise choice or not, but in my case the potential downside is limited by my future use of the HT room and the home environment. The attic above is pretty big, so there's lots of air to help dampen the HT room noise (plus the mass on the ceiling, plus tons of insulation above the room). Even though that's the case, I am aware of joists in the ceiling that are horizontal toward the one room (a bedroom) that shares a wall with the HT room (the other walls face either the attic or outside).




> Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).


Back to your situation.... Again looking at your walls.... Even though you have double stud walls, as @kmhvball pointed out, the wall in between those studs is a no-no and will create a triple-leaf effect when you cover either side of the double wall with drywall. 

How is that inner wall attached and what is it attached to?

Quite frankly, in your case I would suggest you go with clips & channel for your entire room. You have a number of noise issues that would be significantly mitigated via use of C&C: windows, concrete block, triple leaf wall, floor above ceiling.


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## hatlesschimp

Im mid build with my house and Im starting to notice I have a few issues about to pop up. Ive had a busy year so far and the house and theater planning has taken a second seat to the priorities like the health of my family and other things. Everything is fine and we are back on track but I just need some help steading the ship lol. 

This morning I notice the ducts for my aircon go in. I totally forgot about this. 









Also Ive run a little dry on my budget. I have r2.5 insulation in the walls and ceiling with 2 layers of 10mm ordinary plaster and a double stud wall separating the hallway and bedrooms. But now I hear I should go 17mm Marine Ply wood on all the walls first then a single layer of plaster. I accept sound is going to get out but just trying not to blow the budget. Im lucky my wife let me have a room this big and not just a spare bedroom. I will have in ceiling speakers but they will have back boxes but you cant do that with pipework. I also got told to forget about mounting my in wall speakers as i was the sound proofing by cutting holes so I will make boxes forf my speakers lol. I could have just bought freestanding and bookshelfs haha. And then the lighting too. So any help would be great for this poor confused man.  

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## HT Geek

rhodesj said:


> What's the difference in performance between clips/channel and a floating joist ceiling? Particularly at attenuating bass? I think it'd be a lot easier to do clips on my ceiling, but would consider joists if the gains were large enough.


A floating ceiling is the gold standard, but most people don't have the option for one reason or another (most often it's the starting height of the room for example). Clips & channel are your next best bet. You also want lots of mass in between the sound source and whatever you don't want it to reach.

Regarding floating joists, you will need to take into consideration the span of your joists and how much weight they will hold. Those values dictate your options for joist height and width. I created a rather comprehensive spreadsheet in Excel indicates one's options for joist dimensions if you input the joist length. I'll see if I can work on cleaning it up this week and try to post it this weekend. It's easier than pouring over span tables.


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## HT Geek

hatlesschimp said:


> Im mid build with my house and Im starting to notice I have a few issues about to pop up. Ive had a busy year so far and the house and theater planning has taken a second seat to the priorities like the health of my family and other things. Everything is fine and we are back on track but I just need some help steading the ship lol.


Just wanted to say you are not alone. Beginning late last year, my life hit the pause button when one of my kids developed a very serious infection that resulted in a (physical) disability. So, I get that completely what you're going/been through. In my case, it was a motivator to push me to begin my HT transformation from the "media room" that it was before. I needed an outlet.




> Also Ive run a little dry on my budget. I have r2.5 insulation in the walls and ceiling with 2 layers of 10mm ordinary plaster and a double stud wall separating the hallway and bedrooms.


Is there a complete physical separation and de-coupling between those double-stud walls? I can't tell for sure but it appears in one of your photos there are wood blocks in between the stud walls. That would be a bad thing as it physically connects them, dramatically reducing their effectiveness. Unfortunately, this is a common issue with typical builder-installed double stud walls. Even if that is the case, while you can access the framing you may be able to de-couple them by removing said blocks and using clips (e.g. DC-04), but you'd have to examine the situation carefully first and also take into consideration local building codes (and perhaps take this step between building inspections).



> But now I hear I should go 17mm Marine Ply wood on all the walls first then a single layer of plaster.


No, that's not true. At least not from a sound attenuation standpoint. 2x drywall/sheetrock or plaster will work well. What would be ideal is to insert a viscoelastic compound in between whatever the 2 layers are (e.g. Green Glue). It will help noticeably with sound reduction. It's not a miracle worker, but it is similar to adding another layer of plaster (and in some frequency ranges, better).




> I also got told to forget about mounting my in wall speakers as i was the sound proofing by cutting holes so I will make boxes forf my speakers lol. I could have just bought freestanding and bookshelfs haha. And then the lighting too. So any help would be great for this poor confused man.


Yes, it's much better to avoid making holes in your sound-proofed chamber whenever possible. After all the effort to contain sound, you don't want to create easy paths that let it in/out again. Many people use columns to hide surround speakers. That's probably the most common method of concealing in-wall type of speakers while keeping them inside the sound-proofed shell. Might that be an option for you? Make sure you take into consideration your seating plans (width, location in room) and where other things will go. You shouldn't need more than 100mm of depth (maybe less) for the columns to hide your speakers - presuming they are "in-wall" speakers.

Another tip for you.... While you're at the HVAC flex duct stage, try to ensure your supply vents in the HT room will be at the "front" of the room (toward the screen), and any return vents (if present - hopefully) are toward the rear of the room and definitely behind the seats. If you don't have a return vent in the room, I would strongly suggest insisting one is added. Also make certain they calculate the room load for 6-10 air changes per hour. I realize it may be a bit late in the process for you the HVAC stuff, but it would make your life easier if it could be handled before the HVAC is finalized and the walls/ceilings are up. Anything you can get the builder to do in this regard would be a plus. The return vent will matter if you truly seal the room (including the door) in an effort to make it as air-tight as possible.


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## HT Geek

hatlesschimp said:


>


It looks like your best bet (for sound isolation) would be to use clips & channel on all your walls and ceiling. That would give you the best experience.

Are you planning to seal off those windows or use window plugs? I'm presuming they are in the future HT room.


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## jrref

I have an unusual question: I live in an attached town home. The problem is that the living room wall is the common wall and when my neighbor plays his music, too much sound comes through the wall. The common wall is a staggered 2x4 wall with about 4 inches of space in between. That's good but the problem is that the upper and lower sill plates are common. About 2 years ago, I took down the sheetrock on my side, removed the un-faced single batts of pink insulation. The pink insulation filled the entire void. No dead air space. I then put 3 inches of Roxul Safe and Sound between his studs in his wall and another 3 inches in my side with a 4 inch air space and then installed 5/8 Quiet rock with acoustic seal around all of the sheets, etc.. I also used Quiet Putty on all of the outlets on his and my side. The result was that I get about a 50-55db attenuation in sound through the wall. Now I can't hear them hooting and hollering when the game is on and he has to raise the music to about 80-90 db on his side before I start to hear it.

As with all of these installations, although the bass is greatly attenuated, if it's up high enough, it cuts through the wall. After experimenting, I discovered that I could clearly hear the very slight rumbling noise that is made when the slider in my living room is opened and closed in my neighbors living room. This led me to the conclusion that most the bass is being transmitted must be though the common floor.

I was wondering, could I have cut the floor sill between the walls to decouple them since they are sitting on a common poured concrete wall in the basement? I never thought of this because I didn't want to compromise the integrity of the structure.

To address the bass problem, I put Isolate-It rubber washers under his Sonos speakers to decouple the bass from his floor and used similar rubber on all of my speakers as well which did make a noticeable difference.

Also, maybe it's my imagination, but it seems that the sound attenuation of the wall has gotten better over time.

Also, I also measure more attenuation of sound from my side to my neighbors vs the other way around. I'm assuming that the Quiet Rock on my side attenuates the amount of sound transmitted to the wall framing and to the common sill plates on my side vs on my neighbors side more sound is transmitted to the framing and to the common sill plates since there is only the regular 5/8 sheet rock on his wall.

Any comments would be appreciated.


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## HT Geek

jrref said:


> This led me to the conclusion that most the bass is being transmitted must be though the common floor.


Based on your thorough background description, I concur!



> I was wondering, could I have cut the floor sill between the walls to decouple them since they are sitting on a common poured concrete wall in the basement? I never thought of this because I didn't want to compromise the integrity of the structure.


Possibly. It's impossible to say without seeing how the floor sill of your home and neighbors are connected, how the studs are connected to them, etc. Though I would think generally speaking the answer would be 'yes.' It seems to me that would have been a rather difficult feat. It's kind of nice when your house does not collapse due to DIY construction/destruction. 

An alternative method would have been to de-couple your walls from the floor sill and added another layer or two of OSB or plywood with rubber mat in between on top of your original sub-floor. The downside is your floor would be higher up. If you have grade-level entrances to the home on that level, you'd have to make adjustments to your points of entry.




> To address the bass problem, I put Isolate-It rubber washers under his Sonos speakers to decouple the bass from his floor and used similar rubber on all of my speakers as well which did make a noticeable difference.
> 
> Also, maybe it's my imagination, but it seems that the sound attenuation of the wall has gotten better over time.


Possible. I've heard of others experiencing this when using Green Glue. QuietRock also has viscoelastic glue in between two layers (as I'm sure you knew), but it's (theoretically) already cured by the time you install it. I wouldn't expect someone to notice a difference over time w/QuietRock but it's possible. In the case of GG, it takes awhile to fully cure.




> Also, I also measure more attenuation of sound from my side to my neighbors vs the other way around. I'm assuming that the Quiet Rock on my side attenuates the amount of sound transmitted to the wall framing and to the common sill plates on my side vs on my neighbors side more sound is transmitted to the framing and to the common sill plates since there is only the regular 5/8 sheet rock on his wall.


Your assessment seems reasonable.

Overall, it sounds like you did a great job. Certainly above-and-beyond what 99% of people would have done.


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## rhodesj

wingm8 said:


> Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).


Can you tear down the 2x4 wall and use the plywood shear wall as the interior wall for that space? Add layers of drywall glued directly to the ply.

I wonder if you could make an interior door to add a second door in front of the french door? Something that you can close when you want the isolation.


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## rhodesj

HT Geek said:


> A floating ceiling is the gold standard, but most people don't have the option for one reason or another (most often it's the starting height of the room for example). Clips & channel are your next best bet. You also want lots of mass in between the sound source and whatever you don't want it to reach.
> 
> Regarding floating joists, you will need to take into consideration the span of your joists and how much weight they will hold. Those values dictate your options for joist height and width. I created a rather comprehensive spreadsheet in Excel indicates one's options for joist dimensions if you input the joist length. I'll see if I can work on cleaning it up this week and try to post it this weekend. It's easier than pouring over span tables.


What I'm wondering is how to balance the tradeoffs. I'm starting with 90" height from floor to joists, probably needing at least 2x6s, and with plumbing and ducts and whatnot to work around, I don't think I could deeply recess the joists. So a floating ceiling would probably be 3-4 inches lower than with clips and channel... and likely more work to do.

So is a floating ceiling so much better as to be worthwhile?

Definitely appreciate the comments, thanks!


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## hatlesschimp

@HTGeek thanks mate. So if I go clips and channel with green glue thats my best chance of a good result for me. How does mouning electrical points go? Thanks mate

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## HT Geek

rhodesj said:


> What I'm wondering is how to balance the tradeoffs. I'm starting with 90" height from floor to joists, probably needing at least 2x6s, and with plumbing and ducts and whatnot to work around, I don't think I could deeply recess the joists. So a floating ceiling would probably be 3-4 inches lower than with clips and channel... and likely more work to do.
> 
> So is a floating ceiling so much better as to be worthwhile?


If you start out with sufficient ceiling height, a floating ceiling is ideal. It's also (usually) cheaper than clips & channel. You can get about a 12' span out of a 2x6. That 12' figure gets tweaked depending on a few variables, but you won't get much more than that. You can sister the joists to create a 4x6 and that will get you the ability to span longer but obviously at double the lumber cost. 

You can also increase the span by installing beams in a perpendicular fashion that go between the ceiling joist sections, but then those beams will be taller than the 2x6 and you have the ceiling span issue again. You don't normally see the latter method unless there is a structural reason such as running the beams between two load bearing walls, shear walls, etc. Metal joists are another option, but at higher cost and require a bit more work than wood joists.

The bottom line is presume up to 12' span with 2x6 #2 lumber and ~17 feet with 2x8's. You will lose 5 1/2" + air gap height using 2x6's and 7 1/4" + air gap height using 2x8's. Starting with 90" height, depending on your desired features (e.g. will you have a riser? Soffits?) and local building codes, you could possibly do it. However, you also need to consider whether or not you'll be pleased with the reduced headroom, regardless of whether or not you could fit them in.


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## HT Geek

hatlesschimp said:


> So if I go clips and channel with green glue thats my best chance of a good result for me. How does mouning electrical points go?


Mount them normally to the studs. Line the back of them with putty pads, such as 3M Fire Barrier Moldable Putty Pads. You may also consider going the cheapo route and use HVAC Duct Sealant, which will accomplish the same thing. The advantage to the 3M type of pads is they are fire proof (I'm not certain if duct sealer is or not) and most of all they are a very convenient shape, just snuggly fitting over the back of a dual-gang outlet box.

The pads need to be wrapped around the outside of the box, on the portion where there is not a faceplate (i.e. one long side + top and bottom of the outside of the box). You may also want to plug the holes inside the box. *Do not install the Putty Pads until AFTER you have wired the boxes* or you'll need to retroactively touch-up the putty pads. The object is to impede sound from travelling through the outlet boxes.


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## HT Geek

rhodesj said:


> I'm starting with 90" height from floor to joists....


What are your room's current LxW dimensions?

Which species of wood are available at your local lumber yards (just give me most common that you're aware of; e.g. Southern Pine, Hem-Fir, etc.)?

Let me know and I'll be able to tell you what size joists you would need for various load conditions.


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## rhodesj

HT Geek said:


> What are your room's current LxW dimensions?
> 
> Which species of wood are available at your local lumber yards (just give me most common that you're aware of; e.g. Southern Pine, Hem-Fir, etc.)?
> 
> Let me know and I'll be able to tell you what size joists you would need for various load conditions.


I haven't looked too closely when I was at the place nearby (TW Perry) but the web site says #2 or better eastern SPF for 2x6 and 2x8s. 

Room is 22x29. There's a steel I-beam supporting the 2x8 joists in the middle of the 29' span, so I'd probably frame up a beam on either side hold the floating joists, so 14' length or so.

What values would you typically use in a span calculator for live and dead load, deflection, etc, for a typical ceiling that doesn't have to hold much weight other than the layers of drywall?


----------



## HT Geek

rhodesj said:


> I haven't looked too closely when I was at the place nearby (TW Perry) but the web site says #2 or better eastern SPF for 2x6 and 2x8s.
> 
> Room is 22x29. There's a steel I-beam supporting the 2x8 joists in the middle of the 29' span, so I'd probably frame up a beam on either side hold the floating joists, so 14' length or so.
> 
> What values would you typically use in a span calculator for live and dead load, deflection, etc, for a typical ceiling that doesn't have to hold much weight other than the layers of drywall?


Presuming the following:

84" (7 feet) minimum ceiling height
Local code measures ceiling height _after _ceiling interior application (e.g. drywall) and _before _finished flooring (e.g. carpet)
 2 layers of 5/8" drywall/plaster/whatever on the ceiling joists
1" air gap between top of floating ceiling joists and bottom of framing above them

Your only choices that will work for 14' spans:

 2x4 @ 12" O.C.
 Sistered 2x4's @ 24" O.C.

2x6 or 2x8 are strong enough (@24" O.C.) and will span 14' with no issues, but they won't allow a minimum ceiling height (7 feet). You may want to verify your local code minimum ceiling height. Just make certain you understand how it's measured. Some localities measure after the finished floor is installed, and some don't require that. Measurements always consider a finished ceiling (i.e. drywall, etc. installed).

My concern with 2x4's is it's rather difficult to find very long boards that are straight. So, if you want to go this route you should look at engineered lumber. It would solve your 'straight' 2x4 issue. If the ceiling height minimum did not apply, you could use 2x6 engineered beams. 

Engineered wood varies in both strength and minimum height by manufacturer so verify before making a purchase. I took a quick look at Georgia Pacific's Glu-Lam LVL beams as a baseline reference. Their minimum size is 7.25" tall (equivalent to a 2x8). Go with the 1 3/4" thick beams. You would not need the thicker LVL beams in this case as they'd only be supporting the ceiling material.


BTW, I use the raw engineering data to make my calculations on wood joist/beam spans. The span tables found online do not allow for the conditions in a dedicated HT room. They are standardized to allow contractors in the field to make quick calculations to determine what size joists/beams/etc. they need and do not lend themselves well to unusual circumstances. 

What is different in the rooms we're building are: 1) there is no attic above a floating ceiling; 2) there is no live load on a floating ceiling; 3) dead loads are at a level that is not accounted for in the span tables. Basically, we're not doing normal construction practices when building a dedicated HT room and as a result, nearly all the typical references don't work well because they overestimate the load on the structural members (resulting in shorter spans than the wood is actually capable of under the circumstances of a HT room).

As an example, GP's tables will claim you cannot use a 7 1/4" Glu-Lam LVL beam to span 22 feet (2x8 equivalent). However, that is not true in your case. GP's tables apply minimum presumed loads on the structure that your floating ceiling will never have, which lowers the maximum span of the beams. When you remove those restrictions and adjust the stress on the wood to match what your room will experience, that size fits (up to 46" O.C. in fact, though of course you can't do 46" O.C. with drywall or plaster).

[Incidentally, reviewing my spreadsheet calc for this stuff... which is somewhat complex... I'm realizing it may be better for me to create a Web form online that does the calcs instead of distributing an Excel sheet... perhaps would be a more user friendly option.... so, may take me a little while to get to that if I do so.]


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## HT Geek

rhodesj said:


> There's a steel I-beam supporting the 2x8 joists in the middle of the 29' span, so I'd probably frame up a beam on either side hold the floating joists, so 14' length or so.....


Forgot to ask you.... How are you thinking of doing that? 




> What values would you typically use in a span calculator for live and dead load, deflection, etc, for a typical ceiling that doesn't have to hold much weight other than the layers of drywall?


My apologies. I did not answer your question in my previous post!

Live load is not applicable in this case. The live load will be zero on your floating ceiling.

Dead load will only be your ceiling materials. Nominal weight of 5/8" Type X drywall is 2.2 lbs. per square foot. OSB and plywood weights are very close to drywall, so I presume the veneer weight is the same psf regardless of material. Multiply by 2 for 2 layers + add say 0.1 lbs. psf for the Green Glue or equivalent. So, you're at 4.5 psf with 2 layers of 5/8" drywall. Round up and call it 5.

Now, let's say you decide you want a soffit, use clips & channel, etc. Those things all obviously add more weight. I presume soffits are built after the drywall (room) shell, are 2x layers 5/8" drywall, and will add 40% of additional weight to the ceiling (I prefer to error on the side of more weight and presume they're wide soffits). To simplify the calculations a bit, I round up weight estimates and apply the following values based on these scenarios:



1 layer 5/8" DW: 5 psf
1 layer 5/8" DW + soffit: 5 psf
2 layers 5/8" DW: 5 psf
2 layers 5/8" DW + soffit: 10 psf
3 layers 5/8" DW: 10 psf
2 layers 5/8" DW on clips/channel or RC: 10 psf
3 layers 5/8" DW + soffit: 15 psf
4 layers 5/8" DW + soffit: 20 psf

So, although I've complained in my previous post that standard span tables overestimate real-world weight loads in a dedicated HT room, I'm a bit of the pot calling the kettle black, I suppose.  I purposely round up values because I want to be sure the ceiling does not deflect beyond a reasonable level, nor collapse.

Deflection is a function of the span. There is a formula for maximum allowed deflection, and a formula for how much any given piece of wood will deflect across a given span. Again, most span tables you'll find won't show you the relevant information for a dedicated HT room with floating ceiling, which by default is L/240.


----------



## rhodesj

HT Geek said:


> Forgot to ask you.... How are you thinking of doing that?


Park a 2x8 or whatever it takes near to the existing beam, and support at the middle and ends. Middle posts go right next to the post supporting the existing I-Beam. Ends are somewhat stabilized by the wall framing. Repeat on the other side. Would result in a small bump/soffit structure in the middle of the room, but not too bad.



> My apologies. I did not answer your question in my previous post!


Hah, no apologies needed when you've already supplied such a wealth of information! The comments that the normal online calculators don't serve the purpose well enough is an answer anyways.


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## HT Geek

rhodesj said:


> Park a 2x8 or whatever it takes near to the existing beam, and support at the middle and ends. Middle posts go right next to the post supporting the existing I-Beam. Ends are somewhat stabilized by the wall framing. Repeat on the other side. Would result in a small bump/soffit structure in the middle of the room, but not too bad.


So, 2 29' long 2x8's - one on either side of the existing I-beam?

I would encourage you to determine your locality's minimum ceiling height for your room. It's possible they would allow a finished height of 6' 8". If you can get them to allow it, you could do 22' wide 2x6's (12" O.C.; more wood, more room height) or 2x8's (24" O.C.; less wood, less room height).

At a finished height of 6' 10" (just 2" below the normal minimum height), you can fit 2x6's with 2x drywall on them. It's quite possible you would pass inspection and no one would notice the 2" difference. You could even leave just a 1/2" gap above the floating ceiling and reduce the delta to 1 1/2". 

Some related ideas:

1. Pro-actively discuss your concerns with a local inspector now. If he/she is pretty cool and willing to bend a bit in your direction, I'd say go for it and make sure they are the person who does your framing inspection.

2. Another tactic is to call or (preferably) email (if possible) the building inspector's office you were about to hire a contractor to build you a media room, and discovered your existing I-beam the builder installed will already put the room below 84" when it's finished, and therefore you need an exemption or you can't finish the room.

3. There's an exemption in the code for circumstances where ductwork or a beam is in the way and lowers the ceiling height below 7'. It allows you to go as low as 6' 4" (IRC R305.1, R305.1.1). Claim the beam puts your ceiling height below 7' (same as #2 above but don't mention it until you're done framing... and point out the code sections). A bit more risky vs. getting an inspector to pre-approve it.

4. One more idea... build the shell, get it inspected. Tell the inspector it's a storage room. That would put your legal minimum height at 6' 8", since it is then no longer a "habitable" space. Non-issue. Then finish it out after you have your "final" inspection.

5. Go back to the clips & channel concept. You are starting with 6" of play. Clips, channel, and 2x layers of drywall will still keep you within that 6" range.


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## rhodesj

Very good advice.

The hypothetical two 2x8s would be 22, long, and split the 29' in half which would give the 14' span I'm talking about for the 2x6s.

The existing I beam is 6" deep, so the bottom of that is 84" over the floor, what with the wood joists 90" over the floor. Heck, if it were possible to sister some 2x6s parallel to the I beam, the floating ceiling framing could be nearly flush with the I beam, and finished ceiling flat all the way across.

If I needed to keep the finished ceiling above 84", I probably could manage to get the 2x6s pushed a couple inches up. I'd have to notch the existing blocking between the joists, and have a large return duct to work around. The plumbing there is all near the edges so I might be able to notch around it.


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## rhodesj

The blocking and ducts.








The beam and some pipes.


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## HT Geek

rhodesj said:


> The hypothetical two 2x8s would be 22, long, and split the 29' in half which would give the 14' span I'm talking about for the 2x6s.
> 
> The existing I beam is 6" deep, so the bottom of that is 84" over the floor, what with the wood joists 90" over the floor. Heck, if it were possible to sister some 2x6s, the framing could be nearly flush with the I beam, and finished ceiling flat all the way across.
> 
> If I needed to keep the finished ceiling above 84", I probably could manage to get the 2x6s pushed a couple inches up. I'd have to notch the existing blocking between the joists, and have a large return duct to work around. The plumbing there is all near the edges so I might be able to notch around it.


Thanks for the additional detail. 

The thought occurred to me that depending on when your house was built, you have a good argument to make in favor of your local building inspector allowing you to go down to 6' 8" - which was the old minimum height requirement. Normally, new construction needs to conform to current code whereas existing construction needs only to meet the code version when it was built. However, in this case you really can't do anything about the height restriction you've been dealt by the old construction. It appears from the photos that moving that beam is completely impractical. Your only other option to make the room taller would be to dig out the foundation and make it deeper, but that could result in unforeseen consequences. It's not a good option unless $ is no object.

So, as I said I think you have a good point for getting an exemption. If you pursue that route and the inspector says "no," I would personally file an appeal and make a stink to your local elected rep(s).

Another option is don't get it inspected. Since your home is obviously older, it's less likely to raise any red flags during a prospective homeowner's inspection when you sell the home. There's really no point for them to make a big deal out of it and you can always claim the ceiling joists are just that low due to the home's age. If anyone actually looked, they'd see your floating joists - which would corroborate your story.

Now, as you said.... using 2x6's per your plan it would all line up nicely. I think it's a good plan.

One other option: split your room nearly in half and use one 22'x14.5' side for your HT room. Use the other side for an A/V equipment room (you could do a small room, which would actually be really nice), a dead vent, house your HVAC... whatever you want in the other 22x14 space. I realize it would be a tad narrow, but if you search AVS you will find a number of narrow theaters. 14 feet wide is very do-able. Expect it to be around 12.5-13' wide when you're done, depending on how close you can get the wall in the middle of the room to your I-beam. 

I like your idea of a 2x6 support beam in the middle on either side of the I-beam and 2x6 joists on the sides, but I'm not sure it's possible. You would need to use an engineered wood beam or a steel beam. Reflecting on this idea further, 22' would be a long span even for engineered beams that are only 5 1/2" tall. You might be able to use a 3 1/2" or larger width version.

I know they would have to be engineered beams (the 22 footers). You should be able to get a lumber company or engineered lumber firm to calculate the details for you on what thickness and height beam would work. The calculations are very different vs. the spreadsheet I created that calculates joist spans from one wall to another. With those beams, they need to be able to stand on their own and handle the additional sideways pressure from the joists on one side of them. 

If you went with 2x8's and could connect them beneath the I-beam or attach your 2x6 22' beams to the I-beam with clips (e.g. DC-04's), you would add some rigidity to them. Either way though, I think you'll probably need a structural engineer to figure it out to be sure it is sound (and btw, if you do get all this inspected they can't say no if your plans are sealed [stamped] by a licensed structural engineer) on the grounds they don't like your plans.

The easiest and most cost effective option may be to split your room in half as I outlined above, and re-purpose the other half of the room for various anecdotal things such as an A/V equipment room.


EDIT: Sorry, it's Friday afternoon... chaos here... lol. Thought I should clarify my comments above. What I was trying to say is I like your proposal. I believe you can make it work if you want to. However, I'm not sure what you lenghts you'll have to go to in order to make it work. Therefore, a simpler and more cost effective alternative would be to split the room in 1/2 and do a HT on one side, etc.


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## rhodesj

The house is a 1968. The original owner lived here for at least 30 years and was pretty handy, did lots of work around the place including electrical. His workmanship was pretty good but certainly doesn't reflect the past 40+ years of code changes, and it didn't phase our inspector. So any changes I make would likely blend in, and we don't intend to sell any time soon either.

For the 2x6 support beam, there's already a post supporting the steel I beam at the center, so I can add matching ones to the 2x6 support beams and reduce the span to 11'. Sounds like that might actually work.

I was originally going to split the space in half, but... We're actually a few other major home improvement projects (and a year or two) away from a formal theater build. However I already use the basement as my manly hideout and do things like blast music loudly enough to annoy the snot out of my wife.  Because of that she wants some soundproofing implemented. That's entirely compatible with a theater build so I want to do that sooner rather than later. She also wants the space kept open, not split in half. Just preference on her part.

Now, she's 100% onboard with a theater build, has already started looking at recliners and other things... So if she prefers open, I'm happy to do so and maximize WAF. There will need to be some kind of partition around the furnace and hot water heater. That doesn't have to take up more than 1/6 to 1/4 of the room and still gives me space for a rack, dead vents, etc...

So it ends up a win all around for me.


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## hatlesschimp

HT Geek said:


> Mount them normally to the studs. Line the back of them with putty pads, such as 3M Fire Barrier Moldable Putty Pads. You may also consider going the cheapo route and use HVAC Duct Sealant, which will accomplish the same thing. The advantage to the 3M type of pads is they are fire proof (I'm not certain if duct sealer is or not) and most of all they are a very convenient shape, just snuggly fitting over the back of a dual-gang outlet box.
> 
> The pads need to be wrapped around the outside of the box, on the portion where there is not a faceplate (i.e. one long side + top and bottom of the outside of the box). You may also want to plug the holes inside the box. *Do not install the Putty Pads until AFTER you have wired the boxes* or you'll need to retroactively touch-up the putty pads. The object is to impede sound from travelling through the outlet boxes.


I spoke to the Builders and they can do anything I want but its just a case of how much money.

Im thinking

Green glue on both layers of ordinary 10mm dry wall.
Hush box for 2 Projectors.
Back boxes for atmos speakers with holes in ceiling.
columns housing the 4 surround speakers and false wall for lcr and screen. 
two subs inside the room. (18" lol)
6 double power points on the floor. 2 at front, 2 at back, 1 either side.
2 cat 6 to the pj.
1 hdmi to pj
1 spare conduit to pj for future 2nd cheap pj for gaming.
1 double power point for pj
2 speakon for subs. 1 front 1 back of room. 

2 things that have me muffed are the Lights and the ducts. 

My heating cooling system consists of a Heater ducted and an evaporative cooler. If I have the 3 pipes come straight in I may as well not do green glue hey? And with evap I need to have somewhere for the air to escape if I board up the back windows Im stuffed.

Im thinking one solution would be to have a bulkhead and have the ducts come into the bulkhead the along then out into the room. Also have a return exit that expells the hot air from the pj hushbox and the room out to a whirly bird on the roof. Or does a whirly bird suck air in lol. also I have garage next door to the room I can use for any piping. Its not like i need the space up near the ceiling cars only take uo floor space. Anyways thats where I'm at.

Just shooting from the hip till I get organised and smarter lol. 

Thanks lads any input is great. Looking to knock this over quick. Cheers

Sent from my SM-N930F using Tapatalk


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## pchannan

This is a great thread. I've been emailing with Ted @thesoundproofing company and I will be purchasing from him

I'm doing a gut reno on my new basement - digging out depth to 10" ceilings and making some changes on my main floor and upstairs. I'd like to retrofit and sound proof my whole home but that is cost prohibitive. I'm going to isolate the noise from walking on floors. I also want to isolate the master bedroom and bathroom. It doesn't make sense to tear down the existing drywall in the other three upstairs bedrooms just to add mass and isolation with Clips & Channel/DD/GG. 

To further isolate HVAC - I'm going to have duct liners put in the duct work we aren't touching and the main trunk. The house is currently 4500sq feet, I'm adding an additional 500sq ft to the kitchen area and the basement itself is an additional 2800 sq feet (digging out under the 3 car garage to add a HT). We're going to either rework the current furnace with adding a zoning system with a second system for the basement or remove it and add three smaller variable fan furnaces and A/C units with 50% new duct work. Depending on cost, I may have them use duct board for the basement duct work. 

Floors on main floor and upstairs
Tile floors – current plywood, Serena adhesive, Serena Mat, Serena adhesive, OSB, mortar, Nuheat, mortar, Tile 
Wood Floors – current plywood, SA, SM, SA, OSB, engineered wood
Basement floor will have a hydronic in-floor heating system so just engineered hardwood on top

Master bedroom and ensuite - also down to studs
Vaulted Ceiling - one sheet of 5/8" on the Clip & Channel, blown in insulation
Walls - Clip & Channel, Double 5/8" drywall and Green Glue with r12 between the studs

Adjoining wall with master bathroom - Clip & Channel, Double 5/8" drywall and Green Glue with r12 between the studs

The great room is directly below the Master bedroom. I will hate being able to hear the TV below. We are changing the tray ceiling to a coffered ceiling so I may bite the bullet and tear down that portion of the ceiling drywall and refinish with Clip & Channel, single 5/8" drywall and r12 between studs. Each square of the coffer will have a pot light or speaker (atmos).

All basement interior walls will be: Clip & Channel, Double 5/8" drywall and Green Glue with r12 between the studs
All basement walls that border with foundation will be double 5/8" drywall and green glue with r12 between the studs (no clips or resilient channel)

All interior doors are solid core doors

HT will be done at a later date - being left as a concrete bunker for now

Questions
1. Will Backer boxes make a difference for my master bedroom if used in the great room ceiling for the pot lights and speakers?
2. In rooms that are not receiving any sound proofing - do backer boxes make a difference for in-ceiling speakers and sound pollution/diffusion?
3. How is cabinetry or other heavier objects (TV+mounts) anchored into a wall which has clips/channel and DD/GG? If we attach to a stud, don't we lose the effect of isolation?
4. How do we drywall around the HVAC ducts that drop below the ceiling? Create a sofit? 
5. Without putting in extensive muffler system - can I use an insulated or lined flexible duct to connect the bathroom ceiling fan to the cap on the exterior of the house


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## HT Geek

Sound proofing - in an ideal world - is an all or nothing type of thing. However, the world is often not ideal.  My point is that if you don't utilize equal sound-proofing techniques across your entire room, you will have some "leaks" per se. You'll have portions of your room that are more likely to allow unwanted noises in or out.

Now, for most people I think that's fine. You just need to be sure you understand the trade-offs before you start spending money, especially when you are paying others to perform work for you.



hatlesschimp said:


> Green glue on both layers of ordinary 10mm dry wall.


On all 4 walls + ceiling?




> Hush box for 2 Projectors.


Why not get 1 PJ with low latency that can do reasonable gaming? No PJ will provide very good gaming for COD and the like (twitch games). But some are playable (e.g. Panasonic PT-AE8000U).




> Back boxes for atmos speakers with holes in ceiling.
> columns housing the 4 surround speakers and false wall for lcr and screen.
> two subs inside the room. (18" lol)
> 6 double power points on the floor. 2 at front, 2 at back, 1 either side.
> 2 cat 6 to the pj.
> 1 hdmi to pj
> 1 spare conduit to pj for future 2nd cheap pj for gaming.
> 1 double power point for pj
> 2 speakon for subs. 1 front 1 back of room.


That stuff all sounds good.




> 2 things that have me muffed are the Lights and the ducts.


Since you are starting with an unfinished space under construction, I would think you should be able to find a HVAC expert who can figure this out. Just keep in mind the golden principles of HVAC in a HT, such as:

Supplies in front
Returns in rear
At least 1 return, because this will be an air-tight room
Low FPM (


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## HT Geek

pchannan said:


> I also want to isolate the master bedroom and bathroom. It doesn't make sense to tear down the existing drywall in the other three upstairs bedrooms just to add mass and isolation with Clips & Channel/DD/GG.


An alternative would be to add GG + another layer of DW to your existing walls in those rooms. You'll lose about 3/4" per wall or 1 1/2" room width/length. It would help to muffle the sound coming from elsewhere. Not a great solution, but better than what you have and less effort than clips + channel, etc. Just a thought. But don't expect a miracle if you do that. 




> We're going to either rework the current furnace with adding a zoning system with a second system for the basement or remove it and add three smaller variable fan furnaces and A/C units with 50% new duct work. Depending on cost, I may have them use duct board for the basement duct work.


I presume you realize the difference between converting an existing system to a zoned system versus replacement is a huge delta. Don't let anyone tell you that zoning an existing system is a ton of work. It's not. You add a zone controller, additional thermostats, and electronic dampers. It's not a small job mind you, but it's certainly cheaper than replacing an existing HVAC unit with 3 new ones + 50% more duct work. From my perspective, I'd be thinking more about the load on your house. With 5,000 sq ft, you really ought to have at least 2 HVAC units. Otherwise you're placing a strain on your one unit (regardless of how large it is). And if one unit fails and you only have one unit.... Well, let's hope that's not in August. 




> Master bedroom and ensuite - also down to studs....
> 
> ... Adjoining wall with master bathroom - Clip & Channel, Double 5/8" drywall and Green Glue with r12 between the studs....
> 
> The great room is directly below the Master bedroom. I will hate being able to hear the TV below.


So, you're going to go to all that trouble around the master bedroom, except the floor between it and the Great Room below? Why would you do that to yourself. 



> We are changing the tray ceiling to a coffered ceiling so I may bite the bullet and tear down that portion of the ceiling drywall and refinish with Clip & Channel, single 5/8" drywall and r12 between studs.


Best bet is to do this ^^^. You're doing everything else in that room. 

Your other options are 1) do nothing (I think you'll regret that); or 2) raise the floor in master bedroom to add mass and absorption (or possibly hockey pucks to get isolation). Problems with approach No. 2: a) you won't get the floor completely isolated unless you raise it a bit beyond where the master bedroom's floor is (i.e. horizontally); b) raising the floor means adding steps, which will likely be a trip hazard.




> Each square of the coffer will have a pot light or speaker (atmos).
> 
> All basement interior walls will be: Clip & Channel, Double 5/8" drywall and Green Glue with r12 between the studs
> All basement walls that border with foundation will be double 5/8" drywall and green glue with r12 between the studs (no clips or resilient channel)


I would suggest doing clip + channel on your basement ceiling. You are going to great lengths for everything else, why not complete the effect in the basement and minimize impact and footfall noise from above?




> Questions
> 1. Will Backer boxes make a difference for my master bedroom if used in the great room ceiling for the pot lights and speakers?


With clips & channel on the great room's ceiling, yes. If not, don't bother; the benefit will be inconsequential.




> 2. In rooms that are not receiving any sound proofing - do backer boxes make a difference for in-ceiling speakers and sound pollution/diffusion?


Only if the ceiling of the room where you are adding the backer boxes is de-coupled and/or has a lot of mass. Otherwise, they won't help much (i.e. no).




> 3. How is cabinetry or other heavier objects (TV+mounts) anchored into a wall which has clips/channel and DD/GG?


Use additional clips and possibly additional channel in that area. Ideally, you should calculate the anticipated weight of the wall/ceiling coverings, and allow 20% overage if the objects will be cabinets. Most of the clips are designed to hold 36 lbs. per clip. Let's say you want to hang a 100 lb. TV. Just to hang the weight of the TV, you'd need 3 clips. They should be positioned equi-distant where the weight of the TV would be. You might also want another channel, possibly. Personally, I'd over-engineer it and use 6 clips around where the TV would be. Don't forget that around that area you'll also need clips to hold up the drywall layers, and anything else on the wall. 

What I'd suggest is start out with a plan that covers your standard clip + channel configuration. After you determine where various heavy objects will be placed, reinforce the load-bearing capabilities of the wall/ceiling in that area. It's also advisable to have a few extra clips around the epicenter of the heavy weight (e.g. 1-2 feet from where the TV would be), as the weight is going to be distributed across the wall/ceiling surface. I'd also ensure there are at least 2 channels that span the area of the TV.

You can hang anything you want as long as there is enough support. 




> If we attach to a stud, don't we lose the effect of isolation?


Yes. You would short-circuit your efforts at de-coupling and reduce the effectiveness of the isolation from the clips & channel. There is a paper (somewhere) that outlines the percentage reduction is isolation effectiveness for every point that pierces your de-coupled shell. A few piercings are not a huge deal, but after a few the effect becomes significant. And any short-circuits will diminish your efforts, as I said.




> 4. How do we drywall around the HVAC ducts that drop below the ceiling? Create a sofit?


A soffit if feasible, if room height allows, if it is aesthetically acceptable to you, etc. Another option is to frame and drywall around it (ideally DW/GG/DW). Mostly depends on the end result/appearance you would prefer. Some people lower the ceiling in the entire room. 

If you isolate it via soffit or framing/DW, if at all possible perform this step after you have de-coupled the shell of the room.




> 5. Without putting in extensive muffler system - can I use an insulated or lined flexible duct to connect the bathroom ceiling fan to the cap on the exterior of the house


I'm not sure how you'd connect a ceiling fan to flex duct. 

Are you referring to a bathroom exhaust fan? If you are adding one, there is metal duct made specifically for this purpose. I have not looked at the building codes to determine if flex duct would be an option or not, or if you could insulate the exhaust. Most likely, you ought to be able to as the vented air will be room temperature or slightly warmer. Venting to outside is crucial. Whatever you do, do NOT vent it into your attic (can cause condensation build-up and other problems).

EDIT: Corrected typos.


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## pchannan

@HT Geek Thanks for the reply

Floors on main floor and upstairs:
Tile – current plywood, Serena adhesive, Serena Mat, Serena adhesive, OSB, mortar, Nuheat, mortar, Tile 
Wood – current plywood, SA, SM, SA, OSB, engineered wood
Basement floor will have a hydronic in-floor heating system so just engineered hardwood on top

Yes - a bathroom exhaust fan not a ceiling fan

Thanks for the info "Most of the clips are designed to hold 36 lbs. per clip" I will speak to my architect and his structural engineer to figure this out. Maybe Ted includes this calculation as a part of the design

"I would suggest doing clip + channel on your basement ceiling"
We are doing this in the master bedroom, master bathroom and master closet. The entire basement will be Clip & Channel ceiling as well. Ted suggested one layer of 5/8 with the C/C for now ($ saver) as the floor above will have Serena Mat. Is one layer of 5/8 enough rather than the typical DD/GG

I think I will add the great room ceiling. For the coffered ceiling effect - I assume they will have to install into the clips so again we have to calculate for that?

My labour costs look like they are going to skyrocket. To add backer boxes for every potlight/speaker in the Master, Great room and Whole basement will be like 50+ boxes!! I'm not handy so my contractor will have to build them.


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## HT Geek

pchannan said:


> Yes - a bathroom exhaust fan not a ceiling fan
> 
> Thanks for the info "Most of the clips are designed to hold 36 lbs. per clip" I will speak to my architect and his structural engineer to figure this out. Maybe Ted includes this calculation as a part of the design
> 
> "I would suggest doing clip + channel on your basement ceiling"
> We are doing this in the master bedroom, master bathroom and master closet. The entire basement will be Clip & Channel ceiling as well. Ted suggested one layer of 5/8 with the C/C for now ($ saver) as the floor above will have Serena Mat. Is one layer of 5/8 enough rather than the typical DD/GG


Nice house! When is the party?! 

Bathroom exhaust fans typically use a thin aluminum or steel tubing to vent air up through the attic and outside. It's around 4"/100mm in width. Panasonic has an excellent product line of in-line bathroom fans, should you need (or want) one. They are super quiet and can be installed in the attic.

Reflecting further on your project, I agree with Ted. 1 layer of 5/8" DW on the ceiling + the clips/channel makes sense considering your padded flooring above. No great need to use a 2nd layer of DW in areas that are not dedicated HT rooms.




> I think I will add the great room ceiling. For the coffered ceiling effect - I assume they will have to install into the clips so again we have to calculate for that?


Yes. The best way is to build the room shell and then the coffered ceiling inside the shell (screwed through the ceiling drywall into the channel). Then you don't have to worry about the beams resonating sound into/out of other rooms. So, yes you would need to allow for additional clips to hold the additional weight of the beams, attached to your decoupled ceiling. In other words, you decouple the whole room, but the beams will not be decoupled again. They will be bolted into the decoupled ceiling. I hope that's all clear. 




> My labour costs look like they are going to skyrocket. To add backer boxes for every potlight/speaker in the Master, Great room and Whole basement will be like 50+ boxes!! I'm not handy so my contractor will have to build them.


You may be able to find a mill/lumber shop that could pre-cut all the pieces for the backer boxes. Might be cheaper to make them that way. Or you might consider contacting a business that does picture framing and stretcher bars, such as French Canvas. They may be able and willing to create custom work for you, presuming they'd consider 50 to be sufficient quantity. 

I would specifically look for companies (such as aforementioned French Canvas) who produce pressure-fit stretcher bars. If they could create a set of 50+ kits for you that are pressure fit backer boxes, it would save quite a bit of time (though I'd still glue them together, personally... and possibly nail them as well).

The catch with backer boxes is you typically line them with GG and cement board. The latter is time consuming to cut into the small pieces you'd need for the backer boxes, and when cutting it on a table saw it tears up the blades very quickly (guess how I know this? LoL). 

An alternative (and cheaper) idea... use AT (Air-Tight) light fixtures and hope for the best (if you want to save $ on labor). Won't be as good as backer boxes, but cheaper. Food-for-thought. Depends on your priorities.


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## pchannan

Well, it seems like I overlooked a huge issue - hanging stuff on the walls. Ted has recommended that TVs/cabinets/etc should not be supported by the clip/chanel. He suggests a second wall

Maybe I was a bit unrealistic in my previous soundproofing posts– let me it break down 

There is no door from the main level to the basement – it’s open concept. I wanted to minimize sounds travelling up or down stairs respectively. I really want to sound proof the gym, furnace room from sound getting out and guest bedroom from sound getting in/out.

Gym – it will have a mirrored wall, glass French doors and glass flanking the doors on both sides (I could change this to a wood door with a glass insert and insert glass as a window as flanking instead of an entire wall of glass). There will also be a 50” TV mounted on the mirrored wall. The room is small 11’-3 ½” by 12’-5” so a double wall would eat up too much real estate. There also will be a bathroom on the opposite side which I was also planning on CC/DD/GG. It will have an enclosed tiled shower and a stone veneer on the walls or wall paper. Is there a point in sound proofing either of these two with the hanging requirements?

Kids play area – right now the walls are exterior abutting walls so the plan was DD/GG without CC. However we will be attaching built-in storage with a mantel/fireplace/TV. The built-in will have to be anchored into the wall. The depth is only 13’-10 1/4” so I’m afraid a double wall would take too much space. I guess this is out too 

Furnace room – I was planning on doing CC/DD/GG on both sides of the 3 interior walls and the DD/GG on the exterior wall. There will be at least 2 if not 3 furnaces in this room. There will be hydronic heating system with pipes and boiler. The electrical panel, water softener and alarm panel are in here. So that means I don’t think I can enclose the exterior wall portion of the room as there will be conduit to outside for generator hook up and electrical to the gazebo. As well, the equipment is heavy and it would recouple the inner interior wall. So I guess that means CC/DD/GG on the exterior part of the interior wall. Should I do R12 and single layer of 5/8” on the inner interior wall. I’m also going to get a STC 46 door with automatic door stop and door jam seals. Does this make sense or is there no point?

Wine cellar – will have racks attached to all three walls and metal & glass French doors with glass wall flanking it. I was going to do DD/GG for the two walls that are in contact with the exterior wall and CC/DD/GG with the 3rd wall which is interior. However, since racks will be attached to all three walls – is there a point? Room is only 8’-11” wide and 6’-0” deep

Basement bedroom – there may be a TV mounted on the wall. All the walls but the wall shared with the furnace room are abutting an exterior wall so DD/GG and CC/DD/GG for the common interior wall. The current cold cellar is being turned into the ensuite so all of its walls are also abutting exterior concrete wall. There will be a vanity attached to the wall, a mirror and marble stone shower. Does this make sense or is there no point?

Storage room and HA equipment room – these are new rooms in the dig out of the garage. There will be interior walls and exterior abutting walls. CC/DD/GG for interior and DD/GG for exterior. There will be an additional electrical panel and torus transformer attached to one of the walls in the HA equipment room. The projector will be mounted in either the equipment room or storage room with a passage to the theatre room. I am also planning on STC 46 doors between the theatre and storage room and between the storage room and HA equipment room. Does this make sense or is there no point?

Great room – take down tray ceiling and drywall, put in R12 and cc/single 5/8”. Attach the coffered ceiling to the channels. Does this make sense or is there no point?

Master bedroom – this is important to me as I work shifts and would like near silence if I need to sleep. We are going to do Serena mat on the floor. There are two walls which abut the exterior walls but they are not concrete. So plan was for all walls to be CC/DD/GG. I was also going to do this in the master closet but a very large built-in system is going in which will need to be anchored. So maybe just r12 and single 5/8”. One the wall shared by the bedroom and closet – only the bedroom side would be decoupled. Does this make sense or is there no point? I'm looking to see if a STC 46 French door is available

Master Bathroom – There are vanities with upright storage on both sides of the room which will need to be anchored. There is a wall shared with a smaller bedroom. I was going to do CC/GG/DD on that wall on the small bedroom side. I would also do that for the common wall in the upper foyer shared with water closet and shower. Is there any point on doing more that R12 and single 5/8” on the bathroom side of the walls since there will be multiple anchor points? 

Mud room – I wanted to decouple the wall where the washer and dryer and the gallery on the other side. There will be Serena mat under the tile floor. I got the biggest Samsung W/D and we are putting a quartz counter on top. I can’t go any higher – ie I can’t add a sand platform as there will be upper cabinets. Should I just do R12 and single layer 5/8”? 

Profoundly disappointed


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## HT Geek

pchannan said:


> Well, it seems like I overlooked a huge issue - hanging stuff on the walls. Ted has recommended that TVs/cabinets/etc should not be supported by the clip/chanel. He suggests a second wall


We've all got different perspectives and opinions. I'd argue your approach is relative to what you're trying to accomplish and your priorities. If you want to hang solid wood cabinets and fill them with dishes (e.g. kitchen), I'd say that's true a clips & channel arrangement is probably a bad idea due to potential warping of the channel. In that case, wood studs have the advantage; the gravitational force on the screws in the wood is perpendicular to the wood grain. With metal channel, the strain is borne across a smaller surface area and would require many clips per channel. At that point, cost and effort likely become prohibitive vs. an independent stud wall. However, if you're talking about hanging a cabinet with model airplanes on it for example, that might not be a big deal - though again (and as I mentioned before), you have to bear in mind the load capacity of the clips, install a reasonable number of extra channels, etc. to accommodate the extra weight/support. From a purely conceptual perspective, I am inclined to agree with Ted. And I think - opinions, math, and logic aside - Ted's advice should trump mine. He's got a lot of experience in this realm. 




> There is no door from the main level to the basement – it’s open concept. I wanted to minimize sounds travelling up or down stairs respectively.


I'm not following your thought process on that. Open concept... no door. I get it. Open concept... minimize sound travelling; not compatible goals. Open concept designs are notorious for undesirable noise issues. Most people don't think about that when they choose an open concept design. Case in point, my wife fell in love with the "open concept" of our current home. I warned her that while she was watching the TV in the family room from the vantage point of the kitchen, that when my younger child was in the playroom above - which has an open railing above the family room - that she was going to regret having an open concept. I'm sure you see where this is going. The first time she was watching TV from the kitchen while cooking, we ran into two problems: 1) my wife telling my daughter she and her friends were too loud upstairs; and 2) my daughter telling my wife the TV downstairs was too loud. LoL. You can't have it both ways unfortunately.

Without a door, you are going to get lots of sound leaking in/out of your basement. If the stairs to your basement open into a long hallway it might not be so bad, but otherwise, you're very likely to get unwanted flanking in/out of the stairwell. Not suggesting you should install a door, just saying it's a trade-off. I'd suggest thinking about how/when your basement will be used and by whom. Perhaps it's a non-issue.




> I really want to sound proof the gym, furnace room from sound getting out and guest bedroom from sound getting in/out.
> 
> Gym – it will have a mirrored wall, glass French doors and glass flanking the doors on both sides (I could change this to a wood door with a glass insert and insert glass as a window as flanking instead of an entire wall of glass). There will also be a 50” TV mounted on the mirrored wall. The room is small 11’-3 ½” by 12’-5” so a double wall would eat up too much real estate.


I'm concerned the mirrors are going to amplify higher frequency sounds within that room (won't make a difference with LFE), which will then leak out of your french doors. Are you planning on clips & channel in this room? The door will likely be your weakest point/biggest headache to contain sound in there when the TV is blaring. Double pane or leaded glass would help a bit (in the door). Good door seals will be critical.

Will the TV face the door?

Unfortunately, this is one of those big trade-off scenarios. First and foremost, it's a gym. It needs to be usable and you need to be happy with your gym. Otherwise, why bother having one?




> There also will be a bathroom on the opposite side which I was also planning on CC/DD/GG. It will have an enclosed tiled shower and a stone veneer on the walls or wall paper. Is there a point in sound proofing either of these two with the hanging requirements?


The tiled shower is simply DW + tile. Just calculate the weight/load on the wall. Stone veneer... depends on how thick and heavy it is. Are we talking bricks or slivers?

I'm not sure there is much point in sound-proofing either. It really depends on what you want to accomplish. Have you thought about your use-case scenarios? By that I mean, which rooms do you anticipate being used simultaneously, and what will be your priorities for isolating sound from one room to another?




> Kids play area – right now the walls are exterior abutting walls so the plan was DD/GG without CC. However we will be attaching built-in storage with a mantel/fireplace/TV. The built-in will have to be anchored into the wall. The depth is only 13’-10 1/4” so I’m afraid a double wall would take too much space. I guess this is out too


DD/GG on existing stud wall? You only lose 1/2" or 5/8" per wall (depending on which DW size). Again, if sound isolation is a priority... clips & channel would take up less real estate vs. double stud wall. You could do a double stud wall along the interior common/shared wall(s) and DD/GG on the exterior walls. That would help if you don't have concerns with exterior noise coming in for this room; not ideal sound-proofing but a bit better than DD/GG on all walls.




> Furnace room – I was planning on doing CC/DD/GG on both sides of the 3 interior walls and the DD/GG on the exterior wall. There will be at least 2 if not 3 furnaces in this room. There will be hydronic heating system with pipes and boiler. The electrical panel, water softener and alarm panel are in here. So that means I don’t think I can enclose the exterior wall portion of the room as there will be conduit to outside for generator hook up and electrical to the gazebo. As well, the equipment is heavy and it would recouple the inner interior wall. So I guess that means CC/DD/GG on the exterior part of the interior wall. Should I do R12 and single layer of 5/8” on the inner interior wall. I’m also going to get a STC 46 door with automatic door stop and door jam seals. Does this make sense or is there no point?


I don't see the point in DD on your exterior wall in the furnace room. The furnace won't care if it can hear the outside.  I would leave it as single DW layer and use CC/DD/GG as you mentioned on your interior walls. What about the floor and ceiling in this room? Can you do anything to isolate the equipment from the floor, such as rubber mats, hockey pucks, etc.? Will you have the opportunity to use CC/DD on the ceiling, or at least DD/GG?




> Wine cellar – will have racks attached to all three walls and metal & glass French doors with glass wall flanking it. I was going to do DD/GG for the two walls that are in contact with the exterior wall and CC/DD/GG with the 3rd wall which is interior. However, since racks will be attached to all three walls – is there a point? Room is only 8’-11” wide and 6’-0” deep


Wine cellars don't need to be large - unless you have a huge collection (which 99% of people don't). In my last home I had a wine storage unit that fit 150 bottles in an old auxiliary pantry that I gutted to install it. The space was ~2' x 2' x 7' tall. 

Personally, I would focus on climate control first, and sound isolation second. A double stud wall would be very valuable for both in a wine cellar.

Think about temperature and humidity control in that room, and how you could vent out and to where. I know that's not in your sound isolation thought-process, but IMHO should be a focal point for a wine cellar if feasible.




> Basement bedroom – there may be a TV mounted on the wall. All the walls but the wall shared with the furnace room are abutting an exterior wall so DD/GG and CC/DD/GG for the common interior wall. The current cold cellar is being turned into the ensuite so all of its walls are also abutting exterior concrete wall. There will be a vanity attached to the wall, a mirror and marble stone shower. Does this make sense or is there no point?


The vanity should be a non-issue for CC. Just double-up your channels and clips where it will be located. The shower can be OK. Depends on level-of-effort you're willing to go to and how important. Thickness and weight of the stone should be a factor in that decision process. Why wouldn't you do CC/DD/GG on the exterior walls? Is it dirt behind them? I'm not sure what type of basement you have (e.g. daylight, completely submerged, etc.).




> Storage room and HA equipment room – these are new rooms in the dig out of the garage. There will be interior walls and exterior abutting walls. CC/DD/GG for interior and DD/GG for exterior. There will be an additional electrical panel and torus transformer attached to one of the walls in the HA equipment room. The projector will be mounted in either the equipment room or storage room with a passage to the theatre room. I am also planning on STC 46 doors between the theatre and storage room and between the storage room and HA equipment room. Does this make sense or is there no point?


Yes. It makes sense. However, I wouldn't skimp on the CC for the exterior wall. Do that one as well. You won't regret it. You may regret not doing it. I'd say anything involving the HT room area or your master bedroom should have sound isolation as a priority.




> Great room – take down tray ceiling and drywall, put in R12 and cc/single 5/8”. Attach the coffered ceiling to the channels. Does this make sense or is there no point?


Yep. Do it. What did you decide on the lighting backer boxes?




> Master bedroom – this is important to me as I work shifts and would like near silence if I need to sleep. We are going to do Serena mat on the floor. There are two walls which abut the exterior walls but they are not concrete. So plan was for all walls to be CC/DD/GG.


Good.




> I was also going to do this in the master closet but a very large built-in system is going in which will need to be anchored. So maybe just r12 and single 5/8”.


If double stud wall is not an option, how about DD/GG on this wall? Any extra mass will help. The mass of the system in and of itself will help (especially with clothes in it). 

What is on the other side of the wall(s) where the built-in will go?




> One the wall shared by the bedroom and closet – only the bedroom side would be decoupled. Does this make sense or is there no point?
> 
> That works.
> 
> 
> 
> 
> 
> I'm looking to see if a STC 46 French door is available
> 
> 
> 
> I'd be skeptical if there is such a thing as STC 46 french door. Remember the most vulnerable portion are the seals, so if you can find a high STC french door, you must also do the seals or your efforts will be for nought.
> 
> 
> 
> 
> 
> Master Bathroom – There are vanities with upright storage on both sides of the room which will need to be anchored. There is a wall shared with a smaller bedroom. I was going to do CC/GG/DD on that wall on the small bedroom side. I would also do that for the common wall in the upper foyer shared with water closet and shower. Is there any point on doing more that R12 and single 5/8” on the bathroom side of the walls since there will be multiple anchor points?
> 
> Click to expand...
> 
> I'd say you have a good plan there. If you isolate on bedroom side only that will likely be good enough. Before you commit, look/think about potential flanking points from other rooms to the bathroom. I don't see a bathroom as an issue as a noise-maker in and of itself (except hair-dryers perhaps).
> 
> 
> 
> 
> 
> Mud room – I wanted to decouple the wall where the washer and dryer and the gallery on the other side. There will be Serena mat under the tile floor. I got the biggest Samsung W/D and we are putting a quartz counter on top. I can’t go any higher – ie I can’t add a sand platform as there will be upper cabinets. Should I just do R12 and single layer 5/8”?
> 
> Click to expand...
> 
> I would do at least DD in there. Also get a heavy door, and good seals. Washers generate both impact and airborne noise. The impact noise in particular goes right through normal stud walls with 1/2" DW on either side. Therefore, I encourage you to do at least DD on both sides of shared walls with a laundry room. Also, ideally see what you can do to dampen or decouple the sound in the mud/laundry room from going through the room's floor/ceiling (depending on which level it's on and what is below/above it).
> 
> 
> 
> 
> 
> Profoundly disappointed
> 
> Click to expand...
> 
> No need for that! You're doing much, much more than most people can even conceive of. I hope that your efforts translate to higher resale value for you some day. Hopefully, this will be personal and long-term investment for you.
Click to expand...


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## skads_187

lucky for me, I had some water infiltration on some areas of my 2 5/8 sheetrock with greenglue in between, both screwed into hat channels.

they need to cut out 2 areas of the double sheetrock, is there a proper way of cutting it out? in my mind, unscrewing each screw is out of the question, but then the screws are really holding them into place


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## HT Geek

skads_187 said:


> lucky for me, I had some water infiltration on some areas of my 2 5/8 sheetrock with greenglue in between, both screwed into hat channels.
> 
> they need to cut out 2 areas of the double sheetrock, is there a proper way of cutting it out? in my mind, unscrewing each screw is out of the question, but then the screws are really holding them into place


How large are the areas that require removal?


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## skads_187

HT Geek said:


> How large are the areas that require removal?


to roughly estimate , one is a 4 x 8 feet and the other 4 x 6, then the bottom part of a soffit area (maybe 4 x3) that is covering the HVAC vents.


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## HT Geek

skads_187 said:


> to roughly estimate , one is a 4 x 8 feet and the other 4 x 6, then the bottom part of a soffit area (maybe 4 x3) that is covering the HVAC vents.


Sounds like you don't have a choice but to remove screws. I'm not sure why you'd be averse to that either.

Anyway, are your sheets mis-aligned so the seams are not lined up? Presuming the seams are staggered (they should be), it will be easier for you to have the 4x8, 4x6 sections cut out and then put back the drywall in those places without worrying about the seams. Just live with it for that section being non-optimal is my suggestion. Less work and chances are it won't make any difference with regards to sound-proofing (just be sure to caulk the seams around the new DW pieces). And me personally, I would make the 4x6 a 4x8. Two fewer drywall sheets to cut.

What is the source of the water leakage? And how long was your DW wet before the problem was discovered?

You may need to remove insulation behind the damaged area, depending on how long it's been wet and whether or not the moisture has been fully mitigated. Since it sounds like you have not yet removed the affected drywall, IMHO you should plan on replacing any insulation behind it as well. Unfortunately, insulation is a good harbor for mold growth after it's been saturated. That's presuming you have 'pink fluffy' behind the DW. If you have Roxul you may fare better. Maybe not. I'd replace any insulation period. All the insulation manufacturers claim their products don't promote mold growth. And they don't. However, water does and anything attached to the insulation (e.g. wood, dirt, paper facing, etc.) will promote mold growth. Trust me, I've been down that road (drywall in basement flooded for 2 weeks due to hurricane and I was on vacation at the time). 

Bottom line: I know this is a big P.I.T.A. for you atm, but you will have to deal with an even bigger problem long-term if you don't act aggressively to mitigate the issue as soon as you can. Also why it's important to clarify the cause of the damage.


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## skads_187

Thanks, just to clarify on some points.

So the leak came from my fridge (upper floor) and leaked down to the basement, damaging a lot of my blu ray collection and then the water also followed a soft bendable vent which caused the damage in the soundproofed room. Special note: dont buy or use fridges that have the water/ice function. the contractor that came to assess and try to minimize damage informed me that a high number of their water damage calls are related to this type of issue.

So yes, the sheets are staggered in order to cover the joining gaps. obviously now when the repair work is done, i will lose that staggering. I will be ordering some acoustical sealant to cover those seems this time around. 

so the leak must have been going on for approximately 12 hours. I then cleaned everything up and the company came in order to place de-humidifiers and fans to dry as much as they possibly could. the DW on the other side of the wall, dried completely fine, however the double DW still shows high humidity after 2 days of drying. the way he explained it to me, is he thinks water got stuck in between the 2 sheets and is just sitting there, so this is why they want to break it down. And yes, we will also be removing and replacing the insulation that has gotten wet. were not taking any risks.

back to my original question though, the reason why i was asking, they are coming tomorrow to tear down the walls. it is the workers that are affiliated with my insurance company, the same ones that have setup the fans and de-humidifiers.
I am certain they have never had to tear down DW setup of this kind. I know the screws will need to come out for sure, but will they need to break and crumble all the drywall around the screws? I used quite a bit of screws. they cant just rip it off the way they would normally do. 
I dont have any experience in demolition, this is a first for me. I will be there to supervise them, I just want to make sure they dont cause any damage to the existing channels.



HT Geek said:


> Sounds like you don't have a choice but to remove screws. I'm not sure why you'd be averse to that either.
> 
> Anyway, are your sheets mis-aligned so the seams are not lined up? Presuming the seams are staggered (they should be), it will be easier for you to have the 4x8, 4x6 sections cut out and then put back the drywall in those places without worrying about the seams. Just live with it for that section being non-optimal is my suggestion. Less work and chances are it won't make any difference with regards to sound-proofing (just be sure to caulk the seams around the new DW pieces). And me personally, I would make the 4x6 a 4x8. Two fewer drywall sheets to cut.
> 
> What is the source of the water leakage? And how long was your DW wet before the problem was discovered?
> 
> You may need to remove insulation behind the damaged area, depending on how long it's been wet and whether or not the moisture has been fully mitigated. Since it sounds like you have not yet removed the affected drywall, IMHO you should plan on replacing any insulation behind it as well. Unfortunately, insulation is a good harbor for mold growth after it's been saturated. That's presuming you have 'pink fluffy' behind the DW. If you have Roxul you may fare better. Maybe not. I'd replace any insulation period. All the insulation manufacturers claim their products don't promote mold growth. And they don't. However, water does and anything attached to the insulation (e.g. wood, dirt, paper facing, etc.) will promote mold growth. Trust me, I've been down that road (drywall in basement flooded for 2 weeks due to hurricane and I was on vacation at the time).
> 
> Bottom line: I know this is a big P.I.T.A. for you atm, but you will have to deal with an even bigger problem long-term if you don't act aggressively to mitigate the issue as soon as you can. Also why it's important to clarify the cause of the damage.


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## HT Geek

skads_187 said:


> so the leak must have been going on for approximately 12 hours. I then cleaned everything up and the company came in order to place de-humidifiers and fans to dry as much as they possibly could. the DW on the other side of the wall, dried completely fine, however the double DW still shows high humidity after 2 days of drying. the way he explained it to me, is he thinks water got stuck in between the 2 sheets and is just sitting there, so this is why they want to break it down. And yes, we will also be removing and replacing the insulation that has gotten wet. were not taking any risks.


That's good. You'll be fine. 




> back to my original question though, the reason why i was asking, they are coming tomorrow to tear down the walls. it is the workers that are affiliated with my insurance company, the same ones that have setup the fans and de-humidifiers.
> I am certain they have never had to tear down DW setup of this kind. I know the screws will need to come out for sure, but will they need to break and crumble all the drywall around the screws? I used quite a bit of screws. they cant just rip it off the way they would normally do.
> I dont have any experience in demolition, this is a first for me. I will be there to supervise them, I just want to make sure they dont cause any damage to the existing channels.


Explain to them they need to use a Drywall saw, Saw-zall, or similar tool to cut out the sheets because they are glued, screwed, and staggered. They may need to poke around a bit to verify where the columns of screws are. A magnet sometimes works to identify where they are without damaging the drywall, if you/they have one handy.

Your insurance company is obligated to pay for repairs and "like-kind" replacement. Technically, you could argue they need to re-do the entire wall because the wall won't be completely staggered when they are done - as you've pointed out. Personally, I would live with it as long as they take care to minimize the damage in the demo process and someone takes ample acoustic caulk to the seams when the pieces are replaced.

If they are resistant, I would not let them do the work, call your insurance adjuster and *****.


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## HT Geek

One more thought... normally, under state law you have the right to choose the contractor. If you hired a particular company to build the walls in the first place, I'd strongly consider/suggest hiring that company to fix your wall. And in that case, you may consider re-doing the whole wall after all to preserve the staggered pattern. You'd need to negotiate that with your insurance company first of course, but your original contractor could vouch for the construction method and provide an expert opinion on why the entire wall needs to be re-done (and possibly the soffit as well). If you line that up, they can't say no (if they do, you can sue them and file a complaint with your state Attorney General's office, and your state insurance comptroller.... insurance companies don't like to get letters from those folks).


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## skads_187

HT Geek said:


> One more thought... normally, under state law you have the right to choose the contractor. If you hired a particular company to build the walls in the first place, I'd strongly consider/suggest hiring that company to fix your wall. And in that case, you may consider re-doing the whole wall after all to preserve the staggered pattern. You'd need to negotiate that with your insurance company first of course, but your original contractor could vouch for the construction method and provide an expert opinion on why the entire wall needs to be re-done (and possibly the soffit as well). If you line that up, they can't say no (if they do, you can sue them and file a complaint with your state Attorney General's office, and your state insurance comptroller.... insurance companies don't like to get letters from those folks).


so yes, I will be actually getting my own contractor, so at the same time I can help explain exactly how to put it back together. 
but at the same time, I will leave the current workers complete the destruction part of it, because they want to make sure that there is no more water left anywhere.

So far, as far as I am concerned, they will be giving me exactly the same products/quality that Ive had before, but that is to be seen in the next few days when the quotes for repair will be submitted.

just an FYI, im in Canada and not in the US.


----------



## HT Geek

skads_187 said:


> so yes, I will be actually getting my own contractor, so at the same time I can help explain exactly how to put it back together.
> but at the same time, I will leave the current workers complete the destruction part of it, because they want to make sure that there is no more water left anywhere.


Makes sense. I forgot the mitigation phase is independent of the re-construction phase.




> just an FYI, im in Canada and not in the US.


Ah... well, I'm sure Canada has some sort of rules on the subject. Sounds like you are on top of it.


----------



## skads_187

HT Geek said:


> Makes sense. I forgot the mitigation phase is independent of the re-construction phase.
> 
> 
> 
> 
> Ah... well, I'm sure Canada has some sort of rules on the subject. Sounds like you are on top of it.


I hope so lol, im just a bit frustrated that they need to redo the whole flooring in the whole basement, and I will now need to undo everything i just recently did. a real pita, but i guess it could have been worse, they just better give me the money I need to replace my blu-rays!


----------



## Livin

Guys, looking to greatly reduce noise moving through a small wall (~8H x 6W)... where the prior owner built the wall with only a 1" gap between it and the HVAC/Furnace/Blower

The blower & furnace sounds/vibrations go directly through the wall. 

Access between the wall and furnace is VERY difficult but I was thinking I may be able slip one or two of these panels between to stop the noise... at less cost/effort vs redoing (or even just adding GG + Mass to) the wall. I will be remodeling in 10-12 months so this is a stop-gap but I don't want to spend money if it will not really work.

Anyone ever use Quilted Fiberglass Panels for sound mitigation? I might be able to get these pretty inexpensively...
Singer Safety Sound Stopper 4'W - 1" Thick Double Faced Panel - SC-123
-- http://www.singersafety.com/catalog/sound-stopper-noise-control/quilted-fiberglass-panels

And I was also thinking I might hang some MLV since I have a spare 4x8 roll

Interested in anyone having experience with doing anything like this?

Thx!


----------



## BP

I am a novice in the area of soundproofing but have been reading everything I can get my hands/eyes on. I am concerned about whether modifying my original approach to soundproofing my listening space in a more cost effective manner will result in a failed effort. 
My sound system is on the lower level of our home. My wife uses the living room directly above my listening space. She can't hear the TV or speak on the phone when I hit higher volumes with my system. 
We are seeking sound reduction, not sound proofing. 
I intend to close off the open listening space with an attractive glass wall (has STC rating in the mid 50's) which will reduce much of the vocals and higher frequencies from traveling up an open staircase into the living room area. 
Heavy Crestron (Rose Co.) drapes will be hung in front of the glass wall. 
The plan is to tear out the ceiling and stuff it with Roxsul them install a channel system. 
It seems side to side noise is not an unlivable situation as my wife can make a phone call in the next room when the system is played loudly. So noise and vibrations traveling upstairs is my issue. 
I spoke to a rep from one of the soundproofing websites who suggested not going the full distance on the walls as well as the ceiling. He felt a majority of the benefit to soundproof the upstairs area would be realized by doing the ceiling properly. Perphaps adding another layer of wallboard with Green Glue right over the existing wallboard would suffice and save me money?? I have seen some benefit from blowing dense insulation into the walls can add some STC value as well. 
I am open to suggestions. 
Thanks.
bp


----------



## granroth

Livin said:


> Guys, looking to greatly reduce noise moving through a small wall (~8H x 6W)... where the prior owner built the wall with only a 1" gap between it and the HVAC/Furnace/Blower
> The blower & furnace sounds/vibrations go directly through the wall.
> 
> Access between the wall and furnace is VERY difficult but I was thinking I may be able slip one or two of these panels between to stop the noise... at less cost/effort vs redoing (or even just adding GG + Mass to) the wall. I will be remodeling in 10-12 months so this is a stop-gap but I don't want to spend money if it will not really work.
> 
> Anyone ever use Quilted Fiberglass Panels for sound mitigation? I might be able to get these pretty inexpensively...
> Singer Safety Sound Stopper 4'W - 1" Thick Double Faced Panel - SC-123
> -- http://www.singersafety.com/catalog/sound-stopper-noise-control/quilted-fiberglass-panels
> 
> And I was also thinking I might hang some MLV since I have a spare 4x8 roll


The proper solution to this would be to add mass and more mass plus try to decouple that wall as much as possible. The latter definitely falls into a "remodel" perspective, though, not a stop-gap.

In general I wouldn't assume that those fiberglass panels would help in the way you'd hope. Those fall under the absorption umbrella which is the weakest of all the soundproofing types. There's a reason the website says that they should be used in conjunction with other noise control solutions and also refuse to give any sound ratings for the 1". There's simply not enough of it to affect anything but the higher frequencies.

MLV isn't often recommended just because it's very expensive for what you get, compared to solutions like drywall+GG and the like. But it absolutely does work and if you already have it, by all means hang some up and see how much it helps! That'll help far more than the fiberglass solution would.

Now... you did say that you could get the fiberglass sheets inexpensively. If so, then it _might_ be worth getting a few panels of those and combine those with the MLV. I can't guarantee any specific amount of noise reduction but you'd certainly get _something_.


----------



## granroth

BP said:


> I am a novice in the area of soundproofing but have been reading everything I can get my hands/eyes on. I am concerned about whether modifying my original approach to soundproofing my listening space in a more cost effective manner will result in a failed effort.
> My sound system is on the lower level of our home. My wife uses the living room directly above my listening space. She can't hear the TV or speak on the phone when I hit higher volumes with my system.
> We are seeking sound reduction, not sound proofing.
> I intend to close off the open listening space with an attractive glass wall (has STC rating in the mid 50's) which will reduce much of the vocals and higher frequencies from traveling up an open staircase into the living room area.
> Heavy Crestron (Rose Co.) drapes will be hung in front of the glass wall.
> The plan is to tear out the ceiling and stuff it with Roxsul them install a channel system.
> It seems side to side noise is not an unlivable situation as my wife can make a phone call in the next room when the system is played loudly. So noise and vibrations traveling upstairs is my issue.
> I spoke to a rep from one of the soundproofing websites who suggested not going the full distance on the walls as well as the ceiling. He felt a majority of the benefit to soundproof the upstairs area would be realized by doing the ceiling properly. Perphaps adding another layer of wallboard with Green Glue right over the existing wallboard would suffice and save me money?? I have seen some benefit from blowing dense insulation into the walls can add some STC value as well.


I like that you differentiate "sound reduction" from "sound proofing" since, well, that's all we can really do anyway. The only true sound proofing is to build a theater in space -- everything else is just reduction. 

The Soundproofing Company used to have a pretty comprehensive page on the different ways of treating ceilings but I can't find it anymore. Their new page is much more limited but still useful:

https://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/

Note how much of a dramatic difference adding the channels makes and then bumping it up significantly again just by adding more mass in the joist bays themselves. Having two sets of two layers of drywall/wallboard with GG on each side of a decoupled connection can make a difference far outstripping what the simple material additions suggest.

Anything beyond what is suggested in their SPC Ceiling Solution 3 tends to be cost prohibitive and/or requires notable remodeling (e.g., floating ceilings and the like).


----------



## BP

Hi granroth:
Appreciate your response. 
Yes, looks like SPC2 or SPC3 is the ceiling solution I need. Do I understand correctly that the difference are the boards placed in the rafters against the upstairs floor? And this is a way to reduce footsteps, etc from above disturbing the listening space below? If so, I am OK with SPC2 because noise from above is not an issue. 
I was planning on removing the ceiling board, stuffing something like Roxsul in the rafters then adding a clip and channel solution to remount 2 layers of ceiling wallboard on. 
Is this similar to SPC2? 
I am also interested in your opinion about treating the walls to get some benefit but without removing them. I guess adding mass would help; such as 2 layers of wallboard with Geeen Glue. Should any insulation be blown into the walls also? Will doing this type of treatment to the walls help reduce transmission of noise or vibrations to the living room above my listening space?
Thanks!!
bp


----------



## granroth

BP said:


> Yes, looks like SPC2 or SPC3 is the ceiling solution I need. Do I understand correctly that the difference are the boards placed in the rafters against the upstairs floor? And this is a way to reduce footsteps, etc from above disturbing the listening space below? If so, I am OK with SPC2 because noise from above is not an issue.
> I was planning on removing the ceiling board, stuffing something like Roxsul in the rafters then adding a clip and channel solution to remount 2 layers of ceiling wallboard on.
> Is this similar to SPC2?


The difference between SPC2 and SPC3 is, indeed, the two sheets of drywall+GG installed between the rafters. The website stresses their importance for footfall traffic but that's only because that's the focus on ceilings that they are promoting. They will absolutely help even in your case and by a pretty significant amount -- witness the rise from 66 STC to 76 STC with the addition of those layers. It's worth noting that STC doesn't measure anything at all like footfall traffic and thus that increase of 10 STC is all about reducing the sound coming from your theater to the room above.

So what it comes down to is that if you absolutely cannot install those extra sheets (or even one more sheet, which would give you 72 STC) then you will still be getting a very excellent score of 66... but if you do have the access and the time money and will to install them, then the upgraded solution will be even better!

And yes, your existing plan is pretty much SPC2, as long as you are using Green Glue between the two layers and are using 5/8" Type X drywall (or the equivalent, if different locally). Your results will be dramatically different if you skip the Green Glue step or if you use 1/2" or "lightweight" drywall.



BP said:


> I am also interested in your opinion about treating the walls to get some benefit but without removing them. I guess adding mass would help; such as 2 layers of wallboard with Geeen Glue. Should any insulation be blown into the walls also? Will doing this type of treatment to the walls help reduce transmission of noise or vibrations to the living room above my listening space?


Ah, this is where it gets a little more nebulous and harder to predict measurable results. What you'd be attacking by treating the walls would be the "flanking" problem. This is where sound will travel up the studs in your walls and travel through the joists to the floor above, completely bypassing all of our soundproofing efforts. Flanking can absolutely be a huge problem and is a leading cause of soundproofing efforts not delivering the results that you expect.

But... it's hard to predict in advance just how much a problem a specific flanking case will make! You could forgo treating the walls and discover that your expected sound attenuation was far below what was expected... or skip treating them and find that it made no difference in the end. Likewise, you could treat them and have them make no difference (although you wouldn't know).

The issue is that we're in full chaos theory mode trying to track all of the variables that would come into play in order to predict the outcome of those connected pieces.

The end result is that it would never hurt to add a couple layers of DW+GG and if you can afford it, you won't regret it. But you won't know in advance if it's actually required or not.

As far as blown insulation goes... it's essentially not done in any typical professional soundproofing environment, as far as I know. I did see a video a few years ago comparing using densely packed cellulose vs fluffy fiberglass for soundproofing and the video showed a vast improvement with the blown material. In the real world, though, it doesn't appear to work that way. The mass of the material just isn't enough even densely packed to make any notable difference in that regard and the absorption isn't significantly better, either. Worse yet, the packed material will very often settle over time, leaving gaps in the coverage. That could dramatically diminish your attenuation over time.

That's why the standard recommendation is to just install batts of fluffy fiberglass. It holds its shape in filling the bay; is inexpensive; and does a good job of absorbing sound for its size. If you don't want to tear down your existing wallboard, though, then that wouldn't be an option.

Honestly, I wouldn't bother. The absorption part would mostly come into play with sound traveling through the wall and would have little effect to sound traveling up the wall. You've already said that side-to-side sound isn't a problem and so I don't think you'd notice any difference one way or another. It would be the added mass and damping that would prevent the sound from getting to the studs in the first place, thus reducing your flanking.


----------



## BP

Hi granroth:
I think I am starting to get a handle on this effort. Shortchanging the wall effort may defeat my entire goal if low frequencies find their way up the walls and around the treated ceiling. So the walls will have to come down. Too bad but likely worth it in the long run. 
I decided to call The Soundproofing Co today and spoke at length with Ted. What a knowledgeable guy who enjoys sharing his expertise. I am now comfortable with the concept of having my contractor work with Ted to obtain the needed results. My dealer who quoted big $ will not be so pleased...but our 40 year friendship will survive. 
The ceiling rafters will be stuffed with insulation and then a clip and channel setup to attach the 2 layers of wallboard with Green Glue. The walls will either get a new staggered set of studs or S clip and channel setup. 
The most interesting part of our discussion was about a glass wall to close off the listening space. It appears Ted has potentially provided a much more cost effective solution for me to use that will provide a significantly higher STC value. The dealer solution has an STC in the mid 50's. Ted thinks his solution will get me into the 70's. Further research to come and I hope, confirm this estimate. 
Does it seem I am on the right path?? Hope so! I am so enjoying learning about this aspect of audio. 
Thanks!!
bp


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## arcticbowman

Below are a few pictures of my soon to be theater. I am building this along with my brother, and being in Alaska, our resources are limited for this type of information, so this site has been very helpful with planning. I'm just hoping I'm not getting to the point of overthinking everything!

The front screen wall (turret) and one of the main side walls is 8" ICF. The other main wall is a 2X6 bearing wall and I've built a 2X4 wall next to it for separation, so I've got about 9" of depth. My back wall is 2X4 framed, and my ceiling is 12" floor joists. The level above the ceiling (main dining room) is plywood with 1&1/2" of gypcrete. The floor is a concrete slab. I plan to stuff insulation into each wall, the second row seating platform and throughout the ceiling.

Basic room dimensions are 24' deep by 13' wide. The ceilings are 100" and I will be building a ~8"X16" soffit (mostly for looks) on all walls except the screen wall. The screen wall will be built 3'-4' out from the back of the turret and I will be using an AT screen with a shelf holding the front speakers and possibly the subs. I will either be installing a 5.2.4 or 7.2.4 Dolby Atmos system. The door is the only opening in the room, and I do have an air supply duct not too far from the door opening. In the first picture, you can see that I have also installed bracing between the floor joists to firm things up.

I'm looking for some guidance on how I should handle this room for some basic sound proofing. I know some of the basics from reading through these forums, but I'm hoping for some pointers specific to my setup. This room is in the basement and two stories below the main bedrooms. 

On the bearing wall, I can't go much thicker than 1&1/4" of finished wall beyond where it currently is due to the door opening. What I do on the bearing wall I'd like to match on the rear wall since the door is centered at an angle between those two walls. Right now I'm thinking 1/2" OSB with 1/2" drywall, then install acoustic panels over the finished wall. Our drywall up here is about $18 per 4X8 sheet of 1/2", so the $21 per sheet of OSB isn't too much more and would give me a solid nailing surface for acoustic panels and any other treatments. I'm wondering if I going to have any sound issues due to 1/2 of the theater being ICF and the other half wood framed?

Thanks in advance!

Jerry


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## HT Geek

Jerry,

I'll share my thoughts with you, FWIW.



arcticbowman said:


> ... my ceiling is 12" floor joists. The level above the ceiling (main dining room) is plywood with 1&1/2" of gypcrete. The floor is a concrete slab. I plan to stuff insulation into each wall, the second row seating platform and throughout the ceiling.


How thick is the concrete of your dining room floor?




> The front screen wall (turret) and one of the main side walls is 8" ICF. The other main wall is a 2X6 bearing wall and I've built a 2X4 wall next to it for separation, so I've got about 9" of depth. My back wall is 2X4 framed, .... .... Basic room dimensions are 24' deep by 13' wide.... .... The screen wall will be built 3'-4' out from the back of the turret and I will be using an AT screen with a shelf holding the front speakers and possibly the subs.


The shape of your turret wall will give you a bit more interesting acoustics to sort out, relative to sound travelling from the sides and rear of your front side speakers. Just something to keep in mind. You can reduce the potential for issues with that by either very thickly padding those walls with absorption and/or choosing speakers with polar plots that show little rear/side reflections. That said, you might not even notice an issue. I'm just mentioning this because those walls will reflect sound and in your case they will provide non-right angles so it's going to make those reflections different than the norm. Maybe it will help out; I really don't know for sure (if one of the audio gurus here chimes in, then we'll know). 




> .... The ceilings are 100" and I will be building a ~8"X16" soffit (mostly for looks) on all walls except the screen wall.... .... I do have an air supply duct not too far from the door opening.


HVAC vents: My advice... come up with a plan (before you install drywall) that 1) creates at least 2 supply vents in the room; 2) adds a return vent; 3) ensures equal air pressure in/out of the room; 4) allows for reduced velocity of air flow in and out of the room (


----------



## arcticbowman

HT Geek said:


> Jerry,
> 
> I'll share my thoughts with you, FWIW.
> 
> 
> 
> How thick is the concrete of your dining room floor?
> 
> _ - It is 1&1/2" gypcrete over the top of the plywood.
> _
> 
> The shape of your turret wall will give you a bit more interesting acoustics to sort out, relative to sound travelling from the sides and rear of your front side speakers. Just something to keep in mind. You can reduce the potential for issues with that by either very thickly padding those walls with absorption and/or choosing speakers with polar plots that show little rear/side reflections. That said, you might not even notice an issue. I'm just mentioning this because those walls will reflect sound and in your case they will provide non-right angles so it's going to make those reflections different than the norm. Maybe it will help out; I really don't know for sure (if one of the audio gurus here chimes in, then we'll know).
> 
> _ - Interesting point on the rear and side deflections. I will take that into consideration when narrowing down the surviving speakers on my list. I believe only a couple of them have any side or rear ports.
> _
> 
> HVAC vents: My advice... come up with a plan (before you install drywall) that 1) creates at least 2 supply vents in the room; 2) adds a return vent; 3) ensures equal air pressure in/out of the room; 4) allows for reduced velocity of air flow in and out of the room (


----------



## HT Geek

1. 1-1/2" thick gypcrete should be ~14 to 16 psf, if I recall correctly. Prolly closer to 14. Regardless, that is very dense when it comes to residential floors that are not on grade. That's good for this purpose, though concrete tends to conduct LF fairly well (a minus). With an air gap above a double-DW ceiling in your HT room, plus some insulation in there.... That ought to work well. Plus how often do you use your dining room anyway? Most people hardly ever use it.

2. My comments about speakers and their audio dispersion (polar plots) don't have anything to do with the ports. What I was referring to is every speaker has a pattern with which it disperses sound - in a 360 degree arc on each axis (x, y, z) - creating a sphere of sound projecting outward. The most intense/loudest sound comes of course in the front, where the speaker's sound-emitting portions are pointed. However, all speakers "leak" sound in other directions as well, such as from reverberations of the speaker cabinet, and just plain the way sound travels. My point was simply that some speakers are better than others at directing as much as possible of the sound/noise forward. Some are very "leaky" per se and tend to pump out more sound at different frequencies at other angles. You want to try and avoid the latter. The only way you'll know, however is by looking at polar plots.

And I want to add that this is really a micro attention to detail for most people. If you had your speakers right up against the wall, it might be a bigger issue. The only reason I mentioned this is because as I said above, the angle of your wall behind the front side speakers is going to direct those reflected sounds at unusual angles into the room. It could theoretically be something you want to deal with. However, if you have a lot of absorption behind and to the side of those speakers, I believe you'll have no issues. You may wish to consider using a baffle wall, as an example.

3. Is 5/8" better than 1/2" drywall? Yes. Is it a HUGE difference? No. You're talking less than a handful of STC points. That said, the more layers, the more the difference is amplified. If you don't need absolutely the best sound proofing then you'll likely be fine with the 1/2". I understand the motivation of not moving 5/8" sheetrock.  The key is really to use a dampener in between - a viscoelastic compound; e.g. Green Glue, Quiet Glue, TiteBond, etc. (btw, don't use TiteBond). 

Presuming a 2x4 wall cavity with wood studs, insulation in the walls, and the sheetrock attached directly to the walls (i.e. no clips & channel, etc.), the delta between 1x 5/8" sheetrock and 2x 5/8" sheetrock with no glue in between is 2 or 4 STC, depending on your source of info (i.e. who's test you're reading). The delta between 2x 5/8" with no viscoelastic glue and 2x 5/8" DW with Green Glue in between is 7-11 STC. If you use clips & channel + viscoelastic glue, the delta jumps to 20-23 STC (a SUBSTANTIAL difference).

4. I would recommend clips & channel at least on your common (interior) walls. Ideally, you'd have either a) complete room-within-a-room (double stud wall and independent [floating] ceiling); or b) clips & channels on all walls and ceiling. That would be your best isolation. If you like to play movies and music loud and your significant other hates that, this would be your best bet (including viscoelastic glue in between 2x DW layers on all surfaces). You could still skimp a bit and go with 1/2" sheetrock. The isolation offered by the clips & channel + viscoelastic glue will do more for you than the extra mass of the 5/8" drywall (though mass is a big helper in absorption).

If you don't blare your content super loud all the time, you could compromise and use more isolation for those common walls. It would save you time and money. Just depends on your priority. The biggest factor is it's obviously very difficult to re-do anything in the future if you feel you didn't do enough the first time around.

Many people on this forum will tell you to goto the max with isolation, but IMHO one needs to be practical if you're not an ADHD audiophile and this is your home. Like I said, it all depends on your priorities and needs/wants.


----------



## ncabw

I want to do some soundproofing in between my ceiling joist. I see it's best to do DD with GG. I will be using 5/8 DW. I can't get this in between every joist with the existing duct work installed. I have about 24 joist going across and I can get about 20 done leaving 4 that I can't get 2. 

1)So should I still do the 20 or would I be wasting my time and money since I can't do them all. 

2) can I not do the GG just double up on the drywall?


----------



## HT Geek

ncabw said:


> I want to do some soundproofing in between my ceiling joist. I see it's best to do DD with GG. I will be using 5/8 DW. I can't get this in between every joist with the existing duct work installed. I have about 24 joist going across and I can get about 20 done leaving 4 that I can't get 2.
> 
> 1)So should I still do the 20 or would I be wasting my time and money since I can't do them all.
> 
> 2) can I not do the GG just double up on the drywall?


I understand your conundrum, but it's a bit of a loaded question as you put it above. By that I mean - for example - if your room's ceiling is attached to the structural ceiling joists, then what you are proposing will have a minimal benefit because sound will travel via the ceiling joists to which your drywall is directly attached. 

Now, if let's say you have some sort of isolation (such as clips & channel) between your ceiling joists and your drywall ceiling, then at that point doing what you propose begins to become more effective as you are blocking some of the sound traversing through the open cavities in the ceiling between the joists.

All that said, if you still want to consider implementing your plan, a diagram would be helpful for other folks to ascertain the potential effectiveness. Photographs would be even better. Some folks on AVS will tell you it's an all-or-nothing proposition, but I personally believe the devil is in the details. There are some cases where not having 100% of the joists dampened might not be a big deal. So, if you have photos or a diagram, please share so that we can do a more thorough job of advising.


----------



## arcticbowman

HT Geek said:


> 1. 1-1/2" thick gypcrete should be ~14 to 16 psf, if I recall correctly. Prolly closer to 14. Regardless, that is very dense when it comes to residential floors that are not on grade. That's good for this purpose, though concrete tends to conduct LF fairly well (a minus). With an air gap above a double-DW ceiling in your HT room, plus some insulation in there.... That ought to work well. Plus how often do you use your dining room anyway? Most people hardly ever use it.
> 
> *With the ceiling I think I will do a single layer of rock using the clips and channel, stuff the 12" cavity with insulation and call it good. With the added plywood and gypcrete on the dining room level, I'm keeping my fingers crossed that it will be sufficient. I also think I will go a little larger on the soffit. Right now we have it at 8" high by 16" deep, however the last 6 of depth" is going to be a channel for rope lights. I may lower it a couple inches to 10". I don't think I will be doing much more with HVAC in that room. I have a 4X10 supply line to feed the room with a little fresh air, but we hardly use the HVAC.*
> 
> 2. My comments about speakers and their audio dispersion (polar plots) don't have anything to do with the ports. What I was referring to is every speaker has a pattern with which it disperses sound - in a 360 degree arc on each axis (x, y, z) - creating a sphere of sound projecting outward. The most intense/loudest sound comes of course in the front, where the speaker's sound-emitting portions are pointed. However, all speakers "leak" sound in other directions as well, such as from reverberations of the speaker cabinet, and just plain the way sound travels. My point was simply that some speakers are better than others at directing as much as possible of the sound/noise forward. Some are very "leaky" per se and tend to pump out more sound at different frequencies at other angles. You want to try and avoid the latter. The only way you'll know, however is by looking at polar plots.
> 
> And I want to add that this is really a micro attention to detail for most people. If you had your speakers right up against the wall, it might be a bigger issue. The only reason I mentioned this is because as I said above, the angle of your wall behind the front side speakers is going to direct those reflected sounds at unusual angles into the room. It could theoretically be something you want to deal with. However, if you have a lot of absorption behind and to the side of those speakers, I believe you'll have no issues. You may wish to consider using a baffle wall, as an example.
> *
> Thank you for the further explanation on this. I'm wondering if it would be safest to drape velvet directly over the styrofoam of the ICF to keep the hard surfaces at bay. I do need to darken it up back there. I will have about 8" of the angled turret remaining in front of the screen once the screen wall and speaker shelving is built. I could build a baffle wall on each side to eliminate the angles, but I'm thinking that could cause odd deflection as well. Maybe it's just one of those things I should leave well enough alone.
> 
> * 3. Is 5/8" better than 1/2" drywall? Yes. Is it a HUGE difference? No. You're talking less than a handful of STC points. That said, the more layers, the more the difference is amplified. If you don't need absolutely the best sound proofing then you'll likely be fine with the 1/2". I understand the motivation of not moving 5/8" sheetrock.  The key is really to use a dampener in between - a viscoelastic compound; e.g. Green Glue, Quiet Glue, TiteBond, etc. (btw, don't use TiteBond).
> 
> Presuming a 2x4 wall cavity with wood studs, insulation in the walls, and the sheetrock attached directly to the walls (i.e. no clips & channel, etc.), the delta between 1x 5/8" sheetrock and 2x 5/8" sheetrock with no glue in between is 2 or 4 STC, depending on your source of info (i.e. who's test you're reading). The delta between 2x 5/8" with no viscoelastic glue and 2x 5/8" DW with Green Glue in between is 7-11 STC. If you use clips & channel + viscoelastic glue, the delta jumps to 20-23 STC (a SUBSTANTIAL difference).
> 
> *I think I'm sold on the double dry wall with clips and channel. I do need to get educated more on how to properly do the clips and channel, so I will research that some. I'm sure a search in this thread will yield something educational for me, but if you know of a specific thread or search that I should do, I would appreciate it. I will plan to do this on all of the wood framed walls. I'm scratching the OSB idea, so my final dilemma is 1/2" vs. 5/8". Unfortunately the basement is finished too much to bring down 12' sheets anymore, but I'm not overly upset about that. *
> 
> 4. I would recommend clips & channel at least on your common (interior) walls. Ideally, you'd have either a) complete room-within-a-room (double stud wall and independent [floating] ceiling); or b) clips & channels on all walls and ceiling. That would be your best isolation. If you like to play movies and music loud and your significant other hates that, this would be your best bet (including viscoelastic glue in between 2x DW layers on all surfaces). You could still skimp a bit and go with 1/2" sheetrock. The isolation offered by the clips & channel + viscoelastic glue will do more for you than the extra mass of the 5/8" drywall (though mass is a big helper in absorption).
> 
> If you don't blare your content super loud all the time, you could compromise and use more isolation for those common walls. It would save you time and money. Just depends on your priority. The biggest factor is it's obviously very difficult to re-do anything in the future if you feel you didn't do enough the first time around.
> 
> Many people on this forum will tell you to goto the max with isolation, but IMHO one needs to be practical if you're not an ADHD audiophile and this is your home. Like I said, it all depends on your priorities and needs/wants.
> 
> *We have a very open design on our house, so I'm thinking I better do the sound control right the first time around. I'm at the stage where it is easy to do, so I don't want to be kicking myself later on down the road.*


Thanks again for all of your assistance! Obviously you've got an open invite to check out the theater when it's completed. Decent excuse for a trip to Alaska, don't ya think?


----------



## granroth

ncabw said:


> I want to do some soundproofing in between my ceiling joist. I see it's best to do DD with GG. I will be using 5/8 DW. I can't get this in between every joist with the existing duct work installed. I have about 24 joist going across and I can get about 20 done leaving 4 that I can't get 2.
> 
> 1)So should I still do the 20 or would I be wasting my time and money since I can't do them all.
> 
> 2) can I not do the GG just double up on the drywall?


Yes, it's all just a matter of degrees and wether or not a solution meets your requirements. If you are expecting X results but your solution just provides Y, then you'll be disappointed. But if you only expected Y from the start, then anything more is overkill.

Let's start with the fact that doing anything is going to be measurably better than doing nothing. Filling 20 of 24 joist bays will absolutely make a difference as that will attenuate a significant amount of sound energy. Some will absolutely flank around the treated bays into untreated ones but very possibly not enough to bother you.

Likewise with using drywall without GG. The additional mass is the bulk of the benefit anyway and the GG just adds an extra "kick" with its damping. I've always put GG in the "very nice to have if you can afford it" category vs the "must install" like extra mass.

Let's take a step back, though... why are you wanting to treat the inside of the joist bays? Is this just an extra step in addition to the primary treatment of the ceiling itself? If it's a standalone treatment then... well, it will certainly do _something_ but it does get less likely that it'll do enough to satisfy what you have in mind. Handling the joists bays is traditionally the last little bit done to eek out the final bits of performance out of a comprehensive solution and almost never done standalone.


----------



## Livin

granroth said:


> Yes, it's all just a matter of degrees and wether or not a solution meets your requirements. If you are expecting X results but your solution just provides Y, then you'll be disappointed. But if you only expected Y from the start, then anything more is overkill.
> 
> Let's start with the fact that doing anything is going to be measurably better than doing nothing. Filling 20 of 24 joist bays will absolutely make a difference as that will attenuate a significant amount of sound energy. Some will absolutely flank around the treated bays into untreated ones but very possibly not enough to bother you.
> 
> Likewise with using drywall without GG. The additional mass is the bulk of the benefit anyway and the GG just adds an extra "kick" with its damping. I've always put GG in the "very nice to have if you can afford it" category vs the "must install" like extra mass.
> 
> Let's take a step back, though... why are you wanting to treat the inside of the joist bays? Is this just an extra step in addition to the primary treatment of the ceiling itself? If it's a standalone treatment then... well, it will certainly do _something_ but it does get less likely that it'll do enough to satisfy what you have in mind. Handling the joists bays is traditionally the last little bit done to eek out the final bits of performance out of a comprehensive solution and almost never done standalone.


Your your points. Next year I'm tearing out the ceiling of an already finished basement (prior owner did it). Hoping the below plan gets me the 80/20 rule on 'cost & effort' vs 'benefit' to isolate footfall/impact sound (main concern) and sound leakage from HT into living-room above (secondary concern)

Current plan...

1. Leave the current, standard, 1/2" DW walls - doing nothing new
2. Replace the stairwell hollow core door with solid core. Stairwell is folded, so sound must turn 90 degrees to get both in and out of the room, so it is already darn good attenuation even with doors open
3. Tear out all of existing the ceiling
4. Replacement ceiling:
a. add 5/8" DW between joists, a much as possible... not every cavity is possible due to vents/wiring - not planning to use GG
b. add 2x4 cross bracing between joists to increase joists 'stiffness'... thinking less flex = less vibration
c. hang 5/8" DW/GG/DW on basic clips/channel
d. install roll insulation in all joist cavities where possible (not possible to in vent cavities)
e. build DW/GG/DW "boxes" for the 4 atmos ceiling speakers
5. Thick drapes/window coverings over windows & glass doors
6. a few (minimal) absorption and dispersion DIY panels on walls/ceiling (no idea where these will go until the room is complete)


----------



## BP

granroth and other knowledge ones:
I am finally giving up on this process. It appears I will be wasting my money. 
As granroth suggested leakage will be an issue. And make me feel the effort was wasted. 
I think the world of Ted White. After digging into my project he advised me that "holes" created by frames of large sliding glass doors and a stairwell would negate all my planned soundproofing efforts, including an expensive glass wall. 
Just adding a layer of wallboard to increase the mass will be all I should try. 
He didn't even suggest GG!
So I guess I am revising my objective to deal more with mid and high frequencies. 
Not sure if it's stil worth Roxsuling the ceiling and even 1 rear wall anymore. 
Count me as depressed!!
bp


----------



## healthnut

BP said:


> granroth and other knowledge ones:
> I am finally giving up on this process. It appears I will be wasting my money.
> As granroth suggested leakage will be an issue. And make me feel the effort was wasted.
> I think the world of Ted White. After digging into my project he advised me that "holes" created by frames of large sliding glass doors and a stairwell would negate all my planned soundproofing efforts, including an expensive glass wall.
> Just adding a layer of wallboard to increase the mass will be all I should try.
> He didn't even suggest GG!
> So I guess I am revising my objective to deal more with mid and high frequencies.
> Not sure if it's stil worth Roxsuling the ceiling and even 1 rear wall anymore.
> Count me as depressed!!
> bp




I can attest personally to the fact that simply stiffing multiple layers of SafeNSound does very little to reduce sound transmission. I've had to completely rebuild the room and isolate tonget good results 


Sent from my iPhone using Tapatalk


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## bsw

*Puzzled by my options....*

I am a long time lurker and done a ton of reading here but I still have a few questions. I am in the planning stages of my theater and struggling with soundproofing. Most of my problems result from the width of my room. It is rather narrow, being a couple of inches shy of 12 feet from foundation wall to interior wall. On the foundation wall I was planning 2 inches of foam insulation, a one inch gap, a 2x4 wall (stuffed with insulation) and two sheets of 5/8 drywall with GG. I figure right there I am losing almost 8 inches. I live in a cold climate so don’t want to lose the insulation and the foam doubles as a vapor barrier. The opposing interior wall is pre-existing and follows a beam. It also hides the support posts. I can’t easily move it and would prefer not to lose space to clips and channel. I might be able to recess the clips into the wall on blocking but it is built on steel studs and I am not exactly sure how that would work. On the other side of the wall are my furnace room, bathroom, and games room. I don’t really care if some sound leaks to these spaces but would become concerned if it was enough to get picked up by the duct work or bleed substantially through the ceiling. I am not aiming for perfect sound proofing but enough that I can watch movies at a reasonable volume, while others sleep on the second floor. Having spewed all that background here are my questions:

1. Is it acceptable to frame the foundation wall on 2x3s, attached with IB-3 clips and have the insulation bridge the one inch gap to the foundation wall rather than use 2x4s and a one inch air gap?

2. On the interior wall if I just use IB-3 style clips, instead of clips and channel, would it block enough sound so as to not get picked up by the ducts? I can’t seem to find STC or other ratings for these clips. I am thinking of IB-3 clips, double 5/8 drywall with GG on the theater side and a single layer of 1/2 on the outside. These walls are already finished on the non-theater side but I think I can shorten them in place and install IB-3s. My gut is this is fine as it will still be much better than the door….

3. If the answer to number two is “No” is it acceptable to use clips and channel on the outside of the wall (inside the furnace room, bathroom, etc.)? I would rather not have to tear out and rebuild these walls but I could.

I am of course open to any other ideas that will help me achieve my goals of maximizing width and sound proofing. Thanks in advance for any advice.


----------



## HT Geek

healthnut said:


> I can attest personally to the fact that simply stiffing multiple layers of SafeNSound does very little to reduce sound transmission.


Just adding/clarifying that Roxul Safe'n'Sound has the greatest effect in 500+ Hz frequencies. If one wants more uniform absorption, Rockboard 80 comes to mind and it has a relatively consistent damping effect across the whole spectrum. That said, insulation is going to have the least significant impact compared to isolation, mass, etc. But it's not without merit.


----------



## HT Geek

arcticbowman said:


> With the ceiling I think I will do a single layer of rock using the clips and channel, stuff the 12" cavity with insulation and call it good. With the added plywood and gypcrete on the dining room level, I'm keeping my fingers crossed that it will be sufficient. I also think I will go a little larger on the soffit. Right now we have it at 8" high by 16" deep, however the last 6 of depth" is going to be a channel for rope lights. I may lower it a couple inches to 10". I don't think I will be doing much more with HVAC in that room. I have a 4X10 supply line to feed the room with a little fresh air, but we hardly use the HVAC.


IMHO, that's a good plan for your situation, based on what you've described so far.

6" sounds like a rather wide light tray, FWIW. You could also consider placing it externally to the soffit. Here's an example. Food-for-thought.

Regarding the HVAC vent: just a suggestion you take into account your total cubic volume of the room, how you will control heat/cooling into the room, and how your equipment and max # people in the room at one time may impact your comfort. Other factors to consider include noise. I'm just suggest you don't overlook HVAC from several perspectives. And since you are building a soffit anyway, one option would be to re-locate the single existing vent to vents in either side soffit as a means to control air flow, noise, etc.

Another factor related to HVAC is the fact that doing a good job of sound-proofing your room also entails making it air-tight. Thus, your HT room's air will become stale pretty quickly while watching a long movie or other activities. This is also why you should place a return vent in your HT room. Think of your HT room as a mini-climate ecosystem.




> I'm wondering if it would be safest to drape velvet directly over the styrofoam of the ICF to keep the hard surfaces at bay. I do need to darken it up back there. I will have about 8" of the angled turret remaining in front of the screen once the screen wall and speaker shelving is built. I could build a baffle wall on each side to eliminate the angles, but I'm thinking that could cause odd deflection as well. Maybe it's just one of those things I should leave well enough alone.


It's not a bad idea to drape something over the ICF, however I'd suggest MLV (Mass Loaded Vinyl). You'd need to figure out a suitable way of affixing it to the ICF (e.g. concrete screws with big washers). That would be much more useful than velvet as it would attenuate all the frequencies before and after they bounce off the ICF.

Having that wall extend to the sides of your stage may exacerbate the concern I raised about sound deflection off that wall. However, it's also an opportunity to turn it into a style choice relative to your stage. For instance, you could create triangle shapes on the sides of your stage and place your side speakers outside the screen real estate, such as this theater design. Just an idea.




> I think I'm sold on the double dry wall with clips and channel. I do need to get educated more on how to properly do the clips and channel, so I will research that some. I'm sure a search in this thread will yield something educational for me, but if you know of a specific thread or search that I should do, I would appreciate it. I will plan to do this on all of the wood framed walls. I'm scratching the OSB idea, so my final dilemma is 1/2" vs. 5/8".


There's lots of info on AVS, as I'm sure you know. This thread will help get you started tho. 




> We have a very open design on our house, so I'm thinking I better do the sound control right the first time around. I'm at the stage where it is easy to do, so I don't want to be kicking myself later on down the road.


Yes. Agreed.




> Thanks again for all of your assistance! Obviously you've got an open invite to check out the theater when it's completed. Decent excuse for a trip to Alaska, don't ya think?


Thanks! I may take you up on that offer in July when it is 110 here in Austin. LoL.


----------



## HT Geek

This is perhaps a bit better example of upward soffit lighting (versus my previous post).


----------



## ncabw

HT Geek said:


> I understand your conundrum, but it's a bit of a loaded question as you put it above. By that I mean - for example - if your room's ceiling is attached to the structural ceiling joists, then what you are proposing will have a minimal benefit because sound will travel via the ceiling joists to which your drywall is directly attached.
> 
> Now, if let's say you have some sort of isolation (such as clips & channel) between your ceiling joists and your drywall ceiling, then at that point doing what you propose begins to become more effective as you are blocking some of the sound traversing through the open cavities in the ceiling between the joists.
> 
> All that said, if you still want to consider implementing your plan, a diagram would be helpful for other folks to ascertain the potential effectiveness. Photographs would be even better. Some folks on AVS will tell you it's an all-or-nothing proposition, but I personally believe the devil is in the details. There are some cases where not having 100% of the joists dampened might not be a big deal. So, if you have photos or a diagram, please share so that we can do a more thorough job of advising.



I will post some pictures soon. 

Sorry I did forget to mention I will using a channel for the ceiling and will also add some roxul sound insulation in between the joists. 

I know I won't have complete soundproof. Just want to do the most I can with what I already have.


----------



## ncabw

granroth said:


> Yes, it's all just a matter of degrees and wether or not a solution meets your requirements. If you are expecting X results but your solution just provides Y, then you'll be disappointed. But if you only expected Y from the start, then anything more is overkill.
> 
> Let's start with the fact that doing anything is going to be measurably better than doing nothing. Filling 20 of 24 joist bays will absolutely make a difference as that will attenuate a significant amount of sound energy. Some will absolutely flank around the treated bays into untreated ones but very possibly not enough to bother you.
> 
> Likewise with using drywall without GG. The additional mass is the bulk of the benefit anyway and the GG just adds an extra "kick" with its damping. I've always put GG in the "very nice to have if you can afford it" category vs the "must install" like extra mass.
> 
> Let's take a step back, though... why are you wanting to treat the inside of the joist bays? Is this just an extra step in addition to the primary treatment of the ceiling itself? If it's a standalone treatment then... well, it will certainly do _something_ but it does get less likely that it'll do enough to satisfy what you have in mind. Handling the joists bays is traditionally the last little bit done to eek out the final bits of performance out of a comprehensive solution and almost never done standalone.


Sorry I forgot to mention I will be using channels on the ceiling and most likely DD. I will definitely be adding roxul between the joists.


----------



## HT Geek

ncabw said:


> I will post some pictures soon.
> 
> Sorry I did forget to mention I will using a channel for the ceiling and will also add some roxul sound insulation in between the joists.
> 
> I know I won't have complete soundproof. Just want to do the most I can with what I already have.


Sounds like you are on the path of enlightenment.


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## amit916

I was going to go the route of putting my lights in the soffit, but I also have my supply/returns coming through the soffit. Do people just cut holes in the same drop to to place their lights? Wouldn't that introduce new places for sound to escape?

Or should I be thinking about building a 2 step soffit? I've heard Ted mention something about a 4 inch hole (don't hold me to this) won't be that big of a deal since LFE would pass right through anyways and high-freq energy would get caught once they go through the hole.


----------



## HT Geek

amit916 said:


> I was going to go the route of putting my lights in the soffit, but I also have my supply/returns coming through the soffit. Do people just cut holes in the same drop to to place their lights?


Many do, yes.




> Wouldn't that introduce new places for sound to escape?


Yes. However, 2 thoughts: 1) what else are you going to do?? and 2) you can mitigate this by building backer boxes for your light cans.




> Or should I be thinking about building a 2 step soffit? I've heard Ted mention something about a 4 inch hole (don't hold me to this) won't be that big of a deal since LFE would pass right through anyways and high-freq energy would get caught once they go through the hole.


You *could* build a 2-step soffit. If you are really concerned about sound leakage through your recessed light cans, that could mitigate it - depending on how you implement the soffit. It would be easier IMHO to build backer boxes for your lights.

In my HT, I didn't worry about it. I only built backer boxes where the light cans would have been too close to my HVAC flex duct or some other object that was heat sensitive.


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## ncabw

Here are some pics. It doesn't look that bad I think i can still get the DD between the Ijoist where the duct and plm is. The bigger HVAC run is actually just out side my room.

So think I'm going to go with DD + GG between the joists. worst case is i don't get it between to joists out of the roughly 20 spaces i have.


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## HT Geek

Wow. That is gonna be a pain. I hope it's worth your time and effort.

I have forgotten if you were planning to decouple the ceiling as well. You certain you wouldn't rather stuff insulation between the joists and de-couple your HT room ceiling??? It seems to me you wouldn't need to put 2x DW in those cavities if you went that route. Just stuff some insulation in there for good measure.

I'm thinking those metal ducts will be a bigger headache (i.e. deadening them or replacing them with flex-duct).


----------



## ncabw

HT Geek said:


> Wow. That is gonna be a pain. I hope it's worth your time and effort.
> 
> I have forgotten if you were planning to decouple the ceiling as well. You certain you wouldn't rather stuff insulation between the joists and de-couple your HT room ceiling??? It seems to me you wouldn't need to put 2x DW in those cavities if you went that route. Just stuff some insulation in there for good measure.
> 
> I'm thinking those metal ducts will be a bigger headache (i.e. deadening them or replacing them with flex-duct).


I'm decoupling and was going to add insulation. If people don't think there is much value in adding the DD between the joists I won't.


----------



## HT Geek

ncabw said:


> I'm decoupling and was going to add insulation. If people don't think there is much value in adding the DD between the joists I won't.


It's a matter of degree. How important is it to you to squeeze out every last ounce of sound isolation? 

If you add the DD between the joists, you'll be further damping airborne sound, versus the sound that travels via vibration along the joists between floors. There's definitely merit in the DD between joists approach, but it's a much smaller gain when compared to decoupling. 

The downside is you won't know until after the fact. If sound deadening between the floors is a big priority, you may want to err on the side of overkill because at that point retrofitting it in there later on would be an even bigger effort than it is right now.

I hope that helps. This is one of those areas that is very subjective. How well damped/padded of a room is good enough??? It's personal preference.

If you want absolute best sound proofing, then do it. Just bear in mind there are many other ways for sound to escape, and if that happens then the extra work may be for nought.


----------



## ncabw

Thanks for the info/help. For now I will only do the joists if I have time if not I will just decouple the ceiling and DD and insulation. 

I'm not looking for The best sound proofing just something that's better the the standard rooms.


----------



## HT Geek

ncabw said:


> Thanks for the info/help. For now I will only do the joists if I have time if not I will just decouple the ceiling and DD and insulation.
> 
> I'm not looking for The best sound proofing just something that's better the the standard rooms.


FWIW... and this is coming from the perspective of someone who values sound isolation but is not a sound-isolation-nut per se.... I might stuff some insulation in there, but that's about it. I believe your time will be better spent elsewhere. If you decide you're really concerned about it, you could increase the # of clips in your ceiling and put up another layer of drywall. It would be a lot less work for comparable results.

Even with just clips & channel & DD, you are going to notice a huge improvement when comparing before and after results.


----------



## ncabw

I live in Toronto Canada and i don't see anyone selling the IB-1 Soundproofing Clip they all sell the RSIC-1 is this comparable?

now that I'm reading more into this i'm definitely going to add the clips for the ceiling. Would i have to add any to my walls? So far i have a 10" poured foundation then I have spray foamed another 3.5". From here I was now going to build my walls with 3-5/8" metal stud. In total 3 outside walls were going to be done like this. For the 4th dividing wall its going to be 3-5/8" metal stud with DD on one side with sound insulation. options are

1) decouple all the walls 
2) decouple just the dividing wall
2) decouple no walls 

Any pros or cons for using metal stud? I wont be doing wood no matter what my dad's drywall company will be doing all the work for free and since they deal in the commercial office space this is what they work with all the time.


----------



## kmhvball

ncabw said:


> I live in Toronto Canada and i don't see anyone selling the IB-1 Soundproofing Clip they all sell the RSIC-1 is this comparable?
> 
> now that I'm reading more into this i'm definitely going to add the clips for the ceiling. Would i have to add any to my walls? So far i have a 10" poured foundation then I have spray foamed another 3.5". From here I was now going to build my walls with 3-5/8" metal stud. In total 3 outside walls were going to be done like this. For the 4th dividing wall its going to be 3-5/8" metal stud with DD on one side with sound insulation. options are
> 
> 1) decouple all the walls
> 2) decouple just the dividing wall
> 2) decouple no walls
> 
> Any pros or cons for using metal stud? I wont be doing wood no matter what my dad's drywall company will be doing all the work for free and since they deal in the commercial office space this is what they work with all the time.


I would think the 3 concrete walls are likely sufficiently decoupled as it is. I don't know if spray foam somehow creates some coupling, but my impression would be that is minimal. My theater also has 3 concrete foundation walls, so, no clips/channel on those for me (but I did use batt insulation). These walls did all use IB-3 Clips to attach the vertical wall to the floor joists.. you don't want the top plate of the vertical wall touching the floor joists. The word escapes me at the moment, but basically if the walls touch the floor joists, the vibrations can transfer from wall to floor (and above!).

You should decouple the last wall/ dividing wall. I did a double stud wall, but that does take 10" or so. Clips & Channel would work fine.

From everything I read, metal studs are slightly better for sound transmission... I know I read this in the context of normal stud walls with no clips/ channel. I don't recall if you see that same benefit with clips & channel, but I would certainly think at a minimum it wouldn't be any worse. I have no idea about the 'pull out' strength of metal vs wood and whether the weight of multiple drywall layers on metal is any concern. Not suggesting it is, but I don't know, so, thought I would at least mention it.


----------



## HT Geek

ncabw said:


> I live in Toronto Canada and i don't see anyone selling the IB-1 Soundproofing Clip they all sell the RSIC-1 is this comparable?


Yes and no. The IB-1 is the most basic clip. It does de-couple, but not as well as the RSIC-1. The IB-1 is better than no clip. I don't recall the differences in performance (try a search engine if you must know the difference in specs).



> now that I'm reading more into this i'm definitely going to add the clips for the ceiling. Would i have to add any to my walls?


You do not "have to" do that, no. Should you? Depends on your needs/concerns. Your neighbors will appreciate the fact you have concrete walls. However, it will be a bane to you in the room if you don't take steps to control its reflectivity. Concrete _reflects _sound hitting it directly. Your interior walls will benefit greatly from using drywall and other materials to reduce those reflections. 

Concrete makes a good sound _barrier _- provided it is a _minimum_ of 6" thick. Concrete is commonly misconstrued as being a sound absorber (it is not). Concrete is a barrier material. Rockwool OTOH, is an example of an absorber. With regards to your experience inside the room, 6"+ thick concrete will benefit you in regards to keeping outside noise outside, in the same way it will benefit your neighbors from the sound inside your room.

Here are some references if you want to learn more details or have trouble falling asleep at night (documents also attached if available):

1. Belliston, H.W. and Litvin, A. *Sound Transmission Loss Through Concrete and Concrete Masonry Walls*. _Journal of the American Concrete Institute_, No. 12/Vol. 75 (December, 1978).
Notes: Old, but pertinent. Includes test data on 6 and 8 inch thick concrete walls for sound transmission through walls with and without 8 pcf Rockwool, 1/2" gypsum drywall. Pay particular attention to *Table 1: Sound Transmission Class PCA Tests*. 

2._ Sound Transmission Class Ratings For Concrete Masonry Walls_. National Concrete Masonry Association (2012).
See *Table 1: Calculated STC Ratings for Concrete Masonry Walls* provides a short-hand perspective of how thicker or thinner layers of concrete relate to dissipating sound between either side of the wall (4-12" thick).

3. Lamancusa, J.S. _Transmission of Sound Through Structures_. Pennsylvania State University (December 1, 2000).
Excerpt from an engineering class. Skim through it and you'll find succinct explanations on various points of sound transmission relative to your room.

4. Warnock, A.C.C. _Controlling Sound Transmission Through Concrete Block Walls_. Institute for Research in Construction (1998).
Both STC and TL data on various concrete wall configurations, including double-leaf concrete walls.




> So far i have a 10" poured foundation then I have spray foamed another 3.5". From here I was now going to build my walls with 3-5/8" metal stud. In total 3 outside walls were going to be done like this. For the 4th dividing wall its going to be 3-5/8" metal stud with DD on one side with sound insulation. options are
> 
> 1) decouple all the walls
> 2) decouple just the dividing wall
> 2) decouple no walls


I'd suggest - for the exterior walls - stick with your plan but leave a 1" gap between the metal studs and exterior walls. Apply DD with Green Glue or Quiet Glue in between. I don't see a need to de-couple those walls with clips & channel.

Note: I could not locate a link to the Belliston & Litvin doc.


----------



## kciaccio

I live in the Houston Texas area..Does anybody know where you can get proper hat channel and isolation clips locally?


----------



## HT Geek

kciaccio said:


> I live in the Houston Texas area..Does anybody know where you can get proper hat channel and isolation clips locally?


I live in the Austin metro. I've seen hat channel systems sold at several drywall contractor supply stores. I can't speak to Houston personally, but suggest you call around or visit a few showrooms. DON'T visit the Big Box stores. There are local suppliers here who know what you're talking about. No doubt the same is true of Houston.

If you know anyone with connections to builders in the condo or apartment markets, you may want to start with them for supplier leads.


----------



## kciaccio

HT Geek said:


> I live in the Austin metro. I've seen hat channel systems sold at several drywall contractor supply stores. I can't speak to Houston personally, but suggest you call around or visit a few showrooms. DON'T visit the Big Box stores. There are local suppliers here who know what you're talking about. No doubt the same is true of Houston.
> 
> If you know anyone with connections to builders in the condo or apartment markets, you may want to start with them for supplier leads.


Appreciate it...You would think I am the only person in Houston trying to do a proper theater room for as hard as it is to find this stuff..geez...


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## ncabw

HT Geek said:


> Yes and no. The IB-1 is the most basic clip. It does de-couple, but not as well as the RSIC-1. The IB-1 is better than no clip. I don't recall the differences in performance (try a search engine if you must know the difference in specs).
> 
> You do not "have to" do that, no. Should you? Depends on your needs/concerns. Your neighbors will appreciate the fact you have concrete walls. However, it will be a bane to you in the room if you don't take steps to control its reflectivity. Concrete _reflects _sound hitting it directly. Your interior walls will benefit greatly from using drywall and other materials to reduce those reflections.
> 
> Concrete makes a good sound _barrier _- provided it is a _minimum_ of 6" thick. Concrete is commonly misconstrued as being a sound absorber (it is not). Concrete is a barrier material. Rockwool OTOH, is an example of an absorber. With regards to your experience inside the room, 6"+ thick concrete will benefit you in regards to keeping outside noise outside, in the same way it will benefit your neighbors from the sound inside your room.
> 
> Here are some references if you want to learn more details or have trouble falling asleep at night (documents also attached if available):
> 
> 1. Belliston, H.W. and Litvin, A. *Sound Transmission Loss Through Concrete and Concrete Masonry Walls*. _Journal of the American Concrete Institute_, No. 12/Vol. 75 (December, 1978).
> Notes: Old, but pertinent. Includes test data on 6 and 8 inch thick concrete walls for sound transmission through walls with and without 8 pcf Rockwool, 1/2" gypsum drywall. Pay particular attention to *Table 1: Sound Transmission Class PCA Tests*.
> 
> 2._ Sound Transmission Class Ratings For Concrete Masonry Walls_. National Concrete Masonry Association (2012).
> See *Table 1: Calculated STC Ratings for Concrete Masonry Walls* provides a short-hand perspective of how thicker or thinner layers of concrete relate to dissipating sound between either side of the wall (4-12" thick).
> 
> 3. Lamancusa, J.S. _Transmission of Sound Through Structures_. Pennsylvania State University (December 1, 2000).
> Excerpt from an engineering class. Skim through it and you'll find succinct explanations on various points of sound transmission relative to your room.
> 
> 4. Warnock, A.C.C. _Controlling Sound Transmission Through Concrete Block Walls_. Institute for Research in Construction (1998).
> Both STC and TL data on various concrete wall configurations, including double-leaf concrete walls.
> 
> 
> I'd suggest - for the exterior walls - stick with your plan but leave a 1" gap between the metal studs and exterior walls. Apply DD with Green Glue or Quiet Glue in between. I don't see a need to de-couple those walls with clips & channel.
> 
> Note: I could not locate a link to the Belliston & Litvin doc.



Thanks i will read this when i have some time. One last question do i have to add roxul sound insulation to the walls where the concrete foundation is? I Will definitely add it where the wall splits the basement.


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## HT Geek

ncabw said:


> One last question do i have to add roxul sound insulation to the walls where the concrete foundation is? I Will definitely add it where the wall splits the basement.


Well, again you don't _have to_, per se. Aside from helping balance the temperature in your room, it will help attenuate sound (but not by much) - mostly the higher frequencies. It will also help reduce the reflections off the concrete that I mentioned above.


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## kmhvball

ncabw said:


> Thanks i will read this when i have some time. One last question do i have to add roxul sound insulation to the walls where the concrete foundation is? I Will definitely add it where the wall splits the basement.


Most everything I have read, suggests that using 'pink fluffy' is just as good as any other insulation for soundproofing (including Roxul Safe & sound)... and typically speaking, much less expensive. Just a thought.

I did put insulation in the cavities where my wall was against the concrete foundation, my concern was from a 'flanking up the wall', and thought it would be good to have insulation in those studs. 

One thing you'll need to make sure of, is to not have a 'double vapor barrier'. This is something the workers who came out to insulate my basement told me... They were pissed at the lady who had done the estimate for not stating there was already insulation on the walls with vapor barrier... They ended up having to rip off the paper facing in some of the areas where they would have a double vapor barrier.


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## HT Geek

kmhvball said:


> Most everything I have read, suggests that using 'pink fluffy' is just as good as any other insulation for soundproofing (including Roxul Safe & sound)... and typically speaking, much less expensive. Just a thought.


There's a minimal difference in performance, presuming Roxul Safe'n'Sound or AFB, etc. If he went with the firm stuff (e.g. Rockboard) that is closer to OC 703/704/705 but also much more expensive than the normal Roxul products or "pink fluffy."


----------



## Ladeback

kmhvball said:


> Most everything I have read, suggests that using 'pink fluffy' is just as good as any other insulation for soundproofing (including Roxul Safe & sound)... and typically speaking, much less expensive. Just a thought.
> 
> I did put insulation in the cavities where my wall was against the concrete foundation, my concern was from a 'flanking up the wall', and thought it would be good to have insulation in those studs.
> 
> One thing you'll need to make sure of, is to not have a 'double vapor barrier'. This is something the workers who came out to insulate my basement told me... They were pissed at the lady who had done the estimate for not stating there was already insulation on the walls with vapor barrier... They ended up having to rip off the paper facing in some of the areas where they would have a double vapor barrier.


When built my first 2 walls next to the concrete in my basement, I first glued 1" foil backed Styrofoam with an R value of 7 to walls before building the stud walls. This gave me a moisture barrier and a thermal barrier. I will be adding at least a R13 pink insulation in the stud walls against the concrete to help with Flanking and to help keep the room warm.


----------



## jimmykochan

*Double Stud Wall metal guage and spacing question* 


I’ve read a lot of posts here but I have a question about metal stud gauge and spacing for a double stud wall that I haven’t seen addressed. I’m trying to prevent voice noise transmission between rooms in my house and will be using 5/8” DD (~ 4.4 psf weight) & GG. From the metal stud chart (ClarkDietrich Prostud non-composite braced at 48” limiting heights; 5psf lateral load; L/120) it seems I have to use either 20 gauge equalized at 16” oc (0.20” actual; 65KSI steel) or 30MIL at 24” oc (0.31” actual; 33KSI steel). Is one preferable over the other for blocking voices (not worried of LFE)? Do things change if I use two layers of lightweight 5/8” and a third layer of lightweight ½” drywall (~ 5.3 psf weight) so that I could have 2 coatings of GG? Also, I saw a chart from another metal stud manufacturer where they gave higher limiting heights when using DD vs a single layer (still for drywall on just one side of a non-composite wall). Does DD vs SD make a difference to limiting heights? Since the wall isn’t load bearing or exposed to wind for a big lateral load force, I originally was going to use 20 gauge EQ space 24” oc, but now I don’t know. Thanks.


----------



## HT Geek

jimmykochan said:


> *Double Stud Wall metal guage and spacing question*
> 
> 
> I’ve read a lot of posts here but I have a question about metal stud gauge and spacing for a double stud wall that I haven’t seen addressed. I’m trying to prevent voice noise transmission between rooms in my house and will be using 5/8” DD (~ 4.4 psf weight) & GG. From the metal stud chart (ClarkDietrich Prostud non-composite braced at 48” limiting heights; 5psf lateral load; L/120) it seems I have to use either 20 gauge equalized at 16” oc (0.20” actual; 65KSI steel) or 30MIL at 24” oc (0.31” actual; 33KSI steel). Is one preferable over the other for blocking voices (not worried of LFE)? Do things change if I use two layers of lightweight 5/8” and a third layer of lightweight ½” drywall (~ 5.3 psf weight) so that I could have 2 coatings of GG? Also, I saw a chart from another metal stud manufacturer where they gave higher limiting heights when using DD vs a single layer (still for drywall on just one side of a non-composite wall). Does DD vs SD make a difference to limiting heights? Since the wall isn’t load bearing or exposed to wind for a big lateral load force, I originally was going to use 20 gauge EQ space 24” oc, but now I don’t know. Thanks.


Jimmy,

Here's what you need to know:


Metal studs reduce sound transmission slightly better when compared to wood studs
24" O.C. is better than 16" O.C., relative to sound-proofing; reason is you have fewer structural members to transmit vibrations/sound and a larger air mass to dampen sound
Mass is the key relative to DD, so yes your 3-layer sandwich would be superior

If you want to do 3 layers of DW, a 5/8" + 1/2" + 5/8" sandwich is preferable from a freq attenuation perspective (though nothing wrong with 3x 5/8" DW). Technically, this would be superior to either 2x 5/8 or 3x 1/2 because the sound freq absorption is slightly different for 1/2" vs. 5/8" DW.

I'm puzzled why you are referencing lateral load and L/120 as those type of figures are normally associated with horizontal loads (i.e. ceilings), and not walls.


----------



## jimmykochan

HT Geek said:


> Jimmy,
> 
> Here's what you need to know:
> 
> 
> Metal studs reduce sound transmission slightly better when compared to wood studs
> 24" O.C. is better than 16" O.C., relative to sound-proofing; reason is you have fewer structural members to transmit vibrations/sound and a larger air mass to dampen sound
> Mass is the key relative to DD, so yes your 3-layer sandwich would be superior
> 
> If you want to do 3 layers of DW, a 5/8" + 1/2" + 5/8" sandwich is preferable from a freq attenuation perspective (though nothing wrong with 3x 5/8" DW). Technically, this would be superior to either 2x 5/8 or 3x 1/2 because the sound freq absorption is slightly different for 1/2" vs. 5/8" DW.
> 
> I'm puzzled why you are referencing lateral load and L/120 as those type of figures are normally associated with horizontal loads (i.e. ceilings), and not walls.





Thanks for the quick response and good info; I agree with your 3 points. I mention the lateral load & L/120 because I think that they come into play for the limiting height. According to most of the limiting height tables, if I go 24” o.c., I need 30 mil studs to span the just under 9’ I have (though I may be able to get away with old school 27mil (real 22 gauge) or high tensile strength 23 mil (30 EGD)). From other reading, it seems that thinner gauge (25) studs is better than heavy gauge (20 or 18) studs (at least for the 3-5/8” studs and on single stud assemblies that are usually tested) for sound reduction but I want to make sure that the wall can hold up the two (or maybe 3) layers of drywall without any issues. Thanks again for the great info.


----------



## jrref

jimmykochan said:


> Thanks for the quick response and good info; I agree with your 3 points. I mention the lateral load & L/120 because I think that they come into play for the limiting height. According to most of the limiting height tables, if I go 24” o.c., I need 30 mil studs to span the just under 9’ I have (though I may be able to get away with old school 27mil (real 22 gauge) or high tensile strength 23 mil (30 EGD)). From other reading, it seems that thinner gauge (25) studs is better than heavy gauge (20 or 18) studs (at least for the 3-5/8” studs and on single stud assemblies that are usually tested) for sound reduction but I want to make sure that the wall can hold up the two (or maybe 3) layers of drywall without any issues. Thanks again for the great info.


Just one more comment. You mentioned that you are trying to reduce or eliminate voice transmission between rooms. This is very easy to do since these frequencies are easy to block and the power of someone's voice, even if they are yelling, is way less then the db power of a home theater for example. That said you can probably use something simpler like two 5/8 sheetrock with GG or just use Quiet Rock or something equivalent and call it a day. I used Quiet Rock and it completely blocked the voice transmission 100% between the common wall with my neighbor in my condo.


----------



## HT Geek

jimmykochan said:


> Thanks for the quick response and good info; I agree with your 3 points. I mention the lateral load & L/120 because I think that they come into play for the limiting height. According to most of the limiting height tables, if I go 24” o.c., I need 30 mil studs to span the just under 9’ I have (though I may be able to get away with old school 27mil (real 22 gauge) or high tensile strength 23 mil (30 EGD)). From other reading, it seems that thinner gauge (25) studs is better than heavy gauge (20 or 18) studs (at least for the 3-5/8” studs and on single stud assemblies that are usually tested) for sound reduction but I want to make sure that the wall can hold up the two (or maybe 3) layers of drywall without any issues. Thanks again for the great info.


Just to be clear... your mention of L/120... that is for your ceiling, correct? L is a measure of load deflection at the center (weakest) point of a beam (due to gravity). On your walls, gravity is primarily pulling down - as long as your studs are straight. There's very little bending pressure (from the top, inward). Furthermore, if your edges are all square, when you apply a ceiling then the force of the ceiling (downward) effectively mitigates that upper inward gravitational force at the top of the wall (which is negligible to begin with, relative to downward force on the wall).

Point is the strength of the stud to stand upright and support a load from top to bottom is the important factor of vertical studs. The weight of the drywall is not going to be an issue. Look at how thin RC and hat channel are. 26 gauge steel normally. Yet they hold 3 layers of DW + other objects just fine.

There are 3 issues I'd be concerned with in your situation: 

1) If your walls are >10' tall, with wood studs you definitely need lateral supports. With steel, it's less clear. I'm not aware of any tables for that scenario. I don't know if you would need lateral support at that point or not, but it would seem prudent to me.

2) Are any of your walls going to be load bearing (as in holding up the remainder of your home)? If this is a room-within-a-room then the answer is NO, of course. If they were load bearing, then there are tables for that. I have yet to see any tables for steel studs that are not load bearing. There may be some.

3) Your ceiling is the big question mark. Those joists need to be able to handle the ceiling load without exceeding L/240 deflection. I'd start with that and see what size joists you will need, and then choose complimentary vertical studs. For example, if you need 3 5/8" thick joists then use that size or larger studs to support the joists.

Now, you mentioned double-stud walls. Presuming your intent is to build a double-stud or "room-within-a-room" with steel studs and steel joists (ceiling), why would you be looking at a L/120 rating? Not sure where you are located, L/240 is typical in the States (per IRBC). 

If you want/need to use thinner joists, you can reduce deflection somewhat by sistering the joists (though that doubles the cost and in most cases it's not worth it). 

Are you planning for L/120 because of your building code or personal preference?

Let me know if I'm off-the-mark and not getting your scenario clearly, and I'll try again. Otherwise, as I said I would figure out the ceiling joists first. Then let that guide you on the wall studs (same or larger depth/width). With steel studs you also need to be cognizant of what options or requirements you will have for securing the studs to the floor (and laterally if required), and how the studs and joists will be secured to one another.


----------



## jimmykochan

jrref said:


> Just one more comment. You mentioned that you are trying to reduce or eliminate voice transmission between rooms. This is very easy to do since these frequencies are easy to block and the power of someone's voice, even if they are yelling, is way less then the db power of a home theater for example. That said you can probably use something simpler like two 5/8 sheetrock with GG or just use Quiet Rock or something equivalent and call it a day. I used Quiet Rock and it completely blocked the voice transmission 100% between the common wall with my neighbor in my condo.






When I said voices, I meant regular tv & video game sounds topped with wild playing, screaming, stomping, fighting with each other, animal sound imitating, sugar-crazed bouncing off the walls kids “voices” with the all too often overly stressed yelling of adults thrown in for good measure J


----------



## jimmykochan

HT Geek said:


> Just to be clear... your mention of L/120... that is for your ceiling, correct?
> 
> Point is the strength of the stud to stand upright and support a load from top to bottom is the important factor of vertical studs. The weight of the drywall is not going to be an issue. Look at how thin RC and hat channel are. 26 gauge steel normally. Yet they hold 3 layers of DW + other objects just fine.
> 
> There are 3 issues I'd be concerned with in your situation:
> 
> 1) If your walls are >10' tall,
> 
> 2) Are any of your walls going to be load bearing (as in holding up the remainder of your home)?
> 
> 3) Your ceiling is the big question mark.
> 
> Now, you mentioned double-stud walls. Presuming your intent is to build a double-stud or "room-within-a-room" with steel studs and steel joists (ceiling), why would you be looking at a L/120 rating? Not sure where you are located, L/240 is typical in the States (per IRBC).
> 
> If you want/need to use thinner joists, you can reduce deflection somewhat by sistering the joists (though that doubles the cost and in most cases it's not worth it).
> 
> Are you planning for L/120 because of your building code or personal preference?
> 
> Let me know if I'm off-the-mark and not getting your scenario clearly, and I'll try again. Otherwise, as I said I would figure out the ceiling joists first. Then let that guide you on the wall studs (same or larger depth/width). With steel studs you also need to be cognizant of what options or requirements you will have for securing the studs to the floor (and laterally if required), and how the studs and joists will be secured to one another.





Everything I’m writing here solely concerns the wall (I’m going to suspend the ceiling via clips and such). It’s a double stud wall with floor to underside of above of just under 9’; wall is NON-load bearing. It seems there’s no need to worry about L/120…hurray. I’ll go with high strength steel metal studs of either 19 MIL (~ 0.019” 20 gauge EQ) or 23 MIL (~0.023” 30 MIL EQ); with 5/8” DD & GG (and of course insulation between walls) to start and maybe add another layer of ½” over that if it’s not enough.
 

Thank you so much for the insight; a few more questions if I may please. Any benefit (or any harm) in putting iso-sill under & over the sill plates and joist tape over the studs before putting up the drywall? Since I’m doing the work myself, if there’s even a small benefit, it’s worth the small extra up front cost.


----------



## HT Geek

jimmykochan said:


> Everything I’m writing here solely concerns the wall (I’m going to suspend the ceiling via clips and such). It’s a double stud wall with floor to underside of above of just under 9’; wall is NON-load bearing. It seems there’s no need to worry about L/120…hurray. I’ll go with high strength steel metal studs of either 19 MIL (~ 0.019” 20 gauge EQ) or 23 MIL (~0.023” 30 gauge EQ); with 5/8” DD & GG (and of course insulation between walls) to start and maybe add another layer of ½” over that if it’s not enough.



You should be good with DD + GG. I suspect you'll be pleased with that on a double stud config. It's going to be good. 

If I were you... I'd go with 20 gauge steel. Just sayin'. 

30-gauge is way too thin.
  



> Any benefit (or any harm) in putting iso-sill under & over the sill plates




Yes. No harm. Do it.



> and joist tape over the studs before putting up the drywall?


Don't do it. Waste of time and money.


----------



## HT Geek

jimmykochan said:


> steel metal studs of either 19 MIL (~ 0.019” 20 gauge EQ) or 23 MIL (~0.023” 30 gauge EQ)


Believe you may have those mixed up... smaller # "gauge" = thicker, and vice-versa. Also, 19mm 0.19" and likewise 23mm 0.23"

25.5mm = 1"


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## HT Geek

jimmykochan said:


> When I said voices, I meant regular tv & video game sounds topped with wild playing, screaming, stomping, fighting with each other, animal sound imitating, sugar-crazed bouncing off the walls kids “voices” with the all too often overly stressed yelling of adults thrown in for good measure J


Just adding that for the most part, those will be mid to high freqs. Easier to damp (absorb) or block.

To put that into real-world perspective for you, I suggest you focus on either "pink fluffy" (e.g. Owens-Corning fiberglass) or Roxul (e.g. AFB or Safe'n'Sound products) insulation in your walls. They do a bit better job versus other insulation materials relative to higher end freqs ("better" = ~10% or so).


----------



## jimmykochan

HT Geek said:


> You should be good with DD + GG. I suspect you'll be pleased with that on a double stud config. It's going to be good.
> 
> If I were you... I'd go with 20 gauge steel. Just sayin'.
> 
> 30-gauge is way too thin.




I meant 30 MIL EQD (equivalent) for the 0.023" stuff (which is 23mils, or thousands of an inch) thick.
i'm leaning towards the thinnest studs possible because the test data I've seen all say 24" o.c. and 25 gauge (the old real thickness stuff) better than 20 gauge. ~2-4 DB for both stud spacing and stud thickness (though they are were working with 3-5/" steel studs).


yeah, I'll use the iso-mat type stuff below the sill-plate and above the header-plate. i'm looking at the thermafiber (rock mineral wool) stuff; it would add ~$200 to project, i'll probably do it.


do you say no joist tape because it doesn't work or just not worth the time to put on & its' cost? if it works at all, i'm leaning towards using it because I only want to do this project ONCE.


----------



## The Salmon Mousse

*thin recessed lights and soundproofing*

I have a question about installing thin recessed lights in a 5/8 DD assembly. The lights my electrician recommended look something like this:









He seemed to think that installing these would be beneficial for soundproofing compared to regular recessed pot lights. From what I've been able to gather, regular lights require building a soundproof box around them. With these thin lights (they are about 1/2" thick), I would still have to cut a circular hole in the drywall to fit the light though. Is there some way to install them without cutting a hole all the way through the 2nd drywall layer (other than a small hole for the wiring)? Otherwise, I imagine I still have to build a (smaller) box above each light. If that's the case, I guess I'm just better off with a surface mounted product.


----------



## Waterboy77

The Salmon Mousse said:


> I have a question about installing thin recessed lights in a 5/8 DD assembly. The lights my electrician recommended look something like this:
> 
> He seemed to think that installing these would be beneficial for soundproofing compared to regular recessed pot lights. From what I've been able to gather, regular lights require building a soundproof box around them. With these thin lights (they are about 1/2" thick), I would still have to cut a circular hole in the drywall to fit the light though. Is there some way to install them without cutting a hole all the way through the 2nd drywall layer (other than a small hole for the wiring)? Otherwise, I imagine I still have to build a (smaller) box above each light. If that's the case, I guess I'm just better off with a surface mounted product.


You are still going to need a place for the ballast box to be mounted therefore needing a smaller box.
Even with a surface mounted produce you will have an electrical box that will penetrate the soundproofing, requiring something on the back side to aid in the sound leakage


----------



## kmhvball

The Salmon Mousse said:


> With these thin lights (they are about 1/2" thick), I would still have to cut a circular hole in the drywall to fit the light though. Is there some way to install them without cutting a hole all the way through the 2nd drywall layer (other than a small hole for the wiring)? Otherwise, I imagine I still have to build a (smaller) box above each light.


If there is a way to mount the junction box somewhere else & extend the wire, then I would think this could be helpful. In most jurisdictions, you need to be able to access the junction box.

My thought though, is that if you could do that, then potentially you could stub the wire through the drywall, but 'on top' of where you stub the drywall through, you could put 2 extra layers of drywall on top of it to provide the soundproofing you need for the 1/2" deep you cut out. So, essentially the 2 extra pieces of call it 12" x 12" drywall on top could be the 'sound proofing' drywall, and the 1-2 layers you cut out to recess the light into would then be 'okay' to do, since you added two extra layers above it. 

Obviously, 'how' to get these to stick into the drywall with out using the hinges would need to be figured out as well, but there is probably a way.

If you go back to post 427 and post 498, they show how I made super easy 'backer boxes', based on having a low profile LED light. They are a bit different, but should give you some idea...


----------



## Waterboy77

kmhvball said:


> If there is a way to mount the junction box somewhere else & extend the wire, then I would think this could be helpful. In most jurisdictions, you need to be able to access the junction box.
> 
> My thought though, is that if you could do that, then potentially you could stub the wire through the drywall, but 'on top' of where you stub the drywall through, you could put 2 extra layers of drywall on top of it to provide the soundproofing you need for the 1/2" deep you cut out. So, essentially the 2 extra pieces of call it 12" x 12" drywall on top could be the 'sound proofing' drywall, and the 1-2 layers you cut out to recess the light into would then be 'okay' to do, since you added two extra layers above it.
> 
> Obviously, 'how' to get these to stick into the drywall with out using the hinges would need to be figured out as well, but there is probably a way.
> 
> If you go back to post 427 and post 498, they show how I made super easy 'backer boxes', based on having a low profile LED light. They are a bit different, but should give you some idea...


Very good point on the location of ballasts, I use the 6' extension cable but you can get 20' with a max extention to 40' using 2


From Lotus lights website https://www.lotusledlights.com/recessed-lighting/6-inch/12w-super-thin
*"OPTIONS FOR LOCATING DRIVER:*

Fixture comes connected to the driver by 12″ long low voltage cable with waterproof connector in the middle. Depending on where you want the driver to be you have 2 options:


Locate next to the fixture – run line voltage wiring to first junction box and “daisy chain” to the junction boxes of the other fixtures.
Or install all drivers at one location and use low voltage extension cables to the fixtures. Use only extensions provided by the manufacturer. Available jumper cables are 6 feet (1.8m) and 20 feet (6m). Cables are linkable. Maximum run should not exceed 40 feet (12m)."


----------



## HT Geek

jimmykochan said:


> I meant 30 MIL EQD (equivalent) for the 0.023" stuff (which is 23mils, or thousands of an inch) thick.
> i'm leaning towards the thinnest studs possible because the test data I've seen all say 24" o.c. and 25 gauge (the old real thickness stuff) better than 20 gauge. ~2-4 DB for both stud spacing and stud thickness (though they are were working with 3-5/" steel studs).


Yes, agreed. My understanding is the current generally accepted approach is 25-gauge steel @ 24" O.C.



> yeah, I'll use the iso-mat type stuff below the sill-plate and above the header-plate. i'm looking at the thermafiber (rock mineral wool) stuff; it would add ~$200 to project, i'll probably do it.


There's no reason to spend more $ than necessary. I would suggest the sill plate foam - dirt cheap relatively speaking - and spend your $ on GG or something else.




> do you say no joist tape because it doesn't work or just not worth the time to put on & its' cost? if it works at all, i'm leaning towards using it because I only want to do this project ONCE.


The data I've seen show it to be either completely ineffective or 1 STC benefit (which is negligible).


----------



## The Salmon Mousse

kmhvball said:


> If you go back to post 427 and post 498, they show how I made super easy 'backer boxes', based on having a low profile LED light. They are a bit different, but should give you some idea...



Neat! So all I would need to do is add an extra drywall layer (or two) above the light and I should be able to mount the junction box elsewhere.

I'm guessing you were satisfied with the backer box setup you pictured in post #498?


----------



## Ladeback

I need a little advice. I am trying to soundproof my HT on a budget let alone build the room. I have most of the electronics except I would like a better projector then a 720i.

Right now I have built 2x4 stud walls for my home theater which is kind of a room inside a room, but did not decouple them and my wife is not wanting me to spend money on doing it or spend a lot of money on soundproofing. Funds are tight and I want to get the room built. We are not too worried about sound other then I would like to not hear the furnace in our basement run. She thinks just adding some pink insulation in the walls and ceiling should be enough. I know that isn’t the case but, I am thinking of doing that which will need to be done before all the drywall goes up and see how that sounds. I am planning on using clips and hat channel on the ceiling with DD and GG. I am also thinking of putting up DD and GG on the walls. 

From reading some old post on here and talking to friends who has finished a basement, I should put up the ceiling drywall first then the wall with acoustic caulk in between correct? I was hoping to put up the walls first, because I have a lot to do to the ceiling and that having walls would make it feel somewhat done.

As for lights I am going to put sconces on the side walls and 3 surface mounted LED lights that will just need outlet boxes and hopefully not backer boxes. I am going to prewire for Dolby Atmos so I will have to build boxes for those before putting up drywall.


Here is what I looking at putting on my ceiling for lights.
https://www.lowes.com/pd/Good-Earth...onze-LED-Ceiling-Flush-Mount-Light/1000002950


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## HT Geek

Ladeback said:


> I need a little advice. I am trying to soundproof my HT on a budget let alone build the room. I have most of the electronics except I would like a better projector then a 720i.
> 
> Right now I have built 2x4 stud walls for my home theater which is kind of a room inside a room, but did not decouple them


Could you expound on your comments above a bit? How are they not decoupled???

Are you saying you've built an independent set of wall studs inside your existing room? Is there an air gap between them and the original room's interior walls? Did you remove the drywall from the original room's walls and ceiling first?




> ... We are not too worried about sound other then I would like to not hear the furnace in our basement run. She thinks just adding some pink insulation in the walls and ceiling should be enough. I know that isn’t the case but, I am thinking of doing that which will need to be done before all the drywall goes up and see how that sounds.


That would help, but possibly not much. Depends on answers to my questions above, plus how loud is the furnace in your HT room currently?




> I am planning on using clips and hat channel on the ceiling with DD and GG. I am also thinking of putting up DD and GG on the walls.
> 
> From reading some old post on here and talking to friends who has finished a basement, I should put up the ceiling drywall first then the wall with acoustic caulk in between correct? I was hoping to put up the walls first, because I have a lot to do to the ceiling and that having walls would make it feel somewhat done.


You can do the walls first, however it's preferable to put up the ceiling first. Doing so allows the walls to help support the weight of the ceiling. You want to leave about a 1/4" gap between walls & floor and walls & ceiling and caulk the gaps. 

I understand the desire to want to make progress, and your desire to save $. On the money front, if sound dampening is a lesser priority (sounds like it is....), consider skipping the GG. If you bought the GG tubes and just used 1 tube per double-drywall sheet section, you're talking about $16 per sheet. Less per sheet with the buckets, but it's still a substantial investment for many folks.

BTW, I noticed you have 2 entry doors. You'll want to look at sound-proofing them a bit. Otherwise, don't bother with clips & channel as the sound will easily leak out of your existing doors. Unfortunately, the sound-proofing game sort of ends up being almost an 'all or nothing' type of endeavour. It's like a game of whack-a-mole where you're trying to whack the sound back into your room (or keep sound out of it).

Also, where do you intend to place your equipment rack and what type of rack will you be using?




> As for lights I am going to put sconces on the side walls and 3 surface mounted LED lights that will just need outlet boxes and hopefully not backer boxes. I am going to prewire for Dolby Atmos so I will have to build boxes for those before putting up drywall.


If they are in columns, you won't need backer boxes. If not, you should have backer boxes. Even with low-profile LED lights, there are still seams where sound will leak out. Placing the lights and speakers in columns may be an easier route that accomplishes the same thing.


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## Ladeback

HT Geek said:


> Could you expound on your comments above a bit? How are they not decoupled???
> 
> Are you saying you've built an independent set of wall studs inside your existing room? Is there an air gap between them and the original room's interior walls? Did you remove the drywall from the original room's walls and ceiling first?
> 
> Yes there is about a 5" air gap between the concrete foundation wall l with the screen on it, a 6'-8" wall between the north wall and foundation, about a 13' to 14' gap between the south wall and foundation, but I built the walls right up to under the floor joist and one beam. I forgot about using the IB-3 clips I think they are called. I don't want to go back and fix it.]
> 
> 
> That would help, but possibly not much. Depends on answers to my questions above, plus how loud is the furnace in your HT room currently?
> 
> My basement is unfinished so building anything is going to help with hearing the furnace I think. It is about 20 or so from the back wall of my HT and on the other side of the stairs.
> 
> 
> You can do the walls first, however it's preferable to put up the ceiling first. Doing so allows the walls to help support the weight of the ceiling. You want to leave about a 1/4" gap between walls & floor and walls & ceiling and caulk the gaps.
> 
> If there is a 1/4" gap I don't see how much it will actually support. I could build the ceiling first, just have to get other things done first before I do.
> 
> I understand the desire to want to make progress, and your desire to save $. On the money front, if sound dampening is a lesser priority (sounds like it is....), consider skipping the GG. If you bought the GG tubes and just used 1 tube per double-drywall sheet section, you're talking about $16 per sheet. Less per sheet with the buckets, but it's still a substantial investment for many folks.
> 
> I was thinking if I used it I would go with one tube or the equivalent of a bucket.
> 
> BTW, I noticed you have 2 entry doors. You'll want to look at sound-proofing them a bit. Otherwise, don't bother with clips & channel as the sound will easily leak out of your existing doors. Unfortunately, the sound-proofing game sort of ends up being almost an 'all or nothing' type of endeavour. It's like a game of whack-a-mole where you're trying to whack the sound back into your room (or keep sound out of it).
> 
> Well I the HT will be next to what will be a game room I hope at some point and I would like to have sliding barn doors opened when we are watching a football game. I guess if I am doing that then I souldn't worry about soundproofing at all maybe, just put in some insulation and be done with it. I had thought of putting in a side door to the north instead of the back, but I like the open concept more.
> 
> Also, where do you intend to place your equipment rack and what type of rack will you be using?
> 
> 
> The equipment will be in racks to the south and I will control them with a Logitech Harmony system until I can get a Control 4 system.
> 
> If they are in columns, you won't need backer boxes. If not, you should have backer boxes. Even with low-profile LED lights, there are still seams where sound will leak out. Placing the lights and speakers in columns may be an easier route that accomplishes the same thing.


I was thinking of building columns, but for now not. Guess I may be building backer boxes.


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## HT Geek

I looked at your diagram again.

Presuming you won't be using the shop area at the same time as the HT room, it seems to me your main concerns with noise will likely be the room to the rear (bar and game room) and rooms above. If you have double-doors in the HT room, you won't be able to seal them very well from sound escaping no matter what you do. You can still use heavy doors and seal around the perimeter to try and contain some of the sound leakage around the double door, but it sounds like that won't be a big priority for you anyway.

Personally, based on everything you've mentioned, I'd be inclined to focus on reducing sound transmission via the ceiling to isolate this room as much as possible from the floor above. It appears as if your basement is going to be a multi-use entertainment area. 

Ceiling/Wall order: the idea behind the small gap (1/4" or so) is to help with de-coupling and reducing transmission from one surface to another. The walls still help to hold up the ceiling, though you're right it's not quite as effective at that compared with traditional drywall hanging.


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## Ladeback

HT Geek said:


> I looked at your diagram again.
> 
> Presuming you won't be using the shop area at the same time as the HT room, it seems to me your main concerns with noise will likely be the room to the rear (bar and game room) and rooms above. If you have double-doors in the HT room, you won't be able to seal them very well from sound escaping no matter what you do. You can still use heavy doors and seal around the perimeter to try and contain some of the sound leakage around the double door, but it sounds like that won't be a big priority for you anyway.
> 
> Personally, based on everything you've mentioned, I'd be inclined to focus on reducing sound transmission via the ceiling to isolate this room as much as possible from the floor above. It appears as if your basement is going to be a multi-use entertainment area.
> 
> Ceiling/Wall order: the idea behind the small gap (1/4" or so) is to help with de-coupling and reducing transmission from one surface to another. The walls still help to hold up the ceiling, though you're right it's not quite as effective at that compared with traditional drywall hanging.


 @HT Geek, thanks for the help and was leaning to what you advice to do for the ceiling and yes the basement is going to be a multipurpose room eventually. 

As for the double door I could possibly change it to one big 4' door, like the idea of the sliding barn doors. My wife has not complained to much about the sound, but I haven't had the subs hooked up for some time now. I need to finish all me wiring in the walls and the ceiling then I can start getting the ceiling ready for sheet rock. Using clips and hat channel will help drop the ceiling enough to get below some other cat 6 wire to another part of the house that runs along a beam in my HT.

I am the one that would be using the shop/office mostly then anyone else so it shouldn't be a problem. This has been a slow process, mostly because of the cost of soundproofing and trying to find time to work on it. Family and life kind of get in the way.


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## HT Geek

Ladeback said:


> This has been a slow process, mostly because of the cost of soundproofing and trying to find time to work on it. Family and life kind of get in the way.


You're not alone in that regard! I started on my "project" just over a year ago when my son was battling a serious illness which at that time was not diagnosed. I always wanted to have a "true" HT room, and I needed an outlet from the stress of life at the time. Demo'ing my old media room was a great outlet! However, having kids, etc. has meant this has been a slow process for me overall. So far, I've done all the work myself. Still, I wouldn't change any of that if I were to do it over.


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## HT Geek

Ladeback said:


> As for the double door I could possibly change it to one big 4' door, like the idea of the sliding barn doors.


I hope that would be the width and not the height! 

Sliding barn door... not recommended as it will rattle unless you go to great lengths to ensure it's not possible for it to rattle... at which point you may find opening and closing it is challenging (i.e. it won't slide easily). And it will leak sound like a sieve. Sliding doors are very much at odds with good acoustics.


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## healthnut

I spent the last 8 months soundproofing my room. I put a 3/4 inch layer of MDF board on the ceiling, green glue, a second layer of 5/8 drywall over that, hat channel, isolation clips, a double layer of SafeNSound, followed by 2 layers of 5/8 drywall and green glue. I also did the walls with double 5/8, green glue, channel, clips and as much sand sound as I could stuff in. I didn't expect to completely eliminate bass leakage into the kitchen upstairs, but I was quite surprised how little good it did. It may have cut it 50%. This was both a disappointing and unexpected result. 


Sent from my iPhone using Tapatalk


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## whumpf

HT Geek said:


> Sliding barn door... not recommended as it will rattle unless you go to great lengths to ensure it's not possible for it to rattle... at which point you may find opening and closing it is challenging (i.e. it won't slide easily). And it will leak sound like a sieve. Sliding doors are very much at odds with good acoustics.


I just finished a media/game room with the two sections sections separated not by barn doors, but by something even worse in the acoustical community - double pocket doors! (I actually wanted barn doors but didn't have the wall space). In the game room we have a bar with an ice maker, a drink cooler and a wine frig. Between the three, especially the ice maker, they make a fair amount of noise, which is very noticeable in the media room. Closing the pocket doors mutes the sound very effectively. Is it perfect? No, but it mutes the noise substantially and makes movies, or even conversation, more pleasant. 

As for rattling, we haven't watched a lot yet, and I don't have the subs dialed in, but we have watched all three Lord of the Rings movies and haven't noticed rattling, even during Helm's Deep and other bass heavy scenes. I wasn't playing at reference levels, and doubt I ever will, but it was loud enough to feel.


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## HT Geek

healthnut said:


> I spent the last 8 months soundproofing my room. I put a 3/4 inch layer of MDF board on the ceiling, green glue, a second layer of 5/8 drywall over that, hat channel, isolation clips, a double layer of SafeNSound, followed by 2 layers of 5/8 drywall and green glue. I also did the walls with double 5/8, green glue, channel, clips and as much sand sound as I could stuff in. I didn't expect to completely eliminate bass leakage into the kitchen upstairs, but I was quite surprised how little good it did. It may have cut it 50%. This was both a disappointing and unexpected result.
> 
> 
> Sent from my iPhone using Tapatalk


Holy crap Batman! That's a lot of effort that you went to.

Unfortunate that you didn't attain the effect you were striving for. Is the order you listed the parts above the same order as your layering? IOW, did you secure your MDF on the ceiling to existing floor joists above, then GG, 5/8 DW, etc.? Or did your MDF get attached to an original DW ceiling, etc.? 

Your best bet is to think of your HT room as a box, where you want that box completely physically disconnected from the structure of the home as much as possible (and within reason), and then dampen the crud out of it (again within reason).

What is "sand sound?" Did you mean Safe'n'Sound?

And what thickness of S&S did you use? Standard R11 (3") or R13 (3.5")?

Did you gut the room down to the studs prior to the ceiling/wall work you did? 

Do you have a build thread with more details?


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## healthnut

HT Geek said:


> Holy crap Batman! That's a lot of effort that you went to.
> 
> 
> 
> Unfortunate that you didn't attain the effect you were striving for. Is the order you listed the parts above the same order as your layering? IOW, did you secure your MDF on the ceiling to existing floor joists above, then GG, 5/8 DW, etc.? Or did your MDF get attached to an original DW ceiling, etc.?
> 
> 
> 
> Your best bet is to think of your HT room as a box, where you want that box completely physically disconnected from the structure of the home as much as possible (and within reason), and then dampen the crud out of it (again within reason).
> 
> 
> 
> What is "sand sound?" Did you mean Safe'n'Sound?
> 
> 
> 
> And what thickness of S&S did you use? Standard R11 (3") or R13 (3.5")?
> 
> 
> 
> Did you gut the room down to the studs prior to the ceiling/wall work you did?
> 
> 
> 
> Do you have a build thread with more details?




Hi, I appreciate your sympathies! I did this by the book. The 3/4 MDF was screwed into the floor joists, then a layer of green glue, then a layer of 5/8 drywall. Then SafNSound (not sand sound, typo, Don't remember the thickness, but it was at least 3" if not more, and I layered in as much as I could fit in there), then secured hat channel to the ceiling with isolation clips (spaced 24" when possible), then the 2 layers of 5/8 drywall with green glue between. I also build hush boxes for the recessed lighting and special acoustic putty for the switches and outlets. I rebuilt all the side walls also, with clips and channel and double 5/8 drywall. I wasn't expecting to entirety eliminate the low bass infiltration, but I did have higher expectations than what I ended up with. I did tear down the old walls to the studs before commencing.
I didn't do a builder thread (seems like extra work, and this was labor intensive as it was). I should have taken some SPL measurements before and and after so I could quantify the improvement, but it's not as good as I had hoped.




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## HT Geek

That's a bummer.

Have you considered experimenting with corner bass traps and/or sound absorption for LFE on the walls and ceiling?

Are your subs isolated in any way from the stage?

I'm just fishing for ideas that might help at this stage.

I hear ya on the build thread. I've had my phone and 2 digital cameras break in the process, so that slowed down my build-reporting quite a bit (kinda sucks to not include pics).


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## bombertodd

@healthnut do you have pictures of the assembly. Low frequency isolation is difficult to achieve. Look at all the graphs for transmission loss, to me they all seem pretty weak under 80hz.

I'm currently building my room and I'm wondering to what extent I should try to isolate my room.


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## healthnut

HT Geek said:


> That's a bummer.
> 
> 
> 
> Have you considered experimenting with corner bass traps and/or sound absorption for LFE on the walls and ceiling?
> 
> 
> 
> Are your subs isolated in any way from the stage?
> 
> 
> 
> I'm just fishing for ideas that might help at this stage.
> 
> 
> 
> I hear ya on the build thread. I've had my phone and 2 digital cameras break in the process, so that slowed down my build-reporting quite a bit (kinda sucks to not include pics).




Thanks. I do have bass traps in all 4 corners (though they're short of ceiling height with the increase in ceiling height). I also have 6 GIK first reflection panels on the sidewalls. My sub has the best response in the front left corner, and it's a monster, can't really put it anywhere but in or near a corner (it's a Mariana Deep Sea Sound 24"). I've added Crowson Tactile Transducers to the seating and 3 MBM's behind it to get bass impact without shaking the house down. All have helped, but the Mariana still shakes up the kitchen above the theater room pretty extensively.


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## healthnut

bombertodd said:


> @healthnut do you have pictures of the assembly. Low frequency isolation is difficult to achieve. Look at all the graphs for transmission loss, to me they all seem pretty weak under 80hz.
> 
> 
> 
> I'm currently building my room and I'm wondering to what extent I should try to isolate my room.




If you have significant output under 40hz, I don't think you can do much to keep it out of adjoining rooms, at least I couldn't, and I tried very hard to do it properly.










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## bharv2221

*Basement Insulation Question*

I'm new to this forum so I need some expert advice.

I just bought my home recently and I am starting my HT. When I bought the home, the basement was framed, insulated, and the electrical was run. My home is in Wisconsin so insulation is especially important for temperature reasons as well. So just keep that in mind with this.

The exterior cement block walls where all insulated with the rigid pink foam insulation. Then there is about a 3"-4" air gap between that foam and the wall framing studs. Each exterior wall frame was then insulated with your normal r-19 fiberglass insulation. The room which will be my HT will have two exterior walls, one wall is about 18" long and the other is about 13", and again they are insulated as mentioned before.

My goal at the end of this is to have a sound dampened HT. I intend to use many of the techniques which we are all familiar with (safe n sound, res channels, green glue, double drywall, etc.). I'm not looking to make a music studio but I do want to control my noise from the theater and the floor above.

So here are my questions:

1) Is it going to be necessary to remove the existing fiberglass insulation on those two walls and replace it with acoustic insulation?

2) Does an exterior wall have more, less, or the same amount of noise transfer as interior walls?

3) Since those are exterior walls, is safe n sound going to provide the thermal protection I need? If not what would you suggest doing here?


I hope to hear from you guys! Any feedback or ideas help!


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## kmhvball

bharv2221 said:


> I'm new to this forum so I need some expert advice.
> 
> I just bought my home recently and I am starting my HT. When I bought the home, the basement was framed, insulated, and the electrical was run. My home is in Wisconsin so insulation is especially important for temperature reasons as well. So just keep that in mind with this.
> 
> The exterior cement block walls where all insulated with the rigid pink foam insulation. Then there is about a 3"-4" air gap between that foam and the wall framing studs. Each exterior wall frame was then insulated with your normal r-19 fiberglass insulation. The room which will be my HT will have two exterior walls, one wall is about 18" long and the other is about 13", and again they are insulated as mentioned before.
> 
> My goal at the end of this is to have a sound dampened HT. I intend to use many of the techniques which we are all familiar with (safe n sound, res channels, green glue, double drywall, etc.). I'm not looking to make a music studio but I do want to control my noise from the theater and the floor above.
> 
> So here are my questions:
> 
> 1) Is it going to be necessary to remove the existing fiberglass insulation on those two walls and replace it with acoustic insulation?
> 
> 2) Does an exterior wall have more, less, or the same amount of noise transfer as interior walls?
> 
> 3) Since those are exterior walls, is safe n sound going to provide the thermal protection I need? If not what would you suggest doing here?
> 
> I hope to hear from you guys! Any feedback or ideas help!


Everything I have seen, suggests typical 'pink fluffy'/ R-19 is just as effective as more expensive options (e.g., safe 'n sound) at sound reduction. Net, I would definitely not suggest replacing what is there, and frankly, I would suggest for the new walls - to use the standard pink fluffy as well.

I am not clear on the exterior wall lay-out/ question... it sounds to me, like you'll have a wall close to, but parallel to the exterior wall, in which case, then that 'inside' stud wall, is decoupled from the exterior wall. If that is the case, then you don't need to do any clips & channel on that interior wall (but still want double dyrwall/ green glue, pink fluffy insulation, and ideally IB-3 clips at the top of the wall to decouple), and you aren't doing anything to the exterior wall. I may not be understanding the set up the right way though.

Just a comment on your "Resilient Channel"... that is typically viewed as a lower quality/ less effective and more prone for 'error' solution, than "Clips & Hat Channel". The IB-1 clips can be purchased for fairly low cost relative to other clips, and are still quite effective. If executed correctly, the Single Leg resilient channel (normally for walls) is decent, but still not as good. If you need the 'double leg' (usually on ceilings) , you get even worse performance.


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## bharv2221

kmhvball said:


> Everything I have seen, suggests typical 'pink fluffy'/ R-19 is just as effective as more expensive options (e.g., safe 'n sound) at sound reduction. Net, I would definitely not suggest replacing what is there, and frankly, I would suggest for the new walls - to use the standard pink fluffy as well.
> 
> I am not clear on the exterior wall lay-out/ question... it sounds to me, like you'll have a wall close to, but parallel to the exterior wall, in which case, then that 'inside' stud wall, is decoupled from the exterior wall. If that is the case, then you don't need to do any clips & channel on that interior wall (but still want double dyrwall/ green glue, pink fluffy insulation, and ideally IB-3 clips at the top of the wall to decouple), and you aren't doing anything to the exterior wall. I may not be understanding the set up the right way though.
> 
> Just a comment on your "Resilient Channel"... that is typically viewed as a lower quality/ less effective and more prone for 'error' solution, than "Clips & Hat Channel". The IB-1 clips can be purchased for fairly low cost relative to other clips, and are still quite effective. If executed correctly, the Single Leg resilient channel (normally for walls) is decent, but still not as good. If you need the 'double leg' (usually on ceilings) , you get even worse performance.


You're right about my exterior walls. They are parallel and separated from the exterior block walls. However, the stud walls are nailed directly to the floor joists above. Therefore I can't use the IB-3 clips.

So is my best solution on those walls to use the clips and hat channel again? My gut is telling me to just do DD + GG and screw it directly to the studs. But idk if that is hurting me more in the long run. Otherwise, would the resilient channel be more effective? Even if its not as good as hat channel? 

Any thoughts?


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## kmhvball

bharv2221 said:


> You're right about my exterior walls. They are parallel and separated from the exterior block walls. However, the stud walls are nailed directly to the floor joists above. Therefore I can't use the IB-3 clips.
> 
> So is my best solution on those walls to use the clips and hat channel again? My gut is telling me to just do DD + GG and screw it directly to the studs. But idk if that is hurting me more in the long run. Otherwise, would the resilient channel be more effective? Even if its not as good as hat channel?
> 
> Any thoughts?


Having the vertical walls touching the floor joist is not 'best case', and frankly, I don't know how much worse it is... but, my 'gut' would say the same as yours, i.e., stick with DD + GG and skip the resilient channel on those walls. I personally would likely take a saw-zall, and 'notch' out where the walls touch the floor joist at some locations, basically leaving a 'touch point', every 4' still in tact. So, basically cut a 1/4" or 1/2" pieces of the horizontal top plate out where it is touching the wall... better yet, if the horizontal top plate doesn't touch the floor joist, but just the 'long nail', then simply cutting the long nail would do the trick. If that is the case, that the top plate isn't wedged against the floor joist, I would be even more inclined to NOT do clips & channel.

Resilient channel is certainly better than nothing. If done appropriately, it is fairly effective, particularly on walls if using single leg resilient channel. The 'issue', as I understand it, is that many times a drywall contractor will screw through the drywall, into the resilient channel, and then into the stud - which, effectively 'couples' again. I believe resilient channel is supposed to have a screw attaching the resilient channel to the stud (for single leg, two screws for double leg), but then drywall is only screwed from drywall into resilient channel itself, NOT the stud. The way 'clips & channel' works, is a few things.. one it is normally 'deeper', so, a standard 1 1/4" screw wouldn't to through drywall, channel, and into stud. Also, where the 'clips' are, if a screw happens to be screwed in, it will not go into the stud since the clips are steel. When I was planning my room, I asked about if I had to 'save money', would it be better to go with a little less Green Glue, and use the fancier clips or go with the cheaper Clips, and use the optimal green glue, and was told to go with the optimal green glue and use the cheaper clips (by Ted, at the SOundproofingcompany).


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## NickMach007

I have a newbie type question. I have been reading this thread (and many others) as well as frequenting some other popular resources. I tried searching around, and couldn't find it, but I'm sure this question has already been asked before. So, if there is already info out there, I'd love just for someone just to point me in the right way. I am going to be renovating my upstairs and am planning to use some of the standard design principles to help reduce noises between rooms (clips and channels, DD+GG, mineral wool insulation, etc). I have a simple question though, what about trim? Mainly baseboards. Seems that if I nail the baseboards through the drywall into the studs I am undoing some of the decoupling work I will trying to accomplish with clips and channels. The only info I found is to make sure the baseboards only touch the wall (leave a gap along the floor and seal with acoustical caulk). I'm not sure how well just applying something like a construction adhesive (i.e. liquid nails) would hold up over time, but that may be an option. Or I could get creative and figure out how to attach the baseboard just to the drywall and not the studs. 
Is there a simple fix, or am I overthinking this? Thanks!


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## bharv2221

NickMach007 said:


> I have a newbie type question. I have been reading this thread (and many others) as well as frequenting some other popular resources. I tried searching around, and couldn't find it, but I'm sure this question has already been asked before. So, if there is already info out there, I'd love just for someone just to point me in the right way. I am going to be renovating my upstairs and am planning to use some of the standard design principles to help reduce noises between rooms (clips and channels, DD+GG, mineral wool insulation, etc). I have a simple question though, what about trim? Mainly baseboards. Seems that if I nail the baseboards through the drywall into the studs I am undoing some of the decoupling work I will trying to accomplish with clips and channels. The only info I found is to make sure the baseboards only touch the wall (leave a gap along the floor and seal with acoustical caulk). I'm not sure how well just applying something like a construction adhesive (i.e. liquid nails) would hold up over time, but that may be an option. Or I could get creative and figure out how to attach the baseboard just to the drywall and not the studs.
> Is there a simple fix, or am I overthinking this? Thanks!


Good Question! I need that answer too!


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## kmhvball

In my room, I did my first layer of "Drywall", actually using OSB. So, although, I didn't actually do Trim (I did Fabric Frames everywhere)... if I had, I could have simply nailed the trim into the drywall & OSB, NOT into where studs are. I am sure others likely have better feedback, but this is one option to consider.


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## NickMach007

*Trim / baseboards for decoupled walls*



kmhvball said:


> In my room, I did my first layer of "Drywall", actually using OSB. So, although, I didn't actually do Trim (I did Fabric Frames everywhere)... if I had, I could have simply nailed the trim into the drywall & OSB, NOT into where studs are. I am sure others likely have better feedback, but this is one option to consider.


Thanks for the feedback. That is definitely an option. I look forward to hearing from others' experiences as well. Cheers.


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## HT Geek

kmhvball said:


> In my room, I did my first layer of "Drywall", actually using OSB. So, although, I didn't actually do Trim (I did Fabric Frames everywhere)... if I had, I could have simply nailed the trim into the drywall & OSB, NOT into where studs are. I am sure others likely have better feedback, but this is one option to consider.


Ditto. However, I'd not likely do it again when I get to HT v2.0 - whenever that happens. It wasn't a big deal on the walls but was a big pain to put it on the ceiling. At least in my room.


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## HT Geek

*Lead: Ultimate SP Material?*

Stumbled upon some interesting data while learning about lead-lined drywall (likely the ultimate sound-proofing material... at EXTREME cost).

I'm fascinated by their claims of lead vs. aluminum, steel, and concrete. Of course, at ~$80/sq. ft. for 1/2" thick lead sheets, it better be good! Not to mention the weight at ~32 lbs./sq. ft. When I win the lottery and build a bunker, I may decide to make the HT room walls out of 1/2" thick lead. Lol.

Reference to table below: Lead Soundproofing for Noise Reduction


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## Livin

HT Geek said:


> Ditto. However, I'd not likely do it again when I get to HT v2.0 - whenever that happens. It wasn't a big deal on the walls but was a big pain to put it on the ceiling. At least in my room.


Wonder how 1/2" osb affects sound (reflectivity & absorption) vs using 1/2 or 5/8 drywall? 

Given osb cost, I'm considering it on walls, not ceiling. 

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## HT Geek

Livin said:


> Wonder how 1/2" osb affects sound (reflectivity & absorption) vs using 1/2 or 5/8 drywall?
> 
> Given osb cost, I'm considering it on walls, not ceiling.


I'll say it is great on the walls from the standpoint of sticking a nail or screw anywhere. For me, cost was about 20% more than DW, so not a big deal (I used 5/8").

My recollection is the absorption is about the same as drywall, with a different resonant freq. Mass is close to drywall (.1 - .3 lb/sq ft less).


----------



## Livin

HT Geek said:


> Stumbled upon some interesting data while learning about lead-lined drywall (likely the ultimate sound-proofing material... at EXTREME cost).
> 
> I'm fascinated by their claims of lead vs. aluminum, steel, and concrete. Of course, at ~$80/sq. ft. for 1/2" thick lead sheets, it better be good! Not to mention the weight at ~32 lbs./sq. ft. When I win the lottery and build a bunker, I may decide to make the HT room walls out of 1/2" thick lead. Lol.
> 
> Reference to table below: Lead Soundproofing for Noise Reduction


I'm thinking you just build a room that is a concrete box, framed out with 3/4" plywood walls and fill the gap between the plywood and concrete with sand. Totally sound proof and way less cost than lead


HT Geek said:


> Ditto. However, I'd not likely do it again when I get to HT v2.0 - whenever that happens. It wasn't a big deal on the walls but was a big pain to put it on the ceiling. At least in my room.



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## kmhvball

HT Geek said:


> Ditto. However, I'd not likely do it again when I get to HT v2.0 - whenever that happens. It wasn't a big deal on the walls but was a big pain to put it on the ceiling. At least in my room.


Interesting... I only did the walls, but have thought in hind-sight, I would do the ceiling if I get to HT v 2.0 ever... What about the ceiling made it difficult?


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## NickMach007

Any other thoughts on attaching trim while still wanting to maintain decoupled walls? I'd rather just use 2 layers of drywall, but osb certainly is an options. 

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## HT Geek

kmhvball said:


> Interesting... I only did the walls, but have thought in hind-sight, I would do the ceiling if I get to HT v 2.0 ever... What about the ceiling made it difficult?


I'd say it really stems from an error in judgement on my part. I started with OSB on the ceiling as the very first layer. My HT room is on the 2nd floor with a rather large attic above it and the room is on a corner of the house. So, I decided to forgo clips & hat channel for the ceiling. The walls were double-stud (room-within-a-room), but I didn't have enough ceiling height in the room to do an independent joist ceiling.

My 'error in judgement' per se relates to how I started spanning the ceiling joists with the OSB. I ended up with a few pieces of odd sizes and some areas where the sheets didn't quite meet up with the joists. I eventually figured out these hanging joints of OSB sheets needed some reinforcement, so I used 2x4 scrap to screw either sheet into. 

I found that when I put up the subsequent drywall layer over the OSB, the DW sheets seemed much easier to keep straight, easier to trim, etc. Overall easier to work with.

I actually put 2 layers of DW on the ceiling, for 1x OSB + 2x DW (GG in between all layers). I was not happy with the quality of my work with the 1st layer of DW, which is why I put a 2nd layer up. All 3 layers were staggered in order of placement with the walls (i.e. ceiling / walls / ceiling / walls / ceiling).

Bottom line is I found the drywall easier to work with - generally speaking. It's just my personal experience.

If I could do my room over again, I would put clips & channel on the ceiling only, and then do the double-wall studs. I might consider OSB but would likely skip putting it on the ceiling. I can also tell you DW just seemed more rigid to me on the drywall lift vs. the OSB, FWIW.


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## patrio

I'm looking to keep noise from coming into my basement via the door. I need a door seal badly, since the solid core door doesn't do anything on its own. 

Is there a way to go about soundproofing the bottom and jambs without spending $300+? The Zero door seals are just out of my budget.


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## HT Geek

patrio said:


> Is there a way to go about soundproofing the bottom and jambs without spending $300+? The Zero door seals are just out of my budget.


Consider a hybrid approach. Purchase a Zero automatic door bottom and get the thickest rubber seals you can find for the stops from a local hardware store, Amazon, etc. Look for exterior door stop seals. 

If even the Zero auto door bottom is outside your budget, you could use an exterior door sweep. It's the only other option I can think of for a sealed door bottom. But it's not a good option IMHO as it introduces significant risks. Based on the drawbacks (see below), you may decided to forego using a bottom gasket altogether. If that is the case, a 3rd option is to get your door bottom as close to the floor surface as you can without impeding the free movement of the door. If both sides of the door are carpeted, as long as it's not shag or tall carpet this will help a bit. Most importantly you don't want a big gap on the bottom, or you might as well not bother with any seals.

What finished floor surface is on either side of your door?

Is your subfloor wood or concrete, or something else?

*Exterior Door Thresholds*
Exterior doors have a raised threshold. We are all used to stepping slightly up and over an exterior door threshold when entering or exiting a home. This design prevents drafts coming into your home when the door is closed. Of course, that's not ideal in an interior doorway because people are not used to having to step over a 1"+ lip in an interior doorway and it would be a tripping hazard. When you open an exterior door inward, the sweep clears the interior finished floor thanks to the added height of the exterior door threshold.

Using exterior door sweeps on an interior door will have significant drawbacks. Even if you were to mount one flush with the floor, it would make your door more difficult to push/pull open and shut. To avoid that problem and still seal the bottom of the door, you would need to raise the exterior door threshold, as if it were installed at an exterior egress point. However, inside a home that would be a trip hazard and therefore I recommend against it.

There is one exception that I've observed in a few homes: if you have a transition between two different floor surfaces (e.g. hardwood to tile) at an interior doorway. However, most modern homes do not have a threshold there because again it's a tripping hazard. If you are in this situation, you could consider this approach but I would not recommend it and you'd still need a short height transition (e.g. 1/4" or less). For example, I've seen this is at the bottom of a set of stairs, where there was a door at the bottom and also a change in the finished floor type in the same location.


*Interior Door Transitions*
If you use a gasket of some sort on the door bottom (e.g. auto door bottom or door sweep), get a solid wood threshold that is the same height as your carpet on either side of it (typically about 3/4" with the pad, but can vary a bit). This gives the gasket something to press onto and block sound transmission. Again, you don't want something sticking up from the floor that guests and family members might trip over, so measure your finished floor height if you can prior to purchasing the threshold.

If you have a carpet-to-carpet transition (most common scenario) under your HT room door with no threshold, a door sweep will make the door more difficult to open and close, and the process of opening and closing the door will strain the mechanism securing the door sweep to the door. 

Door sweeps can be installed on the inside of the door or mortised into the door, just like Zero's automatic door bottom. In many cases they are simply tacked on underneath the door bottom, but in this case that probably wouldn't work well.


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## patrio

HT Geek said:


> Consider a hybrid approach. Purchase a Zero automatic door bottom and get the thickest rubber seals you can find for the stops from a local hardware store, Amazon, etc. Look for exterior door stop seals.
> 
> If even the Zero auto door bottom is outside your budget, you could use an exterior door sweep. It's the only other option I can think of for a sealed door bottom. But it's not a good option IMHO as it introduces significant risks. Based on the drawbacks (see below), you may decided to forego using a bottom gasket altogether. If that is the case, a 3rd option is to get your door bottom as close to the floor surface as you can without impeding the free movement of the door. If both sides of the door are carpeted, as long as it's not shag or tall carpet this will help a bit. Most importantly you don't want a big gap on the bottom, or you might as well not bother with any seals.
> 
> What finished floor surface is on either side of your door?
> 
> Is your subfloor wood or concrete, or something else?
> 
> *Exterior Door Thresholds*
> Exterior doors have a raised threshold. We are all used to stepping slightly up and over an exterior door threshold when entering or exiting a home. This design prevents drafts coming into your home when the door is closed. Of course, that's not ideal in an interior doorway because people are not used to having to step over a 1"+ lip in an interior doorway and it would be a tripping hazard. When you open an exterior door inward, the sweep clears the interior finished floor thanks to the added height of the exterior door threshold.
> 
> Using exterior door sweeps on an interior door will have significant drawbacks. Even if you were to mount one flush with the floor, it would make your door more difficult to push/pull open and shut. To avoid that problem and still seal the bottom of the door, you would need to raise the exterior door threshold, as if it were installed at an exterior egress point. However, inside a home that would be a trip hazard and therefore I recommend against it.
> 
> There is one exception that I've observed in a few homes: if you have a transition between two different floor surfaces (e.g. hardwood to tile) at an interior doorway. However, most modern homes do not have a threshold there because again it's a tripping hazard. If you are in this situation, you could consider this approach but I would not recommend it and you'd still need a short height transition (e.g. 1/4" or less). For example, I've seen this is at the bottom of a set of stairs, where there was a door at the bottom and also a change in the finished floor type in the same location.
> 
> 
> *Interior Door Transitions*
> If you use a gasket of some sort on the door bottom (e.g. auto door bottom or door sweep), get a solid wood threshold that is the same height as your carpet on either side of it (typically about 3/4" with the pad, but can vary a bit). This gives the gasket something to press onto and block sound transmission. Again, you don't want something sticking up from the floor that guests and family members might trip over, so measure your finished floor height if you can prior to purchasing the threshold.
> 
> If you have a carpet-to-carpet transition (most common scenario) under your HT room door with no threshold, a door sweep will make the door more difficult to open and close, and the process of opening and closing the door will strain the mechanism securing the door sweep to the door.
> 
> Door sweeps can be installed on the inside of the door or mortised into the door, just like Zero's automatic door bottom. In many cases they are simply tacked on underneath the door bottom, but in this case that probably wouldn't work well.


Thanks, I really appreciate it. I just realized that Zero's automatic door bottom is only around $87 and it's actually the jamb/stop set that gets pricey. I'll likely end up going with as you suggested. Would this approach still provide a notable improvement, you think? It's not really home theater related, rather this is for a basement apartment I'm renovating & renting out, and I can't imagine a stranger would be happy renting a place with as much sound leaking through that door as there is right now. 

I'm just unsure what qualifies as thick for door stops. Would something like this work?

https://www.amazon.com/M-D-Building-Products-43305-42-Inch/dp/B008XGR6J6

Or this..

https://www.amazon.com/M-D-Building...qid=1483670412&sr=8-7&keywords=door+jamb+seal


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## HT Geek

patrio said:


> Thanks, I really appreciate it. I just realized that Zero's automatic door bottom is only around $87 and it's actually the jamb/stop set that gets pricey. I'll likely end up going with as you suggested. Would this approach still provide a notable improvement, you think?


Yes. Anything you can do to minimize gaps will help.

The door bottom is going to be your biggest win. There's typically a pretty good sized gap under most interior doors. That's especially true if the finished floor is not carpet.

Here's what is good about Zero's door stops: 
- Neoprene, not rubber
- Round shape that is compressed when pressure is applied (i.e. door closed)




> It's not really home theater related, rather this is for a basement apartment I'm renovating & renting out, and I can't imagine a stranger would be happy renting a place with as much sound leaking through that door as there is right now.
> 
> I'm just unsure what qualifies as thick for door stops. Would something like this work?
> 
> https://www.amazon.com/M-D-Building-Products-43305-42-Inch/dp/B008XGR6J6


That ^ looks pretty decent. Based on the info, it seems like it would be a good fit for your needs. I like the fact there is metal (aluminum) reinforcing the vinyl. OTOH, it uses vinyl. Probably not a big deal presuming this is an interior door. It's going to be much better than without it either way.




> Or this..
> 
> https://www.amazon.com/M-D-Building...qid=1483670412&sr=8-7&keywords=door+jamb+seal


Not that one ^. It's kerfed. You will be putting these on flat surfaces (door jambs).

Also, I wouldn't use ones like below that you will find at big box stores. My personal experience is they are like memory foam. Over time, they will get crushed and stay that way, defeating the purpose. At least that is what I've found on solid wood doors that have a tight fit against them.


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## ncabw

Quick question I have a lot of the Roxul Comfortbatt left over from jobs before. Can I use this instead of the Safe n sound? Either in my ceiling or walls? My walls are decoupled from the foundation so maybe I could use it there? And do safe n sound in the joists. Hopefully I can use it everywhere save me some money😊😊😊😊


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## Ladeback

ncabw said:


> Quick question I have a lot of the Roxul Comfortbatt left over from jobs before. Can I use this instead of the Safe n sound? Either in my ceiling or walls? My walls are decoupled from the foundation so maybe I could use it there? And do safe n sound in the joists. Hopefully I can use it everywhere save me some money😊😊😊😊


I don't know why not, they both are supposed to absorb sound. I believe the Comfortbatt is used on the exterior walls and attics. You should be fine and it would save on buying other insulation. 

Here is Roxul's website with an explanation of the two.

http://www.roxul.com/products/residential/products/roxul+comfortbatt


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## NickMach007

Is it normal to have to wait over a week to get a response to an email from the sound proofing company? I'm trying to get an estimate for some supplies and it has been over a week since I've heard anything. I assumed they'd be eager to take my money, but maybe holidays put them behind. Anyone have experience working with them?

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## HT Geek

NickMach007 said:


> Is it normal to have to wait over a week to get a response to an email from the sound proofing company?


No



> I'm trying to get an estimate for some supplies and it has been over a week since I've heard anything. I assumed they'd be eager to take my money, but maybe holidays put them behind. Anyone have experience working with them?


Well, let's see... today is January 6, so a week ago was..... Hmmm.

I understand your enthusiasm, but I'd cut them a little slack until next week. You're also prolly better off calling.


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## HT Geek

ncabw said:


> Quick question I have a lot of the Roxul Comfortbatt left over from jobs before. Can I use this instead of the Safe n sound? Either in my ceiling or walls? My walls are decoupled from the foundation so maybe I could use it there? And do safe n sound in the joists. Hopefully I can use it everywhere save me some money😊😊😊😊


I've done quite a bit of research on various materials' sound absorption characteristics and I've never been able to locate data on Comfort Batt. My suspicion, FWIW: there's very little difference between the two. 

Safe'n'Sound is slightly more dense (less than 0.5 psf). Comfort Batt is thicker (3-1/2" vs. 3"). ComfortBatt ought to theoretically be a bit better from a depth perspective, and Safe'n'Sound is theoretically a bit better from a mass perspective. Who knows. I say call it a wash. I suspect you'll get similar results from either. 

Go for it and save some $ you can spend elsewhere on something more fun.


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## NickMach007

HT Geek said:


> No
> 
> 
> 
> Well, let's see... today is January 6, so a week ago was..... Hmmm.
> 
> I understand your enthusiasm, but I'd cut them a little slack until next week. You're also prolly better off calling.


Well the first email was actually 2 weeks ago, but again I realize the holidays. I'll give them until mid week, then I'll try calling. Thanks!

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## ncabw

HT Geek said:


> I've done quite a bit of research on various materials' sound absorption characteristics and I've never been able to locate data on Comfort Batt. My suspicion, FWIW: there's very little difference between the two.
> 
> Safe'n'Sound is slightly more dense (less than 0.5 psf). Comfort Batt is thicker (3-1/2" vs. 3"). ComfortBatt ought to theoretically be a bit better from a depth perspective, and Safe'n'Sound is theoretically a bit better from a mass perspective. Who knows. I say call it a wash. I suspect you'll get similar results from either.
> 
> Go for it and save some $ you can spend elsewhere on something more fun.


Thanks for the responses I will just use up the extra insulation I have then. Think I have about 20 full bags so definitely helps with the cost.

Here is what I've done for soundproofing hope it's going to be decent 

1)between the joist I went GG DW GG DW and then will add the insulation 
2)ceiling will be DD & GG. I used the clips and furring channel to decouple from the ceiling
3) walls will be DD & GG. All four walls are now being built off(not touching)the foundation. I also will be using clips and furring channel on all wallls. Not sure if I need 2 since I already built the walls off the concrete foundation. Top plate I'm also using those IB-3 clips to decouple that from the ceiling. Under the bottom plate I added some rubber. 
4) when I do the DW I will be leaving a 1/4" between all walls and using the GG sealant 
5) in all walls I will be adding the roxul insulation just for sound absorption sine I already have my R rating with the sparky foam on the concrete foundation 


Anything else I should be thinking about?

Next is lights. Someone mentioned there might be some puck lights that would just fit into the bottom DD and then to connect you would only have to drill 2 small holes through the top drywall closets to the joists 

Or do I just use pot lights and build those backer boxes?


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## jrref

HT Geek said:


> I've done quite a bit of research on various materials' sound absorption characteristics and I've never been able to locate data on Comfort Batt. My suspicion, FWIW: there's very little difference between the two.
> 
> Safe'n'Sound is slightly more dense (less than 0.5 psf). Comfort Batt is thicker (3-1/2" vs. 3"). ComfortBatt ought to theoretically be a bit better from a depth perspective, and Safe'n'Sound is theoretically a bit better from a mass perspective. Who knows. I say call it a wash. I suspect you'll get similar results from either.
> 
> Go for it and save some $ you can spend elsewhere on something more fun.


I don't think you will ever find that data but through experimentation, SafenSound does not insulate as good as ComfortBatt. I never experimented to see if ComfortBatt works as good as SafenSound in deadening sound but my guess is it probably does a better job at certain frequencies. Either way, you need insulation but most of the soundproofing will come from the sheetrock system you apply vs the insulation.


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## HT Geek

ncabw said:


> Here is what I've done for soundproofing hope it's going to be decent
> 
> 1)between the joist I went GG DW GG DW and then will add the insulation
> 2)ceiling will be DD & GG. I used the clips and furring channel to decouple from the ceiling
> 3) walls will be DD & GG. All four walls are now being built off(not touching)the foundation. I also will be using clips and furring channel on all wallls. Not sure if I need 2 since I already built the walls off the concrete foundation. Top plate I'm also using those IB-3 clips to decouple that from the ceiling. Under the bottom plate I added some rubber.
> 4) when I do the DW I will be leaving a 1/4" between all walls and using the GG sealant
> 5) in all walls I will be adding the roxul insulation just for sound absorption sine I already have my R rating with the sparky foam on the concrete foundation
> 
> 
> Anything else I should be thinking about?


Sounds good. You mention sound proofing between the joists. I presume you are talking between ceiling joists and this is a basement build??

I'm not sure about only rubber under the bottom plate. First, I presume you mean an independent (inner) stud wall. Second, are you going to put rubber down on the entire floor? Third, I've seen a combo of OSB + rubber on the floor, but have not seen only rubber. I did 2x OSB on top of rubber mat. My theater is on 2nd floor.




> Next is lights. Someone mentioned there might be some puck lights that would just fit into the bottom DD and then to connect you would only have to drill 2 small holes through the top drywall closets to the joists
> 
> Or do I just use pot lights and build those backer boxes?


Personal preference. However, you are correct the puck lights have a negligible impact on your DW shell, therefore no need for backer boxes with them.


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## ncabw

It's a basement build so yes doing the DD & GG between ceiling joist. 

The rubber is only on the new inner walls I'm building and it's right on the concrete. I'm doing the sub floor after. It's going to be that 2'x4' dricore flooring I forget the exact name of the one I'm using. 

Is this doing things backwards? I can't change now since we did all the walls and ceilings yesterday and today. 

Is there anything I have to do with the subfloor regarding soundproofing? I would think leave it all 1/8 or 1/4 off the walls. Maybe more? Didn't really think about that step yet. Lol.


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## HT Geek

ncabw said:


> It's a basement build so yes doing the DD & GG between ceiling joist.
> 
> The rubber is only on the new inner walls I'm building and it's right on the concrete. I'm doing the sub floor after. It's going to be that 2'x4' dricore flooring I forget the exact name of the one I'm using.
> 
> Is this doing things backwards? I can't change now since we did all the walls and ceilings yesterday and today.
> 
> Is there anything I have to do with the subfloor regarding soundproofing? I would think leave it all 1/8 or 1/4 off the walls. Maybe more? Didn't really think about that step yet. Lol.


Ok. In the basement, from what I understand you should be good with the rubber under the inner walls. Most people use sill plate protector. Cheap and effective. All you actually need is a moisture barrier.

No, you're NOT doing it backwards. You're good. 

Leave a 1/4-1/2" gap between drywall and the floor, at the bottom and top of your drywall when you hang it on the walls and ceiling. When you're done slapping up each layer of sheetrock, go back and use acoustic caulk to fill in the gaps.

In terms of drywall order, you'll have to decide if you want to the traditional ceiling first, walls second approach or stagger them. The former is theoretically stronger (the walls help hold up the ceiling). The latter is better for soundproofing. Personally, I suggest the latter (staggered) approach. If you actually have to worry about your ceiling sagging it's because you used an insufficient number of screws or some other problem. IMHO, the fact that it's held up a bit better on the edges won't help. It just means if it's going to sag that it will happen in the middle. LoL.

Personally, since you built the inner walls first, I would not leave a gap between your inner walls and your raised floor. I don't believe doing so would yield you any significant improvement in sound reduction. I think you'd just make more work for yourself and introduce a potential path for moisture to wick up into your drywall.

The important gap relative to a floor is when it's a gap between your inner floor and the original stud walls. For instance, in my case my inner wall studs sit on top of my raised floor. I have a gap from my original studs to the raised floor. My inner walls were built on top of the raised floor. 

Since you haven't done your floor quite yet, I've attached a couple of diagrams to this post for Kinetics RIM floor isolation system. You may want to peruse the info. Even if you don't use RIM, it may give you some ideas.

Good luck. 

Have you started a build thread yet? If not, please do. It's the best way to solicit advice and keep yourself motivated.


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## tnycman

I'm planning to do some sound treatments to the room, nothing crazy just something that would help absorb the sound i guess. I'm placing R38 insulation and drywall the side walls, along with some diy, this is for the walls, not sure what to use for the floor and the ceiling. The room is an attic approximately 15x12 and sitts on the top of two bathrooms below.
Any thoughts ?

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## HT Geek

tnycman said:


> I'm planning to do some sound treatments to the room, nothing crazy just something that would help absorb the sound i guess. I'm placing R38 insulation and drywall the side walls, along with some diy, this is for the walls, not sure what to use for the floor and the ceiling. The room is an attic approximately 15x12 and sitts on the top of two bathrooms below.
> Any thoughts ?


We need more details about the environment (room) to help you out.

For example, you said in part,


> I'm placing R38 insulation and drywall the side walls, along with some diy, this is for the walls, not sure what to use for the floor and the ceiling.


Based on your statement, what are you placing the R38 on? When you say, "drywall the side walls," are you adding drywall on top of an existing wall's surface, an existing stud wall with nothing attached to it before-hand, have you built a 'room-within-a-room', etc.? 

Floor and ceiling.... Ok, you've mentioned this is above 2 bathrooms. Is it on your 2nd floor, your main floor, etc.? What is next to your future HT room on the same level? What is above it? Are any surfaces in the room currently finished? If so, with what and what do you plan to do with those finishes (if anything)?

Hopefully, you get the gist of where I'm going with this. The more detail the better. Photos can also be very helpful, but at this stage I believe detailed descriptions of your current situation and what you want to accomplish are good starting points.


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## tnycman

HT Geek said:


> We need more details about the environment (room) to help you out.
> 
> For example, you said in part,
> 
> Based on your statement, what are you placing the R38 on? When you say, "drywall the side walls," are you adding drywall on top of an existing wall's surface, an existing stud wall with nothing attached to it before-hand, have you built a 'room-within-a-room', etc.?
> 
> Floor and ceiling.... Ok, you've mentioned this is above 2 bathrooms. Is it on your 2nd floor, your main floor, etc.? What is next to your future HT room on the same level? What is above it? Are any surfaces in the room currently finished? If so, with what and what do you plan to do with those finishes (if anything)?
> 
> Hopefully, you get the gist of where I'm going with this. The more detail the better. Photos can also be very helpful, but at this stage I believe detailed descriptions of your current situation and what you want to accomplish are good starting points.


Hi Geek,

Seems that i left out the majority of info.

Ok so the room is a small attic room to be converted into HT.

HT room size 15x12
The HT spans above the bathrooms, however the entire attic spans the entire 2nd floor which contains of 3 bedroom and 2 bathrooms.
The area above the bedrooms will not be part of HT because of low clearance, but will be separated by a wall using 2x4 insulation and drywall.
So the HT sits a top of 2 bathrooms, L, R walls are to the storage low clearance space.
Front wall is facing outside the house no other house directly attched. Rear wall is the wall outside to the second floor in the hallway.
Ceilings are pitched and above is the roof.

Agan all the walls will have insulations of at least R38 mostly for the winter weather, but hopefully will do some sound treatments too.

Right now there are no drywalls installed, so the walls are open.

Hope this clarified a bit.

Sent from my SM-N920V using Tapatalk


----------



## tnycman

HT Geek said:


> We need more details about the environment (room) to help you out.
> 
> For example, you said in part,
> 
> Based on your statement, what are you placing the R38 on? When you say, "drywall the side walls," are you adding drywall on top of an existing wall's surface, an existing stud wall with nothing attached to it before-hand, have you built a 'room-within-a-room', etc.?
> 
> Floor and ceiling.... Ok, you've mentioned this is above 2 bathrooms. Is it on your 2nd floor, your main floor, etc.? What is next to your future HT room on the same level? What is above it? Are any surfaces in the room currently finished? If so, with what and what do you plan to do with those finishes (if anything)?
> 
> Hopefully, you get the gist of where I'm going with this. The more detail the better. Photos can also be very helpful, but at this stage I believe detailed descriptions of your current situation and what you want to accomplish are good starting points.


I just found some old pictures, but thisbis pretty much the place.

Front wall facing outside :









Back wall inside the house hallway.










Side walls of the storage area:










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----------



## HT Geek

Alright that's great. So, pretty-much you have a blank slate (of sorts).

Your previous post was helpful, btw. I tried to respond on my cell phone but it was a disaster. I should perhaps invest in TapaTalk. Lol.

How much height do you have to build a ceiling over the 15x12 space? Is your current clearance uniform across the entire space? (e.g. 8' 2" over 15' x 12')

Are any of the wall studs up yet or is this a blank slate except for the floor?

How will you enter the room from below?

You mentioned more space that is not suitable due to height constraints. You may want to think about whether or not you could place your screen and front speakers in one of those lower ceiling height areas. Or perhaps your A/V rack. I'll bet you can find something to make parts of it useful and free up more room for your main area.


----------



## tnycman

HT Geek said:


> Alright that's great. So, pretty-much you have a blank slate (of sorts).
> 
> Your previous post was helpful, btw. I tried to respond on my cell phone but it was a disaster. I should perhaps invest in TapaTalk. Lol.
> 
> How much height do you have to build a ceiling over the 15x12 space? Is your current clearance uniform across the entire space? (e.g. 8' 2" over 15' x 12')
> 
> Are any of the wall studs up yet or is this a blank slate except for the floor?
> 
> How will you enter the room from below?
> 
> You mentioned more space that is not suitable due to height constraints. You may want to think about whether or not you could place your screen and front speakers in one of those lower ceiling height areas. Or perhaps your A/V rack. I'll bet you can find something to make parts of it useful and free up more room for your main area.



The top hight is about 86 inches, and its pitched roof which drops to about 56 inches on the sides, the screen will go where the plywoods are located and the AV rack will be build to the right inwall build rack.

I just measured the room and its actually 
13W x 15L..

Sent from my SM-N920V using Tapatalk


----------



## HT Geek

tnycman said:


> The top hight is about 86 inches, and its pitched roof which drops to about 56 inches on the sides, the screen will go where the plywoods are located and the AV rack will be build to the right inwall build rack.
> 
> I just measured the room and its actually
> 13W x 15L


13x15 by 86" high all throughout? Or do you mean the peak height is 86" and part of that 13x15 room is


----------



## HT Geek

tnycman said:


> The top hight is about 86 inches, and its pitched roof which drops to about 56 inches on the sides


Where will your room egress be located? How will you enter the room? As in... where in the room plan is the entrance (e.g. right rear corner, entering from side wall) and how will you get to this room/floor from the rest of the house?

I'm trying to get the complete picture of the space you have to work with.


----------



## tnycman

HT Geek said:


> Where will your room egress be located? How will you enter the room? As in... where in the room plan is the entrance (e.g. right rear corner, entering from side wall) and how will you get to this room/floor from the rest of the house?
> 
> I'm trying to get the complete picture of the space you have to work with.


The entrance will be left rear corner. There will be stairs build and and the door entrance from the floor below.

Sent from my SM-N920V using Tapatalk


----------



## tnycman

HT Geek said:


> 13x15 by 86" high all throughout? Or do you mean the peak height is 86" and part of that 13x15 room is


----------



## ncabw

HT Geek said:


> Have you started a build thread yet? If not, please do. It's the best way to solicit advice and keep yourself motivated.


Thanks for the all the help. I did start a thread in the multi room board. This build seems to have now changed into more of a theater build. So i might start one there.


http://www.avsforum.com/forum/15-ge...oms/2368481-ncabw-sports-themed-basement.html


----------



## Gouie

I've decided to give communicating doors a shot. Not only will it save me from scouring the city looking for someone willing to amuse my ideas around a single, enormous door, I'm understanding it is in many cases the preferred method if you have the room. My wall depth isn't drastic but should be thick enough to accommodate two even if the space between the two is only an inch. I'm uncertain about mount of the inside (theatre) door. My thought is to use two jams to avoid re-coupling the framing. If I'm on the right track there, I can't figure out the best way of mounting the jam. Without attaching to the framing all that remains is two layers of drywall. 


Welcome your thoughts.


----------



## GatorBlues

I'm including a basement theater in a soon to be built house. I met with my builder about it earlier this week. He proposed to use staggered studs to decouple the theater walls from the walls of the rest of the house. Full double studs would have taken too much space out of the theater. We will hang double drywall with green glue on the staggered studs that jut into the theater. He will run ceiling joists parallel to the floor joists that support the floor above. The ceiling joists will be attached only to the theater rooms staggered studs. Thus, the room's walls and ceiling will be nicely decoupled from the everything else in the house except the concrete floor. I have a few lingering questions:

1. The theater is nestled in the corner of the finished basement space. There are only two theater walls that are shared with other rooms. In each of the rooms that share a wall with the theater, the drywall (obviously) will be hung on that room's side of the staggered stud wall. Would there be much benefit to using double drywall and green glue on the other room's side of the wall too (i.e., in DD/GG on both sides)? 

2. The builder asked if I wanted to use resilient clips and channel inside the theater in between the staggered studs and DD/GG. Will that add much benefit, and if so, at what ballpark cost?

3. Is there much risk of transmitting low frequencies to the rest of the house through the concrete floor? If so, (a) is there anything that should be added between the concrete floor and the flooring in the theater room, and (b) what is the ballpark cost of it? 

Thanks in advance for your help.


----------



## HT Geek

Gouie said:


> I've decided to give communicating doors a shot. Not only will it save me from scouring the city looking for someone willing to amuse my ideas around a single, enormous door, I'm understanding it is in many cases the preferred method if you have the room.


Yes, indeed. That's great you have the space and inclination. 



> My wall depth isn't drastic but should be thick enough to accommodate two even if the space between the two is only an inch. I'm uncertain about mount of the inside (theatre) door. My thought is to use two jams to avoid re-coupling the framing. If I'm on the right track there, I can't figure out the best way of mounting the jam. Without attaching to the framing all that remains is two layers of drywall.


I presume the doors will open in opposite directions. Is that true?

Your're correct that using 2 jambs is the preferred method. Some folks use a single piece of wood for the jambs. Technically this re-couples the walls but only at that point. The hardware for each door is still on each respective side of the room shell. You can put acoustic caulk on the walls before applying the jamb and that will help with vibration transfers. Another option is to use 2 jambs with a 1/4" gap between them. Caulk behind the jambs and in the gap. You have a few options on filling the gap. One is to use acoustic caulk, smooth it out and leave it like that if you think it looks OK. You could use 1/8" gap but I'd go with 1/4" because wood expands and contracts slightly with the seasons. 

I recommend OSI SC-175 acoustic caulk. It is cheap and paintable. The lowest cost supplier I've found is Home Depot where it is $77 a case shipped - that is $6.42 per tube). It only comes in 28 oz. tubes, so you'll want a something to squirt it such as this awesome caulk gun. If you will be doing much of the work on your HT build personally, do yourself a favor and get a Newborn Caulk Gun. Another option to seal the gap is to use Closed Cell Backer Rod (aka 'caulk saver') and acoustic caulk. You shove the backer rod in the gap, then caulk. Yet another idea is to use a viscoelastic glue (e.g. Green Glue) between the jams and the door frames. Still make a gap and caulk between the two jambs as described above. 

If your gap is more than 1/4" I'd recommend finding an appropriate size backer rod as you will have a difficult time getting the caulk to stick very well without one. Either way, sand, prime, and paint over the caulk. If you do a clean job no one will notice and you'll preserve the sound shell as best as you can.

The ideal communicating door setup is to have an air gap of 3' or more (but at least 8" or so). Even if it's coupled to the room shell, it will hardly matter. Naturally, most people don't have the space to do so, or don't wish to sacrifice it or change their room layout.


----------



## HT Geek

GatorBlues said:


> I'm including a basement theater in a soon to be built house. I met with my builder about it earlier this week. He proposed to use staggered studs to decouple the theater walls from the walls of the rest of the house. Full double studs would have taken too much space out of the theater.


Very few contractors have built double stud walls. Staggered stud is uncommon, but you're more likely to find a general or framing contractor who's done it before. Double stud walls will give you better performance, at the expense of another 7" of room length and width (presuming 2x4's). Is your space relatively small for length or width? Of course, it's a personal decision regardless.




> We will hang double drywall with green glue on the staggered studs that jut into the theater. He will run ceiling joists parallel to the floor joists that support the floor above. The ceiling joists will be attached only to the theater rooms staggered studs. Thus, the room's walls and ceiling will be nicely decoupled from the everything else in the house except the concrete floor.


That will be very good. 




> I have a few lingering questions:
> 
> 1. The theater is nestled in the corner of the finished basement space. There are only two theater walls that are shared with other rooms. In each of the rooms that share a wall with the theater, the drywall (obviously) will be hung on that room's side of the staggered stud wall. Would there be much benefit to using double drywall and green glue on the other room's side of the wall too (i.e., in DD/GG on both sides)?


Yes! Most definitely.

That combination was the highest performing test of Green Glue completed by Orfield Laboratories when measuring combined TL across all frequencies, and had the # 1 highest performance for 14 of the tested frequencies (out of 26 freqs total). It was also the 2nd highest performer based on STC (62). 




> 2. The builder asked if I wanted to use resilient clips and channel inside the theater in between the staggered studs and DD/GG. Will that add much benefit, and if so, at what ballpark cost?


Don't use resilient clips and channel (aka "RC"). Resilient Channel is an older technology with a sordid history of poor installations and liability lawsuits. Do not allow someone to talk you into using it. If you need more info, google, "resilient channel lawsuit." BTW, clips don't work with RC. 

Instead, look at hat channel + clips, which is the modern standard. Hat channel (25 gauge steel) + clips is the only other wall combo I've seen data for that would beat what I described above in preceding section (i.e. 2x DW/GG sandwich on both sides of wall). Personally, I would do one or the other but not both. You're paying a lot of $ for a very small difference in performance between these two ideas. If I had to pick, I'd say you're better off going with the clips & channel on the inside of the HT room and forgoing the GG on the outside of the room (i.e. do normal drywall, tho use 5/8" instead of standard 1/2" as it's almost same cost).

*BAD*:











*GOOD*:











Another thought: if you're doing to do clips & channel, should you still have your ceiling framed independently? I would think so. If you have the space, doing independent joists is the optimal method. Cost should be about the same as clips & channel on the ceiling.

And some more thoughts: if you're considering clips & channel then why do staggered studs? Or why not do double stud if you're willing to do staggered studs + lose more length/width for the channels?

Now, if you are going to have a baby sleeping in the room next door, all that's out the window and I would go to extremes. Otherwise, it may not make sense financially and from a space constraint perspective to do both staggered stud + clips/channel. That sounds like overkill to me IMHO. But as usual it depends on your goals.

Cost of the clips is the killer. Range $2-$7 each depending on manufacturer and product. Hat channel is cheap. You need to do the math for each product to figure out how many clips you need. Look at max weight per clip versus weight of building materials. Don't forget about anecdotal items such as wall sconces, columns, wall speakers, etc. that add weight. Give yourself 20% or so cushion at least. Don't over tax them or you may get sagging walls/ceilings over time.




> 3. Is there much risk of transmitting low frequencies to the rest of the house through the concrete floor? If so, (a) is there anything that should be added between the concrete floor and the flooring in the theater room, and (b) what is the ballpark cost of it?


Depends on various factors such as where your speakers and subs are. Impact noise/vibrations are going to be your nemesis (think of the thumping of your subs if they are downward firing). It might not be a big deal if you have carpet in the HT room and carpet in neighboring rooms, though you'll likely still feel it. If you don't want to feel it at all in adjacent rooms you will have to take steps to make that happen.

Most people put some kind of flooring down on the concrete for various reasons. Hard flooring surfaces will be an issue if you don't have a floating floor between the surfaces (it's really going to be a personal preference thing). Here is an experiment to give you an idea of your comfort level. Get a friend to help you with this test in your basement. Grab a hammer and a piece of OSB or plywood 1/2"-3/4" thick and a rubber mat of some sort. Stand barefoot on the concrete. Have your friend stand 5 feet away from you and drop the hammer on the floor from chest height. Feel the vibration in your feet. Now have your friend drop the hammer onto the OSB/plywood. You will notice a difference. The wood will attenuate the vibration a bit, but not much. Now repeat a 3rd time but place the rubber mat under the OSB/plywood and then do the hammer drop test. Another variation is where you stand on the OSB/carpet surfaces and the hammer is dropped onto the concrete each time. [Disclaimer: Please don't blame me if you crack your floor with the hammer!]

The point of the experiment is to demonstrate that cushiony or rubbery type surfaces absorb pressure from impacts better than concrete or concrete/wood. Just putting down a wood sub-floor will help, but not much. So, if you want to attenuate vibrations, that is the direction you should look. If you only place wood (or nothing) on the floor, sound from your subs, speakers, etc. won't be attenuated as much. Carpet pad works well too. The further you are from the source of the impact, the less pronounced the feeling. 

Concrete is good at doing things like stopping sound moving through the air, when the origin of the sound is not touching the concrete or very nearly touching it. Sound hits the concrete and most of it gets absorbed before travelling to the other side (presuming sufficient thickness of concrete). However, on the floor or ceiling you're dealing with a different way that the sound is transmitted and it often becomes an issue (unless you like or want the effect).

Alfred Warnock wrote a good (and short) paper on this subject published in 1999 by the NRC.


----------



## Ladeback

HT Geek said:


> Very few contractors have built double stud walls. Staggered stud is uncommon, but you're more likely to find a general or framing contractor who's done it before. Double stud walls will give you better performance, at the expense of another 7" of room length and width (presuming 2x4's). Is your space relatively small for length or width? Of course, it's a personal decision regardless.
> 
> 
> 
> 
> That will be very good.
> 
> 
> 
> 
> Yes! Most definitely.
> 
> That combination was the highest performing test of Green Glue completed by Orfield Laboratories when measuring combined TL across all frequencies, and had the # 1 highest performance for 14 of the tested frequencies (out of 26 freqs total). It was also the 2nd highest performer based on STC (62).
> 
> 
> 
> 
> Don't use resilient clips and channel (aka "RC"). Resilient Channel is an older technology with a sordid history of poor installations and liability lawsuits. Do not allow someone to talk you into using it. If you need more info, google, "resilient channel lawsuit." BTW, clips don't work with RC.
> 
> Instead, look at hat channel + clips, which is the modern standard. Hat channel (25 gauge steel) + clips is the only other wall combo I've seen data for that would beat what I described above in preceding section (i.e. 2x DW/GG sandwich on both sides of wall). Personally, I would do one or the other but not both. You're paying a lot of $ for a very small difference in performance between these two ideas. If I had to pick, I'd say you're better off going with the clips & channel on the inside of the HT room and forgoing the GG on the outside of the room (i.e. do normal drywall, tho use 5/8" instead of standard 1/2" as it's almost same cost).
> 
> *BAD*:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *GOOD*:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Another thought: if you're doing to do clips & channel, should you still have your ceiling framed independently? I would think so. If you have the space, doing independent joists is the optimal method. Cost should be about the same as clips & channel on the ceiling.
> 
> And some more thoughts: if you're considering clips & channel then why do staggered studs? Or why not do double stud if you're willing to do staggered studs + lose more length/width for the channels?
> 
> Now, if you are going to have a baby sleeping in the room next door, all that's out the window and I would go to extremes. Otherwise, it may not make sense financially and from a space constraint perspective to do both staggered stud + clips/channel. That sounds like overkill to me IMHO. But as usual it depends on your goals.
> 
> Cost of the clips is the killer. Range $2-$7 each depending on manufacturer and product. Hat channel is cheap. You need to do the math for each product to figure out how many clips you need. Look at max weight per clip versus weight of building materials. Don't forget about anecdotal items such as wall sconces, columns, wall speakers, etc. that add weight. Give yourself 20% or so cushion at least. Don't over tax them or you may get sagging walls/ceilings over time.
> 
> 
> 
> 
> Depends on various factors such as where your speakers and subs are. Impact noise/vibrations are going to be your nemesis (think of the thumping of your subs if they are downward firing). It might not be a big deal if you have carpet in the HT room and carpet in neighboring rooms, though you'll likely still feel it. If you don't want to feel it at all in adjacent rooms you will have to take steps to make that happen.
> 
> Most people put some kind of flooring down on the concrete for various reasons. Hard flooring surfaces will be an issue if you don't have a floating floor between the surfaces (it's really going to be a personal preference thing). Here is an experiment to give you an idea of your comfort level. Get a friend to help you with this test in your basement. Grab a hammer and a piece of OSB or plywood 1/2"-3/4" thick and a rubber mat of some sort. Stand barefoot on the concrete. Have your friend stand 5 feet away from you and drop the hammer on the floor from chest height. Feel the vibration in your feet. Now have your friend drop the hammer onto the OSB/plywood. You will notice a difference. The wood will attenuate the vibration a bit, but not much. Now repeat a 3rd time but place the rubber mat under the OSB/plywood and then do the hammer drop test. Another variation is where you stand on the OSB/carpet surfaces and the hammer is dropped onto the concrete each time. [Disclaimer: Please don't blame me if you crack your floor with the hammer!]
> 
> The point of the experiment is to demonstrate that cushiony or rubbery type surfaces absorb pressure from impacts better than concrete or concrete/wood. Just putting down a wood sub-floor will help, but not much. So, if you want to attenuate vibrations, that is the direction you should look. If you only place wood (or nothing) on the floor, sound from your subs, speakers, etc. won't be attenuated as much. Carpet pad works well too. The further you are from the source of the impact, the less pronounced the feeling.
> 
> Concrete is good at doing things like stopping sound moving through the air, when the origin of the sound is not touching the concrete or very nearly touching it. Sound hits the concrete and most of it gets absorbed before travelling to the other side (presuming sufficient thickness of concrete). However, on the floor or ceiling you're dealing with a different way that the sound is transmitted and it often becomes an issue (unless you like or want the effect).
> 
> Alfred Warnock wrote a good (and short) paper on this subject published in 1999 by the NRC.



I am probably going with value clips at $1.89 a clip and hat channel for my ceiling with2X DW and GG. For my walls I probably just do 2X DW and GG. There is nothing nobody else would be outside my HT when watching a movie loud. 

I found this place online I may order from. https://www.tmsoundproofing.com/Resilient-Sound-Clips.html


----------



## Gouie

HT Geek said:


> Yes, indeed. That's great you have the space and inclination.
> 
> 
> 
> 
> 
> 
> 
> I presume the doors will open in opposite directions. Is that true?
> 
> 
> 
> Your're correct that using 2 jambs is the preferred method. Some folks use a single piece of wood for the jambs. Technically this re-couples the walls but only at that point. The hardware for each door is still on each respective side of the room shell. You can put acoustic caulk on the walls before applying the jamb and that will help with vibration transfers. Another option is to use 2 jambs with a 1/4" gap between them. Caulk behind the jambs and in the gap. You have a few options on filling the gap. One is to use acoustic caulk, smooth it out and leave it like that if you think it looks OK. You could use 1/8" gap but I'd go with 1/4" because wood expands and contracts slightly with the seasons.
> 
> 
> 
> I recommend OSI SC-175 acoustic caulk. It is cheap and paintable. The lowest cost supplier I've found is Home Depot where it is $77 a case shipped - that is $6.42 per tube). It only comes in 28 oz. tubes, so you'll want a something to squirt it such as this awesome caulk gun. If you will be doing much of the work on your HT build personally, do yourself a favor and get a Newborn Caulk Gun. Another option to seal the gap is to use Closed Cell Backer Rod (aka 'caulk saver') and acoustic caulk. You shove the backer rod in the gap, then caulk. Yet another idea is to use a viscoelastic glue (e.g. Green Glue) between the jams and the door frames. Still make a gap and caulk between the two jambs as described above.
> 
> 
> 
> If your gap is more than 1/4" I'd recommend finding an appropriate size backer rod as you will have a difficult time getting the caulk to stick very well without one. Either way, sand, prime, and paint over the caulk. If you do a clean job no one will notice and you'll preserve the sound shell as best as you can.
> 
> 
> 
> The ideal communicating door setup is to have an air gap of 3' or more (but at least 8" or so). Even if it's coupled to the room shell, it will hardly matter. Naturally, most people don't have the space to do so, or don't wish to sacrifice it or change their room layout.



Thank you for the insight. So, is this setup with the hassle if the gap between doors will be less than 3"? 

My approach would likely be two jams but I'm still a little unclear on how to mount the inside door. With a single framed wall the exterior jam will be mounted to the stud wall. What does a person mount the interior jam to?


----------



## GatorBlues

HT Geek said:


> Very few contractors have built double stud walls. Staggered stud is uncommon, but you're more likely to find a general or framing contractor who's done it before. Double stud walls will give you better performance, at the expense of another 7" of room length and width (presuming 2x4's). Is your space relatively small for length or width? Of course, it's a personal decision regardless.
> 
> *
> The room will be 22' 8" long inside the standard framing. That's a fairly good size, I think. However, we are trying to squeeze in 2 rows of theater recliners plus a third row consisting of a small counter and chairs -- 3 rows total. Wife's orders.*
> 
> 
> 
> Don't use resilient clips and channel (aka "RC"). Resilient Channel is an older technology with a sordid history of poor installations and liability lawsuits. Do not allow someone to talk you into using it. If you need more info, google, "resilient channel lawsuit." BTW, clips don't work with RC.
> 
> Instead, look at hat channel + clips, which is the modern standard. Hat channel (25 gauge steel) + clips is the only other wall combo I've seen data for that would beat what I described above in preceding section (i.e. 2x DW/GG sandwich on both sides of wall). Personally, I would do one or the other but not both. You're paying a lot of $ for a very small difference in performance between these two ideas. If I had to pick, I'd say you're better off going with the clips & channel on the inside of the HT room and forgoing the GG on the outside of the room (i.e. do normal drywall, tho use 5/8" instead of standard 1/2" as it's almost same cost).
> 
> *I'm new to the terminology. I'm pretty sure the builder was talking about hat channel with clips. I'll reconfirm with him to be sure we're on the same page if that's the direction we go. *
> 
> 
> Another thought: if you're doing to do clips & channel, should you still have your ceiling framed independently? I would think so. If you have the space, doing independent joists is the optimal method. Cost should be about the same as clips & channel on the ceiling.
> 
> *The room will be 11.5 feet tall in the front row and 10 feet in the back. Losing a couple inches for separate joists shouldn't be a problem. Plus, preventing sound from going up into the main level of the house is my number 1 concern. *
> 
> 
> And some more thoughts: if you're considering clips & channel then why do staggered studs? Or why not do double stud if you're willing to do staggered studs + lose more length/width for the channels?
> *
> So it sounds like double studs with 2x4s would be best, correct? Again, my initial hesitation is that I'm worried about fitting 3 rows plus an acoustically transparent screen into 22' 8". (The effort to squeeze it all in will be aided a little by an unfinished space abutting the front wall. We will build boxes for speakers that extend into the unfinished space, which in turn allows the AR screen to be closer to the front wall.) If I add second studs on each end plus double drywall, I'll lose about a foot and will have about 21' 8" left for living space, correct?
> 
> By the way, double drywall and green glue INSIDE the theater room is a still recommended no matter what decoupling is used, correct?*
> 
> 
> Now, if you are going to have a baby sleeping in the room next door, all that's out the window and I would go to extremes. Otherwise, it may not make sense financially and from a space constraint perspective to do both staggered stud + clips/channel. That sounds like overkill to me IMHO. But as usual it depends on your goals.
> 
> Cost of the clips is the killer. Range $2-$7 each depending on manufacturer and product. Hat channel is cheap. You need to do the math for each product to figure out how many clips you need. Look at max weight per clip versus weight of building materials. Don't forget about anecdotal items such as wall sconces, columns, wall speakers, etc. that add weight. Give yourself 20% or so cushion at least. Don't over tax them or you may get sagging walls/ceilings over time.
> 
> *I googled and found Whisper Clips for $6 each. Ballpark, how many of those do you need? Am I looking at a thousand dollars in clips or several thousand?*


Thank you very much for your help. If I may impose on your kindness a little longer, I wrote a few follow up comments/questions above in the quote box in red.


----------



## ncabw

I think I ran into another problem soundproofing my room. I have 4 return air using the joists as the cavity. They are side by side right in the middle of the room. I can use roxul everywhere but these four runs. What options do I have? Since I decoupled the ceiling from the joist I have to seal the bottom of these cavities so it's not sucking air from everywhere in the room. 

My plan was just add 5/8 DW to seal it. Then I would still have the DD&GG on the ceiling. My dad mentioned maybe get that "sound board" it's suppose to equal 4 sheets. 

I can add a pic if this is not clear. 

Also is there anything I can do with the registers to soundproof them? Or is this 2 late in the game for that now? I have 2 in the room. For now I'm not adding the return air in the room going to add an extra one right out front the door. If it gets to stuffy in the room I will have to add one in the room later on. 

So much to think about. Should of looked into all this before starting to build my house. Lol.


----------



## HT Geek

GatorBlues said:


> Thank you very much for your help. If I may impose on your kindness a little longer, I wrote a few follow up comments/questions above in the quote box in red.
> 
> 
> 
> The room will be 22' 8" long inside the standard framing. That's a fairly good size, I think. However, we are trying to squeeze in 2 rows of theater recliners plus a third row consisting of a small counter and chairs -- 3 rows total. Wife's orders.


Sounds familiar to me in more ways than one. First, my room was 24x17 before framing. Second, my wife made the same suggestion, though I managed to talk her out of it because I placed the entrance at a rear corner (it was either that or rear entrance facing screen or side entrance and lose 4' of width). After framing, my room is now ~16' wide and just over 23' long. 

I'm waiting for the wife battle after I install the TV and built-in mini-fridge just outside the door (in hallway). Sometimes it's easier to ask for forgiveness rather than permission.  In your case you can always blame the contractor. 




> I'm new to the terminology. I'm pretty sure the builder was talking about hat channel with clips. I'll reconfirm with him to be sure we're on the same page if that's the direction we go.


NP.  Please make sure you and your contractor are on the same page. RC is still used. Hat channel gets its name from its shape. It must be used with isolation clips, whereas RC does not use clips and you simply screw it into the wall. 




> The room will be 11.5 feet tall in the front row and 10 feet in the back. Losing a couple inches for separate joists shouldn't be a problem. Plus, preventing sound from going up into the main level of the house is my number 1 concern.


Is the height differential due to a riser you will build for the rear row, or due to a sloped ceiling?




> So it sounds like double studs with 2x4s would be best, correct?


Ideally, yes.

Jumping ahead of myself a bit (details below), based on what you're saying... damping sound going up thru ceiling most important, 2 rooms on same level in basement but not too worried about them and noise.... I'm thinking you should be focused on options that favor reducing sound transmission to the ceiling.

In regards to that thought, as you may know by now, the wall studs DO also transmit sound upward and therefore focusing on de-coupling and damping the ceiling only is likely to provide unsatisfactory results. However, it sounds to me (if I'm reading your comments correctly) that the ceiling is a priority.

IMHO, your ideal solution is a true room-within-a-room. Forget the clips & channel. Do a true double-stud wall complete with 1" air gap and an independent ceiling joist setup (also with 1" gap from floor boards above). Stuff insulation in between all joists and studs. Use 24" O.C. wall studs and 2x10 ceiling joists. Put 3 layers of drywall with GG sandwich on your ceiling, and DD/GG on the walls. Use Zero International door seals and auto door bottom on the theater entrance. Communicating door setup if you can. Yes, you'll lose about 1' of wall space both ways and 1' of ceiling, but you will have a kick ass sound-proofed home theater that all your friends and neighbors will be jealous of.  Less complicated. Better results. Cheaper (wood less $ than clips + hire a framer and they will spend less time/money putting it up).

Ok... back to answering questions and details....




> Again, my initial hesitation is that I'm worried about fitting 3 rows plus an acoustically transparent screen into 22' 8". (The effort to squeeze it all in will be aided a little by an unfinished space abutting the front wall. We will build boxes for speakers that extend into the unfinished space, which in turn allows the AR screen to be closer to the front wall.)


Sounds like that will likely work well for you. Hopefully, you know which speakers you want for L/C/R so you won't have an "oops" moment when you try to fit them into the recessed area. Also make sure you will be able to mount the speakers flush or poking a bit into the room, and that you have some kind of backer box built around each speaker to help direct the sound where you want it.

I don't want to overwhelm you with info, but when you have a chance take a look at some of the threads on AVS regarding Baffle Walls. They will give you an idea of some things you should consider with your approach. Essentially, you want to ensure the energy of your speakers is radiating outward and not into their cubbies.




> If I add second studs on each end plus double drywall, I'll lose about a foot and will have about 21' 8" left for living space, correct?


Yes, correct. You have the right idea. This is why more people go with clips & channel on the walls. You lose ~2" per wall. Since you've been bitten by the HT bug, you're going to find this world is a never ending compromise of pretzel logic. It seems no matter what you want to accomplish, it's always at the expense of something else.




> By the way, double drywall and green glue INSIDE the theater room is a still recommended no matter what decoupling is used, correct?


Yes. You seem to be on the right page overall. 




> I googled and found Whisper Clips for $6 each. Ballpark, how many of those do you need? Am I looking at a thousand dollars in clips or several thousand?


There's a little math involved in calculating the number of clips. You need to know the weight each can support and keep in mind you will need to have clips near the perimeter of your wall or ceiling. 

I just realized I don't recall reading your room width. I'm gonna take a wild guess based on memory that you'd need 40-50 clips for your ceiling alone if your room is 23x16, presuming it needs to hold the weight of 2x DW and GG sandwich. Without getting into too much detail atm, you will end up with a staggered pattern of the clips that favors a few extra clips on the ends of walls or on 2 sides of a ceiling near the edges.

The Whisper Clip is a "high end" de-coupling clip. You can spend a bit less and get performance that's very close (e.g. about $5 per clip) or go the cheapo clip route and lose a bit of performance but save substantial $ (about $2 per clip). The delta is the cheapo clips do not use a rubber damper. You're still lifting the hat channel off the wall and de-coupling screws (not in studs directly from drywall), but you lose some of the benefits of the more expensive clips that use two methods to reduce sound transmission (i.e., Isolation + damping for the more expensive clips vs. isolation only technique).

The exact # of clips you'd need depends in part on the manufacturer's recommendations, your room dimensions and shape, what they need to hold up (in terms of weight), and your comfort zone for risk if you choose to use as few as possible. 

However, you've got me thinking.... Why are you considering double stud walls yet clips and channel on the ceiling? Why not the other way around or do a true room-within-a-room and do double studs + an independent joist ceiling. To do a ceiling like that will cost about the same as the clips & channel, possibly less, and it's the ideal method. If you have 10-11 feet you have plenty of room.

If you take that approach, you will need to calculate the beam (joist) size based on desired load capability and span. So, spanning a 16' wide room for example will generally require 2x8 joists at a minimum. Cross bracing, sistering, and other techniques can increase your ceiling strength and/or reduce it's deflection (propensity to sag due to gravity). You need to allow 1" or so clearance from the floor joists above, so with a 2x8 for example you'd be talking about a total of 8-1/4" drop from your current ceiling height. As an example, you could even do 3 layers of drywall with GG in between each layer, and insulation between the joists (though you might need to step up to 2x10's and lose 11-1/4" total ceiling height).

Let's say for discussion's sake you lose 1' of ceiling height. You're still at 10.5' and 9' respectively. Plenty of room. I strongly encourage you to consider this route.

One more thought... with double studs you might not have room to fit the wife's goal of a 3rd row seating area and have the 1st row too close to the screen. You may want to discuss this issue with her a bit. With 3 rows and 23' or so to work with, it's likely that either the front or rear (3rd) row is going to suffer visually (too close or too far away from screen). Other negative factors to consider (why IMHO your room is too short for 3 rows): 3rd row is likely to be too close to rear speakers (they should be 4' or more from furthest row back; at least 2' away bare minimum); you need at least 7' between 1st row and 2nd row seating positions (your 1st row occupants will not be thrilled if the 2nd row occupants feet are touching their heads). Unless you have short statured family and friends, don't put them closer than that. You also need to allow room for folks to walk around if needed (bathroom breaks, etc.). Your 3rd row could go a few feet behind the 2nd if it's just bar stools, etc.

Have you sketched out where everything is going to line up? It's not critical when you're in the early stages and creating the shell (of the room), but it is going to matter soon. Actually, the biggest issue as it relates to drywalling the room is a function of where you need electrical and low-voltage pre-runs (e.g. network wire, speaker wire, conduits, etc.).

Don't rush the framing and drywall. You need a good plan first (not that you don't have one... just trying to save you headaches down the road).

Decide which features are most important in your room. For instance, reduced room length + completely isolated HT room or a 3rd seating row? Is your wife going to complain more about noise upstairs or not having a 3rd row in the room (but having 2 well spaced and comfortable rows)?


----------



## HT Geek

*One More Thing...*



GatorBlues said:


> 3. Is there much risk of transmitting low frequencies to the rest of the house through the concrete floor? If so, (a) is there anything that should be added between the concrete floor and the flooring in the theater room, and (b) what is the ballpark cost of it?


I wanted to briefly clarify my previous comments on this particular topic/question before I forgot....

My previous comments regarding some experiments you can do at your leisure.... with a good carpet and pad over it you should not have a lot of travel of sound from your HT room elsewhere in the basement. And you mentioned you're not too concerned about adjacent rooms. 

Point of my previous comments on this subject was simply to explain that there is some LFE travel thru concrete floors. However, when you have carpet/pad over the floor on the receive side (i.e. other room), it helps quite a bit. Plus the greater the distance the sound has to travel, the less the impact. It's mostly a concern when you have adjacent rooms that for some reason you are concerned about any sound from the HT room (e.g. kids bedrooms).

So bottom line is in your case I suspect it will be a non-issue.

If other neighboring rooms have hard floor surfaces instead of carpet, or if your HT room has hard surfaces instead of carpet, it may exacerbate the perception in the non-HT rooms.


----------



## HT Geek

Gouie said:


> Thank you for the insight. So, is this setup with the hassle if the gap between doors will be less than 3"?
> 
> My approach would likely be two jams but I'm still a little unclear on how to mount the inside door. With a single framed wall the exterior jam will be mounted to the stud wall. What does a person mount the interior jam to?


Even with a small (e.g. 3") gap, I would do it as long as you're able to put door seals (e.g. auto door bottom) on at least one of the doors (and preferably both).

You can't do a communicating door unless you have two door frames (inner and outer). You would have something like this:


Drywall
Drywall
2x4 stud
Gap
2x4 stud
Drywall

You could start with 2 pre-hung doors and use jamb extensions to connect them.

I don't recall if your build is clips & channel. If so, that would explain if you only have 1 door frame (i.e. only one 2x4 thick doorway). If that's the case, you may be better off creating your own thicker door (glue 2 doors together) and get some wide swing hinges, automatic door bottom and jambs.


----------



## HT Geek

ncabw said:


> I think I ran into another problem soundproofing my room. I have 4 return air using the joists as the cavity. They are side by side right in the middle of the room. I can use roxul everywhere but these four runs. What options do I have? Since I decoupled the ceiling from the joist I have to seal the bottom of these cavities so it's not sucking air from everywhere in the room.


Man, I feel bad for you. That is a whole can'o'worms that I'd personally avoid like the Plague. Joist cavity as a return duct is a bad idea IMO. You'll likely never get the system sealed properly. Not your fault. Just a bad idea.

Here are my thoughts on your options:

1. If you have access, run flex duct. There has to be some ductwork somewhere in that cavity that the cavity connects to.

2. The practice you describe is restricted by building codes. Check your local jurisdiction to find out their policy. Even if you didn't set it up, now that you are messing with that portion of your home, you are required to bring it up to current code.

3. Yes, drywall can be used (generally speaking) to seal those joists, but be very OCD about sealing them.




> Also is there anything I can do with the registers to soundproof them? Or is this 2 late in the game for that now? I have 2 in the room.


Why do you want to soundproof them? What is the problem you're trying to solve?

Is there flex duct or rigid metal supply line to the room?




> For now I'm not adding the return air in the room going to add an extra one right out front the door. If it gets to stuffy in the room I will have to add one in the room later on.


You definitely need an air return. If at all possible, use flex duct to hook it up. Don't use the joist-return duct trick if you can avoid it.


----------



## HT Geek

Ladeback said:


> I am probably going with value clips at $1.89 a clip and hat channel for my ceiling with2X DW and GG.


You should be good but quick 2 cents....

The "el cheapo" $2 clips isolate but do not dampen. The more expensive clips do both. That's basically the difference IMO, based on examination of different clips. You will get 80+% of the value out of the cheap clips. Going with more expensive clips is a matter of priority (are you willing to spend 3x cost to get 10-20% improved performance)?


----------



## ncabw

HT Geek said:


> 3. Yes, drywall can be used (generally speaking) to seal those joists, but be very OCD about sealing them.
> 
> 
> 
> 
> Why do you want to soundproof them? What is the problem you're trying to solve?
> 
> Is there flex duct or rigid metal supply line to the room?
> 
> 
> 
> 
> You definitely need an air return. If at all possible, use flex duct to hook it up. Don't use the joist-return duct trick if you can avoid it.


Won't the sound go right through the house with them open. Maybe not furnace is in basement so sound might only go back to the mechanical room? Then maybe same if I just cut a register into the main return air duct? 

My original thought was that sound would go through the ductwork throughout the house.


----------



## GatorBlues

HT Geek said:


> I wanted to briefly clarify my previous comments on this particular topic/question before I forgot....
> 
> My previous comments regarding some experiments you can do at your leisure.... with a good carpet and pad over it you should not have a lot of travel of sound from your HT room elsewhere in the basement. And you mentioned you're not too concerned about adjacent rooms.
> 
> Point of my previous comments on this subject was simply to explain that there is some LFE travel thru concrete floors. However, when you have carpet/pad over the floor on the receive side (i.e. other room), it helps quite a bit. Plus the greater the distance the sound has to travel, the less the impact. It's mostly a concern when you have adjacent rooms that for some reason you are concerned about any sound from the HT room (e.g. kids bedrooms).
> 
> So bottom line is in your case I suspect it will be a non-issue.
> 
> If other neighboring rooms have hard floor surfaces instead of carpet, or if your HT room has hard surfaces instead of carpet, it may exacerbate the perception in the non-HT rooms.


In response to both of your posts:

First and foremost, thank you very much for your advice. 

We have the extra height at the front of the theater because the builder is digging the theater room 16 inches deeper than the rest of the basement. We will walk in level with the other rooms, and then take two steps down to the front row. 

Based on your advice, adding separate ceiling joists, parallel to the floor joists and attached to the second set of interior studs, is almost certainly what I'll have the builder do. Should I have him dig the room even deeper or does 10.5 and 9 feet sound like good heights for a 22 by 18 room (post finishing measurements)? I don't want it to feel cramped.

We will carpet the floor in the theater. The adjoining rooms are the kids' playroom (carpet) and our bar/sitting room (tile). I'm relieved to know that I don't have to add even more expense to the theater floor to deal with LFE issues. This house is getting expensive, and the theater (based on my choices) is only a fraction of the cost overruns we have added (based on my wife's choices).

Do you know off the top of your head what would be the ballpark cost to install double drywall and green glue up against the floor above between the ceiling joists, as has been suggested to me in another thread, and how much benefit that would provide? Again, the room will be 23 by 19 prior to the second set of studs being added for room within a room. 

On an unrelated note, what's the most cost effective way to reduce sound between floors for the non-theater rooms? Is it a good idea to stuff pink fluffy between each floor throughout the house? Is there something else that should be done also, or instead, to dampen the sound between floors in the rooms getting normal day to day use? 

You suggested triple drywall with GG on the ceiling. Would it make sense to do the layers as (1) drywall, then GG, (2) OSB, then GG, and (3) drywall again, so that I can attach on ceiling lights (no cans; too much sound leak), atmos speaker mounts, and a projector into the ceiling?

Our plan is still only a sketch. I've gotten lots of helpful advice from kmhvball in his Cinema-Nati theater build thread (he successfully put 3 rows, with the last one being a small counter, into his room that is only slightly longer than mine), and from him and others (BigMouthinDC and thrillcat chief among them) in my Spinal Tap Theater build thread. I'm trying to get educated and understand the big picture ideas before drawing a final plan. The posters on this site, you included, are the most helpful group of strangers I've ever encountered.

Thank you again for all of your help.


----------



## Ladeback

HT Geek said:


> You should be good but quick 2 cents....
> 
> The "el cheapo" $2 clips isolate but do not dampen. The more expensive clips do both. That's basically the difference IMO, based on examination of different clips. You will get 80+% of the value out of the cheap clips. Going with more expensive clips is a matter of priority (are you willing to spend 3x cost to get 10-20% improved performance)?


 @geek, to me it not worth the extra cost for 10-20% improvement. I will need about 73 or so clips and the difference between the two is about $225.3 and that would pay for my hat channel. If it weren't for some wires I am trying to get below by using the clips and and hat channel I probably would use them to save more money and my wife isn't complaining to much about the sound yet, but I don't have my subs hooked up and I haven't cranked it up for awhile. I more want to not hear me kid playing with his hot wheels or running around upstairs then anything. 

This is my plan for now to do.


----------



## kmhvball

GatorBlues said:


> Do you know off the top of your head what would be the ballpark cost to install double drywall and green glue up against the floor above between the ceiling joists, as has been suggested to me in another thread, and how much benefit that would provide? Again, the room will be 23 by 19 prior to the second set of studs being added for room within a room.
> 
> On an unrelated note, what's the most cost effective way to reduce sound between floors for the non-theater rooms? Is it a good idea to stuff pink fluffy between each floor throughout the house? Is there something else that should be done also, or instead, to dampen the sound between floors in the rooms getting normal day to day use?
> 
> You suggested triple drywall with GG on the ceiling. Would it make sense to do the layers as (1) drywall, then GG, (2) OSB, then GG, and (3) drywall again, so that I can attach on ceiling lights (no cans; too much sound leak), atmos speaker mounts, and a projector into the ceiling?


I did the GG/ DW/GG/DW on my subfloor. I did most of it myself, I hired a guy to help for a day and paid him something like $150 to help. The Drywall cost itself isn't bad, the GG starts to add up - definitely do the 5 Gallon Buckets.

There is an outside chance I'll be building a house again soon, and I have wondered about reducing sound between the 1st floor & 2nd floor in general. In my current basement, I actually did clips & channel & pink fluffy insulation everywhere, and it definitely helps a lot vs my prior basement where I did nothing. So, you could do clips & channels, but single DW layer. The other option I wondered about, is doing multiple layers of OSB sub-floor, with Green Glue in between. So, as the build the 2nd floor, the first thing they do is really put down a subfloor, and potentially do 2 or 3 layers of sub-floor, before the build the walls on top. Kind of like the GG/DW/GG/DW on the sub-floor, but with perfect coverage (vs having to work around things). No idea how much that would cost.

My generic thought would be if you do the GG/DW/GG/DW on the subfloor, I would probably skip the Triple DW on the ceiling and stick with Double. In my theater, my 'walls' were done with my first layer of OSB, which I think attaching columns to and stuff is a lot easier that way. My ceiling I did two layers of DW, except where the projector mounts, where I did a sheet of Plywood. A page or so back there was a brief discussion on this, if I do it again, I'll probably try my first ceiling layer with Plywood/ OSB, but HTGeek would probably not do it again.


----------



## ncabw

So here is what I'm going to do for that return air problem. I'm going to us the "soundboard" above the Joist in full strips and then below the joist with strips that will go between the furring channel. This wai i will have 100% seal for the duct and extra soundproofing with the 2 layers. I will use joist PL and screws to fasten to the joist.

so in that section i will now have a sandwich that looks like this from the top of the Ijoist below the 1st floor subfloor

GG
5/8 DW
GG
5/8 DD

soundboard
2" i joist wood
sound board

then clips
furring channel

5/8 DW
GG
5/8 DW


I think this is best i can do


----------



## HT Geek

ncabw said:


> Won't the sound go right through the house with them open. Maybe not furnace is in basement so sound might only go back to the mechanical room? Then maybe same if I just cut a register into the main return air duct?
> 
> My original thought was that sound would go through the ductwork throughout the house.


I was thinking of it from not only a HT perspective but also an environmental perspective. Joist-as-duct return systems are notorious for air leakage.

You could leave it as-is as you are thinking and seal it with drywall. If your HT room's ceiling is attached directly to the floor joists of the room above, it won't matter anyway from a sound-proofing standpoint. OTOH, if your ceiling is de-coupled from the floor above, you don't want to re-couple it.


----------



## HT Geek

GatorBlues said:


> In response to both of your posts:
> 
> First and foremost, thank you very much for your advice.
> 
> We have the extra height at the front of the theater because the builder is digging the theater room 16 inches deeper than the rest of the basement. We will walk in level with the other rooms, and then take two steps down to the front row.
> 
> Based on your advice, adding separate ceiling joists, parallel to the floor joists and attached to the second set of interior studs, is almost certainly what I'll have the builder do. Should I have him dig the room even deeper or does 10.5 and 9 feet sound like good heights for a 22 by 18 room (post finishing measurements)? I don't want it to feel cramped.


I don't think so unless you are 7' tall or so, you won't. 

My HT ceiling is 7' under the soffit where the riser is. That feels a bit crammed in the rear, and it's a rear-entry room. It's not terrible but definitely noticeable. The main ceiling is 8', which I find fine (and prolly what I'd call a minimum height personally). I am 6' 0" tall, for reference.

Also consider whether you will have a soffit or might decide later on to have one built. They are great hiding things such as your HVAC ducts, running wires, etc. But since you are building the whole house from scratch, you have good alternatives. If the builder is willing to work with you (it sounds like they are), you can easily make arrangements for various features such as running conduit, extra electrical runs, etc. while the home is being built.

One item I would strongly suggest is to have at least two 20-amp circuits run to your HT room. One for your primary A/V equipment where the circuit terminates there. The other to handle your HT room lighting and act as a secondary power source for your A/V rack. This is a controversial topic and many people on AVS will tell you that's overkill. Personally, I favor over-building in situations where you are starting from scratch. It's much easier to add one extra circuit now - at very little cost - compared with retrofitting another circuit if you decide to add 4 monster subs to your HT room in the future with big amps powering each. Or some other potentially large amp-drawing devices. You might even be fine with that scenario on 1 circuit. These days most A/V equipment does not draw that much current _most of the time_. I stress that last part because it's not uncommon for certain devices to spike when they are turned on or when taxed heavily. Amps are certainly in that category. Most modern amps solve this problem by storing or buffering power so when they require a burst, it's right there. That design also reduces lag from input to output. However, it is possible for devices to run low and have to tap a higher amperage directly from the power source.

I prefer to err on the side of overkill, especially when your cost will be minimal. $200-300 or so. The electrician will already be in there anyway. What's an extra line?

Another thought for you on electrical... seriously consider installing a whole-house circuit breaker like this one from Leviton. Even better is the new line of whole house surge protectors from Intermatic, such as the IG2240-IMS. What I really like about the Intermatic line is you can easily replace the modules. With the Leviton, it's a more complicated replacement process if it gets fried (i.e. you'll need an electrician).

I have seen lightning strikes take out these boxes save a homeowner tens of thousands of $ in repairs. They really work. If there is a failure, you still have power going through, you just lose the circuit protection. There is an indicator light on all of these devices (normally green = good and red or blank = it's fried). Of course, I'm sure you have insurance. So do I. But dealing with the hassle and paying the deductible also sucks. And in a worst-case scenario, your house could catch on fire. Food for thought. I know you're trying to save money, so I'm sorry that I keep suggesting ways to spend it. 

One more idea on this subject... consider investing in a smaller type surge protection unit for your A/V equipment. Surges can occur from within the house as well. The whole house surge protectors only protect you from line voltage spikes. That is, only if the spike enters your home via the power company's cables. As odd as it sounds, intra-house spikes are more common than most people realize. A few months ago, my next door neighbor's house was hit by lightning. It blew his pool equipment panel off the wall and fried all the pool equipment. It also blew every GFCI circuit in his house and did some other damage (>$40k). My house was affected as well. The surge hit along the wall that faces my neighbor's home. My hot tub, my home office, alarm system, home network, a bunch of other stuff... zapped. Yet my home was not physically damaged from the outside at all. Even though I had surge protectors on them, the lightning energized the electrical wires in my home's wall. I'm very lucky that none of my A/V equipment was hooked up at the time. It even energized the CAT5 cables on my home network, which is how my home office computer and printer got fried. 

It's worth discussing with your builder. There are a variety of products on the market. Some are easier than others to replace. No need to spend more than $200-300 max if you just focus on a surge protector for the A/V rack. Food for thought. 




> We will carpet the floor in the theater. The adjoining rooms are the kids' playroom (carpet) and our bar/sitting room (tile). I'm relieved to know that I don't have to add even more expense to the theater floor to deal with LFE issues. This house is getting expensive, and the theater (based on my choices) is only a fraction of the cost overruns we have added (based on my wife's choices).


You might feel some LFE (possibly) in the bar/sitting room with tile. Even if you do, it would be minor and I doubt most people would notice. If it bothers you, put down a rug. 




> Do you know off the top of your head what would be the ballpark cost to install double drywall and green glue up against the floor above between the ceiling joists, as has been suggested to me in another thread, and how much benefit that would provide? Again, the room will be 23 by 19 prior to the second set of studs being added for room within a room.


Ballpark $1,200. It would be more labor intensive compared with slapping up drywall normally. Of course, there's no need to mud and tape it, but the installers will probably have to jury-rig supports to screw the drywall into (scrap wood perhaps). If you insist they caulk the seams and ensure there are no gaps, plan on spending another 10-20% for caulk and labor. Someone would need to cut the drywall strips to fit between the floor joists. The minimum recommended application of Green Glue is 1 tube per 4x8 sheet drywall sandwich. With perfect use of materials and no waste, you're looking at ~$1.35 to $1.50 per square foot in materials. To account for waste and keep it simple I'd just take your room size and add 10%. So, that's (23x19) x 1.1 = 481. $650-720 for parts. I'm gonna guess you get quoted about $500 for labor (2 guys, 4-6 hours).

I'm on the fence over that concept myself. You'd think it would create a triple-leaf effect (HT ceiling > DW between floor joists > Floor above). 

I would be inclined to add a 3rd layer of drywall on the ceiling in your HT room. Another option is raise your floor height in the level above just a bit. This is easy if the house is built this way. Ideally do something on the floor above such as Sub-floor > 3/8" or 1/2" Rubber Mat > Sub-floor. You'd have a rock solid floor and it would help not only from the HT room below, but you'll likely never hear foot traffic from above when you are anywhere in the basement (even if your finished floor is tile). The big cost on that approach would be the rubber mat, though I'm sure you could get a healthy discount if you were buying 2-3,000 sq. ft. of it. 

Or Plan C: double up the sub-floor on main level and use 3 layers of drywall/GG on the HT room ceiling. You could (and should) still put insulation between the floor joists above the HT room.

If you seriously think you want to do DD between the studs, I would consult with one or more of the audio experts on this forum first (e.g. Ethan, Nyal, Dennis, Mike Bravo, etc.).




> On an unrelated note, what's the most cost effective way to reduce sound between floors for the non-theater rooms? Is it a good idea to stuff pink fluffy between each floor throughout the house?


That will definitely help. Should lower your utility bills a bit as well. The insulation will be better for blocking out higher frequencies (mids and highs), such as human voices.




> Is there something else that should be done also, or instead, to dampen the sound between floors in the rooms getting normal day to day use?


As mentioned above, double up the sub-floor and put a rubber mat in between is one option. An even better one now that I think about it... double sub-floor with rubber mat underlayment sandwich... but put the whole thing on U-boats (U-shaped hard rubber de-couplers that fit over joists upside down). This would "float" your floors off the joists. That would be a fantastic solution altogether.




> You suggested triple drywall with GG on the ceiling. Would it make sense to do the layers as (1) drywall, then GG, (2) OSB, then GG, and (3) drywall again, so that I can attach on ceiling lights (no cans; too much sound leak), atmos speaker mounts, and a projector into the ceiling?


Yes, that would work. Using a layer of OSB also provides a very slight advantage because every material has a natural resonance. OSB's is different than drywall's, so it means they will cancel out each other's resonance to some extent (by making the dw/osb sandwich as you suggested). I did something similar in my theater. I used OSB as 1st layer then 2 layers of DW with GG between everything. The OSB is a hassle. But if you are paying someone to do it, I say go for it.




> Our plan is still only a sketch. I've gotten lots of helpful advice from kmhvball in his Cinema-Nati theater build thread (he successfully put 3 rows, with the last one being a small counter, into his room that is only slightly longer than mine), and from him and others (BigMouthinDC and thrillcat chief among them) in my Spinal Tap Theater build thread. I'm trying to get educated and understand the big picture ideas before drawing a final plan. The posters on this site, you included, are the most helpful group of strangers I've ever encountered.
> 
> Thank you again for all of your help.


Glad you've been communicating with those folks as well. They're all very knowledgeable. Big in particular has the most varied real-world experience, so I would trust his advice more than anyone else's (including me)!

You are wise to go about the build as you are. Lots of planning. And you have a huge advantage by virtue of being new construction.

Dave


----------



## HT Geek

kmhvball said:


> .... So, as the build the 2nd floor, the first thing they do is really put down a subfloor, and potentially do 2 or 3 layers of sub-floor, before the build the walls on top. Kind of like the GG/DW/GG/DW on the sub-floor, but with perfect coverage (vs having to work around things). No idea how much that would cost.
> 
> My generic thought would be if you do the GG/DW/GG/DW on the subfloor, I would probably skip the Triple DW on the ceiling and stick with Double. In my theater, my 'walls' were done with my first layer of OSB, which I think attaching columns to and stuff is a lot easier that way. My ceiling I did two layers of DW, except where the projector mounts, where I did a sheet of Plywood. A page or so back there was a brief discussion on this, if I do it again, I'll probably try my first ceiling layer with Plywood/ OSB,


Another good idea ^. I agree I really like the idea of beefing up the entire floor above the HT room versus trying to shove a bunch of stuff in the ceiling above the HT. It's something you can only do when you're building the house and it will pay off in more ways than one. But kmhvball's got a good idea with GG in between the layers. I think that or the rubber mat idea would work well. Not sure which would work better. GG version takes up less space. I'll just add that per my last post, if you can I would do the U-boats on the studs, then the sub-flooring, etc. I don't know enough about the U-boats to understand how the sub-floor would be secured to the floor joists. That could be a fly-in-the-ointment. If it's something klugey, the building inspector might not allow it (and you might not want it). Something to consider.

In my HT room, on top of the original sub-floor I added a OSB/GG/Rubber Mat/GG/OSB sandwich. I then built the interior wall on top of that surface. So, in my case it's a 2nd floor theater above the garage. What I did helps a lot, but I can still hear and feel (when not on the riser) my garage door openers. Very annoying to me. If I were to do it over again, I would rip out the original sub-floor and put down the U-boats, then do my floor sandwich. 




> but HTGeek would probably not do it again.


Yep! True!


----------



## ncabw

Man the more I read about soundproofing it seems like so much can go wrong. Lol.


----------



## HT Geek

ncabw said:


> So here is what I'm going to do for that return air problem. I'm going to us the "soundboard" above the Joist in full strips and then below the joist with strips that will go between the furring channel. This wai i will have 100% seal for the duct and extra soundproofing with the 2 layers. I will use joist PL and screws to fasten to the joist.
> 
> so in that section i will now have a sandwich that looks like this from the top of the Ijoist below the 1st floor subfloor
> 
> GG
> 5/8 DW
> GG
> 5/8 DD
> 
> soundboard
> 2" i joist wood
> sound board
> 
> then clips
> furring channel
> 
> 5/8 DW
> GG
> 5/8 DW
> 
> 
> I think this is best i can do


Can we back-up a bit? I'm a little confused. I am not grasping the total picture for your situation.

What is your current framing in your HT room? If you have access above the joist ducts, how is that possible if they are joist ducts? Do you have a floating ceiling in your HT room?


----------



## ncabw

I will send a picture later today but right now I have the following 

from my joists I have used the clips and furring channel for decoupling. 

The way the returns were suppose to work was my drywall was to be screwed right into the joist. This would create the seal for the return run. There is no duck in between the joist. They just use the joist space as the run. 

Since we decoupled the ceiling I have that 1/2" gap from the clip plus whatever the furring channel is. 

Without the prober seal the return would end up sucking the whole theatre room.


----------



## RustyMon

A warm hello to all the soundproofers - I've truly appreciated all the info on this site and am now about ready to begin my build... but before I do, I have some questions that I didn't find answers to elsewhere...

I'm planning to do a room within in a room decoupling inside a crawl space with concrete slab floor. Kids bedrooms are upstairs. My questions are as follows:

1) I am planning of floating new joists between existing joists. I've seen some folks build their new ceiling height 1" below the joists. Any reason to go that far? What if I just go 1/4"-1/2" below? Does that reduce effectiveness or cause issues?

2) I was planning to go OSB/D/D on the ceiling with GG in between each layer. I know the third layer may provide diminishing returns, but figured I'd prefer to go all out. (also planning on doing the two layers of drywall between joists w/ GG below first floor). Any reason to NOT do the extra layer or the OSB first layer?

3) As the floating joists will rise into the cavity of the existing joists, is it a problem if the insulation rests on the new joist (I.E. does this ruin the decoupled structure)? I'm assuming the answer is NO, that this would be acceptable. 

I look forward to your shared wisdom!


----------



## LoudDad

It's ok to leave less than a 1" gap. The only thing you need to watch for is boards twisting or moving as they dry. You don't want them to end up touching the existing structure. So I'd go with a 1/2" but probably not less.
As you already know, third layer of drywall is diminishing returns. The only negatives are extra cost and you lose 5/8" of ceiling height.
I think it's ok if the insulation touches but don't totally pack it in.

Bill


----------



## ncabw

Is there special electrical boxes for plugs and switches for decoupled walls that I'm suppose to use with my setup? Steel stud with decoupled with clips and channel. Then addicting 2 lawyers of 5/8 DD. 

All I've found so far was puddy to go around the boxes for sound. 

Wouldn't attaching the electrical box to the stud defeat the decoupling of the wall?


----------



## RustyMon

Yes, do not attach electrical boxes to your studs, rather use "remodel" boxes - they have tabs that pop out after you insert them into the wall. Pretty much any hardware store will carry them.


----------



## ncabw

HT Geek said:


> Can we back-up a bit? I'm a little confused. I am not grasping the total picture for your situation.
> 
> What is your current framing in your HT room? If you have access above the joist ducts, how is that possible if they are joist ducts? Do you have a floating ceiling in your HT room?




Here is a pic and some sketches of what I'm planning on doing. 

As you can see i have decoupled the ceiling form the Joist. Once i did that i lose my seal that the drywall was suppose to create by being screwed right into the joist. So on the one sketch you can see 3-6 joist spaces are for returns. I cant insulate those runs.

I plan on adding 2 pieces of sound board. One that runs with the joist in between the I's and then cut strips to run between the furring channel. I've decide to do both ways because i was short 8" and need to buy 2 sheets. so figured this might be better for soundproofing. I might also add in some insulation between the 2 sound board where i have that 2" gap


----------



## ncabw

RustyMon said:


> Yes, do not attach electrical boxes to your studs, rather use "remodel" boxes - they have tabs that pop out after you insert them into the wall. Pretty much any hardware store will carry them.


Will this work? I'm pretty sure by code that i can't have the box floating just in the middle of the DW.

I was also thinking maybe just for inspection fastening the box to the stud like normal then after doing what you suggested. This house is a new build so i still have one more electrical inspection left.


----------



## Ladeback

ncabw said:


> Will this work? I'm pretty sure by code that i can't have the box floating just in the middle of the DW.
> 
> I was also thinking maybe just for inspection fastening the box to the stud like normal then after doing what you suggested. This house is a new build so i still have one more electrical inspection left.


I would check your code to see what you can use. I didn't decouple the walls so I am using adjustable boxes like these so I can at least do more then one layer of drywall.

http://www.homedepot.com/p/1-Gang-2...with-Adjustable-Bracket-B121ADJ-40R/202077339


----------



## RustyMon

Question regarding a ceiling for room in a room...
Is it better to build the ceiling to flex more (build 24" on center with minimum lumber size for span) or flex less (overbuild with heavier lumber and 16" on center)?


----------



## Ben L Walker

Hello all,

I have started working on my new home theater and am in the framing process now. I am de-coupling all of the walls with IB-3 brackets (the rear wall and right wall are built about 1 inch out from the foundation walls, the screen wall will be framed 1" from an existing wall that is shared with a bedroom on the other side, and the left wall is framed with a 36" gap between walls. The room is 28'7" X 17'3" between studs. I have been working with Ted at The Soundproofing Company but my questions for the forum are these-

In the 36" cavity between walls on the left wall ( in green), I'm told that since the gap is so large (to avoid having a huge soffit in the room) then the double wall is rendered ineffective, so I will need to clip and channel that wall. If it is clipped and channeled, with DD and GG, then am I free to sheetrock that space between walls and use it for something like movie storage shelving etc? Or will that cavity, if finished, create a sound issue? (I'm thinking echoing or reverb etc...)

I am planning a similar (although much smaller) space behind my AV rack. Same questions there...

On the rear wall, (pictured with the ladder leaning against it), if it is built with space between the concrete foundation, but is touching the insulation and vapor barrier, will that compromise the decoupling? 

On the screen wall, the existing wall is already drywalled with 1/2 drywall on both sides with no insulation. Can I just build my decoupled wall in front of it and then add insulation and DD+GG to that wall or do I need to pull off the existing drywall and insulate the existing wall too?

Any help is appreciated.


----------



## Ladeback

Ben L Walker said:


> Hello all,
> 
> I have started working on my new home theater and am in the framing process now. I am de-coupling all of the walls with IB-3 brackets (the rear wall and right wall are built about 1 inch out from the foundation walls, the screen wall will be framed 1" from an existing wall that is shared with a bedroom on the other side, and the left wall is framed with a 36" gap between walls. The room is 28'7" X 17'3" between studs. I have been working with Ted at The Soundproofing Company but my questions for the forum are these-
> 
> In the 36" cavity between walls on the left wall ( in green), I'm told that since the gap is so large (to avoid having a huge soffit in the room) then the double wall is rendered ineffective, so I will need to clip and channel that wall. If it is clipped and channeled, with DD and GG, then am I free to sheetrock that space between walls and use it for something like movie storage shelving etc? Or will that cavity, if finished, create a sound issue? (I'm thinking echoing or reverb etc...)
> 
> I am planning a similar (although much smaller) space behind my AV rack. Same questions there...
> 
> On the rear wall, (pictured with the ladder leaning against it), if it is built with space between the concrete foundation, but is touching the insulation and vapor barrier, will that compromise the decoupling?
> 
> On the screen wall, the existing wall is already drywalled with 1/2 drywall on both sides with no insulation. Can I just build my decoupled wall in front of it and then add insulation and DD+GG to that wall or do I need to pull off the existing drywall and insulate the existing wall too?
> 
> Any help is appreciated.


I am no expert and I am sure if I am wrong I will get corrected, but for your screen wall you could either build a new wall in front of the old one and use the IB-3 clips and build it like the others with insulation DD+GG or you could use clips and hat channel on the existing wall with DD+GG. Not sure which one is cheaper, but the clips and hat channel is less work.

As for the wall with you 3' space, if you don't want sound to go up I was told you need to decouple it like you are the others or do like I mentioned on the screen wall and use clips and hat channel.

I forgot about the IB-3 clips and wish I would have used them in my build. but I not to worried about sound going up, because it is my kitchen and living room and if I watching a movie my wife will probably be with me so no complaints. I am only going to use clips and channel on my ceiling then DD+GG all the way around.

I hope that helps.


----------



## Ben L Walker

Ladeback said:


> I am no expert and I am sure if I am wrong I will get corrected, but for your screen wall you could either build a new wall in front of the old one and use the IB-3 clips and build it like the others with insulation DD+GG or you could use clips and hat channel on the existing wall with DD+GG. Not sure which one is cheaper, but the clips and hat channel is less work.
> 
> As for the wall with you 3' space, if you don't want sound to go up I was told you need to decouple it like you are the others or do like I mentioned on the screen wall and use clips and hat channel.
> 
> I forgot about the IB-3 clips and wish I would have used them in my build. but I not to worried about sound going up, because it is my kitchen and living room and if I watching a movie my wife will probably be with me so no complaints. I am only going to use clips and channel on my ceiling then DD+GG all the way around.
> 
> I hope that helps.


Thanks for the reply. On the 3' space, I will have that wall decoupled with IB-3 as well. 

On the screen wall, I'm going to be putting up a double wall with the IB-3s, DD+GG, but I'd rather not have to pull down the existing drywall off of the existing wall if it isn't going to cause a problem to leave it up. 

Would you pull it down or not worry about it?


----------



## Ladeback

Ben L Walker said:


> Thanks for the reply. On the 3' space, I will have that wall decoupled with IB-3 as well.
> 
> On the screen wall, I'm going to be putting up a double wall with the IB-3s, DD+GG, but I'd rather not have to pull down the existing drywall off of the existing wall if it isn't going to cause a problem to leave it up.
> 
> Would you pull it down or not worry about it?


I wouldn't worry about it if you are building a wall in front of it. How much of a gap will you have between the two. I would have at least and inch. That would I think act like a double wall. Is the screen wall an out side wall? Does it have any insulation in it?


----------



## Ben L Walker

Ladeback said:


> I wouldn't worry about it if you are building a wall in front of it. How much of a gap will you have between the two. I would have at least and inch. That would I think act like a double wall. Is the screen wall an out side wall? Does it have any insulation in it?


The screen wall is an interior wall with no insulation. I plan on having a 1" gap between walls.


----------



## RustyMon

RustyMon said:


> Question regarding a ceiling for room in a room...
> Is it better to build the ceiling to flex more (build 24" on center with minimum lumber size for span) or flex less (overbuild with heavier lumber and 16" on center)?


Think I finally found an answer to this question... thought I'd share here for others to find... quoted from Ted White on another thread:
----------------------------------------------------------------
The 24" introduces some flex. Also reduces contact surface area = less physical conduction. Both assist in transmission loss

In double or staggered walls, stud spacing makes no difference.

Also, the difference between 16" and 24" on a single stud wall are significant.

STC 36 vs STC 45 looking at a steel stud wall.

BTW a steel stud wall will get a few points over a wood stud (in a single stud comparison) due to the flex.
----------------------------------------------------------------

So, as I'm building a room within a room, it shouldn't make a difference.


----------



## Emaych

Anyone know anything about the efficacy of decorative stone facing on the outside stucco? Am not going to do anything more with the inside, or from the inside, my last hope is that adding a two inch layer of solid stone might work -- won't dampen whatever traffic noise comes through the ceiling, but is it generally pretty effective?


----------



## Vince_B

RustyMon said:


> Think I finally found an answer to this question... thought I'd share here for others to find... quoted from Ted White on another thread:
> ----------------------------------------------------------------
> The 24" introduces some flex. Also reduces contact surface area = less physical conduction. Both assist in transmission loss
> 
> In double or staggered walls, stud spacing makes no difference.
> 
> Also, the difference between 16" and 24" on a single stud wall are significant.
> 
> STC 36 vs STC 45 looking at a steel stud wall.
> 
> BTW a steel stud wall will get a few points over a wood stud (in a single stud comparison) due to the flex.
> ----------------------------------------------------------------
> 
> So, as I'm building a room within a room, it shouldn't make a difference.


I was wondering this today too, thanks for posting the answer!

Sent from my SM-N910V using Tapatalk


----------



## HT Geek

ncabw said:


> Will this work? I'm pretty sure by code that i can't have the box floating just in the middle of the DW.
> 
> I was also thinking maybe just for inspection fastening the box to the stud like normal then after doing what you suggested. This house is a new build so i still have one more electrical inspection left.


I don't know what an "1104" box is the drawing, but to answer your question: Yes, you can certainly have an electrical junction box that is NOT attached to a stud. That's a 'remodel' box type. Non-issue and it IS code compliant provided you observe other related codes. One of the most important is the wire must be secured within either 8" or 12" of the box, depending on a couple of details that escape my memory atm. IMO secure the romex wire within 8" of the box.

Note: if your stud is >6" or so away from the box, it won't be possible to meet that code requirement with a stud. If that's the case, you will either need to move the remodel box closer to the stud or (preferably) use a box with clips that hold the wires securely as they enter the box. That puts your 'securing' of the wire at 0". Many of the home improvement stores have stopped carrying those boxes in favor of the ones with break-away tabs. Those won't be code compliant if the box is too far from being secured to a stud. At least if you have a picky inspector.

Btw, the entire point of all this (in case you're wondering) is to prevent a) loose wires from coming out of the box; and b) prevent any accidental tugging on the wires inside the wall that might loosen the wires in the box.

Hope that helps.


----------



## HT Geek

ncabw said:


> Here is a pic and some sketches of what I'm planning on doing.
> 
> As you can see i have decoupled the ceiling form the Joist. Once i did that i lose my seal that the drywall was suppose to create by being screwed right into the joist. So on the one sketch you can see 3-6 joist spaces are for returns. I cant insulate those runs.
> 
> I plan on adding 2 pieces of sound board. One that runs with the joist in between the I's and then cut strips to run between the furring channel. I've decide to do both ways because i was short 8" and need to buy 2 sheets. so figured this might be better for soundproofing. I might also add in some insulation between the 2 sound board where i have that 2" gap


Now that makes sense to me. I didn't realize you were using clips & channel. So, you're just trying to insulate between the joists (if I now understand correctly). In that case, I would not be too concerned with those joist ducts. There's a chance you could have a triple-leaf effect but not much you can do about it other than your plan, which appears good to me.


----------



## HT Geek

ncabw said:


> Is there special electrical boxes for plugs and switches for decoupled walls that I'm suppose to use with my setup? Steel stud with decoupled with clips and channel. Then addicting 2 lawyers of 5/8 DD.
> 
> All I've found so far was puddy to go around the boxes for sound.
> 
> Wouldn't attaching the electrical box to the stud defeat the decoupling of the wall?


Use the putty all around the box (inside the wall) to plug any holes for sound.

IMO, I don't believe it matters if you use new construction (attached to stud) or remodel boxes. Others' opinions will vary, but fact is you are making the same size hole either way.


----------



## HT Geek

RustyMon said:


> Question regarding a ceiling for room in a room...
> Is it better to build the ceiling to flex more (build 24" on center with minimum lumber size for span) or flex less (overbuild with heavier lumber and 16" on center)?


Other than Vince's comments ^above^, if you want less ceiling deflection, you need to change one of the following:

1. Reduce load (weight) supported by the ceiling joists
2. Increase load carrying ability of ceiling joists
3. Decrease your joist span

Regardless, you should run engineering calculations to determine the relationship between your ceiling joists, maximum permitted deflection, anticipated deflection based on anticipated load, and maximum load.


----------



## HT Geek

Ladeback said:


> I would check your code to see what you can use. I didn't decouple the walls so I am using adjustable boxes like these so I can at least do more then one layer of drywall.


To Ladeback's point, I have yet to see a remodel box that allows >1 layer of drywall. One could possibly jury-rig one by using longer screws.


----------



## HT Geek

Ben L Walker said:


> In the 36" cavity between walls on the left wall ( in green), I'm told that since the gap is so large (to avoid having a huge soffit in the room) then the double wall is rendered ineffective, so I will need to clip and channel that wall. If it is clipped and channeled, with DD and GG, then am I free to sheetrock that space between walls and use it for something like movie storage shelving etc? Or will that cavity, if finished, create a sound issue? (I'm thinking echoing or reverb etc...)


That's going to be a nice room you have there. 

You need to clarify what you mean by, "double wall." When I hear that term in AVS context, I think of a double-stud wall. However, I don't see that in your photos. Is your plan to create a double stud wall? What is your overall plan for the whole room's walls and ceiling? In your photos your walls are connected directly to the floor joists above, and the floor joists above are acting as your ceiling joists.

Short answer regardless of your responses is depends on your room design. Think of everything inside your sound-proofed shell as what needs to be contained within clip & channel or double stud wall, etc. If you intend to use that 36" 'corridor' (for lack of a better term atm) for movie storage, will you want to access it from the room? Or put another way, from inside or outside of the sound-proofed shell? The difference will dictate how you build your doors, walls, etc.

BTW, you have an excellent opportunity here for a double-door system if you do NOT put the movie storage room inside the HT shell.




> I am planning a similar (although much smaller) space behind my AV rack. Same questions there...


Same issues/questions apply. Does that space need to (or do you want it be) sound proofed?

You may find that it's easier to soundproof everything from a labor perspective (or the opposite may be true).




> On the rear wall, (pictured with the ladder leaning against it), if it is built with space between the concrete foundation, but is touching the insulation and vapor barrier, will that compromise the decoupling?


Effectively, no. I wouldn't worry about that unless the insulation and/or vapor barrier were compressed against the concrete. And even if that's the case, you'll have more of an issue with echo/reverberation back into the room from that concrete wall than you will with sound through it unless it's very thin... and if it's a foundation that won't be the case of course.




> On the screen wall, the existing wall is already drywalled with 1/2 drywall on both sides with no insulation. Can I just build my decoupled wall in front of it and then add insulation and DD+GG to that wall or do I need to pull off the existing drywall and insulate the existing wall too?


No. If you do clips & channel on that wall then you DO need to demo the HT side of the wall. Otherwise you're going to create a triple-leaf effect (other side of stud drywall + HT room side of stud drywall + drywall on clips & channel). If that screen wall has the bedroom on the other side of it, you'll want either clips & channel, staggered stud, or a double stud wall on the HT side. Any of those choices will necessitate demo'ing the wall on the HT side. I would also recommend doubling up the drywall on the other side if it's a bedroom.


----------



## HT Geek

*Careful!*



Ben L Walker said:


> Thanks for the reply. On the 3' space, I will have that wall decoupled with IB-3 as well.
> 
> On the screen wall, I'm going to be putting up a double wall with the IB-3s, DD+GG, but I'd rather not have to pull down the existing drywall off of the existing wall if it isn't going to cause a problem to leave it up.
> 
> Would you pull it down or not worry about it?





Ladeback said:


> I wouldn't worry about it if you are building a wall in front of it. How much of a gap will you have between the two. I would have at least and inch. That would I think act like a double wall. Is the screen wall an out side wall? Does it have any insulation in it?


You guys need to be careful so that a triple-leaf effect is not created. A triple leaf is when you have 3 walls in close proximity that create 2 independent air gaps. Sound will get amplified as it passes through the 2nd chamber and bounces between its walls before reverberating out of the 3rd wall. 

So, don't create this:

| gap | gap ||

What you want instead is this:

| gap ||

Put another way, this is OK:

{DW}{Stud}{DW}{DW}

OR

{DW}{Stud}{Clip}{DW}{DW}

But not:

{DW}{Stud}{DW}{Stud}{DW}

nor:

{DW}{Stud}*{DW}*{Clip}{DW}{DW}


Bottom line: Clips must be attached to studs.


----------



## HT Geek

Emaych said:


> Anyone know anything about the efficacy of decorative stone facing on the outside stucco? Am not going to do anything more with the inside, or from the inside, my last hope is that adding a two inch layer of solid stone might work -- won't dampen whatever traffic noise comes through the ceiling, but is it generally pretty effective?


Don't know the answer to your question, but more mass will help with damping.

If you're thinking of putting that on your ceiling, make sure your ceiling joists can support the weight.


----------



## Ben L Walker

HT Geek said:


> You guys need to be careful so that a triple-leaf effect is not created. A triple leaf is when you have 3 walls in close proximity that create 2 independent air gaps. Sound will get amplified as it passes through the 2nd chamber and bounces between its walls before reverberating out of the 3rd wall.
> 
> So, don't create this:
> 
> | gap | gap ||
> 
> What you want instead is this:
> 
> | gap ||
> 
> Put another way, this is OK:
> 
> {DW}{Stud}{DW}{DW}
> 
> OR
> 
> {DW}{Stud}{Clip}{DW}{DW}
> 
> But not:
> 
> {DW}{Stud}{DW}{Stud}{DW}
> 
> nor:
> 
> {DW}{Stud}*{DW}*{Clip}{DW}{DW}
> 
> 
> Bottom line: Clips must be attached to studs.


Thanks for the reply. On the screen wall I am going to go ahead and pull won the existing DW. Here is hoe that wall will go {DW}{STUDS W/R13} 1" GAP {STUDS W/R13}{DD/GG}. Does that sound correct?

On the 36" wall, it will go like this:

{DW}{STUDS W/R13} 36" SPACE {DW}{STUDS W/R13}{CLIPS & CHANNEL}{DD/GG}

I am looking at the 36" space as being similar to a hallway. That shouldn't create a triple leaf effect here, correct?

Finally, on the remaining two walls, they will be like this:

{CONCRETE FOUNDATION WALL} 1" GAP {STUDS W/R13}{DD/GG}

All of the interior walls will be decoupled from the joists with the IB-3 brackets.

Do you see any issues here?

Thanks in advance


----------



## Ben L Walker

HT Geek said:


> That's going to be a nice room you have there.
> 
> You need to clarify what you mean by, "double wall." When I hear that term in AVS context, I think of a double-stud wall. However, I don't see that in your photos. Is your plan to create a double stud wall? What is your overall plan for the whole room's walls and ceiling? In your photos your walls are connected directly to the floor joists above, and the floor joists above are acting as your ceiling joists.


Sorry, Yes I mean a double-stud wall. I have not built the double-stud wall on the screen wall or the left wall yet. I have the IB-3 clips coming on Thursday which is why the rear wall is leaning and not secured in place yet, and the right wall is being held up by some temporary blocking across the top. I'll update with new pics when I have made more progress. (I'd like to do it this weekend but with the Sundance Film Festival in town, I will be preoccupied. 



HT Geek said:


> Short answer regardless of your responses is depends on your room design. Think of everything inside your sound-proofed shell as what needs to be contained within clip & channel or double stud wall, etc. If you intend to use that 36" 'corridor' (for lack of a better term atm) for movie storage, will you want to access it from the room? Or put another way, from inside or outside of the sound-proofed shell? The difference will dictate how you build your doors, walls, etc.


The entrance to the storage area will be outside of the soundproof envelope, as well as the AV rack and the AV rack access. 



HT Geek said:


> BTW, you have an excellent opportunity here for a double-door system if you do NOT put the movie storage room inside the HT shell.


I have thought about that, but the Mrs. isn't sold on that yet. I still could even with the storage access if one door swung into the theater and the other swung into the adjacent room, right?


----------



## Ladeback

HT Geek said:


> You guys need to be careful so that a triple-leaf effect is not created. A triple leaf is when you have 3 walls in close proximity that create 2 independent air gaps. Sound will get amplified as it passes through the 2nd chamber and bounces between its walls before reverberating out of the 3rd wall.
> 
> So, don't create this:
> 
> | gap | gap ||
> 
> What you want instead is this:
> 
> | gap ||
> 
> Put another way, this is OK:
> 
> {DW}{Stud}{DW}{DW}
> 
> OR
> 
> {DW}{Stud}{Clip}{DW}{DW}
> 
> But not:
> 
> {DW}{Stud}{DW}{Stud}{DW}
> 
> nor:
> 
> {DW}{Stud}*{DW}*{Clip}{DW}{DW}
> 
> 
> Bottom line: Clips must be attached to studs.


 @HT Geek,

I am thinking of a building another wall in front of my current screen wall that is just a stud wall that has about 5.5" air gap between the back of the stud and 1" foam that is on concrete wall. The reason for the other wall is to bring it out so I can build shelves under my screen for the center channel, PS3 and pre-build places to add more subs in the future. Two subs is not enough, right? 

I am using Klipsch KPS-400's for my front's that have built in subs. I was going to have them out in the room or should I build out angles walls on the edge of my screen and hide the speakers? Not sure what it would sound like if I put them behind a false wall vs leaving them out in the room. The built in subs will fire at the adjacent wall, what do I need to do to control the bass vibration? Build trap above in the corners?


----------



## HT Geek

Ladeback said:


> @HT Geek,
> 
> I am thinking of a building another wall in front of my current screen wall that is just a stud wall that has about 5.5" air gap between the back of the stud and 1" foam that is on concrete wall. The reason for the other wall is to bring it out so I can build shelves under my screen for the center channel, PS3 and pre-build places to add more subs in the future. Two subs is not enough, right?
> 
> I am using Klipsch KPS-400's for my front's that have built in subs. I was going to have them out in the room or should I build out angles walls on the edge of my screen and hide the speakers? Not sure what it would sound like if I put them behind a false wall vs leaving them out in the room. The built in subs will fire at the adjacent wall, what do I need to do to control the bass vibration? Build trap above in the corners?


Hate to say it but that is a loaded question. 

It's mostly personal preference (how many subs, where to place your speakers) and in terms of controlling bass, that has a lot to do with your room acoustics. Your best bet is going to be place everything where you'd like it to be and run REW tests to see what issues you have. Then you can determine the best method of controlling them, based again on your preferences. As a general guideline, I'd say you'll want to use wall treatments on your side walls up to ear level anyway. With your speakers pointed at opposite walls, you will likely need/want more damping in those locations to control 1st reflections.


----------



## HT Geek

Ben L Walker said:


> Thanks for the reply. On the screen wall I am going to go ahead and pull won the existing DW. Here is hoe that wall will go {DW}{STUDS W/R13} 1" GAP {STUDS W/R13}{DD/GG}. Does that sound correct?
> 
> On the 36" wall, it will go like this:
> 
> {DW}{STUDS W/R13} 36" SPACE {DW}{STUDS W/R13}{CLIPS & CHANNEL}{DD/GG}
> 
> I am looking at the 36" space as being similar to a hallway. That shouldn't create a triple leaf effect here, correct?
> 
> Finally, on the remaining two walls, they will be like this:
> 
> {CONCRETE FOUNDATION WALL} 1" GAP {STUDS W/R13}{DD/GG}
> 
> All of the interior walls will be decoupled from the joists with the IB-3 brackets.


So, a double stud wall then, with the exception of the 36" corridor separated from the main room by clips & channel. So, based on that I have a few thoughts:

1. Why not put DW on both sides of the 36" corridor that you will be converting in to a separate room?
2. If you do that (#1), I don't believe you'll need clips & channel on the wall inside the HT room necessarily (tho wouldn't hurt) because you'd then have a 4 leaf scenario (DW/gap/DW/gap/DW/gap/DW)
3. You'll need to be wary of short-circuiting your sound proof shell via the 36" corridor. For instance, if that's not part of the shell then you need to treat the door into the room with appropriate sound proofing measures. 
4. Why not make the wall between the corridor and HT room a double-stud wall? Is there a space constraint? It would save you a little $ versus clips & channel and keep the framing architecture consistent
5. Your ceiling will be attached directly to the floor joists above. Is that correct?


----------



## HT Geek

Ben L Walker said:


> The entrance to the storage area will be outside of the soundproof envelope, as well as the AV rack and the AV rack access.


Will the A/V rack and rack access be adjacent to any other part of the home or the corridor? If so, be careful with that. Ideally, you will want to do some sound-proofing relative to your A/V rack if that's the case, so you don't have any significant leakage in/out of the HT room. Doesn't have to be fancy. Something like a backer-box design but where you have the ability to access the equipment. Don't forget to plan for cooling your rack.




> I have thought about that, but the Mrs. isn't sold on that yet. I still could even with the storage access if one door swung into the theater and the other swung into the adjacent room, right?


I know it's usually a tough sell to overcome WAF. One possibility is to build a communicating door setup where both doors swing toward you as you enter the theater, and hinge them on the same side as one another. If you structure it such that either door could be left open / propped open, that would create an easier flow that may not upset the wife as much. When you are blaring movies or music in there, you can shut them both to keep from bothering her, family, etc. Or alternatively, do as you mentioned and make the HT room door an in-swing and the outside door an outswing. Either way you should be able to open up the hallway nicely when desired without impinging on access to the corridor, unless you have space constraints I haven't picked up on.

Bear in mind that building code requires level flooring where the door swings a minimum distance from the door frame equal to the width of the door (e.g. 32", 36", etc.). And there is a minimum opening distance (which I don't recall off-hand). The latter comes into play when you have a door that won't open fully due to the room design or an obstruction. I don't believe either of these issues are likely to affect your room design, based on what I've seen so far, but FYI.


----------



## GatorBlues

I have an Atmos question. 

As I have described earlier in this thread, we are building a room within a room to completely decouple the theater from the support walls and from the floor joists above. We will have double drywall all around and, based on a recommendation in this thread, likely a triple layer -- drywall, MDF, then drywall again -- on the ceiling. All of the extra layers will be separated by green glue. Obviously, after all of these efforts to soundproof, I can't justify cutting holes in the triple layered ceiling for overhead speakers. Mounting bookshelf speakers from the ceiling is not acceptable to my wife. And, I'm not thrilled with the on wall speakers I might mount to the ceiling above -- the low profile speakers either are exorbitantly expensive or do not go deep enough (which is a concern for the long run -- I believe Atmos will evolve over time to demand a fuller range performance from the height speakers). 

Brainstorming this morning, I started wondering if it would make sense to build a ceiling column (for lack of a better term). What I'm envisioning is something akin to columns on the side walls that you often see in home theaters, but on the ceiling instead, like a coffered ceiling with an unusually large width. Then, I could mount in wall or in ceiling speakers in the ceiling column/coffer. 

Has anyone tried this? Is there a flaw in my theory that makes it a bad idea? Do you have any other suggestions besides hanging speakers on mounts from the ceiling, which the wife is never going to approve?


----------



## jrref

GatorBlues said:


> I have an Atmos question.
> 
> As I have described earlier in this thread, we are building a room within a room to completely decouple the theater from the support walls and from the floor joists above. We will have double drywall all around and, based on a recommendation in this thread, likely a triple layer -- drywall, MDF, then drywall again -- on the ceiling. All of the extra layers will be separated by green glue. Obviously, after all of these efforts to soundproof, I can't justify cutting holes in the triple layered ceiling for overhead speakers. Mounting bookshelf speakers from the ceiling is not acceptable to my wife. And, I'm not thrilled with the on wall speakers I might mount to the ceiling above -- the low profile speakers either are exorbitantly expensive or do not go deep enough (which is a concern for the long run -- I believe Atmos will evolve over time to demand a fuller range performance from the height speakers).
> 
> Brainstorming this morning, I started wondering if it would make sense to build a ceiling column (for lack of a better term). What I'm envisioning is something akin to columns on the side walls that you often see in home theaters, but on the ceiling instead, like a coffered ceiling with an unusually large width. Then, I could mount in wall or in ceiling speakers in the ceiling column/coffer.
> 
> Has anyone tried this? Is there a flaw in my theory that makes it a bad idea? Do you have any other suggestions besides hanging speakers on mounts from the ceiling, which the wife is never going to approve?


You might just have to use the atmos speakers that have the up-firing drivers that bounce sound off of the ceiling. There are a couple out there that really work well.


----------



## RustyMon

I'm in the exact same boat... why cut holes in the very surface that you're depending on to stop noise!



GatorBlues said:


> We will have double drywall all around and, based on a recommendation in this thread, likely a triple layer -- drywall, MDF, then drywall again -- on the ceiling.


Why Drywall/MDF/Drywall? I was planning on doing OSB then two layers of drywall.



GatorBlues said:


> What I'm envisioning is something akin to columns on the side walls that you often see in home theaters, but on the ceiling instead, like a coffered ceiling with an unusually large width. Then, I could mount in wall or in ceiling speakers in the ceiling column/coffer.


I love this idea. I'm planning on adding some Cambridge Audio Minx Min 22's to the ceiling, as they are as small as possible but maybe beams that run across would be a better way to go about things. I can't see why it wouldn't work.


----------



## GatorBlues

RustyMon said:


> I'm in the exact same boat... why cut holes in the very surface that you're depending on to stop noise!
> 
> 
> 
> Why Drywall/MDF/Drywall? I was planning on doing OSB then two layers of drywall.
> 
> 
> 
> I love this idea. I'm planning on adding some Cambridge Audio Minx Min 22's to the ceiling, as they are as small as possible but maybe beams that run across would be a better way to go about things. I can't see why it wouldn't work.


I think I meant OSB, not MDF. I'm new to this and regularly get acronyms mixed up. Are those the same?

In any event, I was thinking that putting the OSB layer in the middle would make it a more relaxing experience when things are mounted. If my builder's subcontractor accidentally goes too far with a couple mounting screws and penetrates the back of the OSB panel, he would hit the third ceiling layer instead of plunging through the last layer, which would put a hole in the soundproofing.


----------



## hatlesschimp

RustyMon said:


> I'm in the exact same boat... why cut holes in the very surface that you're depending on to stop noise!
> 
> 
> 
> Why Drywall/MDF/Drywall? I was planning on doing OSB then two layers of drywall.
> 
> 
> 
> I love this idea. I'm planning on adding some Cambridge Audio Minx Min 22's to the ceiling, as they are as small as possible but maybe beams that run across would be a better way to go about things. I can't see why it wouldn't work.


I used to have the minx. Never mounted them on the ceiling but did use the key hole mounts and found the worked well if you didnt need to adjust the angle. I think it was also tricky for the speaker cables. Great little speaker by the way. Just need a sub to go to 130 - 140hz for some crossover. They do have the 1/4 inch screw mounts that could be used with various mount from ebay or amazon. Maybe 2 plastic plaster screws with the course thread will hold the weight in the ceiling if your struggling to find suitable positions for atmos inline with the ceiling rafters. Im actual considering the minx for my father in law that wants a cheap atmos setup.

As for cutting into your plaster for atmos height speakers. I cut through two layers to mount mine. They were lie a 9" hole i had to cut lol. Im just going to make some rough back boxes out of 25mm mdf with some egg creat fiam inside and go up into the roof with them and some liquid nails and just glue them over the top onto the plaster. That way the back of the speaker isnt radiating out sound out and sound isnt passing through the speaker etc.


----------



## RustyMon

GatorBlues said:


> I think I meant OSB, not MDF. I'm new to this and regularly get acronyms mixed up. Are those the same?
> 
> In any event, I was thinking that putting the OSB layer in the middle would make it a more relaxing experience when things are mounted. If my builder's subcontractor accidentally goes too far with a couple mounting screws and penetrates the back of the OSB panel, he would hit the third ceiling layer instead of plunging through the last layer, which would put a hole in the soundproofing.


OSB and MDF are not the same... MDF is made from compressed/glued sawdust. OSB is an engineered wood product that is made with flakes or large chips of wood, and I'm guessing that's what you meant. 

I understand your idea of using OSB as a middle layer to help prevent the possibility of "short circuiting" your soundproofing - IE when a long screw goes through the wall and attaches to the secondary framing behind it. Just to be clear, it shouldn't be a problem for a screw to go through all 3 layers, as long as it doesn't touch the framing on the secondary wall. (At least this is my understanding)


----------



## RustyMon

hatlesschimp said:


> I used to have the minx. ....
> 
> As for cutting into your plaster for atmos height speakers. I cut through two layers to mount mine. They were lie a 9" hole i had to cut lol. Im just going to make some rough back boxes out of 25mm mdf with some egg creat fiam inside and go up into the roof with them and some liquid nails and just glue them over the top onto the plaster. That way the back of the speaker isnt radiating out sound out and sound isnt passing through the speaker etc.


Thanks for the thumbs-up on the Minx... just ordered mine and hope they're up to snuff! Unfortunately my sub only goes up to 95Hz... may have to replace it at some point.

Nice work on your space - and I agree, in-ceiling speakers would work when you are going into attic space, but in my case I'm trying to prevent any/all sound from going into the bedrooms immediately above the HT space. Even if I built a backer box, I don't think it would prevent sound as much as the 3 layer ceiling I've planned (OSB/DW/DW). Maybe that is incorrect and I'd be fine with ceiling mount speakers... but I'm spending all this time/energy/money trying to make sure nothing goes up, seems safer to just mount something on the ceiling rather than in!


----------



## HT Geek

GatorBlues said:


> I have an Atmos question.
> 
> As I have described earlier in this thread, we are building a room within a room to completely decouple the theater from the support walls and from the floor joists above. We will have double drywall all around and, based on a recommendation in this thread, likely a triple layer -- drywall, MDF, then drywall again -- on the ceiling. All of the extra layers will be separated by green glue. Obviously, after all of these efforts to soundproof, I can't justify cutting holes in the triple layered ceiling for overhead speakers....


Why not? What you would need is a good backer box. It's not *ideal* but if you want an Atmos experience, that is what you'll need to do unless you like big wall warts protruding from your ceiling.




> Brainstorming this morning, I started wondering if it would make sense to build a ceiling column (for lack of a better term). What I'm envisioning is something akin to columns on the side walls that you often see in home theaters, but on the ceiling instead, like a coffered ceiling with an unusually large width. Then, I could mount in wall or in ceiling speakers in the ceiling column/coffer.


So, basically you are talking about hollow beams in the ceiling. 



> Do you have any other suggestions besides hanging speakers on mounts from the ceiling, which the wife is never going to approve?


Use in-ceiling speakers designed for this purpose. Use thick backer boxes behind them.


----------



## Ladeback

GatorBlues said:


> I have an Atmos question.
> 
> As I have described earlier in this thread, we are building a room within a room to completely decouple the theater from the support walls and from the floor joists above. We will have double drywall all around and, based on a recommendation in this thread, likely a triple layer -- drywall, MDF, then drywall again -- on the ceiling. All of the extra layers will be separated by green glue. Obviously, after all of these efforts to soundproof, I can't justify cutting holes in the triple layered ceiling for overhead speakers. Mounting bookshelf speakers from the ceiling is not acceptable to my wife. And, I'm not thrilled with the on wall speakers I might mount to the ceiling above -- the low profile speakers either are exorbitantly expensive or do not go deep enough (which is a concern for the long run -- I believe Atmos will evolve over time to demand a fuller range performance from the height speakers).
> 
> 
> Is your room built and dry walled yet? If not you could build backer boxes as @HTGeek suggested. I do not have Dolby Atmos yet, but I will be building back boxes and putting them up in the ceiling before I finish my ceiling. I am going to so the same for lights I will be installing. If you do this just remember to get good measurements to the center of the boxes for future speakers if you are not ready like I am.
> 
> Here is one design for lights and could be used for speakers with some modification.
> 
> https://www.soundproofingcompany.com/wp-content/uploads/2011/06/CIM-backer-box-installation-web.pdf
> 
> You could also buy Dynabox's if you don't want to build backer boxes, but they are pricey.
> 
> https://www.amazon.com/Dynamat-5030...e=UTF8&qid=1485362564&sr=8-1&keywords=dynabox


----------



## HT Geek

RustyMon said:


> ... in my case I'm trying to prevent any/all sound from going into the bedrooms immediately above the HT space. Even if I built a backer box, I don't think it would prevent sound as much as the 3 layer ceiling I've planned (OSB/DW/DW)


If you have room, build backer boxes with the same mass as your ceiling (e.g. same layers of materials). As long as there is still an air gap above them, you will have the same effective results of sound reduction and a better experience in your HT from a cosmetic perspective. 

And don't underestimate cement board as a useful, thin alternative to add mass. Have you ever built a backer box with MDF/GG/cement board and picked it up? Heavy. 

Stuff insulation around the backer boxes to tone down any potential reverberations. Shouldn't be a big deal with ceiling speakers. They won't get used much, and they won't be producing deep bass. As long as you don't put an IB sub in your ceiling, you should be ok.


----------



## HT Geek

GatorBlues said:


> In any event, I was thinking that putting the OSB layer in the middle would make it a more relaxing experience when things are mounted. If my builder's subcontractor accidentally goes too far with a couple mounting screws and penetrates the back of the OSB panel, he would hit the third ceiling layer instead of plunging through the last layer, which would put a hole in the soundproofing.


With a double-stud wall, it's not a problem if a screw penetrates all your layers. It will either hang in the air or hit a stud, but it would hit a stud on the inner wall. Those would have to be some hellaciously long screws to penetrate the outer studs. 

If someone has a miss and the screw is hanging in air on the inside of the wall, it won't compromise your sound shell. Now, if they pulled it out and left a hole, that would (but you simply plug the hole by squirting acoustic caulk in there and you're GTG).


----------



## GatorBlues

HT Geek said:


> With a double-stud wall, it's not a problem if a screw penetrates all your layers. It will either hang in the air or hit a stud, but it would hit a stud on the inner wall. Those would have to be some hellaciously long screws to penetrate the outer studs.
> 
> If someone has a miss and the screw is hanging in air on the inside of the wall, it won't compromise your sound shell. Now, if they pulled it out and left a hole, that would (but you simply plug the hole by squirting acoustic caulk in there and you're GTG).


This is very helpful. Thanks. 

By the way, do you have a link handy about how to build and attach backer boxes for ceiling speakers?


----------



## HT Geek

GatorBlues said:


> By the way, do you have a link handy about how to build and attach backer boxes for ceiling speakers?


Here are some useful threads on the subject:

Soundproofing Company Guide to Backer Box Construction

Backer Box thread w/pics and comments from BigMouthinDC

Speaker Backer Boxes


Btw, many folks have used a few IB-3 clips (or similar) to help distribute their weight so they are not only held up by your ceiling. It also helps keep them in place. However, IMHO that's not always necessary. Point is you want to be sure there is suitable strength holding them up. Whether or not you need clips to do that will be relative to the circumstances of your room and the backer box locations.


----------



## Ladeback

GatorBlues said:


> This is very helpful. Thanks.
> 
> By the way, do you have a link handy about how to build and attach backer boxes for ceiling speakers?


Here is a post about them a year or so ago.

http://www.avsforum.com/forum/19-de...n/2337905-backer-boxes-speakers-lighting.html


----------



## RustyMon

HT Geek said:


> If you have room, build backer boxes with the same mass as your ceiling (e.g. same layers of materials).


Thanks for the encouragement... maybe I just need to suck it up and build boxes. It makes sense that it should work well this way. A bit more work, but no speakers hanging down... still scares me - because if I fail in my soundproofing efforts, I won't be able to use the HT after 7:45pm when the kids go to bed! Just have to cowboy up, I guess!


----------



## Ladeback

RustyMon said:


> Thanks for the encouragement... maybe I just need to suck it up and build boxes. It makes sense that it should work well this way. A bit more work, but no speakers hanging down... still scares me - because if I fail in my soundproofing efforts, I won't be able to use the HT after 7:45pm when the kids go to bed! Just have to cowboy up, I guess!


That's why I built mine under the kitchen and living room above. People above can hear my HT when I turn it up, but at normal listening volume it's not to bad. I have to build boxes too, but other things have to come first.


----------



## HT Geek

RustyMon said:


> Thanks for the encouragement... maybe I just need to suck it up and build boxes. It makes sense that it should work well this way. A bit more work, but no speakers hanging down... still scares me - because if I fail in my soundproofing efforts, I won't be able to use the HT after 7:45pm when the kids go to bed! Just have to cowboy up, I guess!


You're not going to fail!!! Worst case scenario, turn the volume down a bit or turn the bass effects down a bit. Achieving complete sound isolation is relative to factors such as the volume of your preferred listening level, construction of your room, distance to other ears, etc.

BTW, if you use cement backer board, the 1/4" stuff can be cut with a utility knife, though it is difficult. The 1/2" I'd say a circular saw or table saw is a must. If you use a saw, be aware the cement boards will 1) make a whole bunch of dust you should not be breathing; and 2) will dull the heck out of your saw blade (so use an old crappy blade if you can and regardless plan on replacing the blade prior to the next time you cut wood)!

The cement backer board is most advantageous for lighting backer boxes because it meets fire code and you can put it close to non-IC lights (you need 1/2" minimum clearance IIRC). You don't need it for speaker backer boxes, but it can be used.


----------



## ncabw

Thanks for all the help so far people. I'm getting ready to DW the walls and ceilings. I have 3 options i think. i have pics and will be using GG between all DW

1)1 layer of DW on wall first then 1 layer of DW on ceiling leaving 1/4". Then 2nd layer DW on wall followed by 2nd layer on ceiling
2)DD wall then DD ceiling leaving 1/4"
3) DD ceiling then DD wall leaving 1/4"

Acoustical seal(GG company) in 1/4" gap 



Also on a side note I might end up framing for a win fridge within the room later on. Can i just add track to the ceiling DW and floor? My ceiling and walls are already decoupled. I was just going to leave 1/4" gap around drywall and seal it after. I think I wil have to upload a pic of what I'm thinking.


----------



## bombertodd

The first pic is what you want.

Rod Gervais is one of the best studio designers in the world he has a great book "Build it Like the Pros" that talks about building rooms with sound isolation. 


He said this to a similar question: 

"You should be holding the drywall clear of all corners (a little crack won't do) from 1/4 to 3/8"...... then install backer rod can caulk (the backer rod is important to create a 2 point connection - without it the caulk will develop stress cracks over time - and fail to stop the passage of air).

So the process would be ceiling first - caulk the 4 edges - wall "A" - caulk all 4 edges - the same for walls "B", "C". * "D". Repeat the process for additional layers.

Now - as to the need to caulk all seams - if you have staggered all of the joints in the subsequent layers there really is no need to caulk the joints. Simply apply a one coat tape job on the seams - which will fill the tapered edge and you're good to go.

Rod"

source: https://www.gearslutz.com/board/stu.../683118-drywall-corners-acoustical-caulk.html


----------



## ncabw

bombertodd said:


> The first pic is what you want.
> 
> 
> 
> Rod Gervais is one of the best studio designers in the world he has a great book "Build it Like the Pros" that talks about building rooms with sound isolation.
> 
> 
> 
> 
> 
> He said this to a similar question:
> 
> 
> 
> "You should be holding the drywall clear of all corners (a little crack won't do) from 1/4 to 3/8"...... then install backer rod can caulk (the backer rod is important to create a 2 point connection - without it the caulk will develop stress cracks over time - and fail to stop the passage of air).
> 
> 
> 
> So the process would be ceiling first - caulk the 4 edges - wall "A" - caulk all 4 edges - the same for walls "B", "C". * "D". Repeat the process for additional layers.
> 
> 
> 
> Now - as to the need to caulk all seams - if you have staggered all of the joints in the subsequent layers there really is no need to caulk the joints. Simply apply a one coat tape job on the seams - which will fill the tapered edge and you're good to go.
> 
> 
> 
> Rod"
> 
> 
> 
> source: https://www.gearslutz.com/board/stu.../683118-drywall-corners-acoustical-caulk.html




Thanks. That's exactly what I was looking for. Is it a big no no not to add the backer rod?

I was planning on just sealing the 2nd layer of DW gaps. 

Or should I just seal both first and 2nd layer DW 

Thanks 


Sent from my iPhone using Tapatalk


----------



## Gouie

Curious, what is the rationale for leaving a gap between the drywall? Wouldn't you want the seal to be as tight as possible?


----------



## bombertodd

ncabw said:


> Thanks. That's exactly what I was looking for. Is it a big no no not to add the backer rod?
> 
> I was planning on just sealing the 2nd layer of DW gaps.
> 
> Or should I just seal both first and 2nd layer DW
> 
> Thanks


I'd seal the layers individually. I'd also use the backer rod or there will be a good chance the caulk will crack on one of the edges. It's under $4 for 20 feet at Lowe's too. Remember the big goal is to air seal. If your caulk develops cracks, that make a poor air seal.



Gouie said:


> Curious, what is the rationale for leaving a gap between the drywall? Wouldn't you want the seal to be as tight as possible?


You want the walls to be able to flex and move. By making a 1/4-3/8 inch gap then filling with caulk, it provides some area to give.


----------



## HT Geek

ncabw said:


> Thanks for all the help so far people. I'm getting ready to DW the walls and ceilings. I have 3 options i think. i have pics and will be using GG between all DW
> 
> 1)1 layer of DW on wall first then 1 layer of DW on ceiling leaving 1/4". Then 2nd layer DW on wall followed by 2nd layer on ceiling
> 2)DD wall then DD ceiling leaving 1/4"
> *3) DD ceiling then DD wall leaving 1/4"*
> 
> Acoustical seal(GG company) in 1/4" gap


Option "3" above is the preferred but not mandatory method. Reasoning is it follows standard practice of professional drywallers; it's purpose is the walls help to hold up the ceiling. In our case w/a HT room build, it's a bit of a moot point because you want a small gap - as you've mentioned. However, in practice aside from being an industry standard it's also easier to trim your wall sheets vs. your ceiling sheets. And in a worst-case scenario if you had some sag in your ceiling for whatever reason, the walls will limit that possibility if they are beneath the edge of the ceiling sheets.

BTW, make sure you double up on the top studs. Otherwise if you start ceiling first, you will run out of wood to screw the top of your walls to for the 2nd layer of wall sheets.




> Also on a side note I might end up framing for a win fridge within the room later on.


I wanted the same thing. I elected to build the fridge inside a cabinet/backer box with the opening into the hallway adjacent to my HT room. The issue with a fridge (of any kind) in your room is noise (picture a quiet scene in a movie and you hear your fridge humming in the background), especially after going to great lengths to sound-proof your room.




> Can i just add track to the ceiling DW and floor? My ceiling and walls are already decoupled. I was just going to leave 1/4" gap around drywall and seal it after. I think I wil have to upload a pic of what I'm thinking.


Not sure what you're referring to by 'track.'




ncabw said:


> Thanks. That's exactly what I was looking for. Is it a big no no not to add the backer rod?
> 
> I was planning on just sealing the 2nd layer of DW gaps.
> 
> Or should I just seal both first and 2nd layer DW


When I was drywalling, I caulked the butt seams vs. mudding them since they were going to be covered anyway by the subsequent layer. It doesn't matter. You just want to seal them with either caulk or mud.


----------



## HT Geek

ncabw said:


> Thanks for all the help so far people. I'm getting ready to DW the walls and ceilings. I have 3 options i think. i have pics and will be using GG between all DW....


Regardless of which method you use for DW layering: Ceiling first or walls first, the most important thing is to stagger your sheets - as per your 'option 1' photo. In my last post, I was suggesting you use that staggering method but start with the ceiling first.


----------



## ncabw

HT Geek said:


> Option "3" above is the preferred but not mandatory method. Reasoning is it follows standard practice of professional drywallers; it's purpose is the walls help to hold up the ceiling. In our case w/a HT room build, it's a bit of a moot point because you want a small gap - as you've mentioned. However, in practice aside from being an industry standard it's also easier to trim your wall sheets vs. your ceiling sheets. And in a worst-case scenario if you had some sag in your ceiling for whatever reason, the walls will limit that possibility if they are beneath the edge of the ceiling sheets.
> 
> 
> 
> BTW, make sure you double up on the top studs. Otherwise if you start ceiling first, you will run out of wood to screw the top of your walls to for the 2nd layer of wall sheets.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I wanted the same thing. I elected to build the fridge inside a cabinet/backer box with the opening into the hallway adjacent to my HT room. The issue with a fridge (of any kind) in your room is noise (picture a quiet scene in a movie and you hear your fridge humming in the background), especially after going to great lengths to sound-proof your room.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Not sure what you're referring to by 'track.'
> 
> 
> 
> 
> 
> 
> 
> 
> 
> When I was drywalling, I caulked the butt seams vs. mudding them since they were going to be covered anyway by the subsequent layer. It doesn't matter. You just want to seal them with either caulk or mud.













So looks like I was planning to do the same thing as you. 

So should I drywall the ceiling and walls then build my wine fridge after as a separate closet. The track is what the metal studs are sitting in. 

The track would have to sit on the floor and be attached to the ceiling. The stud walls for the closet would then be decoupled and use furring channel like the rest of the room. I would then leave the 1/4" Gap and caulk. So only the tract would be attached to the ceiling and ceiling is already decoupled from the joist 





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## Gouie

bombertodd said:


> I'd seal the layers individually. I'd also use the backer rod or there will be a good chance the caulk will crack on one of the edges. It's under $4 for 20 feet at Lowe's too. Remember the big goal is to air seal. If your caulk develops cracks, that make a poor air seal.
> 
> 
> 
> 
> 
> 
> 
> You want the walls to be able to flex and move. By making a 1/4-3/8 inch gap then filling with caulk, it provides some area to give.



Makes sense. Would that concept apply for all drywall joints or just the corners?


----------



## HT Geek

ncabw said:


> So looks like I was planning to do the same thing as you.


Yes. That is same thing I'm doing.




> So should I drywall the ceiling and walls then build my wine fridge after as a separate closet. The track is what the metal studs are sitting in.


If I were to do-over my build, I would place that area outside the HT room shell (since I used double studs). Unfortunately, I came up with the idea after I had framed the room. I had an idea for a fridge in my head, and had planned to install it in the adjacent hallway, but not intruding into the HT room at all. Later I realized there was some HVAC equip behind the wall I was going to use, so carving out space from the HT room became the only option. Hindsight is 20/20, as the saying goes. 





> The track would have to sit on the floor and be attached to the ceiling. The stud walls for the closet would then be decoupled and use furring channel like the rest of the room. I would then leave the 1/4" Gap and caulk. So only the tract would be attached to the ceiling and ceiling is already decoupled from the joist


That's good, however what you want to accomplish is de-coupling that closet/cabinet from the HT room. It doesn't matter if it is de-coupled from the main studs in the house. Basically, you want to eliminate pathways for sound to travel to/from your HT shell and that closet. Otherwise, even if it is de-coupled, since you will have an opening into the main portion of your home you'll be more likely to get some sound cross-contamination.

What I settled on in my case was building a 2x 3/4" MDF layer backer box with GG in between layers. That is what I have inside my room. The outside of the MDF will be covered with 1 or 2" thick fabric frames (thickness TBD) with insulation (type TBD but likely one of the higher density insulation boards). Like you, my inner wall is de-coupled so I wasn't too concerned about the walls (though I used acoustic caulk between the walls and the cabinet edges anyway). I also staggered the MDF layers of the backer box/cabinet that is inside the HT room.

I built a platform inside the cabinet for the bottom. It's a bit complicated as the cabinet bottom unfortunately must span both the inner wall and outer stud walls, and the air gap of course. Technically, it re-couples the HT room and main portion of the house - but just in a 2 sq. ft. area where the fridge sits. To mitigate the issue, on the main house side the fridge (floor) platform is supported by a 2x4 rectangular shaped frame that sits on top of one of the home's structural footers. There is acoustic caulk in between the two surfaces. On top of that rectangular 2x4 arrangement are 2 rubber hockey pucks, with acoustic caulk on both sides of the pucks. The cabinet floor rests on top of those pucks with the caulk in between them. That's the outer stud wall side.

On the inner stud wall, the cabinet sits on top of the riser where it protrudes into the HT room. The bottom layer there (resting on the riser) is [acoustic caulk][hockey puck][acoustic caulk][3/4" plywood][Green Glue][3/4" MDF][Green Glue][Cabinet floor]. So, on the HT room side there are 2 layers of 3/4" material under the cabinet, plus hockey pucks, plus GG/caulk. I went to less intensive lengths on the main house/outer stud side of the cabinet because it seemed pointless to go overboard there.

I have two other challenges I've run into with this concept. First, are concerns about the fridge overheating. I'm not using a true built-in fridge with forward air exhaust and intakes. I chose to spend $350 on a commercial grade free-standing small fridge versus $1,000+ on a "built-in" consumer grade fridge. We'll see how it fares over time, as air flow inside my cabinet will be limited. I was restricted in width (studs) and depth (column to-be-built just behind the fridge in the HT room). My fridge is 17" wide and I had only 17" of width between studs. I 'customized' them to get 1/8" on either side. Hopefully that small gap will eliminate any potential vibration issues, but if not I'll just get some thin sorbothane pads and that should take care of it. This is only an issue on the sides where the fridge fits between the outer studs. The remaining side areas have 1" or more of air space around them. In the rear I have ~3" of space behind it, and ~1-1/2" of space above the fridge.

My second challenge is related to the first. Due to how the HT room is constructed and the fridge's position, the left side of the fridge abuts into an area that will be covered with drywall and/or fabric frames. It will be next to a column and ~7" deep. It has the opportunity of creating a nice air pocket that I can use for additional air flow/venting for the fridge. I'm on-the-fence about using it for this purpose because of course doing so would introduce a potential flanking path for sound. The riser extends into that area, and there is a gap between the riser and wall. So, that cavity is already going to function a bit as a bass trap (in conjunction with the riser). There is insulation stuffed in the gaps in this cavity that would limit air flow to/from the fridge cabinet, but it's likely to become an issue if I'm not diligent with planning and figuring out how to balance air flow for the fridge vs. sound containment.

My point for you is don't overlook the nooks and crannies that might be created when you poke a hole in the sound shell - for whatever reason. In my case, doing so has introduced problems I didn't have before. Problems that can be solved, but it's going to be a matter of accepting different trade-offs (e.g. sound containment versus air flow for fridge).

BTW, forgive me for this question... because with all the threads I follow, at times I forget what de-coupling methods each person is using.... By 'track,' are you referring to hat channel and clips?


----------



## ncabw

HT Geek said:


> Yes. That is same thing I'm doing.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If I were to do-over my build, I would place that area outside the HT room shell (since I used double studs). Unfortunately, I came up with the idea after I had framed the room. I had an idea for a fridge in my head, and had planned to install it in the adjacent hallway, but not intruding into the HT room at all. Later I realized there was some HVAC equip behind the wall I was going to use, so carving out space from the HT room became the only option. Hindsight is 20/20, as the saying goes.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> That's good, however what you want to accomplish is de-coupling that closet/cabinet from the HT room. It doesn't matter if it is de-coupled from the main studs in the house. Basically, you want to eliminate pathways for sound to travel to/from your HT shell and that closet. Otherwise, even if it is de-coupled, since you will have an opening into the main portion of your home you'll be more likely to get some sound cross-contamination.
> 
> 
> 
> What I settled on in my case was building a 2x 3/4" MDF layer backer box with GG in between layers. That is what I have inside my room. The outside of the MDF will be covered with 1 or 2" thick fabric frames (thickness TBD) with insulation (type TBD but likely one of the higher density insulation boards). Like you, my inner wall is de-coupled so I wasn't too concerned about the walls (though I used acoustic caulk between the walls and the cabinet edges anyway). I also staggered the MDF layers of the backer box/cabinet that is inside the HT room.
> 
> 
> 
> I built a platform inside the cabinet for the bottom. It's a bit complicated as the cabinet bottom unfortunately must span both the inner wall and outer stud walls, and the air gap of course. Technically, it re-couples the HT room and main portion of the house - but just in a 2 sq. ft. area where the fridge sits. To mitigate the issue, on the main house side the fridge (floor) platform is supported by a 2x4 rectangular shaped frame that sits on top of one of the home's structural footers. There is acoustic caulk in between the two surfaces. On top of that rectangular 2x4 arrangement are 2 rubber hockey pucks, with acoustic caulk on both sides of the pucks. The cabinet floor rests on top of those pucks with the caulk in between them. That's the outer stud wall side.
> 
> 
> 
> On the inner stud wall, the cabinet sits on top of the riser where it protrudes into the HT room. The bottom layer there (resting on the riser) is [acoustic caulk][hockey puck][acoustic caulk][3/4" plywood][Green Glue][3/4" MDF][Green Glue][Cabinet floor]. So, on the HT room side there are 2 layers of 3/4" material under the cabinet, plus hockey pucks, plus GG/caulk. I went to less intensive lengths on the main house/outer stud side of the cabinet because it seemed pointless to go overboard there.
> 
> 
> 
> I have two other challenges I've run into with this concept. First, are concerns about the fridge overheating. I'm not using a true built-in fridge with forward air exhaust and intakes. I chose to spend $350 on a commercial grade free-standing small fridge versus $1,000+ on a "built-in" consumer grade fridge. We'll see how it fares over time, as air flow inside my cabinet will be limited. I was restricted in width (studs) and depth (column to-be-built just behind the fridge in the HT room). My fridge is 17" wide and I had only 17" of width between studs. I 'customized' them to get 1/8" on either side. Hopefully that small gap will eliminate any potential vibration issues, but if not I'll just get some thin sorbothane pads and that should take care of it. This is only an issue on the sides where the fridge fits between the outer studs. The remaining side areas have 1" or more of air space around them. In the rear I have ~3" of space behind it, and ~1-1/2" of space above the fridge.
> 
> 
> 
> My second challenge is related to the first. Due to how the HT room is constructed and the fridge's position, the left side of the fridge abuts into an area that will be covered with drywall and/or fabric frames. It will be next to a column and ~7" deep. It has the opportunity of creating a nice air pocket that I can use for additional air flow/venting for the fridge. I'm on-the-fence about using it for this purpose because of course doing so would introduce a potential flanking path for sound. The riser extends into that area, and there is a gap between the riser and wall. So, that cavity is already going to function a bit as a bass trap (in conjunction with the riser). There is insulation stuffed in the gaps in this cavity that would limit air flow to/from the fridge cabinet, but it's likely to become an issue if I'm not diligent with planning and figuring out how to balance air flow for the fridge vs. sound containment.
> 
> 
> 
> My point for you is don't overlook the nooks and crannies that might be created when you poke a hole in the sound shell - for whatever reason. In my case, doing so has introduced problems I didn't have before. Problems that can be solved, but it's going to be a matter of accepting different trade-offs (e.g. sound containment versus air flow for fridge).
> 
> 
> 
> BTW, forgive me for this question... because with all the threads I follow, at times I forget what de-coupling methods each person is using.... By 'track,' are you referring to hat channel and clips?




Thanks for the reply

So for my ceiling I used clips and hat channel 
Walls are steel stud wall built in side the foundation. I also used clips and channel there. 


So for track this is wan I'm talking about 











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## ncabw

I think I'm now going to just build the wine fridge outside the room. I have stairs that would be about 3.5-4' away from the new finished wine fridge. I think. That should be enough clearance since originally we had a closet that was going to be 3' away from the stairs. 


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## HT Geek

ncabw said:


> Thanks for the reply
> 
> So for my ceiling I used clips and hat channel
> Walls are steel stud wall built in side the foundation. I also used clips and channel there.


Ideally, you do not want the closet walls to be shared with the room walls.

In my case I don't have enough depth to do that, so I've had to compromise on a solution. And btw, I took a look at my cabinet floor and walls and realized I mis-spoke earlier.

The walls, ceiling, and floor are all 3/4" plywood. Then the outer layers are 3/4" MDF. The floor on the HT room side is constructed as I mentioned in my last post, but there is also a 3/8" rubber mat between the wood layers. The floor of the cabinet in the HT side is ~3" thick.

Or if you put it under your stairs, that's even better.  You should have plenty of clearance under your stairs. There's lots of wasted space under stairs.


----------



## ncabw

HT Geek said:


> Ideally, you do not want the closet walls to be shared with the room walls.
> 
> 
> 
> In my case I don't have enough depth to do that, so I've had to compromise on a solution. And btw, I took a look at my cabinet floor and walls and realized I mis-spoke earlier.
> 
> 
> 
> The walls, ceiling, and floor are all 3/4" plywood. Then the outer layers are 3/4" MDF. The floor on the HT room side is constructed as I mentioned in my last post, but there is also a 3/8" rubber mat between the wood layers. The floor of the cabinet in the HT side is ~3" thick.
> 
> 
> 
> Or if you put it under your stairs, that's even better.  You should have plenty of clearance under your stairs. There's lots of wasted space under stairs.




I can't do the under stairs set up. Wife wants that for storage for kids toys. 

I think it's best to build a little closet for the wine fridge. This way it won't compromise anything I have done so far for soundproofing. 


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## doveman

I've got a difficult room to treat and could use some advice. It's in a block of flats and shares a party wall with a neighbour but also gets a fair bit of noise from the flat above the adjacent neighbour and the flat directly below me. The ceiling seems to be a slab of concrete that probably carries on over the party wall to the neighbour's outside wall. There's a few mm gap between the floor joists and the concrete slab and there's an old, quite thin and squashed, layer of pink insulation in the gap which probably isn't doing much.

The problem is mostly voices, shouting, TV, etc. not really low frequency stuff although that's probably just because people know how bad the soundproofing is and avoid using subwoofers or playing loud bassy music. I don't seem to hear any voices from directly above, there was an issue with impact noise (footsteps, coins being dropped and rolling around) but that has stopped recently, so maybe they've fitted carpet over their laminate flooring. I do hear a fair bit of banging cupboards from there though at certain times of the day and switches being operated (at least one in particular, which might be the bathroom pull cord) sound like they're in my flat, which is probably because the sound is travelling down the breezeblock walls. The only vibration noise comes from the water pumps that were installed a few years ago and that is quite intrusive. 

Because there is serious flanking, with the noise from those other flats being audible in all four walls of the room, I'm guessing the walls must be breezeblock as I've read that only they have such severe flanking issues. I was wondering if it might be possible to significantly improve the problem by stripping the plaster back from the top and bottom of the party wall, as well as the two corners where it meets the end walls, and injecting something to fill any space in the breezeblocks? Would this stop the noise travelling from above/below into the party wall and from there into the end and opposite walls? I'll still need to strip all the plaster off the party wall and build an independent stud wall filled with foam and covered with two layers of plasterboard but if I can get away with doing this only on that wall it will save losing space I can ill afford to lose, not to mention avoid unnecessary time and expense. I've got sufficient chipboard loft panels to cover the floor, so I could take up the floorboards and replace them with these and fit something in the space as well if it will be worth the effort.


----------



## Livin

Impact noise question...

What would be better to stop impact noise (not transmit / block, absorb, etc):
1. real wood floor
2. engineered wood floor, floating the floor
3. large porcelain tile (12x24, 10x20, etc)

the flooring is being redone in a 27x16w room (Kitchen & Living Room) directly above the theater room. Part of the living room 'might' stay carpet but all the walkways & kitchen (places my kids run and jump) will be hard surface.

thanks!


----------



## turbonut

Livin said:


> Impact noise question...
> 
> What would be better to stop impact noise (not transmit / block, absorb, etc):
> 1. real wood floor
> 2. engineered wood floor, floating the floor
> 3. large porcelain tile (12x24, 10x20, etc)
> 
> the flooring is being redone in a 27x16w room (Kitchen & Living Room) directly above the theater room. Part of the living room 'might' stay carpet but all the walkways & kitchen (places my kids run and jump) will be hard surface.
> 
> thanks!



Honestly, they'll all be about the same. Since this is a structure-borne noise path, the only way to really isolate the room beneath would be to fully isolate its drywall on the ceiling and walls from the framing of the house.


----------



## Livin

turbonut said:


> Honestly, they'll all be about the same. Since this is a structure-borne noise path, the only way to really isolate the room beneath would be to fully isolate its drywall on the ceiling and walls from the framing of the house.


I was hoping that the additional mass of the tile or the floating of the engineered wood might help? 

I was thinking I would be redoing the HT room ceiling with Clips + DGD but not redoing the 'standard built' HT room walls, I want to see if a specific floor might help reduce the impact of kids play/jumping, etc


----------



## turbonut

Livin said:


> I was hoping that the additional mass of the tile or the floating of the engineered wood might help?
> 
> I was thinking I would be redoing the HT room ceiling with Clips + DGD but not redoing the 'standard built' HT room walls, I want to see if a specific floor might help reduce the impact of kids play/jumping, etc



The extra mass will have an affect on damping and cause the floor to have a lower natural frequency, true. But unfortunately it won't be a big enough factor to actually change the transfer path which will dictate the acoustics in the room below. 

Therefore for that reason, personally I'd get the flooring I like best up above and fix the root of the problem down below when the time/budget allows. Just my 2 cents though!


----------



## turbonut

Livin said:


> I was hoping that the additional mass of the tile or the floating of the engineered wood might help?
> 
> I was thinking I would be redoing the HT room ceiling with Clips + DGD but not redoing the 'standard built' HT room walls, I want to see if a specific floor might help reduce the impact of kids play/jumping, etc


One quick additional comment I forgot to mention. 

If you do plan to add isolation clips to the theater room, you would really need to isolate the walls at the same time. The reason being, is wall studs are likely connected directly to the floor joists of the room above. All the energy transmitted from foot impacts will travel through the ceiling, but will also travel down the studs and light up the drywall that is attached directly to them. 

In other words, if you leave the walls un-isolated the drywall attached to them will act as a large speaker, transmitting the energy of the impacts directly into your room in the form of a broadband noise of a similar frequency content as the impact.


----------



## doveman

I've attached a couple of photos to show the composition of my walls. 

The first is the opposite side of the dividing wall between the room I want to treat (which is full of clutter whilst I renovate other rooms) and my living room, where you can see there's a couple of layers of plaster, about 4cm thick, on top of whatever the black/dark grey stuff is.

The second is a hole in my hallway wall where I've dug out an old electric socket (don't worry, the fuse box was replaced a few years ago and the cable isn't attached to the new one) giving a clearer view of what appears to be the same black/dark-grey stuff that's in the other wall.

This doesn't actually look like breezeblock to me but I'm not sure how the noise could be flanking so badly if the walls aren't made of that. The only other possibility I can think of is that the neighbour noise is transmitting through their floorboards into their joists, which are attached to the walls and the noise then travels up/down the walls into my concrete ceiling which sits atop the walls and the noise then flanks across the ceiling into the other walls.


----------



## Ladeback

turbonut said:


> One quick additional comment I forgot to mention.
> 
> If you do plan to add isolation clips to the theater room, you would really need to isolate the walls at the same time. The reason being, is wall studs are likely connected directly to the floor joists of the room above. All the energy transmitted from foot impacts will travel through the ceiling, but will also travel down the studs and light up the drywall that is attached directly to them.
> 
> In other words, if you leave the walls un-isolated the drywall attached to them will act as a large speaker, transmitting the energy of the impacts directly into your room in the form of a broadband noise of a similar frequency content as the impact.


When I built my walls I forgot about the IB-3 clips so my walls are right up to the joist. The other issue I have on one side wall I am up against a beam, I don't think using the ib-3 clips would help, but whisper clips and hat channel might?

On the other side wall I am right up under a beam that runs the length of my house. Now this wall I am thinking of moving out 3' and I could use the IB-3's there. I could also go back to the end walls and put IB-3 in, but that is a lot of work and money my wife doesn't want me to spend. I think that would be cheaper and quicker then putting clips and channel on the wall correct? I am looking into using clips and hat channel on the ceiling.


----------



## turbonut

Ladeback said:


> When I built my walls I forgot about the IB-3 clips so my walls are right up to the joist. The other issue I have on one side wall I am up against a beam, I don't think using the ib-3 clips would help, but whisper clips and hat channel might?
> 
> On the other side wall I am right up under a beam that runs the length of my house. Now this wall I am thinking of moving out 3' and I could use the IB-3's there. I could also go back to the end walls and put IB-3 in, but that is a lot of work and money my wife doesn't want me to spend. I think that would be cheaper and quicker then putting clips and channel on the wall correct? I am looking into using clips and hat channel on the ceiling.


Yep like you alluded to above, an ideally isolated wall would have the studs joined to the joists with IB-3 clips. Then additionally one would want to use the whisper clips and hat channel to attach the drywall. This would essentially act as 2 separate systems of isolation from the rest of the house. Doing one or the other would help, both would be ideal though.

Regarding attaching drywall directly to a metal beam, agreed the IB-3 doesn't apply there. Best you could do in that case is probably frame around the beam (not touching the beam) and attach drywall to the wood with isolation clips and IB-3 to the ceiling joists. Otherwise if that's not an option and you had to mount drywall directly to the beam, the clips and hat channel would definitely help at a minimum.

Regarding your statement about using IB'3s without hat channel/whisper clips. While not ideal, if you were mainly interested in isolating walls from footsteps it would certainly help assuming you isolated the ceiling too. The problem it would cause is the sound pressure created from the speakers/subs in the theater would still light up the drywall and sound would bleed outside of the room.

In the end it's really up to your situation and whether it makes sense to go all the way. In theory it always makes sense to do the 100% job, especially with structural isolation it tends to be all or nothing. But with existing rooms that's typically where compromises need to be made... I can tell you it does not make sense to structurally isolate much in our home theater (which was built from an existing finished room). My wife would literally kill me if I tore up all of the drywall in that room, hahaha. But if I ever get the opportunity to build a dedicated theater from scratch, now that's a different story altogether!


----------



## Ladeback

turbonut said:


> Yep like you alluded to above, an ideally isolated wall would have the studs joined to the joists with IB-3 clips. Then additionally one would want to use the whisper clips and hat channel to attach the drywall. This would essentially act as 2 separate systems of isolation from the rest of the house. Doing one or the other would help, both would be ideal though.
> 
> Regarding attaching drywall directly to a metal beam, agreed the IB-3 doesn't apply there. Best you could do in that case is probably frame around the beam (not touching the beam) and attach drywall to the wood with isolation clips and IB-3 to the ceiling joists. Otherwise if that's not an option and you had to mount drywall directly to the beam, the clips and hat channel would definitely help at a minimum.
> 
> Regarding your statement about using IB'3s without hat channel/whisper clips. While not ideal, if you were mainly interested in isolating walls from footsteps it would certainly help assuming you isolated the ceiling too. The problem it would cause is the sound pressure created from the speakers/subs in the theater would still light up the drywall and sound would bleed outside of the room.
> 
> In the end it's really up to your situation and whether it makes sense to go all the way. In theory it always makes sense to do the 100% job, especially with structural isolation it tends to be all or nothing. But with existing rooms that's typically where compromises need to be made... I can tell you it does not make sense to structurally isolate much in our home theater (which was built from an existing finished room). My wife would literally kill me if I tore up all of the drywall in that room, hahaha. But if I ever get the opportunity to build a dedicated theater from scratch, now that's a different story altogether!


I am not to worried about the rooms next to the home theater in the basement, only sound going up and coming down from above. Side rooms are storage and I would be the only one in those rooms most of the time. Room adjacent to the back entry will be a bar and game room so doors will be open during a party. Wife doesn'twant me to spend much on soundproofing, but I don't think she knows how load it can get. If I move the one wall and box in one beam I will probably isolate those. I need to crank it up and let her hear it and she may change her mind. Room above is kitchen and living room. Her and dad think insulation is enough. I only have 2-300 watt 12" subs. I need to start a build thread on it soon, it's been in limbo for a while.


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## MaderaWoodworking

*Tight space for soundproofing!*

We are building a new house with a 2nd floor bathroom located above a dining area. 

We want to reduce the sound of the water/waste flowing through the drains in the dining room ceiling. The drains are installed in 2x12 joists. We plan to put Roxul batts in the joist bays around the pipes. We were also planning on two layers of 5/8" blueboard (with QuietGlue sandwiched between) attached to bottoms of the joists, with a 1/8" veneer plaster finish. This plan would have left a nice 1/2" reveal on the adjacent 8x12 exposed pine beams.

However, the plasterer just requested additional 3/4" strapping on the bottoms of the joists to even out the plane and reduce the potential for cracks in the ceiling plaster, which only leaves 1" of vertical space left for wallboard, plaster, and a reveal on the beams. Even two layers of 3/8" wallboard + plaster would mean losing the reveal on the beams completely.

I looked at the IB-1 clips and furring channels, but that takes up 1 1/8" leaving only enough space for one layer of 3/8" board + plaster if we still want at least a tiny reveal on the beams.

Okay, soundproofing gurus, my question is this: 

What is the maximum soundproofing performance that is affordably achievable in a total 1 3/4" space that would satisfy the plasterer and still leave a reveal on the beams?

Thanks in advance for your advice.


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## Ladeback

MaderaWoodworking said:


> We are building a new house with a 2nd floor bathroom located above a dining area.
> 
> We want to reduce the sound of the water/waste flowing through the drains in the dining room ceiling. The drains are installed in 2x12 joists. We plan to put Roxul batts in the joist bays around the pipes. We were also planning on two layers of 5/8" blueboard (with QuietGlue sandwiched between) attached to bottoms of the joists, with a 1/8" veneer plaster finish. This plan would have left a nice 1/2" reveal on the adjacent 8x12 exposed pine beams.
> 
> However, the plasterer just requested additional 3/4" strapping on the bottoms of the joists to even out the plane and reduce the potential for cracks in the ceiling plaster, which only leaves 1" of vertical space left for wallboard, plaster, and a reveal on the beams. Even two layers of 3/8" wallboard + plaster would mean losing the reveal on the beams completely.
> 
> I looked at the IB-1 clips and furring channels, but that takes up 1 1/8" leaving only enough space for one layer of 3/8" board + plaster if we still want at least a tiny reveal on the beams.
> 
> Okay, soundproofing gurus, my question is this:
> 
> What is the maximum soundproofing performance that is affordably achievable in a total 1 3/4" space that would satisfy the plasterer and still leave a reveal on the beams?
> 
> Thanks in advance for your advice.


There is product called QuiteRock that already has two layers sandwiched together that you might be able to use, but it is a lot heavier I am told and about $40 to $50 a sheet I think. How often is someone going to someone going to be flushing the toilet while you are having a meal? The insulation may be enough, but not sure. Maybe someone else will respond.


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## jrref

Ladeback said:


> There is product called QuiteRock that already has two layers sandwiched together that you might be able to use, but it is a lot heavier I am told and about $40 to $50 a sheet I think. How often is someone going to someone going to be flushing the toilet while you are having a meal? The insulation may be enough, but not sure. Maybe someone else will respond.


I've used the US Gypsum version of Quiet Rock. Same kind of product but it's a little cheaper and easier to get in the US. In my opinion, you can do it the hard way by using green glue and save money or the easy way using a pre-made product like Quiet Rock but it costs more. You will probably get folks who say that GG might be a little better but it's probably splitting hairs. I got good results with Quiet Rock, about 50 db reduction in sound transmission.


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## Ladeback

jrref said:


> I've used the US Gypsum version of Quiet Rock. Same kind of product but it's a little cheaper and easier to get in the US. In my opinion, you can do it the hard way by using green glue and save money or the easy way using a pre-made product like Quiet Rock but it costs more. You will probably get folks who say that GG might be a little better but it's probably splitting hairs. I got good results with Quiet Rock, about 50 db reduction in sound transmission.


I am getting a cost for QuiteRock from a local distributor and I think it is going to be wash in price between the two. To do my HT ceiling and was with DD & GG it is going to cost about $1400 and my bet that is about what the QR will be or hopefully a little less. I agree that I rather put one layer up with insulation behind the walls and have it done. I post if I go with QR or not.


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## Livin

jrref said:


> I've used the US Gypsum version of Quiet Rock. Same kind of product but it's a little cheaper and easier to get in the US. In my opinion, you can do it the hard way by using green glue and save money or the easy way using a pre-made product like Quiet Rock but it costs more. You will probably get folks who say that GG might be a little better but it's probably splitting hairs. I got good results with Quiet Rock, about 50 db reduction in sound transmission.


when you got the 50db reduction, is that just born sounds - did yo see a reduction in impact sound and/or vibration? Was tht nailed directly to the ceiling joists or hung on clips/channel?

I'm debating if I will tear out my existing drywall ceiling and spend the time/money to do Clips/Channel+ D/GG/D or simply put up a layer GG&and 5/8in drywall right over the existing 1/2" DW (and with decoupling the existing DW from the walls)


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## Ladeback

Ladeback said:


> I am getting a cost for QuiteRock from a local distributor and I think it is going to be wash in price between the two. To do my HT ceiling and was with DD & GG it is going to cost about $1400 and my bet that is about what the QR will be or hopefully a little less. I agree that I rather put one layer up with insulation behind the walls and have it done. I post if I go with QR or not.


I got an estimate for QuiteRock and it is a lot more then I thought. $71 for 1/2" and $83 for 5/8. My contact did say he had another product from National Gypsum called Sound Break for $60 a sheet. For current room of 14x26x9 it would cost around $1620 for Sound break and for DD and GG all around it would be for 5/8" 4x8 sheets it would be around $1407.12. The Sound Break is more, but you only would have to handle sheets one time. Will see which way I go.


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## jrref

Ladeback said:


> I got an estimate for QuiteRock and it is a lot more then I thought. $71 for 1/2" and $83 for 5/8. My contact did say he had another product from National Gypsum called Sound Break for $60 a sheet. For current room of 14x26x9 it would cost around $1620 for Sound break and for DD and GG all around it would be for 5/8" 4x8 sheets it would be around $1407.12. The Sound Break is more, but you only would have to handle sheets one time. Will see which way I go.


I used National Gypsum Sound Break because is it readily available here in NY and it worked just fine. I looked up the spec's and it's pretty much identical to QuietRock. QuietRock is made in Canada so that's why it costs more here in the US. I think that Sound Break is made in NJ.

The decision point is if you are going to do the work yourself then DD and GG will be cheaper but there is more labor involved. If you are going to hire someone to do the work then QuietRock or Sound Break will be cheaper because there is a LOT LESS labor involved. Also with the premade product you know that the sound proofing of the rock is perfect where with GG you have to make sure you get an even coat, that the rock is perfectly sandwiched, etc... Both great, just depends on your situation. I can tell you that Sound Break is a heavy, dense piece of sheetrock with their version of GG sandwiched in between. Once on the wall it's like a cement wall.


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## Ladeback

jrref said:


> I used National Gypsum Sound Break because is it readily available here in NY and it worked just fine. I looked up the spec's and it's pretty much identical to QuietRock. QuietRock is made in Canada so that's why it costs more here in the US. I think that Sound Break is made in NJ.
> 
> The decision point is if you are going to do the work yourself then DD and GG will be cheaper but there is more labor involved. If you are going to hire someone to do the work then QuietRock or Sound Break will be cheaper because there is a LOT LESS labor involved. Also with the premade product you know that the sound proofing of the rock is perfect where with GG you have to make sure you get an even coat, that the rock is perfectly sandwiched, etc... Both great, just depends on your situation. I can tell you that Sound Break is a heavy, dense piece of sheetrock with their version of GG sandwiched in between. Once on the wall it's like a cement wall.



Thanks for the information. I would like to have someone do it, but that would depend on the labor cost. I believe the place I would get the Sound Break also installs it. Did you use clips and hat channel as well on the walls and ceiling?


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## HT Geek

doveman said:


> I've attached a couple of photos to show the composition of my walls.
> 
> The first is the opposite side of the dividing wall between the room I want to treat (which is full of clutter whilst I renovate other rooms) and my living room, where you can see there's a couple of layers of plaster, about 4cm thick, on top of whatever the black/dark grey stuff is.
> 
> The second is a hole in my hallway wall where I've dug out an old electric socket (don't worry, the fuse box was replaced a few years ago and the cable isn't attached to the new one) giving a clearer view of what appears to be the same black/dark-grey stuff that's in the other wall.
> 
> This doesn't actually look like breezeblock to me but I'm not sure how the noise could be flanking so badly if the walls aren't made of that. The only other possibility I can think of is that the neighbour noise is transmitting through their floorboards into their joists, which are attached to the walls and the noise then travels up/down the walls into my concrete ceiling which sits atop the walls and the noise then flanks across the ceiling into the other walls.


Reading your post (above), it's not clear to me what the problem is you're trying to solve. That said, it seems to me your best bet is likely to create a room-within-a-room (independent, isolated, inner stud wall/ceiling) in the room you want to treat. That's presuming you want sound isolation.


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## jrref

Ladeback said:


> Thanks for the information. I would like to have someone do it, but that would depend on the labor cost. I believe the place I would get the Sound Break also installs it. Did you use clips and hat channel as well on the walls and ceiling?


I just needed to soundproof a common wall in my condo so no, I only used Roxul and the Sound Break on that wall and got about a 50db reduction. I still get some flanking in the floor because it's a common floor and there is nothing I can do about that.

The labor cost to install Sound Break should be roughly the same cost of installing 5/8 inch sheetrock. The only extra would be to seal the electrical outlets and to use the Quiet Seal around the outer edges of the rock.


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## HT Geek

MaderaWoodworking said:


> We are building a new house with a 2nd floor bathroom located above a dining area.
> 
> We want to reduce the sound of the water/waste flowing through the drains in the dining room ceiling. The drains are installed in 2x12 joists. We plan to put Roxul batts in the joist bays around the pipes. We were also planning on two layers of 5/8" blueboard (with QuietGlue sandwiched between) attached to bottoms of the joists, with a 1/8" veneer plaster finish. This plan would have left a nice 1/2" reveal on the adjacent 8x12 exposed pine beams....
> 
> What is the maximum soundproofing performance that is affordably achievable in a total 1 3/4" space that would satisfy the plasterer and still leave a reveal on the beams?


Those sounds should be in a range where the insulation helps quite a bit. You are not trying to damp LFE, so that's in your favor. It also means adding mass is less critical (though it certainly helps).

Total 1-3/4" for the sound proofing materials? QuietRock comes in different thicknesses. Let's say we're talking 5/8" drywall and manual application of Green Glue in between. That will equate to ~1-3/8" maximum if one allows 1/8" for the GG layer, leaving you with 3/8" room to spare. That seems like your best bet. As you pointed out, using clips either won't work in that space or you'll at best get 1 layer of 1/2" drywall.


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## HT Geek

Ladeback said:


> I got an estimate for QuiteRock and it is a lot more then I thought. $71 for 1/2" and $83 for 5/8. My contact did say he had another product from National Gypsum called Sound Break for $60 a sheet. For current room of 14x26x9 it would cost around $1620 for Sound break and for DD and GG all around it would be for 5/8" 4x8 sheets it would be around $1407.12. The Sound Break is more, but you only would have to handle sheets one time. Will see which way I go.


Do those quotes include delivery of materials, installation, and job site clean-up? Do they include prep and finish work (e.g. mudding and sanding)? Most drywall contractors charge a flat rate of either a) per square foot; or b) per sheet. My experience is most price per sheet, and IMHO is how you should get a quote (make sure it includes mud/tape/finishing). You could save a few bucks if you do the site clean-up yourself. Think like a contractor. 

Ensure you are getting comprehensive quotes that specify what labor is included and the model # of QuietRock or Sound Break. There are multiple QR products in particular, and there is a wide price range depending on what you want/need. You want to see a transparent job quote, and make sure the product that gets delivered is exactly what you agreed to.

Edit: If you are planning to do fabric wall panels, you may be able to skip the finishing steps and get substantial savings. You would still need to mud or caulk the seams and butt joints.


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## Ladeback

HT Geek said:


> Do those quotes include delivery of materials, installation, and job site clean-up? Do they include prep and finish work (e.g. mudding and sanding)? Most drywall contractors charge a flat rate of either a) per square foot; or b) per sheet. My experience is most price per sheet, and IMHO is how you should get a quote (make sure it includes mud/tape/finishing). You could save a few bucks if you do the site clean-up yourself. Think like a contractor.
> 
> Ensure you are getting comprehensive quotes that specify what labor is included and the model # of QuietRock or Sound Break. There are multiple QR products in particular, and there is a wide price range depending on what you want/need. You want to see a transparent job quote, and make sure the product that gets delivered is exactly what you agreed to.
> 
> Edit: If you are planning to do fabric wall panels, you may be able to skip the finishing steps and get substantial savings. You would still need to mud or caulk the seams and butt joints.


The price quotes I believe were for per sheet only and I would be doing the work. I told the guy when I asked for the price that I would be doing the work. I didn't ask for a cost to install and deliver it at this time, but may look into that when the walls and ceiling are all ready for drywall. To get a proper estimate they would have to come out to look at the job to give me a good estimate. I understand about doing the clean up to save money. When we had carpet put in last year, we tore out all the old and moved the furniture to save about $600 to $700. I have no problem doing the walls it is the ceiling and would have to rent a left to do it right.

Now my wife and father in law want to me to just put up insulation and one layer of 1/2" drywall and call it good, but we all no that won't be enough.

The issue right now is I am thinking of moving a wall out 3' more that is just a stud wall. I am trying to decide if having more room for walkways and a few seats is worth the effort to rebuild a wall. I am starting to think NO. Making my room 3' wider would only net me about two more seats in the current configuration I want to have and 3' isles. If I stay with what I have the isles would be around 30" to 32" so I don't think it is worth it.


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## HT Geek

Ladeback said:


> The price quotes I believe were for per sheet only and I would be doing the work. I told the guy when I asked for the price that I would be doing the work. I didn't ask for a cost to install and deliver it at this time, but may look into that when the walls and ceiling are all ready for drywall. To get a proper estimate they would have to come out to look at the job to give me a good estimate. I understand about doing the clean up to save money. When we had carpet put in last year, we tore out all the old and moved the furniture to save about $600 to $700. I have no problem doing the walls it is the ceiling and would have to rent a left to do it right.
> 
> Now my wife and father in law want to me to just put up insulation and one layer of 1/2" drywall and call it good, but we all no that won't be enough.
> 
> The issue right now is I am thinking of moving a wall out 3' more that is just a stud wall. I am trying to decide if having more room for walkways and a few seats is worth the effort to rebuild a wall. I am starting to think NO. Making my room 3' wider would only net me about two more seats in the current configuration I want to have and 3' isles. If I stay with what I have the isles would be around 30" to 32" so I don't think it is worth it.


Sounds a bit pricey to me. I would suggest doing 2x 5/8 drywall with GreenGlue sandwich. In my area, using 1x GG tube per sandwich, my cost was about $40 per 4x8 section. That included delivery directly to the job site (2nd floor), I.e. my room.

I used a drywall lift. You will definitely want one if you do the install yourself. Your back will thank you and it will pay for itself in time + cost savings vs. labor.

The crap part of drywall is mudding and sanding. You could pay someone to do it. If you DIY that part, there are a few variables to consider. If you will use fabric panels, do it yourself and just mud or caulk the seams. You can be sloppy and no one will see it. If you will paint your walls, will they be textured? If so, the texture will hide many imperfections and you can probably get away with two mud coats. If you do painted walls and no texturing, plan on 3 coats of mud. 

If you mud yourself, here are a few tips: use aluminum or stainless steel drywall knives only (no rust after washing and plastic knives are not precise enough); use as thin a coat as you can for each pass; feather you layers so the last one requires a 12" knife; sand after 2nd and 3rd layers but not the first (unless your first layer is sloppy, lol).

You can get an OK DW lift for $300 or so, a good one $500+. Ideally, rent one.

Think it all over. Depending on what you want the finished product to look like, it may be worth the effort to DIY it. Or save some $:and least do the DW/GG sandwich.

Don't forget corner bead and a good vacuum cleaner, and dust mask!

Final note: order drywall from a reputable, drywall supplier for construction contractors. They all deliver, normally free of charge, and their prices are competitive. Don't purchase from a contractor. Go direct. You will need to call the suppliers and some won't help you if you're not a contractor, but keep calling. Someone will be thankful for your business.


Sent from my ONE A2005 using Tapatalk


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## Ladeback

HT Geek said:


> Sounds a bit pricey to me. I would suggest doing 2x 5/8 drywall with GreenGlue sandwich. In my area, using 1x GG tube per sandwich, my cost was about $40 per 4x8 section. That included delivery directly to the job site (2nd floor), I.e. my room.
> 
> I used a drywall lift. You will definitely want one if you do the install yourself. Your back will thank you and it will pay for itself in time + cost savings vs. labor.
> 
> The crap part of drywall is mudding and sanding. You could pay someone to do it. If you DIY that part, there are a few variables to consider. If you will use fabric panels, do it yourself and just mud or caulk the seams. You can be sloppy and no one will see it. If you will paint your walls, will they be textured? If so, the texture will hide many imperfections and you can probably get away with two mud coats. If you do painted walls and no texturing, plan on 3 coats of mud.
> 
> If you mud yourself, here are a few tips: use aluminum or stainless steel drywall knives only (no rust after washing and plastic knives are not precise enough); use as thin a coat as you can for each pass; feather you layers so the last one requires a 12" knife; sand after 2nd and 3rd layers but not the first (unless your first layer is sloppy, lol).
> 
> You can get an OK DW lift for $300 or so, a good one $500+. Ideally, rent one.
> 
> Think it all over. Depending on what you want the finished product to look like, it may be worth the effort to DIY it. Or save some $:and least do the DW/GG sandwich.
> 
> Don't forget corner bead and a good vacuum cleaner, and dust mask!
> 
> Final note: order drywall from a reputable, drywall supplier for construction contractors. They all deliver, normally free of charge, and their prices are competitive. Don't purchase from a contractor. Go direct. You will need to call the suppliers and some won't help you if you're not a contractor, but keep calling. Someone will be thankful for your business.
> 
> 
> Sent from my ONE A2005 using Tapatalk


All great info and I agree, very pricey. I will look into having the drywall delivered, because it is in my basement and I will rent a lift. My father in law is pretty good at doing the muding and finishing before, so I may leave it to him. I would love to fabric panels, but those are more expensive if I did all the walls that way. Thanks for the help.


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## jrref

Ladeback said:


> All great info and I agree, very pricey. I will look into having the drywall delivered, because it is in my basement and I will rent a lift. My father in law is pretty good at doing the muding and finishing before, so I may leave it to him. I would love to fabric panels, but those are more expensive if I did all the walls that way. Thanks for the help.


Just don't forget that if you do the GG sandwich or get sound break, the rock is a lot heavier than just putting up 5/8 inch sheet rock by itself which is heavy to begin with. So depending on your situation, you might need more help than you are anticipating.


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## Ladeback

jrref said:


> Just don't forget that if you do the GG sandwich or get sound break, the rock is a lot heavier than just putting up 5/8 inch sheet rock by itself which is heavy to begin with. So depending on your situation, you might need more help than you are anticipating.


My father in law will help me and maybe even my brother in law. I understand the sound break being heavy, but I will put up a the first layer the second with GG. Does it get that heavy when you put it on?


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## tnicks

Need some help with HVAC trunk / return and I beam soundproofing. Unfortunately, no matter how I dice up the basement, I have these three main things to contend with directly above my speakers and screen. Do I use ductboard or duct lagging around the duct and in between the soffit or simply unfaced batting? Would a third layer of drywall on the soffit be more beneficial than 2" of ductboard or lag? Appreciate the help!


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## doveman

HT Geek said:


> Reading your post (above), it's not clear to me what the problem is you're trying to solve. That said, it seems to me your best bet is likely to create a room-within-a-room (independent, isolated, inner stud wall/ceiling) in the room you want to treat. That's presuming you want sound isolation.


The problem is noise leakage to/from the neighbouring flats via all four walls. The airborne noise is mostly mid/high range frequencies (voices, TV) rather than any low frequencies but that's mainly down to everyone being considerate and not playing loud bassy stuff or using subwoofers. I can manage without, so to simplify the soundproofing I'm not aiming to make it low-frequency proof. There's some impact noise from above, e.g. footsteps, things dropped on floor, and vibration noise (washing machine, switches in wall) which is probably transmitting via both the walls and the ceiling, so I will have to treat both. As I want to lay cork flooring and will need to sort out the uneven floorboards for that and as I already have enough chipboard loft/attic panels to replace the floorboards, then I figure I might as well pull up the flooring and fill the void with rockwool to start with, as it will be easier before I've built the new walls.

I've been told that the black stuff in my walls is cinder block, which is a low-quality version of concrete breeze block, although even the latter is apparently notorious for flanking. So that seems to explain why I have such issues with flanking and suggests there's nothing I can do to stop the noise transferring from wall to wall, so will definitely have to build a room-within-a-room.

I still need to know whether I can safely strip away all the plaster, back to the cinderblock, and build independent stud walls with a 10mm gap from that like this http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_3.php , as I can't really afford to reduce the size of the room by 100mm+ from the existing walls but if I can strip away the 3.5-4cm of plaster then I'd only be losing about 6cm on each side, which should be OK. I guess I'm wondering whether the plaster (maybe there's some sand/limestone mixed in there as well) might be serving an important purpose, such as keeping moisture out. Maybe that depth of independent wall is overkill for my purposes though and I could use something else to achieve adequate isolation?


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## HT Geek

Ladeback said:


> My father in law will help me and maybe even my brother in law. I understand the sound break being heavy, but I will put up a the first layer the second with GG. Does it get that heavy when you put it on?


A dual dw 4x8 5/8 sandwich is ~150/160 lbs.

Sent from my ONE A2005 using Tapatalk


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## Ladeback

HT Geek said:


> A dual dw 4x8 5/8 sandwich is ~150/160 lbs.
> 
> Sent from my ONE A2005 using Tapatalk


I understand that, but I was told you want to install one layer at a time to over lap the seams correct? In that case it would be about 75 lbs per sheet to install them by my calculations. I think 2 or 3 people can handle that. I would think the GG layer would be the hardest layer to deal with. I hope to find out in a few months.


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## HT Geek

Ladeback said:


> I understand that, but I was told you want to install one layer at a time to over lap the seams correct? In that case it would be about 75 lbs per sheet to install them by my calculations. I think 2 or 3 people can handle that. I would think the GG layer would be the hardest layer to deal with. I hope to find out in a few months.


Correct. Apply GG to back of 2nd layer, then place into position.


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## HT Geek

doveman said:


> The problem is noise leakage to/from the neighbouring flats via all four walls. The airborne noise is mostly mid/high range frequencies (voices, TV) rather than any low frequencies but that's mainly down to everyone being considerate and not playing loud bassy stuff or using subwoofers. I can manage without, so to simplify the soundproofing I'm not aiming to make it low-frequency proof.
> 
> ... some impact noise from above, e.g. footsteps, things dropped on floor, and vibration noise (washing machine, switches in wall)....
> 
> ... As I want to lay cork flooring and will need to sort out the uneven floorboards for that and as I already have enough chipboard loft/attic panels to replace the floorboards, then I figure I might as well pull up the flooring and fill the void with rockwool to start with, as it will be easier before I've built the new walls.


What is the 'void' you are referring to? Are you talking about removing the sub-floor and exposing the floor framing beneath?




> I've been told that the black stuff in my walls is cinder block, which is a low-quality version of concrete breeze block, although even the latter is apparently notorious for flanking. So that seems to explain why I have such issues with flanking and suggests there's nothing I can do to stop the noise transferring from wall to wall, so will definitely have to build a room-within-a-room.


The devil is in the details. Solid concrete - particularly vertical surfaces - can be great for sound-proofing, provided it is about 6" deep or thicker. The downside is it's quite reflective of higher freqs inside a room. As a horizontal surface, it tends to allow impact noise to traverse long distances.

If you have flanking issue it will be due to air pockets. If the concrete is relatively thin, the noise may simply be transferred from one side to the other, meaning you might not actually have a flanking issue. Either way, building a room-within-a-room it's possible to solve this problem.




> I still need to know whether I can safely strip away all the plaster, back to the cinderblock, and build independent stud walls with a 10mm gap from that like this http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_3.php , as I can't really afford to reduce the size of the room by 100mm+ from the existing walls but if I can strip away the 3.5-4cm of plaster then I'd only be losing about 6cm on each side, which should be OK. I guess I'm wondering whether the plaster (maybe there's some sand/limestone mixed in there as well) might be serving an important purpose, such as keeping moisture out. Maybe that depth of independent wall is overkill for my purposes though and I could use something else to achieve adequate isolation?


Well, you have raised a good point about moisture. If you applied studs directly to concrete, you would want to ensure there was a moisture barrier between them. However, in this case you want to place the studs near the walls with small air gap, as you've indicated. That makes the moisture problem a non-issue. Use IB-3 clips or something similar to anchor your new studs to the structural walls and ceiling. 

Now the floor. If you're going to rip out your existing flooring, this would be potentially very beneficial. It gives you the opportunity to properly de-couple your floor from the structure - which is the most difficult challenge when you're building a HT room that is not in a basement. Without knowing the full details and being able to take into consideration how much height you will have to work with, I'll say your best bet is to de-couple your floor beneath the sub-floor. In other words, get down to your framing below the floor and de-couple from that framing, then re-build a sub-floor and add a finished floor. U-boats are most commonly used in this scenario for de-coupling from the floor joists.

The next best option is to use a de-coupling technique on top of your sub-floor, such as Kinetics RIM. Even better, use RIM with 2x4 sleepers, 2x sub-floor staggered layers on top, and then your finished floor, such as seen here. Hockey pucks are a cheap alternative that act similarly to the U-boats but are taller. You would place them on your original sub-floor. Make sure you purchase regulation/certified pucks so you know they are actually made of rubber and uniform in size (1" tall IIRC).

What drives your decision on floor de-coupling (other than cost and time) is likely going to be how much of a change in elevation you are able to tolerate, when entering the room. To de-couple the floor you will almost undoubtedly have to accommodate a change in elevation unless you're able to use the U-boats under the sub-floor, in which case you may be able to hide a slight change in elevation with the threshold entering the room. That would also come at the expense of reduced de-coupling compared with what you can accomplish with a thicker floor.

If you have a concrete floor, consider the RIM suggestion above or hockey pucks and as I said. See what you can live with in terms of floor elevation change. Something else to consider in that situation would be entering the room at riser height, which would give you more freedom with floor isolation. If you decide the floor is a non-issue for you in terms of importance of de-coupling, that would make the project easier.

Just keep in mind you will need a solid enough floor for your 'inner' room to be able to secure your wall footers to it. Then you only need a few IB-3 clips to keep the walls plumb. Adding new, independent ceiling joists in your 'inner' room will complete the inner framing and maintain its integrity.


----------



## HT Geek

doveman said:


> I still need to know whether I can safely strip away all the plaster, back to the cinderblock, and build independent stud walls with a 10mm gap


Forgot to answer your question directly.

Yes, there's no reason you can't strip off the plaster. It is there for aesthetic purposes and to reduce the transfer of moisture. Regarding the latter, you won't get much anyway (moisture transfer) in your circumstances. If that were the case you'd end up with moisture behind the plaster and eventually mold. It's more aesthetic (the plaster) than functional. 

It's still wise to remember that concrete is semi-porous. If you are not below earth grade it *should* be a non-issue, but if it were my build I'd still use pressure-treated lumber or a moisture barrier on anything touching concrete. Easier to spend a small amount more $ on a small amount of materials up front vs. a lot of $ and effort fixing a problem if there ever is one down the road.


----------



## doveman

HT Geek said:


> What is the 'void' you are referring to? Are you talking about removing the sub-floor and exposing the floor framing beneath?


Yeah, that's what I meant. Removing the floorboards to expose the joists. By 'void' I just meant the space between my floorboards and the concrete slab underneath my joists (attached to the walls and not touching the concrete slab as far as I can tell) which forms the ceiling of the downstairs flat.



> The devil is in the details. Solid concrete - particularly vertical surfaces - can be great for sound-proofing, provided it is about 6" deep or thicker. The downside is it's quite reflective of higher freqs inside a room. As a horizontal surface, it tends to allow impact noise to traverse long distances.
> 
> If you have flanking issue it will be due to air pockets. If the concrete is relatively thin, the noise may simply be transferred from one side to the other, meaning you might not actually have a flanking issue. Either way, building a room-within-a-room it's possible to solve this problem.


I imagine the concrete slabs that form my ceiling (and the downstairs flat's ceiling, underneath my floorboards and joists) could well be 6" deep or thicker. Not sure about the thickness of the walls but I'm not even sure they're concrete. If they're cinder block, that is apparently made from fly ash or bottom ash. I can't tell from looking into the wall exactly what they look like and if they have holes/air pockets they'd be facing up so they wouldn't be visible from the side but they're definitely almost black rather than light-grey like these concrete blocks https://en.wikipedia.org/wiki/Concrete_masonry_unit#/media/File:Concreteblocks.jpg

It's possible they're Dense Blocks like these (not sure if they're made of concrete) http://www.wickes.co.uk/Products/Bu...-Blocks+Lintels/Blocks/Dense-Blocks/c/1001110 or Aerated Concrete Blocks likes these https://www.travisperkins.co.uk/H+H...0mm/p/700055?gclid=CPui0JTKl9ICFfYK0wodPacBPg

I'm told these properties were built in the 1970's, which might narrow down the materials that were used but probably isn't that much help.

I'm sure the noise does simply transfer from one side of the party wall to the other but it's also definitely flanking into the other three walls, as it can be heard almost as loudly in them. Likewise with the noise from upstairs, which may be originally travelling down one wall and then flanking into the other walls, or maybe through the concrete slab (i.e. my ceiling) that's under their floor and from there into the walls. I'll knock up a rough diagram to illustrate the suspected noise paths when I have time, as it's probably easier to show them rather than try and describe them.



> Well, you have raised a good point about moisture. If you applied studs directly to concrete, you would want to ensure there was a moisture barrier between them. However, in this case you want to place the studs near the walls with small air gap, as you've indicated. That makes the moisture problem a non-issue. Use IB-3 clips or something similar to anchor your new studs to the structural walls and ceiling.


As you say, the stud walls will be spaced 10mm from the original stripped-back walls, so there's no concerns about moisture there. However, as I understand it the stud wall only has a bead of mastic on the side edges to isolate it from the side walls, so if they're concrete (as opposed to cinder/ash block) maybe that's close enough for moisture to be an issue?

I'm not sure why it's OK to only have a thin bead of mastic separating the studs from the side walls when I need a 10mm air gap behind the stud wall. I guess this wouldn't matter if only the wall behind was problematic but when flanking is causing the end walls to leak/transmit as badly as the wall the stud is being built in front of, then I'd think I'd need a 10mm gap on the sides as well but that's not really practical as the wall needs to be supported.



> Now the floor. If you're going to rip out your existing flooring, this would be potentially very beneficial. It gives you the opportunity to properly de-couple your floor from the structure - which is the most difficult challenge when you're building a HT room that is not in a basement. Without knowing the full details and being able to take into consideration how much height you will have to work with, I'll say your best bet is to de-couple your floor beneath the sub-floor. In other words, get down to your framing below the floor and de-couple from that framing, then re-build a sub-floor and add a finished floor. U-boats are most commonly used in this scenario for de-coupling from the floor joists.
> 
> The next best option is to use a de-coupling technique on top of your sub-floor, such as Kinetics RIM. Even better, use RIM with 2x4 sleepers, 2x sub-floor staggered layers on top, and then your finished floor, such as seen here. Hockey pucks are a cheap alternative that act similarly to the U-boats but are taller. You would place them on your original sub-floor. Make sure you purchase regulation/certified pucks so you know they are actually made of rubber and uniform in size (1" tall IIRC).
> 
> What drives your decision on floor de-coupling (other than cost and time) is likely going to be how much of a change in elevation you are able to tolerate, when entering the room. To de-couple the floor you will almost undoubtedly have to accommodate a change in elevation unless you're able to use the U-boats under the sub-floor, in which case you may be able to hide a slight change in elevation with the threshold entering the room. That would also come at the expense of reduced de-coupling compared with what you can accomplish with a thicker floor.
> 
> If you have a concrete floor, consider the RIM suggestion above or hockey pucks and as I said. See what you can live with in terms of floor elevation change. Something else to consider in that situation would be entering the room at riser height, which would give you more freedom with floor isolation. If you decide the floor is a non-issue for you in terms of importance of de-coupling, that would make the project easier.
> 
> Just keep in mind you will need a solid enough floor for your 'inner' room to be able to secure your wall footers to it. Then you only need a few IB-3 clips to keep the walls plumb. Adding new, independent ceiling joists in your 'inner' room will complete the inner framing and maintain its integrity.


The ceiling's quite low already and it will be even lower when I add the independent ceiling so I need to try and minimise any increase in floor elevation. If I do replace the sub-floor, which will probably be the easiest way to sort out the unevenness, then the U-boats look like my best option, along with some rockwall slabs wedged in between the joists, although I like the hockey pucks idea. I don't really understand the Kinetics RIM PDF, as it seems to show it stuffed between the joists, like rockwool, with sleepers resting directly on the joists and 2 layers of plywood sub-floor on top of the sleepers, so there doesn't seem to be anything to stop impact noise transmitting from the subfloor through the sleepers and joists to the concrete structural floor.

In my room it may be that any noise from downstairs is coming up the walls rather than up through downstairs' concrete ceiling, in which case fitting perimeter isolation board and sealant and maybe a few inches deep of rockwool slab around the perimeter might be sufficient to keep the noise from getting into the under-floor space. There'd still be impact noise transmitting from my floor into the joists and then into the walls though, so I'd need the U-boats to deal with that. The floor's probably the least problematic surface though and cork tiles alone might be sufficient to make both airborne and impact noise a non-issue but if I've got to replace the subfloor to level it, I'll probably take the opportunity to beef up the sound isolation just to be safe.



> Yes, there's no reason you can't strip off the plaster. It is there for aesthetic purposes and to reduce the transfer of moisture. Regarding the latter, you won't get much anyway (moisture transfer) in your circumstances. If that were the case you'd end up with moisture behind the plaster and eventually mold. It's more aesthetic (the plaster) than functional.
> 
> It's still wise to remember that concrete is semi-porous. If you are not below earth grade it *should* be a non-issue, but if it were my build I'd still use pressure-treated lumber or a moisture barrier on anything touching concrete. Easier to spend a small amount more $ on a small amount of materials up front vs. a lot of $ and effort fixing a problem if there ever is one down the road.


Good to know that I can strip off the plaster and avoid making the room too small. As discussed above, my walls might be cinder/ash block rather than concrete, in which case the only part of the stud that's close to concrete (but still separated from it by a layer of paint and plaster) would be the part that's joined to the ceiling.


----------



## HT Geek

doveman said:


> I imagine the concrete slabs that form my ceiling (and the downstairs flat's ceiling, underneath my floorboards and joists) could well be 6" deep or thicker. Not sure about the thickness of the walls but I'm not even sure they're concrete. If they're cinder block, that is apparently made from fly ash or bottom ash. I can't tell from looking into the wall exactly what they look like and if they have holes/air pockets they'd be facing up so they wouldn't be visible from the side but they're definitely almost black rather than light-grey like these concrete blocks https://en.wikipedia.org/wiki/Concrete_masonry_unit#/media/File:Concreteblocks.jpg
> 
> It's possible they're Dense Blocks like these (not sure if they're made of concrete) http://www.wickes.co.uk/Products/Bu...-Blocks+Lintels/Blocks/Dense-Blocks/c/1001110 or Aerated Concrete Blocks likes these https://www.travisperkins.co.uk/H+H...0mm/p/700055?gclid=CPui0JTKl9ICFfYK0wodPacBPg
> 
> I'm told these properties were built in the 1970's, which might narrow down the materials that were used but probably isn't that much help.
> 
> I'm sure the noise does simply transfer from one side of the party wall to the other but it's also definitely flanking into the other three walls, as it can be heard almost as loudly in them. Likewise with the noise from upstairs, which may be originally travelling down one wall and then flanking into the other walls, or maybe through the concrete slab (i.e. my ceiling) that's under their floor and from there into the walls. I'll knock up a rough diagram to illustrate the suspected noise paths when I have time, as it's probably easier to show them rather than try and describe them.


That's ok. No need for a diagram. I understand. Bottom line is you appear have noise pollution getting in from something porous, and/or flanking in addition.




> As you say, the stud walls will be spaced 10mm from the original stripped-back walls, so there's no concerns about moisture there. However, as I understand it the stud wall only has a bead of mastic on the side edges to isolate it from the side walls, so if they're concrete (as opposed to cinder/ash block) maybe that's close enough for moisture to be an issue?
> 
> I'm not sure why it's OK to only have a thin bead of mastic separating the studs from the side walls when I need a 10mm air gap behind the stud wall. I guess this wouldn't matter if only the wall behind was problematic but when flanking is causing the end walls to leak/transmit as badly as the wall the stud is being built in front of, then I'd think I'd need a 10mm gap on the sides as well but that's not really practical as the wall needs to be supported.


The mastic bead you described above should solve any potential moisture issue. However, it will be insufficient for proper isolation and de-coupling. You need that 10mm gap. You can still support the walls by attaching them to the main structure via IB-3 clips or IB-2 clips or a similar product. One end is screwed thoroughly into your structural support, and the other end is screwed into a stud. You should only need ~every meter or so. They will stiffen your inner walls sufficiently.




> The ceiling's quite low already and it will be even lower when I add the independent ceiling so I need to try and minimise any increase in floor elevation. If I do replace the sub-floor, which will probably be the easiest way to sort out the unevenness, then the U-boats look like my best option, along with some rockwall slabs wedged in between the joists, although I like the hockey pucks idea.


That sounds good. You are better off going with a simple approach for the floor and keeping the ceiling joists independent of the structure.




> I don't really understand the Kinetics RIM PDF, as it seems to show it stuffed between the joists, like rockwool, with sleepers resting directly on the joists and 2 layers of plywood sub-floor on top of the sleepers, so there doesn't seem to be anything to stop impact noise transmitting from the subfloor through the sleepers and joists to the concrete structural floor.


The RIM lays directly on the concrete floor. The sleepers lay on top of the RIM. The purpose of the sleepers is to provide less surface area contacting the RIM. The RIM is designed to absorb airborne and impact noise. You can do it without the sleepers, but the sleepers reduce the area touching your subfloor. No harm in doing U-boats or hockey pucks though. I'd suggest the U-boats in your situation. They will still transmit some sound, but it's a very small point of contact for each U-boat. You could consider a thick carpet pad under the cork flooring, depending on your tolerance for increasing the floor height. I would also suggest 2x layers of sub-floor wood (plywood, OSB, or whatever you use).




> In my room it may be that any noise from downstairs is coming up the walls rather than up through downstairs' concrete ceiling, in which case fitting perimeter isolation board and sealant and maybe a few inches deep of rockwool slab around the perimeter might be sufficient to keep the noise from getting into the under-floor space.


Make sure you don't compromise your 10mm gap around the walls and between the independent ceiling and original ceiling.




> ... in which case the only part of the stud that's close to concrete (but still separated from it by a layer of paint and plaster) would be the part that's joined to the ceiling.


As stated above, you want to ensure you have that 10mm gap all around. The IB clips should allow that and maintain rigidity of the inner (new) framing.


----------



## doveman

HT Geek said:


> The mastic bead you described above should solve any potential moisture issue. However, it will be insufficient for proper isolation and de-coupling. You need that 10mm gap. You can still support the walls by attaching them to the main structure via IB-3 clips or IB-2 clips or a similar product. One end is screwed thoroughly into your structural support, and the other end is screwed into a stud. You should only need ~every meter or so. They will stiffen your inner walls sufficiently.


I don't really see how it can be OK to have the 10mm gap compromised by clips connecting the original wall to the stud wall. I would have thought that, following the water leak analogy, if there's a single connection anywhere the sound is going to travel across that, even if the rest of the wall is decoupled. Certainly this page shows the stud wall decoupled and says "The stud work should not touch the offending wall at any point, and should be affixed to adjacent walls floor and ceiling." http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_3.php

Obviously it's more complicated in my case where there's issues with the adjacent walls and ceiling (and possibly the floor but that's probably minor compared to the other surfaces) because as you say, the stud wall needs to be sufficiently stiffened and has to be attached to something. I can see how the long part of the clips could be attached to the adjacent walls, with the short part attached to the top plate of the stud wall with that sitting 10mm below the ceiling, which would give me a gap on the sides and at the top but then the plasterboard in front of the stud wall has to extend all the way to the original walls, with just a thin bead of mastic decoupling it, which would seem to make it pointless leaving a 10mm gap at the sides and above the stud wall.

If I build the inner end walls first then the plasterboard part of these will only be decoupled from the adjacent long walls by a bead of mastic but when I build the inner long walls these will end inside the inner end walls giving me approx. 100mm gap from the original adjacent (end) walls but then I can't secure the long walls to the original adjacent walls, only to the new plasterboard walls (and the ceiling and the floor joists).

In the attached diagram, I've indicated in red the approx. 4cm I might be able to reclaim by stripping back the plaster from the walls; green shows the new end walls built first, extending all the way (minus a bit of mastic) to the long walls; blue shows the new long walls built inside the end walls; black shows a possible new partition wall with door I might install to deal with the problem of noise leaking via the original door and yellow just indicates the brick/concrete of the exterior wall which the window is fitted into.

I'm not sure where I'd secure the ceiling joists to within that scheme, as I wouldn't have thought the new plasterboard walls would be strong enough to support the joists and everything else that makes up the independent ceiling, as shown here http://www.soundstop.co.uk/solutions/ceiling_access/ceiling_solution_4.php . So I'm wondering if I need to strip the plaster off the walls, build the independent ceiling with the joists attached to the concrete/cinder block walls, then build the new walls up to the new ceiling? Whilst that isn't ideal as it runs the risk of noise from the walls travelling into the new ceiling joists, perhaps the resilient bars between the joists and the plasterboard will be sufficient to stop that noise being heard through the new ceiling?

I'm also wondering about treating the other side of the dividing wall (the bottom one in the diagram, the top one being the party wall), which is in my living room. I understand it's recommended to only have an air gap on one side of a wall and in any case I'm limited in how much I can increase the depth on the other side as there's doors at each end, as shown in the attached photos, so I could only increase the depth by about 3.5cm, giving me a total of about 7cm to play with after stripping off the plaster. Even if it's not going to make much difference to how soundproofed the HT side of the wall will be (both in preventing my noise disturbing my neighbours and vice-versa), it may still be worth doing as a) that wall is probably the most problematic of the walls in the living room and b) it might be useful to see what improvements I can achieve without having the space for a full independent wall. For example, 1) just two layers of acoustic plasterboard attached directly to the cinder block in place of the existing plaster, 2) resilient bars attached to the cinder block with two layers of acoustic plasterboard attached, 3) some sort of rubber mat attached to the cinder block, with two layers of acoustic plasterboard on top like this http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_4.php .

I'm thinking I wouldn't have to do the whole wall. I could just try a square foot of each method and when I hear noise from the neighbours I can stick one ear against each section and block the other ear to see how effective they are.


----------



## HT Geek

doveman said:


> I don't really see how it can be OK to have the 10mm gap compromised by clips connecting the original wall to the stud wall. I would have thought that, following the water leak analogy, if there's a single connection anywhere the sound is going to travel across that, even if the rest of the wall is decoupled. Certainly this page shows the stud wall decoupled and says "The stud work should not touch the offending wall at any point, and should be affixed to adjacent walls floor and ceiling." http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_3.php


I understand your confusion. Reading the post that excerpt came from, it sounds as if the author is talking about isolating only a single wall. That might not be true. Might be my interpretation of his/her language or that I'm reading it out of context. No matter. First, you can theoretically leave one wall completely floating and have the other three walls secured with IB brackets or a similar system, however at least in the USA you would be violating building codes. You need to physically and structurally support your inner stud walls, ceiling, and floor one way or another. 

The IB brackets are a compromise in the sense that you are creating a handful of points at which your inner and outer walls touch. However, they are designed for this purpose. One end has a thick rubber grommet. The purpose of the rubber is to act as a shock absorber. You want your inner walls to flex minutely with the pressure from sound waves, and these plus the gap between inner and outer walls allows the inner walls to flex a bit without passing the full energy on to the outer (structural) walls.

Now, imagine if you built your room-within-a-room and did not affix the inner walls, ceiling, and floor to anything. Obviously, it would have to levitate for starters. Let's presume the floor is affixed but nothing else. You will have a set of walls and ceiling that won't pass a building code inspection, likely won't be plumb or level, and may sway if pressure is applied at one point or another.

It would theoretically be ideal to have such an inner room (with no contact whatsoever with the outer walls), but in a practical application it's not realistic. Thus, the combination of an air gap and IB or similar brackets are the next best thing. The floor is usually the most difficult surface to isolate if the room is not on a ground floor. And ceilings are often an issue as well due to height restrictions.




> Obviously it's more complicated in my case where there's issues with the adjacent walls and ceiling (and possibly the floor but that's probably minor compared to the other surfaces) because as you say, the stud wall needs to be sufficiently stiffened and has to be attached to something. I can see how the long part of the clips could be attached to the adjacent walls, with the short part attached to the top plate of the stud wall with that sitting 10mm below the ceiling, which would give me a gap on the sides and at the top...


You can install the clips either way, and either horizontally or vertically. 




> ... but then the plasterboard in front of the stud wall has to extend all the way to the original walls, with just a thin bead of mastic decoupling it, which would seem to make it pointless leaving a 10mm gap at the sides and above the stud wall.


I'm not sure what you mean by that. By, 'in front of the wall,' are you referring to the plasterboard currently attached to the existing walls? My understanding is you are planning to remove that, taking you down to your bare studs.




> If I build the inner end walls first then the plasterboard part of these will only be decoupled from the adjacent long walls by a bead of mastic but when I build the inner long walls these will end inside the inner end walls giving me approx. 100mm gap from the original adjacent (end) walls but then I can't secure the long walls to the original adjacent walls, only to the new plasterboard walls (and the ceiling and the floor joists).
> 
> In the attached diagram, I've indicated in red the approx. 4cm I might be able to reclaim by stripping back the plaster from the walls; green shows the new end walls built first, extending all the way (minus a bit of mastic) to the long walls; blue shows the new long walls built inside the end walls; black shows a possible new partition wall with door I might install to deal with the problem of noise leaking via the original door and yellow just indicates the brick/concrete of the exterior wall which the window is fitted into.


I believe I’m seeing the disconnect here. After re-reading a few posts above, perhaps I wasn’t clear on construction of the inner stud walls. The inner walls require an air gap on all sides. That includes the wall with your balcony door. It’s also important to first strip off the plaster inside the room on your walls and ceiling that you have now, to avoid creating a triple-leaf effect.

So, with the existing walls stripped, when you frame the inner wall, you will be able to attach it to the outer (original) stud wall via the IB brackets.



> I'm not sure where I'd secure the ceiling joists to within that scheme, as I wouldn't have thought the new plasterboard walls would be strong enough to support the joists and everything else that makes up the independent ceiling, as shown here http://www.soundstop.co.uk/solutions/ceiling_access/ceiling_solution_4.php


Correct. They won’t be. However, in addition to securing the walls (via IB brackets), you should also secure the footers of the walls to the structural floor. Your floating ceiling will be fine as long as it is secured on either end to the inner wall studs.




> . So I'm wondering if I need to strip the plaster off the walls, build the independent ceiling with the joists attached to the concrete/cinder block walls, then build the new walls up to the new ceiling?


No, no! Build the new floor, then frame the walls, then the ceiling.




> Whilst that isn't ideal as it runs the risk of noise from the walls travelling into the new ceiling joists, perhaps the resilient bars between the joists and the plasterboard will be sufficient to stop that noise being heard through the new ceiling?


You could use clips and hat channel to de-couple your ceiling, but you are better off going with an independent, floating ceiling instead since you’re able to do so.

Your independent ceiling joists will be supported on either end by the inner stud walls. This is an area where you will need to do some engineering calculations (or consult with an engineer, or use look-up tables) to determine what dimensions of wood or steel joists you need, depending on the distance spanned.




> I'm also wondering about treating the other side of the dividing wall (the bottom one in the diagram, the top one being the party wall), which is in my living room. I understand it's recommended to only have an air gap on one side of a wall and in any case I'm limited in how much I can increase the depth on the other side as there's doors at each end, as shown in the attached photos, so I could only increase the depth by about 3.5cm, giving me a total of about 7cm to play with after stripping off the plaster. Even if it's not going to make much difference to how soundproofed the HT side of the wall will be (both in preventing my noise disturbing my neighbours and vice-versa), it may still be worth doing as ….


Nothing wrong with adding an additional layer of plasterboard on the _other _side of the wall (i.e. non-HT room side). Just don’t introduce an additional air gap there.




> I'm thinking I wouldn't have to do the whole wall. I could just try a square foot of each method and when I hear noise from the neighbours I can stick one ear against each section and block the other ear to see how effective they are.


That won’t work. The effects from one will cross-contaminate the other samples. You won’t get an accurate prediction of doing the whole wall via one method or another. That would require either trial-and-error or a lab. Also, if you don’t do the entire wall then don’t bother as the non-treated portion will circumvent the treated area (i.e. no benefit).


----------



## doveman

HT Geek said:


> I understand your confusion. Reading the post that excerpt came from, it sounds as if the author is talking about isolating only a single wall. That might not be true. Might be my interpretation of his/her language or that I'm reading it out of context. No matter. First, you can theoretically leave one wall completely floating and have the other three walls secured with IB brackets or a similar system, however at least in the USA you would be violating building codes. You need to physically and structurally support your inner stud walls, ceiling, and floor one way or another.
> 
> The IB brackets are a compromise in the sense that you are creating a handful of points at which your inner and outer walls touch. However, they are designed for this purpose. One end has a thick rubber grommet. The purpose of the rubber is to act as a shock absorber. You want your inner walls to flex minutely with the pressure from sound waves, and these plus the gap between inner and outer walls allows the inner walls to flex a bit without passing the full energy on to the outer (structural) walls.
> 
> Now, imagine if you built your room-within-a-room and did not affix the inner walls, ceiling, and floor to anything. Obviously, it would have to levitate for starters. Let's presume the floor is affixed but nothing else. You will have a set of walls and ceiling that won't pass a building code inspection, likely won't be plumb or level, and may sway if pressure is applied at one point or another.
> 
> It would theoretically be ideal to have such an inner room (with no contact whatsoever with the outer walls), but in a practical application it's not realistic. Thus, the combination of an air gap and IB or similar brackets are the next best thing. The floor is usually the most difficult surface to isolate if the room is not on a ground floor. And ceilings are often an issue as well due to height restrictions.


The impression I got from the page I linked to (and other sources) was that the new wall should be fixed to the floor, ceiling and adjacent walls but not the wall it's built in front of. I did wonder about the stability of such a wall though and how it would withstand pressure/weight against it.



> You can install the clips either way, and either horizontally or vertically.


The clips are L-shaped, so I can see how I could screw the long part to the original wall and the rubber part to the top of a horizontal noggin in my stud wall but I can't see how they'd go between the original wall and the vertical studs. I've attached a rough diagram showing 0.75mm vertical studs spaced 600mm apart (maybe 400mm would be better?) on one wall (I haven't drawn any horizontal noggins but I guess I'll probably need a couple of runs of these roughly dividing the 3m high wall into thirds. 

I understand when building a normal stud wall you'd have a floor plate and ceiling plate which the vertical studs are fixed to but for soundproofing purposes I presume we need to avoid this but we still need to secure them somehow to the floor and ceiling. I guess with the L-shaped clips the long part could be screwed to the back of the vertical studs and the rubber part then screwed to the ceiling or the floor joists. Perhaps for the adjacent walls the rubber part could be screwed to the wall with it orientated so that the long part lies horizontally behind the vertical stud and is screwed to that.

I'm also wondering how I'd treat the corner section of the wall, as shown in the lower right of the diagram. It's about 190mm deep, so I guess I could fit a single 75mm vertical stud in the middle of that space. Cutting the plasterboard will be fiddly and I don't think I'll be able to stagger the seams between the two layers horizontally, as 190mm isn't really enough space to divide each layer into more than one piece but I can still stagger the vertical seams.



> I'm not sure what you mean by that. By, 'in front of the wall,' are you referring to the plasterboard currently attached to the existing walls? My understanding is you are planning to remove that, taking you down to your bare studs.


Currently I have 3.5-4cm of plaster (not plasterboard) on top of cinderblock (so no studs). What I meant was, even if I leave a 10mm gap between the adjacent walls and the first vertical studs and even if I use clips to create a 10mm gap between the top and bottom of the vertical studs and the ceiling and floor, when I fit the plasterboard on top that will have to extend all the way to the adjacent walls, ceiling and floor, apart from a thin bead of mastic. I don't think you could leave a 10mm gap around all the edges of the plasterboard and fill that with mastic as it would look terrible, if it's even practical to create such a thick layer of mastic. It would seem to defeat the point of separating the joists from all the surrounding surfaces by 10mm if the plasterboard on top then has less separation from those surfaces, as any noise in the ceiling, floor or adjacent walls will surely then transfer into the plasterboard, which is the part of the new wall that's nearest to the interior of the room, so I would think noise transference into that is of greater concern than noise transferring into the studs, which are separated from the interior of the room by resilient channels and two layers of plasterboard.



> I believe I’m seeing the disconnect here. After re-reading a few posts above, perhaps I wasn’t clear on construction of the inner stud walls. The inner walls require an air gap on all sides. That includes the wall with your balcony door. It’s also important to first strip off the plaster inside the room on your walls and ceiling that you have now, to avoid creating a triple-leaf effect.
> 
> So, with the existing walls stripped, when you frame the inner wall, you will be able to attach it to the outer (original) stud wall via the IB brackets.


I think I've confused you with all my photos but the balcony door is on the living room side of the dividing wall, the HT room only has a single door to the hallway and a window. I've attached a sketch showing the junction of the window wall (green) and the adjacent long wall. Assume the green part is the plasterboard layers and the studs (which I haven't drawn) are behind it and start 10mm in from the adjacent long walls. In the sketch I've drawn the plasterboard layer extending all the way to the cinderblock of the stripped back long walls but I guess this isn't really necessary, as the new wall in front of the long walls is 100m deep and so will overlay the edges of the new window wall, as shown in the sketch, so the window wall plasterboard can stop 10mm (or more) from the cinderblock as it won't be visible.

However, as discussed above, I can't see how I can leave a 10mm air gap between the plasterboard and the ceiling and floor.



> Correct. They won’t be. However, in addition to securing the walls (via IB brackets), you should also secure the footers of the walls to the structural floor. Your floating ceiling will be fine as long as it is secured on either end to the inner wall studs.


I presume you mean secure the vertical studs to the floor joists with IB clips or similar? So if my vertical wall studs are spaced 400mm apart, then I would have my floating ceiling joists at the same spacing and secured to my vertical wall studs? Would this then make my walls (at least the long ones which the ceiling joists will be attached to) load-bearing, as this will probably mean I need to take more care to ensure they're designed to support the weight of the ceiling?



> No, no! Build the new floor, then frame the walls, then the ceiling.


OK. I was just thinking that building the ceiling first and attaching it to the cinderblock would mean the weight of it is not being borne by the new stud walls and would also ensure the plasterboard layers of the new walls are separated from the original ceiling (by the height of the floating ceiling), so a thin bead of mastic between the walls and the ceiling would be OK in that situation.



> You could use clips and hat channel to de-couple your ceiling, but you are better off going with an independent, floating ceiling instead since you’re able to do so.
> 
> Your independent ceiling joists will be supported on either end by the inner stud walls. This is an area where you will need to do some engineering calculations (or consult with an engineer, or use look-up tables) to determine what dimensions of wood or steel joists you need, depending on the distance spanned.


Yeah, I think I'll need an engineer to make sure I get that right. I'm not really sure how an independent floating ceiling attached to the new wall joists would differ from one attached to the original walls. I guess the solution shown here http://www.soundstop.co.uk/solutions/ceiling_access/ceiling_solution_4.php is designed for when just the ceiling is being treated and because the joists are attached to the original walls, the resilient channel is needed to stop noise transferring from the walls to the plasterboard via the joists. If I'm suspending my floating ceiling from my new wall joists however, there shouldn't be any risk of noise transferring from the wall joists into the ceiling joists, so maybe the resilient channel is unnecessary.



> Nothing wrong with adding an additional layer of plasterboard on the _other _side of the wall (i.e. non-HT room side). Just don’t introduce an additional air gap there.


Understood. Are two layers of acoustic plasterboard likely to perform much better than the current two layers of plaster (one thick and a thinner skim coat) totalling about 3.5-4cm? I'm thinking that even using resilient channels will create an air gap between the cinderblock and the plasterboard, so my options might be limited to two layers of plasterboard attached to the cinderblock, or the same but with rubber mat between the cinderblock and the plasterboard.



> That won’t work. The effects from one will cross-contaminate the other samples. You won’t get an accurate prediction of doing the whole wall via one method or another. That would require either trial-and-error or a lab. Also, if you don’t do the entire wall then don’t bother as the non-treated portion will circumvent the treated area (i.e. no benefit).


I'd separate everything as much as possilbe, so I'd strip about 1m2 of the existing plaster back to the cinderblock, then in that space fit one 30cm2 section of two layers of plasterboard attached directly to the cinderblock and another 30cm2 section of rubber mat with two layers of plasterboard on top, with a gap around both sections separating them from each other and from the surrounding plaster which I haven't stripped away. Now I realise this won't give accurate results, as the edges of the plasterboard will be exposed to sound emanating from the wall (both the exposed cinderblock part and the plaster covered part) which they wouldn't be if the entire wall was covered with plasterboard but it will hopefully provide some idea of what to expect, in the same way that holding a pillow, a piece of carpet or rubber mat up to the wall and seeing how these affect the sound compared to the bare wall does.

I guess if I decide to go ahead and treat the living room wall I'll have to remove the hallway door and trim first, as that is nailed/screwed to the wall and if I don't replace the plaster in that section with plasterboard (+rubber mat maybe) then the sound in the wall will escape via the door trim and circumvent all the treatment to the rest of the wall?

I'm a bit concerned about how much weight plasterboard can handle compared to plaster. Perhaps the door trim is even fixed to the cinderblock under the plaster to better support it's weight. If I were to fix my plasma TV to the current walls I'd probably ensure the rawlplugs were buried in the cinderblock to make sure it didn't fall off if the plaster failed. I had a clothes rail attached to one of my walls which obviously had too much weight on it as it pulled all the rawlplugs out one night. After that I reduced the weight and reattached it with longer screws which go into the cinderblock and it's been fine since. However I know that nailing/screwing anything through the acoustic plasterboard layers of my new walls into the cinderblock will undermine the soundproofing, so will I just have to avoid attaching anything heavy to the living room wall after I've replaced the plaster with plasterboard? 

As for the HT room, I understand that with a normal stud wall one would fix horizontal noggins between the vertical studs and attach heavy stuff to the noggins but with a soundproofed wall we can't screw through the plasterboard into the stud wall, so do we just have to avoid attaching anything heavy like TVs, speakers, etc to the walls?


----------



## HT Geek

doveman said:


> The impression I got from the page I linked to (and other sources) was that the new wall should be fixed to the floor, ceiling and adjacent walls but not the wall it's built in front of. I did wonder about the stability of such a wall though and how it would withstand pressure/weight against it.


Attach the IB ("L" shaped) clips to the header board. It is not necessary to attach it to the studs. By only attaching it to the header board, you will minimize the points connecting the two walls. You only need them about 1 every meter. Also bolt your inner footer board to the floor. 




> I can't see how I can leave a 10mm air gap between the plasterboard and the ceiling and floor.


Correct. They won’t be. You want a 10mm air gap between each stud wall in a double-stud wall configuration. That's where the air gap goes - between your HT room walls/ceiling and any other surface (such as the outer stud wall). The floor can be dampened in a myriad of ways, as discussed previously in this thread.

Aside from securing the walls (via IB brackets), you should secure the footers of the walls to the structural floor. Your floating ceiling will be fine as long as it is secured on either end to the inner wall studs.




> I presume you mean secure the vertical studs to the floor joists with IB clips or similar? So if my vertical wall studs are spaced 400mm apart, then I would have my floating ceiling joists at the same spacing and secured to my vertical wall studs? Would this then make my walls (at least the long ones which the ceiling joists will be attached to) load-bearing, as this will probably mean I need to take more care to ensure they're designed to support the weight of the ceiling?


No, no. That's overkill. You only need the IB clips at the top, securing your header plate to the structural (outer) stud wall. And you can secure the inner wall header to either vertical studs or the outer wall's header. Doesn't matter (though attaching to the other header is likely to be easier for the most part).




> OK. I was just thinking that building the ceiling first and attaching it to the cinderblock would mean the weight of it is not being borne by the new stud walls and would also ensure the plasterboard layers of the new walls are separated from the original ceiling (by the height of the floating ceiling), so a thin bead of mastic between the walls and the ceiling would be OK in that situation.


Your inner floor and walls will hold up the inner ceiling joists just fine, as long as you properly secure the inner flooring, footer, and studs.




> Yeah, I think I'll need an engineer to make sure I get that right. I'm not really sure how an independent floating ceiling attached to the new wall joists would differ from one attached to the original walls.


Big difference. You don't want your inner ceiling joists attached directly to the original walls or ceiling joists or you will re-couple them. By that I mean you use the IB clips, which while technically creates a few small areas of coupling, that is reduced by the design of the clips so it's really not being re-coupled when using the IB clips.




> ... the resilient channel is needed to stop noise transferring from the walls to the plasterboard via the joists. If I'm suspending my floating ceiling from my new wall joists however, there shouldn't be any risk of noise transferring from the wall joists into the ceiling joists, so maybe the resilient channel is unnecessary.


The use of RC or hat channel (preferable) is when you choose not to use independent or staggered stud walls for whatever reason. The methods are mutually exclusive (channel vs. staggered or double stud walls).




> Are two layers of acoustic plasterboard likely to perform much better than the current two layers of plaster (one thick and a thinner skim coat) totalling about 3.5-4cm?


That depends on the acoustic properties of one set of materials versus another, and which frequencies you are most concerned with dampening. You would need to know the properties of either set of materials and once you have that information it's up to you to decide if a trade-off is warranted, based on your goals and preferences.

Basically, I can't answer your question without knowing which products you're referring to that you might theoretically replace the existing layers.




> I guess if I decide to go ahead and treat the living room wall I'll have to remove the hallway door and trim first, as that is nailed/screwed to the wall and if I don't replace the plaster in that section with plasterboard (+rubber mat maybe) then the sound in the wall will escape via the door trim and circumvent all the treatment to the rest of the wall?


Your best bet is to gut the entire space and start with a blank canvas. Doing so allows you to see everything that you can't see right now (behind the existing wall veneer). That will make your life easier versus uncovering the mystery one area at a time, which is a process more likely to push discoveries forward in time, after you've begun the project. Put another way, doing it piecemeal is more likely to result in re-doing portions of the project, whereas stripping away everything in the beginning allows you to see where all your pitfalls are going to be and address them cohesively, at the start.




> I'm a bit concerned about how much weight plasterboard can handle compared to plaster. Perhaps the door trim is even fixed to the cinderblock under the plaster to better support it's weight.


If the HT room and Living Room will share a wall, that wall needs to be a double-stud wall. Otherwise you are going to get unwanted sound leakage between the two areas. On the living room side of the double wall, simply arrange that (living room side) stud wall with sufficient vertical or lateral supports to handle your TV or anything else you know will be hung from the living room side wall.




> As for the HT room, I understand that with a normal stud wall one would fix horizontal noggins between the vertical studs and attach heavy stuff to the noggins but with a soundproofed wall we can't screw through the plasterboard into the stud wall, so do we just have to avoid attaching anything heavy like TVs, speakers, etc to the walls?


You can certainly do that. Many people do. For instance, hanging fabric panels, securing columns to walls, etc. You want to minimize holes, such as recessed lighting holes, etc. Even then, you can build backer boxes behind them in the ceiling which effectively re-seals the gap.


----------



## doveman

HT Geek said:


> Attach the IB ("L" shaped) clips to the header board. It is not necessary to attach it to the studs. By only attaching it to the header board, you will minimize the points connecting the two walls. You only need them about 1 every meter. Also bolt your inner footer board to the floor.


OK. Just to make sure we're on the same page, I found this image of a stud wall (sorry, I couldn't find anything better with labels) https://s-media-cache-ak0.pinimg.com/originals/55/2f/ea/552feadf7047d00b655c3d4df0326dee.jpg I presume "header board" is what the image calls the "top plate"? So I'd have one part of the IB clips attached to the original cinderblock wall and the other part attached to the top of the header board, which is spaced 10mm down from the ceiling and secured by the IB clips instead of being screwed to the ceiling as in a normal stud wall?

Is "footer board" the same as "bottom plate"? I was going to fix this to the floor joists which I would leave exposed where the bottom plate goes, as I'd read that this is recommended and it seems like it might be a bit more secure than fixing it to the floorboards.



> Correct. They won’t be. You want a 10mm air gap between each stud wall in a double-stud wall configuration. That's where the air gap goes - between your HT room walls/ceiling and any other surface (such as the outer stud wall). The floor can be dampened in a myriad of ways, as discussed previously in this thread.


I'm not sure what you mean by double-stud wall or outer stud wall but I'm only going to have one stud wall, spaced 10mm off the original cinderblock wall. You say there won't be a 10mm gap between the plasterboard and the floor and ceiling but then say there _should_ be such a gap between the HT room walls (i.e the plasterboard) and any other surface (which includes the floor and ceiling), so I'm rather confused. I understand that the plasterboard being in contact with the floor isn't so important if I've built a new soundproofed floor first but it will be the original ceiling I'm building the walls up to, with the floating ceiling added last. Whilst I could stop the plasterboard walls short of the ceiling, whether 10mm or however high the floating ceiling will be (maybe as much as 7") because that section of the walls will be hidden under the ceiling when it's built but until then, leaving a gap with no plasterboard at the top of the walls would seem to defeat the purpose of the walls.



> Aside from securing the walls (via IB brackets), you should secure the footers of the walls to the structural floor. Your floating ceiling will be fine as long as it is secured on either end to the inner wall studs.


Just to check again, by "footers of the walls" secured to the structural floor do you mean the bottom plate fixed to the floor joists?



> No, no. That's overkill. You only need the IB clips at the top, securing your header plate to the structural (outer) stud wall. And you can secure the inner wall header to either vertical studs or the outer wall's header. Doesn't matter (though attaching to the other header is likely to be easier for the most part).


Sorry, you've lost me here. I don't know what you mean by secure the header plate to the structural (outer) stud wall, as there's only going to be one stud wall and the header/top plate is a fundamental part of that so it obviously has to be secured to the rest of it (i.e. the vertical joists/studs, including the ones on each end, which the picture I linked to calls "wall studs"). I'm confused by your reference to inner and outer wall headers too.



> Your inner floor and walls will hold up the inner ceiling joists just fine, as long as you properly secure the inner flooring, footer, and studs.


I haven't decided whether I'm going to use timber or metal for the stud walls yet but even if I use timber, maybe it would be best to use metal for the ceiling to minimse the weight?



> That depends on the acoustic properties of one set of materials versus another, and which frequencies you are most concerned with dampening. You would need to know the properties of either set of materials and once you have that information it's up to you to decide if a trade-off is warranted, based on your goals and preferences.
> 
> Basically, I can't answer your question without knowing which products you're referring to that you might theoretically replace the existing layers.


The troublesome frequencies are mostly mid to high, such as loud voices, TV (no low frequencies, again just voices and music from TV speakers). There might be some impact noises entering the wall from where it's connected to the laminate flooring upstairs but I'm not overly concerned with that in the Living Room. I'm not entirely sure what materials I can use yet. As I only really have about 3.5cm depth to play with once the two layers of plaster are stripped off, I was thinking of 19mm acoustic plasterboard with 12mm acoustic plasterboard on top, which comes to 3.1cm. I thought acoustic plasterboard was a specific product with known properties but maybe it's a generic term and there's lots of different types? I think I could get away with building over the door trim, which would give me another 3-3.5cm, so that would allow me to fix some 7/8" hat channel like this http://www.clarkdietrich.com/products/drywall-framing/furring-channel-hat-channel to the wall and fix the plasterboard to that. As I mentioned before though, I'm concerned that this would create an air gap between the cinderblock wall and the plasterboard, thus violating the rule that only one side of a wall should have an airgap (once I build the stud wall on the HT side of the wall).

Acousticblock looks interesting and is only 1/8" thick http://www.acoustiblok.com/products.php but I don't know how much it costs yet and installation looks tricky due to the weight http://www.acoustiblok.com/instal.php

There's also panels like these http://www.noisestopsystems.co.uk/wall-soundproofing/nssw1-soundproofing-wall-board but it's hard to trust the specs when one part of the blurb says 8db reduction and another says 31db and they haven't been independently tested like Acousticblock. This is a thicker sandwich panel http://www.noisestopsystems.co.uk/wall-soundproofing/nssw2-plus-soundproofing-wall-board . From what I've read, if I'm going to use a layer of insulation the products marketed for this purpose aren't really any better than Rockwool, so there's no point paying extra for them.



> Your best bet is to gut the entire space and start with a blank canvas. Doing so allows you to see everything that you can't see right now (behind the existing wall veneer). That will make your life easier versus uncovering the mystery one area at a time, which is a process more likely to push discoveries forward in time, after you've begun the project. Put another way, doing it piecemeal is more likely to result in re-doing portions of the project, whereas stripping away everything in the beginning allows you to see where all your pitfalls are going to be and address them cohesively, at the start.


Whilst that might be ideal, if I strip away the door trim then I can only build the new wall in that area to the same depth as it currently is, otherwise there won't be room for the door. So perhaps there's little benefit from doing that, as I could only do something like fit 7/8" hat channel and one layer of 12mm plasterboard, assuming the hat channel will be strong enough to support the door trim with the hinges attached and thus the weight of the door. I could still build the rest of the wall deeper, with hat channel and two layers of plasterboard, so that it covers the door trim as described above but it depends whether the shallower area under the door trim will undermine my efforts.



> If the HT room and Living Room will share a wall, that wall needs to be a double-stud wall. Otherwise you are going to get unwanted sound leakage between the two areas. On the living room side of the double wall, simply arrange that (living room side) stud wall with sufficient vertical or lateral supports to handle your TV or anything else you know will be hung from the living room side wall.


Unfortunately there's simply not enough room on the Living Room side to build a stud wall. Presumably this would be fixed directly to the original cinderblock wall to avoid having an airgap on both sides but even then, it would be 50mm and even with the new wall covering the door trim the maximum depth I could have it is 65-70mm, so there'd be insufficient space left for hat channel and one layer of 12mm plasterboard, let alone two.


----------



## HT Geek

doveman said:


> OK. Just to make sure we're on the same page, I found this image of a stud wall (sorry, I couldn't find anything better with labels) https://s-media-cache-ak0.pinimg.com/originals/55/2f/ea/552feadf7047d00b655c3d4df0326dee.jpg I presume "header board" is what the image calls the "top plate"?


Yes, correct.




> So I'd have one part of the IB clips attached to the original cinderblock wall and the other part attached to the top of the header board, which is spaced 10mm down from the ceiling and secured by the IB clips instead of being screwed to the ceiling as in a normal stud wall?


Not quite. You could attach the IB clips to the top of the header board, but it's more common for it to be attached to the _side _of the header board or side of a few studs. It just depends on which method makes more sense for your application. The point is to secure your inner wall to the outer (structural) wall using the IB clips. AND you want that 10mm gap from the ceiling to exist AFTER you have installed new ceiling joists for your room-within-a-room. 

Let's say you build a double stud wall, and you anchor your inner wall to the outer wall via IB clips attached to the header. Well, first off you should use a double header. Reason is because when you install 2x drywall/plasterboard layers inside the room, you will need to ensure you have sufficient height of the top header to screw your staggered wall board layers into the header. So, at that point you then have 3" of wood to secure the side of your IB clip to the side of the header board(s).

Second (and more pertinent to your question above), you want a gap between your ceiling joists and the structural ceiling above (or floor of the room above). That gap needs to exist after you install your ceiling joists, which will be secured to the inner stud walls. Therefore, when calculating the height of your studs for your inner wall, you will need to take into consideration the total room height, minus the height of your air gap + header and footer board heights for your stud walls + ceiling joist height, so that a clearance (gap) is maintained between the top of the inner room's ceiling joists and the floor of the next level above it.

As an example, let's say (using American measurements) you decided on ceiling joists with a 12' wide span using 2x6 lumber. A 2x6 laid on its strong side (for shear) is 5-1/2" tall (your joists must lay vertically). Since the header will support the ceiling joists, that results in the need for a gap of 6" in total height above the header (2x6 height [5-1/2"] + 1/2" gap [bit more than 10mm] because the ceiling joists will lay on top of the stud walls (of which the header board is the top most portion). So in that case the top of your header would be 6" below the top of the original room.




> Is "footer board" the same as "bottom plate"? I was going to fix this to the floor joists which I would leave exposed where the bottom plate goes, as I'd read that this is recommended and it seems like it might be a bit more secure than fixing it to the floorboards.


Yes, 'footer board' is the same thing as 'bottom plate.' However, you don't fix that to the floor joists (normally). You fix it to your sub-floor. Other methods may be possible, but make sure you adhere to building fire codes.




> I'm not sure what you mean by double-stud wall or outer stud wall but I'm only going to have one stud wall, spaced 10mm off the original cinderblock wall.


What you want to do is effectively the same thing. You're considering creating a "room within a room." The difference in your case is the outer or structural wall is concrete block (or whatever the material is) instead of a wood stud wall, but the de-coupling concepts are the same.




> You say there won't be a 10mm gap between the plasterboard and the floor and ceiling but then say there _should_ be such a gap between the HT room walls (i.e the plasterboard) and any other surface (which includes the floor and ceiling), so I'm rather confused. I understand that the plasterboard being in contact with the floor isn't so important if I've built a new soundproofed floor first but it will be the original ceiling I'm building the walls up to, with the floating ceiling added last. Whilst I could stop the plasterboard walls short of the ceiling, whether 10mm or however high the floating ceiling will be (maybe as much as 7") because that section of the walls will be hidden under the ceiling when it's built but until then, leaving a gap with no plasterboard at the top of the walls would seem to defeat the purpose of the walls.


Yes, I think we're not completely following one another. Let's try backing up a bit.

So, you will have a wood stud/ceiling joist "room within a room" or inner room, and this will be built inside an existing room with cinder block walls. Have I got that right?

Presuming that is correct, are the plasterboard walls you're talking about in the paragraph above on (or planned for) the outer wall (cinderblock)?

The idea is to leave a 10mm gap between all walls of the inner room and ceiling, and the original/outer/adjacent walls and ceiling. The floor is normally not much you can do about in terms of de-coupling, but it's ideal to dampen or de-couple the floor to whatever extent you can.

If you have plasterboard on the room's original (exterior to the HT shell) walls, then there would be a 10mm gap between the outer edge of your inside stud wall and that plasterboard. If you didn't have plasterboard on the cinderblock walls, that 10mm gap would be between the outer edge of your inside stud wall and the cinderblock. The point is to have an air gap between the surfaces.




> Just to check again, by "footers of the walls" secured to the structural floor do you mean the bottom plate fixed to the floor joists?


Normally it's the bottom plate fixed to the sub-floor.




> Sorry, you've lost me here. I don't know what you mean by secure the header plate to the structural (outer) stud wall, as there's only going to be one stud wall and the header/top plate is a fundamental part of that so it obviously has to be secured to the rest of it (i.e. the vertical joists/studs, including the ones on each end, which the picture I linked to calls "wall studs"). I'm confused by your reference to inner and outer wall headers too.


Hopefully the details I included above make this clearer. If I now understand you correctly, in your case you want to secure the stud walls that compose your inner room (or HT room shell) to the cinderblock that composes your 'outer' wall (and ceiling). 'Outer' just means the structural walls and ceiling or the existing walls/ceiling in the room. Your 'room within a room' build will create an 'inner' set of walls and ceiling.




> I haven't decided whether I'm going to use timber or metal for the stud walls yet but even if I use timber, maybe it would be best to use metal for the ceiling to minimse the weight?


There are various pros and cons to metal vs wood. Either way you will need to consult building codes and span tables for your ceiling joists. The span tables will allow you to cross reference joist span length, type, thickness, and weight bearing capability. You will need to calculate your anticipated ceiling load to make proper use of the tables. For example, 5/8" Type X drywall weighs 2.1 - 2.2 lb./sq. ft. So, if I had a 100 sq. ft ceiling then I know with 2x layers of 5/8" drywall, I need a minimum load bearing strength of the ceiling joists that will hold a total of 4.4 lb./sq. ft. 

I personally prefer to use engineering formulas, but the span tables (while rough and not completely accurate) are suited to most people because you don't have to deal with formulas and factoring all the details. The span tables are a generalization and allow a margin of error. Even if you do use formulas or hire an engineer, start with the tables as they will at least steer you in the right direction with regards to feasible sizes of lumber or metal joists for your particular needs (i.e. span distance and weight bearing).

The main advantages to metal studs are 1) they are always straight; and 2) support more weight than wood when comparing thinner materials (i.e. you can usually use narrower/thinner metal studs versus wood to support the same load). Wood studs are nearly always cheaper, and somewhat easier to work with.




> The troublesome frequencies are mostly mid to high, such as loud voices, TV (no low frequencies, again just voices and music from TV speakers). There might be some impact noises entering the wall from where it's connected to the laminate flooring upstairs but I'm not overly concerned with that in the Living Room. I'm not entirely sure what materials I can use yet. As I only really have about 3.5cm depth to play with once the two layers of plaster are stripped off, I was thinking of 19mm acoustic plasterboard with 12mm acoustic plasterboard on top, which comes to 3.1cm.


Even ordinary fiberglass insulation is quite effective at diminishing higher freqs such as human speech. Almost any insulating material should work well.




> I thought acoustic plasterboard was a specific product with known properties but maybe it's a generic term and there's lots of different types?


The latter. With any product you consider, make sure you view its acoustical properties. This is typically found under a heading such as "Technical Specifications," though sometimes it will appear in the MSDS. Some products are impossible to verify their acoustical properties. Avoid them.




> I think I could get away with building over the door trim, which would give me another 3-3.5cm, so that would allow me to fix some 7/8" hat channel like this http://www.clarkdietrich.com/products/drywall-framing/furring-channel-hat-channel to the wall and fix the plasterboard to that. As I mentioned before though, I'm concerned that this would create an air gap between the cinderblock wall and the plasterboard, thus violating the rule that only one side of a wall should have an airgap (once I build the stud wall on the HT side of the wall).


It's an either-or proposition between an inner stud wall versus hat channel + clips. With the latter you don't get a complete or true air gap, but the springiness and damping properties of the clips/channel combination more or less make up for it.




> Acousticblock looks interesting and is only 1/8" thick http://www.acoustiblok.com/products.php but I don't know how much it costs yet and installation looks tricky due to the weight http://www.acoustiblok.com/instal.php


I skimmed over the material, but I am not familiar with it or the company.




> There's also panels like these http://www.noisestopsystems.co.uk/wall-soundproofing/nssw1-soundproofing-wall-board but it's hard to trust the specs when one part of the blurb says 8db reduction and another says 31db and they haven't been independently tested like Acousticblock. This is a thicker sandwich panel http://www.noisestopsystems.co.uk/wall-soundproofing/nssw2-plus-soundproofing-wall-board . From what I've read, if I'm going to use a layer of insulation the products marketed for this purpose aren't really any better than Rockwool, so there's no point paying extra for them.


Those panels appear to be designed to act as your wall veneer (i.e. no drywall behind them).




> Whilst that might be ideal, if I strip away the door trim then I can only build the new wall in that area to the same depth as it currently is, otherwise there won't be room for the door. So perhaps there's little benefit from doing that, as I could only do something like fit 7/8" hat channel and one layer of 12mm plasterboard, assuming the hat channel will be strong enough to support the door trim with the hinges attached and thus the weight of the door. I could still build the rest of the wall deeper, with hat channel and two layers of plasterboard, so that it covers the door trim as described above but it depends whether the shallower area under the door trim will undermine my efforts.
> 
> 
> 
> Unfortunately there's simply not enough room on the Living Room side to build a stud wall. Presumably this would be fixed directly to the original cinderblock wall to avoid having an airgap on both sides but even then, it would be 50mm and even with the new wall covering the door trim the maximum depth I could have it is 65-70mm, so there'd be insufficient space left for hat channel and one layer of 12mm plasterboard, let alone two.


Could you use a slightly narrower door?


----------



## Ladeback

WOW! I just did a rough estimate on what it will cost to soundproof my theater with one layer of dry wall and GG between the joist, clips, hat channel, DD, GG, IB-3 type clips to decouple the walls already built and IB-3 type clips for backer boxes. Rough estimate between $3,000 to $4000 and I would still have to seal 2 doors.

I was going to just go with one layer of 5/8" dry wall and GG between the joist, will this help much? I am trying to save where I can and most of the time all of the family will be in the theater when watching a movie. The only time I would be in there alone is during sporting advents and I can hear my son playing above a little. I will also be insulating the walls and ceiling as well. 

Like I have said before on here it may save money to buy all at once, but it may be easier if i buy things and the this in steps. First would be adding the dry wall to the ceiling. Attached is what I was thinking of doing to the ceiling.

My steps would be:

1. Decouple walls
2. Add dry wall to ceiling for mass
3. Build backer boxes for lights and Atmos Speakers
4. Insulation in ceiling
5. Install clips and hat channel
6. Install DD with GG on ceiling
7. Insulation in walls
8. Install DD with GG on walls
9. Soundproofed doors

Am I missing any thing?


----------



## 2pacalypsenow

If the room I'm building a cinema on has 2 of the 4 walls made of concrete, would just applying dual layers with GG be enough? I'm just worried about the sound in the above rooms, not much about outside.


----------



## Ladeback

2pacalypsenow said:


> If the room I'm building a cinema on has 2 of the 4 walls made of concrete, would just applying dual layers with GG be enough? I'm just worried about the sound in the above rooms, not much about outside.


I was told the the sound would flank up the wall and would shake the floor above. I have experienced this in a few home theaters, but they had a LOT OF BASS if you know what I mean. I am building my theater in the basement and am going to go back and decouple the walls from the ceiling before I put up sheet rock. That can be done with IB-3 or like clips.

Read this from an earlier post on the forum about them. It is cheaper then clips and hat channel on the walls. You will want a gap between the concrete and stud. I used 1" foam as a thermal and moisture barrier then the stud wall.

http://www.avsforum.com/forum/19-de...asement-framing-expansion-joint-ib3-dc04.html


----------



## 2pacalypsenow

Thanks for the reply, I will take a read.

Thank you


----------



## Ladeback

2pacalypsenow said:


> Thanks for the reply, I will take a read.
> 
> Thank you


Your welcome, @BIGmouthinDC or HT Geek can give you better advice though. You can build it the way you said above, but if anyone is up there they may not like it to much.


----------



## HT Geek

Ladeback said:


> WOW! I just did a rough estimate on what it will cost to soundproof my theater with one layer of dry wall and GG between the joist, clips, hat channel, DD, GG, IB-3 type clips to decouple the walls already built and IB-3 type clips for backer boxes. Rough estimate between $3,000 to $4000 and I would still have to seal 2 doors.
> 
> I was going to just go with one layer of 5/8" dry wall and GG between the joist, will this help much? I am trying to save where I can and most of the time all of the family will be in the theater when watching a movie. The only time I would be in there alone is during sporting advents and I can hear my son playing above a little. I will also be insulating the walls and ceiling as well.


Took me a few days to get to this response... sorry 'bout that. Kids on Spring Break and LIG been busy!

So, I feel your pain on the cost. However, at least you are getting a feel for it up front.




> Like I have said before on here it may save money to buy all at once, but it may be easier if i buy things and the this in steps. First would be adding the dry wall to the ceiling. Attached is what I was thinking of doing to the ceiling.
> 
> My steps would be:
> 
> 1. Decouple walls
> 2. Add dry wall to ceiling for mass
> 3. Build backer boxes for lights and Atmos Speakers
> 4. Insulation in ceiling
> 5. Install clips and hat channel
> 6. Install DD with GG on ceiling
> 7. Insulation in walls
> 8. Install DD with GG on walls
> 9. Soundproofed doors
> 
> Am I missing any thing?


On the drywall.... Do yourself a favor and do two things: 1) buy it all at once; and 2) buy it from a general contractor supply store - a company that sells regularly at wholesale to drywall contractors. The downside is many of those companies will not sell to homeowners, so you will need to call around. The upside is you should be able to find one who will deliver to your room for free. Well worth it and cost is comparable to the Big Box stores.

Aside from that tip, here are some ideas you may consider to save $ if you wish, based on your comments above:

Door: Use 2x interior solid core doors. I bought 2 Jeldwen doors from Lowe's for $55 each. They were pre-primed, but had no framing, no holes, etc. Heavy tho. Even for 1-3/8". The cost to go 1-3/4" for me was not worth it. Best case scenario would have been if I bought cheap exterior doors and threw away everything except the door. GG in between. Total thickness 2-3/4".

If you're sure the HT room will only ever be used when the whole family is in there, you *could* simply slap a 2nd layer of drywall on top of the existing layer (presuming you're renovating an existing room... I have forgotten what you're starting out with so that comment may not be relevant).

Your steps above should look something like this:

1. Remove any existing drywall inside the room
2. Insulation in ceiling
3. Insulation in walls
4. Build backer boxes for lights and Atmos Speakers
5. Mount backer boxes
6. Install clips and hat channel on ceiling and walls
7. Install DD with GG on ceiling
8. Install DD with GG on walls
9. Soundproofed doors

I found it cheaper to do a double stud wall versus clips & channel. However, if you are space constrained then clips & channel often pays for itself when you look at the Big Picture (i.e. your personal enjoyment or why are you doing this to begin with)? Lol.


----------



## HT Geek

Ladeback said:


> Read this from an earlier post on the forum about them. It is cheaper then clips and hat channel on the walls. You will want a gap between the concrete and stud. I used 1" foam as a thermal and moisture barrier then the stud wall.


With a double stud wall... yes... cheaper than clips but as you pointed out one still needs IB3 clips or similar to secure the "inner" framing to the home's structural framing, all while maintaining the de-coupling air gap.

Personally, I would avoid using foam in the 1" gap between the inner / double stud wall and the structural (original) stud wall. Any solid or semi-solid material is going to pass along some resonance and defeat the purpose of the air gap. The IB-3 clips work because they are points of contact versus surfaces, and they are designed to provide some "give" and cushion sonic vibrations.


----------



## HT Geek

2pacalypsenow said:


> If the room I'm building a cinema on has 2 of the 4 walls made of concrete, would just applying dual layers with GG be enough? I'm just worried about the sound in the above rooms, not much about outside.


Depends.

If you're concerned about sound between your HT room and rooms above, the ceiling is of course a priority. But back to your walls.... Concrete needs to be 6" thick (or more) to have an appreciable effect on dampening sound transmission. It's also a bit more complicated when it comes to concrete walls. For instance, concrete walls tend to be good at reflecting sound back into the room. And again if they are


----------



## Ladeback

HT Geek said:


> Took me a few days to get to this response... sorry 'bout that. Kids on Spring Break and LIG been busy!
> 
> So, I feel your pain on the cost. However, at least you are getting a feel for it up front.
> 
> 
> 
> 
> On the drywall.... Do yourself a favor and do two things: 1) buy it all at once; and 2) buy it from a general contractor supply store - a company that sells regularly at wholesale to drywall contractors. The downside is many of those companies will not sell to homeowners, so you will need to call around. The upside is you should be able to find one who will deliver to your room for free. Well worth it and cost is comparable to the Big Box stores.
> 
> Aside from that tip, here are some ideas you may consider to save $ if you wish, based on your comments above:
> 
> Door: Use 2x interior solid core doors. I bought 2 Jeldwen doors from Lowe's for $55 each. They were pre-primed, but had no framing, no holes, etc. Heavy tho. Even for 1-3/8". The cost to go 1-3/4" for me was not worth it. Best case scenario would have been if I bought cheap exterior doors and threw away everything except the door. GG in between. Total thickness 2-3/4".
> 
> If you're sure the HT room will only ever be used when the whole family is in there, you *could* simply slap a 2nd layer of drywall on top of the existing layer (presuming you're renovating an existing room... I have forgotten what you're starting out with so that comment may not be relevant).
> 
> Your steps above should look something like this:
> 
> 1. Remove any existing drywall inside the room
> 2. Insulation in ceiling
> 3. Insulation in walls
> 4. Build backer boxes for lights and Atmos Speakers
> 5. Mount backer boxes
> 6. Install clips and hat channel on ceiling and walls
> 7. Install DD with GG on ceiling
> 8. Install DD with GG on walls
> 9. Soundproofed doors
> 
> I found it cheaper to do a double stud wall versus clips & channel. However, if you are space constrained then clips & channel often pays for itself when you look at the Big Picture (i.e. your personal enjoyment or why are you doing this to begin with)? Lol.


 @HT Geek,
There is only one wall that has dry wall on it and it is only screwed on so it won't be a problem to remove. It is 1/2" as well and I was going to use it in another part of my basement that I am finishing. I think I may have a contact where I can get dry wall from a local company and delivered to my house. I just need to check with him on price.

So to save money don't add dry wall between the joists, put it into the clips, hat channel and DD & GG for the ceiling? That's how I am reading it.

The room I have built has been built away from the concrete walls. but am thinking of moving them out 3' more to make the room wider and better use of wasted space. On the screen wall I have 1" of foam insulation, then a 5" air gap before there is a stud wall. I was thinking of moving this closer to the foam, but maybe not after reading this. I am also looking into having an AT screen now so there will be a false wall about 2.5' to 3' out from this wall. Can I just fill the studs with insulation and cover it with fabric to absorb sound or do I need to dry wall this wall and then add foam to defuse sound?

If I leave the walls I want to move where they are I could possibly add extra walls, but I am not to concerned with these areas in the basement in that one side will be the entrance to the theater and storage and the other will be a AV Room/Office/Storage and I would be the only one in the most of the time. I figured just decoupling the walls with DD & GG would be better then nothing. If I build anther wall next to the exiting walls would they need to be decoupled as well or fastened to the floor joist?

So for the door you are saying take two doors and glue them together to make one? Then build a custom jamb for the door as well? I was thinking of buying a solid core door and adding a piece of 3/4" MDF to one side or both. It would be nice to make it look smooth in the theater room itself so it kind of a hidden door I think. If so I take it out to swing into the room or out?

The first drawing is what I have now and was originally thinking of going with. The second one is what I thinking of with now. I would push the side walls out about 3' and build a soffit from those new walls to box in the beams and create walk ways. The height for the walk ways should be about 7'-8" or so. This could give me a place to put pod lights instead of sconces on the walls. I would decouple the soffit as well with IB-3 type clips before doing the ceiling.


----------



## ncabw

How big of a problem might I have on my hands now. 

I did DD&GG both ceilings and walls. I left 1/4" for accoustic sealant. I just got back from a vacation and the tappers just sealed up the 1/4" with mud they never used the sealant. 

Is this a major F up? If so how do i go about repairing it? 

If it's only Minor I don't mind not making a big deal about it. 


Sent from my iPhone using Tapatalk


----------



## HT Geek

Ladeback said:


> @HT Geek,
> There is only one wall that has dry wall on it and it is only screwed on so it won't be a problem to remove. It is 1/2" as well and I was going to use it in another part of my basement that I am finishing. I think I may have a contact where I can get dry wall from a local company and delivered to my house. I just need to check with him on price.
> 
> So to save money don't add dry wall between the joists, put it into the clips, hat channel and DD & GG for the ceiling? That's how I am reading it.


It depends on how big a priority is reducing sound transmission through the ceiling. My read on your comments above is it's not a huge priority, presuming most of the time the whole family will be in there with you. I would only go to that length when there is a significant need to reduce sound travelling up through the floor above, such as a kitchen with tile floor for example. It's quite a bit of extra labor, particularly if you have any obstructions up there such as pipes, etc.




> The room I have built has been built away from the concrete walls. but am thinking of moving them out 3' more to make the room wider and better use of wasted space. On the screen wall I have 1" of foam insulation, then a 5" air gap before there is a stud wall. I was thinking of moving this closer to the foam, but maybe not after reading this.


Is that foam insulation sprayed onto a concrete exterior wall? A 5" air gap is plenty of room. You should be good with that. Or you could move it closer as you suggested. I'd leave a 1" gap if you move it. 




> I am also looking into having an AT screen now so there will be a false wall about 2.5' to 3' out from this wall. Can I just fill the studs with insulation and cover it with fabric to absorb sound or do I need to dry wall this wall and then add foam to defuse sound?


You still need to double-drywall it. And you will want absorbent material (e.g. insulation) on the wall behind the screen as well. Speakers radiate sound 360°. They just don't radiate as much out the sides and rear as the front. You'll also get reflections off the back wall that bounce back onto the front wall. Basically, you want to try and capture as much of that sound bouncing off the front wall as you can. 




> ... I figured just decoupling the walls with DD & GG would be better then nothing.


Just to be clear... DD+GG is not decoupling. It adds mass for dampening. You need either double stud/staggered stud wall, clips & channel, etc. to perform the decoupling part.




> If I build anther wall next to the exiting walls would they need to be decoupled as well or fastened to the floor joist?


Any wall you build needs to be fastened to the floor. Decoupling would depend on the details of the new layout. The easiest way to think of it is any surface on the inside of your HT room should be decoupled. So, for instance if you build an A/V closet in a portion of a storage area, that A/V closet also should be decoupled because it opens into the HT room.




> So for the door you are saying take two doors and glue them together to make one? Then build a custom jamb for the door as well? I was thinking of buying a solid core door and adding a piece of 3/4" MDF to one side or both. It would be nice to make it look smooth in the theater room itself so it kind of a hidden door I think. If so I take it out to swing into the room or out?


Doors are a big subject unto themselves.  It's really up to you. Taking a solid core door and adding 3/4" MDF will certainly add weight to it and will help. Also think about any constraints you might have for door width. A wider door means a wider jamb, a wider hinge, etc. I've found this site to be a good resource for hinges. Take a look at Emtek brand door hardware for handles and locks. They have one of the best selections of hardware that fits wide doors. All of their products that I've seen are custom ordered.

You will likely need wide swing hinges. In my case, I used 4" wide hinges. I also decided to have additional holes drilled in the door side of the hinges due to how the original holes aligned with the door parts. In retrospect, I wish I'd done the same thing for the frame side of the hinges (but the door was such a pain to mount - very heavy - that I now don't want to take them down to adjust the hinges)! If I could do it over, I'd have 8 holes in each hinge side. It sounds like overkill, but these doors are heavy and on a 4" wide hinge having 8 holes is not actually extreme.

In-swing vs. out-swing is personal preference. My theater room required an in-swing due to various clearances. One factor in that decision-making process is which side of the door you want your automatic door bottom and stops to be seen from (presuming you go with Zero or similar seals for the door gaps). They are placed on the same side the door swings, so when you close the door it presses against the jamb seals and the auto bottom drops down to seal the bottom.


----------



## HT Geek

Ladeback said:


> [MENTION=8735410]The first drawing is what I have now and was originally thinking of going with. The second one is what I thinking of with now. I would push the side walls out about 3' and build a soffit from those new walls to box in the beams and create walk ways. The height for the walk ways should be about 7'-8" or so. This could give me a place to put pod lights instead of sconces on the walls. I would decouple the soffit as well with IB-3 type clips before doing the ceiling.


Just be careful about the width of your front wall. Why not push out those sides as you had in the 1st drawing? It would give you flexibility to use a larger screen. If you want a smaller look, you could still do it.

I like the idea of boxing in the beam so it is concealed.


----------



## HT Geek

ncabw said:


> How big of a problem might I have on my hands now.
> 
> I did DD&GG both ceilings and walls. I left 1/4" for accoustic sealant. I just got back from a vacation and the tappers just sealed up the 1/4" with mud they never used the sealant.
> 
> Is this a major F up? If so how do i go about repairing it?


It's minor. The acoustic sealant is preferred because it is flexible (hardened mud can/will crack over time). 

Is it going to be buried behind moulding or something else? If so, I wouldn't worry about it. It's a minor issue. If it will be visible, just try to remember to check it periodically (every 6 months or so), and you can seal it up with caulk as needed if it cracks.


----------



## Ladeback

HT Geek said:


> Just be careful about the width of your front wall. Why not push out those sides as you had in the 1st drawing? It would give you flexibility to use a larger screen. If you want a smaller look, you could still do it.
> 
> I like the idea of boxing in the beam so it is concealed.


I could have the walls go all the way to the screen wall, but I may have to move the alarm box if I can't build around it.

I am thinking of building the new wall like this and use IB-3 clips to decouple the ladder's for the soffits. I am also thinking of either angling the soffit wall on the next to the beam in the theater or building a second smaller soffit all around the room to add rope lighting.


----------



## nimlet

*Acoustic sealant between no-touch walls?*

Hi,
I'm building a room with clips on channel and two layers of drywall with green glue. I have a question on whether I need to leave a gap where the drywall sheets would meet each other and fill that with acoustic sealant. I understand the application of the sealant if there's a gap, of course, but I'm wondering if there is a deliberate benefit to leaving a separation of 1/4" where the sidewalls meet or the walls meet ceiling?

Any insight would be much appreciated. I spent a couple of hours sealing between the first layer of drywall and the ceiling and floor perimeter last night and it was a total pain in the a$$. I'd rather not do it on adjacent sheets unless there's a gap!

Thanks,
Dave


----------



## Ladeback

@HT Geek,

It is interesting how big of difference by adding one layer of 5/8" dry wall to between the joist can make. I think I may do the second option below for my ceiling. The question is, do you just do between the joist of the theater room or go out beyond the room about a 1' or so? That's what I am thinking of doing and one layer shouldn't be to expensive an help with noise from above.

For the walls I am going to build it like the first wall photo, but if I need to I can always add a second layer and GG to the back side like in the second photo.

First though I will have to move some walls and get some IB-3 clips to help decouple them from the ceiling as I move them in to place.


----------



## HT Geek

Ladeback said:


> I could have the walls go all the way to the screen wall, but I may have to move the alarm box if I can't build around it.


Now I understand the need to move the wall (after viewing your pics).




> ... building a second smaller soffit all around the room to add rope lighting.


You could also use crown moulding and hide the lights inside of it.


----------



## HT Geek

Ladeback said:


> [MENTION=8735410]The question is, do you just do between the joist of the theater room or go out beyond the room about a 1' or so? That's what I am thinking of doing and one layer shouldn't be to expensive an help with noise from above.


There's no benefit to the HT room itself 1' out from it. However, it may be convenient depending on where your wall studs line up.




> For the walls I am going to build it like the first wall photo, but if I need to I can always add a second layer and GG to the back side like in the second photo.
> 
> First though I will have to move some walls and get some IB-3 clips to help decouple them from the ceiling as I move them in to place.


You have the advantage of totally new construction. But IMHO you need to decide your priorities first (e.g. cost, sound proofing). While knowing what you could do, it may or may not be worthwhile in your circumstances. Though it is worth noting that to retrofit any of these ideas later on would be a lot more work and cost versus doing any of them up front.


----------



## Ladeback

HT Geek said:


> Now I understand the need to move the wall (after viewing your pics).
> 
> 
> 
> 
> You could also use crown moulding and hide the lights inside of it.


With pushing the walls out and building soffits it makes for a better room I think. I should have 7.5' of clearance under the soffits. There is a little bit of work ahead of me.


----------



## doveman

Sorry for the delay in replying, I had some deadlines to meet.



HT Geek said:


> Not quite. You could attach the IB clips to the top of the header board, but it's more common for it to be attached to the _side _of the header board or side of a few studs. It just depends on which method makes more sense for your application. The point is to secure your inner wall to the outer (structural) wall using the IB clips. AND you want that 10mm gap from the ceiling to exist AFTER you have installed new ceiling joists for your room-within-a-room.
> 
> Let's say you build a double stud wall, and you anchor your inner wall to the outer wall via IB clips attached to the header. Well, first off you should use a double header. Reason is because when you install 2x drywall/plasterboard layers inside the room, you will need to ensure you have sufficient height of the top header to screw your staggered wall board layers into the header. So, at that point you then have 3" of wood to secure the side of your IB clip to the side of the header board(s).
> 
> Second (and more pertinent to your question above), you want a gap between your ceiling joists and the structural ceiling above (or floor of the room above). That gap needs to exist after you install your ceiling joists, which will be secured to the inner stud walls. Therefore, when calculating the height of your studs for your inner wall, you will need to take into consideration the total room height, minus the height of your air gap + header and footer board heights for your stud walls + ceiling joist height, so that a clearance (gap) is maintained between the top of the inner room's ceiling joists and the floor of the next level above it.
> 
> As an example, let's say (using American measurements) you decided on ceiling joists with a 12' wide span using 2x6 lumber. A 2x6 laid on its strong side (for shear) is 5-1/2" tall (your joists must lay vertically). Since the header will support the ceiling joists, that results in the need for a gap of 6" in total height above the header (2x6 height [5-1/2"] + 1/2" gap [bit more than 10mm] because the ceiling joists will lay on top of the stud walls (of which the header board is the top most portion). So in that case the top of your header would be 6" below the top of the original room.


Thanks, that all makes sense and it was helpful to highlight the need to take the joist height into account when designing the independent ceiling.



> Yes, 'footer board' is the same thing as 'bottom plate.' However, you don't fix that to the floor joists (normally). You fix it to your sub-floor. Other methods may be possible, but make sure you adhere to building fire codes.
> 
> What you want to do is effectively the same thing. You're considering creating a "room within a room." The difference in your case is the outer or structural wall is concrete block (or whatever the material is) instead of a wood stud wall, but the de-coupling concepts are the same.


OK, just different terms but the concept is the same. Point noted about fixing the footer board to the sub-floor rather than the joists.



> Yes, I think we're not completely following one another. Let's try backing up a bit.
> 
> So, you will have a wood stud/ceiling joist "room within a room" or inner room, and this will be built inside an existing room with cinder block walls. Have I got that right?


Yes, that's right.



> Presuming that is correct, are the plasterboard walls you're talking about in the paragraph above on (or planned for) the outer wall (cinderblock)?


No, the (double) plasterboard walls would be the inner walls, mounted onto the stud frame via hat channel or similar.



> The idea is to leave a 10mm gap between all walls of the inner room and ceiling, and the original/outer/adjacent walls and ceiling. The floor is normally not much you can do about in terms of de-coupling, but it's ideal to dampen or de-couple the floor to whatever extent you can.
> 
> If you have plasterboard on the room's original (exterior to the HT shell) walls, then there would be a 10mm gap between the outer edge of your inside stud wall and that plasterboard. If you didn't have plasterboard on the cinderblock walls, that 10mm gap would be between the outer edge of your inside stud wall and the cinderblock. The point is to have an air gap between the surfaces.


I understand about spacing the stud frame from the existing walls. The bit I'm having trouble understanding is how can I leave a 10mm gap between the top edge of the plasterboard walls and the existing ceiling, as that would obviously leave the top 10mm of the new walls consisting only of the stud frame and insulation stuffed between the studs, with no plasterboard sealing it off, which would thus leave a way for sound to circumvent the plasterboard layers on the rest of the wall. 

If/when I build the independent ceiling then this won't matter as the new ceiling will seal off this gap but it may be that soundproofing the walls is sufficient and I won't need to do the ceiling, or I might only be able to afford to do the floor and walls for now and add the ceiling later, so I'd think the walls should be sealed from top to bottom. I guess one way to look at it is that if I need a 10mm gap between the original ceiling and the top of the plasterboard layers of my new walls, because otherwise there will be enough sound transmitting from the ceiling into the walls to be an issue, then I'll definitely need to build the independent ceiling anyway.



> Hopefully the details I included above make this clearer. If I now understand you correctly, in your case you want to secure the stud walls that compose your inner room (or HT room shell) to the cinderblock that composes your 'outer' wall (and ceiling). 'Outer' just means the structural walls and ceiling or the existing walls/ceiling in the room. Your 'room within a room' build will create an 'inner' set of walls and ceiling.


Yes, you've understood correctly and I better understand what you mean now thanks.



> There are various pros and cons to metal vs wood. Either way you will need to consult building codes and span tables for your ceiling joists. The span tables will allow you to cross reference joist span length, type, thickness, and weight bearing capability. You will need to calculate your anticipated ceiling load to make proper use of the tables. For example, 5/8" Type X drywall weighs 2.1 - 2.2 lb./sq. ft. So, if I had a 100 sq. ft ceiling then I know with 2x layers of 5/8" drywall, I need a minimum load bearing strength of the ceiling joists that will hold a total of 4.4 lb./sq. ft.
> 
> I personally prefer to use engineering formulas, but the span tables (while rough and not completely accurate) are suited to most people because you don't have to deal with formulas and factoring all the details. The span tables are a generalization and allow a margin of error. Even if you do use formulas or hire an engineer, start with the tables as they will at least steer you in the right direction with regards to feasible sizes of lumber or metal joists for your particular needs (i.e. span distance and weight bearing).
> 
> The main advantages to metal studs are 1) they are always straight; and 2) support more weight than wood when comparing thinner materials (i.e. you can usually use narrower/thinner metal studs versus wood to support the same load). Wood studs are nearly always cheaper, and somewhat easier to work with.


Thanks, that's some useful information there to help me investigate the options further.



> Even ordinary fiberglass insulation is quite effective at diminishing higher freqs such as human speech. Almost any insulating material should work well.


For the Living Room I should probably look at insulation options rather than hat channel and plasterboard then. I'm not sure what options I might have with only 35mm to play with though. If it's possible to build a 20mm thick stud frame and get 20mm thick insulation to wedge between it, then I could screw 12mm plasterboard to the studs but as the studs will be attached directly to the cinderblock (no room for 10mm airgap or clips), I'd be concerned that the noise would just transfer from the cinderblock to the plasterboard via the studs.



> Those panels appear to be designed to act as your wall veneer (i.e. no drywall behind them).


I was thinking they might work on the Living Room wall if I just need acoustic insulation there, either stuck on the cinderblock after stripping back the existing plaster or just stuck on top of the existing plaster, although that will probably cause access issues with the electrical sockets and I might only be able to use the thinner 15mm panels for that. In any case, there's no proper technical data provided for those products but maybe there's something similar available with such data.



> The latter. With any product you consider, make sure you view its acoustical properties. This is typically found under a heading such as "Technical Specifications," though sometimes it will appear in the MSDS. Some products are impossible to verify their acoustical properties. Avoid them.


Are there any acoustic plasterboard products you can recommend? They might not be available locally to me but they'd give me something to compare to at least.





> Could you use a slightly narrower door?


Unfortunately not. It's hardly generous as it is, so making it any narrower would cause issues with getting furniture through it.


----------



## HT Geek

doveman said:


> I understand about spacing the stud frame from the existing walls. The bit I'm having trouble understanding is how can I leave a 10mm gap between the top edge of the plasterboard walls and the existing ceiling, as that would obviously leave the top 10mm of the new walls consisting only of the stud frame and insulation stuffed between the studs, with no plasterboard sealing it off, which would thus leave a way for sound to circumvent the plasterboard layers on the rest of the wall.


I see. That's another miscommunication/misunderstanding. Your plasterboard in your 'room within a room' will be installed essentially identically to how you'd install it in any other room. You do NOT leave a gap at the top of it along the walls. You DO want a small (6mm or so) gap at the bottom, which you'll seal with GG sealant or acoustical caulk after all the plasterboard is up.

The 10mm ceiling gap you're referring to is a gap between the exterior of your inner studs and the interior surface of your outer studs (the original or structural studs in the room - or in this case your concrete walls, etc.). Suffice to say, you simply want a 10mm or so gap between the outside of the studs you will build in the room and any other surface exterior to your 'shell.' Same thing for the ceiling. There should be a 10mm gap between the outside/exterior of your inner studs and your ceiling.

Ideally, in a typical residential construction setting such as a detached home, you would remove all the existing plasterboard in the room before you build your room-within-a-room or 'shell.' The idea is to eliminate surfaces which may help resonate the sound waves that do escape your shell and instead create a larger air gap and fewer surface areas that escaping sound waves could impact and vibrate.

While we are on the subject; a quick tip for you: Stagger the seams of your plasterboard. When you lay it on the walls and ceiling, you will of course create seams (referred to in the U.S. by construction workers as "butt joints"). Let's take a wall for example. A simple approach is to alternate the orientation of each layer of plasterboard. For example, you might first lay it vertically, and then the second layer horizontally, or vice-versa. The important point is you do not want seams to overlap one another between layers as it creates an easier path for sound to escape. By staggering the panels, you eliminate that issue.

Likewise, when you are adjoining plasterboard panels in the corners, it's important to stagger your seams there as well. You accomplish this by alternating the order in which you apply your plasterboard to the walls and ceiling. You don't do the walls and then the ceiling, or the other way around. Rather you do the walls or ceiling first, then the other, then back to your first choice for it's 2nd layer of plasterboard, and finally you finish with your second layer of plasterboard on whatever surface remains (ceiling or walls). By following that pattern, you eliminate corner gaps where sound could escape. It's a pain. It's more work, and average contractors (if you hire out the work) will not be used to doing it this way.




> If/when I build the independent ceiling then this won't matter as the new ceiling will seal off this gap but it may be that soundproofing the walls is sufficient and I won't need to do the ceiling, or I might only be able to afford to do the floor and walls for now and add the ceiling later, so I'd think the walls should be sealed from top to bottom.


If you want to build an independent 'shell' then you will have to build the inner ceiling's structure at the same time as your walls. You cannot simply put walls up. There won't be anything at the top of them to keep the walls aligned and level. The ceiling joists serve this purpose, in addition to obviously holding up the ceiling plasterboard. Point is that you can't put up inner stud walls without doing the ceiling at the same time OR choose not to have an independent ceiling and attach the new studs somehow to your existing ceiling.

If what is above your ceiling is not your living quarters, this is an option (not use an independent ceiling). However, you will be at the mercy of the person above you and whatever noise they choose to generate. 




> I guess one way to look at it is that if I need a 10mm gap between the original ceiling and the top of the plasterboard layers of my new walls,


It's actually a gap between the top of your inner room's ceiling joists (your independent ceiling) and the original ceiling in the room. The gap is measured from the outer edge of the independent ceiling joists (the side facing your original ceiling).


[/quote]... because otherwise there will be enough sound transmitting from the ceiling into the walls to be an issue, then I'll definitely need to build the independent ceiling anyway.[/quote]

Right. That's correct. It's a phenomenon often referred to as 'flanking.'




> For the Living Room I should probably look at insulation options rather than hat channel and plasterboard then. I'm not sure what options I might have with only 35mm to play with though. If it's possible to build a 20mm thick stud frame and get 20mm thick insulation to wedge between it, then I could screw 12mm plasterboard to the studs but as the studs will be attached directly to the cinderblock (no room for 10mm airgap or clips), I'd be concerned that the noise would just transfer from the cinderblock to the plasterboard via the studs.


Correct. You will have that sound transmission problem in that scenario. 

You *could* use RC (Resilient Channel), though it is probably sacrilegious for me to mention that! Lol. RC is very controversial due to its sordid history of systemic failure and resulting litigation. However, for your consideration take a look at this 'heavy duty' system from Clark Dietrich. 

Unless you can squeeze in stud + gap + 1 or more layers of plasterboard, your best bet is to use multiple layers of whatever thickness will fit of plasterboard screwed directly into the existing wall (presuming you believe it can support the additional weight). That would at least provide extra mass.




> I was thinking they might work on the Living Room wall if I just need acoustic insulation there, either stuck on the cinderblock after stripping back the existing plaster or just stuck on top of the existing plaster, although that will probably cause access issues with the electrical sockets and I might only be able to use the thinner 15mm panels for that. In any case, there's no proper technical data provided for those products but maybe there's something similar available with such data.


I suspect you would not be satisfied with the result. You'd be better off adding mass.




> Are there any acoustic plasterboard products you can recommend? They might not be available locally to me but they'd give me something to compare to at least.


No, unfortunately. You could look at QuietRock products, but they are virtually the same as sandwiching your own plasterboard layers with Green Glue (or other viscoelastic material) between them.


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## ncabw

HT Geek said:


> It's minor. The acoustic sealant is preferred because it is flexible (hardened mud can/will crack over time).
> 
> Is it going to be buried behind moulding or something else? If so, I wouldn't worry about it. It's a minor issue. If it will be visible, just try to remember to check it periodically (every 6 months or so), and you can seal it up with caulk as needed if it cracks.


Thanks I think I will be adding moulding.


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## HT Geek

In that case, I suggest placing a bead of caulk in the corner before you place and secure the moulding. That will give you a little extra peace of mind.  

Sent from my ONE A2005 using Tapatalk


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## Gouie

Looking for advice on the second layer material for my soffits. Soffits are 5/8 MDF with a 10" cantilever and are housing HVAC. I'm using clips and channel around the soffit framing. I was going to go with MDF for the second layer because I like how clean the edges are. I'm wondering if I am leaving any sound deadening potential on the table by not using drywall for the second layer. Here's a picture if that will help.


Thanks!


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## HT Geek

Gouie said:


> Looking for advice on the second layer material for my soffits. Soffits are 5/8 MDF with a 10" cantilever and are housing HVAC. I'm using clips and channel around the soffit framing. I was going to go with MDF for the second layer because I like how clean the edges are. I'm wondering if I am leaving any sound deadening potential on the table by not using drywall for the second layer. Here's a picture if that will help.


Gouie,

AFAIK, it's mostly personal preference in that scenario. I have no doubt there are variances in frequency absorption between 5/8" type x drywall and 5/8" MDF, but in this case I'd say it depends on the look you want and what you'd rather work with.

One advantage of drywall for your 'veneer' layer is if you make a mistake (hole too large, in wrong location, etc.), it's a simple process to correct the mistake. Using MDF, OSB, etc. you may have to cut out a big hole to fix a small one. OTOH, if you plan to wrap your soffit with fabric (for the appearance), I would go with OSB, MDF, etc. - something rigid that you can staple to.

So, it depends on your plans for the end result of how your soffits will appear.


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## Gouie

. I was hoping there would be a definitive "do this" to help me decide on design . I will say that working with drywall for a while now I'm beginning to appreciate the simplicity. 

I appreciate the input!


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## HT Geek

LoL. 

Well, if you want a straight-forward suggestion: I would do drywall. Only point in doing MDF is if you need to for some reason. If you're just toying with the idea, stick with drywall.


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## Gouie

HT Geek said:


> LoL.
> 
> 
> 
> Well, if you want a straight-forward suggestion: I would do drywall. Only point in doing MDF is if you need to for some reason. If you're just toying with the idea, stick with drywall.




Advice taken, thanks!


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## Livin

I just inherited 10 panels of... Armstrong Ceilings Shasta White Textured 15/16-in Drop Acoustic Panel Ceiling Tiles (Common: 48-in x 24-in)

Any ideas on useful or interesting things to do with them? I have 2" OC703 I'm already making wall (maybe ceiling) panels with.

thx


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## RustyMon

Has anyone tried Owens Corning Pure Safety insulation? 

Home Depot seems to be carrying it now and it supposedly has a Noise Reduction Coefficient (NRC) rating of 1.20. I'd love any feedback as I'm just about to insulate my space with standard fiberglass...

Link: http://www.homedepot.com/p/Owens-Co...-Insulation-Batt-15-in-x-93-in-BU33/300194719


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## HT Geek

RustyMon said:


> Has anyone tried Owens Corning Pure Safety insulation?
> 
> Home Depot seems to be carrying it now and it supposedly has a Noise Reduction Coefficient (NRC) rating of 1.20. I'd love any feedback as I'm just about to insulate my space with standard fiberglass...


Good call. The acoustic figures look promising.

Only shows coefficients up to 4k and only shows 3.5" thickness values, but at least they publish ASTM C423 values.

250 1.18
500 1.28
1000 1.15
2000 1.12
4000 1.16


Data sheet HERE (not the MSDS.... the consumer-ized version).


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## HT Geek

RustyMon said:


> Link: http://www.homedepot.com/p/Owens-Co...-Insulation-Batt-15-in-x-93-in-BU33/300194719


I just did a quick back-of-the-envelope....

Cost-wise it's near the mean of all sound-proofing materials. About $0.79/square foot at Home Depot's (inflated) prices for unfaced. There are only 5 pieces per bag @ 15" wide each, so you're looking at about 48 sq. ft. per bag.

I have not seen it in pallet prices yet. Should be 30%+ cheaper, but we'll see.


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## Livin

HT Geek said:


> Good call. The acoustic figures look promising.
> 
> Only shows coefficients up to 4k and only shows 3.5" thickness values, but at least they publish ASTM C423 values.
> 
> 250 1.18
> 500 1.28
> 1000 1.15
> 2000 1.12
> 4000 1.16
> 
> 
> Data sheet HERE (not the MSDS.... the consumer-ized version).


How does this compare to denium Safe n Sound, or the regular pink stuff? 

Sent from my SAMSUNG-SM-G935A using Tapatalk


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## HT Geek

Livin said:


> How does this compare to denium Safe n Sound, or the regular pink stuff?


Theoretically, it should be denser than either denim or pink fluffy, but I haven't found density data yet. And higher R does not equal higher density. Ultratouch Denim is R-11 and has the same density (1.4 pcf) as pink fluffy.

Ultratouch Denim 3.5" (R-13) is $0.75/sq ft @ Home Depot. And un-faced pink fluffy 3.5" (R11) is less than half that at $0.35/sq ft from Lowe's.



HTML:


Product			thickness	density		125hz	250hz	500hz	1000hz	2000hz	4000hz	NRC				 
Ultratouch Denim R-13	3.5"		1.4 pcf		0.95	1.30	1.19	1.08	1.02	1.00	1.15		 		
Unfaced R11		3.5"		1.4 pcf		0.34	0.85	1.09	0.97	0.97	1.12	0.95

Performance of pink fluffy is improved if it is installed off-the-wall (ideally 16" or more). I'm not sure about Ultratouch or this new Performance insulation, but it stands to reason they would also benefit from that approach.

Btw, Kraft paper faced R-13 pink fluffy has crap absorption in the mids. Not recommended. Go with unfaced if at all possible.



HTML:


Product			thickness	mounting	125hz	250hz	500hz	1000hz	2000hz	4000hz	NRC
O.C. Pink Paper Out R11	3.5"		on wall		0.58	1.11	1.16	0.61	0.40	0.21	0.80

O.C. Pink Unfaced R11	3.5"		on wall		0.34	0.85	1.09	0.97	0.97	1.12	0.95
O.C. Pink Unfaced R11	3.5"		16" air		0.80	0.98	1.01	1.04	0.98	1.15	1.00

FWIW, I just noticed Owens Corning claims this new Pure Safety product is R-15.

It is apparently being sold exclusively at Home Depot for the time being. Unless HD has a patent on it, that's not likely to last. But until then, it would seem there won't be any competition for price.


----------



## RustyMon

HT Geek said:


> It is apparently being sold exclusively at Home Depot for the time being. Unless HD has a patent on it, that's not likely to last. But until then, it would seem there won't be any competition for price.


Great info above... thanks for running with the idea for this new product! I agree with your quote here... seems to be HD only at this time. I'm probably going to put it in a portion of my build and will report back on the install experience.


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## another-user

im just starting to look into building a room for myself. whats the best bang for the buck out there? im on a limited budget, so theres no way i can afford to go all out.

the rooms roughly 10x12x8. cement floor, 1.5x cement walls, and 2.5 standard walls. im mostly concerned about limiting sound through the ceiling as theres 2 bedrooms above me. i get enough complaints as is about my little old logitech Z-680s at 1/3rd volume.

at the moment im looking at 
A237 Resilmount sound isolation clips (might put rubber pads under the clips)
2x 5/8 drywall (maybe with green glue on the ceiling? or some other kind of acoustic caulk... or just regular caulk. somethings gotta be better than nothing)
insulation behind the drywall
pre-insulated subfloor panels.

and if it makes any difference, the max output of my system is only 1000wrms for the speakers, and 400-600wrms for the sub (havnt picked that guy up yet)


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## Mpoes12

HT Geek said:


> LoL.
> 
> Well, if you want a straight-forward suggestion: I would do drywall. Only point in doing MDF is if you need to for some reason. If you're just toying with the idea, stick with drywall.



I just posted this elsewhere so I'll post it here again.
http://www.mne.psu.edu/lamancusa/me458/9_trans.pdf
When soundproofing your ideal barrier is limp, has very low stiffness, and has very high mass. Drywall or plasterboard is a better limp mass than MDF, plywood, or OSB. I would suggest people stay away from any of these materials for the soundproofing layers of the room. In general, you want to minimize anything that increases the rigidity of the walls. I would only use these materials if, as you say, you have a reason to. However, I think it needs to be considered against the drawbacks.


Given that the green glue tests of floor structures with two layers of OSB and green glue have good STC ratings I assume it isn't the worst thing ever to use OSB, but given the various academic articles and engineering books that suggest otherwise, I've felt it is worth avoiding these materials whenever possible. I suspect if you tested two identical walls in the same lab, one has OSB and one has Drywall, that even correcting for mass differences would show the drywall is superior. I suspect the biggest differences would be in the low frequencies and the coincident dip.


----------



## Mpoes12

another-user said:


> im just starting to look into building a room for myself. whats the best bang for the buck out there? im on a limited budget, so theres no way i can afford to go all out.
> 
> the rooms roughly 10x12x8. cement floor, 1.5x cement walls, and 2.5 standard walls. im mostly concerned about limiting sound through the ceiling as theres 2 bedrooms above me. i get enough complaints as is about my little old logitech Z-680s at 1/3rd volume.
> 
> at the moment im looking at
> A237 Resilmount sound isolation clips (might put rubber pads under the clips)
> 2x 5/8 drywall (maybe with green glue on the ceiling? or some other kind of acoustic caulk... or just regular caulk. somethings gotta be better than nothing)
> insulation behind the drywall
> pre-insulated subfloor panels.
> 
> and if it makes any difference, the max output of my system is only 1000wrms for the speakers, and 400-600wrms for the sub (havnt picked that guy up yet)



Something is not always better than nothing. Use Greenglue if you are going to use anything. It's a proven product with consistent results and its cheap compared to caulk given the quantities you would need. The biggest problem with most caulks is that they actually increase material stiffness, which is bad. You want increased mass, increased damping, not no increased stiffness. Green glue meets this criteria, most if not all caulks do not.


The biggest problem you might have with only soundproofing the ceiling is flanking. Sound can escape out the walls and then travel up through the ceiling outside the theater space. You also have things like the outlets, the hvac, you name it. The inner shell of the room needs to be completely sealed from the rest of the house (as in air tight seal) and fully decoupled. Otherwise, any direct connections becomes a source for sound to escape. The ideal is almost always not possible, so you compromise, but be sure to do so in the right ways. For example, whats the point of decoupling the walls and using green glue if you have HVAC pipes that give a direct sound path up stairs to the bedrooms? 


The most bang for the buck is likely to use a cheap hat channel clip like the IB-1 clips, hat channel, and two layers of 5/8" drywall. That provides more sound transmission loss than green glue alone. Adding green glue is the next best thing. If you can't afford that, skipping the green glue is better than skipping the clips and hat channel. You can always add green glue and another layer later. 


Just don't underestimate the cost of fixing flanking paths. I did with my build and spent a lot more money than I had budgeted.


----------



## Mpoes12

HT Geek said:


> Theoretically, it should be denser than either denim or pink fluffy, but I haven't found density data yet. And higher R does not equal higher density. Ultratouch Denim is R-11 and has the same density (1.4 pcf) as pink fluffy.
> 
> Ultratouch Denim 3.5" (R-13) is $0.75/sq ft @ Home Depot. And un-faced pink fluffy 3.5" (R11) is less than half that at $0.35/sq ft from Lowe's.
> 
> 
> 
> HTML:
> 
> 
> Product            thickness    density        125hz    250hz    500hz    1000hz    2000hz    4000hz    NRC
> Ultratouch Denim R-13    3.5"        1.4 pcf        0.95    1.30    1.19    1.08    1.02    1.00    1.15
> Unfaced R11        3.5"        1.4 pcf        0.34    0.85    1.09    0.97    0.97    1.12    0.95
> 
> Performance of pink fluffy is improved if it is installed off-the-wall (ideally 16" or more). I'm not sure about Ultratouch or this new Performance insulation, but it stands to reason they would also benefit from that approach.
> 
> Btw, Kraft paper faced R-13 pink fluffy has crap absorption in the mids. Not recommended. Go with unfaced if at all possible.
> 
> 
> 
> HTML:
> 
> 
> Product            thickness    mounting    125hz    250hz    500hz    1000hz    2000hz    4000hz    NRC
> O.C. Pink Paper Out R11    3.5"        on wall        0.58    1.11    1.16    0.61    0.40    0.21    0.80
> 
> O.C. Pink Unfaced R11    3.5"        on wall        0.34    0.85    1.09    0.97    0.97    1.12    0.95
> O.C. Pink Unfaced R11    3.5"        16" air        0.80    0.98    1.01    1.04    0.98    1.15    1.00
> 
> FWIW, I just noticed Owens Corning claims this new Pure Safety product is R-15.
> 
> It is apparently being sold exclusively at Home Depot for the time being. Unless HD has a patent on it, that's not likely to last. But until then, it would seem there won't be any competition for price.




I'm a little confused by this advice. With regard to sound proofing, as apposed to acoustic treatment, the insulation is placed inside the wall. In that case, the insulation inside the wall should actually be a bit less dense, so pink fluffy stuff or mineral wool, or denim insulation will all work roughly the same. You would want it spaced from the wall so it isn't pressing against the decoupled walls, but you wouldn't space it 16" as you don't typically have 16" of air gap inside a wall. As I understand it, the thickness and amount of insulation doesn't seem to make big differences. It dampens the wall some and lowers the Q of the wall resonance, but it doesn't increase the STC rating drastically and certainly more insulation depth seems to provide little advantages. I actually asked about if it would matter where the insulation was placed in a wall or how thick it was and was provided with numerous test reports from Riverbank on this topic, the engineer that sent them to me indicated the tests they ran didn't show much difference. They suggested using the cheapest insulation you can buy and not worrying about having 5" instead of 3.5" or anything like that, not enough difference to matter (however the actual wall air gap does matter).


In the room what you say is true, an air gap is important. This is always true, regardless of the insulations porosity and density. That is because sound waves are at maximum velocity 1/4 wavelength from the wall and insulation is most effective at reducing velocity rather than pressure. In fact, the means by which insulation damps a wall inside is that the wall surface is actually converting high sound pressure into high sound velocity. Tests have shown that for insulation that is 8" or less in thickness, you will get better bass absorption with higher density insulation. After that point you want the opposite, lower density will work better.


As for differing absorption coefficients, I think it is not a good idea to get too hung up on values greater than 1, nor should they be compared to other tests. Tests between labs have been shown not to be consistent (RPG has an article where they were involved in doing a test to compare consistency between labs) and tests on different days or conducted by different technicians can also differ. Values greater than 1 is an error basically, its inaccurate (you can't absorb more than all of the sound hitting it) and is actually caused by a mis-estimation of the total absorbing area of the sample and base absorption of the room itself, reduction in room volume from samples, etc. I'll be honest in saying this last bit I've never fully understood, it seems easily correctable, but RPG's Peter D'Antonio has been railing about it for ever saying we need to fix it, but nobody has ever bothered to fix it. I believe the Total Sabins for the total sample is the most reliable figure to compare with.


----------



## HT Geek

mpoes12 said:


> the most bang for the buck is likely to use a cheap hat channel clip like the ib-1 clips, hat channel, and two layers of 5/8" drywall. That provides more sound transmission loss than green glue alone. Adding green glue is the next best thing. If you can't afford that, skipping the green glue is better than skipping the clips and hat channel. You can always add green glue and another layer later.
> 
> Just don't underestimate the cost of fixing flanking paths. I did with my build and spent a lot more money than i had budgeted.


+1


----------



## HT Geek

Mpoes12 said:


> I'm a little confused by this advice. With regard to sound proofing, as apposed to acoustic treatment, the insulation is placed inside the wall. In that case, the insulation inside the wall should actually be a bit less dense, so pink fluffy stuff or mineral wool, or denim insulation will all work roughly the same. You would want it spaced from the wall so it isn't pressing against the decoupled walls, but you wouldn't space it 16" as you don't typically have 16" of air gap inside a wall....


I was referring to sound proofing/absorption efforts in the room, or that is not inside the wall. Perhaps my use of words created the point of confusion. Not worth digressing over this IMO, but I do see your point about the semantics of the word references. 

I don't disagree with any of your comments. 




> ... In the room what you say is true, an air gap is important. This is always true, regardless of the insulations porosity and density.


Yes, I was trying to make the point by comparing observed values of sound proofing/absorption materials on the wall (in the room) versus 16" off the wall.


----------



## another-user

Mpoes12 said:


> Just don't underestimate the cost of fixing flanking paths. I did with my build and spent a lot more money than I had budgeted.


when you say flanking paths, do you mean the side walls? what would be recommended for this? just building a new wall in front of the current one? thats what i was planning anyways to hide all the plumbing and pipes up against the wall.
and whats recommended for the hvac sound control? the room is going to have a single T connection in it, 1 down firing in the room, and 1 up firing back to its original location.


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## Mpoes12

another-user said:


> when you say flanking paths, do you mean the side walls? what would be recommended for this? just building a new wall in front of the current one? thats what i was planning anyways to hide all the plumbing and pipes up against the wall.
> and whats recommended for the hvac sound control? the room is going to have a single T connection in it, 1 down firing in the room, and 1 up firing back to its original location.



Flanking paths refers to any indirect path the sound may travel out of the room. I was thinking of the sidewalls, but I used the term flanking path because there are so many others. Because flanking paths are indirect the sound is reduced compared to a direct path. What that means is that while it is true that you can fail to meet your sound proofing expectations due to flanking paths, it would not be true to say that due to flanking paths, the soundproofing in the ceiling is worthless. It still has value, it will still reduce the amount of sound from going into the bedrooms.


Remember that residential levels of soundproofing do very little at low frequencies. Rumbles and vibrations can still make it up to the bedrooms. Typical loss values at say 60hz in the best walls is just 20-30 decibles. Reference level peaks might be 115db's, so we are still talking about 85 to 95 db's at those frequencies in the bedrooms above. That's even with addressing the flanking paths.


HVAC is tricky. The best solution is no direct vent connection at all. Where I live that is not legal, would not meet code. Every room must have one supply and one return at a minimum. As such I was not able to do what is called a dead vent. That is a vent between your room and an adjacent space that contains the supply or return that creates an acoustic break between HVAC and noise source room. The dead vent is typically designed like a labyrinth lined with acoustic material. The alternative approach is to create a system in which air is moved into and out of the room at very low velocity and with a great deal of "distance" between the noise source room and the other vents. You want the ductwork to avoid direct paths between the theater and any other vent. You can use a kind of expansion box made of ductboard with offset in's and out's. This ensures there is an indirect path between the sound source and rest of the ductwork with lots of area to absorb the sound. The biggest problem with any of the vent options that provide a lot of hard bends (including a labyrinth) is that the air then creates turbulence and that is noisy. If all you care about is blocking sound from inside the theater to outside, this isn't a concern. If you also want a low noise floor in the theater, then you need to use an HVAC design that doesn't have any hard bends or where hard bends are made gradually and with turning vanes in the elbows. The best systems have acoustic material in those vanes. These help direct the air and reduce turbulence while also absorbing some of the sound.


Another HVAC problem is that the cheapest solution to absorbing sound that travels through hvacs is flexduct with an acoustic lining. However, flex duct does not stop sound from traveling out of the ductwork, it has a very low STC rating. The common solution is to encase it in a soundproof box inside the soundproof theater (like a soffit). I don't happen to like this solution myself because this doesn't really solve low frequency noise transmission and creates a tuned pipe for which the low frequencies can travel in. A paper looking specifically at the transmission loss in acoustic duct systems found this to create a null where perfect re-transmission takes place and in fact introduced increased LF noise inside the source room. I think a better solution is to design the ductwork to be soundproof and actually model its acoustic behavior to minimize LF resonances (which is why the best solution is to higher a professional). In my case I got the free resources of a professional to help me.


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## another-user

going on the idea of no direct venting... do you mean just a passive heating and cooling duct that leeches hot air from another room? im not sure if that meets code here but i could see that as being a very viable solution. im putting the room together in whats currently an unfinished basement, so i do have some room to play around here. heck, i might even just do passive radiant heating entirely. that section of the basement is always warm. the house is built into the side of a large hill, so half the basement walls are basically geothermally heated/cooled. plus no AC in the house anyways. ill just need to open the window for cooling.


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## Mpoes12

another-user said:


> going on the idea of no direct venting... do you mean just a passive heating and cooling duct that leeches hot air from another room? im not sure if that meets code here but i could see that as being a very viable solution. im putting the room together in whats currently an unfinished basement, so i do have some room to play around here. heck, i might even just do passive radiant heating entirely. that section of the basement is always warm. the house is built into the side of a large hill, so half the basement walls are basically geothermally heated/cooled. plus no AC in the house anyways. ill just need to open the window for cooling.


Some people put fans inside the deadvent, so I don't want to say its passive, but I think we are saying the same thing. Yes you take air from another room. Theaters produce a lot of heat, as do people in those theaters, so I think you need air movement. If you do radiant heat, I would still make sure you have something that allows air to be circulated in and out of the theater. My system actually brings in a mix of fresh outside air into the mix to ensure that the theater has a good supply of air being moved in and out of it. There is also an additional system venting air in and out of the equipment closet separate from the main theater room. In this case air is brought in and vented out to a passage under the stairs. Its made "soundproof" through use of a dead vent. It probably is not legal but since I already met the HVAC requirements they didn't care. I did have to sign a release to the village though.


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## HT Geek

Mpoes12 said:


> The alternative approach is to create a system in which air is moved into and out of the room at very low velocity and with a great deal of "distance" between the noise source room and the other vents. You want the ductwork to avoid direct paths between the theater and any other vent. You can use a kind of expansion box made of ductboard with offset in's and out's. This ensures there is an indirect path between the sound source and rest of the ductwork with lots of area to absorb the sound....


Agreed, but it's more effort than most people are willing/capable of attaining (though I am glad you mentioned it). 




> ... If you also want a low noise floor in the theater, then you need to use an HVAC design that doesn't have any hard bends or where hard bends are made gradually and with turning vanes in the elbows. The best systems have acoustic material in those vanes. These help direct the air and reduce turbulence while also absorbing some of the sound....
> 
> Another HVAC problem is that the cheapest solution to absorbing sound that travels through hvacs is flexduct with an acoustic lining. However, flex duct does not stop sound from traveling out of the ductwork, it has a very low STC rating. The common solution is to encase it in a soundproof box inside the soundproof theater (like a soffit). I don't happen to like this solution myself because this doesn't really solve low frequency noise transmission and creates a tuned pipe for which the low frequencies can travel in.


Yes, but 1) flex duct is much better for residential HT use vs. rigid metal ducting; 2) commonly available; and 3) the soft bend concept you mentioned above can resolve the pipe issue. 




> A paper looking specifically at the transmission loss in acoustic duct systems found this to create a null where perfect re-transmission takes place and in fact introduced increased LF noise inside the source room.


Was that conclusion absolute or did it pertain to a single scenario? What were the broader findings from that paper that are reproducible in common real-world HT room environments?

Do you have a link to it or document copy you could share?




> I think a better solution is to design the ductwork to be soundproof and actually model its acoustic behavior to minimize LF resonances (which is why the best solution is to higher a professional).


Other than the methods you described above, can you think of any other broad concepts that might help the average residential HT room (given proper design constraints, obviously)?


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## HT Geek

another-user said:


> going on the idea of no direct venting... do you mean just a passive heating and cooling duct that leeches hot air from another room? im not sure if that meets code here but i could see that as being a very viable solution. im putting the room together in whats currently an unfinished basement, so i do have some room to play around here.


SPC has a good overview of dead vents here and a brief discussion of why you need bends and insulation around your vent (with illustrations) here.

One word of caution... be sure to take into consideration the volume of air you will be moving, the volume of air in the adjoining space used to utilize the dead vent method, and the number of air exchanges per hour you'll end up with. Another concern is whether your supply and return vents are both via dead vents and if so are they going into/out of the same secondary air space? If you decide to create a dead vent, I would suggest not overlooking these sort of issues to avoid stale air recirculation. Personally, I cannot imagine a dead vent system possibly functioning well without one or more fans (unless perhaps your room is an underground bunker). I do have a friend who built a house in Michigan that is heated and cooled geothermally using no electricity, so I can't say it's not possible. Of course, he has dual PhD's in physics and mechanical engineering. Lol.

There is a short discussion with Rod Gervais regarding some of the challenges of dead vent systems on the Gear Slutz forum which may be worth reading if you decide to seriously consider a dead vent approach. 

IMHO, the bottom line is for most people (everyone?) room climate concerns trump noise concerns. Even in a thoroughly soundproofed room, if you can't stand to be in the room for more than 30 minutes, what good is it? As @Mpoes12 advised above, if you're considering a complex HVAC scenario in your room, it may be wise to consult a professional (perhaps both audio and HVAC) prior to implementation. At the very least, make sure you have thoroughly researched the topic and have a high-level understanding of air exchange, BTU, body heat, etc. variables.


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## Mpoes12

HT Geek said:


> Other than the methods you described above, can you think of any other broad concepts that might help the average residential HT room (given proper design constraints, obviously)?


If I can find the article I mentioned I'll post it. I don't tend to save articles that show things not working as intended, since that doesn't help me. The test was a lab experiment and so has high internal reliability, but the fact that it is not an in situ experiment could mean the results don't replicate in a home. There is a reasonable explanation the authors gave however and so I have no reason to believe this isn't also true of soffits with flex duct. That is that the soffit is a resonant tube. They measured the peak resonance right at the frequency which had a wavelength 4 times the length of the chamber, but did not match the length of the duct. 


I suppose before we start listening to my advice we should remember I posted in my own build thread that I'm not totally positive all of my efforts worked. Having said that, I didn't listen to my acoustic consultant for HVAC either, since some of his recommendations were difficult to achieve in a residential application and within my budget. 


While it is true that flex duct is readily available, the kind of flex duct that serves a good sound mitigation purpose is acoustically lined flex duct, which has a perforated inner sleeve. Most of what you find is not perforated. None the less, plastic isn't very good at containing sound so I'm fairly sure a large amount of sound passes through the lining anyway, making any flex duct acoustically beneficial. The problem I have with flex duct is that calling it sound proofing of the hvac is no different that calling acoustic foam or fiberglass soundproofing. They absorb sound, so there is less sound energy transmitting out of the room, but they do not block sound or contain sound. I don't see any reason why residential applications can't make use of duct board. If you sandwich the outside of ductboard with drywall the transmission loss would be fairly high and it would absorb a lot of sound. In addition you can make whatever shape you need just by cutting the material into the shape you want.


I don't think it is that difficult to design an HVAC setup that lowers the velocity and provides an avenue for sound absorption while also ensuring a high level of transmission loss out of or into the HVAC ducting itself. I think the problem lies in having room to do this and knowing how. You lower velocity by enlarging the chamber size. You absorb sound by lining it with foam or fiberglass insulation. You remove direct paths by creating offset inputs and outputs or using lots of bends.


In terms of what I did, and I'm not suggesting anyone else do what I did, I used 22 gauge rigid double wall acoustically lined steel ductwork from Spiral man for the lines into and out of the theater. The lines are 10" in diameter and branched off of 12" round ductwork, which in turn was connected to a rectangular plenum. The 12" round ductwork was lined with Spiracoustic lining around the section where the theater intersected. We inserted as much as we could before hitting another branch. The ductwork was coated inside and outside with a visco-elastic damping compound. 22 gauge steel that is damped in this fashion actually has an STC rating that is fairly similar to drywall, but one problem is that even with a lot of dampening it will be stiffer and as such have a higher resonant frequency than drywall with a higher Q. That causes a dip in the TL at the frequency. Again though, the TL is many times higher than flex duct. My return line runs into a kind of plenum expansion box with offset inputs and outputs and is made of ductboard and plywood. Because I had a lot leftover, I used greenglue to adhere the ductboard to the drywall, which should provide damping and raise the TL of that box. Measurements so far suggest that I do have a fair bit of LF noise in the room, but the noise floor is generally below my measurement capabilities. The loudest noise I measured with the HVAC running was around 28db's at 100hz and a rise below 40hz.
In the future, once I've had time to measure the room finished, I plan to install a T onto the supply or return (whichever is the source of the 100hz noise) and add a Helmholtz resonator tuned to that frequency. These too are simple to create, but hard to get right. Again, I'm making use of an expert to tell me where to place it and how to build it. 


If I had this to do over, I would have avoided he really expensive metal ductwork and used all ductboard.


Another thing that could help is making massive end boxes for the ductwork lined with acoustic insulation. By creating a flare shape that allows air to expand more gradually you reduce the noise drastically while also creating a huge area to absorb sound being transmitted through the ductwork. I have a drawing I created for one I may use in my theater. If I can dig it up I'll post it (note I am not an engineer and I did this in word, so no making fun of my poor word drawing skills).


Matt


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## HT Geek

Mpoes12 said:


> If I can find the article I mentioned I'll post it. I don't tend to save articles that show things not working as intended, since that doesn't help me. The test was a lab experiment and so has high internal reliability, but the fact that it is not an in situ experiment could mean the results don't replicate in a home. There is a reasonable explanation the authors gave however and so I have no reason to believe this isn't also true of soffits with flex duct. That is that the soffit is a resonant tube. They measured the peak resonance right at the frequency which had a wavelength 4 times the length of the chamber, but did not match the length of the duct.


Fair enough & thanks. That is useful to know.




> I suppose before we start listening to my advice we should remember I posted in my own build thread that I'm not totally positive all of my efforts worked.


LoL. One sad truth of our collective obsession on this forum is - generally speaking - we can never know for sure if various efforts have truly been fruitful or not. I like to believe the odds are that having made the effort(s) increases the likelihood they're beneficial. That might be naivete on my part, but I'll stick with it. 




> .... While it is true that flex duct is readily available, the kind of flex duct that serves a good sound mitigation purpose is acoustically lined flex duct, which has a perforated inner sleeve. Most of what you find is not perforated....


Now that you've mentioned this, I recall that I have seen it once before. 




> .... The problem I have with flex duct is that calling it sound proofing of the hvac is no different that calling acoustic foam or fiberglass soundproofing. They absorb sound, so there is less sound energy transmitting out of the room, but they do not block sound or contain sound. I don't see any reason why residential applications can't make use of duct board. If you sandwich the outside of ductboard with drywall the transmission loss would be fairly high and it would absorb a lot of sound. In addition you can make whatever shape you need just by cutting the material into the shape you want.


Now I see where you are going with this. Yes, you're right. I don't recall which member it is but someone on the forum did exactly that in order to facilitate using part of a floor truss as a duct, though they used an OC product instead of duct liner in the strict sense of a product labeled as such. In a sense, the OC/duct liner facilitated three goals: sound proofing, air flow, and fire spread retardation.




> I don't think it is that difficult to design an HVAC setup that lowers the velocity and provides an avenue for sound absorption while also ensuring a high level of transmission loss out of or into the HVAC ducting itself. I think the problem lies in having room to do this and knowing how. You lower velocity by enlarging the chamber size. You absorb sound by lining it with foam or fiberglass insulation. You remove direct paths by creating offset inputs and outputs or using lots of bends.


If you're pontificating this is possible with enough physical space and enough use of absorbent material, I'm inclined to agree. I briefly considered using rigid metal conduit and lining both the inside and outside of it with duct insulation - until I calculated the cost. I also had pre-existing flex duct in my entire home.




> In terms of what I did, and I'm not suggesting anyone else do what I did, I used 22 gauge rigid double wall acoustically lined steel ductwork from Spiral man for the lines into and out of the theater. The lines are 10" in diameter and branched off of 12" round ductwork, which in turn was connected to a rectangular plenum. The 12" round ductwork was lined with Spiracoustic lining around the section where the theater intersected. We inserted as much as we could before hitting another branch. The ductwork was coated inside and outside with a visco-elastic damping compound. 22 gauge steel that is damped in this fashion actually has an STC rating that is fairly similar to drywall, but one problem is that even with a lot of dampening it will be stiffer and as such have a higher resonant frequency than drywall with a higher Q. That causes a dip in the TL at the frequency. Again though, the TL is many times higher than flex duct.


Wow. Lot of effort. I went with flex duct because it was easier to work with, readily available, less resonant than rigid ductwork (un-insulated), and my soffit was only 10" tall including the 2x4 frame.




> My return line runs into a kind of plenum expansion box with offset inputs and outputs and is made of ductboard and plywood. Because I had a lot leftover, I used greenglue to adhere the ductboard to the drywall, which should provide damping and raise the TL of that box.


Ironically, I took a (perhaps) similar approach with the main portion of my return line. The main return vent in my room is oversized by ~77%. Approximately 1/3 distance inside the room before it goes into my attic, it goes through an expansion box / baffle where it expands into two paths. Further down the line, the two paths are re-joined before entering the attic. There are a couple of other joints as well that feed into the main path. In my original plan, I allocated a return branch for a recessed PJ box and a return branch for my A/V rack. The A/V rack return is utilized, but I plugged the PJ branch after deciding against recessing the PJ into the soffit (my PJ has a rear intake vent and front exhaust and I eventually concluded concealing the PJ in a soffit recessed shelf was likely to create heat exchange issues for the PJ).

Point is my return system has 3 branches that feed into a single exit from the room shell and into the HVAC system proper, though one of those branches is plugged atm. The main branch also has its own expander/backer box/baffle that helps to slow down the velocity of return air. As is, my system is completely silent. The only way I know if it is on is by feeling air moving out of the supply vents.

I also over-sized all the vents quite a bit. As aforementioned, my main return vent is ~77% larger than the original return vent, and that doesn't take into consideration the other 2 vents. With the main return vent + A/V rack vent, my return vents are 197% of the original room vent surface area. On the supply side, I expanded my vents by an equal margin (inclusive of the currently plugged return vent). My current overall push/pull surface area is slightly favoring the supply end of the equation, but only roughly 2-3%; therefore I'm not too concerned about it. Overall, it seems relatively balanced. When I get my door seals installed, I'll find out of I'm right! Lol. 

I have 2 supply vents in the front of the room, and getting them to have relatively equal exhaust pressure was the toughest part for me. Due to the constraints I began with, I had dual inputs into the room with different distances from the HVAC unit. To compensate, I constrained the airflow on one side in order to slow down the pressure entering the room to equalize it with the other side of the room which had a longer run to begin with. In order to compensate for increased airflow velocity in the process, I created a larger cavity on the side where I wanted to slow down the air flow. The net effect is a diffusion of air on the shorter run side without increasing velocity of the exhaust at the vent. I have tested both sides and they are nearly equal.




> Measurements so far suggest that I do have a fair bit of LF noise in the room, but the noise floor is generally below my measurement capabilities. The loudest noise I measured with the HVAC running was around 28db's at 100hz and a rise below 40hz.


Sounds as if you measured that with a proper instrument! Relative to ambient HVAC noise, I prefer to use the subjective test of, "can I hear it?" Not to sound daft, but quite frankly that is the most important factor IMO when it comes to ambient or mechanical noises in a HT room, with regards to issues such as HVAC or similar systems in particular.




> In the future, once I've had time to measure the room finished, I plan to install a T onto the supply or return (whichever is the source of the 100hz noise) and add a Helmholtz resonator tuned to that frequency. These too are simple to create, but hard to get right. Again, I'm making use of an expert to tell me where to place it and how to build it.


Power to you on that one. I would think that will be quite a challenge.




> If I had this to do over, I would have avoided he really expensive metal ductwork and used all ductboard.
> 
> 
> Another thing that could help is making massive end boxes for the ductwork lined with acoustic insulation. By creating a flare shape that allows air to expand more gradually you reduce the noise drastically while also creating a huge area to absorb sound being transmitted through the ductwork.


Although I did not use a flare design, I like to think my box + single input / dual output ducts is helpful compared to a contiguous single duct. My ducts are also surrounded by pink fluffy, drywall, and MDF. I used higher density denim insulation in a few areas as well.


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## Mpoes12

HT Geek said:


> Although I did not use a flare design, I like to think my box + single input / dual output ducts is helpful compared to a contiguous single duct. My ducts are also surrounded by pink fluffy, drywall, and MDF. I used higher density denim insulation in a few areas as well.




Everything you did seems quite exhaustive and good. It also seems that your HT installation was not in a basement, and so using flex duct (I assume you did?) is probably less of an issue for escaping sound because you can isolate it in the attic and the attic is a giant sound absorber. Mine is in a basement below the family room and kitchen so I needed ways to isolate sound from escaping the ductwork right in the theater space.


As for this last point, I think we are talking about different things, but I'm sure what you did worked well. The "flare" as I called it refers to a really long and large opening in the room itself.










Notice how in this picture those end boxes, constructed of ductboard, create a massive acoustically absorbing area and a massive area for the air to expand in before it enters the room. You can see how in a studio this could lead to a really quiet HVAC system. Obviously the above would be near impossible to do in a home theater, but I think the concept could be applied still. For example, if you have the HVAC supply feed into the ceiling in the back of the room, you could construct a shelf/soffit structure along the back wall/ceiling area that has the same construction as above and would net the same effect. I'm actually thinking of doing this myself. 


Another idea I had was to construct a pillar on the wall that is in fact the above shown end box. My return duct currently enters about 2 feet above the floor on a side wall. I was thinking of creating an acoustic pillar/expansion box that would extend floor to ceiling to help.


Mind you, my ear test also shows that I currently cannot hear the air circulating in the room. Like you, I can only tell its working if I put a piece of paper up to the vent. I'm sure I am just being neurotic. My wife hates this about me but I'm always thinking of ways to do something different or better and always nit picking things that are not perfect.


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## HT Geek

Mpoes12 said:


> Everything you did seems quite exhaustive and good. It also seems that your HT installation was not in a basement, and so using flex duct (I assume you did?) is probably less of an issue for escaping sound because you can isolate it in the attic and the attic is a giant sound absorber. Mine is in a basement below the family room and kitchen so I needed ways to isolate sound from escaping the ductwork right in the theater space.


Yes, you are correct. My build is 2nd floor above garage. 




> As for this last point, I think we are talking about different things, but I'm sure what you did worked well. The "flare" as I called it refers to a really long and large opening in the room itself.


Aha. Thanks for sharing the photo. Yes, I was envisioning a cone design in HVAC ducting. It's amazing how we can perceive different images from the same words. English is particularly difficult in this regard.




> Mind you, my ear test also shows that I currently cannot hear the air circulating in the room. Like you, I can only tell its working if I put a piece of paper up to the vent. I'm sure I am just being neurotic. My wife hates this about me but I'm always thinking of ways to do something different or better and always nit picking things that are not perfect.


Well, we seem to have that in common (my OCD and my wife's corresponding eye rolling). :laugh:


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## doveman

HT Geek said:


> I see. That's another miscommunication/misunderstanding. Your plasterboard in your 'room within a room' will be installed essentially identically to how you'd install it in any other room. You do NOT leave a gap at the top of it along the walls. You DO want a small (6mm or so) gap at the bottom, which you'll seal with GG sealant or acoustical caulk after all the plasterboard is up.
> 
> The 10mm ceiling gap you're referring to is a gap between the exterior of your inner studs and the interior surface of your outer studs (the original or structural studs in the room - or in this case your concrete walls, etc.). Suffice to say, you simply want a 10mm or so gap between the outside of the studs you will build in the room and any other surface exterior to your 'shell.' Same thing for the ceiling. There should be a 10mm gap between the outside/exterior of your inner studs and your ceiling.


OK, I understand that but if I'm laying the inner ceiling joists on top of the wall headers, then the wall plasterboard can only go up to the inner ceiling joists, which are roughly 6" below the original ceiling.



> If you want to build an independent 'shell' then you will have to build the inner ceiling's structure at the same time as your walls. You cannot simply put walls up. There won't be anything at the top of them to keep the walls aligned and level. The ceiling joists serve this purpose, in addition to obviously holding up the ceiling plasterboard. Point is that you can't put up inner stud walls without doing the ceiling at the same time OR choose not to have an independent ceiling and attach the new studs somehow to your existing ceiling.


Won't the IB clips securing the header and the rest of the stud wall to the original concrete wall keep the walls aligned and level? What I'm thinking is that if I build the stud walls with the header suitably spaced down from the ceiling to allow for the ceiling joists (say 6"), then I could fit the plasterboard up to the existing ceiling for now so that it's 6" higher than the header (minus a 10mm gap for mastic) and when I come to build the inner ceiling later, I can just remove 6"-7" of plasterboard from the top to expose the headers, so that I can attach the ceiling joists to them.



> While we are on the subject; a quick tip for you: Stagger the seams of your plasterboard. When you lay it on the walls and ceiling, you will of course create seams (referred to in the U.S. by construction workers as "butt joints"). Let's take a wall for example. A simple approach is to alternate the orientation of each layer of plasterboard. For example, you might first lay it vertically, and then the second layer horizontally, or vice-versa. The important point is you do not want seams to overlap one another between layers as it creates an easier path for sound to escape. By staggering the panels, you eliminate that issue.
> 
> Likewise, when you are adjoining plasterboard panels in the corners, it's important to stagger your seams there as well. You accomplish this by alternating the order in which you apply your plasterboard to the walls and ceiling. You don't do the walls and then the ceiling, or the other way around. Rather you do the walls or ceiling first, then the other, then back to your first choice for it's 2nd layer of plasterboard, and finally you finish with your second layer of plasterboard on whatever surface remains (ceiling or walls). By following that pattern, you eliminate corner gaps where sound could escape. It's a pain. It's more work, and average contractors (if you hire out the work) will not be used to doing it this way.


Good tips thanks. I wonder about the seams at the top and the bottom of the wall though, as obviously they can't be staggered and both layers of plasterboard have to end at the same place. Perhaps if these are covered by coving at the top and skirting at the bottom it's less of an issue or maybe sealing the top and bottom with mastic fixes any potential weaknesses?

I'm also wondering how to fit the boards where the wall has an outer 90 degree right angle (e.g. where the wall turns outwards towards the balcony door in the Living Room). Either the board on the main part of the wall or the board on the short right angled section will have it's end exposed and there will probably be a small gap where the two boards butt against each other, so maybe I need to seal this with mastic, before fitting the second layer on top and sealing the gap there as well? Obviously I can't stagger the seams at this junction either, which creates a potential weakspot that could defeat the point of staggering the rest of the boards unless I do something else here to compensate for the lack of staggering.



> Unless you can squeeze in stud + gap + 1 or more layers of plasterboard, your best bet is to use multiple layers of whatever thickness will fit of plasterboard screwed directly into the existing wall (presuming you believe it can support the additional weight). That would at least provide extra mass.


For the living room wall, without removing the existing 3.5-4cm plaster I could fit an extra 3cm of something without obstructing the door, although the skirting board would need to go on top of that to protect the bottom of the wall from shoes, etc, so even if I can find skirting of the right height and design to use throughout the room (it would look a bit strange to have different skirting on one wall) that is only 1cm thick (the current stuff is nearer 2cm) that only leaves me 2cm, possibly 2.5cm at a stretch but as I'll need to skim and paint or at least paint it, I don't think I can afford to add 2.5cm of plasterboard. So I could only really use one layer of something like this http://www.buildingmaterials.co.uk/soundshield-plasterboard-15mm.html or this http://www.buildingmaterials.co.uk/british-gypsum-gyproc-soundbloc-plasterboard-15mm.html

If I remove the existing plaster and assuming I can find a 1cm thick skirting to use, I'd have 5.5-6cm to play with. So I could fit hat channel directly to the concrete wall, which is about 22mm or 7/8" thick and then use two layers of 15mm plasterboard or this 12.5mm http://www.buildingmaterials.co.uk/british-gypsum-gyproc-soundbloc-plasterboard-12-5mm.html The 22mm space between the wall and the plasterboard created by the hat channel might allow me to squeeze in some 25mm insulation like this http://www.insulationshop.co/25mm_ursa_acoustic_insulation_roll_glass_wool.html but it depends whether that will easily compress down to 22mm, as I don't want it putting pressure on the plasterboard. It also depends on whether I can use some adhesive (or something else) to attach the insulation to the cinderblock wall, as there won't be any studs to attach it to. I'm pretty sure I can't use the 25mm rockwool slabs like these http://www.insulationshop.co/25mm_rockwool_rwa45_flexible_slab.html are they're too rigid and won't compress (they'll be good for the 35mm gap under the floorboards though).

Can you think of any other options? Obviously adding just a single layer of plasterboard on top of the existing plaster is the easiest option but I'm not sure how effective the extra mass alone will be at blocking voice/mid-range noise, as the current 3.5-4cm layer of plaster certainly isn't very good. However I don't want to go to the hassle and expense of stripping the existing plaster off if hat channel and two layers of 15mm plasterboard isn't going to give me much benefit either, especially if I can't fit 25mm insulation behind it.


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## doveman

I was also reading this page http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ and was surprised to see that with furring strip/hat channel and drywall on both sides of the wall (Assembly 4), thus creating an airgap on both sides, this gave the best mid-range performance (and the worst low-range), as I've always read that there should only be an airgap on one side. They describe this arrangement as having the largest air cavity of those shown but I would have thought it would count as two separate small airgaps. Near the top of the page it discusses the Triple Leaf effect and basically says two small airgaps are bad and should ideally be combined into one larger one, so I would've thought having furring strip and drywall on each side creating two small airgaps would be bad.

However, as I'm planning to have 10mm gap+50mm stud filled with insulation+hat channel+drywall on the HT side of the wall, there are limited options for the Living Room side which would avoid an airgap completely. According to that page, even attaching drywall directly to the wall leaves a small airgap and the smaller the worse the resonance (or at least the higher frequency and more noticeable). So hat channel attached to the concrete with insulation squeezed in between the concrete and the drywall might be the best option, as shown in Assembly 5 (although the low-range suffers a bit). There are still going to be airgaps created by the U shaped part of the hat channel but maybe if the rest of the space is insulated those gaps don't matter?


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## Mpoes12

Triple leaf is something specific and doesn't necessarily apply to any situation where you have a divided air gap. The main points of that article are that you should not expect good results for sound transmission loss if your plan is to add clips and hat channel over existing drywall (nor should you build your wall like that on purpose. The air cavity behind the decoupled wall surface should be as deep as possible within reason. 

Exceptions to the triple leaf effect are when the inner shell is such a great distance from the outer shell that they don't interact acoustically. For example I have a walk way behind the side and front wall of my theater with a 24" space between the inner and outer shell. These walls don't interact and that space is so great it can create a compromise to the soundproofing if not addressed. One solution is to drywall the back of the inner shell. My solution was to drywall the ceiling since this was the only actual path for sound to escape into the rest of the house. 

Point is, dividing an air space isn't always a triple leaf per say, but with most situations it would be and you want to avoid it. Another issue is that two layers of drywall don't act as one high mass layer when there is any airgap. They don't really couple. The mass of one doesn't really effect the mass of the other and so they can bend independently. To get the benefit of higher mass, they must touch each other. 


Sent from my iPhone using Tapatalk


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## HT Geek

doveman said:


> Won't the IB clips securing the header and the rest of the stud wall to the original concrete wall keep the walls aligned and level? What I'm thinking is that if I build the stud walls with the header suitably spaced down from the ceiling to allow for the ceiling joists (say 6"), then I could fit the plasterboard up to the existing ceiling for now so that it's 6" higher than the header (minus a 10mm gap for mastic) and when I come to build the inner ceiling later, I can just remove 6"-7" of plasterboard from the top to expose the headers, so that I can attach the ceiling joists to them.


I don’t see how that approach would be beneficial. It would introduce unnecessary challenges, such as:

You'd be creating a lot of extra work for yourself
If you're going with independent ceiling joists, they will need to lay on top of your stud wall headers. With walls already up beforehand, you may have trouble maneuvering your new ceiling joists into position. You may find you don't have the necessary clearance.
Ensuring each corner of the room is square will be important. I think if you did that then it could possibly work, but it won't be as simple as one might think. When you apply the plasterboard to the walls, the weight and gravity will want to pull them toward the interior of the room. Normally, the ceiling joists would apply opposing force and prevent the walls from bowing in.
To compensate for above, you would need to be quite liberal with your IB clip placement on the walls (i.e. use many more than 1 per meter)

If you use that approach, you also won’t be able to stagger your wall and ceiling seams, meaning your sound-proofing will be less effective. 




> I wonder about the seams at the top and the bottom of the wall though, as obviously they can't be staggered and both layers of plasterboard have to end at the same place. Perhaps if these are covered by coving at the top and skirting at the bottom it's less of an issue or maybe sealing the top and bottom with mastic fixes any potential weaknesses?


At the bottom of the walls, you start at the same level – about 6mm off the floor - to leave a slight gap that you will caulk after each plasterboard layer is up. This creates a small de-coupling between the wall and floor.

The way you stagger the top of your walls is by alternating applying ceiling and wall layers of plasterboard. The industry standard method is to hang your ceiling first, then the walls. The top of the wall plasterboard sheets push up against the ceiling plasterboard, providing minor structural support to the ceiling that helps prevent sagging.


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## HT Geek

doveman said:


> Can you think of any other options? Obviously adding just a single layer of plasterboard on top of the existing plaster is the easiest option but I'm not sure how effective the extra mass alone will be at blocking voice/mid-range noise, as the current 3.5-4cm layer of plaster certainly isn't very good. However I don't want to go to the hassle and expense of stripping the existing plaster off if hat channel and two layers of 15mm plasterboard isn't going to give me much benefit either, especially if I can't fit 25mm insulation behind it.


What it boils down to is you have to look at your array of available options. First, identify your constraints. Then, decide which sound-proofing methods would be possible within those constraints: de-coupling, adding mass, damping. 

Some ideas: where you have space constraints, you could consider products such as MLV (Mass Loaded Vinyl) and for sure viscoelastic damping compounds such as Green Glue will help considerably and take up very little space.

My personal preference would be to favor de-coupling over the other methods (e.g. clips and hat channel), but in a space constrained environment it is not always practical. Anything you add is going to improve the current situation. It sounds as if you are going to have to settle for a compromise between what is feasible and your ideals.


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## HT Geek

doveman said:


> I was also reading this page http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ and was surprised to see that with furring strip/hat channel and drywall on both sides of the wall (Assembly 4), thus creating an airgap on both sides, this gave the best mid-range performance (and the worst low-range), as I've always read that there should only be an airgap on one side. They describe this arrangement as having the largest air cavity of those shown but I would have thought it would count as two separate small airgaps. Near the top of the page it discusses the Triple Leaf effect and basically says two small airgaps are bad and should ideally be combined into one larger one, so I would've thought having furring strip and drywall on each side creating two small airgaps would be bad.
> 
> However, as I'm planning to have 10mm gap+50mm stud filled with insulation+hat channel+drywall on the HT side of the wall, there are limited options for the Living Room side which would avoid an airgap completely. According to that page, even attaching drywall directly to the wall leaves a small airgap and the smaller the worse the resonance (or at least the higher frequency and more noticeable). So hat channel attached to the concrete with insulation squeezed in between the concrete and the drywall might be the best option, as shown in Assembly 5 (although the low-range suffers a bit). There are still going to be airgaps created by the U shaped part of the hat channel but maybe if the rest of the space is insulated those gaps don't matter?


In those diagrams the furring channel is connected directly to the concrete, and the drywall is then connected directly to the furring channel. So, you are trading a very large surface area where the concrete and drywall touch across the entire surface area for a smaller footprint where they touch. If clips and hat channel were used, the shared contact surface area becomes even smaller. The less area where they are touching, the better.

If LF is a concern, that is when mass and damping come into play. More mass = less LFE transmission.


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## doveman

Mpoes12 said:


> Triple leaf is something specific and doesn't necessarily apply to any situation where you have a divided air gap. The main points of that article are that you should not expect good results for sound transmission loss if your plan is to add clips and hat channel over existing drywall (nor should you build your wall like that on purpose. The air cavity behind the decoupled wall surface should be as deep as possible within reason.


Sure but what I found most confusing is the idea that an airgap either side of a concrete wall is actually a single large airgap, even though there's a concrete wall in the middle of it! I'm not sure why having an existing layer of drywall/plaster attached directly to one or both sides of the concrete wall would change that either.



> Point is, dividing an air space isn't always a triple leaf per say, but with most situations it would be and you want to avoid it. Another issue is that two layers of drywall don't act as one high mass layer when there is any airgap. They don't really couple. The mass of one doesn't really effect the mass of the other and so they can bend independently. To get the benefit of higher mass, they must touch each other.


Yeah, the article says that attaching drywall directly to the concrete block wall creates "an unavoidable tiny air cavity between the drywall and the block" and I presume the same applies to using two layers of drywall and as the resonant frequency is higher the smaller the airgap, this is obviously a bad thing. I guess this is the main reason for using Green Glue between the two drywall layers, to fill this gap, although I'm not sure it can do that entirely as from what I've seen it's not applied in a coat that covers the entire surface, so I imagine some small gaps will remain which can still resonate.


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## doveman

HT Geek said:


> I don’t see how that approach would be beneficial. It would introduce unnecessary challenges, such as:
> 
> You'd be creating a lot of extra work for yourself
> If you're going with independent ceiling joists, they will need to lay on top of your stud wall headers. With walls already up beforehand, you may have trouble maneuvering your new ceiling joists into position. You may find you don't have the necessary clearance.
> Ensuring each corner of the room is square will be important. I think if you did that then it could possibly work, but it won't be as simple as one might think. When you apply the plasterboard to the walls, the weight and gravity will want to pull them toward the interior of the room. Normally, the ceiling joists would apply opposing force and prevent the walls from bowing in.
> To compensate for above, you would need to be quite liberal with your IB clip placement on the walls (i.e. use many more than 1 per meter)
> 
> If you use that approach, you also won’t be able to stagger your wall and ceiling seams, meaning your sound-proofing will be less effective.


All good points that I need to consider. Regarding staggering the seams, if I just fit one layer of plasterboard to the walls for now, then when I fit the ceiling I could fit one layer to that, then the second layer to the walls and then the second layer to the ceiling but I appreciate that's not ideal and this would be better:



> The way you stagger the top of your walls is by alternating applying ceiling and wall layers of plasterboard. The industry standard method is to hang your ceiling first, then the walls. The top of the wall plasterboard sheets push up against the ceiling plasterboard, providing minor structural support to the ceiling that helps prevent sagging.


Nonetheless, I'm still considering alternative approaches such as just fitting an independent ceiling for now with the joists attached to the existing walls like this http://www.soundstop.co.uk/solutions/ceiling_access/ceiling_solution_4.php (but with hat channel or maybe clips+hat channel rather than resilient bar and maybe some rubber lined brackets securing the joists to the walls to reduce any noise transfer) as the most intrusive noise comes from above, so it seems sensible to see how much difference the ceiling makes before deciding how much treatment the walls need. I might even try Genie clips and hat channel attached to the existing ceiling like this http://www.soundstop.co.uk/solutions/ceiling_access/ceiling_solution_1.php or isosonic brackets like this http://www.soundstop.co.uk/solutions/ceiling_access/ceiling_solution_2.php to see whether that's effective enough. I'm thinking that this would at least reduce the weight being added to the walls, as the inner ceiling would be supported by the existing ceiling rather than the walls.

A lot of sites don't seem to give specs but this acoustic plasterboard is around 10.6 kg/m2 for 12.5mm and 12.6 kg/m2 for 15mm http://www.british-gypsum.com/products/gyproc-soundbloc?tab0=1. So if I add even one layer of 15mm to both sides of the 2.3mx3.2m wall separating the living room from the HT room that's an extra 185kg on that wall and with a second layer of 12.5mm on both sides that brings it up to 341kg. Two layers on the 2.3mx4m party wall will add 213kg to it and 133kg to the 2.3mx2.5m end wall. The other end wall is largely window so not so much there. I don't know how much weight removing the existing 3.5cm of plaster will take off and there's the extra weight of the stud wall, clips, insulation, to allow for but I guess I'll need a structural engineer to advise me how much weight I can safely add, so that I don't have to worry about being buried alive under it all! So I might have to avoid loading the weight of the inner ceiling onto the walls as well or maybe even just settle for one layer of plasterboard on the walls.


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## doveman

HT Geek said:


> What it boils down to is you have to look at your array of available options. First, identify your constraints. Then, decide which sound-proofing methods would be possible within those constraints: de-coupling, adding mass, damping.
> 
> Some ideas: where you have space constraints, you could consider products such as MLV (Mass Loaded Vinyl) and for sure viscoelastic damping compounds such as Green Glue will help considerably and take up very little space.
> 
> My personal preference would be to favor de-coupling over the other methods (e.g. clips and hat channel), but in a space constrained environment it is not always practical. Anything you add is going to improve the current situation. It sounds as if you are going to have to settle for a compromise between what is feasible and your ideals.


Yeah, I hate compromising but it can't be avoided most of the time unfortunately. I'll have to look at the weight of MLV and consider whether using that and one layer of plasterboard might suffice, or whether no MLV and two layers with Green Glue between them would be better (assuming the weight is OK).


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## doveman

HT Geek said:


> In those diagrams the furring channel is connected directly to the concrete, and the drywall is then connected directly to the furring channel. So, you are trading a very large surface area where the concrete and drywall touch across the entire surface area for a smaller footprint where they touch. If clips and hat channel were used, the shared contact surface area becomes even smaller. The less area where they are touching, the better.
> 
> If LF is a concern, that is when mass and damping come into play. More mass = less LFE transmission.


I get that but what I didn't understand is how two small airgaps on either side of a concrete wall could be considered a single air gap. Also, hat channel with plasterboard attached creates a small airgap, which is bad from a resonance point of view, even though decoupling the plasterboard from the concrete wall is good as far as transmission is concerned.

It's hard to say how much of an issue LF is. Certainly no-one's using subwoofers or bassy loudspeakers but I suppose impact noise can be considered LF, so if impact noise is transferring from the floor upstairs/my ceiling into the walls (which it will still do even with an extra inner ceiling) then it might be necessary to use mass and damping to contain it.


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## Mpoes12

green glue serves a few purpose. One is that it will adhere the two pieces of drywall together without changing the rigidity of the structure. You could glue them together with construction adhesive but it would end up making the wall too stiff, which is bad. It adds mass, and mass helps add more sound blocking. However, most importantly it converts the two layers of drywall into a constrained layer of drywall. Research into CLD has found that the damping and impedance change through the medium as sound travels provides advantages to transmission loss that exceed what mass alone would predict. It becomes a transmission loss multiplier, in a way, beyond that of mass and allows more transmission loss than you could really get due to mass limits in residential construction. It also damps the coincident frequency which means you don't get a notch in the transmission loss at the coincident frequency. 


A wall structure that is composed of drywall, concrete wall, drywall is not one giant air space. it is in fact two air spaces. I suppose you could call this a triple leaf, but....In this case that is a good wall for sound proofing. One of the highest levels of sound proofing you could achieve would involve using something as massive as a cement wall. The problem with a cement structure would certainly be its rigidity, but...cement actually has good damping properties too it. Another problem with cement is that because it doesn't have perfect damping and because it is so rigid and dense, if the sound source vibrations can't be decoupled from the cement wall, then they will transmit through the wall fairly readily. It's still a very good barrier structure as long as it isn't connected to something it can directly re-radiate through. This is why you want to decouple the drywall inner shell (relative to the sound source) is decoupled from the drywall with a sizable airspace and good damping properties. This is why you want to avoid attaching the drywall or even the hat channel on the cement wall. It just doesn't provide enough decoupling from the cement wall structure at low frequencies. 


I have a British engineering manual for building structures that discusses a case study of transmission loss using British building systems in which an apartment building was constructed with drywall attached to hat channel attached to a stud wall, a 2-3" gap, a cinder block wall, then a 2-3" gap, stud wall, hat channel, and drywall. The results of this structure (I believe it was lab tested, but this may have been in situ testing) were transmission loss values that were much higher than what we would see with even a giant decouple double stud wall, especially at low frequencies. This was due to the very large and massive cement wall in between the two decouple room shells I'm sure. 


If Money were no object and I had full freedom, I would probably want to build my theater inside of a complete cement structure, but the weight of such a structure is so great that you need to take special measures when doing this (and the cement walls and floors need to still be decoupled from other parts of the house). This is because there simply is no way to provide that amount of mass in residential construction otherwise and even the best CLD structures can't make up for that difference in sound isolation that mass could give. 


The reason this is valuable is because there are basically three zones that impact sound isolation with any wall structure. You have the rigidity zone, which impacts sound isolation the most at low frequencies. The more rigid the wall, the higher the resonance frequency of the structure, and the higher up that there is a drop in TL. You want minimal rigidity to maximize the LF transmission loss. If you can't do this, then damping of this rigid structure can lower the resonant frequency, can reduce its Q, and can extend the range in which mass drives transmission loss. This is why I say drywall is better than plywood, OSB, or MDF for a wall, its a lot less rigid for the same mass. Then you have the mass controlled zone, this is the place where the mass of the wall impacts transmission loss. The more massive the better (and why a cement wall with decoupled drywall on studs on either side of a cement wall has so much more transmission loss than just a drywalled wall). Then you have the coincident driven zone and this is where the natural resonant frequency of the material (drywall in this case) has a coincident frequency in which sound will re-radiate directly through the material with nearly no or even no loss. Damping, especially in the form of CLD will impact all three zones. Damping from CLD can lower the Q of the coincident frequency so greatly that it basically disappears and you still have full transmission loss. The damping also provides damping to the entire wall structure which can lower the resonant frequency of the entire wall structure and this reduces the zone by which wall rigidity begins to dominate transmission loss, and again, the lower this is the better. Not only does damping lower it, it also damps the resonance so the Q becomes lower, making the impact of the wall resonance minimal. Then we have the mass controlled zone, and in the mass zone, CLD has multiple benefits. It does add even more mass, but it also provides a trapped damping layer that will dissipate the energy traveling through it. It creates an acoustic barrier for vibrations that don't allow it to travel directly through the material. Often changes in material acoustic impedance cause reflections, but the damping means it really mostly just dissipates the energy. There is also a magic component, namely some studies investigating this have found that accounting for mass and damping don't fully account for the transmission loss found in practice. Modeling of CLD is not all that accurate and its believed that there may be more going on than what mass and damping can account for. If I recall, studies have varied on the theory as to why, so I'm not really sure anymore what all the theories are, point is, in practice CLD has a lot of benefits that can't be achieved any other way. 


Hopefully this helps clarify these wall structures. I know the idea of drywall with a cement wall in between in the above example is confusing. It's not a great example. Certainly in a perfect world, if you created two walls with a 12" gap between them, it has the mass of cement or really lead with the damping properties of lead and the stiffness of jello we would have a much higher transmission loss than we would in any of the real world examples. The problem is its really hard to hang a picture on a massive jello wall, nor does it take paint all that well.


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## ramesh_cm79

*Media room sound transmission help!*

Hi All,
We recently bought a home that has a dedicated media room right above a two car garage. The garage and media room extend out from the house so there is only one wall that is shared between the media room and the adjacent game room. The room is already finished and I am not looking to do full sound proofing but I would like to at least do something to the shared wall. My current plan is as follows:

1) The shared wall is 6" and it has no insulation now. Rest of the three external walls have insulation. I am planning to at least fill the shared wall with blown in insulation.
2) Apply a second layer of drywall with GG - only for the shared wall
3) Replace the double door with solid door (with some added mass, still need to research)

I will be doing the following sound treatments within the room - Fabric walls with 2" insulation all around, false wall with AT screen, bass traps in the corners and also planing to build stage and a soffit that could be used as bass traps. I understand these treatments won't help with the sound transmission coming from or going outside the room but just wanted to mention in case it matters.


Would the above give me any benefits at all or will it be a wasted effort? If someone is talking in the two-story family room lower level, I can hear them clearly inside the media room when the double doors are closed. My goal is not to fully sound proof but at least cut down the sound transmission by 50 to 60%. Would really appreciate any help/suggestions on what I can possibly do without ripping apart the existing walls.

Thanks in advance!


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## Ladeback

ramesh_cm79 said:


> Hi All,
> We recently bought a home that has a dedicated media room right above a two car garage. The garage and media room extend out from the house so there is only one wall that is shared between the media room and the adjacent game room. The room is already finished and I am not looking to do full sound proofing but I would like to at least do something to the shared wall. My current plan is as follows:
> 
> 1) The shared wall is 6" and it has no insulation now. Rest of the three external walls have insulation. I am planning to at least fill the shared wall with blown in insulation.
> 2) Apply a second layer of drywall with GG - only for the shared wall
> 3) Replace the double door with solid door (with some added mass, still need to research)
> 
> I will be doing the following sound treatments within the room - Fabric walls with 2" insulation all around, false wall with AT screen, bass traps in the corners and also planing to build stage and a soffit that could be used as bass traps. I understand these treatments won't help with the sound transmission coming from or going outside the room but just wanted to mention in case it matters.
> 
> 
> Would the above give me any benefits at all or will it be a wasted effort? If someone is talking in the two-story family room lower level, I can hear them clearly inside the media room when the double doors are closed. My goal is not to fully sound proof but at least cut down the sound transmission by 50 to 60%. Would really appreciate any help/suggestions on what I can possibly do without ripping apart the existing walls.
> 
> Thanks in advance!


I believe the blown instillation will help and a second layer of dry wall with GG will help even more, but removing the dry wall, adding clips, hat channel, DD with GG, I would think would be better. If you have enough room you could add another wall an inch out from the other, insulate it, then clips, hat channel, DD and GG. You could then use a double door system. The questions is that may stop the noise from that main door, but what about sound from below or what gets out. I take it since this is over the garage there are no other connecting bedrooms that could be affected?

I am no expert so hopefully @HTGeek will chime in and either agree with me or give you better advice. Soundproofing is a big topic on here.


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## ramesh_cm79

Ladeback said:


> I believe the blown instillation will help and a second layer of dry wall with GG will help even more, but removing the dry wall, adding clips, hat channel, DD with GG, I would think would be better. If you have enough room you could add another wall an inch out from the other, insulate it, then clips, hat channel, DD and GG. You could then use a double door system. The questions is that may stop the noise from that main door, but what about sound from below or what gets out. I take it since this is over the garage there are no other connecting bedrooms that could be affected?
> 
> I am no expert so hopefully @HTGeek will chime in and either agree with me or give you better advice. Soundproofing is a big topic on here.


Thank you for the response. Never heard of the double door system but it's interesting as I won't have to replace the current french doors which are 48" wide (both combined) with a single 36" solid door. But I may not have enough room for this as I have only 14' to work and 4 recliners (existing) at each row. I will double check the dimensions before ruling this option out. I am open to removing the drywall on the shared wall and using the clips and hat channel if it gives a significant improvement. Don't really care about what gets out from the exterior walls and since the garage is below, I might be okay.


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## Mpoes12

ramesh_cm79 said:


> Thank you for the response. Never heard of the double door system but it's interesting as I won't have to replace the current french doors which are 48" wide (both combined) with a single 36" solid door. But I may not have enough room for this as I have only 14' to work and 4 recliners (existing) at each row. I will double check the dimensions before ruling this option out. I am open to removing the drywall on the shared wall and using the clips and hat channel if it gives a significant improvement. Don't really care about what gets out from the exterior walls and since the garage is below, I might be okay.




It sounds like having communicating doors is a bit of an issue for you and I might consider other options. What you do depends on budget. Soundproof doors that are purpose made for theaters are quite expensive, around $2000 on up per door. Ensuring that the doors are solid core, as thick as possible, and have gasketing will minimize sound transmission. Can you share the door construction? Is it solid core? Does it have glass?


French doors need a special kind of gasket known as a style gaskets. Pemko makes these. Don't overdo this. A lot of people use gaskets for soundproofing pointlessly. If your doors STC rating is fairly minimal, then providing more than just a basic foam gasket is wasteful. There is no advantage to using a more advanced gasket in such a situation. A solid core door with a Masonite or particle board core is typically around STC 20 to STC 30 and no higher. This doesn't need a very good gasket. Some people add another layer of MDF or plywood to their existing doors with green glue, and in this case my best guess is that it may add about 5-10 STC points to the door. I've not seen any testing of such a door so its hard to know.


My biggest concern for you is that your proposal may not realize a lot of transmission loss for the effort. Adding a second layer of drywall with green glue does not provide a significant amount of additional sound loss when you have 16" wood studs and no additional measures to address transmission loss, such as flanking paths. Taking down the drywall and adding clips and hat channel will make a big difference. I would give it serious consideration. If you want to think of what gives you most bang for the buck, where addressing all problems is equal to 100%, then adding greenglue and drywall is like 20%-30%, where as Clips, hat channel, and two layers of drywall with green glue is more like 65% to 75%. Most of the STC points starts with the decoupling provided by the hat channel.


Another concern with realizing the sound blocking gains that you desire is flanking paths. Without knowing what I'm dealing with, its hard to provide concrete suggestions. I imagine HVAC is shared between this room and the rest of the house, so sound will leak from the theater to the rest of the house. Depending on how direct, it may leak quite a bit. It is also possible that there is a common attic space above the theater and game room, and so this could be another area where a lot of flanking could take place. The floor could be a flanking path, outlets, etc. I'd spend time thinking about where sound will leak from the theater room to the rest of the house. Imagine you filled the theater with water and just kept pumping more water in. Where would it go? Wherever it goes is where sound will leak.


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## Mpoes12

doveman said:


> Sure but what I found most confusing is the idea that an airgap either side of a concrete wall is actually a single large airgap, even though there's a concrete wall in the middle of it! I'm not sure why having an existing layer of drywall/plaster attached directly to one or both sides of the concrete wall would change that either.
> 
> 
> 
> Yeah, the article says that attaching drywall directly to the concrete block wall creates "an unavoidable tiny air cavity between the drywall and the block" and I presume the same applies to using two layers of drywall and as the resonant frequency is higher the smaller the airgap, this is obviously a bad thing. I guess this is the main reason for using Green Glue between the two drywall layers, to fill this gap, although I'm not sure it can do that entirely as from what I've seen it's not applied in a coat that covers the entire surface, so I imagine some small gaps will remain which can still resonate.




Any airgap on either side of a concrete wall is not one large air gap. that is not a shared airgap, it is divided. The concrete wall is a leaf, its a massive massive barrier. I'm not sure where you are finding information that suggests that it is a single air gap. Can you point me to that?


----------



## Mpoes12

HT Geek said:


> If LF is a concern, that is when mass and damping come into play. More mass = less LFE transmission.



This isn't totally correct, and I hear it all the time. As I mentioned previously, there are three areas that impact sound transmission within a given frequency band. We can treat them like zones. The lowest frequencies are most impacted by the rigidity or stiffness of the material. This isn't to say that mass doesn't matter, but stiffness matters more. This is because the stiffness impacts its overall resonant frequency. The resonance causes a dip in the transmission loss and its Q is such that it basically kills the transmission loss from that point downward. The stiffer the material, the higher the resonance and the more LF area that has reduced transmission loss. If you add mass but also increase stiffness, you won't increase LF transmission loss as much as you would think. If you adjust for mass (standardize the transmission loss) then you will likely have worse transmission loss than before you added stiffness. 


Mass actually is most critical in the zone between the wall resonance frequency and the material resonance frequency (this causes the coincidence frequency) and thus matters for mid and high frequencies too. 


There is a really easy way to see this happening. What travels most readily through the cement slab of our basements? If you put your ear to the floor on the cement slab and plugged your open ear, you would hear the LF rumble of the HVAC, but you wouldn't hear the air rushing or other higher frequency sounds. That cement slab is fairly dense and massive, yet LF's travel readily through them. It's because it IS so dense and so stiff/rigid. If the slab was made of jello with equal mass and density then sound would not travel readily through it because it would have a far lower resonant frequency and far better damping properties.


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## ramesh_cm79

Mpoes12 said:


> It sounds like having communicating doors is a bit of an issue for you and I might consider other options. What you do depends on budget. Soundproof doors that are purpose made for theaters are quite expensive, around $2000 on up per door. Ensuring that the doors are solid core, as thick as possible, and have gasketing will minimize sound transmission. Can you share the door construction? Is it solid core? Does it have glass?
> 
> 
> French doors need a special kind of gasket known as a style gaskets. Pemko makes these. Don't overdo this. A lot of people use gaskets for soundproofing pointlessly. If your doors STC rating is fairly minimal, then providing more than just a basic foam gasket is wasteful. There is no advantage to using a more advanced gasket in such a situation. A solid core door with a Masonite or particle board core is typically around STC 20 to STC 30 and no higher. This doesn't need a very good gasket. Some people add another layer of MDF or plywood to their existing doors with green glue, and in this case my best guess is that it may add about 5-10 STC points to the door. I've not seen any testing of such a door so its hard to know.
> 
> 
> My biggest concern for you is that your proposal may not realize a lot of transmission loss for the effort. Adding a second layer of drywall with green glue does not provide a significant amount of additional sound loss when you have 16" wood studs and no additional measures to address transmission loss, such as flanking paths. Taking down the drywall and adding clips and hat channel will make a big difference. I would give it serious consideration. If you want to think of what gives you most bang for the buck, where addressing all problems is equal to 100%, then adding greenglue and drywall is like 20%-30%, where as Clips, hat channel, and two layers of drywall with green glue is more like 65% to 75%. Most of the STC points starts with the decoupling provided by the hat channel.
> 
> 
> Another concern with realizing the sound blocking gains that you desire is flanking paths. Without knowing what I'm dealing with, its hard to provide concrete suggestions. I imagine HVAC is shared between this room and the rest of the house, so sound will leak from the theater to the rest of the house. Depending on how direct, it may leak quite a bit. It is also possible that there is a common attic space above the theater and game room, and so this could be another area where a lot of flanking could take place. The floor could be a flanking path, outlets, etc. I'd spend time thinking about where sound will leak from the theater room to the rest of the house. Imagine you filled the theater with water and just kept pumping more water in. Where would it go? Wherever it goes is where sound will leak.


Thank you for the detailed response! Yeah, I am now realizing that I will have rip out the existing drywall on the shared wall and go with clips, hat channel and two layers of drywall with GG. I have asked for a quote (soundproofingcompany) on the material for this project. Should I be worried about the 3 exterior walls? I am not planning to touch those for now.

Regarding the double doors I have, they are builder grade light weight doors that have about 3/4" gap and are 48" wide. I am planning on reducing the size to 36" and get a solid core door. I will plan on using two MDF sheets with GG but still need to research on what other things I will need. I would like to keep the budget for the door under 500.

Yes, the room shares HVAC with rest of the house and has common attic with game room, two story family room and other areas. I understand that I won't be able to fully sound proof without addressing all these flanking paths but as long as it's not too bad at the lower level (in family room and kitchen) and on the other side of the house where kids sleep, I will be happy. Again, thanks for the response. Please let me know if you have any other suggestions that might help in my case.


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## Mpoes12

Can you describe in a bit more detail how you plan to make the door? Two .75" slabs of MDF adhered together with green glue? What about the edge? How will you ensure that green glue wont leak out or cover the seam? You want to do so in a manner that isn't too rigid (like I wouldn't use aluminum). Having resilient free ends helps reduce LF transfer, but otherwise isn't all that important. Green glue stays stick but doesn't drip once its "set." However I'd still make sure all seams are covered. Green glue will make a mess of your door handle inner workings.


Communicating doors provides way more sound isolation than the sandwich door your proposing, but would probably cause you to lose about 8" to 12" of floor space. This is what I have. I can take a picture if you like. My assembly is huge, I have a 14"+ wall with an 11" distance between door slabs. 


In a perfect world you should tear down all the walls and ceiling and do the whole thing. That is best because it will address many potential flanking paths and improve the rooms acoustics as well. However, I know that isn't realistic for everyone. The next best thing is to take down the ceiling and common wall and do that. Again, I know that isn't realistic for everyone. The next best thing is to do the common wall only with clips, hat channel, and two layers of drywall with green glue. Then also take measures to address all flanking paths you can see. Take a look at the outlets on the common wall to see if any outlets in the theater and the game room are back to back. This creates a hole directly through to the game room. Move the outlets at this time so they no longer are in line with each other. Even just raising them 5-6" is enough to resolve the problem.


In the attic I'm really unsure how significant this could be, I would need to know what is up there. I think the best option is to play some fairly loud music or test tones (or both) and measure the SPL in the theater, in the game room (with doors shut), and in the attic above the theater. If you have a smart phone the SPL meter apps are accurate enough for this purpose (you don't care about the actual number, only the relative difference. If you can do such a test and report the numbers back to us, that will help. 


If the attic has a lot of sound leaking into it, it will be good to find out where its coming from. Are their can/pot lights in the ceiling? Are they not well sealed? Are their other direct paths? Is it just the poor soundproofing of the ceiling in general? Is there any insulation up there? Insulation does not equal sound proofing, but...it does provide some transmission loss and it can provide absorption of sound that enters the attic through flanking paths and reduce its ability to travel out of the attic into other areas. If you have no other options to mitigate sound traveling through the ceiling, I would add insulation. At least you get something from that, maybe 3-4 db's of additional transmission loss at midrange and high frequencies. 


HVAC is a bigger issue. You will need to take a picture of the HVAC lines and describe what they look like, where they connect, and what is next in line. That all impacts how you treat it and with what. It's not as simple as just slapping in some acoustic flex duct and calling it a day. You have to make sure you address sound going down the HVAC line as well as in or out of the vent wall itself.


----------



## HT Geek

Mpoes12 said:


> This isn't totally correct, and I hear it all the time. As I mentioned previously, there are three areas that impact sound transmission within a given frequency band. We can treat them like zones. The lowest frequencies are most impacted by the rigidity or stiffness of the material. This isn't to say that mass doesn't matter, but stiffness matters more. This is because the stiffness impacts its overall resonant frequency. The resonance causes a dip in the transmission loss and its Q is such that it basically kills the transmission loss from that point downward. The stiffer the material, the higher the resonance and the more LF area that has reduced transmission loss. If you add mass but also increase stiffness, you won't increase LF transmission loss as much as you would think. If you adjust for mass (standardize the transmission loss) then you will likely have worse transmission loss than before you added stiffness.


Good points.

Unfortunately, Doveman's shared wall in his project currently is leaving him with an extremely limited space for sound deadening options.

@doveman, Mpoes12' comments got me reflecting back on our conversation several weeks ago....



doveman said:


> I've been told that the black stuff in my walls is cinder block, which is a low-quality version of concrete breeze block, although even the latter is apparently notorious for flanking. So that seems to explain why I have such issues with flanking and suggests there's nothing I can do to stop the noise transferring from wall to wall, so will definitely have to build a room-within-a-room.



Which got me digging up some old research papers. Which leads me back to your question from mid-February: 



doveman said:


> I still need to know whether I can safely strip away all the plaster, back to the cinderblock....



To which you should now know that - aside from @Mpoes12's aforementioned comments/thoughts on your concrete walls, a simple step that will improve your sound deadening efforts is to seal your concrete wall(s). There is evidence that even doing just that will improve your sound TL. To wit:

_When the concrete block is porous, sealing
the surface with plaster or block sealer
significantly improves the sound insulation;
the more porous the block, the greater
the improvement. Improvements of 5 to
10 STC points, or even more, are not
uncommon for some lightweight block
walls after sealing. Conversely, normal weight
blocks usually show little or no
improvement after sealing. This improvement
in STC in lightweight blocks is related
to the increased airflow resistivity of these
blocks. The leakage of sound through the
material of the block is different only in
degree from leakage of sound through
inadequate mortar joints. To ensure good
sound insulation, mortar joints must always
be properly finished — that is, free from
obvious penetrations.
_

- _*Controlling Sound Transmission through Concrete Block Walls*_ (Andy Warnock, Construction Technology Update No. 13, 1998).

I know Andy was talking about STC, which is why I said generally. He didn't publish all the TL charts in that paper, so we can't say if his statements were universal in a given frequency zone. Regardless, attempting to isolate LFE is notoriously confounding and meanwhile there is nothing negative about improving your wall's STC rating if these factors apply. So, it is more food-for-thought for you.

This concept would be accretive to to any other sound proofing measures you choose to undertake. 

Given the very limited space constraints for sound proofing you have along one shared wall in particular, this information might be helpful.


----------



## Mpoes12

HT Geek said:


> Good points.
> 
> Unfortunately, Doveman's shared wall in his project currently is leaving him with an extremely limited space for sound deadening options.
> 
> @*doveman* , Mpoes12' comments got me reflecting back on our conversation several weeks ago....
> 
> 
> 
> 
> Which got me digging up some old research papers. Which leads me back to your question from mid-February:
> 
> 
> 
> 
> To which you should now know that - aside from @*Mpoes12* 's aforementioned comments/thoughts on your concrete walls, a simple step that will improve your sound deadening efforts is to seal your concrete wall(s). There is evidence that even doing just that will improve your sound TL. To wit:
> 
> _When the concrete block is porous, sealing
> the surface with plaster or block sealer
> significantly improves the sound insulation;
> the more porous the block, the greater
> the improvement. Improvements of 5 to
> 10 STC points, or even more, are not
> uncommon for some lightweight block
> walls after sealing. Conversely, normal weight
> blocks usually show little or no
> improvement after sealing. This improvement
> in STC in lightweight blocks is related
> to the increased airflow resistivity of these
> blocks. The leakage of sound through the
> material of the block is different only in
> degree from leakage of sound through
> inadequate mortar joints. To ensure good
> sound insulation, mortar joints must always
> be properly finished — that is, free from
> obvious penetrations.
> _
> 
> - _*Controlling Sound Transmission through Concrete Block Walls*_ (Andy Warnock, Construction Technology Update No. 13, 1998).
> 
> I know Andy was talking about STC, which is why I said generally. He didn't publish all the TL charts in that paper, so we can't say if his statements were universal in a given frequency zone. Regardless, attempting to isolate LFE is notoriously confounding and meanwhile there is nothing negative about improving your wall's STC rating if these factors apply. So, it is more food-for-thought for you.
> 
> This concept would be accretive to to any other sound proofing measures you choose to undertake.
> 
> Given the very limited space constraints for sound proofing you have along one shared wall in particular, this information might be helpful.



Do you know if the concrete wall was exposed in that study or covered by drywall and what other properties existed? Is the paper available online?


Those numbers are surprising and make me wonder the conditions. There is some research that shows that paint alone improves STC values for standard walls, but only at higher frequencies and only slightly. It makes it more reflective and provides some damping. In a concrete wall I just can't imagine what it could do to provide as much as 10 STC points? It won't add meaningful mass. It will add damping, but it would have to be a lot of paint to provide enough to matter. It will seal the surface, but paint isn't massive enough to block low frequency sounds so you would think it would have minimal impact on an overall STC rating. The only thing I can think of is that the porous nature of cinder blocks causes it to act more like a stiff foam and that sound can travel through the cinder blocks readily. Sealing it might only make a big difference at higher frequencies, but that its so big it impacts the overall STC a surprising amount. If that is true, I still wonder why it would matter if the cinderblock is inside a drywalled structure. The drywall would already block a lot of the higher frequencies. Assuming what he found is true and true of all cinderblock structures, maybe we should all be painting and sealing our cement basements, even if they aren't cinderblock. Even concrete is pretty porous. I have a good 12" of exposed concrete around the perimeter of my house (at least in sections) that might provide flanking paths for sound to get out or even back into the house. 


This is an aside, but I had explored the idea of intentionally building a theater space with decoupled cinderblock walls as an outer shell and decoupled inner drywall walls for the inner shell. I took a course on soundproofing and the course was taught from an engineering standpoint for building soundproof facilities or commercial buildings, not home theaters, so cement was a common ingredient (and you can modify cement to be less rigid and better damped). What I later learned was that when you use something as massive as cement, you have to account for its weight in the floor and footings. In a residential construction, that would mean jacking up the slab floor of the basement and starting over. The only way to provide something like 50-80 db's of transmission loss in the low bass is with giant decoupled floppy and well damped walls, and the only way to do that is basically impossible in a residential structure. I'm sure everyone gets ideas that they will somehow do it bigger and better than anyone else, and then they get quotes and scopes of work and quickly switch course.


----------



## HT Geek

Mpoes12 said:


> Do you know if the concrete wall was exposed in that study or covered by drywall and what other properties existed? Is the paper available online?


That particular example was exposed concrete. Warnock tested a variety of scenarios, including gypsum attached to concrete, studs in between, etc. AFAIK, they were lab tests. I'd imagine it's online somewhere, but I've attached it to this post. 

Here's an example of a dot plot in the paper demonstrating the range of concrete block densities tested:











As you can, it has a linear slope that shows a positive correlation between density and STC, when isolating the uniform mass of concrete blocks in a single layer wall.


The quote I referenced previously is on page 2. Incidentally, Warnock's observations also support your previous comments:

*Concrete Block Walls with Gypsum Board Added*
_Adding gypsum board supported on furring
or studs at a distance from the surface of
the block wall can greatly improve the
sound insulation of the wall assembly.

Three factors that govern the degree of
improvement are:
1. The method of support — ideally, the
gypsum board should not be solidly
connected to the block;
2. The depth of the cavity (the distance
between facing surfaces of the block and
the gypsum board);
3. The use of sound-absorbing material in
the cavity between the gypsum board
and the surface of the block.

If the furring supporting the gypsum board
is rigid, sound can travel directly through it
from the gypsum board to the blocks.
However, if the furring is sufficiently flexible,
the sound will be attenuated. But the best
method of support for the gypsum board is
the use of independent studs that have no
direct connection to the block._




> Those numbers are surprising and make me wonder the conditions. There is some research that shows that paint alone improves STC values for standard walls, but only at higher frequencies and only slightly. It makes it more reflective and provides some damping. In a concrete wall I just can't imagine what it could do to provide as much as 10 STC points? It won't add meaningful mass. It will add damping, but it would have to be a lot of paint to provide enough to matter. It will seal the surface, but paint isn't massive enough to block low frequency sounds so you would think it would have minimal impact on an overall STC rating. The only thing I can think of is that the porous nature of cinder blocks causes it to act more like a stiff foam and that sound can travel through the cinder blocks readily. Sealing it might only make a big difference at higher frequencies, but that its so big it impacts the overall STC a surprising amount. If that is true, I still wonder why it would matter if the cinderblock is inside a drywalled structure.


I can't say for sure, but if I were to speculate, perhaps it is plugging a form of flanking. Warnock mentions that stuffing insulation into porous concrete (one of his tests) had no effect on the STC when the insulation stuffed inside was the only modification to the wall.

I'll just add that Warnock was not looking at LFE in particular, but rather simply comparing STC values amongst different scenarios.




> The drywall would already block a lot of the higher frequencies. Assuming what he found is true and true of all cinderblock structures, maybe we should all be painting and sealing our cement basements, even if they aren't cinderblock. Even concrete is pretty porous. I have a good 12" of exposed concrete around the perimeter of my house (at least in sections) that might provide flanking paths for sound to get out or even back into the house.


Indeed. 




> This is an aside, but I had explored the idea of intentionally building a theater space with decoupled cinderblock walls as an outer shell and decoupled inner drywall walls for the inner shell. I took a course on soundproofing and the course was taught from an engineering standpoint for building soundproof facilities or commercial buildings, not home theaters, so cement was a common ingredient (and you can modify cement to be less rigid and better damped). What I later learned was that when you use something as massive as cement, you have to account for its weight in the floor and footings. In a residential construction, that would mean jacking up the slab floor of the basement and starting over. The only way to provide something like 50-80 db's of transmission loss in the low bass is with giant decoupled floppy and well damped walls, and the only way to do that is basically impossible in a residential structure. I'm sure everyone gets ideas that they will somehow do it bigger and better than anyone else, and then they get quotes and scopes of work and quickly switch course.


Good info.


----------



## Mpoes12

All very interesting. 


Sent from my iPhone using Tapatalk


----------



## doveman

Mpoes12 said:


> Any airgap on either side of a concrete wall is not one large air gap. that is not a shared airgap, it is divided. The concrete wall is a leaf, its a massive massive barrier. I'm not sure where you are finding information that suggests that it is a single air gap. Can you point me to that?


Yeah, it didn't make much sense to me either but as they seem to know what they're talking about on that site it confused me. 

On http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ for Assembly III, where there's a furring strip and drywall on one side of the wall they say "the air cavity is larger now" when compared to drywall attached directly to the concrete, which is obviously true. Then for Assembly IV, where there's furring strip and drywall on both sides they say "This will give us the largest air cavity yet". Clearly it doesn't result in an air cavity any bigger than in Assembly III, there's just two of the same size now, one either side of the wall, so effectively it's a triple-leaf and with two quite small airgaps, certainly not massive ones, as it suggests up the page under "WHAT IS THE TRIPLE LEAF EFFECT?" are the only sort you want in a triple-leaf.


----------



## HT Geek

doveman said:


> Yeah, it didn't make much sense to me either but as they seem to know what they're talking about on that site it confused me.
> 
> On http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ for Assembly III, where there's a furring strip and drywall on one side of the wall they say "the air cavity is larger now" when compared to drywall attached directly to the concrete, which is obviously true. Then for Assembly IV, where there's furring strip and drywall on both sides they say "This will give us the largest air cavity yet". Clearly it doesn't result in an air cavity any bigger than in Assembly III, there's just two of the same size now, one either side of the wall, so effectively it's a triple-leaf and with two quite small airgaps, certainly not massive ones, as it suggests up the page under "WHAT IS THE TRIPLE LEAF EFFECT?" are the only sort you want in a triple-leaf.


They are basically contending in the case of a triple leaf concrete wall with small air gaps, the wall doesn't act like a triple leaf. Or that it doesn't have the negative connotations typically associated with a triple leaf effect. If you look at data on the effect of triple leafs in typical stud construction walls you will see why it's recommended to avoid doing that. SPC is claiming with concrete walls the sound wave behavior differs from a triple leaf wood or metal stud wall. The graphs indicate the data is from the NRC, but do not cite any papers or lab reports. If you're really interested in digging into the actual lab data, I would suggest reaching out to SPC and asking them to provide you with references for their claims.

I agree it is confusing, but if you apply their logic very narrowly to concrete walls only and also note their final conclusion at the bottom of the page, I see their point. They also note that concrete walls in this scenario are uncommon. Here's their final statement at the bottom of the page: "Bottom Line: For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key. While lower frequencies still suffer, the great majority of the frequency spectrum is improved."

What's really interesting IMHO is their statement that it's possible to improve overall TL and get a higher STC but at the expense of increased LFE transmission. This seems (to me at least) consistent with the information I dug up in the 1998 NRC paper by Andy Warnock on concrete walls, and @Mpoes12's training and observations that he has relayed above.


----------



## Mpoes12

Ha! Ok lets not overstate my "training." I have a PhD in child development, not engineering. I took a coursera course on acoustic physics that happened to delve into transmission loss (really focusing in on how sound waves behave when they hit a barrier and things of that nature). I like to learn and like to think I'm relatively smart, but this isn't my field or something I do for a living. I've worked in home theater installation and room design on and off in the past, but either as a side job or for extra money when I was in school, and that is really the only direct real world experience I had with this. I feel like what I'm good at is understanding the physics that underlie these issues, not necessarily fully understanding the real world or practical aspects. I talked to Ted at SPC a lot for help with my build because practical solutions to soundproofing problems is his expertise. 


Concrete is very rigid so my guess is that its typically not a great LF barrier. Cement has better damping properties than say steel or even plywood, but it is not as good as drywall, lead, rubber, etc. When I had looked into the idea of using concrete as the outershell, what I found was that even commercial use of concrete in soundproof labs typically involved modifying the mixture to be better damped and a bit more lossy. As I mentioned a few times, a lot of people overstate the role that mass plays by misunderstanding the behavior at the lowest frequencies. They then assume that the more massive the structure the more LF transmission loss, without accounting for the effect of stiffness. Stiffness matters a lot and our room's have compromised LF transmission loss largely due to being overly stiff. I honestly believe that people who have built their rooms using chipboard or plywood as the first layer in their sandwich wall have worse soundproofing than those who used all drywall.


I think the next step for soundproofing in residential homes that will lead to even greater LF loss will be a new kind of wall board that is less rigid. I'd love to see someone willing to work with a wallboard manufacturer to develop a core that is more lossy and less rigid. I think if we had that, it was made thicker, denser, etc. we would be able to take residential soundproofing another step forward by adding a good 10+ db's of TL at the lower frequencies and a bit more up higher as well. 


There may also be ways to improve upon green glue. In some experiments I did with an accelerometer and some sandwich boards I made to test CLD speaker enclosure ideas, a product made of 40 shore casting urethane with a bunch of fillers provided better damping than green glue. The problem is the set time is short and trying to use it on a wall would be pretty much impossible. It's also about 3 times the price of green glue. I am curious to see what it would do for transmission loss in a wall, but at that price and difficulty of working with, I imagine its not worth it.


----------



## doveman

HT Geek said:


> I agree it is confusing, but if you apply their logic very narrowly to concrete walls only and also note their final conclusion at the bottom of the page, I see their point. They also note that concrete walls in this scenario are uncommon. Here's their final statement at the bottom of the page: "Bottom Line: For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key. While lower frequencies still suffer, the great majority of the frequency spectrum is improved."
> 
> What's really interesting IMHO is their statement that it's possible to improve overall TL and get a higher STC but at the expense of increased LFE transmission. This seems (to me at least) consistent with the information I dug up in the 1998 NRC paper by Andy Warnock on concrete walls, and @Mpoes12's training and observations that he has relayed above.


The idea that I might make the LFE transmission worse does concern me. I believe the average frequency range for human speech varies from 80 to 260 Hz, 85 to 180 Hz for a man and 165 to 255 Hz for a woman, although it may extend from 50-500hz. So if I've got a loud male neighbour the increased transmission at 160hz and below as shown in Assembly IV could be a problem and even adding insulation as in Assembly V doesn't make it as good as the concrete wall alone.

Similarly, if impact noise is transferring from upstairs (or downstairs) into the walls and that is in the LFE range, that could be made worse.

Whilst building a decoupled (other than IB clips) stud wall in the HT room might deal with any such LFE problems, that's not an option on the living room side due to lack of space, so I want to make sure I'm not going to waste my time and money doing what I can to that side (e.g. adding a layer of plasterboard directly to the existing wall; sticking MLV to the wall then screwing 15mm plasterboard through that into the existing wall; stripping the existing plaster and fitting hat channel and possibly insulation with two layers of 15mm plasterboard on top) only to find that overall it's of no benefit. 

I should qualify that and say that certainly a decoupled wall of the spec I'm contemplating in the HT room won't fit in the living room but if I strip off the plaster so that I have 5.5-6cm to play with, I could build a 25mm decoupled stud wall spaced 10mm from the concrete, fit insulation between the studs and attach at least one layer 15mm drywall directly to it (i.e. without hat channel) but the question is a) whether 25mm studs are going to be strong enough and b) whether such a construction would ensure that no speech/impact noise/reasonable volume TV transfers from or into the concrete wall or if one of the non-decoupled options would be as good or better.

Regarding the points you've raised about sealing the concrete wall, I'd have thought that the existing two layers of plaster (with wallpaper on top in the HT room, I've stripped it from the living room side) would achieve that and certainly the wall still carries transmits speech quite badly. Obviously it might be even worse without the plaster though and if I do strip the existing plaster it might be sensible to use a thin layer of plaster or something to seal it again before doing anything else to it, so thanks for raising it.


----------



## doveman

Mpoes12 said:


> As I mentioned a few times, a lot of people overstate the role that mass plays by misunderstanding the behavior at the lowest frequencies. They then assume that the more massive the structure the more LF transmission loss, without accounting for the effect of stiffness. Stiffness matters a lot and our room's have compromised LF transmission loss largely due to being overly stiff. I honestly believe that people who have built their rooms using chipboard or plywood as the first layer in their sandwich wall have worse soundproofing than those who used all drywall.


It's interesting you mention that as I was just reading that it might be a good idea to use plywood or OSB as the first layer, as it will allow things to be screwed on the wall anywhere. I guess with two layers of plasterboard you can only safely screw stuff through them into the studs and the studs won't always be exactly where you want to fix your TV, etc, not to mention that screwing through the plasterboard into the studs might compromise the benefits of using hat channel between them. So I guess if you're never going to screw anything to the walls then two layers of plasterboard is best but otherwise it might not be so straightforward.


----------



## HT Geek

doveman said:


> The idea that I might make the LFE transmission worse does concern me. I believe the average frequency range for human speech varies from 80 to 260 Hz, 85 to 180 Hz for a man and 165 to 255 Hz for a woman, although it may extend from 50-500hz. So if I've got a loud male neighbour the increased transmission at 160hz and below as shown in Assembly IV could be a problem and even adding insulation as in Assembly V doesn't make it as good as the concrete wall alone.


True, but of course the volume or intensity that you wish to mitigate is crucial. 




> Regarding the points you've raised about sealing the concrete wall, I'd have thought that the existing two layers of plaster (with wallpaper on top in the HT room, I've stripped it from the living room side) would achieve that and certainly the wall still carries transmits speech quite badly. Obviously it might be even worse without the plaster though and if I do strip the existing plaster it might be sensible to use a thin layer of plaster or something to seal it again before doing anything else to it, so thanks for raising it.


Yes, it seems clear that sealing a porous concrete surface is low-hanging fruit.

One more issue I thought I'd bring up is the fact that concrete is reflective of sound inside the same room if not treated or covered with an absorptive veneer. This is just something else for you to consider. Let's imagine you left the living room side wall alone (bare concrete), other than to seal it. Within your HT room you will find many audio waves hitting that wall will easily reflect off of it. I'm just pointing this out as it may have an impact on your decision of how to handle the wall. Treating it might not improve sound transmission from the other side a whole lot, but could have an added benefit of improving intra-room acoustics. Just more food-for-thought.


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## Mpoes12

doveman said:


> It's interesting you mention that as I was just reading that it might be a good idea to use plywood or OSB as the first layer, as it will allow things to be screwed on the wall anywhere. I guess with two layers of plasterboard you can only safely screw stuff through them into the studs and the studs won't always be exactly where you want to fix your TV, etc, not to mention that screwing through the plasterboard into the studs might compromise the benefits of using hat channel between them. So I guess if you're never going to screw anything to the walls then two layers of plasterboard is best but otherwise it might not be so straightforward.




Two important issues here. First, you can use OSB or Plywood as the first layer in one 4x8 section to hang something like a TV. Just use drywall everywhere else. Plan ahead as a way to avoid the issue. I'm not sure what you mean by screwing into studs. You can screw into the hat channel for extra capacity, but you can't screw into the studs. You will ground out the wall in that location. DO NOT SCREW DIRECTLY INTO STUD WHEN MOUNTING THINGS ON A SOUNDPROOF WALL!!!!!


Second, clips and hat channel have a weight capacity limit that is well below drywall screwed into studs. You can't mount heavy items to soundproof walls, regardless of what the first layer is. The problem is that the clips and hat channel have a limit and the hat channel could come out of the clips. There are different types of clips and heavier gauge hat channel, but that would negatively impact soundproofing. You have to be very careful what you mount onto walls once you have used hat channel and clips. The IB-1 clip I used has a weight limit of 36 lbs per clip. a 4'x4' section of wall will have roughly 5-6 clips. That allows 216lbs of weight on that set of clips. The drywall alone weighs about 75lbs for 2 sheets of 5/8". The green glue has weight as well. When all is said and done, you might be lucky to have a 100-150lbs margin left on that section of wall before exceeding the clip capacity. The hat channel also has a weight limit, but I forget what it is and if its less than the clip capacity or not. I do remember worrying about my ceiling, which has 3 layers of drywall. I used plywood for a 4x8 section where the projector would mount and added two more 4' sections of hat channel and clips to ensure the projector did not exceed the weight capacity. It very likely compromised soundproofing, but safety is more important.


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## fingersdlp

Posted to wrong thread - deleted.


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## doveman

HT Geek said:


> True, but of course the volume or intensity that you wish to mitigate is crucial.


Of course but if I can already hear my shouty neighbour on the other side of the party wall (the previous one didn't shout but had a very deep and booming voice that intruded even worse than the shouting and you can hardly complain about people talking in their normal voices) and impact noises, then it will clearly be unhelpful to do anything that will increase the transmission of such frequencies.



> One more issue I thought I'd bring up is the fact that concrete is reflective of sound inside the same room if not treated or covered with an absorptive veneer. This is just something else for you to consider. Let's imagine you left the living room side wall alone (bare concrete), other than to seal it. Within your HT room you will find many audio waves hitting that wall will easily reflect off of it. I'm just pointing this out as it may have an impact on your decision of how to handle the wall. Treating it might not improve sound transmission from the other side a whole lot, but could have an added benefit of improving intra-room acoustics. Just more food-for-thought.


I haven't decided whether to wallpaper or paint the living room side yet but I'm not sure I've understood what you mean here as you've referred to both the living room and the HT room. Are you saying that if I only sealed the living room side, this will result in sound in the HT room going through the wall, hitting the sealed layer on the other side and then reflecting back into the HT room? I would imagine that if I properly treat the HT room, so that the sound isn't able to reach the concrete wall (at least not in any amount to be worried about) and sound is prevented from travelling from the concrete wall (whether the source is my living room or a neighbouring flat) into the HT room, then there won't be any issues with sound reflecting back from the living room side.

The main reason I'm thinking of treating the living room side is to prevent noise that's getting into the concrete wall from neighbouring flats intruding into my living room (and vice-versa) rather than to provide any additional isolation between my HT room and my living room, which I'm hoping the HT room treatment will be sufficient for.

Referring back to http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ another reason it confuses me is because it starts off explaining that the smaller the airgap, the higher the resonant frequency and higher frequencies are more common so the wall will resonate more often - see under "WHAT CAN WE DO WITH THIS RESONANCE INFORMATION?" where it shows a small airgap with a resonant frequency of 80hz and a larger airgap with one of 50hz. That makes sense but then the test results for the various assemblies seems to show that the bigger the airgap, the worse the transmission loss for the lower frequencies, other than for Assembly V where the added insulation mimics a larger space and the results are better than for Assembly IV without it.

Now maybe "worse transmission loss" is a different issue than "increased resonance" but even so, if we increase the airgap to lower the resonant frequency to 50hz where it will be less of a problem but in doing so, we increase the transmission in the 80-160hz range then that complicates matters. I wonder what resonant frequency I can expect with a 10mm gap, 50mm stud wall filled with insulation, hat channel and two layers of drywall? I guess it will effectively be a single gap of 10mm+50mm+22mm between the concrete wall and the first layer of drywall but the insulation will make it act as a somewhat larger space.


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## doveman

Mpoes12 said:


> Two important issues here. First, you can use OSB or Plywood as the first layer in one 4x8 section to hang something like a TV. Just use drywall everywhere else. Plan ahead as a way to avoid the issue. I'm not sure what you mean by screwing into studs. You can screw into the hat channel for extra capacity, but you can't screw into the studs. You will ground out the wall in that location. DO NOT SCREW DIRECTLY INTO STUD WHEN MOUNTING THINGS ON A SOUNDPROOF WALL!!!!!


I did think it was a bad idea but didn't see how it could be avoided if one wanted to hang things safely. I'll have to think about where I might want to hang things and plan ahead as you suggest, although I fear that compromising the soundproofing by using plywood anywhere in the first layer of a wall would make it pointless having the rest of that first layer as drywall and if I absolutely needed to do that I might as well just use plywood for the entire first layer.



> Second, clips and hat channel have a weight capacity limit that is well below drywall screwed into studs. You can't mount heavy items to soundproof walls, regardless of what the first layer is. The problem is that the clips and hat channel have a limit and the hat channel could come out of the clips. There are different types of clips and heavier gauge hat channel, but that would negatively impact soundproofing. You have to be very careful what you mount onto walls once you have used hat channel and clips. The IB-1 clip I used has a weight limit of 36 lbs per clip. a 4'x4' section of wall will have roughly 5-6 clips. That allows 216lbs of weight on that set of clips. The drywall alone weighs about 75lbs for 2 sheets of 5/8". The green glue has weight as well. When all is said and done, you might be lucky to have a 100-150lbs margin left on that section of wall before exceeding the clip capacity. The hat channel also has a weight limit, but I forget what it is and if its less than the clip capacity or not. I do remember worrying about my ceiling, which has 3 layers of drywall. I used plywood for a 4x8 section where the projector would mount and added two more 4' sections of hat channel and clips to ensure the projector did not exceed the weight capacity. It very likely compromised soundproofing, but safety is more important.


I wasn't planning on using hat channel and clips on the inner side (facing the room) of the studs, just hat channel with the drywall screwed into it. I wasn't even planning to fit hat channel on the outer side (facing the concrete wall) of the studs. If I did that, I'd have a much larger gap than 10mm between the studs and the concrete, as the hat channel alone is 22mm deep and with IB-1 clips it would be about 28.6mm. I haven't really got my head around what I'm supposed to use between the studs and the concrete wall to be honest. I was looking at the IB-3 http://www.soundproofingcompany.com/product/ib-3-bracket/ which is 1 and 3/4" deep or 44mm, which I guess will put the centre fixing point at 22mm and screwing it 12mm from the edge of the 50mm noggins will put the stud wall at 10mm from the concrete. They could only be fixed to the horizontal noggins though, not the vertical studs, so I don't know if that will be a problem.


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## HT Geek

doveman said:


> I haven't decided whether to wallpaper or paint the living room side yet but I'm not sure I've understood what you mean here as you've referred to both the living room and the HT room. Are you saying that if I only sealed the living room side, this will result in sound in the HT room going through the wall, hitting the sealed layer on the other side and then reflecting back into the HT room?


No... no.... I should have just said whatever room a concrete wall is in, it's going to reflect sound back inside that room. I've lost of track of where your living room wall is in relation to the other and the HT room, so let's just keep it more simplistic for the purpose of this subject. Here's a crude attempt at a diagram:

sound --->>> [ WALL ]


>
sound --->>>


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## Mpoes12

doveman said:


> I wasn't planning on using hat channel and clips on the inner side (facing the room) of the studs, just hat channel with the drywall screwed into it. I wasn't even planning to fit hat channel on the outer side (facing the concrete wall) of the studs. If I did that, I'd have a much larger gap than 10mm between the studs and the concrete, as the hat channel alone is 22mm deep and with IB-1 clips it would be about 28.6mm. I haven't really got my head around what I'm supposed to use between the studs and the concrete wall to be honest. I was looking at the IB-3 http://www.soundproofingcompany.com/product/ib-3-bracket/ which is 1 and 3/4" deep or 44mm, which I guess will put the centre fixing point at 22mm and screwing it 12mm from the edge of the 50mm noggins will put the stud wall at 10mm from the concrete. They could only be fixed to the horizontal noggins though, not the vertical studs, so I don't know if that will be a problem.


I feel like we are talking about different things here. I wasn't referencing hat channel on the concrete wall side. I was saying that when you create decoupled walls, the side inside the room now has weight capacity limits that are well below a normal wall. 


Between the studs and concrete wall you should have insulation. No drywall. That adds an extra pointless leaf, you don't want that.


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## HT Geek

Mpoes12 said:


> Two important issues here. First, you can use OSB or Plywood as the first layer in one 4x8 section to hang something like a TV. Just use drywall everywhere else. Plan ahead as a way to avoid the issue.


Just gonna chime in here with my 2 cents FWIW. 

I did 1st layer OSB in my HT room, for a few reasons. First, I wasn't certain where a few things would go and having the ability to 'stick a screw' almost anywhere seemed advantageous. Second, my understanding was OSB and plywood had a different resonant frequency that drywall, and about the same weight. It seemed logical to me that could be a good thing. Third, the increased stiffness of the walls and ceiling had the benefit of spreading the load of the walls more evenly (and anything attached to them).

No matter what you do in the HT world, you are going to keep coming back to one universal truth: there is not a single best way to do everything, because every decision you make has trade-offs. Therefore, you must decide what your priorities are, and accept the fact you will face mild defeats with some of your secondary goals. 




> I'm not sure what you mean by screwing into studs. You can screw into the hat channel for extra capacity, but you can't screw into the studs. You will ground out the wall in that location. DO NOT SCREW DIRECTLY INTO STUD WHEN MOUNTING THINGS ON A SOUNDPROOF WALL!!!!!


True for clips & channel walls, but clarifying it's less of an issue for double-stud or staggered stud walls (you're screwing the drywall into them to begin with). 




> Second, clips and hat channel have a weight capacity limit that is well below drywall screwed into studs. You can't mount heavy items to soundproof walls, regardless of what the first layer is. The problem is that the clips and hat channel have a limit and the hat channel could come out of the clips. There are different types of clips and heavier gauge hat channel, but that would negatively impact soundproofing. You have to be very careful what you mount onto walls once you have used hat channel and clips. The IB-1 clip I used has a weight limit of 36 lbs per clip. a 4'x4' section of wall will have roughly 5-6 clips. That allows 216lbs of weight on that set of clips. The drywall alone weighs about 75lbs for 2 sheets of 5/8". The green glue has weight as well. When all is said and done, you might be lucky to have a 100-150lbs margin left on that section of wall before exceeding the clip capacity.


Excellent point that cannot be driven home enough. Don't overload your clips or channel!


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## Mpoes12

HT Geek said:


> It just demonstrates that LFE does not necessarily benefit from those air gaps when tested with a single leaf concrete wall. And it shows how other frequency ranges are affected. It seems useful in your case for predicting the outcome of various methods on your wall(s).



This is what I was talking about earlier. Walls have three zones that matter for sound isolation. The lower limit of a walls sound isolation is dictated by its resonant frequency. Ted never seems to mention rigidity, but that is the biggest factor impacting this. Adding insulation lowers the resonant frequency slightly and lowers its Q. That means the peak of the resonance is reduced and you get more transmission loss, but...with a lower Q you also have a wider area impacted by the resonance (still good to add insulation though). Making the cavity larger makes the resonance peak lower, but it can also make it bigger. That means you do lose some lf transmission loss. The best solution is to provide floppier walls with as big an air cavity as you can manage. Adding mass also lowers the resonance frequency and lowers its Q. Having it damped by green glue helps as well. 


I think the better sound isolation from a cement wall at low frequencies is dictated by two things. First I think the resonant frequency of the cement wall is fairly low (looking at the graph I think its around 125hz). I think it is so rigid and so massive it is actually hard to vibrate it at all. I think that makes the impact of the resonance fairly little. That's why big massive walls are good. The other reason is that I do think transmission loss measurements below the STC values are unreliable. These labs are often not certified reliable at such low frequencies. Studies have found that labs actually vary quite a bit amongst themselves. Even technicians can have varying results. This is with all the certification and standardization. Don't read too much into transmission loss values below 100hz or so.


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## GatorBlues

*Double Doors*

I've been unsuccessful in attempting to convince my wife that a single door, for better soundproofing, should be used instead of a double door. She wants the room to open up more for parties. I want it well soundproofed for movies. 

We will have either room within a room or soundproofing clips with hat channel. To save space in the theater room, I want the right side of the double doors to swing into the theater room against the wall, and the left side to swing away from the theater room. With all of the other efforts we are making to soundproof, I want the double doors to seal to each other in the middle and to the floor and door jam when closed. 

Does such a creature exist?

EDIT: What a difference a day makes. My wife relented this morning and is OK with a single door now. After weeks of insisting it had to be French doors, of course she changed her mind less than a day after I gave up trying to convince her and wrote my post above.


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## Ladeback

GatorBlues said:


> I've been unsuccessful in attempting to convince my wife that a single door, for better soundproofing, should be used instead of a double door. She wants the room to open up more for parties. I want it well soundproofed for movies.
> 
> We will have either room within a room or soundproofing clips with hat channel. To save space in the theater room, I want the right side of the double doors to swing into the theater room against the wall, and the left side to swing away from the theater room. With all of the other efforts we are making to soundproof, I want the double doors to seal to each other in the middle and to the floor and door jam when closed.
> 
> Does such a creature exist?


I am not sure, but I axed putting in double doors, because I want a dedicated room and better soundproofing verses having the room open for party's. My wife likes the idea of double doors or sliding barn doors like I first was thinking, but didn't want to have to try and soundproof them. You can do the door soundproofing on the bottom easy enough it's the middle that is hard. Hopefully others that know more will chime in.


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## Mpoes12

Anything is possible with time and money. There are custom sound proof door companies that can make soundproof French doors if you want. Your wife relenting to single doors is obviously cheaper and easier to manage. 

Doors are always a weak point in a soundproof wall. I have 1.75" solid slab communicating doors with double seals each and a 10-12" airgap. It is still the weak point in the wall. 


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## colbysheridan

cgott42 said:


> Quote:Originally Posted by *BasementBob*
> 
> There's single doors: wood hollow core, steel hollow core, wood solid core, steel fire door (aka steel hollow core, thicker steel, filled with insulation, often with better seals), custom door, professional acoustical doors.
> There's double doors: communicating doors (aka tandem doors, width of the double stud wall) , airlock doors (one man room), and lobby doors (a real room).
> ...
> Doors are remarkably sensitive to the seals they have, so a simple study of door types while indicative is not predictive of installed results. I seem to recall a bunch of multi frequency test results for single doors, where they glued the door into a test frame.
> 
> 
> Given that the soundproofing of the door is very sensitive to the sealing (small gaps let a lot of sound out) What about the door jambs - i.e. I am thinking of a solid core door + a 1x1 frame filled with insulation + DW+GG+DW. However isn't all the layers of DW,GG on the door a waste if it's surrounded by 1" of door jamb to easily transmit the sound - what do people do as every inch of the room is covered in 3 layers of DW +GG on top of the wood joists to prevent the wood joists from transmitting sound - and here on the door jamb is a clear path?








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## Mpoes12

Custom soundproof doors typically come prehung with a specially designed door jam. 

I can't speak for others but I honestly lost sleep over this. When we installed my communicating doors there was initially a .5" gap all around the camp and the wall. I thought this is nuts i can't leave it like this. I used green glue and drywall as the shim all around the jambs. I then went back in and sealed the jamb with acoustic caulk. I used solid poplar trim and glued it in place using acoustic caulk. That means my jambs aren't really a weak point. Lots of mass and totally air tight. 

I also lost sleep over the seals and stops. I have a stop made from 11" wide poplar by 7/8" thick. This is what my doors seal against. There is then a layer of cork adhered to the sealing surface and then pemko gaskets. 


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## Mpoes12

this is what the assembly looked like under construction. 

The inner door is 1.75" solid flush slab. The outer is 1.75 solid core panl type. If my wife had allowed it I would have used all flush type. They are better. 


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## Ladeback

Mpoes12 said:


> this is what the assembly looked like under construction.
> 
> The inner door is 1.75" solid flush slab. The outer is 1.75 solid core panl type. If my wife had allowed it I would have used all flush type. They are better.
> 
> 
> Sent from my iPhone using Tapatalk


So you must have a double wall in order for it to be that wide. I won't be doing that and I just planning on one thick would door.


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## Mpoes12

Ladeback said:


> So you must have a double wall in order for it to be that wide. I won't be doing that and I just planning on one thick would door.




Yes I have a double wall. 

It's my understanding that a single door really can't be made to equal of communicating doors, no matter how heavy, shirt of being a bank vault with concrete filled jambs. That implies to me that a single heavy door is likely always a compromise, which is why I went this route. Which isn't to say it's not a good enough solution, theaters are always full of compromises. No solution is perfect. 


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## doveman

HT Geek said:


> No... no.... I should have just said whatever room a concrete wall is in, it's going to reflect sound back inside that room. I've lost of track of where your living room wall is in relation to the other and the HT room, so let's just keep it more simplistic for the purpose of this subject. Here's a crude attempt at a diagram:
> 
> sound --->>> [ WALL ]
> 
> 
> >
> sound --->>>


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## doveman

Mpoes12 said:


> I feel like we are talking about different things here. I wasn't referencing hat channel on the concrete wall side. I was saying that when you create decoupled walls, the side inside the room now has weight capacity limits that are well below a normal wall.
> 
> Between the studs and concrete wall you should have insulation. No drywall. That adds an extra pointless leaf, you don't want that.


OK, thanks for the clarification. It's certainly helpful to be aware of the weight limits so that I can plan for that. I may well use OSB for the first layer throughout the HT room to give me flexibility in hanging stuff but I've got some time to think about that before I decide.

Would you say it's best to a) fill all the space between the concrete wall and the drywall (so the 10mm gap between the wall and the studs, the 50mm depth of the studs and the 22mm gap between the studs and the drywall created by the hat channel), or b) leave a small gap between the studs and the drywall, say 12mm, or c) leave the 10mm gap between the wall and the studs unfilled but fill the rest or d) just fill the 50mm depth of the stud wall and leave the 10mm gap and the 22mm gap unfilled?

From what I've read, it seems to be recommend to not fill the entire gap but also that the insulation acts to mimic a larger gap, so if I filled the entire 10mm+50mm+22mm=82mm gap, maybe the insulation would make it act as 100mm gap and we know the large the gap the lower the resonant frequency. However I'm not sure if it's even possible to get 82mm thick insulation as I think it only comes in standard thicknesses of 25mm, 50mm, 75mm, etc.


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## Mpoes12

Insulating the gap helps absorb energy. When sound hits the wall the wall will reradiate the sound into the cavity. To reduce reflections and excess sound energy inside the cavity you add insulation. Think of it like stuffing a speaker box. If you over stuff it and the insulation is too dense you get an opposite effect. Don't overstuff but be sure it's relatively evenly filled. I think low density is better than high density insulation, but with limits. I wouldn't fill it with polyfill for example. Pink fluffy or standard mineral wool is probably best. 

My only concern with using OSB as he first layer for the entire room is that it does increase stiffness and that will reduce sound proofing. In addition, osb doesn't increase the weight capacity of the decouple wall. The clips and hat channel dictate the weight limit. All it does it allow you to hang stuff without having to find hat channel to screw into, since hat channel becomes like a stud now. Too much weight on the wall would still cause the wall to come loose from the hat channel clip assembly. When I did calculations for the ceiling I found that the normal spacing of clips and hat channel made it so 3 layers of drywall and green glue just about equals the limit. You couldn't then hang a projector. I took Ted's advice from the Soundproofing company and used one piece of plywood for the first layer where the projector will be and added an extra set of clips and hat channel just for that area. They gave me piece of mind. However I am sure the soundproofing has been partially compromised in that region. 


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## The Salmon Mousse

*clip & hat channel question*

I'm installing clip & hat channels on my ceiling (with DD + GG). Some of the ceiling joists are somewhat uneven. I was wondering how much tolerance there was for variations in level between joists. I've read elsewhere that anything below 1/8" was acceptable as the clip + hat channel helps to even out slight variations in height. Is this correct or should I make sure that the clips are all perfectly aligned?


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## Mpoes12

There is give to the hat channel but I'm not so sure it would make an even ceiling. It would bend with the variation in height. The drywall would also bend. They make adjustable clips to fix this. A lot of people use 2x4 pieces to mount clips to that slightly lower the ceiling and can even things out. I did something like this to get the hat channel below some electrical and a gas line. 


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## doveman

The Salmon Mousse said:


> I'm installing clip & hat channels on my ceiling (with DD + GG). Some of the ceiling joists are somewhat uneven. I was wondering how much tolerance there was for variations in level between joists. I've read elsewhere that anything below 1/8" was acceptable as the clip + hat channel helps to even out slight variations in height. Is this correct or should I make sure that the clips are all perfectly aligned?


I was looking at these spring clips for the ceiling which might be of interest but I don't know how much they cost yet.

http://www.kineticsnoise.com/arch/isolated_ceilings.html
http://www.mason-uk.co.uk/spring-hangers.asp


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## Mpoes12

I believe they are around $50 each. That is not something you want to use unless you have good reason. They are very expensive and overkill for most folks. 

It's important to remember that once you get past around 40 db of transmission loss you will begin to find lesser problems creeping in. Flanking for instance takes over. Those spring isolators are designed to provide significant isolation and deflection. To have those exceed the performance you would get with a regular clip you need to make sure you have handled all of the other sources of noise first. Otherwise you won't realize the benefit, they will perform identically to the $1.50 clips. 

This goes for lots of things in soundproofing. Don't waste money on things you don't need. This stuff is expensive enough as is. 

This is true of door seals, extra layers of drywall, fancier clips, etc. Basically once you have done basic clips, hat channel, DD/GG you are very close to the max soundproofing you can achieve in a residential setting without spending a lot more with time and planning. At that point the floor, outlets, hvac, caulking of seams, you name it will all matter more than any extra you could do. 


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## doveman

Mpoes12 said:


> Insulating the gap helps absorb energy. When sound hits the wall the wall will reradiate the sound into the cavity. To reduce reflections and excess sound energy inside the cavity you add insulation. Think of it like stuffing a speaker box. If you over stuff it and the insulation is too dense you get an opposite effect. Don't overstuff but be sure it's relatively evenly filled. I think low density is better than high density insulation, but with limits. I wouldn't fill it with polyfill for example. Pink fluffy or standard mineral wool is probably best.


OK, makes sense. With my stud wall with a total gap of 88.5mm (10mm between wall and stud, 50mm stud depth, 28.5mm for clip and hat channel http://www.soundproofingcompany.com/product/drywall-furring-channel-hat-channel/?page_id=3879), I think the best I could do is use 75mm insulation, as it only seems to come in multiples of 25mm (some products start at 25mm, others at 50mm).

In my living room, I have two external walls, one about 4m with a small window which I'm going to block up and the other about 3m which holds the main window. I'm thinking about what I can do with those to reduce sound transfer both to/from the upstairs/downstairs neighbours and from outside. I'm going to fit secondary glazing to the main window (as I will in the HT room eventually) but I'm also thinking about either stripping back the plaster or just adding something on top of the existing plaster. As it's an external wall I guess I don't have to worry about creating a triple-leaf as I won't be creating a gap on the other side and I could increase the depth by about 50mm without blocking the adjacent balcony door, so I could fit clips and hat channel and then a layer of 15mm OSB (total 43.5mm) and fit 25mm insulation in the space created by the clip and hat channel. If that isn't going to do much good I'd have to strip back the existing plaster (about 35mm) and build up from the concrete wall. 



> My only concern with using OSB as he first layer for the entire room is that it does increase stiffness and that will reduce sound proofing. In addition, osb doesn't increase the weight capacity of the decouple wall. The clips and hat channel dictate the weight limit. All it does it allow you to hang stuff without having to find hat channel to screw into, since hat channel becomes like a stud now. Too much weight on the wall would still cause the wall to come loose from the hat channel clip assembly. When I did calculations for the ceiling I found that the normal spacing of clips and hat channel made it so 3 layers of drywall and green glue just about equals the limit. You couldn't then hang a projector. I took Ted's advice from the Soundproofing company and used one piece of plywood for the first layer where the projector will be and added an extra set of clips and hat channel just for that area. They gave me piece of mind. However I am sure the soundproofing has been partially compromised in that region.


This is why I'm thinking I might need to use OSB on the window wall rather than plasterboard, as it has a radiator hanging off it and I'm not sure that plasterboard would support that. Also, the secondary glazing will probably sit on the sill, which is currently partially supported by the concrete wall and partially by the plaster, so I'm worried that if I replace the latter with plasterboard it might not be strong enough to support the secondary glazing and the radiator. I'm not sure that I could plaster over OSB though, nor whether it's fire resistant. In the 50mm space I have available without stripping the plaster, I might be able to fit 9mm OSB with 12.5mm plasterboard on top but I'm not sure if 9mm OSB would be strong enough.

I understand the optimum gap between the primary glazing and secondary glazing is 100mm-200mm and there's currently about 150mm between the existing double-glazed panes and the edge of the sill, so I'd probably end up with a gap of about 100mm. If I were to increase the depth of the wall, whether by adding layers on top of the plaster or stripping back the plaster first, then I guess I could screw a deeper piece of wood to the existing sill to allow the gap between the glazing to be deeper if that'd be worthwhile.

If there likely to be much difference between 4mm glass and 4mm polycarbonate in terms of soundproofing? For glass this option https://clearviewsg.co.uk/diy-secondary-glazing/ works out around £200. They have a guide which gives some noise reduction details about their products here https://yf241.infusionsoft.com/app/linkClick/3013/4af602285313e334/51772/2ede2fb3c0e818b1

For poly it's a lot cheaper using something like this http://www.diysecondaryglazingkit.co.uk/trackglaze-slider-kit.htm . I only need one pane to be slideable so that I can open the external window for fresh air, the other two thirds of the secondary glazing can be fixed.


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## doveman

Mpoes12 said:


> I believe they are around $50 each. That is not something you want to use unless you have good reason. They are very expensive and overkill for most folks.


Ah, yeah that is too expensive for me then! 



> It's important to remember that once you get past around 40 db of transmission loss you will begin to find lesser problems creeping in. Flanking for instance takes over. Those spring isolators are designed to provide significant isolation and deflection. To have those exceed the performance you would get with a regular clip you need to make sure you have handled all of the other sources of noise first. Otherwise you won't realize the benefit, they will perform identically to the $1.50 clips.


Probably overkill for me then, even if I could afford them, although hopefully I won't have any flanking problems as I'll treat the floor and walls first.


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## Mpoes12

Treating floors and walls is good. Just remember that it won't be perfect. Be prepared for it to have imperfections in the soundproofing. I'm very happy with how my project came out but it didn't meet expectations. I had this dilusion that all my planning and studying would net me super hero soundproofing. It didn't work that way. When I rock out at 100+db you can hear it outside the theater. It's significantly reduced but you can hear it. 


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## The Salmon Mousse

Mpoes12 said:


> This goes for lots of things in soundproofing. Don't waste money on things you don't need. This stuff is expensive enough as is.
> 
> This is true of door seals, extra layers of drywall, fancier clips, etc. Basically once you have done basic clips, hat channel, DD/GG you are very close to the max soundproofing you can achieve in a residential setting without spending a lot more with time and planning. At that point the floor, outlets, hvac, caulking of seams, you name it will all matter more than any extra you could do.


I've been wondering whether it might be useful to add an extra layer of drywall on interior walls in my home. Though because of the principle you mention, I'm worried this wouldn't accomplish much since the doors (plain solid wood) and floor aren't soundproofed.

Since I'm redoing the drywall in these rooms anyway, what's a reasonable amount of soundproofing to add before flanking and lack of soundproof doors renders the extra effort worthless? Would single 5/8 + pink stuff be the most I should consider adding? The goal is modest sound attenuation, not elimination.


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## Mpoes12

Oh certainly an extra layer of drywall will provide some soundproofing. Add a layer of green glue and it's even better. It won't be a huge improvement given the effort because the walls aren't decoupled.

How much soundproofing are you looking for? Modern homes let a lot of sound through. It's because the walls are much lighter and thinner than they used to be. Windows too. Todays windows are far less dense yet far better insulated than before. 

Think about what you want to accomplish and plan around that. An extra layer of drywall will achieve about 3-5 db of extra sound attenuation on average. Adding green glue probably adds a few points to that. To gain more like 20 points require all of that plus decoupling. Average walls have an STC of around 30db or so. Outside walls are a little higher, say 35-40. Adding an extra layer of 5/8 drywall and green glue will take you up to sat 35 for inside and 45 for exterior in the best scenario. That range is at the limit where flanking is significanrly detracting. After this point the flanking paths become bigger problems. 


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## doveman

Mpoes12 said:


> this is what the assembly looked like under construction.
> 
> The inner door is 1.75" solid flush slab. The outer is 1.75 solid core panl type. If my wife had allowed it I would have used all flush type. They are better.


Looks great, I'll have to consider doing something similar, although it's a bit awkward having an outward opening door in my case as it would open into the middle of the hall, rather than against a wall, so there's a risk of smacking someone in the face with it!

Did you isolate the frame from the wall at all? As my flooring is wooden I could put something like uboats on the joists under the base plate but I'm not sure if I could isolate the other three sides whilst maintaining the strength and rigidity needed to support the doors and with rubber isolation strip the frame would still need to be screwed through it into the wall.

On an unrelated point I've seen these ISOMAX clips but I'm not sure they offer any real benefits over cheaper clips. In terms of load-bearing it says they support 22kgs per clip whilst IB-1 supports 36lbs/16kg and IB-2 supports 55lbs/25kg, so unless they're significantly better in terms of soundproofing than IB-2 (or cheaper but I doubt that) there's probably not much point.
http://www.cms-av.com/product-appli...-clips/isomax-clip-complete-isolation-system/

IB clips don't appear to be available in the UK though so I'd have to import them from the Soundproofing Company, which might make the ISOMAX clips more economical.


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## HT Geek

doveman said:


> Well I know I have a concrete/cinder-block wall and that I'm planning to have a 10mm gap, stud wall, hat channel (creating a further 22mm gap) and drywall (with maybe one layer of OSB3) on the HT side. From what I've read, I understand that it's best not to completely fill the gap with insulation, so I could have insulation filling the 10mm gap, plus the 50mm depth of the studs, plus 10mm of the hat channel gap and leave 12mm unfilled, so that there's only a single 12mm gap or I could just fill the 50mm stud depth with insulation, which would leave one 10mm gap and one 22mm gap


Catching up on this thread. 

Regarding your comments above, I would suggest the 50mm depth stud insulation route.



> So my options for the living room side are rather limited. I have about 3.5cm space to stick something on top of the existing plaster, so I guess I could stick a layer of 15mm acoustic plasterboard on with green glue and if that's not sufficient, stick another layer on top. I'm a bit nervous about having heavy plasterboard only held up with glue though, I'd be constantly worrying about it falling down on top of me/my equipment!


Right. Please don't do that.  You need fasteners. You would need special fasteners designed to attach to concrete. Make sure the screw heads are an appropriate shape to counter-sink into the plaster without recessing any more than necessary, and will grab it and hold it in place. That plus glue should work well.




> Alternatively I could strip the existing plaster, seal the concrete wall with something very thin to avoid wasting space, then I'd have about 7cm to play with but as I have to avoid creating any gaps so can't use hat channel or insulation I'm not sure that the extra depth will be useful. I guess if I did that and stuck 15mm acoustic board to the concrete with green glue, then another layer on top I'd end up with the wall being the same, or slightly less, depth than it is now, so I wouldn't be losing any space in the room.


As I've mentioned above in this thread, one advantage to stripping the existing plaster is being able to seal the concrete. Provided you seal it in a manner that is proven to be beneficial in sound reduction and have a plan for adding mass and (ideally) decoupling, it's worth the effort. At the very least, if I were in your position I would strip the plaster, seal the concrete, and add mass to the wall if your primary concerns are LFE. If your primary concerns are higher pitch sounds, I'd suggest sealing the concrete and adding insulation as best you can with the space you have to work with.




> If sticking a single layer of 15mm plasterboard on the existing plaster with green glue would be sufficient to stop neighbour noise leaking out of the wall then obviously that's a lot less work than stripping of the existing plaster and on balance I'd probably prefer to accept the loss of space for the sake of being able to get the living room sorted and decorated so that I can move stuff out of the HT room and start working on that sooner.


And not discounting my comments above, I can certainly appreciate a desire to want to avoid the extra work of sealing the concrete, the flexibility to move your things around, get started on the HT room sooner, etc. It just depends on your priorities and what you can live with when all steps are completed.




> I think I'm going to have to replace the flooring in the living room as the floorboards are too bowed to lay cork tiles on top, so I'll probably take the opportunity to fit 25mm slabs of rockwoll between the joists and fit uboats before laying T&G OSB3, leaving a gap around the edge to ensure it's not touching the wall, then a layer of 6mm plywood on top to stick the cork tiles to. I'm a bit confused about the uboats though as I'll need to screw the OSB3 down but that would short-circuit the uboats. I saw someone who used square neoprene pucks, which had a central hole that he used to screw the pucks to the joists and then he used the outer holes to secure the subfloor to the pucks. He said the floor had a bit of bounce but was solid enough (and he had to go in at night and replace the screws as his contractors insisted on screwing the boards to the joists!). That doesn't look possible with uboats though, so how would I secure the OSB3 with those?


I believe most (if not all) u-boats are not designed to support the weight nor the direction of gravitational pull of walls. The idea is to float your floor, meaning it is not screwed into the floor joists at all. It simply lays on top of the u-boats. I can't imagine doing that with less than 2 layers of flooring, and one would screw the flooring layers to one another for added rigidity while keeping the floor floating. As you mentioned, maintaining a perimeter gap would be essential to keeping it floating as well.

Make sure you position the u-boats per the manufacturer's recommendations. Most follow a similar pattern to ISO clips and walls; e.g. placing a u-boat within 6-8" of a wall, then one every X feet/cm, etc.




> I'm not planning to build stud walls in the living room so the floor won't be supporting the weight of the walls or ceiling but when I do the HT room it will be, which makes it even more critical that the floor is solid. Perhaps this is why some places say to screw the stud wall footboards directly to the joists rather than the subfloor?


Do you mean your existing sub-floor? You should have no issues. Most of the time, you can't tell where the floor joists beneath it are unless you look at the nail positions from when the sub-floor was installed. Even doing that requires you one to presume the sub-floor installer knew what they were doing. Regardless, it seems like an unnecessary level of detail to me as securing your footer board across the entire floor should secure it just fine as long as your walls are plumb. The ceiling and wall layers also help to keep the structure rigid.

I would think securing the floor directly to the floor joists beneath the sub-floor would also increase the propensity for sound flanking via those joists.


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## HT Geek

doveman said:


> On an unrelated point I've seen these ISOMAX clips but I'm not sure they offer any real benefits over cheaper clips. In terms of load-bearing it says they support 22kgs per clip whilst IB-1 supports 36lbs/16kg and IB-2 supports 55lbs/25kg, so unless they're significantly better in terms of soundproofing than IB-2 (or cheaper but I doubt that) there's probably not much point.
> http://www.cms-av.com/product-appli...-clips/isomax-clip-complete-isolation-system/
> 
> IB clips don't appear to be available in the UK though so I'd have to import them from the Soundproofing Company, which might make the ISOMAX clips more economical.


Unless you have a need for a specific product, there's not a huge difference in performance between most clips. You *can* spend your way into better performance, but I find it's most often going down a rabbit hole per se. Once you opt for the best of something, you need to repeat that process with everything else. Otherwise you just short-circuit your efforts by creating a weaker link.

My point is, if you look at your overall goals - and presuming cost is a factor - utilizing comparable level effort across the realms of damping, decoupling, etc. is the most logical route. So, back to the clips for example, here in the U.S. you could spend $2 for clips or $7 or more. You'll need just as many of each, but the expensive route is 3.5x the cost of the cheapo route. For $3.50 or so you can find good quality clips that will give you 90% performance of $7 clips. OTOH, doubling up on $2 clips will not increase performance.

The better designs have rubber, neoprene, or similar materials in addition to the metal clip portion. The cheaper designs use metal only.


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## Mpoes12

HT Geek said:


> Unless you have a need for a specific product, there's not a huge difference in performance between most clips. You *can* spend your way into better performance, but I find it's most often going down a rabbit hole per se. Once you opt for the best of something, you need to repeat that process with everything else. Otherwise you just short-circuit your efforts by creating a weaker link.
> 
> My point is, if you look at your overall goals - and presuming cost is a factor - utilizing comparable level effort across the realms of damping, decoupling, etc. is the most logical route. So, back to the clips for example, here in the U.S. you could spend $2 for clips or $7 or more. You'll need just as many of each, but the expensive route is 3.5x the cost of the cheapo route. For $3.50 or so you can find good quality clips that will give you 90% performance of $7 clips. OTOH, doubling up on $2 clips will not increase performance.
> 
> The better designs have rubber, neoprene, or similar materials in addition to the metal clip portion. The cheaper designs use metal only.


When I looked into the different clips I found that the difference between the metal only and the elastomer isolated clips was just 1-2 STC points. I know there are some tests comparing a large range of clips. I didn't find that difference worth the price. If I had a bigger budget I could see looking into them to get every STC point I could however. 

I went through nearly 200 clips in my theater. We are talking a difference of say $400 vs $1200 for the cheapest clips vs the better rated Green Glue clips. For me that was a lot of money for a few STC points.


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## Mpoes12

doveman said:


> Looks great, I'll have to consider doing something similar, although it's a bit awkward having an outward opening door in my case as it would open into the middle of the hall, rather than against a wall, so there's a risk of smacking someone in the face with it!
> 
> Did you isolate the frame from the wall at all? As my flooring is wooden I could put something like uboats on the joists under the base plate but I'm not sure if I could isolate the other three sides whilst maintaining the strength and rigidity needed to support the doors and with rubber isolation strip the frame would still need to be screwed through it into the wall.


I'm not totally sure what you mean, but no I didn't isolate. The sill plate's of that wall sit on a sheet of cork/rubber. I thought about putting this same around the door frame before assembling it but it wasn't easily done.

One thing I didn't do that I might have done in a perfect world is to split the door stop between the two sides of the room. Technically I have created a solid soundbridge between the source side and other rooms. However, my feeling was that the split was hard to achieve and it isn't a true bridge. The door receives the sound which then would have to transfer through the jambs via a rubber gasket. That should be providing some decoupling. The Door frame itself is heavily damped and decoupled, but it was circumstance rather than choice and I don't know if I would call it decoupled. The frame had a roughly 1" gap around it. I used layers of green glue laminated drywall to fill the gap. The entire thing was coated with a heavy layer of acoustic caulk. The trim was secured in place using acoustic caulk as well. 

I am finding that the door assembly is the weak link in my own theater setup. Pemko had told me that my door setup wouldn't require their better gasket systems and suggested I use their stick on gaskets instead. They recommended a threshold instead of an automatic door bottom. What I am finding is that imperfections in my door jamb assembly and unevenness in the stops has made it so that the gaskets aren't perfect. As such I plan to add an automatic door bottom to the door, even though I was told it wasn't needed, as I feel more confident in the level of the seal I will get. I also plan to add a 2"-4" thick acoustic panel to the inner door as a means to absorb energy inside the communicating door area when closed. This all should add only a handful of db's more energy loss, but it's likely worthwhile. 

In Europe it seems that acoustic door parts are cheaper than here. I have found a handful of companies that make really nice door hardware for soundproofing that appeared quite a bit cheaper than here in the U.S. If it wasn't for shipping problems, I would have loved to order them for myself.


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## Mpoes12

https://firesealshop.com/collections/acoustic-door-bottom-seals/products/nor810db?variant=707384719 Here is the drop seals I found. Maybe you can shed some light on this. Am I missing something or is this price just too cheap? An equivalent door seal to that here would cost between $50 and $100. Most sources are more in the $100 range, but I've found a few specialty suppliers that gave a good discount. That appears to be around $22. How could that be?


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## Gouie

In my search for seals I found a huge range in price for the drop seal depending on where you looked. Those places specializing in soundproofing often charged twice as much as your commercial resellers. I landed mine for $50 CDN each, comparable to $150 at specialty locations. The side and top adjustable seals on the other hand are outrageously priced. I went the stratified route for them.


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## Livin

Gouie said:


> In my search for seals I found a huge range in price for the drop seal depending on where you looked. Those places specializing in soundproofing often charged twice as much as your commercial resellers. I landed mine for $50 CDN each, comparable to $150 at specialty locations. The side and top adjustable seals on the other hand are outrageously priced. I went the stratified route for them.


What do you mean by stratified? Can you post a pic? Thx

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## Gouie

Damn auto correct. That should read commercial.


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## Mpoes12

What is a commercial seal then? I went through Americab Builders Outlet. The top pemko drop seal was $57 but the perimeter seals, while a good price, added up quick. I went with stick on seals for now and may uograde later. I'm seeing a 40-50db drop as is, so I'm happy enough. 


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## doveman

Mpoes12 said:


> I'm not totally sure what you mean, but no I didn't isolate. The sill plate's of that wall sit on a sheet of cork/rubber. I thought about putting this same around the door frame before assembling it but it wasn't easily done.


Sorry, I should have said decouple rather than isolate, as you obviously can't completely isolate the door frame from the wall.



> One thing I didn't do that I might have done in a perfect world is to split the door stop between the two sides of the room. Technically I have created a solid soundbridge between the source side and other rooms. However, my feeling was that the split was hard to achieve and it isn't a true bridge. The door receives the sound which then would have to transfer through the jambs via a rubber gasket. That should be providing some decoupling. The Door frame itself is heavily damped and decoupled, but it was circumstance rather than choice and I don't know if I would call it decoupled. The frame had a roughly 1" gap around it. I used layers of green glue laminated drywall to fill the gap. The entire thing was coated with a heavy layer of acoustic caulk. The trim was secured in place using acoustic caulk as well.
> 
> I am finding that the door assembly is the weak link in my own theater setup. Pemko had told me that my door setup wouldn't require their better gasket systems and suggested I use their stick on gaskets instead. They recommended a threshold instead of an automatic door bottom. What I am finding is that imperfections in my door jamb assembly and unevenness in the stops has made it so that the gaskets aren't perfect. As such I plan to add an automatic door bottom to the door, even though I was told it wasn't needed, as I feel more confident in the level of the seal I will get. I also plan to add a 2"-4" thick acoustic panel to the inner door as a means to absorb energy inside the communicating door area when closed. This all should add only a handful of db's more energy loss, but it's likely worthwhile.


You've clearly done a thorough job there, which I'll refer back to when I get round to my doors. Are you able to add acoustic panel to the room side of the inner door as well, or will the wall prevent you opening it fully if you do that? I'm just thinking that if you can prevent the energy even getting into the door it might be worthwhile, with acoustic panel on the other side as well perhaps to absorb any energy that makes it through.



> In Europe it seems that acoustic door parts are cheaper than here. I have found a handful of companies that make really nice door hardware for soundproofing that appeared quite a bit cheaper than here in the U.S. If it wasn't for shipping problems, I would have loved to order them for myself.


Well there's some benefits to living over here then  I was looking at the bottom seals you linked to https://firesealshop.com/collections/acoustic-door-bottom-seals/products/nor810db?variant=707384699 and thought I might pick up a couple whilst they're on sale but unfortunately my approx. 76cm doors would need the 835mm seals to cut down and they're not selling the 810db in that length. I could get the standard 810 for £15.63 minus a further 20% as they're on sale, or the 810S for £15.50 (not on sale) but it's hard to know what the relative pros and cons are for each product (the S is just a smaller version of the 810 but I wonder whether this comes with any downsides). Alternatively I could just get the retrofit 820 for £20.66, which won't be as discrete but I could easily fit that myself, so it would save the expense of paying someone.


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## doveman

Mpoes12 said:


> When I looked into the different clips I found that the difference between the metal only and the elastomer isolated clips was just 1-2 STC points. I know there are some tests comparing a large range of clips. I didn't find that difference worth the price. If I had a bigger budget I could see looking into them to get every STC point I could however.
> 
> I went through nearly 200 clips in my theater. We are talking a difference of say $400 vs $1200 for the cheapest clips vs the better rated Green Glue clips. For me that was a lot of money for a few STC points.


Yeah, big difference in cost for not so great improvement in STC. I guess it's easy to forget that whilst there might only be a few bucks difference between clips, this soon adds up when you need several hundred of them. I'll probably stick with the IB-1 then but I'll see what the cost including shipping will be for those and the IB-2.


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## doveman

Before I reply to your post I need to discuss a rather disappointing discovery that I made today. 

I took up one of the floorboards in the living room, partly because I want to relocate one of the power sockets but also to investigate the construction further. What is disappointing is that the cinderblock seems to vary in depth, so whereas on the corner of the wall which I previously exposed there's approx 35mm of plaster on top of the cinderblock, next to the floorboard it varies from 2cm down to only 1cm at places. This means that I can't have any certainty that stripping back the plaster will give me any more than 1cm extra depth to play with, so I'm questioning whether it will be worth the effort. If the situation is the same on the HT side of the wall (which I imagine it will be) then I'm not going to have enough space to build a decoupled stud wall even if I strip the plaster back, so I might have to leave it on and settle for clips attached to the plaster (but screwed through into the concrete for strength) with hat channel and two layers of acoustic plasterboard (or one OSB layer and one plasterboard) and 25mm insulation between the existing wall and the 1st layer of plasterboard.

This shows three joists where I lifted the board. Around where the white conduit for the power cables is (I'm not sure why there's two conduits as there's only one socket above them, which rather strangely then has cable extending further up the wall from it to god knows where. Maybe the second conduit is feeding the socket on the other side of the wall) there's about 20mm between the plaster and the cinderblock but at the middle joist, there's only about 1cm. I don't really understand how a cinderblock wall can vary in depth but it certainly appears to.


 


As unbelievable as it seem, it appears that only the middle joist is actually fused to the wall, as I can slide a card behind the other two, so I'm not really sure what's holding them up! The orange insulation is quite thin and appears to be wedged under the joists but it can't be supporting them.




I also took these photos to show the central heating pipes that I've been thinking about relocating to under the floor. 



 

On the living room side of the wall, I could probably just make some skirting pipe boxing like this http://www.carpentry-tips-and-tricks.com/Pipe-Boxing.html# out of plasterboard and fill it with insulation, which would hide it and stop the pipes picking up noise and transferring it to the HT room (although I guess the radiator itself will pick up noise and transfer it into the pipes) and maybe dig out the hole in the wall a bit so that I can wrap lagging around the pipes where they go through it. I couldn't box in the pipes on the HT side if I was going to build a stud frame, as the pipes would be in the way of the floor plate and vertical studs, hence why I thought I'd move all the piping under the floor. Now that it looks like I might not have room for a stud frame however, I'm questioning whether it's worth the hassle and expense of doing that or if I should just box in the piping on the HT side as well and then cover the wall above the boxing with clips, hat, insulation and plasterboard.



HT Geek said:


> Right. Please don't do that.  You need fasteners. You would need special fasteners designed to attach to concrete. Make sure the screw heads are an appropriate shape to counter-sink into the plaster without recessing any more than necessary, and will grab it and hold it in place. That plus glue should work well.


That's what I thought and the only reason I questioned whether glue alone would be sufficient is because the fitting instructions for the SM20 panels http://www.soundstop.co.uk/solutions/wall_solutions/wall_solution_4.php here http://www.soundstop.co.uk/resources/instructions/wall solutions/SS20 panel fitting.pdf say to glue the panels to the wall and then glue the plasterboard to the panels, although it does say "Occasionally, for various reasons, problems may be encountered bonding the product to the wall. When this occurs, mechanical fixings can be used in addition to the adhesive".



> As I've mentioned above in this thread, one advantage to stripping the existing plaster is being able to seal the concrete. Provided you seal it in a manner that is proven to be beneficial in sound reduction and have a plan for adding mass and (ideally) decoupling, it's worth the effort. At the very least, if I were in your position I would strip the plaster, seal the concrete, and add mass to the wall if your primary concerns are LFE. If your primary concerns are higher pitch sounds, I'd suggest sealing the concrete and adding insulation as best you can with the space you have to work with.


I thought we'd agreed that the existing plaster is already sealing the concrete, so that it would be pointless to strip the plaster off just to re-seal it? On the living room side it's more speech/shouting rather than LFE that I want to address, so insulation would be what I need but assuming I won't get enough extra space to make stripping the plaster worthwhile and I only have 35mm to play with, I'm not sure what I can do. The only thing I can think of is to screw hat channel (22mm) directly to the wall and one layer of 12mm plasterboard to the hat channel and stuff insulation in the gap (or glue the insulation to the wall first) but then I'll create a triple-leaf as I'll have a gap on the HT side as well (about 28.5mm if I use clips and hat channel). As insulation acts as a (larger) airgap, I don't see how I can use it on the living room side if I'm to avoid creating a triple-leaf. In any case Rockwool starts at 25mm so that won't fit. Does pink fluffy come in thinner sizes?



> I believe most (if not all) u-boats are not designed to support the weight nor the direction of gravitational pull of walls. The idea is to float your floor, meaning it is not screwed into the floor joists at all. It simply lays on top of the u-boats. I can't imagine doing that with less than 2 layers of flooring, and one would screw the flooring layers to one another for added rigidity while keeping the floor floating. As you mentioned, maintaining a perimeter gap would be essential to keeping it floating as well.
> 
> Make sure you position the u-boats per the manufacturer's recommendations. Most follow a similar pattern to ISO clips and walls; e.g. placing a u-boat within 6-8" of a wall, then one every X feet/cm, etc.


Even though they sell them, they don't seem to think much of uboats here http://isostore.com/shop/product/isojoist-joist-isolators-and-stud-isolators/ so I'm questioning whether that's the best option for me, even in the living room where the floor won't be supporting the walls. Firstly they say that the rubber used is too stiff, resulting in minimal isolation in the low to mid frequency range. They also warn about resonance issues with floating floors, from the air cavity created over an existing sub-floor. Maybe that doesn't apply to me where I'm not building on top of the existing subfloor but there will still be an air cavity between the new OSB subfloor and the concrete slab under the joists and the cavity will be somewhat deeper than it is now when the uboats are added. They say this can be minimised by fitting insulation between the joists and fitting at least two 1/2" layers of plywood or similar mass over the isolated subfloor but it's a question of whether that's practical for my living room or if I'm just creating extra work by using the uboats.

Certainly I can pull up the floorboards, remove the current orange thin insulation and fit 25mm Rockwool or pink fluffy (the joists are about 35mm tall), put uboats on the joists, lay OSB on top but not screw it down, lay 6-9mm ply and stick my cork tiles to that. I can't fit two layers of 13mm plywood though, as it will just make the floor too high relative to the other rooms. I guess I shouldn't glue or screw the plywood to the OSB, as that would make it very hard to remove the plywood in future if I wanted to replace the cork tiles with something else but hopefully the weight of the plywood and tiles combined will stop it lifting accidentally.

They suggest a better alternative would be Geniemat RST http://isostore.com/shop/product/geniemat-rst-rubber-underlayment/ although it says there that it doesn't perform as well over wooden floors as on concrete. They say layering approximately 7 pounds per sq. ft of material over the sub-floor will fix this and adding Green Glue between layers for extra damping will be even better but even with two layers of 6mm ply, which only weighs about about 1.5 pounds per sq. ft, I'd still be adding 6mm ply+(green glue)+6mm ply+10mm GenieMat+6mm ply+4mm cork tiles which at 30mm is far too much. The other alternative, which they say is better, is to fix the structural deflection between the joists by adding blocking between them http://isostore.com/solution/fix-structural-deflection/ which is more realistic for me. They say "Install blocking at the mid-point for spans greater than 10′" so I guess with my room which is just under 10' wide I'd only need to do that. I'd still need 10mm GenieMat+6mm ply+4mm cork tiles on top of the subfloor but maybe I could replace the 18mm floorboards with 12mm OSB to minimise the increase. The adjacent kitchen and hall have, or will have, approx. 15mm of ply and vinyl above the subfloor anyway, so with 12mm OSB and GenieMat, etc. the living room floor would actually be 1mm lower, or with 18mm OSB it would be 5mm higher.



> Do you mean your existing sub-floor? You should have no issues. Most of the time, you can't tell where the floor joists beneath it are unless you look at the nail positions from when the sub-floor was installed. Even doing that requires you one to presume the sub-floor installer knew what they were doing. Regardless, it seems like an unnecessary level of detail to me as securing your footer board across the entire floor should secure it just fine as long as your walls are plumb. The ceiling and wall layers also help to keep the structure rigid.
> 
> I would think securing the floor directly to the floor joists beneath the sub-floor would also increase the propensity for sound flanking via those joists.


No, I meant securing the footer board to the joists rather than the new sub-floor, especially if it's floating on uboats and thus unsecured. I can tell from the nail positions where the joists are but often the nails aren't in the middle of the joist, so when I need to be sure, like if I'm cutting a board and want to leave sufficient each side resting on the joist, I cut through the T&G either side and slide a ruler in the gap to hit it against the joist and mark the edges.

I'm sure you're right that securing the stud frame footer to the joists increases the risk of flanking but I guess it depends on what the joists are attached to, as if they're attached to the walls and there's noise in those walls then it might be a problem (although the joists themselves would probably dampen some of the noise and then the clips and hat channel between the stud frame and plasterboard would further dampen it) but if the joists are attached to the concrete slab underneath and noise isn't really travelling through the concrete then it might not matter.

I found a couple of other pages which looked interesting. This guy has created a pair of cleats from 2x4 which seems to have the advantage of being able to screw into it to hang heavy stuff from. I'd be interested to know what you think. http://www.instructables.com/id/Soundproof-Your-Garage-Walls-Using-My-Cleat-Meth/

The other one is about MLV and suggests that it only works well if hung loosely https://acousticalsolutions.com/mas...op-worrying-and-install-things-the-right-way/ This makes me suspect that products like MuteBoard http://www.ikoustic.co.uk/category/wall_soundproofing , which have one or more layers of MLV laminated to plasterboard and acoustic foam, are unlikely to work very well. I'm not sure about MuteBoard 2 which uses TecSound SY-70, as I don't think that's a MLV, so that might work better but it's still expensive for what it is and I don't trust any site that claims it's products will provide a 40db airborne reduction!


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## HT Geek

Mpoes12 said:


> https://firesealshop.com/collections/acoustic-door-bottom-seals/products/nor810db?variant=707384719 Here is the drop seals I found. Maybe you can shed some light on this. Am I missing something or is this price just too cheap?


Wow. Shipping would probably be a killer for me, but there's even a 20% coupon code on the page atm! Currently $23 converted to USD - 20% = $18.40. That is insanely cheap compared to any other automatic door stop I've seen for sale.


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## HT Geek

doveman said:


> Now that it looks like I might not have room for a stud frame however, I'm questioning whether it's worth the hassle and expense of doing that or if I should just box in the piping on the HT side as well and then cover the wall above the boxing with clips, hat, insulation and plasterboard.


I'd suggest boxing in the pipes. If you ever need to access them for any reason and they are buried under the floor, it would be a lot more work and tear-down to get access to them. I know the downside is a potential eyesore in the room, but as you said there are other headwinds as well. All together, I tend to agree that just dealing with those pipes is becoming a major issue if you still insist on burying them in the floor. Definitely worth considering alternative options and how they would impact the room overall.




> I thought we'd agreed that the existing plaster is already sealing the concrete, so that it would be pointless to strip the plaster off just to re-seal it? On the living room side it's more speech/shouting rather than LFE that I want to address, so insulation would be what I need


Could be. This discussion has been going on for so long that I don't recall and don't have time at this moment to scan all the previous messages. I'd go with whatever comments were expressed at the time (i.e. when I was focused on all the variables of your room with regards to your concrete, and the studies that show the data on sealing concrete). 




> Does pink fluffy come in thinner sizes?


Not that I'm aware of, but it is easily torn/divided. It's much easier to tear apart pink fluffy to stuff where/as you need it vs. rockwool or other products.





> Even though they sell them, they don't seem to think much of uboats here http://isostore.com/shop/product/isojoist-joist-isolators-and-stud-isolators/ so I'm questioning whether that's the best option for me, even in the living room where the floor won't be supporting the walls. Firstly they say that the rubber used is too stiff, resulting in minimal isolation in the low to mid frequency range. They also warn about resonance issues with floating floors, from the air cavity created over an existing sub-floor. Maybe that doesn't apply to me where I'm not building on top of the existing subfloor but there will still be an air cavity between the new OSB subfloor and the concrete slab under the joists and the cavity will be somewhat deeper than it is now when the uboats are added. They say this can be minimised by fitting insulation between the joists and fitting at least two 1/2" layers of plywood or similar mass over the isolated subfloor but it's a question of whether that's practical for my living room or if I'm just creating extra work by using the uboats.


It all depends on the circumstances, though naturally they are not ideal. In an ideal world you'd use clips and channel to raise your floor, if someone made clips designed for that purpose. I've never seen/heard of any that are, and even if they exist they'd have to be incredibly expensive to get an effective arrangement. The advantage of the uboats is to decrease the surface area in contact with the floor joists. It's going to be a minimal improvement, but it will be an improvement versus doing nothing to the floor. You could consider adding more floor layers/mass as an alternative.




> They suggest a better alternative would be Geniemat RST http://isostore.com/shop/product/geniemat-rst-rubber-underlayment/ although it says there that it doesn't perform as well over wooden floors as on concrete. They say layering approximately 7 pounds per sq. ft of material over the sub-floor will fix this and adding Green Glue between layers for extra damping will be even better....


Yes, I would agree. Geniemat is a useful product when it's possible to utilize it and it meets one's needs. Likely better than uboats. More costly.




> The other alternative, which they say is better, is to fix the structural deflection between the joists by adding blocking between them http://isostore.com/solution/fix-structural-deflection/ which is more realistic for me.


That refers to deflection of the ceiling, not the floor. 




> No, I meant securing the footer board to the joists rather than the new sub-floor, especially if it's floating on uboats and thus unsecured. I can tell from the nail positions where the joists are but often the nails aren't in the middle of the joist, so when I need to be sure, like if I'm cutting a board and want to leave sufficient each side resting on the joist, I cut through the T&G either side and slide a ruler in the gap to hit it against the joist and mark the edges.





> I'm sure you're right that securing the stud frame footer to the joists increases the risk of flanking but I guess it depends on what the joists are attached to, as if they're attached to the walls and there's noise in those walls then it might be a problem (although the joists themselves would probably dampen some of the noise and then the clips and hat channel between the stud frame and plasterboard would further dampen it) but if the joists are attached to the concrete slab underneath and noise isn't really travelling through the concrete then it might not matter.


It's a value proposition. It's not ideal, but you have to weigh practical solutions vs. ideal solutions. In many cases, they won't be the same. If you're (practically speaking) concerned about the integrity of your structure and believe screwing the footers directly into the underlying floor joists will solve or mitigate that issue, then if that outweighs the value to you of the benefits from the ideal method (don't do it) then it may make sense in your situation. As you mentioned above, not knowing how all the structural members are connected to one another means there's no way to ascertain the real trade-offs with respect to flanking. However, we can speculate that most likely attaching your footers directly to the underlying floor joists will contribute slightly to flanking versus not doing it. 

FWIW, I'd be more concerned about simply creating the double stud wall and overall safety. If that meant attaching the footers directly into the floor joists for improved structural integrity, I'd choose that route and sacrifice some extra flanking potential.





> I found a couple of other pages which looked interesting. This guy has created a pair of cleats from 2x4 which seems to have the advantage of being able to screw into it to hang heavy stuff from. I'd be interested to know what you think. http://www.instructables.com/id/Soundproof-Your-Garage-Walls-Using-My-Cleat-Meth/


It's an alternative form of decoupling. There are products on the market (usually referred to as 'joist tape' or something similar) that are effectively the same concept, with the exception this person is using pieces of foam staggered across the wood, and he's using the wood as resilient channel. It's an interesting idea, but I don't see any audio testing and even if I did, if it's not in the same lab as other tests then it's not comparable.




> The other one is about MLV and suggests that it only works well if hung loosely


That is my understanding as well. From what I've observed, it isn't a good option in most dedicated room builds.


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## Mpoes12

I'd be concerned with execution for that instructables page. Wood isn't as resilient as metal. Metal studs also provide better Soubd isolation than wood studs. Using wood hung in cleats wont allow the wall to flex the way hat channel does. The weight could also exceed the weight capacity of that foam to remain effective as a damper. At some point you reach full deflection and no longer see benefit. I would think the weight of the drywall would be able to do that, essentially bottom out the foam. For whatever money might be saved, I think you would risk a lot of work with less benefit. 

I would look for alternative suppliers for ib1 clips. SPC doesn't manufacture them. I found their likely supplier once but can't seem to recall anymore. I would think/hope the manufacturer has dealers in England or parts of mainland Europe to order from. 


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## Mpoes12

HT Geek said:


> Wow. Shipping would probably be a killer for me, but there's even a 20% coupon code on the page atm! Currently $23 converted to USD - 20% = $18.40. That is insanely cheap compared to any other automatic door stop I've seen for sale.




It's so cheap I feel like there is a mistake or something. Maybe I should call the company and ask about a US dealer arrangement for importing them. I think they would be very popular if I could sell a product like that at those prices. They would be a deal at twice those prices. 


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## doveman

Mpoes12 said:


> It's so cheap I feel like there is a mistake or something. Maybe I should call the company and ask about a US dealer arrangement for importing them. I think they would be very popular if I could sell a product like that at those prices. They would be a deal at twice those prices.


Please don't tell them that before I've bought mine


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## doveman

HT Geek said:


> I'd suggest boxing in the pipes. If you ever need to access them for any reason and they are buried under the floor, it would be a lot more work and tear-down to get access to them. I know the downside is a potential eyesore in the room, but as you said there are other headwinds as well. All together, I tend to agree that just dealing with those pipes is becoming a major issue if you still insist on burying them in the floor. Definitely worth considering alternative options and how they would impact the room overall.


It's not really about how the pipes look, the main reason for burying them was that it would be impossible to build a stud frame in the HT room with them in the way. I guess I could move them inwards so that they sit outside the plasterboard (i.e. inside the inner room and visible) but that might be impractical as the HT inner room will be quite small enough and with the pipes intruding into the room as well it might make it impossible to get around furniture. Anyway, if there's not as much plaster that I can strip back as I originally thought, the stud frame approach isn't going to practical anyway. I'll have to get a contractor in to determine exactly how much plaster there is so that I can decide how to proceed.

Another potential problem with burying the pipes is that I'd have to cut notches in the top of the joists to let them sit below the subfloor and that creates the risk that someone might accidentally cut through them when cutting through the floor in future. I think normally the pipes would lie in notches at the bottom of the joists (as my electric cables do) to avoid this risk but I don't think this is practical when retrofitting them.

For the living room, the attached (very) rough sketch shows a) the window wall with the radiator on as it currently is, b) how I could add plywood and plasterboard, move the radiator but leave the pipes where they are (obviously I'll have to add a couple of lengths to connect them to the relocated radiator) and box them in and c) the wall with added clip+channel+one layer of plasterboard (+insulation which I haven't drawn), with the radiator and the pipes relocated and no pipe boxing. I'm not sure that the plasterboard alone could support the radiator in c) though.

Without stripping off the existing plaster I can increase the depth of the wall by about 50mm without blocking the balcony door, so two extra layers of 15mm as in b) would fit (or two layers of 12.5mm on 22mm hat channel screwed directly to the wall but not clips), or clips and channel (28.5mm) and one extra layer of 12.5mm/15mm as in c). The radiator isn't near the balcony door so moving that inwards doesn't matter. If I am able to strip back 20mm of plaster, then I'll be able to fit clips and channel and _two_ layers of 12.5mm/15mm whilst only reducing the room by 33.5/38.5mm and that's probably the best option, as it decouples and provides a layer of plywood to support the radiator. Having to strip the plaster off obviously makes it the most intensive/expensive option but as much of that wall is window, it's the easiest wall to strip and on the other walls where I don't need to support anything I might be able to just have one layer of plasterboard as in c).



> Could be. This discussion has been going on for so long that I don't recall and don't have time at this moment to scan all the previous messages. I'd go with whatever comments were expressed at the time (i.e. when I was focused on all the variables of your room with regards to your concrete, and the studies that show the data on sealing concrete).


I can't be sure what was said either but it seems logical that a layer of plaster over the wall will seal it, assuming there aren't any holes or blown plaster. If I was building from scratch I wouldn't choose to use plaster to seal a wall as there's alternatives that are much thinner, thus leaving more space for other treatments that are a more efficient use of that space and if I do strip off the existing plaster I'll use one of those alternatives to re-seal it.



> Not that I'm aware of, but it is easily torn/divided. It's much easier to tear apart pink fluffy to stuff where/as you need it vs. rockwool or other products.


That sounds like my best option for insulating the walls then, if I have to use hat channel secured directly to the wall and only have 22mm to fill. If I can use clips and hat channel, I'll have 28.5mm and can just use 25mm insulation and likewise if I decide to (re)insulate the 35mm gap between the floor joists.



> It all depends on the circumstances, though naturally they are not ideal. In an ideal world you'd use clips and channel to raise your floor, if someone made clips designed for that purpose. I've never seen/heard of any that are, and even if they exist they'd have to be incredibly expensive to get an effective arrangement. The advantage of the uboats is to decrease the surface area in contact with the floor joists. It's going to be a minimal improvement, but it will be an improvement versus doing nothing to the floor. You could consider adding more floor layers/mass as an alternative.





> Geniemat is a useful product when it's possible to utilize it and it meets one's needs. Likely better than uboats. More costly.


I should clarify what my motivations are for treating the floor in the living room:

1) Because I want to lay cork tiles and I need a very flat floor for that and the current floorboards are not flat at all, with some bowed up or down in the middle. I don't think even 9mm plywood on top would even it out as that will just bend to match the floorboards, so I thought I should just take up the floorboards and replace them with 18mm OSB. 

2) The floorboards are quite squeaky in places and I figured OSB, tightly screwed down with these special screws http://www.screwfix.com/p/spax-flooring-screws-4-5-x-60mm-pack-of-300/88716, would eliminate that, especially if I use square edge OSB rather than T&G, which will also be easier to lay and lift in future without having to damage it. I'd be concerned that unscrewed boards laid on uboats would be liable to squeak as much, if not more, than the current floorboards. The flat upstairs from me has squeaky floorboards in places and they're so loud they sound like they're in my flat, even though I never, or rarely, seem to hear the occupants speaking or their TV, so I'm aware of how annoying squeaky floorboards can be to the people underneath.

3) I want to make sure that airborne noise isn't circumventing whatever treatment I fit to the walls and transmitting to/from the neighbours via the floor. This is tricky to evaluate at the moment when I'm not sure exactly how much treatment the walls need to achieve a satisfactory result, nor whether there's actually any sound travelling via the floor. It's probably likely however that some audible noise is currently either exiting from the concrete wall into the void (which I could perhaps address by fitting a few inches of insulation around the perimeter under the subfloor) or travelling out of the concrete wall along the joists which are attached to it and then up through the floorboards (I'm not sure whether speech/TV frequencies rather than LFE are likely to travel through wood in this manner though). It's probably unlikely that any noise is travelling up from downstairs through the concrete ceiling into the void beneath my subfloor but maybe I need to find a way to treat the walls first and then see if I can still hear anything through the floor.

4) I want to minimise the impact noise so that I can exercise without annoying the neighbours. This is not that important though, if it's too difficult to achieve I'll just have to avoid jumping around too much.

Burying the pipes is really a separate consideration, as if I decide to do that I'll only need to remove a few pieces of the subfloor around the perimeter.

The floor height increase I can get away with is largely dictated by the hallway, as I could only increase that by a max. of 20mm without blocking the front door and I need to avoid large differences in levels between the rooms.

If there's a way to address at least 1, 2 and 3 without going to the trouble of lifting the floorboards and replacing them with OSB then that's likely to be preferable, even if it costs a bit more, as it will save a lot of time and hassle. Perhaps 5mm GenieMat or similar would even out the deviations in the floorboards so that I could lay 9mm ply and 4.7mm cork tiles on top, for a total height increase of 18.7mm. I looked at these SBx boards http://www.soundstop.co.uk/ZDBBOARD.php but even if those plus cork tiles stuck directly on top would do the trick, they cost too much. I could buy 6.0mm cork tiles instead of 4.7mm ones for an extra £3 per m2 if that would make a significant difference but then I might have to reduce the ply from 9mm down to 6mm/5.5mm. If you have any other ideas I'd be glad to hear them.



> That refers to deflection of the ceiling, not the floor.


Ah OK, I guess that's irrelevant to me then as the ceiling below my room is concrete.



> It's an alternative form of decoupling. There are products on the market (usually referred to as 'joist tape' or something similar) that are effectively the same concept, with the exception this person is using pieces of foam staggered across the wood, and he's using the wood as resilient channel. It's an interesting idea, but I don't see any audio testing and even if I did, if it's not in the same lab as other tests then it's not comparable.


I was mostly interested as it appeared as if it might offer a way to support hanging much more weight than resilient channel/clips and hat channel could but I appreciate there's no test data available to allow you to compare it's soundproofing potential.



> That is my understanding as well. From what I've observed, it isn't a good option in most dedicated room builds.


OK, I won't rely on any MLV or products containing layers of it for my living room then. The demonstration video they've got at http://www.ikoustic.co.uk/product/mute_board_3 looks impressive but I guess we can't tell what frequency the noise that is being blocked is, so it might only be effective at blocking high frequencies, whilst still letting through a lot of troublesome frequencies in the speech/TV range.


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## Mpoes12

MLV is still widely used in commercial.soundproofing. None the less some direct testing against green glue was some and found green glue to outperform it by quite a bit. 

I've always wondered if a higher transmission loss rating could be achieved especially at low frequencies if you mixed the two. 


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## doveman

Mpoes12 said:


> I'd be concerned with execution for that instructables page. Wood isn't as resilient as metal. Metal studs also provide better Soubd isolation than wood studs. Using wood hung in cleats wont allow the wall to flex the way hat channel does. The weight could also exceed the weight capacity of that foam to remain effective as a damper. At some point you reach full deflection and no longer see benefit. I would think the weight of the drywall would be able to do that, essentially bottom out the foam. For whatever money might be saved, I think you would risk a lot of work with less benefit.
> 
> I would look for alternative suppliers for ib1 clips. SPC doesn't manufacture them. I found their likely supplier once but can't seem to recall anymore. I would think/hope the manufacturer has dealers in England or parts of mainland Europe to order from.


OK, thanks for taking a look. I was interested from a weight-bearing ability POV but it does seem like the downsides are likely to outweigh any benefits.

I'll keep looking for a UK/European source for the IB-1 clips. So far everywhere I've looked seems to only sell the Genie Clips which are more expensive and deeper (44mm in total when used with 22mm hat channel, compared with 28.5mm for IB-1+hat channel)


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## doveman

Mpoes12 said:


> MLV is still widely used in commercial.soundproofing. None the less some direct testing against green glue was some and found green glue to outperform it by quite a bit.
> 
> I've always wondered if a higher transmission loss rating could be achieved especially at low frequencies if you mixed the two.


Certainly if I was building a frame where I could let the MLV hang loosely I'd consider using it. It probably provides _some_ benefit even when stretched tight but not enough to justify the cost of using it when there's other products that will be more beneficial.


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## HT Geek

doveman said:


> It's not really about how the pipes look, the main reason for burying them was that it would be impossible to build a stud frame in the HT room with them in the way.....
> 
> Another potential problem with burying the pipes is that I'd have to cut notches in the top of the joists to let them sit below the subfloor and that creates the risk that someone might accidentally cut through them when cutting through the floor in future. I think normally the pipes would lie in notches at the bottom of the joists (as my electric cables do) to avoid this risk but I don't think this is practical when retrofitting them.


Depending on how long the pipe run is in the room, it may be feasible to leave them as-is and build a stud wall around them. You would need plenty of cross-bracing. The longer your pipe run, the more cross bracing, but it is possible. It is no different than framing an opening for a large window, with the possible exception of not having a footer on the floor at all in that location. Still, if you think of it as a wide window, I'd venture it can be done and IMO is probably a better/easier option than burying them since it would allow easier future access if necessary. If you do, I'd use a strong header and additional cross bracing above the pipes, and a double or possibly triple jack stud on either side.




> For the living room....
> 
> I can't be sure what was said either but it seems logical that a layer of plaster over the wall will seal it, ...


Based on the research report I posted some time ago on this subject, my recollection is the best result in regards to sealing concrete walls was to use drywall/plaster mud or similar material to seal the concrete and then apply plaster/drywall/other veneer layers. If you only apply plaster or drywall directly to the wall without sealing it, you will leave a very small air gap just due to how the veneer will lay against the concrete. 

The more I think about that, if you used Green Glue or another viscoelastic product in between the plaster and concrete, that ought to mitigate the problem somewhat since GG leaves various small gaps anyway by virtue of how it is applied and yet it still works very well. OTOH, if the concrete isn't sealed to begin with, you may introduce further air pockets and/or cracks in the concrete might contribute to sound leakage. Food-for-thought.




> I should clarify what my motivations are for treating the floor in the living room: ...
> 
> 2) The floorboards are quite squeaky in places and I figured OSB, tightly screwed down with these special screws http://www.screwfix.com/p/spax-flooring-screws-4-5-x-60mm-pack-of-300/88716, would eliminate that, especially if I use square edge OSB rather than T&G, which will also be easier to lay and lift in future without having to damage it. I'd be concerned that unscrewed boards laid on uboats would be liable to squeak as much, if not more, than the current floorboards.


Regarding T&G sheets: Tongue-and-groove is preferred because it helps eliminate squeaks and prevents the boards from moving slightly during installation. 

Regarding uboats and floor movement: You need at least 2 layers of new sub-floor. Lay them with overlapping seams. Use roofing felt between all flooring layers. Use Green Glue or similar product if you'd like (not necessary but should theoretically help with some sound/vibration transmissions). Screw the layers together, but do not penetrate the bottom layer. They won't move.

Regarding squeaking on uboats: if you use enough uboats, you won't have an issue. The key is to use enough to support the floor properly and prevent it from flexing/bending.

Believe me, I can't stand squeaky floors either! In my floor, I installed two layers of 5/8" OSB on top of the existing sub-floor. I did not isolate it from the original floor because it seemed impractical at the time. I realized later (too late) that I easily could have done so since I moved my room entry to the riser level. That said, I did not want to go to the trouble of removing the room's existing sub-floor (it's above my garage). It really boils down to one of the compromise issues. How badly do you want to accomplish something versus the work and cost required?

I think you'd be fine with square sheets. I would have preferred to use T&G but could not find any 5/8" OSB in T&G form and at the time I used 5/8" specifically for a reason (it fit in with my overall plan). I used 2 layers of OSB. They are glued and screwed together. There is roofing felt between the sub-floor and bottom 5/8" OSB layer and between both 5/8" OSB layers. I have no floor squeaks. If you find one, put another couple of screws into your raised floor in the vicinity of the squeak. No more squeak.


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## doveman

HT Geek said:


> Depending on how long the pipe run is in the room, it may be feasible to leave them as-is and build a stud wall around them. You would need plenty of cross-bracing. The longer your pipe run, the more cross bracing, but it is possible. It is no different than framing an opening for a large window, with the possible exception of not having a footer on the floor at all in that location. Still, if you think of it as a wide window, I'd venture it can be done and IMO is probably a better/easier option than burying them since it would allow easier future access if necessary. If you do, I'd use a strong header and additional cross bracing above the pipes, and a double or possibly triple jack stud on either side.


I've attached a sketch showing the pipes (brown). There's two pipes, one above the other and they come in from the living room at approx 70mm from the window wall and are spaced approx. 17mm from the wall all around the room. So the only areas that are free of pipes are most of the dividing wall between the living room and the HT room and about 420mm of the right wall by the door.

Assuming there's 20mm of plaster and I strip it, then the pipes would be approx. 37mm from the concrete wall as opposed to 17mm from the plaster but whether I build from the existing plaster wall or from the concrete wall, with a stud frame spaced 10mm from the wall the pipes will be where the footer needs to go. I still agree that it's better to keep the pipes above the floor rather than bury them, as it would be a major hassle to get to them if they burst (whilst most houses do have them under the floor, they generally only have carpet over the subfloor which is fairly easy to pull back for access) and I could move the pipes inwards so that they sit inside the inner room but with the stud frame approach the room may be too small for that, so I may have to consider ditching the stud frame and just using iso clips and hat channel on the walls.



> Based on the research report I posted some time ago on this subject, my recollection is the best result in regards to sealing concrete walls was to use drywall/plaster mud or similar material to seal the concrete and then apply plaster/drywall/other veneer layers. If you only apply plaster or drywall directly to the wall without sealing it, you will leave a very small air gap just due to how the veneer will lay against the concrete.


Sorry, those two sentences seem contradictory. You say that it's best to seal the walls with drywall/plaster mud but then say that applying plaster/drywall directly to the wall without sealing it first will leave an air gap.



> Regarding T&G sheets: Tongue-and-groove is preferred because it helps eliminate squeaks and prevents the boards from moving slightly during installation.


Maybe this is true of larger sheets but certainly my T&G floorboards aren't helping to eliminate squeaks. One benefit I thought T&G had was that it acted to "seal" the gaps between the boards but maybe I can just stick some tape over the joints between square edged board to achieve the same thing, provided it's thin enough not to cause any unevenness in the floor on top of it? 



> Regarding uboats and floor movement: You need at least 2 layers of new sub-floor. Lay them with overlapping seams. Use roofing felt between all flooring layers. Use Green Glue or similar product if you'd like (not necessary but should theoretically help with some sound/vibration transmissions). Screw the layers together, but do not penetrate the bottom layer. They won't move.
> 
> Regarding squeaking on uboats: if you use enough uboats, you won't have an issue. The key is to use enough to support the floor properly and prevent it from flexing/bending.
> 
> Believe me, I can't stand squeaky floors either! In my floor, I installed two layers of 5/8" OSB on top of the existing sub-floor. I did not isolate it from the original floor because it seemed impractical at the time. I realized later (too late) that I easily could have done so since I moved my room entry to the riser level. That said, I did not want to go to the trouble of removing the room's existing sub-floor (it's above my garage). It really boils down to one of the compromise issues. How badly do you want to accomplish something versus the work and cost required?
> 
> I think you'd be fine with square sheets. I would have preferred to use T&G but could not find any 5/8" OSB in T&G form and at the time I used 5/8" specifically for a reason (it fit in with my overall plan). I used 2 layers of OSB. They are glued and screwed together. There is roofing felt between the sub-floor and bottom 5/8" OSB layer and between both 5/8" OSB layers. I have no floor squeaks. If you find one, put another couple of screws into your raised floor in the vicinity of the squeak. No more squeak.


5/8" is 15.875mm. As I can't increase the hall floor by more than 20mm, I can't increase the living room floor by more than that either, so I can't add two layers of 5/8" OSB on top of the existing subfloor. Even if I remove the existing 18mm floorboards, two layers of 15.875mm OSB + 6mm ply to stick the cork tiles to, plus 4.7mm cork tiles would be an increase of 24.45mm and that's without the thickness of any roofing felt. Plus the bottom layer of OSB would be the new sub-floor, so it wouldn't be as good as your setup anyway, where you have a layer of roofing felt between the existing sub-floor and the bottom layer of OSB. If I remove the 18mm floorboards and used two layers of 12.5mm OSB+6mm ply+4.7mm cork tiles, that would be an increase of 17.7mm, so that might be OK with a layer of roofing felt between the OSB layers. Uboats are 1/2' or 12.7mm thick so I wouldn't be able to use those as well but I'm not convinced they're worth the effort anyway and would rather avoid having to remove the floorboards if I can.

It appears that the joists aren't fixed to the wall, so perhaps they're just resting on the concrete slab (with a few mm of insulation between the two). It seems strange not to secure the joists as I'd think they'd move around and make it hard to fix the floorboards on top but I've never built a floor, so what do I know! It might even be better from a noise transmission point of view to remove the joists completely and just lay felt/rubber mat on the concrete slab, with OSB layers on top, which would enable me to have more layers/thickness without exceeding the height of the hall floor and would eliminate the airgap and any problems that creates but unfortunately it's not practical as there needs to be a gap for the electrical cables to lie in.


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## GatorBlues

I had my builder construct a room within a room. This week, without talking to me first, he put in the riser before any drywall had been hung. The riser is attached to the interior room's studs in the back and is flush with the interior room's studs on the sides. I had assumed that the riser would go in after the double drywall/green glue. My fears are that (1) we have a serious problem with the soundproofing where the riser runs down the side of the wall flush with the studs because we can no longer add DD/GG along that wall, and instead, will have a miniscule gap between the riser and the studs, and (2) attaching the riser to the studs in the back is also problematic for soundproofing because it will transmit vibrations. Am I correct? I'd like to be sure I'm not overreacting before I make him tear it out. 

Also, I have 16 inches of concrete on one of the side walls. The interior room's studs are sitting on top of the concrete on that side of the room. What should we use to attach drywall to the concrete surface? Should we just let the drywall pieces hang down from where they are attached to the interior room's studs above?


----------



## GatorBlues

GatorBlues said:


> I had my builder construct a room within a room. This week, without talking to me first, he put in the riser before any drywall had been hung. The riser is attached to the interior room's studs in the back and is flush with the interior room's studs on the sides. I had assumed that the riser would go in after the double drywall/green glue. My fears are that (1) we have a serious problem with the soundproofing where the riser runs down the side of the wall flush with the studs because we can no longer add DD/GG along that wall, and instead, will have a miniscule gap between the riser and the studs, and (2) attaching the riser to the studs in the back is also problematic for soundproofing because it will transmit vibrations. Am I correct? I'd like to be sure I'm not overreacting before I make him tear it out.


Sorry to quote myself, but now I'm wondering if I am in fact overreacting. Perhaps double MDF on the riser, with GG, accomplishes the same effect if we put acoustical sealant to connect the riser to the wall. My hunch is still that this is wrong, however, and that the riser needs to be built after the double drywall is installed floor to ceiling. I need to tell the builder today, if possible, so quick replies would be greatly appreciated.


----------



## HT Geek

GatorBlues said:


> I had my builder construct a room within a room. This week, without talking to me first, he put in the riser before any drywall had been hung. The riser is attached to the interior room's studs in the back and is flush with the interior room's studs on the sides. I had assumed that the riser would go in after the double drywall/green glue. My fears are that (1) we have a serious problem with the soundproofing where the riser runs down the side of the wall flush with the studs because we can no longer add DD/GG along that wall, and instead, will have a miniscule gap between the riser and the studs, and (2) attaching the riser to the studs in the back is also problematic for soundproofing because it will transmit vibrations. Am I correct? I'd like to be sure I'm not overreacting before I make him tear it out.


Considering the trouble you are going to in the first place, no you're not over-reacting and yes, you are correct on comments above.

Your builder's approach does a few things. First, depending on how the riser is constructed, it may join with the air cavity between your inner and outer stud wall to create a larger air cavity. I'm going to guess it's not quite like that as this would also violate building codes. Presuming instead he's affixed the riser rear perimeter wall to the rear inner stud wall, this is still a problem. Risers often function as a bass trap of sorts, and some of that LFE is going to be transmitted directly into your inner stud walls. There's a good reason it is advised to de-couple a riser from the walls, even in a de-coupled room-within-a-room build (though it is a bit less important in the case of a Room-w/in-a-room build). In addition, in your case you'll also be missing the extra mass between the riser, room, and inner stud walls vis-a-vis the DD/GG that should be along that part of your wall. 

Bottom line is your builder has in effect introduced a flanking path. Some may argue it's less significant due to the mass of the riser perimeter, but IMHO the fact that perimeter will be resonating to begin with outweighs any benefits that might be provided by its mass. Besides, it's equivalent to placing a big stud sideways along your wall and expands the surface area of contact with your wall. I just can't see any way to look at your scenario in a good light, especially when you're going above and beyond the average homeowner to begin with.




> Also, I have 16 inches of concrete on one of the side walls. The interior room's studs are sitting on top of the concrete on that side of the room. What should we use to attach drywall to the concrete surface? Should we just let the drywall pieces hang down from where they are attached to the interior room's studs above?


To be clear.... Is your concrete 16 inches thick vertically? Presuming so, ideally you want a small air gap between the concrete surface and your vertically hung drywall. 16" isn't a very big gap, but you would normally have a footer on the bottom of the floor. Ideally, that footer would be slightly off the concrete as well (1/2" or so is OK). I suppose you could theoretically let it hang as you've indicated. I would personally favor placing a footer there, even if it needs to contact the concrete. Sounds like it's not a huge issue if you let it hang, provided you have sufficient height above that 16" to secure the DW well. It would also place a slight strain (from gravity) on the footer that is 16" off the ground, but as long as your wall is 8' or taller it's difficult for me to imagine it would cause any significant deflection in the drywall.


----------



## HT Geek

GatorBlues said:


> Sorry to quote myself, but now I'm wondering if I am in fact overreacting. Perhaps double MDF on the riser, with GG, accomplishes the same effect if we put acoustical sealant to connect the riser to the wall. My hunch is still that this is wrong, however, and that the riser needs to be built after the double drywall is installed floor to ceiling. I need to tell the builder today, if possible, so quick replies would be greatly appreciated.


My personal opinion is it should be pulled out and done properly. Your builder can likely find a creative way to solve the problem without taking the entire riser apart.

Hopefully, they also understand the drywall walls should have a slight (1/4" to 3/8") gap at the top and bottom (i.e. not touch the ceiling or floor directly). The gaps then need to be filled with acoustic caulk (and use caulk saver if prudent, depending on thickness of the gap). This is one reason the recommended install method for DW is ceiling/wall/ceiling/wall. It staggers those 1/4" thick seams (which btw should be caulked in between DW layers).

You are correct about installation order of the riser. It goes in after the DW.


----------



## GatorBlues

HT Geek said:


> Considering the trouble you are going to in the first place, no you're not over-reacting and yes, you are correct on comments above.
> 
> Your builder's approach does a few things. First, depending on how the riser is constructed, it may join with the air cavity between your inner and outer stud wall to create a larger air cavity. I'm going to guess it's not quite like that as this would also violate building codes. Presuming instead he's affixed the riser rear perimeter wall to the rear inner stud wall, this is still a problem. Risers often function as a bass trap of sorts, and some of that LFE is going to be transmitted directly into your inner stud walls. There's a good reason it is advised to de-couple a riser from the walls, even in a de-coupled room-within-a-room build (though it is a bit less important in the case of a Room-w/in-a-room build). In addition, in your case you'll also be missing the extra mass between the riser, room, and inner stud walls vis-a-vis the DD/GG that should be along that part of your wall.
> 
> Bottom line is your builder has in effect introduced a flanking path. Some may argue it's less significant due to the mass of the riser perimeter, but IMHO the fact that perimeter will be resonating to begin with outweighs any benefits that might be provided by its mass. Besides, it's equivalent to placing a big stud sideways along your wall and expands the surface area of contact with your wall. I just can't see any way to look at your scenario in a good light, especially when you're going above and beyond the average homeowner to begin with.
> 
> 
> 
> 
> To be clear.... Is your concrete 16 inches thick vertically? Presuming so, ideally you want a small air gap between the concrete surface and your vertically hung drywall. 16" isn't a very big gap, but you would normally have a footer on the bottom of the floor. Ideally, that footer would be slightly off the concrete as well (1/2" or so is OK). I suppose you could theoretically let it hang as you've indicated. I would personally favor placing a footer there, even if it needs to contact the concrete. Sounds like it's not a huge issue if you let it hang, provided you have sufficient height above that 16" to secure the DW well. It would also place a slight strain (from gravity) on the footer that is 16" off the ground, but as long as your wall is 8' or taller it's difficult for me to imagine it would cause any significant deflection in the drywall.


Yes, it's 16 inches vertically. I had the builder sink the floor by 16 inches so we could walk in level with the rest of the basement and then take two steps down to the front row. The wall is almost 11 feet, including the 16 inches of concrete.

Thanks for your help!


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## GatorBlues

HT Geek said:


> My personal opinion is it should be pulled out and done properly. Your builder can likely find a creative way to solve the problem without taking the entire riser apart.
> 
> Hopefully, they also understand the drywall walls should have a slight (1/4" to 3/8") gap at the top and bottom (i.e. not touch the ceiling or floor directly). The gaps then need to be filled with acoustic caulk (and use caulk saver if prudent, depending on thickness of the gap). This is one reason the recommended install method for DW is ceiling/wall/ceiling/wall. It staggers those 1/4" thick seams (which btw should be caulked in between DW layers).
> 
> You are correct about installation order of the riser. It goes in after the DW.


Yes! I just read up on the drywall installation methods over this weekend. Thanks again.


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## GatorBlues

One more question while I'm on a roll . . . What is recommended for the concrete floor? Should I seal the drywall to the concrete itself, or put down a rubbery layer with an MDF or plywood subfloor on top of it?


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## Primare Knob

I have started the planning and design of my first Home Theater Room. http://www.avsforum.com/forum/19-de...tion/2836441-50sgc-planning-design-phase.html , but I keep running around in circles to get a grip on the sound proofing part of it.

I have been reading through a lot of articles on the web site of the sound proofing company and have a few questions that I like to ask here.

1/ Is it true that the Triple Leaf effect doesn’t seem to have a big impact with concrete/brick walls. http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/

I can come up with the following estimated STC's for my different (constructed) wall types but I can't figure out, or find the data about how to get my brick wall's up to the level that I plan to achieve for my ceiling and back wall.

Estimated STC’s
Ceiling: Estimated STC of 67
http://www.soundproofingcompany.com/soundproof-walls/spc-02-soundproof-wall/
Back Wall: Estimated STC of 71 (Double Stud – Single GG)
http://www.soundproofingcompany.com/soundproof-walls/spc-3-soundproof-wall/
Internal Side Double brick wall (8.3”) (bare): Estimated STC of 48 
http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/
External Front and Side Double brick wall (2 x 3.96”) with air cavity (2.95”)(bare):
Estimated STC of 44+???
http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/

2/ The Internal Double Brick Wall has one side Assembly II (Kitchen side). Brick walls decoupling is an improvent but not for the LF frequencies. Can this be countered with Green Glue, Double Layer of Gyprock or should I use clips. 

3/ I can’t find any mention of using clips or a double layer of Gyprock with green glue on a brick wall. Would that be not effective considering the cost?

4/ With using Clips plus channels plus 2 x Gyprock (5/8”) with green glue I will lose about 61mm (2 3/8”)of space x 2, in room width, for a room that is already narrow. Would this being able to raise the STC above 60 or more, or what need I do, to get the STC of the brick walls above 60 towards 70?


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## HT Geek

GatorBlues said:


> One more question while I'm on a roll . . . What is recommended for the concrete floor? Should I seal the drywall to the concrete itself, or put down a rubbery layer with an MDF or plywood subfloor on top of it?


I suggest you avoid using MDF or OSB on a concrete slab as a sub-floor. Neither are a friend of moisture, and concrete is porous unless sealed (and even then, many sealing products are of dubious longevity).

Depends on how far you're willing to go for sound isolation, comfort, etc. Many concrete floors in the U.S. have carpet and pad because you don't have to worry about using pressure treated wood products to prevent moisture wicking. I believe 'standard' practice for hardwood floors on concrete slabs is to install a 3/4" plywood layer first, and place the hardwood floor on top of the plywood. While it probably won't be pressure treated, plywood is more resistant to temporary or acute moisture issues. If your plywood sub-floor swells, there's a problem causing it that warrants investigation.

Personally, I would prefer a sub-floor consisting of either a 3/8" or 1/2" rubber mat + 3/4" plywood or 3/4" ply|rubber mat|3/4" ply. 

A lot depends on your situation. For example, are there any adjoining rooms? If so, at what height will you enter the HT room and do you have control over that height? As an example, you certainly wouldn't want to introduce a tripping hazard by moving the floor height up 1/2" as you walk into the HT room.

A couple of ideas to handle floor height transitions into an HT room are 1) use a ramp (max slope is 1" height per 1' ramp length) or 2) enter your HT room at riser height.


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## Primare Knob

Is this rubber stuff any good for sound insulation?

M20AD: http://www.soundservice.co.uk/part_e_wall_system_M-20_AD.html
Test: http://www.soundservice.co.uk/tec_spec_M20.html
Certificate: http://www.soundservice.co.uk/test_certificate.html


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## GatorBlues

HT Geek said:


> GatorBlues said:
> 
> 
> 
> One more question while I'm on a roll . . . What is recommended for the concrete floor? Should I seal the drywall to the concrete itself, or put down a rubbery layer with an MDF or plywood subfloor on top of it?
> 
> 
> 
> I suggest you avoid using MDF or OSB on a concrete slab as a sub-floor. Neither are a friend of moisture, and concrete is porous unless sealed (and even then, many sealing products are of dubious longevity).
> 
> Depends on how far you're willing to go for sound isolation, comfort, etc. Many concrete floors in the U.S. have carpet and pad because you don't have to worry about using pressure treated wood products to prevent moisture wicking. I believe 'standard' practice for hardwood floors on concrete slabs is to install a 3/4" plywood layer first, and place the hardwood floor on top of the plywood. While it probably won't be pressure treated, plywood is more resistant to temporary or acute moisture issues. If your plywood sub-floor swells, there's a problem causing it that warrants investigation.
> 
> Personally, I would prefer a sub-floor consisting of either a 3/8" or 1/2" rubber mat + 3/4" plywood or 3/4" ply|rubber mat|3/4" ply.
> 
> A lot depends on your situation. For example, are there any adjoining rooms? If so, at what height will you enter the HT room and do you have control over that height? As an example, you certainly wouldn't want to introduce a tripping hazard by moving the floor height up 1/2" as you walk into the HT room.
> 
> A couple of ideas to handle floor height transitions into an HT room are 1) use a ramp (max slope is 1" height per 1' ramp length) or 2) enter your HT room at riser height.
Click to expand...

We'll simply be putting down carpet when the room is finished. My main concern is keeping the room within a room sealed off as much as reasonably possible from the rest of the house. 

Would acoustic caulk to seal the double drywall to the concrete do the trick? I could then just add the carpet pad and carpet directly on the concrete. 

Or, am I better off to add a rubber under plywood subfloor, caulk the drywall to the plywood subfloor, and put the carpet pad and carpet on top of the plywood? 

Entrance height is not an issue. But is there another reason besides soundproofing and floor height, which I'm overlooking, that should make me lean toward either approach?

Thank you again for all of your help. You are a tremendous resource for the rest of us on these discussion boards.


----------



## HT Geek

GatorBlues said:


> We'll simply be putting down carpet when the room is finished. My main concern is keeping the room within a room sealed off as much as reasonably possible from the rest of the house.
> 
> Would acoustic caulk to seal the double drywall to the concrete do the trick?


For concrete walls, you can. Your sound proofing would be *ideal* if you used clips & channel on a concrete wall. However, realistically I don't believe you're likely to have any issues with sound getting in via those walls. At least presuming we're talking about a basement HT room and the concrete walls are not shared with another floor in the home (i.e. might you have sound vibrating down the concrete walls from rooms above)? Even then, it might not be an issue (more likely to be an issue with sound emanating _from_ your HT room).

Another idea is to build a stud wall next to the concrete. If you were to do that, I'd still recommend 2x drywall w/GG on the HT side.




> I could then just add the carpet pad and carpet directly on the concrete.


For horizontal surfaces on concrete, you ought to be fine with pad + carpet.




> Or, am I better off to add a rubber under plywood subfloor, caulk the drywall to the plywood subfloor, and put the carpet pad and carpet on top of the plywood?


Earlier, I did not grasp the concept you had in mind of placing drywall on the floor. I would recommend against that. Too easy for it to crack and drywall does not like moisture (e.g. absorbing from concrete floor).




> Entrance height is not an issue. But is there another reason besides soundproofing and floor height, which I'm overlooking, that should make me lean toward either approach?


Well, IMHO... I'd say it boils down to your budget, priorities, and how important it is to isolate the tactile feel of sound in your room. Are you going to feel it via your floor, your seat, in the air, etc.? For instance, Butt Kickers transmit tactile sound via your seats. 

Most people seem satisfied with carpet pad + carpet over concrete. If you are keen on eliminating as much tactile response as possible that is not airborne, then you could consider plywood/rubber mat/etc. type of configurations. I'm a fan of using plywood and rubber mat over concrete in part because I don't like cold carpeted floors. When I lived on the East Coast, it was an issue in my basement every winter (cold floor/cold feet).

If you think about the purpose of filling a stage with sand, it's a two-fold gain. First, it helps prevent the whole stage from reverberating when you crank your subs, and possibly vibrating your screen. Second, it isolates the vibrations so that you are feeling airborne sound waves more intensely. Our brains have trouble distinguishing direction of LFE. So, when you reduce or eliminate LFE reaching your body via the floor, it enhances the tactile feel in the room. To some, that is very important. To others, it's not a big deal.




> Thank you again for all of your help. You are a tremendous resource for the rest of us on these discussion boards.


Well, thanks, but I don't know everything. There are some folks here who are way more experienced than me. I just endeavour to share the knowledge.  Just remember every situation is different - room size, construction components, room volume, personal priorities, etc.


----------



## GatorBlues

HT Geek said:


> For concrete walls, you can. Your sound proofing would be *ideal* if you used clips & channel on a concrete wall. However, realistically I don't believe you're likely to have any issues with sound getting in via those walls. At least presuming we're talking about a basement HT room and the concrete walls are not shared with another floor in the home (i.e. might you have sound vibrating down the concrete walls from rooms above)? Even then, it might not be an issue (more likely to be an issue with sound emanating _from_ your HT room).
> 
> Another idea is to build a stud wall next to the concrete. If you were to do that, I'd still recommend 2x drywall w/GG on the HT side.
> 
> 
> 
> 
> For horizontal surfaces on concrete, you ought to be fine with pad + carpet.
> 
> 
> 
> 
> Earlier, I did not grasp the concept you had in mind of placing drywall on the floor. I would recommend against that. Too easy for it to crack and drywall does not like moisture (e.g. absorbing from concrete floor).
> 
> 
> 
> 
> Well, IMHO... I'd say it boils down to your budget, priorities, and how important it is to isolate the tactile feel of sound in your room. Are you going to feel it via your floor, your seat, in the air, etc.? For instance, Butt Kickers transmit tactile sound via your seats.
> 
> Most people seem satisfied with carpet pad + carpet over concrete. If you are keen on eliminating as much tactile response as possible that is not airborne, then you could consider plywood/rubber mat/etc. type of configurations. I'm a fan of using plywood and rubber mat over concrete in part because I don't like cold carpeted floors. When I lived on the East Coast, it was an issue in my basement every winter (cold floor/cold feet).
> 
> If you think about the purpose of filling a stage with sand, it's a two-fold gain. First, it helps prevent the whole stage from reverberating when you crank your subs, and possibly vibrating your screen. Second, it isolates the vibrations so that you are feeling airborne sound waves more intensely. Our brains have trouble distinguishing direction of LFE. So, when you reduce or eliminate LFE reaching your body via the floor, it enhances the tactile feel in the room. To some, that is very important. To others, it's not a big deal.
> 
> 
> 
> 
> Well, thanks, but I don't know everything. There are some folks here who are way more experienced than me. I just endeavour to share the knowledge.  Just remember every situation is different - room size, construction components, room volume, personal priorities, etc.


Clips and channel on concrete is an interesting idea. How do you attach the clips to the concrete? Is that super labor intensive? I have a 16 inch concrete wall down one side of the room that I need to deal with. On that one side, the room within a room studs rest on top of the 16 inch concrete wall. 

I'm confused about the tactile response issue. Using rubber mat/plywood on top of the concrete creates _less _vibration in the seats? I would have guessed the opposite. I assumed concrete wouldn't vibrate as much as wood floating on rubber, and that the seats would feel whatever is happening on the floor. Is it the opposite, i.e., the rubber floor absorbs some of the vibrations the chairs would otherwise experience? 

In any event, it sounds like having carpet pad/carpet installed directly on the concrete won't creating issues for soundproofing. Thus, I'll probably stick with that approach. 

I didn't explain myself very well on the drywall on the floor question. I'm not going to put drywall "on" the floor. I was going to put it on the walls and then acoustically caulk a small gap between the walls and the floor. I wasn't sure if I should just run the caulk along the base of the wall against the concrete floor itself, or put in a subfloor and caulk between the wall and the subfloor. Again, it sounds like the subfloor isn't needed for soundproofing, so I'll just caulk between the walls and the concrete floor.


----------



## HT Geek

GatorBlues said:


> Clips and channel on concrete is an interesting idea. How do you attach the clips to the concrete? Is that super labor intensive? I have a 16 inch concrete wall down one side of the room that I need to deal with. On that one side, the room within a room studs rest on top of the 16 inch concrete wall.


Yes, I recall that per further up this thread. I'd suggest you let it hang suspended off the 16" wall. You previously mentioned the height of the room above that 16" section is >8'. I would just put 1 or 2 extra screws into that wall just above that 16" section on the bottom (into your inner stud wall) to give it a little extra holding power. I would suggest using a footer though, if you have room (perhaps turn a 1x2 sideways if it would fit). My concern is if you don't that the caulk on the bottom might crack over time due to vibration of the wall. OTOH, if you don't have enough room (e.g. your gap is 1/2" or less), just squirt a liberal amount of caulk along the bottom seam w/the concrete floor and hope for the best!




> I'm confused about the tactile response issue. Using rubber mat/plywood on top of the concrete creates _less _vibration in the seats? I would have guessed the opposite. I assumed concrete wouldn't vibrate as much as wood floating on rubber, and that the seats would feel whatever is happening on the floor. Is it the opposite, i.e., the rubber floor absorbs some of the vibrations the chairs would otherwise experience?


Good point. I believe you'd get a little of both. You're right that placing a hard surface _directly_ on the cement floor will exacerbate any reverberations in the floor, because the non-concrete surface on top of the concrete would transmit the sound vibrations better. If you start with a rubber pad, it will help reduce any floor vibrations between the concrete and hard surface. Either way, the key would be to isolate the subfloor from the walls and have an absorptive material under the plywood or OSB. Carpet pads are designed to sit between a solid surface and the carpet, so you wouldn't want to put carpet pad on rubber mat, or carpet on rubber mat. 

I believe the concern in a situation such as yours is primarily one of impact sound waves, such as those from a downward firing sub (if your subs are downward firing). Impact is what you might feel via the concrete. If you're not concerned about impact vibrations then I would stick with your plan of carpet pad + carpet.

A typical concrete floor (residential) has an STC of about 53. If you ARE concerned about impact vibrations/noise, There are some other (superior) ideas I just recalled. Now, IMHO these are overkill and perhaps pointless for your circumstances, but I'll toss them out for you. If you change your mind and REALLY want a robust floor solution, you could consider them. This is presuming cost is not an issue. 



Kinetics RIM Roll-Out Floor Isolation System. Choice of 1", 2", 3", 4" thickness. Thicker = more isolation. These are giant pads you roll out onto the concrete, then place a solid (e.g. wood) layer on top, then your carpet pad and carpet. You can read about them here. With a 2" RIM + 2" of plywood on top and roofing felt between plywood layers, you're looking at STC 66. Adding Green Glue in between the plywood layers, you could probably bump that up to STC 70 or close to it.
Concrete/RIM/Plywood/Concrete. Estimated STC 66.
Concrete/Isolation Pads/Plywood/Concrete. Estimated STC 68.
Concrete/Isolators/Concrete. Estimated STC 69. The isolators create a 2" air pocket. It's the same idea as clips & channel on the walls/ceiling, but designed for concrete floors. Note the air space needs to be vented, which creates additional challenges during construction.
Concrete/Isolators/Reinforced Concrete with 4" air pocket. Estimated STC 71.




> In any event, it sounds like having carpet pad/carpet installed directly on the concrete won't creating issues for soundproofing. Thus, I'll probably stick with that approach.


Its sounds as if you'll be good with that approach. 




> I didn't explain myself very well on the drywall on the floor question. I'm not going to put drywall "on" the floor. I was going to put it on the walls and then acoustically caulk a small gap between the walls and the floor. I wasn't sure if I should just run the caulk along the base of the wall against the concrete floor itself,


Yes. That's the idea. Leave ~1/4" gap top and bottom of the drywall sheets affixed to each wall. Caulk the gaps with acoustic caulk.



> or put in a subfloor and caulk between the wall and the subfloor.


Not unless you build a subfloor across the entire room, which as you've mentioned seems unnecessary in your case.




> Again, it sounds like the subfloor isn't needed for soundproofing, so I'll just caulk between the walls and the concrete floor.


Perfect.


----------



## HT Geek

One more thought... the point of filling the stage with sand is to dampen impact vibrations by increasing the mass of the first object being vibrated (the stage), so that it absorbs more of the energy. So, presuming you are filling your stage with sand then you should be fine (I would think... unless you are really OCD or picky). Lol. 

If you were in a situation such as a condo or apartment, filling the stage with sand would likely not be viable, and in that situation RIM or similar solutions begin to make more sense.


----------



## GatorBlues

HT Geek said:


> I believe the concern in a situation such as yours is primarily one of impact sound waves, such as those from a downward firing sub (if your subs are downward firing). Impact is what you might feel via the concrete. If you're not concerned about impact vibrations then I would stick with your plan of carpet pad + carpet.
> 
> A typical concrete floor (residential) has an STC of about 53. If you ARE concerned about impact vibrations/noise, There are some other (superior) ideas I just recalled. Now, IMHO these are overkill and perhaps pointless for your circumstances, but I'll toss them out for you. If you change your mind and REALLY want a robust floor solution, you could consider them. This is presuming cost is not an issue.
> 
> 
> 
> Kinetics RIM Roll-Out Floor Isolation System. Choice of 1", 2", 3", 4" thickness. Thicker = more isolation. These are giant pads you roll out onto the concrete, then place a solid (e.g. wood) layer on top, then your carpet pad and carpet. You can read about them here. With a 2" RIM + 2" of plywood on top and roofing felt between plywood layers, you're looking at STC 66. Adding Green Glue in between the plywood layers, you could probably bump that up to STC 70 or close to it.
> Concrete/RIM/Plywood/Concrete. Estimated STC 66.
> Concrete/Isolation Pads/Plywood/Concrete. Estimated STC 68.
> Concrete/Isolators/Concrete. Estimated STC 69. The isolators create a 2" air pocket. It's the same idea as clips & channel on the walls/ceiling, but designed for concrete floors. Note the air space needs to be vented, which creates additional challenges during construction.
> Concrete/Isolators/Reinforced Concrete with 4" air pocket. Estimated STC 71.


What's the rough STC of my double drywall/green glue attached to a room within a room? Am I killing the benefits of what I've built by not addressing the concrete floor? 

If I don't add a subfloor as you've described above, would it improve the STC if instead we (1) use a front firing sub, (2) build a small platform for the sub with 2" RIM + 2" of plywood and green glue, rather than doing the it in the entire room, or (3) both? 

Or, what if I were to add 2" RIM + 2" of plywood in the front part of the room (in front of the riser) and only put 2" RIM under the riser itself? Would that as beneficial?


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## Primare Knob

Primare Knob said:


> I have started the planning and design of my first Home Theater Room. http://www.avsforum.com/forum/19-de...tion/2836441-50sgc-planning-design-phase.html , but I keep running around in circles to get a grip on the sound proofing part of it.
> 
> I have been reading through a lot of articles on the web site of the sound proofing company and have a few questions that I like to ask here.
> 
> 1/ Is it true that the Triple Leaf effect doesn’t seem to have a big impact with concrete/brick walls. http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/
> 
> I can come up with the following estimated STC's for my different (constructed) wall types but I can't figure out, or find the data about how to get my brick wall's up to the level that I plan to achieve for my ceiling and back wall.
> 
> Estimated STC’s
> Ceiling: Estimated STC of 67
> http://www.soundproofingcompany.com/soundproof-walls/spc-02-soundproof-wall/
> Back Wall: Estimated STC of 71 (Double Stud – Single GG)
> http://www.soundproofingcompany.com/soundproof-walls/spc-3-soundproof-wall/
> Internal Side Double brick wall (8.3”) (bare): Estimated STC of 48
> http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/
> External Front and Side Double brick wall (2 x 3.96”) with air cavity (2.95”)(bare):
> Estimated STC of 44+???
> http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/
> 
> 2/ The Internal Double Brick Wall has one side Assembly II (Kitchen side). Brick walls decoupling is an improvent but not for the LF frequencies. Can this be countered with Green Glue, Double Layer of Gyprock or should I use clips.
> 
> 3/ I can’t find any mention of using clips or a double layer of Gyprock with green glue on a brick wall. Would that be not effective considering the cost?
> 
> 4/ With using Clips plus channels plus 2 x Gyprock (5/8”) with green glue I will lose about 61mm (2 3/8”)of space x 2, in room width, for a room that is already narrow. Would this being able to raise the STC above 60 or more, or what need I do, to get the STC of the brick walls above 60 towards 70?


Just trying to get some attention quoting my own post.

When using channels and clips with double 5/8" gyprock and green glue, what kind of improvement can one expect on top of that of a brick wall?

Using those channels would leave a 30mm air gap, but the battens thickness starts at 50mm, which would than be compressed to fit the 30mm gap. Would this still be effective as sound insulation? Would I use a high density product to compensate for thickness?

It seems that the R rating in the US and Australia are different. A 14kg/m3 50mm is rated at R1.3, and 17kg/m3 75mm is rated at R2.0. The US R13 mentioned many a time is for a 16 kg/m3 density but I don't know which thickness.


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## BasementBob

HT Geek said:


> Hopefully, they also understand the drywall walls should have a slight (1/4" to 3/8") gap at the top and bottom (i.e. not touch the ceiling or floor directly). The gaps then need to be filled with acoustic caulk (and use caulk saver if prudent, depending on thickness of the gap). This is one reason the recommended install method for DW is ceiling/wall/ceiling/wall. It staggers those 1/4" thick seams (which btw should be caulked in between DW layers).


 There's a nice diagram in post #81 of this thread. http://www.avsforum.com/forum/19-de...undproofing-master-thread-3.html#post24313651


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## GatorBlues

Per my prior posts, our home theater is being built as a room within a room and will be well soundproofed. For the rest of the basement, including the in law suite (where my in laws will actually live), we are concerned about foot noise from above. On the website linked below, I've read up on different options to help alleviate the issue. However, I really have no idea what the cited numbers mean in real world performance. 

http://www.soundproofingcompany.com/product/serena-underlay-tested-soundproof-floors/ 

Are mid-50s good enough for IIC and STC, or should I be spending a small fortune to get to mid-60s? 

What are rough estimates of the IIC and STC of simply adding insulation between the basement and first level floors, but putting hardwoods directly onto the first floor's OSB subfloor, with no extra rubber layer? (That's what currently planned if I don't upgrade at all -- I'm curious how much of an improvement adding the rubber mat and extra layer of OSB will actually provide.)


----------



## HT Geek

GatorBlues said:


> For the rest of the basement, including the in law suite (where my in laws will actually live), we are concerned about foot noise from above....
> 
> Are mid-50s good enough for IIC and STC, or should I be spending a small fortune to get to mid-60s?
> 
> What are rough estimates of the IIC and STC of simply adding insulation between the basement and first level floors, but putting hardwoods directly onto the first floor's OSB subfloor, with no extra rubber layer? (That's what currently planned if I don't upgrade at all -- I'm curious how much of an improvement getting to the mid-50s is.)


Ironically, though that seems it ought to be an easy question to answer, it's not! There's not much lab data (or field test data either for that matter) on IIC for wood joist floors. I say it's ironic because it is so common, one would think there would be tons of data on this subject, but there isn't.

I'd venture you're looking at an IIC >48. There is one report conducted by Kinetics that showed a field tested IIC of 48 on a similar structure. Though there was not a room-within-a-room below, it did have 2x drywall ceiling below. [Reference]

If you take a look at the lab report on the SPC web page you referenced above, you'll find two issues with it (relative to your circumstances): first, the test was on concrete; and second, there's no A/B or before/after comparison. This is the challenge with most lab tests; only a very specific scenario is tested (which is both good and bad, depending on how you look at it).

In the absence of solid, specific information, I can give you some ideas that are known to improve IIC in your situation. IOW, these ideas will improve IIC regardless of what your starting value is. I think that is probably the best you can do quite frankly. Take a look at wood flooring joist tests (there are a few) and you'll be able to see how various scenarios improved (or not) impact sound reduction from the floor above to below.



The largest gain from a rubber underlayment is in having one to begin with (5mm or thicker). Beyond 5mm, your sound proofing gains are a diminishing return. IOW, the gain going from say 5mm thick to 10mm thick is less than going from no pad to a 5mm pad.
We know rubber underlayments DO make a difference with impact sound (and airborne sounds for that matter)
Increasing the mass of the floor above with additional floor coverings _usually_ helps reduce foot fall and other impact noises below. Certain materials are known to improve IIC.
Choice of flooring materials makes a difference. Engineered wood products transmit less impact noise vs. hardwood products, especially >1000 Hz. Porcelain tile is notorious for impact noise transmission and is especially difficult to mitigate.
Examples of a few materials that WILL help, without regard to specific IIC gains from them include: rubber underlayment, additional layers of plywood/OSB sub-flooring, adhesives, concrete gypsum

There is a fascinating but rather short paper released last year that is one of very few examining the role of adhesives in sound proofing, and it found that even standard adhesives such as construction glue help improve IIC when used between sub-flooring and highly 'noisy' materials such as ceramic tile. However, the tests were quite limited in scope and conducted with concrete floors (as seems to be the norm in IIC tests). The same report also noted that even simply sealing tile with grout affects its sound transmission properties (which btw is consistent with other lab tests that found the same to be true of concrete walls).


----------



## HT Geek

Primare Knob said:


> Just trying to get some attention quoting my own post.


I'll reply to your first post when I can later today. In the meantime a few quick comments....



> Using those channels would leave a 30mm air gap, but the battens thickness starts at 50mm, which would than be compressed to fit the 30mm gap. Would this still be effective as sound insulation? Would I use a high density product to compensate for thickness?
> 
> It seems that the R rating in the US and Australia are different. A 14kg/m3 50mm is rated at R1.3, and 17kg/m3 75mm is rated at R2.0. The US R13 mentioned many a time is for a 16 kg/m3 density but I don't know which thickness.


R13 is 3.5" thick (89 mm).

Do NOT compress the insulation batts. You'll create a rigid path for sound transmission (bad). The R ratings do not matter for sound isolation/damping purposes. Density does matter under some circumstances, but in this particular situation it's typically less important. The purpose of the insulation (from a sound proofing perspective) is to lower the energy of sound waves travelling through it. The insulation disperses a portion of the energy from a sound pressure wave into heat, via the resistance to airflow presented by the insulation.

If you wanted extreme sound proofing via insulation in that 30mm cavity, you'd need to look at much heavier density materials (e.g. OC 703/705; something around 8lb/sf or so. 

30mm is not much room, so I'd suggest Linacoustic (~25mm) for a low-density solution or OC 703, 705, or similar products for high density (greater) sound absorption. The latter is designed for such situations and won't create the rigid coupling I warned you about if you compressed typical R11/R13/R15 fiberglass or rockwool insulation.


----------



## HT Geek

Primare Knob said:


> I have started the planning and design of my first Home Theater Room. http://www.avsforum.com/forum/19-de...tion/2836441-50sgc-planning-design-phase.html , but I keep running around in circles to get a grip on the sound proofing part of it.
> 
> I have been reading through a lot of articles on the web site of the sound proofing company and have a few questions that I like to ask here.
> 
> 1/ Is it true that the Triple Leaf effect doesn’t seem to have a big impact with concrete/brick walls.


Relative to concrete walls, the SPC web page you mentioned simply demonstrates the effect of larger air cavities on how a concrete wall resonates sound through it. I don't know if brick has the same characteristics or not, but it seems logical to presume so, though it may very well be worse since brick is partially hollow (perhaps similar to concrete block performance). Brick - like concrete - will have an unavoidable air gap if you attach a veneer directly to it, such as a sheet of drywall. That can be overcome by sealing the wall before applying a mass layer to it (e.g. drywall sheet). There is a NRC study that demonstrated the simple act of sealing concrete walls improves its sound dampening performance, when there is a sheet of drywall attached to it on the side that was sealed.

Concrete and brick are still going to be affected by the triple leaf effect. It's not really discussed in that article. What it does show is that:


Attaching furring strips directly to either side of a concrete wall increases the size of its air gaps
Larger air gaps result in superior sound dampening performance
Insulation mimics the effect of enlargening an air gap
Furring strips attached directly to a concrete wall create a larger air gap that attenuates higher frequencies while simultaneously exacerbating low frequency emissions (LFE) transmission (due to coupling)

So, what are the helpful conclusions we can draw from this information?


If your primary concern is attenuating LFE, these won't be good solutions. Instead, you'll need to look at de-coupling the walls from the brick. 
If your main concern is higher frequency sound waves, the ideas noted above might work for you, albeit at the potential expense of worse LFE performance.

My suggestion: build a true room-within-a-room, with double stud, staggered stud, or clips & channel on each wall and the ceiling.




> I can come up with the following estimated STC's for my different (constructed) wall types but I can't figure out, or find the data about how to get my brick wall's up to the level that I plan to achieve for my ceiling and back wall.
> 
> [/FONT] Estimated STC’s
> Ceiling: Estimated STC of 67
> Back Wall: Estimated STC of 71 (Double Stud – Single GG)
> Internal Side Double brick wall (8.3”) (bare): Estimated STC of 48
> External Front and Side Double brick wall (2 x 3.96”) with air cavity (2.95”)(bare):
> Estimated STC of 44+???
> 
> 2/ The Internal Double Brick Wall has one side Assembly II (Kitchen side). Brick walls decoupling is an improvent but not for the LF frequencies. Can this be countered with Green Glue, Double Layer of Gyprock or should I use clips.


2x gyprock + GG will help, but you'd get better results with clips & channel + 1 layer of gyprock. For best results, de-couple with clips + channel and use 2x gyprock + GG.

I wouldn't leave any brick walls bare as they will be fantastically reflective surfaces (bad) inside your room. IMO, a well sound proofed room with fewer seats where you can truly savour the experience is better than adding one more seat in a room with poor acoustics.




> 3/ I can’t find any mention of using clips or a double layer of Gyprock with green glue on a brick wall. Would that be not effective considering the cost?


No. At least not for LFE. If you take a look at SPC's Assembly II, you can expect to get better performance where there were improvements with Assembly II (mostly mid-freq range improvement). Note that if you were to seal the wall first, you would improve LFE performance, but not to the extent you'll get from a room-within-a-room configuration (clips/double or staggered stud wall).

If there are space constraints, IMHO it's not a bad idea to go this route provided you seal the wall first, but it's not preferred. Now, let's say you only had a 1" or so gap (25mm). If I were in your shoes, I'd consider using that space to add more mass (and seal the brick first), versus a 1" air gap with insulation. I haven't compared estimated performance of those two options side-by-side, but if I were in that situation I would do so and then make a decision.




> 4/ With using Clips plus channels plus 2 x Gyprock (5/8”) with green glue I will lose about 61mm (2 3/8”)of space x 2, in room width, for a room that is already narrow. Would this being able to raise the STC above 60 or more, or what need I do, to get the STC of the brick walls above 60 towards 70?


Is it more important to have another 4-3/4" of space or to get more sound insulating satisfaction out of the end result of your room?

You can't do anything better within that depth constraint (2-3/8"). You would need another 4-1/2" or more (on each wall; lose another 9" of space wall-to-wall) to fit 3" (77mm) for insulation and 1-1/2" for a 2x2 stud (38x38mm). Attach the 2x2 studs to the brick (don't seal it), clips and channel to the 2x2's, stuff gap with 3" thick insulation, 2x gyprock and GG between.

Also consider if your goal is to keep external sounds outside of your HT room, or keep the sound in your HT room isolated from leaving the room. It's worth ascertaining the volume of whichever you're trying to combat and set your minimum bar at a level that will (theoretically) accomplish your goal. For example, if you are concerned with keeping sound inside the HT room and not so concerned with external sounds coming in, and you are the type of person who won't listen very loudly (e.g. reference levels), perhaps you are willing to sacrifice some sound attenuation for more finished wall-to-wall space in your room. 




Primare Knob said:


> Is this rubber stuff any good for sound insulation?
> 
> M20AD: http://www.soundservice.co.uk/part_e_wall_system_M-20_AD.html
> Test: http://www.soundservice.co.uk/tec_spec_M20.html
> Certificate: http://www.soundservice.co.uk/test_certificate.html


Tough to say. Without having ever seen it, and given only the preponderance of evidence on the website you mention, I would say it's a dud. Here's why:

There are a number of red flags on that site that remind me of "scientifically proven" dietary supplements.

It has the appearance of rubber underlayment. It looks like someone took a recycled rubber mat and decided to rotate it 90° on the z-axis and market it as a 'new' product. If that's a good description, then it's a solid product with mass. That means it will rely on mass for sound attenuation, or IOW it's as if you're just making the wall thicker. On a floor, rubber underlayments are great. They are particularly good at attenuating impact noise at the source. Yet the linked test report was an airborne sound test. Ok, fine. How well does this product perform against airborne sound when compared to other choices (or period for that matter)?

The test was a field test. A brick wall was tested (helpful for you), but given the fact it was not in a lab, it's difficult to ascertain exactly what factors contributed to the end results. Any test is only truly valuable when it's an A/B test. Here's what we had before (A) and after (B) we used _Product X_ in the exact same environment where the only thing that changed was the absence or presence of _Product X_. 

Testing with the presence of a product only (as in this case) is of questionable value. Sometimes, one can ascertain the "A" (before) value by reviewing other test case scenarios that are very similar to what one would need in a 'before' test. For example, there are multiple [lab] test cases that have measured how much sound is attenuated by a single sheet of drywall secured in various ways to various building materials (e.g. on 2x4 wood studs or 2x3 metal studs). So, if you came across a test of _Product X_ over drywall attached to 2x4 wood studs at 24" O.C., even if the tester didn't perform a control test, you can find the data you need (to compare to the 'after' test of _Product X_) and determine exactly how beneficial Product X may be based on the delta of the two test results and allowing the possibility of a small margin of difference to account for any unknown factors such as different labs. As a point-to-point tool for comparing performance, that information would be useful. But if you don't have an "A" (before) scenario test, your "B" (after) test results are in reality inconclusive. I hope that makes sense and I'm not beating a dead horse here. 

Field tests are single data points that *should* take into consideration all the characteristics of the test site. The problem with them is you won't be able to replicate the exact scenario anywhere else as each set of circumstances are unique. OTOH, it's useful to get real-world data. The advantage of lab tests is it should be possible to reproduce them and expect results within a few percentage points of any other lab test of the same product, presuming test product uniformity.

Those criticisms aside, let's give M20AD the benefit of the doubt and analyze it further. Did you also read the "Technical Specs" page? If the product is so good, I'm puzzled as to why there is only a 2db reduction when their test wall is doubled in thickness and mass. They provide this example: 

Plasterboard | Stud & air gap - no insulation | Plasterboard | M20AD | Plasterboard | Plasterboard

compared to this example:

Plasterboard | Plasterboard | M20AD | Plasterboard | Stud & air gap - no insulation | Plasterboard | M20AD | Plasterboard | Plasterboard

Basically saying if I take an installation with M20AD and 2x drywall on one side of a wood stud wall, and install an extra 2 sheets of plasterboard and 1 extra layer of M20AD on the other side of the wall, I'll get 2db better performance. That seems like a huge diminishing return and waste of $ given the fact the first example supposedly yields a 10db benefit, compared with the control test which was 1 layer of plasterboard on either side of a wood stud with no insulation. So, if I spend 2x the cost of materials, I get 12db reduction instead of 10db. That's not a good value proposition. I'm not sure if their marketing department thought that through before it was published.

They don't tell you what you could expect for db reduction from 2x plasterboard only on either side of a wood stud, without their M20AD product. AND most importantly they don't tell you the frequency of their claimed db reductions.

Why is there no insulation in the wall in any of their disclosed test results? I'll venture that if you took the single-M20AD example in their Technical Specs page and tested that scenario with fiberglass insulation inside the wall that it would fare as well or better than their dual-M20AD example. 

We also know they bonded (glued) their M20AD product to the test wall. However, we don't really know if there was an air gap there or not. If I glue drywall to concrete block, there will still be tiny air gaps unless I completely seal the concrete first. I also can't tell if M20AD is porous or not.

Beyond adding mass, I'm not sure this product is bringing anything to the table. If it's not, you might as well add another layer of sheetrock, which is likely much cheaper.

The test report only indicates performance from 100-3150 Hz. This is not atypical for field tests, however it underscores the fact all their info is not the total picture. It would be much more valuable if there were both lab test and field test data and if they corroborated one another.

The field test reports DnT,w which is the Weighted, Standardized Level Difference. It's a measure of airborne sound transmission and is a fancy way of saying, "we played some sounds in this room that were _x_ loud, and in this other room connected to it they were _y_ loud." Fine, because that's what you want to know. However, it includes flanking noises as well, which makes an objective analysis of the results difficult if not dubious. Again, it's great info if that is your room/house/building, but if it's not yours then a lab test would be much more informative in helping you make a decision on whether or not a product is going to be useful to you. When you have lab tests that objectify the results by eliminating possible environmental contamination, you know for sure at what level a given product is effective. Then it becomes your job to take advantage of that effectiveness by isolating flanking noises in your space to take glean the most benefit from the product.

Last, but not least their website makes this claim at the bottom of the technical specs page, [emphasis added]

_"This system is designed to comply with Part E of the building regulations to control noise through separating walls. The type of noise these regulations are addressing is normal household noise that would not normally expect to be heard. *Loud noise or low frequency thump such as from stereo systems is more difficult to address and can only be treated with a much thicker sound insulation system such as can be achieved with our independent soundproofed stud system*."_


----------



## HT Geek

@Primare Knob, you piqued my curiosity a bit, so I dug up a few comparisons for you. These are lab test results, using STC methodology.

Incidentally, 1x sheet 5/8" drywall on both sides of a 2x4 wood stud wall + fiberglass insulation in between = STC 40; and 2x sheet 5/8" drywall on both sides of a 2x4 wood stud wall + fiberglass insulation in between = STC 44.


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## GatorBlues

I'm going to need electrical outlets every 6 feet to stay compliant with the building code. I'm concerned about having so many holes in my room within a room. Brainstorming, I came up with three options: (1) I can put putty pads around the outlets; (2) I can have the builder construct a pseudo-chair rail around the room, or an extra deep baseboard, in either case just barely deep enough to hold shallow outlet boxes; this approach would place the outlet boxes outside the double drywall; or (3) perhaps I can have him build a double drywall box for each outlet that would be recessed into the wall cavity (akin to a backer box for an in wall speaker). Thoughts?


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## Primare Knob

HT Geek said:


> @*Primare Knob* , you piqued my curiosity a bit, so I dug up a few comparisons for you. These are lab test results, using STC methodology.
> 
> Incidentally, 1x sheet 5/8" drywall on both sides of a 2x4 wood stud wall + fiberglass insulation in between = STC 40; and 2x sheet 5/8" drywall on both sides of a 2x4 wood stud wall + fiberglass insulation in between = STC 44.


Are they a bit optimistic here?

http://www.soundproofingcompany.com/soundproof-walls/spc-01-soundproof-wall/


----------



## Primare Knob

HT Geek said:


> I'll reply to your first post when I can later today. In the meantime a few quick comments....
> 
> 
> 
> R13 is 3.5" thick (89 mm).
> 
> Do NOT compress the insulation batts. You'll create a rigid path for sound transmission (bad). The R ratings do not matter for sound isolation/damping purposes. Density does matter under some circumstances, but in this particular situation it's typically less important. The purpose of the insulation (from a sound proofing perspective) is to lower the energy of sound waves travelling through it. The insulation disperses a portion of the energy from a sound pressure wave into heat, via the resistance to airflow presented by the insulation.
> 
> If you wanted extreme sound proofing via insulation in that 30mm cavity, you'd need to look at much heavier density materials (e.g. OC 703/705; something around 8lb/sf or so.
> 
> 30mm is not much room, so I'd suggest Linacoustic (~25mm) for a low-density solution or OC 703, 705, or similar products for high density (greater) sound absorption. The latter is designed for such situations and won't create the rigid coupling I warned you about if you compressed typical R11/R13/R15 fiberglass or rockwool insulation.


 Hi HT Geek,

First of all thank you for elaborated answers. It is much appreciated.

I have started to look into the OC703/705 insulation materials. I came across this info where they use the material for acoustic treatment and I am assuming here that the same ground principle applies for acoustics and sound proofing. I have read a few times more that more density isn’t always the best approach, but does this applies to my project as well?
http://www.readyacoustics.com/index.php?main_page=faq_info&fcPath=13_4&faqs_id=36

I have found similar products here in Australia to OC 703 (48kg/m2), and can find materials up to a 130kg/m2.

The 30mm gap is a theoretical estimated based upon information on the sound proofing site, but there are 3 possibilities here.

1/ the sound proofing fits the gap.
2/ the sound proofing is to thick and needs to be compressed. (to which extend can you compress it?)
3/ the sound proofing is to thin and leaves a small air gap. 

Option 1 would be the best, but are option 2 and 3 equally bad?


----------



## Primare Knob

HT Geek said:


> Relative to concrete walls, the SPC web page you mentioned simply demonstrates the effect of larger air cavities on how a concrete wall resonates sound through it. I don't know if brick has the same characteristics or not, but it seems logical to presume so, though it may very well be worse since brick is partially hollow (perhaps similar to concrete block performance). Brick - like concrete - will have an unavoidable air gap if you attach a veneer directly to it, such as a sheet of drywall. That can be overcome by sealing the wall before applying a mass layer to it (e.g. drywall sheet). There is a NRC study that demonstrated the simple act of sealing concrete walls improves its sound dampening performance, when there is a sheet of drywall attached to it on the side that was sealed.



My bricks are solid without a hollow core, but can have an air gap depending on the brickies work since the bricks have a shallow dip on top of them to anchor the mortar/cement into. Up so far, of all the bricks we have removed they seem to have done a proper job. 


What do you mean by sealing a brick wall. Do you mean to render the wall or apply some kind of membrane like a water proofing product?



> Concrete and brick are still going to be affected by the triple leaf effect. It's not really discussed in that article. What it does show is that:
> 
> 
> Attaching furring strips directly to either side of a concrete wall increases the size of its air gaps
> Larger air gaps result in superior sound dampening performance
> Insulation mimics the effect of enlargening an air gap
> Furring strips attached directly to a concrete wall create a larger air gap that attenuates higher frequencies while simultaneously exacerbating low frequency emissions (LFE) transmission (due to coupling)
> 
> So, what are the helpful conclusions we can draw from this information?
> 
> 
> If your primary concern is attenuating LFE, these won't be good solutions. Instead, you'll need to look at de-coupling the walls from the brick.
> If your main concern is higher frequency sound waves, the ideas noted above might work for you, albeit at the potential expense of worse LFE performance.
> 
> My suggestion: build a true room-within-a-room, with double stud, staggered stud, or clips & channel on each wall and the ceiling.
> 
> 
> 
> 
> 2x gyprock + GG will help, but you'd get better results with clips & channel + 1 layer of gyprock. For best results, de-couple with clips + channel and use 2x gyprock + GG.
> 
> I wouldn't leave any brick walls bare as they will be fantastically reflective surfaces (bad) inside your room. IMO, a well sound proofed room with fewer seats where you can truly savour the experience is better than adding one more seat in a room with poor acoustics.


 The rest of the house has drywall directly attached to the brickwork on both sides. I do find the house to be noisy for a place with solid double brick internal walls. Although it is hard to say where the noise is coming from and the ceiling isn’t helping either.

The current plan is to use channels and clips for all the brick walls and ceiling, and build a double stud wall for the back wall of the theatre. One of the questions with that is how much of an improvement the special whisper clips have on top of using regular clips. An estimate based upon the info on the sound proofing site is that I’ll lose 2.44”(62mm) of space when using clips with channels and two layers of 5/8” (16mm)drywall with green glue, which leaves an air gap of 1.18”(30mm). All theoretically at the moment, but I like to keep the width of the room as big as possible as my speakers require a bit of space.



> No. At least not for LFE. If you take a look at SPC's Assembly II, you can expect to get better performance where there were improvements with Assembly II (mostly mid-freq range improvement). Note that if you were to seal the wall first, you would improve LFE performance, but not to the extent you'll get from a room-within-a-room configuration (clips/double or staggered stud wall).
> 
> If there are space constraints, IMHO it's not a bad idea to go this route provided you seal the wall first, but it's not preferred. Now, let's say you only had a 1" or so gap (25mm). If I were in your shoes, I'd consider using that space to add more mass (and seal the brick first), versus a 1" air gap with insulation. I haven't compared estimated performance of those two options side-by-side, but if I were in that situation I would do so and then make a decision.
> 
> 
> 
> 
> Is it more important to have another 4-3/4" of space or to get more sound insulating satisfaction out of the end result of your room?
> 
> You can't do anything better within that depth constraint (2-3/8"). You would need another 4-1/2" or more (on each wall; lose another 9" of space wall-to-wall) to fit 3" (77mm) for insulation and 1-1/2" for a 2x2 stud (38x38mm). Attach the 2x2 studs to the brick (don't seal it), clips and channel to the 2x2's, stuff gap with 3" thick insulation, 2x gyprock and GG between.
> 
> Also consider if your goal is to keep external sounds outside of your HT room, or keep the sound in your HT room isolated from leaving the room. It's worth ascertaining the volume of whichever you're trying to combat and set your minimum bar at a level that will (theoretically) accomplish your goal. For example, if you are concerned with keeping sound inside the HT room and not so concerned with external sounds coming in, and you are the type of person who won't listen very loudly (e.g. reference levels), perhaps you are willing to sacrifice some sound attenuation for more finished wall-to-wall space in your room.


 The picking order would be, 1- keep the sound inside the room, 2- keep the sound outside the room. But the room width does have veto power if losing the 2 3/8” (x2) isn’t giving me a good improvement. The *BIG* question is to find the theoretical improvement for the 2 3/8” construction. Soundproofing the room is going to be a big investment, and it might be that this room isn’t going to be worth it.


You would think that rubber would be a good material for sound proofing, vibration absorption and mass into one product, but it always seem the fall through in reality.


----------



## HT Geek

Primare Knob said:


> Are they a bit optimistic here?
> 
> http://www.soundproofingcompany.com/soundproof-walls/spc-01-soundproof-wall/


Surprisingly, no. Actually, I believe they are under-estimating performance at 59 STC. It should say 61 STC. Another interesting fact is if one moves from 24" O.C. steel studs to 16" O.C., the STC rating drops to 56. The figures I just quoted are derived from lab tests performed in 2006.

If you move further down the page, you'll find the double stud walls are the crème de la crème of sound proofing.


----------



## HT Geek

Primare Knob said:


> I have found similar products here in Australia to OC 703 (48kg/m2), and can find materials up to a 130kg/m2.
> 
> The 30mm gap is a theoretical estimated based upon information on the sound proofing site, but there are 3 possibilities here.
> 
> 1/ the sound proofing fits the gap.
> 2/ the sound proofing is to thick and needs to be compressed. (to which extend can you compress it?)
> 3/ the sound proofing is to thin and leaves a small air gap.
> 
> Option 1 would be the best, but are option 2 and 3 equally bad?


Option 2 is the only bad one. Option 3 is good. Remember, insulation effectively mimics a larger air cavity. 

Since you have a limited space to place anything, your options will be limited. I'll warn you that now that I am reviewing the NRC figures again, 1" thick 703 or 705 won't be very beneficial in the lower freqs. If that is important to you, I'm afraid the reality is you need more space to damp those LFE's (i.e. thicker insulation and/or air gap). However, even at 1" the 703 and 705 are very good at attenuating mid to higher freqs. 

You may be better off saving your $ and simply using 1" thick Linacoustic. While it won't be stellar at anything in particular, it makes for a good broad-band diffuser. Bonded Logic also makes a 1" thick duct liner product. Or you could even cut rockwool into 1" thick pieces (granted, that will likely make a big mess in the process, but it's a DIY option).

Quite frankly, you might be better off with another layer of gypsum w/Green Glue in between (though that's obviously more expensive). It really depends on your priorities and whether or not cost is a concern.


----------



## Primare Knob

HT Geek said:


> Option 2 is the only bad one. Option 3 is good. Remember, insulation effectively mimics a larger air cavity.
> 
> Since you have a limited space to place anything, your options will be limited. I'll warn you that now that I am reviewing the NRC figures again, 1" thick 703 or 705 won't be very beneficial in the lower freqs. If that is important to you, I'm afraid the reality is you need more space to damp those LFE's (i.e. thicker insulation and/or air gap). However, even at 1" the 703 and 705 are very good at attenuating mid to higher freqs.
> 
> You may be better off saving your $ and simply using 1" thick Linacoustic. While it won't be stellar at anything in particular, it makes for a good broad-band diffuser. Bonded Logic also makes a 1" thick duct liner product. Or you could even cut rockwool into 1" thick pieces (granted, that will likely make a big mess in the process, but it's a DIY option).
> 
> Quite frankly, you might be better off with another layer of gypsum w/Green Glue in between (though that's obviously more expensive). It really depends on your priorities and whether or not cost is a concern.


Is there any way to calculate the theoretical improvement of these options?


----------



## doveman

As I have concrete slab under my floorboards and joists, I was wondering if I could just remove the floorboards and joists completely and lay 25mm layer of rigid insulation on the concrete, with 30mm (2*15) of OSB on top, then 6mm plywood with 4.7mm cork tiles stuck to it? As the joists don't appear to be attached to the wall, then the concrete slab is currently taking all the weight of the floor and anything on it, so that wouldn't change.

If that isn't a bad idea, would any of these products be suitable?

https://www.insulationsuperstore.co...rsal-slab-rs45-1200mm-x-600mm-720m2-pack.html
https://www.insulationsuperstore.co...ic-insulation-slab-25mm-30mm-8-64m2-pack.html
https://www.insulationsuperstore.co...eps-70-floor-insulation-24m-x-12m-x-25mm.html
https://www.alsfordtimber.com/build...oard-1200-x-2400-x-25mm-13-pack-hbmeco25.html

My concern would be that the insulation might compress a bit over time and also as the subfloor won't be screwed down, where there's weight on one end of a board (say a sofa with several people sitting on it) then the other end of the board might rise up a bit which would be a bit unsafe and would also damage the tiles. I guess that could be a problem with any solution where the subfloor isn't screwed to the joists or whatever is underneath though.

I'll also have to accommodate the electrical cables that run under the floor. As I've shown in the first sketch, If I was just doing the floor and not the walls, I could have wooden joists at the edge with cutouts for the conduit, so the subfloor above would be supported on wood rather than insulation at the edge of the room, with rubber strip (indicated in black) to decouple the subfloor from the wooden joists. As per the second sketch, if I'm using clips and drywall on the wall then this will create a gap at the perimeter where the conduit can run. If I build studwalls with the footer board attached to the concrete slab then I'd have to use wooden joists as per the first sketch, as there won't be a gap at the perimeter to put the conduit in.


----------



## HT Geek

Primare Knob said:


> My bricks are solid without a hollow core, but can have an air gap depending on the brickies work since the bricks have a shallow dip on top of them to anchor the mortar/cement into. Up so far, of all the bricks we have removed they seem to have done a proper job.
> 
> 
> What do you mean by sealing a brick wall. Do you mean to render the wall or apply some kind of membrane like a water proofing product?


AFAIK, any method of sealing out water should work, but then so would standard drywall/plaster mud. You want to seal all the crevices, holes, and cracks where sound might escape and ideally provide a smooth surface to attach the plasterboard to. The main goals are to make the brick or concrete non-porous (to moisture, sound, etc.) and eliminate the tiny air gaps caused by rough surfaces.

From a few weeks ago in this thread:



HT Geek said:


> _When the concrete block is porous, sealing
> the surface with plaster or block sealer
> significantly improves the sound insulation;
> the more porous the block, the greater
> the improvement. Improvements of 5 to
> 10 STC points, or even more, are not
> uncommon for some lightweight block
> walls after sealing. Conversely, normal weight
> blocks usually show little or no
> improvement after sealing. This improvement
> in STC in lightweight blocks is related
> to the increased airflow resistivity of these
> blocks. The leakage of sound through the
> material of the block is different only in
> degree from leakage of sound through
> inadequate mortar joints. To ensure good
> sound insulation, mortar joints must always
> be properly finished — that is, free from
> obvious penetrations.
> _
> 
> - _*Controlling Sound Transmission through Concrete Block Walls*_ (Andy Warnock, Construction Technology Update No. 13, 1998).
> 
> I know Andy was talking about STC, which is why I said generally. He didn't publish all the TL charts in that paper, so we can't say if his statements were universal in a given frequency zone. Regardless, attempting to isolate LFE is notoriously confounding and meanwhile there is nothing negative about improving your wall's STC rating if these factors apply. So, it is more food-for-thought for you.
> 
> This concept would be accretive to to any other sound proofing measures you choose to undertake.
> 
> Given the very limited space constraints for sound proofing you have along one shared wall in particular, this information might be helpful.





> The rest of the house has drywall directly attached to the brickwork on both sides. I do find the house to be noisy for a place with solid double brick internal walls. Although it is hard to say where the noise is coming from and the ceiling isn’t helping either.


Yes, flanking noise can be quite a challenge to isolate. Not to mention the sealing issue above (or lack of sealing in your case).




> The current plan is to use channels and clips for all the brick walls and ceiling, and build a double stud wall for the back wall of the theatre. One of the questions with that is how much of an improvement the special whisper clips have on top of using regular clips. An estimate based upon the info on the sound proofing site is that I’ll lose 2.44”(62mm) of space when using clips with channels and two layers of 5/8” (16mm)drywall with green glue, which leaves an air gap of 1.18”(30mm). All theoretically at the moment, but I like to keep the width of the room as big as possible as my speakers require a bit of space.


Why not do clips & channel all around? You'd save some space by foregoing the single double stud wall and it would keep your efforts consistent.

I have not seen any objective comparisons between different brands of clips where all other factors were equal. What I have seen are lab reports that demonstrate clips and hat channel are very effective. Theoretically, it's logical to presume clips with a rubber isolator would fare a bit better than those without, but as I see it the differences between clips are marketing differentiators and/or getting around others' patents. Another discernable difference between clips is some require a single screw to secure them to the stud, while others require two screws. There are pros and cons to each approach. Nothing worth splitting hairs over.

If you use the $2 cheapo clips with no rubber or neoprene, you're still getting 90% of the benefit of the more expensive $6 or $7 clips, which is the decoupling/isolation. I would go with whichever clips are readily available to you geographically, fit your budget, and appeal to you from an installation or mechanical viewpoint.




> The picking order would be, 1- keep the sound inside the room, 2- keep the sound outside the room. But the room width does have veto power if losing the 2 3/8” (x2) isn’t giving me a good improvement. The *BIG* question is to find the theoretical improvement for the 2 3/8” construction. Soundproofing the room is going to be a big investment, and it might be that this room isn’t going to be worth it.


To make sure we're on the same page here, what do you mean exactly by 'the 2 3/8" construction'? And when you say 'it might be that this room isn't going to be worth it,' are you referring to your dedicated HT room or the adjoining room where you have the option to use 2 3/8" of space in your HT room for sound proofing?




> You would think that rubber would be a good material for sound proofing, vibration absorption and mass into one product, but it always seem the fall through in reality.


Well, it does help, but I believe it's better suited for flooring. Unless you're able to float a floor in isolators, rubber mat is the next best thing. It's also particularly beneficial relative to impact noise.


----------



## HT Geek

Primare Knob said:


> Is there any way to calculate the theoretical improvement of these options?


Yes. I've compiled a list for you below of all the 1" thick products of which I have acoustic data. You may also want to check out Bob Gold's absorption coefficients page, which is the unofficial Bible of sound proofing insulation materials.  I believe Bob has updated his site recently, and it's now easier to read and contains more info.

Keep in mind the first question is always what are you trying to accomplish? For instance, which portions of the frequency spectrum (20-20,000hz) are you seeking to tame? Next, what are your constraints? Were depth not a limiting factor, it would be much easier to simply look at the freq ranges of biggest concern and attack the problem from that perspective. In your case, it's possible that your space constraints will lead you down a path of accepting what you can get in small depth or doing nothing (relative to insulation). I would argue you'll be better off with _some _form of insulation versus none. Even if it's not doing much to address your primary frequency range(s) of concern, anything you do will likely help just a little bit.

Here are some examples of comparing a few products given your 1" space constraint [the forum tools don't make formatting this in a legible fashion a priority, but hopefully you can glean the jist of it]:

*Product	thickness	mounting	density	125hz	250hz	500hz	1000hz	2000hz	4000hz	NRC*
Kaowool Blanket	1" (25mm)	on wall	4.0 pcf (64 kg/m3)	----	0.29	1.00	1.04	0.99	0.98	0.85
Kaowool Blanket	1" (25mm)	on wall	8.0 pcf (128 kg/m3)	----	0.50	0.92	0.91	0.91	0.94	0.80

Owens Corning Products
703, plain	1" (25mm)	on wall	3.0 pcf (48 kg/m3)	0.11	0.28	0.68	0.90	0.93	0.96	0.70
705, plain	1" (25mm)	on wall	6.0 pcf (96 kg/m3)	0.02	0.27	0.63	0.85	0.93	0.95	0.65
QuietR Rotary Duct Liner	1" 0.05	0.3	0.6	0.87	0.98	1.05	0.70

Roxul Rockboard 60	1"	on wall	3.0 pcf (48 kb/m3)
Bonded Logic Duct Liner	1" 1.5 pcf	0.07	0.33	0.72	0.99	0.99	0.96	0.75
Tuff Guard Duct Liner 1" (DL100)	1" (25mm) 0.10	0.28	0.50	0.70	0.82	0.83	0.60
Linacoustic RC	1" (25mm) 0.08	0.31	0.64	0.84	0.97	1.03	0.70
Permacote® Linacoustic® R-300	1" (25mm) 3.0 pcf (48 kg/m3)	0.04	0.26	0.69	1.00	1.07	1.02	0.75
Permacote Linacoustic Standard	1" (25mm) 0.09	0.31	0.67	0.91	1.01	0.98	0.70
Spin-Glas® Board (HVAC use)	1" (25mm) 3pcf (48kg/m3)	0.06	0.26	0.61	0.86	0.99	1.03	0.70
Spin-Glas® Board (HVAC use)	1" (25mm) 6pcf (96.2kg/m3)	0.10	0.35	0.85	1.04	1.05	1.03	0.80

Sound Seal (aka Industrial Noise) Products
DL100 (Duct Liner)	1" 0.13	0.28	0.51	0.70	0.81	0.86	0.60
DL100 (Duct Liner)	1" 0.12	0.47	0.85	0.84	0.64	0.62	0.70

K-Flex Duct Liner Gray	1" 1.5 pcf (24 kg/m3)	0.06	0.17	1.06	0.32	0.67	0.54	0.55

Certainteed Products
Tuff Guard R Duct Liner 150	1" 1.5 pcf (24 kg/m3)	0.18	0.36	0.59	0.86	0.95	0.90	0.70
Insul-SHIELD 300, Unfaced	1" 3 pcf (48 kg/m3)	0.06	0.29	0.75	0.99	1.04	1.02	0.75
Insul-SHIELD 600, Unfaced	1" 6 pcf (96 kg/m3)	0.10	0.35	0.85	1.04	1.05	1.03	0.80

Ductmate PolyArmor (Polyester Duct Liner)	1" 1.6 pcf	0.1	0.3	0.73	1.07	0.49	----	0.65



Notes:

1. Kaowool Blanket is a ceramic product. Rather expensive and relatively uncommon. Probably best bang-for-the-buck in a 1" thick space if cost is truly not a limiter. Here in the USA it's just over $4 psf (per square foot). Smallest size for sale I've seen is a roll of 50 square feet. The manufacturer's acoustic data does not extend below 250hz, making its LFE performance suspect. As I stated previously, you're just not going to get much attenuation of LFE with a 1" product (well, unless perhaps you use lead).

2. To date, I've been unable to find acoustic performance data on Rockboard 60, though I have it for Rockboard 40 and 80, I've only seen the 60 advertised in a 1" thick variant. I've listed it here for reference in an effort to give you as complete a picture as possible of 1" thick product options that I'm aware of.


----------



## HT Geek

doveman said:


> As I have concrete slab under my floorboards and joists, I was wondering if I could just remove the floorboards and joists completely and lay 25mm layer of rigid insulation on the concrete, with 30mm (2*15) of OSB on top, then 6mm plywood with 4.7mm cork tiles stuck to it?


That won't work, but this will: RIM for Concrete Floated Floors

It's available in 25mm sized increments from 25-100mm.

Your suggestion above would crush the insulation beneath, creating several problems (including facilitating sound transmission, which you don't want). Normally in a room-within-a-room configuration, a floating floor has a rigid layer on top of the structural sub-floor, then a damping layer (e.g. rubber mat), then another rigid layer or two. The raised floor is detached from the structural walls (small gap), and the inner room is built on top of the floating floor. The floating layers are screwed together (so that underlying layers don't move), but the screws do not penetrate into the structural sub-floor or floor joists. 

Going a step further would require U-boats or a similar product. For example, in a typical floor joist setting, one could remove the sub-floor and attach the U-boats to the top of the floor joists, then replace the sub-floor (except this time around it would be floating). Then add more layers as desired.




> If I build studwalls with the footer board attached to the concrete slab then I'd have to use wooden joists as per the first sketch, as there won't be a gap at the perimeter to put the conduit in.


If you're building a double stud room, ideally build your floating floor first and then position the new stud wall on the floating floor. This helps to further reduce sound transmission between the spaces.


----------



## HT Geek

doveman said:


> If that isn't a bad idea, would any of these products be suitable?
> 
> https://www.insulationsuperstore.co...rsal-slab-rs45-1200mm-x-600mm-720m2-pack.html
> https://www.insulationsuperstore.co...ic-insulation-slab-25mm-30mm-8-64m2-pack.html


No. Variations on the insulation theme.




> https://www.insulationsuperstore.co...eps-70-floor-insulation-24m-x-12m-x-25mm.html


Likely, yes.




> https://www.alsfordtimber.com/build...oard-1200-x-2400-x-25mm-13-pack-hbmeco25.html


No. Like 1 and 2 above, it's meant to go inside crawl spaces, between floors, etc.


----------



## HT Geek

GatorBlues said:


> I'm going to need electrical outlets every 6 feet to stay compliant with the building code. I'm concerned about having so many holes in my room within a room. Brainstorming, I came up with three options: (1) I can put putty pads around the outlets;


That is good to do regardless. Its purpose is to reduce the possibility of flanking via your receptacles.




> (2) I can have the builder construct a pseudo-chair rail around the room, or an extra deep baseboard, in either case just barely deep enough to hold shallow outlet boxes; this approach would place the outlet boxes outside the double drywall;


I can't picture how that would work without looking awkward and garnering unwanted scrutiny from the building inspector.




> or (3) perhaps I can have him build a double drywall box for each outlet that would be recessed into the wall cavity (akin to a backer box for an in wall speaker). Thoughts?


That would work, but it's a lot of labor.

Most people just do option 1. Limit the junction boxes to the inner stud wall (i.e. don't penetrate both walls with the JB). All you need is a single electrical cable from the structural room / electric source that feeds one of your receptacles in the inner room. Then simply daisy-chain them as with any other room. Use putty pads to back them and prevent sound leakage through them. You'll be in good shape. 

The 6' rule is not too bad. It equates to about 1 outlet every 12' or so in a normal room. And in your HT room you'll already have outlets in various locations, such as behind your seats. Keep in mind floor-mounted plugs don't count unless they are close to a wall (within 18" IIRC), and there's no requirement that a wide room meet the 6' distance rule in the center of the room (i.e. room wider or longer than 12').


----------



## GatorBlues

HT Geek said:


> The 6' rule is not too bad. It equates to about 1 outlet every 12' or so in a normal room. And in your HT room you'll already have outlets in various locations, such as behind your seats. Keep in mind floor-mounted plugs don't count unless they are close to a wall (within 18" IIRC), and there's no requirement that a wide room meet the 6' distance rule in the center of the room (i.e. room wider or longer than 12').


I wish it were so. My understanding of the six foot rule where we are building is an outlet every 6 feet, so that you can reach one within 3 feet anywhere along the wall. Hopefully I'm wrong about that, but given the spacing of the outlets installed already in the rest of the house, I unfortunately think I'm correct.


----------



## Primare Knob

HT Geek said:


> AFAIK, any method of sealing out water should work, but then so would standard drywall/plaster mud. You want to seal all the crevices, holes, and cracks where sound might escape and ideally provide a smooth surface to attach the plasterboard to. The main goals are to make the brick or concrete non-porous (to moisture, sound, etc.) and eliminate the tiny air gaps caused by rough surfaces.
> 
> From a few weeks ago in this thread:
> 
> 
> 
> 
> 
> 
> Yes, flanking noise can be quite a challenge to isolate. Not to mention the sealing issue above (or lack of sealing in your case).
> 
> 
> 
> 
> Why not do clips & channel all around? You'd save some space by foregoing the single double stud wall and it would keep your efforts consistent.
> 
> I have not seen any objective comparisons between different brands of clips where all other factors were equal. What I have seen are lab reports that demonstrate clips and hat channel are very effective. Theoretically, it's logical to presume clips with a rubber isolator would fare a bit better than those without, but as I see it the differences between clips are marketing differentiators and/or getting around others' patents. Another discernable difference between clips is some require a single screw to secure them to the stud, while others require two screws. There are pros and cons to each approach. Nothing worth splitting hairs over.
> 
> If you use the $2 cheapo clips with no rubber or neoprene, you're still getting 90% of the benefit of the more expensive $6 or $7 clips, which is the decoupling/isolation. I would go with whichever clips are readily available to you geographically, fit your budget, and appeal to you from an installation or mechanical viewpoint.
> 
> 
> 
> 
> To make sure we're on the same page here, what do you mean exactly by 'the 2 3/8" construction'? And when you say 'it might be that this room isn't going to be worth it,' are you referring to your dedicated HT room or the adjoining room where you have the option to use 2 3/8" of space in your HT room for sound proofing?
> 
> 
> 
> 
> Well, it does help, but I believe it's better suited for flooring. Unless you're able to float a floor in isolators, rubber mat is the next best thing. It's also particularly beneficial relative to impact noise.


I can take a look into sealing the wall, but I doubt it will be very usefull since the brickwork and mortar are pretty solid. (Depending on the cost that probably is.)

With the 2 3/8" construction I do mean clips plus channels with layers of 5/8" drywall with GG inbetween. The room I am talking about is the home cinema room.



Thank you for the data. I'll look into it, but right now I don't really know how to read it.

Doing some more reading on the sound proofing website I cam up with the following. But I am not sure if this really works out this way.

Single Side 2nd layer of 5/8" dry wall is an STC increase of 5
Double Sided 2nd layer of 5/8" dry wall is an STC increase of 6

Single Side layer of Green Glue is an STC increase of 9 (Wood studs) or 6 (Steel studs)
Double Sided layer of Green Glue is an STC increase of 13 (Wood studs) or 10 (Steel studs)

Clips and Channels will give an STC increase of 11 (Wood studs) 

In the long run. The more you double up the smaller the benefit. Ans still the LFE performance is very poor.

Theoretically I think a STC improvement of 20 is possible with the 2 3/8" construction.

The reason for going double stud at the back wall is that it creates enough space/wall thickness to create a double door entry. I could still add clips and channels on top of that, but I assume that the performance of the room will be determined by the weakest link, which probably isn't going to be the back wall.


----------



## HT Geek

GatorBlues said:


> I wish it were so. My understanding of the six foot rule where we are building is an outlet every 6 feet, so that you can reach one within 3 feet anywhere along the wall. Hopefully I'm wrong about that, but given the spacing of the outlets installed already in the rest of the house, I unfortunately think I'm correct.


Hmm. I can tell you even the 2017 NEC code the requirement (not yet in-force) STILL requires one receptacle (outlet) per *6 feet*. I suspect it's more likely your builder has chosen to install more outlets due to consumer demand. If you think about how we all use outlets in our homes, it's changed dramatically since the iPhone was released in 2007. I personally have a home built in 2009, and with my wife, me, and my 2 kids we are often competing for the same outlets to charge our devices!

Do yourself a favor and look up your local building code regulations (city or county). If there is no reference locally, then your state code applies. There is always an explicit state adoption; not always a local adoption. Local building code requirements may supersede state code only when it is more restrictive. Often they simply mimic the state law (for whatever odd reason).

First, determine which NEC version your locality has adopted (NEC = National Electrical Code). If you can't find a reference to the NEC, look for a reference to NFPA 70 (essentially the same thing). For instance, my locality still references the 2012 NEC. The current version is 2014, but a 2017 update is nearing completion. It's 2nd public hearing closes tomorrow. However, it will be some time before any locality adopts the 2017 code version (normally requires a legislature to amend city/county code and adopt it).

I've had contractors come to my home and tell me any new electrical work requires updating to the 2014 NEC. I have to educate them on the fact my locality still uses the 2012 version by pointing out the actual local building code reference. Surprise. Don't presume something is required just because a contractor or builder does it. There are often non-code reasons why things are done a particular way. I'm not saying that's a bad thing either. Just that it may not be required. It's worth your time to investigate.


----------



## HT Geek

Thanks for clarifying.



Primare Knob said:


> I can take a look into sealing the wall, but I doubt it will be very usefull since the brickwork and mortar are pretty solid. (Depending on the cost that probably is.)


Conceptually, imagine skimming the entire wall with a light coat of drywall mud, then sanding it so it's relatively smooth. That's the idea I'm getting at for sealing it. The goal is to get a relatively smooth surface to mate your drywall to and eliminate tiny air gaps.



> Thank you for the data. I'll look into it, but right now I don't really know how to read it.


The higher the number, the more sound is absorbed by the insulation at a given frequency range. NRC is an aggregate value, similar to STC. NRC and STC are useful when comparing different strategies. Higher numbers mean better overall performance. However, what they don't tell you (and what the other figures are good for) is how a given solution performs at say low/medium/high frequencies, or specific frequencies.




> Doing some more reading on the sound proofing website I cam up with the following. But I am not sure if this really works out this way.
> 
> Single Side 2nd layer of 5/8" dry wall is an STC increase of 5
> Double Sided 2nd layer of 5/8" dry wall is an STC increase of 6
> 
> Single Side layer of Green Glue is an STC increase of 9 (Wood studs) or 6 (Steel studs)
> Double Sided layer of Green Glue is an STC increase of 13 (Wood studs) or 10 (Steel studs)
> 
> Clips and Channels will give an STC increase of 11 (Wood studs)


Without verifying your figures above, I would say that you're on the right track. As I said above, STC is sort of an aggregate or weighted value. It's useful for back-of-the-envelope comparisons of various STC solutions to one another. So, you can say solution A with a higher STC than solution B is going to be better at sound proofing _overall_. But you can still get circumstances where a lower STC may outperform a higher STC solution _at a particular frequency range_. As you get wider apart from one another in an A/B comparison, that's less likely to be the case (e.g. with an STC delta of say 10 points, you're very unlikely to have the lower STC solution outperform in any freq range).

Something else to consider when looking at STC improvements of various solutions is what is your starting point? For example, steel stud walls start off with a better (higher) STC rating than wood stud walls. Therefore, a smaller gain from A/B solutions to a steel stud wall versus the gains to a wood stud wall does not by default indicate the wood stud wall is the best option. Naturally, one would tend to lean toward the highest STC solution after all sound proofing methods were applied.

No matter what you do, at sufficient volumes inside the room you're likely to still be able to hear it at some level outside the room. However, using any of the methods we've discussed will reduce the 'outside' volume to some extent. 




> In the long run. The more you double up the smaller the benefit. Ans still the LFE performance is very poor.


Depending on your definition of 'poor', true. It's the nature of low frequency sound. Containment is a challenge, for sure.




> Theoretically I think a STC improvement of 20 is possible with the 2 3/8" construction.


Agreed. 




> The reason for going double stud at the back wall is that it creates enough space/wall thickness to create a double door entry. I could still add clips and channels on top of that, but I assume that the performance of the room will be determined by the weakest link, which probably isn't going to be the back wall.


That's a good thing (double door). If I was not clear previously, you do not want a clip & channel setup on a double stud wall. You'd create another air gap (triple leaf effect). It's an either-or proposition (double stud or clips). Statistically, double stud walls outperform clips and channel. It's just more common to see all walls clips or all walls double stud, which is why I asked.


----------



## Primare Knob

https://www.fhwa.dot.gov/Environmen...g/federal_approach/audible_landscape/al04.cfm

I found some information and STC ratings for brick walls in here. And other information about reductions in your sound proofing. I haven't read through all of it, so I can't tell how well it can be trusted

Brick Wall 4” 101.6mm STC40
Brick Wall 9” 228.6mm STC 52
Brick Wall 12” 304.8mm STC 54
Brick Wall 4” Double 203.2mm STC 53 (4" cavity?)



· Increase the spacing between studs. 
In a single stud wall, 24 inch (609.6mm) stud spacing gives a 2-5 dB increase in STC over the common 16 (406.4mm) inch spacing.4





· Increase the width of the airspace. 
A three inch airspace provides significant noise reduction, but increasing the spacing to six inches can reduce noise levels by an additional 5 dBA. Extremely wide air spaces are difficult to design


· Seal cracks and edges. 
If the sound insulation of a high performance wall is ever to be realized, the wall must be well sealed at the perimeter. Small holes and cracks can be devastating to the insulation of a wall. A one-inch square hole or a 1/16 inch crack 16 inches long will reduce a 50 STC wall to 40.4





Windows Sound enters a building through its acoustically weakest points, and windows are one of the weakest parts of a wall. An open or weak window will severely negate the effect of a very strong wall. Whenever windows are going to be a part of the building design, they should be given acoustical consideration. Figure 4.14 illustrates the effects of windows on the sound transmission of walls. For example, if a wall with an STC rating of 45 contains a window with an STC rating of 26 covering only 20% of its area, the overall STC of the composite partition will be 33, a reduction of 12 dB.

5mm glass STC 25dB
However, a double glass acoustical window consisting of two 3/16 inch (4.8mm) thick panes separated by an airspace will have an STC of 51 In general the airspace between the panes should not be less than 2-4 inches if an STC above 40 is desired


----------



## HT Geek

Primare Knob said:


> https://www.fhwa.dot.gov/Environmen...g/federal_approach/audible_landscape/al04.cfm
> 
> I found some information and STC ratings for brick walls in here. And other information about reductions in your sound proofing. I haven't read through all of it, so I can't tell how well it can be trusted
> 
> Brick Wall 4” 101.6mm STC40
> Brick Wall 9” 228.6mm STC 52
> Brick Wall 12” 304.8mm STC 54
> Brick Wall 4” Double 203.2mm STC 53 (4" cavity?)


The other info you pasted makes sense. The issue w/the info above is there will be variations in STC based on how exactly a given wall was constructed. Though these figures at least do provide a starting point or educated guess on STC for an existing wall where the nuances of its construction are likely unknown.

It's easier to find data on concrete. There's not much info on brick walls and acoustics. While both bricks and concrete come in different variations and formulas, bricks seem (to me at least) a little trickier to identify what they're made of (e.g. clay, concrete, lime, sand). OTOH, it may not make any (or hardly any) difference relative to STC. At least you've found some ballpark figures. 

This might also be useful to you, FWIW:










Source: 
_Sound Transmission Class Ratings for Concrete Masonry Walls_. Document ID: TEK 13-1C. National Concrete Masonry Association. Herndon, Virginia (2012). Retrieved from http://www.ncma-br.org/pdfs/5/TEK 13-01C.pdf on 05.17.2017.


----------



## GatorBlues

We have a large cavity between the floor of the first level and the "room within a room" ceiling in the basement. For soundproofing, is it better to put one layer of insulation, with a large air gap, or fill the entire space with insulation from ceiling to floor above?


----------



## HT Geek

GatorBlues said:


> We have a large cavity between the floor of the first level and the "room within a room" ceiling in the basement. For soundproofing, is it better to put one layer of insulation, with a large air gap, or fill the entire space with insulation from ceiling to floor above?


I would fill the entire space (or as much as is reasonable) with insulation. As long as you don't pack it in / force it in, the insulation will have the effect of a larger air space on sound waves. There's no downside to using it. You'll only improve the results.


----------



## doveman

HT Geek said:


> That won't work, but this will: RIM for Concrete Floated Floors
> 
> It's available in 25mm sized increments from 25-100mm.
> 
> Your suggestion above would crush the insulation beneath, creating several problems (including facilitating sound transmission, which you don't want). Normally in a room-within-a-room configuration, a floating floor has a rigid layer on top of the structural sub-floor, then a damping layer (e.g. rubber mat), then another rigid layer or two. The raised floor is detached from the structural walls (small gap), and the inner room is built on top of the floating floor. The floating layers are screwed together (so that underlying layers don't move), but the screws do not penetrate into the structural sub-floor or floor joists.
> 
> Going a step further would require U-boats or a similar product. For example, in a typical floor joist setting, one could remove the sub-floor and attach the U-boats to the top of the floor joists, then replace the sub-floor (except this time around it would be floating). Then add more layers as desired.


Thanks, I wasn't sure exactly how "rigid" that insulation is and was concerned about the insulation being crushed. I'll have to get a price for that RIM, that might be a good choice. Whether I use that or the polystyrene board, the concrete slab will still need to be level (I think 5mm deviation over 3m is acceptable) so that might add to the work needed.


----------



## Primare Knob

HT Geek said:


> The other info you pasted makes sense. The issue w/the info above is there will be variations in STC based on how exactly a given wall was constructed. Though these figures at least do provide a starting point or educated guess on STC for an existing wall where the nuances of its construction are likely unknown.
> 
> It's easier to find data on concrete. There's not much info on brick walls and acoustics. While both bricks and concrete come in different variations and formulas, bricks seem (to me at least) a little trickier to identify what they're made of (e.g. clay, concrete, lime, sand). OTOH, it may not make any (or hardly any) difference relative to STC. At least you've found some ballpark figures.
> 
> This might also be useful to you, FWIW:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Source:
> _Sound Transmission Class Ratings for Concrete Masonry Walls_. Document ID: TEK 13-1C. National Concrete Masonry Association. Herndon, Virginia (2012). Retrieved from http://www.ncma-br.org/pdfs/5/TEK 13-01C.pdf on 05.17.2017.


 I have weighted a brick, which was 3.9kg, effectively totaling a 2251kg/m3. 
A single 4” wall will give me an STC of 48, a double 4” (8”) wall will give me an STC of 57, a double 4” wall with a 3” cavity will give me an STC of high 50’s as well.

It looks like I will be able to reach an STC of 70+ with the room I have in mind.

Ceiling:
Double 5/8” drywall with Green Glue glued to the top of the ceiling, Insulation, Channels and clips , Double 5/8” drywall with Green Glue (STC76)
Back Wall:
Double 5/8” drywall with Green Glue, Double stud with min 1” cavity, Insulation, Double 5/8” drywall with Green Glue. (STC73)
Brick walls:
Double 5/8” drywall with Green Glue, Channels and Clips, High Density Insulation, water proofing membrane. (STC70+)
Floor:
Water proofing membrane and???

I thought that I came across a triple layer 5/8” drywall with Green Glue as well, but I can’t seem to find it anymore.


----------



## Primare Knob

Questions

Insulation:
Looking at the double stud and specially the ceiling construction they leave air cavities open instead of filling them up with insulation. Is this the best approach?

Is a higher density insulation always better, or does it differ per situation?

Is there a difference between Polyester vs Rock Wool?

Floor:
What is the impact of the floor in all of this? There doesn’t seem too much going on. Reading through this thread I came across a couple of options but it doesn’t seem to have a great deal of impact.

I am planning on a floating floor on a 9mm rubber underlay on top of my concrete slap which I will water proof first.

Framing:
When I understand it correctly, the spacing of the studs, and I assume channels as well, also have an impact on the sound proofing?

Window Cover:
I do have a single glazed window in an aluminum frame in my front wall which I plan to cover. I plan to build a frame 185mm (7,2”) deep, that will fit inside the window cavity. I am thinking to construct the frame out of a double layer of plywood with Green Glue in between, cover the front with 2 or 3 layers of 5/8” dry wall with Green Glue and fill the inside up with Insulation.

But the frame will jam up against the aluminum window frame creating a 20mm (0,78”) gap between the end of the frame and the glass panel. Do I leave the back of the window cover open to prevent a triple leaf effect, or would it be better to close it up with 2 or 3 layers of 5/8” dry wall with Green Glue?

Doors:
I am planning with 120mm (4,72”) deep doors. But the deeper the door, the wider the door frame needs to be, leaving more chance of sound to escape. What kind of (doulbe) seal can be used. Are there any “double stud” door constructions possible here?

I am planning for a double door system. 1 HT door and a triple glazed external door, 1HT door and a common semi solid internal entry door. I am thinking about a floor jam where the doors will but up against, which might also leave some room to raise the floor inside the HT


----------



## HT Geek

*What is NRC?*



HT Geek said:


> The higher the number, the more sound is absorbed by the insulation at a given frequency range. NRC is an aggregate value, similar to STC. NRC and STC are useful when comparing different strategies. Higher numbers mean better overall performance. However, what they don't tell you (and what the other figures are good for) is how a given solution performs at say low/medium/high frequencies, or specific frequencies.


 @Primare Knob, I realized I didn't explain that ^^^ very well. Let me try again. Aside from briefly discussing STC, IIC, and NRC, I want to explain why you cannot always take these figures at face value. They're often used as headline numbers in marketing materials. However, just like the news these days, if you want the *real* story on material sound absorption, you need to dig beyond the headlines.


*STC and IIC*

STC and IIC are aggregate lab test measurements. They're what I would call, 'headline' figures; back-of-the-envelope, quick and dirty comparisons of one material versus another to absorb sound across a range of frequencies (thus why I previously described them as aggregate values). They're not good at telling you Material A will be better/worse than Material B at absorbing airborne sound at 500hz. For that granularity, you need to dig into the TL (Transmission Loss) for the 500hz frequency and see what you've got. A lower STC rated product may outperform a higher STC in that particular frequency (for example).

There's also F-STC and F-IIC, which are used when the same tests are performed, but in the field vs. a lab (i.e., "Field-STC"). You can think of F-STC and F-IIC as "real world" measurements, but they're not as useful because you can never completely isolate performance of the material you're testing from the environment. That's fine if it's your environment, but if you are comparing material performance and it's not your environment, then it's less useful. STC and IIC are "better" in the sense they are more objective and thus more useful when making comparisons. Apples to apples if you will.


*NRC*

NRC is a bit different animal. Us human beings - especially here in the USA - always seem to be looking for simple explanations to complex questions. And what we always end up with are incomplete answers. Many people extrapolate narrow conclusions into broad conclusions, which they shouldn't. NRC is often in this category. 

What I'm about to describe could be much more detail than you want right now, but hopefully this will be helpful for you or someone else in the future. Before I delve in, here's the TLDR version: 


If you see NRC >1 it means the edges of the test material were included in the lab test
If your use case will not expose the material's edges, consider looking for other lab tests of the same material that mimic your use case
You can't truly compare NRC values of different materials unless you know they were lab tested with the same mounting method


*What is NRC?*

NRC is not a measurement. It is a _calculation_, based on Sabins (invented by Mr. Sabine) - which are the actual measurement of sound absorption used in audio lab tests. Sabins are the representation of a formula as well (there's an imperial formula and a metric formula). Point is that labs measure sound absorption in sabins. That value is then converted to an NRC or *Noise Reduction Coefficient*. This is why in tables for NRC's you'll often see them referred to as coefficient tables or values.

So, why don't we all simply compare sound absorption values of materials by sabins and call it a day? Well, now we're back to what I said about making complex things simple and how us humans are always trying to do that! NRC is a standardized coefficient. It takes into consideration the size of the test material. This makes a lot of sense, because quite frankly we can't really compare sabins of one test to another. If you tested 100 square feet of 1" thick Material X for sound absorption, and then tested 10 square feet of 1" thick Material X, you'd likely get two different sabin values. So, comparing just their sabins would give you a false conclusion as to which material was better. So, NRC factors in the _area_ of each material and distills it down to a ratio from 0 to 1, where 0 = 0% absorption (100% dispersion/absorbs nothing) and 1 = 100% absorption (no reverberations).

Now, that said have you noticed the reported absorption values of some materials are >1? How is that possible? You can't have >100% absorption, right? Of course you can't. So, that doesn't make sense, does it? Quite frankly, no it doesn't. Not at face value. However, recall that NRC is a _calculation_, and NOT a _measurement_. Therefore, we are not measuring >100% absorption, but we are calculating >100% absorption based on the measurement of sabins relative to the area of the object. That still sounds like it doesn't make any sense, eh? How is this possible? What kind of stupid formula is NRC then???

The answer - as usual - the devil is in the details. In this case, the lab tests. It is possible to get >100% absorption expressed as NRC. Here's how:


Proper lab sound absorption tests use ASTM C423 and ASTM E795
The ASTM E795 standard specifies various specimen mounting options (16 possible variations, I believe)
Only one mounting option is utilized per test
The test mounting method is *supposed to* represent real-world use of the product, but the entity paying for the test dictates what that means (after all, it's their product and their $ spent)
Some mounting options expose the edges of a test material as part of the test and some obscure it
When the edges are included, it effectively increases the surface area of the material

Let's go back to my example of Material X with 100 square feet of surface exposed to a lab test. If the chosen mounting method prescribes that the edges are excluded from the test, then you'll get a Sabine reading based on only 100 square feet. You run your tests, record the Sabins, and calculate the NRC. Now, take the same test but include the edges of the material. Now you have >100 square feet of material, but the lab testing procedure and ASTM C423 to not take that into consideration. 

So, what happens in my example scenario? The 2nd test where Material X's edges are included may record a higher number of sabins (more sound absorption). Let's say for purposes of illustration we had a 50 sabins reduction in test # 1 of Material X, and dividing that by 100 square feet we get an NRC of 0.5. Then let's say a different lab conducts a test with 100 square feet of Material X, but the edges are included and the lab gets a reduction of 60 sabins, and that lab calculates the NRC as 0.6. Now you have two different lab tests of the same material reporting different results. Which one would you use if you were the material manufacturer or reseller?

I know this issue is more complicated that what I've laid out. I simply want to underscore the fact that how a product is tested is just as important as the test results, especially when comparing test results from different products. Unfortunately, it's not always possible to know when one is comparing NRC results of different materials whether or not those materials were mounted using the same ASTM E795 method. Ideally, that's what we want in order to make a clear comparison.

A simple takeaway from all this is that if you see a NRC reported that is >1, then you know immediately the test method included the edges of the material. Therefore, if your mounting method will have sound directed only at its face and the edges won't be in a position to absorb anything (e.g. lining your front or rear wall with absorptive material, where the edges are backed into room corners), that's s warning sign and you may wish to dig deeper into the test method used by the respective lab. You might also want to search for a different lab test that more closely emulates your particular use-case scenario, if one exists.


----------



## HT Geek

Primare Knob said:


> Floor:
> Water proofing membrane and???


Sub-floor is concrete? (apologies, but I've forgotten and too lazy to scroll up in the thread) If so, it's personal preference. Carpet and pad works for many people. Others put down a sub-floor of plywood, rubber mat, etc. Since concrete is porous, it's worth considering any potential moisture issues before deciding on material(s) if you want a sub-floor under carpet pad.

If you want to 'feel' your bass through the floor (or if you don't want to), this may also impact your choice.




> I thought that I came across a triple layer 5/8” drywall with Green Glue as well, but I can’t seem to find it anymore.


I don't recall ever seeing a lab test with 3x drywall. I'm sure someone has estimated the STC value, but I'm not aware of what one would could expect it to be. FWIW, I have OSB + GG + 5/8" DW + GG + 5/8" DW on one wall in my room. The other side of the wall is a bedroom.


----------



## HT Geek

Primare Knob said:


> Questions
> 
> Insulation:
> Looking at the double stud and specially the ceiling construction they leave air cavities open instead of filling them up with insulation. Is this the best approach?


The area between two stud walls is normally left open (air gap). If you stuff insulation there, it has the potential to connect the two walls. Normally, you'd use insulation in both walls but you would use a depth that matched each wall's stud depth. So, for instance in a double stud wall where both wall studs are 2x4's, you'd use R11 (3" thick) or R13 (3.5") fiberglass insulation in each stud wall. That would leave your walls completely disconnected from one another.




> Is a higher density insulation always better, or does it differ per situation?


It differs. Generally speaking, the best value is loose fiberglass (i.e., "pink fluffy"). Some people use rockwool as it has slightly better sound absorption and is minimally more costly compared to other alternatives. Some people also find rockwool easier to work with and use it for that reason. 

When it comes to insulation used for sound absorption inside the room, that is when other products are typically viewed more favorably.




> Is there a difference between Polyester vs Rock Wool?


Yes, they're different. Rockwool/Rock wool is made (literally) from rock fibers woven with other materials and chemicals. It is sometimes referred to as mineral wool.




> Floor:
> What is the impact of the floor in all of this? There doesn’t seem too much going on. Reading through this thread I came across a couple of options but it doesn’t seem to have a great deal of impact.


Not normally, no. My thoughts are it matters under two circumstances:

Living space below
One desires reducing reverberations (typically LFE) in the floor to one's seat

On a concrete floor, If you have a lot of bass and want to feel the airborne sound and not the reverberations through the floor, you'd want to focus on the floor. Otherwise, carpet and pad is sufficient for most people. Just don't use a (sound) reflective floor such as hardwood or tile!




> I am planning on a floating floor on a 9mm rubber underlay on top of my concrete slap which I will water proof first.


That's a good approach IMHO. Personal preference.




> Framing:
> When I understand it correctly, the spacing of the studs, and I assume channels as well, also have an impact on the sound proofing?


Yes. Studs you want spaced apart as far as you can - typically 24" O.C. in the U.S. (will be less if local building codes limit you).

Channels need to be spaced per the manufacturer's instructions and based on how much weight they will support, but otherwise the same principle applies (fewer = better as there are fewer points of contact with the structure).




> Window Cover:
> I do have a single glazed window in an aluminum frame in my front wall which I plan to cover. I plan to build a frame 185mm (7,2”) deep, that will fit inside the window cavity. I am thinking to construct the frame out of a double layer of plywood with Green Glue in between, cover the front with 2 or 3 layers of 5/8” dry wall with Green Glue and fill the inside up with Insulation.


That will be a bad-ass window plug!




> But the frame will jam up against the aluminum window frame creating a 20mm (0,78”) gap between the end of the frame and the glass panel. Do I leave the back of the window cover open to prevent a triple leaf effect, or would it be better to close it up with 2 or 3 layers of 5/8” dry wall with Green Glue?


I'd suggest you leave it as is and not worry about it. I can't imagine it would be an issue given the thickness of your window plug. I would also think a small air gap is probably a good idea.




> Doors:
> I am planning with 120mm (4,72”) deep doors. But the deeper the door, the wider the door frame needs to be, leaving more chance of sound to escape. What kind of (doulbe) seal can be used. Are there any “double stud” door constructions possible here?


That's a very thick door (good). You'll have a double-stud door configuration by virtue of the double stud wall. It's not a big deal. No matter what you do, your door is going to be an unavoidable weak spot. If you search on the forum, you'll find some construction threads that detail options for the door frame. I've seen 1 or 2 with " T " designs that attempt to isolate the door frame somewhat, but most people accept the limitation of attaching the door frame directly to both walls. From a fire code perspective, you cannot have a gap. Another good alternative I've seen is to create a gap and fill it with a rubber or neoprene seal.




> I am planning for a double door system. 1 HT door and a triple glazed external door, 1HT door and a common semi solid internal entry door. I am thinking about a floor jam where the doors will but up against, which might also leave some room to raise the floor inside the HT


A double door configuration will allow you to isolate the door frames from one another / solves the previous issue. Ideally, you want a minimum of 2 feet of air space between the doors; preferably 3 feet/1 meter or more. If you have the space, it's a great opportunity to get creative.


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## doveman

I got a quote for that Kinetics RIM and it £1306.62+VAT for 12m2 (6 * 2.4mx1.2m sheets at £217.77 each), so that's out of the question!

So I'm not sure what to do with the floor. I'm not sure my idea, as shown in the attached sketch, of having the conduit contained in wooden blocks at the perimeter would be sensible anyway. With only a fairly thin layer of rubber between the wooden blocks and the OSB, I would think this would be a weak point from a soundproofing point of view, so even though the rest of the floor has 25mm of rigid insulation or whatever between the OSB and the concrete slab, the sound would travel via the less insulated areas where the wooden blocks are.

Apart from that, each conduit is about 20mm in diameter and there's 2 or 3 on each side of the room, so the wooden blocks would have to be 40-60mm wide (if they floor was deeper they could be stacked so that the wooden block was 60-70mm high and only 20mm wide but my subfloor is only about 55mm high.

I might just replace the floorboards with OSB and maybe replace the existing joists with wider ones so that I don't have to fit noggins to the current quite narrow ones, in order to have room to screw down two adjacent OSB boards. I asked the cork tiles company if they have any data on the difference in terms of sound insulation from using their 6mm tiles instead of their 4.7mm ones but they don't seem to have any. In their reply they just suggested that I use their 2mm cork underlay which they say provides 16db noise reduction if I'm concerned about sound insulation. It looks like they can supply it up to 6mm thick but how much difference that would make I don't know http://www.siestacorktiles.co.uk/product/rubber-cork-acoustic-underlay/ and I could put that on the subfloor underneath the 6mm ply I'll lay to stick the tiles to. Or maybe if I'm replacing the joists I could lay the underlay directly on the concrete slab underneath the new joists but I'm not sure whether that would be better.

For their "Ambiente" range it says they reduce sound by 13db http://www.siestacorktiles.co.uk/coloured-cork-flooring/ so would that mean that if I used the underlay as well I'd achieve 29db reduction?

Some of their tiles are specified as "Heavy density (500 kgs.cu.mt.)" so I'm curious as to what density the normal tiles are and whether that makes any difference in terms of sound insulation.

I also got a quote for the IsoMax clips and they're £5.06 each or £4.66 for 501+. The channel is £4.06, £3.55 for 51+ and £3.24 for 81+ but I guess I don't have to buy their channel and can get it cheaper elsewhere.

I can get the Genie clips for £3.28 each, so I might use those or I'll see if I can import the IB-1 clips.

EDIT: If I do replace the floorboards and joists, it might also be a good idea to seal the concrete slab as it doesn't have a plaster layer sealing it like the walls do and I'll replace the old, quite flattened insulation with some new pink fluffy or rockwool whilst I'm at it.


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## sigma722

GatorBlues said:


> I wish it were so. My understanding of the six foot rule where we are building is an outlet every 6 feet, so that you can reach one within 3 feet anywhere along the wall. Hopefully I'm wrong about that, but given the spacing of the outlets installed already in the rest of the house, I unfortunately think I'm correct.


Did you ever confirm if it's actually what you said? I've never heard the code be that way and agree that anywhere I've seen it, the 6ft rule means you are always within 6ft from an outlet at any point along the wall, so 12 ft between each outlet.

For my outlets in my room, I am building them all into my riser and stage. As long as you are within 18" of your wall it should qualify for the outlet rule, but you might have to refer to the code for that too if you have different rules.


----------



## Ladeback

sigma722 said:


> Did you ever confirm if it's actually what you said? I've never heard the code be that way and agree that anywhere I've seen it, the 6ft rule means you are always within 6ft from an outlet at any point along the wall, so 12 ft between each outlet.
> 
> For my outlets in my room, I am building them all into my riser and stage. As long as you are within 18" of your wall it should qualify for the outlet rule, but you might have to refer to the code for that too if you have different rules.


Having one every 12" is what I found to be so that there is one every 6" for an extension card on a lamp or something else. I don't think it is a code per say, just a good rule of thumb to fallow. I am trying to do 10' to 12' in my theater/basement build.


----------



## Primare Knob

HT Geek said:


> @Primare Knob, I realized I didn't explain that ^^^ very well. Let me try again. Aside from briefly discussing STC, IIC, and NRC, I want to explain why you cannot always take these figures at face value. They're often used as headline numbers in marketing materials. However, just like the news these days, if you want the *real* story on material sound absorption, you need to dig beyond the headlines.
> 
> 
> *STC and IIC*
> 
> STC and IIC are aggregate lab test measurements. They're what I would call, 'headline' figures; back-of-the-envelope, quick and dirty comparisons of one material versus another to absorb sound across a range of frequencies (thus why I previously described them as aggregate values). They're not good at telling you Material A will be better/worse than Material B at absorbing airborne sound at 500hz. For that granularity, you need to dig into the TL (Transmission Loss) for the 500hz frequency and see what you've got. A lower STC rated product may outperform a higher STC in that particular frequency (for example).
> 
> There's also F-STC and F-IIC, which are used when the same tests are performed, but in the field vs. a lab (i.e., "Field-STC"). You can think of F-STC and F-IIC as "real world" measurements, but they're not as useful because you can never completely isolate performance of the material you're testing from the environment. That's fine if it's your environment, but if you are comparing material performance and it's not your environment, then it's less useful. STC and IIC are "better" in the sense they are more objective and thus more useful when making comparisons. Apples to apples if you will.
> 
> 
> *NRC*
> 
> NRC is a bit different animal. Us human beings - especially here in the USA - always seem to be looking for simple explanations to complex questions. And what we always end up with are incomplete answers. Many people extrapolate narrow conclusions into broad conclusions, which they shouldn't. NRC is often in this category.
> 
> What I'm about to describe could be much more detail than you want right now, but hopefully this will be helpful for you or someone else in the future. Before I delve in, here's the TLDR version:
> 
> 
> If you see NRC >1 it means the edges of the test material were included in the lab test
> If your use case will not expose the material's edges, consider looking for other lab tests of the same material that mimic your use case
> You can't truly compare NRC values of different materials unless you know they were lab tested with the same mounting method
> 
> 
> *What is NRC?*
> 
> NRC is not a measurement. It is a _calculation_, based on Sabins (invented by Mr. Sabine) - which are the actual measurement of sound absorption used in audio lab tests. Sabins are the representation of a formula as well (there's an imperial formula and a metric formula). Point is that labs measure sound absorption in sabins. That value is then converted to an NRC or *Noise Reduction Coefficient*. This is why in tables for NRC's you'll often see them referred to as coefficient tables or values.
> 
> So, why don't we all simply compare sound absorption values of materials by sabins and call it a day? Well, now we're back to what I said about making complex things simple and how us humans are always trying to do that! NRC is a standardized coefficient. It takes into consideration the size of the test material. This makes a lot of sense, because quite frankly we can't really compare sabins of one test to another. If you tested 100 square feet of 1" thick Material X for sound absorption, and then tested 10 square feet of 1" thick Material X, you'd likely get two different sabin values. So, comparing just their sabins would give you a false conclusion as to which material was better. So, NRC factors in the _area_ of each material and distills it down to a ratio from 0 to 1, where 0 = 0% absorption (100% dispersion/absorbs nothing) and 1 = 100% absorption (no reverberations).
> 
> Now, that said have you noticed the reported absorption values of some materials are >1? How is that possible? You can't have >100% absorption, right? Of course you can't. So, that doesn't make sense, does it? Quite frankly, no it doesn't. Not at face value. However, recall that NRC is a _calculation_, and NOT a _measurement_. Therefore, we are not measuring >100% absorption, but we are calculating >100% absorption based on the measurement of sabins relative to the area of the object. That still sounds like it doesn't make any sense, eh? How is this possible? What kind of stupid formula is NRC then???
> 
> The answer - as usual - the devil is in the details. In this case, the lab tests. It is possible to get >100% absorption expressed as NRC. Here's how:
> 
> 
> Proper lab sound absorption tests use ASTM C423 and ASTM E795
> The ASTM E795 standard specifies various specimen mounting options (16 possible variations, I believe)
> Only one mounting option is utilized per test
> The test mounting method is *supposed to* represent real-world use of the product, but the entity paying for the test dictates what that means (after all, it's their product and their $ spent)
> Some mounting options expose the edges of a test material as part of the test and some obscure it
> When the edges are included, it effectively increases the surface area of the material
> 
> Let's go back to my example of Material X with 100 square feet of surface exposed to a lab test. If the chosen mounting method prescribes that the edges are excluded from the test, then you'll get a Sabine reading based on only 100 square feet. You run your tests, record the Sabins, and calculate the NRC. Now, take the same test but include the edges of the material. Now you have >100 square feet of material, but the lab testing procedure and ASTM C423 to not take that into consideration.
> 
> So, what happens in my example scenario? The 2nd test where Material X's edges are included may record a higher number of sabins (more sound absorption). Let's say for purposes of illustration we had a 50 sabins reduction in test # 1 of Material X, and dividing that by 100 square feet we get an NRC of 0.5. Then let's say a different lab conducts a test with 100 square feet of Material X, but the edges are included and the lab gets a reduction of 60 sabins, and that lab calculates the NRC as 0.6. Now you have two different lab tests of the same material reporting different results. Which one would you use if you were the material manufacturer or reseller?
> 
> I know this issue is more complicated that what I've laid out. I simply want to underscore the fact that how a product is tested is just as important as the test results, especially when comparing test results from different products. Unfortunately, it's not always possible to know when one is comparing NRC results of different materials whether or not those materials were mounted using the same ASTM E795 method. Ideally, that's what we want in order to make a clear comparison.
> 
> A simple takeaway from all this is that if you see a NRC reported that is >1, then you know immediately the test method included the edges of the material. Therefore, if your mounting method will have sound directed only at its face and the edges won't be in a position to absorb anything (e.g. lining your front or rear wall with absorptive material, where the edges are backed into room corners), that's s warning sign and you may wish to dig deeper into the test method used by the respective lab. You might also want to search for a different lab test that more closely emulates your particular use-case scenario, if one exists.


I still have to take a closer look into this when I have more time, but this came to mind today.

When using 70mm studs instead of 90mm studs it will give a 40mm bigger gap between the two studs, which suggest it would perform better. 

When still using 90mm insulation but leave a minimum of 1" between the battens, with 70mm studs it will give a 65mm gap between the studs, but insulation that is sticking out of the internal cavity.

Would this perform any better or worse?

I have started reading through a Canadian document with a large variety of tests conducted, where it seems that more thickness in insulation performs better and that the air velocity inside the battens is the thing to watch for.

Not sure if that is what you are trying to point out. I understand the limits of STC. In general the high frequencies are easy, the mid frequencies is where sound proofing is creating the biggest advantage, and the low frequencies are just an illusion that you can contain them unless you have a very big wallet.

There are things that can be done, but it mostly involve giving up a lot of real estate or using heavy inert materials. It seems for the common man it is best to try to contain them at the source, meaning speaker and floor.

Forgive me if I am looking at it wrong, I don't really know with what angle you posted this.


----------



## HT Geek

Primare Knob said:


> Forgive me if I am looking at it wrong, I don't really know with what angle you posted this.


LoL 

I was trying to bring attention to two facts:

1) STC and similar values are aggregate, and therefore they don't tell the complete story. The real focus is (IMHO) on TL (Transmission Loss) of various materials at various frequencies; and
2) NRC has issues as well; namely, the most common test method ("Type A") produces somewhat misleading results in many if not all tests. The issue is in that test form, presuming the test sample size is less area than the test room (and I have yet to read of a case where it wasn't), the sides of the material affect the ability of that material to absorb sound (i.e. they contribute to sound absorption). This creates two problems. First, one can attain a result >100% of sound absorption (>1.00 NRC), which is obviously physically impossible. This is due to the way NRC is calculated. And second, that test methodology ("Type A") doesn't lend itself well for comparative purposes if your application will use the given material in a two-dimensional role versus three-dimensional (for example on a front or rear wall).

So, if for instance you're comparing or researching materials with reported NRC ratings, it's important to note that NRC tests should be viewed with a bit of scrutiny with regards to purported results. It's not necessarily a nefarious effort on the part of a manufacturer. 

As an example, let's say you want to know the best material for sound proofing your rear wall with regards to bass frequencies below 500 hz. Unfortunately, just looking at STC or NRC won't give you an accurate picture of a potential material's effectiveness for your particular needs.




> When using 70mm studs instead of 90mm studs it will give a 40mm bigger gap between the two studs, which suggest it would perform better.


I'm not following how the use of thicker studs equates to a larger air gap between studs. 




> When still using 90mm insulation but leave a minimum of 1" between the battens, with 70mm studs it will give a 65mm gap between the studs, but insulation that is sticking out of the internal cavity.
> 
> Would this perform any better or worse?


Insulation sticking out of the cavity is not an issue. The value of the air gap lies (for the most part) in de-coupling, and therefore the point is to have an air gap (period) versus using insulation matching the width of your studs. Incidentally, the value or purpose of the insulation is to slow down the velocity of sound travelling through the cavity. The insulation effectively causes the space between membranes to behave as if it were larger than it actually is (by virtue of the insulation material slowing down the speed of the sound waves via friction).

Theoretically, slightly more insulation will improve your high to mid range frequency absorption, but is likely to have little to no comparable effect versus LFE absorption (because the latter requires substantial amounts of air and/or insulation to create a measurable difference in performance that is worth noting). Put another way, thicker insulation batts may be a benefit... or it may not be... but it won't be a detriment.


----------



## HT Geek

Ladeback said:


> Having one every 12" is what I found to be ... I don't think it is a code per say, just a good rule of thumb to fallow. I am trying to do 10' to 12' in my theater/basement build.


It is code (International Building Code or IRBC / IRC / IBC ... take your pick of abbreviations, lol). It's specified in NFPA 70 (NEC - National Electrical Code). I've poured over even the 2017 (pending) NEC update and the 6' rule is still there. It equates to an effective maximum distance of 12' between outlets. The 6' criteria should be thought of as a radius.

A local jurisdiction could enact a rule that is more stringent. Typically, local and state jurisdictions cite a given IRC version (by year), and the given IRC cites a given (year) NFPA 70 or NEC version.


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## HT Geek

Primare Knob said:


> When still using 90mm insulation but leave a minimum of 1" between the battens, with 70mm studs it will give a 65mm gap between the studs, but insulation that is sticking out of the internal cavity.
> 
> Would this perform any better or worse?


Thought perhaps I ought to clarify further on the air gap. Unless you are going to have a REALLY BIG air gap (e.g. 1 meter or more), then the size of the air gap doesn't matter as you won't gain anything between say a 1" gap and a 3" gap, or a 1/4" gap for that matter. One inch is often touted as a standard to shoot for simply because it (generally) leaves sufficient space to account for imperfectly plumb walls and ceilings.


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## deewan

I have a question regarding soundproofing theater underground walls in a basement. I've tried to search for some information but I'm not having much luck regarding this specific application.

If a theater room has 3 concrete basement walls that are underground and a fourth single wall that is shared with the rest of the basement, how much soundproofing effort needs to go to the 3 underground walls? Here is my example: The north, west, and south wall of a theater are all concrete exterior walls of a basement. The east wall of the theater is adjacent to the basement living room. Above the theater is the master bedroom and master bathroom. The plan for the east wall is 5/8 double drywall with green glue on the living room side and IB-1 clips, hat channel, OSB, green glue and a single layer of 5/8 drywall on the theater side (see example 1 below). The ceiling of the theater will be treated with green glue and 5/8 drywall to the underside of the subfloor and IB-1 clips, hat channel, 5/8 drywall, green glue and 5/8 drywall (see example 2 below). Those are the surfaces I don't want sound to transmit through. 

I was curious if I need to take similar steps to prevent the three underground walls from allowing sound to leak into the walls of the house. All HVAC and electrical work will be treated properly. The exterior walls already have blown-in insulation and any empty space (between floor joists, etc) will be stuffed with insulation. But those walls are not decoupled from the floor joists above. If one would simply put drywall up on those three 'exterior' walls would they lose all the other soundproofing preventive steps? Thanks in advance for your input!

*EXAMPLE 1:*









*EXAMPLE 2:*


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## HT Geek

deewan said:


> If a theater room has 3 concrete basement walls that are underground and a fourth single wall that is shared with the rest of the basement, how much soundproofing effort needs to go to the 3 underground walls? Here is my example: The north, west, and south wall of a theater are all concrete exterior walls of a basement. The east wall of the theater is adjacent to the basement living room. Above the theater is the master bedroom and master bathroom. The plan for the east wall is 5/8 double drywall with green glue on the living room side and IB-1 clips, hat channel, OSB, green glue and a single layer of 5/8 drywall on the theater side (see example 1 below). The ceiling of the theater will be treated with green glue and 5/8 drywall to the underside of the subfloor and IB-1 clips, hat channel, 5/8 drywall, green glue and 5/8 drywall (see example 2 below). Those are the surfaces I don't want sound to transmit through.


Sounds like you're on the right path. You've identified the critical sound proofing areas (shared wall, shared ceiling/floor above).

Your concrete walls will transmit some sound and vibration to the floor joists above (you mentioned those walls are supporting the floor joists). The question is how much, and that's difficult to say. I don't believe I've ever seen a lab test that covers your particular scenario with regards to flanking noise carried by those concrete walls. The effect would be impacted by the thickness of the walls and whatever sound proofing methods you use on those walls. 

It's easier to first think about how your experience _in the room_ could be potentially affected by those concrete walls. If you do not treat them at all, they will reflect quite a bit of sound energy back into the room. Concrete is particularly good at reflecting higher frequency sounds, and with 3 concrete walls, I'm sure you'll get some awful echoes. So, something must be done about that first. After you've addressed that issue, you can decide if it will also dampen/absorb sound attempting to escape your theater well enough to be satisfied in the room(s) above. I would venture the vast majority of people would be happy with the result and not feel the need to do anything further (with your concrete walls).

Turning our attention to those walls, I would suggest - at a minimum - 1) seal the walls (a variety of sealants can be used, even drywall mud); 2) affix 2 layers of 5/8" drywall with Green Glue in between to each concrete wall. The purpose of sealing the walls first is to eliminate the tiny air gaps you'll have if you don't seal it (which will reduce the STC of the walls). If you want to go a bit further, you could use furring strips, and going even further you could build an independent stud wall (where the 2x DW layers would be attached to either the furring strips or the stud wall). If you use furring strips or studs, there's no need to seal the walls first.

Personally, I would spend the extra $100 or so in wood per wall and build studs, etc. Only reason I would not is if space were at a premium. As you've already figured out, the ceiling and shared wall in the basement should be your main concerns.


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## LoudDad

deewan said:


> I was curious if I need to take similar steps to prevent the three underground walls from allowing sound to leak into the walls of the house.


I don't recall reading any specific scientific evidence, but best practice against a basement concrete wall is still to build a stud wall leaving at least 1/2" gap away from the concrete wall and doing double drywall and GG (no need for clips). You should remove any existing insulation and vapor barrier directly attached to the concrete and put new insulation inside the new stud wall then the vapor barrier.

You also want isolation clips at the top of the stud wall to make sure you don't directly attach it to the joists. You're basically trying to make sure your entire room has no solid direct coupling to the rest of the house.

Bill.


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## deewan

Thanks for the replies @LoudDad and @HT Geek. I should have been a little more clear about the three concrete walls. The concrete walls have a standard wooden stud wall built along side with blown-in insulation and a vapor barrier. So it sounds like I may have the best plan already made?? I just wasn't sure if I needed to treat the new stud walls along side the concrete walls to prevent those walls from transmitting sound up.


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## HT Geek

deewan said:


> Thanks for the replies @LoudDad and @HT Geek. I should have been a little more clear about the three concrete walls. The concrete walls have a standard wooden stud wall built along side with blown-in insulation and a vapor barrier. So it sounds like I may have the best plan already made?? I just wasn't sure if I needed to treat the new stud walls along side the concrete walls to prevent those walls from transmitting sound up.


No, that's worse (what you have right now). Thanks for the photo, btw. That helps a lot.

So, to @LoudDad's point, what you want - ideally - is an air gap between your concrete wall and a stud wall, with insulation between the studs. The problem is you currently have the following issues:


Existing stud wall coupled to concrete walls
Existing stud wall coupled to ceiling/floor joists above
Existing studs coupled to HT room floor
Existing studs are 16" O.C.

The last two points are less significant, but I'm mentioning them as they are poignant nonetheless. The biggest issue is your existing studs being coupled to the ceiling joists/floor joists of the room(s) above.

Furthermore, that looks like a glulam in the middle of your unfinished space. In case you're not familiar with that term, it's an engineered wood beam. The term means, "glued, laminated lumber." FYI, whenever you see one of those, it is almost always a load bearing beam (and yours is for sure, as evidenced by the sistered studs supporting it in the far end of the room in your photograph).

So, now this changes things up a bit. You will need to isolate (decouple) those concrete walls. Otherwise, your efforts to decouple the ceiling and 4th wall will be for nought. You're going to need either clips & channel, staggered, or double studs all the way around.

Another note: I see there's also a vapor barrier up on the existing stud walls abutting the concrete walls. Personally, I would not mess with that and leave it as-is. That rules out a staggered stud interior wall on those sections.

I'd say your best bet is likely a double stud wall all around, including independent ceiling joists. A potential issue is if the ceiling height is too low after bringing it down below the height of that glulam. You could also use clips & channel all the way around, which would take up less real estate (to implement).


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## LoudDad

deewan said:


> Thanks for the replies @LoudDad and @HT Geek. I should have been a little more clear about the three concrete walls. The concrete walls have a standard wooden stud wall built along side with blown-in insulation and a vapor barrier. So it sounds like I may have the best plan already made?? I just wasn't sure if I needed to treat the new stud walls along side the concrete walls to prevent those walls from transmitting sound up.


So if your theater is gonna be ending where that beam is (as HT Geek mentioned will be a problem) then what I would do is leave your existing structure and add clips and channel and Double drywall with green glue to those walls.
If the beam will be inside the theater you will either need to drop your entire ceiling if you have enough height or drop a soffit around it.

Bill


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## Primare Knob

Hi guys,

I am in a bit of a hurry since the builder started way earlier than expected. I have postponed the build of the room until I have a better understanding, but there is one thing that I need to take care of now.

The theater room is sitting next to the toilet area, which is sitting next to the laundry, which is sitting next to the garage. The rough idea is to run duct work from the theater room into the garage through the ceiling of the toilet and laundry either HVAC or fan powered.

I can fit in an 8" duct since the ceiling cavity will be 8" , but on this short notice I can only find the 6" non insulated duct's.
How would I insulate these duct pipes? Do I wrap the pipe in insulation or can I insulate the whole ceiling cavity around the ducts?

Should I also use a double layer of plasterboard on the ceiling in the toilet and laundry for better sound proofing?

I am planning on placing the fans or HVAC connected to these ducts on the end, inside the garage.
(These ducts will be placed inside a double stud wall and a floating (clips) ceiling in the end)

Thanks for all your help. Much appreciated.


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## doveman

I'm still undecided how to do the floor. Apart from the fact that U-boats don't seem very good, I don't think any contractor would be prepared to leave boards floating on them and would insist on screwing through the boards and the U-boats into the joists. If I could find these square pucks the chap used in an article I read, where he screwed the centre hole of the puck to the joists and the subfloor to the outer holes, that might be OK. The other option might be to lay 2mm rubber cork underlay like this http://www.siestacorktiles.co.uk/product/rubber-cork-acoustic-underlay/ on the OSB before I lay the 6mm ply that I'll stick the cork tiles to but then I guess I can't screw the ply to the OSB and I'd worry that the ply and cork might lift up.

As I'll need to add noggins to the joists where the sections of OSB meet, it might be easier just to replace some of the joists with wider ones but I haven't costed that yet.

I'm wondering what to do at the perimeter where the living room meets the hall and kitchen. I was thinking maybe I could have two joists with a small gap between them, so the living room board sits on one, the hall/kitchen board on the other and then fill the gap with mastic. As shown in the attached picture, the gap between the OSB boards could be wider than the gap between the joists so that some of the mastic is supported on the joists but maybe that's unnecessary and the gap can be the same between the joists and between the boards. I'm not sure whether it will be best to fill the gap between the joists with mastic as well or leave it as an air gap. I'm worried that if I leave it, bits of wood, etc. might get in there and bridge the gap. I don't think either of the gaps need to be very big to be effective, maybe 1mm between the joists and 3mm between the OSB (if it needs to be larger) would suffice to stop impact noise transmitting to the other rooms?

Regarding air supply to the soundproofed HT room, would a passive duct between there and the living room be sufficient? There's space above the doors for me to run a duct from the HT room, across the hall ceiling (winding it around to reduce the noise transmission) and into the living room which won't be sealed and thus will have fresh air coming in. There's actually already boarded up grilles above the doors and some ducting hidden above a false ceiling in the hall for a redundant ventilation system which was fed by an air grille in the outer wall, so I'm going to have to remove all that old ducting first.


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## HT Geek

doveman said:


> I'm wondering what to do at the perimeter where the living room meets the hall and kitchen. I was thinking maybe I could have two joists with a small gap between them, so the living room board sits on one, the hall/kitchen board on the other and then fill the gap with mastic. As shown in the attached picture, the gap between the OSB boards could be wider than the gap between the joists so that some of the mastic is supported on the joists but maybe that's unnecessary and the gap can be the same between the joists and between the boards. I'm not sure whether it will be best to fill the gap between the joists with mastic as well or leave it as an air gap. I'm worried that if I leave it, bits of wood, etc. might get in there and bridge the gap. I don't think either of the gaps need to be very big to be effective, maybe 1mm between the joists and 3mm between the OSB (if it needs to be larger) would suffice to stop impact noise transmitting to the other rooms?


Seems like a reasonable concept to me, but you'll need larger gaps. I would suggest 6-12mm between the joists. Vibrations won't be completely stopped, but will be mitigated versus passing straight through if the joists were solidly connected.

I don't recall if you've considered RIM. I believe in your case it would raise your floor height. It may be your best bet for sound proofing the floor, but at the expense of dealing with the height adjustment inconvenience. AFAIK, the shortest depth RIM product is 25mm.



> Regarding air supply to the soundproofed HT room, would a passive duct between there and the living room be sufficient? There's space above the doors for me to run a duct from the HT room, across the hall ceiling (winding it around to reduce the noise transmission) and into the living room which won't be sealed and thus will have fresh air coming in. There's actually already boarded up grilles above the doors and some ducting hidden above a false ceiling in the hall for a redundant ventilation system which was fed by an air grille in the outer wall, so I'm going to have to remove all that old ducting first.


Bear in mind you need both supply and return air in the room. Otherwise, you will have uneven air pressure and the air won't circulate. This will lead to stale air, undesirable temperature variations, and potentially other issues. It's a more pronounced concern versus any other room in your abode, since a portion of the concept of a dedicated HT room involves making it as air-tight as possible.


----------



## HT Geek

Primare Knob said:


> The theater room is sitting next to the toilet area, which is sitting next to the laundry, which is sitting next to the garage. The rough idea is to run duct work from the theater room into the garage through the ceiling of the toilet and laundry either HVAC or fan powered.


Just got thru a holiday weekend here in the States or I would have replied more timely! 




> I can fit in an 8" duct since the ceiling cavity will be 8" , but on this short notice I can only find the 6" non insulated duct's.


First and foremost, you need BOTH supply and return air in your room. You have the advantage of new construction, as incorporating return air is often a retrofit challenge in existing rooms that are converted. If you don't have both supply and return, the air pressure in the room will be unbalanced and you won't get proper air circulation.

The ducts must be insulated if they are flex duct and supply runs. Return duct does not have to be insulated except where it transitions to a non-climate controlled space. If you're talking about metal ductwork, it's most often not insulated but will perform better if the supply runs are insulated. Metal ducts are to be avoided if at all possible in HT room construction as it is much more likely to transmit flanking noise.




> How would I insulate these duct pipes? Do I wrap the pipe in insulation or can I insulate the whole ceiling cavity around the ducts?


Supply ducts: you should insulate around them. Use R6 at a minimum.
Return ducts: you may insulate around them (e.g. fiberglass insulation) in climate controlled or semi-climate controlled spaces (e.g. between floors of your home or inside a soffit) or insulate them directly with a wrap as with the supply ducts. If your return ducts transition to a non-climate controlled space such as an attic that is susceptible to extreme temperature differences from your climate controlled space, I would insulate it as your supply ducts (on both sides of the transition for at least 50cm and ideally more). You should fully insulate the duct work inside the attic or other non-climate controlled space. You want to discourage condensation, which will form at the boundary if you don't insulate the ducts. If the non-climate controlled space is between floors, it would likely be fine if non-insulated, but I personally would not take the chance.




> Should I also use a double layer of plasterboard on the ceiling in the toilet and laundry for better sound proofing?


Wouldn't hurt, but I would not bother. It would be ideal to have a non-straight duct run with plenty of bends, but that can also be accomplished with flex duct in the ceiling or a soffit of the HT room, before the duct opens to registers in the room. Don't sweat it at this stage. You'll be able to work around any related issues when you build the HT room.




> I am planning on placing the fans or HVAC connected to these ducts on the end, inside the garage.
> (These ducts will be placed inside a double stud wall and a floating (clips) ceiling in the end)


Sounds good. There are some very good (quiet) in-line fans available if you feel the need to increase the air pressure in or out of the room, when you get to that point in construction/planning.


----------



## doveman

HT Geek said:


> Seems like a reasonable concept to me, but you'll need larger gaps. I would suggest 6-12mm between the joists. Vibrations won't be completely stopped, but will be mitigated versus passing straight through if the joists were solidly connected.


OK, As long as I fill the gap between the joists that should ensure the mastic between the OSB boards remains in place and level, so that there isn't a dip where toes, etc. might catch. I guess I can't use metal door strips like this http://www.screwfix.com/p/extra-wide-carpet-cover-door-strip-aluminium-0-9m-x-61mm/81951 as they'll span the gap and reconnect the two areas but I imagine the drop seals will work OK just sealing against the cork tiles without any need for door strip.



> I don't recall if you've considered RIM. I believe in your case it would raise your floor height. It may be your best bet for sound proofing the floor, but at the expense of dealing with the height adjustment inconvenience. AFAIK, the shortest depth RIM product is 25mm.


Yeah, I got a quote and it was over £1000 for 12m2 of 25mm, so unaffordable for me. I was thinking of laying it on the concrete slab below my subfloor and then OSB/ply on top to bring it up to the same level as the current floor (35mm joists+18mm floorboards), so it wouldn't have raised my floor. Would have been nice but not at that price!



> Bear in mind you need both supply and return air in the room. Otherwise, you will have uneven air pressure and the air won't circulate. This will lead to stale air, undesirable temperature variations, and potentially other issues. It's a more pronounced concern versus any other room in your abode, since a portion of the concept of a dedicated HT room involves making it as air-tight as possible.


OK, thanks. I'll have to research that some more!

EDIT: Do you think it's worth getting some neoprene sheet like these (they come in various thicknesses) http://uk.rs-online.com/web/c/abrasives-engineering-materials/rubber-sheets/neoprene-rubber-sheets/ and cutting them to cover all the joists before I lay the OSB, even if that's screwed into the joists? Although sound will be able to travel via the screws into the joists, perhaps the neoprene will still have a worthwhile effect in reducing the sound transmission from the OSB to the joists?

These are an interesting option too but I imagine they aren't cheap and the labour of having to grout them in will cost a fair bit as well http://www.mason-uk.co.uk/basket.asp?pid=440
This page shows them fitted on levelling pads http://www.mason-uk.co.uk/photos.asp?pid=440

Whilst one might be able to use hockey pucks instead, I'm not sure if they could be grouted in as easily and it wouldn't be sensible to leave them unsecured.


----------



## HT Geek

doveman said:


> OK, As long as I fill the gap between the joists that should ensure the mastic between the OSB boards remains in place and level, so that there isn't a dip where toes, etc. might catch. I guess I can't use metal door strips like this http://www.screwfix.com/p/extra-wide-carpet-cover-door-strip-aluminium-0-9m-x-61mm/81951 as they'll span the gap and reconnect the two areas but I imagine the drop seals will work OK just sealing against the cork tiles without any need for door strip.


If you keep the gap to around 6mm, you shouldn't have any issues. I meant to mention earlier that as you eluded, you should seal it to prevent having a gap that you'll get crap falling into (dust, dirt, etc.). An air gap would be ideal, but if it's not on the edge of the room, I would fill it with mastic or acoustic caulk. Just try to remember to check it a couple of times a year to be sure the seal hasn't broken. OTOH, if you will install carpet over it then it's a non-issue and I'd leave it open with no mastic/caulk.




> EDIT: Do you think it's worth getting some neoprene sheet like these (they come in various thicknesses) http://uk.rs-online.com/web/c/abrasives-engineering-materials/rubber-sheets/neoprene-rubber-sheets/ and cutting them to cover all the joists before I lay the OSB, even if that's screwed into the joists? Although sound will be able to travel via the screws into the joists, perhaps the neoprene will still have a worthwhile effect in reducing the sound transmission from the OSB to the joists?


I can't locate a good reference atm, but my recollection is the little research and conversation I've read on the subject indicates those types of solutions (similar to joist tape) have only demonstrated ~0-1 db improvement at best, with no appreciable change being the norm. IOW, I believe it would yield very little or no benefit, though it wouldn't hurt either. That is presuming a thickness


----------



## Primare Knob

This is what I have at the moment.

8" aluminum foil flex ducts with R1.0 (Australian) insulation. These ducts are actually to big to fit under the ceiling and will be compressed or bend out of shape when the soffit ceiling is fitted. The one on the end, I plan to use as a return, has no room to bend out of shape and is going to be compressed. The front one has some room to warp into an oval shape.

I also bought 6" versions of these, just in case that this compression going on, isn't working out in my favor.
The dry wall guys are starting tomorrow morning (Aussie Time) so there is a slim chance for some last minute changes if needed.


----------



## HT Geek

Primare Knob said:


> 8" aluminum foil flex ducts with R1.0 (Australian) insulation. These ducts are actually to big to fit under the ceiling and will be compressed or bend out of shape when the soffit ceiling is fitted. The one on the end, I plan to use as a return, has no room to bend out of shape and is going to be compressed. The front one has some room to warp into an oval shape.
> 
> I also bought 6" versions of these, just in case that this compression going on, isn't working out in my favor.
> The dry wall guys are starting tomorrow morning (Aussie Time) so there is a slim chance for some last minute changes if needed.


Just going w/your visual (i.e. w/out time to research Aussie R1.0), it looks good (insulation/foil).

Compression is not ideal, especially for that long of a run. Aside from potential damage to the ducts over such a long run of compressing them, you will increase the air speed and resistance and potentially increase noise. To function correctly, they need to be kept in their normal shape as much as possible and stretched out. Otherwise you will decrease their efficiency and potentially lead to the other problems mentioned.

Here's a suggestion: see if you can fit a 8" > 6" reducer, then run 6" flex duct in the HT room so it will fit inside the soffit without compression. 

For the supply ductwork: where it opens into the room, see if you can create a baffle and an oversized hole for the register (grille). The reduced duct width will increase air velocity, but the baffle will decrease it just before it enters the room. Pad the inside of the baffle with Linacoustic or similar HVAC approved use insulation to help control noise and break up any turbulence.

For return ductwork: Create an oversized return grille and feed it into a 6" flex duct. Use the same procedure with a reducer as it exits the room to open it up to the main run's 8" width. Extend the run in the room a bit if you can, such as by snaking the flex duct around a bit. Create a few wide radius turns if you can. You don't want to scrunch up the flex duct as this will create resistance and make the ducts inefficient. But from a soundproofing perspective if you can make the run a bit longer, along with the large grille opening it will slow down the air velocity. The idea is to avoid a hissing or air rushing sound in your HT room as the return sucks air toward your garage.

I am oversimplifying this all a bit. What *should* be done is to calculate air flow (CFM) and air velocity (FPM) as part of sorting out the proper length runs, etc. CFM is much easier to figure out and more important. Ideally, you want the supply and return values for CFM to match, but you also want a minimum of 6 air changes per hour in the room based on the room's volume after it's finished. I realize you probably don't have time to sort that out atm, thus my comments/suggestions above for a quick solution that's better than several meters of compressed ductwork.


----------



## HT Geek

@Primare Knob here are some photos to help you visualize my previous comments.

Here's my return grille housing. As you can see, there are two exit ducts. This allows me to increase air volume movement while dealing with the fact I could only fit 6" ducts inside my soffit (like yours). Note the difference in the take-offs is negligible. I simply used parts I had readily available.











Here it is mounted inside the soffit.











You can see I removed the insulation and foil. This is only for the return duct(s) and only inside the HT room. I did this due to my space constraints. It helped squeeze the duct in between the soffit joists. However, you can see I did put some insulation around them. This is not really necessary from a HVAC perspective, but it doesn't hurt. It was useful for me from a soundproofing perspective to prevent resonance in the soffit.











Here are two photos of the return air muffler box that joined the two take-off flex ducts from the return grille back to a single, larger flex duct (I believe this was 8" wide but it might be 10") before entering my attic. Note the changeover to insulated duct. 

You will want to ensure your flex duct is insulated before it enters your garage, and while it's in your garage (unconditioned air space). Based on your photos above, it appears your return duct is insulated all the way so it should be a non-issue for you.




















Now, for my supplies.... I have two supply ducts entering my room. One is a shorter run than the other, and thus it has a higher velocity airflow by default. To compensate for this and equalize the air pressure in both supply grilles, I actually used a combination of an expander, and then a baffle. I know that sounds odd, but here's how it works. 

The short supply run enters this expander. By 'expander' I mean the space the air is travelling in expands from a 7" wide duct to a 1 meter long box ~11" wide. This slows down the air velocity a bit. 











Then the air enters the baffle/register combo. The small-ish hole between the expander and baffle allows some air to enter, but again this causes a bit of bunching up inside the expander. The combination further slows the air velocity a bit. And finally, the significantly larger hole for the grille in the room allows another expansion before the air enters the room.

The net effect is my supply grilles are completely silent. The only way I know they're on is by feeling the exiting air flow.


----------



## HT Geek

doveman said:


> These are an interesting option too but I imagine they aren't cheap and the labour of having to grout them in will cost a fair bit as well http://www.mason-uk.co.uk/basket.asp?pid=440
> This page shows them fitted on levelling pads http://www.mason-uk.co.uk/photos.asp?pid=440
> 
> Whilst one might be able to use hockey pucks instead, I'm not sure if they could be grouted in as easily and it wouldn't be sensible to leave them unsecured.


I agree they look like narrow hockey pucks, and yes you might consider hockey pucks instead. I've had good luck with grouting small platforms of hockey pucks using acoustic caulk, applying weight above, and allowing 48 hours for it to set. I've also used hockey pucks with a reasonable amount of weight on top and no caulk. They haven't moved so far (and to get them to do so would now require considerable lateral force; I'm confident they are secure).

If you do decide to use hockey pucks, I'd suggest official pucks made in Canada and to try and avoid those made in 3rd world countries. The Canadians are zealous of their hockey puck certification, so I would personally feel confident they are truly galvanized rubber. From some countries such as China, one never knows for sure what things are made of.


Back to your HVAC question you had yesterday; you may be able to get a passive system such as a Dead Vent to work as well. I'd suggest researching that option. The SPC website has a good overview.


----------



## Primare Knob

HT Geek said:


> Just going w/your visual (i.e. w/out time to research Aussie R1.0), it looks good (insulation/foil).
> 
> Compression is not ideal, especially for that long of a run. Aside from potential damage to the ducts over such a long run of compressing them, you will increase the air speed and resistance and potentially increase noise. To function correctly, they need to be kept in their normal shape as much as possible and stretched out. Otherwise you will decrease their efficiency and potentially lead to the other problems mentioned.
> 
> Here's a suggestion: see if you can fit a 8" > 6" reducer, then run 6" flex duct in the HT room so it will fit inside the soffit without compression.
> 
> For the supply ductwork: where it opens into the room, see if you can create a baffle and an oversized hole for the register (grille). The reduced duct width will increase air velocity, but the baffle will decrease it just before it enters the room. Pad the inside of the baffle with Linacoustic or similar HVAC approved use insulation to help control noise and break up any turbulence.
> 
> For return ductwork: Create an oversized return grille and feed it into a 6" flex duct. Use the same procedure with a reducer as it exits the room to open it up to the main run's 8" width. Extend the run in the room a bit if you can, such as by snaking the flex duct around a bit. Create a few wide radius turns if you can. You don't want to scrunch up the flex duct as this will create resistance and make the ducts inefficient. But from a soundproofing perspective if you can make the run a bit longer, along with the large grille opening it will slow down the air velocity. The idea is to avoid a hissing or air rushing sound in your HT room as the return sucks air toward your garage.
> 
> I am oversimplifying this all a bit. What *should* be done is to calculate air flow (CFM) and air velocity (FPM) as part of sorting out the proper length runs, etc. CFM is much easier to figure out and more important. Ideally, you want the supply and return values for CFM to match, but you also want a minimum of 6 air changes per hour in the room based on the room's volume after it's finished. I realize you probably don't have time to sort that out atm, thus my comments/suggestions above for a quick solution that's better than several meters of compressed ductwork.


Just for a quick clarification, am I OK with compressed 8" ducts over the toilet and laundry area? (3meter run)

I don't have room to run multiple outside the cinema or for the return inside the HR room. I can run a 6" return over 5 meter length inside the ht room, or I have to run all ducts inside the planned double stud wall.

Or should I change the return supply from an 8" non insulated or to a 6" insulated.

I'll see if I can work out some quick calculations.

Sent from my HTC_0PKV1 using Tapatalk


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## HT Geek

Primare Knob said:


> Just for a quick clarification, am I OK with compressed 8" ducts over the toilet and laundry area? (3meter run)


It's not ideal, but better than compressing it inside your HT room. I am not an HVAC expert, so I don't know how big of an issue that may be. However, I'm inclined to think in that scenario that an expert might recommend using metal ductwork with suitable dimensions to maintain the same airflow rate. There are adapters to switch between metal duct (rectangular) and flex duct.

Or you could use 8" > 6" reducers to change the width between 8" and 6" sections. Then use 6" duct in the areas where you don't have room for 8".




> I don't have room to run multiple outside the cinema or for the return inside the HR room. I can run a 6" return over 5 meter length inside the ht room, or I have to run all ducts inside the planned double stud wall.


I'm not sure if we're on the same page on that ^ or not. You only need 1x supply line and 1x return line coming into the HT room. Once inside, you can split them if desired to allow for multiple supply or return grilles. Your choice at that point (though the recommended configuration is supply grilles in the front end of the room and return grilles in the rear).




> Or should I change the return supply from an 8" non insulated or to a 6" insulated.


You can use non-insulated for the returns ONLY (not supply runs), provided before you transition to an unconditioned air space that it is insulated. I like to give it about 1 meter or more of insulation before the duct breaches the barrier to the unconditioned space (such as your garage), but you can do it with less (insulated distance before transition). What you're trying to accomplish in that process is preventing condensation buildup on your flex duct due to temperature changes between climate controlled and non-climate controlled air spaces. Over time, such condensation leads to mold, and potentially, duct structural failure. The condensation forms due to differences in air temperature inside and outside of the flex duct.


----------



## Primare Knob

HT Geek said:


> It's not ideal, but better than compressing it inside your HT room. I am not an HVAC expert, so I don't know how big of an issue that may be. However, I'm inclined to think in that scenario that an expert might recommend using metal ductwork with suitable dimensions to maintain the same airflow rate. There are adapters to switch between metal duct (rectangular) and flex duct.
> 
> Or you could use 8" > 6" reducers to change the width between 8" and 6" sections. Then use 6" duct in the areas where you don't have room for 8".
> 
> 
> 
> 
> I'm not sure if we're on the same page on that ^ or not. You only need 1x supply line and 1x return line coming into the HT room. Once inside, you can split them if desired to allow for multiple supply or return grilles. Your choice at that point (though the recommended configuration is supply grilles in the front end of the room and return grilles in the rear).
> 
> 
> 
> 
> You can use non-insulated for the returns ONLY (not supply runs), provided before you transition to an unconditioned air space that it is insulated. I like to give it about 1 meter or more of insulation before the duct breaches the barrier to the unconditioned space (such as your garage), but you can do it with less (insulated distance before transition). What you're trying to accomplish in that process is preventing condensation buildup on your flex duct due to temperature changes between climate controlled and non-climate controlled air spaces. Over time, such condensation leads to mold, and potentially, duct structural failure. The condensation forms due to differences in air temperature inside and outside of the flex duct.


Thanks, I might already have an issue here. 

I understand and I am also limited to one supply and return duct. I have a couple of roof joist running in the length of the HT room creating cavities in which I run these ducts.

I can only use the outer 2 cavities to run ducts because of a sky light and entry access into the garage.

The most outer cavity is actually only suited for a 6" perhaps with some insulation. Due to the roof joist I can only make this run longer and add a vent/box design at the end of it.

The other one is hight wise only suited for an 8" non insulated but could potentially run a second duct paralel to it inside the HT room.

The option to create bulk heads isn't a great one, since my ceiling will be sitting at 225cm and adding bulk head will make this even worse. The bulk head could potentially add a second run of ducts inside the HT room to increase total diameter, but in the end it will all have to be hooked up into the main 2 ducts over the toilet and laundry.
And that is were I am at the moment.

The first plan is to use inline fans, and if that doesn't work switch to a HVAC unit. It would then be the only room with air-con since the rest of the house doesn't.

There is a 5 degree (cooler) difference between garage and inside due to an earth wall and concrete slab straight on the always moist ground. But I assume that the air velocity or flow, is the same for both HVAC and inline fan anyway. In that case the only option is to either keep or remove the insulation.

Or to not do it at all. It is still an option to not go sound proofing and just turn it into a room with some cinema equipment. This is another compromise added to a growing list.


----------



## Primare Knob

I have tried to do some duct calculations, but I don't really know what they tell me, or if it is any good.

Room size 1380.6 Cu/ft x 6 air change overs = 8238.55 / 60(min) = CFM 138.06

I put that into a calculator for both 6" and 8" flexi-ducts. But what number is the important one.
Is there a max or min FPM for a dedicated home theater? I come across the number 250 a lot but can't find a definite answer so far.


----------



## HT Geek

Primare Knob said:


> I have tried to do some duct calculations, but I don't really know what they tell me, or if it is any good.
> 
> Room size 1380.6 Cu/ft x 6 air change overs = 8238.55 / 60(min) = CFM 138.06
> 
> I put that into a calculator for both 6" and 8" flexi-ducts. But what number is the important one.


That should be your target. Here's a rough estimator for CFM supply and return ducts. This chart is most useful when figuring out how to balance supply and return ducts with equal air flow. In your case, if you have supply and return vents that are the same size that won't be an issue as long as the fans you will use are the same flow rate. 











Looks like you should (ideally) use a 7" round duct (# above your target of 138). However, a 6" is pretty close. Perhaps install variable speed fans you can control remotely. That way if your room gets too warm watching a movie, you can adjust the flow rate (even at the expense of increased noise). At least it would provide that option.




> Is there a max or min FPM for a dedicated home theater? I come across the number 250 a lot but can't find a definite answer so far.


Yes. You want to keep it below 250 FPM if you can. It's unlikely to be an issue. Just don't install a wind cannon in your garage. 

@doveman, FYB (and Primare's), the Sound Proofing Company (SPC) guide on dead vents is here.


----------



## HT Geek

Primare Knob said:


> Thanks, I might already have an issue here.
> 
> I understand and I am also limited to one supply and return duct. I have a couple of roof joist running in the length of the HT room creating cavities in which I run these ducts.
> 
> I can only use the outer 2 cavities to run ducts because of a sky light and entry access into the garage.
> 
> The most outer cavity is actually only suited for a 6" perhaps with some insulation. Due to the roof joist I can only make this run longer and add a vent/box design at the end of it.
> 
> The other one is hight wise only suited for an 8" non insulated but could potentially run a second duct paralel to it inside the HT room.
> 
> The option to create bulk heads isn't a great one, since my ceiling will be sitting at 225cm and adding bulk head will make this even worse. The bulk head could potentially add a second run of ducts inside the HT room to increase total diameter, but in the end it will all have to be hooked up into the main 2 ducts over the toilet and laundry.
> And that is were I am at the moment.
> 
> *The first plan is to use inline fans, and if that doesn't work switch to a HVAC unit. It would then be the only room with air-con since the rest of the house doesn't.
> *
> There is a 5 degree (cooler) difference between garage and inside due to an earth wall and concrete slab straight on the always moist ground. But I assume that the air velocity or flow, is the same for both HVAC and inline fan anyway. In that case the only option is to either keep or remove the insulation.
> 
> Or to not do it at all. It is still an option to not go sound proofing and just turn it into a room with some cinema equipment. This is another compromise added to a growing list.


Ah. Now understanding you don't have A/C to begin with changes the picture a bit. A 5° difference won't be significant enough to create condensation issues. I'd venture you would be OK using uninsulated duct all around in that case (for supply and return). IF you decided to add A/C in the future though, that could create a problem because there's often 40+ degrees Fahrenheit difference in return and supply air temps. Then add a few more degrees for ambient air temp diffs of unconditioned/conditioned air space, and you might create a problem and you'd be back to needing insulated supply runs. So, how you handle this now will impact your future options.

Another idea would be install a mini-split in your room, but that would introduce noise. An option (and you could decide in the future), and as you say there are always compromises.

BTW, there are plenty of folks with just 1 supply vent and 1 return vent in their room. No need to create more issues if adding additional duct runs and grilles in your room would be problematic.


----------



## doveman

HT Geek said:


> If you keep the gap to around 6mm, you shouldn't have any issues. I meant to mention earlier that as you eluded, you should seal it to prevent having a gap that you'll get crap falling into (dust, dirt, etc.). An air gap would be ideal, but if it's not on the edge of the room, I would fill it with mastic or acoustic caulk. Just try to remember to check it a couple of times a year to be sure the seal hasn't broken. OTOH, if you will install carpet over it then it's a non-issue and I'd leave it open with no mastic/caulk.


That's a good point, it will probably have cork tile over the gap so nothing will be able to fall into it.



> I can't locate a good reference atm, but my recollection is the little research and conversation I've read on the subject indicates those types of solutions (similar to joist tape) have only demonstrated ~0-1 db improvement at best, with no appreciable change being the norm. IOW, I believe it would yield very little or no benefit, though it wouldn't hurt either. That is presuming a thickness


----------



## doveman

HT Geek said:


> I agree they look like narrow hockey pucks, and yes you might consider hockey pucks instead. I've had good luck with grouting small platforms of hockey pucks using acoustic caulk, applying weight above, and allowing 48 hours for it to set. I've also used hockey pucks with a reasonable amount of weight on top and no caulk. They haven't moved so far (and to get them to do so would now require considerable lateral force; I'm confident they are secure).
> 
> If you do decide to use hockey pucks, I'd suggest official pucks made in Canada and to try and avoid those made in 3rd world countries. The Canadians are zealous of their hockey puck certification, so I would personally feel confident they are truly galvanized rubber. From some countries such as China, one never knows for sure what things are made of.


Yeah, I've seen some pucks that say they're made of "rubber foam", whatever that is! I'll have to compare using Canadian pucks vs the Form Work products. One advantage of the latter is that it comes in 38mm depth, which is pretty close to the 35mm depth of my joists. Obviously with shorter pucks I could build up layers of OSB to recreate the same height, it just might be easier using the 38mm Form Work ones.



> Back to your HVAC question you had yesterday; you may be able to get a passive system such as a Dead Vent to work as well. I'd suggest researching that option. The SPC website has a good overview.


Thanks, I'll have a read of the link you posted. It might actually be quite easy for me, as there's an old vent system that's fed from a grille outside my kitchen window, so I might be able to tap into the that for the cold air intake and have the stale air exhaust into the kitchen (maybe via the living room if I need extra length in the ducting) where it can exit through the open window.


----------



## Cpowell99

*Studs: 2x6 or 2x4?*

Hi All,

I'm building a room within a room and was thinking to use 2x6 studs so that when I put my 3" batting in, I have a 2.5" air pocket. Would that be more beneficial than the 0.5" air pocket using 2x4s would leave?

Thanks in advance,
Chris Powell


----------



## HT Geek

doveman said:


> Yeah, I've seen some pucks that say they're made of "rubber foam", whatever that is! I'll have to compare using Canadian pucks vs the Form Work products. One advantage of the latter is that it comes in 38mm depth, which is pretty close to the 35mm depth of my joists. Obviously with shorter pucks I could build up layers of OSB to recreate the same height, it just might be easier using the 38mm Form Work ones.


Good thought. The regulation pucks are either 25 or 25.5mm tall.


----------



## HT Geek

Cpowell99 said:


> Hi All,
> 
> I'm building a room within a room and was thinking to use 2x6 studs so that when I put my 3" batting in, I have a 2.5" air pocket. Would that be more beneficial than the 0.5" air pocket using 2x4s would leave?


Technically, yes. However, you'd be missing an opportunity to use thicker battings. Insulation acts as a pressure absorber. The more you have, the more it lowers the frequency of the sound travelling through it by converting some of the sound energy into heat. The end result is more thickness won't help with LFE absorption (until you get into _feet_ of thickness), but will improve your mid-to-high frequency absorption if you use a wider cavity (2x6 vs. 2x4). In turn, going from 3" thick insulation in that cavity to 5-5.5" thick will reduce the mids and highs even further.

Owens Corning manufactures 5.5" thick fiberglass batts (rated R21). Roxul makes a 5.5" thick mineral wool batt as well (rated R23). I'm sure other companies make them too. The R-ratings don't matter for sound proofing, but they do help verify what thickness the batts are when you're shopping.


----------



## doveman

HT Geek said:


> Good thought. The regulation pucks are either 25 or 25.5mm tall.


I had an e-mail back from Mason and they suggested using these 50x50x19mm pads, which are only £1.80+VAT and shipping, so probably not much different from the Canadian hockey pucks (and importing those could be expensive). http://www.masonuk.co.uk/sw16v2.pdf

They recommended placing them at 400mm centres under the floor and using two layers of 18mm ply for mass and rigidity, although I guess OSB would be just as good. 

Those are going to be too high for me though, so I've e-mailed them back to explain I can only use 25mm or 38mm isolators and I'll see what they recommend.

As I need a smooth ply surface to stick the cork tiles to, using two layers of 18mm OSB with 2mm ply on top might be the cheapest option and with 38mm isolators would raise my floor height by 14mm and with 5mm cork tiles on top it would match the height of the adjoining kitchen floor, which is covered with 19mm of ply and vinyl.


----------



## GatorBlues

I have a few double drywall with green glue questions. By way of background, the theater is a room within a room, so there are no clips or channel to worry about. We are building a new home, and the contractor will install whatever drywall approach we decide to use.

Should we use acoustical caulk between the seams on the first layer, or just mud? 

At the intersection of the walls and ceiling (i.e., where the drywall on the wall has the drywall for the ceiling on top of it), do we seal it with mud or acoustical sealant? 

(I am aware that we want a small gap between the drywall on the walls and the concrete floor, and that we will seal the gap with acoustical sealant.) 

Should we consider using one layer of Quietrock instead of DD/GG? Is QR as effective? Typically, is it more or less expensive when paying for installation too? (My searches have given me inconsistent information of the comparative "installed" pricing.)


----------



## Ladeback

GatorBlues said:


> I have a few double drywall with green glue questions. By way of background, the theater is a room within a room, so there are no clips or channel to worry about. We are building a new home, and the contractor will install whatever drywall approach we decide to use.
> 
> Should we use acoustical caulk between the seams on the first layer, or just mud?
> 
> At the intersection of the walls and ceiling (i.e., where the drywall on the wall has the drywall for the ceiling on top of it), do we seal it with mud or acoustical sealant?
> 
> (I am aware that we want a small gap between the drywall on the walls and the concrete floor, and that we will seal the gap with acoustical sealant.)
> 
> Should we consider using one layer of Quietrock instead of DD/GG? Is QR as effective? Typically, is it more or less expensive when paying for installation too? (My searches have given me inconsistent information of the comparative "installed" pricing.)


From what I have read and heard you don't need to mud or seal the first layer of dry wall.

I have read and been told to leave a 1/4" gap at the top and bottom and where ever the dry wall come together at a 90 degree. You then would fill it with acoustical caulk. 

I have priced QR and it is a lot more extensive to me and I was told pretty heavy. It was more the cost of DD & GG, but that is in my area. Call around and get some prices on it to see for your cost.


----------



## HT Geek

Ladeback said:


> From what I have read and heard you don't need to mud or seal the first layer of dry wall.


Actually, I'd say it's a somewhat controversial topic, but I agree with you. It's probably more controversial relative to the final/outer layer of drywall. IMHO, if you stagger your seams you shouldn't worry about it and use normal mud on the outer layer (and as Gator said, don't use anything for the inner layers as it doesn't matter).




> I have read and been told to leave a 1/4" gap at the top and bottom and where ever the dry wall come together at a 90 degree. You then would fill it with acoustical caulk.


Yes, this is the important part.




> I have priced QR and it is a lot more extensive to me and I was told pretty heavy. It was more the cost of DD & GG, but that is in my area. Call around and get some prices on it to see for your cost.


That's been my experience as well. However, it is worth pricing out and comparing total cost of labor + Green Glue/Quiet Glue Pro if you do the DD+GG route instead of QuietRock. Building contractors are accustomed to free delivery to a jobsite, so your labor should only be moving and slapping up the drywall. The advantage therein of QR is 1) you don't need to purchase Green Glue or a similar product (e.g. Quiet Glue Pro); and 2) you are not paying for 2 rounds of drywall attachment in your room. 

My point is if you're talking DIY labor then normal Type X drywall + GG is virtually always going to be cheaper. However, when you are paying laborers, the cost delta shrinks by virtue of the fact the QR requires less than 1/2 the labor of a DD+GG installation. It's probably still cheaper to do DD+GG, but it might not be.


----------



## Ladeback

HT Geek said:


> Actually, I'd say it's a somewhat controversial topic, but I agree with you. It's probably more controversial relative to the final/outer layer of drywall. IMHO, if you stagger your seams you shouldn't worry about it and use normal mud on the outer layer (and as Gator said, don't use anything for the inner layers as it doesn't matter).
> 
> 
> 
> 
> Yes, this is the important part.
> 
> 
> 
> 
> That's been my experience as well. However, it is worth pricing out and comparing total cost of labor + Green Glue/Quiet Glue Pro if you do the DD+GG route instead of QuietRock. Building contractors are accustomed to free delivery to a jobsite, so your labor should only be moving and slapping up the drywall. The advantage therein of QR is 1) you don't need to purchase Green Glue or a similar product (e.g. Quiet Glue Pro); and 2) you are not paying for 2 rounds of drywall attachment in your room.
> 
> My point is if you're talking DIY labor then normal Type X drywall + GG is virtually always going to be cheaper. However, when you are paying laborers, the cost delta shrinks by virtue of the fact the QR requires less than 1/2 the labor of a DD+GG installation. It's probably still cheaper to do DD+GG, but it might not be.


When I looked in to Quite Rock there were different levels based on thickness and materials. I don't remember the difference in cost other then that just using Green Glue and two layers of dry wall was a lot cheaper and QR is pretty heavy stuff. So I didn't want to mess with it. Now my brother in law had his contractor use it when he built his house in Colorado and likes it, but he didn't install it. With the price of a new house he may not have noticed the difference as much in price.


----------



## GatorBlues

HT Geek said:


> My point is if you're talking DIY labor then normal Type X drywall + GG is virtually always going to be cheaper. However, when you are paying laborers, the cost delta shrinks by virtue of the fact the QR requires less than 1/2 the labor of a DD+GG installation. It's probably still cheaper to do DD+GG, but it might not be.


My builder will do the install and I'm waiting on the quote. After paying for labor, the two options could turn out to be roughly the same price. We'll see. Assuming they're roughly the same price, which do you prefer? Is QR better than DD/GG, vice versa, or are they about equal?


----------



## jrref

GatorBlues said:


> My builder will do the install and I'm waiting on the quote. After paying for labor, the two options could turn out to be roughly the same price. We'll see. Assuming they're roughly the same price, which do you prefer? Is QR better than DD/GG, vice versa, or are they about equal?


The DD/GG will probably give you a little better results because you are using 2x5/8 sheetrock, but you might want to consider using QR if the builder is doing the job since there is no guarantee that he will make the DD/GG "sandwich" correctly on all the sheets unless you plan to stand there and watch him on every sheet. At least with QR all he has to do is install the rock and use the sealant. Just my opinion.


----------



## Ladeback

jrref said:


> The DD/GG will probably give you a little better results because you are using 2x5/8 sheetrock, but you might want to consider using QR if the builder is doing the job since there is no guarantee that he will make the DD/GG "sandwich" correctly on all the sheets unless you plan to stand there and watch him on every sheet. At least with QR all he has to do is install the rock and use the sealant. Just my opinion.


I agree with @jrref. There are different levels of Quite Rock and it depends on what you go with. I think the EZ-Snap is the cheapest and can get you a STC from 60 to 80 they say, but clips, channel, DD and GG on theater side and DD & GG on other wall will give you around an STC of 71. I would think if you decouple the walls and use QR it should be pretty good. 

Are you going to use clips and channel on the walls and ceiling? I take it you are also 

https://www.quietrock.com/productsinsulating the walls and ceiling?

Here is different ways you can do soundproofing on a wall.

http://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-walls/


----------



## GatorBlues

Ladeback said:


> I agree with @jrref. There are different levels of Quite Rock and it depends on what you go with. I think the EZ-Snap is the cheapest and can get you a STC from 60 to 80 they say, but clips, channel, DD and GG on theater side and DD & GG on other wall will give you around an STC of 71. I would think if you decouple the walls and use QR it should be pretty good.
> 
> Are you going to use clips and channel on the walls and ceiling? I take it you are also
> 
> https://www.quietrock.com/productsinsulating the walls and ceiling?
> 
> Here is different ways you can do soundproofing on a wall.
> 
> http://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-walls/


The theater is a room within a room, so I won't use clips and channel. The builder will install either DD/GG on the room within a room's studs and ceiling joists, or will install Quietrock instead. We're insulating each of the walls and the ceiling above the theater too. 

In the rest of the basement, we've been considering whether to use clips, channel and either DD/GG or Quietrock on the ceilings just to improve the sound isolation between the kids' play areas in the basement from the living areas upstairs. Until we see the quote, I'm not sure if we'll think it's worth the expense.


----------



## GatorBlues

jrref said:


> The DD/GG will probably give you a little better results because you are using 2x5/8 sheetrock, but you might want to consider using QR if the builder is doing the job since there is no guarantee that he will make the DD/GG "sandwich" correctly on all the sheets unless you plan to stand there and watch him on every sheet. At least with QR all he has to do is install the rock and use the sealant. Just my opinion.


Thanks. Honestly, when they hang sheetrock in the theater, I probably will stand there and watch them do it. I'm sinking a bunch of extra money into this theater room (room within a room, plus a riser, theater chairs, projector, screen, and audio equipment). I want to keep an eye on them and make sure it comes out right.


----------



## HT Geek

I agree with @jrref as well, though there's something to be said for the DD/GG route. If you're confident you'll be able to oversee that part, I'd personally steer toward that route if supplies & labor were equal $. I say that only because DD+GG is a time-tested approach. Many folks on this forum have reported good results. I've heard a few good stories about QuietRock as well, but it's probably a ratio of 100:1 of folks who've used GG vs QR. 

One issue in QR's favor is consistency of the amount of viscoelastic glue, though I don't know how much they purport to use per 4x8 'sandwich.' There are different versions of QR as well, so make sure you know what you're getting installed if you go that route. GG's effectiveness is supposed to be maximized by using a volume of 2x tubes per 1x 4x8 sheet of drywall, yet I personally only used 1 tube per sheet, to save $. 

One more thought.... I have looked at a wealth of lab test data of various configurations of drywall installs. The vast majority of these used Green Glue or no viscoelastic glue. I'd say a handful or so used Quiet Glue or QuietRock. I'm just saying there's much more data on GG, FWIW. To that end I can tell you the _performance_ of GG is very consistent. Comparing GG vs. QG Pro or QR - accepting the fact there's not much empirical data on them - what they offer is similar in performance to the GG tests. If you take all the tests at face value, there were some slight variations where one product was slightly better at the other in a few freq ranges, but it's not something I would be concerned about (minor differences). But again there's not much data on the QR/QG side of the coin, which is why I would not put much emphasis on a comparison between the two using lab tests. What is clear is they both work. 

What I'm trying to say... in my long-winded fashion... is you'll be good with either one from a performance perspective. It really boils down to personal preference, cost, and if you're truly able to oversee the installation process (if using GG). The vast majority of drywall hangers have no experience with GG. This is one reason I did my DW work myself. And my other point is: there's a wealth of data backing up GG's performance claims, so if confidence in the product is important to you, there is more objective data available for GG.


----------



## MidnightWatcher

Question - I'm building a home theater in my basement which has two windows, but the top of both windows are higher than the base of the floor joists. Any suggestions on how to "soundproof" the bottom of the subfloor where the windows are framed out? They are similar to this:


----------



## jrref

HT Geek said:


> I agree with @jrref as well, though there's something to be said for the DD/GG route. If you're confident you'll be able to oversee that part, I'd personally steer toward that route if supplies & labor were equal $. I say that only because DD+GG is a time-tested approach. Many folks on this forum have reported good results. I've heard a few good stories about QuietRock as well, but it's probably a ratio of 100:1 of folks who've used GG vs QR.
> 
> One issue in QR's favor is consistency of the amount of viscoelastic glue, though I don't know how much they purport to use per 4x8 'sandwich.' There are different versions of QR as well, so make sure you know what you're getting installed if you go that route. GG's effectiveness is supposed to be maximized by using a volume of 2x tubes per 1x 4x8 sheet of drywall, yet I personally only used 1 tube per sheet, to save $.
> 
> One more thought.... I have looked at a wealth of lab test data of various configurations of drywall installs. The vast majority of these used Green Glue or no viscoelastic glue. I'd say a handful or so used Quiet Glue or QuietRock. I'm just saying there's much more data on GG, FWIW. To that end I can tell you the _performance_ of GG is very consistent. Comparing GG vs. QG Pro or QR - accepting the fact there's not much empirical data on them - what they offer is similar in performance to the GG tests. If you take all the tests at face value, there were some slight variations where one product was slightly better at the other in a few freq ranges, but it's not something I would be concerned about (minor differences). But again there's not much data on the QR/QG side of the coin, which is why I would not put much emphasis on a comparison between the two using lab tests. What is clear is they both work.
> 
> What I'm trying to say... in my long-winded fashion... is you'll be good with either one from a performance perspective. It really boils down to personal preference, cost, and if you're truly able to oversee the installation process (if using GG). The vast majority of drywall hangers have no experience with GG. This is one reason I did my DW work myself. And my other point is: there's a wealth of data backing up GG's performance claims, so if confidence in the product is important to you, there is more objective data available for GG.


So here is where the train comes off the track.

I think GG is a great product and the reports on it's effectiveness are from those who use the recommended amount of GG and apply it with precision, probably themselves. It's not something that you just slap on and assume you are getting maximum soundproofing. QuietRock or the American Gypsum product, SoundBreak XP which is cheaper, has the viscoelastic layer put on at the factory and is done with precision so you know that you are getting the specified level of soundproofing on every sheet. This is why I get skeptical when someone says that their contractor is going to do GG. Bottom line, if your contractor is very reliable and is willing to follow exact instructions on how to apply the GG and you are monitoring to make sure that they are actually doing everything right on every sheet, then go with GG otherwise you are probably better off getting the pre-made sheets and not have to worry that maybe the contractor did something wrong with one or two sheets of GG here and there. Also although GG will give better results, it's not that big of a difference. I guess it's how much stress you are able to handle. Just my opinion.


----------



## HT Geek

MidnightWatcher said:


> Question - I'm building a home theater in my basement which has two windows, but the top of both windows are higher than the base of the floor joists. Any suggestions on how to "soundproof" the bottom of the subfloor where the windows are framed out? They are similar to this:


Depends on your overall strategy for the room. 

What are you planning in terms of sound-proofing from a framing perspective? Will this be a room-within-a-room? If so, clips and channel, staggered stud, double stud walls?? What's your plan for the ceiling? Are you completely open to which route you will take?

And last but not least, what are the current room dimensions?


----------



## MidnightWatcher

HT Geek said:


> Depends on your overall strategy for the room.
> 
> What are you planning in terms of sound-proofing from a framing perspective? Will this be a room-within-a-room? If so, clips and channel, staggered stud, double stud walls?? What's your plan for the ceiling? Are you completely open to which route you will take?
> 
> And last but not least, what are the current room dimensions?


Nothing fancy, just need decent sound dampening. Drywall with Roxul Safe 'N Sound in walls and ceilings, Safe 'N Sound door with weather stripping. Seems like the weakest link are those windows, which extend up to the subfloor of the upper floor, which is hardwood.


----------



## HT Geek

MidnightWatcher said:


> Nothing fancy, just need decent sound dampening. Drywall with Roxul Safe 'N Sound in walls and ceilings, Safe 'N Sound door with weather stripping. Seems like the weakest link are those windows, which extend up to the subfloor of the upper floor, which is hardwood.


I'm going to presume by your statement (unless you indicate otherwise) that you're saying no build-a-room-within-a-room craziness or extra drywall layers, etc. In that case, it seems to me the best choice would be to block out the window(s). 

Board up the window from the inside w/plywood, add insulation, then another layer of plywood or MDF and adhere drywall to that. Something like an L-shape inside the room. Create a new corner in the room, as if the current indentation wasn't there. That's all presuming it's possible to access the window from the outside in the event it suffers damage or needs replacement due to broken seals. My understanding is most windows can be accessed for repair from the outside, provided you hire someone who knows what to do.


----------



## MidnightWatcher

HT Geek said:


> I'm going to presume by your statement (unless you indicate otherwise) that you're saying no build-a-room-within-a-room craziness or extra drywall layers, etc. In that case, it seems to me the best choice would be to block out the window(s).
> 
> Board up the window from the inside w/plywood, add insulation, then another layer of plywood or MDF and adhere drywall to that. Something like an L-shape inside the room. Create a new corner in the room, as if the current indentation wasn't there. That's all presuming it's possible to access the window from the outside in the event it suffers damage or needs replacement due to broken seals. My understanding is most windows can be accessed for repair from the outside, provided you hire someone who knows what to do.


Correct, no craziness. Boarding up the windows is a no go due to the WAF. Is there any sound dampening foam or any other material I could apply to the subfloor inside the window framing?


----------



## HT Geek

MidnightWatcher said:


> Boarding up the windows is a no go due to the WAF. Is there any sound dampening foam or any other material I could apply to the subfloor inside the window framing?


What is the WAF concern exactly? Appearance from the outside, inside appearance, wants to keep the window, etc.?


----------



## MidnightWatcher

HT Geek said:


> What is the WAF concern exactly? Appearance from the outside, inside appearance, wants to keep the window, etc.?


Safety.


----------



## HT Geek

MidnightWatcher said:


> Safety.


Safety as in egress? Am I correct in presuming this room is in a basement?

How high off the floor is the window? Is it reasonably accessible now? 

Windows that look like that are normally not considered a point of egress in an emergency. There are many laws and regulations that go into determining how the windows in our homes look and function, but emergency access via a small window near the ceiling is not one of them.

btw, I don't intend to come across as The Spanish Inquisition. I'm trying to formulate ideas on what might placate your wife's concerns and your interests.


----------



## MidnightWatcher

HT Geek said:


> Safety as in egress? Am I correct in presuming this room is in a basement?
> 
> How high off the floor is the window? Is it reasonably accessible now?
> 
> Windows that look like that are normally not considered a point of egress in an emergency. There are many laws and regulations that go into determining how the windows in our homes look and function, but emergency access via a small window near the ceiling is not one of them.
> 
> btw, I don't intend to come across as The Spanish Inquisition. I'm trying to formulate ideas on what might placate your wife's concerns and your interests.


I've looked into local building codes and it seems that we need to have at least one window. At any rate, I talked it over with my wife and the contractor and boarding up the windows requires that it be closed properly from the outside as well, which isn't in the budget. Furthermore, it could be a sticking point for most future buyers if we ever decided to resell.

Looks like I need to identify another way to physically dampen sound transference. Rigid foam perhaps?


----------



## HT Geek

MidnightWatcher said:


> I've looked into local building codes and it seems that we need to have at least one window. At any rate, I talked it over with my wife and the contractor and boarding up the windows requires that it be closed properly from the outside as well, which isn't in the budget. Furthermore, it could be a sticking point for most future buyers if we ever decided to resell.
> 
> Looks like I need to identify another way to physically dampen sound transference. Rigid foam perhaps?


Well.... this is a can-o-worms, but here goes....

First off, unless you can finish off that corner (as in effectively isolate the window from your room), you will not be able to deal with the issue it presents very effectively. However, that said, it seems you're contemplating going to light-to-moderate lengths in prepping your room to begin with. I can appreciate that decision on several levels.

There are a few problems I believe you'll run into with the window. First, outside noise getting into the HT room (e.g. lawn mowers). Second, flanking noise travelling from your HT room to the room(s) above, and vice-versa. However, without treating the ceiling and walls, you're going to have a less-than-ideal solution anyway. 

What I'd suggest under the circumstances is consider something like a big blob of fiberglass ("pink fluffy") insulation. Ideally, you want to isolate that window and corner to prevent light and sound from emanating from or into it. But being cognizant of your limitations, your next-best option may be to stuff as much insulation as you can up there. The insulation won't provide an ideal solution, but it will mitigate the effect by a small amount. The result will be slightly better than what you have now, but don't expect a miracle. And without a window-plug arrangement of some sort, you'll still have to figure out how to make your blob stay in place.

Another idea would be to install room darkening blinds there, or don't do anything with it at all. Unfortunately, you're going to find the Roxul in between the walls, etc. will help with some mid-to-high frequencies (e.g. some human speech), but it won't have little to no effect on lower frequencies that traverse via your walls. This is why you see folks on AVS going to what the average person perceives to be extreme measures of sound proofing. To have a noticeable impact on LFE transmission, you need a physical separation between surfaces that can and do transmit sound. The purpose of plugging and damping windows is to add mass, which is your next best option for acoustic isolation.

With regards to potential resale issues, although pluging a window is unusual, IMHO it boils down to the details. If there's a reason why it's plugged, reversing it can be done, and the end result is positive, it shouldn't be an issue. Being able to speak to any concerns about them being plugged (such as how to deal with potential future repairs) goes a long way. OTOH, who says home buying is a 'reasonable', logical process???

I've got to plug 5 windows in my HT room. I could have opted to remove them and seal off the walls, but chose to use plugs in case a future owner would prefer to have an HT room with broad daylight streaming in from two different directions. In my case I'd describe them as "semi-permanent." That said, they _can _be removed. The key is to design your plugs such that removal or maintenance - while not a fun task - is a possibility.

I happen to have a friend w/a relative in the window repair business who reassured me it's possible to repair/replace the glass in them from the outside. I also took care to ensure that from the outside or street view, one can't tell they're plugged. So, IMHO, the Devil is in the Details as the saying goes. If something is important enough to you, it's often possible to find a resolution. And with regards to resale, I'm betting any future owner will be thrilled with the HT room they'll be getting and would prefer that over some windows. If not, it is a good idea to have an exit strategy though. In my case, I know how to 'un-do' the plugs if necessary, though I would not consider partially demo-ing my room without a signed contract and sufficient escrow to un-do the undoing if they backed out. After all, right now it's my house. If someone buys it in the future, when it is their house then they can decide what to do with it.


----------



## MidnightWatcher

Thanks HT Geek, lots to consider. I knew LFE would be near impossible to eliminate, so I can live with that. I'll be installing TTs to all seats to compliment adjusted LFE levels. As for noise coming in through the windows, I've no worries. The neighborhood is quiet and the theater will be used after sundown.


----------



## GatorBlues

Here's a quick update on the quietrock versus double drywall / green glue issue. We got our quote. Our theater is in the north Atlanta suburbs. It's about 18' by 22'. The quote indicated that QR installed will run roughly $2500 and DD/GG installed will be about $1600. So DD/GG it is. 

The quote raised another question. The subcontractor appears to be proposing clips, hat channel, and a single layer of 5/8 drywall as a solution to help soundproof the rest of the basement (the areas outside the theater) from the first floor. There won't be any subwoofers outside the theater, so would a single drywall layer with the clips and channel help much? Or do I still need a double layer to make it worthwhile?


----------



## Ladeback

GatorBlues said:


> Here's a quick update on the quietrock versus double drywall / green glue issue. We got our quote. Our theater is in the north Atlanta suburbs. It's about 18' by 22'. The quote indicated that QR installed will run roughly $2500 and DD/GG installed will be about $1600. So DD/GG it is.
> 
> The quote raised another question. The subcontractor appears to be proposing clips, hat channel, and a single layer of 5/8 drywall as a solution to help soundproof the rest of the basement (the areas outside the theater) from the first floor. There won't be any subwoofers outside the theater, so would a single drywall layer with the clips and channel help much? Or do I still need a double layer to make it worthwhile?


HT Geek could and probably will answer it better, but I think one layer of 5/8" with no clips would be enough on the outside walls of the theater or 2 layers or DW and GG. 

Here is what the Soundproofing Company suggest for wall solution 2.

http://www.soundproofingcompany.com/soundproof-walls/spc-02-soundproof-wall/


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## GatorBlues

Ladeback said:


> HT Geek could and probably will answer it better, but I think one layer of 5/8" with no clips would be enough on the outside walls of the theater or 2 layers or DW and GG.
> 
> Here is what the Soundproofing Company suggest for wall solution 2.
> 
> http://www.soundproofingcompany.com/soundproof-walls/spc-02-soundproof-wall/


I didn't word my prior post very well. I'm really looking at what to do with the ceilings in the rest of the basement. We are hoping to minimize noise in the basement from footsteps above (especially where the master suite on the main sits on top of the in-law suite in the basement), and also minimize noise from kids playing ping pong and air hockey (and otherwise making lots of noise) in the basement from reaching the first floor above. We also are leaning toward beefing up the long wall in the basement between the kids play area and the in-law suite. The link you provided gives STC ratings from: 

58 (clips, channel and one layer of drywall), to 

67 (clips, channel and DD/GG). 

With no subwoofers in the rooms at issue, is 58 sufficient for foot traffic above and play noise below? We will be insulating in the ceiling too, as the soundproofing website recommends.


----------



## Ladeback

GatorBlues said:


> I didn't word my post very well. I'm really looking at what to do with the ceilings in the rest of the basement, We are hoping to minimize noise in the basement from footsteps above (especially where the master suite on the main sits on top of the in-law suite in the basement), and also minimize noise from kids playing ping pong and air hockey (and otherwise making lots of noise) in the basement from reaching the first floor above. We also are leaning toward beefing up the long wall in the basement between the kids play area and the in-law suite. The link you provided gives STC ratings from:
> 
> 58 (clips, channel and one layer of drywall), to
> 
> 67 (clips, channel and DD/GG).
> 
> With no subwoofers in the rooms at issue, is 58 sufficient for foot traffic above and play noise below? We will be insulating in the ceiling too, as the soundproofing website recommends.


I have been told and it is on the website I sent you to help with noise above is to add mass to ceiling above. You can do that by putting up layers of 5/8" DW and GG, but I would think you may only need that in the theater. In my sister in laws house they finished there basement and can't hear the kids play above in the living room unless they are jump up and down. I don't know if they put insulation in the floor joist or not. I am planning on at least putting insulation in the ceiling of my basement above my game room. The rest of our living room and master bath and bedroom are above it and my wife has complained at times she can her my son with his friends playing in the basement. I am also only putting insulation in the ceiling of my theater. I am not doing DW & GG between the joist. I am also using clips and channel on the ceiling to decouple it.


----------



## HT Geek

I'd say it's a great idea for @GatorBlues to do clips on all the basement ceilings. Though since he's building from scratch, I'd suggest clips + 2x DW on the basement ceilings if possible. One layer is probably sufficient, but his only delta in cost will be 2x the drywall ceiling cost and a bit more labor (no need to mud and finish the first layer). If cost is an issue, spend the money on the clips and just do 1x drywall with them. Either way it's going to be money well spent for quiet and peace-of-mind. I'm just thinking adding another layer of drywall in the future will be much more expensive if he ever wants to do that.



Ladeback said:


> I have been told and it is on the website I sent you to help with noise above is to add mass to ceiling above.


That helps particularly with LFE, though de-coupling is the best line of defense when it's feasible. Adding mass is typically easier and relatively cheap. Just slap up another layer of drywall. But given the choice, I would de-couple first and get the ceiling off the floor joists/trusses, then add mass.



> You can do that by putting up layers of 5/8" DW and GG, but I would think you may only need that in the theater.


Depends on your goals, and the number / type of noise makers in your home. 

It gets a little tricky when talking about ceilings and floors vs. walls. For instance, impact noise often comes into play, whereas one normally doesn't have an issue with that and walls unless there's a big in-wall subwoofer on the other side of a wall. Mitigating impact noise is a bit different animal versus airborne.

The most important factor is defining a goal. If isolation from floor-to-floor or room-to-room is important (other than the HT room), we have to kick it up a notch. If the goal is mitigating typical house/kid/dog/family noises, I'd shift attention to factors such as what type of floor surfaces are in rooms above the basement? If they're tile, concrete, or hardwood, it will pay off to be a bit more aggressive with sound proofing below. Tile and bare concrete are the worst/most difficult to deal with.

It's possible to address the problem on the floor side as well, such as with cork or recycled rubber underlayments. However, this approach needs to be factored in carefully as it will raise the subfloor height (i.e. best to do it for the entire floor level of the home in question). If there's carpet / carpet pad / wood sub-floor above, then clips + 1x DW below is highly likely to be sufficient. Stuffing insulation in the floor joists will help as well (with voices, kid noises not involving jumping up and down). If you want to get real crazy, there are RIM solutions but they start at 1" depth and go up to 4" thick. The upside is you could drive a truck through your living room upstairs and never know it in the basement. 

If we focus on walls for a moment (even tho not directly applicable), look at this chart from SPC's website. You can see the biggest bang-for-your-buck is adding the IB-1 clips. When you add on to the benefits from those clips, the STC gain per additional layer of stuff is less than the bump up from no-clips to clips. STC should be taken with a grain of salt, but it is useful for back-of-the-envelope comparisons.











The chart above doesn't actually demonstrate the bene of @GatorBlues' proposed scenario (1x DW on clips), but we can extrapolate from the values derived from the 1x DW on clips both sides of wall (53 STC) and the 2x DW one side of wall (58 STC) that there's some significant value provided by the clips. Unfortunately, we can't use these values to get an accurate idea of how this would help with a ceiling/floor combo as it's a different beast. But the value of this data is that _yes, clips are worthwhile_.

What you're going to have different in the ceiling/floor scenario vs. walls are:

Wider air gap (joist/truss height) [good]
Hard surface attached to joists on one end (floor above) [bad]
Impact noise + airborne noise [bad]




> In my sister in laws house they finished there basement and can't hear the kids play above in the living room unless they are jump up and down. I don't know if they put insulation in the floor joist or not.


This is a great example of when impact noise comes into play. If you don't have a known source or potential source of impact noise, there's not much need to worry about it. If you do, it should be taken into consideration. Kids, dogs, high heels (on hard floor surfaces), etc. all frequently generate impact noise and vibrations. These will go right through a typical floor joist/truss system, hit the drywall ceiling in the basement below, and vibrate that and your basement wall studs.

This is where having a larger air gap and the isolation/spring action provided by the clips will really shine. Furthermore, adding more mass on either the transmit and/or receive side of the equation will help attenuate that impact noise. So, I do agree with @Ladeback that adding mass is a good thing.

Impact noise is measured as IIC (equivalent of STC but for impact noise). Like STC, higher numbers are better. The IIC measuring system is limited to a small group of frequencies (just like STC), but it's not a big deal as impact noise is always on the lower end of the freq spectrum anyway. Here are some examples of floor/ceiling combos with various floor materials above and standard 1x drywall ceiling attached below (ceiling attached to joists above):

Ceramic tile on wood sub-floor: IIC 40
1-1/2" thick concrete slab: IIC 40
Wood joist sub-floor, no floor covering: IIC 46
5/8" Plywood + 2x4 Wood Furring Strips + 1" Fiber Board: IIC 55-58
Carpet + carpet pad + plywood underlayment + floating 1-1/2" concrete slab: IIC >85

You can see that a concrete floor by itself (hopefully you won't have that) is awful. In fact it is just as bad as tile. Yet when one adds carpet, pad, and an underlayment (partly to prevent moisture buildup in the carpet pad), and "floats" the concrete slab, you have a terrific impact noise insulator. Even better, the concrete + carpet combo improves sound attenuation at all frequencies (i.e. airborne noise as well). So, there are a bunch of things you could do to the floor instead of the ceiling below that would improve the situation.




> I am planning on at least putting insulation in the ceiling of my basement above my game room. The rest of our living room and master bath and bedroom are above it and my wife has complained at times she can her my son with his friends playing in the basement. I am also only putting insulation in the ceiling of my theater. I am not doing DW & GG between the joist. I am also using clips and channel on the ceiling to decouple it.


I'll just add it's possible for sound from one floor to traverse to the other via other means as well, such as flanking noise through the walls, HVAC system, etc. Addressing the floor above or ceiling below will mitigate most of the sound, but likely not all of it. Treating floor/ceiling will address impact noise for sure, so if that is the main concern then you know it's going to be effective. 

DD/GG between joists - IMHO - only makes sense for a HT room unless you have an unusual circumstance (mother-in-law bedroom perhaps).  

If you've had issues with sound transmission between floors already, you may want to consider doing 2x DW on the ceiling clips. Personally, I'd skip the GG layer outside the theater room. That would keep your costs down and you probably don't need it in the remainder of the house. Or you could do 1x DW on the ceiling clips and if you're not satisfied with the results, add another layer later on. The downside of that approach is the time and labor required to finish the drywall (especially if it's textured), versus another +$10 per 32 sq. ft. of ceiling up front.

Don't forget to factor in any heavy light fixtures, if any are planned. You'll want to add extra clips in that area to support current/future plans.

*Edit*: Just noticed the chart above is 24" O.C. wood studs. The benefit of the clips will be even greater on 16" or 19.2" O.C. (depending on how your joists or trusses are laid out). If you have the option to use steel joists instead of wood, that would also improve the situation.


----------



## GatorBlues

Just FYI, I had a productive meeting with the builder today. It looks like we'll be going with RSIC-1 clips, hat channel, and double drywall/green glue throughout the entire basement for the ceiling and between certain key walls (like the one separating the in-law suite in the basement from the play areas). 

He's also building me 1 cubic foot speaker boxes (following the construction guide on the soundproofing company's website for building recessed lighting boxes) to help soundproof my in-ceiling whole house speakers, which will be hung in certain rooms between the ceiling joists with RSIC-DC04 clips.

And of course, thanks to advice received here a couple months ago, the theater is a room within in room and will have DD/GG as well. 

Thanks, @HT Geek, @jrref, and @Ladeback, for all of your help!


----------



## Ladeback

GatorBlues said:


> Just FYI, I had a productive meeting with the builder today. It looks like we'll be going with RSIC-1 clips, hat channel, and double drywall/green glue throughout the entire basement for the ceiling and between certain key walls (like the one separating the in-law suite in the basement from the play areas).
> 
> He's also building me 1 cubic foot speaker boxes (following the construction guide on the soundproofing company's website for building recessed lighting boxes) to help soundproof my in-ceiling whole house speakers, which will be hung in certain rooms between the ceiling joists with RSIC-DC04 clips.
> 
> And of course, thanks to advice received here a couple months ago, the theater is a room within in room and will have DD/GG as well.
> 
> Thanks, @HT Geek, @jrref, and @Ladeback, for all of your help!


Awesome, sounds like you have a builder who understands our hobby well. Wish I could of had the coin to do that before we moved in. You will have to start a build thread soon. Good luck.

Edit: I just seen your build thread and am checking it out.


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## doveman

doveman said:


> I had an e-mail back from Mason and they suggested using these 50x50x19mm pads, which are only £1.80+VAT and shipping, so probably not much different from the Canadian hockey pucks (and importing those could be expensive). http://www.masonuk.co.uk/sw16v2.pdf
> 
> They recommended placing them at 400mm centres under the floor and using two layers of 18mm ply for mass and rigidity, although I guess OSB would be just as good.
> 
> Those are going to be too high for me though, so I've e-mailed them back to explain I can only use 25mm or 38mm isolators and I'll see what they recommend.
> 
> As I need a smooth ply surface to stick the cork tiles to, using two layers of 18mm OSB with 2mm ply on top might be the cheapest option and with 38mm isolators would raise my floor height by 14mm and with 5mm cork tiles on top it would match the height of the adjoining kitchen floor, which is covered with 19mm of ply and vinyl.


Doh! I had a brain malfunction when reading the e-mail from Mason and thought the pads were 50mm high, when in fact they're only 19mm high, so I could use them. 

As the floor will need to be about 80mm deep to be level with the adjoining rooms, I'd have to use something like 3 layers of 18mm OSB + 2mm ply + 5mm cork tiles to achieve this, which is going to get a bit expensive as 12m2 of 18mm OSB costs about £70 * 3 = £210 + £200 for the cork tiles + £150 for the Foam Work pads comes to around £560, plus the ply, insulation, not to mention the labour makes it a bit OTT just to do the floor in one room! So I may have to settle for replacing the floorboards with one layer of OSB, 2mm ply and cork tiles and put up with the fact that there's a 12mm step between the rooms.


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## HT Geek

doveman said:


> Doh! I had a brain malfunction when reading the e-mail from Mason and thought the pads were 50mm high, when in fact they're only 19mm high, so I could use them.
> 
> As the floor will need to be about 80mm deep to be level with the adjoining rooms, I'd have to use something like 3 layers of 18mm OSB + 2mm ply + 5mm cork tiles to achieve this, which is going to get a bit expensive as 12m2 of 18mm OSB costs about £70 * 3 = £210 + £200 for the cork tiles + £150 for the Foam Work pads comes to around £560, plus the ply, insulation, not to mention the labour makes it a bit OTT just to do the floor in one room! So I may have to settle for replacing the floorboards with one layer of OSB, 2mm ply and cork tiles and put up with the fact that there's a 12mm step between the rooms.


If you want to consider performing the labor yourself, it's not difficult (provided you have a few power tools). 

Another option for materials would be to use furring strips in place of one layer of 18mm OSB, though I'm not sure you can find a furring strip in the exact size you'd need and I'd suggest a maximum distance between furring strips of 50cm O.C. Probably not enough savings to be worthwhile. You'll need at least 2 layers of OSB or plywood to prevent flex in the floor on top of the work pads and to provide sufficient support for the cork tiles.


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## doveman

HT Geek said:


> If you want to consider performing the labor yourself, it's not difficult (provided you have a few power tools).
> 
> Another option for materials would be to use furring strips in place of one layer of 18mm OSB, though I'm not sure you can find a furring strip in the exact size you'd need and I'd suggest a maximum distance between furring strips of 50cm O.C. Probably not enough savings to be worthwhile. You'll need at least 2 layers of OSB or plywood to prevent flex in the floor on top of the work pads and to provide sufficient support for the cork tiles.


I'm sure I could manage to lay, glue and screw the layers of OSB and I can probably get the 2.4mx1.2m boards cut to something more manageable like 1.2mx1.2m by the timber yard. The difficulty I'd have is with getting the boards here, as I don't drive or know anyone with a van and most suppliers seem to say that they'll only drop the boards off in the street, so whilst I'm carrying them upstairs to my flat one by one, someone could come along and nick the others! I guess I could hire a van and get a friend to drive me to the timber yard though and they can stay with the van whilst I carry the boards upstairs.

However I'd probably also struggle with grouting the isolators to the concrete, having no experience of doing this; ensuring the isolators are level and possibly having to level out the concrete slab somehow first; and disposing of the old floorboards and joists. I guess if I can prise up the floorboards ahead of time so that they're just lying loose on the joists then I might be able to quickly remove them the same day I pick up the OSB, so that I can use the van to take the waste to the tip but I'd have to do that before picking up the OSB as I don't have a spare room in my flat to store it. The order of business would be get rid of the floorboards and joists, then grout/level the isolators, then maybe leave them for a day to set before laying the OSB. That's logistically difficult, as I'd need the van on day 1 to get rid of the old flooring and again on day 2 or 3 to pick up the OSB, unless I can make space in my hall to store the OSB but it would have to be stored upright against the wall rather than flat, which I think is recommended. It probably won't be an issue not having any subfloor for a day or two as I can walk on the concrete slab between the isolators to get to the kitchen but even so, if a contractor can come and remove the old flooring and grout the isolators in place on day 1, then bring the OSB and lay it on day 2 that would obviously be a lot easier but as I said, it's all getting a bit expensive just for the living room floor, especially when I'm not sure how much difference it will make or whether I'm going to be able to treat the walls and ceiling in that room. I probably will do the ceiling but the walls are tricky in there.

When it comes to the HT room I'll be more concerned about getting the floor right but even then I'll need to limit how much I spend on the floor to ensure I have enough money to do the walls and ceiling.


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## HT Geek

doveman said:


> .... The difficulty I'd have is with getting the boards here, as I don't drive or know anyone with a van and most suppliers seem to say that they'll only drop the boards off in the street, so whilst I'm carrying them upstairs to my flat one by one, someone could come along and nick the others!....
> However I'd probably also struggle with grouting the isolators to the concrete, having no experience of doing this; ensuring the isolators are level and possibly having to level out the concrete slab somehow first; and disposing of the old floorboards and joists...., it's all getting a bit expensive just for the living room floor, especially when I'm not sure how much difference it will make or whether I'm going to be able to treat the walls and ceiling in that room. I probably will do the ceiling but the walls are tricky in there.
> 
> When it comes to the HT room I'll be more concerned about getting the floor right but even then I'll need to limit how much I spend on the floor to ensure I have enough money to do the walls and ceiling.


It's good you're thinking this through beforehand. You could save yourself a bit of coin if you do the demolition yourself, provided it's not too much trouble to take up the old floor, break it down, and haul it out. May be worth bribing a friend with free beer and food to make it go faster. You could get quotes with/without the demo phase from contractors and see how much coin you'd save.

Regarding the living room, the benefit is going to be quite limited if you don't address the floor, walls, and ceiling with a similar level of attention. Would it perhaps be wise to focus on just the HT room for now? Make sure you allow some room in your budget for any unforeseen complications that could be discovered once the demo starts. You never know what you'll find until you start knocking out walls, floors, etc.


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## mcgeebc

I am in the planning stages of finishing my basement. I'm planning to include a dedicated theater area. As such, I'd like to do what I can within reason to keep noise in and out of the basement from/to the upstairs. 

The house was built a few years ago. The basement is currently unfinished, but due to new fire codes, the builder drywalled the ceiling. That's going to make it difficult for us to run electric and plumbing. I'm trying to figure out what do do with the ceiling and have considered the following:

1) Tear down the drywall, run the electric and plumbing and rehang with clips and channels. Add another layer of drywall with GG.
2) Run electric and plumbing below the drywall and drop a suspended ceiling below. I can't find much information on suspended ceilings and soundproofing on this forum. Seems like with the existing drywall and drop ceiling tiles, I'd probably have decent results. I don't love the look of suspended ceilings, but I'm open to it if it means I don't have to tear down the existing drywall. 

As I read this forum and the "room within a room" concepts, I'm wondering if I have another option. Could I suspend another drywall ceiling below the current ceiling and run plumbing and electric in the cavity? Would that give me the "room within a room" benefits for soundproofing? Has anyone done that or have examples they can point me towards? 

We have very high ceilings in the basement, so that is not much of a concern.


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## HT Geek

mcgeebc said:


> I am in the planning stages of finishing my basement. I'm planning to include a dedicated theater area. As such, I'd like to do what I can within reason to keep noise in and out of the basement from/to the upstairs....
> 
> 1) Tear down the drywall, run the electric and plumbing


Do this ^^^^




> ... I'm wondering if I have another option. Could I suspend another drywall ceiling below the current ceiling and run plumbing and electric in the cavity? Would that give me the "room within a room" benefits for soundproofing?


No. That would do the opposite. You'd create what is a called a 'triple leaf.' Essentially, sound at certain frequencies is increased versus attenuated due to how the sound travels through the cavities and how it interacts with the solid wall/ceiling materials. 

You have two options to accomplish your goal: 1) The better of the two: tear out your existing ceiling and de-couple it. Since you have the height, I would suggest you do a floating ceiling. You'll then have plenty of room to run utilities, and from a sound-proofing standpoint it is superior to clips & channel. Cheaper as well. Stuff fiberglass insulation above and into your floor joists/trusses above. Option 2) add 1 or more layers of drywall to the existing ceiling. This is the fastest/cheapest route, but the benefit is lesser. 

If you're considering a R-w/in-a-R to begin with, it's likely you will be dissatisfied with the results from option 2.




> We have very high ceilings in the basement, so that is not much of a concern.


That will be to your benefit. Most folks have the opposite problem. However, that fact does not change the physics behind recommendations above.

Edit: Also de-couple your walls in the room or you'll get flanking noise travelling along the wall studs (and potentially other ways as well). Imagine you're building a secure bunker inside your home. That will set your mind in the right direction.


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## GatorBlues

*Speaker Backer Box*

Check out one of my speaker backer boxes for each in-ceiling speaker (picture attached). I had the builder follow the guidelines from soundproofing company's website for building a backer box for can lights ( http://www.soundproofingcompany.com/wp-content/uploads/2011/06/CIM-backer-box-installation-web.pdf ). It still needs to be lined with green glue and drywall on the interior of the box, and then the edges will be sealed with acoustical caulk. Lastly, the drywall will be attached to the flange on the box with acoustical sealant in between. The builder will take care of the rest of these steps tomorrow. It's hung between the joists with four RSIC-DC04 clips to isolate it from the joists. It's a cubic foot (interior dimensions) to avoid compromising the performance of the speaker. The orange thingy was to mark the spot of the wires and will be removed. If it works as planned, I'll be able to play music without disturbing those in the rooms above. Including wood, clips, and carpenter time, these cost me only about $50 per box.


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## HT Geek

Looks great. Is that Roxul behind it?

With 4 clips, you could probably do pullups off it. Not going anywhere! 

Sent from my ONE A2005 using Tapatalk


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## GatorBlues

HT Geek said:


> Looks great. Is that Roxul behind it?
> 
> With 4 clips, you could probably do pullups off it. Not going anywhere!
> 
> Sent from my ONE A2005 using Tapatalk


I think that's the subfloor for the next level that's a couple inches above the top of the box. It looks in the picture like they might be touching, but the builder (who sent me the picture) assures me it has clearance.


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## BasementBob

Triple Leaf
http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm


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## HT Geek

GatorBlues said:


> I think that's the subfloor for the next level that's a couple inches above the top of the box. It looks in the picture like they might be touching, but the builder (who sent me the picture) assures me it has clearance.


You're right. When I look at the pic on my PC, it's clearly the sub-floor. On my mobile phone, it had a greenish hue, and I couldn't see the detail on the 5" screen.


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## HT Geek

BasementBob said:


> Triple Leaf
> http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm


Bob, if you are trying to make a point, please state and it and don't just post a link. I find it very frustrating when people do that. It's like I'm on Facebook. Without an accompanying comment, no one knows what your point is, or your intent. That leads to open interpretation of others' thoughts, which is never a good idea. Again, I'm picturing Facebook.  Please elaborate so there's clear communication. Besides, you tend to have insightful comments. 

Just looking at that page - with no accompanying contextual explanation - I do see that the charts would appear to contradict some advice from SPC on triple leaf walls that has been widely discussed on this forum. In particular, above 200hz it looks good compared to the other methods. I'm also surprised at how poor the staggered stud wall is compared to the others above 200hz. However, missing from the page would be the context of the test environments. The doc links at the top of the page are broken.


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## Tyrindor

(Mini-rant)

Well today my contractors came with my 5/8 drywall. 89 sheets, roughly 9000 pounds of drywall. The problem? They ordered lightweight drywall! Had to tell them to load it all back up and bring me the real stuff. They couldn't understand why, and blamed me for "lack of communication" when I NEVER asked for lightweight. They knew the room was being soundproofed, why the frick would you get lightweight drywall which has 25-30% less mass?

If you have the money, hire a professional HT contractor because normal contractors do not understand this stuff.


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## deewan

@Tyrindor
Hopefully they are taking away the light drywall and bring back the heavy drywall free of charge. 

If they say they know how to install using GG, I would still believe them. They may have used GG many times, but with light weight drywall. They know the process, just not the preferred product. 

Reminds me of a neighbor. His daughter purchased a new car and after the first 1,000 miles they decided to change to oil which is often suggested with new engines (mileage varies based on who you ask). To save money he decided to do it himself. I asked him if he knew how to change the oil. He went on and on about how he knew what to do. A week later I see him taking out his recycling and see the empty 'new' oil containers. I asked him if those were the containers for his daughters oil change. He proudly said "yes" and that he got the oil changed in 40 minutes and didn't spill a drop. Well, the problem is his daughter's car recommends synthetic oil and he used regular dinosaur oil. He also used the wrong weight of oil. 

Technically he knew how to change the oil and completed the process correctly. He just used the wrong material/product. Could be the same as your drywall guys.


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## Tyrindor

deewan said:


> @Tyrindor
> Hopefully they are taking away the light drywall and bring back the heavy drywall free of charge.
> 
> If they say they know how to install using GG, I would still believe them. They may have used GG many times, but with light weight drywall. They know the process, just not the preferred product.
> 
> Reminds me of a neighbor. His daughter purchased a new car and after the first 1,000 miles they decided to change to oil which is often suggested with new engines (mileage varies based on who you ask). To save money he decided to do it himself. I asked him if he knew how to change the oil. He went on and on about how he knew what to do. A week later I see him taking out his recycling and see the empty 'new' oil containers. I asked him if those were the containers for his daughters oil change. He proudly said "yes" and that he got the oil changed in 40 minutes and didn't spill a drop. Well, the problem is his daughter's car recommends synthetic oil and he used regular dinosaur oil. He also used the wrong weight of oil.
> 
> Technically he knew how to change the oil and completed the process correctly. He just used the wrong material/product. Could be the same as your drywall guys.


Paying for it is my biggest concern, but i'll probably never know because the invoices usually aren't that detailed. I figure 89 sheets of drywall will likely run me about $3,000 - $5,500 after materials and labor based on what I've researched. It may be more because GG takes additional labor.

I bought 5x 5 gallon buckets of GG (knowing they'd charge me way more), and told them to do 2 tubes per 4x8 sheet, but they brought 4x12 sheets, so hopefully they don't mess it up. If I end up with a lot left over or not enough, than I'll know they messed up as I calculated the amount needed using the official GG calculator.


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## HT Geek

Tyrindor said:


> Paying for it is my biggest concern, but i'll probably never know because the invoices usually aren't that detailed. I figure 89 sheets of drywall will likely run me about $3,000 - $5,500 after materials and labor based on what I've researched. It may be more because GG takes additional labor.
> 
> I bought 5x 5 gallon buckets of GG (knowing they'd charge me way more), and told them to do 2 tubes per 4x8 sheet, but they brought 4x12 sheets, so hopefully they don't mess it up. If I end up with a lot left over or not enough, than I'll know they messed up as I calculated the amount needed using the official GG calculator.


Glad you got it sorted out and were there to oversee their activity. 

I believe the average cost of drywall for parts + labor, and including installation, mudding, and sanding is ~$1.50 psf. That's based on the rough room dimensions and accounts for some waste. You should be paying a bit less than that since your 1st layer won't require finishing (other than sealing the butt joints, which is not required but recommended). OTOH, the GG obviously adds some time, but it's not nearly as much work to squirt GG onto a panel vs. mudding and sanding, which is a royal P.I.T.A.


----------



## HT Geek

Tyrindor said:


> (Mini-rant)
> 
> Well today my contractors came with my 5/8 drywall. 89 sheets, roughly 9000 pounds of drywall. The problem? They ordered lightweight drywall! Had to tell them to load it all back up and bring me the real stuff. They couldn't understand why, and blamed me for "lack of communication" when I NEVER asked for lightweight. They knew the room was being soundproofed, why the frick would you get lightweight drywall which has 25-30% less mass?
> 
> If you have the money, hire a professional HT contractor because normal contractors do not understand this stuff.


So true. I feel bad for ya having that experience, but glad you were there to sort it out. It sounds as if that would have ruined the experience for you if you found out after the fact.

Unfortunately, this is a) why you have to watch contractors like a hawk and be available to oversee at least the beginning and end of each phase to ensure it's been done properly; b) why I've done all my labor myself; and c) why I'm still working on my HT room after >18 months.

I agree that hiring a true HT pro is ideal if you're going to hire the work out. They know what to do, what not to do, and how to solve the problems that will arise.

The vast majority of contractors mean well, but they are used to doing certain things in a way that benefits them (money and time), since 99% of their customers have no clue what they are doing. They only see the end result (and will don't see the imperfections many of them leave behind). I'm fortunate enough to have previously been a partner in a building materials manufacturing company, so I have 1st hand experience hiring and/or training guys who think they know what they are doing, but whose standards might not be up to mine and/or they are learning a new product/technique. Unfortunately, it's much akin to the car world (i.e. if you want to KNOW your oil was changed properly, best to do it yourself).


----------



## jrref

HT Geek said:


> So true. I feel bad for ya having that experience, but glad you were there to sort it out. It sounds as if that would have ruined the experience for you if you found out after the fact.
> 
> Unfortunately, this is a) why you have to watch contractors like a hawk and be available to oversee at least the beginning and end of each phase to ensure it's been done properly; b) why I've done all my labor myself; and c) why I'm still working on my HT room after >18 months.
> 
> I agree that hiring a true HT pro is ideal if you're going to hire the work out. They know what to do, what not to do, and how to solve the problems that will arise.
> 
> The vast majority of contractors mean well, but they are used to doing certain things in a way that benefits them (money and time), since 99% of their customers have no clue what they are doing. They only see the end result (and will don't see the imperfections many of them leave behind). I'm fortunate enough to have previously been a partner in a building materials manufacturing company, so I have 1st hand experience hiring and/or training guys who think they know what they are doing, but whose standards might not be up to mine and/or they are learning a new product/technique. Unfortunately, it's much akin to the car world (i.e. if you want to KNOW your oil was changed properly, best to do it yourself).


Again, this is the reason why I suggest to get the pre-made stuff such as quiet rock because otherwise you are going to have to watch the contractor like a Hawk to make sure he does everything right.


----------



## Tyrindor

Drywallers got here 5 hours late. 2 mexicans, no english. Definitely illegals. Can't even speak with them to ensure they do DD + GG correctly. Do they expect me to pay a normal drywall labor fee when I can't talk to my drywallers? 

I called the drywall company to ask when an english-speaking drywaller was coming, and my main contractor called me back an hour later and chewed my ass out. "It's not your place to call companies, that's my job, don't ever do it again!". I went off on him and told him if he raises his voice at me again, I'll find someone else to finish the rest of the project. He kept insisting that I was in the wrong for calling the company, and the conversation ended with me telling him I am not arguing about it anymore (then he hung up on me!). I'm a bit worried now he's going to screw me on the bill, and not sure if I should just fire him.

For now, going to see how well they install the drywall. If it looks sketchy I am going to call the main contractor back again, tell him to get these illegals out of here and fire his ass. Either way, I am not paying full labor for people that can't speak english. I wanted to oversee this project and communicate with them to ensure DD + GG is done correctly. 

What a damn headache. Has anyone else dealt with crap like this?


----------



## jrref

Tyrindor said:


> Drywallers got here 5 hours late. 2 mexicans, no english. Definitely illegals. Can't even speak with them to ensure they do DD + GG correctly. Do they expect me to pay a normal drywall labor fee when I can't talk to my drywallers?
> 
> I called the drywall company to ask when an english-speaking drywaller was coming, and my main contractor called me back an hour later and chewed my ass out. "It's not your place to call companies, that's my job, don't ever do it again!". I went off on him and told him if he raises his voice at me again, I'll find someone else to finish the rest of the project. He kept insisting that I was in the wrong for calling the company, and the conversation ended with me telling him I am not arguing about it anymore (then he hung up on me!). I'm a bit worried now he's going to screw me on the bill, and not sure if I should just fire him.
> 
> For now, going to see how well they install the drywall. If it looks sketchy I am going to call the main contractor back again, tell him to get these illegals out of here and fire his ass. Either way, I am not paying full labor for people that can't speak english. I wanted to oversee this project and communicate with them to ensure DD + GG is done correctly.
> 
> What a damn headache. Has anyone else dealt with crap like this?


Didn't you read the previous posts above?


----------



## Tyrindor

jrref said:


> Didn't you read the previous posts above?


Yes.. I expected normal contractors wouldn't be very experienced with soundproofing. I'm more talking about a contractor yelling at a customer and blaming them when things go wrong, hiring illegals that can't speak english, etc. That doesn't seem normal to me.

Also, is it true that lightweight drywall is considered the standard now? My contractor claims "lightweight is always used unless the customer specifically asks for heavy.". I am refusing to pay for the labor involved with the lightweight drywall shipment that they took back, and he's still claiming the fault was mine because "Standard 5/8 drywall" means lightweight. That's BS right?


----------



## doveman

HT Geek said:


> It's good you're thinking this through beforehand. You could save yourself a bit of coin if you do the demolition yourself, provided it's not too much trouble to take up the old floor, break it down, and haul it out. May be worth bribing a friend with free beer and food to make it go faster. You could get quotes with/without the demo phase from contractors and see how much coin you'd save.
> 
> Regarding the living room, the benefit is going to be quite limited if you don't address the floor, walls, and ceiling with a similar level of attention. Would it perhaps be wise to focus on just the HT room for now? Make sure you allow some room in your budget for any unforeseen complications that could be discovered once the demo starts. You never know what you'll find until you start knocking out walls, floors, etc.


I had a builder/carpenter have a look at my room the other day and he said that my floorboards were in good condition and I should keep them, that he could fix the squeaks and suggested just laying 6mm ply and using leveling compound to create a flat surface to stick the tiles to. Of course, he was just advising what would be simplest, not what would work from a soundproofing point of view. He gave a rough quote of £200 for the labour, £120 for the ply and £120 for the compound although he said I could get those myself and I've had a quick look and it seems I could get them cheaper than that. He also said the walls were in good condition and he could skim them all for about £200, which is probably reasonable but I'll get some other quotes.

I don't want to spend nearly £500 just to get a floor that looks a bit nicer though. Even if I trim the floorboards and joists back to ensure none are touching the wall and fit cork tiles, I'm sure impact noise is still going to travel via the joists into the concrete slab and into the walls which are joined to it. I want to be able to work out and jump around in there without having to worry that impact noise is travelling into the flat below and if I do most of the work myself I should be able to construct a new OSB sub-floor on isolator pads for about the same price or maybe even less.

He did say that if he takes the waste to the dump they charge him £75 for commercial waste, so if I'm taking up the old floor it will be best if I can cut the floorboards and joists down to a size that will fit in my friend's car and dump it myself. Although if I plan it well, I could hire a van and dispose of the waste and collect the OSB the same day. I'm trying to decide what the quickest way of cutting the floorboards will be, as I'll need to cut them across the joists, prise up each section, bang out the nails then lay them down again so that when I hire the van I can quickly lift them to dispose of. I've done small sections with a multitool but it was quite slow and I must have hit a nail at some point, as I ruined the blade! A mini circular saw with a titanium blade (in case I hit a nail) set to the depth of the floorboards (18mm) might be better.

To create a larger airgap, partly to raise the subfloor to the same level as the adjoining rooms and partly to provide space for 25mm rockwool, I'm thinking of just using 18mm spacers on top of the isolator pads, with two layers of 18mm OSB on top. If necessary I'll get a professional to lay a 3mm layer of levelling compound but I might be able to just stick the cork tiles to the OSB if the subfloor is fairly even.

Mason sent me an drawing for another project they did which has got some useful tips on laying the pads. It's just a bit too big to upload here so I've put it on my Dropbox in case it's of interest to anyone else.
https://www.dropbox.com/s/jz04vbyw5vawqrj/Cochlear Refurb - EAFM dwg.pdf?dl=0


----------



## HT Geek

doveman said:


> Mason sent me an drawing for another project they did which has got some useful tips on laying the pads. It's just a bit too big to upload here so I've put it on my Dropbox in case it's of interest to anyone else.
> https://www.dropbox.com/s/jz04vbyw5vawqrj/Cochlear Refurb - EAFM dwg.pdf?dl=0


I would recommend adding cross-bars to the furring strips. Otherwise it looks good.


----------



## BasementBob

HT Geek said:


> Bob, if you are trying to make a point, please state and it and don't just post a link. I find it very frustrating when people do that. It's like I'm on Facebook. Without an accompanying comment, no one knows what your point is, or your intent.



I was just supporting your post 2153 http://www.avsforum.com/forum/19-de...ndproofing-master-thread-72.html#post53786433
You mentioned Triple Leaf and described it a bit -- but pictures and examples are usually better and I had that really old link handy from back when I used to describe Triple Leaf every week, so I posted it in case mcgeebc wanted more details.


Usually I left the explanations and observations about the data, to the surrounding thread -- since context is useful. You seem to be doing a yeoman's work in that regard the past year or so.


The problem with triple leaf is the resonance between the smallest two air gaps, which is usually a low frequency (15hz to 80hz). An attribute of a good wall is one with the lowest possible resonance frequency -- triple leaf makes a mess of that. More mass lowers the resonance. A larger air gap lowers the resonance.
Other than that horrible effect (raising the resonance) which is particularly bad for home theatres because we have a bizarre amount of bass (relative to business office or nature), it's ok. The smaller the distance between the two air gaps, the higher that resonance frequency, and the closer it gets to the easily perceived frequencies of the loudness sound curve (human hearing is great at 1000hz or so, supposedly the primary frequency of a baby's cry).
Or to say the same thing another way, it's cheaper (less drywall) and increased soundproofing, to put only two leaves far apart rather than three or more more narrowly spaced between the walls -- and why not do it cheaper when it's also better and easier.


A newbie mistake of triple leaf is someone who has an existing wall, and rather than just screwing another layer of drywall on, which would raise the mass and lower the resonance -- someone instead screws resilient channel to the wall's drywall and then puts another layer of drywall on top of that. Bingo, triple leaf with a tiny air gap and an additional higher frequency resonance through the wall. This happens when someone hears in Home Depot that resilient channel is good for soundproofing, but doesn't know about triple leaf effects.


----------



## HT Geek

Tyrindor said:


> I called the drywall company to ask when an english-speaking drywaller was coming, and my main contractor called me back an hour later and chewed my ass out. "It's not your place to call companies, that's my job, don't ever do it again!". I went off on him and told him if he raises his voice at me again, I'll find someone else to finish the rest of the project. He kept insisting that I was in the wrong for calling the company, and the conversation ended with me telling him I am not arguing about it anymore (then he hung up on me!). I'm a bit worried now he's going to screw me on the bill, and not sure if I should just fire him.


I would. Get rid of them and move on. You have nothing to gain keeping him/them after that experience. Take the brief hit on your time and the inconvenience. You can't undo or ignore that type of experience. If he's a sub, I would give the GC an ultimatum. Give him 2 business days to put a better sub on the job for the same cost or tell him you're pulling the plug.

You have to see yourself as a general contractor or Project Manager and not a homeowner/customer. Imagine you are a VIP home builder. They want/need your business. You have the cash. If I were the GC, I would at best reassign the guy who spoke to you like that, and more likely fire him. That person is going to cost the company revenue - yours and/or other customers.


----------



## HT Geek

BasementBob said:


> I was just supporting your post 2153 http://www.avsforum.com/forum/19-de...ndproofing-master-thread-72.html#post53786433
> You mentioned Triple Leaf and described it a bit -- but pictures and examples are usually better and I had that really old link handy from back when I used to describe Triple Leaf every week, so I posted it in case mcgeebc wanted more details.
> 
> Usually I left the explanations and observations about the data, to the surrounding thread -- since context is useful.


Bob,

I figured as much. I probably should have kept my trap shut, but I wanted to ensure your point(s) were clear. I suppose I'm jaded from my experiences with Facebook. I can't stand that platform.

Back to the charts you linked to.... So, I was quite surprised to see the triple-leaf approach is not a complete loser from a soundproofing perspective. Clearly, it does hurt LFE as expected, but I was surprised the high freqs fare better than I expected. In this case, I'd imagine the OP would still not want to do a triple-leaf since it's a ceiling. OTOH, I'd have to go back and look at the NRC tests of floor/ceiling impact noise to see what the freqs are (I recall there were 3 or 4 main freq ranges but can't recall what they were). I can now imagine (after reviewing the charts you linked to), triple leaf might not be so bad under some circumstances.

It's amazing how rare absolutes are in this genre, and how important it is to evaluate the full picture of an HT-room's environment.




> You seem to be doing a yeoman's work in that regard the past year or so.


LoL. Thanks. 

The thread seemed as if it needed some attention, and assisting others helps push my learning envelope.


----------



## sdaveNC

HT Geek said:


> Bob,
> 
> 
> Back to the charts you linked to.... So, I was quite surprised to see the triple-leaf approach is not a complete loser from a soundproofing perspective. Clearly, it does hurt LFE as expected, but I was surprised the high freqs fare better than I expected. In this case, I'd imagine the OP would still not want to do a triple-leaf since it's a ceiling. OTOH, I'd have to go back and look at the NRC tests of floor/ceiling impact noise to see what the freqs are (I recall there were 3 or 4 main freq ranges but can't recall what they were). I can now imagine (after reviewing the charts you linked to), triple leaf might not be so bad under some circumstances.
> 
> It's amazing how rare absolutes are in this genre, and how important it is to evaluate the full picture of an HT-room's environment.


This is a timely discussion on triple leaf effect as I am finishing insulation and sheathing in my bonus room build. The wall construction will be 5/8 DD with GG on clips and channel 2x4 construction. I sheathed the back of the wall or "second leaf" with 19/32 OSB leaving another air cavity then finally the third leaf being the roof (OSB w asphalt shingles). 

I know the larger the air space the lower the resonance. The question is, at what size does the triple leaf air cavity go from being a soundproofing negative to neutral or a positive? The space behind the wall is 6.5ft tall x 5.5ft wide x 28ft deep with a sloped ceiling so roughly 500 ft3 not counting insulated space inside the 2x8 rafters. 

My assumption is the air space is large enough that I will not experience the typical triple leaf negatives in the higher frequencies. If there are negative effects they could be mitigated by further stuffing that cavity to lower the resonance. Am I off base with my thought process or do I need to rip the OSB down?


----------



## HT Geek

sdaveNC said:


> This is a timely discussion on triple leaf effect as I am finishing insulation and sheathing in my bonus room build. The wall construction will be 5/8 DD with GG on clips and channel 2x4 construction. I sheathed the back of the wall or "second leaf" with 19/32 OSB leaving another air cavity then finally the third leaf being the roof (OSB w asphalt shingles).
> 
> I know the larger the air space the lower the resonance. The question is, at what size does the triple leaf air cavity go from being a soundproofing negative to neutral or a positive? The space behind the wall is 6.5ft tall x 5.5ft wide x 28ft deep with a sloped ceiling so roughly 500 ft3 not counting insulated space inside the 2x8 rafters.
> 
> My assumption is the air space is large enough that I will not experience the typical triple leaf negatives in the higher frequencies. If there are negative effects they could be mitigated by further stuffing that cavity to lower the resonance. Am I off base with my thought process or do I need to rip the OSB down?


Are you saying you have this order of materials (starting inside your HT room)?

DW | GG | DW | CLIPS & CHANNEL | 2x4 STUD | OSB | LARGE AIR CAVITY | ANGLED ROOF SHEATHING (OSB)


----------



## sdaveNC

HT Geek said:


> Are you saying you have this order of materials (starting inside your HT room)?
> 
> DW | GG | DW | CLIPS & CHANNEL | 2x4 STUD | OSB | LARGE AIR CAVITY | ANGLED ROOF SHEATHING (OSB)


Exactly. The clips, channel, DD, and GG are not installed yet.


----------



## HT Geek

sdaveNC said:


> Exactly. The clips, channel, DD, and GG are not installed yet.


It doesn't seem like a big deal to me. The outer OSB is the same as a DW layer if this were an interior wall. The cavity is a decent size, and more importantly the roof is the outer layer, with an infinite air gap beyond that (outside).

I'm not sure how the angle will affect things, but I still don't see anything to worry about. On the off-chance you were to get any sort of resonance between the OSB panels, it ought to be mitigated significantly by the DD/Clips on the interior side. I doubt that would even be an issue. Concerns with triple leaf typically stem from adding a double stud wall without first removing the HT-room side drywall layer on the original (structural) studs.

Others who know more than me could have differing opinions, but I'd say you're GTG.


----------



## sdaveNC

HT Geek said:


> Others who know more than me could have differing opinions, but I'd say you're GTG.


Sounds good to me. Thanks for the help.


----------



## jln1980

*Sanity check*

finalizing plans to my home theater build 8/1 but I need some advice. I have read and read soundproofing post and talked to the Soundproofing Company. I keep going back and fourth on what level of soundproofing I need. So before I spend 3K on soundproofing materials and install i need a sanity check.

Green glue and double drywall 1500-1600 installed
Clips and channel 1300 installed
or both for around 3k

Rooms is 13-9L x 18-7D - 8 foot ceilings

Whats my biggest bang for the buck? 

Pink or Roxul?

Thanks in advance


----------



## TTC

Hi, everyone -


I've been trying to come up with a way to soundproof the entry to the HT but I still want the large entry for when we're having a gathering and/or watching the games where people can hang out in the theater room and in the game room at the same time. 


I'm thinking about building a double wall (from inside the HT to the game: 5/8 drywall, GG, 5/8 drywall, 2x4 studs with Roxul SnS, 1/2 drywall, space, 1/2 drywall, 2x4 studs with Roxul SnS, 5/8 drywall) and have pocket door sliding in/out between these walls. On the outside wall of the HT, have a nice, thick sliding barn door for additional sound blockage. Please see the attached drawing.


Will this help in anyway or is this a stupid idea and I should come up with something else?

Thanks,
TTC


----------



## HT Geek

jln1980 said:


> finalizing plans to my home theater build 8/1 but I need some advice. I have read and read soundproofing post and talked to the Soundproofing Company. I keep going back and fourth on what level of soundproofing I need. So before I spend 3K on soundproofing materials and install i need a sanity check.
> 
> Green glue and double drywall 1500-1600 installed
> Clips and channel 1300 installed
> or both for around 3k
> 
> Rooms is 13-9L x 18-7D - 8 foot ceilings
> 
> Whats my biggest bang for the buck?
> 
> Pink or Roxul?


That sounds too cheap to me. In the U.S., typical DW install rates is ~$1.50 psf. The cost varies by metro location, based mostly on labor cost.

Looking at rough numbers, you've got ~1,000 sq ft of drywall surface area. Your first layer of drywall should be dirt cheap as no mudding and sanding is required. Just make sure they overlap the seams (and you can have them mud but not sand the seams if you want be diligent about it, but I would be inclined to save the $ and not worry about it). Point is your first layer is going to be light on the labor cost but 90% of the materials cost of the 2nd layer. I'd estimate $2000 - 2500 for the drywall alone. 

Continuing my back-of-the-envelope estimate, adding the cost of Green Glue (say, 3x 5-gallon buckets), we're talking ~$750-800 for GG (considering potential shipping costs).

Then add hat channel + clips + labor, depending on which clips you go with the cost will vary from ~$2-7 per clip. Let's say you need 100 clips (there are calculators online, but I'm gonna just pick a number for purpose of this discussion). That's a median cost of $450 for clips. Hat channel is cheap. Add some screws. Another $200 or so. Then add labor, which is very difficult to predict. Most contractors have not worked with hat channel and clips before, and they will likely overestimate just to make sure they don't come up with the short stick.

So, bottom line is I'm coming up with a ballpark cost of $4,000+ for clips, hat channel, double drywall, and green glue, all parts delivered and installed. I think $4,500 is a relatively good estimate. Please bear in mind all my room's labor was performed by me _in suum_.

Regarding insulation, use whichever is cheaper (typically pink fluffy). The difference in performance is negligible.


----------



## TTC

Hey, jln1980 -


I'm in the same boat with you. I have a very limited budget to soundproof my new HT and want the biggest bang for the bucks. I'm hoping to only spend between $2,000 to $3,000. Even though I haven't really priced out all the material nor finalized my plan, but as of right now, this price range doesn't seem possible.


Here's my current plan (HT will be on the second floor):


Floor - insulate the floor with Roxul SnS, 3/4" T&G glued/screwed to joist, GG, 3/4" T&G


Three Walls to the Outside: Roxul Comfortbatt R-15 (I'm in the South, only need R-13 min.), 5/8" drywall, GG, 5/8" drywall


Inside Wall: double wall consist of from the HT to the game room - 5/8" drywall, GG, 5/8" drywall, 2x4 studs with Roxul SnS, 1/2" drywall, space, 1/2" drywall, 2x4 studs with Roxul SnS, 5/8" drywall


I've also looked in the one-legged resilient channels and seems like that product can fail easily (screwed to the stud, not leaving enough gap between the ends, hanging pictures to the walls, etc.). The resilient clips with the furring/hat channels seem to be a better way to go but those clips are so expensive, between $5-$7. For my project, I think I needed around 200+ of them.


I'm also planning to float the entire room on the U-Float rubber clip. They're about $2 each but I'm not sure how much I need yet.


Good luck with your HT! 

Regards,
TTC


----------



## HT Geek

TTC said:


> Hi, everyone -
> 
> 
> I've been trying to come up with a way to soundproof the entry to the HT but I still want the large entry for when we're having a gathering and/or watching the games where people can hang out in the theater room and in the game room at the same time.
> 
> 
> I'm thinking about building a double wall (from inside the HT to the game: 5/8 drywall, GG, 5/8 drywall, 2x4 studs with Roxul SnS, 1/2 drywall, space, 1/2 drywall, 2x4 studs with Roxul SnS, 5/8 drywall) and have pocket door sliding in/out between these walls. On the outside wall of the HT, have a nice, thick sliding barn door for additional sound blockage. Please see the attached drawing.
> 
> 
> Will this help in anyway or is this a stupid idea and I should come up with something else?


Two thoughts:

1. Don't put drywall on the inside of the pocket door air cavity (you'll create a triple leaf, which will make your bass blocking attempts less effective)
2. The pocket door and barn door will leak sound like a sieve

Hate to tell you this, but I would not recommend the approach you've outlined if your goal is isolation. There's no good way of having your cake and eating it at the same time. The best approach is to decide which is a higher priority: sound isolation of the HT room versus open room concept.


----------



## deewan

HT Geek said:


> Two thoughts:
> 
> 1. Don't put drywall on the inside of the pocket door air cavity (you'll create a triple leaf, which will make your bass blocking attempts less effective)
> 2. The pocket door and barn door will leak sound like a sieve
> 
> Hate to tell you this, but I would not recommend the approach you've outlined if your goal is isolation. There's no good way of having your cake and eating it at the same time. The best approach is to decide which is a higher priority: sound isolation of the HT room versus open room concept.


 @TTC have you considered double, double doors? One set of heavy duty double doors with sound seals that open to the game room side and one set of double doors that open to the theater side? You lose a lot of floor space for the swing of the doors, but you could likely get better sound isolation with a set of double, double doors. Just a thought.


----------



## TTC

HT Greek, 


Thanks for the quick response.


You're right about don't add the drywall in between the two walls. I don't know what I was thinking.


Sigh...I like the look at the large doors and I was hoping that my idea would trap some sound/bass. I might just end up adding a solid 3' door instead since I like it kinda loud when I'm watching a movie.


I started looking at your built thread and it's turning out really nice. Your plan is almost exactly how I vision my HT to be like (soffit with the overhang, two levels, stage, room size). I'm in Texas as well but my HT will be over the kitchen, nook, and family room, instead over the garage. So, my first priority is to soundproof the floor, preventing the sound, especially the low frequency, from traveling downward. My wife would be pissed if the bass from the HT somehow knock out one the recessed lights in the kitchen.


----------



## TTC

Hi, Deewan -


Thanks for your suggestion but yes, I have considered the double door option. The issues I'm concern with are the size (too small) and that one of the doors will swing inside the HT. I'm okay with the one swinging in to the game room. I could possibly replace the sliding barn door with a swing/sealed door and keep the pocket door? That would probably help with the sound but the picture in my head, it'll look kind of weird.


TTC


----------



## jln1980

HT Geek said:


> That sounds too cheap to me. In the U.S., typical DW install rates is ~$1.50 psf. The cost varies by metro location, based mostly on labor cost.
> 
> Looking at rough numbers, you've got ~1,000 sq ft of drywall surface area. Your first layer of drywall should be dirt cheap as no mudding and sanding is required. Just make sure they overlap the seams (and you can have them mud but not sand the seams if you want be diligent about it, but I would be inclined to save the $ and not worry about it). Point is your first layer is going to be light on the labor cost but 90% of the materials cost of the 2nd layer. I'd estimate $2000 - 2500 for the drywall alone.
> 
> Continuing my back-of-the-envelope estimate, adding the cost of Green Glue (say, 3x 5-gallon buckets), we're talking ~$750-800 for GG (considering potential shipping costs).
> 
> Then add hat channel + clips + labor, depending on which clips you go with the cost will vary from ~$2-7 per clip. Let's say you need 100 clips (there are calculators online, but I'm gonna just pick a number for purpose of this discussion). That's a median cost of $450 for clips. Hat channel is cheap. Add some screws. Another $200 or so. Then add labor, which is very difficult to predict. Most contractors have not worked with hat channel and clips before, and they will likely overestimate just to make sure they don't come up with the short stick.
> 
> So, bottom line is I'm coming up with a ballpark cost of $4,000+ for clips, hat channel, double drywall, and green glue, all parts delivered and installed. I think $4,500 is a relatively good estimate. Please bear in mind all my room's labor was performed by me _in suum_.
> 
> Regarding insulation, use whichever is cheaper (typically pink fluffy). The difference in performance is negligible.


Sorry I should have specified these are quoted prices. Green glue and double drywall 1500-1600 installed only factors in the 2nd layer and the green glue. The finishing of the drywall is over and above the 1500-1600. 

I'm trying to determine do i need to go all in and do DD, green glue and clips or just do DD and green glue.


----------



## HT Geek

*Need more info*



jln1980 said:


> I'm trying to determine do i need to go all in and do DD, green glue and clips or just do DD and green glue.


What are your goals?

It really depends on the answer to that ^ question. There aren't many absolutes in the A/V world. Much depends on your ideals and the minimum viable solution that will meet your needs. 

Here are a few important questions that will help narrow down the answer to your question:

1. On which floor of your home will the HT room be located?
2. What is directly above, below, and beside the room?
3. Do you know the default construction materials of the room? (e.g. concrete wall on east side, 2x4 wood stud wall w/1x drywall both sides and no insulation on west wall, etc.)?
4. Room dimensions (and specify roughed in or finished if known)
5. What are your goals for sound volume outside the HT room, in adjacent spaces?
6. Floor/Ceiling construction type if known (e.g. floor trusses, ceiling joists 2x12 24" O.C., etc.)


----------



## deewan

TTC said:


> Hi, Deewan -
> 
> 
> Thanks for your suggestion but yes, I have considered the double door option. The issues I'm concern with are the size (too small) and that one of the doors will swing inside the HT. I'm okay with the one swinging in to the game room. I could possibly replace the sliding barn door with a swing/sealed door and keep the pocket door? That would probably help with the sound but the picture in my head, it'll look kind of weird.
> 
> 
> TTC


A barn door will do very little to isolate sound unless when it's closed it can somehow create a seal with the wall. Any air gap is a freeway for sound to escape. Simply adding a door will muffle sound in the theater a little on the game room side, but I wouldn't consider it for sound isolation.


----------



## HT Geek

TTC said:


> You're right about don't add the drywall in between the two walls. I don't know what I was thinking.


It can be done, but it will make the bass transmission outside the room more notable. This is why it's generally recommended to avoid doing that and tear it out first.



> Sigh...I like the look at the large doors and I was hoping that my idea would trap some sound/bass. I might just end up adding a solid 3' door instead since I like it kinda loud when I'm watching a movie.


Vault doors work well. 

A 3-4' communicating door space works really well if you have the room. My solution was to use 2x 32" doors glued and screwed together using Green Glue, but there are a myriad of ways to solve the problem depending on how much room you have. I couldn't do a communicating door setup without creating a room egress problem or shrinking the length (or width) of my room. I chose to compromise some sound leakage in exchange for a larger room. I figured when I have the volume cranked up, I won't be able to hear my wife complaining from downstairs.




> I started looking at your built thread and it's turning out really nice. Your plan is almost exactly how I vision my HT to be like (soffit with the overhang, two levels, stage, room size). I'm in Texas as well but my HT will be over the kitchen, nook, and family room, instead over the garage. So, my first priority is to soundproof the floor, preventing the sound, especially the low frequency, from traveling downward. My wife would be pissed if the bass from the HT somehow knock out one the recessed lights in the kitchen.


Well, I'll share what I've learned about 2nd floor theaters and their flooring from my experience:

1. I've found my garage has created a minor environmental challenge in the HT room. In the summer the heat below migrates up into the room a bit (not much, but I notice the difference vs. remainder of 2nd floor); likewise with cold in the winter.
2. If I were to do it over, I would either rip up the original sub-floor and install U-boats on the floor trusses below, or lay a product similar to RIM over the original sub-floor, and build up the room's floor on top of that (latter would be preferable as it's less work and materials).
3. I can barely hear, and certainly feel one of my garage door openers that is directly below where my front chairs are going to be. Once my carpet and pad are in, that issue should reduce somewhat, but it bothers me. I plan to address this issue by isolating the garage door openers with clips.

So, my concerns for your situation would be.....

* You've got to invest significant thought in how to isolate your floor from the trusses or joists below it
* Make sure you have at least a rudimentary understanding of building codes and how they relate to the structural requirements of your room as it was originally built; for instance, depending on when your home was built, a bedroom should have a minimum support of 30 psf in the floor; almost any other room is 40 psf minimum. However, that's total load. It gets a bit complicated, but those total load numbers are a good figure to keep in mind when you're adding weight in the form of various materials.
* You also must address your studs in the HT room as they will transmit bass downstairs very efficiently

Isolating the walls is pretty straightforward: clips & channel, double stud (inner wall), or staggered stud wall + double drywall on the inside, ideally with a viscoelastic material between layers (e.g. Green Glue). To accomplish your goals relative to downstairs, your best bet is double stud or clips & channel.

I'd suggest you also isolate your ceiling, but it's less important. If you adhere your ceiling to the current/structural ceiling joists, some of the bass in particular will travel along them to the structural wall studs and downstairs, but it will be much less sound vs. the other potential leakage areas. If you want to save a little $, that is one area where you could do it. That is what I chose to do, in part because I have a large air space (attic) above the room. I also used 3x layers of drywall with Green Glue on the ceiling, except where the soffits are (the ceilings above the soffits are 2x drywall w/GG, and the soffits themselves are DW+MDF w/GG on bottom and sides, with fiberglass insulation inside. I'm personally not concerned with my ceiling arrangement. I should mention my room also shares only 1 wall with the remainder of the home. All other walls are exterior or attic, which was also a factor for me as well. If your walls are all or mostly internal, it would push me in the direction of ceiling isolation vs. damping only (my approach).

If you could upload photos of your current room, you'll likely get more input from members here. Also see if you can figure out what your room's floor is made of (e.g. floor trusses or joists), including the characteristics (e.g. 2x4 trusses, 14" tall, 24" on center).

Hope that helps a bit. Careful planning now will benefit you greatly when it's done.


----------



## HT Geek

deewan said:


> A barn door will do very little to isolate sound unless when it's closed it can somehow create a seal with the wall. Any air gap is a freeway for sound to escape. Simply adding a door will muffle sound in the theater a little on the game room side, but I wouldn't consider it for sound isolation.


^^^ What he said. 

The keys are mass of the door and sealing the gaps all doors have with gaskets (e.g. automatic door bottom), while still allowing it to be useful as a door.


----------



## jln1980

HT Geek said:


> What are your goals?
> 
> It really depends on the answer to that ^ question. There aren't many absolutes in the A/V world. Much depends on your ideals and the minimum viable solution that will meet your needs.
> 
> Here are a few important questions that will help narrow down the answer to your question:
> 
> 1. On which floor of your home will the HT room be located?
> 2. What is directly above, below, and beside the room?
> 3. Do you know the default construction materials of the room? (e.g. concrete wall on east side, 2x4 wood stud wall w/1x drywall both sides and no insulation on west wall, etc.)?
> 4. Room dimensions (and specify roughed in or finished if known)
> 5. What are your goals for sound volume outside the HT room, in adjacent spaces?
> 6. Floor/Ceiling construction type if known (e.g. floor trusses, ceiling joists 2x12 24" O.C., etc.)


Goals I want a theater that sounds great and has a big picture. I'm not looking to play movies at ref volumes. 

1. On which floor of your home will the HT room be located? Basement
2. What is directly above, below, and beside the room? Closet above, single bed room beside with a closet that runs the width between the bed room and the theater room.
3. Do you know the default construction materials of the room? (e.g. concrete wall on east side, 2x4 wood stud wall w/1x drywall both sides and no insulation on west wall, etc.)? Concrete front and 1 side wall. other 2 Walls will be 2x4
4. Room dimensions (and specify roughed in or finished if known) 13'9"x 18'7"
5. What are your goals for sound volume outside the HT room, in adjacent spaces? I have never had a space like this so i'm not sure whats reasonable. 80% of the time the whole family will be watching the movie together.
6. Floor/Ceiling construction type if known (e.g. floor trusses, ceiling joists 2x12 24" O.C., etc.) floor trusses


----------



## HT Geek

jln1980 said:


> 2. What is directly above, below, and beside the room? Closet above, single bed room beside with a closet that runs the width between the bed room and the theater room.
> 4. Room dimensions (and specify roughed in or finished if known) 13'9"x 18'7"


That's a big closet above!

If the bedroom will be used on a regular basis (i.e. family member and not a guest room), I'd be very inclined to go with the clips & channel, to prevent disturbing someone's sleep while preserving the ability to use the HT room at the same time at reasonable volumes. If you have a child who thinks their bedroom is a jungle gym at times, you might have issues with sound in the reverse direction (coming into the HT room). Even with DD, you will likely hear impact noise from above w/out the clips.

But it's such a subjective matter (solutions that will meet your minimum standards). I can give you my opinion, but it's just another subjective viewpoint. 

If I were in your shoes, I would spring for the clips & channel. I hate to promote spending more $, but quite frankly it's an investment (in you and your family's personal enjoyment of your room), and the cost of retrofitting your room in the future is prohibitive if you don't do it and decide later on you wish you had (you'd have to demo the room and effectively start over).

Another option is to do the clips & channel and only 1 layer of drywall. However, you don't save much $ in doing so. You save the cost of Green Glue and a single layer of drywall that doesn't require finishing. I'd estimate you would save $1,500 - $1,800 with that approach. If you decided to add a 2nd layer of drywall in the room + GG later on, you're looking at $2,500 or so. If you're comfortable with possibly spending an extra $1,000 down the road, this could be a viable choice for you. Put the clips in now and see what you think of the result. To retrofit clips with GG later on will likely be more like a $6,500 - $7,500 job since it would require demo'ing the original installation, site prep, and then adding all the parts.

I feel confident saying no one is going to regret using clips but might regret not using them. If you're sure that bi-directional extraneous sounds won't be emanating between your HT room and the living areas above and around them, it's logical to think of saving $ and skipping the clips & channel. The question is, are you comfortable with the consequences if you're mistaken??? 

One more idea for you: consider double stud walls and a floating ceiling. You lose ~6" of room height and ~1' L and W of room dimensions, but it's cheaper. Materials are less. Labor is less.

If you're still on the fence after those comments, ponder what type of films, music, games, etc. you watch/listen to/play. Imagine when your kids are older and they don't want to hang out with you and your wife as much, and you two are watching a film in the HT with some quiet scenes. Will you be bothered by the sound of raucous teens in another part of your home? Will that disturb your experience?


----------



## jln1980

HT Geek said:


> That's a big closet above!
> 
> If the bedroom will be used on a regular basis (i.e. family member and not a guest room), I'd be very inclined to go with the clips & channel, to prevent disturbing someone's sleep while preserving the ability to use the HT room at the same time at reasonable volumes. If you have a child who thinks their bedroom is a jungle gym at times, you might have issues with sound in the reverse direction (coming into the HT room). Even with DD, you will likely hear impact noise from above w/out the clips.
> 
> But it's such a subjective matter (solutions that will meet your minimum standards). I can give you my opinion, but it's just another subjective viewpoint.
> 
> If I were in your shoes, I would spring for the clips & channel. I hate to promote spending more $, but quite frankly it's an investment (in you and your family's personal enjoyment of your room), and the cost of retrofitting your room in the future is prohibitive if you don't do it and decide later on you wish you had (you'd have to demo the room and effectively start over).
> 
> Another option is to do the clips & channel and only 1 layer of drywall. However, you don't save much $ in doing so. You save the cost of Green Glue and a single layer of drywall that doesn't require finishing. I'd estimate you would save $1,500 - $1,800 with that approach. If you decided to add a 2nd layer of drywall in the room + GG later on, you're looking at $2,500 or so. If you're comfortable with possibly spending an extra $1,000 down the road, this could be a viable choice for you. Put the clips in now and see what you think of the result. To retrofit clips with GG later on will likely be more like a $6,500 - $7,500 job since it would require demo'ing the original installation, site prep, and then adding all the parts.
> 
> I feel confident saying no one is going to regret using clips but might regret not using them. If you're sure that bi-directional extraneous sounds won't be emanating between your HT room and the living areas above and around them, it's logical to think of saving $ and skipping the clips & channel. The question is, are you comfortable with the consequences if you're mistaken???
> 
> One more idea for you: consider double stud walls and a floating ceiling. You lose ~6" of room height and ~1' L and W of room dimensions, but it's cheaper. Materials are less. Labor is less.
> 
> If you're still on the fence after those comments, ponder what type of films, music, games, etc. you watch/listen to/play. Imagine when your kids are older and they don't want to hang out with you and your wife as much, and you two are watching a film in the HT with some quiet scenes. Will you be bothered by the sound of raucous teens in another part of your home? Will that disturb your experience?


Thank you.

Everything i have read says that you have to do backer boxes for recessed lights. I hate to do clips and DD with GG and lose the effectiveness by having can lights any way around backer boxes? I plan to have 6 can lights. If I skip the backer boxes how mush of an impact will i see from that?

I would also like to do in wall and ceiling speakers for my surrounds channels. I just keep cutting holes in my soundproof box.


----------



## EC

I designed / built my HT so there is no lighting in the ceiling to minimize the holes in the ceiling as above the HT is a kitchen and living room with piano. All the lighting are low profile LED lights along the two long walls using standard octagon boxes with puddy on the back to minimize sound leak.


----------



## HT Geek

*Backer Boxes*



jln1980 said:


> Thank you.
> 
> Everything i have read says that you have to do backer boxes for recessed lights. I hate to do clips and DD with GG and lose the effectiveness by having can lights any way around backer boxes? I plan to have 6 can lights. If I skip the backer boxes how mush of an impact will i see from that?
> 
> I would also like to do in wall and ceiling speakers for my surrounds channels. I just keep cutting holes in my soundproof box.


I would do backer boxes whether you use clips and channel or not. For in-wall and ceiling speakers, that's the ideal method. If you skip the backer boxes but you have the clips & hat channel, the impact will be more or less the same versus not using clips & channel, because it's primarily an issue of flanking noise through the speakers and fixtures that is the concern. Clips and backer boxes are solving two independent problems.

Alternative options to DIY backer boxes include mounting in-wall speakers inside columns, and I have seen a room with Atmos speakers bolted to the ceiling and exposed in the room. The latter was in a room with a tall ceiling. They were not particularly obtrusive, but they were visible. When the lights are out, no one sees them.

The impact of not building backer boxes varies. What essentially happens is some sound is able to travel through holes in them (especially light fixtures), and you'll get some resonance in either that will transmit into the walls/joists/etc. Basically, you introduce a flanking path when they don't have backer boxes.

Something to consider is there are speakers built with backer boxes of sorts. The best in-wall and in-ceiling speakers are designed as such. Purists will recommend you still put these in backer boxes as well, just because DIY backer boxes are heavy and you KNOW they are built to do their job, whereas a factory box is a bit of an unknown variable.

Here's an example of a Triad speaker with an integrated backer box. You can see it's made of wood.











Here's a Snell in-wall. It has an aluminum backer box (you can't really tell from this photo, and I could not find a good photo online of the rear).











And here's a metal after-market backer box. I don't recommend these. They're typically light weight and are more likely to increase resonance and muddiness in the sound, reverberate, etc.











Here is your worst-case scenario: an in-wall with no factory backer box at all. It's like creating a giant hole in your wall.











When you build your own, you are able to control its mass and seals. Here's a photo of Dozer's backer box construction. 











DIY backer boxes are typically made of an OSB or MDF shell and lined with cement backer board, though drywall can be used. I recommend Green Glue between layers. It needs to be a bit larger than whatever you want to put in it so that your speaker does not physically contact it directly. They are quite heavy when completed.


----------



## Ladeback

HT Geek said:


> I would do backer boxes whether you use clips and channel or not. For in-wall and ceiling speakers, that's the ideal method. If you skip the backer boxes but you have the clips & hat channel, the impact will be more or less the same versus not using clips & channel, because it's primarily an issue of flanking noise through the speakers and fixtures that is the concern. Clips and backer boxes are solving two independent problems.
> 
> Alternative options to DIY backer boxes include mounting in-wall speakers inside columns, and I have seen a room with Atmos speakers bolted to the ceiling and exposed in the room. The latter was in a room with a tall ceiling. They were not particularly obtrusive, but they were visible. When the lights are out, no one sees them.
> 
> The impact of not building backer boxes varies. What essentially happens is some sound is able to travel through holes in them (especially light fixtures), and you'll get some resonance in either that will transmit into the walls/joists/etc. Basically, you introduce a flanking path when they don't have backer boxes.
> 
> Something to consider is there are speakers built with backer boxes of sorts. The best in-wall and in-ceiling speakers are designed as such. Purists will recommend you still put these in backer boxes as well, just because DIY backer boxes are heavy and you KNOW they are built to do their job, whereas a factory box is a bit of an unknown variable.
> 
> Here's an example of a Triad speaker with an integrated backer box. You can see it's made of wood.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here's a Snell in-wall. It has an aluminum backer box (you can't really tell from this photo, and I could not find a good photo online of the rear).
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> And here's a metal after-market backer box. I don't recommend these. They're typically light weight and are more likely to increase resonance and muddiness in the sound, reverberate, etc.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here is your worst-case scenario: an in-wall with no factory backer box at all. It's like creating a giant hole in your wall.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> When you build your own, you are able to control its mass and seals. Here's a photo of Dozer's backer box construction.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> DIY backer boxes are typically made of an OSB or MDF shell and lined with cement backer board, though drywall can be used. I recommend Green Glue between layers. It needs to be a bit larger than whatever you want to put in it so that your speaker does not physically contact it directly. They are quite heavy when completed.


There is Dynabox buy Dynamat, but are probably a little more in cost then making your own backer boxes. Amazon sells them cheaper then from Dynamatt I believe. 

http://www.dynamat.com/architectural-home/architectural-home-dynabox/


----------



## HT Geek

Ladeback said:


> There is Dynabox buy Dynamat, but are probably a little more in cost then making your own backer boxes. Amazon sells them cheaper then from Dynamatt I believe.
> 
> http://www.dynamat.com/architectural-home/architectural-home-dynabox/


I checked out the product info. I can't tell what it's made of. Some sort of foam is what it appears to be, but no way to tell without one in-hand. Either way, one advantage of a DIY backer box is the mass. I would estimate the ones I built for my ceiling are close to 10 lbs. each. I purposely built them large (about 18 x 18 inches), not knowing which speakers I'd use up there and also figuring I might want to change them in the future. 

Choosing your dimensions for your backer boxes is another advantage of the DIY route. Either way, there are pros and cons of any approach. I happen to prefer DIY since it is truly custom, although I understand not everyone has the time, tools, patience, desire, and/or skill to DIY everything. Thanks for presenting an alternative, particularly for existing installations.


----------



## TTC

@HT Greek - Thank you.


I just fired my General Contractor yesterday. So, my HT will have to be put on hold for now...but I will be back (probably sooner than I think) cause I have a lot of questions and will need the help, expertly, and knowledge from you and the other members on this forum to properly setup my HT. It seems that this new venture will be more challenging than my reef tank!


----------



## HT Geek

TTC said:


> @HT Greek - Thank you.
> 
> 
> I just fired my General Contractor yesterday. So, my HT will have to be put on hold for now...but I will be back (probably sooner than I think) cause I have a lot of questions and will need the help, expertly, and knowledge from you and the other members on this forum to properly setup my HT. It seems that this new venture will be more challenging than my reef tank!


TTC,

I know that's a pain, as of course it derails your plans. However, in the long run probably for the better.

My suggestion is to start from a blank slate. Don't think about what your room is like atm (yet). Start with defining your vision of HT utopia. No doubt, there will be constraints with your room that you will need to overcome, but starting with your ideal vision will provide you with a good compass for the decision making process.

BTW, is your future build going to be new construction or modifying your existing home? I just realized I was presuming a remodel, but that might not be the case.


----------



## TTC

HT Geek said:


> TTC,
> 
> I know that's a pain, as of course it derails your plans. However, in the long run probably for the better.
> 
> My suggestion is to start from a blank slate. Don't think about what your room is like atm (yet). Start with defining your vision of HT utopia. No doubt, there will be constraints with your room that you will need to overcome, but starting with your ideal vision will provide you with a good compass for the decision making process.
> 
> BTW, is your future build going to be new construction or modifying your existing home? I just realized I was presuming a remodel, but that might not be the case.





HT Geek said:


> TTC,
> 
> I know that's a pain, as of course it derails your plans. However, in the long run probably for the better.
> 
> My suggestion is to start from a blank slate. Don't think about what your room is like atm (yet). Start with defining your vision of HT utopia. No doubt, there will be constraints with your room that you will need to overcome, but starting with your ideal vision will provide you with a good compass for the decision making process.
> 
> BTW, is your future build going to be new construction or modifying your existing home? I just realized I was presuming a remodel, but that might not be the case.



HT Geek -

This GC would keep changing the start date as he realized he underquoted us for the price. He kept increasing the price slowly but we still agreed to it anyway as we knew how the real estate market here in Dallas is getting out of control. He started dragging his feet and took 3-5 days to respond each time I would call and/or text him. I'm just glad I didn't start the project yet. He could've just been honest with me and said he could do it for that price. Enough of my ranting....

You're right. This is a remodel. We are changing 1/4 of the structure on the first floor and adding a second floor. The HT will be a completely new build. This HT will be on the second floor above the kitchen and family. That's why I have this major concern about sound transfer. Since the construction hasn't started yet, I would like to begin the sound proofing now.

The HT will be about 26 x 15 with two levels. I've attached a picture of the architect drawing. My vision is to have a 10' ceiling (current 9' in the drawing) and soffit around the room with 3" or 4" recessed lights shining down and also in the soffit, 4 in-ceiling speakers for an atmos setup. In the center ceiling, I'm planning to install about 600-800 fiber optics for the night sky effect. I'm planning to add columns around the room and in these columns, there will be lights on the top portion and either in-wall speakers or shelves to hold surround speakers hidden behind framed speaker fabric. I also want a small stage just for the look but haven't decided if I want perforated screen and place the front speakers behind it or a regular screen and place the speakers on the sides/below. The first level will have 3 seating. The second level will have also 3 seating with a bar right behind them that will fit 3-4 chairs. The media closet will be to the right of the bar. The screen size and speaker type haven't been decided. I will need to find an 11.2 receiver and I'm not sure how many surround speakers I would need for a 26' long room. I'm not sure if the 7.2.4 will work.

The entire remodel is a big project. So, my budget is really limited for the theater room. I can slowly build it but certain things like soundproofing, framing/drywall, and electrical work are the top priorities.


----------



## Ladeback

TTC said:


> HT Geek -
> 
> This GC would keep changing the start date as he realized he underquoted us for the price. He kept increasing the price slowly but we still agreed to it anyway as we knew how the real estate market here in Dallas is getting out of control. He started dragging his feet and took 3-5 days to respond each time I would call and/or text him. I'm just glad I didn't start the project yet. He could've just been honest with me and said he could do it for that price. Enough of my ranting....
> 
> You're right. This is a remodel. We are changing 1/4 of the structure on the first floor and adding a second floor. The HT will be a completely new build. This HT will be on the second floor above the kitchen and family. That's why I have this major concern about sound transfer. Since the construction hasn't started yet, I would like to begin the sound proofing now.
> 
> The HT will be about 26 x 15 with two levels. I've attached a picture of the architect drawing. My vision is to have a 10' ceiling (current 9' in the drawing) and soffit around the room with 3" or 4" recessed lights shining down and also in the soffit, 4 in-ceiling speakers for an atmos setup. In the center ceiling, I'm planning to install about 600-800 fiber optics for the night sky effect. I'm planning to add columns around the room and in these columns, there will be lights on the top portion and either in-wall speakers or shelves to hold surround speakers hidden behind framed speaker fabric. I also want a small stage just for the look but haven't decided if I want perforated screen and place the front speakers behind it or a regular screen and place the speakers on the sides/below. The first level will have 3 seating. The second level will have also 3 seating with a bar right behind them that will fit 3-4 chairs. The media closet will be to the right of the bar. The screen size and speaker type haven't been decided. I will need to find an 11.2 receiver and I'm not sure how many surround speakers I would need for a 26' long room. I'm not sure if the 7.2.4 will work.
> 
> The entire remodel is a big project. So, my budget is really limited for the theater room. I can slowly build it but certain things like soundproofing, framing/drywall, and electrical work are the top priorities.


 @TTC, looks like a cool plan, but a few questions. What is the distance from your step up to the screen wall? Have you thought about how big of a screen you want? My room I am building is also 26' or so and I was going to have the back third row table a little closer to wall if I decide to go with a AT screen. I was planning on having 11' from eyes to screen so I can get a 150" diagonal 2.35:1 screen. I would have about 32" from front wall to false wall. I have a regular 120" 16:9 screen now, but wish I had looked into a AT screen before I got it about 6 or 7 years ago. The wife doesn't want me to upgrade and spend more money so I may stay with it and build my room for it later maybe.

I hope you can find a good GC. They can be hard to find.


----------



## HT Geek

TTC said:


> The HT will be about 26 x 15 with two levels. I've attached a picture of the architect drawing. My vision is to have a 10' ceiling (current 9' in the drawing) and soffit around the room with 3" or 4" recessed lights shining down and also in the soffit, 4 in-ceiling speakers for an atmos setup. In the center ceiling, I'm planning to install about 600-800 fiber optics for the night sky effect. I'm planning to add columns around the room and in these columns, there will be lights on the top portion and either in-wall speakers or shelves to hold surround speakers hidden behind framed speaker fabric. I also want a small stage just for the look but haven't decided if I want perforated screen and place the front speakers behind it or a regular screen and place the speakers on the sides/below. The first level will have 3 seating. The second level will have also 3 seating with a bar right behind them that will fit 3-4 chairs. The media closet will be to the right of the bar. The screen size and speaker type haven't been decided. I will need to find an 11.2 receiver and I'm not sure how many surround speakers I would need for a 26' long room. I'm not sure if the 7.2.4 will work.
> 
> The entire remodel is a big project. So, my budget is really limited for the theater room. I can slowly build it but certain things like soundproofing, framing/drywall, and electrical work are the top priorities.



Thanks for the overview. That helps a lot in terms of providing advice and suggestions. 

As I'm sure you're aware, there's a lot of important details you need to sort out prior to construction beginning. I'm gonna give you a few things for your brain to munch on for the time being to help you solve the puzzle. You need to decide on priorities for these big items, if you haven't already. Once you know the answer to these questions, it will make the design/tradeoff choosing process easier. The key is to choose the big items that narrow your other choices, and to fully understand what you can/cannot live with.

To narrow down your focus, I would start by defining the primary factors in your decision making process moving forward. Will you have a fixed budget? Or is there a specific level of performance you must have? Can you answer all of these questions below?


Use cases. How will your HT room be utilized _most of the time_? What are your top 3 activities you want to enjoy in this room? e.g., watching movies, watching TV, listening to music. 
Who will you be using it most frequently? You, the whole family, guests, etc.? How many people in there simultaneously?
Sound proofing goals. We've discussed that a bit already. Floor -> ceiling below transmission is a particular concern. Side-sound transmission (walls) is likely to be one as well.
How many rows of seats, and how many seats per row? Is that a must-have or nice-to-have?
Budget or Features? Which will be the controlling factor in your decisions? It sounds like the answer is likely, 'budget,' but it's part of the larger home reno budget. 


Next, here are some pre-planning thoughts while you're in the budget/planning stage. Time to open the can o' worms: 

Ceiling murals: *@NightSkyMurals;*. Keep that username in the back of your mind. Jeff is the best, and he does it for a living. Plenty of reference installs pictured on AVS. Might not be in your budget, but even if you don't use him, he's an excellent resource for Q&A on ceiling murals.
*@BigMouthinDC;*. Another reference to keep handy. Another guy named Jeff.  When your contractors get stumped and are driving you crazy, he's the guy you want to ask for advice.
Electrical: Have at least 2 (two) 20-amp circuits run to your room from the breaker box. The vast majority of installs are fine with one, but here's why I recommend 2+:
Place your lighting on seperate circuit from A/V; if you blow one fuse, you won't blow the other and can still see
Leaves options open for more power hungry equipment such as amps
Peace of mind

Electrical: Run conduit at a minimum between A/V closet and PJ, behind/near your seats, and behind stage. Behind seats to allow future changes such as butt kickers. Preferably an independent outlet so you can run either 120v or low-voltage (e.g. speaker wire). Do not run 120v and LV in same conduit.
Home Automation: Decide on your home automation system (if you will use one) prior to finalizing the electrical plan. There's a wide range from Crestron, Lutron's Grafik Eye, to Z-Wave, remote IR emitters, and Harmony remotes (cost roughly in high->low order of that short list). Any system will require some home-run wires and some sort of gateway controller that needs to be in range of anything you want to control. Some require 120v 3-wire, some are wireless, etc. You get the idea. It's cheaper to run more wires once versus fewer wires two times.
Sound proofing: Partial parts list to consider: Green Glue of course, Putty Pads (applied to rear of electrical outlets), various types of insulation (in walls, possibly in soffit, likely on walls in various places), extra drywall, potentially hat channel & clips. This and furniture are likely to be your largest expenses. A/V equipment can be very pricey, but it doesn't have to be. Sort of like furniture, there's a wide range of costs and you can always upgrade in the future.
Flooring/Ceiling: Your flooring is clearly going to be a priority for sound-proofing. Figuring out how this will be handled should be in your top 3 priorities regarding your design. It has the potential to be a huge cost factor, or a small cost factor. More on that in a moment. 
Soffit: Make sure you have enough total room height for a reasonable soffit. Mine is 10" tall including 2x4 framing inside it and 1-1/8" of MDF and drywall on the bottom surface. That presented a minor challenge to me when running HVAC flex duct inside it. I was also marginally limited in recessed lighting choices, after accounting for backer box dimensions. I would have preferred another 2" of interior depth, however as-is I barely meet the 7' minimum height (building code) beneath the soffit where the 11-3/4" riser is beneath it. In the center of my room, room height is 8' over the riser and just under 9' where the front seats will be. Your plan to use a 10' starting height will provide you with more options.
HVAC. Do not underestimate how important this is!!! At a bare minimum, you will need 1 return vent and 2 supply vents. I strongly recommend you budget for in-line duct fans to improve your air flow (figure ~$250 each for size you will need). Easily installed by HVAC contractor at same time as the system. If possible, also zone your HT room and add a 2nd floor HVAC unit. Ensure the HVAC contractor takes into consideration the intelligent use of bypass ducts if only your HT room is calling for service. A 2-stage system would be ideal as it can be set to move less air on the lower setting when only the HT room needs conditioned air.
Your room is very similar to mine in terms of exterior walls, 2nd floor, etc. Although my situation is worse with my unconditioned garage below, you're going to find that a sound-proofed, sealed room is incredibly adept at retaining heat from all sources (including people) and stale air. At a minimum, you'll want to run the HVAC fan when the room is occupied. Without the in-line fans though I'm concerned you will run into the same issue I have, which is that during the summer in Texas you'll need more A/C circulation in your room, and without those fans you will refrigerate the remainder of your home in the process (even with a zoned system).
Another idea is put a mini-split system in your room. If your budget allows it, I would highly recommend that route. I would do so if I were to do-over my room build. Figure about $3,000-$3,500 installed, but you save yourself $1,000-$1,500 by not paying for a zoned system, electronic dampers, and in-line duct fans.


Looking at the bigger picture.... I see three significant areas of concern you should discuss with your architect ASAP (but not before you decide on the questions I've outlined in this post): 

1) Room dimensions are not realistic. You're going to need your architect to take into consideration the extra wall thickness of either double stud walls or clips & channel, presuming you go with one or the other. Your room dimensions will be reduced by 6-12" total in both directions (x,y axis). I also don't see drawn dimensions showing distance from front wall to riser. How much room will you have before adding a false wall and screen? You need a rough idea of your eye-to-screen distance for your front row.
2) Framing methods can help improve sound isolation. Explain to your architect that one of your goals is to minimize sound transmission from your HT room to adjacent rooms via the ceiling beams and floor joists/trusses. If it's possible to design the flooring and ceiling in such a way to minimize contact at those points without dramatically increasing cost, it would be preferable.
3) 2nd floor flooring. This is the biggie I'm concerned about. Right now your HT room has an entry at grade level, relative to the remainder of the 2nd floor. That makes sense for a typical house, but not for what you want to accomplish. You are going to want to use additional materials aside from a standard sub-floor, specifically to isolate your HT room and possibly your entire 2nd floor.
As-is right now, to isolate the HT room's floor from its sub-floor/joists/trusses, you could do one of the following:

a) Flip your room on the horizontal access (per drawing), such that entry is at the riser level; or
b) Have a lip/step up into the room 


Option (a) would allow you to increase the room floor height via de-coupling materials without impacting the room entry. Option (b) is a bad idea. You would have to make the step a minimum height to meet building codes, and that would throw off your room ceiling height. There's also the question of which room the step goes in, and whether it creates a trip hazard, etc. (it's best not to place it in the HT room just inside the door).

In your case, you have the luxury of a clean slate. Here are some other, superior options :
a) Raise the height of the floor framing of the entire 2nd floor excluding the HT room by ~14" or so (exact height TBD). This is not a difficult thing to do, depending on technique and materials. The net result is your HT room sub-floor would be lower than the remainder of your 2nd floor. You would enter the room at riser height, and step down toward the front/stage. You'd still want a 10' ceiling height (unless you ditch the soffit). If the remainder of your 2nd floor has 9' ceilings, this would make the 2nd floor roof the same height.
This would be my preferred option as it solves several problems and allows you to use sophisticated floor isolation methods such as Kinetics' RIM products.
b) Leave the room layout as-is, and isolate the entire 2nd floor. That would be quite expensive and is unnecessary. The only reason to do that would be if you had to leave the HT room layout as-is and did not want a step-up into the room to get over the lip created by floor isolation for just the HT room.

The disadvantage to flipping your room layout would be how to accommodate relocating your equipment room. Since your drawing only shows a small snippet of the adjacent rooms, I can't tell how big of an issue that could be with the current plan.


----------



## HT Geek

Ladeback said:


> I was planning on having 11' from eyes to screen so I can get a 150" diagonal 2.35:1 screen. I would have about 32" from front wall to false wall.


Yes... very good point. I decided not to get into that just yet w/my post above ^. TTC needs to get his architect on board, plus a sound-proofing plan as it will decrease his room size. I'm concerned after taking into account that fact, plus other factors such as where the door will be located, riser depth (front to back), etc., that he may not have enough room for a bar area. Depends on those factors plus seating type of 2nd row (presuming a 2nd row of comfy seats), what distance he's comfortable with between rear wall speakers and closest listener, etc.

Finished room dimensions, distance from riser lip to false wall and actual front wall, room width, and front-row eye distance-to-screen will be the biggest factors in where everything else lands.




> I have a regular 120" 16:9 screen now, but wish I had looked into a AT screen before I got it about 6 or 7 years ago. The wife doesn't want me to upgrade and spend more money so I may stay with it and build my room for it later maybe.


FWIW, I paid $350 shipped for my 130" 2.35:1. If you're brand agnostic, Silver Ticket has a 150" 16:9 on Amazon for $450.

Or another idea would be to paint your own (MississippiMan is a good authority, though he can be a little ornery, LoL... check out his posts on AVS; he is a good resource). Or build yourself a spandex frame screen for ~$150 or so at that size.




> I hope you can find a good GC. They can be hard to find.


You just reminded me... I have a good GC reference in Dallas who is a custom home builder! I'll PM @TTC.


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## mccraig416

*Need assistance/advice on soundproofing narrow wall*

Hoping someone can help me with a particularly tricky area i'm attempting to soundproof. 

I'm presently trying to soundproof the basement from the main floor of my new house, and have one last area that's a bit tricky. Sound travels from the main floor down the staircase to the basement. The wall separating the main floor from this staircase leading down is very narrow (it's a little over ~ 2 inches wide). The wall itself is really just wood paneling on both sides. See photo here.

My home theater is near this area (top of photo, to the right is entrance to room with my home theater)

It's not really possible to widen this wall because it will either extend beyond the stairs, or make the basement staircase way too narrow. So sorta stuck with this situation. 

I've been mulling over options and hoping to get some advice. Not sure if any of these are feasible or will work...

Replace the wood paneling on the hallway side with 5/8" SilentFX Drywall 
Use drywall from previous bullet and in narrow gap between basement staircase wood paneling and drywall (roughly 1.5 inches) add some sort of sound dampening insulation (suggestions for something of this thickness? Narrow roxul?)
Use same drywall and affix something like a soundproofing barrier to the interior side of the drywall, using something like a Green Glue
Any other creative suggestions? 

I realize there's no way to completely block out the sound in the current configuration, but I'd definitely like to lessen/dampen it as much as possible. For those wondering, the door itself is being replaced with a solid core door. The basement ceiling is presently being stuffed with Roxul Safe and Sound, and I'm using Resilient Channel with a 5/8" drywall.

Any/all help appreciated.


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## HT Geek

mccraig416 said:


> Hoping someone can help me with a particularly tricky area i'm attempting to soundproof.
> 
> I'm presently trying to soundproof the basement from the main floor of my new house, and have one last area that's a bit tricky. Sound travels from the main floor down the staircase to the basement. The wall separating the main floor from this staircase leading down is very narrow (it's a little over ~ 2 inches wide). The wall itself is really just wood paneling on both sides. See photo here.
> 
> My home theater is near this area (top of photo, to the right is entrance to room with my home theater)
> 
> It's not really possible to widen this wall because it will either extend beyond the stairs, or make the basement staircase way too narrow. So sorta stuck with this situation.
> 
> I've been mulling over options and hoping to get some advice. Not sure if any of these are feasible or will work...
> 
> [*]Replace the wood paneling on the hallway side with 5/8" SilentFX Drywall


Glad you shared that. I hadn't heard of Certainteed's SilentFX drywall. Given the fact it's only 1/2" thick, I'd bet it won't perform anywhere close to QuietRock or a standard DD/GG install. Ought to be superior to standard 1/2" drywall, but no way to know for sure without lab results (and I don't see any on Certainteed's site from a cursory look).




> [*]Use drywall from previous bullet and in narrow gap between basement staircase wood paneling and drywall (roughly 1.5 inches) add some sort of sound dampening insulation (suggestions for something of this thickness? Narrow roxul?)


How are you calculating this 1-1/2" gap? I'm not following you on where that is, unless you are referring to what I presume are 2x4 or 2x3 studs turned sideways inside the wall to create a 1-1/2" gap between existing drywall sheets on either side of the wall. If so, you could put rigid fiberglass in there, but you'll still have transmission from the studs.




> [*]Use same drywall and affix something like a soundproofing barrier to the interior side of the drywall, using something like a Green Glue


Looks like recycled rubber floor attached to a wall. Again, I don't see any lab tests. I do see claimed STC and db figures, but I don't see 3rd party lab references. I don't see an explanation of what they mean by db. Is that db transmitted through or transmission loss (TL)? If they have done lab tests to produce those results, why don't they share the lab report(s)?




> [*]Any other creative suggestions?


Is that staircase wall vibrating from sound, do you just hear it downstairs, what are the symptoms you notice?

It seems to me the best things you could do would be to 1) install a good quality, solid core door 1-1/2" thick or greater (e.g. consider gluing and screwing two doors together to create more mass); 2) install a good quality automatic door bottom and corresponding door seals where the stops are; and 3) use of sound-proofing techniques in the room (not sure what you've done there). If the room is not decoupled, you're also going to get sound transmission via the floor joists, ceiling joists, walls, etc. You won't be able to stop all that by treating that staircase wall. It sounds as if you understand this and are simply looking for ideas to make an annoying situation a bit less annoying.

How about attaching acoustic wall panels to that hallway across from your HT room? Or better yet, replace your wood paneling in the main floor hallway (opposite HT room entrance) with fabric wall panels lined with rigid fiberglass (OC 703/704/705)? Either method would absorb some of the sound coming out of the HT room via the door.

I wouldn't go that route until first trying the door bottom & door seals and see if the situation improves. Your efforts are going to be more productive if you can first isolate the specific source of the noise you want to abate (i.e. via door, floor joists, etc.).


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## doveman

I still have so many questions and so much I don't understand but I'll try and stick to one subject at a time!

I contacted the Soundproofing Company to request a quote for IB-1 clips but apart from a standard acknowledgement e-mail on 11 July I haven't heard from them, so it seems they're not interested in shipping them to the UK, which is a shame as even with the shipping on top, at $1.50 per clip they are the most affordable option.

I'm certainly not going pay £6 per clip for the ISOMAX clips (which are similar to IB-1 but covered in rubber) and even if I could afford to pay £4 per clip for the Genie clips, at 41mm (including the hat channel) compared to the 28.6mm for the IB-1+hat channel, they're too deep for me to use on my walls, although I may use them for the ceiling.

So what other options are there for treating my walls, bearing in mind I can't afford to lose much space and can't build a frame spaced off the wall, using a baseboard secured to the concrete slab under my subfloor? All I can think of is screwing wooden joists that are less then 30mm deep (they can be as wide as needed) directly to the wall and then just screwing the acoustic plasterboard directly to the joists, with 25mm pink fluffy or rockwoll in the gap. This is obviously not going to be very good in terms of impact noise (in either direction) but maybe it would significantly improve the airborne noise problems? Will 30mm deep joists be strong enough to support two layers of acoustic plasterboard though? I'm leaning towards using Knauf Soundshield Plus which weighs 11.5kg/m2 for the 12.5mm boards and 12.8kg/m2 for the 15mm boards, so with a layer of each I'd be looking at 24.3kg/m2. http://www.knauf.co.uk/files/download/plasterboardbrochure2013pdf/292


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## HT Geek

doveman said:


> I contacted the Soundproofing Company to request a quote for IB-1 clips but apart from a standard acknowledgement e-mail on 11 July I haven't heard from them, so it seems they're not interested in shipping them to the UK, which is a shame as even with the shipping on top, at $1.50 per clip they are the most affordable option.


I can't imagine they wouldn't ship to you in the UK. I'm confident they have shipped overseas before. OTOH, I handled international shipping as part of a previous role in a company and I can tell you it's a big P.I.T.A. to ship internationally from the U.S. It is something one gets better at as you figure out the nuances of U.S. Customs' and shipping companies' processes. It's also much easier now than when I was doing it, from what I've heard. Point is there is a learning curve if someone isn't used to doing it all the time. Just sayin'. Keep bugging them!

You might also check Ebay for the same clips.




> So what other options are there for treating my walls, bearing in mind I can't afford to lose much space and can't build a frame spaced off the wall, using a baseboard secured to the concrete slab under my subfloor? All I can think of is screwing wooden joists that are less then 30mm deep (they can be as wide as needed) directly to the wall and then just screwing the acoustic plasterboard directly to the joists, with 25mm pink fluffy or rockwoll in the gap. This is obviously not going to be very good in terms of impact noise (in either direction) but maybe it would significantly improve the airborne noise problems?


True, but your options are limited. I was about to suggest furring strips as well, and I agree that is perhaps your next best option. At least it would reduce your mated surface area.




> Will 30mm deep joists be strong enough to support two layers of acoustic plasterboard though?


What kind of joists? As in furring strips attached to the walls? "Joists" normally refers to horizontal supports.

On the walls, 30mm is fine, depending on how they are attached to the structural wall. If you've got sufficient adhesion (e.g. enough screws), you'll be fine. Shear (pull out) force is what you need to worry about. Not really the weight of the wall panels per se.


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## doveman

HT Geek said:


> I can't imagine they wouldn't ship to you in the UK. I'm confident they have shipped overseas before. OTOH, I handled international shipping as part of a previous role in a company and I can tell you it's a big P.I.T.A. to ship internationally from the U.S. It is something one gets better at as you figure out the nuances of U.S. Customs' and shipping companies' processes. It's also much easier now than when I was doing it, from what I've heard. Point is there is a learning curve if someone isn't used to doing it all the time. Just sayin'. Keep bugging them!
> 
> You might also check Ebay for the same clips.


OK, I won't give up on them just yet then. I have checked on e-bay but haven't seen anything and I'd be a bit worried about buying something that needs to stop considerable weight from falling down and killing me from untrusted sources anyway!



> True, but your options are limited. I was about to suggest furring strips as well, and I agree that is perhaps your next best option. At least it would reduce your mated surface area.
> 
> What kind of joists? As in furring strips attached to the walls? "Joists" normally refers to horizontal supports.
> 
> On the walls, 30mm is fine, depending on how they are attached to the structural wall. If you've got sufficient adhesion (e.g. enough screws), you'll be fine. Shear (pull out) force is what you need to worry about. Not really the weight of the wall panels per se.


By joists I guess I meant studs, i.e. vertical wooden supports screwed to the wall, which in turn I'd screw the drywall to. I wasn't thinking of just using furring strips screwed directly to the wall as that wouldn't provide the gap needed to fit the rockwool. I guess I might be able to have vertical wooden studs (or metal studs which might be easier), then horizontal furring strip to attach the drywall to if that would be worthwhile in terms of impact noise (I can't imagine it would make much difference to airborne noise) and didn't increase the depth too much.

Glad to hear that 30mm studs will be OK, as I was worried I'd need something thicker than I could accommodate. I'll definitely make sure someone who knows what they're doing (like a structural engineer) ensures the shear force is covered!


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## HT Geek

doveman said:


> By joists I guess I meant studs, i.e. vertical wooden supports screwed to the wall, which in turn I'd screw the drywall to. I wasn't thinking of just using furring strips screwed directly to the wall as that wouldn't provide the gap needed to fit the rockwool. I guess I might be able to have vertical wooden studs (or metal studs which might be easier), then horizontal furring strip to attach the drywall to if that would be worthwhile in terms of impact noise (I can't imagine it would make much difference to airborne noise) and didn't increase the depth too much.
> 
> Glad to hear that 30mm studs will be OK, as I was worried I'd need something thicker than I could accommodate. I'll definitely make sure someone who knows what they're doing (like a structural engineer) ensures the shear force is covered!


Just to be clear....

If you have 30mm deep freestanding vertical studs, I would be leery of those being able to support sufficient shear force. Though it might be possible, you'd definitely want to run some engineering calculations first, or hire someone to. If the 30mm studs are screwed to a structural wall, you ought to be fine. They would then functionally be acting as furring strips.

If you want a proper gap, then naturally the furring strip/direct attachment idea won't work. In that case I would be inclined to focus on steel studs, but I'm not sure which gauge minimum you'd need. That is where an engineering analysis would come in to play (and the engineer would need to know the weight of whatever would hang from the metal studs; whatever is in between them - such as Rockwool - will be inconsequential).


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## EC

doveman said:


> OK, I won't give up on them just yet then. I have checked on e-bay but haven't seen anything and I'd be a bit worried about buying something that needs to stop considerable weight from falling down and killing me from untrusted sources anyway!


Look at the Resilmount A237 clips. I used the A237 for my walls and the A237R clips for my ceiling. There may be a local supplier in your country. There are also online companies based out of the USA that sell these.


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## bubbrik

Hello

I have a question regarding the use of green glue/double drywall and clips/hat channel.

How and when should the two techniques be applied to a wall that is shared between a dedicated HT room and a living space?
1. Apply both techniques on both sides of the wall
2. Apply one technique on the HT side of the wall and the other technique on the living space side
3. Is there some other typical combination?

Thanks in advance for your guidance.


Sent from my iPhone using Tapatalk


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## GatorBlues

HT Geek said:


> ^^^ What he said.
> 
> The keys are mass of the door and sealing the gaps all doors have with gaskets (e.g. automatic door bottom), while still allowing it to be useful as a door.


Is there a particular brand or style of automatic door bottoms that you recommend? What about door frame seals -- is there a particular brand or style of those you recommend as well?


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## Ladeback

GatorBlues said:


> Is there a particular brand or style of automatic door bottoms that you recommend? What about door frame seals -- is there a particular brand or style of those you recommend as well?


Check out The Soundproofing Company. 

http://www.soundproofingcompany.com/product-category/soundproofing-products/door-bottom-jamb-stop/


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## HT Geek

bubbrik said:


> Hello
> 
> I have a question regarding the use of green glue/double drywall and clips/hat channel.
> 
> How and when should the two techniques be applied to a wall that is shared between a dedicated HT room and a living space?
> 1. Apply both techniques on both sides of the wall
> 2. Apply one technique on the HT side of the wall and the other technique on the living space side
> 3. Is there some other typical combination?


Depends on your goals, budget, etc. However, to provide you with some guidance:

For the most soundproofing, you would do clips, hat channel, DD (double drywall) and GG (Green Glue) on BOTH sides of the wall. However, most people do clips & channel + DD/GG on the HT side only, and that's all that is normally necessary. If you have the budget and motivation for doing both, it would only benefit you further. I wouldn't bother though unless it were a bedroom next door.

The most important factor is that you apply a consistent approach to de-coupling the HT room from the remainder of the home, across all wall and ceiling surfaces. If the room is not in a basement or ground floor, you may want to consider isolating the floor as well.

Much depends on your specific situation. The more details you provide, the better advice you will receive.


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## HT Geek

GatorBlues said:


> Is there a particular brand or style of automatic door bottoms that you recommend? What about door frame seals -- is there a particular brand or style of those you recommend as well?





Ladeback said:


> Check out The Soundproofing Company.
> 
> http://www.soundproofingcompany.com/product-category/soundproofing-products/door-bottom-jamb-stop/


Zero International is the de-facto standard in ADB's. Their stops and headers are also very good. I've also heard good things about Reese, and mixed reviews on Pemko (though I believe the not-so-good reviews on Pemko were regarding rigid sealing material instead of spongy or flexible material that we'd want).

Zero's products are typically going to be 2x or more in cost versus the others.

Anything you buy from SPC or Trademark Soundproofing should be good. The latter will do custom sizes if you call them.


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## bubbrik

HT Geek said:


> Depends on your goals, budget, etc. However, to provide you with some guidance:
> 
> 
> 
> For the most soundproofing, you would do clips, hat channel, DD (double drywall) and GG (Green Glue) on BOTH sides of the wall. However, most people do clips & channel + DD/GG on the HT side only, and that's all that is normally necessary. If you have the budget and motivation for doing both, it would only benefit you further. I wouldn't bother though unless it were a bedroom next door.
> 
> 
> 
> The most important factor is that you apply a consistent approach to de-coupling the HT room from the remainder of the home, across all wall and ceiling surfaces. If the room is not in a basement or ground floor, you may want to consider isolating the floor as well.
> 
> 
> 
> Much depends on your specific situation. The more details you provide, the better advice you will receive.




Thank you so much.

Here are some additional details in the attached and also some notes.


1. HT is the basement
2. The wall with the HT entrance is shared its a living space / family room in the basement.
3. The room behind the screen is a kids playroom/craft room (shown as unfinished room in the picture)
4. We have our dining area on the main floor above the HT room
5. The wall on the left is 2/3rds foundation and 1/3rd Hvac/equipment/storage room












Sent from my iPhone using Tapatalk


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## HT Geek

bubbrik said:


> Thank you so much.
> 
> Here are some additional details in the attached and also some notes.
> 
> 
> 1. HT is the basement
> 2. The wall with the HT entrance is shared its a living space / family room in the basement.
> 3. The room behind the screen is a kids playroom/craft room (shown as unfinished room in the picture)
> 4. We have our dining area on the main floor above the HT room
> 5. The wall on the left is 2/3rds foundation and 1/3rd Hvac/equipment/storage room


Hmm. You definitely have a few challenges.

A few cursory thoughts:


Any interest in a soffit? I hope not because realistically you don't have sufficient height, unless you don't do a rear seating riser
Ideally, you want a uniform ceiling height. Is the lower ceiling height section due to a step-down on the floor above?
Any chance you could relocate access to the HVAC room via another part of the basement?
I'd suggest clips & channel, DD/GG on all 4 walls of the HT room plus the ceiling; floor should be fine w/carpet and pad
Acoustically Transparent screen w/speakers behind? Or not? Or undecided?
How many rows of seats would you like to have?
How many seats would you prefer to have in the room?
If you must access HVAC room from HT room, is it possible to relocate the door (move it slightly left or right along the wall)?
Any chance you'd consider a longer room and taking space from the kids' playroom area? Or is that off limits?
Any chance of stealing a few feet from the adjacent family room?
Do you know if either of those two walls I just mentioned are load bearing?
Why do you have two large return vents in the bottom/south wall of the room??? Are those actually vents, or pass-thru ductwork?


----------



## bubbrik

HT Geek said:


> Hmm. You definitely have a few challenges.
> 
> 
> 
> A few cursory thoughts:
> 
> 
> 
> 
> Any interest in a soffit? I hope not because realistically you don't have sufficient height, unless you don't do a rear seating riser
> 
> Ideally, you want a uniform ceiling height. Is the lower ceiling height section due to a step-down on the floor above?
> 
> Any chance you could relocate access to the HVAC room via another part of the basement?
> 
> I'd suggest clips & channel, DD/GG on all 4 walls of the HT room plus the ceiling; floor should be fine w/carpet and pad
> 
> Acoustically Transparent screen w/speakers behind? Or not? Or undecided?
> 
> How many rows of seats would you like to have?
> 
> How many seats would you prefer to have in the room?
> 
> If you must access HVAC room from HT room, is it possible to relocate the door (move it slightly left or right along the wall)?
> 
> Any chance you'd consider a longer room and taking space from the kids' playroom area? Or is that off limits?
> 
> Any chance of stealing a few feet from the adjacent family room?
> 
> Do you know if either of those two walls I just mentioned are load bearing?
> 
> Why do you have two large return vents in the bottom/south wall of the room??? Are those actually vents, or pass-thru ductwork?




- yes, after much thought and disappointment, I've decided to even out the ceiling height to 8' but with double drywall and clips, it would be a couple of inches below 8'
- we are not going for risers at all...we are not set on formal HT seats...we might end up with some informal HT seating
- there is no space for another entry way into the HVAC room other than through the HT room; moving the door to the right is not possible due to the foundation wall and the it cannot be moved to the left as the HVAC system if right there
- yes, the speakers will be behind an AT screen - the room was originally 20 ft but had to steal 2 feet from the kids craft room to accommodate a false wall - that wall was not a load bearing wall
- the wall of the family room is load bearing and there are stairs to the first floor for half of the width of that wall
- the two vents that I noted are return ducts (sorry, I used the wrong term); one return for the HT room and the other return for the family room



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----------



## HT Geek

bubbrik said:


> - yes, after much thought and disappointment, I've decided to even out the ceiling height to 8' but with double drywall and clips, it would be a couple of inches below 8'
> - we are not going for risers at all...we are not set on formal HT seats...we might end up with some informal HT seating
> - there is no space for another entry way into the HVAC room other than through the HT room; moving the door to the right is not possible due to the foundation wall and the it cannot be moved to the left as the HVAC system if right there
> - yes, the speakers will be behind an AT screen - the room was originally 20 ft but had to steal 2 feet from the kids craft room to accommodate a false wall - that wall was not a load bearing wall
> - the wall of the family room is load bearing and there are stairs to the first floor for half of the width of that wall
> - the two vents that I noted are return ducts (sorry, I used the wrong term); one return for the HT room and the other return for the family room


Excellent response! Thanks. 

Quick follow-up: I'm still a bit confused about the return ducts. Are there currently exposed ducts in the future HT room??? Or are those in the ceiling?

So, overall it sounds like you've got a few decisions already sorted. An important item that comes to mind is you'll want to do something about isolating sound from the equipment/HVAC room. At the very least I'd suggest a solid core door, ideally sealed with neoprene stops, header, and an automatic door bottom. That would keep out most mechanical noise from permeating the HT room during quiet scenes, and at a relatively reasonable cost.

Next, might you have enough room in that equipment area to possibly place your A/V equipment rack in there? It would be a big bonus to you if you could access your 'rack' from the sides and rear via the HVAC room.

Now, I should have asked this clearly earlier.... what are your goals with your HT room? And of those, which are primary/must haves?

Edit: Forgot to ask... is your current HT entry a double wide door? Is it 5' wide (per your diagram)?


----------



## bubbrik

HT Geek said:


> Excellent response! Thanks.
> 
> 
> 
> Quick follow-up: I'm still a bit confused about the return ducts. Are there currently exposed ducts in the future HT room??? Or are those in the ceiling?
> 
> 
> 
> So, overall it sounds like you've got a few decisions already sorted. An important item that comes to mind is you'll want to do something about isolating sound from the equipment/HVAC room. At the very least I'd suggest a solid core door, ideally sealed with neoprene stops, header, and an automatic door bottom. That would keep out most mechanical noise from permeating the HT room during quiet scenes, and at a relatively reasonable cost.
> 
> 
> 
> Next, might you have enough room in that equipment area to possibly place your A/V equipment rack in there? It would be a big bonus to you if you could access your 'rack' from the sides and rear via the HVAC room.
> 
> 
> 
> Now, I should have asked this clearly earlier.... what are your goals with your HT room? And of those, which are primary/must haves?
> 
> 
> 
> Edit: Forgot to ask... is your current HT entry a double wide door? Is it 5' wide (per your diagram)?




Here are the pictures of the ducts. The first one is from the outside of the HT room (family room). The second one is from inside the HT room.


















Yes, there is enough room in the HVAC room for an equipment rack.

Our primary use is for the four us to watch movies. Not a serious HT room some high tech ones I see on these forums but a dedicated one. No plans now for formal HT seating. We want a big screen with some good sound. When we do this, we definitely do not want to bother the first floor.

Yes, the main entrance to the HT room is 5ft for a double door.

Can you help me pick the soundproof door for the HVAC room? You mentioned neoprene stops, header, and a stop.

Thank you so much for your patience.


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----------



## HT Geek

bubbrik said:


> Here are the pictures of the ducts. The first one is from the outside of the HT room (family room). The second one is from inside the HT room.


So, it looks as if those are just returns to draw air into the HVAC unit and presumably they were installed there simply because it was an efficient way to draw return air from your future HT room and family room into the HVAC unit.




> Yes, there is enough room in the HVAC room for an equipment rack.


It looks as if the HVAC room could be very useful for that (an equipment rack). However, it also appears that would require some careful planning in order to facilitate proper HVAC operation and some sound proofing between the HVAC system room and equipment rack room. Can be done though.




> Our primary use is for the four us to watch movies. Not a serious HT room some high tech ones I see on these forums but a dedicated one. No plans now for formal HT seating. We want a big screen with some good sound. When we do this, we definitely do not want to bother the first floor.
> 
> Yes, the main entrance to the HT room is 5ft for a double door.
> 
> Can you help me pick the soundproof door for the HVAC room? You mentioned neoprene stops, header, and a stop.


I'm thinking some of the challenges I'd want to be thinking about up front are:

HVAC room isolation (sound proofing from HT room)
Exactly how HVAC room could be reconfigured to accomodate dedicated A/V room/rack
Sound proofing entry way / entry door
Leveling the ceiling to a consistent height

Regarding the door.... An open entry would be the worst-case scenario. 2nd I'd say is a barn door. 3rd is probably a double-wide-door (aka French door).

So, for starters it would be ideal to replace the double door you have with an alternative. If you don't have a door there but only an opening, then it's easily rectified. A communicating door system is the best option from a sound proofing standpoint. For instance, if you could create a small room or foyer of sorts by taking some space from the adjacent family room. Next best option would be a bank vault type of door: something heavy. Beyond that... solid core doors. A couple of common solutions are 1) using an exterior grade door (they're thicker and heavier than interior doors); or 2) gluing and screwing two interior solid core doors together.

If you use clips & channel and double drywall, or build an independent inner wall/ceiling frame, you will have a thicker than normal doorway. Therefore, it's not going to look out of place having a thicker door. No one will know until they open the door.

You can find perfectly suitable doors at the big box stores or purchase from a door company. 

The automatic door bottom, neoprene gasketed header and door stops are all designed to complement a solid door and help to prevent sound from leaking around the door.


----------



## doveman

HT Geek said:


> Just to be clear....
> 
> If you have 30mm deep freestanding vertical studs, I would be leery of those being able to support sufficient shear force. Though it might be possible, you'd definitely want to run some engineering calculations first, or hire someone to. If the 30mm studs are screwed to a structural wall, you ought to be fine. They would then functionally be acting as furring strips.
> 
> If you want a proper gap, then naturally the furring strip/direct attachment idea won't work. In that case I would be inclined to focus on steel studs, but I'm not sure which gauge minimum you'd need. That is where an engineering analysis would come in to play (and the engineer would need to know the weight of whatever would hang from the metal studs; whatever is in between them - such as Rockwool - will be inconsequential).


The vertical studs won't be freestanding. I can't even imagine how that might work! They'll definitely be screwed to the walls. It might be tricky with the wall that divides my HT room and living room as I need to make sure (a) the wall can support the extra weight of two layers of drywall on both sides but also that I can fit deep enough screws on both sides of the wall. I guess I might need to arrange the studs so that they're not directly opposite each other to avoid weakening the wall.

I'll discuss metal studs with the engineer in due course. I was considering them anyway as they're easier to work with, albeit slightly more expensive.


----------



## doveman

EC said:


> Look at the Resilmount A237 clips. I used the A237 for my walls and the A237R clips for my ceiling. There may be a local supplier in your country. There are also online companies based out of the USA that sell these.


Thanks, I didn't realise there was an alternative to the IB-1 clips, so having more choices of supplier should make it possible for me to find someone who will ship them here at a reasonable price. I don't think the A237R clips will work out any cheaper than buying Genie clips here though, so I might just use those for the ceiling. I was actually just thinking of using the IB-1 clips for the ceiling as well as the walls but maybe I should use something with more isolation on the ceiling.


----------



## HT Geek

doveman said:


> Thanks, I didn't realise there was an alternative to the IB-1 clips


Here are the most commonly referenced clips, in order of least to most expensive. You can likely find the Resilmount A237R cheaper, but this is what I found from a cursory scan.

IB-1 clips; $1.87/clip

Whisper Clip; $4.49/clip

RSIC-1 clips (w/rubber); $4.80/clip

Resilmount A237R (R = with rubber); $5/clip

Kinetics IsoMax; $5.25/clip


----------



## deewan

HT Geek said:


> Here are the most commonly referenced clips, in order of least to most expensive. You can likely find the Resilmount A237R cheaper, but this is what I found from a cursory scan.
> 
> IB-1 clips; $1.87/clip
> 
> Whisper Clip; $4.49/clip
> 
> RSIC-1 clips (w/rubber); $4.80/clip
> 
> Resilmount A237R (R = with rubber); $5/clip
> 
> Kinetics IsoMax; $5.25/clip


I had searched once before but couldn't find solid answers. Is there information someplace showing the benefits of the clips listed above and compared to one another? In other words, do the $5 clips work 10-60% better than the $2 clips? I've only used the IB-1 clips before and have been curios if the extra cash for the RSIC-1 clip is worth it.


----------



## HT Geek

deewan said:


> I had searched once before but couldn't find solid answers. Is there information someplace showing the benefits of the clips listed above and compared to one another? In other words, do the $5 clips work 10-60% better than the $2 clips? I've only used the IB-1 clips before and have been curios if the extra cash for the RSIC-1 clip is worth it.


It's logical to presume the clips without the rubber isolation would be only slightly less beneficial in effect, but the difference between clips versus no clips is significant.

I'm not aware of any Brand A vs. Brand B comparos. Some of them have lab tests (paid for by the manufacturer). Here's a sample from my database of HT stuff:

Green Glue Noiseproofing Clip

Wood studs, 1x DW HT room side, 1x DW other side of wall; Orfield Laboratories 08-0323; STC 60
Wood studs, 2x DW HT room side, 1x DW other side of wall; Orfield Laboratories 08-0324; STC 63

Kinetics IsoMax

Wood studs, 1x DW HT room, 1x DW other side of wall, 16" O.C. studs; Riverbank Acoustical Laboratories TL 04-277; STC 33
Wood studs, 1x DW HT room side, 1x DW other side of wall; Riverbanks Acoustical Laboratories TL 02-34; STC 57
Wood studs, 2x DW HT room side, 1x DW other side of wall; Riverbanks Acoustical Laboratories TL 02-35; STC 61 
Wood studs, 2x DW HT room side, 2x DW other side of wall; Riverbanks Acoustical Laboratories TL 02-40; STC 64
Wood studs, 3x DW HT room side, 2x DW other side of wall; Riverbanks Acoustical Laboratories TL 02-46; STC 65
Steel studs, 2x DW HT room side, 1x DW other side of wall; Riverbanks Acoustical Laboratories TL 06-25; STC 60
Steel studs, 2x DW HT room side, 2x DW other side of wall; Riverbanks Acoustical Laboratories TL 06-48; STC 63

Select reports linked below and/or attached to this post:

Kinetics IsoMax [Concrete Ceiling] STC 66 / IIC 44; NRC B-3448.5

Kinetics IsoMax vs. Resilient Channel [Wood & Steel Wall Studs] STC 57 wood / 54 steel (note: this is contrary to most lab tests, which tend to indicate steel studs are better at sound isolation)


----------



## veger69

I need some advice on sound proofing a home theater. It's a remodel so all walls can be treated. I'm planning on using rokwul safe and sound and trying do decide what the difference would be between 1/2" drywall with green glue or quiterock 530 directly screwed into studs or using a ISO clip. And the cost ratio. Thanks


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----------



## HT Geek

veger69 said:


> I need some advice on sound proofing a home theater. It's a remodel so all walls can be treated. I'm planning on using rokwul safe and sound and trying do decide what the difference would be between 1/2" drywall with green glue or quiterock 530 directly screwed into studs or using a ISO clip. And the cost ratio.


QuietRock 530 is 5/8" thick. If you compared normal drywall 1/2" vs. 5/8" thick, the 5/8" thick version will provide slightly better sound proofing. QuietRock 530 will provide better soundproofing vs. Drywall 1/2" or 5/8" because it already has a viscoelastic layer.

Are you considering 2x 1/2" drywall + GG versus 1x QuietRock 530??

Difficult to give you ratios on costs without knowing some variables (e.g. what size and number of GG containers [5-gallon bucket vs. tubes], shipping costs of GG, who will install materials, etc.).


----------



## TTC

@HT Geek @Ladeback

Sorry guys, for not coming back sooner to this thread. I've been busy with packing/upacking the PODS and been still trying to find a new General Contractor. School is about to start back up and I might have to move this renovation until next year. It might to be crazy and hectic for my wife to get our daughter ready for school in the morning while the house is under major construction. I will be back once this project starts back up.


----------



## HT Geek

TTC said:


> @HT Geek @Ladeback
> 
> Sorry guys, for not coming back sooner to this thread. I've been busy with packing/upacking the PODS and been still trying to find a new General Contractor. School is about to start back up and I might have to move this renovation until next year. It might to be crazy and hectic for my wife to get our daughter ready for school in the morning while the house is under major construction. I will be back once this project starts back up.


No worries. I've been working on my room 1-1/2 years due to LIG.  It happens. It's tough to dedicate the focus required without other things interrupting. At least for right now it's one fewer item on your plate.


----------



## veger69

HT Geek said:


> QuietRock 530 is 5/8" thick. If you compared normal drywall 1/2" vs. 5/8" thick, the 5/8" thick version will provide slightly better sound proofing. QuietRock 530 will provide better soundproofing vs. Drywall 1/2" or 5/8" because it already has a viscoelastic layer.
> 
> 
> 
> Are you considering 2x 1/2" drywall + GG versus 1x QuietRock 530??
> 
> 
> 
> Difficult to give you ratios on costs without knowing some variables (e.g. what size and number of GG containers [5-gallon bucket vs. tubes], shipping costs of GG, who will install materials, etc.).



Yes 1/2 rock x 2 w/gg vs 5/8 quiterock 
Well the sqft is about 700 and we are installing it ourselves although if I could avoid doing a double layer ceiling I'm all for it. But I'm really interested in doing quiterock to save sweat and time but just need to know if it's worth it. I've heard different opinions on weather quiterock works or not. If it works how much better would it be with clips compared to the cost?


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----------



## HT Geek

veger69 said:


> Yes 1/2 rock x 2 w/gg vs 5/8 quiterock
> Well the sqft is about 700 and we are installing it ourselves although if I could avoid doing a double layer ceiling I'm all for it. But I'm really interested in doing quiterock to save sweat and time but just need to know if it's worth it. I've heard different opinions on weather quiterock works or not. If it works how much better would it be with clips compared to the cost?


Well, here's my 2 cents FWIW:

Does QuietRock "work"? Yes, with the caveat that it depends on your definition of "working." Presuming you mean does it work for soundproofing, yes for sure. Is it right for you? That depends....

QuietRock 530 is 5/8" thick and weighs 3.3 psf. Type X 5/8" drywall weighs 2.2 psf. A double-drywall (DD) + Green Glue sandwich will weigh ~4.5 psf. So, from a mass perspective (more is better for sound proofing), DD+GG wins. And I can tell you that IIRC from memory, the DD+GG trumps QR 530 in lab tests as well (i.e. objective verification).

1x sheet of QuietRock will typically cost more than 2 sheets of Type X 5/8" drywall (~$20-22). When you add the cost of Green Glue, you can easily top $50 per 4x8 section. Some folks (like me) used only 1/2 the recommended GG to save $ (1 tube per 4x8 sheet versus 2).

So, ballpark.... 5/8" DD + GG.... Let's presume you need 30 sheets of 4x8 drywall to cover your 700 sq ft. So, 60 sheets total. That's ~$600 in drywall. Let's also presume you purchase 2x 5-gallon Green Glue buckets (to get the 2x tube coverage per 4x8 sheet) for $250 each, plus a dispensing gun for $75. So, that's $575 in Green Glue costs. So, you're at roughly $1,200 + tax + delivery/shipping for your drywall and Green Glue.

Or you could do 1x layer of QuietRock 530. I can't give you a price guess on that because they only places you'll find it will be drywall contractor supply stores. Most of them will have to special order it, and they will likely charge you for that privilege. But for the sake of discussion let's guesstimate your total cost of materials, including delivery, comes to $800.

From a price-to-performance perspective, superior sound proofing (DD+GG) will cost you an additional $400-500. Is that worth it to you?

Now, if you were paying for the labor, I would say the delta would be +$1,000 or so above that figure (depending on contract labor costs in your area). When you throw labor into the mix, you're talking more-or-less double the cost to do DD+GG. But at the DIY level, it's a question of whether the added benefits of the DD+GG route are worth $500 and more of your time.

If you would like, I'll look through my records to see if I can find an objective comparison between the two concepts in terms of lab reports of sound proofing performance. Might take me a day or two to post the results though. Please reply and let me know if you'd like me to do that, or if the info above is helpful enough, or if you still have questions on this subject. 

EDIT: Yes, I would do the clips & channel either way. They will have a significant impact with either approach (DD/QR).


----------



## bubbrik

HT Geek said:


> So, it looks as if those are just returns to draw air into the HVAC unit and presumably they were installed there simply because it was an efficient way to draw return air from your future HT room and family room into the HVAC unit.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It looks as if the HVAC room could be very useful for that (an equipment rack). However, it also appears that would require some careful planning in order to facilitate proper HVAC operation and some sound proofing between the HVAC system room and equipment rack room. Can be done though.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'm thinking some of the challenges I'd want to be thinking about up front are:
> 
> 
> HVAC room isolation (sound proofing from HT room)
> 
> Exactly how HVAC room could be reconfigured to accomodate dedicated A/V room/rack
> 
> Sound proofing entry way / entry door
> 
> Leveling the ceiling to a consistent height
> 
> 
> 
> 
> Regarding the door.... An open entry would be the worst-case scenario. 2nd I'd say is a barn door. 3rd is probably a double-wide-door (aka French door).
> 
> 
> 
> So, for starters it would be ideal to replace the double door you have with an alternative. If you don't have a door there but only an opening, then it's easily rectified. A communicating door system is the best option from a sound proofing standpoint. For instance, if you could create a small room or foyer of sorts by taking some space from the adjacent family room. Next best option would be a bank vault type of door: something heavy. Beyond that... solid core doors. A couple of common solutions are 1) using an exterior grade door (they're thicker and heavier than interior doors); or 2) gluing and screwing two interior solid core doors together.
> 
> 
> 
> If you use clips & channel and double drywall, or build an independent inner wall/ceiling frame, you will have a thicker than normal doorway. Therefore, it's not going to look out of place having a thicker door. No one will know until they open the door.
> 
> 
> 
> You can find perfectly suitable doors at the big box stores or purchase from a door company.
> 
> 
> 
> The automatic door bottom, neoprene gasketed header and door stops are all designed to complement a solid door and help to prevent sound from leaking around the door.



@HT Geek
Thank you. I've been researching/planning and I'm back to my soundproofing. Thought I'd pick your brain before finalizing my soundproofing plan.

- going with roxul safe n sound + cheaper of the clips ($2) + hat channel + DD + GG + acoustic sealant for all four walls and ceiling on the inside of the HT room
- should I do the same as above for the walls outside of the HT room?
- my ceiling joists have a ton of height (close to 2 ft) because I leveled off the height across the room to 8 ft - should I fill all of it Roxul safe n sound? Worried about the cost here...
- I am not planning to build any boxes for in ceiling atmos and in wall surround speakers
- I could not convince my wife on taking up some space from the family room for a foyer for communicating door system
- for HT entrance - change from double door (60 x 80) to a single 36 x 80 - solid core door with automatic door bottom (surface installed as it seems easier to install) and threshold
- for door to the HVAC room (AV equipment room) - 36 x 80 solid core door with automatic door bottom (surface installed as it seems easier to install) and threshold
- since I have pipes and ducts running in the HT ceiling, should I attempt to cover them with PVC sheets being sold at tmsoundproofing?
- I also have three ducts feeding my first floor that are running through the HT room ceiling. Do you suggest doing anything to soundproof them so that sound doesn't travel through the vents?

I've included some pictures for reference.

Thanks again for you help.





















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----------



## veger69

HT Geek said:


> Well, here's my 2 cents FWIW:
> 
> 
> 
> Does QuietRock "work"? Yes, with the caveat that it depends on your definition of "working." Presuming you mean does it work for soundproofing, yes for sure. Is it right for you? That depends....
> 
> 
> 
> QuietRock 530 is 5/8" thick and weighs 3.3 psf. Type X 5/8" drywall weighs 2.2 psf. A double-drywall (DD) + Green Glue sandwich will weigh ~4.5 psf. So, from a mass perspective (more is better for sound proofing), DD+GG wins. And I can tell you that IIRC from memory, the DD+GG trumps QR 530 in lab tests as well (i.e. objective verification).
> 
> 
> 
> 1x sheet of QuietRock will typically cost more than 2 sheets of Type X 5/8" drywall (~$20-22). When you add the cost of Green Glue, you can easily top $50 per 4x8 section. Some folks (like me) used only 1/2 the recommended GG to save $ (1 tube per 4x8 sheet versus 2).
> 
> 
> 
> So, ballpark.... 5/8" DD + GG.... Let's presume you need 30 sheets of 4x8 drywall to cover your 700 sq ft. So, 60 sheets total. That's ~$600 in drywall. Let's also presume you purchase 2x 5-gallon Green Glue buckets (to get the 2x tube coverage per 4x8 sheet) for $250 each, plus a dispensing gun for $75. So, that's $575 in Green Glue costs. So, you're at roughly $1,200 + tax + delivery/shipping for your drywall and Green Glue.
> 
> 
> 
> Or you could do 1x layer of QuietRock 530. I can't give you a price guess on that because they only places you'll find it will be drywall contractor supply stores. Most of them will have to special order it, and they will likely charge you for that privilege. But for the sake of discussion let's guesstimate your total cost of materials, including delivery, comes to $800.
> 
> 
> 
> From a price-to-performance perspective, superior sound proofing (DD+GG) will cost you an additional $400-500. Is that worth it to you?
> 
> 
> 
> Now, if you were paying for the labor, I would say the delta would be +$1,000 or so above that figure (depending on contract labor costs in your area). When you throw labor into the mix, you're talking more-or-less double the cost to do DD+GG. But at the DIY level, it's a question of whether the added benefits of the DD+GG route are worth $500 and more of your time.
> 
> 
> 
> If you would like, I'll look through my records to see if I can find an objective comparison between the two concepts in terms of lab reports of sound proofing performance. Might take me a day or two to post the results though. Please reply and let me know if you'd like me to do that, or if the info above is helpful enough, or if you still have questions on this subject.
> 
> 
> 
> EDIT: Yes, I would do the clips & channel either way. They will have a significant impact with either approach (DD/QR).




Thanks yes i would appreciate you getting the numbers because if it's a minor difference I'll save my brothers back since I'm disabled and my brother and a contractor will be doing the labor. Question if doing clips and channel how much would it add to the cost per sqft? And how do you modify the outlets to take the increased Sheetrock channel and clip thickness?
Also does 2 5 gallon buckets of GG for the job mean 2tubes per sheet or 1?

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## veger69

veger69 said:


> Thanks yes i would appreciate you getting the numbers because if it's a minor difference I'll save my brothers back since I'm disabled and my brother and a contractor will be doing the labor. Question if doing clips and channel how much would it add to the cost per sqft? And how do you modify the outlets to take the increased Sheetrock channel and clip thickness?
> 
> Also does 2 5 gallon buckets of GG for the job mean 2tubes per sheet or 1?
> Sent from my iPad using Tapatalk







Sent from my iPad using Tapatalk


----------



## HT Geek

bubbrik said:


> [MENTION=8735410]- going with roxul safe n sound + cheaper of the clips ($2) + hat channel + DD + GG + acoustic sealant for all four walls and ceiling on the inside of the HT room


Check 




> - should I do the same as above for the walls outside of the HT room?


Ordinarily, no need. If you have a *specific* need to do so, then I would consider it (e.g. grandma sleeping in room next door during movie). Otherwise, there's normally insufficient benefit to warrant the extra work and materials.




> - my ceiling joists have a ton of height (close to 2 ft) because I leveled off the height across the room to 8 ft - should I fill all of it Roxul safe n sound? Worried about the cost here...


You could, but again if there's not a need then I wouldn't. That's a lot of space, and a lot of cost as you've pointed out (to fill it with Roxul). It would be useful to throw some pink fluffy (fiberglass batts) up there, but you have an unusually deep space (2 feet). You could spend a lot of $ on pink fluffy (or Roxul). Insulation acts as a velocity absorber, and slows down the speed and energy of sound waves. It causes small air cavities to act like larger air cavities. With a 2' gap to begin with, compared to most people's builds, you have less of a need to add insulation there. If you want to reduce LFE transmission, it's a different ballgame and you'd need to add mass in there (e.g. insulation + drywall cut to fit in between the joists).

Based on the photos you posted, I would suggest focusing your concern on items with greater potential for noise relative to your HT. Namely, the metal HVAC ducts and PVC pipes. I say this for two reasons: 1) if you don't isolate those issues, then from the HT room's perspective it won't matter if you have 2' of Roxul everywhere else - sounds will permeate; and 2) on the off-chance that sound gets through your clips + DD ceiling, those are likely to be the culprits.





> - I am not planning to build any boxes for in ceiling atmos and in wall surround speakers


Are you planning for any canned (recessed) lighting? If so, you should build backer boxes for them.




> - I could not convince my wife on taking up some space from the family room for a foyer for communicating door system
> - for HT entrance - change from double door (60 x 80) to a single 36 x 80 - solid core door with automatic door bottom (surface installed as it seems easier to install) and threshold
> - for door to the HVAC room (AV equipment room) - 36 x 80 solid core door with automatic door bottom (surface installed as it seems easier to install) and threshold


You're on the right path there ^. 

Yes, the surface mount auto door bottoms are easier to install. They're also slightly less effective than the semi-mortised or fully mortised version. However, just like the joist air gap, it quickly gets to the point of splitting hairs when one looks at the big picture and the overall soundproofing strategy. Translation: I would not be concerned; an auto door bottom is better than no door bottom.




> - since I have pipes and ducts running in the HT ceiling, should I attempt to cover them with PVC sheets being sold at tmsoundproofing?


Do you mean this? In principle, yes. However, save yourself some $ and look at Linacoustic or Industrial Noise Duct Liner, K-Flex Duct Liner, or similar products. The 1/2" or 1" version should be sufficient. Check Zoro Tools, NewEgg, Walmart, Jet.com, and Amazon.



> - I also have three ducts feeding my first floor that are running through the HT room ceiling. Do you suggest doing anything to soundproof them so that sound doesn't travel through the vents?


If it's flex duct and the ducts do not originate or terminate in the HT room then it's a non-issue. If they're rigid metal ducts (as you showed in photograph), there's some potential noise from airflow and the metal creaking as the temperature changes (predominantly when the heat is on). Use Linacoustic or similar material described above (it's made for this purpose).

Linacoustic is normally installed on the inside of ducts to quiet the airflow. However, you can also install it on the exterior and it will reduce sound transmission. Or you could just rely on the clips and channel, DD, etc. It's quite frankly likely to be a non-issue. In some homes, noise from the PVC pipes is more likely to be an issue.

So, to re-cap....

Clips + channel, DD, GG are all good. They alone should isolate your from from the vast majority of noise.

For added peace-of-mind (it would suck to rip out walls and add this retroactively if you later decide there is a need) you could add Linacoustic or similar material on the ductwork, and foam or Linacoustic around the PVC pipes. Don't break the bank on this. It's not worth it. Selective dampening may be worthwhile.

You could then add insulation in the joist cavity above the room if you'd like. Pink fluffy fiberglass works nearly as well as Roxul for significantly less $. However, unless you have a known noise issue above, with your 2' gap I would not be overly concerned with it. If the budget is tight, I would spend $ elsewhere.

And finally, I almost forgot to ask but I presume your ceiling will also be de-coupled with clips just like the walls (?).

I attempt to be practical with advice on soundproofing. Most people are cost conscious and/or don't have needs to go to extreme lengths. If you follow my suggestions above, you're unlikely to get 100% sound isolation, but you will get 90%. If you are good with that then save your $. Your cost to insulate the pipes should be minimal. To get your room to the 95%ile, you're looking at 2x-3x your outlay compared to a 90% solution. As I said, IMHO it's just not worth the investment to most people.


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## HT Geek

veger69 said:


> Thanks yes i would appreciate you getting the numbers because if it's a minor difference I'll save my brothers back since I'm disabled and my brother and a contractor will be doing the labor. Question if doing clips and channel how much would it add to the cost per sqft?


I'll get back to you on those questions in 1-2 days (will post reply in this thread) when I can dedicate the time.




> And how do you modify the outlets to take the increased Sheetrock channel and clip thickness?


They're not affected by the clip thickness. You simply use adjustable junction boxes like this (pic below). The JB is screwed into the drywall. It's OK if the screws penetrate the channel, as long as they don't screw into a stud.

Just remove the "wings" if you don't need them.












> Also does 2 5 gallon buckets of GG for the job mean 2tubes per sheet or 1?


In my ballpark estimate, I was referring to the equivalent of 2 tubes per sheet. If you did 1 tube per sheet it might be more cost effective to forego the dispenser gun and purchase tubes. If you go that route, I highly recommend this pneumatic caulk gun for ~$20: Newborn 255


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## HT Geek

*QuietRock 530 vs. DD+GG: FIGHT! LoL*



veger69 said:


> Thanks yes i would appreciate you getting the numbers because if it's a minor difference I'll save my brothers back since I'm disabled and my brother and a contractor will be doing the labor. Question if doing clips and channel how much would it add to the cost per sqft? And how do you modify the outlets to take the increased Sheetrock channel and clip thickness?


TLDR; version: In terms of sound proofing performance, it's a wash. 

I'm surprised to say that analyzing the lab reports indicates there is no appreciable performance difference between DD+GG versus QuietRock 530, presuming DD/GG or QR are used on only one side of the wall. Comparing data from various installation configurations gets complicated quickly. I'm presuming your non-HT room side of the walls are 1/2" gypsum drywall. 

Here's a snapshot of lab test results of various combinations of sound proofing. 












Cutting to the chase regarding what you care about, your options (in terms of performance) boil down to:

*2x 5/8" Drywall + Green Glue | 2x4 Wood Stud | Insulation | 1x 1/2" Drywall = Estimated STC 51*
2x 5/8" Drywall + Green Glue | 2x4 Wood Stud | Insulation | 2x 1/2" Drywall + GG = Estimated STC 56
*2x 5/8" Drywall + Green Glue | Lower end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 1x 1/2" Drywall = Estimated STC 66*
2x 5/8" Drywall + Green Glue | Lower end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 2x 1/2" Drywall = Estimated STC 68
2x 5/8" Drywall + Green Glue | Higher end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 1x 1/2" Drywall = Estimated STC 68
2x 5/8" Drywall + Green Glue | Higher end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 2x 1/2" Drywall = Estimated STC 70

*1x 5/8" QuietRock | 2x4 Wood Stud | Insulation | 1x 1/2" Drywall = Estimated STC 51*
1x 5/8" QuietRock | 2x4 Wood Stud | Insulation | 2x 1/2" Drywall = Estimated STC 53
*1x 5/8" QuietRock | Lower end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 1x 1/2" Drywall = Estimated STC 66*
1x 5/8" QuietRock | Lower end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 2x 1/2" Drywall = Estimated STC 68
1x 5/8" QuietRock | Higher end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 1x 1/2" Drywall = Estimated STC 68
1x 5/8" QuietRock | Higher end Clips & Hat Channel | 2x4 Wood Stud | Insulation | 2x 1/2" Drywall = Estimated STC 70


Some pointers on the chart above:


TL = Transmission Loss
TL Rank = tests ranked from best to worst performance; lower numbers are better performers
STC raw is the raw STC score
STC Ranked is a ranked STC score, similar to TL rankings (lower = better)
DW = DryWall
GG = Green Glue
QR = QuietRock
Double Stud Wall means what it sounds like - 2 wood stud walls with a small air gap between them
Clips = sound proofing clips
All tested walls had insulation
The red highlighted figures are errors in the data. Specifically, the publisher of those reports has duplicate raw data tables. I've asked them to please correct and republish, but in the meantime I don't know which test's set of values is correct (one of them is).
Tests with Green Glue and double drywall on both sides of the wall had Green Glue applied on both sides of the wall

Dissecting the information, we can draw the following general conclusions based on the information in the table:


The amount of Green Glue applied per 4x8 drywall sandwich appears to make a difference (more is better); at least we know there is a difference between 2 tubes vs. 1/2 tube (4:1 ratio)
Green Glue Noiseproofing brand clips outperform IB-1 clips
Clips outperform QuietRock
Double stud walls outperform clips
QuietRock and clips both outperform standard drywall walls
Double Drywall + Clips outperforms Double Drywall + Green Glue (with no clips)
Higher end clips provide ~15 STC improvement, while lower end clips provide ~13 STC improvement (versus no clips)


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## Ladeback

WOW! That's a lot of information. I remember from checking on Quiterock prices that it was a lot cheaper to go with DD & GG. Quiterock was well over $40 a sheet and there I can't see DD & GG being just as much. The only advantage I see is you skip having to do the drywall twice, so you save time. That would make since if you are having someone doing it maybe.


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## veger69

Thank you so much for the info! So assuming a 100db signal what would be the difference in sound reduction for 51 vs 66 or 68 for the higher end clips? And how much would it add to the cost per sqft for channel and clips? HT Geek thanks again for all the info!


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## HT Geek

Ladeback said:


> WOW! That's a lot of information. I remember from checking on Quiterock prices that it was a lot cheaper to go with DD & GG. Quiterock was well over $40 a sheet and there I can't see DD & GG being just as much. The only advantage I see is you skip having to do the drywall twice, so you save time. That would make since if you are having someone doing it maybe.


Yep. If you're paying for labor it can make a significant difference. That said, I calculated my cost of DD+GG at ~$35/4x8 section. $10 drywall x 2 + $13 and some change for 1 tube of GG + sales tax. I only used one tube of GG per 4x8 section. If I'd used the recommended 2 tubes it would have pushed my cost to nearly $50 per 4x8 section. I could have saved $ by going with 5-gallon pails, but then I'd need to add in a $75 GG dispenser. I opted for the tubes out of convenience and because I planned to use 1/2 the recommended application.




veger69 said:


> Thank you so much for the info! So assuming a 100db signal what would be the difference in sound reduction for 51 vs 66 or 68 for the higher end clips?


STC or Sound Transmission Class is an average ratio of sound dampening between roughly 125-4000 Hz. Therefore, it is best utilized as a generalized comparison between two or more scenarios. For example, a solution with an STC of 60 will likely provide better sound proofing than a solution with an STC of 50. However (it seems there's always a gotcha in the A/V world), this is not a universal truth. You could have a STC 50 solution that is very good at absorbing LFE and terrible at dampening higher frequencies, and you could have a STC 60 solution that is vice-versa. If you were concerned with LFE absorption and purchased the 60 STC solution thinking that would solve your problem, you'd be more likely to be disappointed. This is why one has to be a bit skeptical when product retailers and/or manufacturers only advertise STC; it masks very low and very high values. Furthermore, STC tells you nothing about very low (sub-125 Hz) and high freq (>5000 Hz) absorption.

So, to answer your question you need to get into the details of lab and real-world testing. To wit, 100db signal at what frequency? Answer me that and I can give you a comparison of the aforementioned solutions in that context. The caveat is lab tests (theoretically) produce ideal results that are repeatable, but your room is going to have its own characteristics that will influence the final outcome. Still, lab tests are the best thing we've got to form comparisons and make decisions prior to construction. 




> And how much would it add to the cost per sqft for channel and clips? HT Geek thanks again for all the info!


To calculate clips & channel, you need to map out the room. You also need to know the maximum weight each clip is rated for, the recommended pattern, how many hat channels you'll need, and the cost per clip. From the 10,000 foot view, I can tell you a very rough estimate is 100 clips per 200 square feet of an 8' tall room, but that is a VERY rough guesstimate. 

I suggest you check out this calculator at IsoStore. It will provide you a more accurate estimate.

You don't gain much performance between the cheapo IB-1 clips and expensive GGNP clips or the Whisper Clips. The IB-1's are about 1/3 the price of the expensive versions. OTOH, it's a zero-cost change on the labor side (though I believe that's not relevant in your case) versus other methods of improving sound containment.

Most clips are rated for ~36 lbs. DD+GG will give you a bit under 5 psf. If you add a soffit or other items, remember to factor them in.


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## veger69

Here's a drawing of my room it is 9' tall and the opening on the bottom will be a door









I used the calc you linked and it gave 153 clips and 348 lf of track. I included 3 windows and 2 doors, and used 16x13x9 LxWxH. how accurate is the calc?
Sent from my iPad using Tapatalk


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## bubbrik

HT Geek said:


> I would do backer boxes whether you use clips and channel or not. For in-wall and ceiling speakers, that's the ideal method. If you skip the backer boxes but you have the clips & hat channel, the impact will be more or less the same versus not using clips & channel, because it's primarily an issue of flanking noise through the speakers and fixtures that is the concern. Clips and backer boxes are solving two independent problems.
> 
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> 
> Alternative options to DIY backer boxes include mounting in-wall speakers inside columns, and I have seen a room with Atmos speakers bolted to the ceiling and exposed in the room. The latter was in a room with a tall ceiling. They were not particularly obtrusive, but they were visible. When the lights are out, no one sees them.
> 
> 
> 
> The impact of not building backer boxes varies. What essentially happens is some sound is able to travel through holes in them (especially light fixtures), and you'll get some resonance in either that will transmit into the walls/joists/etc. Basically, you introduce a flanking path when they don't have backer boxes.
> 
> 
> 
> Something to consider is there are speakers built with backer boxes of sorts. The best in-wall and in-ceiling speakers are designed as such. Purists will recommend you still put these in backer boxes as well, just because DIY backer boxes are heavy and you KNOW they are built to do their job, whereas a factory box is a bit of an unknown variable.
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@HT Geek

How to attach the backer boxes to the ceiling? Also, would you happen to recall a post with step by step instructions to build backer boxes? I don't any skills for this but want to give it a shot.


Sent from my iPhone using Tapatalk


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## bubbrik

HT Geek said:


> Check
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> Ordinarily, no need. If you have a *specific* need to do so, then I would consider it (e.g. grandma sleeping in room next door during movie). Otherwise, there's normally insufficient benefit to warrant the extra work and materials.
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> You could, but again if there's not a need then I wouldn't. That's a lot of space, and a lot of cost as you've pointed out (to fill it with Roxul). It would be useful to throw some pink fluffy (fiberglass batts) up there, but you have an unusually deep space (2 feet). You could spend a lot of $ on pink fluffy (or Roxul). Insulation acts as a velocity absorber, and slows down the speed and energy of sound waves. It causes small air cavities to act like larger air cavities. With a 2' gap to begin with, compared to most people's builds, you have less of a need to add insulation there. If you want to reduce LFE transmission, it's a different ballgame and you'd need to add mass in there (e.g. insulation + drywall cut to fit in between the joists).
> 
> 
> 
> Based on the photos you posted, I would suggest focusing your concern on items with greater potential for noise relative to your HT. Namely, the metal HVAC ducts and PVC pipes. I say this for two reasons: 1) if you don't isolate those issues, then from the HT room's perspective it won't matter if you have 2' of Roxul everywhere else - sounds will permeate; and 2) on the off-chance that sound gets through your clips + DD ceiling, those are likely to be the culprits.
> 
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> Are you planning for any canned (recessed) lighting? If so, you should build backer boxes for them.
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> You're on the right path there ^.
> 
> 
> 
> Yes, the surface mount auto door bottoms are easier to install. They're also slightly less effective than the semi-mortised or fully mortised version. However, just like the joist air gap, it quickly gets to the point of splitting hairs when one looks at the big picture and the overall soundproofing strategy. Translation: I would not be concerned; an auto door bottom is better than no door bottom.
> 
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> 
> Do you mean this? In principle, yes. However, save yourself some $ and look at Linacoustic or Industrial Noise Duct Liner, K-Flex Duct Liner, or similar products. The 1/2" or 1" version should be sufficient. Check Zoro Tools, NewEgg, Walmart, Jet.com, and Amazon.
> 
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> 
> If it's flex duct and the ducts do not originate or terminate in the HT room then it's a non-issue. If they're rigid metal ducts (as you showed in photograph), there's some potential noise from airflow and the metal creaking as the temperature changes (predominantly when the heat is on). Use Linacoustic or similar material described above (it's made for this purpose).
> 
> 
> 
> Linacoustic is normally installed on the inside of ducts to quiet the airflow. However, you can also install it on the exterior and it will reduce sound transmission. Or you could just rely on the clips and channel, DD, etc. It's quite frankly likely to be a non-issue. In some homes, noise from the PVC pipes is more likely to be an issue.
> 
> 
> 
> So, to re-cap....
> 
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> 
> Clips + channel, DD, GG are all good. They alone should isolate your from from the vast majority of noise.
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> 
> For added peace-of-mind (it would suck to rip out walls and add this retroactively if you later decide there is a need) you could add Linacoustic or similar material on the ductwork, and foam or Linacoustic around the PVC pipes. Don't break the bank on this. It's not worth it. Selective dampening may be worthwhile.
> 
> 
> 
> You could then add insulation in the joist cavity above the room if you'd like. Pink fluffy fiberglass works nearly as well as Roxul for significantly less $. However, unless you have a known noise issue above, with your 2' gap I would not be overly concerned with it. If the budget is tight, I would spend $ elsewhere.
> 
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> 
> And finally, I almost forgot to ask but I presume your ceiling will also be de-coupled with clips just like the walls (?).
> 
> 
> 
> I attempt to be practical with advice on soundproofing. Most people are cost conscious and/or don't have needs to go to extreme lengths. If you follow my suggestions above, you're unlikely to get 100% sound isolation, but you will get 90%. If you are good with that then save your $. Your cost to insulate the pipes should be minimal. To get your room to the 95%ile, you're looking at 2x-3x your outlay compared to a 90% solution. As I said, IMHO it's just not worth the investment to most people.




Yes, I plan to give the same treatment to the ceiling as I will be to the walls. Thanks again for your thorough response.


Sent from my iPhone using Tapatalk


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## HT Geek

bubbrik said:


> How to attach the backer boxes to the ceiling? Also, would you happen to recall a post with step by step instructions to build backer boxes? I don't any skills for this but want to give it a shot.


The photo above from Dozer's theater.... It's a very basic, but effective backer box. 

First, a couple of tips:

Plan the location of backer boxes prior to running wires and pipes
Take into consideration limiters such as cavity clearances (in whatever cavity you will place the backer box, if applicable)


*Here's a brief set of guidelines to create a simple backer box:*

You begin making a cube shape from 1/2" - 3/4" MDF or OSB; leave one side of the cube open
You must make the cube larger than whatever you want to put into it. Factors that influence the dimensions include: size of the object to be contained in the backer box, room for heat dissipation if necessary (usually a good idea), dimensional restrictions based on where it will be mounted (e.g. inside soffit)
Also leave a little extra room for your 2nd layer of material that will go inside the box (1" extra side to side and 1/2" extra interior depth)
Inside the box you will place 1/2" cement board (aka Hardiboard or 'backer board'); any of those can be used. You're looking for density and heat resistance (if this will be a lighting fixture backer box)
Cut your cement board to fit into the inside of all 5 sides of your box, taking care to allow for proper overlap when measuring
Use Green Glue or similar product (e.g. Quiet Glue) to adhere the cement board pieces to the inside of your OSB/MDF box
Utilize clamps to hold the sides together and allow the glue to cure overnight
The final step before installation is to seal the seams inside the box with acoustic sealant
I also recommend sealing the outer seams with caulk as well (flip the box over with the open end facing down to get at all the seams); you could alternatively do this from the inside prior to inserting the cement boards
Drill a hole in whichever side is pertinent to run speaker cable, electrical cable, etc.; then plug the hole with acoustic caulk once you're sure there is enough slack and the cable won't need to move around in the hole (but do this prior to installation/mounting of the box)


*Installing Your Beauty*


You mount ceiling backer boxes with the open side facing down, into the room
If possible, plan your ceiling material installation so you'll have side access to where the backer box is going; this way you can slide the backer box into position after the relevant ceiling area is affixed to your ceiling joists
Don't forget to allow for clearances
Put a thick bead of acoustic caulk on the bottom edge (facing down) of the backer box just prior to installation; you want that caulk to mate with the inside of the ceiling surface and form an airtight seal
Make your cut-outs in the ceiling material BEFORE you install the backer box; this will help you guide the box into position


The good news (for you) is backer boxes for speakers are a bit easier to deal with versus lighting backer boxes. Lighting puts out heat and you have to be aware of IC versus non-IC lighting fixtures, and regardless you'll need space all around the light fixture inside the box to prevent overheating it. Speakers - such as Atmos speakers - don't normally have that problem. For speakers, you just need to be sure it will fit inside the backer box.


*Securing the Backer Box to your Ceiling (or Walls)*
Most of the time you can simply apply a thick caulk to the lip of the backer box where it will mate with the inside of your ceiling, and that's all you need to do. Gravity and the caulk will keep it in place.

If you will be mounting a backer box to the inside of your room, so it's acting more like a speaker baffle per se, you can use any method you like to affix it to the ceiling. I'd be inclined to use lag screws if I could get it aligned with a ceiling joist, or possibly heavy duty toggle bolts or lag screws if it's going to be held up by drywall. You can always add construction glue for good measure if you're concerned.


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## HT Geek

veger69 said:


> Here's a drawing of my room it is 9' tall and the opening on the bottom will be a door
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I used the calc you linked and it gave 153 clips and 348 lf of track. I included 3 windows and 2 doors, and used 16x13x9 LxWxH. how accurate is the calc?
> Sent from my iPad using Tapatalk


That sounds about right, but it is just an estimate. To get an accurate number, you'll need a build plan. You will need to map out a pattern on pen and paper. Corners, windows, doors, etc. all require more clips near them to ensure sufficient support.

SPC has some good visual guides, such as this one:











That is a staggered configuration. Do you see how there are many more clips at the vertical edges of the wall? This is to compensate for shear and surface tension. You must strike a delicate balance between the need for structural rigidity of a wall and the flex provided by the clips, which is good for sound proofing.

Generally speaking, you can do a max of about 4' between clips.


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## HT Geek

bubbrik said:


> [MENTION=8735410]... would you happen to recall a post with step by step instructions to build backer boxes?


Here's another take on it that's a bit more polished than my post.... 

SPC Backer Box Installation Guide


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## veger69

HT Geek said:


> That sounds about right, but it is just an estimate. To get an accurate number, you'll need a build plan. You will need to map out a pattern on pen and paper. Corners, windows, doors, etc. all require more clips near them to ensure sufficient support.
> 
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> SPC has some good visual guides, such as this one:
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> That is a staggered configuration. Do you see how there are many more clips at the vertical edges of the wall? This is to compensate for shear and surface tension. You must strike a delicate balance between the need for structural rigidity of a wall and the flex provided by the clips, which is good for sound proofing.
> 
> 
> 
> Generally speaking, you can do a max of about 4' between clips.




Do you have any info on how to handle windows and doors or just the same as the end of wall. And is there any problem with using 530 on the ceiling I've heard quiterock 500/510 can sag at corners?


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## EC

veger69 said:


> Do you have any info on how to handle windows and doors or just the same as the end of wall. And is there any problem with using 530 on the ceiling I've heard quiterock 500/510 can sag at corners?


Yes you need to put clips at the end of the hat channel whether it is a wall, window or door. I would avoid the quiet rock for cost savings and to add more mass with two 5/8". Also keep in mind there will be drywall (quietrock $$$) wastage and some "F... ups" where a piece of drywall was not measured / cut properly or something unforseen wasn't considered. I'd sleep better knowing it was $15 piece of drywall than quiet rock. 

Depending on where your room is (eg basement). I think it is more important to use double drywall +GG on the ceiling for noise isolation. I did the DD+GG between the floor joist, clips and DD+GG for the ceiling. no regrets especially since there is a piano above the HT.

I can't see sagging as an issue if there are drywall screws in the appropriate areas. Also ceiling edges will be partially held up by the drywall on the wall. yes it is not supposed to touch but the acoustic caulking fills the gap anyway.

Lastly, buy more clips than you think you will need. There $2 each and shouldn't break the bank. Last thing you want is to find out you are short a few clips and can't complete the clip / channel hat. insert phrase here!


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## veger69

Ok I just read more carefully you're post and how do I figure the correct spacing on clips I'm planning on using the 530 quiterock? When you say the most you can get away with is 4' between clips does that depend on the weight?


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## veger69

HT Geek said:


> Generally speaking, you can do a max of about 4' between clips.


This is what I'm taking about could you clarify this statement?


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## veger69

And I need to know how to use whisper clips around a door and windows? because the trim shouldn't be attached to the Sheetrock?


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## doveman

HT Geek said:


> Here are the most commonly referenced clips, in order of least to most expensive. You can likely find the Resilmount A237R cheaper, but this is what I found from a cursory scan.
> 
> IB-1 clips; $1.87/clip
> 
> Whisper Clip; $4.49/clip
> 
> RSIC-1 clips (w/rubber); $4.80/clip
> 
> Resilmount A237R (R = with rubber); $5/clip
> 
> Kinetics IsoMax; $5.25/clip


Thanks for the links.

I e-mailed the first company about the A237 clips and they've said they can only arrange shipping to the UK for orders over $1,000 or if I have a Fed Ex account they can charge the shipping to that. I'm certainly not planning on spending $1,000 but it looks like I can open a personal Fed Ex account, so that might be an option. They haven't given me a quote yet though, so I'll ask them for that before I bother opening an account.

I found the Whisper Clips on e-bay for $399 for 100, which works out about £3.10 per clip, so quite a bit more cost than the A237 for probably not much benefit but the seller doesn't ship to the UK anyway http://www.ebay.co.uk/itm/Commercia...6630110?_trksid=p2141725.m3641.l6368#shpCntId

I can get the GenieClip here for about £3.28 https://www.soundstop.co.uk/ZGENIECLIP.php but they're much deeper than the A237/IB-1 so I can't really use them for the walls. I can probably use them for the ceiling if necessary. Would you think there'd be much benefit in using those, or the A237R, or some other clips rather than the IB-1, for the ceiling where impact noise from above is an issue?

An alternative for the ceiling I thought of was to fix a wooden baton/joist/stud (not sure of the right word) running horizontally along the two longest walls, set a few inches down from the top of the wall and then fixing metal studs between the batons and screwing the drywall into those studs without any clips or hat channel (I'd still put insulation in the space of course). I could use clips and hat channel if necessary but I was thinking that as there would be no contact at all with the original ceiling there might not be any need, as the impact noise would have no direct path into the metal studs. I guess it might still travel down the walls and into the studs that way though. I'm not even sure if this is feasible or has been done before though, or whether the wooden batons attached to the walls could even support the weight of the ceiling drywall, not to mention the walls would need to take the weight of the drywall I'd be adding to them as well.


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## doveman

Also, in terms of perimeter strip for the floor, I'll be using 19mm rubber pads+10mm OSB spacer+18mm OSB+18mm OSB = 65mm, so is that the height I need the perimeter strip to be, so that it's level with the sub-floor but not the stuff on top of that (underlay, cork tiles, etc.)?

I'd have to cut something like this 
https://flooringwarehousedirect.co....dwork-isolating-strip-self-adhesive-15m-roll/

down from 75mm (actually they say they will cut it to order). It's 15m and 6mm thick, so should just about do my room with 2*4m walls and 2*3.3m walls and costs £36.

Does that seem like a good option or could I get something considerably cheaper?


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## HT Geek

EC said:


> I can't see sagging as an issue if there are drywall screws in the appropriate areas. Also ceiling edges will be partially held up by the drywall on the wall. yes it is not supposed to touch but the acoustic caulking fills the gap anyway.
> 
> Lastly, buy more clips than you think you will need. There $2 each and shouldn't break the bank. Last thing you want is to find out you are short a few clips and can't complete the clip / channel hat. insert phrase here!


Two very good points Eric made. 

And as he also mentioned, you need clips on the ends of any wall section (though you do not need them on every hat channel).

I haven't heard any stories of QuietRock being an issue on ceiling installs. As long as there's a sufficient number of clips on the walls and ceiling, they should be fine. It's all about distributing the load evenly amongst the clips.


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## HT Geek

veger69 said:


> Ok I just read more carefully you're post and how do I figure the correct spacing on clips I'm planning on using the 530 quiterock? When you say the most you can get away with is 4' between clips does that depend on the weight?


Yes, though it is a balance between load (weight) support, flex in the walls/ceiling (which you want), and maintaining structural rigidity of the surfaces (no cracks).




veger69 said:


> This is what I'm taking about could you clarify this statement?


I've attached a brief guide for installing Whisper Clips to this post. The methodology is the same for other clips/brands. And I've linked an excellent online guide (also linked below, in this post) that I believe will answer most of your questions and should be a big help for you.

4 feet maximum distance between clips is a ballpark/estimate that fits typical installs. By "typical," I mean DD+GG wall with some can lights. For instance, if add a soffit, you will likely need more clips where the soffit is to support its weight. To estimate how many you'll need, the calculator I previously directed you to will give you a good ballpark estimate. You truly need to draw/map out all your walls and ceiling after you have finalized your design and you know what materials the clips need to hold (weight). And as Eric pointed out, it's wise to add slack to that figure so you don't run out. Say, 5-10%. 

You should make a diagram for each surface (wall, ceiling) and map out your clips prior to construction. Some key concepts to bear in mind:



Spread your clips uniformly to distribute the weight of your walls/ceiling evenly
Channels on walls are laid horizontally, a maximum of every 2' of vertical height (remember these are what your drywall will be attached to, so the 2' distance emulates 24" O.C. studs)
Hat channels on ceilings are a maximum of 2' apart and run perpendicular to your ceiling joists
Corners need clips on every hat channel (every 2')
Where you have open wall/ceiling areas between corners (not near another wall or ceiling), you can place clips every 4'
Only screw your drywall into channels, never into studs
Understand the weight rating of your clips (max load)
Calculate the weight of your wall/ceiling materials
Ensure your design plan is fully factored into your engineering/construction plan (building materials weight)
Use more clips where you have more weight (e.g. soffit)
Doors and windows are handled just like corners (clips 6-8" from edges, every 2')
Anything that needs a hole, needs channel and clips around it and may require additional clips (e.g. HVAC registers, electrical receptacles, light switches)

Surface edges you need more clips. This is for support and prevents the walls from bending/deforming over time, which can cause cracks in the drywall or structural problems. 

There are two pattern methods of installing clips: standard and staggered. What's the difference? Staggered uses more clips, and for that you get a theoretical improvement in performance. AFAIK, all the lab tests with clips & channel use the staggered layout.




veger69 said:


> And I need to know how to use whisper clips around a door and windows? because the trim shouldn't be attached to the Sheetrock


Two different things. You'll have to decide how you want to trim the windows on the inside wall surface. Your clips and channel around the windows will decouple them from the room, so attaching trim to the drywall is not an issue. Just be sure to draft stop inside the walls, per building code.

Regarding clips, treat windows and doors like a wall corner. Use clips about every 2' or so around them, with an emphasis of more clips around the corners of the windows/doors (just like a wall corner). You do this because you can't get clips actually in the corners. THIS is perhaps the most detailed guide you will find online, and should (hopefully) answer all your questions and give you a better idea of the process. That guide has some great illustrations too. 

I'll only disagree slightly with one portion of the guide, which pertains to fire stops. 











There is more than one method of handling fire stops. While the illustration shown will work, it's not required to be done that way.


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## HT Geek

doveman said:


> I can get the GenieClip here for about £3.28 https://www.soundstop.co.uk/ZGENIECLIP.php but they're much deeper than the A237/IB-1 so I can't really use them for the walls. I can probably use them for the ceiling if necessary. Would you think there'd be much benefit in using those, or the A237R, or some other clips rather than the IB-1, for the ceiling where impact noise from above is an issue?


I'll look around to see if I have any lab tests of clips that reported IIC. All of them I recall are airborne noise (STC). You're looking at 2-3 STC difference in performance between cheapo clips (no rubber isolator) and the rubber/foam isolated clips. Keep in mind STC is an average and does not measure the lower end LFE and upper freqs. Personally, if budget is an issue, I would spend $ on Green Glue and drywall, and get the cheaper clips. Going from DD and no GG to DD+GG using the cheapo IB-1 clips will give you a 9 STC improvement. Well worth the investment, versus 2-3 STC for more expensive clips. Naturally, if budget is not a barrier then do both!




> An alternative for the ceiling I thought of was to fix a wooden baton/joist/stud (not sure of the right word) running horizontally along the two longest walls, set a few inches down from the top of the wall and then fixing metal studs between the batons and screwing the drywall into those studs without any clips or hat channel (I'd still put insulation in the space of course). I could use clips and hat channel if necessary but I was thinking that as there would be no contact at all with the original ceiling there might not be any need, as the impact noise would have no direct path into the metal studs. I guess it might still travel down the walls and into the studs that way though. I'm not even sure if this is feasible or has been done before though, or whether the wooden batons attached to the walls could even support the weight of the ceiling drywall, not to mention the walls would need to take the weight of the drywall I'd be adding to them as well.


If I am comprehending your comment above correctly, you are contemplating creating a floating ceiling (independent ceiling joists). If that's true, your plan will not work. You cannot properly support a ceiling via furring strips attached to the walls. You would need vertical studs holding up your floating ceiling.




doveman said:


> Also, in terms of perimeter strip for the floor, I'll be using 19mm rubber pads+10mm OSB spacer+18mm OSB+18mm OSB = 65mm, so is that the height I need the perimeter strip to be, so that it's level with the sub-floor but not the stuff on top of that (underlay, cork tiles, etc.)?
> 
> I'd have to cut something like this
> https://flooringwarehousedirect.co....dwork-isolating-strip-self-adhesive-15m-roll/
> 
> down from 75mm (actually they say they will cut it to order). It's 15m and 6mm thick, so should just about do my room with 2*4m walls and 2*3.3m walls and costs £36.
> 
> Does that seem like a good option or could I get something considerably cheaper?


Perhaps I'm failing recall from a prior post/discussion, but I'm not following this bit with regards to the purpose of a "perimeter strip." Where would you place this and what would be the purpose?


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## BasementBob

HT Geek said:


> It's all about distributing the load evenly amongst the clips.


Although it's important to have the about same load on each clip, I wouldn't say it's "all about" that.




HT Geek said:


> Yes, though it is a balance between load (weight) support, flex in the walls/ceiling (which you want), and maintaining structural rigidity of the surfaces (no cracks).



That's better.


I start with the idea that the way these clips work is that they're damped 'rubber' springs. Each clip has to be loaded into it's working weight range for it to work properly. Too little load, the 'spring' (rubber) isn't compressed enough, and it doesn't work well. Too much load, the 'spring' is compressed too much and may both degrade early (or even fail spectacularly) as well as transmit more sound energy. So rather than a 4' rule, I'd be happier following the individual clip manufacturer's specifications, which would be based upon the load you're hanging on each clip (drywall density per square inch * square inches of drywall held up by that clip). 


If you're planning on hanging additional weight on the wall other than drywall -- absorbers, art paintings, lights, baseboard/trim, whatever -- that needs to be part of the load calculations. If there's additional weight at the top, you may want more clips per square foot at the top than the bottom, maybe, based on the idea that 4x8' drywall panel may be rigid but there's no structural transfer between horizontal sheets of drywall.
And of course 'wall supported cupboards' are pretty much out because you never know how much weight someone will subsequently put into the cupboard.




HT Geek said:


> I'll look around to see if I have any lab tests of clips that reported IIC. All of them I recall are airborne noise (STC).



RSIC-1 clips used to publish their lab tests, which would be multi frequency results (STC-ish). I don't recall any multi frequency IIC results for clips.


There are single number IIC (impact) results published in a few places, like this one:
https://isostore.com/shop/product/pliteq-genieclip/


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## HT Geek

BasementBob said:


> Although it's important to have the about same load on each clip, I wouldn't say it's "all about" that.


Yes... I know. That's why I clarified in the subsequent post, but you're right, I prolly should have edited the original comment. I wanted to be sure he understood clips do have weight limitations, and factors such as soffits usually call for factoring that into the layout plan.




> I start with the idea that the way these clips work is that they're damped 'rubber' springs.


Most do, but they don't all have rubber. The lab tests with/without indicate the clips with rubber or neoprene perform slightly better at soundproofing.




> Each clip has to be loaded into it's working weight range for it to work properly. Too little load, the 'spring' (rubber) isn't compressed enough, and it doesn't work well. Too much load, the 'spring' is compressed too much and may both degrade early (or even fail spectacularly) as well as transmit more sound energy. So rather than a 4' rule, I'd be happier following the individual clip manufacturer's specifications, which would be based upon the load you're hanging on each clip (drywall density per square inch * square inches of drywall held up by that clip).
> 
> 
> If you're planning on hanging additional weight on the wall other than drywall -- absorbers, art paintings, lights, baseboard/trim, whatever -- that needs to be part of the load calculations. If there's additional weight at the top, you may want more clips per square foot at the top than the bottom, maybe, based on the idea that 4x8' drywall panel may be rigid but there's no structural transfer between horizontal sheets of drywall.
> And of course 'wall supported cupboards' are pretty much out because you never know how much weight someone will subsequently put into the cupboard.


Well said and great explanation of the physics. Agreed, manufacturer specs are the key.




> RSIC-1 clips used to publish their lab tests, which would be multi frequency results (STC-ish). I don't recall any multi frequency IIC results for clips.
> 
> 
> There are single number IIC (impact) results published in a few places, like this one:
> https://isostore.com/shop/product/pliteq-genieclip/


Their figures are better than no info, yet unfortunately, IsoStore - like many merchants - fails to publish the source of their lab test claims. I find that practice to be disingenuous. 

I wasn't aware of any GenieClip specific IIC tests (or STC for that matter). I'll try and chase down the real lab reports. At least SPC publishes the lab report ID's, though they do not indicate who the lab was and fail to reveal the actual reports (their site now has doctored lab test reports that were cut and pasted from the real reports). The only way to truly objectively compare product performance is to gain access to the original lab reports and hope there is the same level of detail in each. When details are known but omitted, it leaves open the possibility something significant has not been disclosed.


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## veger69

Unfortunately I just did the demo in the room and learned that two of the walls are shear walls solid plywood sheeting over studs so I'm assuming rails and clips will make no appreciable difference when screwed to a solid wall of plywood. So I'm going to go with a single sheet of 530 quiterock


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## HT Geek

veger69 said:


> Unfortunately I just did the demo in the room and learned that two of the walls are shear walls solid plywood sheeting over studs so I'm assuming rails and clips will make no appreciable difference when screwed to a solid wall of plywood. So I'm going to go with a single sheet of 530 quiterock


That's a bummer. You're right, as you'd effectively create a triple leaf, resulting in increased resonance and reduced performance. At least, presuming you would then have

QUIETROCK | CLIPS & CHANNEL | PLYWOOD | STUDS | DRYWALL

or put another way

Surface 1 | air gap | Surface 2 | air gap | Surface 3


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## veger69

Yes that's correct. So I'm planning on just going with 530 quiterock screwed directly into plywood should I bother with acoustic caulking between the sheets?


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## Ladeback

veger69 said:


> Yes that's correct. So I'm planning on just going with 530 quiterock screwed directly into plywood should I bother with acoustic caulking between the sheets?
> 
> 
> Sent from my iPad using Tapatalk


I would use Green Glue between the plywood and 530.


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## HT Geek

Ladeback said:


> I would use Green Glue between the plywood and 530.


+1

and caulk your seams with acoustic caulk or mud. Probably won't help much to leave 1/4" gap between QR and the floor and ceiling, but I'd do it anyway.

Would be good to caulk between the plywood sheets first as well, before you put up the QR. Might not notice the difference, but might as well. Personal preference if you are good with it as-is or want to do whatever you can to improve the situation.


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## veger69

So if you going to texture the Sheetrock do you acoustic caulk then mud over it? or just acoustic caulk and paint? How do you figure caulk needed my contractor said it would take 20 sheets


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## HT Geek

veger69 said:


> So if you going to texture the Sheetrock do you acoustic caulk then mud over it? or just acoustic caulk and paint? How do you figure caulk needed my contractor said it would take 20 sheets


I'd say it depends. First on whether or not you will have the walls exposed. If you're going to put up fabric wall panels over the drywall for example, there's no requirement to have the drywall taped, mudded and sanded x3 times. You could leave it rough w/screws visible. In that scenario (which saves $ btw), I would do acoustic caulk in all the seams. 

OTOH, if you are going to have your walls painted and they will be visible, I'd suggest normal mudding procedure. It's most important to seal the gaps. Acoustic caulk is preferable, but the concept of sealing them period is most important. If you're going to be looking at the walls when all is said and done, it's a surer bet of what the outcome will look like if you stick with a traditional mudding and sanding procedure. 

You should use acoustic caulk in the 1/4" gap above and below the sheets either way.

How much caulk to use depends on what size bead you use and how good you are at caulking.  I'd pick up a 12-pack of either Green Glue's Acoustic Sealant or OSI SC-175. The latter is cheaper, the former a bit easier to apply IMHO (I've used both). A case of either should set you back $75-$100 or so. The OSI you can get from most drywall contractor supply stores or Home Depot (online only; free shipping). You'll find you will need it in other areas as well, not just for your drywall seams. It's great almost anywhere in your room where you need to seal a gap.


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## doveman

HT Geek said:


> I'll look around to see if I have any lab tests of clips that reported IIC. All of them I recall are airborne noise (STC). You're looking at 2-3 STC difference in performance between cheapo clips (no rubber isolator) and the rubber/foam isolated clips. Keep in mind STC is an average and does not measure the lower end LFE and upper freqs. Personally, if budget is an issue, I would spend $ on Green Glue and drywall, and get the cheaper clips. Going from DD and no GG to DD+GG using the cheapo IB-1 clips will give you a 9 STC improvement. Well worth the investment, versus 2-3 STC for more expensive clips. Naturally, if budget is not a barrier then do both!


Oh wow! I should definitely use DD+GG if it gives a 9 STC improvement over just DD. Even if they weren't more expensive, I wouldn't really want to use the rubber/foam isolated clips on the walls as most of them are quite a bit deeper than the IB-1 clips and I don't have room to lose that extra depth.



> If I am comprehending your comment above correctly, you are contemplating creating a floating ceiling (independent ceiling joists). If that's true, your plan will not work. You cannot properly support a ceiling via furring strips attached to the walls. You would need vertical studs holding up your floating ceiling.


I'm sure I described it badly but I wasn't suggesting using furring strips attached to the walls to support a ceiling. I was thinking of a solid baton of wood running along the length of the two walls which metal (or wooden) joists could be hung between. However I've just read about joist hangers like these http://www.diydoctor.org.uk/projects/joisthangers.htm so maybe they'd be a more practical option, with a pair for each joist. There's three possible options, a) clips+channel attached to the original ceiling, b) wall joist hangers and joists, c) wall joist hangers and joists AND clips and channel.

If b works out cheaper than a then that might be the better option, particularly if it has some advantage in terms of impact noise by breaking any direct connection with the original ceiling. I'd also probably be able to save some money by fitting the joist hangers to the wall myself, whereas I'd probably struggle to screw the clips into the ceiling as it's quite fiddly standing on a ladder and screwing into something above you anyway but I suffer from vertigo and neck pain which makes it even harder.

If the impact noise is liable to travel down the wall and transfer into the joists however (or at least if more impact noise is able to transfer that way than would transfer via option a), then it may be necessary to use clips+channel as well (i.e option c) which is obviously the most expensive option but may provide the best reduction in impact noise (whether the difference is worth the extra cost is another matter).



> Perhaps I'm failing recall from a prior post/discussion, but I'm not following this bit with regards to the purpose of a "perimeter strip." Where would you place this and what would be the purpose?


The drawing here shows where it goes https://flooringwarehousedirect.co.uk/product/karma-perimeter-strip/ Basically it's used to isolate the new subfloor from the structural wall and the baseboard from the floor. I think it's also known as isolation tape. It's not shown there but normally it's recommend to have the strip come to just below the top of the subfloor and then fill the gap with caulking, as shown in the Cochlear Refurb PDF I posted previously. I notice that this product seems about 3x cheaper than the one I linked to in my previous post and is a 25m roll rather than 15m, so I'm even more uncertain which product I should buy now!


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## HT Geek

doveman said:


> Oh wow! I should definitely use DD+GG if it gives a 9 STC improvement over just DD.


Just to be clear, here's the difference:

1x drywall | 1x drywall: STC 40
2x drywall | 1x drywall: STC 42
2x drywall + GG | 1x drywall: STC 52
IB-1 Clips/Channel + 1x drywall | 1x drywall: STC 53
IB-1 Clips/Channel + 2x drywall | 1x drywall: STC 58
IB-1 Clips/Channel + 2x drywall + GG | 1x drywall: STC 67




> I'm sure I described it badly but I wasn't suggesting using furring strips attached to the walls to support a ceiling. I was thinking of a solid baton of wood running along the length of the two walls which metal (or wooden) joists could be hung between. However I've just read about joist hangers like these http://www.diydoctor.org.uk/projects/joisthangers.htm so maybe they'd be a more practical option, with a pair for each joist. There's three possible options, a) clips+channel attached to the original ceiling, b) wall joist hangers and joists, c) wall joist hangers and joists AND clips and channel.


I'm still not sure I have a clear picture in my mind of what you would attach the joist hangers to. What part of the structure of your home would they be attached to? What would be holding up the new, floating ceiling?

Ideally, you'd want to do either method a or method c, as they would provide superior isolation of the ceiling.




> The drawing here shows where it goes https://flooringwarehousedirect.co.uk/product/karma-perimeter-strip/ Basically it's used to isolate the new subfloor from the structural wall and the baseboard from the floor. I think it's also known as isolation tape. It's not shown there but normally it's recommend to have the strip come to just below the top of the subfloor and then fill the gap with caulking, as shown in the Cochlear Refurb PDF I posted previously. I notice that this product seems about 3x cheaper than the one I linked to in my previous post and is a 25m roll rather than 15m, so I'm even more uncertain which product I should buy now!


The recommended practice is to leave a 6mm gap and fill with acoustic caulk. You'd leave the gap where the isolation tape is shown in the diagram. I would recommend that route (air gap and fill with caulk) versus that tape, which essentially re-couples the surfaces.


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## doveman

HT Geek said:


> Just to be clear, here's the difference:
> 
> 1x drywall | 1x drywall: STC 40
> 2x drywall | 1x drywall: STC 42
> 2x drywall + GG | 1x drywall: STC 52
> IB-1 Clips/Channel + 1x drywall | 1x drywall: STC 53
> IB-1 Clips/Channel + 2x drywall | 1x drywall: STC 58
> IB-1 Clips/Channel + 2x drywall + GG | 1x drywall: STC 67


Thanks, it's useful to have the various options listed like that for comparison.



> I'm still not sure I have a clear picture in my mind of what you would attach the joist hangers to. What part of the structure of your home would they be attached to? What would be holding up the new, floating ceiling?
> 
> Ideally, you'd want to do either method a or method c, as they would provide superior isolation of the ceiling.


The joist hangers are fixed to the walls, specifically in my case the two longest walls so that the joists would span the width (3.3m) off the room. Ideally the joists would be metal I guess to reduce the weight. I know that I can use metal rather than wood for the vertical wall studs that hold the drywall so presumably the same thing would be strong enough to hold the ceiling drywall but I'm not sure if they'd be compatible with the wall joist hangers or if I'd need to find something else.

The question is whether having the ceiling drywall attached to joists hanging from the wall in this way (i.e. method b) rather than the ceiling via clips and channel would provide more impact noise isolation. Certainly method c would provide the most isolation but it would also be the most expensive so I'd need to be sure it was really worth it before doing that.



> The recommended practice is to leave a 6mm gap and fill with acoustic caulk. You'd leave the gap where the isolation tape is shown in the diagram. I would recommend that route (air gap and fill with caulk) versus that tape, which essentially re-couples the surfaces.


Surely the caulk re-couples the surfaces as well though? The question is whether it re-couples them less than the tape would and also whether there's any benefit to sealing off the wall perimeter underneath the floor, which could help prevent noise transferring from the wall into the underfloor space. Bear in mind that the part of the wall below the subfloor doesn't have any plaster covering the cinderblock, or at least it's not as thick or unbroken as the rest of the wall, so the mass of 25mm of plaster that the rest of the wall has covering it isn't there to help stop sound escaping.

I drew the attached diagram to illustrate, showing the 25mm insulation (pink), 10mm OSB spacer (brown), 19mm rubber pad (black) and two layers of 18mm OSB on top, with caulk (white) at the top. Presumably if you were using just caulk you wouldn't fill the entire gap but just to a depth of around 18mm to prevent the OSB shifting (the two layers will be glued and screwed so if one layer can't move, neither can the other). This leaves the rest of the gap unfilled, potentially allowing sound leakage from the wall into the underfloor. There will be 25mm of insulation at the bottom but that still leaves about 22mm empty space between the insulation and the caulk and insulation doesn't really block sound anyway.

I'm concerned that this perimeter gap will be a weak spot for sound leakage coming up into my room from both the wall and the concrete slab below. The rest of the floor has the mass of two layers of OSB blocking any noise from below getting into my room but at the perimeter there's only caulking, which has very little mass, so surely that's going to undermine the whole floor?

Regarding the rubber pads, I've been told I need to space them slightly (2-3mm) away from the wall to allow them to bulge when loaded. I'm also a bit concerned about fire safety, as rubber starts to melt at 180c, whereas wood only auto-ignites at 300c+, so if there was a fire in the flat below me (I understand house fires can reach 600c+) it's possible the heat coming through the concrete slab would cause the pads to melt and the floor to collapse before I was aware of the fire or able to evacuate and the floor or things on the floor could end up blocking my doors!


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## HT Geek

doveman said:


> The joist hangers are fixed to the walls, specifically in my case the two longest walls so that the joists would span the width (3.3m) off the room. Ideally the joists would be metal I guess to reduce the weight. I know that I can use metal rather than wood for the vertical wall studs that hold the drywall so presumably the same thing would be strong enough to hold the ceiling drywall but I'm not sure if they'd be compatible with the wall joist hangers or if I'd need to find something else.


Hmm. I hope you fully understand how joist hangers function. They need to be attached to beams. The beams must be supported vertically.

Metal joists are more expensive than wood (though not by much) and offer a few advantages, notably: a) potentially more load bearing capability, but depends on gauge and what you are comparing it to; b) guaranteed straight. I'm not sure about the process to attach metal joists to a beam with joist hangers. Have you researched it? I know when they are laid on top of a stud wall, the attachment method is different vs. wood joists.

Anyway, point is there's two ways to attach ceiling or floor joists. One is to the side of a beam with joist hangers, and the other is they lay on top of your stud walls. The latter method is more common. If you just do clips & channel on the existing ceiling, it would be a non-issue. 




> The question is whether having the ceiling drywall attached to joists hanging from the wall in this way (i.e. method b) rather than the ceiling via clips and channel would provide more impact noise isolation. Certainly method c would provide the most isolation but it would also be the most expensive so I'd need to be sure it was really worth it before doing that.


Depends on the details of your construction. Generally speaking, a true floating ceiling will be better than clips & channel. However, that presumes complete isolation from the structural ceiling (thus the term, "floating"). 





> Surely the caulk re-couples the surfaces as well though? The question is whether it re-couples them less than the tape would and also whether there's any benefit to sealing off the wall perimeter underneath the floor, which could help prevent noise transferring from the wall into the underfloor space. Bear in mind that the part of the wall below the subfloor doesn't have any plaster covering the cinderblock, or at least it's not as thick or unbroken as the rest of the wall, so the mass of 25mm of plaster that the rest of the wall has covering it isn't there to help stop sound escaping.
> 
> I drew the attached diagram to illustrate, showing the 25mm insulation (pink), 10mm OSB spacer (brown), 19mm rubber pad (black) and two layers of 18mm OSB on top, with caulk (white) at the top. Presumably if you were using just caulk you wouldn't fill the entire gap but just to a depth of around 18mm to prevent the OSB shifting (the two layers will be glued and screwed so if one layer can't move, neither can the other). This leaves the rest of the gap unfilled, potentially allowing sound leakage from the wall into the underfloor. There will be 25mm of insulation at the bottom but that still leaves about 22mm empty space between the insulation and the caulk and insulation doesn't really block sound anyway.
> 
> I'm concerned that this perimeter gap will be a weak spot for sound leakage coming up into my room from both the wall and the concrete slab below. The rest of the floor has the mass of two layers of OSB blocking any noise from below getting into my room but at the perimeter there's only caulking, which has very little mass, so surely that's going to undermine the whole floor?


The mass of caulk vs. joist tape won't matter. Additional mass there won't matter period. The goal at the edge is to eliminate a flanking path. LFE will pass through no matter what it is. The mass helps dampen LFE, but it's the mass of the whole layer(s) that matters. Basically, it's a non-issue unless you want to fill the corner with lead or iron. 

The goal at the perimeter is to maintain a small air gap between edges of the walls/ceiling/floor so that one does not vibrate the other directly via contact. Acoustical caulk will do a better job than the joist tape because it's a smaller footprint/contact point. Plus the caulk is like rubber after it dries. You want the small air gap in there, behind the caulk. The caulk is going to do as good a job or a better job than the joist tape where it actually makes contact with both both surfaces. Furthermore, it ensures there's no hole for high freqs to pass through easily (vis-a-vis flanking).




> Regarding the rubber pads, I've been told I need to space them slightly (2-3mm) away from the wall to allow them to bulge when loaded. I'm also a bit concerned about fire safety, as rubber starts to melt at 180c, whereas wood only auto-ignites at 300c+, so if there was a fire in the flat below me (I understand house fires can reach 600c+) it's possible the heat coming through the concrete slab would cause the pads to melt and the floor to collapse before I was aware of the fire or able to evacuate and the floor or things on the floor could end up blocking my doors!


I believe you're overthinking that and would have other issues to worry about in that situation. Overall, your room post-build will be more robust if you're concerned about having time to get out in a fire.

Rubber will turn viscous before it burns. I'd expect your floor to lower slightly and perhaps move a bit. However, unless the liquified can find a way to fall into a hole, it won't go anywhere. It would simply change form from a solid to a liquid. That wouldn't happen instantaneously either.


----------



## Ladeback

HT Geek said:


> Just to be clear, here's the difference:
> 
> 1x drywall | 1x drywall: STC 40
> 2x drywall | 1x drywall: STC 42
> 2x drywall + GG | 1x drywall: STC 52
> IB-1 Clips/Channel + 1x drywall | 1x drywall: STC 53
> IB-1 Clips/Channel + 2x drywall | 1x drywall: STC 58
> IB-1 Clips/Channel + 2x drywall + GG | 1x drywall: STC 67
> 
> 
> 
> So what would the STC be if you use IB-3 clips to decouple the walls at the top, 5/8" DD + GG on one side and single layer of 5/8"? That's what I was thinking of doing on my walls to save width, time and little cost maybe.


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## HT Geek

Ladeback said:


> So what would the STC be if you use IB-3 clips to decouple the walls at the top, 5/8" DD + GG on one side and single layer of 5/8"? That's what I was thinking of doing on my walls to save width, time and little cost maybe.


Those are normally used to decouple walls from ceilings. For instance, during double wall construction you could use IB-3 clips to secure your inner wall to the outer (structural) one, to help maintain the integrity of your inner wall while keeping them decoupled. I did that in my HT room and the interior walls are rock solid.

How would you propose using the clips in your situation? What would the clips be decoupling the walls from?


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## Ladeback

HT Geek said:


> Those are normally used to decouple walls from ceilings. For instance, during double wall construction you could use IB-3 clips to secure your inner wall to the outer (structural) one, to help maintain the integrity of your inner wall while keeping them decoupled. I did that in my HT room and the interior walls are rock solid.
> 
> How would you propose using the clips in your situation? What would the clips be decoupling the walls from?


I was going to use them to to decouple the walls to the ceiling joist in my basement. I was thinking then I wouldn't need clips and channel on the walls.


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## HT Geek

HT Geek said:


> The mass of caulk vs. joist tape won't matter. Additional mass there won't matter period. The goal at the edge is to eliminate a flanking path. LFE will pass through no matter what it is. The mass helps dampen LFE, but it's the mass of the whole layer(s) that matters. Basically, it's a non-issue unless you want to fill the corner with lead or iron.
> 
> The goal at the perimeter is to maintain a small air gap between edges of the walls/ceiling/floor so that one does not vibrate the other directly via contact. Acoustical caulk will do a better job than the joist tape because it's a smaller footprint/contact point. Plus the caulk is like rubber after it dries. You want the small air gap in there, behind the caulk. The caulk is going to do as good a job or a better job than the joist tape where it actually makes contact with both both surfaces. Furthermore, it ensures there's no hole for high freqs to pass through easily (vis-a-vis flanking).


 @doveman, this chart may help to visualize my point about using acoustic caulk in the corner seams:











Legend:*

Blue = Common Wood Stud Wall, STC=40
Black = Common Wall with poor Seal, STC=26
Green = Green Glue Wood Stud Wall, STC=56
Red = Green Glue Wood Stud Wall with poor seals, STC =27



Speaking of good seals....











Above* is in order of least to most effective applications of acoustic sealant on a wall, from the perspective of the footers and bottom of the drywall. The pics above are (in left-to-right order):



Bad - Sealant under frame only. Sound can easily enter and exit the wall cavities
Good - A good start for remodeling jobs where you are adding drywall to an existing wall
Very good - Beads under drywall to keep sound from leaking into the cavity, and under frame for redundancy
Best - A heavy bead under the walls plates plus a bead under each drywall layer


* Source: *Understanding Flanking Noise*, Trademark Soundproofing, Chestnut Hill, New York, retrieved August 22, 2017 from http://www.tmsoundproofing.com/understanding-flanking-noise.html


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## HT Geek

Ladeback said:


> I was going to use them to to decouple the walls to the ceiling joist in my basement. I was thinking then I wouldn't need clips and channel on the walls.


If you do that, what will be holding up your house???

In a room-within-a-room setup, IB-3 clips work because the walls are not considered load bearing. They may be holding up a floating ceiling, but that's it. And the IB-3's aside from decoupling those walls from the structural ceiling joists, also help to stiffen the walls. However, all of that only works because there is already a solid structure, and you only need the new walls/ceiling to support the weight of the drywall + whatever hanging on them and that's it. The interior wall studs don't hold up your house.


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## doveman

HT Geek said:


> Hmm. I hope you fully understand how joist hangers function. They need to be attached to beams. The beams must be supported vertically.
> 
> Metal joists are more expensive than wood (though not by much) and offer a few advantages, notably: a) potentially more load bearing capability, but depends on gauge and what you are comparing it to; b) guaranteed straight. I'm not sure about the process to attach metal joists to a beam with joist hangers. Have you researched it? I know when they are laid on top of a stud wall, the attachment method is different vs. wood joists.
> 
> Anyway, point is there's two ways to attach ceiling or floor joists. One is to the side of a beam with joist hangers, and the other is they lay on top of your stud walls. The latter method is more common. If you just do clips & channel on the existing ceiling, it would be a non-issue.


I'm not sure why joist hangers need to be attached to beams rather than directly to the wall, although the only picture on that website does seem to show them attached to a beam http://www.diydoctor.org.uk/project_images/joisthangers/face-fixed-joist-hanger.jpg

From what you've said about supporting beams vertically, I presume it wouldn't be possible to just screw a piece of wood to the wall and then attach the joist hangers to that?

It mentions masonry joist hangers on that page too. A horizontal chase has to be cut into the wall for those to be slotted in to but that would be an option.

However, if just using IB-1 clips and channel on the existing ceiling will provide sufficient impact noise reduction then I guess that's the easiest option, even if I will need to pay someone to do all the work.



> The mass of caulk vs. joist tape won't matter. Additional mass there won't matter period. The goal at the edge is to eliminate a flanking path. LFE will pass through no matter what it is. The mass helps dampen LFE, but it's the mass of the whole layer(s) that matters. Basically, it's a non-issue unless you want to fill the corner with lead or iron.
> 
> The goal at the perimeter is to maintain a small air gap between edges of the walls/ceiling/floor so that one does not vibrate the other directly via contact. Acoustical caulk will do a better job than the joist tape because it's a smaller footprint/contact point. Plus the caulk is like rubber after it dries. You want the small air gap in there, behind the caulk. The caulk is going to do as good a job or a better job than the joist tape where it actually makes contact with both both surfaces. Furthermore, it ensures there's no hole for high freqs to pass through easily (vis-a-vis flanking).


So when you say "it's the mass of the whole layer(s) that matters" as far as LFE reduction is concerned, are you're saying that having holes right through the two layers of OSB at various points, whether at the perimeter or in the middle of the floor, will have no detrimental effect on the LFE reduction? Or a solid door with a 1/2" gap at the bottom will block LFE just as well as a door without any gap? That would only seem to make sense if LF sound waves are too "big" to pass through small spaces but maybe that's true. Surely greater mass provides greater reduction of mid and high frequencies as well though doesn't it, in which case having a relatively high mass of two layers of OSB over most of the floor but a much lower mass of only caulk at the perimeter would seem to provide a weak spot through which those frequencies could pass.

If that's true, then perhaps replacing the insulation at the perimeter, between the wall and the rubber pad, with a piece of OSB (or something else with similar or greater mass), as shown in red in the attached drawing, would help? Whilst this could only be about 28mm high to ensure it only touches the rubber pad and not the OSB layers and thus it won't be the same height/mass as the 36mm of the two OSB layers, perhaps it would be better than just having air or insulation there, whilst still having caulk at the top to allow the wood to expand.



> I believe you're overthinking that and would have other issues to worry about in that situation. Overall, your room post-build will be more robust if you're concerned about having time to get out in a fire.
> 
> Rubber will turn viscous before it burns. I'd expect your floor to lower slightly and perhaps move a bit. However, unless the liquified can find a way to fall into a hole, it won't go anywhere. It would simply change form from a solid to a liquid. That wouldn't happen instantaneously either.


It's the melting rather than burning that's a concern, as it will start to do that at 180c whereas the wooden joists wouldn't lose their structural integrity until they auto-ignite at 300c. Whether the rubber can fall into the porous concrete slab or if it just spreads sideways into the insulation, it will still result in the flooring above the pads dropping and depending on which pads start to melt first, it could result in the flooring near the door raising up and blocking it, or just heavy furniture falling over and blocking the escape route or injuring me.

Now I may well be overthinking it and maybe if I haven't evacuated before that happens I'd be toast anyway but I'll probably need to satisfy Building Control that I'm not causing any safety issues. Why do you say that overall my room post-build will be more robust?


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## doveman

HT Geek said:


> @doveman, this chart may help to visualize my point about using acoustic caulk in the corner seams:


Thanks, that's useful although I still wonder if the STC wouldn't be even better if the lower part of the perimeter gap was filled with some mass.



> Above* is in order of least to most effective applications of acoustic sealant on a wall, from the perspective of the footers and bottom of the drywall.


Thanks for that too, I might have been inclined to only fit caulk beneath the inner layer of drywall but I can see the benefits of fitting it beneath both layers.


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## Ladeback

HT Geek said:


> If you do that, what will be holding up your house???
> 
> In a room-within-a-room setup, IB-3 clips work because the walls are not considered load bearing. They may be holding up a floating ceiling, but that's it. And the IB-3's aside from decoupling those walls from the structural ceiling joists, also help to stiffen the walls. However, all of that only works because there is already a solid structure, and you only need the new walls/ceiling to support the weight of the drywall + whatever hanging on them and that's it. The interior wall studs don't hold up your house.


So in reading this you agree? Two of the walls well be under beams that are holding up our house. I was going to do something like this in those areas.


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## HT Geek

Doveman, I'll post later today when I'm still a PC, but wanted to post short reply.

Adding mass lowers the resonance frequency. You're right that plugging gaps in your floor is better than not plugging them, however IMHO, in your case the higher priority ought to be sealing the corner seams. 

To some extent, sound travels like water. It will permeate through cracks, especially higher freqs with shorter wavelengths. LFE will vibrate. The slight additional mass from those small gaps just won't make a significant difference, compared to the other items. At least that's my thinking, FWIW.

Sent from my ONE A2005 using Tapatalk


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## HT Geek

HT Geek said:


> Doveman, I'll post later today when I'm still a PC, but wanted to post short reply.
> 
> Adding mass lowers the resonance frequency. You're right that plugging gaps in your floor is better than not plugging them, however IMHO, in your case the higher priority ought to be sealing the corner seams.
> 
> To some extent, sound travels like water. It will permeate through cracks, especially higher freqs with shorter wavelengths. LFE will vibrate. The slight additional mass from those small gaps just won't make a significant difference, compared to the other items. At least that's my thinking, FWIW.
> 
> Sent from my ONE A2005 using Tapatalk


*When I'm at a PC. Damn, I hate typing on "smart" phone form factors. 

Sent from my ONE A2005 using Tapatalk


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## HT Geek

Ladeback said:


> So in reading this you agree? Two of the walls well be under beams that are holding up our house. I was going to do something like this in those areas.


Sure. You can certainly duplicate that method on those two walls. 

Sent from my ONE A2005 using Tapatalk


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## Ladeback

HT Geek said:


> Sure. You can certainly duplicate that method on those two walls.
> 
> Sent from my ONE A2005 using Tapatalk


Then I should be able to do it on the end walls as well. The screen wall end is up against a concrete foundation wall and the end does not support anything above. The design I am going with is the first one on post #77 of build my thread that is my signature.


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## doveman

HT Geek said:


> Doveman, I'll post later today when I'm still a PC, but wanted to post short reply.
> 
> Adding mass lowers the resonance frequency. You're right that plugging gaps in your floor is better than not plugging them, however IMHO, in your case the higher priority ought to be sealing the corner seams.
> 
> To some extent, sound travels like water. It will permeate through cracks, especially higher freqs with shorter wavelengths. LFE will vibrate. The slight additional mass from those small gaps just won't make a significant difference, compared to the other items. At least that's my thinking, FWIW.


I thought that the resonant frequency is lowered by increasing the space between the structural wall and the drywall (including by the use of insulation, which acts to make the space larger than it is from a thermodynamic point of view)? I thought mass served some other purpose?

When you say that sealing the corner seams is a higher priority than plugging gaps in the floor, do you mean sealing the 6mm perimeter gap with caulk is more important than filling the space (or at least the bottom part of it) at the edge under the subfloor with a piece of OSB, as I showed in my last drawing?

I'm not sure what you mean by "the slight additional mass from those small gaps" as a gap obviously doesn't have any mass. The water analogy is useful to a certain extent when explaining how sound will escape through any gaps but we need another analogy when talking about differences in mass across the floor and what effect this might have on the soundproofing, as a fishtank keeps the water in regardless of whether one part of the glass is thinner than the rest.

Whilst LFE soundwaves are bigger than higher frequency ones, as they vibrate the air I guess this air can travel through any size gap, whether at the perimeter of the floor or at the bottom of a door. With my two-layer OSB floor, the mass of it should block the LFE but at the perimeter where there is only caulk, I would think the low mass of it would allow some of the LFE (and maybe higher frequencies) to get through. If that wasn't the case, surely we could just use low mass for the entire floor? If the high mass is needed to lower the resonant frequency, wouldn't the perimeter area where there is only low mass caulk still have a higher resonant frequency than the rest of the floor and thus be a weak point? I do know that the 25mm plaster on my walls, which has much more mass than caulk, isn't effectively blocking mid to high frequencies from escaping out of the wall.

I was actually wondering whether replacing the 25mm insulation underneath my subfloor with 18mm OSB would be beneficial? I think the cost would be about the same for each. I would either need to cut holes 8mm deep for the rubber pads (so that they're raised up 10mm above the concrete slab) or if it would be too difficult to get the holes flat, just cut right through and put a 10mm spacer under the pads. Even though 25mm insulation would make the gap larger from a resonant frequency perspective, maybe the mass of 18mm OSB would still be more beneficial? Obviously I couldn't use OSB instead of insulation with the walls or ceiling as it would add too much weight but that probably isn't an issue with the floor.

Sorry if I sound a bit dumb. Physics never was my strong point!


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## bubbrik

HT Geek said:


> Check
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Ordinarily, no need. If you have a *specific* need to do so, then I would consider it (e.g. grandma sleeping in room next door during movie). Otherwise, there's normally insufficient benefit to warrant the extra work and materials.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You could, but again if there's not a need then I wouldn't. That's a lot of space, and a lot of cost as you've pointed out (to fill it with Roxul). It would be useful to throw some pink fluffy (fiberglass batts) up there, but you have an unusually deep space (2 feet). You could spend a lot of $ on pink fluffy (or Roxul). Insulation acts as a velocity absorber, and slows down the speed and energy of sound waves. It causes small air cavities to act like larger air cavities. With a 2' gap to begin with, compared to most people's builds, you have less of a need to add insulation there. If you want to reduce LFE transmission, it's a different ballgame and you'd need to add mass in there (e.g. insulation + drywall cut to fit in between the joists).
> 
> 
> 
> Based on the photos you posted, I would suggest focusing your concern on items with greater potential for noise relative to your HT. Namely, the metal HVAC ducts and PVC pipes. I say this for two reasons: 1) if you don't isolate those issues, then from the HT room's perspective it won't matter if you have 2' of Roxul everywhere else - sounds will permeate; and 2) on the off-chance that sound gets through your clips + DD ceiling, those are likely to be the culprits.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Are you planning for any canned (recessed) lighting? If so, you should build backer boxes for them.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You're on the right path there ^.
> 
> 
> 
> Yes, the surface mount auto door bottoms are easier to install. They're also slightly less effective than the semi-mortised or fully mortised version. However, just like the joist air gap, it quickly gets to the point of splitting hairs when one looks at the big picture and the overall soundproofing strategy. Translation: I would not be concerned; an auto door bottom is better than no door bottom.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Do you mean this? In principle, yes. However, save yourself some $ and look at Linacoustic or Industrial Noise Duct Liner, K-Flex Duct Liner, or similar products. The 1/2" or 1" version should be sufficient. Check Zoro Tools, NewEgg, Walmart, Jet.com, and Amazon.
> 
> 
> 
> 
> 
> 
> 
> If it's flex duct and the ducts do not originate or terminate in the HT room then it's a non-issue. If they're rigid metal ducts (as you showed in photograph), there's some potential noise from airflow and the metal creaking as the temperature changes (predominantly when the heat is on). Use Linacoustic or similar material described above (it's made for this purpose).
> 
> 
> 
> Linacoustic is normally installed on the inside of ducts to quiet the airflow. However, you can also install it on the exterior and it will reduce sound transmission. Or you could just rely on the clips and channel, DD, etc. It's quite frankly likely to be a non-issue. In some homes, noise from the PVC pipes is more likely to be an issue.
> 
> 
> 
> So, to re-cap....
> 
> 
> 
> Clips + channel, DD, GG are all good. They alone should isolate your from from the vast majority of noise.
> 
> 
> 
> For added peace-of-mind (it would suck to rip out walls and add this retroactively if you later decide there is a need) you could add Linacoustic or similar material on the ductwork, and foam or Linacoustic around the PVC pipes. Don't break the bank on this. It's not worth it. Selective dampening may be worthwhile.
> 
> 
> 
> You could then add insulation in the joist cavity above the room if you'd like. Pink fluffy fiberglass works nearly as well as Roxul for significantly less $. However, unless you have a known noise issue above, with your 2' gap I would not be overly concerned with it. If the budget is tight, I would spend $ elsewhere.
> 
> 
> 
> And finally, I almost forgot to ask but I presume your ceiling will also be de-coupled with clips just like the walls (?).
> 
> 
> 
> I attempt to be practical with advice on soundproofing. Most people are cost conscious and/or don't have needs to go to extreme lengths. If you follow my suggestions above, you're unlikely to get 100% sound isolation, but you will get 90%. If you are good with that then save your $. Your cost to insulate the pipes should be minimal. To get your room to the 95%ile, you're looking at 2x-3x your outlay compared to a 90% solution. As I said, IMHO it's just not worth the investment to most people.


 @HT Geek

When I'm installing a receptacle on one of my HT walls that would have ib-1 clip + furring channel + 5/8 drywall + GG + 5/8 drywall, should the receptacle be moved out by 2.125 inches or should I have it come out more?


Sent from my iPhone using Tapatalk


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## HT Geek

doveman said:


> So when you say "it's the mass of the whole layer(s) that matters" as far as LFE reduction is concerned, are you're saying that having holes right through the two layers of OSB at various points, whether at the perimeter or in the middle of the floor, will have no detrimental effect on the LFE reduction?


That would depend on a number of factors, such as how many holes, how large, how the floor was constructed overall, etc. Strictly theoretically, if the holes removed no mass from the floor and they were smaller than the smallest LFE wavelength, then yes that would be true.




> Or a solid door with a 1/2" gap at the bottom will block LFE just as well as a door without any gap? That would only seem to make sense if LF sound waves are too "big" to pass through small spaces but maybe that's true.


Correct. In a very simplistic model where there's a door and no other factors, the overall mass of the door is what is going to block LFE. It's an oversimplification, but relative to your question yes, that's true.




> Surely greater mass provides greater reduction of mid and high frequencies as well though doesn't it, in which case having a relatively high mass of two layers of OSB over most of the floor but a much lower mass of only caulk at the perimeter would seem to provide a weak spot through which those frequencies could pass.


Technically, correct. However, that is why you need the caulk there. All frequencies are attenuated further by decoupling. Using mass + decoupling is better than just one or the other. That said, decoupling only produces better results than mass only (and no decoupling). 




> If that's true, then perhaps replacing the insulation at the perimeter, between the wall and the rubber pad, with a piece of OSB (or something else with similar or greater mass), as shown in red in the attached drawing, would help? Whilst this could only be about 28mm high to ensure it only touches the rubber pad and not the OSB layers and thus it won't be the same height/mass as the 36mm of the two OSB layers, perhaps it would be better than just having air or insulation there, whilst still having caulk at the top to allow the wood to expand.


Sure. There's nothing wrong with doing that. Technically, it will add a bit more mass and that will help a bit, but I doubt anyone would ever notice the difference if it were possible to perform an A/B comparison.




> Why do you say that overall my room post-build will be more robust?


It's going to be a tougher built room with more materials. If a tornado were traversing down my street, if my HT room were on the 1st floor I would go there and not the designated shelter room my home was built with (I live in Texas). My HT room has more mass and thicker walls than any other room in my home.




doveman said:


> I thought that the resonant frequency is lowered by increasing the space between the structural wall and the drywall (including by the use of insulation, which acts to make the space larger than it is from a thermodynamic point of view)? I thought mass served some other purpose?


That's true, but mass also affects the resonance. Yes, insulation slows down and dissipates some of the sound waves, by absorbing some of their energy and converting it to heat.




> When you say that sealing the corner seams is a higher priority than plugging gaps in the floor, do you mean sealing the 6mm perimeter gap with caulk is more important than filling the space (or at least the bottom part of it) at the edge under the subfloor with a piece of OSB, as I showed in my last drawing?


Yes




> I'm not sure what you mean by "the slight additional mass from those small gaps" as a gap obviously doesn't have any mass. The water analogy is useful to a certain extent when explaining how sound will escape through any gaps but we need another analogy when talking about differences in mass across the floor and what effect this might have on the soundproofing, as a fishtank keeps the water in regardless of whether one part of the glass is thinner than the rest.


What I was attempting to get across is I would not be too worried about the small gaps you expressed concern over. You could fill them with insulation. Compared to the overall mass of the floor as a whole, I was suggesting it's more important to focus on sealing the 1/4" de-coupling gaps between surfaces (walls/ceiling/floor) versus focusing on an issue (gap) that is likely something you'll have to live with. There are always compromises in building these rooms. It's more important IMHO to focus on the 1/4" perimeter gaps that require caulking as doing so will reduce/prevent flanking. Whether the small gaps under the floor surface are solid or filled with insulation will have a lesser effect on your room's sound proofing, relatively speaking.




> Whilst LFE soundwaves are bigger than higher frequency ones, as they vibrate the air I guess this air can travel through any size gap, whether at the perimeter of the floor or at the bottom of a door. With my two-layer OSB floor, the mass of it should block the LFE but at the perimeter where there is only caulk, I would think the low mass of it would allow some of the LFE (and maybe higher frequencies) to get through. If that wasn't the case, surely we could just use low mass for the entire floor? If the high mass is needed to lower the resonant frequency, wouldn't the perimeter area where there is only low mass caulk still have a higher resonant frequency than the rest of the floor and thus be a weak point?


Technically, yes. However, the point of the caulk is not to block LFE. It is to block flanking noise, which will be higher frequencies. You can get flanking LFE, but that is normally via connected structural components and not airborne. LFE is going to bounce around the room and vibrate your wall/ceiling/floor surfaces. Each of those surfaces will vibrate or 'resonate' and some sound will pass through them. It's unavoidable. Physics. Whether or not you notice the LFE is another matter. Adding more mass, more distance between you and the sound source, etc. weakens the energy of the wave as it travels. And yes, low frequency waves cannot fit through small openings. This is why public safety organizations favor high frequency radios for urban environments and low frequency radios for rural environments. The higher frequencies more easily penetrate into buildings. They also require more energy (power) to travel greater distances. Low frequency radio transmissions will travel very far with less energy, but are poor at penetrating building materials. The higher freqs basically have an easier time penetrating small openings and bouncing around inside a building. What we are referring to as flanking noise for the purpose of this discussion is the same effect. The LFE's won't go through those cracks. They will smack into the surface and resonate it. Thus, at that point the overall mass of the surface begins to play a more prominent role. 

So, my point is the 6mm perimeter caulk will help prevent flanking noises, which will be higher frequencies. The mass in your floor is not going to be impacted to a significant effect by a small portion of a layer or two that is essentially an air gap. That said, if you can fill that air gap with insulation, it will benefit you. Not because it will do anything to the LFE, but because it will also help to prevent flanking, higher frequencies from bouncing around in there and into/out of your room. It ought to have a very minimal positive effect on LFE dampening, but minimal is the keyword there.

Let's backup for a moment. I'm not suggesting you should ignore a gap in your floor layers or plan. I would suggest not using joist tape. I have yet to see a credible lab test that indicates it is useful for our purposes. I doubt it would be harmful, but if it's not useful and costs money and time, why bother? I strongly suggest leaving a 6mm gap between wall/ceiling/floor connections, and caulking that 6mm gap with acoustical caulk. If your floor plan could entail a multi-layer sub-floor, and if some portion of that multi-layer sub-floor will leave empty space in one or more of its layers, I would not be overly concerned with worrying about it. If it's possible to stuff some insulation in such a space, that would be better than having nothing there.

In any room that is not on a concrete slab, it's usually very difficult to isolate the floor. Ideally, you would want to completely de-couple the floor from the structure, and then create a new sub-floor. However, that is beyond the budget, capability, and/or tolerance for most people. In my case for example, my HT room is on the 2nd floor of my home, above my garage. I contemplated removing the original/structural sub-floor and installing rubber U-boats on the flooring joists, then replacing the sub-floor. I chose not to do this due to the level of effort required and the inconvenience. I ascertained the potential gain was not worth the effort. It was a personal decision. What I did do was to perform limited decoupling of the HT room's floor from the original subfloor by installing a 3/8" rubber mat, then 2x layers of 5/8" OSB on top of that, with Green Glue between them. It's not a perfect solution. I can still barely hear/feel the garage door opener activating below. However, that and other vibrations from below are muted relative to how noticeable they were before. Furthermore, after carpet was installed the effect was exacerbated so it is now even less of an issue. At some point in the future, I shall decouple the garage door opener from the ceiling in the garage, which should resolve that particular issue. Finally, I don't care if anyone in the garage is bothered by my HT room blasting sound. That's unlikely to be a problem. 




> I do know that the 25mm plaster on my walls, which has much more mass than caulk, isn't effectively blocking mid to high frequencies from escaping out of the wall.


That is because of:


Everything is coupled together (all surfaces)
Not enough mass
Flanking noise permeates through minute cracks and gaps

I was actually wondering whether replacing the 25mm insulation underneath my subfloor with 18mm OSB would be beneficial? I think the cost would be about the same for each. I would either need to cut holes 8mm deep for the rubber pads (so that they're raised up 10mm above the concrete slab) or if it would be too difficult to get the holes flat, just cut right through and put a 10mm spacer under the pads. Even though 25mm insulation would make the gap larger from a resonant frequency perspective, maybe the mass of 18mm OSB would still be more beneficial? Obviously I couldn't use OSB instead of insulation with the walls or ceiling as it would add too much weight but that probably isn't an issue with the floor.

You could. Depends on what you wish to accomplish. De-coupling + mass is going to provide better results versus mass only. Floors are tough though. That's why I wouldn't spend too much time focusing on the floor. It's likely to be a sore point no matter what you do.


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## HT Geek

bubbrik said:


> When I'm installing a receptacle on one of my HT walls that would have ib-1 clip + furring channel + 5/8 drywall + GG + 5/8 drywall, should the receptacle be moved out by 2.125 inches or should I have it come out more?


There are a few different ways to tackle the problem. One method is to put your walls up and then install remodel junction boxes. Mark your walls during construction, or poke a hole in them and push the Romex through. When your walls are up, cut a hole and insert the junction box. Tighten the screws and the "wings" in the rear of the box will tighten against the wall. In this case, you only need a remodel box capable of being installed into the thickness of the drywall layers. 

Another is to use adjustable gang boxes, like this Carlton branded version:












Using adjustable boxes, the most common installation method is to attach it to a stud. You will need to ensure the box(es) you acquire are able to adjust to the total thickness of your wall (per your calculations above). Carlton calls them, "zip boxes." I'd recommend the Arlington brand over Carlton. The Arlington boxes are more difficult to source, but have a superior design IMO (more robust). Arlington also has both line voltage and low voltage versions (LV pictured below).












Edit: It's preferable to use line voltage boxes for all of your gang box wiring needs. Don't forget to use putty pads on the back of the boxes (helps prevent sound leakage and flanking noise transmission). It's much easier to apply putty pads to the adjustable boxes, since you have complete access to their rear and you're able to verify the pads have been applied correctly.


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## bubbrik

HT Geek said:


> There are a few different ways to tackle the problem. One method is to put your walls up and then install remodel junction boxes. Mark your walls during construction, or poke a hole in them and push the Romex through. When your walls are up, cut a hole and insert the junction box. Tighten the screws and the "wings" in the rear of the box will tighten against the wall. In this case, you only need a remodel box capable of being installed into the thickness of the drywall layers.
> 
> 
> 
> Another is to use adjustable gang boxes, like this Carlton branded version:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Using adjustable boxes, the most common installation method is to attach it to a stud. You will need to ensure the box(es) you acquire are able to adjust to the total thickness of your wall (per your calculations above). Carlton calls them, "zip boxes." I'd recommend the Arlington brand over Carlton. The Arlington boxes are more difficult to source, but have a superior design IMO (more robust). Arlington also has both line voltage and low voltage versions (LV pictured below).




You are just awesome @HT Geek. A very thorough response again. I like the adjustable ones as there is less guessing involved. I'll go hunt for them locally if I can. Thank you!


Sent from my iPhone using Tapatalk


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## HT Geek

bubbrik said:


> I like the adjustable ones as there is less guessing involved. I'll go hunt for them locally if I can. Thank you!


You're welcome. I agree w/you; I prefer the adjustable as well. I've seen the Arlington boxes on Amazon in up to 4-gang sizes. Electrical contractor supply shops should have them. 

Madison Electric may also be a good choice. I haven't used them, but they seem to get good reps and you can purchase them individually on Amazon. You might have to get a box of 10 of the Arlington boxes if you order online.

Oh, and here's what the putty pads I was talking about look like. You can kinda see how to use them in the photo:












They're not cheap though ($65 for 10 on Amazon). If you'd prefer a cheaper alternative, Home Depot and Lowes both sell Duct Seal. It's effectively the same stuff, at a fraction of the cost (~$1.50 or less per pad). 1 pound of duct seal ($3) should cover 2-3 outlets, once you get the hang of it. Tear off a chunk, roll it on a flat surface and flatten it. Those cookie dough making roller things work great if you have one. Voila! Homemade putty pads.


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## jrref

I have a question for the experts.

I live in an attached town home where my living wall is common to my neighbor. A couple of years ago I took down the wall on my side, took out all of the insulation and did the following:
1) Installed 3 inches of Roxul safe and sound in my neighbors wall and another 3 inches in my side of the wall. The wall is staggered 2x4 construction with a 4 inch air gap. The only issue is that the top and bottom plates are common to both sides which is a path for sound transmission, i.e. flanking.
2) Installed 5/8 inch Quiet Rock on my side using Quiet Seal around all of the edges leaving 1/4 inch space around the top and bottom of each sheet which was then sealed.

After all was done, i'm getting about a 50-55 db reduction in sound which I think is pretty good. One thing I notice is that I get slightly less sound transmission from my side to my neighbors and i'm assuming that's because the Quiet Rock is isolating the sound from vibrating the physical structure of the wall.

All this said, here is the problem. My neighbor likes to play his Sonos system a full volume occasionally which I measured at 105 db. Although I have his Speakers on rubber isolation pads, I believe the sheer energy of the sound is vibrating the physical structure of the wall and also i'm getting some flanking due to the common top and bottom wall plates.

My question is, if I were to get my neighbor to install a layer of 5/8 inch Quiet Rock on top of the current 5/8 inch drywall that is there now so not to have to talk the wall down, how much more sound reduction do you think i'll get and do you think it will be enough to make a difference?


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## deewan

HT Geek said:


> They're not cheap though ($65 for 10 on Amazon). If you'd prefer a cheaper alternative, Home Depot and Lowes both sell Duct Seal. It's effectively the same stuff, at a fraction of the cost (~$1.50 or less per pad). 1 pound of duct seal ($3) should cover 2-3 outlets, once you get the hang of it. Tear off a chunk, roll it on a flat surface and flatten it. Those cookie dough making roller things work great if you have one. Voila! Homemade putty pads.


Another option, but not as cheap as the duct seal, are these pads found on Amazon. I am thinking of buying these putty pads since they seem to be much cheaper and already in the square pieces for application.

*ATS Putty Pads*


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## HT Geek

deewan said:


> Another option, but not as cheap as the duct seal, are these pads found on Amazon. I am thinking of buying these putty pads since they seem to be much cheaper and already in the square pieces for application.
> 
> *ATS Putty Pads*


Hmm. Shows $45 to me w/shipping for 10 pads. 

I just noticed Zoro sells the 3M version thru New Egg for $5.71 per pad + $5 total shipping. The 3M's are the gold standard. I've used them and the cheapo HVAC putty, and the 3M are much easier to use. The cheapo stuff is good around edges of outlet boxes though (when your hole is a bit too big).

It's unfortunate the 3M's are so expensive. I paid 1/2 their current price just over a year ago.


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## HT Geek

jrref said:


> I have a question for the experts.
> 
> I live in an attached town home where my living wall is common to my neighbor. A couple of years ago I took down the wall on my side, took out all of the insulation and did the following:
> 1) Installed 3 inches of Roxul safe and sound in my neighbors wall and another 3 inches in my side of the wall. The wall is staggered 2x4 construction with a 4 inch air gap. The only issue is that the top and bottom plates are common to both sides which is a path for sound transmission, i.e. flanking.


Wow. I'm really surprised there is not a more robust fire stop between your units, such as concrete block. I've found that to be common on TH's built in the 70's and 80's. This essentially isolates most fire spreads to the roof and in some cases exterior wall veneer. The homes I mentioned that I've examined were brick. What year was your home built?




> One thing I notice is that I get slightly less sound transmission from my side to my neighbors and i'm assuming that's because the Quiet Rock is isolating the sound from vibrating the physical structure of the wall.


Yes. You're getting more absorption before it hits the connected structure and can flank, etc.




> All this said, here is the problem. My neighbor likes to play his Sonos system a full volume occasionally which I measured at 105 db. Although I have his Speakers on rubber isolation pads, I believe the sheer energy of the sound is vibrating the physical structure of the wall and also i'm getting some flanking due to the common top and bottom wall plates.
> 
> My question is, if I were to get my neighbor to install a layer of 5/8 inch Quiet Rock on top of the current 5/8 inch drywall that is there now so not to have to talk the wall down, how much more sound reduction do you think i'll get and do you think it will be enough to make a difference?


It will help, but not by much. Based on comparative lab tests, you will gain 3 STC. OTOH, your current config should have given you about +4 STC compared to what you started with, so even only +3 STC is likely something you'll notice.

If you want better isolation, you'll have to do some decoupling, such as clips & channel on at least one side. No way around it.


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## jrref

HT Geek said:


> Wow. I'm really surprised there is not a more robust fire stop between your units, such as concrete block. I've found that to be common on TH's built in the 70's and 80's. This essentially isolates most fire spreads to the roof and in some cases exterior wall veneer. The homes I mentioned that I've examined were brick. What year was your home built?
> 
> 
> 
> 
> Yes. You're getting more absorption before it hits the connected structure and can flank, etc.
> 
> 
> 
> 
> It will help, but not by much. Based on comparative lab tests, you will gain 3 STC. OTOH, your current config should have given you about +4 STC compared to what you started with, so even only +3 STC is likely something you'll notice.
> 
> If you want better isolation, you'll have to do some decoupling, such as clips & channel on at least one side. No way around it.


The unit was built in 1995. Yea so I agree on the fire rating but I guess they believe that the 5/8 inch sheetrock is sufficient as a fire stop.


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## RyanDHT

I have a question that I have looked and cannot seem to find an answer to. I live in Illinois where it is required to run ridged/EMT conduit for basically all electrical runs. Currently I am renovating my basement and using IB-3's on all of the walls and IB-1's on the ceiling to decouple the walls and ceiling. I have EMT that runs throughout the basement walls, and also from the breaker to a couple spots on the framed walls through the joists cavities above to provide electricity to my theater room.

Should I be concerned about the conduit (specifically the hangers that fix the conduit to the joists above the ceiling) when trying to soundproof my basement? Maybe I am just being anal but it seems like the hangers would serve to re-couple the walls with the joists, or even the EMT could transmit the sound that would be able to come out the electrical outlets boxes? Are there specific hangers that would help with this?


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## HT Geek

RyanDHT said:


> I have a question that I have looked and cannot seem to find an answer to. I live in Illinois where it is required to run ridged/EMT conduit for basically all electrical runs.


Do you know why? Is that because you are required to protect all wiring from physical damage? Is it an issue of grounding the conduit? Is EMT specifically called for?




> Should I be concerned about the conduit (specifically the hangers that fix the conduit to the joists above the ceiling) when trying to soundproof my basement? Maybe I am just being anal but it seems like the hangers would serve to re-couple the walls with the joists, or even the EMT could transmit the sound that would be able to come out the electrical outlets boxes?
> 
> Yes. You're concern is justified. Sounds like you can't do much about it though. I'm thinking the more bends you have, the less flanking noise you'll get going from inside the junction boxes through the conduit. You could possibly apply foam insulation around the pipes - sort of like plumbing insulation - however, your building inspector might not think highly of that idea. Plus it would not stop sound bouncing around inside the conduit.
> 
> Either way, it's likely to be a minor issue compared with other stuff you'll be focusing on sound proofing. Using the clips will make a big (positive) difference overall.
> 
> 
> 
> 
> 
> Are there specific hangers that would help with this?
> 
> 
> 
> Yes. There are hangers with neoprene or rubber padding. Of course, they must still be attached to the studs.
> 
> I ran into a similar challenge when running conduit in my soffits. I wanted to ensure they wouldn't vibrate too much. I tried plastic clamps, but a few broke during installation, so I switched to metal. I used Duct Seal and Putty Pads to line the inside of the metal clamps. Then I squished the conduit into the putty, and attached the clamps to the soffits' studs. If you go this route, my suggestion is you purchase clamps for 1 size larger than your conduit diameter. That will allow room for the putty without compressing it to the point it's too thin to be effective.
Click to expand...


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## RyanDHT

HT Geek said:


> Do you know why? Is that because you are required to protect all wiring from physical damage? Is it an issue of grounding the conduit? Is EMT specifically called for?
> 
> 
> 
> 
> 
> Should I be concerned about the conduit (specifically the hangers that fix the conduit to the joists above the ceiling) when trying to soundproof my basement? Maybe I am just being anal but it seems like the hangers would serve to re-couple the walls with the joists, or even the EMT could transmit the sound that would be able to come out the electrical outlets boxes?
> 
> Yes. You're concern is justified. Sounds like you can't do much about it though. I'm thinking the more bends you have, the less flanking noise you'll get going from inside the junction boxes through the conduit. You could possibly apply foam insulation around the pipes - sort of like plumbing insulation - however, your building inspector might not think highly of that idea. Plus it would not stop sound bouncing around inside the conduit.
> 
> Either way, it's likely to be a minor issue compared with other stuff you'll be focusing on sound proofing. Using the clips will make a big (positive) difference overall.
> 
> 
> 
> 
> Yes. There are hangers with neoprene or rubber padding. Of course, they must still be attached to the studs.
> 
> I ran into a similar challenge when running conduit in my soffits. I wanted to ensure they wouldn't vibrate too much. I tried plastic clamps, but a few broke during installation, so I switched to metal. I used Duct Seal and Putty Pads to line the inside of the metal clamps. Then I squished the conduit into the putty, and attached the clamps to the soffits' studs. If you go this route, my suggestion is you purchase clamps for 1 size larger than your conduit diameter. That will allow room for the putty without compressing it to the point it's too thin to be effective.
> 
> 
> Many people around Chicagoland(Myself included) believe it’s mostly a ploy to keep the Electrical Unions in business, because it is much harder to do and learn to bend conduit then it is to run things like Romex. The official reason that I have heard, and I am sure there are more than one is that “there are many studies that show that electrical fires are drastically reduced in walls run with EMT instead of things like Romex”. I have no doubt that there are benefits to using EMT over Romex, but that does not make it any more annoying, and even the use of things like armored flex cable is severely limited.
> 
> Anyway, thanks for your post. I am glad I wasn’t completely off track. It’s funny I had come up with a solution last night that is basically the exact same thing as yours, but instead of the putty I was using weatherstripping to line the inside of the clamp. I have an extra trip to HD last night to prove that you need at least a size larger clamp. I will see if I can grab some pics tonight.
> 
> I am thinking that if I can decouple the conduit from all of the things that are not my decoupled walls, and if I can get rid of any potential rattling of the conduit that runs through the stud walls then I have done the best I can do. I am not sure if I can do anything about the transfer of sound if/when it gets into the conduit. I guess I could make sure there are at least 1 to 2 bends in each conduit run which is already about 95% of the case.
> 
> I don't think I can get away with wrapping all of the conduit with insulation, but if I did would that help to reduce sound transmission into the conduit?
> 
> Thanks again
Click to expand...


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## HT Geek

RyanDHT said:


> Many people around Chicagoland(Myself included) believe it’s mostly a ploy to keep the Electrical Unions in business, because it is much harder to do and learn to bend conduit then it is to run things like Romex. The official reason that I have heard, and I am sure there are more than one is that “there are many studies that show that electrical fires are drastically reduced in walls run with EMT instead of things like Romex”. I have no doubt that there are benefits to using EMT over Romex, but that does not make it any more annoying, and even the use of things like armored flex cable is severely limited.


I'd bet my money you're right. If it's such a great idea then why doesn't the NEC require it??? Perhaps some politician with no subject-matter knowledge noticed commercial building regulations are tighter than residential and decided residential construction ought to meet the same standards. That is a slippery slope. You can't have housing affordability and have a house built like Fort Knox with concrete walls, thick windows, metal studs, etc. etc. 

The purveyors of misinformation may be quoting studies that demonstrate fire spread and smoke development statistics versus NM-B. Well, if the wall is already on fire then yeah, that's probably true since the metal conduit won't burn. However, at that point it won't matter. I bet if you asked someone in-the-know on the statute they could not cite a single study supporting their claim that is worth the paper it's printed on AND which relates to Class I or II dwellings. Commercial building codes have to apply to a much wider set of possible scenarios, and a much wider variety of use cases, environments, and locations. It's comparing apples and yogurt.

I feel bad for you living in a Nanny State (Illinois, and especially Chicago). Illinois, California, and Puerto Rico are examples of what happens when there's too much government nanny-ism across many sectors.... bankruptcy, poor infrastructure, ever rising taxes, etc. are the end result. I'm sure the $ is being siphoned off somewhere - just not to the benefit of the majority of its citizens. Ah, the agony of incompetence; but I digress.... 




> Anyway, thanks for your post. I am glad I wasn’t completely off track. It’s funny I had come up with a solution last night that is basically the exact same thing as yours, but instead of the putty I was using weatherstripping to line the inside of the clamp. I have an extra trip to HD last night to prove that you need at least a size larger clamp. I will see if I can grab some pics tonight.


Yeah, the larger size clamp ensures you won't short-circuit the concept. I believe the duct seal is probably cheaper and perhaps easier to use. If you haven't seen it, HD and Lowes both sell Gardner Bender Duct Seal Compound for ~$3 or so per pound. You should only need 1 or 2 lbs. of it unless you have a lot of clamps. There's probably a regulation somewhere that defines how many feet your conduit can travel without support. I'd use the minimum number of clamps. If there is no specification, every 4' and support at bends should be a good ballpark.




> I am thinking that if I can decouple the conduit from all of the things that are not my decoupled walls, and if I can get rid of any potential rattling of the conduit that runs through the stud walls then I have done the best I can do. I am not sure if I can do anything about the transfer of sound if/when it gets into the conduit. I guess I could make sure there are at least 1 to 2 bends in each conduit run which is already about 95% of the case.


Yep. Sounds like a good plan. The more bends you have, the less likely sound will get from one end to the other. More bends = better. OTOH, more bends = more P.I.T.A. for you. I presume you're aware you can buy a tool that bends the EMT? It's actually very easy to use. The challenge is bending in the correct location. Cutting the conduit is also a pain. Any chance you could use BX (armored cable) instead (maybe inside PVC Schedule 40 conduit if you have to)? The 14-gauge version can easily be cut with a large side cutter.




> I don't think I can get away with wrapping all of the conduit with insulation, but if I did would that help to reduce sound transmission into the conduit?


Yeah. If they are unreasonable enough to make you use EMT in the first place, I'm sure they'd find a reason to freak over the insulation around it.

Theoretically, it ought to help a bit. But realistically, it's probably unnecessary. The more I think about it, I would skip it. If there is any flanking noise it's going to primarily travel through the conduit from end-to-end, not through the walls of the conduit (except perhaps LFE in the form of vibration... but I wouldn't worry about that since you will be using the putty).


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## Mpoes12

I'm in Illinois and had similar concerns. I plugged the ends of the conduit with leftover pieces of the putty pad on both sides. I did it after the electrical was done and passed inspection. The inspector noticed it later and isn't care. I also had putty pads around the boxes and conduit clamp. Two of my theater walls are accessible through a crawl space and so I was able to test and there was no evidence of sound leaking through the conduit. I also put a mic in my electrical box to test and picked up less noise than I was when I measured in that room. In other words more sound was leaking through my soundproof walls than through the conduit. 

When I did my outlets I ran double gang boxes and then used box extended plates that converted them to single gang. I put putty pads around the entire structure and the decoupled drywall layer against a layer of neoprene sitting in the putty pad. I then caulked the boxes against he drywall. When I shared this with a soundproofing expert he felt it was probably silly overkill and likely added no meaningful stc points to the structure. 

To date the biggest sound leak in my entire room is the communicating doors. I have solid core doors on both, double gaskets, a very solid and massive door frame. My best guess is that the gaskets aren't tight enough and I may have created a flanking path with the way the door frame was built. The inner trim in a single piece of 12" wide poplar which does tie the two doors together. In any case I wouldn't worry too much about the conduit. It's very likely to be a minor flanking path as compared to sound leaks like hvac and doors. 


Sent from my iPhone using Tapatalk


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## RyanDHT

Mpoes12 said:


> I'm in Illinois and had similar concerns. I plugged the ends of the conduit with leftover pieces of the putty pad on both sides. I did it after the electrical was done and passed inspection. The inspector noticed it later and isn't care. I also had putty pads around the boxes and conduit clamp. Two of my theater walls are accessible through a crawl space and so I was able to test and there was no evidence of sound leaking through the conduit. I also put a mic in my electrical box to test and picked up less noise than I was when I measured in that room. In other words more sound was leaking through my soundproof walls than through the conduit.
> 
> When I did my outlets I ran double gang boxes and then used box extended plates that converted them to single gang. I put putty pads around the entire structure and the decoupled drywall layer against a layer of neoprene sitting in the putty pad. I then caulked the boxes against he drywall. When I shared this with a soundproofing expert he felt it was probably silly overkill and likely added no meaningful stc points to the structure.
> 
> To date the biggest sound leak in my entire room is the communicating doors. I have solid core doors on both, double gaskets, a very solid and massive door frame. My best guess is that the gaskets aren't tight enough and I may have created a flanking path with the way the door frame was built. The inner trim in a single piece of 12" wide poplar which does tie the two doors together. In any case I wouldn't worry too much about the conduit. It's very likely to be a minor flanking path as compared to sound leaks like hvac and doors.
> 
> 
> Sent from my iPhone using Tapatalk


Thanks for the recommendation on the putty pads HT geek, it works way better than the weather stripping I had tried. Mpoes I am glad to hear your success story as I had planned on doing the putty around the junction boxes and caulking the plate to the wall as well, but I was starting to feel as though I was doing all this work and it would be for nothing, or that I was being too concerned about little things. I will probably end up overkilling this thing like you did, but it is good to hear that it will work, or at least be overkill.


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## Mpoes12

Also don't forget that steel has a fairly high stc rating at low thicknesses and is fairly dense. The argument against metal in soundproofing comes from the significant resonance related ringing. A steel plate wall composed of two 5/8" layers adhered with a viscoelastic adhesive would probably have a very high stc rating. I'd guess much higher than drywall. It's problem would be having a viscoelastic material to dampen its serious resonance problem. At and around the resonance the sound is reradiated at roughly the same level as if nothing was stopping it. 

I say this because there is a lot of anti-steel in soundproofing around here, but it's actually good at sound blocking. For example 30 gauge steel hvac ducting has an stc rating in the mid to upper 20's when lightly damped. I used a double walled material that used 24 gauge steel for the outer layer and 28 for the inner layer (with 18 ppi perforations) and fiberglass. Mine was damped with a spray damping compound inside and out and he engineering sheet they sent me suggested stc in the high 40's. Tests I did on the damped expansion box I had built from 18 gauge steel showed transmission loss in the mid frequencies in excess of 50db. I couldn't really give it an stc rating, but I'm sure it would be high. 


Sent from my iPhone using Tapatalk


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## GatorBlues

I have a question about my columns, which will double as giant speaker boxes for my Volt side surrounds. As many of you know, I have built a room within a room. There is an inch or two gap between the studs that support the rest of the house and the separate 2x4 studs that frame the interior of the theater room. I'd like to minimize the depth of the columns to preserve space in the room, but of course, the columns must have a certain depth to accommodate the speakers. Thus, I was contemplating building the columns in between the interior room's 2x4 studs. I would put the back of the columns flush with the back of the 2x4 studs (mdf at the back of the column, then a layer of drywall, with green glue between the layers). Then, the column would only stick out 4 or 5 inches into the room instead of 8 or 9 inches. If I do this, the columns will be secured to the interior studs, will have a double layer of mass (MDF, GG, Drywall), and will not touch the other row of studs that support the rest of the house. This would essentially be a giant speaker box flush with the outside edge of the interior studs that constitute the walls of the theater room. I do not believe this would create a triple layer effect or other adverse effect on soundproofing. Does this make sense? 

I might even just build recessed speaker boxes and then build the rest of the columns around them, but the question would be the same, only on a slightly smaller scale -- The back of the speaker box would be recessed so that it is flush with the back of the interior studs, leaving only a one inch gap between the back of the speaker box and the separate studs that support the house. Is this OK? 

And one more thing -- Given that this is a room within a room, I'm operating under the belief that I can attach the speaker boxes (side, rear and atmos) directly to the studs. In other words, I don't need RSIC clips to attach the boxes to the studs in the hopes of decoupling the speaker boxes from studs that are already decoupled from the rest of the house. Correct? 

I'm not sure I explained this very well. Let me know if I should draw some pictures before you can advise me. Thanks in advance for your help.


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## HT Geek

GatorBlues said:


> I have a question about my columns, which will double as giant speaker boxes for my Volt side surrounds. As many of you know, I have built a room within a room. There is an inch or two gap between the studs that support the rest of the house and the separate 2x4 studs that frame the interior of the theater room. I'd like to minimize the depth of the columns to preserve space in the room, but of course, the columns must have a certain depth to accommodate the speakers. Thus, I was contemplating building the columns in between the interior room's 2x4 studs. I would put the back of the columns flush with the back of the 2x4 studs (mdf at the back of the column, then a layer of drywall, with green glue between the layers). Then, the column would only stick out 4 or 5 inches into the room instead of 8 or 9 inches. If I do this, the columns will be secured to the interior studs, will have a double layer of mass (MDF, GG, Drywall), and will not touch the other row of studs that support the rest of the house. This would essentially be a giant speaker box flush with the outside edge of the interior studs that constitute the walls of the theater room. I do not believe this would create a triple layer effect or other adverse effect on soundproofing. Does this make sense?
> 
> I might even just build recessed speaker boxes and then build the rest of the columns around them, but the question would be the same, only on a slightly smaller scale -- The back of the speaker box would be recessed so that it is flush with the back of the interior studs, leaving only a one inch gap between the back of the speaker box and the separate studs that support the house. Is this OK?


Two factors to consider here. First, your speaker boxes will resonate with the inner wall (more or less). Second, you'll create more opportunities for noise to penetrate via joints. I suppose there's also a third factor where the mass of the wall where your speaker boxes are may be different from the surrounding wall. Overall, I don't think it's a really big deal. Sure, a purist will say don't do it because you are poking holes in the shell (effectively), but as you pointed out it's still decoupled. The worst part of your plan may be the part about coupling your columns to the studs on either side of them. However, I don't think it's a really big deal. Technically, you'd be better off with the column completely inside the shell, but I'm sure you know that. It's a trade-off between performance and space/column thickness. 




> And one more thing -- Given that this is a room within a room, I'm operating under the belief that I can attach the speaker boxes (side, rear and atmos) directly to the studs. In other words, I don't need RSIC clips to attach the boxes to the studs in the hopes of decoupling the speaker boxes from studs that are already decoupled from the rest of the house. Correct?


With a double stud wall configuration, correct.


----------



## doveman

HT Geek said:


> That would depend on a number of factors, such as how many holes, how large, how the floor was constructed overall, etc. Strictly theoretically, if the holes removed no mass from the floor and they were smaller than the smallest LFE wavelength, then yes that would be true.
> 
> Correct. In a very simplistic model where there's a door and no other factors, the overall mass of the door is what is going to block LFE. It's an oversimplification, but relative to your question yes, that's true.





> Technically, yes. However, the point of the caulk is not to block LFE. It is to block flanking noise, which will be higher frequencies. You can get flanking LFE, but that is normally via connected structural components and not airborne. LFE is going to bounce around the room and vibrate your wall/ceiling/floor surfaces. Each of those surfaces will vibrate or 'resonate' and some sound will pass through them. It's unavoidable. Physics. Whether or not you notice the LFE is another matter. Adding more mass, more distance between you and the sound source, etc. weakens the energy of the wave as it travels. And yes, low frequency waves cannot fit through small openings. This is why public safety organizations favor high frequency radios for urban environments and low frequency radios for rural environments. The higher frequencies more easily penetrate into buildings. They also require more energy (power) to travel greater distances. Low frequency radio transmissions will travel very far with less energy, but are poor at penetrating building materials. The higher freqs basically have an easier time penetrating small openings and bouncing around inside a building. What we are referring to as flanking noise for the purpose of this discussion is the same effect. The LFE's won't go through those cracks. They will smack into the surface and resonate it. Thus, at that point the overall mass of the surface begins to play a more prominent role.
> 
> So, my point is the 6mm perimeter caulk will help prevent flanking noises, which will be higher frequencies. The mass in your floor is not going to be impacted to a significant effect by a small portion of a layer or two that is essentially an air gap. That said, if you can fill that air gap with insulation, it will benefit you. Not because it will do anything to the LFE, but because it will also help to prevent flanking, higher frequencies from bouncing around in there and into/out of your room. It ought to have a very minimal positive effect on LFE dampening, but minimal is the keyword there.


OK, I can see that the 6mm perimeter gap isn't going to have much, if any, detrimental effect on the LFE reduction afforded by the mass of two layers of 18mm OSB.



> Technically, correct. However, that is why you need the caulk there. All frequencies are attenuated further by decoupling. Using mass + decoupling is better than just one or the other. That said, decoupling only produces better results than mass only (and no decoupling).


I'm afraid I don't understand this reply in the context of my question which was "Surely greater mass provides greater reduction of mid and high frequencies as well though doesn't it, in which case having a relatively high mass of two layers of OSB over most of the floor but a much lower mass of only caulk at the perimeter would seem to provide a weak spot through which those frequencies could pass."

You seem to have said "Yes, the lower mass of caulk will create a weak spot at the perimeter gap through which mid and high frequencies could pass, but that is why you need caulk there".



> Let's backup for a moment. I'm not suggesting you should ignore a gap in your floor layers or plan. I would suggest not using joist tape. I have yet to see a credible lab test that indicates it is useful for our purposes. I doubt it would be harmful, but if it's not useful and costs money and time, why bother? I strongly suggest leaving a 6mm gap between wall/ceiling/floor connections, and caulking that 6mm gap with acoustical caulk. If your floor plan could entail a multi-layer sub-floor, and if some portion of that multi-layer sub-floor will leave empty space in one or more of its layers, I would not be overly concerned with worrying about it. If it's possible to stuff some insulation in such a space, that would be better than having nothing there.


I'm not really arguing that joist tape is better than caulk. Clearly there has to be a gap (even if it wouldn't create flanking issues by having the floor touching the wall, it would be impossible to get the OSB to meet the wall perfectly with no gaps) and we have to fill it with something (otherwise mid->high frequencies would have nothing blocking them at the perimeter) and maybe caulk is the best option to maximise decoupling but it still seems that this caulk-filled area is going to be a weak spot for escape of mid->high frequencies compared to the much higher mass of the OSB. Maybe I'm overestimating how much mass is needed to block those frequencies and if it was practical we could just cover a wall with a layer of caulk and it would block those frequencies just as well (in practical/audible terms, measurable but inaudible differences aren't important) as the much greater mass of two layers of acoustic drywall but I find that hard to believe.

Having said that, there doesn't seem to be any better option and it seems to be standard practice to have a caulk-filled perimeter gap in soundproofed rooms, so I should probably just try and ignore my nagging doubts and go with it, even if I don't understand it!



> In any room that is not on a concrete slab, it's usually very difficult to isolate the floor. Ideally, you would want to completely de-couple the floor from the structure, and then create a new sub-floor. However, that is beyond the budget, capability, and/or tolerance for most people. In my case for example, my HT room is on the 2nd floor of my home, above my garage. I contemplated removing the original/structural sub-floor and installing rubber U-boats on the flooring joists, then replacing the sub-floor. I chose not to do this due to the level of effort required and the inconvenience. I ascertained the potential gain was not worth the effort. It was a personal decision. What I did do was to perform limited decoupling of the HT room's floor from the original subfloor by installing a 3/8" rubber mat, then 2x layers of 5/8" OSB on top of that, with Green Glue between them. It's not a perfect solution. I can still barely hear/feel the garage door opener activating below. However, that and other vibrations from below are muted relative to how noticeable they were before. Furthermore, after carpet was installed the effect was exacerbated so it is now even less of an issue. At some point in the future, I shall decouple the garage door opener from the ceiling in the garage, which should resolve that particular issue. Finally, I don't care if anyone in the garage is bothered by my HT room blasting sound. That's unlikely to be a problem.


I'm fortunate at least that I will be building my sub-floor on a concrete slab. I can't really tell how much airborne noise is leaking via the floor at the moment but I'm certain that some of the vibration/impact noise from things like water pumps in the neighbouring flats, cars parking outside, etc. will be radiating from the walls into the concrete slab, so I'm hoping that building my sub-floor on the rubber isolater pads will significantly reduce how much those noises can penetrate my room via the floor and then hopefully the clips+channel+drywall on the walls and ceiling will do the same for those parts of the room.



> It's going to be a tougher built room with more materials. If a tornado were traversing down my street, if my HT room were on the 1st floor I would go there and not the designated shelter room my home was built with (I live in Texas). My HT room has more mass and thicker walls than any other room in my home.


Then again my room's going to have two layers of heavy acoustic drywall screwed into hat channel, which in turn is attached to clips which are screwed through the plaster on the wall and into the cinderblock or brick underneath. I would think that there's more risk of the screws working loose and the drywall falling down on top of me if a tornado hits the building (not that we have tornados here) then there would be of the plaster coming off the wall and even if it did, it would probably come off in small pieces as opposed to an entire sheet or two of drywall falling on me.



> That is because of:
> 
> 
> Everything is coupled together (all surfaces)
> Not enough mass
> Flanking noise permeates through minute cracks and gaps


Sure the 25mm plaster layer on my walls is coupled to the cinderblock/brick, whereas there will be a large airgap (maybe partially filled with insulation) between my concrete slab and the caulk but the caulk will still be directly coupled to the walls and the top layer of OSB. So if the higher mass of 25mm plaster isn't sufficient to block mid->high frequencies leaking out of the wall, then surely they will find it even easier to travel through the caulk? I take your point about the plaster having lots of minute cracks though, which won't be the case with the caulk.


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## HT Geek

doveman said:


> I'm afraid I don't understand this reply in the context of my question which was "Surely greater mass provides greater reduction of mid and high frequencies as well though doesn't it, in which case having a relatively high mass of two layers of OSB over most of the floor but a much lower mass of only caulk at the perimeter would seem to provide a weak spot through which those frequencies could pass."
> 
> You seem to have said "Yes, the lower mass of caulk will create a weak spot at the perimeter gap through which mid and high frequencies could pass, but that is why you need caulk there".


Short answer is, yes - you're right (about more mass being better). The point I apparently didn't get across too well is I don't believe a small area of the floor lacking an additional layer (mass) of solid material will significantly affect your outcome. I was attempting to suggest focusing your attention and efforts on other areas of your room and not worrying about that too much, particularly since I got the impression your choices are limited. I'm sure you could come up with a way to fill the area, but my suggestion is the minimal gain is probably not worth the effort required to do so.

So, bottom line - yes, you're right a bit more mass in the gap area would help with sound absorption. However, I don't personally believe it's worth the effort given your circumstances. Purely a personal opinion though.


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## bubbrik

HT Geek said:


> Check
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Ordinarily, no need. If you have a *specific* need to do so, then I would consider it (e.g. grandma sleeping in room next door during movie). Otherwise, there's normally insufficient benefit to warrant the extra work and materials.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You could, but again if there's not a need then I wouldn't. That's a lot of space, and a lot of cost as you've pointed out (to fill it with Roxul). It would be useful to throw some pink fluffy (fiberglass batts) up there, but you have an unusually deep space (2 feet). You could spend a lot of $ on pink fluffy (or Roxul). Insulation acts as a velocity absorber, and slows down the speed and energy of sound waves. It causes small air cavities to act like larger air cavities. With a 2' gap to begin with, compared to most people's builds, you have less of a need to add insulation there. If you want to reduce LFE transmission, it's a different ballgame and you'd need to add mass in there (e.g. insulation + drywall cut to fit in between the joists).
> 
> 
> 
> Based on the photos you posted, I would suggest focusing your concern on items with greater potential for noise relative to your HT. Namely, the metal HVAC ducts and PVC pipes. I say this for two reasons: 1) if you don't isolate those issues, then from the HT room's perspective it won't matter if you have 2' of Roxul everywhere else - sounds will permeate; and 2) on the off-chance that sound gets through your clips + DD ceiling, those are likely to be the culprits.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Are you planning for any canned (recessed) lighting? If so, you should build backer boxes for them.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You're on the right path there ^.
> 
> 
> 
> Yes, the surface mount auto door bottoms are easier to install. They're also slightly less effective than the semi-mortised or fully mortised version. However, just like the joist air gap, it quickly gets to the point of splitting hairs when one looks at the big picture and the overall soundproofing strategy. Translation: I would not be concerned; an auto door bottom is better than no door bottom.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Do you mean this? In principle, yes. However, save yourself some $ and look at Linacoustic or Industrial Noise Duct Liner, K-Flex Duct Liner, or similar products. The 1/2" or 1" version should be sufficient. Check Zoro Tools, NewEgg, Walmart, Jet.com, and Amazon.
> 
> 
> 
> 
> 
> 
> 
> If it's flex duct and the ducts do not originate or terminate in the HT room then it's a non-issue. If they're rigid metal ducts (as you showed in photograph), there's some potential noise from airflow and the metal creaking as the temperature changes (predominantly when the heat is on). Use Linacoustic or similar material described above (it's made for this purpose).
> 
> 
> 
> Linacoustic is normally installed on the inside of ducts to quiet the airflow. However, you can also install it on the exterior and it will reduce sound transmission. Or you could just rely on the clips and channel, DD, etc. It's quite frankly likely to be a non-issue. In some homes, noise from the PVC pipes is more likely to be an issue.
> 
> 
> 
> So, to re-cap....
> 
> 
> 
> Clips + channel, DD, GG are all good. They alone should isolate your from from the vast majority of noise.
> 
> 
> 
> For added peace-of-mind (it would suck to rip out walls and add this retroactively if you later decide there is a need) you could add Linacoustic or similar material on the ductwork, and foam or Linacoustic around the PVC pipes. Don't break the bank on this. It's not worth it. Selective dampening may be worthwhile.
> 
> 
> 
> You could then add insulation in the joist cavity above the room if you'd like. Pink fluffy fiberglass works nearly as well as Roxul for significantly less $. However, unless you have a known noise issue above, with your 2' gap I would not be overly concerned with it. If the budget is tight, I would spend $ elsewhere.
> 
> 
> 
> And finally, I almost forgot to ask but I presume your ceiling will also be de-coupled with clips just like the walls (?).
> 
> 
> 
> I attempt to be practical with advice on soundproofing. Most people are cost conscious and/or don't have needs to go to extreme lengths. If you follow my suggestions above, you're unlikely to get 100% sound isolation, but you will get 90%. If you are good with that then save your $. Your cost to insulate the pipes should be minimal. To get your room to the 95%ile, you're looking at 2x-3x your outlay compared to a 90% solution. As I said, IMHO it's just not worth the investment to most people.



@HT Geek
Hope your project has been moving on well. I haven't seen an update for a few days.

With respect to linacoustic, a local distributor quoted $275 for a roll of 1" 47x100 and $220 for the 1/2" version. Is that reasonable? Would 1" be the right thickness for use to treat ducks and pipes in the ceiling?

Is this the same material I would use on the wall behind the AT screen for sound treatment? Asking only so I don't buy too much of the material when not needed.

Thanks again!


Sent from my iPhone using Tapatalk


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## HT Geek

doveman said:


> Having said that, there doesn't seem to be any better option and it seems to be standard practice to have a caulk-filled perimeter gap in soundproofed rooms, so I should probably just try and ignore my nagging doubts and go with it, even if I don't understand it!


Think of cracking open a window in a city apartment. Listen to the sounds. Now shut the window and listen. That's the effect you'll get from the caulk. Now if you build a concrete wall on the inside of your window - but not touching it - of course it would block even more. But if you open the window again and there are gaps around that concrete wall, more sound will find its way into your listening area again. So, the combination of the mass of the concrete and the caulk work better than one or the other alone.

Mass will do more blocking than the caulk. However, without the caulk (sealing gaps), it won't work as well. It's the higher frequency noises with shorter wavelengths that will sneak around and through the gaps. 




> I'm fortunate at least that I will be building my sub-floor on a concrete slab. I can't really tell how much airborne noise is leaking via the floor at the moment but I'm certain that some of the vibration/impact noise from things like water pumps in the neighbouring flats, cars parking outside, etc. will be radiating from the walls into the concrete slab, so I'm hoping that building my sub-floor on the rubber isolater pads will significantly reduce how much those noises can penetrate my room via the floor and then hopefully the clips+channel+drywall on the walls and ceiling will do the same for those parts of the room.


Yes, they'll help for sure because you will be adding decoupling. The more complete the isolation, the more effective.




> Sure the 25mm plaster layer on my walls is coupled to the cinderblock/brick, whereas there will be a large airgap (maybe partially filled with insulation) between my concrete slab and the caulk but the caulk will still be directly coupled to the walls and the top layer of OSB. So if the higher mass of 25mm plaster isn't sufficient to block mid->high frequencies leaking out of the wall, then surely they will find it even easier to travel through the caulk? I take your point about the plaster having lots of minute cracks though, which won't be the case with the caulk.


Higher mass essentially lowers the resonance of the surface. Frequencies above the resonance point will get blocked/absorbed more than those below it. That's why mass is so good for sound proofing, at least up to the resonance point. Then decoupling and other factors kick in to improve the results. Insulation slows down the velocity of sound waves and converts the energy to heat. AFAIK, the insulation does not affect the sound freqs but effectively reduces its intensity. The effect is more pronounced on higher frequency sound waves, as they require more energy to travel (therefore removing some of that energy reduces their effective travel distance).

If you are familiar with RF energy, it's very similar. Low freq RF signals travel further with less energy, and vice-versa. That is why cell phones have crap range and we need towers all over the place to act as repeaters. Meanwhile, military submarines use extremely low frequency radios because they can literally bounce the signal from one side of the planet to the other and through the oceans.


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## HT Geek

bubbrik said:


> @HT Geek
> Hope your project has been moving on well. I haven't seen an update for a few days.


Yes, my bad! I have a bunch of photos I need to upload and notate. Just been very busy. The room is now almost done. A/V rack, PJ, and equipment setup are all that's left.




> With respect to linacoustic, a local distributor quoted $275 for a roll of 1" 47x100 and $220 for the 1/2" version. Is that reasonable? Would 1" be the right thickness for use to treat ducks and pipes in the ceiling?
> 
> Is this the same material I would use on the wall behind the AT screen for sound treatment? Asking only so I don't buy too much of the material when not needed


1/2" not worthwhile. Get the 1". It's useful in a variety of places, such as strategically placed on the side and rear walls. 100' roll won't last you as long as you might think.

btw, I'm thinking that's 100 square feet (25' x 4'), not 100' x 4' roll. Price sounds average for that size (100 sf).

Edit: ^^ Just thinking you might as well get a 1" thick roll since you can use it other places besides your pipes. The pipes won't need much thickness. I wouldn't use anything thinner than 1" on the walls or behind front screen. Use thicker if you can (walls), where it's needed.


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## GatorBlues

HT Geek said:


> Two factors to consider here. First, your speaker boxes will resonate with the inner wall (more or less).


Should I reconsider and use RSIC clips after all to hang the speaker boxes to avoid this?


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## HT Geek

GatorBlues said:


> Should I reconsider and use RSIC clips after all to hang the speaker boxes to avoid this?


No, I don't believe that's necessary. One factor in your favor is under your current plan, the speaker boxes will not be connected to your outer (structural) stud wall at all. So, that's good. I think you just need to be sure and caulk any gaps well and put a double layer of OSB/Plywood/Drywall with GG comprising the rear of the backer boxes.

Overall, I don't think it's a big deal since you're not connecting them to the structural/outer stud wall.


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## GatorBlues

doveman said:


> I'm fortunate at least that I will be building my sub-floor on a concrete slab. I can't really tell how much airborne noise is leaking via the floor at the moment but I'm certain that some of the vibration/impact noise from things like water pumps in the neighbouring flats, cars parking outside, etc. will be radiating from the walls into the concrete slab, so I'm hoping that building my sub-floor on the rubber isolater pads will significantly reduce how much those noises can penetrate my room via the floor and then hopefully the clips+channel+drywall on the walls and ceiling will do the same for those parts of the room.


So am I. I'm putting down a rubber layer, then some 1x4s, then plywood. I read that this helps with the tactile impact of your subwoofers. Apparently, you don't feel as much vibration from the subs if you just put pad and carpet down over the concrete. 

The 1x4s will leave some large areas where there will be a 1 inch gap between the rubber and the plywood. Should I fill the gap with a little insulation?


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## HT Geek

GatorBlues said:


> So am I. I'm putting down a rubber layer, then some 1x4s, then plywood. I read that this helps with the tactile impact of your subwoofers. Apparently, you don't feel as much vibration from the subs if you just put pad and carpet down over the concrete.
> 
> The 1x4s will leave some large areas where there will be a 1 inch gap between the rubber and the plywood. Should I fill the gap with a little insulation?


Are you interested in improving airborne tactile feel or feeling the bass via the floor?


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## GatorBlues

HT Geek said:


> Are you interested in improving airborne tactile feel or feeling the bass via the floor?


Via the floor. As I was reading up on DIY subs, I learned that some are using mid-base modules behind their seats to get the vibrations they weren't feeling with a concrete floor. I don't have enough space to add yet more speakers. From what I read, doing the floor in the manner I described will allow it to vibrate like you'd feel if your theater was on the second floor.

I just thought of another question -- I assume I'll want to acoustically seal the drywall to the concrete floor and let this plywood floor vibrate. Does that make sense?


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## HT Geek

GatorBlues said:


> Via the floor. As I was reading up on DIY subs, I learned that some are using mid-base modules behind their seats to get the vibrations they weren't feeling with a concrete floor. I don't have enough space to add yet more speakers. From what I read, doing the floor in the manner I described will allow it to vibrate like you'd feel if your theater was on the second floor.
> 
> 
> 
> Should, yes. Concrete is great at absorption (when the concrete is on the floor), so moving your sub-floor up above that should help. I'm thinking you're probably better off not using insulation between the sub-floor and concrete.
> 
> You may want to price out the cost of Butt Kickers (or equivalent) versus your materials+labor cost of adding the sub-flooring. You will need a minimum of 2 layers of plywood sub-floor for stability. I don't recall if you plan on having a riser, but if you do then you'd need to take the floor design into consideration for that as well (e.g. place some extra 1x4 supports underneath the sub-floor where the riser will be built).
> 
> Have you looked at the Cinemar build thread? He incorporated a D-Box Motion Platform beneath his front row seats. I tried to locate the portion of his build thread that goes over the construction process for the cavity is housed in, but it seems at some point AVS Forum has changed the hyperlink format and existing links in some older threads (including Cinemar) no longer function (they all divert to the AVS Forums home page). It appears to me the old links only referenced a post id, whereas the new links include what are likely intended as search tags in the link title (presumably to increase search engine hit rates). I worked in Ecommerce a number of years ago, and I recall converting links to the latter format. It is difficult to catch all the old links and auto convert them, but it's frustrating from a user perspective.
> 
> Mario also used Aura Pro Bass Shakers in the rear seats. There's a thread here you may find worth reading that discusses Aura vs Butt Kickers.
> 
> 
> 
> 
> 
> I just thought of another question -- I assume I'll want to acoustically seal the drywall to the concrete floor and let this plywood floor vibrate.
> 
> 
> 
> No. You should run the drywall from ceiling to the sub-floor. Build the sub-floor first, then the inner wall on top of that. So, your construction order is:
> 
> 
> 
> Raised sub-floor
> Inner stud wall
> First ceiling layer
> First wall layer
> Second ceiling layer
> Second wall layer
> 
> 
> Click to expand...
Click to expand...


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## GatorBlues

HT Geek said:


> GatorBlues said:
> 
> 
> 
> You may want to price out the cost of Butt Kickers (or equivalent) versus your materials+labor cost of adding the sub-flooring. You will need a minimum of 2 layers of plywood sub-floor for stability. I don't recall if you plan on having a riser, but if you do then you'd need to take the floor design into consideration for that as well (e.g. place some extra 1x4 supports underneath the sub-floor where the riser will be built).
> 
> Have you looked at the Cinemar build thread? He incorporated a D-Box Motion Platform beneath his front row seats. I tried to locate the portion of his build thread that goes over the construction process for the cavity is housed in, but it seems at some point AVS Forum has changed the hyperlink format and existing links in some older threads (including Cinemar) no longer function (they all divert to the AVS Forums home page). It appears to me the old links only referenced a post id, whereas the new links include what are likely intended as search tags in the link title (presumably to increase search engine hit rates). I worked in Ecommerce a number of years ago, and I recall converting links to the latter format. It is difficult to catch all the old links and auto convert them, but it's frustrating from a user perspective.
> 
> Mario also used Aura Pro Bass Shakers in the rear seats. There's a thread here you may find worth reading that discusses Aura vs Butt Kickers.
> 
> 
> 
> 
> No. You should run the drywall from ceiling to the sub-floor. Build the sub-floor first, then the inner wall on top of that. So, your construction order is:
> 
> 
> 
> Inner stud wall
> Raised sub-floor
> First ceiling layer
> First wall layer
> Second ceiling layer
> Second wall layer
> 
> 
> 
> 
> I think the D-box products are far out of my price range. With respect to buttkickers, I was going to see how things feel and consider whether to add them later. I doubt I'll need them.
> 
> Why two layers of Plywood on the floor? I'm pretty sure the rest of the house has just one. Is there something special about the theater floor that needs two?
> 
> Thanks for the advice on sealing to the subfloor rather than the concrete.
Click to expand...


----------



## mhutchins

GatorBlues said:


> HT Geek said:
> 
> 
> 
> Why two layers of Plywood on the floor? I'm pretty sure the rest of the house has just one. Is there something special about the theater floor that needs two?
> 
> Thanks for the advice on sealing to the subfloor rather than the concrete.
> 
> 
> 
> I believe 2 layers is typical construction practice to eliminate the possibility of soft spots along the seems. The layers are arrayed to eliminate seam overlap as much as possible. Even tongue-and-groove seams are not as rigid as an area without a seam.
> 
> Mike
Click to expand...


----------



## HT Geek

GatorBlues said:


> HT Geek said:
> 
> 
> 
> Why two layers of Plywood on the floor? I'm pretty sure the rest of the house has just one. Is there something special about the theater floor that needs two?
> 
> 
> 
> I should have clarified. I was picturing 5/8" plywood in my head, but I don't know what you're planning.
> 
> You should use a minimum of 3/4" T&G plywood with the 1x4's spread apart a maximum of 24" on center. Even doing that you may get some floor creaks. If you use 2 layers with overlapping seams (minimum 1/2" thick each layer), you'll ensure you don't get a creaky floor. Placing your 1x4's closer together would also help reduce the likelihood of creaking.
> 
> And come to think of it, your approach with the sub-floor support could impact how you approach the order of your inner walls/ceiling/sub-floor construction. You may want to create a perimeter 1x4 all the way around the room (to allow the weight of your inner wall to be transferred to your concrete foundation). It could be fine without doing that, but it's also possible the weight of your inner walls and ceiling could cause some sagging over time along the edges of the sub-floor. Might be a non-issue. I don't know. I do know the ideal method of the floor/walls/ceilings going up is as I described in my previous post. Sorry to complicate matters further.
> 
> If you use 2 layers on the floor, the perimeter concerns I just mentioned should be a non-issue. Either way, a perimeter of 1x4's would be ideal. Small additional cost for peace-of-mind.
Click to expand...


----------



## GatorBlues

HT Geek said:


> GatorBlues said:
> 
> 
> 
> I should have clarified. I was picturing 5/8" plywood in my head, but I don't know what you're planning.
> 
> You should use a minimum of 3/4" T&G plywood with the 1x4's spread apart a maximum of 24" on center. Even doing that you may get some floor creaks. If you use 2 layers with overlapping seams (minimum 1/2" thick each layer), you'll ensure you don't get a creaky floor. Placing your 1x4's closer together would also help reduce the likelihood of creaking.
> 
> And come to think of it, your approach with the sub-floor support could impact how you approach the order of your inner walls/ceiling/sub-floor construction. You may want to create a perimeter 1x4 all the way around the room (to allow the weight of your inner wall to be transferred to your concrete foundation). It could be fine without doing that, but it's also possible the weight of your inner walls and ceiling could cause some sagging over time along the edges of the sub-floor. Might be a non-issue. I don't know. I do know the ideal method of the floor/walls/ceilings going up is as I described in my previous post. Sorry to complicate matters further.
> 
> If you use 2 layers on the floor, the perimeter concerns I just mentioned should be a non-issue. Either way, a perimeter of 1x4's would be ideal. Small additional cost for peace-of-mind.
> 
> 
> 
> I think we have 3/4 tongue and groove as the subfloor for the upper floors of the house. It is screwed down to prevent squeaking. I'll have to double check with the builder to be sure.
> 
> Thanks!
Click to expand...


----------



## HT Geek

GatorBlues said:


> HT Geek said:
> 
> 
> 
> I think we have 3/4 tongue and groove as the subfloor for the upper floors of the house. It is screwed down to prevent squeaking. I'll have to double check with the builder to be sure.
> 
> Thanks!
> 
> 
> 
> That is the norm. However, regular 3/4" sub-floors are nailed down across joists, such that there's no gap between the joists and the sub-floor. So, in your case the potential problem is you're elevating the new sub-floor every _n_". Does that make sense? The pressure of whatever is sitting on the sub-floor + the sub-floor material itself are applying gravitational force at only the points where your 1x4's contact the underside of the sub-floor.
> 
> So, first if you strengthen the thickness of the sub-floor, then the sub-floor itself becomes more rigid and is better able to handle what are called point loads without flexing. Secondly, you will have a consistent load on the sub-floor above its outer edges, created by the bottom plate of your inner stud wall. By utilizing 1x4's beneath the edge of the sub-flooring, you would reinforce the ability of the sub-floor to transmit that vertical load down to the concrete foundation.
> 
> I hope that's helpful and not confusing.
Click to expand...


----------



## bubbrik

Hello

I was wondering how to handle the heating/ac vent placed in the ceiling of the HT room. The bottom of the boots (straight or elbow) seems to be designed for one layer of drywall. When going with clips, hat channel, and double drywall, I would like to know how you handled the extra thickness of the ceiling?

Thanks


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----------



## GatorBlues

HT Geek said:


> GatorBlues said:
> 
> 
> 
> That is the norm. However, regular 3/4" sub-floors are nailed down across joists, such that there's no gap between the joists and the sub-floor. So, in your case the potential problem is you're elevating the new sub-floor every _n_". Does that make sense? The pressure of whatever is sitting on the sub-floor + the sub-floor material itself are applying gravitational force at only the points where your 1x4's contact the underside of the sub-floor.
> 
> So, first if you strengthen the thickness of the sub-floor, then the sub-floor itself becomes more rigid and is better able to handle what are called point loads without flexing. Secondly, you will have a consistent load on the sub-floor above its outer edges, created by the bottom plate of your inner stud wall. By utilizing 1x4's beneath the edge of the sub-flooring, you would reinforce the ability of the sub-floor to transmit that vertical load down to the concrete foundation.
> 
> I hope that's helpful and not confusing.
> 
> 
> 
> I'm a little confused simply because I may have misunderstood what to do with my riser. For the riser, I had thought that the drywall should go all the way to the concrete floor (with a quarter inch gape that will be acoustically caulked to the concrete), with the riser added later to the interior of the room after the double drywall is up. I was thinking of my contraption in the front of the theater as a mini-riser of sorts, which is why I was assuming it should be installed the same way. Is my plan for the big riser correct? What is the advantage of attaching the drywall to the baby riser?
Click to expand...


----------



## HT Geek

bubbrik said:


> I was wondering how to handle the heating/ac vent placed in the ceiling of the HT room. The bottom of the boots (straight or elbow) seems to be designed for one layer of drywall. When going with clips, hat channel, and double drywall, I would like to know how you handled the extra thickness of the ceiling?


I custom built the air return and supply vents into my room. 

Depending on the design of the boot/register/grille, you may have to create a short flue of some sort they attach to. Or you may be able to modify the OEM parts to fit in 2x thick drywall. Another option would be to install the 1st layer of drywall, install the boots, then install the 2nd layer of drywall.


----------



## HT Geek

GatorBlues said:


> I'm a little confused simply because I may have misunderstood what to do with my riser. For the riser, I had thought that the drywall should go all the way to the concrete floor (with a quarter inch gape that will be acoustically caulked to the concrete), with the riser added later to the interior of the room after the double drywall is up. I was thinking of my contraption in the front of the theater as a mini-riser of sorts, which is why I was assuming it should be installed the same way. Is my plan for the big riser correct? What is the advantage of attaching the drywall to the baby riser?


You're on the right path. The riser gets built after the room's floor/wall/ceiling inner shell. Leave a 1/4" or so gap between your riser and the drywall. Don't connect the riser to the walls directly (e.g. screws, etc.). Gravity will keep it in place.

In your case - with a raised floor - this will be another area where you need to plan your sub-floor carefully. You will want to ensure there is sufficient support beneath your riser. That likely will just mean a few extra 1x4 boards placed strategically to ensure even load support of the riser above them.

To re-cap, ideally you'll build the sub-floor, your wall and ceiling framing (inner stud wall), then stagger your ceiling/wall drywall layers, and then create your riser. Leave 1/4" or so gap in corners where the various surfaces meet. For example, where you have a corner between drywall wall and sub-floor, and drywall wall and ceiling. Caulk the gaps. The purpose of the gaps is to provide some decoupling between neighboring surfaces by creating a very small separation. The acoustic caulk seals the gap to prevent flanking sound leakage. Acoustic caulk is more flexible than regular caulk so even though you are technically recoupling the surfaces, it is with a material designed to give a little and bounce back.

So, there's two factors at play here. One is physically supporting the inner wall you're building. The other is retaining as much flexibility as possible in your inner wall so when sound wave pressures hit them they are able to flex a little while absorbing energy at the same time.

If you build your new sub-floor as I've indicated, it will also help keep the column speaker backer boxes isolated from the main structure, as they'll also be on top of your floating floor.


----------



## doveman

HT Geek said:


> Short answer is, yes - you're right (about more mass being better). The point I apparently didn't get across too well is I don't believe a small area of the floor lacking an additional layer (mass) of solid material will significantly affect your outcome. I was attempting to suggest focusing your attention and efforts on other areas of your room and not worrying about that too much, particularly since I got the impression your choices are limited. I'm sure you could come up with a way to fill the area, but my suggestion is the minimal gain is probably not worth the effort required to do so.
> 
> So, bottom line - yes, you're right a bit more mass in the gap area would help with sound absorption. However, I don't personally believe it's worth the effort given your circumstances. Purely a personal opinion though.


I've read your other post and I get that caulk is better than no caulk. What I'm having trouble understanding is how the caulked area doesn't create a weak spot that undermines the soundproofing. I realise that this is largely academic as we have to seal the gap and caulk is the best/only option but still the question bothers me.

I've attached three drawings to illustrate my thinking. In the first one, there's no caulk and I've drawn arrows to show where sound could be rising up from the floor (and then travelling through the insulation) and coming out of the wall (which has less plaster, or even none, on the area below the wall). These sounds would then be free to travel up into my room and equally sound could travel from my room down into the wall and the concrete slab. 

In the second drawing I've added the double drywall walls, with the clips+channel indicated in black with insulation between. I imagine in some scenarios people only need to treat the floor but I'm almost certainly going to have to do the walls as well, so I'll assume that's the case here. Without caulk, there's still no real impediment to sound travelling in either direction (other than the size of the gap, which as we've already discussed would be too small for LFE to travel through).

In the third drawing I've filled both the floor perimeter gap and the gap under the wall with caulk. This obviously improves things considerably compared to having those gaps open but what I'm querying is whether the relatively low mass of caulk can sufficiently block mid->high range frequencies? It doesn't matter whether caulk blocks those frequencies less than two layers of OSB, all that matters is whether caulk blocks them enough that no human would notice the difference. In the case of the sounds emanating from under the floor, there's two separate layers of caulk between them and my room which no doubt helps, but only one layer between the above floor section of wall and my room.

If caulk does sufficiently block mid->high range frequencies, then presumably if they were all that needed addressing and there was no LFE to worry about, then a single layer of something light-weight and low mass like plywood would be sufficient on the walls (still using clips+channel to decouple), as I imagine even the lightest wood has more mass than caulk? Obviously one would have to use something thicker for the floor as it has to support the load but still only a single layer would be needed.

As for the perimeter tape, I should clarify that it's not a choice of caulk or perimeter tape. As shown in that Cochlear drawing I linked to previously (screenshot attached), there's still caulk at the top, just perimeter tape underneath that.

So the perimeter tape doesn't substitute for caulk as a means of closing the gap at the top. I presume it helps to prevent noise from the wall getting into the underfloor space and also to keep the subfloor from shifting. With caulk, how much depth would you fit, just equal to the top layer of 18mm OSB or even less and how do you control the depth of the caulk as there's nothing to stop it going all the way down to the bottom? Would 18mm depth of caulk be sufficient to stop the subfloor shifting?

If the perimeter tape is completely unnecessary to stop the subfloor shifting, then I'd be inclined to fit a piece of wood to the wall in it's place to seal it off, or maybe just add some extra plaster, making sure that whatever I use doesn't touch the subfloor as obviously anything solid would transfer sound. I wouldn't have thought it would matter if the wood/plaster touches the caulk as the caulk is already attached to the wall anyway and that would provide a base to build the caulk up from.


----------



## HT Geek

doveman said:


> In the third drawing I've filled both the floor perimeter gap and the gap under the wall with caulk. This obviously improves things considerably compared to having those gaps open but what I'm querying is whether the relatively low mass of caulk can sufficiently block mid->high range frequencies? It doesn't matter whether caulk blocks those frequencies less than two layers of OSB, all that matters is whether caulk blocks them enough that no human would notice the difference. In the case of the sounds emanating from under the floor, there's two separate layers of caulk between them and my room which no doubt helps, but only one layer between the above floor section of wall and my room.
> 
> If caulk does sufficiently block mid->high range frequencies, then presumably if they were all that needed addressing and there was no LFE to worry about, then a single layer of something light-weight and low mass like plywood would be sufficient on the walls (still using clips+channel to decouple), as I imagine even the lightest wood has more mass than caulk? Obviously one would have to use something thicker for the floor as it has to support the load but still only a single layer would be needed.


The caulk simply completes the process of creating a sealed chamber of sorts. It will help dampen flanking sounds that could otherwise enter via a small gap. It's purpose is to cover gaps. The purpose of using acoustical caulk is it's designed to flex. Your walls will be flexing a bit from the sound pressure applied to them. Small gaps are normally left between adjoining surfaces (e.g. wall and floor) so the surfaces can flex independently of each other.




> As for the perimeter tape, I should clarify that it's not a choice of caulk or perimeter tape. As shown in that Cochlear drawing I linked to previously (screenshot attached), there's still caulk at the top, just perimeter tape underneath that.
> 
> So the perimeter tape doesn't substitute for caulk as a means of closing the gap at the top. I presume it helps to prevent noise from the wall getting into the underfloor space and also to keep the subfloor from shifting. With caulk, how much depth would you fit, just equal to the top layer of 18mm OSB or even less and how do you control the depth of the caulk as there's nothing to stop it going all the way down to the bottom? Would 18mm depth of caulk be sufficient to stop the subfloor shifting?
> 
> If the perimeter tape is completely unnecessary to stop the subfloor shifting, then I'd be inclined to fit a piece of wood to the wall in it's place to seal it off, or maybe just add some extra plaster, making sure that whatever I use doesn't touch the subfloor as obviously anything solid would transfer sound. I wouldn't have thought it would matter if the wood/plaster touches the caulk as the caulk is already attached to the wall anyway and that would provide a base to build the caulk up from.


It's up to you if you want to use the perimeter tape or not. I just don't believe it's going to have a significant impact on your overall sound proofing results.

You just want the caulk in between material surface layers on the inside of your room, where there's a gap. If your gap is larger than about 10mm or so, you may need to use what is commonly referred to in the USA as "caulk saver." 











IMHO, I don't believe there's going to be a significant difference in sound proofing results whether you plug the holes on the edges of your flooring plan with OSB, drywall, etc. or not as it doesn't seem to be a lot of space. It's possible that I'm wrong, but as I see it the concern there will be flanking noise from below. Since any sound from below will already have to travel through the other floor areas, it's already going to be damped. If you feel the need to fill the space, I would suggest something flexible such as stuffing it with loose fiberglass insulation. That would have the benefit of further reducing sound transmission and it would be a relatively easy process to implement. 

I did not intend to suggest filling the edge holes/space with caulk. It seems as if that would be quite a bit of caulk! The caulk only needs to in seams between surface materials.


----------



## BasementBob

HT Geek said:


> "caulk saver."


We call that "backer rod" 
It's available in several diameters from 1/4" to 1". 


Note that caulking that covers a wide gap will fail. Googling for "caulk two point adhesion" "caulk three point adhesion chinking", or "caulk why joints fail" will turn up details. Basically caulk should only fill gaps between 1/4" and 3/8", with no side nor depth more than 1/4" from any point on the caulk. Backer rod is good for reducing that gap down to something caulking will stay with.


----------



## Mpoes12

I couldn't keep up with all the back and forth but as for this discussion of caulking and mass. The gap should and usually is very small. As HTGeek pointed out, a surprising amount of sound can get through a crevice. You want to avoid having the wall sitting right on the floor and the floor sitting right against the wall. It helps decouple them from each other. That gap should be filled with caulk. Typically this gap is tiny so the loss of mass is minor. 

I too made a big deal about this. I was really worried. All the pros and everything was reading said don't worry and just caulk. I can honestly say my end product bore our that advice. Just don't lose sleep over it. The issue is minor.

In fact many people have far greater problems with their door frames, hvac, etc in this regard. 


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## Mpoes12

HT Geek said:


> GatorBlues said:
> 
> 
> 
> No. You should run the drywall from ceiling to the sub-floor. Build the sub-floor first, then the inner wall on top of that. So, your construction order is:
> 
> 
> 
> 
> 
> 
> Inner stud wall
> 
> Raised sub-floor
> 
> First ceiling layer
> 
> First wall layer
> 
> Second ceiling layer
> 
> Second wall layer
> 
> 
> 
> 
> 
> 
> HTGeek what makes you feel this way? I'm not sure I've read a definitive on this before. In my mind there are advantages to running the walls closer to the concrete and caulking it. Then adding the subfloor and caulking the perimeter again. My thinking is that since the floors typically aren't built to be soundproof over concrete this avoids a possible flanking path through the floor.
> 
> I didn't address this in my build because I don't have a subfloor. I put a sub on the riser and have butt kickers for the tactile sensation.
> 
> While some may use MBM's for tactile bass I did it for smoothing the bass. I have three subs currently used for optimal bass coverage. I actually used my MBM's up front, the lower frequency sub (ULF) on the riser, and I'm currently finishing a fourth. I think the most important reason for having subs like that is smoother bass rather than the feel.
> 
> At a future date I plan to commit the cardinal sin and penetrate my shell to duct bandpass subs into the room. I have a very large crawl space around the outer shell and want to hide them in that space. I have some ideas on how to duct the bass without impacting soundproofing much.
> 
> 
> 
> Sent from my iPhone using Tapatalk
Click to expand...


----------



## HT Geek

Mpoes12 said:


> HTGeek what makes you feel this way? I'm not sure I've read a definitive on this before. In my mind there are advantages to running the walls closer to the concrete and caulking it. Then adding the subfloor and caulking the perimeter again. My thinking is that since the floors typically aren't built to be soundproof over concrete this avoids a possible flanking path through the floor.


Thanks for quoting part of my post, as I realized I had juxtaposed the order of the first 2 list items. They should have been in the order of my preceding text comment. I've edited my original comment (above).

Anyway, to answer your question: My thinking was if the goal is to get vibrations through the floor, then it may be better to allow any vibrations in the walls to travel down to the sub-floor instead of the concrete. However, I'm not sure it matters a whole lot either way. I agree with you either caulk and/or the thin insulation that goes under the footer (the name of which escapes me atm) should be used.

There shouldn't be a flanking issue if all the gaps and seams are caulked.




> At a future date I plan to commit the cardinal sin and penetrate my shell to duct bandpass subs into the room. I have a very large crawl space around the outer shell and want to hide them in that space. I have some ideas on how to duct the bass without impacting soundproofing much.


That should be interesting!


----------



## Mpoes12

HT Geek said:


> Thanks for quoting part of my post, as I realized I had juxtaposed the order of the first 2 list items. They should have been in the order of my preceding text comment. I've edited my original comment (above).
> 
> 
> 
> Anyway, to answer your question: My thinking was if the goal is to get vibrations through the floor, then it may be better to allow any vibrations in the walls to travel down to the sub-floor instead of the concrete. However, I'm not sure it matters a whole lot either way. I agree with you either caulk and/or the thin insulation that goes under the footer (the name of which escapes me atm) should be used.
> 
> 
> 
> There shouldn't be a flanking issue if all the gaps and seams are caulked.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> That should be interesting!




Hey I didn't invent the idea! Seems to be working for a variety of manufacturers. I won't cut holes until I'm confident in the designs. At the moment the bandpass subs have undersized ports and overload easily. The plan is to use an hvac duct boot or possibly a 6" flares duct end. A rubber isolation collar, semirigid flex duct, and then another rubber collar and take off. The semirigid flexduct is stiffened and damped with window flashing tape. I have the materials just waiting on a friend with a router to stop by and help me cut some holes in the boxes. I'll test them behind the false wall for now. 

I'm going to reinforce the entry point into the room with a third layer of drywall, caulk it really well, etc. even if it does compromise the soundproofing a little, it's leaking sound into a craw space under the stairs that is fully dry walled itself. 

I actually drew up plans for these bandpass subs using 18" or 21" B&C drivers. They really will be nutty. 130db at 1 meter in a through wall subwoofer. The 18" driver I want should be available any day now and so once it is I'll order one to test. If it works out I'll go from there. 


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## TechEnthusiast

*Brainstorming Stage*

Hi, I'd appreciate any feedback on my soundproofing concept.

For starters, I already have a room within a room, so I'm simply going to do the following to the interior drywall:



1st Layer: MLV or Peacemaker (6.4 mm)
2nd Layer: Audimute's Acoustic Tiles
3rd Layer: Acoustic Wedges
4th Layer: Base Traps (in corners)
5th Layer: Sound Absorption Sheets/Blankets (Hanging)

I'm hoping to affix the first layer with some kind of spray adhesive. Then I'll use the same adhesive to affix the tiles and wedges onto the MLV/Peacemaker. Not sure what I'll do with the ceiling, though.

So...instead of decoupling and installing sheet rock, will this alternative route help me achieve my goal of "soundproofing" the space (despite my using an inordinate amount of sound absorption techniques)? If so, by how many decibels (theoretically)?


----------



## deewan

TechEnthusiast said:


> Hi, I'd appreciate any feedback on my soundproofing concept.
> 
> For starters, I already have a room within a room, so I'm simply going to do the following to the interior drywall:
> 
> 
> 
> 1st Layer: MLV or Peacemaker (6.4 mm)
> 2nd Layer: Audimute's Acoustic Tiles
> 3rd Layer: Acoustic Wedges
> 4th Layer: Base Traps (in corners)
> 5th Layer: Sound Absorption Sheets/Blankets (Hanging)
> 
> I'm hoping to affix the first layer with some kind of spray adhesive. Then I'll use the same adhesive to affix the tiles and wedges onto the MLV/Peacemaker. Not sure what I'll do with the ceiling, though.
> 
> So...instead of decoupling and installing sheet rock, will this alternative route help me achieve my goal of "soundproofing" the space (despite my using an inordinate amount of sound absorption techniques)? If so, by how many decibels (theoretically)?


I believe you are going to be creating a very dead sounding space if you follow through on your plans. Many of those products you have listed are used to help absorb sound inside the room and prevent sound from reflecting and causing issues inside the room. They are not used to help keep sound from escaping the room. 

I would wager that if you already have a room within a room and the inner room is properly decoupled from the main structure of the house you are already pretty well sound isolated once you hang one or two layers of drywall. Depending how "sound proof" you want the room to be you could use green glue between two layers of drywall and skip the clips and channel.


----------



## HT Geek

Mpoes12 said:


> Hey I didn't invent the idea! Seems to be working for a variety of manufacturers. I won't cut holes until I'm confident in the designs. At the moment the bandpass subs have undersized ports and overload easily. The plan is to use an hvac duct boot or possibly a 6" flares duct end. A rubber isolation collar, semirigid flex duct, and then another rubber collar and take off. The semirigid flexduct is stiffened and damped with window flashing tape. I have the materials just waiting on a friend with a router to stop by and help me cut some holes in the boxes. I'll test them behind the false wall for now.


Well, why not take advantage of the properties of flanking, eh? 

Have you considered an infinite baffle? If you're going to poke a hole in your shell and you have the space, it may be worth considering. Not sure it would work in your case (space-wise). I don't see why you couldn't also do it via your duct concept. 

What is an infinite baffle subwoofer? [HT Shack]

IB build project w/pics, REW data


----------



## HT Geek

TechEnthusiast said:


> Hi, I'd appreciate any feedback on my soundproofing concept.
> 
> For starters, I already have a room within a room, so I'm simply going to do the following to the interior drywall:


How would you describe the construction of your existing room-within-a-room? Double stud, staggered stud, clips & channel, etc.?? Are the interior walls/ceiling/floor decoupled from the home's structure? Which floor of your home is the room on?




> So...instead of decoupling and installing sheet rock, will this alternative route help me achieve my goal of "soundproofing" the space (despite my using an inordinate amount of sound absorption techniques)? If so, by how many decibels (theoretically)?





deewan said:


> I believe you are going to be creating a very dead sounding space if you follow through on your plans. Many of those products you have listed are used to help absorb sound inside the room and prevent sound from reflecting and causing issues inside the room. They are not used to help keep sound from escaping the room.


+1




> ... inner room is properly decoupled from the main structure of the house you are already pretty well sound isolated once you hang one or two layers of drywall. Depending how "sound proof" you want the room to be you could use green glue between two layers of drywall and skip the clips and channel.


Agreed. Your base should be 2x layers of drywall, either with or without a viscoelastic material in between the layers (e.g. Green Glue). The GG lowers the resonance of your walls (good thing). With the exception of MLV, all the other products you've identified are designed to tackle particular issues present in a room that has already had a 2+ sheet drywall shell built. MLV is normally applied to the studs before drywall is attached. MLV is not very useful as a sound dampening tool. It's awkward and difficult to apply to the studs, and you're looking at minimal benefit in most circumstances. 

To illustrate what I'm talking about, here's a selection of lab results with various combinations of drywall layers, Green Glue (or not), and MLV (or not). The examples that don't have clips are single stud walls (not room-within-a-room). This is just for comparison purposes, to illustrate the benefits of extra drywall layers, drywall thickness, MLV, and Green Glue. All are 2x4 wood stud walls, 24" O.C. with R13 fiberglass insulation, unless indicated otherwise:



1x 5/8" Drywall | 1x 5/8" Drywall; no insulation: STC 38
1x 5/8" Drywall | 1x 5/8" Drywall [with R13 insulation]: STC 40
2x 5/8" Drywall | 1x 5/8" Drywall: STC 42
2x 1/2" Drywall + MLV | 1x 1/2" Drywall: STC 44
1x 5/8" Drywall + MLV | 1x 5/8" Drywall: STC 45
2x 1/2" Drywall + GG | 1x 1/2" Drywall: STC 52
2x 5/8" Drywall + GG | 1x 5/8" Drywall: STC 52
1x 5/8" Drywall + RSIC-1 Clips | 1x 5/8" Drywall: STC 56 [16" O.C. studs]
1x 5/8" Drywall + RSIC-1 Clips + 1 psf MLV | 1x 5/8" Drywall: STC 57 [16" O.C. studs]
1x 5/8" Drywall + RSIC-1 Clips + 2 psf MLV | 1x 5/8" Drywall: STC 58 [16" O.C. studs]
2x 5/8" Drywall + RSIC-1 Clips | 1x 5/8" Drywall: STC 60 [16" O.C. studs]
2x 5/8" Drywall + GG + IB-1 Clips | 1x 5/8" Drywall: STC 67
2x 5/8" Drywall + GG + IB-1 Clips | 2x 5/8" Drywall + GG: STC 71

At first glance, looking at what I like to call the 'headline number' (STC), it appears using MLV is a no-brainer, right? 5 STC points better than no MLV on a single drywall layer on both sides of a wall. Well, unfortunately it's not that straightforward. Comparing the results ONLY to a standard 1x/1x wall, MLV does provide significant benefits in most frequency ranges (+5 STC; only 63-80 Hz, 250-315 Hz get worse). However, look at what happens when you decouple one side of the wall and then add MLV. Hardly any difference. What does this tell us? MLV is quite useful on a standard, single shared stud wall with no decoupling. However, decoupling is more effective, and decoupling plus MLV results in minimal gains (+1 STC) versus decoupling only.

You can also infer from the results above that Green Glue is more effective at sound proofing than MLV (+10 STC for GG; 52 vs 42). I haven't seen any lab reports that used both MLV and GG. It's possible the combination would be even better, but even if that is true, we already know when decoupling is added into the mix, MLV is likely to only provide +1 STC at best. And we know that swapping out MLV and replacing it with GG on a non-decoupled wall gives us another +8 STC (52 vs 44).

Point is most people don't use MLV because unless you're going to have a standard 1x/1x drywall wall, it's really not worth the work and cost. It is true that the heavier the MLV, the more effective, but beyond 2 psf it's going to be quite difficult to install and could begin to have an adverse effect on the load bearing capability of whatever one is attaching it to.


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## Mpoes12

I don't know if this was already said. T MLV should also not be adhered to drywall. That isn't how it was designed to be used nor most effective. It should be adhered to the studs directly with the drywall over that. This allows it to act as a limp mass between studs. It also was originally specified on 24" studs for this reason. When you glue it to the drywall the mass is made rigid by coupling. 

If the room within a room was done right and drywall is already hung, then a second layer with green glue would be more effective. 


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## HT Geek

Mpoes12 said:


> I don't know if this was already said. T MLV should also not be adhered to drywall. That isn't how it was designed to be used nor most effective. It should be adhered to the studs directly with the drywall over that. This allows it to act as a limp mass between studs. It also was originally specified on 24" studs for this reason. When you glue it to the drywall the mass is made rigid by coupling.


Good points.

You've also reminded me one of the issues with MLV is its nature tends to make for inconsistent installation techniques. There's very few lab tests with it, and I only recall one with details of how it was hung on the studs. I still don't get how it's possible to hang it 'limply' as you said. I know it's the recommended method, but how does one interpret "limply?" How does one retain limpness while mashing a sheet of drywall onto it? 

Btw, I'm not questioning you... rather, trying to underscore your comments. Personally, I think MLV is just so much more likely to create a problem versus solve one that it's not worth considering.


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## deewan

I apologize for the double post. I have a question for the experts on something I'm not entirely sure on after some of my research.

HVAC pipe. I have three runs of HVAC pipe between the overhead floor joists of my theater. None of these runs will be fed or output from the same air space as my theater since the theater will have it's own cooling/heating system. I'm trying to decide for sound isolation if I need replace the pipe runs with flex duct to help reduce sound transmission to rooms upstairs. The only sound that would enter the pipe would be sound transmitting through (from theater up to HVAC pipe) drywall, green glue, OSB, 25-gauge furring channel, clips and the dead space between the floor joists filled with Owens Corning Thermafiber or Roxuol Rock Wool. I've also considered keeping the pipe but wrapping the pipe with Dynamat or a similar product to help insulate them a little more. I'm just not sure how much I need to worry about sound making it into the HVAC pipe before it gets a clear path to the output vents in the rooms above.

Here is a picture of the pipes I am considering replacing with flex tubing. Thoughts?


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## Mpoes12

As I understand limp hanging just means it's hung on the studs. The drywall won't add much stiffness over the mlv because it isn't adhered to the drywall. 

While I've never seen true lab tests of this I have seen builds of studios where a half inch of material was added on the studs after hanging the mlv to give a half in of air space. 

MLV is still far more widely used than is greenglue. It doesn't get tested like Green Glue partly because it has been tested and the findings published in 100's of journal articles, books, etc. if you search the literature you will find more information. My understanding is that there are also a number of lab reports floating around that give the info you suggest. The limp vs sand which approach was tested and that report is available. I forget where I found it but if I find it I'll share. 

I'm not as anti-MLV as some. I actually think MLV used in conjunction with CLD has merit. They each operate on slightly different principles and so I think they would provide coverage where the other is weakest. I have a feeling that it would extend the TL to lower frequencies and would also add 2-3 stc points on average across the board. I think it's biggest negative is that it's really expensive and hard to work with. For the same cost you could add a third layer of drywall with green glue. In fact for the same cost you could probably add a 4th layer. 


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## Mpoes12

deewan said:


> I apologize for the double post. I have a question for the experts on something I'm not entirely sure on after some of my research.
> 
> HVAC pipe. I have three runs of HVAC pipe between the overhead floor joists of my theater. None of these runs will be fed or output from the same air space as my theater since the theater will have it's own cooling/heating system. I'm trying to decide for sound isolation if I need replace the pipe runs with flex duct to help reduce sound transmission to rooms upstairs. The only sound that would enter the pipe would be sound transmitting through (from theater up to HVAC pipe) drywall, green glue, OSB, 25-gauge furring channel, clips and the dead space between the floor joists filled with Owens Corning Thermafiber or Roxuol Rock Wool. I've also considered keeping the pipe but wrapping the pipe with Dynamat or a similar product to help insulate them a little more. I'm just not sure how much I need to worry about sound making it into the HVAC pipe before it gets a clear path to the output vents in the rooms above.
> 
> Here is a picture of the pipes I am considering replacing with flex tubing. Thoughts?


Don't change those to flexduct. Leave them alone. I think you may be mixing up concepts a bit here. The reason to use acoustic flex duct is because it has a microperforated inner layer that absorbs sound that is transmitted through the duct. Transmission loss of flex duct is next to nothing (sound readily travels through flexduct). Transmission loss of steel ducting is actually fairly high due to the mass and stiffness. If you dampen the steel ducting (which dampens the resonance spike at the critical frequency) you actually get a value on par with a single layer of drywall or better. 


I'm not sure of your plans, but if you are building a soundproof theater, then the ceiling itself will largely keep sound from transmitting through to the ductwork. The steel ductwork will further mitigate transmission. You should have very little sound that makes it to the duct work. 


To maximize this, you will want to insulate around the ductwork. The insulation will help absorb some of the sound, help dampen the steel, etc. If you really are worried there are spray on damping materials that will increase TL. You would spray it on all the ductwork before insulating and hanging drywall. Me personally, I wouldn't bother. I did it to mine largely because I did run the ductwork into my theater and I did need to maximize the damping and TL of the ducting. You don't have the same issues.


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## HT Geek

Mpoes12 said:


> I have a feeling that it would extend the TL to lower frequencies and would also add 2-3 stc points on average across the board. I think it's biggest negative is that it's really expensive and hard to work with. For the same cost you could add a third layer of drywall with green glue. In fact for the same cost you could probably add a 4th layer.


Yeah. It's a P.I.T.A. to work with, which is primarily why I'm not a big fan of it. I agree that adding another drywall layer is easier. GTK regarding your other comments above.


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## HT Geek

deewan said:


> Here is a picture of the pipes I am considering replacing with flex tubing. Thoughts?


Agreed with @Mpoes12. You could:



Do nothing to them
Stuff fiberglass insulation around them
Apply Dynamat or similar material to them

Personally, I'd probably stuff fiberglass insulation around them. Or do nothing. The concern with ductwork is normally related to sound flanking inside the ducts (bouncing) into or out of the HT room. In your case, your sound from the HT room will be hitting the ducts laterally and only after penetrating your shell. Should be a non-issue. Use insulation around it if you want to be sure you've done what you can, just in case. Stuffing some fiberglass around them would be cheap, quick, and effective. Don't use Kraft paper backed for this purpose.

On another note, may I ask why you're planning on drywall over a layer of OSB? I did this in my room and I'll tell you if I were to do it over, I would not do it. The OSB is a pain to work with. In theory you'd think it would be easier to apply than the drywall, but in fact the opposite is true. Cutting drywall sheets on each end of the wall and ceiling as you work your way around the room is much quicker and easier than cutting OSB for the same purpose. And if you over-cut the OSB, you're kinda stuck with a bigger gap than you wanted (or rip another sheet). 

If there's a good reason then by all means go for it, but I wouldn't do it again unless I felt there was a strong purpose to do so. For instance, I previously thought it would be useful to be able to 'put a nail/screw anywhere.' Well, guess what? I had no need of that! It might help just a tad with some of the furring strips for my fabric frames, but quite frankly they would have done just fine being screwed into a 2x drywall/GG sandwich. 

Unless you truly have a need, I hope I've convinced you to just do a 2x drywall/Green Glue sandwich! Should be cheaper too if you're paying for labor. Caulk or mud the seams on the first layer (don't sand/finish it). Acoustic caulk is preferable, but not required. Outer/Second layer, mud, sand, and finish as normal.


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## deewan

Thanks @Mpoes12 and @HT Geek. I knew the flex vent works mostly to stop sound from traveling within a vent, but I wasn't sure how much sound would get into the pipe through my 'soundproof shell' of a room and then into the pipe and if that would cause my any concern. Sounds like I don't have to worry and wrapping some unface insulation around it will be good enough. THANKS!



HT Geek said:


> On another note, may I ask why you're planning on drywall over a layer of OSB? I did this in my room and I'll tell you if I were to do it over, I would not do it. The OSB is a pain to work with. In theory you'd think it would be easier to apply than the drywall, but in fact the opposite is true. Cutting drywall sheets on each end of the wall and ceiling as you work your way around the room is much quicker and easier than cutting OSB for the same purpose. And if you over-cut the OSB, you're kinda stuck with a bigger gap than you wanted (or rip another sheet).
> 
> If there's a good reason then by all means go for it, but I wouldn't do it again unless I felt there was a strong purpose to do so. For instance, I previously thought it would be useful to be able to 'put a nail/screw anywhere.' Well, guess what? I had no need of that! It might help just a tad with some of the furring strips for my fabric frames, but quite frankly they would have done just fine being screwed into a 2x drywall/GG sandwich.
> 
> Unless you truly have a need, I hope I've convinced you to just do a 2x drywall/Green Glue sandwich! Should be cheaper too if you're paying for labor. Caulk or mud the seams on the first layer (don't sand/finish it). Acoustic caulk is preferable, but not required. Outer/Second layer, mud, sand, and finish as normal.


Great advice on why not to use OSB. My reasoning for the OSB layer is the ability to stick a nail/screw anywhere. I'm doing all the labor myself so the cost for labor is not an factor. In my theater I plan on having acoustically transparent splayed walls and ceiling. Strange term, I know so let me explain. I hope to build a soundproof shell of a room suing clips, channel, green glue and two layers of something for walls. Inside that shell, I will build some type of wall skeleton for acoustically transparent fabric to cover and create a splayed wall feel. I realize this defeats the purpose of splayed walls, but I'm going for the look not the sonic benefits of splayed walls. Any sound treatments will be hidden behind the AT splayed walls and ceiling. This also allows me to save a lot of time by not needing to properly tape, mud, sand and paint walls. In essence the walls will be built and finished very similar to my last theater, only the fabric frames will be splayed or angled a bit instead of laying flat against the drywall. Here is the example of my previous room and the fabric frames I made to cover the walls.









So, to sum it up, I'd like to be able to attach the splayed frames anywhere along my walls or ceiling without having to worry about hitting channel or the drywall supporting the weight. As of right now I plan on having my surround and overhead speakers exposed in the room, not hidden within backer boxes. So this are also things I'd like to know I can put almost anywhere without having to worry about channel.

But you have given me some pause to if I should create backer boxes and use two layers of drywall instead. I'll give it some thought.


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## TechEnthusiast

deewan said:


> I would wager that if you already have a room within a room and the inner room is properly decoupled from the main structure of the house you are already pretty well sound isolated once you hang one or two layers of drywall. Depending how "sound proof" you want the room to be you could use green glue between two layers of drywall and skip the clips and channel.


Would GG between two layers of drywall mitigate low-frequency sounds (e.g., 20 Hz)? Would nailing/screwing be required?



HT Geek said:


> How would you describe the construction of your existing room-within-a-room? Double stud, staggered stud, clips & channel, etc.?? Are the interior walls/ceiling/floor decoupled from the home's structure? Which floor of your home is the room on?
> 
> Agreed. Your base should be 2x layers of drywall, either with or without a viscoelastic material in between the layers (e.g. Green Glue). The GG lowers the resonance of your walls (good thing). With the exception of MLV, all the other products you've identified are designed to tackle particular issues present in a room that has already had a 2+ sheet drywall shell built.
> 
> 
> 1x 5/8" Drywall | 1x 5/8" Drywall; no insulation: STC 38
> 1x 5/8" Drywall | 1x 5/8" Drywall [with R13 insulation]: STC 40
> 2x 5/8" Drywall | 1x 5/8" Drywall: STC 42
> 2x 1/2" Drywall + MLV | 1x 1/2" Drywall: STC 44
> 1x 5/8" Drywall + MLV | 1x 5/8" Drywall: STC 45
> 2x 1/2" Drywall + GG | 1x 1/2" Drywall: STC 52
> 2x 5/8" Drywall + GG | 1x 5/8" Drywall: STC 52
> 1x 5/8" Drywall + RSIC-1 Clips | 1x 5/8" Drywall: STC 56 [16" O.C. studs]
> 1x 5/8" Drywall + RSIC-1 Clips + 1 psf MLV | 1x 5/8" Drywall: STC 57 [16" O.C. studs]
> 1x 5/8" Drywall + RSIC-1 Clips + 2 psf MLV | 1x 5/8" Drywall: STC 58 [16" O.C. studs]
> 2x 5/8" Drywall + RSIC-1 Clips | 1x 5/8" Drywall: STC 60 [16" O.C. studs]
> 2x 5/8" Drywall + GG + IB-1 Clips | 1x 5/8" Drywall: STC 67
> 2x 5/8" Drywall + GG + IB-1 Clips | 2x 5/8" Drywall + GG: STC 71
> 
> However, decoupling is more effective, and decoupling plus MLV results in minimal gains (+1 STC) versus decoupling only.
> 
> You can also infer from the results above that Green Glue is more effective at sound proofing than MLV (+10 STC for GG; 52 vs 42).
> 
> Point is most people don't use MLV because unless you're going to have a standard 1x/1x drywall wall, it's really not worth the work and cost. It is true that the heavier the MLV, the more effective, but beyond 2 psf it's going to be quite difficult to install and could begin to have an adverse effect on the load bearing capability of whatever one is attaching it to.



I appreciate your informative reply.

Single stud walls. First floor. The interior walls/ceiling/flooring aren't decoupled from the home's structure. Dimensions: L = 9.2 Feet / W = 6 Feet / H = 8 Feet.

I suppose that in addition to the other products I mentioned (excluding MLV or Peacemaker), I'll use a viscoelastic material (i.e., GG) in between the drywall layers. I'm notably interested in installing that STC 71 configuration: 2x 5/8" Drywall + GG + IB-1 Clips | 2x 5/8" Drywall + GG. However, my primary concern is whether I can do it by myself. I've never done anything like this. Perhaps I could hire someone to do this for me? If so, how much do you think it'll cost? Are there even better (yet still affordable) configurations?


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## deewan

TechEnthusiast said:


> Would GG between two layers of drywall mitigate low-frequency sounds (e.g., 20 Hz)? Would nailing/screwing be required?[/COLOR]


You would need screws to attach a second layer of drywall. Low frequency is the most difficult to isolate. I'm fairly certain what you had planned on doing would have little impact on keep sound and low frequency sound inside your room.




TechEnthusiast said:


> I appreciate your informative reply.
> 
> Single stud walls. First floor. The interior walls/ceiling/flooring aren't decoupled from the home's structure. Dimensions: L = 9.2 Feet / W = 6 Feet / H = 8 Feet.
> 
> I suppose that in addition to the other products I mentioned (excluding MLV or Peacemaker), I'll use a viscoelastic material (i.e., GG) in between the drywall layers. I'm notably interested in installing that STC 71 configuration: 2x 5/8" Drywall + GG + IB-1 Clips | 2x 5/8" Drywall + GG. However, my primary concern is whether I can do it by myself. I've never done anything like this. Perhaps I could hire someone to do this for me? If so, how much do you think it'll cost? Are there even better (yet still affordable) configurations?


This seems like a really small room. 55 sq ft total space with a width of 6 ft? Sounds like your describing a closet as a room within a room. This is the best picture explanation I can find on short notice of a room within a room. The space on the right is a room within a room. There is a structure wall and inside of that, decoupled from the structural wall, is another set of walls creating the inner room. 









The double, decoupled walls is what helps isolate sound and prevent it from escaping your listening space.


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## Mpoes12

TechEnthusiast said:


> Would GG between two layers of drywall mitigate low-frequency sounds (e.g., 20 Hz)? Would nailing/screwing be required?
> 
> 
> 
> 
> I appreciate your informative reply.
> 
> Single stud walls. First floor. The interior walls/ceiling/flooring aren't decoupled from the home's structure. Dimensions: L = 9.2 Feet / W = 6 Feet / H = 8 Feet.
> 
> I suppose that in addition to the other products I mentioned (excluding MLV or Peacemaker), I'll use a viscoelastic material (i.e., GG) in between the drywall layers. I'm notably interested in installing that STC 71 configuration: 2x 5/8" Drywall + GG + IB-1 Clips | 2x 5/8" Drywall + GG. However, my primary concern is whether I can do it by myself. I've never done anything like this. Perhaps I could hire someone to do this for me? If so, how much do you think it'll cost? Are there even better (yet still affordable) configurations?



Adding green glue and another layer of drywall will increase transmission loss in the low frequencies, but probably not at 20hz. If it did, it would be minor. The reason is because you are now operating below the critical frequency of the wall structure. At that point mass and damping are unimportant, only stiffness matters. If the CLD process is working correctly, the wall structure won't be much if any stiffer than it was solely because of the GG. Reality is, in a house using normal building methods, it would be nearly impossible to effectively stop very low frequencies from transmitting out of the room. Having said that, its also likely that the frequency of the sounds that are transmitting out of the room are not 20hz. Remember, we can't hear 20hz all that well, most men would need it to be very loud to hear clearly and most women effectively can't hear it. If people are "hearing" bass coming from the theater, then you probably are dealing with something that is more between 30hz and 100hz. In that case, it is likely that the extra layer of drywall and GG could make a noticeable difference. You can add a third layer even and the result is even greater.


Yes you need to screw the drywall. The GG is sticky but I wouldn't have that much faith in it. The screws don't short circuit the wall, tests have shown that the screws have little to no effect.


Keep in mind that once a wall's STC rating starts to get out of the 40's the flanking paths and little mistakes that compromise transmission loss become ever greater risks. You won't get an STC 71 wall even if you follow that structure, it will be incrementally less. In situ testing of an STC 71 wall would likely yield something in the lower 60's even if you did a perfect job. In general the in situ standard is a good 10 points less than the lab standard. Once you add in things like doors, windows, outlets, and any other penetration, the value drops further. The point being, don't kill yourself trying to achieve a super high STC value. If you plan to go through the effort of that STC71 wall, make sure you are also handling all flanking paths as perfectly as possible. Also, you said your room is already a room within a room but then just noted single stud walls? That doesn't sound like a room within a room. I would need to know more about exactly what you have at this point? If the stud walls aren't decoupled you really need to tear down the drywall and isolate the stud walls from the ceiling. You would then need to install clips and hat channel.


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## Mpoes12

I personally think using OSB as the first layer of a room should be avoided. I believe it will actually reduce the STC value in the critical upper bass and midrange as compared with drywall alone. OSB is far stiffer than drywall. When coupled to drywall with greenglue it should make the sandwich structure stiffer. That stiffness could be good for LF containment but it would raise the critical frequency and still not be that stiff. You want to typically have the widest possible span for the mass controlled region which means lowering the critical frequency as much as possible. That is achieved by adding mass without adding stiffness. 

I haven't seen enough test data comparisons to feel like we know with any certainty and the issue would be minor at best. However if I'm right and it's harder to work with then what's the point. 

Just as anther point. Most people use 1/2" OSB and 5/8" drywall. In that scenario the OSB is about 10-12lbs lighter so you lowered the mass and increased the stiffness. Both are potentially bad for transmission loss. Like I said earlier, this would actually have benefit in the very low frequencies (say 30hz and below, but by that point you are typically seeing TL values in the terms anyway. That sudden dip in the low end of an STC graph is the critical frequency. You don't want to raise that unless the structure only operates below the critical frequency. 


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## HT Geek

deewan said:


> ... I wasn't sure how much sound would get into the pipe through my 'soundproof shell' of a room and then into the pipe and if that would cause my any concern. Sounds like I don't have to worry and wrapping some unface insulation around it will be good enough.


Keep it 'fluffy' (loose) around them, just like you'd insulate a ceiling on your home's upper floor. 




> My reasoning for the OSB layer is the ability to stick a nail/screw anywhere. I'm doing all the labor myself so the cost for labor is not an factor.


That was my thinking too, but it doesn't work as well in practice, unfortunately. If you still have concerns about sticking screws/nails wherever, I'd suggest using plywood instead of OSB. I've found OSB doesn't hold screws as well as plywood. The downside to that approach is cost as you should use sanded plywood sheets (otherwise you're going to get small air gaps that will be counterproductive to soundproofing).




> In my theater I plan on having acoustically transparent splayed walls and ceiling. Strange term, I know so let me explain. I hope to build a soundproof shell of a room suing clips, channel, green glue and two layers of something for walls. Inside that shell, I will build some type of wall skeleton for acoustically transparent fabric to cover and create a splayed wall feel. I realize this defeats the purpose of splayed walls, but I'm going for the look not the sonic benefits of splayed walls. Any sound treatments will be hidden behind the AT splayed walls and ceiling. This also allows me to save a lot of time by not needing to properly tape, mud, sand and paint walls.


Nothing wrong with that. I did the same thing. I started finishing my walls and realized why was I making extra work for myself when I was planning to cover them anyway???




> So, to sum it up, I'd like to be able to attach the splayed frames anywhere along my walls or ceiling without having to worry about hitting channel or the drywall supporting the weight. As of right now I plan on having my surround and overhead speakers exposed in the room, not hidden within backer boxes. So this are also things I'd like to know I can put almost anywhere without having to worry about channel.
> 
> But you have given me some pause to if I should create backer boxes and use two layers of drywall instead. I'll give it some thought.


Sounds like backer boxes won't work for your splayed walls. May work for your Atmos.

Why are you planning to splay the walls? What is the problem solved?


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## HT Geek

Mpoes12 said:


> I haven't seen enough test data comparisons to feel like we know with any certainty and the issue would be minor at best.


PAC International conducted several tests substituting plywood instead of drywall in 2006. Unfortunately, none of them are identical to the scenario we're discussing. That said, one of the tests - which substituted plywood on both sides of the wall lowered the STC of an insulated wall by 4 points compared with a normal drywall/drywall stud wall (from 40 down to 36) - seems to corroborate @Mpoes12 theory. 




> Most people use 1/2" OSB and 5/8" drywall.


I have to admit my knowledge of these issues is much greater now versus when I began building my room, and it's another reason I would not do an OSB layer with my next room. In my case, I used the same thickness OSB as my drywall (5/8"), but I have no reason to believe that will make a difference versus 1/2" thick or whatever. I used it for consistency and because 1/2" seemed a bit thin to me at the time for screw holding power (I recall looking at shear force charts for OSB, but I don't recall how big of a difference there was from 1/2").

That said, it is an unknown factor. None of the tests PAC paid for (performed by Western Electro labs) tested the concept of the plywood hanging off the RSIC clips. They tested basically every combo except that. The tests - including the results I referenced above - were single stud walls where the plywood stiffened one side or the other, or both sides of the wall. In my room's case the OSB is stiffening the inner wall of a double stud room. It remains to be seen how it impacts my wall resonance and overall soundproofing results.


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## Mpoes12

HT Geek said:


> PAC International conducted several tests substituting plywood instead of drywall in 2006. Unfortunately, none of them are identical to the scenario we're discussing. That said, one of the tests - which substituted plywood on both sides of the wall lowered the STC of an insulated wall by 4 points compared with a normal drywall/drywall stud wall (from 40 down to 36) - seems to corroborate @Mpoes12 theory.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have to admit my knowledge of these issues is much greater now versus when I began building my room, and it's another reason I would not do an OSB layer with my next room. In my case, I used the same thickness OSB as my drywall (5/8"), but I have no reason to believe that will make a difference versus 1/2" thick or whatever. I used it for consistency and because 1/2" seemed a bit thin to me at the time for screw holding power (I recall looking at shear force charts for OSB, but I don't recall how big of a difference there was from 1/2").
> 
> 
> 
> That said, it is an unknown factor. None of the tests PAC paid for (performed by Western Electro labs) tested the concept of the plywood hanging off the RSIC clips. They tested basically every combo except that. The tests - including the results I referenced above - were single stud walls where the plywood stiffened one side or the other, or both sides of the wall. In my room's case the OSB is stiffening the inner wall of a double stud room. It remains to be seen how it impacts my wall resonance and overall soundproofing results.




That's good to know. I had read some test data on OSB and wonder if it came from PAC. I have a piece of Marine grade plywood in my ceiling for the projector. I obviously don't think it's such a big issue to avoid at all costs. I think it probably makes things slightly worse, but adds cost and complexity. Hence I think it should be avoided where possible. Sometimes it's necessary and that's ok. I just don't understand when folks actually make a point of doing it on every surface and go so far as to claim they did it for superior soundproofing. 


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## TechEnthusiast

deewan said:


> I'm fairly certain what you had planned on doing would have little impact on keep sound and low frequency sound inside your room.
> 
> Sounds like your describing a closet as a room within a room. This is the best picture explanation I can find on short notice of a room within a room. The space on the right is a room within a room. There is a structure wall and inside of that, decoupled from the structural wall, is another set of walls creating the inner room.
> 
> The double, decoupled walls is what helps isolate sound and prevent it from escaping your listening space.


Indeed. My original plan would have had little effect on sounds entering and leaving the room. 

You're correct. It's a small storage room at the center of my home.

Thank you for the clarification. I now have a better understanding of what a "room within a room" means.



Mpoes12 said:


> Adding green glue and another layer of drywall will increase transmission loss in the low frequencies, but probably not at 20hz. If it did, it would be minor.
> 
> Remember, we can't hear 20hz all that well, most men would need it to be very loud to hear clearly and most women effectively can't hear it. If people are "hearing" bass coming from the theater, then you probably are dealing with something that is more between 30hz and 100hz. In that case, it is likely that the extra layer of drywall and GG could make a noticeable difference. You can add a third layer even and the result is even greater.
> 
> Keep in mind that once a wall's STC rating starts to get out of the 40's the flanking paths and little mistakes that compromise transmission loss become ever greater risks. You won't get an STC 71 wall even if you follow that structure, it will be incrementally less.
> 
> The point being, don't kill yourself trying to achieve a super high STC value. If you plan to go through the effort of that STC71 wall, make sure you are also handling all flanking paths as perfectly as possible. Also, you said your room is already a room within a room but then just noted single stud walls? That doesn't sound like a room within a room. I would need to know more about exactly what you have at this point? If the stud walls aren't decoupled you really need to tear down the drywall and isolate the stud walls from the ceiling. You would then need to install clips and hat channel.


You and Deewan are correct. Turns out I didn't know the real definition of "room within a room." To be clear, it's a simple storage room at the center of my home.

If I were to tear down the drywall and isolate the stud walls from the ceiling as well as install clips and a hat channel, I suspect that I might still need to do a lot more. The cars, trains, and airplanes are quite loud. Perhaps I should just move and build another home from scratch? On the other hand, how about sound isolation booths/enclosures (e.g., WhisperRoom, VocalBooth, StudioBricks)?

What's highly problematic is the feeling that most low frequency sounds produce. Would GG and three (or four) layers of drywall make a noticeable difference in terms of mitigating the physical sensations generated by low frequency sounds as well as reducing those in the mid- and high-frequency range?

So far I have scrapped my original idea. I am also deterred by the prospect of tearing down walls and installing layers of drywall. No guarantee that it'll work...or be done correctly.


----------



## Mpoes12

TechEnthusiast said:


> Indeed. My original plan would have had little effect on sounds entering and leaving the room.
> 
> You're correct. It's a small storage room at the center of my home.
> 
> Thank you for the clarification. I now have a better understanding of what a "room within a room" means.
> 
> 
> 
> You and Deewan are correct. Turns out I didn't know the real definition of "room within a room." To be clear, it's a simple storage room at the center of my home.
> 
> If I were to tear down the drywall and isolate the stud walls from the ceiling as well as install clips and a hat channel, I suspect that I might still need to do a lot more. The cars, trains, and airplanes are quite loud. Perhaps I should just move and build another home from scratch? On the other hand, how about sound isolation booths/enclosures (e.g., WhisperRoom, VocalBooth, StudioBricks)?
> 
> What's highly problematic is the feeling that most low frequency sounds produce. Would GG and three (or four) layers of drywall make a noticeable difference in terms of mitigating the physical sensations generated by low frequency sounds as well as reducing those in the mid- and high-frequency range?
> 
> So far I have scrapped my original idea. I am also deterred by the prospect of tearing down walls and installing layers of drywall. No guarantee that it'll work...or be done correctly.



I wouldn't be so deterred. If you tear down the drywall and add clips and hat channel, then layer on drywall and green glue, it WILL noticeably reduce the sound leakage. Even if you did a bad job, you would have to so significantly screw up for it to not be noticeable. The mistakes you (and all of us) make would minor in absolute terms, they are only significant in a value way. You put a lot of time and money into sound isolation, you don't want silly mistakes to cost you precious STC points. Remember that STC is a kind of weighted average of the transmission loss, in DB's, over a specified frequency range. That isn't an intuitive concept, but db's and volume is. If your mistakes lead to a penalty of 3db's at 1khz, well, let's be realistic, that is noticeable but not huge. 


The mass and the CLD will help dissipate some of the energy, so its not for nothing. I would need to know a lot more about your theater equipment, subwoofers, and house construction to fully answer your questions. Vibrations travel through solids readily (as does sound). In many homes, the floor has joists that connect multiple rooms together (running most or all of the length of a span of the house). For example, the kitchen and living room in my house are on the same set of joists, as is half of the dining room. The dining room is completely separated from the kitchen and living room. Further, the joists are connected to the next "group" and could transfer that energy. As such, the interconnectedness of the floor allows vibrations produced in one area to travel throughout the first floor. Thankfully, energy is "shed" as it travels as a result of friction. The vibrations dissipate over time as they travel farther out, they also spread in a circular arc and so the inverse square law states that for a doubling in distance, energy is 1/4th. There are things that can make that not true, but lets just pretend like it is. What that means for you is that if you are feeling the vibrations intensely, even a fully soundproof room may not have fully isolated all paths for sound and energy to travel, and so you may still feel the bass. 


Before going down this road, I would consider a few things. First, you may need to decouple your floor. A cheap starting point may be to try decoupling the subwoofers from the floor to see if that helps. If it does, then you need to decouple your entire media rooms floor. Second, that you may want to consider heavy duty soundproofing since your concern is primarily bass. That is by far the hardest area to address, so consulting experts can be helpful. In general though, the best LF isolation is possible when your airgap is large, your wall mass is great, damping is high, and the outershell is stiff. This has the best potential to "contain" lf energy. 


p.s. look up decoupled floor. If ripping drywall down scared you, that will be worse. Again, its not as bad as it seems. 


P.P.S. even with new construction the effort to do this is significant and fairly expensive. Most houses aren't built for soundproofing.


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## HT Geek

TechEnthusiast said:


> Single stud walls. First floor. The interior walls/ceiling/flooring aren't decoupled from the home's structure. Dimensions: L = 9.2 Feet / W = 6 Feet / H = 8 Feet.


Are you expecting your finished space of a room-within-a-room to be contained within that area? You'll lose around 6-12" along both the X and Y axes, depending on the method you choose.



> Perhaps I could hire someone to do this for me? If so, how much do you think it'll cost? Are there even better (yet still affordable) configurations?


National average is ~$1.50 psf for drywall. That includes acquiring product, delivering to jobsite, installation, mud and finish. Slapping up the inner layers and caulking them should be more like $1.00-$1.25 psf.




> The cars, trains, and airplanes are quite loud. Perhaps I should just move and build another home from scratch?


There are ways to deal with that successfully. The main problem I see atm is lack of sufficient space for even a small room.



> What's highly problematic is the feeling that most low frequency sounds produce. Would GG and three (or four) layers of drywall make a noticeable difference in terms of mitigating the physical sensations generated by low frequency sounds as well as reducing those in the mid- and high-frequency range?


Yes. More mass will help. However, for best results it should be done in conjunction with decoupling.


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## doveman

Mpoes12 said:


> I couldn't keep up with all the back and forth but as for this discussion of caulking and mass. The gap should and usually is very small. As HTGeek pointed out, a surprising amount of sound can get through a crevice. You want to avoid having the wall sitting right on the floor and the floor sitting right against the wall. It helps decouple them from each other. That gap should be filled with caulk. Typically this gap is tiny so the loss of mass is minor.
> 
> I too made a big deal about this. I was really worried. All the pros and everything was reading said don't worry and just caulk. I can honestly say my end product bore our that advice. Just don't lose sleep over it. The issue is minor.
> 
> In fact many people have far greater problems with their door frames, hvac, etc in this regard.


Yeah, I figured it couldn't really be an issue as it's standard practice to caulk the perimeter gap, I was just trying to understand why low-mass caulk in this gap is OK when the rest of the floor needs to be high-mass.

You're right though, I should just accept it's not an issue and move on.

So, onto my next problem. On my window wall, shown in the attached photos, once I've fitted the clips+channel+DD the inner wall will be about 60mm off the structural wall, leaving an open gap running around all four sides of the window reveal. How would I seal those gaps off? Just stick a piece of wood over them, glued to the edge of the drywall and caulked at the structural wall?

I'll also need to be able to seal off the window when I need the room soundproofed. I can't see that it would make any sense to fit clips+channel+DD within the reveal and I couldn't do that on the window sill anyway. Fitting secondary glazing might be sufficient to stop sound getting in from outside (and vice-versa) but the frame will be secured/coupled to the reveal (i.e. the structural wall) and will only be plastic, so I don't think that would do much to block sound entering/escaping that part of the wall. In addition, I only ever open the right-hand window so I'd only get secondary glazing that had an opening panel there too but that would still allow dirt to get onto the other panes whilst leaving me unable to reach them to clean them.

So what I thought might be better is to have wooden shutters that are attached by hinges to the inner wall and close over the reveal, thus blocking sound going to/from outside and also to/from the reveal. They'd need something to close against, so I'd install two vertical wooden pillars between the sill and the top of the reveal just within either side of the central pane of glass and fit weather strip to the pillars and the shutters to form a seal and keep the shutters and pillars decoupled. I'd have a single shutter on the right side that just covered the right-hand pane and on the left I'd have a two-piece shutter, hinged in the middle, that covers the other two-thirds of the window. Does that make sense? I realise the electric outlet needs to be moved to the left-hand wall to provide room for the shutters (well I guess I could just move it down a bit but I don't like it on that wall anyway).

As this wall has to hold the radiator, which is rather heavy when full of water, plus a curtain rail above the window, plus the wooden shutters and an interior door to seal off the balcony door (which I'll discuss in another post), I think I'll have to use ply for the first layer. Even then, will that plus extra clips in the radiator area be sufficient to hold its weight?


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## veger69

I have a window wall in my theater room that I'm planning on building some 2x4 frames to plug the windows. I want something that breathes so no mold. I'm thinking covered with black felt or something similar. If you know a source for felt or similar material that will work I'll take suggestions. I'm planning on putting Roxul safe and sound in the frames because they are behind my main speakers although if you think another material would work better I'm take suggestions. Here is the wall

















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## ScottieBoysName

Anyone have any good suggestions for sound proofing doors that lead to a dedicated media room? My media room will have two french doors leading to it..that I'll probably have "upgraded" to solid-core doors. I'd imagine that would help, that will make them heavier and a lot more solid like a block of wood. Could I just run some foam around the edges of the doorway to create a tight seal when they close....and to prevent them from rattling?


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## HT Geek

doveman said:


> So, onto my next problem. On my window wall, shown in the attached photos, once I've fitted the clips+channel+DD the inner wall will be about 60mm off the structural wall, leaving an open gap running around all four sides of the window reveal. How would I seal those gaps off? Just stick a piece of wood over them, glued to the edge of the drywall and caulked at the structural wall?


The only thing special you need to do around a window like that is make sure you have sufficient clips. You'll apply the drywall/plaster sheets as normal on the hat channel. The hat channels will span across your window opening, so you'll have something to adhere the plaster sheets to. Before installing the hat channel, you should plug the window. Note that it is possible to not run hat channels across it. For instance, if you feel the need to be able to access the window area from inside your home, you could use an alternative method. The recommended route is drywall over it, so you can complete your room's shell. 

There are a few threads on AVS regarding window plugs. How you plug it and what you use will depend in part on whether or not you may need to access it in the future from the inside. I've used combinations of plywood, MDF, and various forms of thick insulation, depending on what type of window it was.




> I'll also need to be able to seal off the window when I need the room soundproofed. I can't see that it would make any sense to fit clips+channel+DD within the reveal and I couldn't do that on the window sill anyway. Fitting secondary glazing might be sufficient to stop sound getting in from outside (and vice-versa) but the frame will be secured/coupled to the reveal (i.e. the structural wall) and will only be plastic, so I don't think that would do much to block sound entering/escaping that part of the wall. In addition, I only ever open the right-hand window so I'd only get secondary glazing that had an opening panel there too but that would still allow dirt to get onto the other panes whilst leaving me unable to reach them to clean them.


Your best bet - from a sound proofing perspective - is to plug the window and seal it off as I described above. You could make a removable window plug. It will likely cause some sound leakage, but it's an option if that is more important to you versus sound proofing. Your windows will still be accessible and cleanable, etc. from the exterior. Many members on AVS have plugged and sealed off windows in their rooms and never had issues with the window, selling their home, etc.



> So what I thought might be better is to have wooden shutters that are attached by hinges to the inner wall and close over the reveal, thus blocking sound going to/from outside and also to/from the reveal. They'd need something to close against, so I'd install two vertical wooden pillars between the sill and the top of the reveal just within either side of the central pane of glass and fit weather strip to the pillars and the shutters to form a seal and keep the shutters and pillars decoupled. I'd have a single shutter on the right side that just covered the right-hand pane and on the left I'd have a two-piece shutter, hinged in the middle, that covers the other two-thirds of the window. Does that make sense?


Naturally, you can do whatever you like. It all boils down to compromises of performance vs. features.




> As this wall has to hold the radiator, which is rather heavy when full of water, plus a curtain rail above the window, plus the wooden shutters and an interior door to seal off the balcony door (which I'll discuss in another post), I think I'll have to use ply for the first layer. Even then, will that plus extra clips in the radiator area be sufficient to hold its weight?


Most clips are rated around 36 lbs. per clip. There are some heavy duty versions with higher ratings. Be sure to consult the manufacturer's specifications on maximum weight of any given product, so you know for sure. The pro and con of plywood is it increases the rigidity of a wall. It also makes hanging stuff a bit easier. Unfortunately, it turns out that plywood also reduces your sound proofing performance. Plywood doesn't absorb as well as drywall, and the few studies on the subject indicate it's less effective to use plywood+drywall (for instance) versus 2x drywall. Expect to lose up to 4 STC in performance. Again, it's a function of priorities.

Wouldn't your radiator have most of its weight on the floor?


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## HT Geek

veger69 said:


> I have a window wall in my theater room that I'm planning on building some 2x4 frames to plug the windows. I want something that breathes so no mold. I'm thinking covered with black felt or something similar. If you know a source for felt or similar material that will work I'll take suggestions. I'm planning on putting Roxul safe and sound in the frames because they are behind my main speakers although if you think another material would work better I'm take suggestions.





doveman said:


> On my window wall, shown in the attached photos, once I've fitted the clips+channel+DD the inner wall will be about 60mm off the structural wall, leaving an open gap running around all four sides of the window reveal. How would I seal those gaps off? Just stick a piece of wood over them, glued to the edge of the drywall and caulked at the structural wall?


Just want to clarify for you both.... There should be a gap between your inner (shell) wall and your outer (structural) wall for a room-within-a-room configuration, where your windows are. You want the walls to be de-coupled everywhere. You should loosely (but thoroughly) stuff the gap around the window edges with insulation, to meet building code requirements on air cavities within a wall. That way, if the window is penetrated somehow when your build is complete, you won't have a draft source going behind your inner wall, which could act as a chimney in the event of a fire.

Roxul products or solid fiberglass solutions such as OC703/705 are your best bet if mold is also a concern (none of those will promote mold growth). I have seen mold on standard fiberglass insulation.

@veger69, you raised another good point, which is to be cognizant of how your window plug(s) will appear from the outside. 

In my case, my wife wanted a white appearance, so I used a opaque but translucent film over the inside of my windows. I then applied a white spray-painted piece of plywood as a backer up against the glass (well, small gap actually), then I stuffed about 6" of Roxul, then a MDF backer on the room side. Seams sealed. More insulation on the room side. Done.


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## HT Geek

ScottieBoysName said:


> Anyone have any good suggestions for sound proofing doors that lead to a dedicated media room? My media room will have two french doors leading to it..that I'll probably have "upgraded" to solid-core doors. I'd imagine that would help, that will make them heavier and a lot more solid like a block of wood. Could I just run some foam around the edges of the doorway to create a tight seal when they close....and to prevent them from rattling?



Get rid of your french doors
Replace with a heavy solid core door or exterior door up to 36" wide, 1-3/4" or more thick
Install an automatic door bottom, and corresponding neoprene door stops

The problem with french doors is you'll never get a good seal on them. 

If you MUST retain french doors, replace the door portions with solid core - as heavy and thick as your situation can accommodate. Note that thicker, heavier doors may require new hinges. Examine your doors to see if it's feasible to install neoprene on one or both insides of the doors where they meet, so when they close the neoprene smushes the doors tighter together. Get a rubber or neoprene strip to run down the middle of the door so when they're closed it seals the crack. You won't be able to use an automatic door bottom effectively with a french door. As an alternative, look at high quality door sweeps you could install on the inside of the doors. You might want to hire a carpenter, to make sure it all aligns properly.

None of what I've just described relative to keeping your french doors will be ideal, and I don't recommend that route. You might be better off getting a cheap draft stopper to throw down when playing your system loud and calling it a day, and just accept the fact those doors are going to leak sound like a sieve.


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## veger69

HT Geek said:


> Just want to clarify for you both.... There should be a gap between your inner (shell) wall and your outer (structural) wall for a room-within-a-room configuration, where your windows are. You want the walls to be de-coupled everywhere. You should loosely (but thoroughly) stuff the gap around the window edges with insulation, to meet building code requirements on air cavities within a wall. That way, if the window is penetrated somehow when your build is complete, you won't have a draft source going behind your inner wall, which could act as a chimney in the event of a fire.
> 
> 
> 
> Roxul products or solid fiberglass solutions such as OC703/705 are your best bet if mold is also a concern (none of those will promote mold growth). I have seen mold on standard fiberglass insulation.
> 
> 
> 
> @veger69, you raised another good point, which is to be cognizant of how your window plug(s) will appear from the outside.
> 
> 
> 
> In my case, my wife wanted a white appearance, so I used a opaque but translucent film over the inside of my windows. I then applied a white spray-painted piece of plywood as a backer up against the glass (well, small gap actually), then I stuffed about 6" of Roxul, then a MDF backer on the room side. Seams sealed. More insulation on the room side. Done.




I'm going to go with the color scheme shown in the attached pic so probably go with cream color cloth










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## ScottieBoysName

HT Geek said:


> Get rid of your french doors
> 
> Replace with a heavy solid core door or exterior door up to 36" wide, 1-3/4" or more thick
> 
> Install an automatic door bottom, and corresponding neoprene door stops
> 
> 
> 
> 
> The problem with french doors is you'll never get a good seal on them.
> 
> 
> 
> If you MUST retain french doors, replace the door portions with solid core - as heavy and thick as your situation can accommodate. Note that thicker, heavier doors may require new hinges. Examine your doors to see if it's feasible to install neoprene on one or both insides of the doors where they meet, so when they close the neoprene smushes the doors tighter together. Get a rubber or neoprene strip to run down the middle of the door so when they're closed it seals the crack. You won't be able to use an automatic door bottom effectively with a french door. As an alternative, look at high quality door sweeps you could install on the inside of the doors. You might want to hire a carpenter, to make sure it all aligns properly.
> 
> 
> 
> None of what I've just described relative to keeping your french doors will be ideal, and I don't recommend that route. You might be better off getting a cheap draft stopper to throw down when playing your system loud and calling it a day, and just accept the fact those doors are going to leak sound like a sieve.




That’s kinda what I was afraid of. The main issue is that the opening to the media room is large enough to require the French doors, so really the only thing I COULD do is put in exterior French doors there. 

The automatic door bottom...even if I could put a single door there and do that....how would that work on carpet?


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## ScottieBoysName

HT Geek said:


> Get rid of your french doors
> 
> Replace with a heavy solid core door or exterior door up to 36" wide, 1-3/4" or more thick
> 
> Install an automatic door bottom, and corresponding neoprene door stops
> 
> 
> 
> 
> The problem with french doors is you'll never get a good seal on them.
> 
> 
> 
> If you MUST retain french doors, replace the door portions with solid core - as heavy and thick as your situation can accommodate. Note that thicker, heavier doors may require new hinges. Examine your doors to see if it's feasible to install neoprene on one or both insides of the doors where they meet, so when they close the neoprene smushes the doors tighter together. Get a rubber or neoprene strip to run down the middle of the door so when they're closed it seals the crack. You won't be able to use an automatic door bottom effectively with a french door. As an alternative, look at high quality door sweeps you could install on the inside of the doors. You might want to hire a carpenter, to make sure it all aligns properly.
> 
> 
> 
> None of what I've just described relative to keeping your french doors will be ideal, and I don't recommend that route. You might be better off getting a cheap draft stopper to throw down when playing your system loud and calling it a day, and just accept the fact those doors are going to leak sound like a sieve.



That’s kinda what I was afraid of. The main issue is that the opening to the media room is large enough to require the French doors, so really the only thing I COULD do is put in exterior French doors there. 

The automatic door bottom...even if I could put a single door there and do that....how would that work on carpet?



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## HT Geek

ScottieBoysName said:


> That’s kinda what I was afraid of. The main issue is that the opening to the media room is large enough to require the French doors, so really the only thing I COULD do is put in exterior French doors there.
> 
> The automatic door bottom...even if I could put a single door there and do that....how would that work on carpet?
> 
> 
> Sent from my iPhone using Tapatalk Pro


You'd have to frame it out and close off part of it. Can be done.

The auto door bottom will work on carpet. Not as effective as a hard surface, but it can be done and should be better than not having one.

It's all relative though; to your budget, goals, and expectations. May not be worth the effort.


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## ScottieBoysName

HT Geek said:


> You'd have to frame it out and close off part of it. Can be done.
> 
> The auto door bottom will work on carpet. Not as effective as a hard surface, but it can be done and should be better than not having one.
> 
> It's all relative though; to your budget, goals, and expectations. May not be worth the effort.
> 
> 
> Sent from my ONE A2005 using Tapatalk




Yeah, you’re right. We’re building the house now, and I can’t deviate much from the set plans. I can ask though. What’s the widest single door you can put in a house? Didn’t you say 36 inches?


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## doveman

HT Geek said:


> Your best bet - from a sound proofing perspective - is to plug the window and seal it off as I described above. You could make a removable window plug. It will likely cause some sound leakage, but it's an option if that is more important to you versus sound proofing. Your windows will still be accessible and cleanable, etc. from the exterior. Many members on AVS have plugged and sealed off windows in their rooms and never had issues with the window, selling their home, etc.
> 
> Naturally, you can do whatever you like. It all boils down to compromises of performance vs. features.


I can't plug the windows as I need to be able to see out of the window and let light and air in for most of the day when I'm not making noise or wanting piece and quiet from outside noise. So hinged shutters are the only option I can think of that will provide a reasonable amount of sound proofing over the windows whilst being easy to open and close. The soundproofing on the walls should pretty much address the noise to/from the neighbouring flats, with the exception of those areas where it ends at the window reveal, hence why I suggested maybe sealing off those ends with wood might be required.



> Just want to clarify for you both.... There should be a gap between your inner (shell) wall and your outer (structural) wall for a room-within-a-room configuration, where your windows are. You want the walls to be de-coupled everywhere. You should loosely (but thoroughly) stuff the gap around the window edges with insulation, to meet building code requirements on air cavities within a wall. That way, if the window is penetrated somehow when your build is complete, you won't have a draft source going behind your inner wall, which could act as a chimney in the event of a fire.
> 
> Roxul products or solid fiberglass solutions such as OC703/705 are your best bet if mold is also a concern (none of those will promote mold growth). I have seen mold on standard fiberglass insulation.


There will be a gap between the inner and outer walls of about 30mm created by the clips+channel and I will fit 25mm insulation in this gap, all the way up to the point where the end of the wall and the window reveal meet but even so I think I need to close off those ends with wood or something to stop noise being able to get in via the gap when the window shutters are open. Of course, if there's no soundproofing on the reveal itself then it might not really matter if those ends are left open from a soundproofing POV but it would still look better and avoid any fire safety issues. 

I may have sufficient clearance between the reveal and the edge of the windows to fit soundproofing on the reveal as well and I guess I could just use a clip at each end of the three sections (L, R and top) of the reveal as the drywall strips will be very narrow and thus not very heavy but I'd still have the wooden window sill, which is coupled to the structure, to deal with and I'm not sure how I could treat that.



> Most clips are rated around 36 lbs. per clip. There are some heavy duty versions with higher ratings. Be sure to consult the manufacturer's specifications on maximum weight of any given product, so you know for sure. The pro and con of plywood is it increases the rigidity of a wall. It also makes hanging stuff a bit easier. Unfortunately, it turns out that plywood also reduces your sound proofing performance. Plywood doesn't absorb as well as drywall, and the few studies on the subject indicate it's less effective to use plywood+drywall (for instance) versus 2x drywall. Expect to lose up to 4 STC in performance. Again, it's a function of priorities.


I understand that drywall is preferable from a soundproofing POV but the wall has to support the weight of the radiator, curtain rail, window shutters and balcony door/shutter so there's no choice.



> Wouldn't your radiator have most of its weight on the floor?


No, it's entirely hanging off the wall so none of its weight will be on the floor.


----------



## HT Geek

ScottieBoysName said:


> Yeah, you’re right. We’re building the house now, and I can’t deviate much from the set plans. I can ask though. What’s the widest single door you can put in a house? Didn’t you say 36 inches?


There are wider, but they'd be custom ($$$$). 36" is the widest standard interior door size.

If you're building from scratch, you may want to consider placing a wood threshold under the door, for the automatic door bottom to push down on. That would give you a better seal. Presuming there's carpet on either side, it's simple for the carpet installers to work around it. That's what I did for my HT room.


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## ScottieBoysName

HT Geek said:


> There are wider, but they'd be custom ($$$$). 36" is the widest standard interior door size.
> 
> If you're building from scratch, you may want to consider placing a wood threshold under the door, for the automatic door bottom to push down on. That would give you a better seal. Presuming there's carpet on either side, it's simple for the carpet installers to work around it. That's what I did for my HT room.


I know they MIGHT let me get away with swapping out the French for a single door (I just asked and they're going to get back to me), but the auto/doorstop I might have to do after I close on the home. Their big fear with letting me run wild, is that if I don't close on the house...they're stuck with something another home-owner might not want. 

If I can get them to swap the french doors for the single 36 inch door, I"ll start there. I'm HIGHLY certainly they won't let me install an exterior door frame with seals in it's place. 

In the even they don't do that....let's say they let me install a 36 inch solid core door. I can put foam around the door frame to seal it up as a starter, right?


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## HT Geek

doveman said:


> I can't plug the windows as I need to be able to see out of the window and let light and air in for most of the day when I'm not making noise or wanting piece and quiet from outside noise. So hinged shutters are the only option I can think of that will provide a reasonable amount of sound proofing over the windows whilst being easy to open and close. The soundproofing on the walls should pretty much address the noise to/from the neighbouring flats, with the exception of those areas where it ends at the window reveal, hence why I suggested maybe sealing off those ends with wood might be required....
> 
> There will be a gap between the inner and outer walls of about 30mm created by the clips+channel and I will fit 25mm insulation in this gap, all the way up to the point where the end of the wall and the window reveal meet but even so I think I need to close off those ends with wood or something to stop noise being able to get in via the gap when the window shutters are open. Of course, if there's no soundproofing on the reveal itself then it might not really matter if those ends are left open from a soundproofing POV but it would still look better and avoid any fire safety issues.


You could still do removable window plugs. Shutters will be not-so-good from a sound proofing perspective. Sounds as if it boils down to form vs. function and your priorities.

If thick enough, it's possible your plugs could be engineered to fill the gap between the inner and outer walls in the reveal. You'd still need to draft stop it per U.S. building codes. Not sure about where you live, but something I'd suggest you investigate. If you must have a fire stop then your options will be limited and you'll have no choice but to recouple the inner/outer walls around the circumference of the window reveal.

I wouldn't be too concerned with sound leaking from the windows into the cavity between the inner and outer walls. That's going to be a minor issue as most of that will bounce around inside the wall cavity and get absorbed by the inner wall.




> I may have sufficient clearance between the reveal and the edge of the windows to fit soundproofing on the reveal as well and I guess I could just use a clip at each end of the three sections (L, R and top) of the reveal as the drywall strips will be very narrow and thus not very heavy but I'd still have the wooden window sill, which is coupled to the structure, to deal with and I'm not sure how I could treat that.


I'm not totally following the mental picture there, but will say I was wondering if your interior window sill is going to protrude further than 30mm, and if so if it might be an additional challenge in constructing your inner wall. You could consider trimming its depth if that is the case.


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## HT Geek

ScottieBoysName said:


> I know they MIGHT let me get away with swapping out the French for a single door (I just asked and they're going to get back to me), but the auto/doorstop I might have to do after I close on the home. Their big fear with letting me run wild, is that if I don't close on the house...they're stuck with something another home-owner might not want.
> 
> If I can get them to swap the french doors for the single 36 inch door, I"ll start there. I'm HIGHLY certainly they won't let me install an exterior door frame with seals in it's place.
> 
> In the even they don't do that....let's say they let me install a 36 inch solid core door. I can put foam around the door frame to seal it up as a starter, right?


You could simply replace the stock door stops with stops that include a neoprene seal. It would be best to install them at the same time as the automatic door stop. 

If you decide to install a hardwood threshold at the same time, it's a simple modification for a carpet installer to make the cut, install the threshold, and then re-stretch and tack the carpet in place. Make sure they use a z-bar (prevents you from stepping on nails in the tack strip next to the threshold).


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## ScottieBoysName

HT Geek said:


> You could simply replace the stock door stops with stops that include a neoprene seal. It would be best to install them at the same time as the automatic door stop.
> 
> If you decide to install a hardwood threshold at the same time, it's a simple modification for a carpet installer to make the cut, install the threshold, and then re-stretch and tack the carpet in place. Make sure they use a z-bar (prevents you from stepping on nails in the tack strip next to the threshold).


Awesome. Thanks so much! I really appreciate it!


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## Mpoes12

ScottieBoysName said:


> That’s kinda what I was afraid of. The main issue is that the opening to the media room is large enough to require the French doors, so really the only thing I COULD do is put in exterior French doors there.
> 
> The automatic door bottom...even if I could put a single door there and do that....how would that work on carpet?
> 
> 
> Sent from my iPhone using Tapatalk Pro




Not all doors are created equal here. A lot of exterior doors are insulated. They have relatively low mass and poor sound blocking ability. You want a solid core. In addition there are some core materials being made of leftover agro products and they are actually not that dense. The doors need to be thick and heavy. 

If you need French doors then consider an acoustic door astragal. 

Something like this: https://acousticalsolutions.com/product/acoustic-double-door-astragals/

If you have the budget there are companies who can make high STC French doors in any style you can imagine. I believe they start around $3500 but that might be off. 

You can also make a good soundproof door. If I was doing this I would layer 5/8" MDF with GreenGlue. You would need to glue edge banding around the outside of the door and you would have to probably make a custom door frame. It's a lot of work but it would probably equal the commercial offerings for considerably less. 


Sent from my iPhone using Tapatalk


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## Mpoes12

ScottieBoysName said:


> Awesome. Thanks so much! I really appreciate it!




You also need to be sure they glue the threshold down. It needs to have an airtight seal or sound could leak under the threshold. I used acoustic caulk when I did mine. 


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## HT Geek

Mpoes12 said:


> You want a solid core....
> 
> If you need French doors then consider an acoustic door astragal.
> 
> Something like this: https://acousticalsolutions.com/product/acoustic-double-door-astragals/


Good points. The idea behind using an exterior door (as I'm certain you already know, but stating here FBO others), is related to 1) mass and 2) the seals. The idea is to get yourself a heavy door with thick seals. It used to be that fire-rated doors had lots of mass (material to slow down fire spread) and seals (to reduce the likelihood of oxygen permeating through the doors). Unfortunately (from a sound proofing perspective), that's not always true these days thanks to advances in building materials (advances from a non-sound deadening perspective).


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## Mpoes12

HT Geek said:


> Good points. The idea behind using an exterior door (as I'm certain you already know, but stating here FBO others), is related to 1) mass and 2) the seals. The idea is to get yourself a heavy door with thick seals. It used to be that fire-rated doors had lots of mass (material to slow down fire spread) and seals (to reduce the likelihood of oxygen permeating through the doors). Unfortunately (from a sound proofing perspective), that's not always true these days thanks to advances in building materials (advances from a non-sound deadening perspective).



Yes yes I spent a ton of time looking into all of this when I chose my doors. I looked at fireproof doors and those are still a great option. I found a handful that were fire rated and had stc data. The doors were in the low 40's, much better than the Average door. When I inquired on cost they were $800 each and did not include gaskets.

I looked at exterior doors, which often are rated with a different system for sound transmission., OITC. I found it very rare if ever that an exterior door had a better rating than an equivalent interior door. In addition many exterior doors are made with steel or fiberglass. While they often had decent transmission loss values they were no better than mdf core and in my opinion not a good option. The effect of the coincident frequency of both fiberglass and steel is very prominent. The core on most of these is polystyrene. 

I also didn't find the weight to be any higher on the slabs, or if it was, only a small amount. My slab alone weighed 160 lbs and the solid wood core exterior doors I checked were in that range. 

All that to say I question the wisdom of using exterior doors for soundproofing. I think their gasketing is an advantage, but otherwise I don't think they are a better option. I believe it's too easy for people to buy the wrong door and that even the best of them are no better than equivalent interior doors. If you look at Jeld-Wen you will find all their stc and oitc data. Their Procore doors are around stc 30. Their R series is actually 43 with gaskets. It's the highest I could find and much higher than any exterior door I could find. I could justify the cost of those doors and went with something from a Masonite company that had a rating of stc 32 I believe. Again, that was higher than the rating I could find on any exterior door. 

If you can find some readily available exterior doors with higher ratings please let me know. I'd love to be wrong in this as it opens up a lot of options. 


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## HT Geek

Makes sense. I used 2 solid core interior doors and glued & screwed them together w/Green Glue to make a door sandwich. I'd estimate it weighs around 200 lbs., maybe more. I had to jerry-rig a fulcrum to maneuver it after assembly due to its weight. It's a beast. The door is 32" wide.


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## ScottieBoysName

Mpoes12 said:


> Not all doors are created equal here. A lot of exterior doors are insulated. They have relatively low mass and poor sound blocking ability. You want a solid core. In addition there are some core materials being made of leftover agro products and they are actually not that dense. The doors need to be thick and heavy.
> 
> If you need French doors then consider an acoustic door astragal.
> 
> Something like this: https://acousticalsolutions.com/product/acoustic-double-door-astragals/
> 
> If you have the budget there are companies who can make high STC French doors in any style you can imagine. I believe they start around $3500 but that might be off.
> 
> You can also make a good soundproof door. If I was doing this I would layer 5/8" MDF with GreenGlue. You would need to glue edge banding around the outside of the door and you would have to probably make a custom door frame. It's a lot of work but it would probably equal the commercial offerings for considerably less.
> 
> 
> Sent from my iPhone using Tapatalk


Good news! They're going to let me replace the french doors with a single solid core door, 36 inches wide.  So, instead of two 24 inch french doors, I'll have a single solid core 36 inch door. So, I feel like that's a good starting point and way ahead of the french doors. I'm stoked! I've seen kits for $200-$300, that basically install on the door stop, and have adjustable neoprene seals for the door. They also have the automatic door bottoms as well. I was thinking in investing in one of those kits to start, and see how well that stands up with the solid core door.


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## ScottieBoysName

Mpoes12 said:


> You also need to be sure they glue the threshold down. It needs to have an airtight seal or sound could leak under the threshold. I used acoustic caulk when I did mine.
> 
> 
> Sent from my iPhone using Tapatalk


If I go that route, I certainly will. Threshold might not pass the wife test. Especially if it's metal looking or aluminum looking. Do they make any kind of decorative ones or something else I could do?


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## Mpoes12

ScottieBoysName said:


> If I go that route, I certainly will. Threshold might not pass the wife test. Especially if it's metal looking or aluminum looking. Do they make any kind of decorative ones or something else I could do?



Yes they make wooden thresholds. Commonly made of oak. I made my own from marine plywood and poplar. You can also make them from just a single piece of wood. With carpet it's best to have the door cut so it's just above the height of the carpet and for the threshold to come up to the door with as little clearance as possible. Remember houses shift so I would suggest a 1/4" rather than a 1/16". 

The Gasket sets you want to use are way overkill but they are easy to implement and certainly won't be the weak point. You can achieve the exact same level of soundproofing on a door like that with just neoprene or silicone gaskets and a lower end automatic door bottom. Having said all that, I wish I had bought the more expensive set as I think the door gaskets are a weak point in my setup. It isn't the gaskets themselves but he ability to align them with the door for even solid contact. You save some money if you like but there is a bit more work to get it all working right. 


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## ScottieBoysName

Mpoes12 said:


> Yes they make wooden thresholds. Commonly made of oak. I made my own from marine plywood and poplar. You can also make them from just a single piece of wood. With carpet it's best to have the door cut so it's just above the height of the carpet and for the threshold to come up to the door with as little clearance as possible. Remember houses shift so I would suggest a 1/4" rather than a 1/16".
> 
> The Gasket sets you want to use are way overkill but they are easy to implement and certainly won't be the weak point. You can achieve the exact same level of soundproofing on a door like that with just neoprene or silicone gaskets and a lower end automatic door bottom. Having said all that, I wish I had bought the more expensive set as I think the door gaskets are a weak point in my setup. It isn't the gaskets themselves but he ability to align them with the door for even solid contact. You save some money if you like but there is a bit more work to get it all working right.
> 
> 
> Sent from my iPhone using Tapatalk


All good points. I think I'd rather spend the $200-$300 to get those I linked, since they're adjustable and appear that I can make sure they make good contact. Know what I mean?

Any pictures of the wooden threshold?


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## Mpoes12

https://www.tmhardware.com/Seam-Binding-or-Wooden-Threshold-3.5-Oak-.5-Height.html

Pemko makes an oak threshold. 

Here is mine but remember I have communicating doors and a modern style dedicated theater.









You could just as easily stain that wood as paint it. I just wanted it to match the walls. 


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## doveman

HT Geek said:


> I wouldn't be too concerned with sound leaking from the windows into the cavity between the inner and outer walls. That's going to be a minor issue as most of that will bounce around inside the wall cavity and get absorbed by the inner wall.


It's not sound from the windows getting into the cavity that I'm concerned about, more the sound I'm making in my room being able to bypass the inner wall by getting into the cavity and from there into the outer wall (and vice-versa for the neighbour noise escaping from the outer wall into my room via the cavity). This won't be a problem when the shutters are closed, as the cavity will be behind them but if I seal the cavities off with some lengths of wood then hopefully it will prevent this even when the shutters are open.



> I'm not totally following the mental picture there, but will say I was wondering if your interior window sill is going to protrude further than 30mm, and if so if it might be an additional challenge in constructing your inner wall. You could consider trimming its depth if that is the case.


Hopefully the attached highly detailed(!) drawing will help illustrate my thinking. The red squares on the reveal are where the clips would go, with channel running between them and then one or two layers of drywall would sit 3cm off the reveal and extend from the window frame to the edge of the drywall that's mounted on the wall next to the window (I haven't shown any clips on this wall but obviously they'd be there). I'd do the same on the top and left side of the reveal.

As for the window sill, this currently extends about 3.5cm from the wall so I may well have to cut off (or at least cut back) the sections that extend either side of the window as they'd be in the way of the drywall, although maybe I could just cut the drywall around them and seal the gap with caulk and the mass of the wood in these small areas wouldn't undermine the soundproofing. As things stand, those parts of the sill aren't actually touching the wall as they just sit in front and the plaster has crumbled away, leaving a gap between the two (as you can probably see in the second photo) but I'll need to fill in the plaster to seal it before fitting the drywall.

For the part of the sill that's within the reveal, I could cut it back flush with the wall and then have the shutters close over it (they'd be decoupled from the sill by rubber, weatherstrip, or something). The problem with that is the drywall underneath the sill, where the radiator is, will extend up to about 6cm from the outer wall and people are liable to rest their weight on that drywall when going to open (or look out) the window. So the safer option is probably to screw a piece of wood to the sill to extend it out about 2.5cm so that it covers the drywall underneath and then seal the gap between the two with caulk. That way, people will only be able to lean on the sill rather than the drywall and their weight will be supported by the outer wall.

It's obviously not ideal having a piece of wood coupled to the outer wall extending past the shutters but compromises have to be made. I suppose I could use spacers on the side walls to bring the shutters out so that they close over the extended sill but I'm not sure it's worth it.


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## GatorBlues

HT Geek said:


> Zero International is the de-facto standard in ADB's. Their stops and headers are also very good. I've also heard good things about Reese, and mixed reviews on Pemko (though I believe the not-so-good reviews on Pemko were regarding rigid sealing material instead of spongy or flexible material that we'd want).
> 
> Zero's products are typically going to be 2x or more in cost versus the others.
> 
> Anything you buy from SPC or Trademark Soundproofing should be good. The latter will do custom sizes if you call them.


I've been reading up on trademark soundproofing's website, and it looks like they have several options for sealing around the door frames (in addition to the automatic door bottom). They have a teardrop seal that you apply to an existing door gasket, and then two options to replace the door gasket with their metal contraption that holds the rubber seal -- a standard and a heavy duty version. Does anyone have experience with these, or information about them, such that you can recommend whether it's worth the substantial cost increases to jump from teardrop to standard, or from standard to heavy duty? 

https://www.tmsoundproofing.com/Door-Soundproof-Gaskets.html

I also wonder the same thing about jumping from the standard to the heavy duty automatic door bottom, but the price increase for that upgrade isn't substantial the way it is with the door gaskets.


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## Mpoes12

GatorBlues said:


> I've been reading up on trademark soundproofing's website, and it looks like they have several options for sealing around the door frames (in addition to the automatic door bottom). They have a teardrop seal that you apply to an existing door gasket, and then two options to replace the door gasket with their metal contraption that holds the rubber seal -- a standard and a heavy duty version. Does anyone have experience with these, or information about them, such that you can recommend whether it's worth the substantial cost increases to jump from teardrop to standard, or from standard to heavy duty?
> 
> 
> 
> https://www.tmsoundproofing.com/Door-Soundproof-Gaskets.html
> 
> 
> 
> I also wonder the same thing about jumping from the standard to the heavy duty automatic door bottom, but the price increase for that upgrade isn't substantial the way it is with the door gaskets.




There is not going to be a sound isolation advantage between the two for the vast majority of people. Pemko has test data showing the loss in isolation compared to glued in place. You have to have a very high STC door to need either of the options compared to what basic silicone or neoprene stick on gaskets will give you. The advantage with these systems is that they are adjustable and so easy to align and get a good seal. 

I've seen test data on the transmission loss of plywood or MDF with green glue and the stc values of even that is far lower than you might hope. Basically the stc value of your door needs to be in the low 40's before there becomes a need for the lighter duty door gasket system. It needs to be well into the 50's before the heavy duty is needed. A normal solid core door is going to range from around stc20 to stc35. The most commonly available solid core doors are in the mid to upper 20's. 

In other words, buy what you like. There is no sound isolation advantage for you unless you are building a very soundproof wall with a very high STC door assembly. It's mostly going to be for ease of use and bragging rights. 


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## Mpoes12

I'll also say that having both a top end Zero door bottom and the equivalent from Pemko, quality is the same but I feel strongly the neoprene gasket on the pemko is better engineered. The Pemko also applies a bit more pressure to the floor which I like. Cost was very similar. 

Also all of those vendors charge retail. There are other sources that provide substantial discount but have a high minimum order. I paid about half retail on all my pemko products but had to spend $500. Thankfully two doors worth of hinges, gaskets, bottoms, and latches exceeded $500. 


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## GatorBlues

Mpoes12 said:


> There is not going to be a sound isolation advantage between the two for the vast majority of people. Pemko has test data showing the loss in isolation compared to glued in place. You have to have a very high STC door to need either of the options compared to what basic silicone or neoprene stick on gaskets will give you. The advantage with these systems is that they are adjustable and so easy to align and get a good seal.
> 
> I've seen test data on the transmission loss of plywood or MDF with green glue and the stc values of even that is far lower than you might hope. Basically the stc value of your door needs to be in the low 40's before there becomes a need for the lighter duty door gasket system. It needs to be well into the 50's before the heavy duty is needed. A normal solid core door is going to range from around stc20 to stc35. The most commonly available solid core doors are in the mid to upper 20's.
> 
> In other words, buy what you like. There is no sound isolation advantage for you unless you are building a very soundproof wall with a very high STC door assembly. It's mostly going to be for ease of use and bragging rights.
> 
> 
> Sent from my iPhone using Tapatalk


The walls will be good -- room within a room, DD, & GG; virtually no holes -- the outlets and switches are going in columns, the surround speakers will have backer boxes with MDF/GG/Drywall. 

The door is the weak link. How would I beef it up? I was interested in interlocking doors, but my wife vetoed it. I saw some people have added GG and then a layer of wood or drywall to a solid core door. Does that make much of a difference?


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## Mpoes12

GatorBlues said:


> The walls will be good -- room within a room, DD, & GG; virtually no holes -- the outlets and switches are going in columns, the surround speakers will have backer boxes with MDF/GG/Drywall.
> 
> 
> 
> The door is the weak link. How would I beef it up? I was interested in interlocking doors, but my wife vetoed it. I saw some people have added GG and then a layer of wood or drywall to a solid core door. Does that make much of a difference?




The door is almost always the weakest link. My comment about the gaskets was specifically because the door is the weakest link. 

Ok so first, moderators I am not selling any products or services with the following comments. I've been looking into possibly having a soundproof door manufactured and being offered. I've investigated the current offerings and how they are constructed. I've recently been in contact with a well known acoustic testing lab about testing door slabs and they gave me access to their test results library so I can avoid retesting things they have already tested. I don't have results on a mdf door with mdf laminated to it with green glue, but I do have results for slabs made from multiple layers of mdf laminated with a damping compound/adhesive. From what I can infer, I would estimate that adding a 1/2" piece of mdf to a mdf core door would add about 5-7stc points. That is with green glue. With the original slab only having an stc rating of 25-30, we are talking about moving up to maybe 30-35. When you consider that a moderate STC rates door is in the 40's, you can see we are way off a high stc rating. 

To be honest I'm looking into options but at the moment I am yet to find a solution I'm confident would offer an stc rating unto the 40's or 50's. 

I've seen some "bank vault" builds around here. I'm not sure anything like that has been tested. I still am thinking from the data I have read the STC rating wouldn't be all that high. 


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## deewan

I’ve done some searching on this and I haven’t found an answer that specifically answers my question so I’m looking for some guidance. Everything I find appears to involve in-ceiling speakers (no cabinets) or can lights.

My room’s soundproof ceiling will consist of Safe N Sound insulation between floor joists, isolation clips, 25-gauge resilient channel, one layer of 1/2” OSB, green glue and finally 5/8” drywall. The OSB will be use on ceiling only and needed for a “screw anywhere and attach something” reason. All walls if have same treatment but double 5/8” drywall, no OSB.

I plan on putting DIY Soundgroup Volt 6 ported speaker enclosures above my seats for Atmos/DTS:X channels. If I mount the Volt 6 cabinet in the ceiling much like a backer box is there a need to create a backer box for the speaker cabinet? I’m thinking the speaker cabinet acts as a backer box. Yes?

If the cabinet can act as a backer box I would have no problem adding a second layer to all exterior cabinet surfaces expect the baffle and putting green glue between them to make sure no sound escapes out of the room or speaker. I should be good, right? Or am I creating an issue I’m not aware of?


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## Mpoes12

deewan said:


> I’ve done some searching on this and I haven’t found an answer that specifically answers my question so I’m looking for some guidance. Everything I find appears to involve in-ceiling speakers (no cabinets) or can lights.
> 
> 
> 
> My room’s soundproof ceiling will consist of Safe N Sound insulation between floor joists, isolation clips, 25-gauge resilient channel, one layer of 1/2” OSB, green glue and finally 5/8” drywall. The OSB will be use on ceiling only and needed for a “screw anywhere and attach something” reason. All walls if have same treatment but double 5/8” drywall, no OSB.
> 
> 
> 
> I plan on putting DIY Soundgroup Volt 6 ported speaker enclosures above my seats for Atmos/DTS:X channels. If I mount the Volt 6 cabinet in the ceiling much like a backer box is there a need to create a backer box for the speaker cabinet? I’m thinking the speaker cabinet acts as a backer box. Yes?
> 
> 
> 
> If the cabinet can act as a backer box I would have no problem adding a second layer to all exterior cabinet surfaces expect the baffle and putting green glue between them to make sure no sound escapes out of the room or speaker. I should be good, right? Or am I creating an issue I’m not aware of?




Can you share more details. These volts will be recessed into the walls? How will you attach them? What will they be attached to?

A speaker enclosure can certainly act like a backer box and adding additional CLD layers will help with sound isolation and possibly even sound quality. I think my biggest concerns would be ensuring they are decouple from the house and that you still have an airtight ceiling. 


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## deewan

Mpoes12 said:


> Can you share more details. These volts will be recessed into the walls? How will you attach them? What will they be attached to?
> 
> A speaker enclosure can certainly act like a backer box and adding additional CLD layers will help with sound isolation and possibly even sound quality. I think my biggest concerns would be ensuring they are decouple from the house and that you still have an airtight ceiling.
> 
> 
> Sent from my iPhone using Tapatalk


Geesh, can't believe I forgot how I plan to hang them. The cabinets will be recessed into the ceiling and between the floor joists. I plan on adding 1x3 poplar around the front baffle to screw the OSB to and use acoustic caulk on all the seams. Bascially build backer boxes, but use them as speaker cabinets for overhead speakers. I will attach the speaker cabinets to the floor joists in the ceiling using clips like the clip shown in the picture below. The cabinet will be decoupled from the floor joists.









Adding another layer with green glue and mdf will be easy so I can do that.


----------



## Mpoes12

Then I think you will be fine. Just pay special attention to how the cabinet is sealed. Also Remember that joint compound isn't air tight. Use acoustic caulk in as many places as possible before sealing it up. You may want to consider building a flange on the box to rest the drywall on. Then put acoustic caulk on the flange. When you hang the drywall it will make an airtight seal with a good amount of mass behind it. 


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## ramesh_cm79

deewan said:


> I’ve done some searching on this and I haven’t found an answer that specifically answers my question so I’m looking for some guidance. Everything I find appears to involve in-ceiling speakers (no cabinets) or can lights.
> 
> My room’s soundproof ceiling will consist of Safe N Sound insulation between floor joists, isolation clips, 25-gauge resilient channel, one layer of 1/2” OSB, green glue and finally 5/8” drywall. The OSB will be use on ceiling only and needed for a “screw anywhere and attach something” reason. All walls if have same treatment but double 5/8” drywall, no OSB.
> 
> I plan on putting DIY Soundgroup Volt 6 ported speaker enclosures above my seats for Atmos/DTS:X channels. If I mount the Volt 6 cabinet in the ceiling much like a backer box is there a need to create a backer box for the speaker cabinet? I’m thinking the speaker cabinet acts as a backer box. Yes?
> 
> If the cabinet can act as a backer box I would have no problem adding a second layer to all exterior cabinet surfaces expect the baffle and putting green glue between them to make sure no sound escapes out of the room or speaker. I should be good, right? Or am I creating an issue I’m not aware of?


I was planning to do the same exact thing and I did ask Ted White the following:

Which of these two solutions would give me a better sound proofing?
1) Add additional layers of MDF directly on the existing speaker cabinet with green glue (i.e. speaker cabinet + green glue + 3/4" MDF + green glue + 3/4" MDF). Add an MDF/plywood lip around the speaker baffle and seal the resulting heavy single piece speaker to the drywall.
2) build a separate backer box (3/4" mdf + green glue + 3/4" mdf), seal to drywall from back and rest the speaker inside this backer box with one inch gap around the edges. I see that this is the preferred/documented approach but I am wondering what advantages this would have over option 1 above which is also adding the same extra layers of MDF with an extra layer of green glue. 

He recommended the second option and the reason was "The air cavity in this example gives isolation."

Here's my new plan (my goal is to minimize the overall depth without sacrificing the sound proofing)
1) Treat volt-6 or volt-10lx as an in-wall speaker so just order the kit with the front baffle without the flat pack. 
2) Build a new backer box (two 3/4" mdf layers with green glue in between) whose internal volume is equal to or greater than the recommended volume for the speaker (based off of the flat packs)
3) Seal the backer box to the back of the drywall
4) Attach the woofer to the front baffle.
5) Cut the drywall as minimal as possible to insert just the woofer with front baffle glued/screwed to the wall.


I am not sure if the above will work and if it compromises the speaker's SQ and how it compares to a regular backer box as far as sound proofing is concerned. Would really appreciate any thoughts from this group.


----------



## RyanDHT

ramesh_cm79 said:


> I was planning to do the same exact thing and I did ask Ted White the following:
> 
> Which of these two solutions would give me a better sound proofing?
> 1) Add additional layers of MDF directly on the existing speaker cabinet with green glue (i.e. speaker cabinet + green glue + 3/4" MDF + green glue + 3/4" MDF). Add an MDF/plywood lip around the speaker baffle and seal the resulting heavy single piece speaker to the drywall.
> 2) build a separate backer box (3/4" mdf + green glue + 3/4" mdf), seal to drywall from back and rest the speaker inside this backer box with one inch gap around the edges. I see that this is the preferred/documented approach but I am wondering what advantages this would have over option 1 above which is also adding the same extra layers of MDF with an extra layer of green glue.
> 
> He recommended the second option and the reason was "The air cavity in this example gives isolation."
> 
> Here's my new plan (my goal is to minimize the overall depth without sacrificing the sound proofing)
> 1) Treat volt-6 or volt-10lx as an in-wall speaker so just order the kit with the front baffle without the flat pack.
> 2) Build a new backer box (two 3/4" mdf layers with green glue in between) whose internal volume is equal to or greater than the recommended volume for the speaker (based off of the flat packs)
> 3) Seal the backer box to the back of the drywall
> 4) Attach the woofer to the front baffle.
> 5) Cut the drywall as minimal as possible to insert just the woofer with front baffle glued/screwed to the wall.
> 
> 
> I am not sure if the above will work and if it compromises the speaker's SQ and how it compares to a regular backer box as far as sound proofing is concerned. Would really appreciate any thoughts from this group.


I am very interested in this topic as well. I assume we have all checked out this thread? Specifically post 141. The way I understood Big was basically just put a beefed up cabinet into the wall/ceiling and putting flange on the front baffle to seal to the front of the drywall. I had originally planned on building a backer box to serve as a "speaker cabinet" similar to what was explained above, but Bigs method seemed so much easier so I had changed to planning to doing that, but would be interested if there are newer best practices?

http://www.avsforum.com/forum/155-d...ling-speakers-dolby-atmos-5.html#post25932145


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## HT Geek

ScottieBoysName said:


> If I go that route, I certainly will. Threshold might not pass the wife test. Especially if it's metal looking or aluminum looking. Do they make any kind of decorative ones or something else I could do?


As @Mpoes12 mentioned, wood thresholds are common. Even the Frost King brand makes them. You can fabricate your own if you like. The advantage of the pre-manufactured designs is they are engineered to facilitate carpet butting up to at least one side (by virtue of the angle of the wood thresholds or design of the metal thresholds).




ScottieBoysName said:


> Good news! They're going to let me replace the french doors with a single solid core door, 36 inches wide.  So, instead of two 24 inch french doors, I'll have a single solid core 36 inch door. So, I feel like that's a good starting point and way ahead of the french doors. I'm stoked!


Good for you! Quite frankly it should have been a no-brainer/non-issue for the builder. They still need to frame a door header. Nothing really changes for them from an engineering perspective.




ScottieBoysName said:


> All good points. I think I'd rather spend the $200-$300 to get those I linked, since they're adjustable and appear that I can make sure they make good contact. Know what I mean?


Adjustable gaskets are a mixed bag. Pros: they are adjustable and as necessary you can ... obviously... adjust them. Cons are higher cost and .... you have to adjust them when you think it's warranted. Quite frankly, IMHO you are better off saving your $, installing on Day One, and calling it a day. BUT it's not a bad thing to have adjustable stops, etc. If you are a major geek, it can be a good thing.


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## HT Geek

Mpoes12 said:


> To be honest I'm looking into options but at the moment I am yet to find a solution I'm confident would offer an stc rating unto the 40's or 50's.
> 
> I've seen some "bank vault" builds around here. I'm not sure anything like that has been tested. I still am thinking from the data I have read the STC rating wouldn't be all that high.


Well, maybe... maybe not. The fact is unless your door is a mirror image of the remainder of your wall design, it's probably lower STC.

I just want to add that I've read of a very few "bank vault" type door arrangements. The most impressive versions I've read up on involved pneumatic seals and/or multiple gasket layers with metal doors. Extreme is the adjective that comes to my mind. I'd venture that in those cases, the doors are truly likely to be of high STC value.

When it comes to wood or wood core doors, I generally agree with you. But just to be clear, automatic door bottoms, neoprene gaskets, etc. are not without merit. I believe it's important to reinforce to folks - in the context of this discussion and debate - that those techniques DO have value. But it's perhaps worth noting that those efforts portend improvements in performance when compared with the alternative (not using them) versus comparative results to sound-proofed walls and ceilings. IOW, folks should expect their doors/doorways will be weak points in their build. What we are talking about here are methods to reduce the negative affect of having a door, not trying to create a door that mimics the sound proofing qualities of the wall. IOOW... accept your door is a weak point. Given the alternative (no entry), it's not a bad tradeoff.

Just seeking to clarify expectations here. There is so much attention in this forum to 'do this' or 'do that', I believe sometimes the big picture gets lost in the details. I'm not discounting any of @Mpoes12 comments, but rather seeking to clarify the fact one should not panic if your door's STC does not equal or exceed your wall theoretical STC.

To his point however, real-world sound proofing is nearly always inferior to lab results and that's certainly true of doors.


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## ScottieBoysName

HT Geek said:


> As @Mpoes12 mentioned, wood thresholds are common. Even the Frost King brand makes them. You can fabricate your own if you like. The advantage of the pre-manufactured designs is they are engineered to facilitate carpet butting up to at least one side (by virtue of the angle of the wood thresholds or design of the metal thresholds).
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Good for you! Quite frankly it should have been a no-brainer/non-issue for the builder. They still need to frame a door header. Nothing really changes for them from an engineering perspective.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Adjustable gaskets are a mixed bag. Pros: they are adjustable and as necessary you can ... obviously... adjust them. Cons are higher cost and .... you have to adjust them when you think it's warranted. Quite frankly, IMHO you are better off saving your $, installing on Day One, and calling it a day. BUT it's not a bad thing to have adjustable stops, etc. If you are a major geek, it can be a good thing.




Got it. Awesome advice. Thanks so much!


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## Mpoes12

HT Geek said:


> Well, maybe... maybe not. The fact is unless your door is a mirror image of the remainder of your wall design, it's probably lower STC.
> 
> 
> 
> I just want to add that I've read of a very few "bank vault" type door arrangements. The most impressive versions I've read up on involved pneumatic seals and/or multiple gasket layers with metal doors. Extreme is the adjective that comes to my mind. I'd venture that in those cases, the doors are truly likely to be of high STC value.
> 
> 
> 
> When it comes to wood or wood core doors, I generally agree with you. But just to be clear, automatic door bottoms, neoprene gaskets, etc. are not without merit. I believe it's important to reinforce to folks - in the context of this discussion and debate - that those techniques DO have value. But it's perhaps worth noting that those efforts portend improvements in performance when compared with the alternative (not using them) versus comparative results to sound-proofed walls and ceilings. IOW, folks should expect their doors/doorways will be weak points in their build. What we are talking about here are methods to reduce the negative affect of having a door, not trying to create a door that mimics the sound proofing qualities of the wall. IOOW... accept your door is a weak point. Given the alternative (no entry), it's not a bad tradeoff.
> 
> 
> 
> Just seeking to clarify expectations here. There is so much attention in this forum to 'do this' or 'do that', I believe sometimes the big picture gets lost in the details. I'm not discounting any of @Mpoes12 comments, but rather seeking to clarify the fact one should not panic if your door's STC does not equal or exceed your wall theoretical STC.
> 
> 
> 
> To his point however, real-world sound proofing is nearly always inferior to lab results and that's certainly true of doors.




I think we may have been making a different point here. Everything you've said is true. I was not suggesting that gaskets aren't important. Just that the expensive adjustable gasket will likely yield no benefit over the cheaper stick on gaskets. 

My point was based on test data from Pemko where they looked at the number of stc points lost with using their gaskets for a given door assembly. Their results showed that the kinds of doors we typically use do. It benefit from anything greater than the stick in bulb type silicone gaskets. The more expensive adjustable gaskets with neoprene were only of benefit once the door assembly stc got up into the 40's. 

My main point is that you don't need to spend $100's of dollars on door gaskets to achieve the best results you are going to get with a given door. If you are using a standard solid core door, then less than $50 in gaskets should be adequate. Pemko also recommends a threshold with rubber gasket on lower stc doors without the automatic door bottom. It works just as well and is quite a bit cheaper. On mid range doors they suggest the automatic door bottom. With top end doors they suggest using both. 

My point about building high stc doors was that it's very hard to obtain a high stc door for a reasonable price. If I could have bought a door that offered an stc rating of 55 for $500. I would have happily used two of them in my theater. However anything over stc 35 was well over $1000 with most being more like 3 times that amount. I had thought that it might be possible to build such a door, but as it turns out those high stc doors cost a lot for a reason.

I agree the door is always a weak point and we need to accept it. I guess the point with the gaskets was really that people should realize just how big a weak point it is. The door is such a weak point that anything over basic weather stripping isn't adding much value. It's too bad. St after all that Effort to make high stc walls, we are stuck with an stc 25 door covering 15% of the wall.


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## GatorBlues

Mpoes12 said:


> My point about building high stc doors was that it's very hard to obtain a high stc door for a reasonable price. If I could have bought a door that offered an stc rating of 55 for $500. I would have happily used two of them in my theater. However anything over stc 35 was well over $1000 with most being more like 3 times that amount. I had thought that it might be possible to build such a door, but as it turns out those high stc doors cost a lot for a reason.


For you and @HT Geek --

So what's the best reasonably priced approach? A standard solid core exterior door? $1,000 per door sounds high but not impossible if it adds significant improvement. Three times that amount is out of the question. 

Is there value in adding a layer of MDF to it (with green glue) or is that a myth?


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## HT Geek

GatorBlues said:


> For you and @HT Geek --
> 
> So what's the best reasonably priced approach? A standard solid core exterior door? $1,000 per door sounds high but not impossible if it adds significant improvement. Three times that amount is out of the question.
> 
> Is there value in adding a layer of MDF to it (with green glue) or is that a myth?


The best approach is a communicating door system where at least one of the doors is decoupled, neoprene seals and auto door bottoms on both doors. Minimum 3' air space between doors, and both doors 1-3/4" thick solid core minimum.

More mass is good, but as @Mpoes12 was mentioning, the seals are the weak point in a door. Adjustable seals help a minute amount because they can be tweaked over time to accommodate the natural movement of building materials over time (especially wood). However, I'm not a big fan of them because they cost more and most people (myself included) are unlikely to tweak them periodically.

It all boils down to a game of whack-a-mole. As one improves sound proofing in one area, a weak spot pops up in another. Sound proof your room to the high 60's STC for example, and suddenly a 40-50 STC door is the weak point; or the door seals, etc. etc. So, I'd say what is 'best' is a function of whatever limitations you're working within. If you can fit a communicating door, I'd do that. It is by far the best method regardless of what type of doors you use. If that is not practical, consider 1-3/4" or thicker solid core door or an exterior door (but be mindful of the fact it still needs to be solid and heavy as some exterior doors are not). One of the reasons exterior doors are often recommended is they come with seals, which interior doors don't come with by default. However, the aftermarket seals for an interior door are typically superior for sound proofing.


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## Mpoes12

I'll add that you need to check the STC rating of the doors. The vast majority of doors have an stc rating between 15 and 25. I looked at a lot of exterior doors. Here is what I can say for sure. Masonite and Jeld Wen doors all have substantially better stc ratings for their interior solid core doors over all exterior door options. They are quite a bit more massive too. The highest rated stc door I could find that wasn't a very expensive sound rated door is the Jeld wen r series with rigicore and gaskets. 


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## bubbrik

I need some help with deciding the best way to mount my projector without causing too much damage to the clip/channel/double drywall shell. Since th ceiling height is low, I would like to install the projector slightly behind the second row and over the bar table. I would like to hear how you may have tackled this. For my setup, I don't have a soffit to put the projector in.

Thanks!


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## Mpoes12

The standard way is to use a sheet of plywood or OSB as the first layer. It's also good practice to increase the number of clips and space the channel closer together. There IS a weight limit for the clips and channel so you want to be sure you don't exceed it. I calculated that my 35lb projector was probably ok but very close to the limit so I added channel so that the area around he projector has 12" spaced channel and a few extra clips. The plywood then stiffens the structure and gives you something to screw into.

I do not suggest that doing the first layer with OSB or plywood is a good thing for the entire first layer. Theoretically it will degrade transmission loss performance and adds a lot of extra work and expense. However strategically placed is a good idea. This is an example. 

If it's too late then you need to find your channel and screw directly into that. At least two large screws must pass through channel. 


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## bubbrik

Mpoes12 said:


> The standard way is to use a sheet of plywood or OSB as the first layer. It's also good practice to increase the number of clips and space the channel closer together. There IS a weight limit for the clips and channel so you want to be sure you don't exceed it. I calculated that my 35lb projector was probably ok but very close to the limit so I added channel so that the area around he projector has 12" spaced channel and a few extra clips. The plywood then stiffens the structure and gives you something to screw into.
> 
> I do not suggest that doing the first layer with OSB or plywood is a good thing for the entire first layer. Theoretically it will degrade transmission loss performance and adds a lot of extra work and expense. However strategically placed is a good idea. This is an example.
> 
> If it's too late then you need to find your channel and screw directly into that. At least two large screws must pass through channel.
> 
> 
> Sent from my iPhone using Tapatalk



Thanks @Mpoes12

My framing is still open and no drywall yet. If I understand you correctly, for the area where I plan to have the projector installed, my first layer that goes on the clip/channel should be plywood or OSB instead of drywall and for the rest of the ceiling, go with drywall for both layers as I was already planning to do. Did I get that right?



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## Mpoes12

bubbrik said:


> Thanks @Mpoes12
> 
> My framing is still open and no drywall yet. If I understand you correctly, for the area where I plan to have the projector installed, my first layer that goes on the clip/channel should be plywood or OSB instead of drywall and for the rest of the ceiling, go with drywall for both layers as I was already planning to do. Did I get that right?
> 
> 
> 
> Sent from my iPhone using Tapatalk




Yes that is correct. I used a single 4x8 sheet. The advantage is that it spreads the stronger piece over a larger area. You could probably get away with a 4x4 sheet. I was just trying to be extra cautious. My favorite projectors are all on the heavy side and I wanted to be prepared. 


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## bubbrik

Hello

When attaching the second layer of drywall to ceilings and walls, should it be screwed into the channel using fine thread screws or attach it just to the first layer of drywall using laminator screws?

Thanks


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## LydMekk

Into the channel.
Example: my builders use a 25mm drywall screw for the first layer. Then applies GG to the second layer of plates and uses a 42mm screw on that one.
Important: do not use overly long screws. It heightens the danger of screwing through the channel and into wood beams behind them, which will totally negate the use of the channels.


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## bubbrik

LydMekk said:


> Into the channel.
> Example: my builders use a 25mm drywall screw for the first layer. Then applies GG to the second layer of plates and uses a 42mm screw on that one.
> Important: do not use overly long screws. It heightens the danger of screwing through the channel and into wood beams behind them, which will totally negate the use of the channels.




Thank you @LydMekk for your quick response. I've noted the lengths of the drywall screws as well.


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## Mpoes12

LydMekk said:


> Into the channel.
> Example: my builders use a 25mm drywall screw for the first layer. Then applies GG to the second layer of plates and uses a 42mm screw on that one.
> Important: do not use overly long screws. It heightens the danger of screwing through the channel and into wood beams behind them, which will totally negate the use of the channels.



They actually tested the effect of short circuiting the channel with greenglue and found the negative impact to be minor. Certainly don't want to do it on purpose but it's not the end of the world. 

It makes sense too. The problem is the screw transferring sound energy into the joist or stud. If the screw is now attached to a large heavily damped piece of drywall then much of that energy is being damped away before it can transfer to the stud or joist. 


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## LydMekk

That made little sense. Short-circuiting with GG??
And who are "they"?

TL;DR: dont use too long screws.


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## dennwood

LydMekk said:


> That made little sense. Short-circuiting with GG??
> And who are "they"?
> 
> TL;DR: dont use too long screws.


The Green Glue company posted results of STC testing where two layers of drywall and GG were used with resilient channel. They apparently simulated the effects of short circuiting the resilient channel assembly and noted that with GG, there was not much effect. My take from that is that if you're using two layers of drywall and GG, resilient channel may be somewhat redundant. There are other good reasons to use resilient though..more related to the reliability of the drywall long terms from flex etc.

http://www.greengluecompany.com/sites/default/files/Green_Glue_Vs_Resilient_Channel_1.pdf

Those tests show that the Green Glue tests are also 6db better at noise reduction in the 60Hz range..something they push for marketing...


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## Mpoes12

LydMekk said:


> That made little sense. Short-circuiting with GG??
> 
> And who are "they"?
> 
> 
> 
> TL;DR: dont use too long screws.




They is green glue and someone else already noted what they found. It makes perfect sense if you understood what I was trying to say. I'm sorry what I wrote wasn't clear. 

I stand by what I said. Don't do it on purpose but with green glue it's been proven a minor problem. 


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## impreza276

Question: My mine is an older house with a wooden plank sub floor underneath the hardwood floor. Does this pose any special challenges for soundproofing the basement HT room?


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## Mpoes12

impreza276 said:


> Question: My mine is an older house with a wooden plank sub floor underneath the hardwood floor. Does this pose any special challenges for soundproofing the basement HT room?




It can create challenges that could negatively impact soundproofing. A few concerns are sound leakage and squeeking from those walking above. 

http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/










As long as you don't mind doing this, it should fix the problems. I certainly wouldn't rip up your floors over this. 


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## impreza276

Thanks. I was looking at that and wondering whether it would make a big difference to quietening sound entering the rooms above. If the extra drywall and green glue only addresses footfall coming from above then it's not worth it for me. The additional cost of green glue would be painful!


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## Mpoes12

impreza276 said:


> Thanks. I was looking at that and wondering whether it would make a big difference to quietening sound entering the rooms above. If the extra drywall and green glue only addresses footfall coming from above then it's not worth it for me. The additional cost of green glue would be painful!




It's primary benefit is footfall. It probably adds a few dB's of extra transmission loss but not a lot. My guess is that most folks would mitigate that benefit with typical flanking paths. 


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## Ladeback

My house is ten years old and the area above my theater is our living room and kitchen. There is a sub floor with a engineered wood floor that squeaks in places. I hear the squeaks when walking above, but don't hear them below when I am down stairs. Now I do hear my kid running and playing, but I not done any soundproofing at all. I was just going to do insulation, clips, channel, DD and GG for my ceiling. I think that would be enough. One layer of drywall and green glue would do something between the joist, but as you said GG is not cheap.


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## Mpoes12

Ladeback said:


> My house is ten years old and the area above my theater is our living room and kitchen. There is a sub floor with a engineered wood floor that squeaks in places. I hear the squeaks when walking above, but don't hear them below when I am down stairs. Now I do hear my kid running and playing, but I not done any soundproofing at all. I was just going to do insulation, clips, channel, DD and GG for my ceiling. I think that would be enough. One layer of drywall and green glue would do something between the joist, but as you said GG is not cheap.



I guess I feel that in the grand scheme of things the green glue isn't that expensive. You don't have to do two layers between joists as shown. You can do just one layer. The effect isn't as great but not a huge issue. 

You could use acoustic caulk instead of green glue if the only purpose is to lessen foot fall and reduce squeaks. It would likely have a similar effect. I'm not sure it's any cheaper per oz and the green glue is at least proven for this purpose.

I didn't find this method to add a lot of benefit. My dining room is above the theater and has carpet. I can't hear footfall but can hear the bass of kids jumping. My plan is to add a second layer of plywood to the floor with GreenGlue at a layer date when we change our the carpet. That and something like serenity Mat will have the same effect and more. 



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## shblt

Looking back a few pages and the issue of ridged ducts running through a room was addressed, but just to confirm is the conscious to use flex duct where the duct vents into the room? Also, would it be worth it to build a duct muffler or silencer between the take off and vent drops? The goal being to reduce the flanking noise from the theater into the rest of the duct work.

I have an existing ridged duct that vents into my unfinished basement, running parallel between the joists. I’m planning on having the vents in the room ceiling, no extra isolated soffit for the duct work, and I’m wondering if I should replace it with flex duct or do anything else when I extend it. If it makes a difference I’m planning on doing all the recommend techniques discussed in this thread – DD + GG, clips and channel, DD between floor joists, disconnect walls, etc.


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## Ladeback

shblt said:


> Looking back a few pages and the issue of ridged ducts running through a room was addressed, but just to confirm is the conscious to use flex duct where the duct vents into the room? Also, would it be worth it to build a duct muffler or silencer between the take off and vent drops? The goal being to reduce the flanking noise from the theater into the rest of the duct work.
> 
> I have an existing ridged duct that vents into my unfinished basement, running parallel between the joists. I’m planning on having the vents in the room ceiling, no extra isolated soffit for the duct work, and I’m wondering if I should replace it with flex duct or do anything else when I extend it. If it makes a difference I’m planning on doing all the recommend techniques discussed in this thread – DD + GG, clips and channel, DD between floor joists, disconnect walls, etc.


My basement is unfinished as well, but I have no duct work feeding the it. I do have run that go through joist to the upstairs and was told this are ok, but if I bring ducts and venrs into the room I should build duct mufflers and use flex duct to do it. A recommend size was for it to be 14' to 15' long and 15"x15" in a double lined box with insulation around it, but that it could be built in the joist as well. If you contact the Soundproofing Company they have a SIM on how to build it and can be of great help on other things soundproofing.

http://www.soundproofingcompany.com


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## BSHuff

Issue from my plan review with my city:

I have an existing walkup unfinished attic. The existing stair well as existing up is 37.5 wide with 5/8 drywall on exterior wall side and 1/2 on interior side. they want a 36" clear width for code. One wall is against the exterior wall. As I need to open this wall to do the construction they want that wall to become R-15 vs the R-13 as built 

I have 1.5 inches to play with to isolate and insulate the wall. I can not do anything to the exterior at this time. 

What is the most isolation for the smallest width on a 2X4 wall with R15 so I can keep my 36" clear

My best plan so far is to use rockwool to get my R15 and DD/GG on both walls, this would take 1-1.25" (1/2 vs 5/8) of the available 1.5" and leave me a little wiggle room for measuring 36" when inspected. Drywall cost is a wash +/- a few sheets and would add a requirement of ~200sqft of rockwool. 

Any other 'system' I came up with would take 1.5 inches minimum. Plan reviewer said to add 1/2 of rigid foam to the wall to add R3 and drywall.


----------



## Ladeback

BSHuff said:


> Issue from my plan review with my city:
> 
> I have an existing walkup unfinished attic. The existing stair well as existing up is 37.5 wide with 5/8 drywall on exterior wall side and 1/2 on interior side. they want a 36" clear width for code. One wall is against the exterior wall. As I need to open this wall to do the construction they want that wall to become R-15 vs the R-13 as built
> 
> I have 1.5 inches to play with to isolate and insulate the wall. I can not do anything to the exterior at this time.
> 
> What is the most isolation for the smallest width on a 2X4 wall with R15 so I can keep my 36" clear
> 
> My best plan so far is to use rockwool to get my R15 and DD/GG on both walls, this would take 1-1.25" (1/2 vs 5/8) of the available 1.5" and leave me a little wiggle room for measuring 36" when inspected. Drywall cost is a wash +/- a few sheets and would add a requirement of ~200sqft of rockwool.
> 
> Any other 'system' I came up with would take 1.5 inches minimum. Plan reviewer said to add 1/2 of rigid foam to the wall to add R3 and drywall.


So the walkup goes to your atic, I take it is were you are building your theater? Are you putting DD, GG, clips and channel in you theater? If so I would just put in plain R15 pink insulation and 5/8" drywall up in the stairwell. I have read here a lot that the Ruxol doesn't make much difference from the pink stuff, but not for sure.


----------



## BSHuff

Ladeback said:


> So the walkup goes to your atic, I take it is were you are building your theater? Are you putting DD, GG, clips and channel in you theater? If so I would just put in plain R15 pink insulation and 5/8" drywall up in the stairwell. I have read here a lot that the Ruxol doesn't make much difference from the pink stuff, but not for sure.


The walkup is the entrance to corridor the media room in the attic. 3 of the 4 walls in the room are to be double stud, and clips&hat on the ceiling - it has 3 different angles to play with. Had planned on clips/hat on the wall that includes the stairs, but now that I have to add additional insulation there that cramped the plans, and only gave me 1.5" to use. The stairs go under the media room, so wanted to condition them as much as I could while I was at it to keep that 'hall' as quiet as I could. 

Found this evening R-15 fiberglass in 2X4 size, the Roxul was thought as it was R15 for 2X4 over the fiberglass. Looks like I will just R15 fiberglass and double as much as I can in that stairwell to maintain my 36" width for code.


----------



## HT Geek

Mpoes12 said:


> You could use acoustic caulk instead of green glue if the only purpose is to lessen foot fall and reduce squeaks. It would likely have a similar effect. I'm not sure it's any cheaper per oz and the green glue is at least proven for this purpose.


AC is a fraction of the cost of GG. $77 delivered from Home Depot, case of 12.


----------



## Mpoes12

HT Geek said:


> AC is a fraction of the cost of GG. $77 delivered from Home Depot, case of 12.



There you go! It is certainly cheaper. I decided to calculate the actual per oz price in each case and it does appear to be a good bit cheaper. 22 cents an oz vs 39 cents an oz roughly. I guess each person needs to decide if that difference in he grand scheme of things is worth it. 



I do think it’s important to stress that while I feel that acoustic caulk and drywall will help reduce footfall since it adds mass and damping. I don’t think it is likely to be as good as green glue. If you have a choice, use green glue. I know tests comparing caulk to green glue were done and found to show caulk to be only marginally effective. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


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## impreza276

One possibility I considered was using using Quiet Glue and applying Green Glue or acoustic sealant around the perimeter of the board to contain the dripping. I'm playing safe though and sticking to Green Glue.


----------



## HT Geek

impreza276 said:


> One possibility I considered was using using Quiet Glue and applying Green Glue or acoustic sealant around the perimeter of the board to contain the dripping. I'm playing safe though and sticking to Green Glue.


Wise. If you've seen the post in my sig.... my experience with QuietGlue was very disappointing. Not in that thread, but I'll mention here that even 6 months after application I still had dripping issues using QG on vertical surfaces. Unbelievable. I have witnessed very minor vertical "shear" of the glue with GG by comparison, and that was only within a few days of application and an isolated section that posed some other challenges to begin with.


----------



## HT Geek

BSHuff said:


> Issue from my plan review with my city:
> 
> I have an existing walkup unfinished attic. The existing stair well as existing up is 37.5 wide with 5/8 drywall on exterior wall side and 1/2 on interior side. they want a 36" clear width for code. One wall is against the exterior wall. As I need to open this wall to do the construction they want that wall to become R-15 vs the R-13 as built
> 
> I have 1.5 inches to play with to isolate and insulate the wall. I can not do anything to the exterior at this time.
> 
> What is the most isolation for the smallest width on a 2X4 wall with R15 so I can keep my 36" clear
> 
> My best plan so far is to use rockwool to get my R15 and DD/GG on both walls, this would take 1-1.25" (1/2 vs 5/8) of the available 1.5" and leave me a little wiggle room for measuring 36" when inspected. Drywall cost is a wash +/- a few sheets and would add a requirement of ~200sqft of rockwool.
> 
> Any other 'system' I came up with would take 1.5 inches minimum. Plan reviewer said to add 1/2 of rigid foam to the wall to add R3 and drywall.


So, I'm not sure I'm interpreting your post correctly. Have I got this right?:


Existing wall 2x4 stud with R13 insulation in wall
R13 must be brought up to R15
Finished wall clearance is 37-1/2" and that's with the R13/15 wall to one side
The wall side in question is an exterior wall
Drywall of the stairwell interior is 1/2" thick
Max room for improvement is 1-1/2" width
Based on that, my suggestions:


Replace R13 insulation with R15 Rockwool Safe'n'Sound or Comfort series. The R15 is 3-1/2" wide. Provided your wall was built with standard 2x4's and not the engineered 2x4's, it will fit. The engineered 2x4's are sometimes 1/4" thinner all around.
You could add 1 extra layer of drywall on that same wall with Green Glue. Then you're down to ~1" wiggle room in the stairwell.
Slap a 5/8" layer of drywall + GG on the other (interior side) wall in the stairwell. You could possibly do 2x 1/2" sheets more with GG between layers, but I'd say it's prolly not worth it and you'll shrink your gap


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## BSHuff

HT Geek said:


> So, I'm not sure I'm interpreting your post correctly. Have I got this right?:
> 
> 
> Existing wall 2x4 stud with R13 insulation in wall
> R13 must be brought up to R15
> Finished wall clearance is 37-1/2" and that's with the R13/15 wall to one side
> The wall side in question is an exterior wall
> Drywall of the stairwell interior is 1/2" thick
> Max room for improvement is 1-1/2" width
> Based on that, my suggestions:
> 
> 
> Replace R13 insulation with R15 Rockwool Safe'n'Sound or Comfort series. The R15 is 3-1/2" wide. Provided your wall was built with standard 2x4's and not the engineered 2x4's, it will fit. The engineered 2x4's are sometimes 1/4" thinner all around.
> You could add 1 extra layer of drywall on that same wall with Green Glue. Then you're down to ~1" wiggle room in the stairwell.
> Slap a 5/8" layer of drywall + GG on the other (interior side) wall in the stairwell. You could possibly do 2x 1/2" sheets more with GG between layers, but I'd say it's prolly not worth it and you'll shrink your gap


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## BSHuff

For HVAC flex ducts, I have the option of R6 or R8 insulation levels. R6 is minimum by my code. Is there any benefit of going to the R8 ducting for soundproofing reasons? If I plan to insulate the chase with as much fiberglass as I can, is there having a little more thickness around the actual duct going to help at all?


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## Mpoes12

BSHuff said:


> For HVAC flex ducts, I have the option of R6 or R8 insulation levels. R6 is minimum by my code. Is there any benefit of going to the R8 ducting for soundproofing reasons? If I plan to insulate the chase with as much fiberglass as I can, is there having a little more thickness around the actual duct going to help at all?



Flex duct isn’t soundproof. It leaks sound like a siv. The advantage of the R8 is for sound absorption reasons, not soundproofing reasons. The R8 would absorb reflected sound energy inside the duct to a lower frequency than the R6, but neither the R6 nor R8 will absorb much above 600hz if it’s not acoustic flex duct with a perforated lining. 

For soundproofing you need to have that duct in a soundproof enclosure of some type. A lot of people use soffits. If the flex duct leaves the soundproof shell of the theater at all it will leak sound. The transmission loss through R8 fiberglass is only a few db’s. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


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## TheZoof

I wanted to take a moment and thank every one in this thread.

We designed our home theater with a lot of the tips found here.

Unfortunately we couldn't get it 100% sound proof due to the HVAC system however overall it is as good as we can make it.

Thanks again.


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## HT Geek

Mpoes12 said:


> Flex duct isn’t soundproof. It leaks sound like a siv. The advantage of the R8 is for sound absorption reasons, not soundproofing reasons. The R8 would absorb reflected sound energy inside the duct to a lower frequency than the R6, but neither the R6 nor R8 will absorb much above 600hz if it’s not acoustic flex duct with a perforated lining.
> 
> For soundproofing you need to have that duct in a soundproof enclosure of some type. A lot of people use soffits. If the flex duct leaves the soundproof shell of the theater at all it will leak sound. The transmission loss through R8 fiberglass is only a few db’s.


True, but placing plenty of bends in the duct is also an integral part of making the whole process work since it causes the sound waves to bounce around inside the duct, and in the process they lose some energy. 

A straight duct will easily transmit sound from one point to another, but the combination of bends and surrounding the duct with other absorbent materials (e.g. placing it inside a soffit where there's insulation, drywall, etc.) will work to quiet noise that would otherwise travel inside the duct.


----------



## Mpoes12

HT Geek said:


> True, but placing plenty of bends in the duct is also an integral part of making the whole process work since it causes the sound waves to bounce around inside the duct, and in the process they lose some energy.
> 
> 
> 
> A straight duct will easily transmit sound from one point to another, but the combination of bends and surrounding the duct with other absorbent materials (e.g. placing it inside a soffit where there's insulation, drywall, etc.) will work to quiet noise that would otherwise travel inside the duct.




You got a straw man argument there. You are talking about the sound that travels through the duct and assuming that the sound is bouncing through it. Due to the very low mass of the flex duct material that would only hold true at high frequencies. The vast majority of sound is going to pass through the walls. Flex duct is good at absorbing the sound that travels through it it’s line internally. However not a soundproof medium and no matter how many bends will not stop sound from passing through its walls. In fact it would pass through largely at the first bend. 

I vaguely recall finding some hvac investigations into transmission loss through various duct materials and will try to post if it helps. I really think we are talking about Two different things and I think the more important one for soundproofing is actually the sound traveling through the wall of the duct. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


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## HT Geek

Mpoes12 said:


> You got a straw man argument there. You are talking about the sound that travels through the duct and assuming that the sound is bouncing through it. Due to the very low mass of the flex duct material that would only hold true at high frequencies. The vast majority of sound is going to pass through the walls. Flex duct is good at absorbing the sound that travels through it it’s line internally. However not a soundproof medium and no matter how many bends will not stop sound from passing through its walls. In fact it would pass through largely at the first bend.
> 
> I vaguely recall finding some hvac investigations into transmission loss through various duct materials and will try to post if it helps. I really think we are talking about Two different things and I think the more important one for soundproofing is actually the sound traveling through the wall of the duct.


I re-read the original question on the subject a few posts above ^ and the details of what the OP were gauging aren't clear. You're right I was addressing the question of sound transmission from one end of a duct to the other (i.e., flanking), which was perhaps the right answer to the wrong question.  I should have read his question more carefully, though it seems like an odd question to begin with now that I've correctly re-read it.

Perhaps the subject is worthy of a qualifying question back to the OP. I'm not sure what the OP was really trying to figure out. I have yet to hear of anyone trying to sound proof their walls by stuffing flex duct into them, and therefore I presumed (perhaps incorrectly) what they were really interested in was akin to sound transmitting through the flex duct from one point to another (i.e. along the duct versus laterally).


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## BSHuff

HT Geek said:


> I re-read the original question on the subject a few posts above ^ and the details of what the OP were gauging aren't clear. You're right I was addressing the question of sound transmission from one end of a duct to the other (i.e., flanking), which was perhaps the right answer to the wrong question.  I should have read his question more carefully, though it seems like an odd question to begin with now that I've correctly re-read it.
> 
> Perhaps the subject is worthy of a qualifying question back to the OP. I'm not sure what the OP was really trying to figure out. I have yet to hear of anyone trying to sound proof their walls by stuffing flex duct into them, and therefore I presumed (perhaps incorrectly) what they were really interested in was akin to sound transmitting through the flex duct from one point to another (i.e. along the duct versus laterally).


My question was assuming that I had the same routing of R6 vs R8 duct (squiggly in a soffit and some hard directional changes in the equipment room), will I see any overall sound control benefit of going to the more expensive better insulated duct. Does having thicker more perfect insulation application wrapped around the flex duct system get me any benefits over just stuffing some random loose scraps/etc in to fill the cavity with the cheaper duct. The walls/etc are conventionally insulated, any insulation on the ductwork/in the soffit is supplemental to the envelope insulation. 

My HVAC unit and majority of ductwork is in unconditioned attic, so some extra insulation in that part of the run would be better for energy concerns.


----------



## HT Geek

BSHuff said:


> My question was assuming that I had the same routing of R6 vs R8 duct (squiggly in a soffit and some hard directional changes in the equipment room), will I see any overall sound control benefit of going to the more expensive better insulated duct. Does having thicker more perfect insulation application wrapped around the flex duct system get me any benefits over just stuffing some random loose scraps/etc in to fill the cavity with the cheaper duct. The walls/etc are conventionally insulated, any insulation on the ductwork/in the soffit is supplemental to the envelope insulation.
> 
> My HVAC unit and majority of ductwork is in unconditioned attic, so some extra insulation in that part of the run would be better for energy concerns.


No, there's no benefit from an audio perspective to using R6 vs R8. The bene would be from a climate perspective; i.e., more insulation means better temperature maintenance / less loss of air temp as it travels through the duct. 

You'd be better off going with cheaper R6 and using insulation scraps around it inside the soffit, as you mentioned. That would help with temp inside the duct, and from a sound perspective it also helps to dampen sounds passing through the soffit. Scraps are typically stuffed into the soffit to prevent resonance. There really isn't any procedure to control sound passing laterally through the flex duct. It's not something I would worry about at all. Should be a non-issue.

The concern with duct is longitudinal sound travel (down the duct work from one egress point to another), and that is the purpose of putting bends in and longer runs. The combination of longer runs and bends causes the sound to be dissipated so by the time you get from your HVAC equipment (for example) to the vent in your room, you don't hear mechanical noise emanating into your room. There can be other reasons to do this as well, such as reducing the velocity of air flow (also to reduce noise to an inaudible level), but that's another sub-topic so to speak. It gets a little tricky to control velocity while still ensuring sufficient flow (CFM) so the HVAC can still do its job of climate control.


----------



## Mpoes12

HT Geek said:


> No, there's no benefit from an audio perspective to using R6 vs R8. The bene would be from a climate perspective; i.e., more insulation means better temperature maintenance / less loss of air temp as it travels through the duct.
> 
> 
> 
> You'd be better off going with cheaper R6 and using insulation scraps around it inside the soffit, as you mentioned. That would help with temp inside the duct, and from a sound perspective it also helps to dampen sounds passing through the soffit. Scraps are typically stuffed into the soffit to prevent resonance. There really isn't any procedure to control sound passing laterally through the flex duct. It's not something I would worry about at all. Should be a non-issue.
> 
> 
> 
> The concern with duct is longitudinal sound travel (down the duct work from one egress point to another), and that is the purpose of putting bends in and longer runs. The combination of longer runs and bends causes the sound to be dissipated so by the time you get from your HVAC equipment (for example) to the vent in your room, you don't hear mechanical noise emanating into your room. There can be other reasons to do this as well, such as reducing the velocity of air flow (also to reduce noise to an inaudible level), but that's another sub-topic so to speak. It gets a little tricky to control velocity while still ensuring sufficient flow (CFM) so the HVAC can still do its job of climate control.




I’m sorry but again I disagree with you. Why would you think that breakout sound doesn’t matter at all? That’s simply not true. It only doesn’t matter if you have contained the breakout sound. If anything increases breakout sound would further reduce sound traveling through the duct, but you still need to deal with that sound to prevent it from retaliating where you don’t want it. I think it’s inappropriate to suggest that isn’t a concern. Even the manufacturers often add warnings to be careful about the radiation or breakout sound. It is a standard part of architectural acoustics to consider that. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


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## HT Geek

Mpoes12 said:


> I’m sorry but again I disagree with you. Why would you think that breakout sound doesn’t matter at all? That’s simply not true. It only doesn’t matter if you have contained the breakout sound. If anything increases breakout sound would further reduce sound traveling through the duct, but you still need to deal with that sound to prevent it from retaliating where you don’t want it. I think it’s inappropriate to suggest that isn’t a concern. Even the manufacturers often add warnings to be careful about the radiation or breakout sound. It is a standard part of architectural acoustics to consider that.


I'm confused by your response.

Could you explain what you mean by "breakout sound?" How is sound capable of "retaliation." Retaliating against what?

I'm not sure what we apparently disagree on.

Getting back to HVAC flex duct, the point is you can either have it in your HT room or not have it. If you don't have it, then it's obviously a non-issue presuming there's no duct at all. But even under that circumstance, with regards to soffits or other cavities in the ceiling or wherever, I would stuff them with insulation to help mitigate the likelihood of reverberation. Regardless of the exact circumstances, doing so won't be a negative AFAIK.

If a room has HVAC vents, there are many examples of reducing sound from air velocity in particular by making flex duct runs longer and adding bends to slow down the velocity of the air. In addition, that process also reduces the likelihood someone will hear sound traversing from one end to another; though that's not usually a big deal with flex duct to begin with since it is commonly home-run to a plenum (versus rigid ducts that often share common branches between rooms). Even when a HT room's supply vents are in close proximity to a HVAC unit, the problem is normally air velocity noise and not mechanical noise.

Distance travelled makes a big difference as well. How far is a duct run? 5 feet? 500 feet? The longer the run, the more sound is dissipated between Point A and Point B. More bends help. Flex duct is a poorer reflector of sound than rigid duct, though rigid duct can be lined with duct liner, which helps mitigate that problem. Other techniques include using in-line mufflers.

It really all depends on what someone is trying to accomplish. If sound is traversing through the diameter of a flex duct, perpendicular to its air flow direction, and crossing through both sides of its insulation it will be affected differently versus if the sound is traveling longitudinally through the duct from point-to-point along the same axis as the air flow direction. And as you pointed out earlier, if the sound is cutting across a duct sideways or perpendicular to the air flow, that flex duct isn't going to do much to stop some types of sound. I certainly do not disagree with that.

The OP clarified his question....



BSHuff said:


> My question was *assuming that I had the same routing of R6 vs R8 duct* (squiggly in a soffit and some hard directional changes in the equipment room), *will I see any overall sound control benefit of going to the more expensive better insulated duct. Does having thicker more perfect insulation application wrapped around the flex duct system get me any benefits over just stuffing some random loose scraps/etc in to fill the cavity with the cheaper duct.*


It's still not crystal clear to me if the OP is concerned about sound transmission along the path of the flex duct (e.g. HVAC equipment to HT room) or through the side of the duct (e.g. between floors of a home), but I'm still presuming (and perhaps erring) on the side that he's interested in the former and that is what I was referring previously (sound travelling from vent to plenum for example, not between floors).

So, in my last post I was addressing that question... of which the answer is, no it doesn't matter if he uses R6 or R8. And furthermore, I sought to clarify that btw it is a good idea to stuff loose insulation around it to fill the cavity he mentioned. Not because it would benefit the point A-to-point B volume of sound through the duct (it won't affect that), but because it benefits the overall room sound proofing process in other ways.

I hope I've helped clarify my position. All that said, which point(s) are we disagreeing on?


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## jjackkrash

Repost from other thread that got no hits:

I am back on my basement build, which is using soundproofing techniques with double stud walls and clips and hat channel on for the ceiling. I am installing a dedicated Fujitsu mini split (ceiling cassette) with a fresh air return in the room to keep the HVAC separate from the rest of the house and to get fresh air in the room. I have several questions.

1. Any general install advice or things I might not have thought about would be great about installing the ceiling cassette with soundproofing in mind.

2. I am assuming I need to use clips to the joists for the ceiling cassette maybe using plywood base to decouple the cassette from the joists holding up the floor above.

3. I apparently need a trap door for the fresh air return to service it which attaches to the ceiling cassette. Any tips on making this happen without losing the seal and soundproofing benefits?

Here is the fresh-air intake assessories.

https://www.ecomfort.com/Fujitsu-UTZ-VXAA/p65857.html


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## deewan

jjackkrash said:


> Repost from other thread that got no hits:
> 
> I am back on my basement build, which is using soundproofing techniques with double stud walls and clips and hat channel on for the ceiling. I am installing a dedicated Fujitsu mini split (ceiling cassette) with a fresh air return in the room to keep the HVAC separate from the rest of the house and to get fresh air in the room. I have several questions.
> 
> 1. Any general install advice or things I might not have thought about would be great about installing the ceiling cassette with soundproofing in mind.
> 
> 2. I am assuming I need to use clips to the joists for the ceiling cassette maybe using plywood base to decouple the cassette from the joists holding up the floor above.
> 
> 3. I apparently need a trap door for the fresh air return to service it which attaches to the ceiling cassette. Any tips on making this happen without losing the seal and soundproofing benefits?
> 
> Here is the fresh-air intake assessories.
> 
> https://www.ecomfort.com/Fujitsu-UTZ-VXAA/p65857.html


I'm installing my (wall mounted) mini-split today. I had considered the ceiling cassette design to help with the keeping the conditioned air closer to the center of the room. I was looking at the Mitz units, so the size difference may have been causing my issues. For the life of me with the size of the ceiling unit that needed to go between the floor joists I was really struggling with how I could create a backer box and keep the sound shell intact. Best of luck!


----------



## Ladeback

deewan said:


> I'm installing my (wall mounted) mini-split today. I had considered the ceiling cassette design to help with the keeping the conditioned air closer to the center of the room. I was looking at the Mitz units, so the size difference may have been causing my issues. For the life of me with the size of the ceiling unit that needed to go between the floor joists I was really struggling with how I could create a backer box and keep the sound shell intact. Best of luck!


So you are installing the mini split your self? Do you have equipment to charge the outside unit? I am thinking that a mini split may be a better way to go then branching off the existing system. I think in the winter when the room is sealed up it will be hot and need AC not heat.


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## deewan

Ladeback said:


> So you are installing the mini split your self? Do you have equipment to charge the outside unit? I am thinking that a mini split may be a better way to go then branching off the existing system. I think in the winter when the room is sealed up it will be hot and need AC not heat.


Yup. Installing myself. I decided on a 2-ton Lennox unit. Should be enough to heat or cool the area regardless of outside temp, room temp, or number of people in the room. Best part is I don't have to worry about sound reaching other areas of the house through the duct work and the inside operating unit is only 29db loud when operating.

https://www.lennox.com/products/heating-cooling/mini-split-systems/mpa


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## galtrucco

*visco-elastic silly putty*

Hello, 
It seems that a lot of people have experience with green glue in between layers of drywall due to its viscoelastic properties. I was wondering if anyone had any experience with another widespread viscoelastic material with similar properties known since 1940s, that is... silly putty.

Silly putty can be made with some combination of borax, liquid starch, laundry detergent, glycerine and some glue. I think any glue will do, but perhaps need acrylic bonding for long-lasting plasticity, any suggestion(?)

Thanks!
G.


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## jjackkrash

Here's two pics of the cassette.


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## jjackkrash

I had to cut a notch out of one of the above joists centered above to get it to fit; I braced it with a pair of 2x4s on each side. Then I built a frame to hang it and connected it to the joists using 1b-3 clips.


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## deewan

@jjackkrash, your ceiling mounted unit looks great. Besides decoupling from the floor joists did you make any sort of backer box to help contain sound from the theater room and prevent it from escaping the hole cut in the drywall for the unit? From the pictures I would guess it could be possible to build a 4 sided box to bridge the gap between the fascia of the unit and the ceilings drywall to help create a sound proof shell.


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## jjackkrash

deewan said:


> @jjackkrash, your ceiling mounted unit looks great. Besides decoupling from the floor joists did you make any sort of backer box to help contain sound from the theater room and prevent it from escaping the hole cut in the drywall for the unit? From the pictures I would guess it could be possible to build a 4 sided box to bridge the gap between the fascia of the unit and the ceilings drywall to help create a sound proof shell.


There is no room to get a backer box above it. The unit itself does appear to be pretty sealed and insulated, except for the fresh air return hole, which I have not dealt with yet. I am open to suggestions.


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## BasementBob

Ducts


There's transmission through the wall of the duct, and transmission along the inside/length of the duct.


Transmission through the 'wall' of the duct resembles traditional wall (drywall, studs, drywall) construction results. Ducts are probably behind drywall.


Transmission along the length of the duct is measured in dBA drop per foot of length for various frequency bands. There's a bunch of published data for that. Even a straight duct, that's acoustically lined in any of the common ways (acoustical fiberglass duct liner with that interior coating to keep the dust out, perforated metal, etc) absorbs more sound than I would have guessed from my youthful experiences yelling into 8' plumbing PVC pipes. Wide ducts (18") have significantly less attenuation than narrow (6") ducts. e.g. a 3 meter insulated duct with 140 mm wide diameter has 50 dB attenuation near 1khz, and drop off in attenuation to both higher and lower frequencies.
Look for "duct silencer" or attenuation in rectangular ducts and it should turn up estimators and manufacturer's test data. There was a discussion somewhere here on AVS near Aug 2016 but I can't find it just now.


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## veger69

Hey guys I need to figure out the amount of acoustic caulking I need to do a 1/4” bead at the top and bottom of 16’x13’ room I’m going to using Green Glue Noiseproofing Sealant, 28 oz


Sent from my iPad using Tapatalk


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## HT Geek

veger69 said:


> Hey guys I need to figure out the amount of acoustic caulking I need to do a 1/4” bead at the top and bottom of 16’x13’ room I’m going to using Green Glue Noiseproofing Sealant, 28 oz


Veger, I had a chuckle at your post. 

My father-in-law and I had a similar conversation early in my build. All I can tell you is there's a difference in how every person applies caulk into the same cavity! It's really impossible for anyone to accurately predict. For instance, I wasted a lot more caulk than my F-I-L, but that's probably because I didn't have 30 years experience doing it like he did. 

That caveat aside, if you're only doing the seams where the walls/ceiling/floor meet one another, I'd calc the total linear feet and then figure perhaps about 2' per ounce. I can't recall exactly how much I used as it's been quite awhile, but I think 1-1/2 to 2 feet per ounce seems about right for me. YMMV.

If you have a some right now, why not try and see what you actually put down with one tube? If you must know before you order, I would just get a 6-pack unless you have really tall ceilings (>10').


----------



## HT Geek

jjackkrash said:


> Repost from other thread that got no hits:
> 
> I am back on my basement build, which is using soundproofing techniques with double stud walls and clips and hat channel on for the ceiling. I am installing a dedicated Fujitsu mini split (ceiling cassette) with a fresh air return in the room to keep the HVAC separate from the rest of the house and to get fresh air in the room. I have several questions.
> 
> 1. Any general install advice or things I might not have thought about would be great about installing the ceiling cassette with soundproofing in mind.
> 
> 2. I am assuming I need to use clips to the joists for the ceiling cassette maybe using plywood base to decouple the cassette from the joists holding up the floor above.
> 
> 3. I apparently need a trap door for the fresh air return to service it which attaches to the ceiling cassette. Any tips on making this happen without losing the seal and soundproofing benefits?
> 
> Here is the fresh-air intake assessories.
> 
> https://www.ecomfort.com/Fujitsu-UTZ-VXAA/p65857.html


JJack, I'm finally catching up to your progress on the mini-split. Looks like you've done good so far.

To Basement Bob's point, my thought is to consider wrapping some duct liner around the top and sides of canister. You might not need it. And it may not help much. Sound is like water and will find a way around things. But... it might help and wouldn't cost much in time or $ to implement. The question is whether or not it's feasible for you to get between the floor above and top of the canister and if you'd be able to do so while ensuring the duct liner doesn't touch the floor above or floor joists.

Another option would be to just stuff some pink fluffy in there. Not ideal perhaps, but better than nothing and cheap.

Based on the photos, I suspect getting a backer box built up there is not realistic at this point (and may not have realistically fit period even if installed before the canister).

I'm thinking it will most likely be a non-issue for your HT room compared with whatever sound it will make when operating, but that's one of the classic trade-offs in this field: climate or quiet? Looks like you chose climate, and I would too! (even tho I'm a stickler for good audio)


----------



## HT Geek

galtrucco said:


> Hello,
> It seems that a lot of people have experience with green glue in between layers of drywall due to its viscoelastic properties. I was wondering if anyone had any experience with another widespread viscoelastic material with similar properties known since 1940s, that is... silly putty.
> 
> Silly putty can be made with some combination of borax, liquid starch, laundry detergent, glycerine and some glue. I think any glue will do, but perhaps need acrylic bonding for long-lasting plasticity, any suggestion(?)


Odds are... on this forum... someone has tried it. 

Alas, not I.

All I can tell you is there are a number of factors that would impact its effectiveness. Just a few that I can think of (and I'm no expert on this): 

Consistency: Are you gonna make this yourself? Like slime??

Quality of materials. Is all Silly Putty the same? I don't know. Just sayin'. Are we talking silly putty made by a Chinese drywall company??? Hmm.....

Viscosity. There's an interesting semi-scientific research study on Shear-Thickening Fluids (STF's) performed at the physics department of Wooster College in 2012. The study examined some properties of certain types of fluids when exposed to shear force or impact force. STF's are supposed to be an actually very interesting product that is naturally in a fluid state but transforms into a solid when exposed to certain types of force. At least I think that's pretty cool. Beyond that statement though, I can't comment. 

source: http://physics.wooster.edu/JrIS/Files/Price_Web_Article.pdf

Now, of course I don't believe Silly Putty would qualify as a STF (but who knows)? My point is the viscosity of the material will matter. For example, I have personally had a negative experience with Quiet Glue Pro in this regard. I can tell you Green Glue has a higher level of viscosity or thickening rate than QG Pro. 

I've had vertical applications of QG Pro still unable to defy gravity after more than 60 days of drying. That is awful for one's needs on this forum. I mean, that's just plain inexcusable and an unusable product. I used my remaining stock to treat horizontal surfaces at that point. To contrast that experience, I've had no such experiences with Green Glue on vertical surfaces.

Now, if you want to try Silly Putty, by all means go for it, and please report back to the forum somewhere because I'm sure many folks would be curious to hear of your experience just for fun. But, I would caution you to (in addition to other factors to think about), consider how well it may or may not maintain a suitable physical state sandwiched inside your walls over several years.

The reason Green Glue is so widely recommended on this forum is because hundreds (if not thousands) of us have already used it and other products and seen the differences, and validated real-world performance. Furthermore, there are lab tests that corroborate all of our subjective data with objective evidence able to exclude most other factors. I'm not aware of any acoustic lab tests on silly putty.

Bottom line: I'd avoid using it and stick with a validated product if I were you. It doesn't have to be Green Glue, but at least use a product designed for the task at hand. That's my $0.02.


----------



## jjackkrash

HT Geek said:


> To Basement Bob's point, my thought is to consider wrapping some duct liner around the top and sides of canister. You might not need it. And it may not help much. Sound is like water and will find a way around things. But... it might help and wouldn't cost much in time or $ to implement. The question is whether or not it's feasible for you to get between the floor above and top of the canister and if you'd be able to do so while ensuring the duct liner doesn't touch the floor above or floor joists.


I have less than a 1/4 inch between the center floor joist that I had to cut out and the top of the ceiling cassette. But I would not mind wrapping the rest with duct liner (and also maybe Roxul). Any thoughts on duct-liner brand and best place to buy?


----------



## HT Geek

jjackkrash said:


> I have less than a 1/4 inch between the center floor joist that I had to cut out and the top of the ceiling cassette. But I would not mind wrapping the rest with duct liner (and also maybe Roxul). Any thoughts on duct-liner brand and best place to buy?


Of the standard stuff, Industrial Noise is the cheapest I've found, but I've also never seen it in quantities


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## jjackkrash

HT Geek said:


> Of the standard stuff, Industrial Noise is the cheapest I've found, but I've also never seen it in quantities


----------



## jjackkrash

Question: The HVAC installers for the main house unit (not the mini split) ran a PVC drip pipe between the 2x4 house framing and the 2x4 room-within-a-room framing that touches a few studs on both sets of frames. Will PVC transmit sound from one frame to the other such that I need to move the drip pipe or notch out the room-within-a-room frame so the pipe does not touch? It does not seem any worse than IB3 clips as far as contact goes, but I don't want to f this up. I will take steps to eliminate the contact unless I get a clear indication that this is not big deal. Thanks.


----------



## deewan

jjackkrash said:


> Question: The HVAC installers for the main house unit (not the mini split) ran a PVC drip pipe between the 2x4 house framing and the 2x4 room-within-a-room framing that touches a few studs on both sets of frames. Will PVC transmit sound from one frame to the other such that I need to move the drip pipe or notch out the room-within-a-room frame so the pipe does not touch? It does not seem any worse than IB3 clips as far as contact goes, but I don't want to f this up. I will take steps to eliminate the contact unless I get a clear indication that this is not big deal. Thanks.


My opinion, it all depends on what you consider a big deal. It likely won't make a huge sound transfer impact, but it will make some. I would guess it all depends how snuggle the PVC pipe is lodged between the two walls. If notching out the 2x4's on the room within a room is fairly easy I'd do that. If the PVC pipe is loosely touching the walls then see if you can throw some green glue tape or something between the items.


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## HT Geek

jjackkrash said:


> Question: The HVAC installers for the main house unit (not the mini split) ran a PVC drip pipe between the 2x4 house framing and the 2x4 room-within-a-room framing that touches a few studs on both sets of frames. Will PVC transmit sound from one frame to the other such that I need to move the drip pipe or notch out the room-within-a-room frame so the pipe does not touch? It does not seem any worse than IB3 clips as far as contact goes, but I don't want to f this up. I will take steps to eliminate the contact unless I get a clear indication that this is not big deal. Thanks.


It will. You want to avoid those type of connections between the walls. In this case, there's only so much you can realistically do about it, and it's not likely to be a huge impact anyway.

If the pipe is touching any stud directly, i'd put some kind of insulating material between the pipe and studs if you can.

If there's a gap between the pipe and studs, place something in there like putty to keep the pipe from vibrating on the studs.

Sent from my ONE A2005 using Tapatalk


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## veger69

Hey guys I have a 6” exterior wall that needs R19 insulation on one side of my theater room and I was wondering what insulation value if any Roxul safe n sound has? Because if it doesn’t have a good value I have three inches to add another insulation if needed.


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## Ladeback

veger69 said:


> Hey guys I have a 6” exterior wall that needs R19 insulation on one side of my theater room and I was wondering what insulation value if any Roxul safe n sound has? Because if it doesn’t have a good value I have three inches to add another insulation if needed.
> 
> 
> Sent from my iPad using Tapatalk


I have seen on a the Home Depot site that they have 5.5"x15.5 with and R23 value.


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## veger69

Ladeback said:


> I have seen on a the Home Depot site that they have 5.5"x15.5 with and R23 value.




California so only need R19 but my question is “what R value does Roxul Safe n Sound have” if any


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## jjackkrash

veger69 said:


> California so only need R19 but my question is “what R value does Roxul Safe n Sound have” if any
> 
> 
> Sent from my iPad using Tapatalk


I don't think they rate it with an R value. From Roxul's FAQ's:

"33) What are the R-values of AFB® and SAFE’n’SOUND®?
Interior insulation products do not require an R-value and as such, we do not brand our interior insulation with this information."


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## veger69

So does it make sense to try and stuff R19 insulation and Roxul in that 6” inch space or since it’s an outside wall just use R19


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## HT Geek

jjackkrash said:


> I don't think they rate it with an R value. From Roxul's FAQ's:
> 
> "33) What are the R-values of AFB® and SAFE’n’SOUND®?
> Interior insulation products do not require an R-value and as such, we do not brand our interior insulation with this information."


That's odd. I've seen batts of Safe'n'Sound and it does have an R-rating prominently displayed. Not sure about AFB since it's rare to find it in a retail shop. I'm sure it must have an R-value though.




veger69 said:


> So does it make sense to try and stuff R19 insulation and Roxul in that 6” inch space or since it’s an outside wall just use R19


You don't have to use Roxul. Generic fiberglass insulation would work as well. Roxul is more expensive, a bit denser, and resists mildew growth much better than fiberglass can. Fiberglass is cheaper. I wouldn't worry about mildew growth because if someone has a problem with that, then they have a problem that should be taken care of other than masking it with Roxul.

Bottom line is fiberglass is cheaper and unless you have a reason to use Roxul specifically, I would go with the most economical solution.


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## jjackkrash

HT Geek said:


> That's odd. I've seen batts of Safe'n'Sound and it does have an R-rating prominently displayed. Not sure about AFB since it's rare to find it in a retail shop.


I have an unopened batt downstairs so I went down to check and didn't see an R-rating on it. So I got curious and checked the Roxul web sight's FAQ's and copied the post above. Maybe they stopped giving it an r-rating. The only two sources of information I have are the batt downstairs and the Roxul website, so I dunno.


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## HT Geek

jjackkrash said:


> I have an unopened batt downstairs so I went down to check and didn't see an R-rating on it. So I got curious and checked the Roxul web sight's FAQ's and copied the post above. Maybe they stopped giving it an r-rating. The only two sources of information I have are the batt downstairs and the Roxul website, so I dunno.


Doh! Just realized I was apparently having a 'senior moment' earlier.... Indeed, you're right on (of course). I got myself mixed up with the packaging for Roxul's _Comfort Batt_, which looks almost identical to the Safe'n'Sound packaging. And now I recall, indeed Roxul does not indicate the R-rating of Safe'n'Sound anywhere. IIRC, that is because some nitwit at Roxul decided it made for a better marketing ploy to obfuscate it's insulation properties and market SnS for sound-proofing only, and not certify it for its heat retention properties.

I'm not sure if one can *technically* even use SnS period when an R-value is required for an installation (e.g. exterior walls). However, I can't imagine any inspector would notice or have a clue if you'd packed in SnS or Comfort Batt. The product appears virtually identical.

SnS vs. Comfort Batt has been the subject of debate on AVS from time-to-time. Personally, I'd feel comfortable using either for sound proofing or R-rating.


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## bombertodd

Safe n' Sound has an R-value of 3.9 r per inch of thickness.


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## HT Geek

bombertodd said:


> Safe n' Sound has an R-value of 3.9 r per inch of thickness.


Well, that's GTK. 

And responses like that are why I love this forum so much!


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## veger69

Thanks so a double batt should do it!


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## deewan

With all this talk about Safe N Sound and Comfort Batt, I forget if anyone has used the denim products and how they have done with sound control. I used Safe n Sound in the last theater but it appears right now the denim product is on sale and it would cost less with the added bonus of being completely itch free and safe to install. And the added bonus of completely recycled product.


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## Ladeback

deewan said:


> With all this talk about Safe N Sound and Comfort Batt, I forget if anyone has used the denim products and how they have done with sound control. I used Safe n Sound in the last theater but it appears right now the denim product is on sale and it would cost less with the added bonus of being completely itch free and safe to install. And the added bonus of completely recycled product.


This looks interesting. I thought Roxul was supposed to be itch free?


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## deewan

Roxul ins't as bad as the fiberglass, but this denim stuff is cotton. That seems to be one the least itchy materials I can think of.


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## jjackkrash

Is there any downside from a soundproofing standpoint to using plywood for the first layer instead of sheetrock in DD + GG configuration? I have seen people use OSB for the first layer. 3/4 ply is about as heavy as 5/8 firewall rated sheetrock. I suspect its more rigid, would this take away for my soundproofing efforts? 

The walls are double stud on 2-foot centers (mostly) the ceiling is using IB-1 clips and hat channel.


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## mtbdudex

Hey, I’m getting a FLIR one Pro thermal imaging camera to help me complete my log home energy efficiency improvements.
Earlier I had an energy audit done and they used a traditional handheld gun.

Energy audit

















FLIR one Pro 









Curious if anyone has used it for HT soundproofing audit, sound leakage might be able to be seen as heat energy transfer .

I hear there’s a Black Friday sale, so I’m waiting to order mine till then.










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## HT Geek

deewan said:


> With all this talk about Safe N Sound and Comfort Batt, I forget if anyone has used the denim products and how they have done with sound control. I used Safe n Sound in the last theater but it appears right now the denim product is on sale and it would cost less with the added bonus of being completely itch free and safe to install. And the added bonus of completely recycled product.


I've used it and I like it for some areas. It has superior acoustic damping compared to fiberglass or Roxul. Cost is on par with Roxul. However, it's a bit controversial.

I'll present to you the concerns I'm aware of some folks have:
Moisture retention (think sponge)
Chemical additives (for insect control & fire retardation)
Non-standard batt size (product dimensions)
Poor vapor barrier (they only come unfaced)

Other than the moisture retention concern that might bother some folks, as long as it's contained within a sealed wall, it's difficult for me to understand why anyone would be worried about the other issues I mentioned. Of course, I don't live in a climate where I need a vapor barrier so that's a factor to me personally.

These things are soaked in boric acid during the manufacturing process. How does that potentially affect you? The batts do give off some dust. They contain hydrogen borate (boric acid), ammonium sulfate, and binding fibers. You will get some dust, but there is no off-gassing I'm aware of. Even so, it can be irritating to your lungs. This is no different from other forms of insulation in the sense you should probably be wearing a dust mask anyway when working with any of them. Once it's inside the walls, it's a non-issue. I read the MSD sheet and it mentions the boron dust and to keep it in temps


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## HT Geek

jjackkrash said:


> Is there any downside from a soundproofing standpoint to using plywood for the first layer instead of sheetrock in DD + GG configuration? I have seen people use OSB for the first layer. 3/4 ply is about as heavy as 5/8 firewall rated sheetrock. I suspect its more rigid, would this take away for my soundproofing efforts?
> 
> The walls are double stud on 2-foot centers (mostly) the ceiling is using IB-1 clips and hat channel.


The primary purpose for a layer of plywood or OSB is that you can hang anything anywhere on your walls. The downside is it actually slightly detrimental to sound proofing. I know sounds counter-intuitive. Drywall has more flex than plywood or OSB, and that flex allows it to "give" a bit more. What you end up with is an undulating surface material (drywall) that does a better job at absorbing various frequencies of sound versus a very rigid surface (plywood, OSB). I would venture OSB is likely slightly 'less bad' compared to plywood, since my experience has been plywood is stiffer.

I don't think it's a huge issue. I used 5/8" OSB for my first layer before I knew it would be slightly counter-productive to my goals. I'm still pleased with the outcome of my room. That said, if I were to do-it-over, I would do all-drywall layers. Drywall is also easier to work with (surprisingly). It's much easier to cut quickly and conform to desired shapes or sizes where you need it.


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## HT Geek

mtbdudex said:


> Hey, I’m getting a FLIR one Pro thermal imaging camera to help me complete my log home energy efficiency improvements.
> Earlier I had an energy audit done and they used a traditional handheld gun....
> 
> Curious if anyone has used it for HT soundproofing audit, sound leakage might be able to be seen as heat energy transfer .


Some folks on the forum have done this, but I don't recall who or what type of FLIR device they used. The best ones I've seen are what the fire department uses, but they are VERY expensive!

I've never tried it for sound-proofing analysis, so I can't comment on whether or not it's truly a useful approach.


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## jrref

HT Geek said:


> I've used it and I like it for some areas. It has superior acoustic damping compared to fiberglass or Roxul. Cost is on par with Roxul. However, it's a bit controversial.
> 
> I'll present to you the concerns I'm aware of some folks have:
> Moisture retention (think sponge)
> Chemical additives (for insect control & fire retardation)
> Non-standard batt size (product dimensions)
> Poor vapor barrier (they only come unfaced)
> 
> Other than the moisture retention concern that might bother some folks, as long as it's contained within a sealed wall, it's difficult for me to understand why anyone would be worried about the other issues I mentioned. Of course, I don't live in a climate where I need a vapor barrier so that's a factor to me personally.
> 
> These things are soaked in boric acid during the manufacturing process. How does that potentially affect you? The batts do give off some dust. They contain hydrogen borate (boric acid), ammonium sulfate, and binding fibers. You will get some dust, but there is no off-gassing I'm aware of. Even so, it can be irritating to your lungs. This is no different from other forms of insulation in the sense you should probably be wearing a dust mask anyway when working with any of them. Once it's inside the walls, it's a non-issue. I read the MSD sheet and it mentions the boron dust and to keep it in temps


----------



## jjackkrash

HT Geek said:


> The primary purpose for a layer of plywood or OSB is that you can hang anything anywhere on your walls. The downside is it actually slightly detrimental to sound proofing. I know sounds counter-intuitive. Drywall has more flex than plywood or OSB, and that flex allows it to "give" a bit more. What you end up with is an undulating surface material (drywall) that does a better job at absorbing various frequencies of sound versus a very rigid surface (plywood, OSB). I would venture OSB is likely slightly 'less bad' compared to plywood, since my experience has been plywood is stiffer.
> 
> I don't think it's a huge issue. I used 5/8" OSB for my first layer before I knew it would be slightly counter-productive to my goals. I'm still pleased with the outcome of my room. That said, if I were to do-it-over, I would do all-drywall layers. Drywall is also easier to work with (surprisingly). It's much easier to cut quickly and conform to desired shapes or sizes where you need it.


Ok, that confirms my suspicions. I'll need to think on this, I would like to be able to hang things anywhere without looking for studs on 2 foot centers. I may just hang one piece of ply on the ceiling where the PJ mount goes so I don't have the deal with the hole it will make in the ceiling.


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## tamiya

How good this gonna get for Soundproofing? Half decent? Total not work? 

Because I'm renting the place and convert the garage to HT so I don't want to do heavy permanent stuff.
This is my idea of building the soundproofing and acoustic treatment. Let me know if this feasible or how to make it better.
Thanks a lot!










For soundproofing, how does it compare to staggered stud?


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## klimo

I'm throwing around the idea to sound proof my theater, but it's already finished with just standard framing and dry wall practices.

Can I add clips to the existing drywall then double drywall/green glue from there? Is there anything inherently wrong in doing that? Would it actually be better than just clubs on the studs? 

I would have to do this around the sofit and what not as well.

What about with walls with foundation behind them? The theater is under the garage, so is it necessary to do the ceiling as well?

Thanks.


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## HT Geek

klimo said:


> I'm throwing around the idea to sound proof my theater, but it's already finished with just standard framing and dry wall practices.
> 
> Can I add clips to the existing drywall then double drywall/green glue from there? Is there anything inherently wrong in doing that? Would it actually be better than just clubs on the studs?
> 
> I would have to do this around the sofit and what not as well.
> 
> What about with walls with foundation behind them? The theater is under the garage, so is it necessary to do the ceiling as well?
> 
> Thanks.


Kilmo, hate to tell you this but it's an all or nothing affair. You would need to demo your room first. If you proceeded as you've suggested, you'll create what is called a "triple leaf effect." What that means - essentially - is you'd make your acoustics worse.

I also have a 2nd floor theater above my garage. Check out my build (in my signature) to get an idea of level-of-effort.

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## HT Geek

Doh. I misspoke. One reason I don't like Tapatalk - I can't figure out a way to edit my previous posts!

You're right, there's limited value in worrying about your ceiling. However, you might still get noise flanking in your ceiling above your room. All depends on your home's existing construction.

Sent from my ONE A2005 using Tapatalk


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## Ladeback

@klimo, you may want to check out these builds. They are building their theaters under their garage as well. It might give you some ideas. There have been a few others but can't seem to find them right now.

http://www.avsforum.com/forum/19-dedicated-theater-design-construction/1607217-theater-design-build-under-suspended-slab-garage.html

http://www.avsforum.com/forum/19-dedicated-theater-design-construction/2580921-cinema-midwest-2-0-a.html


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## klimo

HT Geek said:


> Doh. I misspoke. One reason I don't like Tapatalk - I can't figure out a way to edit my previous posts!
> 
> You're right, there's limited value in worrying about your ceiling. However, you might still get noise flanking in your ceiling above your room. All depends on your home's existing construction.
> 
> Sent from my ONE A2005 using Tapatalk


I see this now. Kind of a bummer for me. Tearing down, is not an option at this time. Thanks for your input


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## Ladeback

klimo said:


> I see this now. Kind of a bummer for me. Tearing down, is not an option at this time. Thanks for your input


 @HTGeek, Would it help it for him to at least add another layer of drywall with green glue?


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## HT Geek

Ladeback said:


> @HTGeek, Would it help it for him to at least add another layer of drywall with green glue?


Yes.

It's all relative to your goals and budget. Adding another layer of drywall is the cheapest option. It won't provide dramatic results, but it will improve the situation a bit.


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## klimo

HT Geek said:


> Yes.
> 
> It's all relative to your goals and budget. Adding another layer of drywall is the cheapest option. It won't provide dramatic results, but it will improve the situation a bit.


That's probably my only realistic option. My goal is to shore up the door first and go from there.


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## jjackkrash

I posted this in my minisplit thread, but was hoping for maybe some more traffic here:

***

I am concerned that the fresh-air supply on my minisplit will be the weakest link in my room for soundproofing purposes, especially bass leakage through flanking. I need to get the 4" supply line to the outside world through a hole in my house above the shell. I would like to run it sideways to the outside of the house about 8-10 feet in just under or between the joists. If I don't make it longer I can avoid a booster fan and reduce complexity (according to my HVAC installer). I am not concerned about sound escaping outside the house, but I don't want flanking to the upstairs. 

Any thoughts? Would a 4" PVC pipe caulked to the supply port wrapped in dynamite or mass loaded vinyl work? Or would a box encasing covering flex duct and insulation work better? Thought on the opening to the outside world?


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## jjackkrash

Pics of the cassette with the supply port:


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## impreza276

jjackkrash said:


> Pics of the cassette with the supply port:


I have no experience in ducting but I would build a box encasing rigid PVC or steel duct simply because of ease of cleaning if anything ever entered the duct.

For your unit suspended by IB3 clips - it might be better to reverse the rubber grommets. They are easy to take out it you squish the sides but a bit tricky to reinsert without damaging the rubber.


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## jjackkrash

impreza276 said:


> I have no experience in ducting but I would build a box encasing rigid PVC or steel duct simply because of ease of cleaning if anything ever entered the duct.
> 
> For your unit suspended by IB3 clips - it might be better to reverse the rubber grommets. They are easy to take out it you squish the sides but a bit tricky to reinsert without damaging the rubber.


Good catch on the grommets. It was hectic when the HVAC guys were here as they had their own time constraints, and I didn't even notice that. Thanks a bunch.


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## SeekingNirvana

I have a 20x24x9 room that I am currently converting into a theater. I took it down to studs and am almost ready to install the rock. I am not going to go the route of green glue, hat channel, isolation clips etc, but was thinking of building a secondary wall (room within a room) on 3 walls. The fourth wall is a interior wall and im not concerned about sound going into the house. Trying to stop from getting to the neighbors. 

Would building the 3 walls make a big impact compared to just sheet rocking the existing walls? I would still have the 1" air gap, insulation and a layer of 5/8 rock on the secondary wall. 

Trying to see if doing this work is a waste of time and money. 

I started a thread but it isn't getting any traction......


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## Ladeback

SeekingNirvana said:


> I have a 20x24x9 room that I am currently converting into a theater. I took it down to studs and am almost ready to install the rock. I am not going to go the route of green glue, hat channel, isolation clips etc, but was thinking of building a secondary wall (room within a room) on 3 walls. The fourth wall is a interior wall and im not concerned about sound going into the house. Trying to stop from getting to the neighbors.
> 
> Would building the 3 walls make a big impact compared to just sheet rocking the existing walls? I would still have the 1" air gap, insulation and a layer of 5/8 rock on the secondary wall.
> 
> Trying to see if doing this work is a waste of time and money.
> 
> I started a thread but it isn't getting any traction......


Attached is from Soundproofing's company web page for walls with double studs. Double studs help and if you just add two layers of drywall on one side you can have at STC of 64, if you add green glue it would be a STC of 71. Others should chime in soon who have done this before.

http://www.soundproofingcompany.com/soundproof-walls/spc-3-soundproof-wall/


----------



## jjackkrash

@SeekingNirvana

The potential problem with your approach and not sealing the entire room is flanking. 

http://www.soundproofingcompany.com/soundproofing101/flanking-and-indirect-sound-leaks/


----------



## jrref

Ladeback said:


> Attached is from Soundproofing's company web page for walls with double studs. Double studs help and if you just add two layers of drywall on one side you can have at STC of 64, if you add green glue it would be a STC of 71. Others should chime in soon who have done this before.
> 
> http://www.soundproofingcompany.com/soundproof-walls/spc-3-soundproof-wall/


This is a nice web site and at least for me, this is all pretty standard but I think their STC ratings may be for a perfect room environment because they seem a little high. I think in the real world there are sometimes things that you can't work around to sound proof which gives you a slightly less STC rating than what they at publish.


----------



## jjackkrash

impreza276 said:


> For your unit suspended by IB3 clips - it might be better to reverse the rubber grommets. They are easy to take out it you squish the sides but a bit tricky to reinsert without damaging the rubber.


This was an easy swap thanks for spotting this.


----------



## HT Geek

jjackkrash said:


> @SeekingNirvana
> 
> The potential problem with your approach and not sealing the entire room is flanking.


^ He has a good point.




SeekingNirvana said:


> I have a 20x24x9 room that I am currently converting into a theater. I took it down to studs and am almost ready to install the rock. I am not going to go the route of green glue, hat channel, isolation clips etc, but was thinking of building a secondary wall (room within a room) on 3 walls. The fourth wall is a interior wall and im not concerned about sound going into the house. Trying to stop from getting to the neighbors.
> 
> Would building the 3 walls make a big impact compared to just sheet rocking the existing walls? I would still have the 1" air gap, insulation and a layer of 5/8 rock on the secondary wall.
> 
> Trying to see if doing this work is a waste of time and money.


In spite of my comment above, yes it will help. Which floor of your home is the room? If it's on the top floor, I'd suggest you also build a floating ceiling if possible. You might also get flanking via the floor unless it's on the ground level. If you can improve the exterior walls and connecting points via floor or ceiling that could flank noise across beams to your structural exterior wall, then I wouldn't be as concerned with the remaining interior wall as it will be directing sound mostly into the home (and you mentioned that fact is not a concern).



> I started a thread but it isn't getting any traction......


Please share a link here.

Also consider placing a link in your sig.


----------



## lsturbointeg

HT Geek said:


> Kilmo, hate to tell you this but it's an all or nothing affair. You would need to demo your room first. If you proceeded as you've suggested, you'll create what is called a "triple leaf effect." What that means - essentially - is you'd make your acoustics worse.
> 
> I also have a 2nd floor theater above my garage. Check out my build (in my signature) to get an idea of level-of-effort.
> 
> Sent from my ONE A2005 using Tapatalk



HT...i'm going to read your build regarding 2nd floor HT above the garage and see if it answers my question here:











Hello forum members! I'm in the middle of my thought process on SoundProofing my dedicated HT which sits above my garage on the 2nd floor. Really it's a bonus room which measures 25x20x9. My dilemma is now that I've been thinking about this 3 of the walls are external while 1 wall is connected to the house. The laundry room and my son's room is butt up against that wall. Is it necessary now that i think about it to SoundProof the 3 external walls? Also my other concern was SoundProofing the ceiling as it's just an attic above that? I will be tearing out all the existing drywall on all 4 walls as well as the ceiling so i can run all my electrical for the projector, canned lights, speaker wires, HDMI, ethernet, ect...than seal everything up using Roxul Safe n Sound on all walls including the ceiling with Resilient Channels with DD and GG. But i was thinking maybe in my circumstance it's not needed to SoundProof the 3 external walls and possibly the ceiling? Any advice would be greatly appreciated before i spend money on something that is not needed. Thanks!


----------



## Ladeback

lsturbointeg said:


> HT...i'm going to read your build regarding 2nd floor HT above the garage and see if it answers my question here:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hello forum members! I'm in the middle of my thought process on SoundProofing my dedicated HT which sits above my garage on the 2nd floor. Really it's a bonus room which measures 25x20x9. My dilemma is now that I've been thinking about this 3 of the walls are external while 1 wall is connected to the house. The laundry room and my son's room is butt up against that wall. Is it necessary now that i think about it to SoundProof the 3 external walls? Also my other concern was SoundProofing the ceiling as it's just an attic above that? I will be tearing out all the existing drywall on all 4 walls as well as the ceiling so i can run all my electrical for the projector, canned lights, speaker wires, HDMI, ethernet, ect...than seal everything up using Roxul Safe n Sound on all walls including the ceiling with Resilient Channels with DD and GG. But i was thinking maybe in my circumstance it's not needed to SoundProof the 3 external walls and possibly the ceiling? Any advice would be greatly appreciated before i spend money on something that is not needed. Thanks!



I would think flanking would be an issue on the three walls you don't do anything with and sending sound up and down could carry into the rest of the house especially through the ceiling into the rafters. @HTGeek will have more to say soon.

By the way is that a skylight in the room? That is going to be fun to work around and may need to be addresses as well.

Nice big room. The room in my basement I want to use for my theater is that, but have to deal with a beam and column.


----------



## lsturbointeg

HT Geek said:


> Unless you truly have a need, I hope I've convinced you to just do a 2x drywall/Green Glue sandwich! Should be cheaper too if you're paying for labor. Caulk or mud the seams on the first layer (don't sand/finish it). Acoustic caulk is preferable, but not required. Outer/Second layer, mud, sand, and finish as normal.


interested in why sanding is not needed for the 1st layer of drywall?


----------



## lsturbointeg

Ladeback said:


> I would think flanking would be an issue on the three walls you don't do anything with and sending sound up and down could carry into the rest of the house especially through the ceiling into the rafters. @*HTGeek* will have more to say soon.
> 
> By the way is that a skylight in the room? That is going to be fun to work around and may need to be addresses as well.
> 
> Nice big room. The room in my basement I want to use for my theater is that, but have to deal with a beam and column.


the skylight i was gonna close up. wife's no too happy about that but she understands. i had to research what flanking means and now i understand. in regards to that i mean those 3 external walls sits right on the garage so sound tranmission going down the walls into the garage for me is not an issue. but soud transmission going up the walls and into the attic and into the rafters i see where that can affect all the rooms upstairs. i'm wondering if there's a way to soundproof the top of the cavities of those 3 walls to prevent the flanking? i have no problems if anything to actually do all 4 walls and ceiling the right way but just didn't want to find out in the end i could have saved money because it was not necessary.


----------



## Ladeback

lsturbointeg said:


> the skylight i was gonna close up. wife's no too happy about that but she understands. i had to research what flanking means and now i understand. in regards to that i mean those 3 external walls sits right on the garage so sound tranmission going down the walls into the garage for me is not an issue. but soud transmission going up the walls and into the attic and into the rafters i see where that can affect all the rooms upstairs. i'm wondering if there's a way to soundproof the top of the cavities of those 3 walls to prevent the flanking? i have no problems if anything to actually do all 4 walls and ceiling the right way but just didn't want to find out in the end i could have saved money because it was not necessary.


To help in keeping the sound from flanking up the walls you would need to decouple it somehow. One way is to rip off the old drywall, add IB-1 clips and hat channel and then attach the drywall to the channel. Another way is to build a room inside a room and have the walls on the inside decoupled. 

You might want to read this first and check out more on Soundproofing Companies website to better understand soundproofing. I am still learning about it. 

http://www.soundproofingcompany.com/soundproofing101/4-elements-of-soundproofing/


----------



## SeekingNirvana

HT Geek said:


> ^ He has a good point.
> 
> 
> 
> 
> In spite of my comment above, yes it will help. Which floor of your home is the room? If it's on the top floor, I'd suggest you also build a floating ceiling if possible. You might also get flanking via the floor unless it's on the ground level. If you can improve the exterior walls and connecting points via floor or ceiling that could flank noise across beams to your structural exterior wall, then I wouldn't be as concerned with the remaining interior wall as it will be directing sound mostly into the home (and you mentioned that fact is not a concern).
> 
> 
> 
> Please share a link here.
> 
> Also consider placing a link in your sig.


Thanks @HT Geek,

The house is a single level house and the room in question used to be a garage so it is on a slab. Above the room is the attic...

http://www.avsforum.com/forum/19-dedicated-theater-design-construction/2933842-my-2-car-theater-build.html


----------



## HT Geek

lsturbointeg said:


> interested in why sanding is not needed for the 1st layer of drywall?


Mudding the seams of the 1st layer is optional. Sanding is not necessary because you're covering it with the 2nd layer. You mud and sand the 2nd layer as normal. At least unless you are using all fabric panel coverings, in which case you could mud only or caulk in between the seams.




lsturbointeg said:


> ... flanking... in regards to that i mean those 3 external walls sits right on the garage so sound tranmission going down the walls into the garage for me is not an issue. but soud transmission going up the walls and into the attic and into the rafters i see where that can affect all the rooms upstairs. i'm wondering if there's a way to soundproof the top of the cavities of those 3 walls to prevent the flanking? i have no problems if anything to actually do all 4 walls and ceiling the right way but just didn't want to find out in the end i could have saved money because it was not necessary.


You could do the 3 exterior walls and ceiling as double drywall/Green Glue. Question: Is it worthwhile to save time and money by not doing the same to the 4th wall? Then there's the question of the floor. But back to the ceiling... double drywall/green glue and adding extra insulation above the room in the attic ought to improve the situation if you don't want to create a completely decoupled shell.

The floor is tough because there's not a good way to handle it without a lot of work. My room is above my garage, and I chose to thicken the floor but that was all I did. I didn't want to pull up the sub-floor, decouple and replace it.


----------



## HT Geek

SeekingNirvana said:


> Thanks @HT Geek,
> 
> The house is a single level house and the room in question used to be a garage so it is on a slab. Above the room is the attic...
> 
> http://www.avsforum.com/forum/19-dedicated-theater-design-construction/2933842-my-2-car-theater-build.html


Alright. In that case, if you do not decouple the ceiling, you will get more flanking noise travelling via the attic to other parts of the home. It may or may not bother you. Decoupling the ceiling would reduce the effect. 

It's largely a question of how much sound energy will get to the joists in the attic and travel along them. You could even add more drywall to the existing ceiling to thicken it and make it heavier, but decoupling the ceiling would give you the best result.


----------



## Ladeback

HT Geek said:


> Alright. In that case, if you do not decouple the ceiling, you will get more flanking noise travelling via the attic to other parts of the home. It may or may not bother you. Decoupling the ceiling would reduce the effect.
> 
> It's largely a question of how much sound energy will get to the joists in the attic and travel along them. You could even add more drywall to the existing ceiling to thicken it and make it heavier, but decoupling the ceiling would give you the best result.


If I remember from reading on his build thread, he has removed the old drywall and so it would be a good time to add clips and hat channel to the ceiling, alnog with two layers of drywall and green glue correct?


----------



## HT Geek

Ladeback said:


> If I remember from reading on his build thread, he has removed the old drywall and so it would be a good time to add clips and hat channel to the ceiling, alnog with two layers of drywall and green glue correct?


Yep. Either that or build a room-within-a-room (double stud) with a floating ceiling. Clips would be less work and sacrifice less space.


----------



## SeekingNirvana

@HT Geek and @Ladeback

The more I think about it and the more I hear from you guys, it makes me lean to not doing anything at all other than just putting 1 layer of rock on the the existing walls. This seems like an all or nothing approach, and at this time I am not all in. We just bought this house and I thought I could take some budget DIY steps to make the room soundproof. I have read up on this topic and understand the basics of what needs to be done to accomplish a soundproof room but I do not want to spend thousands upon thousands on clips, channel, green glue etc. I have not done the exact math but off the top of my head it would probably around 3-5k  This is money that could be used in other places of the house like new windows, interior doors....I was willing to fork out 5-7 hundred on framing materials and an extra layer of rock but that doesn't sound like it will get me very far. 

With out treating the ceiling the sound will flank to the exterior walls. In my case the exterior walls are the most important as I am trying to keep sound from going to the neighbors. Since the ceiling is directly attached to the exterior walls, adding a secondary wall inside the room would not do much? All of the sound energy would just bypass the secondary walls and transfer to the exterior walls and the roof, which would then radiate out from there. Also the 4th wall is structurally attached to the same exterior walls so sound would flank that way too.

I had to take the room down to studs regardless of what I did. I just thought while I had it that way I would do some things to help the situation. I'm sure it will be ok if I do nothing....

Thanks for taking the time to reply


----------



## Ladeback

SeekingNirvana said:


> @HT Geek and @Ladeback
> 
> The more I think about it and the more I hear from you guys, it makes me lean to not doing anything at all other than just putting 1 layer of rock on the the existing walls. This seems like an all or nothing approach, and at this time I am not all in. We just bought this house and I thought I could take some budget DIY steps to make the room soundproof. I have read up on this topic and understand the basics of what needs to be done to accomplish a soundproof room but I do not want to spend thousands upon thousands on clips, channel, green glue etc. I have not done the exact math but off the top of my head it would probably around 3-5k  This is money that could be used in other places of the house like new windows, interior doors....I was willing to fork out 5-7 hundred on framing materials and an extra layer of rock but that doesn't sound like it will get me very far.
> 
> With out treating the ceiling the sound will flank to the exterior walls. In my case the exterior walls are the most important as I am trying to keep sound from going to the neighbors. Since the ceiling is directly attached to the exterior walls, adding a secondary wall inside the room would not do much? All of the sound energy would just bypass the secondary walls and transfer to the exterior walls and the roof, which would then radiate out from there. Also the 4th wall is structurally attached to the same exterior walls so sound would flank that way too.
> 
> I had to take the room down to studs regardless of what I did. I just thought while I had it that way I would do some things to help the situation. I'm sure it will be ok if I do nothing....
> 
> Thanks for taking the time to reply



I was just looking at you build again on your thread with the photos and building a second wall with a 1" and double drywall should help better then doing nothing I would think. If decoupled the new inner walls with IB-3 clips from the ceiling joist that would decouple them from the ceiling and help with flanking. To do just the ceiling in clips and channel isn't has bad as you think, the green glue to me is what is the the most expensive part. 

A rough estimate so don't quote me on this; IB-3 clips would be around $180 to $190, Clips and channel could cost somewhere around $380 to $400 or so. I would give Ted or someone at the Soundproofing Company a call and talk to them about what you want to do and your budget. They are very helpful. The Room I am thinking of building my theater in my basement is roughly 21x26x9 so close to what you have an am thinking of doing this, but maybe adding green glue as well. Make sure to insulate both inner and outer walls and the ceiling well and I think you would notice a difference. What do you think @HTGeek.


----------



## HT Geek

Ladeback said:


> A rough estimate so don't quote me on this; IB-3 clips would be around $180 to $190, Clips and channel could cost somewhere around $380 to $400 or so. I would give Ted or someone at the Soundproofing Company a call and talk to them about what you want to do and your budget. They are very helpful. The Room I am thinking of building my theater in my basement is roughly 21x26x9 so close to what you have an am thinking of doing this, but maybe adding green glue as well. Make sure to insulate both inner and outer walls and the ceiling well and I think you would notice a difference. What do you think @HTGeek.


I'm thinking ~$200 for ceiling clips. However....




SeekingNirvana said:


> @HT Geek and @Ladeback
> 
> The more I think about it and the more I hear from you guys, it makes me lean to not doing anything at all other than just putting 1 layer of rock on the the existing walls. This seems like an all or nothing approach, and at this time I am not all in. We just bought this house and I thought I could take some budget DIY steps to make the room soundproof. I have read up on this topic and understand the basics of what needs to be done to accomplish a soundproof room but I do not want to spend thousands upon thousands on clips, channel, green glue etc. I have not done the exact math but off the top of my head it would probably around 3-5k  This is money that could be used in other places of the house like new windows, interior doors....I was willing to fork out 5-7 hundred on framing materials and an extra layer of rock but that doesn't sound like it will get me very far.
> 
> With out treating the ceiling the sound will flank to the exterior walls. In my case the exterior walls are the most important as I am trying to keep sound from going to the neighbors. Since the ceiling is directly attached to the exterior walls, adding a secondary wall inside the room would not do much? All of the sound energy would just bypass the secondary walls and transfer to the exterior walls and the roof, which would then radiate out from there. Also the 4th wall is structurally attached to the same exterior walls so sound would flank that way too.
> 
> I had to take the room down to studs regardless of what I did. I just thought while I had it that way I would do some things to help the situation. I'm sure it will be ok if I do nothing....


Don't give up yet.

I just read your build thread. Thanks for posting pics. That helps a lot. Now that we know your budget and your room 'before' pics, I believe all is not lost. I'll post more comments in your build thread.


----------



## ExarKun9

Currently have a basement HT room, 22x29x8. Ceiling has 10 can lights. New sub woofers are causing some vibrations up stairs even at reasonable volume. I know removing dry wall on ceiling and adding channels with dry wall/green glue/dry wall would be best. Looking for cheaper and less time consuming solutions. I was considering- 1. removing can lights and sealing holes, 2. Green glue 2nd layer of drywall on to existing ceiling (sound proof caulk around edges), 3. Use flush mount led lights. Would this give me a noticeable sound reduction? Or is that a waste doing this half measure? I'm not looking to blast HT safely at 3am. Just need some improvement. Convincing my wife to go all out is likely a losing battle.

Thanks


----------



## HT Geek

ExarKun9 said:


> Currently have a basement HT room, 22x29x8. Ceiling has 10 can lights. New sub woofers are causing some vibrations up stairs even at reasonable volume. I know removing dry wall on ceiling and adding channels with dry wall/green glue/dry wall would be best. Looking for cheaper and less time consuming solutions. I was considering- 1. removing can lights and sealing holes, 2. Green glue 2nd layer of drywall on to existing ceiling (sound proof caulk around edges), 3. Use flush mount led lights. Would this give me a noticeable sound reduction? Or is that a waste doing this half measure? I'm not looking to blast HT safely at 3am. Just need some improvement. Convincing my wife to go all out is likely a losing battle.


Just removing and replacing the ceiling might not fix it to your satisfaction. The sound could also be traversing via wall studs, for example.

I'd say just changing the can lights is not likely to make noticeable difference. Probably a waste of time if that's the only thing you did.

Where are the subs in the room right now? How are they affixed/mounted? Is your current ceiling 1x drywall (i.e. standard ceiling)? What is between ceiling and floor above, besides air? How about the walls?


----------



## jjackkrash

ExarKun9 said:


> Convincing my wife to go all out is likely a losing battle.


A constant battle between my subwoofers and my wife caused to her _order_ me to go all out. You might just need bigger, more convincing subwoofers to fight your battle for you.


----------



## ExarKun9

HT Geek said:


> Just removing and replacing the ceiling might not fix it to your satisfaction. The sound could also be traversing via wall studs, for example.
> 
> I'd say just changing the can lights is not likely to make noticeable difference. Probably a waste of time if that's the only thing you did.
> 
> Where are the subs in the room right now? How are they affixed/mounted? Is your current ceiling 1x drywall (i.e. standard ceiling)? What is between ceiling and floor above, besides air? How about the walls?


Subs are 25ft away from area I'm focused on sound dampening. Subs are powered towers about 16in from #1 corner/wall, #2 wall. Current ceiling is 1x drywall, 10 can lights, not sure about insulation. Walls 1x drywall,studs. There's bedroom at back of HT and above that is master BR- want to keep quiet. 

Bedroom upstairs isn't directly above HT so I thought removing can lights, then green gluing 2nd drywall to ceiling. Possible 2nd layer dry wall to basement BR. I know sound will still travel up the outside wall studs but I put on some loud music. Went upstairs to master BR and it really wasn't bad. I'd barely hear it if tv was on upstairs. Guess my wife is a light sleeper.


----------



## ExarKun9

jjackkrash said:


> A constant battle between my subwoofers and my wife caused to her _order_ me to go all out. You might just need bigger, more convincing subwoofers to fight your battle for you.


Just upgraded and that's why I'm looking at sound proofing. Def Tech 9080 set, each tower 12" sub, 455 watt, two 12" radiators. Center has 8" sub, 250 watt. It's plenty big enough for me, just want to use it more than once a week.


----------



## jjackkrash

ExarKun9 said:


> I know sound will still travel up the outside wall studs but I put on some loud music. Went upstairs to master BR and it really wasn't bad. I'd barely hear it if tv was on upstairs. Guess my wife is a light sleeper.


Our bedroom is on the third floor, the subs were in the basement. You can't hear much in the bedroom from the basement, except the low frequency effects from movies. Even at low volume the movie bass travels up the studs and turns the sheet rock into passive subwoofers in the bedroom, only you can't hear the rest of the soundtrack. The subs would knock things off the walls it was so bad. She said it was way worse than hearing the whole soundtrack, cause it was all just startling LFE without a soundtrack to provide context. You might toss in Intersteller instead of music just to see.


----------



## Ladeback

jjackkrash said:


> Our bedroom is on the third floor, the subs were in the basement. You can't hear much in the bedroom from the basement, except the low frequency effects from movies. Even at low volume the movie bass travels up the studs and turns the sheet rock into passive subwoofers in the bedroom, only you can't hear the rest of the soundtrack. The subs would knock things off the walls it was so bad. She said it was way worse than hearing the whole soundtrack, cause it was all just startling LFE without a soundtrack to provide context. You might toss in Interstellar instead of music just to see.


Especially the rocket launch scene. I got to see and here that in @Archaea's house a few weeks ago and I thought we were actually taking off when the rocket launched. Not sure what it sounded like above us in his living room, but I think his family is used to it.

I only have 2-15' sealed subs corner loaded set at about 1/4 gain and when I watch movies in my makeshift theater below our kitchen and living room, my says things on one our cabinets shakes and rattles, but not enough that she complains. I am just glad my theater is now under our bedroom. 

Try this clip from Interstellar. I am going to tonight to see what my wife says.


----------



## deewan

I ordered the drywall for my room yesterday and as I began thinking ahead, something struck me. I’m trying to make sure every seam of hole in the theater is treated to maximized soundproofing. Acoustic caulk over all seams, all layers. All junction boxes are wrapped in putty pads with a bead of acoustic caulk around the box to seal to the ceiling/wall panel. So on and so forth. But now I’m need a solution. Here in Iowa and for people with concrete floors it is normally recommended to leave at least ½ inch gap between the concrete floor and bottom lip of drywall so ensure if the concrete sweats the drywall doesn’t grab the moisture and over time develop mold or break down the drywall making it weak. With normal framing and construction the gap between the bottom lip and concrete floor isn’t a big deal because the 2x4 bottom plate is 1.5” tall and the drywall would still create a seal of sorts. A bead of acoustic caulk could easy make sure that situation is air tight. 

However, with resilient channel the drywall is ¾” (or whatever) away from the wood frame and the bottom plate. If I leave a 1/2” to 5/8” gap between the concrete floor and bottom lip of the drywall I have a HUGE air leak into my walls and a gap large enough that it may be difficult to create a seal with acoustic caulk no matter how much I use.

What have others done? Used a large bead of acoustic caulk to fill the gap? I’ve thought about finding some sort of small diameter foam rope to set the first layer of drywall onto and then caulk but I’m open for ideas.


----------



## healthnut

ExarKun9 said:


> Currently have a basement HT room, 22x29x8. Ceiling has 10 can lights. New sub woofers are causing some vibrations up stairs even at reasonable volume. I know removing dry wall on ceiling and adding channels with dry wall/green glue/dry wall would be best. Looking for cheaper and less time consuming solutions. I was considering- 1. removing can lights and sealing holes, 2. Green glue 2nd layer of drywall on to existing ceiling (sound proof caulk around edges), 3. Use flush mount led lights. Would this give me a noticeable sound reduction? Or is that a waste doing this half measure? I'm not looking to blast HT safely at 3am. Just need some improvement. Convincing my wife to go all out is likely a losing battle.
> 
> 
> 
> Thanks




I went all out attempting to isolate my basement theater from the kitchen above, and while it’s much better than it was, the bass STILL makes it’s presence felt. It’s not realistic to expect to eliminate all the bass from adjoining spaces, unless money is no object and you can install giant industrial springs, such as the guy behind Auro did in his studio.


Sent from my iPhone using Tapatalk


----------



## healthnut

deewan said:


> I ordered the drywall for my room yesterday and as I began thinking ahead, something struck me. I’m trying to make sure every seam of hole in the theater is treated to maximized soundproofing. Acoustic caulk over all seams, all layers. All junction boxes are wrapped in putty pads with a bead of acoustic caulk around the box to seal to the ceiling/wall panel. So on and so forth. But now I’m need a solution. Here in Iowa and for people with concrete floors it is normally recommended to leave at least ½ inch gap between the concrete floor and bottom lip of drywall so ensure if the concrete sweats the drywall doesn’t grab the moisture and over time develop mold or break down the drywall making it weak. With normal framing and construction the gap between the bottom lip and concrete floor isn’t a big deal because the 2x4 bottom plate is 1.5” tall and the drywall would still create a seal of sorts. A bead of acoustic caulk could easy make sure that situation is air tight.
> 
> 
> 
> However, with resilient channel the drywall is ¾” (or whatever) away from the wood frame and the bottom plate. If I leave a 1/2” to 5/8” gap between the concrete floor and bottom lip of the drywall I have a HUGE air leak into my walls and a gap large enough that it may be difficult to create a seal with acoustic caulk no matter how much I use.
> 
> 
> 
> What have others done? Used a large bead of acoustic caulk to fill the gap? I’ve thought about finding some sort of small diameter foam rope to set the first layer of drywall onto and then caulk but I’m open for ideas.




What could work in your application is backer rod. You can get it in different widths and cut the lengths to size, and it’d be easy to stuff it in there.


Sent from my iPhone using Tapatalk


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## deewan

healthnut said:


> What could work in your application is backer rod. You can get it in different widths and cut the lengths to size, and it’d be easy to stuff it in there.
> 
> 
> Sent from my iPhone using Tapatalk


I had thought about something like that. Like you said should be fairly easy to stuff underneath and then to make sure it is sealed up use a strong bead of caulk. Much easier to caulk into a three sided area than trying to bridge the gap between two. Thanks!


----------



## Volleyfroebs

Hello everyone, I am building a theater on the second floor of new construction. I've been researching and dreaming about this theater for years. I am having a hard time understanding how to address walls/ceiling adjacent to the attic. My plan is double stud the walls and clip and channel the ceiling. I believe I have an understanding of the walls adjacent to other rooms with them being mass/air/mass. With regards to the walls next to open attic, it would be dw/gg/dw/stud/air space with pink fluffy/stud and then open to the attic. Is this correct or what am I missing? I know soundproofing is an all or nothing task. Studs are up now so pressure to get this right now.


----------



## BIGmouthinDC

A double framed wall with one side without drywall doesn't make any sense as a double frame is to keep vibration from transferring from one wall surface to the other, you would have no other surface. so here are your choices:
1) just frame one wall and do the dw/gg/dw on that wall, insulation only on the attic side
2) double framed wall . Add drywall to both walls. The wall framed adjacent to the attic space could get drywall on either side, then the inner framed wall gets your dw/gg/dw.


----------



## Volleyfroebs

My thinking regarding the double wall on the attic walls was to prevent sound transmission through the studs of the attic side and into the sub floor into the rest of the house. So you are saying that won't happen? All the reading has me paranoid about this being all or nothing! I've attached some pictures. First picture will be towards the rear of the room. The valley is definitely not ideal but was unavoidable with the design of the house. Second pic is the screen wall side of the room.


----------



## HT Geek

Ladeback said:


> I only have 2-15' sealed subs corner loaded


2x 15 foot subs? No wonder you feel the rocket launching! LoL.


----------



## HT Geek

deewan said:


> However, with resilient channel the drywall is ¾” (or whatever) away from the wood frame and the bottom plate. If I leave a 1/2” to 5/8” gap between the concrete floor and bottom lip of the drywall I have a HUGE air leak into my walls and a gap large enough that it may be difficult to create a seal with acoustic caulk no matter how much I use.
> 
> What have others done? Used a large bead of acoustic caulk to fill the gap? I’ve thought about finding some sort of small diameter foam rope to set the first layer of drywall onto and then caulk but I’m open for ideas.


Get yourself what is sometimes referred to as, "caulk saver." Open-cell foam. Like this.

Then apply caulk after you shoved this in the gap.










Edit: AKA 'backer rod' as others have mentioned. Frost King calls it 'caulk saver.' Same thing.


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## Ladeback

Volleyfroebs said:


> My thinking regarding the double wall on the attic walls was to prevent sound transmission through the studs of the attic side and into the sub floor into the rest of the house. So you are saying that won't happen? All the reading has me paranoid about this being all or nothing! I've attached some pictures. First picture will be towards the rear of the room. The valley is definitely not ideal but was unavoidable with the design of the house. Second pic is the screen wall side of the room.


There are various ways you can do the walls, ceiling and the floor. Here are some links to Soundproofing Company's website. It depends on how much you want to spend. I would give them a call they, tell them what you want to do and they can point you in the right direction. The one thing that you won't be able to stop with out a lot of effort is the bass. If you have living space below that room like a bed room I would treat the floor as well as the walls and ceiling. It depends on how much you want to keep sound from getting out or in.

http://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-walls/


http://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-floors/

http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/


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## BIGmouthinDC

looking at the pictures I don't see any walls with 100% attic floor to ceiling, I see a lot of structure and ceilings of other spaces all around. Double wall everywhere is probably a good strategy to do your room within a room strategy or clips and channel.


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## Volleyfroebs

Jeff, 
Yes, I would definitely treat the floor. The rear wall and ceiling are the two open to the attic. There are no living spaces directly next to the rear wall or ceiling. Kind of deceiving in the picture. Flanking would be the issue I would think. I guess I'm looking to find out if I'm doing the double stud wall on the rear wall, must the attic side of the wall have mass to be effective? Or, since it connects to the attic space is it OK to only have the mass on the theater side?


----------



## lsturbointeg

SeekingNirvana said:


> @*HT Geek* and @*Ladeback*
> 
> The more I think about it and the more I hear from you guys, it makes me lean to not doing anything at all other than just putting 1 layer of rock on the the existing walls. This seems like an all or nothing approach, and at this time I am not all in. We just bought this house and I thought I could take some budget DIY steps to make the room soundproof. I have read up on this topic and understand the basics of what needs to be done to accomplish a soundproof room but I do not want to spend thousands upon thousands on clips, channel, green glue etc. I have not done the exact math but off the top of my head it would probably around 3-5k  This is money that could be used in other places of the house like new windows, interior doors....I was willing to fork out 5-7 hundred on framing materials and an extra layer of rock but that doesn't sound like it will get me very far.
> 
> With out treating the ceiling the sound will flank to the exterior walls. In my case the exterior walls are the most important as I am trying to keep sound from going to the neighbors. Since the ceiling is directly attached to the exterior walls, adding a secondary wall inside the room would not do much? All of the sound energy would just bypass the secondary walls and transfer to the exterior walls and the roof, which would then radiate out from there. Also the 4th wall is structurally attached to the same exterior walls so sound would flank that way too.
> 
> I had to take the room down to studs regardless of what I did. I just thought while I had it that way I would do some things to help the situation. I'm sure it will be ok if I do nothing....
> 
> Thanks for taking the time to reply


i'm in the same boat as you. i had the mentality of going all out for soundproofing as drywall isn't that expensive but since i've been doing so much research over the last week over hat channels, clips and GG it's just out of my budget when i started adding it all up. i thought using channels from HD would be okay but i could'nt get a solid yes or no from searching? like you i still have to take the existing drywall down to studs so i can do the electrical rough in. i wonder how much of an improvement would be with just Roxul Safe n sound on all walls and batts for the ceiling, DD with GG be? i know i can't eliminate all the noise but i wonder if something is better than nothing? unless there's places to order the hat channels and clips at an economial cost or if there's something cheaper everyone's been using that works?


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## HT Geek

lsturbointeg said:


> i thought using channels from HD would be okay but i could'nt get a solid yes or no from searching?


Well, technically... if you get the 25-gauge from HD, it will work. I believe it's mail-order/Web-order for most stores. Personally, I would get it from a drywall / contractor supply company. You should be able to find one who has it in stock locally and ensure it's the correct gauge. Home Depot calls it 'furring channel.' The key is make sure it's hat channel and NOT RC (Resilient Channel).




> like you i still have to take the existing drywall down to studs so i can do the electrical rough in. i wonder how much of an improvement would be with just Roxul Safe n sound on all walls and batts for the ceiling, DD with GG be? i know i can't eliminate all the noise but i wonder if something is better than nothing? unless there's places to order the hat channels and clips at an economial cost or if there's something cheaper everyone's been using that works?


So, the weird thing about Green Glue is it's been shown in lab tests to actually perform _worse _with GG vs. without when decoupling methods are not used.

Normal interior 2x4 wood stud wall with 1x 5/8" drywall on either side (no insulation) = STC 33 [TL04-277]
1x 5/8 drywall + Pink Fluffy = STC 40 [OL05-1003]
1x 5/8 drywall + Roxul = STC 47 [TL93-327]
2x 5/8 drywall + Roxul = STC *53*
1x 5/8 drywall + Roxul + clips/channel = STC 55-57 (depending on lab test)
2x 5/8 drywall + GG + Pink Fluffy = STC *52*
2x 5/8 drywall + GG + Pink Fluffy + Clips/Channel = STC 60

FWIW, you can see there's some variation in test results between labs. Wider than I'd expect in some cases, so take these figures with a grain of proverbial salt.

Also, those figures are with 1x drywall on the outside of the stud wall. Without that it would be less, but with your attic there no one is going to be hearing it there anyway. What I would think would be important for you is to know if you just do 2x drywall (no GG) vs. 1x drywall, you'll get a +6 bump in STC. DD+GG+clips would be about +20 STC.

Edit: I don't believe there is +7 STC difference between using Roxul vs. pink fluffy. That is what I have in my notes from the lab reports. However, I couldn't locate the report for TL93-327. I'm thinking there must be more to those figures. That's too big a diff to make sense. But I posted them anyway because that's what I could find on short notice. Just a word-of-warning.


----------



## deewan

@lsturbointeg and @SeekingNirvana - I agree soundproofing is not cheap so you need to decide how important it is for you. A couple things to keep in mind, maybe you don't watch movies at reference level. If not, maybe you don't need as much soundproofing and can cut some corners.

If you have time, shop around. Instead of purchasing many items online I've been able to source my Green Glue locally at Menard's. I've purchased 72 tubes of GG for an average of $14.20 a tube (purchased during 11% off sale) compared to the $17-$18 I was finding online. Menards was also a great source for 12' 25-gauge hat channel. And I shopped and shopped and found the lowest price (after shipping) for the clips. 

My room is roughly 14'x28'x9' and I've spent around $3000 on soundproofing but that includes clips on ceiling and walls, clips to decouple the walls, duct putty covering all the junction boxes, 25-gauge hat channel on walls and ceiling, Green Glue (2 tubes per 4x8 sheet), acoustical caulk, 5/8" drywall for two layers on all walls, 5/8" OSB on the ceiling then 5/8 drywall on ceiling and Roxul Safe N Sound for the entire ceiling. While $3000 isn't cheap, I feel for that size of room and the materials used, it isn't bad. 

I could have likely cut a few more corners and obtained similar results while spending less money. Like using pink fluffy insulation instead of Safe N Sound, using drywall on the ceiling instead of OSB or purchasing my drywall from a big box store instead of the Gypsy company who is delivering and carrying into my basement for a fee (but at a 30% price premium). If I would have made those cost savings choices I think the soundproofing would have been still very good and my budget would have been closer to $2600. Another thought, I think using one tube of green glue instead of two tubes for every 4x8 sheet gets you somewhere around 70% of the impact (someone please correct me if I am wrong). Again, depending on your soundproofing goals you could use one tube instead of two and still have everything I listed above for around $2100. Of course there are trade-offs, but knowing your goals first and then sticking to a budget is doable. Best of luck to you both and your rooms!


----------



## lsturbointeg

HT Geek said:


> Well, technically... if you get the 25-gauge from HD, it will work. I believe it's mail-order/Web-order for most stores. Personally, I would get it from a drywall / contractor supply company. You should be able to find one who has it in stock locally and ensure it's the correct gauge. Home Depot calls it 'furring channel.' The key is make sure it's hat channel and NOT RC (Resilient Channel).
> 
> 
> 
> 
> So, the weird thing about Green Glue is it's been shown in lab tests to actually perform _worse _with GG vs. without when decoupling methods are not used.
> 
> Normal interior 2x4 wood stud wall with 1x 5/8" drywall on either side (no insulation) = STC 33 [TL04-277]
> 1x 5/8 drywall + Pink Fluffy = STC 40 [OL05-1003]
> 1x 5/8 drywall + Roxul = STC 47 [TL93-327]
> 2x 5/8 drywall + Roxul = STC *53*
> 1x 5/8 drywall + Roxul + clips/channel = STC 55-57 (depending on lab test)
> 2x 5/8 drywall + GG + Pink Fluffy = STC *52*
> 2x 5/8 drywall + GG + Pink Fluffy + Clips/Channel = STC 60
> 
> FWIW, you can see there's some variation in test results between labs. Wider than I'd expect in some cases, so take these figures with a grain of proverbial salt.
> 
> Also, those figures are with 1x drywall on the outside of the stud wall. Without that it would be less, but with your attic there no one is going to be hearing it there anyway. What I would think would be important for you is to know if you just do 2x drywall (no GG) vs. 1x drywall, you'll get a +6 bump in STC. DD+GG+clips would be about +20 STC.
> 
> Edit: I don't believe there is +7 STC difference between using Roxul vs. pink fluffy. That is what I have in my notes from the lab reports. However, I couldn't locate the report for TL93-327. I'm thinking there must be more to those figures. That's too big a diff to make sense. But I posted them anyway because that's what I could find on short notice. Just a word-of-warning.


thanks for all that info HT! i'm surprised at how the STC is decreased by 1 point when using 2x 5/8 drywall with GG and Pink Fluffy vs 2x 5/8 drywall + Roxul = STC *53. *GG isn't cheap and if you're spending $300 for a 5 gallon bucket and your actually losing 1 point that's just crazy.


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## veger69

Hey guys I need to seal the gaps between a doorframe and the 2x4’s is there a foam sealant that I can pick up at a big box store that would work? I can’t wait for green glue sealant the work has to be done tomorrow.


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## lsturbointeg

deewan said:


> @*lsturbointeg* and @*SeekingNirvana* - I agree soundproofing is not cheap so you need to decide how important it is for you. A couple things to keep in mind, maybe you don't watch movies at reference level. If not, maybe you don't need as much soundproofing and can cut some corners.
> 
> If you have time, shop around. Instead of purchasing many items online I've been able to source my Green Glue locally at Menard's. I've purchased 72 tubes of GG for an average of $14.20 a tube (purchased during 11% off sale) compared to the $17-$18 I was finding online. Menards was also a great source for 12' 25-gauge hat channel. And I shopped and shopped and found the lowest price (after shipping) for the clips.
> 
> My room is roughly 14'x28'x9' and I've spent around $3000 on soundproofing but that includes clips on ceiling and walls, clips to decouple the walls, duct putty covering all the junction boxes, 25-gauge hat channel on walls and ceiling, Green Glue (2 tubes per 4x8 sheet), acoustical caulk, 5/8" drywall for two layers on all walls, 5/8" OSB on the ceiling then 5/8 drywall on ceiling and Roxul Safe N Sound for the entire ceiling. While $3000 isn't cheap, I feel for that size of room and the materials used, it isn't bad.
> 
> I could have likely cut a few more corners and obtained similar results while spending less money. Like using pink fluffy insulation instead of Safe N Sound, using drywall on the ceiling instead of OSB or purchasing my drywall from a big box store instead of the Gypsy company who is delivering and carrying into my basement for a fee (but at a 30% price premium). If I would have made those cost savings choices I think the soundproofing would have been still very good and my budget would have been closer to $2600. Another thought, I think using one tube of green glue instead of two tubes for every 4x8 sheet gets you somewhere around 70% of the impact (someone please correct me if I am wrong). Again, depending on your soundproofing goals you could use one tube instead of two and still have everything I listed above for around $2100. Of course there are trade-offs, but knowing your goals first and then sticking to a budget is doable. Best of luck to you both and your rooms!


this actually gives me hope! everything you wrote sounds like something i can do. where did you buy the clips from and which kind did you go with that will work with the Menard's hat channel as that's the one item i've been trying to find for a decent price. i gave myself a coupl of years to build this Dedicated HT and i can budget that amount you came up with for my first year.


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## HT Geek

lsturbointeg said:


> thanks for all that info HT! i'm surprised at how the STC is decreased by 1 point when using 2x 5/8 drywall with GG and Pink Fluffy vs 2x 5/8 drywall + Roxul = STC *53. *GG isn't cheap and if you're spending $300 for a 5 gallon bucket and your actually losing 1 point that's just crazy.


I agree. It's odd. 

I haven't tried to delve into those details. Just don't have the free time atm. Those figures are from a few databases I have of research into sound proofing and are all pulled from various lab tests done at different times and in different labs. The only thing I can think of is perhaps for some reason GG works better in conjunction with the decoupling provided by clips or a double stud wall. I say that because once you begin looking at those types of structures with and without GG, it's a pretty remarkable improvement using GG. It just seems the 2x + GG on regular studs with no decoupling is an oddball. That said, I believe it's good to know that route is not worthwhile. Someone would be better off doubling up the drywall and calling it a day.


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## HT Geek

lsturbointeg said:


> this actually gives me hope! everything you wrote sounds like something i can do. where did you buy the clips from and which kind did you go with that will work with the Menard's hat channel as that's the one item i've been trying to find for a decent price. i gave myself a coupl of years to build this Dedicated HT and i can budget that amount you came up with for my first year.


Food-for-thought.... You might get a good deal right now being end-of-year, especially if you buy direct from a manufacturer or major distributor.

For example, consider giving PAC International a call (they manufacture the RSIC clips). 866/774-2100.


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## veger69

Can anyone help does spray foam for filling gaps a good sound dampening agent or is gg acoustic caulk the only thing that will work?


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## lsturbointeg

HT Geek said:


> Food-for-thought.... You might get a good deal right now being end-of-year, especially if you buy direct from a manufacturer or major distributor.
> 
> For example, consider giving PAC International a call (they manufacture the RSIC clips). 866/774-2100.


found these and was wondering if that's a good deal for the RSIC's?
https://www.ebay.com/itm/RSIC-1-Resilient-Sound-Isolation-Clip-10-Pack-Noiseproofing-Clip/120916596543?hash=item1c2730d73f:gG4AAOSw9N1VrsEa


also found these for pretty cheap but wasn't sure if the design acceptable $1.79. they kinda look like the same one's sold by SoundProofingCo
https://www.ebay.com/itm/A237-Resil...Noiseproofing-Acoustic-Mounting-/191507456980


same clips 250 clips per box for $447
https://www.ebay.com/itm/A237-Resil...d=191507456980&_trksid=p2047675.c100005.m1851


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## HT Geek

veger69 said:


> Can anyone help does spray foam for filling gaps a good sound dampening agent or is gg acoustic caulk the only thing that will work


The ideas behind filling the gaps are: 1) fill the gap (obviously) to deter airborne sound; and 2) retain elasticity between surfaces so they will 'give' a bit (i.e. flex). So, to answer your question.... Normal spray foam is not ideal, no. Acoustic caulk is the way to go as it performs both functions admirably.


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## HT Geek

lsturbointeg said:


> found these and was wondering if that's a good deal for the RSIC's?
> https://www.ebay.com/itm/RSIC-1-Resilient-Sound-Isolation-Clip-10-Pack-Noiseproofing-Clip/120916596543?hash=item1c2730d73f:gG4AAOSw9N1VrsEa


No. Too expensive.




> also found these for pretty cheap but wasn't sure if the design acceptable $1.79. they kinda look like the same one's sold by SoundProofingCo
> https://www.ebay.com/itm/A237-Resil...Noiseproofing-Acoustic-Mounting-/191507456980


These are the Honda of clips. They work, but BMW clips work better. Lol. The diff is (mostly) the absence of the rubber.




> same clips 250 clips per box for $447
> https://www.ebay.com/itm/A237-Resil...d=191507456980&_trksid=p2047675.c100005.m1851


Same price, so not really any point in buying in bulk IMHO.


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## HT Geek

lsturbointeg said:


> found these and was wondering if that's a good deal for the RSIC's?
> https://www.ebay.com/itm/RSIC-1-Resilient-Sound-Isolation-Clip-10-Pack-Noiseproofing-Clip/120916596543?hash=item1c2730d73f:gG4AAOSw9N1VrsEa


These would be better value. You ought to be able to find them for about $4.50 each if you look around. If you're buying a minimum of 100 units, I would call around to a few distributors and see who will give you a deal.


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## veger69

HT Geek said:


> The ideas behind filling the gaps are: 1) fill the gap (obviously) to deter airborne sound; and 2) retain elasticity between surfaces so they will 'give' a bit (i.e. flex). So, to answer your question.... Normal spray foam is not ideal, no. Acoustic caulk is the way to go as it performs both functions admirably.




Thanks HT


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## deewan

lsturbointeg said:


> also found these for pretty cheap but wasn't sure if the design acceptable $1.79. they kinda look like the same one's sold by SoundProofingCo
> https://www.ebay.com/itm/A237-Resil...Noiseproofing-Acoustic-Mounting-/191507456980



Those are the clips I purchased and have used on my last two builds. They might be the Honda of clips  , but in my opinion the price justifies their performance. The cost for me for the Honda model was $292 instead of $742 for the luxury import. I won't ever know the lack of performance from the lesser clips, but from what I've read sound isolation is pretty solid with the lesser clips, channel, double drywall and green glue. If I am only improving by a few decibels or STC by spending $500 more, it wasn't worth it for me. But that my personal opinion. I am not going for complete sound isolation. I am going for a level that I can watch with modern levels and disturb nobody else in the house.

FWIW I purchased all my clips from TMSoundproofing.com


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## lsturbointeg

deewan said:


> Those are the slips I purchased and have used on my last two builds. They might be the Honda of clips  , but in my opinion the price justifies their performance. The cost for me for the Honda model was $292 instead of $742 for the luxury import. I won't ever know the lack of performance from the lesser clips, but from what I've read sound isolation is pretty solid with the lesser clips, channel, double drywall and green glue. If I am only improving by a few decibels or STC by spending $500 more, it wasn't worth it for me. But that my personal opinion. I am not going for complete sound isolation. I am going for a level that I can watch with modern levels and disturb nobody else in the house.
> 
> FWIW I purchased all my clips from TMSoundproofing.com


if i could afford the BMW i would but i think i'll cut corners on this and go with the Honda lol! big difference in price especially when i can use that difference towards GG. this really helps now that i can cut some cost but still be able to do the 2x 5/8 drywall + GG + Pink Fluffy + Clips/Channel = STC 60. i'll check out TMS...thanks for that! 


on a side note i've seen a few YouTube videos where they added drywall inside the cavity against the other room's drywall making it a DD. does it help or is that a waste of drywall? tho it's not a true DD but wondering if this method helps?


----------



## Claybe

lsturbointeg said:


> if i could afford the BMW i would but i think i'll cut corners on this and go with the Honda lol! big difference in price especially when i can use that difference towards GG. this really helps now that i can cut some cost but still be able to do the 2x 5/8 drywall + GG + Pink Fluffy + Clips/Channel = STC 60. i'll check out TMS...thanks for that!
> 
> 
> on a side note i've seen a few YouTube videos where they added drywall inside the cavity against the other room's drywall making it a DD. does it help or is that a waste of drywall? tho it's not a true DD but wondering if this method helps?


This is a great question as this is what they recommend for ceilings that have traffic above. Interested to hear the response.


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## lsturbointeg

Claybe said:


> This is a great question as this is what they recommend for ceilings that have traffic above. Interested to hear the response.


yes...hopefully the pros will chime in. i've seen them add this to the ceilings under the OSB board (floor) cavities and i've seen them add this to the existing walls where there are bedrooms/bathrooms on the other side. they didn't really explain why they did this other than as part of the install. it makes sense because it than makes it a DD but i'm wondering since it's just the cavities is it a true DD? i'm not sure if they used GG on the drywall being attached? so it would end up being DD/Roxul/clips/hat/DD/GG would be the end result.


----------



## deewan

lsturbointeg said:


> on a side note i've seen a few YouTube videos where they added drywall inside the cavity against the other room's drywall making it a DD. does it help or is that a waste of drywall? tho it's not a true DD but wondering if this method helps?


Anytime you can add mass to a wall or ceiling, you will likely improve the soundproofing. In this case adding drywall with a layer of green glue will help add mass. I had given it some thought but decided against it. I think the soundproofing company has stats on their site on how much higher a STC value you get if you put that layer on the bottom side.


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## lsturbointeg

from a local supplier:


*Gene the RSIC-1 isolation clips come either in 100 PCS or 300 PCS counts. Unfortunately the manufacture does not offer price breaks on clips. Price for the 100 PCS pail is $500.00 or 300 PCS pail $1500.00, lead time is 1-2 business days. Let me know if you have any other questions.*

OUCH!


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## deewan

lsturbointeg said:


> from a local supplier:
> 
> 
> *Gene the RSIC-1 isolation clips come either in 100 PCS or 300 PCS counts. Unfortunately the manufacture does not offer price breaks on clips. Price for the 100 PCS pail is $500.00 or 300 PCS pail $1500.00, lead time is 1-2 business days. Let me know if you have any other questions.*
> 
> OUCH!


That is about the going rate for the BMW clip.  Like I said above, I went with the clip without the rubber gasket to save several hundred dollars and it appeared the trade-offs weren't that much. The average rate for the clip without the rubber gasket is closer to $1.80 with a minimum order of 50 (then any increment), instead of the $5.00 for the rubber gasket clip.


----------



## jjackkrash

FWIW, the soundproofingcompany folks talked be out of the more expensive clips. They indicated that rubber clips holding the hat channel offer "some benefit" over the standard clips, but not a very big benefit.


----------



## dchabby

Hi all - soundproofing newb here just looking for a little advice.

I have an area in my basement that is about 13' x 14' and I am thinking about building a room in this area that will be about 12' x 12'.

Now I was thinking about building it as a freestanding room so it would not be attached to any other walls or the ceiling, the only place it will touch the house obviously will be the concrete floor.

I assume this will work better for soundproofing than using clips/channels, am I correct in this assumption ?

And would there be any concern with the integrity of the room building it this way as there wont be any support from the other walls ?

For the green glue - I saw it mentioned to use 2 tubes per 4' x 8' sheet of drywall - is that the recommended amount ?

I don't need 100% complete soundproofedness but would like to be as close to that as possible so would I need to DD w/GG on the outside walls or would doing that inside be enough ?

I am just trying to get a budget in mind for this project to see if it is something I can move forward with.

Thanks in advance !


----------



## HT Geek

dchabby said:


> Hi all - soundproofing newb here just looking for a little advice.
> 
> I have an area in my basement that is about 13' x 14' and I am thinking about building a room in this area that will be about 12' x 12'.


A square shape is bad for sound. It enhances negative effects such as reflections (echoes). 13x14 would be better. Almost anything that is not a perfect square will be better than a square. I supposed a perfect cube is the worst-case scenario.




> Now I was thinking about building it as a freestanding room so it would not be attached to any other walls or the ceiling, the only place it will touch the house obviously will be the concrete floor.
> 
> I assume this will work better for soundproofing than using clips/channels, am I correct in this assumption ?


Depends on the details, but conceptually if you're talking about a room-within-a-room with independent walls (double walls) and a floating ceiling, then yes.




> And would there be any concern with the integrity of the room building it this way as there wont be any support from the other walls ?


You have to find a way to secure it structurally. If you bolt your footer boards to the floor, it's possible you could make it structurally sound. That would be no different than building a shed on a concrete foundation in your yard (for example). However, the standard approach is to attach it to the structural ceiling/walls via clips (such as these IB-3 clips).













> For the green glue - I saw it mentioned to use 2 tubes per 4' x 8' sheet of drywall - is that the recommended amount ?


Yes. However, to save $ some people use 1 tube per 4x8. I've heard reference to 70% attainment of the sound-dampening from 2 tubes, but I can't verify that information.




> I don't need 100% complete soundproofedness but would like to be as close to that as possible so would I need to DD w/GG on the outside walls or would doing that inside be enough ?


DD+GG on the wall surfaces on the inside of the HT room is the gold standard. Using DD+GG on the walls in an adjacent room with a wall shared with the HT room would improve your sound dampening further.


----------



## dchabby

HT Geek said:


> A square shape is bad for sound. It enhances negative effects such as reflections (echoes). 13x14 would be better. Almost anything that is not a perfect square will be better than a square. I supposed a perfect cube is the worst-case scenario.
> 
> 
> 
> 
> Depends on the details, but conceptually if you're talking about a room-within-a-room with independent walls (double walls) and a floating ceiling, then yes.
> 
> 
> 
> 
> You have to find a way to secure it structurally. If you bolt your footer boards to the floor, it's possible you could make it structurally sound. That would be no different than building a shed on a concrete foundation in your yard (for example). However, the standard approach is to attach it to the structural ceiling/walls via clips (such as these IB-3 clips).
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Yes. However, to save $ some people use 1 tube per 4x8. I've heard reference to 70% attainment of the sound-dampening from 2 tubes, but I can't verify that information.
> 
> 
> 
> 
> DD+GG on the wall surfaces on the inside of the HT room is the gold standard. Using DD+GG on the walls in an adjacent room with a wall shared with the HT room would improve your sound dampening further.


Thank you very much HTG !

I am aware about the best shape for a room, I was just throwing out those numbers as a general idea of what I wanted to do.

By floating ceiling are you referring to the fact it wont be connected to the floor above ?


----------



## lsturbointeg

jjackkrash said:


> FWIW, the soundproofingcompany folks talked be out of the more expensive clips. They indicated that rubber clips holding the hat channel offer "some benefit" over the standard clips, but not a very big benefit.


thank you for that!


----------



## HT Geek

dchabby said:


> By floating ceiling are you referring to the fact it wont be connected to the floor above ?


That it won't be directly connected. The IB-3 clips are considered an indirect attachment for this purpose. IOW, with a floating ceiling, the ceiling joists of your HT room will not be directly attached to the structural ceiling of the original room. The IB-3 clips provide some connection to keep your room-within-a-room connected to the home's structure. This prevents future issues such as your room-within-a-room shifting laterally (and cracked drywall, etc. as a result).

The downside to this approach is it lowers your ceiling quite a bit. For starters, you need to calculate the ceiling load and choose a suitable size beam for your joists. Let's use 2x6 as an example (and which is the size for most 12' spans, but it depends on how much weight they will hold). So, a 2x6 standing vertical is 5.5" tall. Your joists will almost always need to be laid vertically to support the weight because wood beams are significantly stronger vertically when it comes to resisting shear force (gravity pulling them downward).

So, then you need an air gap between your floating ceiling and the structural ceiling above. Let's say 1", which is a good figure since it gives you a little wiggle room to account for minor imperfections in the original ceiling (i.e. if it's not completely level, which it probably isn't). That's a total drop of 6.5" below your original ceiling joists, and that is also before you've added drywall to the ceiling. Two layers of drywall = 2x 5/8" = 1-1/4". Add a little wiggle room for Green Glue... say, 1/4" (should be less). Now, we're at a total height drop of 5-1/2" + 1" + 1-1/4" + 1/4" = 8" drop in height from the structural ceiling joists.

Compare that with clips: Clip height + 1-1/4" drywall + 1/4" GG = 3" to 3-1/2" or so drop from structural ceiling joists (depending on the clip).

Do you see where I'm going with this? Your pre-existing room height plays a huge part in whether or not a floating ceiling is an option to begin with. Most building codes will require a minimum of 7' of room height when the room is finished. Some jurisdictions (such as NJ - IIRC) measure from the finished floor surface. And some (such as most counties in Texas where I live) will allow taking the measurement when there's no floor covering in yet (i.e. you can get your final building inspection done before the floor's finished as long as the sub-floor is in).

So, to re-cap... what are the factors that determine if you CAN do a floating ceiling?

Total rough floor-to-ceiling distance
Height of floating ceiling joists
Air gap between floating ceiling joists and structural ceiling joists
Floor height
Ceiling covering (e.g. drywall) height

Will you have a minimum of 7' headroom remaining? Note: if you have a riser, and if the riser is NOT directly affixed to the walls, technically it is an accessory/furniture and not structural, which means it will not adversely affect your headroom calculation. However, if it IS directly affixed to the walls then it will be counted as your floor-to-ceiling height. You may have to argue this with a building inspector if you get one who is being an asshat, but the international residential building code (IRBC) supports that position when interpreted correctly.

I hope that's not overwhelming for you. An easy way to think of it is don't even consider a floating ceiling unless you have a minimum of 8' floor-to-ceiling height when your room has been gutted down to the studs.


----------



## dchabby

^^ Thanks again HTG !

Right now I have 7.5' between the floor and ceiling and I wasn't planning on gutting the current ceiling but may rethink that.

This is going to be a very simple build, nothing fancy like risers if I do go ahead with it.


----------



## HT Geek

dchabby said:


> ^^ Thanks again HTG !
> 
> Right now I have 7.5' between the floor and ceiling and I wasn't planning on gutting the current ceiling but may rethink that.
> 
> This is going to be a very simple build, nothing fancy like risers if I do go ahead with it.


Gotcha. In that case, consider doing clips & channel on the ceiling. You should still have 7' minimum height clearance afterwards if you do.


----------



## BSHuff

Question regarding IB3 clip orientation for double stud walls?

I have seen various pictures of the IB3 clips used in many different orientations. Is there a best practice for installing them when fastening the top of a double stud wall? 

I see 'hanging' the top of the wall from the ceiling joist to top plate like the picture a few comments back. So the elastomer is in shear. 

I have also seen pics of them installed like an IB4 clip but to blocking/studs on the 'back' wall so the elastomer is in more compression. 


Or am I just splitting hairs here and using them is all that really matters?


----------



## Ladeback

BSHuff said:


> Question regarding IB3 clip orientation for double stud walls?
> 
> I have seen various pictures of the IB3 clips used in many different orientations. Is there a best practice for installing them when fastening the top of a double stud wall?
> 
> I see 'hanging' the top of the wall from the ceiling joist to top plate like the picture a few comments back. So the elastomer is in shear.
> 
> I have also seen pics of them installed like an IB4 clip but to blocking/studs on the 'back' wall so the elastomer is in more compression.
> 
> 
> Or am I just splitting hairs here and using them is all that really matters?


From what I remember what I was told if you do with a double stud wall is your outside wall is built like normal from floor to ceiling, then you have at least a 1/2" gap between the walls and the inner walls can be fastened fro the top plate to ceiling joist with the IB-3 clips. You want one about 3 to 6 inches from the ends and the rest spaced no more then 4' apart. You want an extra one or two over doorways. You can fastened them from the outer wall in inner wall, but you will use more and they are about $6 a pices or so. You would want to fastened the bottom plate to the floor like normal so doesn't moved. @HTGeek can tell you more.


----------



## HT Geek

BSHuff said:


> Or am I just splitting hairs here and using them is all that really matters?


Basically, yep. 

It doesn't matter how you orient them from the standpoint of which surface the rubber portion is attached to. An important factor is allowing yourself the ability to adjust the position of the clip at the top of your inner room. Before you permanently secure the clips you'll want to use a level to ensure the wall is plumb and square. You work your way around the room doing this. So, the orientation of the clips has a lot to do with the angle you're able to access the screw holes with a drill. A flexible drill bit extender is helpful to have handy. 




Ladeback said:


> From what I remember what I was told if you do with a double stud wall is your outside wall is built like normal from floor to ceiling, then you have at least a 1/2" gap between the walls and the inner walls can be fastened fro the top plate to ceiling joist with the IB-3 clips. You want one about 3 to 6 inches from the ends and the rest spaced no more then 4' apart. You want an extra one or two over doorways. You can fastened them from the outer wall in inner wall, but you will use more and they are about $6 a pices or so. You would want to fastened the bottom plate to the floor like normal so doesn't moved. @HTGeek can tell you more.


Right on. 

You literally frame a box, just like a normal room. The clips make sure it remains square and plumb when you're finished. If you follow Ladeback's guidelines, your room will be rock solid. I was amazed at how rigid mine was after the clips were installed (even at ~4' apart).


----------



## Ladeback

When I built my current walls with no clips, I got them straight and plumb as possible and attached them at the top first. It was easier to do the final fastenin to the floor in my basement with a ramset to the concrete. Now depending on how you install the IB-3 clips it could be easier to make sure they are plumb and fastened at the bottom then at the top. I was able to do my walls by myself, but with the clips you may need someone to hold the wall while get it straight and plumb while you fastened it down.


----------



## BSHuff

Thanks @Ladeback and @HTGeek. Part of the issue I have in my room is that it is an attic with a 10 foot wall that tapers down to a 4' wall on the other side of the room over ~16 feet. In order to get the 12" cavity needed for code insulation there is some creative framing needed around the edges to satisfy fireblocking & insulation yet still allowing the double stud walls. There will be a mix of both orientations of clips to make it work. Glad both are OK methods. 

I have my walls currently sound-shorted/connected together with some OSB gussets at the tops of the studs so the walls are plumbed/square. The clips came in this weekend and the plan is to add the clips with the shorting braces still installed. Once I have all the clips in, I will remove the OSB gussets and hope the walls stay reasonably where they were with the gussets.


----------



## HT Geek

BSHuff said:


> The clips came in this weekend and the plan is to add the clips with the shorting braces still installed. Once I have all the clips in, I will remove the OSB gussets and hope the walls stay reasonably where they were with the gussets.


Just use a 4' bubble level. Plus a laser level helps if you have one or can borrow one.

It will all be worth it in the long run. Keep us posted, and share your build thread link if/when you have one.


----------



## deewan

The floor of my basement is a concrete slab. I understand low frequencies are easily transmitted from a sub sitting on a concrete floor to the structure of the room. To help prevent the bass notes from traveling through the floor and into the structure I’ve been giving some thought about using DRIcore subfloor panels. The DRICore panels have the added benefit of giving a warmer feel to the floor during the cold Iowa winters. 

I’ve also considered some sort of stage up front for the speakers and subs to sit on. My room design does not include a front stage, but I could create a shallow stage hidden behind my AT wall if I decide against the DRIcore. If I go with a stage I'd like to avoid having to fill the stage with bags and bags of dry sand.

Maybe just rubber mats for the speakers and subs to sit on?

What is the best practice for people on this forum who’ve had similar setups and concerns?


----------



## HT Geek

deewan said:


> The floor of my basement is a concrete slab. I understand low frequencies are easily transmitted from a sub sitting on a concrete floor to the structure of the room. To help prevent the bass notes from traveling through the floor and into the structure I’ve been giving some thought about using DRIcore subfloor panels. The DRICore panels have the added benefit of giving a warmer feel to the floor during the cold Iowa winters.
> 
> I’ve also considered some sort of stage up front for the speakers and subs to sit on. My room design does not include a front stage, but I could create a shallow stage hidden behind my AT wall if I decide against the DRIcore. If I go with a stage I'd like to avoid having to fill the stage with bags and bags of dry sand.
> 
> Maybe just rubber mats for the speakers and subs to sit on?
> 
> What is the best practice for people on this forum who’ve had similar setups and concerns?


A concrete floor - provided it's a thick slab with dirt under it - will actually give you very good performance. That's especially true if you have carpet on top of the concrete. The funny thing about concrete is while it's great at dispersing sound in that scenario, it's also very good at reflecting sound. However, again once you throw carpet and pad over it, there's a big (positive) difference. Impact sound is a bit more of a challenge, but the density of the concrete slab will absorb it better than anything else.

A stage will 'deaden' your room a bit more from an impact sound standpoint. I would think that would probably be the biggest pro of using a stage in your case from a functional perspective; i.e. if you want to reduce impact vibrations and orient your subs so more of their energy is directed as airborne sound.


----------



## lsturbointeg

HT Geek said:


> A concrete floor - provided it's a thick slab with dirt under it - will actually give you very good performance. That's especially true if you have carpet on top of the concrete. The funny thing about concrete is while it's great at dispersing sound in that scenario, it's also very good at reflecting sound. However, again once you throw carpet and pad over it, there's a big (positive) difference. Impact sound is a bit more of a challenge, but the density of the concrete slab will absorb it better than anything else.
> 
> A stage will 'deaden' your room a bit more from an impact sound standpoint. I would think that would probably be the biggest pro of using a stage in your case from a functional perspective; i.e. if you want to reduce impact vibrations and orient your subs so more of their energy is directed as airborne sound.


so reading this you guys got me thinking about my floors. since my HT sits above the garage i'm able to budget Roxul/clips/hat channel/DD/GG on all 4 walls/ceiling but am i still gonna have issues with the floor not being done at all? right now it's carpet but i will be building a riser and from reading through the forums i have yet to get a solid answer on whether to leave the carpet and build the riser on top of it and adding carpet or remove all the carpet and build directly on the subflooring? but now this post has got me thinking about my floors. it's not concrete so i don't have that density. it is above the garage so i'm not worried about noise transmitting into the garage. do you guys advise on getting some kind of absorbing material/padding on top of the sub flooring and than normal carpet pad and carpet or should i just leave as is? it would suck to spend all this money on soundproofing the room only to realize my floor will null everything i've done


----------



## jjackkrash

lsturbointeg said:


> it is above the garage so i'm not worried about noise transmitting into the garage. do you guys advise on getting some kind of absorbing material/padding on top of the sub flooring and than normal carpet pad and carpet or should i just leave as is? it would suck to spend all this money on soundproofing the room only to realize my floor will null everything i've done


The problem is going to be flanking through the floor.

http://www.soundproofingcompany.com/soundproofing101/flanking-and-indirect-sound-leaks/


----------



## lsturbointeg

jjackkrash said:


> The problem is going to be flanking through the floor.
> 
> http://www.soundproofingcompany.com/soundproofing101/flanking-and-indirect-sound-leaks/


ugh! this really sux! thanks for the link tho as it really explains flanking and the options for soundproofing the floor. this really is discouraging as you'd like to do whatever you can to help with the noise getting into other rooms and i thought doing the walls and ceilings would be enough but there's a point to where it's just not doable anymore. i'm not into 100% soundproofing a room but thought doing some kind of soundproofing will help without breaking the bank. i've learned with a bit of research on this topic of soundproofing that it's almost an all or nothing when it comes to sound proofing.


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## Ladeback

lsturbointeg said:


> ugh! this really sux! thanks for the link tho as it really explains flanking and the options for soundproofing the floor. this really is discouraging as you'd like to do whatever you can to help with the noise getting into other rooms and i thought doing the walls and ceilings would be enough but there's a point to where it's just not doable anymore. i'm not into 100% soundproofing a room but thought doing some kind of soundproofing will help without breaking the bank. i've learned with a bit of research on this topic of soundproofing that it's almost an all or nothing when it comes to sound proofing.


I see you are building above your garage and it looks like your plan for the walls and ceiling are good to me and what I plan to do in my HT that is in my basement. As for flanking into the garage, is that a big issue since people won't spend a ton of time there when you or someone else is using the HT. You could put down another layer of sub floor with Green glue, then a good thick pad and carpet. I think that would help. I would also not take the new subfloor all the way to the walls. leave at least a 1/4" to a 1/2" gap and fill it with acoustical caulking. This should help with flanking I would think.

You also asked about building the riser eiher on the sub floor or the carpet. I was orginally thinking of build a riser on my conrete floor, but I am thinking of building it on top of the carpet. I currently have a 120" fixed 16:9 screen and I eventually want to go to a AT scope screen so either I build for it nor or make it so I can move the riser a later date. Also if you ever sell your house and the riser is on top of the carpet the new owners could take it out if they want. I have seen it done both ways.

I may have missed it, but what do you have for subs? Are you doing a AT screen with the speakers behind it?


----------



## HT Geek

Ladeback said:


> I see you are building above your garage and it looks like your plan for the walls and ceiling are good to me and what I plan to do in my HT that is in my basement. As for flanking into the garage, is that a big issue since people won't spend a ton of time there when you or someone else is using the HT. You could put down another layer of sub floor with Green glue, then a good thick pad and carpet. I think that would help. I would also not take the new subfloor all the way to the walls. leave at least a 1/4" to a 1/2" gap and fill it with acoustical caulking.


^^^ Agreed.




jjackkrash said:


> The problem is going to be flanking through the floor.





lsturbointeg said:


> so reading this you guys got me thinking about my floors. since my HT sits above the garage i'm able to budget Roxul/clips/hat channel/DD/GG on all 4 walls/ceiling but am i still gonna have issues with the floor not being done at all? right now it's carpet but i will be building a riser and from reading through the forums i have yet to get a solid answer on whether to leave the carpet and build the riser on top of it and adding carpet or remove all the carpet and build directly on the subflooring?


I wouldn't be too concerned with the floor given the fact the garage is beneath it. Though it's more likely to be a flanking path if the floor joists beneath your room are connected to other parts of the home's structure.

As Ladeback suggested, you could partially mitigate this issue by raising your sub-floor a bit and as he said keep it a small distance from the walls. Caulk the gap. I did this in my build, and my room is also above the garage. I added 2 staggered layers of 5/8" OSB onto the original sub-floor. One of the downsides to this approach is it raises your floor (obviously). In my case, one enters the room at riser height. I did that for two reasons: 1) it takes care of the raised sub-floor/lip; and 2) that was the only feasible place to put the back row seats unless I wanted either just 1 row of seating or have people walking in front of the screen when they entered the room.

Your *best* option would be to rip up your sub-floor and install rubber U-boats or use some other method of decoupling your floor. I thought about that and decided it was way too much work, and not worth the end result considering the fact the garage is below. I considered it because the floor joists in the HT room do connect with an adjacent bedroom. However, I decided the occupant of that room will just have to deal with it. 

One more idea.... RIM. It's also very effective in the 2" or deeper size, however it would of course raise the sub-floor even more. And then there's the ceiling height to worry about.


----------



## lsturbointeg

i decided to go forward and at least do the walls and ceiling like i planned. as for the floors ef it lol! i think i feel comfortable knowing i did some kind of SoundProofing than nothing at all. will let you guys know the progress. oh, what i did want to ask is am i better off saving a bit going with the pink fluffy stuff which i think is just normal insulation correct over the Roxul SafenSound? seems like all the YouTube videos i've been watching say this is fine


----------



## Ladeback

lsturbointeg said:


> i decided to go forward and at least do the walls and ceiling like i planned. as for the floors ef it lol! i think i feel comfortable knowing i did some kind of SoundProofing than nothing at all. will let you guys know the progress. oh, what i did want to ask is am i better off saving a bit going with the pink fluffy stuff which i think is just normal insulation correct over the Roxul SafenSound? seems like all the YouTube videos i've been watching say this is fine


I think you will be fine going with pink fluffy insulation, that's what The Soundproofing Company suggest to be used. That's what I am thinking of using.


----------



## HT Geek

lsturbointeg said:


> i decided to go forward and at least do the walls and ceiling like i planned. as for the floors ef it lol! i think i feel comfortable knowing i did some kind of SoundProofing than nothing at all. will let you guys know the progress. oh, what i did want to ask is am i better off saving a bit going with the pink fluffy stuff which i think is just normal insulation correct over the Roxul SafenSound? seems like all the YouTube videos i've been watching say this is fine


Yes. I'd suggest using pink fluffy. It's the cheapest solution. Technically Roxul outperforms pink fluffy by 1 STC. However, there are very few true comparisons, so it's contentious as to whether that is true after someone has taken other measures such as clips & channel or a double stud wall, etc. My point is IMHO, it's not worth the extra cost of Roxul. Even if you could be assured of 1 STC improvement, the cost/performance ratio isn't worth it.

That being said, I've used both, but that was for other reasons. Most of my room has pink fluffy where insulation was used.


----------



## jjcook

Questions about in-wall speakers and subwoofers:

1) I've seen for enclosed in-wall speakers (e.g., Triad) the common methods are to build a backer box and either attach the backer to the drywall/furring channel (maybe with additional local clips/channel) or to attach backer box to studs with IB3 clips and keep it decoupled from the drywall as well. Which method is better and why?

2) What have others done for (DIY) in-wall (or floor supported but wall recessed) subwoofers in small rooms without compromising the overall soundproofing? My room is only 10' deep studs-to-studs (and 15' wide) and I would like to have subwoofers along the front wall and rear wall (and maybe along the side wall) for mode smoothing -- as my seating will need to be close to the rear wall there won't be much depth behind the HT recliner seating (8-12" ?). I recall @granroth had considered in-column subwoofers...

2b) As another option, in-ceiling could work as the attic is above my ceiling so space is less of an issue there but I'll need to figure out how to add joist support (strongbacks/other) for the additional weight and more so how to minimize vibration transfer. I'd assume if the sub is sitting on my floor (I-joist, subfloor, rubber mat, 3/8 plywood + GG + 3/8 plywood, carpet) inside my soundproof shell (IB-2 clips) it will dampen the sub's cabinet vibration and sound energy better than IB3 clips in attic outside the shell??


----------



## donktard

Any of you guys using mass loaded vinyl as a layer of insulation? I am looking for best soundproofing performance for the least wall thickness possible, so I am looking for best options.


----------



## HT Geek

donktard said:


> Any of you guys using mass loaded vinyl as a layer of insulation? I am looking for best soundproofing performance for the least wall thickness possible, so I am looking for best options.


Not many of us have used it. MLV is difficult to work with and can be easily short-circuited by accident (and by virtue of incorrect application). 

I'd suggest searching the forum thoroughly. It does provide some benefits (if installed properly), but it's not very great. However, if installation wall depth is at a premium, it may be worth considering.


----------



## SeekingNirvana

Ladeback said:


> From what I remember what I was told if you do with a double stud wall is your outside wall is built like normal from floor to ceiling, then you have at least a 1/2" gap between the walls and the inner walls can be fastened fro the top plate to ceiling joist with the IB-3 clips. You want one about 3 to 6 inches from the ends and the rest spaced no more then 4' apart. You want an extra one or two over doorways. You can fastened them from the outer wall in inner wall, but you will use more and they are about $6 a pices or so. You would want to fastened the bottom plate to the floor like normal so doesn't moved. @HTGeek can tell you more.


It sounds like you would only use the clips at the top of the wall? This is what I am thinking......but I have heard that you use the clips like you would if you were using the clips for hat channel. So it would be every 4' but throughout the entire wall? 

I am planning on building a inner wall on a slab and anchoring the bottom sill to the floor with concrete wedge anchors. To me the IB3 clips would just hold the wall upright and plumb.


----------



## HT Geek

SeekingNirvana said:


> It sounds like you would only use the clips at the top of the wall? This is what I am thinking......but I have heard that you use the clips like you would if you were using the clips for hat channel. So it would be every 4' but throughout the entire wall?
> 
> I am planning on building a inner wall on a slab and anchoring the bottom sill to the floor with concrete wedge anchors. To me the IB3 clips would just hold the wall upright and plumb.


Right. Depends on implementation. You should be good if it is well secured top and bottom. I would use some clips (spaced vertically) in the corners, to help ensure it remains square over time.


----------



## veger69

Oops wrong fourm


----------



## bubbrik

Hi All

When putting up second layer of drywall on the walls with green glue, would the green glue drip? When we did the second layer on the ceiling, dripping wasn’t a problem but I’m worried that it would drip when we turn the boards sideways. Are there any tips to prevent any dripping?

Thanks


Sent from my iPhone using Tapatalk


----------



## HT Geek

bubbrik said:


> Hi All
> 
> When putting up second layer of drywall on the walls with green glue, would the green glue drip? When we did the second layer on the ceiling, dripping wasn’t a problem but I’m worried that it would drip when we turn the boards sideways. Are there any tips to prevent any dripping?


I'd say there's always a possibility. However, from my experience Green Glue is not particularly problematic. As long as you apply the outer GG backed drywall and screw it into place immediately afterwards, and use a sufficient number of screws (i.e. standard installation), you should be fine.

That said, I've had terrible experiences with Quiet Glue (QG Pro). I do NOT recommend that particular product. I've had it pool terribly at the bottom of vertical sheets months after initial installation. It was so bad that I decided to postpone carpet installation until I was certain that damn stuff was done oozing. I'll never use it again on vertical surfaces.


----------



## bubbrik

HT Geek said:


> I'd say there's always a possibility. However, from my experience Green Glue is not particularly problematic. As long as you apply the outer GG backed drywall and screw it into place immediately afterwards, and use a sufficient number of screws (i.e. standard installation), you should be fine.
> 
> 
> 
> That said, I've had terrible experiences with Quiet Glue (QG Pro). I do NOT recommend that particular product. I've had it pool terribly at the bottom of vertical sheets months after initial installation. It was so bad that I decided to postpone carpet installation until I was certain that damn stuff was done oozing. I'll never use it again on vertical surfaces.




Thank you @HT Geek
Since I will be using Green Glue, I’ll follow your advice and see how it goes.


Sent from my iPhone using Tapatalk


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## HT Geek

bubbrik said:


> Thank you @HT Geek
> Since I will be using Green Glue, I’ll follow your advice and see how it goes.


Sure thing.... And I should have clarified a couple things in your case...

1. By "immediately" what I meant was soon after. Just don't let it sit overnight, etc. Not that you'd be likely to do that anyway. 

There's no urgent need to slap it up in 5 seconds or whatever. I didn't intend to give you that impression, if I did.

2. You may want to try installing one sheet and then stop, and let it sit overnight and check it. If you do have any issues, just go a little lighter with the GG toward the bottom end of the sheet.

I suspect you won't have any issues, but it's tough to say for sure since there are a number of variables. And FYI, it will take ~30 days for it to completely dry, at which point it your 2x drywall sheets + GG will act like one massively thick sheet of drywall. It needs to cure though. Sort of like concrete.

But like I said earlier, if you have the two layers of drywall squeezed tight (with screws of course) then you should not have any issues.

Anyway, apologies on my ramblings here. Just trying to be thorough!


----------



## bubbrik

HT Geek said:


> Sure thing.... And I should have clarified a couple things in your case...
> 
> 
> 
> 1. By "immediately" what I meant was soon after. Just don't let it sit overnight, etc. Not that you'd be likely to do that anyway.
> 
> 
> 
> There's no urgent need to slap it up in 5 seconds or whatever. I didn't intend to give you that impression, if I did.
> 
> 
> 
> 2. You may want to try installing one sheet and then stop, and let it sit overnight and check it. If you do have any issues, just go a little lighter with the GG toward the bottom end of the sheet.
> 
> 
> 
> I suspect you won't have any issues, but it's tough to say for sure since there are a number of variables. And FYI, it will take ~30 days for it to completely dry, at which point it your 2x drywall sheets + GG will act like one massively thick sheet of drywall. It needs to cure though. Sort of like concrete.
> 
> 
> 
> But like I said earlier, if you have the two layers of drywall squeezed tight (with screws of course) then you should not have any issues.
> 
> 
> 
> Anyway, apologies on my ramblings here. Just trying to be thorough!




I was more worried about it dripping when we lift the board sideways to hang it than it squeezing out after the screws are driven in. I originally thought the ceiling would be a pain but it went uneventful. I’m hoping the same with the walls. 

Since this is my first time, your clarifications are very helpful. I’ll also try the one board first and use that to help decide on the quantity of GG to use especially towards the bottom edges. Thanks again @HT Geek for your time.


Sent from my iPhone using Tapatalk


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## Badbird

Hi. First post here, been lurking for a few weeks. Currently getting my feet wet on a home theater build. Unfinished basement in a new home.

I have access to a product that is used as an underlay for tile. It is a sound proofing membrane. It can be applied over a variety of substrates; OSB, concrete and drywall. I wonder how it would do between to layers of drywall or a layer of osb and dry wall. Its a peal and stick product, I was thinking of maybe even using it to line the insides of my joist bays in the ceiling.

Its sound reduction is listed as "Sound reduction: IIC: 71*; STC: 72*" I don't know what that means, perhaps someone here can weigh in?

I cannot post a link (I'm too new) but product is "Flextile 2000 SC"


----------



## HT Geek

Badbird said:


> Hi. First post here, been lurking for a few weeks. Currently getting my feet wet on a home theater build. Unfinished basement in a new home.
> 
> I have access to a product that is used as an underlay for tile. It is a sound proofing membrane. It can be applied over a variety of substrates; OSB, concrete and drywall. I wonder how it would do between to layers of drywall or a layer of osb and dry wall. Its a peal and stick product, I was thinking of maybe even using it to line the insides of my joist bays in the ceiling.
> 
> Its sound reduction is listed as "Sound reduction: IIC: 71*; STC: 72*" I don't know what that means, perhaps someone here can weigh in?
> 
> I cannot post a link (I'm too new) but product is "Flextile 2000 SC"


First off, welcome to the "club".  Now that you've been bitten by the bug, prepare to spend copious amounts of time and money. LoL. 

Well, it's certainly possible this product could be useful. However, to quantify whether or not that is true would require considerable diligence and research. The products you've presumably read about on this forum have been vetted via thousands of real-world use cases and dozens of lab tests. If you want to seriously consider the Flextile product, I'd advise you to first make certain you understand exactly what materials would be required for implementation. Second, ask yourself if it's realistic to expect those materials to stay in place vertically (on a wall) and on a ceiling, both while resisting gravity's force (which is shear force for vertical surfaces and direct gravitational pull for horizontal surfaces).

After you've ascertained the suitability of the material for a HT room construction environment, figure out the total cost including labor if applicable.

If all of that looks good, the next step I'd recommend is to take a good look at any lab tests (I see this product purportedly has some, though the manufacturer fails to disclose the details and suggests in their datasheet you should contact them directly if you want the info - do so). Compare the lab test environment to what yours would be. How closely do they correlate?

This part is usually the zinger that when examined realistically, typically kills an idea. If you can't find lab tests that mimic acoustic chambers with measurements on both send and receive sides of a surface, and if drywall wasn't used in some capacity, or if the material in question was not sandwiched in between drywall, then all bets are off and I would suggest you abandon the idea.

Most products are purpose-built for the use they are advertised for and don't perform as well in other uses. The datasheet mentions it was tested over 8" concrete slab with a "sound rated ceiling." I don't know what the latter means. I know what 8" of concrete is. I also see other portions of the document indicate application instructions that are quite specific, yet the "Sound Performance" section fails to mention those techniques. Were they also used to attain the quoted sound attenuation results? Based on this document, we don't know. In short, be very skeptical of such documents. You need to get your hands on the real lab test results (all pages).

The general consensus on this Board is don't waste your time with such products. There are a small number of tried-and-true techniques, and you'll find many examples of implementation of them on this forum. Trust me, your time and energy will be better spent figuring out other challenges. Even if you could save money with this alternative product, you're highly likely risking unknown consequences of performance, and the sound-proofing product is just a small portion of your overall cost of building out a room, equipment, furniture, etc.

If you are under budget constraints, you can choose to forego some items including Green Glue or similar products. Drywall is cheap. Of course, much depends on your overall goals, but as an example you'll get more bang-for-your-buck spending money on clips & hat channel and forgoing Green Glue versus the other way around.


----------



## HT Geek

Badbird said:


> Its sound reduction is listed as "Sound reduction: IIC: 71*; STC: 72*" I don't know what that means, perhaps someone here can weigh in?


IIC = Impact Insulation Class

STC = Sound Transmission Class

IIC measures reduction in impact noise, such as dropping a hammer on a floor above a room.

STC measures sound transmission through a surface, such as a wall.

They are both weighted, relative measurements. IOW, they are useful when comparing two products where you have IIC or STC values for each product. The higher the value product will ostensibly be "better" than the product with the lower number. However, as is most often the case in the world of acoustics, it's not truly that simple. 

First off, IIC and STC are lab result figures where the entire environment is controlled. Second, they only measure a portion of the human spectrum of audible sound. Third, the system uses a weighted analysis method that tends to result in stronger weighting of higher frequency attenuation. So? Why does this matter? In a typical home environment, that's not a big deal because if you are a home builder trying to meet EPA sound requirements, most of the portion of the human-audible spectrum you are concerned with is in the mid to high freqs. However, in the HT world, the biggest nemesis is LFE (Low Frequency Emissions). It's the sub-100hz bass you're trying to control and keep from irritating your family members when you are blasting Jurassic Park at reference levels.

The bottom line is STC and IIC are somewhat useful, but they're really only good for a sort of first-glance type of analysis. You should dig into the details when making decisions on exactly what your sound attenuation plan is going to be. That means closely examining lab test results to see which products (or methods) perform better than others when mitigating the portion of the frequency spectrum you're most concerned with - be it LFE or otherwise.

Another way to look at this is let's say your HT room will have a tile floor above it and your significant other likes to walk around in stilettos all day long on that tile floor. Well, then IIC tests will be of importance to you. But if you don't have kids or dogs, the floor above is carpeted, and you'll be using clips & hat channel to suspend the ceiling, plus 3 layers of drywall, you probably won't be too concerned with IIC tests on the ceiling above as it will be very unlikely to present a potential issue.

I hope that's helpful.


----------



## Badbird

HT Geek said:


> The general consensus on this Board is don't waste your time with such products. There are a small number of tried-and-true techniques, and you'll find many examples of implementation of them on this forum. Trust me, your time and energy will be better spent figuring out other challenges. Even if you could save money with this alternative product, you're highly likely risking unknown consequences of performance, and the sound-proofing product is just a small portion of your overall cost of building out a room, equipment, furniture, etc.
> 
> If you are under budget constraints, you can choose to forego some items including Green Glue or similar products. Drywall is cheap. Of course, much depends on your overall goals, but as an example you'll get more bang-for-your-buck spending money on clips & hat channel and forgoing Green Glue versus the other way around.


Thanks for that. I'll take it to heart. I do have a few hundred square feet of the product laying around, but I think I'll stick to the tried and true methods.

I have only started finishing my basement. I'm currently framing and working my way to the theater area. I am just trying to get my ducks in a row and educate myself on the whole process. I am not building a dedicated theater room but what to implement as many aspects as I feel I can make work in my shared media room, including isolating sound coming out of the theater area. More so than sound getting in, but those go hand in hand I'm sure.

Once I get a little more organized and have a more fleshed out plan I will start a thread on my build in the general home theater & media forum.


----------



## jjcook

Is there a technique to adaptively increase the load a decoupled (clips & channel) wall can support while maintaining transmission loss (w.r.t. not overloading the clips)? My concern here is that I do not have a solid and well vetted acoustic treatment plan and so it is unclear what weight and where I may be adding to my walls in the future (e.g., a 70-lb helmholtz resonator bass trap).

The two solutions that come to mind are (1) additional channels recessed from the first layer of drywall that can be screwed into when significant new loads are added (e.g., I'm using A237R clips so I could put the additional channel in with A237 clips which are not as deep), or (2) build independent 2x framing inside the room along the walls (resiliently connected to the structural walls for stability) so that the weight of treatments is transferred to the floor.


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## HT Geek

jjcook said:


> The two solutions that come to mind are (1) additional channels recessed from the first layer of drywall that can be screwed into when significant new loads are added (e.g., I'm using A237R clips so I could put the additional channel in with A237 clips which are not as deep), or (2) build independent 2x framing inside the room along the walls (resiliently connected to the structural walls for stability) so that the weight of treatments is transferred to the floor.


You're more or less on the right path there, though as the old saying goes, "the devil is in the details."

The key is the load bearing capability of each clip and how far apart they are spaced. Unless you're going to have some extreme localized loads, I don't see the need for additional channels. Though if the weight will be near a surface edge, it might make sense to add a channel or two, depending on the circumstances.

Most clips are rated ~36 lbs. maximum supported load. A 70 lb. load isn't bad, though you will also need to add the load of the wall itself, which should be total 5-10 lb. depending on materials, thickness, and any other loads (e.g. lighting fixtures in a ceiling).

Sounds like this would be on a wall if I understand the concept correctly. In that case you also need to consider the shear force where the weight is hanging off part of the wall. It would be wise to reinforce the wall area just above and below the height of the weight. That weight would be tugging on portions of the wall around it. I'd use something like this type of pattern of support. A clip every 2' is likely sufficient, but make sure you run calculations first to verify.


[CLIP] .......... [CLIP] .......... [CLIP]

[CLIP] .......... [CLIP] .......... [CLIP]

[CLIP] .......... [CLIP] .......... [CLIP]


With the weight in the center. Or if it's a wide object:

[CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP]

[CLIP] ............................... [CLIP] .............................. [CLIP]

[CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP]


Or tall:

[CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP]

[CLIP] ............................... [CLIP] .............................. [CLIP]

[CLIP] ............................... [CLIP] .............................. [CLIP]

[CLIP] ............................... [CLIP] .............................. [CLIP]

[CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP] .......... [CLIP]


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## Dennis Erskine

donktard said:


> Any of you guys using mass loaded vinyl as a layer of insulation? I am looking for best soundproofing performance for the least wall thickness possible, so I am looking for best options.


The key word is "Mass". Mass Loaded Vinyl has less mass per sq. ft. than 5/8" drywall. It was never designed, nor intended to be applied in the manner you're intending.


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## Livin

Dennis Erskine said:


> The key word is "Mass". Mass Loaded Vinyl has less mass per sq. ft. than 5/8" drywall. It was never designed, nor intended to be applied in the manner you're intending.


Dennis
in the past I did a lot of online research about MLV and found a lot of conflicting info. What is MLV actually good for?

Also, what's your thought about concrete board? I have a wall (which will be rebuilding later) where the HVAC is literally 1"from bare 2x4 studs with 1/2" DW on the opposite side of the wall.

I was thinking of sliding either MLV or concrete board in the gap as a bandaid until I can redo that area in a year or so. The goal is to reduce sound and vibration as much as reasonable in the situation

Thx

Sent from my SM-G950U using Tapatalk


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## donktard

Dennis Erskine said:


> The key word is "Mass". Mass Loaded Vinyl has less mass per sq. ft. than 5/8" drywall. It was never designed, nor intended to be applied in the manner you're intending.


I stopped reading into it but I was pretty certain it has more mass per square feet, thats why thinner sheet of vinyl would be equally effective as thicker drywall but save space.


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## Dennis Erskine

donktard said:


> I stopped reading into it but I was pretty certain it has more mass per square feet, thats why thinner sheet of vinyl would be equally effective as thicker drywall but save space.


5/8" drywall is rated at 2.35lbs /sq.ft. not to mention far less expensive. Have at it.


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## Dennis Erskine

Livin said:


> Dennis
> in the past I did a lot of online research about MLV and found a lot of conflicting info. What is MLV actually good for?
> 
> Also, what's your thought about concrete board? I have a wall (which will be rebuilding later) where the HVAC is literally 1"from bare 2x4 studs with 1/2" DW on the opposite side of the wall.
> 
> I was thinking of sliding either MLV or concrete board in the gap as a bandaid until I can redo that area in a year or so. The goal is to reduce sound and vibration as much as reasonable in the situation
> 
> Thx
> 
> Sent from my SM-G950U using Tapatalk


That will do some, but little good. You need to be concerned about flanking. I doubt doing just that one wall will help you much. You'd need a more complete solution which would include placing an isolation mat under the air handler and addressing all walls and penetration in that utility space.


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## jjcook

HT Geek said:


> The key is the load bearing capability of each clip and how far apart they are spaced. Unless you're going to have some extreme localized loads, I don't see the need for additional channels. Though if the weight will be near a surface edge, it might make sense to add a channel or two, depending on the circumstances.
> 
> Most clips are rated ~36 lbs. maximum supported load. A 70 lb. load isn't bad, though you will also need to add the load of the wall itself, which should be total 5-10 lb. depending on materials, thickness, and any other loads (e.g. lighting fixtures in a ceiling).
> 
> Sounds like this would be on a wall if I understand the concept correctly. In that case you also need to consider the shear force where the weight is hanging off part of the wall. It would be wise to reinforce the wall area just above and below the height of the weight. That weight would be tugging on portions of the wall around it. I'd use something like this type of pattern of support. A clip every 2' is likely sufficient, but make sure you run calculations first to verify.


Thanks -- the patterns you provide look promising for the case that I know where the extra load will be placed. My question was more about how does one build with flexibility in mind where the locations of the extra loads are not pre-determined or at least where the planned loads may not end up being present? My understanding is if I over-support the walls with extra clips that it will not decouple as effectively, so I would like to have a system to adaptively increase the load bearing capacity. Are there any transmission loss measurements for the varying amounts of clips per unit wall area?

A related question: If I use my A273R & A237 example, will the new screws attached to the recessed channel (~1/2" from the drywall) provide much additional load bearing or does the channel need to be snug up to the channel? I presume leaving unattached channel up against the drywall is a recipe for disaster (vibration).


----------



## HT Geek

jjcook said:


> Thanks -- the patterns you provide look promising for the case that I know where the extra load will be placed. My question was more about how does one build with flexibility in mind where the locations of the extra loads are not pre-determined or at least where the planned loads may not end up being present? My understanding is if I over-support the walls with extra clips that it will not decouple as effectively,


Well, technically that is true, yes. However, provided it's not the entire wall the effect should be limited if noticeable at all. 




> so I would like to have a system to adaptively increase the load bearing capacity. Are there any transmission loss measurements for the varying amounts of clips per unit wall area?


I can't think of how that would be possible. It's something that needs to be planned ahead for. You're going to encounter many decisions in this process that are a trade-off that result in sacrifices one way or another. This sounds like one of those circumstances.

What is the maximum weight and dimensional size of the object you're thinking of?




> A related question: If I use my A273R & A237 example, will the new screws attached to the recessed channel (~1/2" from the drywall) provide much additional load bearing or does the channel need to be snug up to the channel? I presume leaving unattached channel up against the drywall is a recipe for disaster (vibration).


Sorry, but I'm not following your question here. Could you reword it a bit? And, I presume you mean A237R and A237 clips (with and without the 3/8" rubber grommet, respectively).


----------



## HT Geek

donktard said:


> I stopped reading into it but I was pretty certain it has more mass per square feet, thats why thinner sheet of vinyl would be equally effective as thicker drywall but save space.


MLV can be readily had in 1/4" thickness at 2 psf. However, it's an entirely different animal from drywall in a number of respects; aside from its obviously different cosmetic properties.

For instance, 


The resonance of drywall (regardless of thickness) is different from MLV.
MLV is often advised to be applied, "limply" (whatever that means is open to interpretation)
It's not clear how air pockets introduced by "limp" application impact its effectiveness
The very few lab tests on MLV show little improvement in sound attenuation; comparatively speaking it is _at best_ roughly 25-33% of the positive effect of adding a single layer of drywall (notwithstanding their differences in resonance frequencies)

Without delving into the complications of applying MLV on vertical surfaces (e.g. walls), suffice to say the limited amount of objective data indicates its value is sub-par when compared to the benefits of other products - most of which involve much less labor and cost to apply. That said, just like any other product, there may be circumstances where it is useful. However, I'd argue MLV is a product where the number of use cases where it could conceivably be useful is very very small. As in close to zero. What little objective data that exists is very disappointing with respect to attenuation benefits.

And finally, it's not easy to work with on a vertical surface and it is very likely to ultimately take up more than 1/4" of thickness due to the difficulties in applying it vertically. You'd be better off with a sheet of 3/8" drywall that will have a uniform thickness, be substantially cheaper, and provide similar (and perhaps superior) results.


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## jjcook

HT Geek said:


> I can't think of how that would be possible. It's something that needs to be planned ahead for. You're going to encounter many decisions in this process that are a trade-off that result in sacrifices one way or another. This sounds like one of those circumstances.
> 
> What is the maximum weight and dimensional size of the object you're thinking of?


I am not certain what and where I will be placing treatments. I had intended to build an acoustic treatment plan after the drywall was up as I could then take REW measurements etc. but that is not entirely compatible with a clips system.

If I stick to 2-4" thick porous treatments then even with 6pcf density material that's only 1-2psf and so not much of a concern for the wall. However when considering tuned membrane bass traps and diffusors their weight becomes more substantial such as the GIK Scopus 40Hz trap 2'x2' @ 30lb = 7.5psf, or Gik Quadratic Diffusor 1.5'x1.5' @ 20lb = 9psf, or the RPG Modex is 5'x3' @ 90lbs = 5.5psf. In reality I'm unlikely to use many of these heavy products but I don't want to dismiss the idea altogether.



HT Geek said:


> Sorry, but I'm not following your question here. Could you reword it a bit? And, I presume you mean A237R and A237 clips (with and without the 3/8" rubber grommet, respectively).


Yes. Image rows of A237R clips and channel attached to a stud wall at height X and X+24". Then attach a row of A237 clips and channel at height X+12". The channel attached to the A237 clips will be 3/8" away from the drywall. The A237 channel will not impact the load capacity nor the decoupling unless attached to the drywall with screws that penetrate and bridge the 3/8" gap. However this A237 idea does sound like a recipe for rattles when it is unloaded.


All this said I will simply plan for a typical set of treatments and adjust the clips spacing accordingly.


----------



## jrref

I have a generic soundproofing question.
I was reading that placing a bass trap say behind a speaker for example doesn't lessen the transmission of the bass through the wall. Doesn't the bass trap absorb some of the bass sound waves and prevent subsequent reflections off of other objects in the room therefore lessening the transmission level through the wall?


----------



## HT Geek

jrref said:


> I have a generic soundproofing question.
> I was reading that placing a bass trap say behind a speaker for example doesn't lessen the transmission of the bass through the wall. Doesn't the bass trap absorb some of the bass sound waves and prevent subsequent reflections off of other objects in the room therefore lessening the transmission level through the wall?


It does. However, not all bass traps are equal in performance. Other factors also come into play such as flanking. 

LFE is good at penetrating surfaces. The more density in the material and the lower the resonance of the wall, the better job it will do absorbing the bass. Bass traps help, but most are not large enough to help as much as people might expect. Better than not having them though.


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## Blue

Any advice for how to seal off the door frame? I have a room within a room. The double drywall is already up. The doors and frames should be arriving soon. I'm not sure how to get a good seal with the door frame. Is acoustical caulk all that's needed, or do I need to beef it up somehow?


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## HT Geek

Blue said:


> Any advice for how to seal off the door frame? I have a room within a room. The double drywall is already up. The doors and frames should be arriving soon. I'm not sure how to get a good seal with the door frame. Is acoustical caulk all that's needed, or do I need to beef it up somehow?


It really depends on your implementation and which aspect of the door frame/room framing contact you are concerned about. Are you talking about the mating of a pre-manufactured door frame to the jack studs?


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## Blue

HT Geek said:


> It really depends on your implementation and which aspect of the door frame/room framing contact you are concerned about. Are you talking about the mating of a pre-manufactured door frame to the jack studs?


I think the answer is yes, but I'm not sure what "jack studs" means. I'm talking about mating the manufactured door frame to the interior studs that hold up the ceiling of the room within a room.


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## HT Geek

Blue said:


> I think the answer is yes, but I'm not sure what "jack studs" means. I'm talking about mating the manufactured door frame to the interior studs that hold up the ceiling of the room within a room.


Gotcha. What I figured. I'd suggest doing what you alluded to and apply acoustic caulk between door frame and stud. Unfortunately, there's not much else you can do without going to extremes. Doors put a lot of twisting force on the studs the frame is attached to so it must be solid.


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## ncabw

I want to make some bass traps. How do I go about installing them now that I’ve already did the following 

DD+GG 
All walls and ceilings installed on clips. 

Can I just use toggle screws?

Most panels will be 2’x4’
I plan on making 7-10 of them. So say about 40 screw holes. Does this effect the soundproofing I’ve already done?


Sent from my iPad using Tapatalk


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## SeekingNirvana

Anyone heard of or used this product? 

http://https://www.usg.com/content/usgcom/en/products-solutions/products/wall-prep/sealants/usg-sheetrock-acoustical-sealant.html

I’ve been lurking here and reading a lot in the last few months about soundproofing and in all that time I have not heard anyone talk about this product? It looks to be realitivily cheap and looks to have legit testing done on it. I wonder how it compares to green glue version. 

If you read the installion it says you can butter outlet boxes. This along with green glue and OSI’s version say the same. So literally I would just smear a bunch on the box? Would this work with can lights also? I know I know can lights are not allowed in a soundproof room, but I’m putting them in anyways. Would I be able to smear it on the outside of the can to help reduce sound transfer?


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## HT Geek

SeekingNirvana said:


> Anyone heard of or used this product?
> 
> http://https://www.usg.com/content/usgcom/en/products-solutions/products/wall-prep/sealants/usg-sheetrock-acoustical-sealant.html
> 
> I’ve been lurking here and reading a lot in the last few months about soundproofing and in all that time I have not heard anyone talk about this product? It looks to be realitivily cheap and looks to have legit testing done on it. I wonder how it compares to green glue version.


It's an acoustic caulk. Same thing as SC-175. That and Green Glue Noiseproofing Sealant are the go-to on this forum simply because many people have used them. OSI SC-175 is cheap ($78/dozen 28 oz. tubes delivered). You could also use 40 or 50 year caulk if you can find it. Same result. Boils down to cost and availability. The GG caulk is roughly 30% more expensive. USG products like that are normally only available via a contractor supply store. If you can find and purchase it, I would venture it's likely priced similar to the OSI product. BTW, the GG product is labeled as a sealant but behaves more like a caulk.

There really is no good reason IMHO to pay for the GG caulk. Now, GG Noiseproofing Compound is another matter.



> If you read the installion it says you can butter outlet boxes. This along with green glue and OSI’s version say the same. So literally I would just smear a bunch on the box?


No. That's not how you apply this type of product. You'd caulk around the box opening; between the rough drywall opening/edge and the outlet itself. Most people just use putty pads and don't bother worrying about the gap left over, if there is one after the putty pad.

If you want to wrap the box to lessen flanking noise through the box, you need putty pads.




> Would this work with can lights also? I know I know can lights are not allowed in a soundproof room, but I’m putting them in anyways. Would I be able to smear it on the outside of the can to help reduce sound transfer?


No. Don't apply any type of material to the light housing. That is asking for trouble. The proper method for recessed "can" lights is to build a backer box above them. There are various tutorials on this forum and elsewhere that describe how to do that. You would caulk the edge of the backer box where it meets the drywall above your room (e.g. attic side of ceiling).


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## dchabby

so i have had a 'theatre area' in my basement for awhile now but it has come to the point where i need a separate, soundproofed room in order for me and the rest of the household to keep our sanity !!

problem is we dont have much space or money but it looks like i should be able to use one of the bedrooms on the main floor of our bungalow.

now the room is not large, 11.5' x 10.5' but i can get an extra 2.5' if i take out the closet to get 11.5' x 13' which should be just enough for what i need. the height of the room is 7.5'.

if i tear down the walls and ceiling and use clips/channel then i wont loose too much of the floor space and height correct ? would it be an inch or two on each side ?

soundproofing the floor is also a concern as i just layed down a new laminate floor last year. Now i dont mind pulling it up if i have to but is there a way to soundproof without pulling it up ?

i just read about the Serena Mat flooring underlay, would it be best to pull the floor up, put down the underlay and put the laminate back down ?

What else would need to be done as far as the flooring in concerned ? There are 2 bedrooms in the basement just below this room so i need to make sure i can soundproof the room fully before going ahead with this.

Appreciate the help anyone can give !


----------



## HT Geek

dchabby said:


> so i have had a 'theatre area' in my basement for awhile now but it has come to the point where i need a separate, soundproofed room in order for me and the rest of the household to keep our sanity !!
> 
> problem is we dont have much space or money but it looks like i should be able to use one of the bedrooms on the main floor of our bungalow.
> 
> now the room is not large, 11.5' x 10.5' but i can get an extra 2.5' if i take out the closet to get 11.5' x 13' which should be just enough for what i need. the height of the room is 7.5'.


With some creativity, you can squeeze in a single row of seats in a room that size, yes.




> if i tear down the walls and ceiling and use clips/channel then i wont loose too much of the floor space and height correct ? would it be an inch or two on each side ?


Really depends on details of your plan, but plan on losing 6" on each axis. That will give you a good ballpark (should be a bit less, but like I said... ballpark).




> soundproofing the floor is also a concern as i just layed down a new laminate floor last year. Now i dont mind pulling it up if i have to but is there a way to soundproof without pulling it up ? i just read about the Serena Mat flooring underlay, would it be best to pull the floor up, put down the underlay and put the laminate back down ?


Depends on what is under it.




> There are 2 bedrooms in the basement just below this room so i need to make sure i can soundproof the room fully before going ahead with this.


Ok. So, now we know there's another level below this room. When was the home built? What year? Which country are you in?


----------



## dchabby

HT Geek said:


> With some creativity, you can squeeze in a single row of seats in a room that size, yes.


yes only looking at a single 3 seat couch for this room - hoping to also get a small computer desk in here but that will be a topic for another thread !




> Really depends on details of your plan, but plan on losing 6" on each axis. That will give you a good ballpark (should be a bit less, but like I said... ballpark).


so is that 6" even after tearing down the existing drywall ? so my 11'5" x 13' would then be 10'11" x 12'6" correct ?




> Depends on what is under it.


underneath the laminate flooring ? the flooring came with a small underpad attached and was layed down on plywood subfloor




> Ok. So, now we know there's another level below this room. When was the home built? What year? Which country are you in?


home is located in Toronto, Ontario , Canada and I think it was built in the 1980's


----------



## HT Geek

dchabby said:


> so is that 6" even after tearing down the existing drywall ? so my 11'5" x 13' would then be 10'11" x 12'6" correct ?


You'll end up with a wall thickness of roughly 2-1/2 to 3 inches on each wall/ceiling surface. Exact offset will depend on the specific channel, drywall width, etc. you use.




> underneath the laminate flooring ? the flooring came with a small underpad attached and was layed down on plywood subfloor


Well, the easy way would be lay down pad and carpet on top of the laminate. You have quite a few options. Depends on desired result, level of effort you're willing to undertake, and your budget.

Bear in mind how any changes will impact floor height and transitions in/out of the room to/from other rooms.

Let's start with goals for noise below the room. What are your thoughts on this subject?




> home is located in Toronto, Ontario , Canada and I think it was built in the 1980's


Ok. Good. No danger of asbestos if you remove the laminate.


----------



## dchabby

HT Geek said:


> You'll end up with a wall thickness of roughly 2-1/2 to 3 inches on each wall/ceiling surface. Exact offset will depend on the specific channel, drywall width, etc. you use.


ok thanks




> Well, the easy way would be lay down pad and carpet on top of the laminate. You have quite a few options. Depends on desired result, level of effort you're willing to undertake, and your budget.
> 
> Bear in mind how any changes will impact floor height and transitions in/out of the room to/from other rooms.
> 
> Let's start with goals for noise below the room. What are your thoughts on this subject?



Desired result is as much sound containment as possible as this is a bedroom that is located right beside and above other bedrooms. Yes budget is tight but level of effort is there and willing to do what it takes.

I don't mind pulling up the existing laminate if it will produce greater results.



> Ok. Good. No danger of asbestos if you remove the laminate.


definitely no asbestos ! 

I just layed this laminate down last year and could repurpose some of it if need be.

is there a way to get good results re-using laminate or will it pretty much have to be carpet for best results ?


----------



## LydMekk

Best results: wall to wall carpet.

BUT: you can probable get within 90% results by laying down a big carpet which does not necessarily cover the exact whole floor.

Try it first and see? That way you can preserve that laminate.


----------



## HT Geek

dchabby said:


> is there a way to get good results re-using laminate or will it pretty much have to be carpet for best results ?


The problem with laminate is it reflects sound. You'll want an absorptive material. Carpet is the best all-around. Your best bet is to use some sort of padding underneath the carpet pad, such as the serenity mat you mentioned. The typical layout is something like this:

carpet
pad
OSB or plywood
serenity mat or equivalent
sub-floor

The issue with this approach is the floor height, as you'll be increasing it above a normal residential floor height. This makes transitions between rooms a challenge. It's not as big of a deal when the HT room is at the bottom of stairs or some other situation where there is already a height change to begin with as it becomes easier to mask the HT floor height.

There are some other alternative methods. If the floor height is a concern, you could lay carpet without the pad over the laminate, or use a thin pad. Another option is remove the laminate and sub-floor, install floor isolators and reinstall the sub-floor. Depends on how crazy you want to get and your budget of course.

What are your thoughts on floor height? Your options are also limited by the room height. In the U.S. it can't drop below 7' tall. Not sure about Canada.


----------



## dchabby

LydMekk said:


> Best results: wall to wall carpet.
> 
> BUT: you can probable get within 90% results by laying down a big carpet which does not necessarily cover the exact whole floor.
> 
> Try it first and see? That way you can preserve that laminate.


thank you 



HT Geek said:


> The problem with laminate is it reflects sound. You'll want an absorptive material. Carpet is the best all-around. Your best bet is to use some sort of padding underneath the carpet pad, such as the serenity mat you mentioned. The typical layout is something like this:
> 
> carpet
> pad
> OSB or plywood
> serenity mat or equivalent
> sub-floor
> 
> The issue with this approach is the floor height, as you'll be increasing it above a normal residential floor height. This makes transitions between rooms a challenge. It's not as big of a deal when the HT room is at the bottom of stairs or some other situation where there is already a height change to begin with as it becomes easier to mask the HT floor height.
> 
> There are some other alternative methods. If the floor height is a concern, you could lay carpet without the pad over the laminate, or use a thin pad. Another option is remove the laminate and sub-floor, install floor isolators and reinstall the sub-floor. Depends on how crazy you want to get and your budget of course.
> 
> What are your thoughts on floor height? Your options are also limited by the room height. In the U.S. it can't drop below 7' tall. Not sure about Canada.


floor height would be a concern as I am already sitting at 7'6" and would lose about 3" after ripping the drywall out and then doing clips/channel/DD with green glue. Then adding all the extra layers of flooring will definitely take me under 7'. I'm not sure on the regulations here but I don't want to feel cramped and not sure if that low of a height works for an atmos setup.

like Lydmekk posted above - would I get 90% of the results just by throwing a good carpet on top of the laminate ?


----------



## HT Geek

dchabby said:


> floor height would be a concern as I am already sitting at 7'6" and would lose about 3" after ripping the drywall out and then doing clips/channel/DD with green glue. Then adding all the extra layers of flooring will definitely take me under 7'. I'm not sure on the regulations here but I don't want to feel cramped and not sure if that low of a height works for an atmos setup.
> 
> like Lydmekk posted above - would I get 90% of the results just by throwing a good carpet on top of the laminate ?


If you want to block sound, that last 10% will be the bane of your existence. You'll basically get flanking noise. Sound functions kind of like water. If it can find a way in, it will. You'd need to do wall-to-wall carpet over the laminate.

BTW, when you're looking at that type of scenario, there are two types of sound to take into consideration: airborne and impact. You can do some simple things to mitigate impact sound transmission, such as not using a downward firing subwoofer in your room. HT rooms are most concerned with airborne sound. Footsteps on tile above a room.... that's the sort of thing I think of being an issue for impact noise, and it's normally a concern when the HT room is below something like a room with tile floor. In your case, you should focus on airborne sound containment.


----------



## Ladeback

HTGeek, I have a question about using IB-3 clips. I have a wall that I have framed under a beam and was thinking adding another top plate and use IB-3 clips to decouple it from the beam. Would this work or am I still going to get a lot of flanking going up the wall? If would, then it makes since to push that wall out to make the room wider and have that wall under the floor joist instead.


----------



## dchabby

HT Geek said:


> If you want to block sound, that last 10% will be the bane of your existence. You'll basically get flanking noise. Sound functions kind of like water. If it can find a way in, it will. You'd need to do wall-to-wall carpet over the laminate.
> 
> BTW, when you're looking at that type of scenario, there are two types of sound to take into consideration: airborne and impact. You can do some simple things to mitigate impact sound transmission, such as not using a downward firing subwoofer in your room. HT rooms are most concerned with airborne sound. Footsteps on tile above a room.... that's the sort of thing I think of being an issue for impact noise, and it's normally a concern when the HT room is below something like a room with tile floor. In your case, you should focus on airborne sound containment.


thanks for all your help here - its really appreciated !

is there a certain type of carpet that works better than others when it comes to soundproofing ?


----------



## HT Geek

dchabby said:


> is there a certain type of carpet that works better than others when it comes to soundproofing ?


One that you like.


----------



## HT Geek

Ladeback said:


> HTGeek, I have a question about using IB-3 clips. I have a wall that I have framed under a beam and was thinking adding another top plate and use IB-3 clips to decouple it from the beam. Would this work or am I still going to get a lot of flanking going up the wall? If would, then it makes since to push that wall out to make the room wider and have that wall under the floor joist instead.


The Devil is in the Details, but conceptually, yes you can do that. As long as it's not a load bearing wall.


----------



## Ladeback

HT Geek said:


> The Devil is in the Details, but conceptually, yes you can do that. As long as it's not a load bearing wall.



The wall wouldn't bearing. This beam and another run the length of the house and are supported by columns in certain places. Right I was thinking of hiding a column in the wall I have built under the beam or push the wall out to go wider. If I did this I would bring power into my riser down the column so the riser wouldn't touch any of the walls at all.


----------



## HT Geek

When I built my "room within a room" I used IB-3 clips along the top plate (horizontally) and vertically in the corners. They're very versatile.


----------



## dchabby

HT Geek said:


> One that you like.


LOL 

so if i was more concerned about blocking incoming noise would i be able to get away without doing anything to the ceiling ?

and would just doing the floor help keep the noise down for the rooms underneath me or not really ?

i know i have read that soundproofing is really an all or nothing deal but if i can get some decent results with some barebones work then that might work in my situation.


----------



## LydMekk

A carpet doesn't do anything to block sound as in soundproofing, it only dampens reflections acoustically inside the room.
2 different things.


----------



## HT Geek

dchabby said:


> so if i was more concerned about blocking incoming noise would i be able to get away without doing anything to the ceiling ?
> 
> and would just doing the floor help keep the noise down for the rooms underneath me or not really ?
> 
> i know i have read that soundproofing is really an all or nothing deal but if i can get some decent results with some barebones work then that might work in my situation.


Many of us talk in AVS about 'all or nothing' but that statement needs clarification. IMHO, it relates to a particular method of soundproofing. For example, if you used IB-3 clips to decouple 3/4 of your ceiling beams from your wall's top header when building a 'room within a room' you can't expect it to have a significant effect on the end result, because the coupled 1/4 of your ceiling will defeat the efforts in the 3/4 decoupled section.

In your case, carpet will actually help a tad. It's better than tile for example, which would make your HT room worse (reflective) and make impact noise worse to the room below. However, it's mostly the pad that adds any benefit at all and it's barely any help.

The only way you're going to get substantial noise reduction between your HT room and the rooms below is by decoupling the HT room floor and/or ceiling and walls of the room below, and/or adding mass to the floor of the HT room and decoupling its walls. You have to find a way to isolate the HT room or isolate the other room(s). There's no way around it. In this case, unless you can raise the floor of the HT room without causing other issues, you're better off treating the ceiling and possibly the walls of the room(s) below. One advantage of this approach is you can build your HT room based on other soundproofing criteria and once you observe the results, then tackle any issues in the room(s) below or above the HT room.

Let's say you decouple your HT room's ceiling and walls with clips and channel. That should go a long way to reduce airborne noise travelling to rooms above or beside your HT room. Your room(s) below will be your headache. The HT room floor is going to vibrate what are the ceiling joists from the perspective of the floor below, and likely also the studs in the room(s) below that make up their walls. If reducing noise travelling from the HT room to the rooms below is a priority, your best bet would be to decouple the HT room floor. Unfortunately, that is a very labor intensive and expensive task for most HT rooms. For most people, it's not practical. 

If you want to consider that route, the most cost efficient and least labor intensive method is going to be to raise the floor. I don't know what your technical background is, but if you're familiar at all with how IT data centers are built, they all have raised floors. You'd want to build your HT room in a similar fashion - planning on a raised floor to begin with. In data centers it's done primarily to allow wires to be run everywhere, and secondarily to prevent damage in the event of a flood and sometimes (rarely) to aid in air circulation.

In your HT room, a raised floor gives you a ton of options to mitigate sound travel through your sub-floor. The best products I've seen are manufactured by Kinetics and are their RIM floor line. They are not cheap, but they are very effective. Get yourself something like a 2"-4" thick RIM floor and you'll be GTG. Of course, there is always a catch: height. And in your case even if you created a step up into your room to hide the higher floor, you're going to end up below 7' room height. Aside from the possibility of it feeling too "closed in," it may not meet legal requirements; which should be either 7', 6' 6", or 6' 8" depending on jurisdiction and an inspector's opinion of what your HT room is (purpose).

So, you MAY be able to do a raised floor (legally). I'm not sure of course if you'd like the effect psychologically. Dark rooms tend to feel smaller to begin with. OTOH, it's a small room (LxW) so you're less likely to have an issue with it since a shorter ceiling should feel proportional in some sense. If this is going to be your man cave, perhaps consider whether it's really a big deal or not. When the lights are out, will you notice and will you care? Probably not. Particularly when weighed with the end result. Would you rather have 3-6" less headroom in the room and the rest of the house is relatively quiet while you are blasting a movie, or have more headroom and your family is complaining? [my caveat to that is don't expect a miracle of sound attenuation... too many variables to expect that, but it will help significantly to decouple your floor - in your particular situation]


----------



## Ladeback

@dchabby, I remember from your first post you said you had a theater space in your basement. Why can you not build you dedicated space down there? It may be easier then building it in a bedroom. 

Just a thought.


----------



## dchabby

HT Geek said:


> Many of us talk in AVS about 'all or nothing' but that statement needs clarification. IMHO, it relates to a particular method of soundproofing. For example, if you used IB-3 clips to decouple 3/4 of your ceiling beams from your wall's top header when building a 'room within a room' you can't expect it to have a significant effect on the end result, because the coupled 1/4 of your ceiling will defeat the efforts in the 3/4 decoupled section.
> 
> In your case, carpet will actually help a tad. It's better than tile for example, which would make your HT room worse (reflective) and make impact noise worse to the room below. However, it's mostly the pad that adds any benefit at all and it's barely any help.
> 
> The only way you're going to get substantial noise reduction between your HT room and the rooms below is by decoupling the HT room floor and/or ceiling and walls of the room below, and/or adding mass to the floor of the HT room and decoupling its walls. You have to find a way to isolate the HT room or isolate the other room(s). There's no way around it. In this case, unless you can raise the floor of the HT room without causing other issues, you're better off treating the ceiling and possibly the walls of the room(s) below. One advantage of this approach is you can build your HT room based on other soundproofing criteria and once you observe the results, then tackle any issues in the room(s) below or above the HT room.
> 
> Let's say you decouple your HT room's ceiling and walls with clips and channel. That should go a long way to reduce airborne noise travelling to rooms above or beside your HT room. Your room(s) below will be your headache. The HT room floor is going to vibrate what are the ceiling joists from the perspective of the floor below, and likely also the studs in the room(s) below that make up their walls. If reducing noise travelling from the HT room to the rooms below is a priority, your best bet would be to decouple the HT room floor. Unfortunately, that is a very labor intensive and expensive task for most HT rooms. For most people, it's not practical.
> 
> If you want to consider that route, the most cost efficient and least labor intensive method is going to be to raise the floor. I don't know what your technical background is, but if you're familiar at all with how IT data centers are built, they all have raised floors. You'd want to build your HT room in a similar fashion - planning on a raised floor to begin with. In data centers it's done primarily to allow wires to be run everywhere, and secondarily to prevent damage in the event of a flood and sometimes (rarely) to aid in air circulation.
> 
> In your HT room, a raised floor gives you a ton of options to mitigate sound travel through your sub-floor. The best products I've seen are manufactured by Kinetics and are their RIM floor line. They are not cheap, but they are very effective. Get yourself something like a 2"-4" thick RIM floor and you'll be GTG. Of course, there is always a catch: height. And in your case even if you created a step up into your room to hide the higher floor, you're going to end up below 7' room height. Aside from the possibility of it feeling too "closed in," it may not meet legal requirements; which should be either 7', 6' 6", or 6' 8" depending on jurisdiction and an inspector's opinion of what your HT room is (purpose).
> 
> So, you MAY be able to do a raised floor (legally). I'm not sure of course if you'd like the effect psychologically. Dark rooms tend to feel smaller to begin with. OTOH, it's a small room (LxW) so you're less likely to have an issue with it since a shorter ceiling should feel proportional in some sense. If this is going to be your man cave, perhaps consider whether it's really a big deal or not. When the lights are out, will you notice and will you care? Probably not. Particularly when weighed with the end result. Would you rather have 3-6" less headroom in the room and the rest of the house is relatively quiet while you are blasting a movie, or have more headroom and your family is complaining? [my caveat to that is don't expect a miracle of sound attenuation... too many variables to expect that, but it will help significantly to decouple your floor - in your particular situation]


thank you very much for the info - lots for me to think about. I think I will do a dry run this weekend to see how bad the noise is before doing anything and then move forward from there.



Ladeback said:


> @dchabby, I remember from your first post you said you had a theater space in your basement. Why can you not build you dedicated space down there? It may be easier then building it in a bedroom.
> 
> Just a thought.


it would definitely be easier and I would have more room for it as well.

unfortunately for me, that space is now kinda spoken for so I have been desperately trying to come up with an alternative location.

I have gone from converting our garage to putting an addition on top of the garage to building a 'shed' outside to now trying to squeeze into this bedroom.


----------



## HT Geek

If above the garage is still a potential option, it sounds like you don't have a finished area there yet. That would be ideal from a soundproofing perspective as you could choose from a variety of techniques to attain the results you want.


----------



## jjcook

HT Geek said:


> In your HT room, a raised floor gives you a ton of options to mitigate sound travel through your sub-floor. The best products I've seen are manufactured by Kinetics and are their RIM floor line. They are not cheap, but they are very effective. Get yourself something like a 2"-4" thick RIM floor and you'll be GTG. Of course, there is always a catch: height. And in your case even if you created a step up into your room to hide the higher floor, you're going to end up below 7' room height. Aside from the possibility of it feeling too "closed in," it may not meet legal requirements; which should be either 7', 6' 6", or 6' 8" depending on jurisdiction and an inspector's opinion of what your HT room is (purpose).


I am also converting a small bedroom above living space (but not above bedrooms). My plan has been: existing subfloor - 3/8" serenity mat - 3/8" plywood - green glue - 3/8" plywood - thicker carpet pad - low'ish pile carpet. This will add approximately 1.25" to my floor height assuming pad+carpet total height stays constant. As my door opens into the theater I will by code need to gradually change the floor height outside the door (under the carpet) to meet the maximum safe threshold height step (don't recall something like 3/8").

Assuming @dchabby goes with carpet, are you recommending the RIM floor as serenity mat, etc., will not be sufficiently effective for his scenario?

As the minimum RIM application install appears to be 2" RIM + 2x 3/4 plywood = 3.5", this height difference seems tricky if his door swings into the room. Due to the location of my room in the hallway I cannot have the door open blindly into the hall due to risk of injury and egress interference.


----------



## HT Geek

jjcook said:


> I am also converting a small bedroom above living space (but not above bedrooms). My plan has been: existing subfloor - 3/8" serenity mat - 3/8" plywood - green glue - 3/8" plywood - thicker carpet pad - low'ish pile carpet. This will add approximately 1.25" to my floor height assuming pad+carpet total height stays constant. As my door opens into the theater I will by code need to gradually change the floor height outside the door (under the carpet) to meet the maximum safe threshold height step (don't recall something like 3/8").


In the United States, under the residential building code adopted in most states, 3/8" variation is the most you can have between steps along a single contiguous staircase. Outside of that 3/8" reference, I'm not sure what you mean in your scenario. 

Let's say you've got a scenario where you need to make a gradual floor height adjustment from Point A to Point B. Again, using U.S.A. residential building typical guidelines, your maximum slope for a ramp is 1:12, such as 1" of elevation must be made over a minimum distance of 12" or 1' of elevation change must be made over a minimum distance of 12'. So, if for example you need to gradually raise a floor - akin to a ramp - a height of 1-1/4", you wound have to do that across a minimum of 1.25*12 = 15". You could do it over a broader (longer) distance, but not shorter.




> Assuming @dchabby goes with carpet, are you recommending the RIM floor as serenity mat, etc., will not be sufficiently effective for his scenario?


No. I was simply suggesting Kinetics' RIM is a very good application from a soundproofing perspective. The catch is you need something on top of the RIM (e.g. OSB or plywood), and then you could put carpet on top of that.




> As the minimum RIM application install appears to be 2" RIM + 2x 3/4 plywood = 3.5", this height difference seems tricky if his door swings into the room.


I could be wrong, but I don't believe that is quite correct. I believe that is an example Kinetics gives, though it's certainly a good approach (just not the only one). The underlayment beneath the 2" RIM could be different. It really depends on what is under the underlayment (e.g. concrete, wood sub-floor, etc.). That said, you need something rigid on top of the RIM itself, so to your point it's going to be a thick floor if you use RIM no matter the total design.

To your point, yes the use of RIM would add substantially to the floor height.




> Due to the location of my room in the hallway I cannot have the door open blindly into the hall due to risk of injury and egress interference.


Right. Please take care to familiarize yourself with building codes. For example - again in the U.S.A. in the preponderance of jurisdictions - you cannot have a door swing open across a change in elevation. The most common scenario is a step down. The edge of the door must swing such that it is across a level platform and in the case of a step down outside the doorway, the door must not extend over a step (down). I hope that makes sense. The purpose is to prevent falls from unexpected sudden changes in elevation of the floor beneath one's feet.

Sounds like you're on the right path though.


----------



## dchabby

HT Geek said:


> If above the garage is still a potential option, it sounds like you don't have a finished area there yet. That would be ideal from a soundproofing perspective as you could choose from a variety of techniques to attain the results you want.


there is nothing above the garage at the moment.

I would absolutely love to build a room above it but we are looking at $50000+ to have an addition put on which we cant afford right now, at least not until we win the lottery !!


----------



## tbraden32

Starting our HVAC this week. Double stud wall, GG etc for dedicated room. Will have its own Zone for the room. Currently installing 3-6" supplies and a return. 

Builder and HVAC contractor wanting to install return low in wall, assuming that is incorrect for this room? Supplies will be built into soffits, should the return too? Thats what my plans call for.


----------



## bluetv

Does anyone have a suggestion as to sound proofing a sliding glass door? I have heavy drapes but can still hear outside sound.


----------



## HT Geek

tbraden32 said:


> Starting our HVAC this week. Double stud wall, GG etc for dedicated room. Will have its own Zone for the room. Currently installing 3-6" supplies and a return.


What are these supplies going to be run from? The main plenum? Or a trunk? If a trunk, what is the diameter coming off the main plenum prior to your 3x 6" split?




> Builder and HVAC contractor wanting to install return low in wall, assuming that is incorrect for this room? Supplies will be built into soffits, should the return too? Thats what my plans call for.


Well, there are fundamentally two schools of thought here. One is: if you live in a northern climate, install the return low the suck in cool air since you will never run your A/C.

The other is: 1) You don't live in an (extreme) northern climate and/or who cares because heat rises, and you want to remove the heat since it's bad for your PJ, A/V equipment, etc.

I personally subscribe to school of thought number 2; i.e., agree with you. Install it up high to capture warmer air.


----------



## HT Geek

bluetv said:


> Does anyone have a suggestion as to sound proofing a sliding glass door?


Yes. Get rid of it. 

Seriously.

If that is not practical, block it off with some combination of drywall and/or insulation. Preferably, seal it off in such a way to reduce the potential negative impacts in your room of condensation and/or moisture penetration. Like I said above, best option is to get rid of it.


----------



## tbraden32

HT Geek said:


> What are these supplies going to be run from? The main plenum? Or a trunk? If a trunk, what is the diameter coming off the main plenum prior to your 3x 6" split?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Well, there are fundamentally two schools of thought here. One is: if you live in a northern climate, install the return low the suck in cool air since you will never run your A/C.
> 
> 
> 
> The other is: 1) You don't live in an (extreme) northern climate and/or who cares because heat rises, and you want to remove the heat since it's bad for your PJ, A/V equipment, etc.
> 
> 
> 
> I personally subscribe to school of thought number 2; i.e., agree with you. Install it up high to capture warmer air.




Ohio- not sure what is considered the main vs trunk, but it is dedicated to the HT and Golf Sim rooms only on their own zone. If that helps.


----------



## tbraden32

If anyone recommends a return in the bottom, can you do a muffler in between a double stud wall or would this be a huge sound isolation problem, plus couple the walls?


----------



## HT Geek

tbraden32 said:


> Ohio- not sure what is considered the main vs trunk, but it is dedicated to the HT and Golf Sim rooms only on their own zone. If that helps.


So, from the main plenum - where the HVAC supply run originates from - do you know how wide the diameter is of the HVAC supply duct?

HVAC can get a little tricky, but two important factors to bear in mind are:

1. Input (supply) and output (exhaust) into/out of a room should be as equal as possible
2. A HT room's HVAC is usually a trade-off between noise (audible sound from it) and capacity (cooling effectiveness)

My concern from reading your comment was regarding the air movement through 3x 6" ducts and whether or not it will be equal to the air movement in size duct before the split into 3x 6" ducts.


----------



## HT Geek

tbraden32 said:


> If anyone recommends a return in the bottom, can you do a muffler in between a double stud wall or would this be a huge sound isolation problem, plus couple the walls?


What's your concern that would precipitate using some sort of a muffler? Are you trying to solve a particular problem? If so, what is it? Or what are your concerns?


----------



## bluetv

HT Geek said:


> Yes. Get rid of it.
> 
> Seriously.
> 
> If that is not practical, block it off with some combination of drywall and/or insulation. Preferably, seal it off in such a way to reduce the potential negative impacts in your room of condensation and/or moisture penetration. Like I said above, best option is to get rid of it.


Let's say I get rid of it. Do you have a recommendation for a soundproof replacement? The sliding glass door is quite large (141 in (W) x 93 in (H)).


----------



## tbraden32

HT Geek said:


> What's your concern that would precipitate using some sort of a muffler? Are you trying to solve a particular problem? If so, what is it? Or what are your concerns?




Have always seen the return mufflers built into the soffits. If we try to build a muffler into the wall cavity which is a double stud wall, I was worried about coupling the double stud wall for one, and will it be less productive then high up in the mufflers. Second they were wanting it at front of the room, just concerned with doing it correctly and not having them just talk me into the easiest solution for them. 

As for the trunk and air flow, not sure of the size but HVAC contractor was aware of sealed room with people and PJ in room. Originally we were talking around 450cfms coming into the room.

16x17. 10' ceilings. Smallish room.


----------



## HT Geek

bluetv said:


> Let's say I get rid of it. Do you have a recommendation for a soundproof replacement? The sliding glass door is quite large (141 in (W) x 93 in (H)).


Your best bet is to remove the door and convert into a wall. If you must have a door / entryway there, you've got several options. If that is the case though I suggest sealing it off from inside the room. You'll want access to it from the outside in case it's ever damaged or if you want to restore the door at any point in the future, so think about being able to un-do whatever you do internally.

If you leave it, you also need to think about what could go wrong that you might not be aware of from inside the room. For example, water leaks. There's no easy answer other than remove it and seal off the hole to make a wall. I know that's not always practical. If not, chances are sealing it with marine grade plywood from the outside probably isn't either (not exactly aesthetically attractive for your neighbors, if you have any).

On the inside, you have a number of options. If you just want to keep sound from entering your HT room, you can probably get away with a few inches of insulation almost up against the glass, and then put 2 layers of drywall up. Of course, you'd want the end result to be flush with your surrounding walls. With a hole that big in your wall, you'll need to frame it as well. You want to keep the framing off the glass and create an air gap between the glass and framing, insulation, etc. You don't want a direct connection to the insulation/framing for sound proofing and also to prevent condensation buildup on the insulation.


----------



## HT Geek

tbraden32 said:


> Have always seen the return mufflers built into the soffits. If we try to build a muffler into the wall cavity which is a double stud wall, I was worried about coupling the double stud wall for one, and will it be less productive then high up in the mufflers. Second they were wanting it at front of the room, just concerned with doing it correctly and not having them just talk me into the easiest solution for them.
> 
> As for the trunk and air flow, not sure of the size but HVAC contractor was aware of sealed room with people and PJ in room. Originally we were talking around 450cfms coming into the room.
> 
> 16x17. 10' ceilings. Smallish room.


Normally, you want supply vents at the room front and returns at the rear. Several reasons for this. The big ones are so your equipment's hot air gets exhausted up into the return duct. This is also partly why you want the return duct up high. Second good reason for supplies front/returns rearward is it will 'pull' the cool air across your room, your seats/guests, and equipment when you have the A/C on (you're not likely to ever need heat in there when equip is running).

A zoned system - as you're planning - is ideal. You may wish to consider setting it up so the return duct will still run even if your supply vents are closed if your equipment is on. I did that in my room, but largely because my equip rack exhausts heat directly into the HVAC return line.

450cfm is a good amount of air in that size room. If it's not enough, you could add an inline duct fan. I have one in both supply and return ducts in my room. They're controlled by a combination of the zoned system and relays, so I can control the circumstances when they are on or off.


----------



## tbraden32

HT Geek said:


> Normally, you want supply vents at the room front and returns at the rear. Several reasons for this. The big ones are so your equipment's hot air gets exhausted up into the return duct. This is also partly why you want the return duct up high. Second good reason for supplies front/returns rearward is it will 'pull' the cool air across your room, your seats/guests, and equipment when you have the A/C on (you're not likely to ever need heat in there when equip is running).
> 
> 
> 
> A zoned system - as you're planning - is ideal. You may wish to consider setting it up so the return duct will still run even if your supply vents are closed if your equipment is on. I did that in my room, but largely because my equip rack exhausts heat directly into the HVAC return line.
> 
> 
> 
> 450cfm is a good amount of air in that size room. If it's not enough, you could add an inline duct fan. I have one in both supply and return ducts in my room. They're controlled by a combination of the zoned system and relays, so I can control the circumstances when they are on or off.




Awesome Info. Thanks HT.


----------



## bluetv

HT Geek said:


> Your best bet is to remove the door and convert into a wall. If you must have a door / entryway there, you've got several options. If that is the case though I suggest sealing it off from inside the room. You'll want access to it from the outside in case it's ever damaged or if you want to restore the door at any point in the future, so think about being able to un-do whatever you do internally.
> 
> If you leave it, you also need to think about what could go wrong that you might not be aware of from inside the room. For example, water leaks. There's no easy answer other than remove it and seal off the hole to make a wall. I know that's not always practical. If not, chances are sealing it with marine grade plywood from the outside probably isn't either (not exactly aesthetically attractive for your neighbors, if you have any).
> 
> On the inside, you have a number of options. If you just want to keep sound from entering your HT room, you can probably get away with a few inches of insulation almost up against the glass, and then put 2 layers of drywall up. Of course, you'd want the end result to be flush with your surrounding walls. With a hole that big in your wall, you'll need to frame it as well. You want to keep the framing off the glass and create an air gap between the glass and framing, insulation, etc. You don't want a direct connection to the insulation/framing for sound proofing and also to prevent condensation buildup on the insulation.


This is an indoor sliding glass door that opens from the dining room to the media room. I got a quote for this service. What do you think? I left the price out.


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*
Window and Door Information: *(*3/8”* *studio* grade glass)--------------------------------------
One 4-panel _Telescoping_ Soundproof Sliding Glass Door: 141" x 93"…. x1


----------



## Blue

Mpoes12 said:


> There is not going to be a sound isolation advantage between the two for the vast majority of people. Pemko has test data showing the loss in isolation compared to glued in place. You have to have a very high STC door to need either of the options compared to what basic silicone or neoprene stick on gaskets will give you. The advantage with these systems is that they are adjustable and so easy to align and get a good seal.
> 
> I've seen test data on the transmission loss of plywood or MDF with green glue and the stc values of even that is far lower than you might hope. Basically the stc value of your door needs to be in the low 40's before there becomes a need for the lighter duty door gasket system. It needs to be well into the 50's before the heavy duty is needed. A normal solid core door is going to range from around stc20 to stc35. The most commonly available solid core doors are in the mid to upper 20's.
> 
> In other words, buy what you like. There is no sound isolation advantage for you unless you are building a very soundproof wall with a very high STC door assembly. It's mostly going to be for ease of use and bragging rights.
> 
> 
> Sent from my iPhone using Tapatalk


I'm resurrecting an old exchange we had because the room is finally coming along to the point that I need to make some door soundproofing purchases. I bought the JELD-WEN doors you recommended in the thread you launched about doors, which the chart you cited shows as having an STC rating of 43. From your response I've quoted here, am I correct in believing that the rubber tear drop seals applied to the wood door gaskets will be effective for the sides and top of the door? Or, in other words, would there be any real benefit to instead paying almost $500 per door to get the fancy heavy duty adjustable door gaskets that one can buy and install in place of wood door gaskets? (I.e., these: https://www.tmsoundproofing.com/Heavy-Duty-Door-Gasket.html ) 

Also, I'm getting automatic door bottoms. Is there a benefit to also getting door saddles? 
(These: https://www.tmsoundproofing.com/Door-Saddle-125.html ) It seems to me that either door saddles OR door bottoms accomplish the same goal, but if having both will improve things, then I can do both. 

Assuming there's no need for both, are the door saddles _all _you need? In other words, do the automatic bottoms actually add any extra sound isolation versus the door saddles?


----------



## Mpoes12

Blue said:


> I'm resurrecting an old exchange we had because the room is finally coming along to the point that I need to make some door soundproofing purchases. I bought the JELD-WEN doors you recommended in the thread you launched about doors, which the chart you cited shows as having an STC rating of 43. From your response I've quoted here, am I correct in believing that the rubber tear drop seals applied to the wood door gaskets will be effective for the sides and top of the door? Or, in other words, would there be any real benefit to instead paying almost $500 per door to get the fancy heavy duty adjustable door gaskets that one can buy and install in place of wood door gaskets? (I.e., these: https://www.tmsoundproofing.com/Heavy-Duty-Door-Gasket.html )
> 
> 
> 
> Also, I'm getting automatic door bottoms. Is there a benefit to also getting door saddles? (These: https://www.tmsoundproofing.com/Door-Saddle-125.html )




In theory there is no benefit but in practice the better gaskets are easier to get a better deal with. It’s a lot of money to spend for a very small potential improvement, and if you get a good deals the tear drop, no improvement at all. However if you find you can’t get a good deal you may need to try the adjustable. 

Personally I would use the stick on first and see how it goes. 

The saddle is needed if you have carpet under the door or if the door gap is large. It is not needed if you cut the door with a minimum gap. The saddle that seals to the door adds another gasket so that has some
Benefit, but again it’s minor. 


Sent from my iPhone using Tapatalk


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## Blue

Mpoes12 said:


> In theory there is no benefit but in practice the better gaskets are easier to get a better deal with. It’s a lot of money to spend for a very small potential improvement, and if you get a good deals the tear drop, no improvement at all. However if you find you can’t get a good deal you may need to try the adjustable.
> 
> Personally I would use the stick on first and see how it goes.
> 
> The saddle is needed if you have carpet under the door or if the door gap is large. It is not needed if you cut the door with a minimum gap. The saddle that seals to the door adds another gasket so that has some
> Benefit, but again it’s minor.
> 
> 
> Sent from my iPhone using Tapatalk


Thanks! You responded in record time, even more quickly than I could edit my post. My edit has one more question that I hope you won't mind helping with. Do you think an automatic door bottom is more effective than a saddle with its built-in rubber seal?


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## HT Geek

Blue said:


> Thanks! You responded in record time, even more quickly than I could edit my post. My edit has one more question that I hope you won't mind helping with. Do you think an automatic door bottom is more effective than a saddle with its built-in rubber seal?


I'd argue Yes. You're not going to get the same type of seal with a saddle that comes with a built-in seal. If you're talking about a seal mounted on the side of the door that contacts the saddle, it will be close. The advantage of the automatic bottoms is they push down in a way that ensures a positive seal and they are adjustable. Whereas a factory saddle type seal is (usually) not adjustable and you don't know if it's truly leaving no gap.

And adding to @Mpoes12 comments above, FWIW I went the cheapo route with door seals for the jambs. They are easily replaced if I'm dissatisfied over time. They work as well as expected for now. My only concern is the adjustable models allow tweaking over time in the event there's any movement due to natural settling of the home, extensive use, etc. I thought it was not worth paying the huge difference in cost to get the adjustable models. 

I DID get an Zero automatic door bottom, which while pricey seems very well made. That is a part that I thought the slight premium for a known and respected manufacturer was worthwhile given the mechanical nature of the device.

Just my 2 cents. I'd get an auto door bottom. You don't have to get a Zero. Pemco and Reese make cheaper models I'm sure are just as effective. In my case, I felt by saving hundreds of $ on the jamb seals, I was fine springing for an extra $50 or so to get the Zero auto bottom.

EDIT: And if the saddle seal is installed into the bottom of the door, those are notorious for coming apart eventually, over time. Your HT door probably won't get enough use for that to happen (vs. exterior door for example), but it's very annoying when that happens to a door.


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## doveman

I got distracted by other stuff I had to take care of but I'm hoping to make some progress on my soundproofing soon.

I still have a few things I don't get though.

1) I understand I should use tapered plasterboard for the top layer on the walls and ceiling, as then I just need to tape and fill the tapered area rather than skim plaster the whole surface. I'm thinking of using this Knauf Soundshield Plus https://www.roofingsuperstore.co.uk...x-125mm.html?gclid=CLnnl7u3u9MCFYE4GwodO34IlQ

However, is it only tapered on one edge or on all four? My walls are approx 2.3m high and the long walls are 4.4-4.6m long and the end walls 2.4-3m long. So with those boards that are 2.4m long and 1.2m wide, I'd only need to trim about 0.1m off the length to fit the height of my walls and wouldn't need or want a taper on the top or bottom edge. If all four edges are tapered however and I need to trim them off the top and bottom I'm not sure how that would work, as removing them both would probably take off more than 0.1m wouldn't it? I'll need between 2 and 4 boards for the width of the walls, so I'd need a tapered edge where each of the boards meet.

2) I've attached a photo of the end wall containing the doors to the hallway (which opens inwards) and to the kitchen (which opens outwards). Because the hallway door is butted right up against the left-hand wall, I'll have to remove that door and frame completely in order to fit my clips and two layers of plasterboard on the wall. Before going to such lengths I plan to treat just the floor and ceiling first to see how much of an improvement that makes. However I don't want to just fit clips and two layers of plasterboard to the ceiling but want to do it the recommended way of first ceiling layer, first wall layer, second ceiling layer, second wall layer, to ensure there isn't a weak spot at the edges where sound from above could get through.

Clearly I can't fit full length layers to the walls without removing the door but there's about 27cm space that I can cover. without blocking the doors The ceiling with Genie Clip+Channel+15mm+12.5mm board will come down less than 7cm, so I only really need to go a little beyond that to seal it off. I'm presuming that I'd be able to use tapered board so that I leave the bottom edge tapered and then if I decide to cover the rest of the wall I can join another tapered board to that?

3. If I do cover the walls I'll need to build an inner wall in front of the wall shown in that photo. Above the left-hand door is just a wooden panel with a void behind it, so I couldn't attach any weight-bearing clips there and above the right-hand door seems to be plasterboard, so I couldn't attach any clips there either. Between the two doors and above and below the window on the right appears to be solid wall that could support clips. Is that going to be enough to support the inner wall? I'd remove the left-hand door and frame and then fit an inward-opening door into the inner wall and if necessary I'll fit an outward opening door in the hallway just behind it. The right-hand door opens away from the room and I'd probably just fit a sliding door to the inner wall to cover that, as it's a bit impractical to have an inward-opening door in the middle of the wall there even though that would obviously be better from a soundproofing point of view.


----------



## bubbrik

As part of my soundproofing attempt, I put backer boxes for in-ceiling speakers for atmos use. After channel + DD with GG, I ventured to cut out holes in the DD where the boxes were placed and I made some blunders - 1) holes were not centered in the box and 2) holes were much bigger than what I needed. Both situations leaving no lip for the in-ceiling speakers’ clips to hang on to.

With that mess at hand, I am inclining towards going to a speaker that needs a smaller hole. Originally, it was the RSL 34e at a diameter of ~10” and now to a Volt-8 at ~8”. 

One thought I had was to cover up the hole with 12”x12” piece of 1/2” plywood. The plywood piece will be glued and screwed to the double drywall and have the smaller 8” hole cut in the plywood centered in the box. However I’m not sure if this would work. 

I’m looking for some advice on ways to deal with this. 


Sent from my iPhone using Tapatalk


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## HT Geek

doveman said:


> 1) I understand I should use tapered plasterboard for the top layer on the walls and ceiling, as then I just need to tape and fill the tapered area rather than skim plaster the whole surface. I'm thinking of using this Knauf Soundshield Plus https://www.roofingsuperstore.co.uk...x-125mm.html?gclid=CLnnl7u3u9MCFYE4GwodO34IlQ
> 
> However, is it only tapered on one edge or on all four?


The wallboard being tapered is not critical. The only thing it does is helps joining seams, but you'll need to tape and mud them anyway. The tapered edges make the process a bit easier and allow the mud to seal the crack more uniformly. Basically, they're made that way because it helps professional installers work the material a bit faster. Just make sure the butt-jointed wallboard edges are as smooth as possible on the surface before applying mud and tape, and more mud.




> 3. If I do cover the walls I'll need to build an inner wall in front of the wall shown in that photo. Above the left-hand door is just a wooden panel with a void behind it, so I couldn't attach any weight-bearing clips there and above the right-hand door seems to be plasterboard, so I couldn't attach any clips there either. Between the two doors and above and below the window on the right appears to be solid wall that could support clips. Is that going to be enough to support the inner wall?


Without specific measurements and a reasonably detailed diagram, I can't say for sure, but one of the key factors to consider is the load bearing capability of the clips. As you know, the clips need to be secured to solid framing. Each clip is rated for a maximum support weight, typically around 16 kgs.




> I'd remove the left-hand door and frame and then fit an inward-opening door into the inner wall and if necessary I'll fit an outward opening door in the hallway just behind it.


Communicating door system would be your best bet from a sound-proofing standpoint.




> The right-hand door opens away from the room and I'd probably just fit a sliding door to the inner wall to cover that, as it's a bit impractical to have an inward-opening door in the middle of the wall there even though that would obviously be better from a soundproofing point of view.


FYI, sliding doors are notorious for leaking sound.


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## HT Geek

bubbrik said:


> As part of my soundproofing attempt, I put backer boxes for in-ceiling speakers for atmos use. After channel + DD with GG, I ventured to cut out holes in the DD where the boxes were placed and I made some blunders - 1) holes were not centered in the box and 2) holes were much bigger than what I needed. Both situations leaving no lip for the in-ceiling speakers’ clips to hang on to.
> 
> With that mess at hand, I am inclining towards going to a speaker that needs a smaller hole. Originally, it was the RSL 34e at a diameter of ~10” and now to a Volt-8 at ~8”.
> 
> One thought I had was to cover up the hole with 12”x12” piece of 1/2” plywood. The plywood piece will be glued and screwed to the double drywall and have the smaller 8” hole cut in the plywood centered in the box. However I’m not sure if this would work.
> 
> I’m looking for some advice on ways to deal with this.


You're considering attaching a 12" x 12" piece of 1/2" plywood to the inside of the room? So, you'd get a bump down in the ceiling height in that spot? You could do that but I'm not sure you'll be pleased with the result.

A few other options:

1. If feasible, use the off-center locations for the speakers; as long as you can fit them of course and if they'd be lined up symmetrically. The slight offset in location won't make a big difference audibly. I'm kinda presuming you already thought of this and you can't fit the speakers in the backer box or the holes are not aligned.

2. Can you attach wood to the inside and then screw a new piece of drywall to the interior of the room, then cut the hole in the desired location? I'm thinking you'd get the ceiling back to a uniform surface level.

3. If you can manufacture (or have made) some sort of aesthetic cover/plate, and make a hole in the center of it for the speaker. Perhaps a metal working shop might be able to accommodate something like that. As long as the speaker is securely attached and the metal is thin and light (aluminum would be good), you could jerry-rig it to hold up the metal plate. This is a common practice in the electrical contracting industry to cover up recessed lighting hole goofs. 

No. 3 ^ would also solve the "hole too big for speaker lip" problem. Prime and paint the metal circles before you attach to ceiling.

It would go together sort of like this:


............
............[ Speaker Lip ].............
.......
...........[ Speaker Body ]............

OR this

............
.......
............[ Speaker Lip ].............
...........[ Speaker Body ]............

Depending on speaker design/construction.


----------



## doveman

HT Geek said:


> The wallboard being tapered is not critical. The only thing it does is helps joining seams, but you'll need to tape and mud them anyway. The tapered edges make the process a bit easier and allow the mud to seal the crack more uniformly. Basically, they're made that way because it helps professional installers work the material a bit faster. Just make sure the butt-jointed wallboard edges are as smooth as possible on the surface before applying mud and tape, and more mud.


I had the impression that being tapered allows you to just tape and mud the tapered area to bring it level with the rest of the board, whereas with non-tapered board when you tape and mud the seam you end up making that area higher than the rest of the board so you have to plaster the whole board to make it level.

Going back to my question though, is tapered board actually tapered on all four edges? I can't imagine how it would work otherwise, as you'll need to join the edges on both sides as you work along the wall and depending on the height of the wall you might need to join edges heightwise as well, although I guess it's unlikely anyone would need to join more than 2 boards in that direction so it would be enough if only one of the short edges on each board was tapered.



> Without specific measurements and a reasonably detailed diagram, I can't say for sure, but one of the key factors to consider is the load bearing capability of the clips. As you know, the clips need to be secured to solid framing. Each clip is rated for a maximum support weight, typically around 16 kgs.


The measurements are Left door - 0.87m, wall between doors 0.44m, Right door - 0.85m, remaining wall - 0.85m. The wall is 2.3m high and there's about 27cm above the doors.

If there's not enough structural wall to support the inner wall, I might be able to build a stud wall there. From what I recall, these aren't really supported at either side, with just a gap filled by acoustic caulk there, so it would need to be supported by the ceiling and floor. Looking at that photo I posted imagine I've removed the left-hand door, and frame, would I first clip+channel+double board the entire left-hand wall and then build my stud wall out from that, or should I just treat the left-hand wall up to where the stud wall will start so that the stud wall is only separated from the structural left-hand wall by acoustic caulk?

For the top plate would I screw Genie or A237R clips into the ceiling, then channel and screw the top plate into the channel?

My sub-floor is going to be rubber pads under two layers of chipboard screwed together. Would it be safe to screw the bottom plate to the chipboard, or should I stop the chipboard where the stud wall starts so that I can screw the bottom plate into the concrete structure (through the levelling compound I'll almost certainly need to use before laying the rubber pads)? Doing that would seem to carry the risk of sound transmitting from the concrete into the stud wall though. However I build this wall I'll be doing it as the very last step, after treating both rooms, so that I can easily move stuff between the two rooms as necessary. So if I can screw the base plate into the chipboard it'll be a bit easier but if I really need to screw it to the concrete structure I guess it won't be that hard to cut away a section of the chipboard subfloor to allow me to do that. Obviously the base plate can't go where the doorways will be, so it will only be between the left and right doors and under the window area on the right. 

If the top and bottom plates are isolated from the structure, could I just screw the plasterboard directly to the studs without using clips+channel and how thick would the studs need to be? If I didn't need to build a stud wall and could just use A237 wall clips+channel+15mm plasterboard+12.5mm plasterboard the total depth would be 68.775mm. Obviously the stud wall needs to be spaced away from the structural wall but only enough to provide isolation I think (say 10mm), so if the studs need to be 50mm + the 27.5mm for the two layers of plasterboard the total depth is 87.5mm, which is a bit worse than using clips on the wall but probably OK. If I need to fit clips and channel (combined total of 41.275mm) between the studs and the plasterboard however, it pushes it up the total to 128.775mm, which is getting a bit much.



> Communicating door system would be your best bet from a sound-proofing standpoint.
> 
> FYI, sliding doors are notorious for leaking sound.


For the left-hand door a communicating door system is what I had in mind. I realise a sliding door in front of the right-hand door won't be ideal but as that just goes into my kitchen I'll probably try it first to see if it's good enough, as a normal door there will be rather inconvenient.


----------



## HT Geek

doveman said:


> I had the impression that being tapered allows you to just tape and mud the tapered area to bring it level with the rest of the board, whereas with non-tapered board when you tape and mud the seam you end up making that area higher than the rest of the board so you have to plaster the whole board to make it level.


Yes. Technically, you are correct. However, I stated it's primarily to make pro installers' lives easier because that's who it benefits most. But to your point, what will happen if you don't have tapered edges is you will need to do more careful mudding and more sanding to get it smooth and level. It should not create an end result that is noticeably any different. If that happens to you, then you need to extend our mudding to a wider area in order to slope it appropriately so you can't tell when you're finished with all the mudding and sanding. More work, as I said. But the end result is the same whether the edges are tapered or not.




> Going back to my question though, is tapered board actually tapered on all four edges? I can't imagine how it would work otherwise, as you'll need to join the edges on both sides as you work along the wall and depending on the height of the wall you might need to join edges heightwise as well, although I guess it's unlikely anyone would need to join more than 2 boards in that direction so it would be enough if only one of the short edges on each board was tapered.


In the U.S.A., no. Just on the long edges. Imagine how the corners would have to be constructed if all 4 sides were tapered. You'd always have to fill a larger area of each panel at every corner. 4-way corners would be a big headache.




> If there's not enough structural wall to support the inner wall, I might be able to build a stud wall there. From what I recall, these aren't really supported at either side, with just a gap filled by acoustic caulk there, so it would need to be supported by the ceiling and floor. Looking at that photo I posted imagine I've removed the left-hand door, and frame, would I first clip+channel+double board the entire left-hand wall and then build my stud wall out from that, or should I just treat the left-hand wall up to where the stud wall will start so that the stud wall is only separated from the structural left-hand wall by acoustic caulk?
> 
> For the top plate would I screw Genie or A237R clips into the ceiling, then channel and screw the top plate into the channel?


That said, the stud walls should be attached to one another. That is true for interior/exterior walls and interior/inner walls only. Whether it's with clips or otherwise, from a structural standpoint, all your stud walls need to be connected to and supported by a load bearing wall.

There's too much going on there for me to give you specific advice on how to approach the problem. In complex scenarios, one really needs to examine the site and come up with a plan that meets your needs, building codes, and common sense measures. You can't leave a wall stud section "hanging" per se (not correctly supported in 3 dimensions).




> My sub-floor is going to be rubber pads under two layers of chipboard screwed together. Would it be safe to screw the bottom plate to the chipboard, or should I stop the chipboard where the stud wall starts so that I can screw the bottom plate into the concrete structure (through the levelling compound I'll almost certainly need to use before laying the rubber pads)?


Non-ground level floors are really tough. There's really no good way to do a very good job of sound-proofing them from the structure without going to extremes. Of course, some non-ideal methods are going to be better at sound isolation than others.

I suggest laying the new floor on top of your sub-floor before building the inner stud walls and ceiling. Leave a small gap (5-10mm) along the edge so your new floor does not touch the sides of the structural wall studs. Build your inner wall studs on top of the inner/new sub-floor (including laying the bottom plate on the new sub-floor edge). When you screw the bottom plate to the new sub-floor, ensure your screws are not long enough to penetrate the new sub-floor (this would make a connection to the structural sub-floor below). When you put the inner wall studs up, use clips every meter or so in both dimensions (up/down, side-to-side) to make a connection between your inner stud walls and the outer, structural stud walls. You'll have a solid, stable, and de-coupled (as much as possible) inner wall and floor.




> If the top and bottom plates are isolated from the structure, could I just screw the plasterboard directly to the studs without using clips+channel and how thick would the studs need to be? If I didn't need to build a stud wall and could just use A237 wall clips+channel+15mm plasterboard+12.5mm plasterboard the total depth would be 68.775mm. Obviously the stud wall needs to be spaced away from the structural wall but only enough to provide isolation I think (say 10mm), so if the studs need to be 50mm + the 27.5mm for the two layers of plasterboard the total depth is 87.5mm, which is a bit worse than using clips on the wall....


Right. That's one of the differences between clips & channel vs. a double-stud wall. If you use clips & channel, you wouldn't use a new bottom plate on the stud walls. You'd still build a new sub-floor as described above, but skip the bottom plate and inner stud wall.




> For the left-hand door a communicating door system is what I had in mind. I realise a sliding door in front of the right-hand door won't be ideal but as that just goes into my kitchen I'll probably try it first to see if it's good enough, as a normal door there will be rather inconvenient.


Understood. This hobby is full of compromises.


----------



## HT Geek

HT Geek said:


> 3. If you can manufacture (or have made) some sort of aesthetic cover/plate, and make a hole in the center of it for the speaker. Perhaps a metal working shop might be able to accommodate something like that. As long as the speaker is securely attached and the metal is thin and light (aluminum would be good), you could jerry-rig it to hold up the metal plate. This is a common practice in the electrical contracting industry to cover up recessed lighting hole goofs.
> 
> No. 3 ^ would also solve the "hole too big for speaker lip" problem. Prime and paint the metal circles before you attach to ceiling.
> 
> It would go together sort of like this:
> 
> 
> ............
> ............[ Speaker Lip ].............
> .......
> ...........[ Speaker Body ]............
> 
> OR this
> 
> ............
> .......
> ............[ Speaker Lip ]..............
> ...........[ Speaker Body ]............
> 
> Depending on speaker design/construction.


Just realized this is what I SHOULD have said in previous post is preferred method:

*..........[ Speaker Body ]...........*
............
.......
............[ Speaker Lip ]..............

The idea is to cover up the 'hole too big' problem with a custom plastic or metal disc (presuming a round hole). There are several ways to handle the situation. This route is a suggestion that I've seen electricians use to cover up the same problem with recessed lighting goof-ups.


----------



## bubbrik

HT Geek said:


> Just realized this is what I SHOULD have said in previous post is preferred method:
> 
> 
> 
> *..........[ Speaker Body ]...........*
> 
> ............
> 
> .......
> 
> ............[ Speaker Lip ]..............
> 
> 
> 
> The idea is to cover up the 'hole too big' problem with a custom plastic or metal disc (presuming a round hole). There are several ways to handle the situation. This route is a suggestion that I've seen electricians use to cover up the same problem with recessed lighting goof-ups.




Thanks a bunch @HT Geek

I read the previous illustration and I was confused. So wanted to come back to it again as all this is still new to me. Thanks for the clarification though.

Yes, the original option that I was thinking of would leave a bump at every speaker location. It won’t be clean at all.

Option 1 (off-center): my cuts were bad...I would’ve compromised with them being off-center. But they are just too big for the speaker and also they went all the way to the edge of the box not leaving anything for the speaker clips to hold on to.

Option 2 (wood support): I think I can try this. Put some pieces of wood and screw the circular drywall cutout pieces that have from the previous cut. I have to make sure that the pieces of wood don’t come in the way of the smaller speaker hole that I would drill. Since I am planning to go with DIYSG’s Volt-8, it comes with a 10”x10” Front Baffle https://www.diysoundgroup.com/home-theater-speaker-kits/home-theater-series/volt/volt-8.html. I am exploring if there is a way I can use that baffle.

Option 3 (metal disc): What you are suggesting here is put the circular drywall (double with GG in my case) piece back / mud / seal etc. and reinforce it with a metal disc before Re-cutting for a smaller hole, correct? I’m sorry, I don’t think I follow this well.

Thanks again for your time and suggestions.


Sent from my iPhone using Tapatalk


----------



## doveman

HT Geek said:


> Yes. Technically, you are correct. However, I stated it's primarily to make pro installers' lives easier because that's who it benefits most. But to your point, what will happen if you don't have tapered edges is you will need to do more careful mudding and more sanding to get it smooth and level. It should not create an end result that is noticeably any different. If that happens to you, then you need to extend our mudding to a wider area in order to slope it appropriately so you can't tell when you're finished with all the mudding and sanding. More work, as I said. But the end result is the same whether the edges are tapered or not.


OK, well I'm not keen on "more work"  Good to know I could use either type though.



> In the U.S.A., no. Just on the long edges. Imagine how the corners would have to be constructed if all 4 sides were tapered. You'd always have to fill a larger area of each panel at every corner. 4-way corners would be a big headache.


True, I hadn't thought of that. My walls are short enough that I can cover them with one board anyway, so just being tapered on the longs edges is perfect for me.



> That said, the stud walls should be attached to one another. That is true for interior/exterior walls and interior/inner walls only. Whether it's with clips or otherwise, from a structural standpoint, all your stud walls need to be connected to and supported by a load bearing wall.


I'm only going to build a stud wall in front of that door wall and then only if I have to. The other three walls can easily be done with clip+channel+board with much less space loss.



> There's too much going on there for me to give you specific advice on how to approach the problem. In complex scenarios, one really needs to examine the site and come up with a plan that meets your needs, building codes, and common sense measures. You can't leave a wall stud section "hanging" per se (not correctly supported in 3 dimensions).


I appreciate it's a bit tricky to advise on these things without being on site. I'll probably have to get some advice from a local builder about what can be done with that wall before I start work.



> I suggest laying the new floor on top of your sub-floor before building the inner stud walls and ceiling. Leave a small gap (5-10mm) along the edge so your new floor does not touch the sides of the structural wall studs. Build your inner wall studs on top of the inner/new sub-floor (including laying the bottom plate on the new sub-floor edge). When you screw the bottom plate to the new sub-floor, ensure your screws are not long enough to penetrate the new sub-floor (this would make a connection to the structural sub-floor below). When you put the inner wall studs up, use clips every meter or so in both dimensions (up/down, side-to-side) to make a connection between your inner stud walls and the outer, structural stud walls. You'll have a solid, stable, and de-coupled (as much as possible) inner wall and floor.


I don't know why I said chipboard before but my subfloor is going to be 15mm rubber isolator pads sitting on 10mm OSB spacers (to ensure the new subfloor ends up level with the other rooms) and two layers of 18mm OSB on top of the pads. So there'll be 36mm of OSB that the base plate can be screwed into without the screws coming anywhere near the structural sub-floor.

Apart from the top plate attached to the structural ceiling and the bottom plate attached to the OSB subfloor, I could use clips on the right edge of the stud wall to secure it to the right-hand structural wall. Doing that on the left edge is more tricky as there's only about 40mm of door frame between the wall and the door hinges, so the combined width of the clip and the left-hand vertical stud couldn't be more than that without starting to block the doorway and although I could make the door a bit less wide I might not be able to get furniture through it then!

If the stud wall was spaced 41.275mm away from the structural door wall behind it then I could use clips+channel in that space to reinforce the stud wall but increasing from a 5-10mm gap to 41.275mm is probably going to make the room too small.

I note you said "use clips every meter or so in both dimensions" and not "clips+channel" though, so is there a particular type of clip that I could use to attach the stud wall to the structural walls that would take less space than clips+channel, bearing in mind that I intend to attach the two plasterboard layers to the stud wall directly, not via clips+channel for space reasons?



> Understood. This hobby is full of compromises.


As is life


----------



## impreza276

bubbrik said:


> As part of my soundproofing attempt, I put backer boxes for in-ceiling speakers for atmos use. After channel + DD with GG, I ventured to cut out holes in the DD where the boxes were placed and I made some blunders - 1) holes were not centered in the box and 2) holes were much bigger than what I needed. Both situations leaving no lip for the in-ceiling speakers’ clips to hang on to.
> 
> With that mess at hand, I am inclining towards going to a speaker that needs a smaller hole. Originally, it was the RSL 34e at a diameter of ~10” and now to a Volt-8 at ~8”.
> 
> One thought I had was to cover up the hole with 12”x12” piece of 1/2” plywood. The plywood piece will be glued and screwed to the double drywall and have the smaller 8” hole cut in the plywood centered in the box. However I’m not sure if this would work.
> 
> I’m looking for some advice on ways to deal with this.
> 
> 
> Sent from my iPhone using Tapatalk


Here is an idea that might be more work than you'd like:

Using a rotozip, cut the entire section of ceiling within the box.
Put internal wood bracing along the inner perimeter of the box that a replacement ceiling face plate will be screwed and glued to.
make the new face plates and cut the speaker holes into them
Glue, screw in and finish the new speaker ceiling face plates.


----------



## HT Geek

impreza276 said:


> Here is an idea that might be more work than you'd like:
> 
> Using a rotozip, cut the entire section of ceiling within the box.
> Put internal wood bracing along the inner perimeter of the box that a replacement ceiling face plate will be screwed and glued to.
> make the new face plates and cut the speaker holes into them
> Glue, screw in and finish the new speaker ceiling face plates.


I like that idea better than my suggestions.


----------



## HT Geek

bubbrik said:


> Thanks a bunch @HT Geek
> 
> I read the previous illustration and I was confused. So wanted to come back to it again as all this is still new to me. Thanks for the clarification though.
> 
> Yes, the original option that I was thinking of would leave a bump at every speaker location. It won’t be clean at all.
> 
> Option 1 (off-center): my cuts were bad...I would’ve compromised with them being off-center. But they are just too big for the speaker and also they went all the way to the edge of the box not leaving anything for the speaker clips to hold on to.
> 
> Option 2 (wood support): I think I can try this. Put some pieces of wood and screw the circular drywall cutout pieces that have from the previous cut. I have to make sure that the pieces of wood don’t come in the way of the smaller speaker hole that I would drill. Since I am planning to go with DIYSG’s Volt-8, it comes with a 10”x10” Front Baffle https://www.diysoundgroup.com/home-theater-speaker-kits/home-theater-series/volt/volt-8.html. I am exploring if there is a way I can use that baffle.
> 
> Option 3 (metal disc): What you are suggesting here is put the circular drywall (double with GG in my case) piece back / mud / seal etc. and reinforce it with a metal disc before Re-cutting for a smaller hole, correct? I’m sorry, I don’t think I follow this well.


Not exactly, but close. What I have seen done is you cut a hole the correct size you need in the plate (usually made of plastic or metal). And btw, you'd probably want to trim said plate as well. You want it just large enough to cover your too-big hole. So, make it as small as you can, though it obviously must be a larger radius than your intended hole size.

I like Impreza's idea better though, which is basically: 1) fix your oops hole; and 2) try again! LoL. 

There are a multitude of ways to solve the problem. If you want to explore my suggestion, you might consider inquiring with an electrical contractor store. I don't know what those round plates are called, but there are enough electricians who screw up recessed lighting holes that there is apparently a market for them (and I'm sure a name as well). 

Best of luck to you. I know it really sucks when that type of incident occurs, especially late in the game.  Just remember, the end result will be worth it!


----------



## HT Geek

doveman said:


> I appreciate it's a bit tricky to advise on these things without being on site. I'll probably have to get some advice from a local builder about what can be done with that wall before I start work.


I believe once you've removed your existing sheetrock/plaster/veneer and get down to existing studs, your path forward will become more apparent. It's really guesswork until you can see what you're truly dealing with in terms of existing framing.




> I note you said "use clips every meter or so in both dimensions" and not "clips+channel" though, so is there a particular type of clip that I could use to attach the stud wall to the structural walls that would take less space than clips+channel, bearing in mind that I intend to attach the two plasterboard layers to the stud wall directly, not via clips+channel for space reasons?


I was a bit concerned about topics getting mixed up a tad. What I was attempting to refer to was the process of joining inner wall studs to outer (structural) wall studs, for the purpose of maintaining rigidity and structural reinforcement of your inner wall. In which case, you'd likely use clips to connect your inner wall to the structure while retaining some decoupling. You'll have an air gap of course, and the clips in that case will connect inner/outer studs. Use the IB-3 clips or similar ("L" shaped).

On your non-double wall surfaces, you'd use clips & channel on the structural wall. 

I hope that's easier to follow and a more straightforward explanation.


----------



## bubbrik

HT Geek said:


> Not exactly, but close. What I have seen done is you cut a hole the correct size you need in the plate (usually made of plastic or metal). And btw, you'd probably want to trim said plate as well. You want it just large enough to cover your too-big hole. So, make it as small as you can, though it obviously must be a larger radius than your intended hole size.
> 
> 
> 
> I like Impreza's idea better though, which is basically: 1) fix your oops hole; and 2) try again! LoL.
> 
> 
> 
> There are a multitude of ways to solve the problem. If you want to explore my suggestion, you might consider inquiring with an electrical contractor store. I don't know what those round plates are called, but there are enough electricians who screw up recessed lighting holes that there is apparently a market for them (and I'm sure a name as well).
> 
> 
> 
> Best of luck to you. I know it really sucks when that type of incident occurs, especially late in the game.  Just remember, the end result will be worth it!




Thank you both @HT Geek and @impreza276 for coming to the rescue. I will look for an electrical contractor place and if that fails, I’ll go with the bracing inside the box option. Either of these options will get me to a flush ceiling.

I really appreciate your suggestions and the encouragement (I needed that after this goof).


Sent from my iPhone using Tapatalk


----------



## doveman

HT Geek said:


> I believe once you've removed your existing sheetrock/plaster/veneer and get down to existing studs, your path forward will become more apparent. It's really guesswork until you can see what you're truly dealing with in terms of existing framing.


I don't actually have anything to remove here. It's just plaster over breezeblock, so what you see is what I'll be building onto.



> I was a bit concerned about topics getting mixed up a tad. What I was attempting to refer to was the process of joining inner wall studs to outer (structural) wall studs, for the purpose of maintaining rigidity and structural reinforcement of your inner wall. In which case, you'd likely use clips to connect your inner wall to the structure while retaining some decoupling. You'll have an air gap of course, and the clips in that case will connect inner/outer studs. Use the IB-3 clips or similar ("L" shaped).
> 
> On your non-double wall surfaces, you'd use clips & channel on the structural wall.
> 
> I hope that's easier to follow and a more straightforward explanation.


It's my fault for raising too many questions/issues in one post. I'll try and stick to one at a time in future.

I can see how the IB-3 clips would work to secure the horizontal noggins to the wall behind. I think something else would be needed to attach the vertical studs on the far right (and maybe left but probably not enough room there) to the side walls.

The IB-3 clips are 1-3/4" deep (44.45mm) so if the stud wall is spaced 5mm from the structural wall, a 40mm deep noggin would accommodate the depth of the IB-3, with the screw hole about 17mm in from the back of the noggin. So with 15mm+12.5mm plasterboard attached to the stud wall, the total loss of space would be 5+40+15+12.5=72.5mm, which isn't too bad. If the vertical studs need to be 50mm rather than 40mm then it will be 82.5mm, which is still OK I think.

Which clips would you use for attaching the top plate to the structural concrete ceiling? IB-2 (or similar) with channel and then screw the top plate from below into the channel?


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## BLUCanadian

Hi all,
I have been reading this forum religiously the past month or so... There is so much info here that at times it makes my head swim with all the considerations I will have to keep in mind. I just bought a house and move in date is May 2, but I have been allowed access to the house for the purpose of renovations. I will be embarking on my first dedicated home theatre build and I am both excited and nervous! I will likely open a new thread in the design/construction forum as I will need plenty of expert advise as the process unfolds.
But for now, I have a question regarding floor treatment. The home theater is in the basement. The main reason I will be soundproofing is that directly above the theater room, there are bedrooms where my 2 young daughters will be sleeping during prime-time movie watching hours! The flooring in the bedrooms is being completely removed and replaced with an engeneered hardwood floor. I would like to know what would be the best possible underlay system I could use to assisst with the soundproofing efforts. Currently the plan is to lay down some plywood and then this really thin green underlay that is supposed to somehow help with soundproofling... Im dubious. I would prefer to only have to treat the bedrooms but if the price is right and its worth the extra money, I would be willing to treat the entire main floor in order to keep uniformity if necessary.
Thanks for taking the time to read and respond!


----------



## newtoavs_2018

*How afraid of glass in HT should I be?*

Hi all! Just started a new thread in a different part of AVS and realizing this may be the right thread to consult, so I'm trying here instead 

Planning out a new construction home theater that will be part of a larger multiuse space. I'm new to AVS but have found all of your forums AMAZINGLY helpful, and I'm reaching out now to the community to ask for help on a materials decision about the door to the space.

We want to be able to use the home theater space for other purposes (e.g., family games and lounging). Therefore, we will be making some compromises in terms of construction that I realize aren't totally ideal in terms of sound control. Specifically, we want to do a double door system so that there is a large pass through space that will largely be kept open but able to close off when watching movies.

We are needing advice on how to construct that double door system. Options:

1. (And first design choice to enable visual connection to the multiuse space) Full glass, double door system (imagine modern farmhouse steel door look, but we envision this door frame being made of solid core wood instead of steel) with two side lights (i.e., full height windows on either side). We would do laminated acoustic glass (ideally dual paned) for the glass and also use after market products (like mortised/operable door bottoms, neoprene gasketing around the perimeters and jambs of doors) to improve sound control of the glass. In this option, we'd also have a heavy weight curtain on the theater side of the wall for light and acoustical control when watching movies.
2. Solid core wood double door system
3. Solid core wood barn doors

We have eliminated pocket doors as an option because it seems like that's the worst in terms of sound control (but are open to them if that's not the case).

Wondering opinions about those three options (or other suggestions). Another consideration is we do need to try to keep as much sound as possible in the theater itself, because there is a large open staircase that is about 15 feet away. Also note that we are going to prep the walls and ceilings and flooring of the theater space to provide as much sound control as possible - my main worry is sound leakage through the double door system.

Also, how afraid of glass should we be, as a rule, in terms of:

1) its sound reflective properties (or will the planned heavy weight curtain fix that problem?)
2) sound leakage when compared to solid core wood (or will sealing the windows well and using double paned, laminated glass fix that problem?)


----------



## alinkous

Quick question on making a window plug: The window is dead center my front wall, 58x58". There is about 5.5 - 6" of space between the window and the edge of the molding around the window. Is that enough depth to sandwich some insulation between two MDF panels for some sort of bass trap and be effective? If not, I'll just put the money towards another in room panel or something.

Once the plug is flush with the wall, I'll be lining everything with linacoustic and adding in corner bass traps as well.


----------



## PonzLL

Here's one I can't find an answer to by googling. 

Currently my home theater is basically just my livingroom. My tv is against the outside wall and the neighbor's bedroom is about 12 feet from my house. If I crank up a bass heavy movie and stand between our houses, I can sorta "feel" the booms (and hear them to an extent). 

Now they've never said anything so I don't even think it's going into their house, so I don't really worry about it. 

That said, we're considering moving the theater to the basement, directly below where it's at now. My worry is how sound from the subwoofer will travel through cinder block walls and through the ground. Is that even a thing? That's what I can't seem to find an answer to.


----------



## Helheim

Do I have to do anything special to block this window in or can I just fill it with insulation, rockwool, and drywall over it? Thanks.


----------



## Ladeback

PonzLL said:


> Here's one I can't find an answer to by googling.
> 
> Currently my home theater is basically just my livingroom. My tv is against the outside wall and the neighbor's bedroom is about 12 feet from my house. If I crank up a bass heavy movie and stand between our houses, I can sorta "feel" the booms (and hear them to an extent).
> 
> Now they've never said anything so I don't even think it's going into their house, so I don't really worry about it.
> 
> That said, we're considering moving the theater to the basement, directly below where it's at now. My worry is how sound from the subwoofer will travel through cinder block walls and through the ground. Is that even a thing? That's what I can't seem to find an answer to.


I think it kind of depends on how much bass you have and power going to the subs. I know one of the local guys here on the form was testing out the JTR ULF 4000 in his basement and neighbors blocks away thought it was an earthquake. Now he had 4000 watts going to the subs and was driving them hard. 

I have two 15" 300 watt powered subs and you can feel and hear it upstairs with no soundproofing. Not sure about outside, but the neighbors haven't complained.


----------



## griffindodd

With regard to sound isolation channel and dual layer drywall+GG...

Q1) I'm building my entire room on a floating base, room-within-a-room styleee. When I hang the first layer of drywall on the noise isolation channel, is it allowed to touch the OSB of my floating floor? To be clear, my actual walls will be framed on top of my floating floor, the entire room will sit on that base, air gapped from the outer room walls around it.

Q2) Because my whole theater room is a floating box, does it even make sense to do the sound channels/clips at all or would that be overkill?


----------



## healthnut

PonzLL said:


> Here's one I can't find an answer to by googling.
> 
> 
> 
> Currently my home theater is basically just my livingroom. My tv is against the outside wall and the neighbor's bedroom is about 12 feet from my house. If I crank up a bass heavy movie and stand between our houses, I can sorta "feel" the booms (and hear them to an extent).
> 
> 
> 
> Now they've never said anything so I don't even think it's going into their house, so I don't really worry about it.
> 
> 
> 
> That said, we're considering moving the theater to the basement, directly below where it's at now. My worry is how sound from the subwoofer will travel through cinder block walls and through the ground. Is that even a thing? That's what I can't seem to find an answer to.




I would say no. I have a basement theater with prodigious bass and while sound (particularly low bass), travels vertically into the kitchen (despite all the sound proofing I did), it doesn’t travel thru the concrete walls horizontally. No neighbor issues whatsoever.


Sent from my iPhone using Tapatalk


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## impreza276

PonzLL said:


> Here's one I can't find an answer to by googling.
> 
> Currently my home theater is basically just my livingroom. My tv is against the outside wall and the neighbor's bedroom is about 12 feet from my house. If I crank up a bass heavy movie and stand between our houses, I can sorta "feel" the booms (and hear them to an extent).
> 
> Now they've never said anything so I don't even think it's going into their house, so I don't really worry about it.
> 
> That said, we're considering moving the theater to the basement, directly below where it's at now. My worry is how sound from the subwoofer will travel through cinder block walls and through the ground. Is that even a thing? That's what I can't seem to find an answer to.


I'd say with reasonable confidence that the basement will be a lot better at shielding sound from your neighbor. There is one sure way to find out: Take the sub downstairs and try it out.


----------



## Ladeback

griffindodd said:


> With regard to sound isolation channel and dual layer drywall+GG...
> 
> Q1) I'm building my entire room on a floating base, room-within-a-room styleee. When I hang the first layer of drywall on the noise isolation channel, is it allowed to touch the OSB of my floating floor? To be clear, my actual walls will be framed on top of my floating floor, the entire room will sit on that base, air gapped from the outer room walls around it.
> 
> Q2) Because my whole theater room is a floating box, does it even make sense to do the sound channels/clips at all or would that be overkill?


I have read you thread and seen how you are going to do the floor, but am not sure how you are decoupling the walls to the ceiling and how are you decoupling the ceiling? I am goign to decouple walls to at the ceiling by using IB-3 clips then I won't need to use clips and hat channel on the walls. Mt theater is in the basement and I am not to worried about the floor. I will probably use Dricore on the floors to decouple it. You want to leave a gap all the way around on the floor if you do this. The same goes for drywall or osb. You want to leave a gap so the edges don't touch. You would fill these gaps with acoustical sealant.
@HTGeek could answer these questions better. I like you current rendering on your build thread, especially post #51 .


----------



## griffindodd

Ladeback said:


> I have read you thread and seen how you are going to do the floor, but am not sure how you are decoupling the walls to the ceiling and how are you decoupling the ceiling? I am goign to decouple walls to at the ceiling by using IB-3 clips then I won't need to use clips and hat channel on the walls. Mt theater is in the basement and I am not to worried about the floor. I will probably use Dricore on the floors to decouple it. You want to leave a gap all the way around on the floor if you do this. The same goes for drywall or osb. You want to leave a gap so the edges don't touch. You would fill these gaps with acoustical sealant.
> 
> @HTGeek could answer these questions better. I like you current rendering on your build thread, especially post #51 .


Thanks for the reply. I was planning on de-coupling the walls from my ceiling with clips too. That's why I was wondering if I even needed to do clips on my theater walls as everything else is already air gapped. It would make life much easier (and cheaper) if I can just do double dry wall and GG on my floating frame.


----------



## flynfish

Ladeback said:


> I have read you thread and seen how you are going to do the floor, but am not sure how you are decoupling the walls to the ceiling and how are you decoupling the ceiling? I am goign to decouple walls to at the ceiling by using IB-3 clips then I won't need to use clips and hat channel on the walls. Mt theater is in the basement and I am not to worried about the floor. I will probably use Dricore on the floors to decouple it. You want to leave a gap all the way around on the floor if you do this. The same goes for drywall or osb. You want to leave a gap so the edges don't touch. You would fill these gaps with acoustical sealant.
> 
> 
> @HTGeek could answer these questions better. I like you current rendering on your build thread, especially post #51 .



@Ladeback take a look at dmx airflow underlayment. I am probably going to use that throughout my whole basement. I think it would be a lot cheaper than dricore. You can put osb on top of it or lay carpet directly on it without the osb.


----------



## Livin

flynfish said:


> @Ladeback take a look at dmx airflow underlayment. I am probably going to use that throughout my whole basement. I think it would be a lot cheaper than dricore. You can put osb on top of it or lay carpet directly on it without the osb.


How well does it work vs using cork or rubber? I need to decouple the floor above the ceiling of the HT since I cannot decouple the HT ceiling. Thx

Sent from my SM-G950U using Tapatalk


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## flynfish

Livin said:


> How well does it work vs using cork or rubber? I need to decouple the floor above the ceiling of the HT since I cannot decouple the HT ceiling. Thx
> 
> Sent from my SM-G950U using Tapatalk




I’m not sure as I haven’t heard of anyone using it in these forums, I think it’s a newer product. It does have an R value rating because there is foam on both sides of it.

I figured it would be fine for my concrete basement floor in regards to sound. Not sure how it compares to cork for sound on the first floor

https://www.dmxairflow.com/


----------



## flynfish

Livin said:


> How well does it work vs using cork or rubber? I need to decouple the floor above the ceiling of the HT since I cannot decouple the HT ceiling. Thx
> 
> Sent from my SM-G950U using Tapatalk




The info for their other product called dmx 1 step says it has an STC rating of 66. That product is thicker than the airflow, but it only has one side with foam and less R value. I’m not sure if airflow would have a better or worse STC rating... I couldn’t find mention of one on the airflow site.

https://www.dmx1step.com/


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## Ladeback

flynfish said:


> @Ladeback take a look at dmx airflow underlayment. I am probably going to use that throughout my whole basement. I think it would be a lot cheaper than dricore. You can put osb on top of it or lay carpet directly on it without the osb.


I have looked at this also and I just priced the two out and the DMX is almost half the cost so I probably will go with it. Thanks


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## flynfish

Ladeback said:


> I have looked at this also and I just priced the two out and the DMX is almost half the cost so I probably will go with it. Thanks




Nice! Now you can use those savings on some equipment


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## Ladeback

flynfish said:


> Nice! Now you can use those savings on some equipment


Or other soundproofing material. I have equipment for 7.1 and a 1080p projector, but plan on building for Atmos and 4K.


----------



## kfh227

In a basement build, I've read that a subfloor should be installed over the cement. Is this for sound isolation, an acoustical treatment or both?


What is the proper way to do this part of an install?


----------



## Matt Helander

kfh227 said:


> In a basement build, I've read that a subfloor should be installed over the cement. Is this for sound isolation, an acoustical treatment or both?
> 
> 
> What is the proper way to do this part of an install?


I'll just came here to ask a question (which I will do) but as I did install a subfloor in my basement. I used DriCore, primarily for keeping the space warmer and not having cold floors. I'm not aware of any way it would help with sound consideration at all.


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## Matt Helander

I have a quick opinion question - I'm almost to the drywall phase of by build, and I did the math and I'll have 10 sheets of drywall left. It would take 9 to put a 2nd layer on the ceiling. 

I am considering picking up some green glue and doing that. 

I do not have ANY other soundproofing - the rest of the basement is just a storage room, a mech room, 1 extra bedroom and a bathroom. 2 of the theater walls are concrete, 1 wall shares with the mech room, and the other borders the bedroom / bathroom. 

I have an open stairway to the main level which will not change. 

All that being said - is there really any point to double up the drywall on the ceiling and add green glue? Or will I be wasting my time and money when it won't matter anyway? (presumably because I'm not putting in any additional effort to soundproofing)

Thank you!


----------



## Livin

Matt Helander said:


> I have a quick opinion question - I'm almost to the drywall phase of by build, and I did the math and I'll have 10 sheets of drywall left. It would take 9 to put a 2nd layer on the ceiling.
> 
> I am considering picking up some green glue and doing that.
> 
> I do not have ANY other soundproofing - the rest of the basement is just a storage room, a mech room, 1 extra bedroom and a bathroom. 2 of the theater walls are concrete, 1 wall shares with the mech room, and the other borders the bedroom / bathroom.
> 
> I have an open stairway to the main level which will not change.
> 
> All that being said - is there really any point to double up the drywall on the ceiling and add green glue? Or will I be wasting my time and money when it won't matter anyway? (presumably because I'm not putting in any additional effort to soundproofing)
> 
> Thank you!


What I've been told is... Depends on your goal. 

If you are trying to stop sound from going out of the room... Not having a door on the stairs pretty much kills anything. Sound will go through the stairs

If you're trying to make the room itself sound better (lower the noise floor, etc)... just doing the ceiling is not going to help much. You should do the entire room. This is what I am going to do.

But it also depends on how much noise infiltration you have from outside the room.

You should put a door on the stairs if you are trying to stop sound from leaking out 

Sent from my SM-G950U using Tapatalk


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## healthnut

kfh227 said:


> In a basement build, I've read that a subfloor should be installed over the cement. Is this for sound isolation, an acoustical treatment or both?
> 
> 
> What is the proper way to do this part of an install?




A subfloor can help with bass tactility, which a concrete floor kills. The way to do this properly is called a “floating floor” which is not connected to any concrete walls. I wish now i had done this, because bass response is important to me, and the inertness of the concrete seriously compromises this. 


Sent from my iPhone using Tapatalk


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## Matt Helander

Livin said:


> What I've been told is... Depends on your goal.
> 
> If you are trying to stop sound from going out of the room... Not having a door on the stairs pretty much kills anything. Sound will go through the stairs
> 
> If you're trying to make the room itself sound better (lower the noise floor, etc)... just doing the ceiling is not going to help much. You should do the entire room. This is what I am going to do.
> 
> But it also depends on how much noise infiltration you have from outside the room.
> 
> You should put a door on the stairs if you are trying to stop sound from leaking out
> 
> Sent from my SM-G950U using Tapatalk


The only issue is if i build a door, i'll never he able to get big stuff up or down the basement, i need that opening. 

Sent from my SM-N950U using Tapatalk


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## Livin

Matt Helander said:


> The only issue is if i build a door, i'll never he able to get big stuff up or down the basement, i need that opening.
> 
> Sent from my SM-N950U using Tapatalk


Why? I can remove my doors. 

Sent from my SM-G950U using Tapatalk


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## Matt Helander

Livin said:


> Why? I can remove my doors.
> 
> Sent from my SM-G950U using Tapatalk


It's not about removing the door, or even just that space - it would be losing the wall space on the way down - I need to be able to make the corner.


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## Livin

Matt Helander said:


> It's not about removing the door, or even just that space - it would be losing the wall space on the way down - I need to be able to make the corner.


Door at top or I could see making a Removable wall section at the bottom there for the times you need the space. There is probably a solution that can be used with a little creativity 

Sent from my SM-G950U using Tapatalk


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## jcr159

Livin said:


> Door at top or I could see making a Removable wall section at the bottom there for the times you need the space. There is probably a solution that can be used with a little creativity
> 
> Sent from my SM-G950U using Tapatalk


This... plus, without a door, good luck pressuring a bajillion cubic feet with your subs...


----------



## Matt Helander

Livin said:


> Door at top or I could see making a Removable wall section at the bottom there for the times you need the space. There is probably a solution that can be used with a little creativity
> 
> Sent from my SM-G950U using Tapatalk





jcr159 said:


> This... plus, without a door, good luck pressuring a bajillion cubic feet with your subs...


Hahaha - love it. Thanks guys. Two ideas I did have -
1. Install a sliding "barn door" type deal - It would have to be massive though - 6' or so wide. As for any attempt at sealing that when it was closed - I'm not sure. 
2. Hang a very heavy curtain over the opening. The thought process here is that it would at least muffle the sound that does escape up the stair well. 

The door at the top of the stairs has about a 1" gap at the bottom, but I'm confident I can find something to close that - maybe a rubber strip attached to the bottom of the door that will slide against the floor?


----------



## Livin

Matt Helander said:


> Hahaha - love it. Thanks guys. Two ideas I did have -
> 1. Install a sliding "barn door" type deal - It would have to be massive though - 6' or so wide. As for any attempt at sealing that when it was closed - I'm not sure.
> 2. Hang a very heavy curtain over the opening. The thought process here is that it would at least muffle the sound that does escape up the stair well.
> 
> The door at the top of the stairs has about a 1" gap at the bottom, but I'm confident I can find something to close that - maybe a rubber strip attached to the bottom of the door that will slide against the floor?


Barn door will block some sound but lots of leaking... Drapes will block almost nothing.

A pocket door is better than both of those... But still difficult to seal out sound. 

Sent from my SM-G950U using Tapatalk


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## Matt Helander

Livin said:


> Barn door will block some sound but lots of leaking... Drapes will block almost nothing.
> 
> A pocket door is better than both of those... But still difficult to seal out sound.
> 
> Sent from my SM-G950U using Tapatalk


I understand what you're saying - I know that sound is all about air movement, and really I don't have a good solution for that without making some sacrifices I'm not currently willing to make.


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## Matt Helander

One other question I did have for this group - 

Now that I am ready to start loading up drywall - Should I consider putting some insulation in the walls? I Understand it does virtually nothing for soundproofing the room, but are there any other benefits? Will is make the room itself sound better at all? 

I'm not too worried about the speakers in the wall as I have the sealed MDF backer boxes, but just seeing if there are any benefits to spending $120 on R13 insulation?


----------



## jcr159

Matt Helander said:


> One other question I did have for this group -
> 
> Now that I am ready to start loading up drywall - Should I consider putting some insulation in the walls? I Understand it does virtually nothing for soundproofing the room, but are there any other benefits? Will is make the room itself sound better at all?
> 
> I'm not too worried about the speakers in the wall as I have the sealed MDF backer boxes, but just seeing if there are any benefits to spending $120 on R13 insulation?


Door at the top with a 1” air gap is fine from a pressuring the room with bass perspective. Sliding barn door would also work for this purpose. Curtain not so much... 

From a sound containment perspective, none of the items will do anything for ya... sound gets out like water through a sieve. Heavy solid door with weather strip on all sides would help, but still probably not be enough. 

As for the insulation, it doesn’t hurt, and will help reduce resonance in the walls so they don’t sound like a drum, but I don’t know if you will actually hear it in room. Look at it this way, it’ll keep the heat in a little better since you are below grade....


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## Matt Helander

jcr159 said:


> Door at the top with a 1” air gap is fine from a pressuring the room with bass perspective. Sliding barn door would also work for this purpose. Curtain not so much...
> 
> From a sound containment perspective, none of the items will do anything for ya... sound gets out like water through a sieve. Heavy solid door with weather strip on all sides would help, but still probably not be enough.
> 
> As for the insulation, it doesn’t hurt, and will help reduce resonance in the walls so they don’t sound like a drum, but I don’t know if you will actually hear it in room. Look at it this way, it’ll keep the heat in a little better since you are below grade....


I thought about that aspect too - But when I spoke to my homebuilder, I asked what they use to insulate when they finish the basement in these models, and he said "Uh, nothing" Apparently the foil faced stuff the put up against the concrete is pretty damn good - something stupid like R19. 

I AM laying down subfloor, I have a stack of Dricore waiting - so that should help with the thermal part. I just don't know if any extra will really make a $120 difference or not.


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## jjcook

*Rockwool clearance at Home Depot*

Heads up that Rockwool is on clearance at Home Depot nationwide for 50% off as they are replacing it with the Owens Corning Thermafiber mineral wool products, ~$24 per 60 sqft of 3/3.5"-thick

However, I haven't checked with local builder supply houses to see if their normal price for the small quantity that we buy in is close to Home Depot normal or clearance price -- anybody have feedback on this?


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## jcr159

Matt Helander said:


> I thought about that aspect too - But when I spoke to my homebuilder, I asked what they use to insulate when they finish the basement in these models, and he said "Uh, nothing" Apparently the foil faced stuff the put up against the concrete is pretty damn good - something stupid like R19.
> 
> I AM laying down subfloor, I have a stack of Dricore waiting - so that should help with the thermal part. I just don't know if any extra will really make a $120 difference or not.


I hear ya, I’m not sure either, but my home built in 2009 was energy star certified and part of that required the builder to insulate the top 5 feet of block to meet the spec... I assume that’s cause the top 5 feet get the coldest, but not sure how much it actually helps with anything... thermal or sound wise...


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## HT Geek

doveman said:


> Which clips would you use for attaching the top plate to the structural concrete ceiling? IB-2 (or similar) with channel and then screw the top plate from below into the channel?


It all depends on your particular scenario. The most common is the IB-3 clip, because there's typically a slight offset both horizontally and vertically.


----------



## HT Geek

newtoavs_2018,

I didn't see a response to your query. I'm just returning from a multi-week absence from AVS due to new job and biz travel, and catching up. I hate to see someone new not get their questions answered. Apologies it took so long! Anyway, here goes:




newtoavs_2018 said:


> Hi all! Just started a new thread in a different part of AVS and realizing this may be the right thread to consult, so I'm trying here instead
> 
> Planning out a new construction home theater that will be part of a larger multiuse space. I'm new to AVS but have found all of your forums AMAZINGLY helpful, and I'm reaching out now to the community to ask for help on a materials decision about the door to the space.
> 
> We want to be able to use the home theater space for other purposes (e.g., family games and lounging). Therefore, we will be making some compromises in terms of construction that I realize aren't totally ideal in terms of sound control. Specifically, we want to do a double door system so that there is a large pass through space that will largely be kept open but able to close off when watching movies.
> 
> We are needing advice on how to construct that double door system. Options:
> 
> 1. (And first design choice to enable visual connection to the multiuse space) Full glass, double door system (imagine modern farmhouse steel door look, but we envision this door frame being made of solid core wood instead of steel) with two side lights (i.e., full height windows on either side). We would do laminated acoustic glass (ideally dual paned) for the glass and also use after market products (like mortised/operable door bottoms, neoprene gasketing around the perimeters and jambs of doors) to improve sound control of the glass. In this option, we'd also have a heavy weight curtain on the theater side of the wall for light and acoustical control when watching movies.
> 2. Solid core wood double door system
> 3. Solid core wood barn doors
> 
> We have eliminated pocket doors as an option because it seems like that's the worst in terms of sound control (but are open to them if that's not the case).


Well, simply put - from a sound-proofing perspective - yes, pocket doors tend to be the equivalent of sieves. 

Glass presents a few challenges. First, it is relatively good at reflecting sound. It will be a disservice to you from the standpoint of the _inside _of your home theater room. Second, it's not a very good insulator of sound at certain frequencies that resonate with the glass. Double or triple pane glass panels help a bit, but there's such a small air gap in between panes that it won't help to any substantial degree.




> Wondering opinions about those three options (or other suggestions). Another consideration is we do need to try to keep as much sound as possible in the theater itself, because there is a large open staircase that is about 15 feet away. Also note that we are going to prep the walls and ceilings and flooring of the theater space to provide as much sound control as possible - my main worry is sound leakage through the double door system.
> 
> Also, how afraid of glass should we be, as a rule, in terms of:
> 
> 1) its sound reflective properties (or will the planned heavy weight curtain fix that problem?)
> 2) sound leakage when compared to solid core wood (or will sealing the windows well and using double paned, laminated glass fix that problem?)


I'll throw out a few random, but related thoughts. 

First, if you were to apply thick curtains over your door, that would help. It's not ideal, but it will help if they are dense enough. The folds in the curtains will also help deflect some sound at irregular angles, so you'd gain a bit from both that and their mass. However, it's not going to stop all sound and some sound will get around them.

Unfortunately, all of your door ideas will be detrimental to sound containment in your HT room. Sound will travel through any cracks, crevices, open seams, etc. Think of how water tries to move through a door or opening. Sound functions much the same way. If there is any opening, it will find it.

Pocket doors are bad partly because when they are in the closed position, you have air gaps inside the adjacent walls. Most of all, you just won't ever be able to get a good door seal when they are closed.

I understand the desire or need to compromise, and that in this case creating your multi-use space seems to be your priority. Aside from heavy curtains as mentioned above, you may also want to consider attaching sound dampening materials to the HT room side of your doors and the shared wall (with remainder of the multi-use space), if that's practical. It's tough to advise without room diagrams and photos.

To be clear, I'm referring to acoustic panels, such as these.


----------



## HT Geek

alinkous said:


> Quick question on making a window plug: The window is dead center my front wall, 58x58". There is about 5.5 - 6" of space between the window and the edge of the molding around the window. Is that enough depth to sandwich some insulation between two MDF panels for some sort of bass trap and be effective? If not, I'll just put the money towards another in room panel or something.
> 
> Once the plug is flush with the wall, I'll be lining everything with linacoustic and adding in corner bass traps as well.


It sounds as if you're confusing bass traps and window plugs. The purpose of window plugs is simply to prevent sound leakage in or out. The use of a "plug" design has two primary purposes: 1) Aforementioned sound-proofing effort; and 2) ability to remove if necessary in the future. The goal is to create a broadband diffuser, not a bass trap.

Bass traps require large amounts of space to be effective, and are specifically designed to address LFE.


----------



## HT Geek

Helheim said:


> Do I have to do anything special to block this window in or can I just fill it with insulation, rockwool, and drywall over it? Thanks.


That depends on three primary factors:

1) Local building codes on the subject (if any)
2) Room construction / how you're building out the room
3) Whether or not you want to the window to be readily accessible when you're finished building the room

The photo looks like you've got metal studs in front of the window, but I can't tell for sure if that's what they are. So, going out on a limb for a moment and guessing those are vertical metal studs and that your drywall will be attached to them in the room....

1) Hopefully, you have an air gap between those metal studs and the structural house framing
2) It's really virtually impossible to create a traditional window plug with those studs blocking access to the window
3) What you could do is simply stuff insulation in the window cavity, and then seal off the rough-in area in the room with an appropriately sized plywood or OSB sheet to seal off the window, though that is dependent on sufficient space and continuing to have an air gap between it and the metal studs.

A more common approach is to frame around the window opening and insert a window plug, though some people still seal it off completely and drywall over the window opening even if they framed around it.


----------



## HT Geek

Apologies on the slow response. New job, biz travel, and other obligations kept me away from AVS for much of the past 6 weeks or so. 



griffindodd said:


> With regard to sound isolation channel and dual layer drywall+GG...
> 
> Q1) I'm building my entire room on a floating base, room-within-a-room styleee. When I hang the first layer of drywall on the noise isolation channel, is it allowed to touch the OSB of my floating floor?


No.




> To be clear, my actual walls will be framed on top of my floating floor, the entire room will sit on that base, air gapped from the outer room walls around it.


That's good, but you still want a slight (1/4") gap between the bottom of the drywall wall pieces and the room's sub-floor. The idea is to disconnect surfaces surfaces that will have sound waves directed at them, as much as is reasonably possible. It helps reduce sound transmission between materials from vibration by very slightly breaking one of their physical connections. 

Caulk the gap with acoustic caulk when you're done. And do the same at the top, where it meets the ceiling.

If you have a larger gap for some reason (floors and ceilings are rarely perfectly uniform), use backer rod (aka "caulk saver" to some) to help the caulk stick in place.




> Q2) Because my whole theater room is a floating box, does it even make sense to do the sound channels/clips at all or would that be overkill?


If you are building a true "room within a room" (which it sounds like you are), then yes it would be overkill and you could potentially and inadvertently create a triple-leaf phenomenon (which is bad).


----------



## HT Geek

flynfish said:


> I’m not sure as I haven’t heard of anyone using it in these forums, I think it’s a newer product. It does have an R value rating because there is foam on both sides of it.


You may already be aware of this, but FYI the R-rating of products has no bearing on sound-proofing. It is a measure of heat transmission/insulation value.




> I figured it would be fine for my concrete basement floor in regards to sound. Not sure how it compares to cork for sound on the first floor


Much depends on what one is trying to accomplish. Standard carpet and pad work surprisingly well for most people in a basement, from the perspective of those in the HT room. It does a good job of damping reflections off the concrete floor in the room, and there is no one below that floor to bother. Vibrations in the floor are well mitigated before they leave the house.




flynfish said:


> The info for their other product called dmx 1 step says it has an STC rating of 66.


No published lab report = be very skeptical.

Videos with people wearing 'seen on TV' telemarketing headsets = be wary.

Sold at Home Depot = be wary.

Also, keep in mind that STC is most useful when comparing products. It is marginal at best when making a decision on materials to use for sound-proofing. I say that because it is an amalgamation of TL (Transmission Loss) readings across a portion of the human-audible sound spectrum. It does not address LFE or high freqs (>5000 Hz). To add more confusion to it, there are some lab tests that report LFE and HFE values that are not used in the STC calculations.

You really need to dig into lab data to know for sure what you're buying and whether it is likely to be of benefit to you.




> That product is thicker than the airflow, but it only has one side with foam and less R value. I’m not sure if airflow would have a better or worse STC rating... I couldn’t find mention of one on the airflow site.
> 
> https://www.dmx1step.com/


----------



## HT Geek

Matt Helander said:


> I have a quick opinion question - I'm almost to the drywall phase of by build, and I did the math and I'll have 10 sheets of drywall left. It would take 9 to put a 2nd layer on the ceiling.
> 
> I am considering picking up some green glue and doing that.
> 
> I do not have ANY other soundproofing - the rest of the basement is just a storage room, a mech room, 1 extra bedroom and a bathroom. 2 of the theater walls are concrete, 1 wall shares with the mech room, and the other borders the bedroom / bathroom.
> 
> I have an open stairway to the main level which will not change.
> 
> All that being said - is there really any point to double up the drywall on the ceiling and add green glue? Or will I be wasting my time and money when it won't matter anyway? (presumably because I'm not putting in any additional effort to soundproofing)


Yes; though whether or not it's truly worth it may depend on what is above your room and/or what your HT room's ceiling joists are connected to, and what those things are connected to (i.e. flanking noise via beams in your home to who-knows-where).

Basically, adding more mass is not a bad thing. It can only help. Just don't exceed the weight limit of your ceiling joists. If you have standard 2x6 19.2" O.C. or 24" O.C., you'll be fine with 2x sheets.

EDIT: I missed the part about the open stairway and no door at the top. I'd still say the 2x drywall ceiling is worthwhile if you're looking for somewhere to use your extra drywall. Adding a door somewhere will make the thicker ceiling more effective. OTOH, as others have mentioned, if you have no door then this may be a moot point. However, I'd personally do it anyway (2x drywall on ceiling), as you can always add a door. Not so easy to add more drywall once the room is complete.


----------



## kfh227

In my eventual basement build, I was going to build a subfloor and put the walls on top. Is it better to have the walls built directly on the concrete and then build the subfloor detached?


How big of a difference is it?


----------



## Helheim

HT Geek said:


> That depends on three primary factors:
> 
> 1) Local building codes on the subject (if any)
> 2) Room construction / how you're building out the room
> 3) Whether or not you want to the window to be readily accessible when you're finished building the room
> 
> The photo looks like you've got metal studs in front of the window, but I can't tell for sure if that's what they are. So, going out on a limb for a moment and guessing those are vertical metal studs and that your drywall will be attached to them in the room....
> 
> 1) Hopefully, you have an air gap between those metal studs and the structural house framing
> 2) It's really virtually impossible to create a traditional window plug with those studs blocking access to the window
> 3) What you could do is simply stuff insulation in the window cavity, and then seal off the rough-in area in the room with an appropriately sized plywood or OSB sheet to seal off the window, though that is dependent on sufficient space and continuing to have an air gap between it and the metal studs.
> 
> A more common approach is to frame around the window opening and insert a window plug, though some people still seal it off completely and drywall over the window opening even if they framed around it.


Ya those are metal studs I added. I ended up spraying it with a thermal sealer then foam insulation then stuffing it with roxul insulation. Yes there is an air gap between the exterior concrete and walls.
http://www.avsforum.com/forum/attachment.php?attachmentid=2387538&d=1523282734

Thanks


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## HT Geek

kfh227 said:


> In my eventual basement build, I was going to build a subfloor and put the walls on top. Is it better to have the walls built directly on the concrete and then build the subfloor detached?


The preferred method is to build the sub-floor first, then build the walls on top of it. However, that presumes there is an existing structural wall to which you will attach your inner stud wall via IB-3 or similar clips. Thus the term "room within a room." Basically, you end up with two stud walls. One - the outer wall - is your normal structural wall that helps hold up your house. Your inner wall is not load bearing and exists solely to define your HT room.

You want an air gap between the two stud walls. 1" is a good figure. That allows some room for variation due to not-perfectly-straight studs (wood), settling, and other variations in construction. You could do 1/2" but 1" gives you a bit more wiggle room per se.

Make sense?




> How big of a difference is it?


No one will be able to give you a definitive answer, such as "_x_db better sound attenuation," but I can tell you what I described would be following best practices.


----------



## HT Geek

Helheim said:


> Ya those are metal studs I added. I ended up spraying it with a thermal sealer then foam insulation then stuffing it with roxul insulation. Yes there is an air gap between the exterior concrete and walls.
> http://www.avsforum.com/forum/attachment.php?attachmentid=2387538&d=1523282734
> 
> Thanks


Looks great. You're in good shape then.


----------



## kfh227

HT Geek said:


> The preferred method is to build the sub-floor first, then build the walls on top of it. However, that presumes there is an existing structural wall to which you will attach your inner stud wall via IB-3 or similar clips. Thus the term "room within a room." Basically, you end up with two stud walls. One - the outer wall - is your normal structural wall that helps hold up your house. Your inner wall is not load bearing and exists solely to define your HT room.
> 
> You want an air gap between the two stud walls. 1" is a good figure. That allows some room for variation due to not-perfectly-straight studs (wood), settling, and other variations in construction. You could do 1/2" but 1" gives you a bit more wiggle room per se.
> 
> Make sense?



Forgot to say that in the basement itself, I am doing a room within a room. none of the structure for the home theater will be attached to the wall or ceiling in the basement. I want to build the subfloor then but the walls directly on top of it and I'll probably do just that. I'll be buying a framing nailer..... I already own a pancake compressor.


----------



## Helheim

Maybe a dumb question but even with 2 layers of drywall on each side of this wall isn't the sound just going to go through that thin metal at the top anyway since most of the wall is on the other side of the joist? Should I put some dynamat or something on it?


----------



## griffindodd

HT Geek said:


> Apologies on the slow response. New job, biz travel, and other obligations kept me away from AVS for much of the past 6 weeks or so.
> 
> That's good, but you still want a slight (1/4") gap between the bottom of the drywall wall pieces and the room's sub-floor. The idea is to disconnect surfaces surfaces that will have sound waves directed at them, as much as is reasonably possible. It helps reduce sound transmission between materials from vibration by very slightly breaking one of their physical connections.
> 
> Caulk the gap with acoustic caulk when you're done. And do the same at the top, where it meets the ceiling.
> 
> If you have a larger gap for some reason (floors and ceilings are rarely perfectly uniform), use backer rod (aka "caulk saver" to some) to help the caulk stick in place.
> 
> If you are building a true "room within a room" (which it sounds like you are), then yes it would be overkill and you could potentially and inadvertently create a triple-leaf phenomenon (which is bad).


Thank you for taking the time to answer these questions!!!

One more quicky. My subfloor will be (from the ground up) u-boats>2x4s 16" on center>OSB with glue and screw>30# roofing felt> OSB. Is it worth spending money on r13 to put between the 2x4's or will that do pretty much nothing for sound control?


----------



## newtoavs_2018

Oh my goodness, THANK YOU so much, HT Geek, for your thoughtful response! I so appreciate it!!

To divide the family room from the theater, we have decided to go with a double door system with solid core doors. The wall itself between the two rooms is 16'. In the middle of that wall, we'll place two, 3' doors that swing open 180 degrees to rest against the inside of the theater wall. That way, when we're using it as multipurpose space, there is a full 6' opening in the middle of that 16' wall for pass through. When we want to use the theater as a theater, we'll shut those doors. 

We are currently deciding whether to use 1 3/4" solid core doors and apply after market soundproofing materials (e.g., operable mortised door bottom, astragals for where the doors meet in the middle, and weatherstripping silicone seals for along the door jambs) or to invest in expensive "acoustic rated doors" that claim they can achieve greater STC. For context, we are planning to otherwise "soundproof" our theater "box" (16' x 22.5') by using isolation clips, mass loaded vinyl, etc. (per the principles espoused on this site including dampening, decoupling, mass, etc.).

Any feedback on that plan would be greatly appreciated.

Lastly, we are also trying to decide how to handle HVAC and recessed lighting in the theater space. From what I gather on this forum, a lot of people handle this by building out soffit boxes around the perimeter of their theater to provide a) housing for HVAC and recessed lighting) and b) a place to install cove lighting LED light strips. Is this accurate? 

However, I've also read that HVAC in the theater can be problematic because it allows sound transmission through other areas of the house? I'm a little confused on that front. Also, wondering how people construct those "boxes" in which wall-mounted speakers should live, as it seems like it may be necessary to cut into that "soundproof'd theater box" (i.e., the original 16'x22.5') in order to install those speakers.

Thanks again to you and the rest of the community for your incredibly helpful feedback - and your patience with a newbie!!!





HT Geek said:


> newtoavs_2018,
> 
> I didn't see a response to your query. I'm just returning from a multi-week absence from AVS due to new job and biz travel, and catching up. I hate to see someone new not get their questions answered. Apologies it took so long! Anyway, here goes:
> 
> 
> 
> 
> Well, simply put - from a sound-proofing perspective - yes, pocket doors tend to be the equivalent of sieves.
> 
> Glass presents a few challenges. First, it is relatively good at reflecting sound. It will be a disservice to you from the standpoint of the _inside _of your home theater room. Second, it's not a very good insulator of sound at certain frequencies that resonate with the glass. Double or triple pane glass panels help a bit, but there's such a small air gap in between panes that it won't help to any substantial degree.
> 
> 
> 
> 
> I'll throw out a few random, but related thoughts.
> 
> First, if you were to apply thick curtains over your door, that would help. It's not ideal, but it will help if they are dense enough. The folds in the curtains will also help deflect some sound at irregular angles, so you'd gain a bit from both that and their mass. However, it's not going to stop all sound and some sound will get around them.
> 
> Unfortunately, all of your door ideas will be detrimental to sound containment in your HT room. Sound will travel through any cracks, crevices, open seams, etc. Think of how water tries to move through a door or opening. Sound functions much the same way. If there is any opening, it will find it.
> 
> Pocket doors are bad partly because when they are in the closed position, you have air gaps inside the adjacent walls. Most of all, you just won't ever be able to get a good door seal when they are closed.
> 
> I understand the desire or need to compromise, and that in this case creating your multi-use space seems to be your priority. Aside from heavy curtains as mentioned above, you may also want to consider attaching sound dampening materials to the HT room side of your doors and the shared wall (with remainder of the multi-use space), if that's practical. It's tough to advise without room diagrams and photos.
> 
> To be clear, I'm referring to acoustic panels, such as these.


----------



## HT Geek

newtoavs_2018 said:


> ... we have decided to go with a double door system with solid core doors. The wall itself between the two rooms is 16'. In the middle of that wall, we'll place two, 3' doors that swing open 180 degrees to rest against the inside of the theater wall. That way, when we're using it as multipurpose space, there is a full 6' opening in the middle of that 16' wall for pass through. When we want to use the theater as a theater, we'll shut those doors.


Gotcha. If that approach suits your lifestyle and needs, then that's good.




> We are currently deciding whether to use 1 3/4" solid core doors and apply after market soundproofing materials (e.g., operable mortised door bottom, astragals for where the doors meet in the middle, and weatherstripping silicone seals for along the door jambs) or to invest in expensive "acoustic rated doors" that claim they can achieve greater STC. For context, we are planning to otherwise "soundproof" our theater "box" (16' x 22.5') by using isolation clips, mass loaded vinyl, etc. (per the principles espoused on this site including dampening, decoupling, mass, etc.).


My suggestion is that - aside from cost difference as a potential issue - think about how those acoustic doors are going to be connected to their neighboring walls and how they will be sealed when closed, as compared to the normal solid core door alternative. Will your acoustic doors be sealed as well as, or better than, the solid core doors? My point is: first establish whether or not moving from your solid core door concept to an acoustic door concept, how will it impact the ability of noise to escape around the doors?

So, if you presume for a moment that the door seals in either scenario are equal, then the question boils down to a cost/benefit analysis strictly of the doors themselves. And at that point you're comparing apples to apples (sound attenuation of one versus the other). Then at that point, let's assume theoretically that the acoustic doors block all sound. What will happen is you'll still have sound transmitting from the walls adjacent to the doors. And the question becomes, how well do the acoustic doors block sound relative to those walls? Are they as good as or better than sound attenuation versus the walls?

It's a value proposition so long as the seals on the acoustic doors are as-good-as or better than those of the solid core doors. Then it's a question of whether or not the acoustic doors are worth it or not.

Another factor could be where the doors are in relation to the sound waves as they will emanate from your speakers. Your main (front) speakers in particular. Let's say your doors will be directly facing the front speakers. That means the sound emanating from your speakers will hit the doors at full volume, and those doors will be the first point of reflection for some of the sound coming out of the speakers. The most intense (loudest) volume of sound coming out of a speaker is nearly always directly in front of it. So, if you have a scenario like that then I think it increases the value of using "better" doors.

I would suggest if you can get your hands on actual lab data of any door, look at how it fares with TL (Transmission Loss) of the lower frequencies. Heavier doors should perform substantially better with LFE (Low Frequency Emissions). That ought to be where the acoustic door would shine, and I would tend to base my opinion (irrespective of cost) on that factor more than anything else (i.e. if you could compare lab tested LFE TL of acoustic vs. solid core doors). The higher freqs are easier to block to begin with; good seals will be instrumental in that regard. 




> ... Lastly, we are also trying to decide how to handle HVAC and recessed lighting in the theater space. From what I gather on this forum, a lot of people handle this by building out soffit boxes around the perimeter of their theater to provide a) housing for HVAC and recessed lighting) and b) a place to install cove lighting LED light strips. Is this accurate?


Partly. Soffits server a variety of purposes (which vary depending on the room). They are typically used to hide HVAC and other infrastructure (e.g. electrical wiring or plumbing). Whether you have a soffit or not, you can install crown moulding and conceal light strips inside it. You'll get a similar effect whether there is a soffit or not.

I'm not sure if you're getting a bit mixed up with regards to backer boxes versus soffits when it comes to recessed lighting. For recessed fixtures, if you are going to the length of sound proofing the room (as you are), you should build backer boxes. Those backer boxes create a shell inside the ceiling that help isolate any sound that escapes around the edge or openings of a recessed light fixture, so they are contained before they have a chance to bounce around inside your ceiling.




> However, I've also read that HVAC in the theater can be problematic because it allows sound transmission through other areas of the house? I'm a little confused on that front.


It can. It's a form of flanking noise. What happens is sound waves enter your HVAC grille and travel through your ducts, exiting in another room. It's a much more prevalent problem with rigid metal ductwork versus flex-duct. You may have experienced this at some point in a home where you find in certain areas (e.g. kitchen duct hood) you can hear a lawnmower outside or a dog barking. Bathroom fans are often a similar source of nuisance noise in homes, because they also typically use rigid metal conduit for exhausting air out of the home. One of the reasons why these particular things are prevalent at noise transmission (besides they're conduits made of rigid metal) is they tend to be straight and short (home builders don't like to spend money).

Ideally, here's what to focus on at a high-level, re: your HVAC:

1. Use _insulated_ flexible duct
2. Make plenty of bends in the path of the ductwork
3. Use longer runs

These concepts will provide several benefits:

1. Slow down the velocity of the air (quieter at the grilles)
2. Flanking sound will get absorbed via the bends in the duct as the sound bounces around inside it




> Also, wondering how people construct those "boxes" in which wall-mounted speakers should live, as it seems like it may be necessary to cut into that "soundproof'd theater box" (i.e., the original 16'x22.5') in order to install those speakers.


Same thing as the recessed lights. Build a backer box and insert the speaker into it. That's why I placed my recessed wall speakers in columns, which is a common method of getting around the problem. Recessing speakers into the walls also means you need to take their depth + the depth of a backer box into consideration when planning the offset of your inner walls from your outer walls in a room-within-a-room concept. You do not want that backer box touching the outer stud wall or the drywall of an adjacent room.


----------



## HT Geek

Helheim said:


> Maybe a dumb question but even with 2 layers of drywall on each side of this wall isn't the sound just going to go through that thin metal at the top anyway since most of the wall is on the other side of the joist? Should I put some dynamat or something on it?


I can't tell exactly what the scenario is from that photo. That looks like a metal header, which is part of a metal stud wall. It looks to me as if the header is touching a wood I-beam / joist. That would not be good. Sound will transfer (via vibration) from one to the other, which is why you ideally want an air gap with as few connecting points (usually clips placed as needed) to join them.


----------



## HT Geek

griffindodd said:


> Thank you for taking the time to answer these questions!!!
> 
> One more quicky. My subfloor will be (from the ground up) u-boats>2x4s 16" on center>OSB with glue and screw>30# roofing felt> OSB. Is it worth spending money on r13 to put between the 2x4's or will that do pretty much nothing for sound control?


Thought I answered this earlier, but just realized I did not. 

Yes, I'd recommend including insulation (pink fluffy or whatever is cheapest - but not blown insulation) in between the 2x4's. It will have a minor but useful impact on sound proofing. Perhaps more importantly, it will deaden the sound of walking on the OSB (if you bang your foot on the finished product it will sound solid / not hollow).


----------



## newtoavs_2018

Again...THANK YOU!!! I have a few follow up questions.

Your guidance about the acoustic vs normal solid core door is extremely helpful. We indeed have a set up as you intuited - the doors will be directly facing the front speakers (about 22 feet apart). Given this, are there any other measures that can be taken to upgrade a normal solid core door? E.g., mounting the acoustic panels you described onto the door? Or will it never stand up to the acoustic door (e.g., they claim those can be up to 55 STC - not sure how that sound rating stands up to the potential rating we could even achieve by the mass/dampening/decoupling strategies in building the room-within-a-room anyway).

With the backer boxes you describe, is there a particular thread on this forum that describes how to construct those so we can share it with our architect? And do you build those backer boxes into columns/soffits outside the "soundproof box" or do you recess it into the "soundproof box" (hence your feedback about the offset of the inner wall from the outerwall)?

Lastly, if we need additional consulting, do you know of anyone who would be able to provide some input and even some drawings for how to construct those backer boxes, room within a room, planning for cove lighting, hvac, etc.? We are almost there but not quite...the original consultant we hired wasn't very clear in communicating with us about what's needed and we're feeling a bit unsure and stuck. 

Million thanks!!!





HT Geek said:


> Gotcha. If that approach suits your lifestyle and needs, then that's good.
> 
> 
> 
> 
> My suggestion is that - aside from cost difference as a potential issue - think about how those acoustic doors are going to be connected to their neighboring walls and how they will be sealed when closed, as compared to the normal solid core door alternative. Will your acoustic doors be sealed as well as, or better than, the solid core doors? My point is: first establish whether or not moving from your solid core door concept to an acoustic door concept, how will it impact the ability of noise to escape around the doors?
> 
> So, if you presume for a moment that the door seals in either scenario are equal, then the question boils down to a cost/benefit analysis strictly of the doors themselves. And at that point you're comparing apples to apples (sound attenuation of one versus the other). Then at that point, let's assume theoretically that the acoustic doors block all sound. What will happen is you'll still have sound transmitting from the walls adjacent to the doors. And the question becomes, how well do the acoustic doors block sound relative to those walls? Are they as good as or better than sound attenuation versus the walls?
> 
> It's a value proposition so long as the seals on the acoustic doors are as-good-as or better than those of the solid core doors. Then it's a question of whether or not the acoustic doors are worth it or not.
> 
> Another factor could be where the doors are in relation to the sound waves as they will emanate from your speakers. Your main (front) speakers in particular. Let's say your doors will be directly facing the front speakers. That means the sound emanating from your speakers will hit the doors at full volume, and those doors will be the first point of reflection for some of the sound coming out of the speakers. The most intense (loudest) volume of sound coming out of a speaker is nearly always directly in front of it. So, if you have a scenario like that then I think it increases the value of using "better" doors.
> 
> I would suggest if you can get your hands on actual lab data of any door, look at how it fares with TL (Transmission Loss) of the lower frequencies. Heavier doors should perform substantially better with LFE (Low Frequency Emissions). That ought to be where the acoustic door would shine, and I would tend to base my opinion (irrespective of cost) on that factor more than anything else (i.e. if you could compare lab tested LFE TL of acoustic vs. solid core doors). The higher freqs are easier to block to begin with; good seals will be instrumental in that regard.
> 
> 
> 
> 
> 
> Partly. Soffits server a variety of purposes (which vary depending on the room). They are typically used to hide HVAC and other infrastructure (e.g. electrical wiring or plumbing). Whether you have a soffit or not, you can install crown moulding and conceal light strips inside it. You'll get a similar effect whether there is a soffit or not.
> 
> I'm not sure if you're getting a bit mixed up with regards to backer boxes versus soffits when it comes to recessed lighting. For recessed fixtures, if you are going to the length of sound proofing the room (as you are), you should build backer boxes. Those backer boxes create a shell inside the ceiling that help isolate any sound that escapes around the edge or openings of a recessed light fixture, so they are contained before they have a chance to bounce around inside your ceiling.
> 
> 
> 
> 
> It can. It's a form of flanking noise. What happens is sound waves enter your HVAC grille and travel through your ducts, exiting in another room. It's a much more prevalent problem with rigid metal ductwork versus flex-duct. You may have experienced this at some point in a home where you find in certain areas (e.g. kitchen duct hood) you can hear a lawnmower outside or a dog barking. Bathroom fans are often a similar source of nuisance noise in homes, because they also typically use rigid metal conduit for exhausting air out of the home. One of the reasons why these particular things are prevalent at noise transmission (besides they're conduits made of rigid metal) is they tend to be straight and short (home builders don't like to spend money).
> 
> Ideally, here's what to focus on at a high-level, re: your HVAC:
> 
> 1. Use _insulated_ flexible duct
> 2. Make plenty of bends in the path of the ductwork
> 3. Use longer runs
> 
> These concepts will provide several benefits:
> 
> 1. Slow down the velocity of the air (quieter at the grilles)
> 2. Flanking sound will get absorbed via the bends in the duct as the sound bounces around inside it
> 
> 
> 
> 
> Same thing as the recessed lights. Build a backer box and insert the speaker into it. That's why I placed my recessed wall speakers in columns, which is a common method of getting around the problem. Recessing speakers into the walls also means you need to take their depth + the depth of a backer box into consideration when planning the offset of your inner walls from your outer walls in a room-within-a-room concept. You do not want that backer box touching the outer stud wall or the drywall of an adjacent room.


----------



## bubbrik

newtoavs_2018 said:


> Again...THANK YOU!!! I have a few follow up questions.
> 
> 
> 
> Your guidance about the acoustic vs normal solid core door is extremely helpful. We indeed have a set up as you intuited - the doors will be directly facing the front speakers (about 22 feet apart). Given this, are there any other measures that can be taken to upgrade a normal solid core door? E.g., mounting the acoustic panels you described onto the door? Or will it never stand up to the acoustic door (e.g., they claim those can be up to 55 STC - not sure how that sound rating stands up to the potential rating we could even achieve by the mass/dampening/decoupling strategies in building the room-within-a-room anyway).
> 
> 
> 
> With the backer boxes you describe, is there a particular thread on this forum that describes how to construct those so we can share it with our architect? And do you build those backer boxes into columns/soffits outside the "soundproof box" or do you recess it into the "soundproof box" (hence your feedback about the offset of the inner wall from the outerwall)?
> 
> 
> 
> Lastly, if we need additional consulting, do you know of anyone who would be able to provide some input and even some drawings for how to construct those backer boxes, room within a room, planning for cove lighting, hvac, etc.? We are almost there but not quite...the original consultant we hired wasn't very clear in communicating with us about what's needed and we're feeling a bit unsure and stuck.
> 
> 
> 
> Million thanks!!!




For backer boxes, you can refer to this:
http://www.soundproofingcompany.com/soundproofing-installation-manuals/sim-backer-box/


Sent from my iPhone using Tapatalk


----------



## newtoavs_2018

thanks, bubbrik!!



bubbrik said:


> For backer boxes, you can refer to this:
> http://www.soundproofingcompany.com/soundproofing-installation-manuals/sim-backer-box/
> 
> 
> Sent from my iPhone using Tapatalk


----------



## HT Geek

newtoavs_2018 said:


> Again...THANK YOU!!! I have a few follow up questions.
> 
> Your guidance about the acoustic vs normal solid core door is extremely helpful. We indeed have a set up as you intuited - the doors will be directly facing the front speakers (about 22 feet apart). Given this, are there any other measures that can be taken to upgrade a normal solid core door? E.g., mounting the acoustic panels you described onto the door? Or will it never stand up to the acoustic door (e.g., they claim those can be up to 55 STC - not sure how that sound rating stands up to the potential rating we could even achieve by the mass/dampening/decoupling strategies in building the room-within-a-room anyway).


Yes. You could do what I did, which is to take 2x solid core doors and glue & screw them together to create a massive, 3" thick door. Then add acoustic panels on the inside of the door (minimum 1" thick panels).

Seriously, this is possible for you. The doors will be very heavy (which is good - mass). You lay one down on the floor and apply a couple of tubes of Green Glue judiciously, then screw them together. Then apply acoustic panels to the inside of the doors, so you reduce their reflectivity inside the room. It's a fraction of the cost of acoustic doors, but they are thicker and this will present some additional challenges.

I had to purchase custom-made door hardware (~$200) and extra-wide hinges. For me, the extra work was well worth it. I only paid $55 per door (delivered) from Lowe's, though the doors were a special order and took 3 weeks to arrive (not a bad time-frame, really). In total, it took me a month to acquire the parts and build the doors. When I applied the Green Glue between them, I allowed it to set for 48 hours and I placed weights (i.e. weightlifting weights) on top of the top door to help compress them a bit (don't use a ton of weight.... just enough to hold things together well.... 50-100 lbs. at most... not so much you squeeze out all the GG).

I don't know what my door's STC rating is, but I do know it cost a fraction of a high-STC acoustic door. I spent around $350 total including the hinges (4x extra wide throw... I forget the exact width of them). By the time I add custom made acoustic panels to the inside of it (I'll make those myself), it will cost me under $450 total investment. Granted, I'll have also spent hours of my time on it. Getting the hinges right were the toughest part since there is one part on the door and one part on the door frame, and you only get one chance to get it right!

BTW, I should have clarified earlier that it's not actually the volume per se directed at your doors but rather the energy of the sound waves. Regardless, the point is those doors are going to bear the brunt of it. So, if you want to mitigate what passes through them, density and mass will be important factors in attaining your goal.

If you want to consider my 2x thick solid core door approach, the biggest headache is working out the hinges and framing support of the doors (e.g. extra thick hinges, extra thick door framing, reinforced jack and king studs to bear the weight, etc.). If you're not comfortable figuring out those details, hire a good carpenter. 

If you want to go with an acoustic door, make sure you note its weight as you'll probably need to reinforce your door frame anyway.




> With the backer boxes you describe, is there a particular thread on this forum that describes how to construct those so we can share it with our architect? And do you build those backer boxes into columns/soffits outside the "soundproof box" or do you recess it into the "soundproof box" (hence your feedback about the offset of the inner wall from the outerwall)?


The link @Bubbrik ;posted is one of the best resources. I'll add that you can vary the thickness of the materials a bit. For instance, 1/4" cement board is fine. You can use 3/8" if you can find it. 1/2" is quite heavy. You can use whatever. Also, the OSB.... 1/2" is a good general guide, but 1/16" either way won't matter. And plywood is OK too. The point is to create a dense shell composed of different materials with a fire and heat-resistant interior (cement board). Measuring well is critical. You should have at least 1/2" distance between all parts of the light fixture, to allow a bit of airflow. And check your fixture. Some require more space around them, though 1/2" to non-combustible materials is the norm.



> Lastly, if we need additional consulting, do you know of anyone who would be able to provide some input and even some drawings for how to construct those backer boxes, room within a room, planning for cove lighting, hvac, etc.? We are almost there but not quite...the original consultant we hired wasn't very clear in communicating with us about what's needed and we're feeling a bit unsure and stuck.


You can find references to some very good consultants here on AVS, but the vast majority are full-service. 

Are you hiring a general contractor? We can get in the weeds pretty quickly here, but I'll toss out some thoughts in case you are hiring a GC.

1. Electrical prep and HVAC prep are really important. I would run a minimum of one dedicated 20 amp circuit just to your room. For reference, I went a bit over-the-top. I have 3x 20-amp circuits in my room. One for room lighting, a small beverage fridge, and general use. One for the PJ, receiver, HTPC, and some Smart Home devices on a UPS. My 3rd circuit only powers the amps. If I were to do it over, I'd probably do two circuits. I like having the room lighting on a different circuit from the equipment. If my amps trip a breaker, I can still see. But that is just me. It's likely overkill. But if you are running one 20-amp 120vac line, adding a 2nd at the same time results in a minimal cost increase. Adding one later on is prohibitively expensive when you consider the damage to your HT room shell that will need to be rectified.

2. The cove lighting you can rough-in the electrical and figure out the details later. Your moulding will hide imperfections provided you have the electrical box mounted at an appropriate height. Again, pre-planning the electrical is so important. Doing it later will be 10x the cost. 

3. HVAC planning is another biggie as mentioned. The gist of it is: supplies in the front, returns in the rear. Pull air from front to rear, across your seats. And don't forget about cooling your equipment and the heat it will generate. Make sure you have both supplies and a return in your room. There are various details around air velocity and air flow (CFM) that I won't get into here as it's a complex topic in-and-of-itself, but they are important to ensure guests are comfortable.

4. Your rack. Where will your equipment rack be located? How will it be fed power? How will it be cooled? If you dump HVAC in there, can you shut it off if the heat is on?

There are so many variables, but spending more time on the planning stage will pay off.

BTW, if you have not already done so, consider mapping out where you think you'll want seats, a riser, etc. Viewing distance vs. screen size. What will be the FOV (Field-Of-View) for your seating rows? Will the rear row be able to see over the heads of the front row? There are so many things to think about before you start construction, I know it can get overwhelming at times.


----------



## newtoavs_2018

Oh my goodness, I can't thank you enough for this wealth of information! One big question about process. For context, this is a new construction home and we are in final stages of designing the home and getting permits and putting the package together to go out for GC bids. Is this depth and degree of planning for the home theater (i.e., all of the implications for HVAC, electrical circuitry, reinforcement of door frame for a heavy door, backer box design, rack placement and cooling) something that the architect should be involved in at this stage? Or is it for the GC to add on later in the build? Your answer to this question will impact whether we try to hire a consultant at this stage or not. Ultimately, as you noted, although I've done my best to learn as much as possible through this site, it's quite overwhelming! I'm thinking we need some more informed help  I know our architects, while they have expertise on wall and floor and ceiling construction from a sound management standpoint, aren't experts in designing home theaters and all of the implications for HVAC, electrical, etc., that is involved. Thank you again, so much, for sharing your wisdom and knowledge! How did you come by all of it, btw?? 




HT Geek said:


> Yes. You could do what I did, which is to take 2x solid core doors and glue & screw them together to create a massive, 3" thick door. Then add acoustic panels on the inside of the door (minimum 1" thick panels).
> 
> Seriously, this is possible for you. The doors will be very heavy (which is good - mass). You lay one down on the floor and apply a couple of tubes of Green Glue judiciously, then screw them together. Then apply acoustic panels to the inside of the doors, so you reduce their reflectivity inside the room. It's a fraction of the cost of acoustic doors, but they are thicker and this will present some additional challenges.
> 
> I had to purchase custom-made door hardware (~$200) and extra-wide hinges. For me, the extra work was well worth it. I only paid $55 per door (delivered) from Lowe's, though the doors were a special order and took 3 weeks to arrive (not a bad time-frame, really). In total, it took me a month to acquire the parts and build the doors. When I applied the Green Glue between them, I allowed it to set for 48 hours and I placed weights (i.e. weightlifting weights) on top of the top door to help compress them a bit (don't use a ton of weight.... just enough to hold things together well.... 50-100 lbs. at most... not so much you squeeze out all the GG).
> 
> I don't know what my door's STC rating is, but I do know it cost a fraction of a high-STC acoustic door. I spent around $350 total including the hinges (4x extra wide throw... I forget the exact width of them). By the time I add custom made acoustic panels to the inside of it (I'll make those myself), it will cost me under $450 total investment. Granted, I'll have also spent hours of my time on it. Getting the hinges right were the toughest part since there is one part on the door and one part on the door frame, and you only get one chance to get it right!
> 
> BTW, I should have clarified earlier that it's not actually the volume per se directed at your doors but rather the energy of the sound waves. Regardless, the point is those doors are going to bear the brunt of it. So, if you want to mitigate what passes through them, density and mass will be important factors in attaining your goal.
> 
> If you want to consider my 2x thick solid core door approach, the biggest headache is working out the hinges and framing support of the doors (e.g. extra thick hinges, extra thick door framing, reinforced jack and king studs to bear the weight, etc.). If you're not comfortable figuring out those details, hire a good carpenter.
> 
> If you want to go with an acoustic door, make sure you note its weight as you'll probably need to reinforce your door frame anyway.
> 
> 
> 
> 
> The link @Bubbrik ;posted is one of the best resources. I'll add that you can vary the thickness of the materials a bit. For instance, 1/4" cement board is fine. You can use 3/8" if you can find it. 1/2" is quite heavy. You can use whatever. Also, the OSB.... 1/2" is a good general guide, but 1/16" either way won't matter. And plywood is OK too. The point is to create a dense shell composed of different materials with a fire and heat-resistant interior (cement board). Measuring well is critical. You should have at least 1/2" distance between all parts of the light fixture, to allow a bit of airflow. And check your fixture. Some require more space around them, though 1/2" to non-combustible materials is the norm.
> 
> 
> 
> You can find references to some very good consultants here on AVS, but the vast majority are full-service.
> 
> Are you hiring a general contractor? We can get in the weeds pretty quickly here, but I'll toss out some thoughts in case you are hiring a GC.
> 
> 1. Electrical prep and HVAC prep are really important. I would run a minimum of one dedicated 20 amp circuit just to your room. For reference, I went a bit over-the-top. I have 3x 20-amp circuits in my room. One for room lighting, a small beverage fridge, and general use. One for the PJ, receiver, HTPC, and some Smart Home devices on a UPS. My 3rd circuit only powers the amps. If I were to do it over, I'd probably do two circuits. I like having the room lighting on a different circuit from the equipment. If my amps trip a breaker, I can still see. But that is just me. It's likely overkill. But if you are running one 20-amp 120vac line, adding a 2nd at the same time results in a minimal cost increase. Adding one later on is prohibitively expensive when you consider the damage to your HT room shell that will need to be rectified.
> 
> 2. The cove lighting you can rough-in the electrical and figure out the details later. Your moulding will hide imperfections provided you have the electrical box mounted at an appropriate height. Again, pre-planning the electrical is so important. Doing it later will be 10x the cost.
> 
> 3. HVAC planning is another biggie as mentioned. The gist of it is: supplies in the front, returns in the rear. Pull air from front to rear, across your seats. And don't forget about cooling your equipment and the heat it will generate. Make sure you have both supplies and a return in your room. There are various details around air velocity and air flow (CFM) that I won't get into here as it's a complex topic in-and-of-itself, but they are important to ensure guests are comfortable.
> 
> 4. Your rack. Where will your equipment rack be located? How will it be fed power? How will it be cooled? If you dump HVAC in there, can you shut it off if the heat is on?
> 
> There are so many variables, but spending more time on the planning stage will pay off.
> 
> BTW, if you have not already done so, consider mapping out where you think you'll want seats, a riser, etc. Viewing distance vs. screen size. What will be the FOV (Field-Of-View) for your seating rows? Will the rear row be able to see over the heads of the front row? There are so many things to think about before you start construction, I know it can get overwhelming at times.


----------



## Ladeback

newtoavs_2018 said:


> Oh my goodness, I can't thank you enough for this wealth of information! One big question about process. For context, this is a new construction home and we are in final stages of designing the home and getting permits and putting the package together to go out for GC bids. Is this depth and degree of planning for the home theater (i.e., all of the implications for HVAC, electrical circuitry, reinforcement of door frame for a heavy door, backer box design, rack placement and cooling) something that the architect should be involved in at this stage? Or is it for the GC to add on later in the build? Your answer to this question will impact whether we try to hire a consultant at this stage or not. Ultimately, as you noted, although I've done my best to learn as much as possible through this site, it's quite overwhelming! I'm thinking we need some more informed help  I know our architects, while they have expertise on wall and floor and ceiling construction from a sound management standpoint, aren't experts in designing home theaters and all of the implications for HVAC, electrical, etc., that is involved. Thank you again, so much, for sharing your wisdom and knowledge! How did you come by all of it, btw??


I know HTGeek wil get back to you soon, but I thought I would add some things and ask some questions.

Where are you wanting to build your theater? In the basement, main lever, upper level or a stand alone room or building? I would at least talk to your architect that you are wanting to build a home theater so they know to have it in the plans. If you went with say one of the people on the form that design home theaters they could work with your architect on the build to get what you want in the room. If you are going to DIY the room after the house is built. I would have them do as much of what Geek has put in here. You could have them frame the basic room then you could come in after them and build a room inside a room to decouple it from the house. I am building my theater in my basement and I believe Geek is building his on a second level in his house. If you go the basement route if you can, I would see about at least 10' or taller ceilings for the theater area if you can. There are some really cool builds on here where people have built their theater under a suspended garage. 

Here is one to check out.

http://www.avsforum.com/forum/19-dedicated-theater-design-construction/1607217-theater-design-build-under-suspended-slab-garage.html


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## healthnut

I just received a noticed that PAC international will introduce a spring loaded isolation clip for soundproofing purposes. This could have real potential to increase isolation between spaces. I’ve heard that the founder of Auro 3D completely soundproofed his studio using large industrial springs, while I’m sure the new offering won’t eliminate sound transmission, hopefully it will be an advance in the state of the art...


Sent from my iPhone using Tapatalk


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## newtoavs_2018

Thank you!! And yes, in a basement with 10' ceilings 





Ladeback said:


> I know HTGeek wil get back to you soon, but I thought I would add some things and ask some questions.
> 
> Where are you wanting to build your theater? In the basement, main lever, upper level or a stand alone room or building? I would at least talk to your architect that you are wanting to build a home theater so they know to have it in the plans. If you went with say one of the people on the form that design home theaters they could work with your architect on the build to get what you want in the room. If you are going to DIY the room after the house is built. I would have them do as much of what Geek has put in here. You could have them frame the basic room then you could come in after them and build a room inside a room to decouple it from the house. I am building my theater in my basement and I believe Geek is building his on a second level in his house. If you go the basement route if you can, I would see about at least 10' or taller ceilings for the theater area if you can. There are some really cool builds on here where people have built their theater under a suspended garage.
> 
> Here is one to check out.
> 
> http://www.avsforum.com/forum/19-dedicated-theater-design-construction/1607217-theater-design-build-under-suspended-slab-garage.html


----------



## HT Geek

newtoavs_2018 said:


> Oh my goodness, I can't thank you enough for this wealth of information! One big question about process. For context, this is a new construction home and we are in final stages of designing the home and getting permits and putting the package together to go out for GC bids. Is this depth and degree of planning for the home theater (i.e., all of the implications for HVAC, electrical circuitry, reinforcement of door frame for a heavy door, backer box design, rack placement and cooling) something that the architect should be involved in at this stage?


Depending on your goals, you can normally go either way. However, in your case I would suggest working with an architect. They don't normally spec the level-of-detail down to things like where air vents will be located or where/how your HVAC ducts will be run, but just for your HT room it's worth investigating how much level of detail they feel comfortable helping you plan it out. You might not need the architect's help with all of that, but advise them you wish to accomplish building a dedicated HT room using construction methods designed to isolate the room acoustics from the remainder of the home. To most architects, this would be a welcome (and fun) task.

Now that said, if they don't have any clue about building acoustics then scratch that. In that case consider working on the details with the GC and possibly look for an independent sub-contractor with experience in clips & channel. Or pressure your GC to find one. That way you'll be working with a sub-contractor who has some idea of what you are trying to accomplish and they will be familiar with the challenges that come with working around obstacles in a room when installing clips & channel or a double-framed room. Speaking of obstacles.... Make sure both the architect and GC understand you do not want any of the home's infrastructure passing through that room; i.e., plumbing lines of any kind, primary electrical conduits, bathroom vent pipes, etc. Nothing that doesn't need to be there. Obviously, if you wanted a sink in there you'd have to plumb it, but you don't want to (for example) hear water running through a pipe from and adjacent bathroom after someone unplugs the bathtub or flushes a toilet. Likewise, you don't want your HVAC system in the wall with a neighboring room. Those just become nuisances you then have to mitigate from an acoustic standpoint, costing you time and money.

If you have your architect draw up some of the details on the plans, make sure they have a chat with the GC about your HT room in particular. You don't want to drive over to the job site one day and find out they screwed it up due to a lack of communication with the framers or the plumber, etc. The framing crew will be one of the few subs who actually looks closely at the architect's drawings, but most of the subs will need clear guidance or they will just run your utilities, etc. like every other house they've worked on.

It's a lot of work and detail, but I envy your position in that you have a blank slate! It's an excellent opportunity for you and the architect to think about what dimensions you want for the room and specify details such as how the floor will be built. That's one of those things you can't normally do-over. If you haven't seen/read it, take a couple of hours to skim over Mario's Cinemar build thread. That is hands-down one of the best HT construction threads on AVS, and his theater is amazing. Regarding the floor, jump to post 81 in Mario's thread. Notice he's got about an 18" drop in the concrete itself. His theater is in the basement, and he had the home built like that on purpose IIRC. You could do what he did and install this insane D-Box setup.

Here's a photo of Mario's floor after the D-Box support system was installed:











Notice the steps on the sides of it and the fact the floor at the bottom level has been raised around the D-Box framing. He thought through making sure the lower floor would be correctly leveled with the D-Box system under the lower level seats.

Here's a post showing his backer boxes assembled (but not installed). Scroll down from that one and you'll find photos that show his soffit framing and clips & channel on the ceiling. There are also photos on the page of his huge vent muffler for his HVAC being installed. I think you'll find Mario's Cinemar thread to be very useful in your discussions with your architect and eventually your GC.

There are many useful photos in his build, such as these that discuss and demonstrate some of the subtle but important nuances of construction.



> I know our architects, while they have expertise on wall and floor and ceiling construction from a sound management standpoint, aren't experts in designing home theaters and all of the implications for HVAC, electrical, etc., that is involved. Thank you again, so much, for sharing your wisdom and knowledge! How did you come by all of it, btw??


You're most welcome. 

I hope those tips above are useful.

It helped that I already had a basic understanding of residential construction, but I've acquired much of my knowledge from a combination of studies. A combination of personal experience (building my HT room solo), learning (mostly via this forum), and interpolation of the first two. I spent about two years planning my build, including reading most of the DIY build threads on AVS. And in a past "career life" I spent a few years working for a construction materials supplier. I occasionally dealt with architectural drawings and engineering plans of various sorts.


----------



## newtoavs_2018

As always, THANK YOU for your insights!! A final few questions about our general approach and backer boxes.

We are following the "room within a room" build approach. Our architect says that if we can at this point just plan to build the "room" then later we can design the "room within." In other words, the architect is mapping out the mass, dampening, decoupling for that room shell to contain sound; we would plan to NOT cut into the shell with exception of the doors into the space. Therefore, planning for soffiting to house HVAC and recessed lights. 

Question A: How does this general plan sound?

Question B: Do the backer boxes get installed into the "room" or the "room within?" In other words, do you cut into the mega soundproofed shell to accommodate those backer boxes or do you cut into the room within? Are those backer boxes implicated for recessed speakers (including the ones behind the screen and also to the sides and back of the room) or recessed lights or both?

Thank you again!!





HT Geek said:


> Depending on your goals, you can normally go either way. However, in your case I would suggest working with an architect. They don't normally spec the level-of-detail down to things like where air vents will be located or where/how your HVAC ducts will be run, but just for your HT room it's worth investigating how much level of detail they feel comfortable helping you plan it out. You might not need the architect's help with all of that, but advise them you wish to accomplish building a dedicated HT room using construction methods designed to isolate the room acoustics from the remainder of the home. To most architects, this would be a welcome (and fun) task.
> 
> Now that said, if they don't have any clue about building acoustics then scratch that. In that case consider working on the details with the GC and possibly look for an independent sub-contractor with experience in clips & channel. Or pressure your GC to find one. That way you'll be working with a sub-contractor who has some idea of what you are trying to accomplish and they will be familiar with the challenges that come with working around obstacles in a room when installing clips & channel or a double-framed room. Speaking of obstacles.... Make sure both the architect and GC understand you do not want any of the home's infrastructure passing through that room; i.e., plumbing lines of any kind, primary electrical conduits, bathroom vent pipes, etc. Nothing that doesn't need to be there. Obviously, if you wanted a sink in there you'd have to plumb it, but you don't want to (for example) hear water running through a pipe from and adjacent bathroom after someone unplugs the bathtub or flushes a toilet. Likewise, you don't want your HVAC system in the wall with a neighboring room. Those just become nuisances you then have to mitigate from an acoustic standpoint, costing you time and money.
> 
> If you have your architect draw up some of the details on the plans, make sure they have a chat with the GC about your HT room in particular. You don't want to drive over to the job site one day and find out they screwed it up due to a lack of communication with the framers or the plumber, etc. The framing crew will be one of the few subs who actually looks closely at the architect's drawings, but most of the subs will need clear guidance or they will just run your utilities, etc. like every other house they've worked on.
> 
> It's a lot of work and detail, but I envy your position in that you have a blank slate! It's an excellent opportunity for you and the architect to think about what dimensions you want for the room and specify details such as how the floor will be built. That's one of those things you can't normally do-over. If you haven't seen/read it, take a couple of hours to skim over Mario's Cinemar build thread. That is hands-down one of the best HT construction threads on AVS, and his theater is amazing. Regarding the floor, jump to post 81 in Mario's thread. Notice he's got about an 18" drop in the concrete itself. His theater is in the basement, and he had the home built like that on purpose IIRC. You could do what he did and install this insane D-Box setup.
> 
> Here's a photo of Mario's floor after the D-Box support system was installed:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Notice the steps on the sides of it and the fact the floor at the bottom level has been raised around the D-Box framing. He thought through making sure the lower floor would be correctly leveled with the D-Box system under the lower level seats.
> 
> Here's a post showing his backer boxes assembled (but not installed). Scroll down from that one and you'll find photos that show his soffit framing and clips & channel on the ceiling. There are also photos on the page of his huge vent muffler for his HVAC being installed. I think you'll find Mario's Cinemar thread to be very useful in your discussions with your architect and eventually your GC.
> 
> There are many useful photos in his build, such as these that discuss and demonstrate some of the subtle but important nuances of construction.
> 
> 
> 
> You're most welcome.
> 
> I hope those tips above are useful.
> 
> It helped that I already had a basic understanding of residential construction, but I've acquired much of my knowledge from a combination of studies. A combination of personal experience (building my HT room solo), learning (mostly via this forum), and interpolation of the first two. I spent about two years planning my build, including reading most of the DIY build threads on AVS. And in a past "career life" I spent a few years working for a construction materials supplier. I occasionally dealt with architectural drawings and engineering plans of various sorts.


----------



## newtoavs_2018

p.s. I know in a previous post you shared some super valuable information about backer boxes - I just want to make sure I understand fully and am comprehending the notion of "outer wall" vs "inner wall" correctly. 




newtoavs_2018 said:


> As always, THANK YOU for your insights!! A final few questions about our general approach and backer boxes.
> 
> We are following the "room within a room" build approach. Our architect says that if we can at this point just plan to build the "room" then later we can design the "room within." In other words, the architect is mapping out the mass, dampening, decoupling for that room shell to contain sound; we would plan to NOT cut into the shell with exception of the doors into the space. Therefore, planning for soffiting to house HVAC and recessed lights.
> 
> Question A: How does this general plan sound?
> 
> Question B: Do the backer boxes get installed into the "room" or the "room within?" In other words, do you cut into the mega soundproofed shell to accommodate those backer boxes or do you cut into the room within? Are those backer boxes implicated for recessed speakers (including the ones behind the screen and also to the sides and back of the room) or recessed lights or both?
> 
> Thank you again!!


----------



## HT Geek

newtoavs_2018 said:


> p.s. I know in a previous post you shared some super valuable information about backer boxes - I just want to make sure I understand fully and am comprehending the notion of "outer wall" vs "inner wall" correctly.


No worries. That's a good subject to clarify.

The "outer wall" is the original, structural wall of the room. The "inner wall" is the interior wall that's the business side of the HT room. Both "walls" refer to the framing. So, if you are thinking of the wall frames, assuming you are using 2x4 studs, you'd have two walls that are both composed of 2x4's, making them each 3-1/2" thick.

Your "outer" wall will only have drywall applied on the side away from the HT room; namely, whatever other room is adjacent. If it were an exterior wall, you'd have just the exterior side surfaced. Do not install any facing on the "inside" or HT-room side of this outer framing. You don't want to do that because you'll end up creating a situation that basically causes certain frequency sounds to become amplified outside your HT room. 

Likewise, on your "inner" wall, you want your walls surface material (usually drywall) to only be applied on the inside or HT-room side of that interior wall framing. 

Leave a small air gap (1" minimum is recommended) between both wall frames. This decouples the two walls.

Some things to keep in mind when designing and constructing a double-framed wall:


Do apply loose fill insulation between the studs in both walls (e.g. pink fiberglass or Roxul)
If not in basement, de-couple the floor of the inner wall (also optional in basement installs, but often not practical)
De-couple the ceiling attached to the inner wall
Don't forget the air gap between walls
No surface covering (e.g. drywall) between the inner/outer walls
Use 24" O.C. (On Center) spacing between vertical studs
Metal studs are _slightly _better at sound attenuation than wood studs
Biggest advantage of metal studs is they are always straight; biggest disadvantage is cost




newtoavs_2018 said:


> We are following the "room within a room" build approach. Our architect says that if we can at this point just plan to build the "room" then later we can design the "room within." In other words, the architect is mapping out the mass, dampening, decoupling for that room shell to contain sound; we would plan to NOT cut into the shell with exception of the doors into the space. Therefore, planning for soffiting to house HVAC and recessed lights.
> 
> Question A: How does this general plan sound?


I'm not sure. The devil is in the details, per se. If he/she means they want to concentrate on the outer room / shell only and make the room a bit larger to accommodate an inner room, and that you should have a general contractor or HT consultant design the inner room with you, I'd say yes that will work provided the architect understands some key points.

Let me clarify a few important points in deference to helping prevent unwanted surprises when you get to the stage of building the inner room. 

The design features of the HT room will (generally speaking) need to be part of the "inner" room but not the "outer" room. IOW, the outer room is just a shell. It should be built like a box. You'll need your architect to note points where the HVAC and electrical systems enter the outer room. That's because you will need to tap into those areas for the inner room. If you get to the point of building the inner room and those utilities are not in a convenient location for the inner room design, re-routing them will mean making some sacrifices on some of your inner room dimensions.

The inner room will be free-standing, but you're contractor will use isolation clips to permanently secure and connect the inner walls to the outer walls. This is for the purpose of structural integrity of the inner room. The clips have vibration absorbing materials to help reduce sound transmissions between both sets of framing. You also don't need very many of them, but you need some.

To illustrate, let's say as an example your outer room was 24' long by 16' wide by x 10' tall. And in your outer room the HVAC system is roughed in with a single supply duct entering the room at the rear in the middle of the room, and your return vent is roughed in at the very front of the room in the middle. Well, now you have a problem to deal with:

The supply vent enters the room in the wrong spot, and the return vent enters the room in the wrong spot.
To solve these problems, you'll need to find a way to swap which end of the room these vents are entering the room.
If your room is in the basement, you can't tackle the issue from above, which means you will be forced to take some dimensional space from the room in order to rectify the situation.

In this example, if you intended to have soffits from the get-go, it's not a big deal because you can just route your HVAC into your to-be-built soffits in the room. However, this fact is going to influence how wide and tall your soffits will need to be.


Back to your planning.... If you want soffits, that's great because they are very useful in concealing utilities (especially electrical and HVAC) and they're great for routing other stuff such as speaker cables, network cables, etc. BUT here's the catch: your soffit needs to dimensionally meld with your room. There's no steadfast formula, but I'd say a good rule-of-thumb is a 1:8 ratio. Some people do like taller or wider soffits. It's really up to you. 

Here's what I mean by that 1:8 ratio:

Soffit Height : Room Height w/out Soffit
Soffit Width : Room Width

Examples would be a 1' tall soffit in a 8' tall room (8 feet bottom of soffit to floor); 2' wide soffit in a 16' wide room (wall to wall beneath the soffit). Just remember this is a very subjective value! I'm just providing a very rough guideline and example. Opinions will vary widely! Try to examine soffit size ratios in rooms you like before you commit to your own ratios in your HT room.

[BTW, if you do want a soffit, consider doing a starfield ceiling with fiber optic lighting. You'd have it installed in the middle of the room, where the ceiling is higher (i.e. not in/under the soffit).]

Anyway, my point on the soffit is make sure everything will fit. The HVAC duct is the biggest concern due to its diameter. This can be mitigated by using more than one supply or return duct entry into the room. Make sure the HVAC ducts will enter the room along its perimeter in the ceiling and not in the middle of the room or you could find yourself having to lower the entire room height in order to hide it. 

Generally speaking, I would suggest you plan for a a bit more height than you think you'll need. It will allow you some wiggle room to deal with any unforeseen issues. You can always make the inner room shorter in height than the space you have to work with if you prefer a shorter ceiling effect. For instance, if you think you'll want a 9' tall ceiling, have the home built with a 10' or 11' ceiling in the "outer" room portion.

Plan at least an extra foot (12") along all dimensions between your inner and outer rooms. Presume you will lose a minimum of 12" height, width, and length between the size of your outer versus inner rooms. If your outer room is 24' x 16' x 9', your inner room will end up being around 23' x 15' x 8'. That's not including soffits, so again be sure to especially be cognizant of final room height.

How will your floor be decoupled? You need to be sure the final floor height of the inner room is going to be a seamless transition between the outer shell and remainder of the house versus the inner room. If this will be built in a basement, don't worry about this issue as the concrete floor under your carpet will be fine. Another option - regardless of which floor your room is on - is to do what I alluded to in Mario's build, which is to enter the room at the higher elevation (riser level) and have a step-down built into the room's infrastructure where your lower seating level will be built. This is presuming you have/use a riser.

Last but not least, keep in mind the thickness of your ceiling joists in your inner room. I would recommend getting the architect to help you with those calculations. I have a spreadsheet that I created which I can share if you want to DIY the calculations, but you need to know the room dimensions, which way the joists will be run (normally width-wise), and the weight of stuff that will hang from the ceiling (e.g. 2x drywall layers). The span is the most important factor. Longer spans require taller joists to prevent sagging. For example, the limit of a 2x6 wood joist is ~12 feet, give or take based on load bearing requirements and how close together the joists are spaced. 

I'm mentioning this because that's a significant factor in the height of your inner room. The inner room's joists have to fit in the outer room's space. And you need an air gap between the top of the inner room joists and the bottom of the outer room joists. Let's say you use 2x8's. That would be 7-1/2" tall + 1" air gap = 8-1/2" of space lost. Then add 2x layers of 5/8" thick drywall on the inside of the inside room ceiling and you have lost 9-3/4" of ceiling height from your outer room (rough-in dimensions) to the inner room's finished ceiling-to-floor height dimension. If you used 2x10's it would be a loss of 11-1/2" (9-1/4 + 1 + 1/14). Now you begin to see why I recommend going taller with your outer room than an architect might think of doing without this sort of advice.

One more very important note about soffits: A best practice is to build the soffit on the _interior_ of the sound-proof shell. This is a finer point that many people don't realize until it's too late. When you build your inner room, it's going to be built as a box inside your outer room box. The soffit should be built inside the inner room. IOW, do not build the soffit as a part of the inner room framing. Build it inside the inner room, after the drywall is up. Most contractors will not do or understand this unless you clearly explain it ahead of time as they're not used to that method. The reason you want to do this is to prevent issues where a flanking path gets accidentally created to/from your inner room, through the soffit, through an opening or gap somewhere in the soffit, and into the outer room space. If that happens, you'll likely never be able to find and fix it without tearing out a lot of hard work. By constructing the soffit inside the inner room after it's drywalled, you create another barrier to sound transmission between the spaces.




> Question B: Do the backer boxes get installed into the "room" or the "room within?" In other words, do you cut into the mega soundproofed shell to accommodate those backer boxes or do you cut into the room within? Are those backer boxes implicated for recessed speakers (including the ones behind the screen and also to the sides and back of the room) or recessed lights or both?


Great question. You cut a hole in the "sound proof shell", which is the inner room. This is the reason for the backer box. What you're accomplishing is preserving as much of the shell as possible, but you are extending it in 3 dimensions up and into the outer room's space. You'll have to make a hole in the backer box to allow wiring in/out, and then you'd caulk the hole afterwards to seal it. BTW, this can make lighting placement a challenge because you don't want a backer box positioned where it would conflict with a ceiling joist above it.

There is a bit of a work-around to this issue. If you have a soffit, install the backer boxes inside the soffit. You eliminate the possibility of lighting position conflicting with the location of your outer room's joists. You also are still inside the sound-proofed shell, thought it's still a good idea to use the backer box anyway.

And yes, use backer boxes for recessed lighting and recessed speakers. Also, if they are on the wall or ceiling it doesn't matter. The same principles apply.

One more thing... for electrical supply to the room.... I would recommend you plan on two 20-amp circuits being routed to the room. One for room lighting and outlets, and a dedicated circuit for your equipment rack. This raises another important point. Where will your equipment rack be located? Inside or outside the room? Wherever it is going to be, you want a conduit running to it for a 20-amp service. Have the electrician use a conduit so you can upgrade it in the future if you ever want to. Much less work to do that now. Will cost you an extra $100 or so. Also setup a conduit between your HT equipment spot and your home's central distribution node location for your Internet and media closet. You never know if/when that will come in handy.

The room lighting supply should enter the room somewhere where it can be accessed easily once the inner room construction begins. I'd have it placed far into the outer room and terminated with a single outlet. That will give your contractor plenty of slack in the wire to relocate it and bring it into the inner room as needed when the time comes.

I know there's so many little details!


----------



## gooch02000

Any tips on muffling the sound of a window box air conditioner?


----------



## HT Geek

gooch02000 said:


> Any tips on muffling the sound of a window box air conditioner?


If you're concerned with the unit's normal noise, there's not much you can do about it. If you have a specific issue such as vibration of the window or window frame, you can attempt to address those issues directly. There are some good basic tips here.

Most of the noise is caused by one of two things: poor seals around the perimeter (sound leakage from outside in), and the construction of the unit.

If you can afford it, a mini-split system will give you better performance and much less noise (and you get your window back, FWIW).

Relocating it would be the zero-cost option.


----------



## gooch02000

HT Geek said:


> If you can afford it, a mini-split system will give you better performance and much less noise (and you get your window back, FWIW).
> 
> Relocating it would be the zero-cost option.


I was afraid someone would say that.

A minisplit is on the list, but I can't afford it at the moment. The box cools the room quite well, but is way, way too loud even on low fan mode. The room itself is halfway below grade, a walkout basement, so it stays much cooler than the first floor; but I live in central Arkansas where it gets quite hot during the summer months (and beyond).


----------



## policy

I'm meeting with my structural engineer a week from Monday to discuss my room within a room plans. My LARGEST concern is about bass escaping up through the ceiling. 

I'm planning on attaching two sheets of drywall cut to width between the joists under the subfloor (of the ceiling), and then I plan on going OSB, 5/8"x2 on the ceiling. Does it make sense to use soundclips on the ceiling as well?


----------



## Ladeback

policy said:


> I'm meeting with my structural engineer a week from Monday to discuss my room within a room plans. My LARGEST concern is about bass escaping up through the ceiling.
> 
> I'm planning on attaching two sheets of drywall cut to width between the joists under the subfloor (of the ceiling), and then I plan on going OSB, 5/8"x2 on the ceiling. Does it make sense to use soundclips on the ceiling as well?


Yes, go with clips and channel on the ceiling. Are you doing two layers of OSB or one and one layer of drywall. Bass is the hardest thing to stop. You probably won't stop it all, depending on how many subs and watts you have to them.

Check this out on Soundproofing Company's website.

http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/


----------



## policy

Ladeback said:


> Yes, go with clips and channel on the ceiling. Are you doing two layers of OSB or one and one layer of drywall. Bass is the hardest thing to stop. You probably won't stop it all, depending on how many subs and watts you have to them.
> 
> Check this out on Soundproofing Company's website.
> 
> http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/


I'm going with 1 layer of OSB and 2 layers of drywall, the OSB is so that I can just wall mount the side and rear speakers. 

Movie theaters can stop bass. Cost no object, what can I do? I can put cement walls in there if that's better. I have a blank slate, its just small (Room is 12x10x8 at BEST). I'm open to ideas


----------



## Ladeback

policy said:


> I'm going with 1 layer of OSB and 2 layers of drywall, the OSB is so that I can just wall mount the side and rear speakers.
> 
> Movie theaters can stop bass. Cost no object, what can I do? I can put cement walls in there if that's better. I have a blank slate, its just small (Room is 12x10x8 at BEST). I'm open to ideas


Three layers? I would make sure your ceiling can handle the weight and the clips and channel will as well. Give the Soundproofing a call or send them an email of what you want to do. They are very helpful and can point you in the right direction.

As for commercial theaters stopping all bass, I have been to movies where I can still hear bass coming through into the theater I am in. Now not at a load level, but I can still hear it. How many and what kind of subs are you using.


----------



## HT Geek

policy said:


> Cost no object, what can I do? I can put cement walls in there if that's better. I have a blank slate, its just small (Room is 12x10x8 at BEST). I'm open to ideas


All of the above.

3" Tongue & Groove Subfloor | 1" Oak Hardwood Floor | 1" RIM | 2x 1/2" OSB | 1-1/2" Gypcrete | 3/4" Sleepers | 3/4" Red Oak Flooring
STC 50 100hz -25db | 125hz -32db
* RIM = Kinetics Roll-out Isolation Material and would be placed on the floor above.

Concrete Slab 14" 'T' w/2" Top (16" total height)
STC 54 100hz -39db | 125hz -39db

Concrete Slab 6"
STC 53 50hz -41db | 63hz -41db | 80hz -41db | 100hz -40db | 125hz -42db

Concrete Slab 6" | KSCH Ceiling Hanger | Cold Rolled Channel | Furring Channel | 2x 5/8" Drywall
STC 59 50hz -35db | 63hz -35db | 80hz -36db | 100hz -36db | 125hz -39db

Concrete Slab 6" | ICC Isolation Hanger | Cold Rolled Channel | Furring Channel | 3-1/2" Insulation | 2x 5/8" Drywall
STC 84 80hz -57db | 100hz -61db | 125hz -63db

*"The Bomb"*
4" Concrete Slab | 1/2" Plywood | 2" RIM | 6" Concrete Slab | ICC Isolation Hanger | Cold Rolled Channel | Furring Channel | 3-1/2" Fiberglass | 2x 5/8" Drywall
STC *94* 80hz -63db | 100hz -65db | 125hz -70db

The RIM goes under the sub-floor of the floor above the HT room. Use >1 layer of 1/2" plywood on top of the RIM for better results. These figures above are from lab tests. In the real world, I would use minimum 3/4" plywood on top of the RIM for support and to keep the floor level. 2x interleaved 1/2" plywood would be better. 2x 3/4" better still. Don't worry about the weight on top of the RIM. It is designed to support steel and concrete structures on top of it.

For airborne sound, concrete beats wood hands-down, but you need concrete + isolators for best results. Add fiberglass, wood joists, etc. and will be even better. Don't use T-beams. You may substitute clips & channel for the Kinetics Isolators I mention above. I just used those for demonstration purposes since I have lab test results with above configs tested as a ceiling.


----------



## doveman

HT Geek said:


> It all depends on your particular scenario. The most common is the IB-3 clip, because there's typically a slight offset both horizontally and vertically.


Sorry but I don't understand how IB-3 can be used to secure a top plate to the ceiling. It's a right-angle clip, as shown here http://www.soundproofingcompany.com/product/ib-3-bracket/ so if the bit with the rubber washer is screwed to the top plate, the longer section could be screwed to an adjacent wall but not the ceiling as far as I can see.

Just to remind you, I'm planning to use Genie Clips and channel on the ceiling to suspend two-layers of acoustic plasterboard. Genie Clip+Channel+15mm+12.5mm plasterboard will come to about 74mm. There's only one wall (which has two doors) where I'll probably need to build a stud wall in front of it and whatever I use needs to fit within that 74mm space, so I couldn't use IB-3 anyway as they're about 114mm high.


----------



## Ladeback

doveman said:


> Sorry but I don't understand how IB-3 can be used to secure a top plate to the ceiling. It's a right-angle clip, as shown here http://www.soundproofingcompany.com/product/ib-3-bracket/ so if the bit with the rubber washer is screwed to the top plate, the longer section could be screwed to an adjacent wall but not the ceiling as far as I can see.
> 
> Just to remind you, I'm planning to use Genie Clips and channel on the ceiling to suspend two-layers of acoustic plasterboard. Genie Clip+Channel+15mm+12.5mm plasterboard will come to about 74mm. There's only one wall (which has two doors) where I'll probably need to build a stud wall in front of it and whatever I use needs to fit within that 74mm space, so I couldn't use IB-3 anyway as they're about 114mm high.


The flat bracket of the IB-3 can be screwed into the ceiling joist above the wall like shown on Soundproofing Company's website.

http://www.soundproofingcompany.com/product/ib-3-bracket/

If you are parallel between two joist you will need to install blocking between them for the top clip to attach to.

Spacing is important, you want the first clip to be within 6" of the end of the wall and spaced no more then 4' apart. They can also used to support backer boxes in the ceiling for speakers and lights.


----------



## doveman

With my walls I'm planning to use A237 clips rather than Genie clips, mainly to minimise space loss but they also cost quite a bit less and there's less of an issue with impact noise with the walls than the ceilings.

I believe I need to space them at maximum 600/1200mm spacings, as shown in the attached picture (bear in mind I won't be using studs, just screwing them directly into the wall), but presumably as I'll be fitting my inner ceiling first (or at least the first layer of plasterboard), I need to space the top row 100mm down from that, so it will be approx 161.5mm down from the original ceiling and once I add the second layer (12.5mm) plasterboard to the ceiling, the first row of wall clips+channel will be 87.5mm down from the inner ceiling?

My walls are 2.3m high, so if the first row is 161.5mm down, that leaves 2138.5mm, so would I fit three clips at 600mm spacings with a fourth one 238.5mm from the previous one, to leave the required 100mm spacing from the floor, or would it be better to just reduce the spacings for all four clips to around 509.5mm?

That's for the two end columns. The next one in has the first clip 600mm down from the top row and the next clip 1200mm from that, so would I also only have two clips in that column? Then the next column has a clip on the top row and a further two at 1200mm spacings which my wall isn't high enough for, so presumably I'd just have the bottom one spaced approx. 838.5mm from the middle one?

Sorry if these seem like dumb questions, I just want to be sure I know what I'm talking about and haven't missed something obvious before I start discussing my plans with a builder/engineer.


----------



## doveman

Ladeback said:


> The flat bracket of the IB-3 can be screwed into the ceiling joist above the wall like shown on Soundproofing Company's website.
> 
> http://www.soundproofingcompany.com/product/ib-3-bracket/
> 
> If you are parallel between two joist you will need to install blocking between them for the top clip to attach to.
> 
> Spacing is important, you want the first clip to be within 6" of the end of the wall and spaced no more then 4' apart. They can also used to support backer boxes in the ceiling for speakers and lights.


Ah, I see the misunderstanding. I don't have any ceiling joists so I'm going to have to screw something directly up into the concrete ceiling.


----------



## Ladeback

doveman said:


> Ah, I see the misunderstanding. I don't have any ceiling joists so I'm going to have to screw something directly up into the concrete ceiling.


OK, I understand now, but I think you could turn them the other way and they still work. Like these. You could just screw the rubble part into the the concrete and attach your walls to the drop down angle part or attach 2x4's to the ceiling then attach IB-3's to it.


----------



## niccolo

I'm exploring lower-budget floor soundproofing under carpet on the second floor of an existing home, are there threads or places on the internet you'd point me? I've read most of what's posted at Soundproofing Company and a ton of what's posted on this forum, and I have a decent handle on soundproofing 101, including the fact that soundproofing has a bit of an all-or-nothing quality, i.e. is only as effective as the weakest link. Basically what I'm trying to figure out is if I'm _not _going to deconstruct the existing OSB subfloor, what are my options. For example:


1) Adding a higher-priced (Serena) or cheaper rubber (horse stall mats) material on top of the OSB and a suspended OSB floor on top of that and pad and carpet on that seems like the most capable option, but it's costly and it would elevate the floor significantly, requiring a step up or ramp at the room entrance.


2) Adding rubber material (horse stall mats) with carpet pad and carpet directly on top is cheaper and elevates the floor less, I don't have a good sense of how significantly it would reduce soundproofing, but the loss of suspended mass (the extra layer of OSB) seems consequential.


3) There are carpet pads that are thicker and/or have multiple layers that are advertised for soundproofing purposes, but my guess is they help only modestly. If I'm only putting a pad down over the OSB subfloor and under the carpet, I don't have a good sense of how to think through the options.


----------



## HT Geek

niccolo said:


> I'm exploring lower-budget floor soundproofing under carpet in an existing home, are there threads or places on the internet you'd point me? I've read most of what's posted at Soundproofing Company and a ton of what's posted on this forum, and I have a decent handle on soundproofing 101, including the fact that soundproofing has a bit of an all-or-nothing quality, i.e. is only as effective as the weakest link. Basically what I'm trying to figure out is if I'm _not _going to deconstruct the existing OSB subfloor, what are my options. For example:
> 
> 
> 1) Adding a higher-priced (Serena) or cheaper rubber (horse stall mats) material on top of the OSB and a suspended OSB floor on top of that and pad and carpet on that seems like the most capable option, but it's costly and it would elevate the floor significantly, requiring a step up or ramp at the room entrance.


Is this a non-ground floor theater room? On a wooden sub-floor, Option 1 is your best bet of these three. 




> 2) Adding rubber material (horse stall mats) with carpet pad and carpet directly on top is cheaper and elevates the floor less, I don't have a good sense of how significantly it would reduce soundproofing, but the loss of suspended mass (the extra layer of OSB) seems consequential.


Not much. The additional mass in option 1 helps to isolate the noise in conjunction with the rubber mats. 




> 3) There are carpet pads that are thicker and/or have multiple layers that are advertised for soundproofing purposes, but my guess is they help only modestly. If I'm only putting a pad down over the OSB subfloor and under the carpet, I don't have a good sense of how to think through the options.


There's no substantial performance difference between high priced rubber mats and cheaper mats (e.g. horse stall mats). The important aspects are continuous coverage (no gaps) and cost/convenience/ease of installation.


----------



## niccolo

Thanks! Yep, second floor. Preventing sound from leaking into the room below is a secondary priority. My major motivation for exploring soundproofing of the floor is reducing the sound traveling through the framing to other rooms. Nearby rooms are a somewhat lesser concern than rooms that are a bit farther away.


Basically, I'm looking at options to enclose a second-floor loft area and turn it into a room. I can allocate a few thousand dollars to soundproofing upgrades, but not ten+ thousand dollars. I can work alongside a contractor but don't have the chops to do major work on my own. So I'm exploring incremental improvements that might help even if I don't do a full-on strip the walls and ceiling to the studs and build a proper room within a room. For example, for the two new walls I'll have to construct, I'm seriously considering staggered stud or dual-stud construction (with the caveat that if I'm doing less elsewhere flanking sound will reduce the soundproofing value). I'm thinking about putting an extra layer of drywall on the existing walls and/or ceiling. If I do that, I'm thinking about Green Glue between the drywall layers, though that stuff is seriously expensive. I'm thinking about backer boxes around canned ceiling lights and outlets. 



And I'm thinking about cost-effective things I might do on the floor. I'm guessing my best bet is probably a fairly thin rubber mat on top of the OSB subfloor with another OSB subfloor floating on top of the rubber mat, and pad and carpet on top of that. That would yield a fair bit of isolation and wouldn't elevate the floor too much.


----------



## HT Geek

niccolo said:


> Thanks! Yep, second floor. Preventing sound from leaking into the room below is a secondary priority. My major motivation for exploring soundproofing of the floor is reducing the sound traveling through the framing to other rooms. Nearby rooms are a somewhat lesser concern than rooms that are a bit farther away.
> 
> 
> Basically, I'm looking at options to enclose a second-floor loft area and turn it into a room. I can allocate a few thousand dollars to soundproofing upgrades, but not ten+ thousand dollars. I can work alongside a contractor but don't have the chops to do major work on my own. So I'm exploring incremental improvements that might help even if I don't do a full-on strip the walls and ceiling to the studs and build a proper room within a room. For example, for the two new walls I'll have to construct, I'm seriously considering staggered stud or dual-stud construction (with the caveat that if I'm doing less elsewhere flanking sound will reduce the soundproofing value). I'm thinking about putting an extra layer of drywall on the existing walls and/or ceiling. If I do that, I'm thinking about Green Glue between the drywall layers, though that stuff is seriously expensive. I'm thinking about backer boxes around canned ceiling lights and outlets.


You mentioned double-stud or staggered-stud walls but you also mentioned adding another layer of drywall to the existing walls. When talking about adding another layer of drywall, were you referring to the drywall on the walls in an adjacent room? If you build a double-stud or staggered stud interior room-within-a-room, you will need to remove any existing drywall on the HT room side first.




> And I'm thinking about cost-effective things I might do on the floor. I'm guessing my best bet is probably a fairly thin rubber mat on top of the OSB subfloor with another OSB subfloor floating on top of the rubber mat, and pad and carpet on top of that. That would yield a fair bit of isolation and wouldn't elevate the floor too much.


That's more or less what I did for the floor of my 2nd floor HT room. Be advised it will raise the floor to the point where you will need some sort of transition into the room. A ramp, steps, etc. Something. There's no way around that if you raise the floor. For my room I just made the entry at riser level and entering at a rear corner.

On top of my inner-room's sub-floor is a combo of rubber mat, OSB, and Green Glue.

Wood double-stud or staggered-stud walls are cheaper than using clips & channel. Drywall is cheap. It is beneficial, but you could skip the Green Glue if the cost is prohibitive for you.


----------



## niccolo

HT Geek said:


> You mentioned double-stud or staggered-stud walls but you also mentioned adding another layer of drywall to the existing walls. When talking about adding another layer of drywall, were you referring to the drywall on the walls in an adjacent room? If you build a double-stud or staggered stud interior room-within-a-room, you will need to remove any existing drywall on the HT room side first.
> 
> 
> 
> 
> That's more or less what I did for the floor of my 2nd floor HT room. Be advised it will raise the floor to the point where you will need some sort of transition into the room. A ramp, steps, etc. Something. There's no way around that if you raise the floor. For my room I just made the entry at riser level and entering at a rear corner.
> 
> On top of my inner-room's sub-floor is a combo of rubber mat, OSB, and Green Glue.
> 
> Wood double-stud or staggered-stud walls are cheaper than using clips & channel. Drywall is cheap. It is beneficial, but you could skip the Green Glue if the cost is prohibitive for you.


I have to build two new walls to enclose the loft space--that's where I'm considered staggered studs (only makes the wall one inch thicker) or dual stud (makes the wall another ~4 inches thicker compared to staggered studs). I have basically ruled out stripping drywall off existing walls and ceiling and doing a full room within a room, due to budget constraints, so this only applies to the new walls.


On the two new walls, a second layer of drywall on the interior is inexpensive so I'm thinking of doing that. Green Glue between the layers is pricey, so I'm leaning toward skipping that.


On the existing walls and ceiling, I'm mulling adding a second layer of drywall, too. That would get a bit more complicated because of multiple windows and power outlets on those walls. Here, too, Green Glue is an option. The windows will stay and just get covered by heavy drapes, this is intended to be both a movie and music room. The fact that I'm keeping multiple windows is presumably another argument for not going all-out on soundproofing, because the windows are going to somewhat compromise the soundproofing anyway.



On the floor, the options range from just putting a pad and carpet on the OSB subfloor to putting down a rubber pad and suspending a second OSB subfloor.


And as mentioned, backer boxes for canned ceiling lights and new electrical outlets make sense.


----------



## HT Geek

niccolo said:


> I have to build two new walls to enclose the loft space--that's where I'm considered staggered studs (only makes the wall one inch thicker) or dual stud (makes the wall another ~4 inches thicker compared to staggered studs). I have basically ruled out stripping drywall off existing walls and ceiling and doing a full room within a room, due to budget constraints, so this only applies to the new walls.


Speaking in a very general sense, the framing of a Room-w/in-a-Room is not costly when compared with other factors. For example, a rubber floor cost would likely be a multiple of the framing cost. But that is a generalization. Every room is unique.




> On the two new walls, a second layer of drywall on the interior is inexpensive so I'm thinking of doing that. Green Glue between the layers is pricey, so I'm leaning toward skipping that.


As much as I like GG, your approach makes sense.




> On the existing walls and ceiling, I'm mulling adding a second layer of drywall, too. That would get a bit more complicated because of multiple windows and power outlets on those walls. Here, too, Green Glue is an option. The windows will stay and just get covered by heavy drapes, this is intended to be both a movie and music room. The fact that I'm keeping multiple windows is presumably another argument for not going all-out on soundproofing, because the windows are going to somewhat compromise the soundproofing anyway.


Ok. GTK. This will be a multi-purpose room.




> On the floor, the options range from just putting a pad and carpet on the OSB subfloor to putting down a rubber pad and suspending a second OSB subfloor.
> 
> And as mentioned, backer boxes for canned ceiling lights and new electrical outlets make sense.


Backer boxes are good for various things. You don't need them for electrical outlets. You can use Acoustic Putty Pads instead; though backer boxes are not a bad thing per se for outlets. The QuietPutty brand costs a fraction of 3M (the gold standard).


----------



## Killroy

I have a question about an exterior facing wall that I want to further sound-proof...I want to be a good neighbor.

Here in AZ we get stucco over an inch of white hard foam. 2x4 studs with R31 pink foam and 1/2 standard sheet rock.

I want to create a 2x2 stud frame on the inside and add two layers of 5/8" X-rated sheetrock with Green Glue between the two layers. Using the 2x2 studs I was thinking of leaving an air gap between the original drywall and the new dual layer of 5/8". But then I began to think that maybe a 1" layer of Owens Corning fiberglass boards and then covered with a layer of TMS Mass Loaded Vinyl MLV Soundproofing Barrier which would leave about an inch of air between the dual 5/8"s.

Will this addition provide any more sound proofing that just the 2" air gap? I keep thinking that any additional mass would but then I read that air gap is afar more important.

So confused!


----------



## niccolo

Killroy said:


> I have a question about an exterior facing wall that I want to further sound-proof...I want to be a good neighbor.
> 
> Here in AZ we get stucco over an inch of white hard foam. 2x4 studs with R31 pink foam and 1/2 standard sheet rock.
> 
> I want to create a 2x2 stud frame on the inside and add two layers of 5/8" X-rated sheetrock with Green Glue between the two layers. Using the 2x2 studs I was thinking of leaving an air gap between the original drywall and the new dual layer of 5/8". But then I began to think that maybe a 1" layer of Owens Corning fiberglass boards and then covered with a layer of TMS Mass Loaded Vinyl MLV Soundproofing Barrier which would leave about an inch of air between the dual 5/8"s.
> 
> Will this addition provide any more sound proofing that just the 2" air gap? I keep thinking that any additional mass would but then I read that air gap is afar more important.
> 
> So confused!


Be cautious about avoiding a triple leaf effect: http://www.buyinsulationproductstore.com/blog/key-to-soundproofing-avoiding-the-triple-leaf-effect/


----------



## HT Geek

Killroy said:


> ... Using the 2x2 studs I was thinking of leaving an air gap between the original drywall and the new dual layer of 5/8"....


What you're describing sounds sounds like a triple leaf, which is bad in terms of sound attenuation. If there is existing drywall on the inside of the room, make sure you remove it first. Then leave an air gap between those 2x2 studs and the original framing of the room.

Furthermore, 2x2's are notorious for warping. They're often warped when purchased. It takes some effort to find any that aren't badly warped to start with. Try 2x3's instead if you insist on using boards smaller than 2x4's. Also, the 2x2's have other issues as well such as less load bearing capability and the wood is more likely to split when driving a screw into it since they're only 1-1/2" deep. Use 2x3's or larger.


----------



## Killroy

niccolo said:


> Be cautious about avoiding a triple leaf effect: http://www.buyinsulationproductstore.com/blog/key-to-soundproofing-avoiding-the-triple-leaf-effect/





HT Geek said:


> What you're describing sounds sounds like a triple leaf, which is bad in terms of sound attenuation. If there is existing drywall on the inside of the room, make sure you remove it first. Then leave an air gap between those 2x2 studs and the original framing of the room.
> 
> Furthermore, 2x2's are notorious for warping. They're often warped when purchased. It takes some effort to find any that aren't badly warped to start with. Try 2x3's instead if you insist on using boards smaller than 2x4's. Also, the 2x2's have other issues as well such as less load bearing capability and the wood is more likely to split when driving a screw into it since they're only 1-1/2" deep. Use 2x3's or larger.


Now I am even more confused.... I had read those before and I was under the understanding that a "leaf" was referring to sheetrock (drywall) only. So in my situation, I technically only have a single leaf wall. Our exterior walls are open faced to the exterior with the 1" anti-mold foam over a thin sheet of water barrier. They do put the stucco over the foam. So adding a double 5/8" layer would be the double leaf.

Would the foam and the stucco be considered a "leaf"?

So if a leaf is only drywall then wouldn't this be a double leaf?

Here's what I see:


----------



## HT Geek

Killroy said:


> Now I am even more confused....
> 
> Would the foam and the stucco be considered a "leaf"?


Yes




> So if a leaf is only drywall then wouldn't this be a double leaf?


No




> Here's what I see:


You have 3 surface layers. The foam board/stucco will have a different resonance vs. the drywall layers, which will alter the physics a bit, but it's still a "triple leaf" (i.e. 3 leafs or surface layers). What happens: a portion of sound travelling through the air cavities is amplified by the time it passes through the second air cavity.

However... come to think of it *since in your case the wall is exterior*, sound travelling out of your room may not be a concern to you. It's more difficult to judge how sound coming into your home would be impacted, but if you don't normally hear outside sounds coming into your home via those exterior walls, it stands to reason that you likely would not have an issue on the inside of your room even with your triple-leaf design.

It's primarily the low to mid frequency sounds that aren't damped as well in a triple leaf vs. double leaf wall.

This may help: http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/


----------



## Killroy

HT Geek said:


> Yes
> 
> 
> 
> 
> No
> 
> 
> 
> 
> You have 3 surface layers. The foam board/stucco will have a different resonance vs. the drywall layers, which will alter the physics a bit, but it's still a "triple leaf" (i.e. 3 leafs or surface layers). What happens: a portion of sound travelling through the air cavities is amplified by the time it passes through the second air cavity.
> 
> However... come to think of it *since in your case the wall is exterior*, sound travelling out of your room may not be a concern to you. It's more difficult to judge how sound coming into your home would be impacted, but if you don't normally hear outside sounds coming into your home via those exterior walls, it stands to reason that you likely would not have an issue on the inside of your room even with your triple-leaf design.
> 
> It's primarily the low to mid frequency sounds that aren't damped as well in a triple leaf vs. double leaf wall.
> 
> This may help: http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/


Thanks... now I get it.

The house is not done being built so I cannot judge how the exterior walls will perform to outside noise. We were going to do a test, once we move in, and see if we were getting good noise suppression without any added sheetrock. I do have two windows to deal with but those are far easier to deal with since I had already done that in our current home. I am getting pretty good at window plugs...although new home has very shallow window depth & sills. UGH!


----------



## niccolo

HT Geek said:


> Yes
> 
> 
> 
> 
> No
> 
> 
> 
> 
> You have 3 surface layers. The foam board/stucco will have a different resonance vs. the drywall layers, which will alter the physics a bit, but it's still a "triple leaf" (i.e. 3 leafs or surface layers). What happens: a portion of sound travelling through the air cavities is amplified by the time it passes through the second air cavity.
> 
> However... come to think of it *since in your case the wall is exterior*, sound travelling out of your room may not be a concern to you. It's more difficult to judge how sound coming into your home would be impacted, but if you don't normally hear outside sounds coming into your home via those exterior walls, it stands to reason that you likely would not have an issue on the inside of your room even with your triple-leaf design.
> 
> It's primarily the low to mid frequency sounds that aren't damped as well in a triple leaf vs. double leaf wall.
> 
> This may help: http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/


He did say a key motivation for the soundproofing was to be a good neighbor. Triple leaf pretty dramatically degrades the soundproofing effect, according to the data available. I can see the argument for not doing soundproofing of an exterior wall because it's not needed, but it doesn't make much sense to me to go to the trouble of constructing a dual-wall but to do it in a way that significantly degrades its performance.


----------



## Killroy

niccolo said:


> He did say a key motivation for the soundproofing was to be a good neighbor. Triple leaf pretty dramatically degrades the soundproofing effect, according to the data available. I can see the argument for not doing soundproofing of an exterior wall because it's not needed, but it doesn't make much sense to me to go to the trouble of constructing a dual-wall but to do it in a way that significantly degrades its performance.


My next door neighbor will be about 21-23 feet away with a 7-foot block wall between us. Wife thinks the distance is far enough to dissipate most of the noise that may escape the room through the wall. I am not so sure. But that is why we were going to do actual tests before adding anything to the room. I have at least one-month after we move into the new house before I can do anything to the room, including removing a wall that separates the two bedrooms that we're combining into one big room.

Now that I know that my original plans makes a triple leaf I may just add the two layers of 5/8"w/GG to the existing wall without any added space. But then again, that will be decided after I torture test the built wall.


----------



## niccolo

Killroy said:


> My next door neighbor will be about 21-23 feet away with a 7-foot block wall between us. Wife thinks the distance is far enough to dissipate most of the noise that may escape the room through the wall. I am not so sure. But that is why we were going to do actual tests before adding anything to the room. I have at least one-month after we move into the new house before I can do anything to the room, including removing a wall that separates the two bedrooms that we're combining into one big room.
> 
> Now that I know that my original plans makes a triple leaf I may just add the two layers of 5/8"w/GG to the existing wall without any added space. But then again, that will be decided after I torture test the built wall.


My guess is you'll find that if you're playing an action movie, a fair bit of low frequency sound/energy will leak. A capable sub will turn your house into a sub, i.e. the outside of the house will resonate. I've had a neighbor who lives 50 feet away, and on the opposite side relative to where my current setup is located, think that someone was revving a muscle car when I was watching an action movie with a lot of explosions. I have a fairly capable Rythmik FV15HP, though. And if you're not planning to watch loud action movies late at night, this may be less of a concern.


----------



## HT Geek

niccolo said:


> My guess is you'll find that if you're playing an action movie, a fair bit of low frequency sound/energy will leak. A capable sub will turn your house into a sub, i.e. the outside of the house will resonate. I've had a neighbor who lives 50 feet away, and on the opposite side relative to where my current setup is located, think that someone was revving a muscle car when I was watching an action movie with a lot of explosions. I have a fairly capable Rythmik FV15HP, though. And if you're not planning to watch loud action movies late at night, this may be less of a concern.


Good points, especially about nighttime when there is less background noise and neighbors might on occasion be sleeping with a window open (though perhaps that is a non-issue in AZ)!

I'd also surmise that 7' wall won't help much with mitigating any sound that leaks out. The sound will bounce around. Not saying it will be of no benefit; rather that it isn't going to stop it. Sound will bounce off that wall, the house, then over the wall for example.

Also, I agree with @Niccolo ;. Just applying extra drywall to the inside of your exterior wall will help mitigate the sound exiting the wall but not by much. -3 db perhaps. Clips and channel or inner wall/double stud/room-within-a-room will get you much better performance. 

Whether or not that approach is worthwhile depends on your goals. It sounds as if you do care about your neighbors possibly being bothered if they are outside while you're blaring an action movie inside. 

Looking at it from your perspective inside the room, the question is what sort of outside noises will you want to keep from penetrating into your cocoon? If you'll have dump trucks driving by for example, I'd suggest a double wall setup in the room (room-within-a-room).


----------



## nonstopdoc1

Guys, 2 of my walls are exterior concrete walls. Do I need DDW/GG and Rockwool Safe-n-sound insulation on framing alongside concrete walls?


----------



## Ladeback

nonstopdoc1 said:


> Guys, 2 of my walls are exterior concrete walls. Do I need DDW/GG and Rockwool Safe-n-sound insulation on framing alongside concrete walls?


I plan on doing it for the one wall I have that is near a concrete wall, but I only plan using pink fluffy and glueing 1" Styrofoam insulation on the concrete and at least a 1/2" gap from stud wall. I am also going to use IB-3 clips to decouple the top plate from the ceiling. The DDW/GGis mass a d will help and the link fluffy to help another some sound.


----------



## healthnut

nonstopdoc1 said:


> Guys, 2 of my walls are exterior concrete walls. Do I need DDW/GG and Rockwool Safe-n-sound insulation on framing alongside concrete walls?




Yes. I have a similar configuration in my basement and was also hoping to avoid this, but alas, after researching it, had to build the concrete walls the same as the others. 


Sent from my iPhone using Tapatalk


----------



## HT Geek

nonstopdoc1 said:


> Guys, 2 of my walls are exterior concrete walls. Do I need DDW/GG and Rockwool Safe-n-sound insulation on framing alongside concrete walls?





healthnut said:


> Yes. I have a similar configuration in my basement and was also hoping to avoid this, but alas, after researching it, had to build the concrete walls the same as the others.


It all depends on what you wish to accomplish and your starting circumstances.

For example, if you are planning to build a "room within a room" and use the double-stud wall construction technique, and if the concrete wall currently had no framing against it but there was existing (structural) framing in place against other walls, one could build a new wall frame along the concrete wall (air gapped from the concrete) and join that with the other interior walls (double stud). That would give you a hybrid where parts of the room would be using double stud walls (beside existing structural stud wall), and part would not (beside concrete wall). Since the concrete wall is your structural support in this example, you don't need to make a double stud wall along the concrete wall section. However, you must take care to ensure the structural and non-structural (inner) walls are not joined to one another.

So, as I said it depends on the circumstances and what you wish to accomplish.


----------



## niccolo

I am thinking through enclosing a loft and doing meaningful soundproofing. HT Geek has been hugely helpful in talking me through lots of details. I'm realizing a major challenge is going to be constructing an isolated floor and incorporating either a ramp or a step up to it. Major construction to take apart the existing subfloor is presumably not within a reasonable budget. I have some reservations about ramping or stepping, partly because that makes the room less generic if I decide to sell the house some day. But I also recognize that soundproofing the floor is an important component of an overall soundproofing effort. I'd love to see links to descriptions, and especially pictures, of ramp or step solutions people have implemented in their spaces. I tried to search but I don't think I had the optimal search terms.


----------



## niccolo

An additional question--I don't see much discussion of combining staggered stud _and _clip-and-channel (or the extreme of combining dual stud _and _clip-and channel). Is that because if you're already doing clip-and-channel, staggered stud (or dual stud) doesn't add much?


----------



## Nightlord

niccolo said:


> An additional question--I don't see much discussion of combining staggered stud _and _clip-and-channel (or the extreme of combining dual stud _and _clip-and channel). Is that because if you're already doing clip-and-channel, staggered stud (or dual stud) doesn't add much?



Every step further you take is diminishing returns... and any "leak" you have will be more fed. Think of soundproofing as waterproofing... the less you make it leak overall, the more it has the desire to leak where it's easiest ( as the pressure at that point increases when the rest don't leak as much ).


That's not saying you shouldn't do it. Every place is different and the current main leak may already be in a beneficial position, so it won't matter if that leaks a bit more when the rest gets more silent. Also when building new... unless you're very willing to re-do things, you only get one shot... so go for the max that you can... it won't be that easy to tear everything down to try dual studs instead of staggered one you have done all the rest....


If we're talking money... to spend a ****load of money on not getting the result you want..... or saving up some more and spending a ****load+some to get a satisfying result... At least for me that's a given what the choice would be.


Edit: Haha! Didn't know the site did censoring before!


----------



## niccolo

In my case I'd be stripping drywall off two existing walls (and building two new walls). If I'm already going to the trouble of doing that demolition, I'm just wondering whether _both _staggered stud and clip and channel should be on the agenda. Dual stud involves sacrificing too much space that's already limited. Part of my interest is also academic, I'm just curious to understand this soundproofing stuff better.







Nightlord said:


> Every step further you take is diminishing returns... and any "leak" you have will be more fed. Think of soundproofing as waterproofing... the less you make it leak overall, the more it has the desire to leak where it's easiest ( as the pressure at that point increases when the rest don't leak as much ).
> 
> 
> That's not saying you shouldn't do it. Every place is different and the current main leak may already be in a beneficial position, so it won't matter if that leaks a bit more when the rest gets more silent. Also when building new... unless you're very willing to re-do things, you only get one shot... so go for the max that you can... it won't be that easy to tear everything down to try dual studs instead of staggered one you have done all the rest....
> 
> 
> If we're talking money... to spend a ****load of money on not getting the result you want..... or saving up some more and spending a ****load+some to get a satisfying result... At least for me that's a given what the choice would be.
> 
> 
> Edit: Haha! Didn't know the site did censoring before!


----------



## Nightlord

niccolo said:


> In my case I'd be stripping drywall off two existing walls (and building two new walls). If I'm already going to the trouble of doing that demolition, I'm just wondering whether _both _staggered stud and clip and channel should be on the agenda. Dual stud involves sacrificing too much space that's already limited. Part of my interest is also academic, I'm just curious to understand this soundproofing stuff better.



If you CAN do both, then why not? I would think staggered is the more important part. An alternative to the clips would be more drywall lawyers... or mixed materials... green glue perhaps? Everything depends... what's your main issue? deep bass, or general soundproofing... ?



What are you doing with the other two walls?


----------



## niccolo

Hmm, if it's a choice, the evidence strongly suggests that just clip and channel beats just staggered studs. And the additional mass of more drywall layers doesn't seem like a good substitute for the decoupling that clips offer or the damping that Green Glue offers. Here's a good primer if of interest: http://www.soundproofingcompany.com/soundproofing101/4-elements-of-soundproofing/



I'm just struck that there's rarely mention of doing clip and channel _and _either staggered or dual studs. Maybe the marginal benefits are too small to justify doing it, but intuitively, when trying to contain very loud/reference level sound, it would seem like an obvious choice. Maybe my intuition is wrong?





Nightlord said:


> If you CAN do both, then why not? I would think staggered is the more important part. An alternative to the clips would be more drywall lawyers... or mixed materials... green glue perhaps? Everything depends... what's your main issue? deep bass, or general soundproofing... ?
> 
> 
> 
> What are you doing with the other two walls?


----------



## HT Geek

niccolo said:


> In my case I'd be stripping drywall off two existing walls (and building two new walls). If I'm already going to the trouble of doing that demolition, I'm just wondering whether _both _staggered stud and clip and channel should be on the agenda. Dual stud involves sacrificing too much space that's already limited. Part of my interest is also academic, I'm just curious to understand this soundproofing stuff better.


You could. The only downsides are cost and a bit more reduced finished room area/volume.




niccolo said:


> An additional question--I don't see much discussion of combining staggered stud _and _clip-and-channel (or the extreme of combining dual stud _and _clip-and channel). Is that because if you're already doing clip-and-channel, staggered stud (or dual stud) doesn't add much?


As @Nightlord alluded to, it's a prospect of diminishing returns. Much like trading up in higher end audio equipment. 




niccolo said:


> Hmm, if it's a choice, the evidence strongly suggests that just clip and channel beats just staggered studs. And the additional mass of more drywall layers doesn't seem like a good substitute for the decoupling that clips offer or the damping that Green Glue offers. Here's a good primer if of interest: http://www.soundproofingcompany.com/soundproofing101/4-elements-of-soundproofing/


Right. Double stud > clips & channel > staggered studs > normal (structural) studs.




> I'm just struck that there's rarely mention of doing clip and channel _and _either staggered or dual studs. Maybe the marginal benefits are too small to justify doing it, but intuitively, when trying to contain very loud/reference level sound, it would seem like an obvious choice. Maybe my intuition is wrong?


I suspect it's due to the cost and work/effort. Staggered stud installs are relatively rare.

To your point, it would provide a slight benefit in sound reduction, but I'd be inclined to recommend an alternative of clips & channel, 3x drywall layers, and additional clips to handle the increased weight.


----------



## niccolo

HT Geek said:


> You could. The only downsides are cost and a bit more reduced finished room area/volume.
> 
> 
> 
> 
> As @Nightlord alluded to, it's a prospect of diminishing returns. Much like trading up in higher end audio equipment.
> 
> 
> 
> 
> Right. Double stud > clips & channel > staggered studs > normal (structural) studs.
> 
> 
> 
> 
> I suspect it's due to the cost and work/effort. Staggered stud installs are relatively rare.
> 
> To your point, it would provide a slight benefit in sound reduction, but I'd be inclined to recommend an alternative of clips & channel, 3x drywall layers, and additional clips to handle the increased weight.


Interesting. There are a lot of theaters posted on here where cost and effort don't seem like they'd tip the scales. People must assess that if they're already doing clip and channel, dual stud or staggered just just doesn't add much. I don't think I've seen any empirics one way or another, i.e. testing dual or staggered stud _and _clips, which itself seems surprising.


I'm not surprised there's less staggered stud. When space is at a premium, clips have the advantage, albeit at somewhat higher cost. When space is less constrained, dual stud has the clear advantage. Staggered stud seems to fall into the niche of space _and _budget constrained.


----------



## policy

Is there a way to use conduits to future proof my room without losing soundproofing? Im installing a 7.4.1 (2 maybe) system, and I would like to be able to have the conduits to add upper atmospheric speakers if necessary. Has anyone done this before?


----------



## HT Geek

niccolo said:


> Interesting. There are a lot of theaters posted on here where cost and effort don't seem like they'd tip the scales. People must assess that if they're already doing clip and channel, dual stud or staggered just just doesn't add much. I don't think I've seen any empirics one way or another, i.e. testing dual or staggered stud _and _clips, which itself seems surprising.


I've never seen a lab test that covered that scenario (and I've read MANY!). Academically speaking, it seems logical to me that it would provide superior performance vs. only clips or only staggered stud, since either provides an improvement in performance by itself and using clips in conjunction with staggered would have two benefits: 1) increased air gap depth; and 2) further decoupling from the structure.


----------



## HT Geek

policy said:


> Is there a way to use conduits to future proof my room without losing soundproofing? Im installing a 7.4.1 (2 maybe) system, and I would like to be able to have the conduits to add upper atmospheric speakers if necessary. Has anyone done this before?


Yes! I would say that's one of the 'best practices' of dedicated home theater room construction. Running conduit for speaker wires in particular allows for future-proofing of technology changes and makes it easier to run new wires if that ever becomes necessary.

The challenge lies in how to place them such that they are not impeding anything else, hidden from view, and don't compromise one's sound proofing efforts. The typical method is to install them in a soffit.

Clamp down the conduits to hold them in place. Place some insulation around them as best you can to minimize the risk of vibration. Place them in the ceiling, walls, or soffits to hide them from view. Limit their openings so you don't create a "tin cans and string" effect of channeling flanking noise from one end to the other.

To give you an example, my HT room has a conduit running from the rear to front of my room. In the rear, it is open to the inside of my equipment rack. The other end opens behind my AT screen. There are a couple of 90 degree turns at either end. The equipment rack is sealed to prevent sound leakage. I've never had any issues with sound traversing/flanking through the conduit. I use it to run speaker wire from rear to front of the room.

I have another conduit that routes my Atmos wiring up into the attic. That one required a bit more thought process because I had to punch a hole in my sound-proof shell. My compromise was to punch that hole via the equipment rack rear/closet area and not the listening room itself. There are also several bends in the pipe, and it is sealed where it enters the backer boxes for my (TBD) Atmos positions (I have installed backer boxes in the ceiling and pre-wired them but no Atmos speakers in use atm).


----------



## policy

If the conduit was run so that it was all connected, with openings for the speaker holes, wouldn't that eliminate flanking?

What about using steel conduit as opposed to PVC? Preferable? Or PVC preferable? 

The current plans call for OSB--->5/8--->GG--->5/8.


----------



## MBK_BKLYN

Hi folks,

I've got a soundproofing question I could use some help on:

The master bedroom of my apartment shares a thin wall with the apartment next door. To make matters worse, the apartments share a bank of windows and are split along a window mullion (NYC real estate adventures...). This means that I've got loads of places for sound to leak in:


The wall itself
The thin metal strip splitting the window mullion
The window frame itself

You can hear people in the other apartment readily, their conversations, their alarm clock (the wall on the other side is their kids' bedroom), etc.

I'm guessing the wall construction is a single layer of 5/8" drywall on each side against metal studs, with some basic insulation.

I've got a few remediation options:


I could install a layer of drywall over the existing drywall with Green Glue. 
I could rip down the drywall and install clips and Green Glue. 
I could get some interior soundproofing windows installed that isolated the window, from a company like CityProof.

How much improvement in noise transmission reduction might I expect just doing a second drywall layer with Green Glue over the existing drywall? I found some data showing a single later of GG on the source side gets you fairly close to Resilient channel STC. However, in my situation the GG would be on the receiving room side.

Thanks for any insight!


----------



## HT Geek

policy said:


> If the conduit was run so that it was all connected, with openings for the speaker holes, wouldn't that eliminate flanking?
> 
> What about using steel conduit as opposed to PVC? Preferable? Or PVC preferable?
> 
> The current plans call for OSB--->5/8--->GG--->5/8.


It all depends on your implementation, but it's not a complicated feat. You want to avoid it potentially vibrating and have enough bends and/or length that sound going into any openings will dissipate before it would reach another outlet in the conduit/pipe.

If you were to create a conduit with multiple branches for example, that could get more complex to avoid sound entering the conduit and coming out elsewhere, but overall it will just require some forethought and planning before implementation.

Also think about how you might want to utilize it after your walls are up and it's buried. You don't want too many bends or your wires/connectors are more likely to get stuck. Make sure you snake extra pull wires before you conceal the conduit and anytime you run a new wire, include a new pull wire for the next time you want to run a wire.

It's ideal to use separate conduits between various points. The more branches you have off a conduit, the more difficult it's likely to be to run wires between Point A and Point X. 

Oversize your conduit as much as is reasonable. Larger conduits mean larger holes, which means greater chance of unwanted flanking noise. It's a balance. Larger conduit makes future wiring jobs much easier. If the wires inside are too tight, you may not be able to run new wires as desired. OTOH, Murphy's Law says if you use a fat pipe to avoid that problem, you will probably never ever use it in the future. LoL. 

I have conduits in my HT room that basically provide a wiring path from the equipment rack to areas that would otherwise be impossible to reach. I used as few as possible. Mine are all in my soffit.


----------



## HT Geek

MBK_BKLYN said:


> Hi folks,
> 
> I've got a soundproofing question I could use some help on:
> 
> The master bedroom of my apartment shares a thin wall with the apartment next door. To make matters worse, the apartments share a bank of windows and are split along a window mullion (NYC real estate adventures...). This means that I've got loads of places for sound to leak in:
> 
> 
> The wall itself
> The thin metal strip splitting the window mullion
> The window frame itself
> 
> You can hear people in the other apartment readily, their conversations, their alarm clock (the wall on the other side is their kids' bedroom), etc.
> 
> I'm guessing the wall construction is a single layer of 5/8" drywall on each side against metal studs, with some basic insulation.


Or perhaps there is no insulation. Fiberglass insulation is surprisingly decent at muffling the frequencies of human voices.



> I've got a few remediation options:
> 
> 
> I could install a layer of drywall over the existing drywall with Green Glue.
> I could rip down the drywall and install clips and Green Glue.
> I could get some interior soundproofing windows installed that isolated the window, from a company like CityProof.
> 
> How much improvement in noise transmission reduction might I expect just doing a second drywall layer with Green Glue over the existing drywall? I found some data showing a single later of GG on the source side gets you fairly close to Resilient channel STC. However, in my situation the GG would be on the receiving room side.


To deal with the noisy neighbor, your best bet would be removing existing drywall, add insulation if there isn't any, clips & channel, 2x drywall w/Green Glue sandwich.

Your next best option is to add DW + GG to your existing wall. 

One more thing.... Beefing up that wall won't help you with sound that flanks via the ceilings or through your window. You'll most likely solve one problem and it will amplify another (i.e. draw more attention to where else sound leaks in). That may or may not bother you.

In your case, when you compare soundproofing options, pay particular attention toward low to mid frequency performance (~100 to about 4,000 Hz). Ignore the STC ratings. Think of STC as a marketing tool. Focus on lab tests that demonstrate performance sub-4,000 Hz.


----------



## RyanDHT

policy said:


> Is there a way to use conduits to future proof my room without losing soundproofing? Im installing a 7.4.1 (2 maybe) system, and I would like to be able to have the conduits to add upper atmospheric speakers if necessary. Has anyone done this before?


I ran 1-1/4" smurf tube around my entire room. I have a couple closets in the room that it would allow me to get to the ends of the smurf tube if necessary. the 1-1/4" stuff is pretty spendy, but the 3/4" stuff isn't as bad. I also ran a giant PVC tube from where the projector to the media closet is. I terminated that connection with a threaded PVC fitting that I found in the plumbing aisle of Big Orange and a lock nut from the electrical aisle that I attached to a junction box. I had to cut the hole for the fitting in the junction box with a hole saw. I covered the entire back of the junction box with a putty pad as well as I could around the PVC pipe. and I stuff a ball of putty into the PVC tube when the cables are run, and I can pull the ball out if I need to run more cables. Wish I had taken a picture of this before I drywalled everything. Not sure if that helps you at all.


----------



## LydMekk

I ran 40mm plastic tubes for all the signal and speaker wires in the room, exiting by the outside rack.
Placed them in the soffits inside the room. Tied down, filled with insulation around them.
Nothing is vibrating, no rattles.
And completely future proof in regds. to more wires, faulty wires etc.
Did the same to the projector. 3 tubes where 2 going to the proj and one for the ceiling electrical and atmos cables.
Stuffed the exit to the outside rack with acoustic foam. The exit is place in the rear soffit.
Built in 2 removable small hatches in the soffit back there to be able to reach in and do future cable stuff.

You need to think ahead in this hobby ^^.


----------



## doveman

Ladeback said:


> OK, I understand now, but I think you could turn them the other way and they still work. Like these. You could just screw the rubble part into the the concrete and attach your walls to the drop down angle part or attach 2x4's to the ceiling then attach IB-3's to it.


Thanks. I'll have to see if something like that would work. 

The wall I need to build the stud wall in front of has two doors in it and there's not much area of the wall which is strong enough to screw the clips to, so the first picture probably wouldn't work but it depends on how many clips I'd actually need to support the stud wall.

Same with the second picture. If I only need a few clips I might be able to screw the short part of the clip to the ceiling and hide the longer part behind the vertical studs but if I need clips all along the wall then the long part may end up being in the way of the doorways.

The third option I think would be tricky as I'd have to stop the ceiling soundproofing where the top plate of the stud wall sits and I plan to do the ceiling first, so it would be difficult to plan for this. 

Whatever I do I need to be careful not to undermine the ceiling soundproofing (which is where the biggest problem is) by coupling the stud wall to the ceiling in a way that allows the noise to travel through that instead. For that reason it would probably be preferable to put the clips on the structural wall rather than the ceiling if possible but as I say, I'm not sure I can do this.


----------



## doveman

I wonder if someone could clue me in about air conditioning, about which I know very little.

I see on this page that there are wall-mounted and ducted units https://www.airconco.com/home-air-conditioning/ but surely even the wall-mounted ones need to be ducted to an exterior condensor don't they? Are there any particular units you'd recommend?

As for the condensor, presumably it would be a bad idea from a soundproofing point of view to mount that on the exterior of a room that's being soundproofed, as you'd have to make a hole in the structural wall and the inner wall to connect the condensor to the wall-unit or outlets in the room? So I should be looking to mount the condensor outside a different room, like my kitchen, and then run pipes/ducts via the longest route with multiple bends, which for me would be across the kitchen ceiling, out into the hall and then into the soundproofed room(s)?

If I'm fitting a ducted system, I guess the ceiling is better place to fit the duct outlet rather than the wall, as in my case at least there's going to be more of an air-gap with the ceiling, so I can probably still fit some insulation between the ducting and the structural ceiling. Presumably the ducting will still undermine the soundproofing somewhat though, as where it runs there'll just be some a box made of quite thin material filled with air, instead of thick sound-absorbing insulation?

I understand that I can get a unit with a heat-pump which are very efficient but only adequate when the temperature's no lower than about 4c. As it does get colder than that here in England, I'll need another source of heating as well. I have central heating but as it's going to be tricky soundproofing the walls with the radiators on, not to mention around the pipes, I'm thinking of removing the radiators and pipes and just fitting underfloor electric heating instead. The underfloor heating will cost approx. £300-400 per room, plus the costs of removing the radiators+pipes, so I'll have to think about whether that's really necessary. Can you buy feet for radiators so that most of the weight is supported by the floor rather than the wall, or get ones designed to sit on the floor as replacing the radiators might be a lot cheaper, although I'll still have the pipes to deal with. I was just going to box them in but that'll mean fitting battens above and below them to the wall, with a piece of wood on top and of course that means the box is attached to the structural wall, so carries the risk that noise will transfer from the wall through the box into the room (and vice-versa).


----------



## HT Geek

doveman said:


> I wonder if someone could clue me in about air conditioning, about which I know very little.
> 
> I see on this page that there are wall-mounted and ducted units https://www.airconco.com/home-air-conditioning/ but surely even the wall-mounted ones need to be ducted to an exterior condensor don't they? Are there any particular units you'd recommend?


Most of what is on that page are called min-split systems. They are available in both ductless and ducted forms. Mitsubishi is known for its mini-split systems. I'm sure there are other good brands, but Mitsu is more or less the standard to meet or beat.

If you have a ductless system, there will be a wall mounted unit. Electrical wiring and tubes must be run that connect the wall unit and heat exchanger (mounted on the exterior of your home). A ducted system works just like a normal HVAC system, but it is smaller and has less capacity. Typically, you can heat/cool 2-3 average size rooms and that's about it. You have an exterior component and an interior component. The interior component will have a fan that blows supply air through the ducts, which are usually flex duct. I'm not familiar enough with them to know how they handle return air.




> As for the condensor, presumably it would be a bad idea from a soundproofing point of view to mount that on the exterior of a room that's being soundproofed, as you'd have to make a hole in the structural wall and the inner wall to connect the condensor to the wall-unit or outlets in the room? So I should be looking to mount the condensor outside a different room, like my kitchen, and then run pipes/ducts via the longest route with multiple bends, which for me would be across the kitchen ceiling, out into the hall and then into the soundproofed room(s)?


Yes. Correct.




> If I'm fitting a ducted system, I guess the ceiling is better place to fit the duct outlet rather than the wall, as in my case at least there's going to be more of an air-gap with the ceiling, so I can probably still fit some insulation between the ducting and the structural ceiling. Presumably the ducting will still undermine the soundproofing somewhat though, as where it runs there'll just be some a box made of quite thin material filled with air, instead of thick sound-absorbing insulation?


That's not a big deal in and of itself. The solution is the same as any other HVAC setup. Use flex duct. Make bends in the duct to allow flanking noise to be dissipated as it is directed into the flex duct bends. Place insulation around the flex duct in the cavity where the duct is run.




> I understand that I can get a unit with a heat-pump which are very efficient but only adequate when the temperature's no lower than about 4c. As it does get colder than that here in England, I'll need another source of heating as well. I have central heating but as it's going to be tricky soundproofing the walls with the radiators on, not to mention around the pipes, I'm thinking of removing the radiators and pipes and just fitting underfloor electric heating instead.


Heat pumps are awful unless you live in a climate that is warm all the time (e.g. Florida). Beyond that, they should be avoided IMHO.

Removing the radiators would be advisable from several viewpoints. For example, there is obviously the issue of trying to soundproof around them. Then there's the question of whether or not they will continue to be functional, etc. It would be easier if they didn't exist in that room.




> The underfloor heating will cost approx. £300-400 per room, plus the costs of removing the radiators+pipes, so I'll have to think about whether that's really necessary. Can you buy feet for radiators so that most of the weight is supported by the floor rather than the wall, or get ones designed to sit on the floor as replacing the radiators might be a lot cheaper, although I'll still have the pipes to deal with. I was just going to box them in but that'll mean fitting battens above and below them to the wall, with a piece of wood on top and of course that means the box is attached to the structural wall, so carries the risk that noise will transfer from the wall through the box into the room (and vice-versa).


I don't know about supporting their weight, but I'd say whether or not they are functional is the key to everything else. If they are disabled then you have more options even if they remain physically in place.


----------



## doveman

HT Geek said:


> Most of what is on that page are called min-split systems. They are available in both ductless and ducted forms. Mitsubishi is known for its mini-split systems. I'm sure there are other good brands, but Mitsu is more or less the standard to meet or beat.
> 
> If you have a ductless system, there will be a wall mounted unit. Electrical wiring and tubes must be run that connect the wall unit and heat exchanger (mounted on the exterior of your home). A ducted system works just like a normal HVAC system, but it is smaller and has less capacity. Typically, you can heat/cool 2-3 average size rooms and that's about it. You have an exterior component and an interior component. The interior component will have a fan that blows supply air through the ducts, which are usually flex duct. I'm not familiar enough with them to know how they handle return air.


It seems strange but these systems don't seem to have any return ducts, they just appear to have a tube going from the exterior component to the wall mounted units https://www.appliancesdirect.co.uk/p/eiq-9k9kc18kwminv/electriq-eiq9k9kc18kwminv so I don't know how that works.

Perhaps with ductless systems like that it wouldn't be so bad having the exterior component mounted directly outside a soundproofed room, as the only things penetrating the wall would be the power cable and the flexible tube(s), which seem unlikely to transfer much sound from/to the interior? I could run the tube long, behind the inner wall or ceiling, with lots of bends so that any noise generated by the exterior component is dissipated before it gets to the wall unit.

With a ducted system, whether mini-split or normal HVAC, and the exterior unit mounted outside my kitchen would I just run one duct from that to the hall and then split it from there into separate ducts for each of the soundproofed rooms, with a separate fan for each? Then I'd need a separate return duct from each room going back to the hall where they'd combine before going back to the exterior unit?



> Heat pumps are awful unless you live in a climate that is warm all the time (e.g. Florida). Beyond that, they should be avoided IMHO.


OK, good to know.



> Removing the radiators would be advisable from several viewpoints. For example, there is obviously the issue of trying to soundproof around them. Then there's the question of whether or not they will continue to be functional, etc. It would be easier if they didn't exist in that room.
> 
> I don't know about supporting their weight, but I'd say whether or not they are functional is the key to everything else. If they are disabled then you have more options even if they remain physically in place.


I'm not sure disabling them and leaving them in place really helps. I'd have to remove them from the wall and remount them on the inner wall in any case, as it'd be impossible to soundproof around them but there's still the issue of the pipes. I could get those remounted on the inner wall as well (they'd need some cutting and splicing in places to make them a bit shorter) but then I've still got the issue of where they go through the wall between the two soundproofed rooms. It doesn't really matter to me if some noise transfers between the rooms via the pipes, it's just whether I can insulate around them to prevent them contacting the structural wall and transferring noise via that to/from the adjoining flats, which I guess should be possible by making some space around the pipes to fit some sealant.

Some of the underfloor heating systems I've seen have lifetime guarantees and I guess it'd sit on top of my sub-floor and below my floor covering (cork tiles or wood/veneer planks probably), so it wouldn't be impossible to access if it did develop a fault but obviously a lot harder than servicing a radiator as I'd have to clear the entire room to take the floor covering up!


----------



## HT Geek

doveman said:


> It seems strange but these systems don't seem to have any return ducts, they just appear to have a tube going from the exterior component to the wall mounted units https://www.appliancesdirect.co.uk/p/eiq-9k9kc18kwminv/electriq-eiq9k9kc18kwminv so I don't know how that works.
> 
> Perhaps with ductless systems like that it wouldn't be so bad having the exterior component mounted directly outside a soundproofed room, as the only things penetrating the wall would be the power cable and the flexible tube(s), which seem unlikely to transfer much sound from/to the interior? I could run the tube long, behind the inner wall or ceiling, with lots of bends so that any noise generated by the exterior component is dissipated before it gets to the wall unit.


That would work. You should be fine.



> With a ducted system, whether mini-split or normal HVAC, and the exterior unit mounted outside my kitchen would I just run one duct from that to the hall and then split it from there into separate ducts for each of the soundproofed rooms, with a separate fan for each? Then I'd need a separate return duct from each room going back to the hall where they'd combine before going back to the exterior unit?


That all depends on the system design. The ducted ones are more complicated. They're basically just a compact HVAC system.




> I'm not sure disabling them and leaving them in place really helps. I'd have to remove them from the wall and remount them on the inner wall in any case, as it'd be impossible to soundproof around them but there's still the issue of the pipes. I could get those remounted on the inner wall as well (they'd need some cutting and splicing in places to make them a bit shorter) but then I've still got the issue of where they go through the wall between the two soundproofed rooms. It doesn't really matter to me if some noise transfers between the rooms via the pipes, it's just whether I can insulate around them to prevent them contacting the structural wall and transferring noise via that to/from the adjoining flats, which I guess should be possible by making some space around the pipes to fit some sealant.


Ideally, just wrap them with pipe insulator and leave a small air gap between the edge of the pipe insulation and the walls (inner and outer). I suspect the question is going to be, do you have enough space for a large enough air gap to do that? You might be better off running the majority of the pipe inside your HT room, much like what you must have in the room currently. Disconnect them. Build the inner room and install an extension pipe. Reinstall them inside the interior room. Insulate the pipes. Seal the opening around the insulated pipe with acoustic caulk. Live with the occasional hissing/operating noise. At least you'll have heat in there when you need it. 

Incidentally, I'd also suggest - if you don't have it already - a cut off valve outside the room to allow you to turn off heating the HT room while continuing to heat the remainder of your home. HT rooms are usually warmer than other rooms when you have the room closed off and all the equipment running. Between that and the fact the room will be better insulated than the remainder of your home, you won't need as much heating in there.

I'd still consider a mini-split HVAC for cooling purposes.


----------



## doveman

HT Geek said:


> That would work. You should be fine.
> 
> That all depends on the system design. The ducted ones are more complicated. They're basically just a compact HVAC system.


There's pros and cons either way. With the ductless mini-split, I could put the exterior unit on my balcony which would be a lot easier to access for visual checks and service, whereas a ducted exterior unit outside my kitchen would only be accessible with a tall ladder (I'm in a first floor apartment) and I couldn't even go up to check it myself, as I suffer from severe vertigo.

On the other hand a ducted system would be more discreet and look better than having big old units hanging off the wall, plus I'd have to plan to ensure the wall can hold the weight wherever I plan to hang them. Maybe the ducts are less likely to develop issues than the mini-split tubes too, which would be a problem if they're buried behind the wall/ceiling. I'm just wondering if there's any possibility of the rubber tubes cracking or rotting over time?

I'm still confused how the mini-split system works without a return path, as one of the reasons I'll need air con is because the rooms will be airtight, so if there's just extra air being pumped in with nowhere for the existing air to go I can't see how that can work. Perhaps it uses a single tube by switching the wall unit between bringing in fresh air and exhausting the old air back out? I'm not even sure if HVACs actually exhaust air per se, as I read that the return vent is to allow the system to filter and recirculate the already cooled/warmed air to improve efficiency.

Of course the rooms won't always be airtight. When I open doors that will let in fresh air from the hallway and kitchen but when the doors are closed and the windows plugged it will (or should) be.



> Ideally, just wrap them with pipe insulator and leave a small air gap between the edge of the pipe insulation and the walls (inner and outer). I suspect the question is going to be, do you have enough space for a large enough air gap to do that? You might be better off running the majority of the pipe inside your HT room, much like what you must have in the room currently. Disconnect them. Build the inner room and install an extension pipe. Reinstall them inside the interior room. Insulate the pipes. Seal the opening around the insulated pipe with acoustic caulk. Live with the occasional hissing/operating noise. At least you'll have heat in there when you need it.


I doubt there'll be room to have a gap between the pipes and the inner and outer walls, as I'm deliberating using clip+channel rather than stud walls to minimise the space lost. So moving the pipes to inside the room and then sealing around where they go through the walls to isolate it will probably be the best option. I can live with a bit of hissing 

Regarding underfloor heating, I guess I might be able to just have that in the centre of the room and not under the sofa and other furniture around the perimeter, so I'd only have to lift the flooring in the middle of the room to repair/replace it and wouldn't have to clear the entire room.



> Incidentally, I'd also suggest - if you don't have it already - a cut off valve outside the room to allow you to turn off heating the HT room while continuing to heat the remainder of your home. HT rooms are usually warmer than other rooms when you have the room closed off and all the equipment running. Between that and the fact the room will be better insulated than the remainder of your home, you won't need as much heating in there.


Good point, I'll probably save so much on heating that it will pay for the build  I've got thermostatic valves on the radiators, so it's quite easy to disable them individually. I'm not sure if hot water still fills the pipes up to the valve but that's not going to generate much heat anyway.


----------



## dellhop

I'm sorry if these questions have been covered but its been a while since I builT my theater room and a lot has happened since then. 

When I built my theater I did not sound proof due to cost and the size of the room. I was not concerned with sound proofing since typically everyone in the house would be together in the room at the time. 10 years later though my kids are 10 and 12, getting into gaming and there own things. I will be converting my theater into a multipurpose gaming/movie/hang out. As such I need to move my office out of the room (it was in the corner and again wasn't an issue since I wouldn't be working if we were watching a movie). 

My theater/variety room takes up half the basement of my standard colonial (center stair case). All the mechanical is on the half. I want to add a new office to about 2/5 of that unfinished section and want to sound proof it to some extent so that the kids can be in the theater area and I can still either work, play or stream with out to much interference. I'm not too worried about low end dampening as movies being watched while I'm not in there will be few. I'm more concerned with voices, laughter and jumping around noises. Here's are the sources or issues I think I have to deal with. 

1. Limiting the sounds I mentioned above, kids playing, laughing and occasionally screaming
2. The section I will build has concrete half walls with two windows, one on each side of the exterior
3. Bulkhead
4. HVAC blower, furnace in the last bit of unfinished area
5. Drains and water feeds below the joists in the ceiling. 
6. over-sized hollow core door to theater area
7. Hose shut off that needs access (so some form of box added that can be opened to reach valve)
8. Potential access to electric junction box.

I've read through and understand sounds proofing and its requirements when you build a new theater with no windows and limited access. But is there any way to dampen most sounds to the point where head set mics and/or the right type of microphone (podcasts and streaming) won't pick up with all the above issues existing? Again not looking to create a black hole of sound, but enough that normal everyday life doesn't intrude. 

Sorry if this is all over the place and I appreciate all the insight available. Thanks.


----------



## niccolo

dellhop said:


> I'm sorry if these questions have been covered but its been a while since I builT my theater room and a lot has happened since then.
> 
> When I built my theater I did not sound proof due to cost and the size of the room. I was not concerned with sound proofing since typically everyone in the house would be together in the room at the time. 10 years later though my kids are 10 and 12, getting into gaming and there own things. I will be converting my theater into a multipurpose gaming/movie/hang out. As such I need to move my office out of the room (it was in the corner and again wasn't an issue since I wouldn't be working if we were watching a movie).
> 
> My theater/variety room takes up half the basement of my standard colonial (center stair case). All the mechanical is on the half. I want to add a new office to about 2/5 of that unfinished section and want to sound proof it to some extent so that the kids can be in the theater area and I can still either work, play or stream with out to much interference. I'm not too worried about low end dampening as movies being watched while I'm not in there will be few. I'm more concerned with voices, laughter and jumping around noises. Here's are the sources or issues I think I have to deal with.
> 
> 1. Limiting the sounds I mentioned above, kids playing, laughing and occasionally screaming
> 2. The section I will build has concrete half walls with two windows, one on each side of the exterior
> 3. Bulkhead
> 4. HVAC blower, furnace in the last bit of unfinished area
> 5. Drains and water feeds below the joists in the ceiling.
> 6. over-sized hollow core door to theater area
> 7. Hose shut off that needs access (so some form of box added that can be opened to reach valve)
> 8. Potential access to electric junction box.
> 
> I've read through and understand sounds proofing and its requirements when you build a new theater with no windows and limited access. But is there any way to dampen most sounds to the point where head set mics and/or the right type of microphone (podcasts and streaming) won't pick up with all the above issues existing? Again not looking to create a black hole of sound, but enough that normal everyday life doesn't intrude.
> 
> Sorry if this is all over the place and I appreciate all the insight available. Thanks.



You're going to get asked for a floorplan right away--it's hard to picture this without one.


The basic principles of soundproofing apply--decoupling (e.g. clips), mass (e.g. extra drywall), damping (e.g. Green Glue), absorption (e.g. cheap pink insulation). All of these matter as part of a system. And the system is only as capable as its weakest link, whether that's a door or the ceiling or unsealed can lighting.


----------



## dellhop

niccolo said:


> You're going to get asked for a floorplan right away--it's hard to picture this without one.
> 
> 
> The basic principles of soundproofing apply--decoupling (e.g. clips), mass (e.g. extra drywall), damping (e.g. Green Glue), absorption (e.g. cheap pink insulation). All of these matter as part of a system. And the system is only as capable as its weakest link, whether that's a door or the ceiling or unsealed can lighting.


Got it. I'll work on the floor plan. I wondered if one would be desired as I'm not looking for the best solution, but more what would be worth doing with all the week points. I'll try to draw up the plan. Thanks.

Edit. Here's what i could come up with for floor plan. Hope it usable

The top blue line is the electrical I mentioned and the bottom is the water shut off. The red square is the bulk head and the yellow is the proposed wall.


----------



## policy

I need the braintrust's help here. I purchased these speakers: https://www.klipsch.com/products/ks-7502-thx-in-ceiling-speaker which are 13.25" wide. My joist openings are 14" across at the bottom of the Boise Pacific I-Beam which my engineer says I CANNOT notch (I have 15" in between the particle board joists). So I am pretty much SOL on backer boxes.

So the first thing: These speakers are sealed on the back, by a pretty flimsy plastic housing. Do I NEED backer boxes? 













Second, if I do need back boxers, because I have NO little area to work with, I was thinking about gluing MLV around the sides, and then basically fashioning a coffee can around the speakers, and then a bead of GG seal around the end of the spaekers. 


My third thought is using a 14" PVC tube, cut to length, with 2 layers of MLV surrounding the speaker. I would sand flat the two sides of the tube that would butt up against the joists, because obviously a speaker rubbing the joists breaks the de-coupling.

Any thoughts team?


----------



## Ladeback

policy said:


> I need the braintrust's help here. I purchased these speakers: https://www.klipsch.com/products/ks-7502-thx-in-ceiling-speaker which are 13.25" wide. My joist openings are 14" across at the bottom of the Boise Pacific I-Beam which my engineer says I CANNOT notch (I have 15" in between the particle board joists). So I am pretty much SOL on backer boxes.
> 
> So the first thing: These speakers are sealed on the back, by a pretty flimsy plastic housing. Do I NEED backer boxes?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Second, if I do need back boxers, because I have NO little area to work with, I was thinking about gluing MLV around the sides, and then basically fashioning a coffee can around the speakers, and then a bead of GG seal around the end of the spaekers.
> 
> 
> My third thought is using a 14" PVC tube, cut to length, with 2 layers of MLV surrounding the speaker. I would sand flat the two sides of the tube that would butt up against the joists, because obviously a speaker rubbing the joists breaks the de-coupling.
> 
> Any thoughts team?


My first thought it looks sealed and is better then normal ceiling speakers, but you could still make a one layer box I bet and that wouldn't hurt to do and better then non.


----------



## Kezzbot

The basement of our house is 2. 4 metre from floor to joist and in which I am going to start building internal walls for a new home theatre. Obviously I don't want any sound travelling through to the above floor especially bass, but I also don't want to lose too much height.
even though I haven't heard anyone else doing this before, I was planning on cutting out pieces of plasterboard and gluing, screwing and caulking these peices to the underside of the above hardwood floor in between the joists. I could do two layers of plasterboard in this way and one layer as the ceiling to the theatre room which would make 3 layers of plasterboard in total. 

What do you think of soundproofing against bass in this way?


----------



## HT Geek

policy said:


> I need the braintrust's help here. I purchased these speakers: https://www.klipsch.com/products/ks-7502-thx-in-ceiling-speaker which are 13.25" wide. My joist openings are 14" across at the bottom of the Boise Pacific I-Beam which my engineer says I CANNOT notch (I have 15" in between the particle board joists). So I am pretty much SOL on backer boxes.
> 
> So the first thing: These speakers are sealed on the back, by a pretty flimsy plastic housing. Do I NEED backer boxes?


Ideally, yes to backer boxes. Let's please clarify the exact issue. 


Cannot notch I-Beams. Check. That would be a very bad idea.
You have 14" opening and a 13-1/4" wide object
Net you have 3/4" space to fit something on the sides of the speaker

Is that all correct? 

What is the width of the speaker if you remove the plastic housing?




> Second, if I do need back boxers, because I have NO little area to work with, I was thinking about gluing MLV around the sides, and then basically fashioning a coffee can around the speakers, and then a bead of GG seal around the end of the spaekers.
> 
> 
> My third thought is using a 14" PVC tube, cut to length, with 2 layers of MLV surrounding the speaker. I would sand flat the two sides of the tube that would butt up against the joists, because obviously a speaker rubbing the joists breaks the de-coupling.
> 
> Any thoughts team?


So, you're thinking, "Can I manufacture a better case around the speaker than the one it came with?"

Well, I'm contemplating your options for a backer box, but quite frankly it seems as if you're likely to have coupling issues either way given the lack of room. I have two preliminary thoughts:


Don't use those speakers (preferred option)
Apply concrete backer board around the cavity where the speaker will be placed

To secure it in place, what will you attach the speaker to? How are you measuring the diameter? Plastic lip edge to edge or physical speaker (sans plastic lip) edge to edge? If you install with that plastic lip/backing on, you will need clearance for the clips to maneuver. I can't imagine that will be possible if the whole thing is sandwiched in between two I-beams unless you're going to lower your entire ceiling so there's clearance for the clips to function properly.


----------



## HT Geek

Kezzbot said:


> The basement of our house is 2. 4 metre from floor to joist and in which I am going to start building internal walls for a new home theatre. Obviously I don't want any sound travelling through to the above floor especially bass, but I also don't want to lose too much height.
> even though I haven't heard anyone else doing this before, I was planning on cutting out pieces of plasterboard and gluing, screwing and caulking these peices to the underside of the above hardwood floor in between the joists. I could do two layers of plasterboard in this way and one layer as the ceiling to the theatre room which would make 3 layers of plasterboard in total.
> 
> What do you think of soundproofing against bass in this way?


What you're describing is similar to this design.

Your idea will help mitigate bass travelling to the floor above, but the crucial factor is decoupling the ceiling in your HT room. If you don't do that in addition to your idea, I fear you'll be disappointed with the end result.


----------



## Ladeback

Kezzbot said:


> The basement of our house is 2. 4 metre from floor to joist and in which I am going to start building internal walls for a new home theatre. Obviously I don't want any sound travelling through to the above floor especially bass, but I also don't want to lose too much height.
> even though I haven't heard anyone else doing this before, I was planning on cutting out pieces of plasterboard and gluing, screwing and caulking these peices to the underside of the above hardwood floor in between the joists. I could do two layers of plasterboard in this way and one layer as the ceiling to the theatre room which would make 3 layers of plasterboard in total.
> 
> What do you think of soundproofing against bass in this way?


Yes this normal for soundproofing and there are some build threads here that have done this. What you are doing is adding mass to between the joist which will help slow down the base, but it is hard to stop all bass and it depends on how many sub, size and power you are talking. You also dont want to just use glue, you want to use Green Blue if you can get it. It has adds another layer to helping with mass and soundproofing. 

You also need to think about the walls as well. If you don't decouple them and add mass to them the sound will just go out around what you did to the ceiling and travel up through those walls and rooms around them.

I suggest checking out this website to learn more about soundproofing.

http://www.soundproofingcompany.com/soundproofing-solutions/


----------



## HT Geek

dellhop said:


> Got it. I'll work on the floor plan. I wondered if one would be desired as I'm not looking for the best solution, but more what would be worth doing with all the week points. I'll try to draw up the plan. Thanks.
> 
> Edit. Here's what i could come up with for floor plan. Hope it usable
> 
> The top blue line is the electrical I mentioned and the bottom is the water shut off. The red square is the bulk head and the yellow is the proposed wall.





dellhop said:


> I'm sorry if these questions have been covered but its been a while since I builT my theater room and a lot has happened since then.
> 
> When I built my theater I did not sound proof due to cost and the size of the room. I was not concerned with sound proofing since typically everyone in the house would be together in the room at the time. 10 years later though my kids are 10 and 12, getting into gaming and there own things. I will be converting my theater into a multipurpose gaming/movie/hang out. As such I need to move my office out of the room (it was in the corner and again wasn't an issue since I wouldn't be working if we were watching a movie).
> 
> My theater/variety room takes up half the basement of my standard colonial (center stair case). All the mechanical is on the half. I want to add a new office to about 2/5 of that unfinished section and want to sound proof it to some extent so that the kids can be in the theater area and I can still either work, play or stream with out to much interference. I'm not too worried about low end dampening as movies being watched while I'm not in there will be few. I'm more concerned with voices, laughter and jumping around noises. Here's are the sources or issues I think I have to deal with.
> 
> 1. Limiting the sounds I mentioned above, kids playing, laughing and occasionally screaming
> 2. The section I will build has concrete half walls with two windows, one on each side of the exterior
> 3. Bulkhead
> 4. HVAC blower, furnace in the last bit of unfinished area
> 5. Drains and water feeds below the joists in the ceiling.
> 6. over-sized hollow core door to theater area
> 7. Hose shut off that needs access (so some form of box added that can be opened to reach valve)
> 8. Potential access to electric junction box.
> 
> I've read through and understand sounds proofing and its requirements when you build a new theater with no windows and limited access. But is there any way to dampen most sounds to the point where head set mics and/or the right type of microphone (podcasts and streaming) won't pick up with all the above issues existing? Again not looking to create a black hole of sound, but enough that normal everyday life doesn't intrude.
> 
> Sorry if this is all over the place and I appreciate all the insight available. Thanks.


Please clarify a few points. Are my interpretations below, correct?


Your HT room is not represented on this diagram
The diagram shows an area that is currently unfinished
You wish to sub-divide this unfinished area
The portion on the right (10x17 floor) will be your new office
The portion on the left will remain unfinished
You wish to soundproof the area on the right
Where is your staircase? Is that the object in the lower left, or bottom of the left side of the diagram?


----------



## policy

HT Geek said:


> Ideally, yes to backer boxes. Let's please clarify the exact issue.
> 
> 
> Cannot notch I-Beams. Check. That would be a very bad idea.
> You have 14" opening and a 13-1/4" wide object
> Net you have 3/4" space to fit something on the sides of the speaker
> 
> Is that all correct?
> 
> What is the width of the speaker if you remove the plastic housing?
> 
> 
> 
> 
> So, you're thinking, "Can I manufacture a better case around the speaker than the one it came with?"
> 
> Well, I'm contemplating your options for a backer box, but quite frankly it seems as if you're likely to have coupling issues either way given the lack of room. I have two preliminary thoughts:
> 
> 
> Don't use those speakers (preferred option)
> Apply concrete backer board around the cavity where the speaker will be placed
> 
> To secure it in place, what will you attach the speaker to? How are you measuring the diameter? Plastic lip edge to edge or physical speaker (sans plastic lip) edge to edge? If you install with that plastic lip/backing on, you will need clearance for the clips to maneuver. I can't imagine that will be possible if the whole thing is sandwiched in between two I-beams unless you're going to lower your entire ceiling so there's clearance for the clips to function properly.



The housing is not detachable. Klipsch speakers (at least these ones) have some sort of electrical speaker control mechanism built in, and I believe that it cannot be exposed to detritus/dust, so I am limited. The width is the plastic housing, not the lip. The lip is wider by about 1/4".


My current plan is this:


Bore out a 14" PVC pipe .5" (The ID of a 14" PVC pipe is 13.07"), cap it with 2 layers of 1/2" thick PVC, then a bead of acoustical sealant inside the cylinder, and a bead of acoustical sealant around the end of the cap that meets the OSB which makes up the first layer of my ceiling. 



My ceiling is OSB--->5/8--->GG---->5/8 (2"), and apparently the way that this speaker attaches is that those flanges sandwich the speaker to the drywall, so I plan to put ANOTHER bead of acoustical sealant around the lip.


I plan to attach the cylinders to the back of the OSB with 90 degree brackets, then dremel the interior hole out.

Thoughts?


----------



## dellhop

HT Geek said:


> Please clarify a few points. Are my interpretations below, correct?
> 
> 
> Your HT room is not represented on this diagram
> The diagram shows an area that is currently unfinished
> You wish to sub-divide this unfinished area
> The portion on the right (10x17 floor) will be your new office
> The portion on the left will remain unfinished
> You wish to soundproof the area on the right
> Where is your staircase? Is that the object in the lower left, or bottom of the left side of the diagram?


You are correct on all accounts. The blob on the bottom left is the stair case. You access from the left, walking up to the right. 

Also to clarify a little, I'm not trying to sound proof to the level desired for a HT (assuming there are such distinctions) but for everyday house sound and potential for 5 kids in the HT doing what kids do. 

THANKS!


----------



## HT Geek

policy said:


> The housing is not detachable. Klipsch speakers (at least these ones) have some sort of electrical speaker control mechanism built in, and I believe that it cannot be exposed to detritus/dust, so I am limited. The width is the plastic housing, not the lip. The lip is wider by about 1/4".


Ok. I took a closer look at the photo. 

It still seems to me you'll need clearance for the plastic clips to move and engage in order to secure the speaker. Let's say you've got your hole cut out in the ceiling between two I-beams. You shove the speaker up in there and try to turn the screws to rotate those plastic clips. They won't be able to fully rotate into position if you have insufficient clearance for the plastic clips inside the ceiling to rotate into place. Does that make sense? 

Point is you will need a minimum clearance in width between the I-beams of the diameter of the speaker that _includes_ the lip. If the lip is only 1/4" (which would be a rather narrow clip width, btw) you're talking 1/2" additional diameter.




> My current plan is this:
> 
> 
> Bore out a 14" PVC pipe .5" (The ID of a 14" PVC pipe is 13.07"), cap it with 2 layers of 1/2" thick PVC, then a bead of acoustical sealant inside the cylinder, and a bead of acoustical sealant around the end of the cap that meets the OSB which makes up the first layer of my ceiling.
> 
> 
> 
> My ceiling is OSB--->5/8--->GG---->5/8 (2"), and apparently the way that this speaker attaches is that those flanges sandwich the speaker to the drywall, so I plan to put ANOTHER bead of acoustical sealant around the lip.
> 
> 
> I plan to attach the cylinders to the back of the OSB with 90 degree brackets, then dremel the interior hole out.
> 
> Thoughts?


Gotcha. It seems to me that would work. So, basically the angle brackets would secure the speaker, from the inside of the ceiling?


----------



## HT Geek

dellhop said:


> You are correct on all accounts. The blob on the bottom left is the stair case. You access from the left, walking up to the right.
> 
> Also to clarify a little, I'm not trying to sound proof to the level desired for a HT (assuming there are such distinctions) but for everyday house sound and potential for 5 kids in the HT doing what kids do.
> 
> THANKS!


Alright. A few more questions:



Where is the HT room in relation to the room to-be-built on the right side of the diagram? Is it below/South of the to-be-built home office? Is that door in the SE quadrant of the diagram facing South leading to the HT room?
Is this area a daylight basement, with 1/2 the room submerged underground 1/2 above ground?
How does one access the staircase? I don't see any doors on the left side of the diagram.
Which way do your ceiling joists run?
What is the unfinished height of the future office area?
What room is above the future office area?


----------



## dellhop

HT Geek said:


> Alright. A few more questions:
> 
> 
> 
> Where is the HT room in relation to the room to-be-built on the right side of the diagram? Is it below/South of the to-be-built home office? Is that door in the SE quadrant of the diagram facing South leading to the HT room?
> Is this area a daylight basement, with 1/2 the room submerged underground 1/2 above ground?
> How does one access the staircase? I don't see any doors on the left side of the diagram.
> Which way do your ceiling joists run?
> What is the unfinished height of the future office area?
> What room is above the future office area?


Where is the HT room in relation to the room to-be-built on the right side of the diagram? Is it below/South of the to-be-built home office? Is that door in the SE quadrant of the diagram facing South leading to the HT room? -* Added a more detailed floor plan. Apologies for simplifying originally*. 

Is this area a daylight basement, with 1/2 the room submerged underground 1/2 above ground? - *Only the section I want to finish now is daylight. I've indicated with yellow the extent of the half concrete wall (have below/half above ground)*

How does one access the staircase? I don't see any doors on the left side of the diagram. - *Added to the floor plan*. 

Which way do your ceiling joists run? *North to South*

What is the unfinished height of the future office area? - *From joists to floor is 7'10". Pipes extend 3-4" below the joists in some places. Septic pipe runs lower but its close to wall and ifgured would wrap in a soffit.*

What room is above the future office area? *From top to bottom laundry room, bathroom, part of kitchen (cabinets and stove).*










Yellow bottom left is screen, red L-shape is count, black squares are posts, black fan lines are speakers, red arrow is direction up stairs.


----------



## policy

HT Geek said:


> Ok. I took a closer look at the photo.
> 
> It still seems to me you'll need clearance for the plastic clips to move and engage in order to secure the speaker. Let's say you've got your hole cut out in the ceiling between two I-beams. You shove the speaker up in there and try to turn the screws to rotate those plastic clips. They won't be able to fully rotate into position if you have insufficient clearance for the plastic clips inside the ceiling to rotate into place. Does that make sense?
> 
> Point is you will need a minimum clearance in width between the I-beams of the diameter of the speaker that _includes_ the lip. If the lip is only 1/4" (which would be a rather narrow clip width, btw) you're talking 1/2" additional diameter.
> 
> 
> 
> 
> Gotcha. It seems to me that would work. So, basically the angle brackets would secure the speaker, from the inside of the ceiling?


The angle brackets will secure the PVC cylinder to the back of the OSB (Top layer of drawing). The Klipsch support people said that there is 2" of clearance between the lip and the "dogs" so that it should be able to clamp, I just need enough space inside the cylinder to let it clamp on, there are 4 of them, so if I have 1/2" on each of the sides, along with the bead of GG sealant, I feel pretty secure. Obviously if I lose the airtight nature of the seal, it's all for not, and I think that the double airtight nature is solid. I plan to do a demo run just in the pre-cut OSB, to make sure I do in fact have 2" of clearance. The screws can be replaced, much like in an adjustable J-Box, should I not have enough clearance.


----------



## HT Geek

policy said:


> The angle brackets will secure the PVC cylinder to the back of the OSB (Top layer of drawing). The Klipsch support people said that there is 2" of clearance between the lip and the "dogs" so that it should be able to clamp, I just need enough space inside the cylinder to let it clamp on, there are 4 of them, so if I have 1/2" on each of the sides, along with the bead of GG sealant, I feel pretty secure. Obviously if I lose the airtight nature of the seal, it's all for not, and I think that the double airtight nature is solid. I plan to do a demo run just in the pre-cut OSB, to make sure I do in fact have 2" of clearance. The screws can be replaced, much like in an adjustable J-Box, should I not have enough clearance.


Ok. So, just to be clear.... Will it be the screws penetrating the PVC sleeve that prevent gravity from pulling down on the speaker inside the PVC sleeve?

And how will you access the speaker if you need to replace it for any reason?

EDIT: I just re-read your last comment (above). So, I'm not following your thought-pattern on the "dogs" / i.e. rotating clips of the speaker. Just to be clear on this, you're saying there's 2" required of vertical clearance above the inside of the lip to support the rotation of the clips?

Obviously, in a normal installation they would clip onto the back of the drywall, and you'll have 2x OSB + 1/8" maximum for the GG in between (likely closer to 1/16"). Is that 2" the maximum height of those dog ears or the maximum thickness of material they can clamp onto (i.e. between interior of lip and maximum extension of clip)?

IIRC, your lip is outside the width of the opening between your I-Beams, unless I misunderstood or my memory is failing.

Are you sure this whole contraption will fit in between the I-Beams, allow insertion of the speaker into the PVC sleeve, and then allow you to rotate the clips and secure the speaker? What I'm struggling with visualizing is how the rotating clips will be able to move freely and be able to grab onto anything. I thought the issue was there's not a large enough space between the I-Beams to allow that to happen.


----------



## HT Geek

dellhop said:


> Where is the HT room in relation to the room to-be-built on the right side of the diagram? Is it below/South of the to-be-built home office? Is that door in the SE quadrant of the diagram facing South leading to the HT room? -* Added a more detailed floor plan. Apologies for simplifying originally*.
> 
> Is this area a daylight basement, with 1/2 the room submerged underground 1/2 above ground? - *Only the section I want to finish now is daylight. I've indicated with yellow the extent of the half concrete wall (have below/half above ground)*
> 
> How does one access the staircase? I don't see any doors on the left side of the diagram. - *Added to the floor plan*.
> 
> Which way do your ceiling joists run? *North to South*
> 
> What is the unfinished height of the future office area? - *From joists to floor is 7'10". Pipes extend 3-4" below the joists in some places. Septic pipe runs lower but its close to wall and ifgured would wrap in a soffit.*
> 
> What room is above the future office area? *From top to bottom laundry room, bathroom, part of kitchen (cabinets and stove).*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Yellow bottom left is screen, red L-shape is count, black squares are posts, black fan lines are speakers, red arrow is direction up stairs.


Ok. Thanks. Now I've got a better idea/picture of the scenario. 

So, a few thoughts....



Without knowing which state/locality you reside in, generally speaking 7' finished ceiling will be your minimum height
I'd suggest at a minimum soundproofing the shared wall to the "south" of the new office area and the ceiling, since your joists run north/south
Beef up the shared door with a solid core
Build a partial room-within-a-room, including independent ceiling joists in the office. You would need to either stagger them from the original (less than ideal) or run a new ceiling perpendicular to the structural/original ceiling and attach to the original with clips for support (preferred)
Your room will be narrow enough you could use 2x4's if you wanted for the new ceiling joists and minimize your height drop to 4 to 4-1/2" depending on the size of your air gap above to the structural joists.
Some municipalities/states measure "finished height" of a room sans flooring material and some measure it during the final inspection. If the latter and you install carpet, if it's a close call, make sure the inspector measures next to his/her feet where the carpet and pad will be compressed slightly.

If you want to consider using 2x4's for ceiling joists, I can run the engineering calcs for you if you like to tell you how far apart their max spread could be. Also realize you will have a greater risk of ceiling deflection versus using 2x6's, and it's tough to find straight 2x4's these days. Your best bet would be to purchase engineered 2x4's, such as Glulams. They will be straight and strong and you will have no deflection issues if installed properly and within sufficient offset parameters (distance on-center between each joist). 

btw, don't be concerned about that last comment. It's a lot easier to figure out than it sounds and really not a big deal. My point is: use the best materials for the job. 

Place insulation ("pink fluffy") in the ceiling joist areas. Use double stud or clips & channel on the shared wall w/the HT room. Carpet and pad on the floor.

You should consider soundproofing the other 2 walls with clips & channel, staggered stud, or double stud. One reason why is because you don't know what the future holds. Easier and less $ to do it now versus retrofit later.


----------



## HT Geek

dellhop said:


> When I built my theater I did not sound proof due to cost and the size of the room. I was not concerned with sound proofing since typically everyone in the house would be together in the room at the time. 10 years later though my kids are 10 and 12, getting into gaming and there own things.


btw, I also wanted to advise you... speaking from experience... if you have boys, don't underestimate their interest in testing the limits of your theater's subwoofers when they get to be about 15. I suggest planning accordingly. Just sayin'.


----------



## dellhop

HT Geek said:


> Ok. Thanks. Now I've got a better idea/picture of the scenario.
> 
> So, a few thoughts....
> 
> 
> 
> Without knowing which state/locality you reside in, generally speaking 7' finished ceiling will be your minimum height
> I'd suggest at a minimum soundproofing the shared wall to the "south" of the new office area and the ceiling, since your joists run north/south
> Beef up the shared door with a solid core
> Build a partial room-within-a-room, including independent ceiling joists in the office. You would need to either stagger them from the original (less than ideal) or run a new ceiling perpendicular to the structural/original ceiling and attach to the original with clips for support (preferred)
> Your room will be narrow enough you could use 2x4's if you wanted for the new ceiling joists and minimize your height drop to 4 to 4-1/2" depending on the size of your air gap above to the structural joists.
> Some municipalities/states measure "finished height" of a room sans flooring material and some measure it during the final inspection. If the latter and you install carpet, if it's a close call, make sure the inspector measures next to his/her feet where the carpet and pad will be compressed slightly.
> 
> If you want to consider using 2x4's for ceiling joists, I can run the engineering calcs for you if you like to tell you how far apart their max spread could be. Also realize you will have a greater risk of ceiling deflection versus using 2x6's, and it's tough to find straight 2x4's these days. Your best bet would be to purchase engineered 2x4's, such as Glulams. They will be straight and strong and you will have no deflection issues if installed properly and within sufficient offset parameters (distance on-center between each joist).
> 
> btw, don't be concerned about that last comment. It's a lot easier to figure out than it sounds and really not a big deal. My point is: use the best materials for the job.
> 
> Place insulation ("pink fluffy") in the ceiling joist areas. Use double stud or clips & channel on the shared wall w/the HT room. Carpet and pad on the floor.
> 
> You should consider soundproofing the other 2 walls with clips & channel, staggered stud, or double stud. One reason why is because you don't know what the future holds. Easier and less $ to do it now versus retrofit later.


Wow! This is all fantastic. There's so much info on here and I really appreciate the summary of needs. Have to research the independent ceiling joists and how that is all constructed, but I know there are plenty of threads already addressing this. You covered exactly what I needed to understand the scope of what is required. Thank you very much.

I'll work on the details and take you up on the engineering calc offer. Thank you again. 



> btw, I also wanted to advise you... speaking from experience... if you have boys, don't underestimate their interest in testing the limits of your theater's subwoofers when they get to be about 15. I suggest planning accordingly. Just sayin'.


Excellent point! 

I'll be back


----------



## ambesolman

HT Geek said:


> Build a partial room-within-a-room, including independent ceiling joists in the office. You would need to either stagger them from the original (less than ideal) or run a new ceiling perpendicular to the structural/original ceiling and attach to the original with clips for support (preferred)


How would these attach at 90deg angles to the originals? I'll have to lower my height as well due to new conduits and existing junk below my joists.




> [*]Your room will be narrow enough you could use 2x4's if you wanted for the new ceiling joists and minimize your height drop to 4 to 4-1/2" depending on the size of your air gap above to the structural joists.



How narrow to do this?




> If you want to consider using 2x4's for ceiling joists, I can run the engineering calcs for you if you like to tell you how far apart their max spread could be.


I'd be interested in this too if you don't mind



> Also realize you will have a greater risk of ceiling deflection versus using 2x6's


Would you please elaborate on this?



> Your best bet would be to purchase engineered 2x4's, such as Glulams. They will be straight and strong and you will have no deflection issues if installed properly and within sufficient offset parameters (distance on-center between each joist).



Do these essentially look like small wooden i beams? Know how much these run by chance? Would you have to get them from a lumber yard? Don't see them at HD.

Also, I finally responded to your forever old post in my build thread




Sent using Tapatalk cuz the mobile version is still


----------



## jrref

I have an interesting problem that maybe someone here has the answer.

I'm finishing my basement, sheetrock, etc.. but just using it for a playroom, not a home theater. I live in an attached town home and one side is the common wall with my neighbor. Fortunately, the common wall is poured concrete with a wood truss system sits on top of that structure.

When my neighbor plays loud music in his basement I hear it and I believe it's mostly coming through the rim joists. Currently I have pink insulation in this area. I'm not planning on soundproofing the basement but I want a way to lessen the sound transmission from my neighbor's basement.

Is there a way to use soundproof sheetrock in the rim joists? Since I have a truss structure holding up the upper floors I can't see a way to use it except cut a piece of soundproof sheetrock and screw and or glue it to the wood rim joist then fill the rest of the cavity with insulation.

If this is ok, should i put insulation in the rim joist cavity then try to cap the gap with the sheetrock?

Please note that along this 30 foot common wall, 1/2 of it, i'll be closing the ceining and the other half is a work room where i don't plan on closing the ceiling, thus the need to try and cap off the rim joists.

Any ideas?

Thanks in advance, John


----------



## Ladeback

jrref said:


> I have an interesting problem that maybe someone here has the answer.
> 
> I'm finishing my basement, sheetrock, etc.. but just using it for a playroom, not a home theater. I live in an attached town home and one side is the common wall with my neighbor. Fortunately, the common wall is poured concrete with a wood truss system sits on top of that structure.
> 
> When my neighbor plays loud music in his basement I hear it and I believe it's mostly coming through the rim joists. Currently I have pink insulation in this area. I'm not planning on soundproofing the basement but I want a way to lessen the sound transmission from my neighbor's basement.
> 
> Is there a way to use soundproof sheetrock in the rim joists? Since I have a truss structure holding up the upper floors I can't see a way to use it except cut a piece of soundproof sheetrock and screw and or glue it to the wood rim joist then fill the rest of the cavity with insulation.
> 
> If this is ok, should i put insulation in the rim joist cavity then try to cap the gap with the sheetrock?
> 
> Please note that along this 30 foot common wall, 1/2 of it, i'll be closing the ceining and the other half is a work room where i don't plan on closing the ceiling, thus the need to try and cap off the rim joists.
> 
> Any ideas?
> 
> Thanks in advance, John


So there is wood between the trusses on top of The concrete wall? If so, I would like you said put drywall in that area, but also use Green Blue and at least 2 layers. You may want to do the same to ceiling above between the trusses if the rim joist area isn't enough. You could then add pink insulation in the ceiling before drywall goes up. I think that would help. Try one layer of drywall first to see what it does. If it is enough you may not need the second layer. 

When I lived in my duplex that I now rent and hard my first home theater my neighbors complained mostly about the base and it shaking the walls. You could build a wall that is decoupled from the ceiling with an inch of Styrofoam insulation and one inch air gap. Then add DDW/TH to the wall. That's more work, but follows the three parts of soundproofing, decouple, mass and absorption.


----------



## jrref

Thanks,
So just to clarify, there is wood at the end of the rim joist. Is it better to put the drywall against that wood then insulation or put insulation in and then try to glue in the drywall? The first is easiest but i'm not sure is there will be any difference between the two methods.


----------



## Ladeback

jrref said:


> Thanks,
> So just to clarify, there is wood at the end of the rim joist. Is it better to put the drywall against that wood then insulation or put insulation in and then try to glue in the drywall? The first is easiest but i'm not sure is there will be any difference between the two methods.


It would be better to put the drywall and green glue first for mass then pink fluffy or Roxul. You could try one layer first to see if that is enough to help.

Sorry didn't respond soon,I have been taking a break from social media and online forums for a bit.


----------



## HT Geek

ambesolman said:


> How would these attach at 90deg angles to the originals? I'll have to lower my height as well due to new conduits and existing junk below my joists.


Good point. I must have been tired when I wrote that. Lol.  Though it is possible to attach perpendicular joists below the originals. It's a question of how the clips are mounted, though it normally requires using blocks.

It's been almost 2 weeks since I've had time to be on the forums, but I believe what I meant/should have said is you could stagger with clips or run new joists perpendicular and below the original joists. But however you do it, you should plan on some attachments via clips to the structural joists, just to help maintain rigidity.




> How narrow to do this?


I'd have to dig up my structural calculator to give you exact figures, but speaking off-the-cuff, a 12' span absolute maximum, and that is with tolerating max deflection in your ceiling. Probably looking at around 12" O.C. joist span.

The Glulams would help you reduce the deflection risk.



> I'd be interested in this too if you don't mind
> 
> Would you please elaborate on this?


No prob. It may take me a couple of days to find time and post back results.



> Do these essentially look like small wooden i beams? Know how much these run by chance? Would you have to get them from a lumber yard? Don't see them at HD.


You definitely will not find them at H.D. or any other big box stores. You will have to get them from a true lumber yard, but they're common. 

No, not I-Beams. They are engineered wood beams. "Glulam" is a manufacturer/brand name, but the term tends to be commonly known because these engineered beams are all basically pressed and glued bits of wood. They are engineered to be straighter and stronger than most naturally occurring wood beams. They are not very expensive (relatively speaking), but the prices change from time-to-time. You'd likely need to call lumber yards to get quotes.

In a nutshell, try to think like a contractor and not a homeowner. 

The old-school approach of making phone calls and negotiating will yield you a better result vs. shopping at the Big Box consumer stores.





> Also, I finally responded to your forever old post in my build thread


LoL. Do you happen to have a link handy? If not, I'll see if I can backtrack to it.


----------



## HT Geek

*Now, I'm awake enough to elaborate. *



ambesolman said:


> I'd be interested in this too if you don't mind
> 
> Would you please elaborate on this


Context of my original comment and your response isn't captured above, so let's re-cap and allow me to clarify a few important factors.


IIRC, your ceiling span will be ~10 feet or so. Is that correct?
You can safely go up to about 12 feet *maximum* span with 2x4 ceiling joists, but it is usually frowned upon for several reasons
Why? Deflection, crap material, cost, time. I'll explain these below.

Deflection is basically how much deviation you get from a perfectly flat surface. Unless you're using steel studs as joists, virtually no wood ceiling has zero deflection from one end of the room to the other. However, our human eyes are not good at seeing it (thankfully) unless your field of view is very close to the ceiling (short room) and/or the deflection is extreme. The smaller the room, the more likely you are to notice it, but only if you're really looking for it unless it's extreme.

Building codes put a cap on the maximum deflection a ceiling or even a wall can have. That has more to do with structural support than aesthetics, but as homeowners we're concerned with both. One advantage you have - of a sort - is the load above the ceiling will be zero, other than the weight of the wood itself. All this ceiling would do is hold up your drywall/ceiling in the room and anything attached to it such as light fixtures. 

So, that is deflection. I also mentioned crap materials, cost, and time. Well, if you have ventured into the lumber section of a Home Depot, Lowe's, or similar store in the last 10 years or so you might have noticed lumber isn't what it used to be. Good luck finding enough straight 2x4's to build your walls and ceiling without spending a couple of hours sorting through all the crap wood that is warped beyond one's preferences (at least beyond mine). And good luck hiring a contractor who will do that. Most of them want to spend as little time as possible in the store and they will load up a little extra, take it all to the job site, and sort it out later. Some of the junk will end up building your room.

Aside from saving time at the Big Box store, most contractors also don't want to take the extra time nor work with the extra materials to create a ceiling with 2x4's unless the room is very small. In order to get around the deflection problem, using thinner wood means you need more of it, spaced closer together. So, for instance you might need a joist every 12" on-center (o.c.) versus 16", 19.2" or 24", which are standard widths apart. If you used thicker wood, you could space them further apart, thus requiring fewer materials and less time.

So, you're talking more cost in labor and possibly materials (2x4's are cheaper than 2x6's for example) to shave 2" of height.

My comment on Glulams or engineered beams was to explain a good method of getting around the crap materials problem. Engineered wood is _straight_ and strong. It will have greater support capabilities and you can stretch longer distances with it because of its strength. It also resists deflection better than most natural wood products.

Now, having explained all that, here is the kicker: If you want to pursue this route, you will need to gather the following information before making any purchase, so you can calculate the viability of the project:


Where you can puchase engineered wood 2x4's locally
Cost including delivery
Physical properties (from the manufacturer)

The last item is the key from my perspective. I need to know the following:


Wood species (e.g. Southern Yellow Pine or SYP)
Visual Grade (e.g. No. 2); sometimes called the Wood Group
_fb_: bending resistance, expressed as psi (Pounds per Square Inch)
_E_: Modulus of Elasticity

You will find that information from the manufacturer.

From that I can calculate the permitted load and maximum span (ceiling width) based on various sizes of joists. It's a complex calculation that is based on not just the wood properties, but also factors found in various portions of national building codes.

I've attached two documents to help steer you in the right direction. One explains common wood markings. It is not all encompassing, but may be helpful. If you go with engineered wood it won't be relevant. You must get the info from the manufacturer. If you buy wood off the shelf, I would use a reference guide (such as the other doc attached to this post) to determine the pertinent engineering values. The most important thing to know is you must evaluate the capabilities of potential materials before you commit.


----------



## HT Geek

jrref said:


> I have an interesting problem that maybe someone here has the answer.
> 
> I'm finishing my basement, sheetrock, etc.. but just using it for a playroom, not a home theater. I live in an attached town home and one side is the common wall with my neighbor. Fortunately, the common wall is poured concrete with a wood truss system sits on top of that structure.
> 
> When my neighbor plays loud music in his basement I hear it and I believe it's mostly coming through the rim joists. Currently I have pink insulation in this area. I'm not planning on soundproofing the basement but I want a way to lessen the sound transmission from my neighbor's basement.
> 
> Is there a way to use soundproof sheetrock in the rim joists? Since I have a truss structure holding up the upper floors I can't see a way to use it except cut a piece of soundproof sheetrock and screw and or glue it to the wood rim joist then fill the rest of the cavity with insulation.
> 
> If this is ok, should i put insulation in the rim joist cavity then try to cap the gap with the sheetrock?
> 
> Please note that along this 30 foot common wall, 1/2 of it, i'll be closing the ceining and the other half is a work room where i don't plan on closing the ceiling, thus the need to try and cap off the rim joists.


Hi John.

I'm trying to fathom exactly where you are at this moment in the "finishing the basement" process. I presume you've already got a stud wall along that common wall, and you just want to know if there's any point in adding sound proofing materials in the cavity between the rim joist and top of your wall studs. Is that right?

If so, that's kind of a tough call as you might also have some flanking coming in via the edge of your floor in the room above. I'd imagine it's going to be very difficult to tell the difference between that and sound actually coming through the rim joist. But, no matter... I don't disagree with @Ladeback's comments. It's possible adding mass to your rim joist could help mitigate both issues. I don't see how it could harm anything. I suppose it boils down to how much effort you are willing to put into it. Since your workroom area will be at least partially open/unfinished, I tend to lean toward making the effort. 

There are other methods you could employ, but you'd be sacrificing real estate to de-couple and without finishing off the whole area it's not worth it unless you wanted to isolate just the playroom area. Either way, your approach seems reasonable and won't have a negative impact.


----------



## jrref

^^^
Right, so i'm trying to add sound proofing materials in the cavity between the rim joist and the top of the wall studs. I know it's not going to be perfect but just want to attenuate it as best as possible. Thanks for the advice.
John


----------



## ambesolman

HT Geek said:


> Good point. I must have been tired when I wrote that. Lol.  Though it is possible to attach perpendicular joists below the originals. It's a question of how the clips are mounted, though it normally requires using blocks.
> 
> It's been almost 2 weeks since I've had time to be on the forums, but I believe what I meant/should have said is you could stagger with clips or run new joists perpendicular and below the original joists. But however you do it, you should plan on some attachments via clips to the structural joists, just to help maintain rigidity.
> 
> 
> 
> 
> I'd have to dig up my structural calculator to give you exact figures, but speaking off-the-cuff, a 12' span absolute maximum, and that is with tolerating max deflection in your ceiling. Probably looking at around 12" O.C. joist span.
> 
> The Glulams would help you reduce the deflection risk.
> 
> 
> 
> No prob. It may take me a couple of days to find time and post back results.
> 
> 
> 
> You definitely will not find them at H.D. or any other big box stores. You will have to get them from a true lumber yard, but they're common.
> 
> No, not I-Beams. They are engineered wood beams. "Glulam" is a manufacturer/brand name, but the term tends to be commonly known because these engineered beams are all basically pressed and glued bits of wood. They are engineered to be straighter and stronger than most naturally occurring wood beams. They are not very expensive (relatively speaking), but the prices change from time-to-time. You'd likely need to call lumber yards to get quotes.
> 
> In a nutshell, try to think like a contractor and not a homeowner.
> 
> The old-school approach of making phone calls and negotiating will yield you a better result vs. shopping at the Big Box consumer stores.
> 
> 
> 
> 
> 
> LoL. Do you happen to have a link handy? If not, I'll see if I can backtrack to it.





HT Geek said:


> Context of my original comment and your response isn't captured above, so let's re-cap and allow me to clarify a few important factors.
> 
> 
> IIRC, your ceiling span will be ~10 feet or so. Is that correct?
> You can safely go up to about 12 feet *maximum* span with 2x4 ceiling joists, but it is usually frowned upon for several reasons
> Why? Deflection, crap material, cost, time. I'll explain these below.
> 
> Deflection is basically how much deviation you get from a perfectly flat surface. Unless you're using steel studs as joists, virtually no wood ceiling has zero deflection from one end of the room to the other. However, our human eyes are not good at seeing it (thankfully) unless your field of view is very close to the ceiling (short room) and/or the deflection is extreme. The smaller the room, the more likely you are to notice it, but only if you're really looking for it unless it's extreme.
> 
> Building codes put a cap on the maximum deflection a ceiling or even a wall can have. That has more to do with structural support than aesthetics, but as homeowners we're concerned with both. One advantage you have - of a sort - is the load above the ceiling will be zero, other than the weight of the wood itself. All this ceiling would do is hold up your drywall/ceiling in the room and anything attached to it such as light fixtures.
> 
> So, that is deflection. I also mentioned crap materials, cost, and time. Well, if you have ventured into the lumber section of a Home Depot, Lowe's, or similar store in the last 10 years or so you might have noticed lumber isn't what it used to be. Good luck finding enough straight 2x4's to build your walls and ceiling without spending a couple of hours sorting through all the crap wood that is warped beyond one's preferences (at least beyond mine). And good luck hiring a contractor who will do that. Most of them want to spend as little time as possible in the store and they will load up a little extra, take it all to the job site, and sort it out later. Some of the junk will end up building your room.
> 
> Aside from saving time at the Big Box store, most contractors also don't want to take the extra time nor work with the extra materials to create a ceiling with 2x4's unless the room is very small. In order to get around the deflection problem, using thinner wood means you need more of it, spaced closer together. So, for instance you might need a joist every 12" on-center (o.c.) versus 16", 19.2" or 24", which are standard widths apart. If you used thicker wood, you could space them further apart, thus requiring fewer materials and less time.
> 
> So, you're talking more cost in labor and possibly materials (2x4's are cheaper than 2x6's for example) to shave 2" of height.
> 
> My comment on Glulams or engineered beams was to explain a good method of getting around the crap materials problem. Engineered wood is _straight_ and strong. It will have greater support capabilities and you can stretch longer distances with it because of its strength. It also resists deflection better than most natural wood products.
> 
> Now, having explained all that, here is the kicker: If you want to pursue this route, you will need to gather the following information before making any purchase, so you can calculate the viability of the project:
> 
> 
> Where you can puchase engineered wood 2x4's locally
> Cost including delivery
> Physical properties (from the manufacturer)
> 
> The last item is the key from my perspective. I need to know the following:
> 
> 
> Wood species (e.g. Southern Yellow Pine or SYP)
> Visual Grade (e.g. No. 2); sometimes called the Wood Group
> _fb_: bending resistance, expressed as psi (Pounds per Square Inch)
> _E_: Modulus of Elasticity
> 
> You will find that information from the manufacturer.
> 
> From that I can calculate the permitted load and maximum span (ceiling width) based on various sizes of joists. It's a complex calculation that is based on not just the wood properties, but also factors found in various portions of national building codes.
> 
> I've attached two documents to help steer you in the right direction. One explains common wood markings. It is not all encompassing, but may be helpful. If you go with engineered wood it won't be relevant. You must get the info from the manufacturer. If you buy wood off the shelf, I would use a reference guide (such as the other doc attached to this post) to determine the pertinent engineering values. The most important thing to know is you must evaluate the capabilities of potential materials before you commit.


Room width will be at least 14' before any new construction so it sounds like engineered is the only option. I'm getting quotes for replacing support poles with a beam so how expensive that is will determine room width, how to run hvac, power, etc..

Added a link to my sig for my build thread for ya


----------



## HT Geek

ambesolman said:


> Room width will be at least 14' before any new construction so it sounds like engineered is the only option. I'm getting quotes for replacing support poles with a beam so how expensive that is will determine room width, how to run hvac, power, etc..
> 
> Added a link to my sig for my build thread for ya


A 14' span is beyond the scope of 2x4 joists, even if you used engineered wood and sistered them into 4x4's. Even using 2x6's you'd probably require engineered joists at that distance. I can verify once the values I mentioned are available, but I would plan on 2x6 at a minimum for that span.

I also posted a couple questions in your build thread.


----------



## tamiya

Hi, Guys

The green glue clip installation video shows the wall become elastic when push.




What's the difference between a rigid wall(stagger stud) vs elastic wall(clip) on soundproofing?
I believe decoupling is the key to soundproofing but elastic(resilient) wall works better?

Is any clip result in elastic(resilient) wall or just the clip from green glue?


----------



## HT Geek

tamiya said:


> Hi, Guys
> 
> The green glue clip installation video shows the wall become elastic when push.
> https://youtu.be/8JD08i6jgLw
> What's the difference between a rigid wall(stagger stud) vs elastic wall(clip) on soundproofing?


When all other factors are equal, clip & channels will provide better performance. Exact differences you can expect in sound attenuation will depend on the details of what you are comparing.



> Is any clip result in elastic(resilient) wall or just the clip from green glue?


Any of the same type will be nearly identical in performance. By "type" I mean whether or not the clip includes rubber. Some clips are metal only. The clips with rubber will perform a bit better, but the key is the decoupling as you mentioned and both types do that.


----------



## tamiya

HT Geek said:


> When all other factors are equal, clip & channels will provide better performance. Exact differences you can expect in sound attenuation will depend on the details of what you are comparing.
> 
> 
> 
> Any of the same type will be nearly identical in performance. By "type" I mean whether or not the clip includes rubber. Some clips are metal only. The clips with rubber will perform a bit better, but the key is the decoupling as you mentioned and both types do that.


OK, how about ceilings? My ceiling is like this, no panel or subfloor in the attic. 
So there is no triple leaf effect by leaving existing ceiling alone, right?
And if weight is the issue can't do two layer of 5/8s, which one is better; adding one layer of 5/8 and GG to existing ceiling or clip & channel with one layer 5/8?


----------



## jjcook

tamiya said:


> OK, how about ceilings? My ceiling is like this, no panel or subfloor in the attic.
> So there is no triple leaf effect by leaving existing ceiling alone, right?
> And if weight is the issue can't do two layer of 5/8s, which one is better; adding one layer of 5/8 and GG to existing ceiling or clip & channel with one layer 5/8?


I'd vote for remove the existing ceiling drywall and hang two layers of drywall (ideally both 5/8 but even 5/8 + 1/2 for example would work) from clip & channel and green glue. This is what I am in process of doing for my room with truss attic above.


----------



## tamiya

jjcook said:


> I'd vote for remove the existing ceiling drywall and hang two layers of drywall (ideally both 5/8 but even 5/8 + 1/2 for example would work) from clip & channel and green glue. This is what I am in process of doing for my room with truss attic above.


Well, take out the ceiling drywall is a lot of work.
Don't know if I can salvage the ceiling drywall; if not then derbies to dispose of.
I'm exploring the benefit of just one more layer of 5/8 with GG directly to the existing ceiling worth the effort.
Haven't seen any STC number on putting one layer of 5/8 with GG anywhere.


----------



## Ladeback

tamiya said:


> Well, take out the ceiling drywall is a lot of work.
> Don't know if I can salvage the ceiling drywall; if not then derbies to dispose of.
> I'm exploring the benefit of just one more layer of 5/8 with GG directly to the existing ceiling worth the effort.
> Haven't seen any STC number on putting one layer of 5/8 with GG anywhere.


I found this on Soundproofing Company's website, but it calls for three layers of 5/8" drywall and green glue.

the reason i want to use clip & channel along with insulation and maybe some drywall with green glue between my food joist in my best is to mostly stop sound or footfall from coming from above more then sound getting out. The reason for clips and channel is decouple so sound doesn't travel up and maybe over to another room nearby. You will want to decouple the walls as well for the same reason. The extra layer of drywall with GG is mostly adding mass to the ceiling which should help some, but as good as with clips and channel.

http://www.soundproofingcompany.com/soundproof-ceilings/spc-1-soundproof-ceiling//


----------



## HT Geek

tamiya said:


> OK, how about ceilings? My ceiling is like this, no panel or subfloor in the attic.
> So there is no triple leaf effect by leaving existing ceiling alone, right?
> And if weight is the issue can't do two layer of 5/8s, which one is better; adding one layer of 5/8 and GG to existing ceiling or clip & channel with one layer 5/8?


Tough to tell for sure what you are showing here, but for the moment I'll presume it's top side of your ceiling, 1 sheet of drywall attached to 2x6 joists which are also supporting your roof struts.

You'd create a triple leaf if - inside your room - you added clips and channel over top of the existing drywall, and then 1 or more layers of drywall affixed to the clips & channel. So, as mentioned by others above, you should remove the existing ceiling/drywall FIRST and then install the clips/channel to the ceiling joists, then install new drywall. That is the proper method.

As you eluded above, yes it is a lot of work to demo the existing drywall. More work than most people anticipate if they have not done demo work before. However, there is a direct correlation between one's level-of-effort and the end result.

Weight (that you described) is not an issue for your joists. Use the clips & channel plus drywall. Preferably 2 sheets, but you could do just 1 if you like. It's not a weight issue with 2 layers. Your only weight-related issue will be of the clips themselves. Check the manufacturer's weight rating.


----------



## HT Geek

tamiya said:


> Haven't seen any STC number on putting one layer of 5/8 with GG anywhere.


Do you mean one layer of 5/8 + GG on top of existing drywall (i.e. a drywall sandwich) over studs (no clips & channel)?


----------



## tamiya

HT Geek said:


> Do you mean one layer of 5/8 + GG on top of existing drywall (i.e. a drywall sandwich) over studs (no clips & channel)?


Yes


----------



## jrref

HT Geek said:


> Hi John.
> 
> I'm trying to fathom exactly where you are at this moment in the "finishing the basement" process. I presume you've already got a stud wall along that common wall, and you just want to know if there's any point in adding sound proofing materials in the cavity between the rim joist and top of your wall studs. Is that right?
> 
> If so, that's kind of a tough call as you might also have some flanking coming in via the edge of your floor in the room above. I'd imagine it's going to be very difficult to tell the difference between that and sound actually coming through the rim joist. But, no matter... I don't disagree with @Ladeback's comments. It's possible adding mass to your rim joist could help mitigate both issues. I don't see how it could harm anything. I suppose it boils down to how much effort you are willing to put into it. Since your workroom area will be at least partially open/unfinished, I tend to lean toward making the effort.
> 
> There are other methods you could employ, but you'd be sacrificing real estate to de-couple and without finishing off the whole area it's not worth it unless you wanted to isolate just the playroom area. Either way, your approach seems reasonable and won't have a negative impact.


So just to re-cap, the common wall in the basement is poured concrete where there the truss's sit on top creating the ceiling beams and supporting the floor above. Between the truss is the rim joist area where there is 2 layers of 5/8 firerock. 5/8 on my and 5/8 on my neighbor's side. That's it! It's only about 15 inches high if I remember correctly and 24 inches wide. My contractor installed 2 layers of 1/2 Quiet Rock on my side (because we were having trouble getting 5/8 at the last minute) in each rim joist, sealed everything with Quiet Seal acoustical sealant, added insulation installed the ceiling rock and it worked. Turned up the music in my neighbor's basement full blast and can barely hear it on my side. I know this isn't text book and we could have used green glue, etc, but the point I wanted to post was putting more mass in the rim joist really did the trick in this particular case. This would probably have helped in my living room, there we took down the common wall and re-installed 5/8 quiet rock with ROXUL, got about a 55db reduction in sound but didn't want to take down the ceiling to get at the rim joists. I guess a future project if it's needed.


----------



## Ladeback

jrref said:


> So just to re-cap, the common wall in the basement is poured concrete where there the truss's sit on top creating the ceiling beams and supporting the floor above. Between the truss is the rim joist area where there is 2 layers of 5/8 firerock. 5/8 on my and 5/8 on my neighbor's side. That's it! It's only about 15 inches high if I remember correctly and 24 inches wide. My contractor installed 2 layers of 1/2 Quiet Rock on my side (because we were having trouble getting 5/8 at the last minute) in each rim joist, sealed everything with Quiet Seal acoustical sealant, added insulation installed the ceiling rock and it worked. Turned up the music in my neighbor's basement full blast and can barely hear it on my side. I know this isn't text book and we could have used green glue, etc, but the point I wanted to post was putting more mass in the rim joist really did the trick in this particular case. This would probably have helped in my living room, there we took down the common wall and re-installed 5/8 quiet rock with ROXUL, got about a 55db reduction in sound but didn't want to take down the ceiling to get at the rim joists. I guess a future project if it's needed.


Glad that worked. The harder thing to stop is bass. So that could still get through at times.


----------



## jrref

Right, but in the basement, everything is poured concrete so it's pretty good, but I know what you mean.


----------



## jrref

jrref said:


> So just to re-cap, the common wall in the basement is poured concrete where there the truss's sit on top creating the ceiling beams and supporting the floor above. Between the truss is the rim joist area where there is 2 layers of 5/8 firerock. 5/8 on my and 5/8 on my neighbor's side. That's it! It's only about 15 inches high if I remember correctly and 24 inches wide. My contractor installed 2 layers of 1/2 Quiet Rock on my side (because we were having trouble getting 5/8 at the last minute) in each rim joist, sealed everything with Quiet Seal acoustical sealant, added insulation installed the ceiling rock and it worked. Turned up the music in my neighbor's basement full blast and can barely hear it on my side. I know this isn't text book and we could have used green glue, etc, but the point I wanted to post was putting more mass in the rim joist really did the trick in this particular case. This would probably have helped in my living room, there we took down the common wall and re-installed 5/8 quiet rock with ROXUL, got about a 55db reduction in sound but didn't want to take down the ceiling to get at the rim joists. I guess a future project if it's needed.


I have something interesting to report. So after doing the above work in the basement common wall rim joists I found that the sound attenuation right above in my living room where I previously installed ROXUL and 5/8 Quiet Rock is now greater. I knew I was getting flanking sound via the floor but I never expected adding more mass in the rim joists below would actually help but it did, noticeably. I haven't measured it with a sound meter yet but I will. Too bad it's a huge job to cut open my living room ceiling and do the same to the rim joists above but at least now I know that's a potential for improvement if ever needed. Hope this experience helps.


Also, I know I could have used green glue, etc, but in my case i'm talking about a 20 ft common wall and with labor costs where I live in NY, it was just easier to use the Quiet Rock.


----------



## HT Geek

HT Geek said:


> Do you mean one layer of 5/8 + GG on top of existing drywall (i.e. a drywall sandwich) over studs (no clips & channel)?





tamiya said:


> Yes


Now that I'm back from vacation, I can finally answer your question. LoL.


----------



## HT Geek

jrref said:


> I have something interesting to report. So after doing the above work in the basement common wall rim joists I found that the sound attenuation right above in my living room where I previously installed ROXUL and 5/8 Quiet Rock is now greater. I knew I was getting flanking sound via the floor but I never expected adding more mass in the rim joists below would actually help but it did, noticeably. I haven't measured it with a sound meter yet but I will. Too bad it's a huge job to cut open my living room ceiling and do the same to the rim joists above but at least now I know that's a potential for improvement if ever needed. Hope this experience helps.


Careful now. You may have been bitten by the Home Audio Improvement Bug. That's what you get for hanging around this forum. 

If you have a significant other or roommate, you better warn them they may come home one day and find the living room ceiling is missing. 




> Also, I know I could have used green glue, etc, but in my case i'm talking about a 20 ft common wall and with labor costs where I live in NY, it was just easier to use the Quiet Rock.


Yeah, I don't blame you. There is only a _marginal _difference in performance between the two. Most people on this forum choose Green Glue, for a variety of reasons, but IMHO there is nothing wrong with QuietRock. Well... except it's damn heavy. LoL.


----------



## jrref

About QR being heavy, it is very heavy and besides lifting it, when you knock on my living room wall it's "like" knocking on cement. The stuff has a lot of mass.


----------



## cxwingav

*Expectations of soundproofing?*

Hi everyone,
I'm in the house market as a buyer, and as I visit different houses, I have of course the "where's the theater going to go" question on my mind. Being in CA in the Bay Area, spaces are tight (and expensive!), so I'm hoping you guys can help me with the following question: assume soundproofing being done all the right ways (room in a room), following the guidebook of the experts in the field, what can I expect from soundproofing? With a soundtrack playing at reference level, with no artificially exaggerated bass, would someone in an adjacent room be able to read quietly / sleep? Or it's just going to be relatively quieter with some thumping of all LFE hits?
Maybe a more constrained example: what are the expectations for a bedroom above a garage, where the garage (concrete slab floor for garage, wooden house) would house the theater built inside with the room within a room approach (decoupled walls and ceiling), occupying say 2/3 of the garage space to leave some space for storage?
Opinions and experiences to share are welcome, thanks in advance!
(consultants or contractors in the Santa Cruz/Monterey area are also welcome to IM me!)


----------



## plugto

I tried to make the apartment downstairs a little quieter. I have a modest sized theater and like to play fairly loud, maybe around 69 to 70db. I would like some feedback on what you guys think. I couldn't afford to decouple everything so I stuffed the inside walls with safe and sound. I also did the ceiling with safe and sound, then a layer of 5/8ths sound board before a 5/8ths sheet rock. The outside walls got R23 Rockwool.


----------



## mattztt

*Adding backer boxes to existing lights*

If I have access to the ceiling above existing can lights is it alright to just lay backer boxes directly on the drywall with acoustic caulk without screwing them to the drywall from below or attaching them to trusses or hat channel? These are 4" old work can lights so they are pretty small.

I'm not worried about the weight, but are there other potential issues? Will the acoustic caulk make a good seal and keep them in place if they are not screwed in?


----------



## mattztt

plugto said:


> I tried to make the apartment downstairs a little quieter. I have a modest sized theater and like to play fairly loud, maybe around 69 to 70db. I would like some feedback on what you guys think. I couldn't afford to decouple everything so I stuffed the inside walls with safe and sound. I also did the ceiling with safe and sound, then a layer of 5/8ths sound board before a 5/8ths sheet rock. The outside walls got R23 Rockwool.


Conventional wisdom is to use Green Glue between two layers of 5/8" sheetrock. "Sound board", despite it's name, has limited ability to attenuate sound.
https://www.soundproofingcompany.com/soundproofing-articles/should-i-use-sound-board-in-my-room/


----------



## plugto

Well mattztt I first was going to go with Quiet Rock 510 but that was so expensive. I compared the STC factor and the soundboard wasn't far off and the savings was significant. So with the sound board and the 5/8ths drywall together I think the STC factor is the biggest bang for the buck that I could afford.
But thanks for the link, I will check it out and apply any added information I gather to the upstairs theater- living room when I get up to that part of the remodel.


----------



## mattztt

plugto said:


> Well mattztt I first was going to go with Quiet Rock 510 but that was so expensive. I compared the STC factor and the soundboard wasn't far off and the savings was significant. So with the sound board and the 5/8ths drywall together I think the STC factor is the biggest bang for the buck that I could afford.
> But thanks for the link, I will check it out and apply any added information I gather to the upstairs theater- living room when I get up to that part of the remodel.


Yep, you gotta work with your budget and available materials. Quiet Rock is expensive stuff. From what I've seen the pros who do custom theaters avoid it. It does better than a layer of standard drywall, but the double drywall(*not* Quiet Rock)/Green Glue sandwich seems to be both the least expensive *and* best performing option so that's an easy pick. It's what virtually every custom build I've followed has used.

More info on lab tested results for that setup:
http://www.greengluecompany.com/sites/default/files/Green_Glue_Vs_Soundboard.pdf

I don't sell this stuff, I've just been researching for months in preparation for soundproofing the HT build I'm about to start.


----------



## Kevin4730

Contractor wants to use metal studs to frame out my basement. I don’t know much about metal studs yet, but my first thought is if it is lighter will it effect soundproofing at all?


----------



## mattztt

Kevin4730 said:


> Contractor wants to use metal studs to frame out my basement. I don’t know much about metal studs yet, but my first thought is if it is lighter will it effect soundproofing at all?


If you are just doing drywall directly on the studs then steel is slightly better than wood, but if you do a proper decoupling scheme (double wall or clips/channels) then it doesn't make a difference.


----------



## Kevin4730

mattztt said:


> If you are just doing drywall directly on the studs then steel is slightly better than wood, but if you do a proper decoupling scheme (double wall or clips/channels) then it doesn't make a difference.


This was a reassuring and unexpected response. The contractor sold it as cheaper and easier, if the sound isolation is better why don’t more people use steel beams on here?


----------



## mattztt

Kevin4730 said:


> This was a reassuring and unexpected response. The contractor sold it as cheaper and easier, if the sound isolation is better why don’t more people use steel beams on here?


I imagine it's because most people that care about sound isolation who are doing new construction will be using techniques that mitigate the slight advantage of steel, leaving only the disadvantages.

ETA: Not to say that steel is terrible in any way. It's fine. It's just not as strong as wood and if you're the DIY type it's harder to work with compared to wood if you ever want to do modifications or attach anything to the wall.


----------



## HT Geek

Kevin4730 said:


> This was a reassuring and unexpected response. The contractor sold it as cheaper and easier, if the sound isolation is better why don’t more people use steel beams on here?





mattztt said:


> I imagine it's because most people that care about sound isolation who are doing new construction will be using techniques that mitigate the slight advantage of steel, leaving only the disadvantages.
> 
> ETA: Not to say that steel is terrible in any way. It's fine. It's just not as strong as wood and if you're the DIY type it's harder to work with compared to wood if you ever want to do modifications or attach anything to the wall.


99% of the time, when a contractor offers you a suggestion like that, it is because it benefits them in some way. Steel studs are normally cheaper than wood, but the Catch-22 there is be mindful of the gauge of steel. As @mattztt mentioned, the load bearing capability of steel is less than comparable wood studs due to a variety of technical factors. 

Their biggest advantage is they will never warp. 

If you're going to install anything on your walls other than a single sheet of drywall, I'd be inclined to either use wood or use closer spacing (of steel studs) than the typical 24" O.C. recommended for dedicated HT rooms. Unfortunately, at that point you start reducing your sound proofing ever so slightly. One way to look at it is the very slight improvement in sound proofing offered by steel studs will be mitigated if you have to install them closer together for weight-bearing purposes. And that in turn may eliminate your cost savings.

Bottom line, if you're doing just a standard wall/ceiling with a single layer of drywall, there is nothing wrong with steel studs. However, if you want to go further (strongly recommended), ask yourself if steel studs were such a great idea, why aren't they used in more HT theaters?

Recapping their benes, if you are super anal-retentive about drywall warping or sagging, perhaps steel studs would be a good choice for you (note: my HT ceiling slopes by less than 1/4" across a 23' span, I used wood joists, and my ceiling is 3x drywall layers plus a soffit w/2x layers of drywall). OR if you have an exceptionally complex design (particularly for ceilings), then steel studs can be easier to work with and yield lower labor costs and/or superior results.


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## taxman48

Robot drywall installation:


https://www.engadget.com/2018/10/01/aist-humanoid-robot-installs-drywall/


----------



## taxman48

Question: if the sheet rock ends before a channel, do you add another channel to hold the sheet rock? Ive seen many videos but cant seem to get a straight answer ..


thanks in advance..


----------



## mattztt

taxman48 said:


> Question: if the sheet rock ends before a channel, do you add another channel to hold the sheet rock? Ive seen many videos but cant seem to get a straight answer ..
> 
> 
> thanks in advance..


Generally speaking, if your channel is properly spaced (24" or 16" OC), you should be cutting drywall to line up with your channel, not adding channel to accommodate your drywall.


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## Skylinestar

I'm planning to soundproof a little for my ceiling as I can hear when it rains. Gotta add 4" thick roxul batts at the attic. Is that ok?


----------



## Ladeback

Skylinestar said:


> I'm planning to soundproof a little for my ceiling as I can hear when it rains. Gotta add 4" thick roxul batts at the attic. Is that ok?


I take it you theater is in a bed room? Do you here it hit the walls as well? I think the insulation would help, but Green Glue with another layer of 5/8" drywall may help more. @HT Geek what do you think? He would be better to answer this, I believe your theater is in an upstairs room.


----------



## Ladeback

Skylinestar said:


> I'm planning to soundproof a little for my ceiling as I can hear when it rains. Gotta add 4" thick roxul batts at the attic. Is that ok?


I take it you theater is in a bed room? Do you here it hit the walls as well? I think the insulation would help, but Green Glue with another layer of 5/8" drywall may help more. @HT Geek what do you think? He would be better to answer this, I believe your theater is in an upstairs room.


----------



## HT Geek

Ladeback said:


> I take it you theater is in a bed room? Do you here it hit the walls as well? I think the insulation would help, but Green Glue with another layer of 5/8" drywall may help more. @*HT Geek* what do you think? He would be better to answer this, I believe your theater is in an upstairs room.





Skylinestar said:


> I'm planning to soundproof a little for my ceiling as I can hear when it rains. Gotta add 4" thick roxul batts at the attic. Is that ok?



There's no issue adding more insulation, but that might not solve your problem.


What insulation is in the attic currently? What is the roof made of (exterior surface)?


----------



## HT Geek

taxman48 said:


> Question: if the sheet rock ends before a channel, do you add another channel to hold the sheet rock? Ive seen many videos but cant seem to get a straight answer ..
> 
> thanks in advance..





mattztt said:


> Generally speaking, if your channel is properly spaced (24" or 16" OC), you should be cutting drywall to line up with your channel, not adding channel to accommodate your drywall.



Right. What @*mattztt* said is the recommended/best practice method.

If you have drywall protruding past a stud/joist, it is not being supported at its weakest point where it is most likely to flex. The worst-case scenario would be a ceiling installation of drywall where the edge doesn't land on a stud. Gravity is not going to be your friend in that scenario. Even walls will develop cracks and/or indentations, popping out of the edge, etc.

Now, if you MUST live with the situation for some reason... and I don't recommend this, but as I said if there is a logistical issue you have to deal with... there are a few things you can do to mitigate the problem a bit:

1) Use 2x3 or 2x4 blocks of wood to join adjacent pieces of drywall. It doesn't need to be the entire length. Every 2' or so would be better than nothing. Make them about 6"long or so minimum. Align them so you can get screws in from each adjacent piece of drywall. Note this is going to be a bit more tricky since you're using channel. For one thing, take care not to create a physical connection with the wall that the channels are holding your drywall off of. If necessary, use 1x4 instead if the 2x's are too thick.

2) Stagger at least one more layer of drywall over the layer with the hanging drywall pieces. Make sure you glue the drywall sheets together (Green Glue ideally, or drywall glue if you are not doing GG or similar product in between layers). I'd be inclined to mud and tape the seam of the first layer before layering the second layer over it to try and encourage the first layer to stay in place.

Again, the best method would be to cut the drywall so it aligns with your channels. If someone miscalculated the channel placement, it's best to add a new channel somewhere to compensate and then re-figure the drywall piece dimensions for that portion of your room. You might need to get creative and cut pieces on either side to conform to odd measurements so the seams line up properly.


----------



## Skylinestar

HT Geek said:


> There's no issue adding more insulation, but that might not solve your problem.


I'm worried if it will suck the mid bass away as it is not that thick.



HT Geek said:


> What insulation is in the attic currently? What is the roof made of (exterior surface)?


Just 2 layers of aluminum foil to block some radiant heat from the sun. Roof tiles are of clay.


----------



## Javs

Has anyone actually built a room with STC 73/76 solutions for the walls and ceiling?

Curious how well it actually works, when I build a house and theatre in about 18 months I plan on implementing such a solution the likes of which can be found at 

https://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-walls/

Curious if anyone here has gone the double stud and double green glue route? Or do most of you stop at clips and channels and double drywall+ GG?

I will be most interested in doing everything I can in that room to contain (as best as possible) all the subwoofer energy that will be put out at reference level, pretty aware best case scenario would be about 30db reduction on reference at 20hz.

I want to be able to watch films in there are pretty much reference and not piss off the neighbours. 










I already own pretty much all the actual gear I would use in the room (built all my own speakers) so when building this theatre, pretty much all the cost I am going to put into it will be spent on soundproofing.


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## HT Geek

Skylinestar said:


> I'm worried if it will suck the mid bass away as it is not that thick.
> 
> Just 2 layers of aluminum foil to block some radiant heat from the sun. Roof tiles are of clay.


Are you concerned about possible attenuation of your sound by insulation in your attic? That should be a non-issue. Without knowing the particulars of your attic (slope, air volume, etc.), generally speaking... insulation in the attic for a 2nd floor theater will - aside from environmental concerns - help to slow down sound waves a bit before they make it through the roof and your neighbors can hear them.

In your case - talking about the rain - thicker insulation is going to be more helpful. It's really tough to estimate the actual frequncy of rain hitting your roof, since there are so many variations in roofing materials, roof design, rain intensity, and rain type. I like to endeavor to keep the sound of the elements out period - regardless of what is going on outside. I also have a 2nd floor dedicated HT room. I've had 50mph winds and hail outside and I can't hear any of it inside that room.  Between room air space and the attic interior is approximately 12" of 'pink fluffy' insulation, 5/8" OSB, 1-1/4" drywall, and 2 layers of Green Glue.

If your space is limited in the attic, I would recommend the denser insulation such as 4" thick rigid mineral wool. If you can't do at least 4" thick then also put up another layer of drywall in the ceiling.

If you can do 4" rigid mineral wool, try that first and wait until you can test the results/compare the difference. If that seems insufficient, add an additional layer of drywall to the ceiling.

If you can fit 6" or more of space, you could do pink fluffy / fiberglass insulation and save some $. 

An advantage to the rigid mineral wool is the fact it is resistant to mold/mildew, so if you develop a cracked tile at some point and get any water intrusion, you will likely be OK. Mold does not like to grow in the rigid stuff. Also, make sure you get the aluminum backed boards and install them with the aluminum/shiny side facing UP toward your roof tile. This will serve several benefits: resistance to water intrusion, better behaving sound absorption from your room, and another radiant heat barrier from the exterior. You'll also find adding the insulation will reduce temperature fluctuations in your room.

I hope all that helps.

Bottom line: I'd do rigid fiberglass (4" thick) inside the attic and above your room, aluminum faced (facing up), and possibly also another layer of drywall on the ceiling (wait and test first unless you just want to do it up front).


----------



## HT Geek

Javs said:


> Has anyone actually built a room with STC 73/76 solutions for the walls and ceiling?
> 
> Curious how well it actually works, when I build a house and theatre in about 18 months I plan on implementing such a solution the likes of which can be found at
> 
> https://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-walls/
> 
> Curious if anyone here has gone the double stud and double green glue route? Or do most of you stop at clips and channels and double drywall+ GG?


My dedicated room is double stud, double drywall. It is on a 2nd floor, above my garage. Not ideal location. The weak spot in my room is the floor. I chose not to put the work into what I would call "ideal" isolation, which would have involved removing all the sub-floor and creating a new sub-floor on rubber pucks. I wanted to use RIM but did not have the height clearance without making structural changes to the room that were beyond my comfort level. 

That backdrop explained, I get LFE penetration through the floor into other rooms when the volume is at reference level. There is some penetration through the walls into an adjoining bedroom, but it's muted quite a bit and I can't tell if it's coming through the floor only or both floor and walls. Either way, it is SUBSTANTIALLY less noise than what is in the room. I don't envision someone sleeping in the room next door if the volume were at reference levels and someone was playing rap music in the HT room, for example.

With the volume at 80% of reference and playing a typical music track or a movie, I have to concentrate to hear it from the adjacent bedroom. The biggest headache is scenes with excessively low bass. It's exceptionally difficult to keep sub-50hz bass played at very loud volumes from traveling where you don't want it to. I have dual 18" subs rated 900w RMS and 1800w peak.

What would I do differently next time?

1) Find a way to isolate the floor further
2) Possibly put another layer of drywall + GG on the shared wall in the bedroom adjacent to the HT room

If you want max performance, presuming this will be in a basement or 1st floor, I would suggest investing in an extra layer of drywall + GG on any shared walls (non-HT room side). 



> I want to be able to watch films in there are pretty much reference and not piss off the neighbours.


My room has 2 exterior walls. From outside, you can hear excessive bass played at reference volume from about 30-50 feet away maximum. It's quite audible from around 10' away of the exterior walls. You cannot hear frequencies above around 300hz or so, even at reference level.


----------



## jjcook

As I never finalized this detail yet, regarding 2nd floor builds with existing subfloor which stack up is better for ~low frequency (~40-150Hz) containment?

(A) 3/8 rubber mat + 19/32 osb/t&g + GG + 19/32 osb/t&g, or (B) GG + 23/32 osb/t&g + GG + 23/32 osb/t&g

Both are approximately the same height, the rubber mat choice B is more mass but also creates a somewhat floating floor with a new resonance weak point.


----------



## HT Geek

jjcook said:


> As I never finalized this detail yet, regarding 2nd floor builds with existing subfloor which stack up is better for ~low frequency (~40-150Hz) containment?
> 
> (A) 3/8 rubber mat + 19/32 osb/t&g + GG + 19/32 osb/t&g, or (B) GG + 23/32 osb/t&g + GG + 23/32 osb/t&g
> 
> Both are approximately the same height, the rubber mat choice B is more mass but also creates a somewhat floating floor with a new resonance weak point.



I built mine with a rubber mat beneath the OSB/GG layers and would not heitate to do that again. It's not going to stop bass from permeating through your joists, but it will give your floor a better "feel" all around (walking on it, etc.) and it's a bit better at containment than using wood only (which effectively amounts to just adding more mass to the floor).


----------



## jjcook

HT Geek said:


> I built mine with a rubber mat beneath the OSB/GG layers and would not heitate to do that again. It's not going to stop bass from permeating through your joists, but it will give your floor a better "feel" all around (walking on it, etc.) and it's a bit better at containment than using wood only (which effectively amounts to just adding more mass to the floor).


Thank you for the feedback. My concern is that for some frequency band the ~floating floor will actually be much worse transmission loss since it will have a higher resonant frequency than the original subfloor + additional wood layers approach; its been so long since I looked into this that I don't recall how to approximate the resonant frequency of the rubber+osb stack up; when I get some time I'll go dig that up and follow up here. I am trending towards the rubber underlay stack up...


----------



## HT Geek

jjcook said:


> Thank you for the feedback. My concern is that for some frequency band the ~floating floor will actually be much worse transmission loss since it will have a higher resonant frequency than the original subfloor + additional wood layers approach; its been so long since I looked into this that I don't recall how to approximate the resonant frequency of the rubber+osb stack up; when I get some time I'll go dig that up and follow up here. I am trending towards the rubber underlay stack up...


One way to look at it is that you're simply shifting the resonate frequency. There will be one either way, but if you shift it up it is typically more advantageous than the other way around due to the longer wavelengths of lower Hz sound. Of course, it's possible to get yourself into an undesirable scenario where you're creating a lot of sound in the frequency that is most resonant, but it's nearly impossible to forecast that ahead of time (unless all the content you will play is going to be very similar) and most people won't bother trying to figure out what that would be.

From the 2nd floor, I can tell you from experience that some LFE will permeate through the floor when sound is played at very high volume (e.g. reference level). The effect will be most pronounced directly below the room.

What you can do - and what I would have done in my case if I didn't have a garage beneath my room - is to decouple your sub-floor from the joists below it. That is really what is necessary to get the most sound-proofing end result with regards to the floor. Doing so will improve the situation substantially greater than whether or not you choose to use a rubber mat (though I'd do both, personally).


----------



## Kezzbot

HT Geek said:


> What you can do - and what I would have done in my case if I didn't have a garage beneath my room - is to decouple your sub-floor from the joists below it.


Using hat and channel? Or room in a room?


----------



## HT Geek

Kezzbot said:


> Using hat and channel? Or room in a room?



Basically ala room-within-a-room. Definitely not with hat/channel. Not strong enough. There are several possible approaches to decoupling a floor. And I should have been a bit more specific. Technically, I *did* decouple my floor in my room. I used the technique with 2 layers of plywood or OSB and rubber mat. However, speaking from experience... while it's better than no decoupling, it's not very effective against LFE.


So... if I were to do-it-over, I'd seriously consider using a different technique with greater damping capability, such as rubber U-mounts (they go upside down on the floor joists and raise the floor by a fraction of an inch), or RIM, which would be one of your best options if you use the 2" or thicker version. An advantage to RIM is that AFAIK, you do not need to remove the sub-floor first. It's not cheap, but it is effective.


----------



## GloriousEuropa

About to move into my semi-detached house here in the UK (standard cavity wall brick built). Is there any point in putting soundproofing, dampening drywall on the living room party wall if there's a shared chimney breast between our living room and the neighbour's?


----------



## mhutchins

HT Geek said:


> .
> .
> So... if I were to do-it-over, I'd seriously consider using a different technique with greater damping capability, such as rubber U-mounts (they go upside down on the floor joists and raise the floor by a fraction of an inch), or RIM, which would be one of your best options if you use the 2" or thicker version. An advantage to RIM is that AFAIK, you do not need to remove the sub-floor first. It's not cheap, but it is effective.



Is this how you contemplated using the U-Boats on top of the floor joists? Would you then install a floating sub-floor leaving a gap around the rim to fill with acoustic caulk? Would you still do Serena mat on top of the sub-floor and float another 2 layers of OSB on top of that? If this is going over a garage, would you need to do some form of fire blocking between the U-Boats, or would a ceiling composed 2 layers of 5/8" drywall be sufficient for code compliance? I'm asking because I want to build a maximally isolated above-garage theater.


Thanks,
Mike


Edit - I found a better diagram at the Soundproofing Co.


----------



## HT Geek

mhutchins said:


> Is this how you contemplated using the U-Boats on top of the floor joists? Would you then install a floating sub-floor leaving a gap around the rim to fill with acoustic caulk?


Yes.



> Would you still do Serena mat on top of the sub-floor and float another 2 layers of OSB on top of that?


Yes.



> If this is going over a garage, would you need to do some form of fire blocking between the U-Boats, or would a ceiling composed 2 layers of 5/8" drywall be sufficient for code compliance?



A normal ceiling below it is fine. There is nothing in the building code that says you can't use the U-Boats. While it does alter the air gap beneath the sub-floor, it doesn't change whether or not there is a cavity there (i.e. there is a cavity either way). From a fire-proofing standpoint it doesn't matter.

Two things to watch out for: 

1) Whether or not your layout of U-Boats is sufficient from a load-bearing perspective, since the sub-floor is then resting on the U-Boats. Make sure you understand the U-Boat load bearing rating and the number you're using is sufficient. This should be a non-issue, but it's good to know the details in case you have a picky building inspector (if they even see the U-Boats... unless they can see them from below, they probably won't). Also good for your piece-of-mind.

2) I would personally float the floating floor on the U-Boats, meaning do not screw the sub-floor into the U-Boats. The floating floor should not be coupled to the joists via screws. Only by its weight. Your floor will be so heavy it's a non-issue. I would not mention that to the building inspector since they're not used to that and might freak, even though it's a non-issue. That floor is not going to move when it is 3 layers thick. Besides, your walls will be pushing down on it as well, and your walls and ceiling will all be attached to the outer room shell via clips or similar means. You'll end up with a box inside a box. It's not going anywhere. 



> I'm asking because I want to build a maximally isolated above-garage theater.


If $ and room height are not barriers, I would recommend you also do one or the other (or ideally both) of the following:

1. HT room side: Install a 2" RIM product on top of the floating floor. Your total raised floor height will be about 4"
2. Remove existing drywall (if any) in garage ceiling. Use clips & channel on the garage ceiling with 2x drywall and Green Glue.

Alternative to #2 would be just put a 2nd layer of drywall on ceiling in garage. Won't be as effective but more effective than not doing it.


----------



## HT Geek

GloriousEuropa said:


> About to move into my semi-detached house here in the UK (standard cavity wall brick built). Is there any point in putting soundproofing, dampening drywall on the living room party wall if there's a shared chimney breast between our living room and the neighbour's?


I would do it. I believe you'd find it's still worthwhile.

You'll still improve the transmission loss across the entire surface area. What you should expect is you will get more sound leakage where there isn't additional sound proofing. Lower frequencies tend to be more difficult to isolate direction, but it should help reduce higher frequency sound levels transmitting between the walls (e.g. you'd be less likely to hear people talking in the adjacent unit).

The chimney breast should provide decent sound proofing to begin with, compared with the surrounding walls, so I would think you'd benefit overall by improving the walls around it. IOW, the chimney is not your weak point right now to begin with.


----------



## mhutchins

HT Geek said:


> .
> .
> Two things to watch out for:
> 
> 1) Whether or not your layout of U-Boats is sufficient from a load-bearing perspective, since the sub-floor is then resting on the U-Boats. Make sure you understand the U-Boat load bearing rating and the number you're using is sufficient. This should be a non-issue, but it's good to know the details in case you have a picky building inspector (if they even see the U-Boats... unless they can see them from below, they probably won't). Also good for your piece-of-mind.


Absolutely! Kinetics Noise Control has a spec sheet for their RIM system that specifies special High-Load pads spaced 16"OC underneath any partition walls that are attached to the floating floor. I will definitely check with the U-Boat manufacturer and get their recommendations for supporting a partition wall, as that is currently part of my plan.



HT Geek said:


> 2) I would personally float the floating floor on the U-Boats, meaning do not screw the sub-floor into the U-Boats. The floating floor should not be coupled to the joists via screws. Only by its weight. Your floor will be so heavy it's a non-issue. I would not mention that to the building inspector since they're not used to that and might freak, even though it's a non-issue. That floor is not going to move when it is 3 layers thick. Besides, your walls will be pushing down on it as well, and your walls and ceiling will all be attached to the outer room shell via clips or similar means. You'll end up with a box inside a box. It's not going anywhere.
> 
> If $ and room height are not barriers, I would recommend you also do one or the other (or ideally both) of the following:
> 
> 1. HT room side: Install a 2" RIM product on top of the floating floor. Your total raised floor height will be about 4"


This is my current plan, from the joist up: Floor Joists ^ U-Boats ^ T&G OSB ^ Green Glue ^ T&G OSB (OSB layers screwed together with overlapping seams, no screw penetrations into joists, air gap around perimeter of floating floor filled with 1/2" polyethylene foam and topped with fire resistant caulking) ^ Tractor Supply 3/4" Horse stall mats* ^ T&G OSB ^ Green Glue ^T&G OSB (air gap around perimeter of floating floor filled with 1/2" polyethylene foam and topped with fire resistant caulking) ^ carpet pad ^ carpet

* Since deep bass isolation is my biggest concern, which product will do more to isolate the bass from penetrating/flanking through the floor: the heavy horse stall mats or the 2" RIM product with the insulated air gap?



HT Geek said:


> 2. Remove existing drywall (if any) in garage ceiling. Use clips & channel on the garage ceiling with 2x drywall and Green Glue.
> 
> Alternative to #2 would be just put a 2nd layer of drywall on ceiling in garage. Won't be as effective but more effective than not doing it.


I will probably just do 2 layers of 5/8" drywall with Green Glue for the garage ceiling. I'm not concerned with blocking sound transmission from the garage into the theater because I am the only one that uses the garage and I haven't yet mastered the power of being in two places at once. 

Mike


----------



## HT Geek

mhutchins said:


> Absolutely! Kinetics Noise Control has a spec sheet for their RIM system that specifies special High-Load pads spaced 16"OC underneath any partition walls that are attached to the floating floor. I will definitely check with the U-Boat manufacturer and get their recommendations for supporting a partition wall, as that is currently part of my plan.
> 
> This is my current plan, from the joist up: Floor Joists ^ U-Boats ^ T&G OSB ^ Green Glue ^ T&G OSB (OSB layers screwed together with overlapping seams, no screw penetrations into joists, air gap around perimeter of floating floor filled with 1/2" polyethylene foam and topped with fire resistant caulking) ^ Tractor Supply 3/4" Horse stall mats* ^ T&G OSB ^ Green Glue ^T&G OSB (air gap around perimeter of floating floor filled with 1/2" polyethylene foam and topped with fire resistant caulking) ^ carpet pad ^ carpet
> 
> * Since deep bass isolation is my biggest concern, which product will do more to isolate the bass from penetrating/flanking through the floor: the heavy horse stall mats or the 2" RIM product with the insulated air gap?


My money is on the RIM, but I'd do both if you can. 

Above ground floors are really tough to isolate. And there's just not much data on floor assembly performance, so I find one often has to look for anecdotal evidence via comparisons of whatever test data is available plus use general audio science knowledge to come up with a SWAG (Scientific Wild Ass Guess).

Bruck Richards Chaudiere Inc. did a comparo in 2000 between rubber mat, engineered wood, and natural hardwood. These were field tests performed in a gym where the products in question were installed on the surface. If you only look at the headline numbers, the rubber mat's performance was not impressive; it only outperformed the hardwood products by 1 F-IIC ("Field" IIC, meaning measurements were taken "in the field" and "not in a lab"). Big whoop! Except, that is not the real story. The 'real' data shows the rubber mat outperformed in LFE impact tests by roughly 5 db at the lowest freqs compared to the wood products. Maybe not huge, but better.

That's the only bona-fide test of rubber mats I can recall off-hand. It's unclear to me how much of a difference it makes when the surface material is the same and the rubber is sandwiched between other products. I believe the prevailing wisdom is what makes the rubber mat sandwich valuable (versus another layer of plywood, for example), is the fact the resonate frequency of the rubber mat will be different than the wood around it. So, between that fact and its mass, you are addressing damping via two methods (frequency absorption and mass). Speaking of mass... most 3/8" rubber mat is close to the mass of OSB.

There's a lot more data on RIM. Using STC/IIC just for an easy comparison of sorts. Laid on a concrete sub-floor, 2" RIM with 3x plywood layers on top is 66 STC / 63 IIC. With regards to bass performance, the lowest the test went to was 80 Hz, which was -36 db. Incidentally, RIM is insanely effective at higher frequency blocking (90+ db TL from 2khz and up).

BTW, something interesting about RIM.... If you take a floor and apply RIM, then create an air gap (e.g. 16" or 24" O.C. joists), and then place plywood on top of that, the end result is highly detrimental to sound proofing. The air cavity reduces the TL (Transmission Loss) by more than 50%. Ouch.

If you use RIM and rubber mats, your best bet would be:

*Floor Joists --> U-Boats --> Structural Sub-floor --> RIM --> 2 layers Plywood, staggered --> Rubber mat --> 1 or 2 layers Plywood (staggered if 2) --> Pad --> Carpet*



> I will probably just do 2 layers of 5/8" drywall with Green Glue for the garage ceiling. I'm not concerned with blocking sound transmission from the garage into the theater because I am the only one that uses the garage and I haven't yet mastered the power of being in two places at once.


 So, if you're not concerned with sound exiting the HT room into the garage.... Why go to all that trouble? A standard floating floor with plywood or OSB and rubber mat will suffice, with one exception: vibration from garage door openers may be felt/heard (depends on your door opener). Of course, that only lasts a few seconds and would be rare.

OTOH, your approach would be very beneficial in dramatically reducing the transmission of bass through the floor joists and throughout the remainder of your home. So, if that is also a goal then it may be worth the effort.


----------



## mhutchins

HT Geek said:


> My money is on the RIM, but I'd do both if you can.
> .
> .
> If you use RIM and rubber mats, your best bet would be:
> 
> *Floor Joists --> U-Boats --> Structural Sub-floor --> RIM --> 2 layers Plywood, staggered --> Rubber mat --> 1 or 2 layers Plywood (staggered if 2) --> Pad --> Carpet*
> 
> 
> 
> mhutchins said:
> 
> 
> 
> I will probably just do 2 layers of 5/8" drywall with Green Glue for the garage ceiling. I'm not concerned with blocking sound transmission from the garage into the theater because I am the only one that uses the garage...
> 
> 
> 
> So, if you're not concerned with sound exiting the HT room into the garage.... Why go to all that trouble? A standard floating floor with plywood or OSB and rubber mat will suffice, with one exception: vibration from garage door openers may be felt/heard (depends on your door opener). Of course, that only lasts a few seconds and would be rare.
Click to expand...

My comment above was poorly phrased. Let me restate it this way: I'm not overly concerned with direct sound transmission between the theater and the garage below. I am very concerned with flanking sound transmission through the theater floor into adjacent rooms both on the level of the theater (2nd floor) and the rooms below on the 1st floor (other than the garage directly below).

So, your comment below, is very reassuring.



HT Geek said:


> OTOH, your approach would be very beneficial in dramatically reducing the transmission of bass through the floor joists and throughout the remainder of your home. So, if that is also a goal then it may be worth the effort.


Mike


----------



## dmbmay98

I could use some advice. My basement was already finished by the builder but we are looking to remodel it into a dedicated theater. The area we are looking at putting the theater is under the morning room in the basement. Three sides of the room are cement and the 4th we need to frame out. I was thinking of ripping out the ceiling and doing the best SPC solution from their website. My question is for the side walls. How should I go about handling those since they are facing cement? Do I need to rip those out and start over. For the fourth wall I am framing I will implement some type of SPC solution. I just was not sure how the sound moves up from the side walls facing the cement.


----------



## HT Geek

dmbmay98 said:


> My question is for the side walls. How should I go about handling those since they are facing cement? Do I need to rip those out and start over.


No. That would be a bad idea. Those are load bearing walls (holding your house up)! Plus that is actually a positive for a dedicated HT room.

What you will need to do is add wood or steel stud framing, spaced slightly away from the walls to create an air gap (1" is a good figure in terms of how much space between the concrete wall and edge of your studs).



> For the fourth wall I am framing I will implement some type of SPC solution. I just was not sure how the sound moves up from the side walls facing the cement.


It will be good at absorption for sound traveling up. The trade-off is cement reflects some of the sound that hits it straight-on. Build inner walls as mentioned above and stuff with insulation and you will eliminate most of that as the sound will have to travel through the inner wall and insulation twice. 

If you have the height, I would construct a floating ceiling as well. That will allow your entire room to be 'contained' or isolated from the main house.

If you are really concerned with sound travel and like to play movies and music at high volumes, you could also use clips & channel, but that's going to be overkill for most people. The ceiling will be the biggest concern in your case.

Pay particular attention to your room height. Most municipal and state building codes require a minimum 7 feet of finished height. Some are vague as to whether or not that is pre or post flooring installation in a room. If you don't have a lot of height to work with, it will mean either sacrifices or getting creative. 

I'm only scratching the surface here. There are many more details to consider, but those are the high points for now.


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## Jetski6

Current unfinished theater space is 18'10” wide, 19.3' long, and has 8'9” ceilings. Will have to build 3of4 wall off concrete walls and will be doing clip & channel on walls and ceiling. Planning for dbl 5/8 dw with green glue in ceiling joists to reduce footfall. Question is what length screws are needed for each layer of DW? Just screw thru the subfloor only as have hardwoods above. 1 1/8 and 1 3/4 long enough? Last question is acoustical caulk needed for the sides?

Thanks in advance for help


----------



## gigging

Hello,

I bought enough roxul safe and sound and 2x2’s to build (2) corner bass traps. I will be putting one in each of my front corners. 
I have a false wall with 24” of space in it. The false wall is covered with 1/4 plywood. Do I place the corner bass traps behind the screen wall or in front of the screen wall?
My room is 28x20x8’

Thank you!
Just realized I put this in the soundproofing thread, I meant to put it in the acoustic treatment thread. Sorry, but if anyone wants to answer I’d appreciate it


Sent from my iPhone using Tapatalkjust


----------



## DoofusOfDeath

HT Geek said:


> No. That would be a bad idea. Those are load bearing walls (holding your house up)! Plus that is actually a positive for a dedicated HT room.
> 
> What you will need to do is add wood or steel stud framing, spaced slightly away from the walls to create an air gap (1" is a good figure in terms of how much space between the concrete wall and edge of your studs).
> 
> It will be good at absorption for sound traveling up. The trade-off is cement reflects some of the sound that hits it straight-on. Build inner walls as mentioned above and stuff with insulation and you will eliminate most of that as the sound will have to travel through the inner wall and insulation twice.
> 
> If you have the height, I would construct a floating ceiling as well. That will allow your entire room to be 'contained' or isolated from the main house.
> 
> If you are really concerned with sound travel and like to play movies and music at high volumes, you could also use clips & channel, but that's going to be overkill for most people. The ceiling will be the biggest concern in your case.
> 
> Pay particular attention to your room height. Most municipal and state building codes require a minimum 7 feet of finished height. Some are vague as to whether or not that is pre or post flooring installation in a room. If you don't have a lot of height to work with, it will mean either sacrifices or getting creative.
> 
> I'm only scratching the surface here. There are many more details to consider, but those are the high points for now.


I'm soundproofing a home office in the corner of my basement, where the foundation wall goes from the floor to about 4' up, and after that it's external framing. 

I too have been confused regarding how SPC's recommended wall designs apply to rooms adjacent to the concrete foundation.

For lack of any better ideas, I'm planning a design based on (a) the principles I've read about in the past few months and (b) limitations imposed by my local building codes and (c) space limitations. They include:

Try to avoid triple / quadruple -leaf designs.
Try to maximize the volume of the empty chamber behind the drywall in your soundproofed room, to reduce low-frequency transmission.
(Local code requirement) Interior partitions require R13+ insulation.
(Local code requirement, maybe universal) Need fire-stopping material at top of wall interiors.
Take comfort that the foundation is very massive on its own.

So basically I'm going for a double-framed wall design, treating my house's foundation / external wall as the "outer" of the two walls. And I'm just accepting that I have limited control over the composition of that "outer" wall.

Starting with the surface of the inner wall, I intend to use this sequence of layers:


5/8" type X gypsum
GG
5/8" type X gypsum
hat channel on GG Whisper Clips
2x4 framing, maybe (TBD) isolated from the ceiling joists using something like SBC's IB-3 decoupling brackets. R13 batt between the studs.
Air gap (size TBD, no more than 12") to the concrete foundation wall. At the top, some kind of fire-stopping insulation between the new wall's top plate and the exterior wall (to comply with fire code).

I'm having a hard time deciding whether or not it's worth including the IB-3 (or similar) decoupling clips in these walls or any others. Here are some factors in my uncertainty:

They're _not_ stipulated in the wall design recommended by Green Glue's design guide[/URL] (p. 39). (Google for "green_glue_electronic_design_guide_0.pdf")
They're not mentioned in SPC's "Level 3" wall design[/URL].
But in private conversation with Ted, it sounded like they might improve the wall's low-frequency performance. I'm still unclear on why if they might be helpful, they're not shown in the SPC's Level 3 wall design.


----------



## Ladeback

DoofusOfDeath said:


> I'm soundproofing a home office in the corner of my basement, where the foundation wall goes from the floor to about 4' up, and after that it's external framing.
> 
> I too have been confused regarding how SPC's recommended wall designs apply to rooms adjacent to the concrete foundation.
> 
> For lack of any better ideas, I'm planning a design based on (a) the principles I've read about in the past few months and (b) limitations imposed by my local building codes and (c) space limitations. They include:
> 
> Try to avoid triple / quadruple -leaf designs.
> Try to maximize the volume of the empty chamber behind the drywall in your soundproofed room, to reduce low-frequency transmission.
> (Local code requirement) Interior partitions require R13+ insulation.
> (Local code requirement, maybe universal) Need fire-stopping material at top of wall interiors.
> Take comfort that the foundation is very massive on its own.
> 
> So basically I'm going for a double-framed wall design, treating my house's foundation / external wall as the "outer" of the two walls. And I'm just accepting that I have limited control over the composition of that "outer" wall.
> 
> Starting with the surface of the inner wall, I intend to use this sequence of layers:
> 
> 
> 5/8" type X gypsum
> GG
> 5/8" type X gypsum
> hat channel on GG Whisper Clips
> 2x4 framing, maybe (TBD) isolated from the ceiling joists using something like SBC's IB-3 decoupling brackets. R13 batt between the studs.
> Air gap (size TBD, no more than 12") to the concrete foundation wall. At the top, some kind of fire-stopping insulation between the new wall's top plate and the exterior wall (to comply with fire code).
> 
> I'm having a hard time deciding whether or not it's worth including the IB-3 (or similar) decoupling clips in these walls or any others. Here are some factors in my uncertainty:
> 
> They're _not_ stipulated in the wall design recommended by Green Glue's design guide[/URL] (p. 39). (Google for "green_glue_electronic_design_guide_0.pdf")
> They're not mentioned in SPC's "Level 3" wall design[/URL].
> But in private conversation with Ted, it sounded like they might improve the wall's low-frequency performance. I'm still unclear on why if they might be helpful, they're not shown in the SPC's Level 3 wall design.


In my basement I am against one wall and have glued 1" of Styrofoam to the concrete wall and have about 5" air gap between the foam and back of the stud wall. Now I did this because I run it under a joist at the recommendation of my father in law. Now I could have put up blocking and moved it closer or use IB-3 clips to support the wall. I may still do this to get about 4" more in my room length. Now on my other walls I was just going to decouple the walls at the top with IB-3 clips and not use IB-1 clips and hat channel on the wall to save room and thought it was over kill to me. Some I believe done it this way, with just clips and hat channel or both. I would ask Ted his opinion on it, but to me the IB-3"s give you a small attachment point to the floor above and decrease the sound traveling up to the next floor through the walls. I was only going to clips and channel on the ceiling with DDW+GG and Rockwool in the walls and ceiling.
@HTGeek would be better to answer this though.


----------



## Gazzer55

Hi All - I have a time sensitive question - I have 15 bags of safe n sound for a new theater build as I am finishing my basement. The contractors out 6 bags in the ceiling which I felt was necessary to prevent as much sound from getting up into the kitchen directly above.

I have 9 bags remaining for the 4 walls however recently read that putting S+S on the exterior walls where there is already pink fluffy / vapour barrier will have little effect, is that true? I will do the two interior walls for sure but am wondering if I should put the rest of the material in the ceiling outside of the theater or keep to my original plan and use it in the theater exterior walls to keep the coverage consistent (S+S on all the walls).


----------



## HT Geek

Gazzer55 said:


> Hi All - I have a time sensitive question - I have 15 bags of safe n sound for a new theater build as I am finishing my basement. The contractors out 6 bags in the ceiling which I felt was necessary to prevent as much sound from getting up into the kitchen directly above.
> 
> I have 9 bags remaining for the 4 walls however recently read that putting S+S on the exterior walls where there is already pink fluffy / vapour barrier will have little effect, is that true? I will do the two interior walls for sure but am wondering if I should put the rest of the material in the ceiling outside of the theater or keep to my original plan and use it in the theater exterior walls to keep the coverage consistent (S+S on all the walls).


It really depends on your goals. What are you trying to accomplish by adding insulation?

With regard to your exterior walls, are you looking at this from a perspective of R rating (heat exchanger) or soundproofing? What are the exterior walls made of? Are your exterior walls underground or partially subterranean?

How concerned are you about sound traveling through those exterior walls?

Presuming for a moment your primary concern is the kitchen, and that the kitchen is above your theater room, you may be better off using more in the ceiling of the theater room. However, you have to be a bit cautious in that regard if that is your goal for the interior. You don't want to condense that insulation too much or you will produce a counterproductive effect.

I realize I'm giving you a vague response when you expressed a time-sensitive nature of your query. the issue is without lots of details it's difficult to give you a good answer. Pictures and additional information would be helpful in giving you a clearer response.

What other soundproofing measures have you implemented (or plan to)? And what are the most important concerns you have regarding soundproofing? Do you have a build thread?


----------



## Gazzer55

HT Geek said:


> It really depends on your goals. What are you trying to accomplish by adding insulation?
> 
> With regard to your exterior walls, are you looking at this from a perspective of R rating (heat exchanger) or soundproofing? What are the exterior walls made of? Are your exterior walls underground or partially subterranean?
> 
> How concerned are you about sound traveling through those exterior walls?
> 
> Presuming for a moment your primary concern is the kitchen, and that the kitchen is above your theater room, you may be better off using more in the ceiling of the theater room. However, you have to be a bit cautious in that regard if that is your goal for the interior. You don't want to condense that insulation too much or you will produce a counterproductive effect.
> 
> I realize I'm giving you a vague response when you expressed a time-sensitive nature of your query. the issue is without lots of details it's difficult to give you a good answer. Pictures and additional information would be helpful in giving you a clearer response.
> 
> What other soundproofing measures have you implemented (or plan to)? And what are the most important concerns you have regarding soundproofing? Do you have a build thread?


Thanks for the note - I am less concerned with R rating, the exterior walls are concrete and are underground. There is already pink insulation which I believe is code and I am not overly concerned with sound getting to the outside as I have my driveway, then a neighbours before their house

My primary use of the same n sound is to keep the theater room noise as contained as possible (I know I didnt take enough steps for the low frequency but thats something I have to live with).

My other reason why I was leaning towards using it is to make sure the reflections of all the speakers are consistent from wall to wall. If I only had the 1/ inch drywall, then an air gap of the frame before hitting vapour barrier. pink insulation, concrete wall, will that behave much differently that the interior walls using the same drywall and filled with S+S.


----------



## mattztt

Does that air gap provide a flanking path out of the room? (Does it continue to the exterior of an adjacent room?) If so I'd use some to fill that gap.


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## HT Geek

Gazzer55 said:


> Thanks for the note - I am less concerned with R rating, the exterior walls are concrete and are underground. There is already pink insulation which I believe is code and I am not overly concerned with sound getting to the outside as I have my driveway, then a neighbours before their house
> 
> My primary use of the same n sound is to keep the theater room noise as contained as possible (I know I didnt take enough steps for the low frequency but thats something I have to live with).
> 
> My other reason why I was leaning towards using it is to make sure the reflections of all the speakers are consistent from wall to wall. If I only had the 1/ inch drywall, then an air gap of the frame before hitting vapour barrier. pink insulation, concrete wall, will that behave much differently that the interior walls using the same drywall and filled with S+S.



Tough to say without fully understanding your room layout from a construction perspective. At a high level, concrete tends to be reflective of higher frequency sound, and a good absorber of lower frequency sound. When sound hits concrete at a 90° angle, higher freqs will tend to bounce back. Point is yes, you want some damping material between the concrete and the sound source. That said, under most circumstances I'd venture that pink fluffy and drywall would be sufficient and I doubt you'd perceive any difference in reflection from that wall versus another in the room. But that is a generalization without detailed knowledge of your layout. OTOH, it won't hurt to line those exterior walls with more insulation, so if you are concerned about it then I'd say go for it if you have the physical space. Like I said, it won't harm anything. It might be a benefit.


Back to the trade-off between room above and those exterior walls in your basement.... if I were in your position, I would be more concerned with sound traversing up into the room above versus through a subterranean exterior wall, provided you already have some insulation on that exterior wall already. And if you're concerned about both, why not stop by a Big Box hardware store tomorrow morning and get some more pink fluffy, and stuff that along the exterior wall? It's cheap and readily available on short notice. Use your Roxul to further insulate the ceiling above. My 2 cents, FWIW... based on limited info.


----------



## Gazzer55

HT Geek said:


> Tough to say without fully understanding your room layout from a construction perspective. At a high level, concrete tends to be reflective of higher frequency sound, and a good absorber of lower frequency sound. When sound hits concrete at a 90° angle, higher freqs will tend to bounce back. Point is yes, you want some damping material between the concrete and the sound source. That said, under most circumstances I'd venture that pink fluffy and drywall would be sufficient and I doubt you'd perceive any difference in reflection from that wall versus another in the room. But that is a generalization without detailed knowledge of your layout. OTOH, it won't hurt to line those exterior walls with more insulation, so if you are concerned about it then I'd say go for it if you have the physical space. Like I said, it won't harm anything. It might be a benefit.
> 
> 
> Back to the trade-off between room above and those exterior walls in your basement.... if I were in your position, I would be more concerned with sound traversing up into the room above versus through a subterranean exterior wall, provided you already have some insulation on that exterior wall already. And if you're concerned about both, why not stop by a Big Box hardware store tomorrow morning and get some more pink fluffy, and stuff that along the exterior wall? It's cheap and readily available on short notice. Use your Roxul to further insulate the ceiling above. My 2 cents, FWIW... based on limited info.


Thanks for the note - I started installing the Safe and Sound on the walls of the theater last night and ultimately I think I will go ahead and cover all of the walls. Perhaps it's a waste of money on the exterior walls if it will have little to no change on soundproofing / dampening (as the general contractor said), but I figure for the $200 it will cost, it gives me piece of mind and will be far more expensive to do it later. 
I'll do an initial test by hooking up my sub / one speaker to see just how the safe and sound helped in comparison to no safe and sound, before the drywall goes up. 

I hope the results are decent - especially since I only have an SVS PB1000 now and plan on upgrading to include another larger sub.......I'll make sure I really crank the PB tonight. Unfortunately I dont think I will be able to get too much more in the way of soundproofing since the installer is not using a resilient channel on the walls / ceiling.....


----------



## Gazzer55

Following the below - I have a rather large bulkhead beside the ibeam running lengthwise for the theater which is only partly filled with ductwork. Is it generally good practice to fill this rather tightly with safe and sound or better to put one layer on the bottom and sides so there is an air cavity in the middle area?


----------



## HT Geek

Gazzer55 said:


> Thanks for the note - I started installing the Safe and Sound on the walls of the theater last night and ultimately I think I will go ahead and cover all of the walls. Perhaps it's a waste of money on the exterior walls if it will have little to no change on soundproofing / dampening (as the general contractor said), but I figure for the $200 it will cost, it gives me piece of mind and will be far more expensive to do it later.


Sounds like a plan. As you said, it's a relatively small investment for peace of mind, and to retrofit it later would be substantially more work and cost.



> I'll do an initial test by hooking up my sub / one speaker to see just how the safe and sound helped in comparison to no safe and sound, before the drywall goes up.
> 
> I hope the results are decent - especially since I only have an SVS PB1000 now and plan on upgrading to include another larger sub.......I'll make sure I really crank the PB tonight. Unfortunately I dont think I will be able to get too much more in the way of soundproofing since the installer is not using a resilient channel on the walls / ceiling.....


Depending on how you're conducting your test... and what you're testing... in general you'll find the insulation makes a bigger difference with regards to mid-to-high frequency sound (e.g. speech/voices/kid noises).



Gazzer55 said:


> Following the below - I have a rather large bulkhead beside the ibeam running lengthwise for the theater which is only partly filled with ductwork. Is it generally good practice to fill this rather tightly with safe and sound or better to put one layer on the bottom and sides so there is an air cavity in the middle area?


Fill loosely with pink fluffy. Double drywall on your ceiling, with Green Glue or similar product to make a sandwich. If it's metal ductwork you might consider using something like OC 703 around the duct, but make sure there is an air gap between the duct and drywall. 

Another factor to consider with ducts is their openings in your room and potential flanking sound through the ducts, which is why flex duct and snaking it is recommended (this creates bends that promote capturing deflected sound, in conjunction with the pink fluffy padded around it).


----------



## Gazzer55

HT Geek said:


> Sounds like a plan. As you said, it's a relatively small investment for peace of mind, and to retrofit it later would be substantially more work and cost.
> 
> 
> Depending on how you're conducting your test... and what you're testing... in general you'll find the insulation makes a bigger difference with regards to mid-to-high frequency sound (e.g. speech/voices/kid noises).
> 
> 
> 
> Fill loosely with pink fluffy. Double drywall on your ceiling, with Green Glue or similar product to make a sandwich. If it's metal ductwork you might consider using something like OC 703 around the duct, but make sure there is an air gap between the duct and drywall.
> 
> Another factor to consider with ducts is their openings in your room and potential flanking sound through the ducts, which is why flex duct and snaking it is recommended (this creates bends that promote capturing deflected sound, in conjunction with the pink fluffy padded around it).


Thanks for the note - Unfortunately all I have to work with right now is the safe and sound material - I have about a 3 hour window tonight to get it all in place as the drywall guys are coming tomorrow. For the duct, would putting a later on the bottom as well as the sides, effectively boxing it on where there is an air gap in the middle be acceptable? The entire ceiling is done already. 

I will try and put the insulation in the ceiling for at least a few feet in the adjacent rooms to help absorb any sound that escapes through the floor joists.


----------



## HT Geek

Gazzer55 said:


> Thanks for the note - Unfortunately all I have to work with right now is the safe and sound material - I have about a 3 hour window tonight to get it all in place as the drywall guys are coming tomorrow. For the duct, would putting a later on the bottom as well as the sides, effectively boxing it on where there is an air gap in the middle be acceptable? The entire ceiling is done already.


 Yes.

Actually... if it is flex duct, don't worry about the air gap. If it is rigid metal duct, you should leave an air gap (1/2" minimum).



> I will try and put the insulation in the ceiling for at least a few feet in the adjacent rooms to help absorb any sound that escapes through the floor joists.


Anything directly connected and hard, such as floor joists, is going to transmit sound through vibration. Particularly LFE. Use a double-drywall layer on adjacent rooms if you can. It will help more than anything else (more mass). Make it a Green Glue sandwich if you can.

Since it sounds like you're not using clips & channel or double framing.... Also, a note on double drywall.... make sure the drywall guys understand the inner layer should be mudded but don't pay them to tape it (no point). You want the mud in between the seams though. Your outer layer (the one you see in the room) gets finished normally, of course.

Does that make sense? With a build where you aren't able to use decoupling techniques such as clips & channel or independent framing (room-within-a-room) methods, your next best option is to hang as much mass in that room's walls and ceiling as you can. Drywall is cheap. The labor to install inner layers in a multi-layer configuration is less than the outer layer, because they require basic mudding (does not need to be sanded) and only finishing the outer layer.

Furthermore, if you are thinking of going with fabric wall panels in the room, you can save more $ by skipping the finishing process on the outer later of drywall and having them mud it only (again this can be done without sanding the walls). Reason being you will cover it all up with the fabric panels. Food for thought.


----------



## denslayer

So this is what I hear sometimes when watching a movie. The neighbors 30+ yr shower valve was one layer of sheetrock from our bed. I plan on 2 layers 5/8 + GG, putty pads, some insulation , channels and clips. I'm planning on somehow putting sheetrock around the valve area. Looking for any other suggestions to reduce or silence this valve. Can also hear just about everything in that bathroom


----------



## warwwolf7

*sprayed foam against fiberglass actual measurements*



BasementBob said:


> If you must use both foam and fluffy, use as little fluffy as possible. You don't need much fluffy to get the most soundproofing benefit, and the less thermal insulation the fluffy provides the more likely the condensation point will be inside the closed cell foam somewhere which is just fine. For example, 3" of closed cell foam, 1" air gap, 1" fluffy in the studs, would be fine just about anywhere.



Hi,
I've been scavanging the web for days about actual test results on Sprayed foam Stc result in wall assembly comparison. I could not find official test. I looked-NRC-CNRC
-soundproofingcompany (they even refer to this https://nparc.nrc-cnrc.gc.ca/eng/view/fulltext/?id=bd0ee4e8-155e-4a79-9aaa-83aaa117d6da but there is nothing about spray foam)
-numerous soundproofing and stc walls assembly documents from various companies.​In this thread, it has been recommended mutliple times to use the doublewall assembly and 1" fiberglass insulation. Not to much fiberglass in order to avoid condensation and mold problem. 

My situation for my basement 

concrete wall (8") - 1" gap- 2"x3"wall - 2-3inches of sprayed foam (in the 1"gap and between the 2x3 studs)
Future HT room dimension : -13'wide x 24'long 
-2 exterior walls. 
​I'm really curious to find the difference in the STC result of this type of wall8"concretewall - 1" gap- 2"x3"wall - 2-3inches of sprayed foam (in the 1"gap and between the 2x3 studs) - hat and channels - 5/8typeX drywall - GG - 5/8"drywall​Against this type of wall8"concretewall - 2"x3"wall - fiberglass - 5/8typeX drywall - GG - 5/8"drywall

​What is going the be the major differences. From what AVS members said, the foam will couple the wall to the concrete. I don't see how this could be of any issue since the drywall is already de-coupled from the wall with hat-channel. I know we don't want to have an empty cavity in the wall. Wouldn't the sprayfoam do that in a certain extend? Is it so bad at absorbing sound that the sound will bounce back in the room?


I want to take this line to thank every contributors of this forum. Such a pleasure to read. So many details are given. So many answers are given. I've never had to ask any question yet, as all the answers I had were answered in AVS forum. 

Cheers


----------



## OJ Bartley

I'm not an expert by any means, but I have been reading up on the subject since I want to do spray foam in my basement. From my understanding, spray foam is best used on exterior walls where you want to seal against the elements (drafts, leaks, insects, etc), and its 2 main benefits are A) achieving that tight seal (that you usually don't get with fluffy batts); and B) good insulation R-value. I don't believe it does much at all for sound proofing, and can sometimes actually have a negative impact from coupling everything together, and transmitting vibration, as you noted.

Now, my plan is to spray my exterior walls to about 2 - 3" depth, getting a solid vapor barrier in that, and a complete exterior seal. My walls are framed on average about 1" off the concrete due to being mostly out of square, so in most places I'll be left with an inch or two of air gap to the drywall, which I plan to fill with SafeNSound batts, cut or ripped down to the right depth. This will both combat the "stack effect" of leaving an open space, and hopefully add some small degree of sound insulation. All interior walls will be fully filled with SafeNSound, as will all ceiling joist cavities.

The theatre will have double drywall with GG on all 4 walls and ceiling, but I am not planning to decouple with clips and channel. I have already added a layer of drywall+GG to the subfloor above, between the ceiling joists. I hope that all together, that will end up giving me some reduction in the overall sound transmission.


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## ronny31

One question though, what is the concrete, is it those Leca pebbles in nice rectangular grey blocks or is it poured concrete from a truck? 8" of poured concrete is pretty darn sound-proof in of itself, the rest will depend on the wood structure above it and around the vents (if there are any) and the windows (if there are any) and the doors (if there is one, or if you built a concrete room with no doors you monster  ). 

What frequencies you'll be putting out also matters a little, we build the car sound deadening a bit different depending on where it is in the car (we want to reduce how much bass escapes the rear half of the car, and want to reduce road noise intruding in the front half). The basic rule of thumb is that there's the car chassis, then some reinforcement on that in the rear half of the car and the roof, then there's a heavy dense rubber compound called butyl, then there's some soft plushy material we mostly skip at the rear half of the car except the wheel arches. So from this I'd wager if you had 2 by 4 studs mounted to the concrete, with a layer of something properly dense sprayed on the concrete between the studs, then some rockwool on that to fill the remaining bit to the plywood that's screwed onto the studs, then some drywall if you want (mostly for its weight, you could use high density particle-board aka floor sheets too), then a layer of plushy material like some rockwool or glasswool, then simply fabric on top of that stapled in place on some floating 1by1 studs. Or maybe even just glued onto the rockwool with spray fabric adhesive.


----------



## warwwolf7

ronny31 said:


> One question though, what is the concrete, is it those Leca pebbles in nice rectangular grey blocks or is it poured concrete from a truck? 8" of poured concrete is pretty darn sound-proof in of itself, the rest will depend on the wood structure above it and around the vents (if there are any) and the windows (if there are any) and the doors (if there is one, or if you built a concrete room with no doors you monster  ).
> 
> What frequencies you'll be putting out also matters a little, we build the car sound deadening a bit different depending on where it is in the car (we want to reduce how much bass escapes the rear half of the car, and want to reduce road noise intruding in the front half). The basic rule of thumb is that there's the car chassis, then some reinforcement on that in the rear half of the car and the roof, then there's a heavy dense rubber compound called butyl, then there's some soft plushy material we mostly skip at the rear half of the car except the wheel arches. So from this I'd wager if you had 2 by 4 studs mounted to the concrete, with a layer of something properly dense sprayed on the concrete between the studs, then some rockwool on that to fill the remaining bit to the plywood that's screwed onto the studs, then some drywall if you want (mostly for its weight, you could use high density particle-board aka floor sheets too), then a layer of plushy material like some rockwool or glasswool, then simply fabric on top of that stapled in place on some floating 1by1 studs. Or maybe even just glued onto the rockwool with spray fabric adhesive.


Thank you for your answer.

The concrete walls are 8" of poured concrete.

My plan, is to go with 2x3" wall on the 2 exterior walls as they are already built and insulated with 2-3" of spray foam.

I want to go with channel - drywall 5/8 - green glue - drywall 5/8. The 2x3 wall is attached to the floor joists above. No channel would mean I'm just wasting my money as the sound from above will be transmitted to the 2x3wall back to the drywall.

Now, my question is, does anyone has heard of any test that was done with spray foam vs fiberglass or mineral wool regarding Soundproofing.

I know it was said that spray foam is bad for sound proofing. But does anyone has data to back it up?


@jc

Im planning on window plugs on the exterior wall and double door on a double wall. 
I also plan to go with drywall and GG and drywall under the floor. But it as been discussed enough in this thread already I think , I have nothing to add that would be of any interest. 
The only part that I can't get any test results is the spray foam effiency against fiberglass or.... 

What is the difference going to be? 3stc? 15stc?

If I have to add a 2"x2" (I know originally I wrote 1x1", typo error) to the exterior walls, and add small layer of fiberglass, then I'll do it. But if it's doing no difference, I don't want to waste time doing that. 

Thank you all. 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## ronny31

One test is better than a thousand expert opinions. You could build a test box and test different solutions. 
My gut says a thin layer of spray foam over the studs first, then rockwool, will be best.


----------



## warwwolf7

*my Conclusion on Spray foam sound insulation*



ronny31 said:


> One test is better than a thousand expert opinions. You could build a test box and test different solutions.
> My gut says a thin layer of spray foam over the studs first, then rockwool, will be best.


I would hope so. I did found some tests but they were not done in comparison to others tests.I found this but could not find any reference of the test facilities and method used. They only mention "verified by an acoustic consultant". Which doesn't help and Sounds fishy at best.
*"Sealection 500"*
http://www.polyurethanefoamsystems.com/files/Sealection%20500%20-%20The%20Sound%20Barrier.pdf

they all refer to the "sealection 500" tests. 
http://bresslerinsulation.com/soundratings_files/sound-rating-and-spray-polyurethane-foam-article.pdf
https://www.demilec.ca/documents/Bibliotheque-Technique/Sealection-500-Fiche-Technique.pdf

ref 8a : stc52
While the same test with fiberglass in owens corning document gives a stc57. Looking at the well respected NRC-CNRC work, the documents IRC-IR-761 : gives a STC62 with fiberglass.

While I looked at the NRC-CNRC document, I decided to do one last search with CNRC and spray foam. Here are my findings.
Those studies were about "flanking path". Which is something that eveybody should also be aware of when building their walls as it has a big significance in the final STC result of the room
*Document A1-004377.2 *
"The use of spray foam insulation instead of fiberglass insulation reduces the direct sound insulation by approximately 5 STC points, but does not significantly influence the flanking sound insulation." refering to A1-100035-02.1 

document
* A1-100035-02.1*
I found this
"NLB-W7 (exterior wall – spray foam insulation) " I got pretty excited. Maybe I had found what I was looking for for soo long. 
Is put againts NLB-W6 (fiberglass batt) Result:
NLB-W7 : stc34
NLB-W6 : stc38
that's a 4STC difference, which is appreciable and goes in the same direction as Document A1-004377.2


page 171in the pdf (however labled p.165 in the page) there are a bunch of floor comparison with a 38mm concrete floor as the base.
38mm (1.5inch) concrete with 9.5mm(3/8") closed cell foam (i would guess it's rigid board)... 
not much helpful data here

https://svetlanaroit.files.wordpress.com/2009/11/visual_values2.pdf
page 4, polyurethame foam (1") have a noise reduction coefficients of 0.3 while fiberglass 1" semi-rigid is 0.75 while this document gives a NRC of 0.5 

A single layer of poured concrete 150 mm thick gives an STC of about 55
pdf link
8" concrete wall, which give by itself STC58 (RiverBank Acoustical Labs (TL 76-77 1977 16f)
8" concrete wall stc58
sound transmission loss through concrete and concrete masonry walls by...

*
_Conclusion Spray foam sound insulation________________________*

I really hope this can help others as well. Based on my very tiny findings, spray foam would give around 4-5STC lower than fiberglass batt. Now the reason I have spray foam on exterior walls is purely for thermal insluation and water barrier. So spray foam will stay. Fortunatly for me, those wall are against a 8" concrete wall, which give by itself STC58, I therefore think that with channel, 5/8"DD + GG I should be able to go meet 60STC+
Anyone care to add anything?

cheers


----------



## OrangePhile

So, I'm busy with my own HT build, thread here. I thought I'll start browsing the "what I'll do differently next time" and the soundproofing threads....you guys pretty much have me in tears now, I'm never going to get my project done.



My HT(25' x 16' x 8') is directly beneath my main bedroom. Right now it's unlikely that the HT will be used while someone is trying to sleep above. 5 years from now when kids are teenagers it might be a different story, and by then I might have upgraded my equipment and made them output more oomph.





















My plan up to this morning was just to insert some pink fluff in my wall cavities and safeNsound(or similar) in the ceiling. Was then going to follow up with suspended 2x4 black ceiling tiles. I unfortunately cannot install proper drywall sheets as ceiling as my joists has more spring in them than I care for, so I fear it will always give a bit and that will crack my ceiling over time.



Now, after reading all of the last 6months' posts I'm thinking maybe I need to use channel and insulating clips for the walls(with one 5/8" sheet) with pink stuffing, and then GG strips of 1/2" strips into the ceiling between the joists then follow that with safeNsound and suspended ceiling.



I could double up my walls but since there isn't much on the other side I don't really care.



Thoughts?


----------



## warwwolf7

OrangePhile said:


> So, I'm busy with my own HT build, thread here. ... I'm never going to get my project done.
> 
> 
> 
> 
> 
> 
> . I unfortunately cannot install proper drywall sheets as ceiling as my joists has more spring in them than I care for, so I fear it will always give a bit and that will crack my ceiling over time.
> 
> 
> 
> Now, after reading all of the last 6months' posts I'm thinking maybe I need to use channel and insulating clips for the walls(with one 5/8" sheet) with pink stuffing, and then GG strips of 1/2" strips into the ceiling between the joists then follow that with safeNsound and suspended ceiling.
> 
> 
> 
> I could double up my walls but since there isn't much on the other side I don't really care.
> 
> 
> 
> Thoughts?


Don't get overwhelmed by the amount of work. You don't have to swallow it all at once, take one step at a time. Planning is the most critical phase, after that just follow the plan. Yes it is time consuming, but you have to enjoy the path otherwise you'll find yourself always looking for the end result and never feel satisfied. (it's been a 7year project for me as I had numerous other issues to solve before I could get to the build of the room itself. (delivery of gypsum arrives on Saturday)) 

If you think your floor is to springy, you could look into joist sistering. I see you already have blocking between your joists. Blocking usually helps to reduce spring in joist. A visit of an engineer could also be beneficial. I did and it helped me to go in the right direction. It's was a good investment for me. 

I'm pretty sure that a suspended ceiling is a compromise from gypsum. Even more if you plan to add more oomph in it. It was discussed somewhere in this thread about suspended ceiling. Not sure if it relates to your situation or not. I believe it was in the first 50-75pages. (that's about where I got tired and started to skip 1-2-10-50 pages, I have only one live to live! ) 

Wish you the best.


----------



## OrangePhile

warwwolf7 said:


> Don't get overwhelmed by the amount of work. You don't have to swallow it all at once, take one step at a time. Planning is the most critical phase, after that just follow the plan. Yes it is time consuming, but you have to enjoy the path otherwise you'll find yourself always looking for the end result and never feel satisfied. (it's been a 7year project for me as I had numerous other issues to solve before I could get to the build of the room itself. (delivery of gypsum arrives on Saturday))
> 
> If you think your floor is to springy, you could look into joist sistering. I see you already have blocking between your joists. Blocking usually helps to reduce spring in joist. A visit of an engineer could also be beneficial. I did and it helped me to go in the right direction. It's was a good investment for me.
> 
> I'm pretty sure that a suspended ceiling is a compromise from gypsum. Even more if you plan to add more oomph in it. It was discussed somewhere in this thread about suspended ceiling. Not sure if it relates to your situation or not.
> 
> Wish you the best.
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk




Thanks Wolf. I already sistered some of the joists, especially the cracked ones(40yr old house) and I might add a few more just for fun!

The blocks are in and certainly makes a difference. I wonder if adding more will make a positive difference?

Problem right now is that my space downstairs is pretty much an unfinished basement with a projector and speakers. My wife hates it down there....so right now is just my space. Maybe that's a good thing.  I do need to spend and few thousand to finish it up to get return on my investment. 


Sent from my iPhone using Tapatalk


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## warwwolf7

OrangePhile said:


> Thanks Wolf. I already sistered some of the joists, especially the cracked ones(40yr old house) and I might add a few more just for fun!
> 
> The blocks are in and certainly makes a difference. I wonder if adding more will make a positive difference?
> 
> Problem right now is that my space downstairs is pretty much an unfinished basement with a projector and speakers. My wife hates it down there....so right now is just my space. Maybe that's a good thing.  I do need to spend and few thousand to finish it up to get return on my investment.
> 
> 
> Sent from my iPhone using Tapatalk


Joist sistering, the goal is to add stiffness. How to achieve that : a lot of fasteners. Nails. A lot. Of them. You want them to behave like one, no two separate joist. By looking at you picture is see through bolts. I tell you, you need a lot fasteners. You want every bit of flexing force to be transferred to the sister joist to help resist. 3-4 through bolt will help, but you'll get better results with nails. A lot of them. (I you have limited space in between, use a palm nailer, a beautiful invention) screws will break on shear force, nails will bend long before breaking. 

There is also a lot of argumentation about gluing them or not. Wet the wood and apply urethane glue (like pl premium) . Without water the urethane glue is almost useless. 

I have no idea about blocking, but the pair of blocking would probably be better than 1 set. But if I had tk choose between 2 blocking of joist sistering with 1 block. I'd choose the second one. 
Don't take my word for it, look it up. (just be prepared for arm fatigue, arms up, for 30 nails times x joists... Fun times!) 

. I could go on, but it's a bit far from soundproofing thread's subject...

You want to keep your wife away? Hahaha. Don't say that. I'm sure you'll want her by your side when your finish.

Envoyé de mon LG-H873 en utilisant Tapatalk


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## geelo

Apologies in advance for hijacking the thread. If I am posting in the wrong place, please escort me to the nearest exit!

I was hoping I could get some feedback about my particular finished basement. I have attached a floorplan of the room in question. My challenge is that I have tenants that lives adjacent to the room where I would like to begin setting up a home theatre. 

My biggest concern is the open space by the "wet bar" as the sound would have a clear path to reaching the tenant bedroom wall. My initial thought is to have a door built between the wet bar and the bathroom. Would that be a practical solution?

With regard to the wall shared between the "flex area" and the tenant living room, should I be looking to build a double wall there? What about the walls surrounding the staircase?


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## niccolo

geelo said:


> Apologies in advance for hijacking the thread. If I am posting in the wrong place, please escort me to the nearest exit!
> 
> I was hoping I could get some feedback about my particular finished basement. I have attached a floorplan of the room in question. My challenge is that I have tenants that lives adjacent to the room where I would like to begin setting up a home theatre.
> 
> My biggest concern is the open space by the "wet bar" as the sound would have a clear path to reaching the tenant bedroom wall. My initial thought is to have a door built between the wet bar and the bathroom. Would that be a practical solution?
> 
> With regard to the wall shared between the "flex area" and the tenant living room, should I be looking to build a double wall there? What about the walls surrounding the staircase?


A door that closes a huge hole will make a significant difference, especially for higher frequency sound (but far less so for lower frequency sound).


Isolated double walls, when other parts of the structure are untreated, are likely to make only a modest difference.



A lot of sound, especially lower frequency sound, will travel through the framing. So a full-on build would involve what people here call "room within a room" construction, combining isolation, mass, absorption, and damping, and especially isolation and mass.


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## warwwolf7

Gello
double wall and room within a room aren't your only options. 
Look at nrc 761 and nrc 766 (I don't remember which is the one for the wall soundproof test).you can see that there are other options that takes less real estate and can give good results.

Double wall or double drywall + channel (maybe green glue) both requires you to rip current drywall. (look "triple leaf effect"). Whether you have the space to do double wall or not is upon you.

Double drywall +channel is less space invasive.

You would have to do the wall between flex and the room, the staircases, the wall on the right of the wet bar, and the door you would install. Ceiling should also be addressed.

Then you room will be isolated from your tenant. There is also a possible leaking path from the outside wall to you ceiling then to your tenant. While you're at it, doing all the walls of your theatre room would reduce the sound leakage. 

Like was said before, if you do soundproofing, do it "all-in" or be prepared for mixed results. 

That's only my opinion.
Good luck 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## akiddo

Hello all,

I'm finishing my basement and have a space I'm building out for a home theater. The room is not closed off, it's in a corner of the house and open on 2 sides with half walls. I have no expectations of creating a high quality sound setup in the room, but I am looking to reduce sound transmission to the upstairs. I have plans to insulate the ceiling in the entire basement with something like Roxul Safe 'n' Sound, and the walls will be insulated as well, but I'm not sure if there is value in me doing more than this, particularly in the ceiling space above the theater space. Given that 2 of the walls are open to the remainder of the basement (and near the stairs), do you think there would there be sufficient value in finishing the ceiling in this space with green glue, resilient channel, etc...

I'm open to any and all advice about how to maximize the sound quality and soundproofing in this space.

Thanks!


----------



## niccolo

akiddo said:


> Hello all,
> 
> I'm finishing my basement and have a space I'm building out for a home theater. The room is not closed off, it's in a corner of the house and open on 2 sides with half walls. I have no expectations of creating a high quality sound setup in the room, but I am looking to reduce sound transmission to the upstairs. I have plans to insulate the ceiling in the entire basement with something like Roxul Safe 'n' Sound, and the walls will be insulated as well, but I'm not sure if there is value in me doing more than this, particularly in the ceiling space above the theater space. Given that 2 of the walls are open to the remainder of the basement (and near the stairs), do you think there would there be sufficient value in finishing the ceiling in this space with green glue, resilient channel, etc...
> 
> I'm open to any and all advice about how to maximize the sound quality and soundproofing in this space.
> 
> Thanks!



The four principles of soundproofing apply, as always: decoupling (breaking the connection between stuff), mass (making stuff heavier to reduce the resonance frequency), absorption (making cavities less drum-like), damping (making stuff resonate less).


Just putting some insulation into cavities will make them less drum-like, but if vibration is flowing through the framing, that's not going to do much for you, and especially at lower frequencies.


The challenge with your setup is that there's a large area to treat, and it's hard to assess how useful just treating a smaller area would actually be. But you can try to assess it logically and you can also experiment (put speakers in various places downstairs, play content at various frequencies, and see how the sound travels).


Others have far more experience than I, but my best guess is clips and channel or Green Glue are not worth doing in your case.


----------



## DoofusOfDeath

Any suggestions for how to cut 25 gauge steel hat channel (for hanging an decoupled ceiling)?

I've tried metal sheers, but they deform the hat channel near the cut. I've looked into a steel-cutting blade for my mitre saw, but the blades for cutting ferrous metals run close to $100, so I'd like to avoid that if I can.

I'm only going to need 10 or fewer cuts, so I'm not very concerned about saving time on each individual cut.


----------



## DoofusOfDeath

akiddo said:


> Hello all,
> 
> I'm finishing my basement and have a space I'm building out for a home theater. The room is not closed off, it's in a corner of the house and open on 2 sides with half walls. I have no expectations of creating a high quality sound setup in the room, but I am looking to reduce sound transmission to the upstairs. I have plans to insulate the ceiling in the entire basement with something like Roxul Safe 'n' Sound, and the walls will be insulated as well, but I'm not sure if there is value in me doing more than this, particularly in the ceiling space above the theater space. Given that 2 of the walls are open to the remainder of the basement (and near the stairs), do you think there would there be sufficient value in finishing the ceiling in this space with green glue, resilient channel, etc...
> 
> I'm open to any and all advice about how to maximize the sound quality and soundproofing in this space.
> 
> Thanks!


I'm at the tail end of a soundproofing project for my basement home office. I did a _lot_ of research ahead of time, with many hours scouring message boards, vendor websites, etc. 

I could have saved myself tons of wasted time and energy by just starting with Rod Gervais' book, available through Amazon or other sources. I strongly recommend it as your starting point. I also recommend getting the print version, as it can be awkward trying look at some of the figures (which are often rotated 90 degrees) in the e-book format.


----------



## Ladeback

akiddo said:


> Hello all,
> 
> I'm finishing my basement and have a space I'm building out for a home theater. The room is not closed off, it's in a corner of the house and open on 2 sides with half walls. I have no expectations of creating a high quality sound setup in the room, but I am looking to reduce sound transmission to the upstairs. I have plans to insulate the ceiling in the entire basement with something like Roxul Safe 'n' Sound, and the walls will be insulated as well, but I'm not sure if there is value in me doing more than this, particularly in the ceiling space above the theater space. Given that 2 of the walls are open to the remainder of the basement (and near the stairs), do you think there would there be sufficient value in finishing the ceiling in this space with green glue, resilient channel, etc...
> 
> I'm open to any and all advice about how to maximize the sound quality and soundproofing in this space.
> 
> Thanks!


I have been reading and debating if I want to soundproof my theater I am building in my basement under my kitchen and livingroom. From what I have been told is kind all or nothing. Going all out is not cheap even if you do it your self and my wife didn't understand why it was needed because I don't really go that load in the room currently, but I am not using my subs because of load hum from a ground loop. I am just going with drywall on the walls and Rockwool in the ceiling to see how that works. Now I may screw up some drywall with Green Glue between the joists to help if the subs are to much when I get them working. 

What is the room above your theater? I usually am just watching football when my wife is watching he Hallmark shows and she doesn't complain. We usually watch movies together so no one complains, even my 9 year old. Now the subs haven't been on remember, but I have a 5.1 system in my livingroom and hear the 10" in basement at times, but not that bad. Do you like watching are reference? I have been in a few theaters in my area that can shake the house pretty good and not sure soundproofing would do a lot about 1000 watts going to 8 18" subs. 

You could contact the soundproofing company, they are pretty helpful.


----------



## akiddo

Ladeback said:


> I have been reading and debating if I want to soundproof my theater I am building in my basement under my kitchen and livingroom. From what I have been told is kind all or nothing. Going all out is not cheap even if you do it your self and my wife didn't understand why it was needed because I don't really go that load in the room currently, but I am not using my subs because of load hum from a ground loop. I am just going with drywall on the walls and Rockwool in the ceiling to see how that works. Now I may screw up some drywall with Green Glue between the joists to help if the subs are to much when I get them working.
> 
> What is the room above your theater? I usually am just watching football when my wife is watching he Hallmark shows and she doesn't complain. We usually watch movies together so no one complains, even my 9 year old. Now the subs haven't been on remember, but I have a 5.1 system in my livingroom and hear the 10" in basement at times, but not that bad. Do you like watching are reference? I have been in a few theaters in my area that can shake the house pretty good and not sure soundproofing would do a lot about 1000 watts going to 8 18" subs.
> 
> You could contact the soundproofing company, they are pretty helpful.


Yeah - I've spent that last few days researching this and more or less decided that I'll do the insulation in the ceiling and that's it. I started poking in this direction because I was building it out and figured it was now or never. Given that the room isn't fully contained anything I do would only be a half-way job at best. And at that point, why do it. The insulation will cut down on the noise from the kids playing downstairs, and 800% of the time that will be more than enough.

I do have a consult setup for tomorrow with a local sound and video company. I'm gonna more or less play dumb with them and see what they have to say. We'll see if that changes anything.


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## Ladeback

I mostly don't want to hear my son playing upstairs, my sump pump run and our furnace run. Adding some drywall wall has helped with the furnace in the basement, but not the sump pump or kid bouncing a ball. On weekends after everyone goes to bed I will watch a movie so no issues with people making noise above.


----------



## DoofusOfDeath

*Ventilation design*

As mentioned elsewhere, I'm nearing the end of a project to soundproof my home office. It's in a corner of my basement, with a laundry room on one side and a recreation room on the other. 

In order to get good airflow within my office, I plan to draw air from one of those adjacent rooms, and exhaust into the other. This will place the air inlet and outlet at opposite ends of my office, which should give good air exchange.

I'm looking for suggestions about the design to use for the air ducting. I've seen a few competing designs, and I'm not sure which is better for my scenario. I'm shooting for about 100 CFM of ventilation.

Design "A" calls for a run of flexible duct, with some curvature within the run, and enclosed in a soundproof box. We see this with The Soundproofing Company's "dead vent" design, and a few other places on the Internet. (I'd post a link but I don't have enough forum-karma for that.) The vent's footprint is a box about 8' x 1' x 2

Design "B" calls for a relatively compact box that implement a baffle, without using any manufactured ducting. We see this in Figure 7.8 of Rod Gervais' book (2nd edition), and also elsewhere on the Internet. This vent's footprint is about 4' x 3' x 2'.

Gervais' book also shows what looks like a hybrid of "A" and "B", an "exchange chamber' in Figure 7.5. This design is similar to The Soundproofing Company's "dead vent", in the use of (at least one) long, enclosed duct, without an (obvious) baffle box.

Aside from preferences regarding the footprint, does anyone know of a reason to choose one of these designs over the others?


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## niccolo

Ladeback said:


> I have been reading and debating if I want to soundproof my theater I am building in my basement under my kitchen and livingroom. From what I have been told is kind all or nothing. Going all out is not cheap even if you do it your self and my wife didn't understand why it was needed because I don't really go that load in the room currently, but I am not using my subs because of load hum from a ground loop. I am just going with drywall on the walls and Rockwool in the ceiling to see how that works. *Now I may screw up some drywall with Green Glue between the joists to help if the subs are to much when I get them working. *
> 
> What is the room above your theater? I usually am just watching football when my wife is watching he Hallmark shows and she doesn't complain. We usually watch movies together so no one complains, even my 9 year old. Now the subs haven't been on remember, but I have a 5.1 system in my livingroom and hear the 10" in basement at times, but not that bad. Do you like watching are reference? I have been in a few theaters in my area that can shake the house pretty good and not sure soundproofing would do a lot about 1000 watts going to 8 18" subs.
> 
> You could contact the soundproofing company, they are pretty helpful.



Extra drywall (mass) will lower the resonant frequency of your walls, and Green Glue will damp the drywall so it resonates less. But just thinking about it logically, low frequency vibration is going to travel through the framing, so isolation (e.g. clip and channel, dual wall, or staggered studs) is crucial, and I doubt extra drywall and Green Glue will help much in containing your subs (they will help more with higher frequency sound, especially if done comprehensively).


----------



## Ladeback

niccolo said:


> Extra drywall (mass) will lower the resonant frequency of your walls, and Green Glue will damp the drywall so it resonates less. But just thinking about it logically, low frequency vibration is going to travel through the framing, so isolation (e.g. clip and channel, dual wall, or staggered studs) is crucial, and I doubt extra drywall and Green Glue will help much in containing your subs (they will help more with higher frequency sound, especially if done comprehensively).


I was thinking of doing it more for foot fall and helping to not hear my kid bang around above me, but if just insulation and drywall will help then no need for it.


----------



## 1mageWIS

*Soundproofing Wall Remodel Questions / Advice*

Hello All, I have a very inconsiderate neighbor (tenant at that, he doesn't even own it and his landlord does nothing; this is a condo) who has his flat screen TV against the wall, he's using the built in speakers which, as you know face backwards and project directly against my wall. He's also in his 60's and is losing his hearing, so he turns it up to a crazy high volume level. He's unwilling to change anything, so I'm going to have to soundproof the wall. 

The wall is: H: 8' - 1/4" x W: 12' - 11 1/8". 

The current wall from mine to his is: 1/2" drywall, 1" air gap, concrete wall, 1" air gap, 1/2" drywall; voices are almost clearly audible from the TV 35' - 40' away. 

*I was thinking of:*

1) Removing the current drywall, adding to the another 1' x 2' wood furring strip to the current 1' x 2' studs (or replacing them and adding 2' x 4's, not sure which way makes the most sense)

2) Putting in Roxul (Rockwool) Safe n' Sound insulation (what's the best spacing width to use?) 

3) Adding isolation clips (which are best?) 

4) Adding metal resilient metal channels to decouple

5) Adding two layers of 5/8" drywall sandwiched with Green Glue. 

A) There is only one electrical outlet, and I plan on sealing that / wrapping acoustical putty around it. 


*Questions:* 

I) Should this be enough to stop me from hearing my neighbors TV? 

II) What's the correct way to attach baseboard to the new wall as to not cause (sound) short circuits? 

III) Is it enough that the wood studs be attached to the brick wall, or do I have to 

IV) Doesn't the small gap of air between the clips and the drywall create another 'triple leaf effect'? 


Any answers and/or thoughts would be greatly appreciated!


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## DoofusOfDeath

DoofusOfDeath said:


> Any suggestions for how to cut 25 gauge steel hat channel (for hanging an decoupled ceiling)?
> 
> I've tried metal sheers, but they deform the hat channel near the cut. I've looked into a steel-cutting blade for my mitre saw, but the blades for cutting ferrous metals run close to $100, so I'd like to avoid that if I can.
> 
> I'm only going to need 10 or fewer cuts, so I'm not very concerned about saving time on each individual cut.


FYI, I've found a solution to this:

I took two of the hat-channel-holding clips, and screwed them very close to each other on a 2x4. I then put a piece of hat-channel into those clips, such that the location of my cut will be in the narrow gap between the two clips. I then made my cuts with a simple handheld hack saw.

Before using a hack saw, I tried using my sawzall with metal-cutting blades. This failed miserably, I think because the blades' teeth were too coarse. When I tried making the cut, the hat-channel, along with the bracing I used, jumped all over the place.

I also looked into using a circular saw (either handheld, or chop saw, etc.) with a fine-tooth carbide blade. Apparently this works, but will ultimately wreck the tool as metal filings end up in the motor compartment. So I didn't try this myself.


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## DoofusOfDeath

1mageWIS said:


> Hello All, I have a very inconsiderate neighbor (tenant at that, he doesn't even own it and his landlord does nothing; this is a condo) who has his flat screen TV against the wall, he's using the built in speakers which, as you know face backwards and project directly against my wall. He's also in his 60's and is losing his hearing, so he turns it up to a crazy high volume level. He's unwilling to change anything, so I'm going to have to soundproof the wall.
> 
> The wall is: H: 8' - 1/4" x W: 12' - 11 1/8".
> 
> The current wall from mine to his is: 1/2" drywall, 1" air gap, concrete wall, 1" air gap, 1/2" drywall; voices are almost clearly audible from the TV 35' - 40' away.
> 
> *I was thinking of:*
> 
> 1) Removing the current drywall, adding to the another 1' x 2' wood furring strip to the current 1' x 2' studs (or replacing them and adding 2' x 4's, not sure which way makes the most sense)
> 
> 2) Putting in Roxul (Rockwool) Safe n' Sound insulation (what's the best spacing width to use?)
> 
> 3) Adding isolation clips (which are best?)
> 
> 4) Adding metal resilient metal channels to decouple
> 
> 5) Adding two layers of 5/8" drywall sandwiched with Green Glue.
> 
> A) There is only one electrical outlet, and I plan on sealing that / wrapping acoustical putty around it.
> 
> 
> *Questions:*
> 
> I) Should this be enough to stop me from hearing my neighbors TV?
> 
> II) What's the correct way to attach baseboard to the new wall as to not cause (sound) short circuits?
> 
> III) Is it enough that the wood studs be attached to the brick wall, or do I have to
> 
> IV) Doesn't the small gap of air between the clips and the drywall create another 'triple leaf effect'?
> 
> 
> Any answers and/or thoughts would be greatly appreciated!


Depending on your relationship with this guy, you might consider tackling this from a different direction: 

For example, there are bluetooth speakers that could be placed right near his chair. If he'd be willing to use those, then it would be far cheaper for you to buy him one of those than for you to add soundproofing.

Even better is if you, or one of his kids if he has any, could persuade him to get a hearing aid. Unfortunately sometimes people really resist getting them, even if money isn't an object. I'm not sure why.

If you're not worried about maintaining a cordial relationship with him, you might also consider filing noise complaints with the police until he finally gets tired of them visiting him and/or having to paying fines. That could also be the motivation he needs to use one of the solutions I mentioned above.

If you're really committed to soundproofing your living space, I highly recommend you a hard-copy of "Home Recording Studio: Build It Like the Pros" by Rod Gervais as a starting point. Just be warned that you _might_ be signing up for a bigger project than you realize, depending on the particulars.

(A truly evil person would take advantage of the fact that the TV is located on a shared wall, whose wiring you could access without him realizing. I'm not actually suggesting you do that, but it's funny to contemplate.)


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## 1mageWIS

DoofusOfDeath said:


> Depending on your relationship with this guy, you might consider tackling this from a different direction:
> 
> For example, there are bluetooth speakers that could be placed right near his chair. If he'd be willing to use those, then it would be far cheaper for you to buy him one of those than for you to add soundproofing.
> 
> Even better is if you, or one of his kids if he has any, could persuade him to get a hearing aid. Unfortunately sometimes people really resist getting them, even if money isn't an object. I'm not sure why.
> 
> If you're not worried about maintaining a cordial relationship with him, you might also consider filing noise complaints with the police until he finally gets tired of them visiting him and/or having to paying fines. That could also be the motivation he needs to use one of the solutions I mentioned above.
> 
> If you're really committed to soundproofing your living space, I highly recommend you a hard-copy of "Home Recording Studio: Build It Like the Pros" by Rod Gervais as a starting point. Just be warned that you _might_ be signing up for a bigger project than you realize, depending on the particulars.
> 
> (A truly evil person would take advantage of the fact that the TV is located on a shared wall, whose wiring you could access without him realizing. I'm not actually suggesting you do that, but it's funny to contemplate.)


There is no relationship with this guy. He's been renting for 20 years, and he constantly breaks city ordinances and HOA rules and no one does anything. His landlord lives in another state and doesn't care about anything but getting his rent check. I've already offered money to them to purchase a pair of bluetooth headphones (and explained what the technical issue is), but to no avail. 

He's an old, miserable 60-something-year-old man who doesn't understand he's not alone on this planet. He has no kids, only two dogs he constantly yells at. When I tried speaking with him, he was automatically defensive, didn't want to hear anything I said, yelled at, and slammed the door in my face. 

Small claims in the amount of $5000 in my county would cost $300 to file (small claims costs are the same as civil costs, FML), so I'd rather put that $300 towards soundproofing the wall and getting the HOA to deny renewal of his lease (there are more than a few CCR's that he's breaking, for years now). Soundproofing is my only option at this point. 

I wrote the particulars of what I need to achieve, any advice on that front would be appreciated.


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## niccolo

1mageWIS said:


> There is no relationship with this guy. He's been renting for 20 years, and he constantly breaks city ordinances and HOA rules and no one does anything. His landlord lives in another state and doesn't care about anything but getting his rent check. I've already offered money to them to purchase a pair of bluetooth headphones (and explained what the technical issue is), but to no avail.
> 
> He's an old, miserable 60-something-year-old man who doesn't understand he's not alone on this planet. He has no kids, only two dogs he constantly yells at. When I tried speaking with him, he was automatically defensive, didn't want to hear anything I said, yelled at, and slammed the door in my face.
> 
> Small claims in the amount of $5000 in my county would cost $300 to file (small claims costs are the same as civil costs, FML), so I'd rather put that $300 towards soundproofing the wall and getting the HOA to deny renewal of his lease (there are more than a few CCR's that he's breaking, for years now). Soundproofing is my only option at this point.
> 
> I wrote the particulars of what I need to achieve, any advice on that front would be appreciated.



One interested wrinkle here is that we tend to talk about soundproofing from the inside out, i.e. certain things (like adding damped, isolated mass) are most effective on the side of the wall where the noise is being produced. 



Still, the basic principles apply--isolate to break the connections through which vibrations transfer, add mass to reduce vibration frequency, damp that mass to make it vibrate less readily, and put absorptive material into cavities so they're less drum-like.


In a perfect world, you'd build a second wall as decoupled as possible from his wall, and as massive as possible, and you'd damp it, and you'd add absorptive material into the cavity. Clip and channel gets you a significant degree of isolation, especially at higher frequencies. Or worst case if you can't do any isolation you just add as much mass as possible, and think seriously about damping it with Green Glue, too.


Re triple leaf, at least as I understand it, it'll degrade performance relative to having a single cavity, but should still be an improvement over not having added the additional leaf. But whether clip and channel over existing drywall makes sense, versus just putting that money into more mass (an additional layer of drywall) is worth considering, and perhaps others will weigh in with opinions about that.


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## HT Geek

niccolo said:


> In a perfect world, you'd build a second wall as decoupled as possible from his wall, and as massive as possible, and you'd damp it, and you'd add absorptive material into the cavity. Clip and channel gets you a significant degree of isolation, especially at higher frequencies. Or worst case if you can't do any isolation you just add as much mass as possible, and think seriously about damping it with Green Glue, too.
> 
> Re triple leaf, at least as I understand it, it'll degrade performance relative to having a single cavity, but should still be an improvement over not having added the additional leaf. But whether clip and channel over existing drywall makes sense, versus just putting that money into more mass (an additional layer of drywall) is worth considering, and perhaps others will weigh in with opinions about that.



Without understanding all the nuances of his particular layout (adjacent surfaces, limitations due to whatever other circumstances, etc.), my suggestions:

1. Most effective: remove drywall; install clips & hat channel; apply drywall/GG/drywall sandwich
2. Most practical solution: add 1-2 layers of drywall (preferably as drywall/GG/drywall sandwich) over existing wall surface

Make sure you seal the seams of interior drywall sheets. Finishing them is an unnecessary waste of labor and time. Just caulk them and wipe flush.

Please don't install the clips & channel onto the preexisting drywall itself. If you go the H&C route, strip the old drywall, ensure the wall interior is insulated (pink fluffy - do not compress); caulk or plug any potential flanking paths you can see while you have the interior of the wall exposed.

And one more thing... ensure you have suitable expectations before beginning any changes. You're likely to still be able to hear some noise occasionally unless you can figure out a way to enact more extreme measures. However, the ideas expressed here will provide noticeable improvements compared to no change.


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## niccolo

HT Geek said:


> Without understanding all the nuances of his particular layout (adjacent surfaces, limitations due to whatever other circumstances, etc.), my suggestions:
> 
> 1. Most effective: remove drywall; install clips & hat channel; apply drywall/GG/drywall sandwich
> 2. Most practical solution: add 1-2 layers of drywall (preferably as drywall/GG/drywall sandwich) over existing wall surface
> 
> Make sure you seal the seams of interior drywall sheets. Finishing them is an unnecessary waste of labor and time. Just caulk them and wipe flush.
> 
> Please don't install the clips & channel onto the preexisting drywall itself. If you go the H&C route, strip the old drywall, ensure the wall interior is insulated (pink fluffy - do not compress); caulk or plug any potential flanking paths you can see while you have the interior of the wall exposed.
> 
> And one more thing... ensure you have suitable expectations before beginning any changes. You're likely to still be able to hear some noise occasionally unless you can figure out a way to enact more extreme measures. However, the ideas expressed here will provide noticeable improvements compared to no change.



If losing an additional ~5" of space isn't a concern, building a second wall as decoupled from the first as possible should be more effective, and possibly cheaper, than clip and channel.


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## HT Geek

niccolo said:


> If losing an additional ~5" of space isn't a concern, building a second wall as decoupled from the first as possible should be more effective, and possibly cheaper, than clip and channel.


Depends on the details of the room, wall construction, etc. Building another wall would add more than 1/2". What's the wall made of? 2x3's? 2x4's? Wood or metal studs?

I personally prefer a minimum of 1" gap. It avoids any issues with imperfectly straight studs in wood stud construction and imperfectly square rooms in general. 1/2" is normally do-able, but it leaves less room for error and movement. Granted, if we're talking about just 1 wall surface in this case then it's likely less of a concern.

Triple-leaf effect is not ideal either:

WALL | GAP | WALL | GAP | WALL

Of course, he/she could create:

WALL | GAP | WALL | GAP | WALL | GAP | WALL

if a new wall were built with drywall on both sides. Another option (quad-leaf).

Yet another idea is a staggered stud installation. To your point one could conceivably sacrifice just a 1/2" gap with that method (relative to the existing scenario and presuming 1x drywall layer on the OP's interior wall).

Either way, a lot more data should be required for strong advice and for the OP to achieve an informed decision.

For example, a risk we haven't discussed is flanking around the perimeter, regardless of the solution. Unless the OP goes with the el-cheapo option of simply adding additional layers of drywall to the existing surface, a new flanking path may be introduced. 

Right now there isn't enough data for a holistic analysis and the solutions we are tossing out are skeletal frameworks at best. The OP would be better off - IMHO - thoroughly vetting ideas and taking his/her time to consult a number of opinions on this forum and elsewhere before taking action. The more details and discussions that are had, the more confident the OP will be proceeding in any particular direction (which of course is what we are doing... which is good... but we are still lacking many important details regarding the room, and thus all of our comments have limited value at this time).


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## niccolo

HT Geek said:


> Depends on the details of the room, wall construction, etc. Building another wall would add more than 1/2". What's the wall made of? 2x3's? 2x4's? Wood or metal studs?
> 
> I personally prefer a minimum of 1" gap. It avoids any issues with imperfectly straight studs in wood stud construction and imperfectly square rooms in general. 1/2" is normally do-able, but it leaves less room for error and movement. Granted, if we're talking about just 1 wall surface in this case then it's likely less of a concern.
> 
> Triple-leaf effect is not ideal either:
> 
> WALL | GAP | WALL | GAP | WALL
> 
> Of course, he/she could create:
> 
> WALL | GAP | WALL | GAP | WALL | GAP | WALL
> 
> if a new wall were built with drywall on both sides. Another option (quad-leaf).
> 
> Yet another idea is a staggered stud installation. To your point one could conceivably sacrifice just a 1/2" gap with that method (relative to the existing scenario and presuming 1x drywall layer on the OP's interior wall).
> 
> Either way, a lot more data should be required for strong advice and for the OP to achieve an informed decision.
> 
> For example, a risk we haven't discussed is flanking around the perimeter, regardless of the solution. Unless the OP goes with the el-cheapo option of simply adding additional layers of drywall to the existing surface, a new flanking path may be introduced.
> 
> Right now there isn't enough data for a holistic analysis and the solutions we are tossing out are skeletal frameworks at best. The OP would be better off - IMHO - thoroughly vetting ideas and taking his/her time to consult a number of opinions on this forum and elsewhere before taking action. The more details and discussions that are had, the more confident the OP will be proceeding in any particular direction (which of course is what we are doing... which is good... but we are still lacking many important details regarding the room, and thus all of our comments have limited value at this time).


Agreed on pretty much all counts.


I estimated the new wall as a 2x4 with 1" of spacing, hence the ~5" estimate. The drywall that gets hung on the wall gets hung in any scenario, so it doesn't count as additional thickness _relative_ to not doing a dual wall. 



Whether it would make sense to remove the existing drywall to avoid triple leaf is an interesting question; if I had to guess, and it's a sheer guess, leaving the drywall up would be better than removing it, for soundproofing purposes. Given a choice, the data clearly suggests it's better to have a single cavity and put any layers of drywall on the outside of the cavity, so that's the obvious prescription for _new _construction. But if drywall is already hung, whether to remove it seems less obvious (unless cost isn't a factor and space is at an extreme premium, in which case it can be removed and replaced by an equivalent layer of drywall on the face of the wall).


Staggered stud is worth considering if space is at a premium, but the coupling of the studs top and bottom reduces the isolation. Then again, clip and channel would seem to involve some coupling, too (and of course anything real-world involves _some_ coupling).



Flanking is a huge issue, i.e. the OP is presumably getting sound not only through that wall, but through the nearby ceiling, floor, and other walls, and that will become more apparent if that wall is soundproofed more.


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## HT Geek

niccolo said:


> Agreed on pretty much all counts.
> 
> I estimated the new wall as a 2x4 with 1" of spacing, hence the ~5" estimate. The drywall that gets hung on the wall gets hung in any scenario, so it doesn't count as additional thickness _relative_ to not doing a dual wall.


So, I had to laugh at myself over this. When I was reading your post on my phone... I thought you'd written .5 ... i.e., 0.5" or 1/2"... Doh!  Now, I'm following you and what you stated in that post makes more sense. LoL. 



> Whether it would make sense to remove the existing drywall to avoid triple leaf is an interesting question; if I had to guess, and it's a sheer guess, leaving the drywall up would be better than removing it, for soundproofing purposes. Given a choice, the data clearly suggests it's better to have a single cavity and put any layers of drywall on the outside of the cavity, so that's the obvious prescription for _new _construction. But if drywall is already hung, whether to remove it seems less obvious (unless cost isn't a factor and space is at an extreme premium, in which case it can be removed and replaced by an equivalent layer of drywall on the face of the wall).


Yes, I know what you mean. That's why I'm of the opinion there's not enough details known atm to provide truly informed advice. For instance, as you point out, there is almost undoubtedly already a flanking issue to begin with, and in this case - with very limited site knowledge - I tend to agree it is worth considering entertaining a triple-leaf solution (even though I try to avoid them) simply from the standpoint of being practical and not desiring to create a new flanking problem.

I'd say in this particular case, the fact the primary source of offending sound on the exterior side of the wall (from the OP's perspective) is direct firing resonance aimed at the OP. I'd say it would also be worthwhile to take a peek inside the existing wall cavity and verify it is insulated (even if a decision were made to leave the wall intact). Every bit of damping helps in that sort of scenario and you never know what the original builder did until you look. If there is no insulation inside, that would tip my rec in the direction of removing existing drywall, again regardless of the solution.



> Staggered stud is worth considering if space is at a premium, but the coupling of the studs top and bottom reduces the isolation. Then again, clip and channel would seem to involve some coupling, too (and of course anything real-world involves _some_ coupling).
> 
> Flanking is a huge issue, i.e. the OP is presumably getting sound not only through that wall, but through the nearby ceiling, floor, and other walls, and that will become more apparent if that wall is soundproofed more.


 Agreed.


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## A.T.M.

It sounds like from the OP's original post there is no insulation just an air gap on either side of the concrete wall in the middle and 1/2" DW on each of the living quarters (please correct me if I am wrong). The only structural uncertainty in the explanation seems to be if the "concrete" wall is a concrete masonry unit= cinder/hollow/breeze block wall- or if it is a solid concrete wall-- no insulation options with either choice. Either way I think insulation is a must in any direction that is taken, but you'll need more than an inch of it.

You could always hang your TV on _his_ wall but that will interfere with your sound when you watch TV OR to be evil; while your soundproofing your side you could install some speakers inside the wall facing his side.  j/k- no need to start a war, just write a letter every week to the HOA board and call them every other week or every time you hear a noise. The police would also be a pain for him (here if you get 3 complaints) it's a 1000 bucks. 

Aaron


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## DoofusOfDeath

It might also help to know the power spectrum of the OP's offending sounds. I suspect that's pretty dependent on the particulars of the neighbor's TV's speakers and viewing habits.

If the offending sounds are mostly above 2 kHz, for example, there's perhaps a stronger case for starting with easy/simple approaches that only work at those higher frequencies.


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## troyh4

In a few years , I plan on buying a new house. The house that I am interested in has a great bonus room upstairs.
I will ask the builder to not finish out the room so me and a friend can get up there and finish it out like I want.
So my question is I definately want to soundproof this room from the rest of the house. I have read this forum and other online articles on what is involved in doing this. My question is If I decide to do the resilient channel and sound isolation clip process, what do I need to do when I go to put my two pieces of 5/8" sheetrock together? I read that you can use GREEN GLUE in between the two layers of sheetrock and or insert sheets of MASS LOADED VINYL's (MLV) in between the sheetrock. PLEASE explain to me do put both in between ? or just one of the other products in between the sheetrock?
Any clarification is apprciated,
Thanks,


----------



## Ladeback

troyh4 said:


> In a few years , I plan on buying a new house. The house that I am interested in has a great bonus room upstairs.
> I will ask the builder to not finish out the room so me and a friend can get up there and finish it out like I want.
> So my question is I definately want to soundproof this room from the rest of the house. I have read this forum and other online articles on what is involved in doing this. My question is If I decide to do the resilient channel and sound isolation clip process, what do I need to do when I go to put my two pieces of 5/8" sheetrock together? I read that you can use GREEN GLUE in between the two layers of sheetrock and or insert sheets of MASS LOADED VINYL's (MLV) in between the sheetrock. PLEASE explain to me do put both in between ? or just one of the other products in between the sheetrock?
> Any clarification is apprciated,
> Thanks,


I haven't done any soundproofing yet, but been on soundproofing company's website and it would be a big help to you and asking questions, but you only need to do either not both. If it was me I would use the Green Glue on the ceiling at least so don't have to attach it to keep it in place. The channel you want is Hat channel with the clues, not resilient channel. I would look to find ot locally to save on shipping and it getting bent. Are you going to decouple the walls from the ceiling?


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## 1mageWIS

A.T.M. said:


> It sounds like from the OP's original post there is no insulation just an air gap on either side of the concrete wall in the middle and 1/2" DW on each of the living quarters (please correct me if I am wrong). The only structural uncertainty in the explanation seems to be if the "concrete" wall is a concrete masonry unit= cinder/hollow/breeze block wall- or if it is a solid concrete wall-- no insulation options with either choice. Either way I think insulation is a must in any direction that is taken, but you'll need more than an inch of it.
> 
> You could always hang your TV on _his_ wall but that will interfere with your sound when you watch TV OR to be evil; while your soundproofing your side you could install some speakers inside the wall facing his side.  j/k- no need to start a war, just write a letter every week to the HOA board and call them every other week or every time you hear a noise. The police would also be a pain for him (here if you get 3 complaints) it's a 1000 bucks.
> 
> Aaron


Correct, there is no insulation at all. I have no idea what kind of concret the blocks are made out of or how thick. A picture of the wall is attached. There is flanking noise from the right wall, but not from the left wall. How would I get rid of the flanking noise?


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## niccolo

1mageWIS said:


> Correct, there is no insulation at all. I have no idea what kind of concret the blocks are made out of or how thick. A picture of the wall is attached. There is flanking noise from the right wall, but not from the left wall. How would I get rid of the flanking noise?


Same principles apply to addressing flanking noise as non-flanking noise: isolation, mass, damping, absorption, and they work best in concert with each other. 



Part of your challenge is that since you can't treat the source of the sound (the room where it's coming from), you have to treat all the other places the sound flows from there, and that may be multiple walls or even multiple rooms.


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## 1mageWIS

niccolo said:


> Same principles apply to addressing flanking noise as non-flanking noise: isolation, mass, damping, absorption, and they work best in concert with each other.
> 
> 
> 
> Part of your challenge is that since you can't treat the source of the sound (the room where it's coming from), you have to treat all the other places the sound flows from there, and that may be multiple walls or even multiple rooms.


I can do that to one wall, but to do it to the flanking wall is really problematic, since it's actually arching around a large sliding glass window. 

I could do something about the room where it's coming from, as soon as murder is legal.


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## niccolo

1mageWIS said:


> I can do that to one wall, but to do it to the flanking wall is really problematic, since it's actually arching around a large sliding glass window.
> 
> I could do something about the room where it's coming from, as soon as murder is legal.


When you open things up, I wonder whether you might be able to decouple the flanking wall to some extent? Even if not, I'm guessing the main wall poses the majority of your issue, especially since we're talking about somewhat higher frequency content, not subwoofer output you're trying to contain.


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## 1mageWIS

niccolo said:


> When you open things up, I wonder whether you might be able to decouple the flanking wall to some extent? Even if not, I'm guessing the main wall poses the majority of your issue, especially since we're talking about somewhat higher frequency content, not subwoofer output you're trying to contain.


That is the question. If you look at the pic I posted the wall with flanking, which is on the right is an exterior wall, so I assume there's basically just a 1 or 2" air gap between the brick and drywall there as well. My guess is that the sound is resonating in there in the air gap, and if I were to plug that up with mineral wool and maybe a strip of MLV, that might help the flanking noise? I assume there are some low frequencies that are coming through, even if they are weak flat screen speakers... 

Additionally, it just dawned on me: I have popcorn ceilings and tile floors... and the new drywall will certainly be past where the current wall is, can I place the 'floating' wall above the tile? I'm going to place baseboard as well, so I wonder if I have to cut the tile as well?


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## A.T.M.

niccolo said:


> When you open things up, I wonder whether you might be able to decouple the flanking wall to some extent? Even if not, I'm guessing the main wall poses the majority of your issue, especially since we're talking about somewhat higher frequency content, not subwoofer output you're trying to contain.





1mageWIS said:


> That is the question. If you look at the pic I posted the wall with flanking, which is on the right is an exterior wall, so I assume there's basically just a 1 or 2" air gap between the brick and drywall there as well. My guess is that the sound is resonating in there in the air gap, and if I were to plug that up with mineral wool and maybe a strip of MLV, that might help the flanking noise? I assume there are some low frequencies that are coming through, even if they are weak flat screen speakers...
> 
> Additionally, it just dawned on me: I have popcorn ceilings and tile floors... and the new drywall will certainly be past where the current wall is, can I place the 'floating' wall above the tile? I'm going to place baseboard as well, so I wonder if I have to cut the tile as well?


I think Niccolo is right, because you're dealing with flatscreen's speakers; we're mainly looking at higher frequencies (fortunately for you, not in the 10-300 Hz range). Your visible wall is already Pseudo decoupled from the concrete wall with the 1-2 " gap. I think the sound that is reaching your main wall is traveling down the 1-2" gap (like you said) that likely continues on the flanking external wall. If you added insulation, Owens Corning/ Thermafiber or roux safe and sound etc...(both probably equally effective at higher frequencies) may help some with the flanking wall sounds if placed in both walls.

I think your best bet will be to take down your dry wall on main and flanking walls and to:

*Main wall* decouple the wall using hat channels with clips, Absorb _some_ sound by using insulation, add mass with 2 layers of Drywall (DW), and dampen the vibrations with Green glue (GG) in between the 2 layers of DW.

*Flanking wall*
Absorb some sound by using insulation, add mass with 2 layers of Drywall (DW), and dampen the vibrations with Green glue (GG) in between the 2 layers of DW.

There's normally a decrease in sound attenuation at around 1600-3500 Hz (especially at 2000-2500 hz) and putting more than 2 layers of DW doesn't help that much~probably a 6db attenuation difference between 2 layers and 4 layers of DW. That is why GG is going to be very important for your situation. When sandwiched between DW/GG/DW it provides excellent results, ~18db attenuation difference, in that frequency range. 

I would only cut the tile if you think that the sound is transferring up from the flooring--The tile may go the studs but shouldn't go to the concrete. Put your ear to it next time your neighbor is obnoxious and see, I'd be interested in what you find.

If all of this Doesn't help-- you could get a long concrete drill bit, drill through the concrete at the top of the wall where it meets the ceiling, go all the way to his side without breaking through his DW, inject red food coloring at the top of his DW, inject water and create a "shining" like effect (Blood dripping down the walls)--maybe you could scare him into moving out 

Aaron


----------



## 1mageWIS

A.T.M. said:


> I think Niccolo is right, because you're dealing with flatscreen's speakers; we're mainly looking at higher frequencies (fortunately for you, not in the 10-300 Hz range). Your visible wall is already Pseudo decoupled from the concrete wall with the 1-2 " gap. I think the sound that is reaching your main wall is traveling down the 1-2" gap (like you said) that likely continues on the flanking external wall. If you added insulation, Owens Corning/ Thermafiber or roux safe and sound etc...(both probably equally effective at higher frequencies) may help some with the flanking wall sounds if placed in both walls.
> 
> I think your best bet will be to take down your dry wall on main and flanking walls and to:
> 
> *Main wall* decouple the wall using hat channels with clips, Absorb _some_ sound by using insulation, add mass with 2 layers of Drywall (DW), and dampen the vibrations with Green glue (GG) in between the 2 layers of DW.
> 
> *Flanking wall*
> Absorb some sound by using insulation, add mass with 2 layers of Drywall (DW), and dampen the vibrations with Green glue (GG) in between the 2 layers of DW.
> 
> There's normally a decrease in sound attenuation at around 1600-3500 Hz (especially at 2000-2500 hz) and putting more than 2 layers of DW doesn't help that much~probably a 6db attenuation difference between 2 layers and 4 layers of DW. That is why GG is going to be very important for your situation. When sandwiched between DW/GG/DW it provides excellent results, ~18db attenuation difference, in that frequency range.
> 
> I would only cut the tile if you think that the sound is transferring up from the flooring--The tile may go the studs but shouldn't go to the concrete. Put your ear to it next time your neighbor is obnoxious and see, I'd be interested in what you find.
> 
> If all of this Doesn't help-- you could get a long concrete drill bit, drill through the concrete at the top of the wall where it meets the ceiling, go all the way to his side without breaking through his DW, inject red food coloring at the top of his DW, inject water and create a "shining" like effect (Blood dripping down the walls)--maybe you could scare him into moving out
> 
> Aaron


I can't add mass or decouple the flanking wall with noise due to the sliding window in the way. The best I can do is seal up the air gap between the drywall and exterior wall. 

I can decouple the main offending wall, but I'm concerned about the tile flooring and the popcorn ceiling when it comes to installing the actual drywall, as the new 2x4's and clips + hat channels will push the wall further out than it is now.


----------



## A.T.M.

1mageWIS said:


> I can't add mass or decouple the flanking wall with noise due to the sliding window in the way. The best I can do is seal up the air gay between the drywall and exterior wall.
> 
> I can decoplus the main offending wall, but I'm concerned about the tile flooring and the popcorn ceiling when it comes to installing the actual drywall, as the new 2x4's and clips + hat channels will push the wall further out than it is now.


What is worrisome about the tile floor and the ceiling?
Sorry if I am a bit slow and am not realizing something.

For the main wall:

You can use the same 2 x 4 framing you already have and when you put the hat channels and clips up you will attach the 2 layers of DW and GG to the channels, not the floor/ceiling or the 2 x 4 's; so the only real connection between the wall and the ceiling or the tile floor will be acoustic caulking (+/- mud and tape for the ceiling). For the floor the the baseboard will be in contact with the tile and the drywall. I would have the DW float about 1/16" or (whatever is code) above the tile. Therefore, you don't need to cut the ceiling or tile floor as the 2x4's are not moving.

Can you attach a pic of the window and the trim up close?

Thanks

Aaron


----------



## impmonkey

Some good info here.


----------



## mhutchins

I just watched most of the video above and I have to say there is more misinformation than valid building tips. From ignoring flanking paths to promoting a triple-leaf wall design, this guy shouldn't be allowed anywhere close to a home theater. Do not do anything he says. He does not understand the basic concepts of sound isolation beyond higher STC is better.

Mike


----------



## Ladeback

mhutchins said:


> I just watched most of the video above and I have to say there is more misinformation than valid building tips. From ignoring flanking paths to promoting a triple-leaf wall design, this guy shouldn't be allowed anywhere close to a home theater. Do not do anything he says. He does not understand the basic concepts of sound isolation beyond higher STC is better.
> 
> Mike


I just finished watching this and thought why is putting drywall between the two walls and didn't really show decoupling the inner wall from the ceiling above. There are better ways to do it and the soundproofing company has diagrams to show you how.


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## mhutchins

A few examples of bad practice or misinformation:

4:30 Only 2 elements to soundproofing: 1) Cancellation - the holes in resilient channel break up the big sound waves into lots of smaller waves that cancel each other out.
2) The best is absorption with fiberglass and 2 layers of 5/8" drywall. No mention of mass, decoupling or damping. Arghhh. He has no clue how little he understands!

13:48 Green Glue works by creating an air gap between the two layers of drywall. No mention of visco-elastic damping!

14:30 Apply Green Glue evenly in a pattern and use 1 tube per sheet of 4x8 drywall

18:40 How to make a Triple Leaf wall system 

22:18 How to create flanking paths through your drywall envelope.

24:49 Resilient channel and hat channel are equivalent.

It's like a recipe for what not to do.


Mike


----------



## mackstann

I'm wondering about some finer points of flanking through framing. I'm building a room in my basement. My main concern is the ceiling. It'll have floating ceiling joists. The joist ends could rest on the mud sill, and the new framed walls could attach to the new joists. Would sound transmit from the upstairs joists, through the mud sill, and into the new joists? Or is the mud sill so solid that this is not a concern (since it's laying on concrete and compressed by all the building's weight on it)? It's not floating in air like a joist or stud is, so I wouldn't think it would vibrate in the same way. If it is a problem, I could instead attach the basement stud walls to the concrete walls and use them to support the new ceiling joists, but anchoring into concrete is a bit more of a pain.

Question 2: One of the walls will basically fill in the (6x6) posts & (6x8) beams that run down the center of the basement. The ceiling joist ends will also rest on the beams. Will sound from upstairs transmit down through these large framing members? Or are they so solid and heavy that it's not a concern?


----------



## Ladeback

mackstann said:


> I'm wondering about some finer points of flanking through framing. I'm building a room in my basement. My main concern is the ceiling. It'll have floating ceiling joists. The joist ends could rest on the mud sill, and the new framed walls could attach to the new joists. Would sound transmit from the upstairs joists, through the mud sill, and into the new joists? Or is the mud sill so solid that this is not a concern (since it's laying on concrete and compressed by all the building's weight on it)? It's not floating in air like a joist or stud is, so I wouldn't think it would vibrate in the same way. If it is a problem, I could instead attach the basement stud walls to the concrete walls and use them to support the new ceiling joists, but anchoring into concrete is a bit more of a pain.
> 
> Question 2: One of the walls will basically fill in the (6x6) posts & (6x8) beams that run down the center of the basement. The ceiling joist ends will also rest on the beams. Will sound from upstairs transmit down through these large framing members? Or are they so solid and heavy that it's not a concern?


Flanking can be fun to deal with. Sound can make most things vibrate and bass will be the tough one to deal with. This is long, but may help with understanding flanking.

https://www.tmsoundproofing.com/understanding-flanking-noise.html


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## DreamingOfHT

Hi everyone,
I've moved to a new house with an existing finished basement. I'm working on 2 18" driver full Marty subs for the HT. My setup is an open, approximately 1000 ft2 finished space with the HT at one end. Two walls are framed against the foundation concrete and seem pretty solid; one divider wall with a solid core door to the mechanical room; and the back is open to the rest of the basement. The basement stairs are open to the 1st floor. 

I'm worried about the big subs lighting up the 1/2" drywall ceiling and mechanical room wall. Ceiling and dividing wall have metal studs (ceiling is dropped to clear duct work). Ceiling has 6-9 inches of pink fiberglass directly on top of the drywall.

Is this a valid concern?

I'm moving the divider wall to make room for speakers on either side of the screen. I could get 3+" of added headroom by redoing the ceiling (currently hung at 6'10"). 

Do you think there's much to gain accoustically to justify the cost of Roxul in the ceiling, doubling the drywall with GG on the divider wall, tearing out the existing ceiling, etc? I can't make a sound proof room. I'm trying to make a space free of rattling and can sound good after equalization.

Any feedback is welcome. Thanks


----------



## jjcook

For my small second floor DD+GG+clips/channel soundproofed room in progress, I am considering building DIY ULF subwoofers above the theater in the attic (save space in room) for bass content less than 40-50Hz where I will have enough space to build large dual-opposed ported enclosures with a 12-17Hz port tune, something like a LLT built using 2 layers MDF/plywood with GG. I am considering to build the enclosures in-place with independent "framing" and have them rest on rubber mat strips on top of the room's non-decoupled framing and with rubber isolated screws to secure (similar to wall sill plate isolation). Let us assume I've done the structural math so the room framing can support the weight.

1. When these attic ULF subwoofers are NOT in use will I be sacrificing my soundproofing? (if using the appropriate rubber isolation pad; how about horse stall mats?)

2. Is there any point to building an independent backer box around these beasts? I presume when they are in use the backer box will be ineffective and when not in use the enclosure is already effectively a backer box.


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## MordredKLB

Hey guys, I'm doing an extensive remodel on a house, and adding a 2nd story which will have an open media room, and two kids bedrooms. I'm attaching the floorplan. This is an open room, so I'm not even going to attempt to really soundproof things, but I would like to minimize sound leakage into the two bedrooms. If I can drop the volume 30dB-40dB between the rooms I'll consider that a win. Anything more than that is just gravy.

I'm looking for advice for the things I absolutely _need_ to do. Budget is a strong consideration unfortunately and the large size of the room makes that even more of an issue.

I'm already planning to do double-drywall and green glue along the walls of the main theater area. I'll also be installing solid core doors to the kids bedrooms. I'm doing inwall speakers for the surrounds and will be putting Dynaboxes around those as well. I don't have the budget for clip and hat.

I know I can afford to add acoustiseal around the top and bottom of the drywall, as well as around gang boxes, but not sure if that's even worth doing if I've got a lot of sound leakage elsewhere. Anything else I should consider?


----------



## niccolo

MordredKLB said:


> Hey guys, I'm doing an extensive remodel on a house, and adding a 2nd story which will have an open media room, and two kids bedrooms. I'm attaching the floorplan. This is an open room, so I'm not even going to attempt to really soundproof things, but I would like to minimize sound leakage into the two bedrooms. If I can drop the volume 30dB-40dB between the rooms I'll consider that a win. Anything more than that is just gravy.
> 
> I'm looking for advice for the things I absolutely _need_ to do. Budget is a strong consideration unfortunately and the large size of the room makes that even more of an issue.
> 
> I'm already planning to do double-drywall and green glue along the walls of the main theater area. I'll also be installing solid core doors to the kids bedrooms. I'm doing inwall speakers for the surrounds and will be putting Dynaboxes around those as well. I don't have the budget for clip and hat.
> 
> I know I can afford to add acoustiseal around the top and bottom of the drywall, as well as around gang boxes, but not sure if that's even worth doing if I've got a lot of sound leakage elsewhere. Anything else I should consider?


Is staggered stud an option? The additional labor and materials are modest, the walls would be an inch or two thicker (depending on how thick you made the framing footer), and you'd get a lot of additional decoupling, comparable to clip and hat (if I recall correctly, staggered stud is a bit better at containing lower frequencies and a bit less good at higher frequencies, all things equal). That mass and damping you're already planning to add will do its job a lot better if you can add some decoupling.


https://www.soundproofingcompany.com/soundproofing101/building-a-staggered-stud-wall/


That said, what you do on the walls is limited by the huge flanking issues, including via the floor and ceiling if they're coupled to the framing. But it's at least worth thinking about whether some decoupling of the floor and ceiling might be feasible, too. And even if you can't treat the floor and ceiling, at least for the higher frequencies I suspect you'll still benefit quite a bit from treating the walls.


----------



## MordredKLB

niccolo said:


> Is staggered stud an option? The additional labor and materials are modest, the walls would be an inch or two thicker (depending on how thick you made the framing footer), and you'd get a lot of additional decoupling, comparable to clip and hat (if I recall correctly, staggered stud is a bit better at containing lower frequencies and a bit less good at higher frequencies, all things equal). That mass and damping you're already planning to add will do its job a lot better if you can add some decoupling.
> 
> 
> https://www.soundproofingcompany.com/soundproofing101/building-a-staggered-stud-wall/
> 
> 
> That said, what you do on the walls is limited by the huge flanking issues, including via the floor and ceiling if they're coupled to the framing. But it's at least worth thinking about whether some decoupling of the floor and ceiling might be feasible, too. And even if you can't treat the floor and ceiling, at least for the higher frequencies I suspect you'll still benefit quite a bit from treating the walls.


Yeah, I suppose I should have been more clear. All the framing is already done, and I've already got most of it wired for in-wall/in-ceiling speakers (I'm going to have boxes). I think it's too late to do anything with the decoupling. We're probably less than 2 weeks out from drywall starting to go up.

The staggered stud is an interesting idea and I wish I'd heard of it earlier. Not sure I could have afforded it, but would have been nice to get a quote.

One question I've got. I installed low-voltage brackets into the walls in a couple places bordering the bedrooms. Those are open backed, so I'm not quite sure how to go about preventing sound leaking through them. Doesn't seem like the putty pads would work on them and acoustical seal seems pointless. Should I rip those out and install normal electrical gang boxes?


----------



## mattztt

MordredKLB said:


> One question I've got. I installed low-voltage brackets into the walls in a couple places bordering the bedrooms. Those are open backed, so I'm not quite sure how to go about preventing sound leaking through them. Doesn't seem like the putty pads would work on them and acoustical seal seems pointless. Should I rip those out and install normal electrical gang boxes?


I would rip them out. I used low voltage brackets for the networks drops throughout my house but the LV drops in the theater got standard electrical boxes so I could seal and putty them.


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## MordredKLB

mattztt said:


> I would rip them out. I used low voltage brackets for the networks drops throughout my house but the LV drops in the theater got standard electrical boxes so I could seal and putty them.


I went ahead and made that call this weekend. Need to order the putty pads though.

I've seen that it's best to use Acoustic Seal where the first layer of drywall meets the floor and ceiling. Should this be done on the other side of a wall shared with the theater which doesn't have double drywall? i.e.:

Home Theater -> drywall -> Green Glue -> drywall (with acoustic seal at floor and ceiling) -> stud cavity -> single layer drywall (*do I need acoustic seal on this side?*)


----------



## mattztt

MordredKLB said:


> I've seen that it's best to use Acoustic Seal where the first layer of drywall meets the floor and ceiling. Should this be done on the other side of a wall shared with the theater which doesn't have double drywall? i.e.:
> 
> Home Theater -> drywall -> Green Glue -> drywall (with acoustic seal at floor and ceiling) -> stud cavity -> single layer drywall (*do I need acoustic seal on this side?*)


It certainly won't hurt though at some point you're getting into diminishing returns. For my build after the drywall was put in on the opposite side of the wall I went through and sealed any visible gaps along the sill plate from the inside of the wall.


----------



## barfle

There's almost 3,000 posts on this forum, so forgive me if I missed seeing the answer to this concern.

I have a room that's adequately isolated from other sound sources (double-stud, solid door, etc.). Alas, the main source of noise is the HVAC vent. I can turn off the furnace fan, but it doesn't take the length of a movie for it to get too hot, too cold, or too stuffy, so I'm putting up with it.

What I'd like, of course, is a vent that doesn't make noise, but my searches haven't found one (other than a booster fan that just says its fan is quiet). Barring that, I could redo the vent track (furnace is about 20' from the HT room), but I'd like some assurance that it would work before I spend the money and effort.

Thanks in advance for any suggestions!


----------



## mattztt

barfle said:


> There's almost 3,000 posts on this forum, so forgive me if I missed seeing the answer to this concern.
> 
> I have a room that's adequately isolated from other sound sources (double-stud, solid door, etc.). Alas, the main source of noise is the HVAC vent. I can turn off the furnace fan, but it doesn't take the length of a movie for it to get too hot, too cold, or too stuffy, so I'm putting up with it.
> 
> What I'd like, of course, is a vent that doesn't make noise, but my searches haven't found one (other than a booster fan that just says its fan is quiet). Barring that, I could redo the vent track (furnace is about 20' from the HT room), but I'd like some assurance that it would work before I spend the money and effort.
> 
> Thanks in advance for any suggestions!


Are you hearing the furnace itself or the movement of the air through the vent?

A noisy vent where the noise is coming from the movement of air through that vent is moving too much air too quickly. If you can increase the size of the vent (possibly including the ducting leading to the vent) or split the air supply with an additional vent you'll likely quiet the noise.

If the problem is that the vent is transmitting noise from the furnace then you need to introduce a convoluted path for the air to follow so that noise dissipates before it gets into the room.

A third possibility is vibration of the vent which can be addressed with Dynamat or similar products.


----------



## barfle

mattztt said:


> Are you hearing the furnace itself or the movement of the air through the vent?
> 
> A noisy vent where the noise is coming from the movement of air through that vent is moving too much air too quickly. If you can increase the size of the vent (possibly including the ducting leading to the vent) or split the air supply with an additional vent you'll likely quiet the noise.
> 
> If the problem is that the vent is transmitting noise from the furnace then you need to introduce a convoluted path for the air to follow so that noise dissipates before it gets into the room.
> 
> A third possibility is vibration of the vent which can be addressed with Dynamat or similar products.


It's mostly the noise from the air moving through the vent, not the sound of the furnace itself (although, of course when you fix the obvious problem, the next most obvious problem shows up!).

It sounds like it's going to take some duct work  but if that's what it takes, well, time to buck up and do the work. Thanks for the suggestion of multiple vents, that's the direction I'll go.


----------



## niccolo

barfle said:


> It's mostly the noise from the air moving through the vent, not the sound of the furnace itself (although, of course when you fix the obvious problem, the next most obvious problem shows up!).
> 
> It sounds like it's going to take some duct work  but if that's what it takes, well, time to buck up and do the work. Thanks for the suggestion of multiple vents, that's the direction I'll go.


When you pop out the vent cover, does the noise go away? I'm having a hard time imagining a residential HVAC system that moves so much air that it makes an audible, distracting noise coming through the vent.


----------



## ScottieBoysName

I have a door leading to my theater that I want to insulate/dampen better. I have seals running around all of the edges of the door but the floor (no threshold yet) so I know I need to get on that. 

It's a 36 inch solid core door. Would building an acoustic panel over the door help? Attaching drywall to the door help? What should be my next step?


----------



## mhutchins

Automatic door bottom


----------



## ncabw

How much sound would travel through an open hole in the ceiling the size of a receptacle box? I have done DD GG inveterate the joists. And DD GG blue clips for the ceiling. Pretty happy with the sound results but haven’t yet patched the last hole. Out of curiosity was wondering how much sound actually goes through and what kind of difference it will make. 

Also I have one solid door with a door drop and seals all around. I was thinking of adding a second to finish everything off. 




Sent from my iPhone using Tapatalk


----------



## HT Geek

ScottieBoysName said:


> I have a door leading to my theater that I want to insulate/dampen better. I have seals running around all of the edges of the door but the floor (no threshold yet) so I know I need to get on that.
> 
> It's a 36 inch solid core door. Would building an acoustic panel over the door help? Attaching drywall to the door help? What should be my next step?





mhutchins said:


> Automatic door bottom


I agree with Mike. You should invest in an automatic door bottom.

That said, if you only have a standard, single solid core door and you want to dampen it further, adding mass is a common approach. You've only got two realistic options: add mass and/or sound proofing material such as dense insulation (e.g. OC 703/704/705). Aside from aesthetic effects, they are going to help similar (but not quite identical) problems.

Adding density (weight/mass) does a great job of reducing bass passthru. If you want to curb reflections inside the room, the fiberglass is going to be a better bet.

Also, keep in mind that sound proofing often becomes a bit of a whack-a-mole game. You reinforce one area and it exposes weaknesses in others, or it makes other portions of your setup appear weak. For example, if you beef up your door you might then notice sound bleeding through an adjacent wall that wasn't as apparent as before. Just something to bear in mind. I'm saying this with no knowledge of your overall configuration, so please take that advice FWIW. 

I would go with Mike's suggestion first, and compare the before/after impact. Perhaps you'll be satisfied with the result and not feel the need to go further. Everyone's scenario is unique.


----------



## HT Geek

ncabw said:


> How much sound would travel through an open hole in the ceiling the size of a receptacle box? I have done DD GG inveterate the joists. And DD GG blue clips for the ceiling. Pretty happy with the sound results but haven’t yet patched the last hole. Out of curiosity was wondering how much sound actually goes through and what kind of difference it will make.
> 
> Also I have one solid door with a door drop and seals all around. I was thinking of adding a second to finish everything off.


That's kind of a loaded question. It depends....  I would plug it. You risk compromising your hard work.

Imagine sound is water, and you're going to have the "water" moving through the hole. Sound is going to find its way though that hole, between the spaces on either side of it. 

Are you concerned about sound coming into the room or exiting your theater room?

Whether or not it will bother you depends on a number of factors. For instance, what is above your HT room? If it's an attic, you'll get intrusion from outdoor noises coming in, and some of your room's sound will leak out that route (though the latter may not be a big deal for you). If it's another room, you may bother folks in there while watching a loud movie or listening to loud music, and/or someone in the HT room may get annoyed with their experience being disturbed by sound leaking in.

Generally speaking... and applying Murphy's Law.... if you don't address it, you'll likely regret that once your room is finished. I'd plug it (using appropriate techniques, relative to your scenario).


----------



## ScottieBoysName

HT Geek said:


> I agree with Mike. You should invest in an automatic door bottom.
> 
> 
> 
> That said, if you only have a standard, single solid core door and you want to dampen it further, adding mass is a common approach. You've only got two realistic options: add mass and/or sound proofing material such as dense insulation (e.g. OC 703/704/705). Aside from aesthetic effects, they are going to help similar (but not quite identical) problems.
> 
> 
> 
> Adding density (weight/mass) does a great job of reducing bass passthru. If you want to curb reflections inside the room, the fiberglass is going to be a better bet.
> 
> 
> 
> Also, keep in mind that sound proofing often becomes a bit of a whack-a-mole game. You reinforce one area and it exposes weaknesses in others, or it makes other portions of your setup appear weak. For example, if you beef up your door you might then notice sound bleeding through an adjacent wall that wasn't as apparent as before. Just something to bear in mind. I'm saying this with no knowledge of your overall configuration, so please take that advice FWIW.
> 
> 
> 
> I would go with Mike's suggestion first, and compare the before/after impact. Perhaps you'll be satisfied with the result and not feel the need to go further. Everyone's scenario is unique.




Thanks all!


----------



## ScottieBoysName

HT Geek said:


> I agree with Mike. You should invest in an automatic door bottom.
> 
> 
> 
> That said, if you only have a standard, single solid core door and you want to dampen it further, adding mass is a common approach. You've only got two realistic options: add mass and/or sound proofing material such as dense insulation (e.g. OC 703/704/705). Aside from aesthetic effects, they are going to help similar (but not quite identical) problems.
> 
> 
> 
> Adding density (weight/mass) does a great job of reducing bass passthru. If you want to curb reflections inside the room, the fiberglass is going to be a better bet.
> 
> 
> 
> Also, keep in mind that sound proofing often becomes a bit of a whack-a-mole game. You reinforce one area and it exposes weaknesses in others, or it makes other portions of your setup appear weak. For example, if you beef up your door you might then notice sound bleeding through an adjacent wall that wasn't as apparent as before. Just something to bear in mind. I'm saying this with no knowledge of your overall configuration, so please take that advice FWIW.
> 
> 
> 
> I would go with Mike's suggestion first, and compare the before/after impact. Perhaps you'll be satisfied with the result and not feel the need to go further. Everyone's scenario is unique.




Thanks all!


----------



## 1mageWIS

HT Geek said:


> Without understanding all the nuances of his particular layout (adjacent surfaces, limitations due to whatever other circumstances, etc.), my suggestions:
> 
> 1. Most effective: remove drywall; install clips & hat channel; apply drywall/GG/drywall sandwich
> 2. Most practical solution: add 1-2 layers of drywall (preferably as drywall/GG/drywall sandwich) over existing wall surface
> 
> Make sure you seal the seams of interior drywall sheets. Finishing them is an unnecessary waste of labor and time. Just caulk them and wipe flush.
> 
> Please don't install the clips & channel onto the preexisting drywall itself. If you go the H&C route, strip the old drywall, ensure the wall interior is insulated (pink fluffy - do not compress); *caulk or plug any potential flanking paths you can see while you have the interior of the wall exposed.*
> 
> And one more thing... ensure you have suitable expectations before beginning any changes. You're likely to still be able to hear some noise occasionally unless you can figure out a way to enact more extreme measures. However, the ideas expressed here will provide noticeable improvements compared to no change.


Err, I just re-read your post and have a question.

As an update: I went ahead opened the wall, removed the 3/4" furring strips, built a new stud frame using 23" spaced 25 gauge metal studs (wall is only 8' x 13' and non-load bearing) (the reason the studs are 23" is because I used 3" thick Rockwool Safe n Sound and I was completely unable to find the steel stud version, and ended up creatively using the wood stud version, which is actually 23" wide; it was placed friction fit and not compressed). 

Then added PAC Intl (who as an aside were great at offering info and tech support, even for my tiny project) RSIC-1 isolation clips and attached 25 gauge hat channels to the clips.

The first layer of 5/8" sheet rock was installed today, leaving a 1/8" - 1/4" gap (the walls are beyond the normal 'not straight' kind), it was taped and mudded, and GG Acoustical Caulk was placed around the perimeter. 

In regards to flanking sounds:

I did cut a small bit of Rockwool Safe n Sound and put it into the only small crevice it would fit into on one of the flanking walls, the other flaking wall had ZERO space to, for lack of a better term, shove insulation into it. Both had metal studs right at the edge of where the 'party wall' was. 

I still haven't installed the GG and second layer of 5/8" yet, but no TV was audible noise this evneing directly from the wall, but am now worried about the flanking paths... :-/ 

In the future, how could I go about caulking or plugging flanking paths? Especially when there doesn't seem to be any space to do so?


----------



## jjcook

jjcook said:


> For my small second floor DD+GG+clips/channel soundproofed room in progress, I am considering building DIY ULF subwoofers above the theater in the attic (save space in room) for bass content less than 40-50Hz where I will have enough space to build large dual-opposed ported enclosures with a 12-17Hz port tune, something like a LLT built using 2 layers MDF/plywood with GG. I am considering to build the enclosures in-place with independent "framing" and have them rest on rubber mat strips on top of the room's non-decoupled framing and with rubber isolated screws to secure (similar to wall sill plate isolation). Let us assume I've done the structural math so the room framing can support the weight.
> 
> 1. When these attic ULF subwoofers are NOT in use will I be sacrificing my soundproofing? (if using the appropriate rubber isolation pad; how about horse stall mats?)
> 
> 2. Is there any point to building an independent backer box around these beasts? I presume when they are in use the backer box will be ineffective and when not in use the enclosure is already effectively a backer box.


Any soundproofing feedback on this plan?


----------



## Ladeback

jjcook said:


> Any soundproofing feedback on this plan?


Not sure this will help with the soundproofing, but maybe how to get them in to the ceiling.

I would contact d_c if you have any questions. I have been in this room a few times and it is awesome. He has a dedicated theater in the basement as well.

https://www.avsforum.com/forum/155-diy-speakers-subs/1495785-doug-s-dual-gjallarhorn-build.html


----------



## HT Geek

1mageWIS said:


> Err, I just re-read your post and have a question.
> 
> As an update: I went ahead opened the wall, removed the 3/4" furring strips, built a new stud frame using 23" spaced 25 gauge metal studs (wall is only 8' x 13' and non-load bearing) (the reason the studs are 23" is because I used 3" thick Rockwool Safe n Sound and I was completely unable to find the steel stud version, and ended up creatively using the wood stud version, which is actually 23" wide; it was placed friction fit and not compressed).
> 
> Then added PAC Intl (who as an aside were great at offering info and tech support, even for my tiny project) RSIC-1 isolation clips and attached 25 gauge hat channels to the clips.



That's all good ^^^^




> The first layer of 5/8" sheet rock was installed today, leaving a 1/8" - 1/4" gap (the walls are beyond the normal 'not straight' kind), it was taped and mudded, and GG Acoustical Caulk was placed around the perimeter.



Hmm. Well, FYI for next time... you do not need to tape the inner (1st) layer of drywall. Just mudding or caulking the seams is sufficient since it gets covered up, but no matter. Sometimes it's tough to get that across to the drywall guys if you're paying for pro install. They're not used to thinking about it in that manner.

When you say there was a 1/8" - 1/4" gap, where is the gap you're referring to? The perimeter around the drywall, or did you mean somewhere else?




> In regards to flanking sounds:
> 
> I did cut a small bit of Rockwool Safe n Sound and put it into the only small crevice it would fit into on one of the flanking walls, the other flaking wall had ZERO space to, for lack of a better term, shove insulation into it. Both had metal studs right at the edge of where the 'party wall' was.
> 
> I still haven't installed the GG and second layer of 5/8" yet, but no TV was audible noise this evneing directly from the wall, but am now worried about the flanking paths... :-/
> 
> In the future, how could I go about caulking or plugging flanking paths? Especially when there doesn't seem to be any space to do so?



For really small gaps, just use acoustical caulk. The cheapest stuff you can get is typically OC-175. Home Depot sells it for ~$80 for a 12-pack of the big tubes (28 oz.). Last time I ordered it from them the shipping was free.

There's also a Green Glue equivalent of acoustic caulk, called Green Glue Noiseproofing Sealant. It is generally about 2x the cost of the OC-175. OTOH, it's easier to find in small quantities (look on EBay or Amazon).


----------



## HT Geek

Hey Jeff. Looks like your post from a month ago fell thru the proverbial cracks. 



jjcook said:


> For my small second floor DD+GG+clips/channel soundproofed room in progress, I am considering building DIY ULF subwoofers above the theater in the attic (save space in room) for bass content less than 40-50Hz where I will have enough space to build large dual-opposed ported enclosures with a 12-17Hz port tune, something like a LLT built using 2 layers MDF/plywood with GG. I am considering to build the enclosures in-place with independent "framing" and have them rest on rubber mat strips on top of the room's non-decoupled framing and with rubber isolated screws to secure (similar to wall sill plate isolation). Let us assume I've done the structural math so the room framing can support the weight.
> 
> 1. When these attic ULF subwoofers are NOT in use will I be sacrificing my soundproofing? (if using the appropriate rubber isolation pad; how about horse stall mats?)


If you build backer boxes around them, properly secured to the room ceiling / attic floor, and properly caulked and sealed, *no*. 



> 2. Is there any point to building an independent backer box around these beasts? I presume when they are in use the backer box will be ineffective and when not in use the enclosure is already effectively a backer box.


 It's a best practice to build backer boxes around anything like that (ceiling speakers of any kind). The backer box should be handling the sealing/sound proofing for you, versus the construction of the speaker.


Horse stall mats are equivalent to other rubber mats. You may have reverberation issues though, even with rubber mats. Be cautious with your design.


----------



## 1mageWIS

HT Geek said:


> T
> 
> Hmm. Well, FYI for next time... you do not need to tape the inner (1st) layer of drywall. Just mudding or caulking the seams is sufficient since it gets covered up, but no matter. Sometimes it's tough to get that across to the drywall guys if you're paying for pro install. They're not used to thinking about it in that manner.
> 
> When you say there was a 1/8" - 1/4" gap, where is the gap you're referring to? The perimeter around the drywall, or did you mean somewhere else?


The gap is around the perimeter, sorry, I should have been more clear. It was well within 1/8" - 1/4" gap on the first layer. Second layer went up today and on one of the 5/8" panels the tolerance is really, really small. We put shims so it shouldn't be touching the floor, but just by a tiny bit, I think less than 1/8", maybe 1/16"? I really hope no part of it is touching the floor (how bad would that be? It was installed today and even though I hear the flanking TV noise from one of the walls, I don't hear it at all from the new isolated wall. 




> For really small gaps, just use acoustical caulk. The cheapest stuff you can get is typically OC-175. Home Depot sells it for ~$80 for a 12-pack of the big tubes (28 oz.). Last time I ordered it from them the shipping was free.
> 
> There's also a Green Glue equivalent of acoustic caulk, called Green Glue Noiseproofing Sealant. It is generally about 2x the cost of the OC-175. OTOH, it's easier to find in small quantities (look on EBay or Amazon).


We used Green Glue Acoustical Sealant for all of the perimeter gaps, on both the first layer of drywall, and the second layer... generously placed in there and made sure that the first layer sealant was cured before installing the second layer. I will let the second layer sealant cure, and then add more if any cracks develop and to smooth out with the wall, so there is a continuous layer for painting. 

Since the wall is already up, I don't have any more correct access to that flanking wall, but there was a metal stud right where the drywall ended, so it was basically impossible to add anything to that wall. Any suggestions re: flanking noises? 

One of the things that I think is also allowing flanking sound in is the ceiling fan, which is original to when the condo was built in 1985... I'm going to go look tomorrow and try to seal any air gaps between the fan and the ceiling.


----------



## HT Geek

1mageWIS said:


> The gap is around the perimeter, sorry, I should have been more clear. It was well within 1/8" - 1/4" gap on the first layer. Second layer went up today and on one of the 5/8" panels the tolerance is really, really small. We put shims so it shouldn't be touching the floor, but just by a tiny bit, I think less than 1/8", maybe 1/16"? I really hope no part of it is touching the floor (how bad would that be? It was installed today and even though I hear the flanking TV noise from one of the walls, I don't hear it at all from the new isolated wall.


You're on the right path. You should be fine with the work you've had done. The important point is having _a_ gap. The purpose of the gaps is to allow the drywall to flex, such that the drywall diffuses most of the sound energy before it hits air on the other side; versus sound using the drywall as a conduit and traversing to other surfaces (e.g. floor).

Also sounds as if (no pun intended) you're getting a good lesson in flanking sound. This is why there's so much focus on this forum with regards to building a "room within a room." It's the only way to gain complete control over all the surfaces in the room that react with the outside world (outside your HT cocoon that is).



> We used Green Glue Acoustical Sealant for all of the perimeter gaps, on both the first layer of drywall, and the second layer... generously placed in there and made sure that the first layer sealant was cured before installing the second layer. I will let the second layer sealant cure, and then add more if any cracks develop and to smooth out with the wall, so there is a continuous layer for painting.
> 
> Since the wall is already up, I don't have any more correct access to that flanking wall, but there was a metal stud right where the drywall ended, so it was basically impossible to add anything to that wall. Any suggestions re: flanking noises?
> 
> One of the things that I think is also allowing flanking sound in is the ceiling fan, which is original to when the condo was built in 1985... I'm going to go look tomorrow and try to seal any air gaps between the fan and the ceiling.


You may be able to make use of some putty pads to help with the ceiling fan cavity. Note that is a very loose statement on my part though, but I'm just suggesting they might come in handy to plug gaps/holes in an electrical box (though they're normally used on the outside of the box... which I suspect would require making holes in your ceiling... that you probably don't want to do... I wouldn't either).

Just keep in mind, this project is all about what you want and what makes you happy. I try to tailor my advice to the problem at hand, filtered by the perspective of the person asking the question. For example, if you want to totally eliminate all flanking noise, you are likely going to have to go to what most people would consider extreme lengths. Keep asking yourself if you can live with the current situation. It's easy to drink too much of the Kool-Aid on this forum sometimes and potentially put a much larger investment of money and time into a project than common sense would warrant. Most regulars here are probably OCD (myself included).


----------



## HT Geek

MordredKLB said:


> I went ahead and made that call this weekend. Need to order the putty pads though.
> 
> I've seen that it's best to use Acoustic Seal where the first layer of drywall meets the floor and ceiling.


Just wanted to clarify that practice belongs on EVERY layer of drywall, not just the 1st. Sound is like water. It will find a way from Point A to Point B, if you allow it to.


----------



## HT Geek

MordredKLB said:


> Hey guys, I'm doing an extensive remodel on a house, and adding a 2nd story which will have an open media room, and two kids bedrooms. I'm attaching the floorplan. This is an open room, so I'm not even going to attempt to really soundproof things, but I would like to minimize sound leakage into the two bedrooms. If I can drop the volume 30dB-40dB between the rooms I'll consider that a win. Anything more than that is just gravy.
> 
> I'm looking for advice for the things I absolutely _need_ to do. Budget is a strong consideration unfortunately and the large size of the room makes that even more of an issue.
> 
> I'm already planning to do double-drywall and green glue along the walls of the main theater area. I'll also be installing solid core doors to the kids bedrooms. I'm doing inwall speakers for the surrounds and will be putting Dynaboxes around those as well. I don't have the budget for clip and hat.
> 
> I know I can afford to add acoustiseal around the top and bottom of the drywall, as well as around gang boxes, but not sure if that's even worth doing if I've got a lot of sound leakage elsewhere. Anything else I should consider?


Automatic door bottoms would help as well. Decent ones will set you back ~$100-150 or so per door for 32". No need to spend on the $300+ versions if you are budget conscious.


----------



## HT Geek

barfle said:


> It's mostly the noise from the air moving through the vent, not the sound of the furnace itself (although, of course when you fix the obvious problem, the next most obvious problem shows up!).
> 
> It sounds like it's going to take some duct work  but if that's what it takes, well, time to buck up and do the work. Thanks for the suggestion of multiple vents, that's the direction I'll go.


You'll get best results if you do a combination of two things (if you are so inclined):

Extending/Snaking ductwork (no straight lines into/thru room)
Build a vent/duct muffler

There are a number of techniques that work well. I've attached some photos that illustrate a large muffler and a dual-box muffler system. In the dual system, air passes through one of the boxes (to another vent), and there is a vent on the 2nd muffler box attached to the first. The inside of the mufflers are lined with duct liner. The mufflers reduce the velocity of the airflow. If you are able to control the airflow noise well enough, you can then introduce an inline blower motor if you have concerns with airflow volume. In this case (pictured), the dual-muffler system served an additional purpose, which was equalizing the air velocity on both sides of the room. The dual box muffler was where the forced air was entering the room too rapidly. The other side of the room's velocity was too low. I figured that out before installing the mufflers, when testing the airflow while the flex duct was roughed in throughout the room. Some creative re-orientation of flex duct and the custom muffler boxes solved several issues with a single solution.

It's a balancing act: velocity vs. flow. Too little or too much of one or the other results in an issue of noise or comfort. In some cases, you can also stress your HVAC system. I recommend figuring out the appropriate calculations for your room before making any modifications to avoid the last point.


----------



## jjcook

HT Geek said:


> If you build backer boxes around them, properly secured to the room ceiling / attic floor, and properly caulked and sealed, *no*.
> ...
> It's a best practice to build backer boxes around anything like that (ceiling speakers of any kind). The backer box should be handling the sealing/sound proofing for you, versus the construction of the speaker.


I get the theory, but due to their size the backer boxes seem less practical.

I'm still in the planning phase so to speak so this is just hypothetical for now. Lets discuss from a different perspective, for these large and heavy subwoofers (20-25 cuft, i.e., 2' x 2' x 6', ~200 lbs before backer box) how can I support the subwoofer and/or it's large backer box and keep it decoupled from the non-decoupled framing (outside the shell) besides supporting it with rubber mat strips (plus appropriate rubber sandwich screws to keep it from shifting around)? If I do the sub/backer decoupling correctly and build the subwoofer box as a backer box with double layers of material and green glue, then when not in use as a subwoofer it should be equivalent to a backer box, no? (properly caulked etc). And when used for high SPL < 40Hz bass I'm not expecting any backer box to make much of a difference, so why add the complexity of extra weight ~150lbs of a few addition sheets of material for backer to the subwoofer? Perhaps I'm discounting what a backer box can do for a subwoofer...


----------



## 1mageWIS

HT Geek said:


> You're on the right path. You should be fine with the work you've had done. The important point is having _a_ gap. The purpose of the gaps is to allow the drywall to flex, such that the drywall diffuses most of the sound energy before it hits air on the other side; versus sound using the drywall as a conduit and traversing to other surfaces (e.g. floor).
> 
> Also sounds as if (no pun intended) you're getting a good lesson in flanking sound. This is why there's so much focus on this forum with regards to building a "room within a room." It's the only way to gain complete control over all the surfaces in the room that react with the outside world (outside your HT cocoon that is).
> 
> 
> 
> You may be able to make use of some putty pads to help with the ceiling fan cavity. Note that is a very loose statement on my part though, but I'm just suggesting they might come in handy to plug gaps/holes in an electrical box (though they're normally used on the outside of the box... which I suspect would require making holes in your ceiling... that you probably don't want to do... I wouldn't either).
> 
> Just keep in mind, this project is all about what you want and what makes you happy. I try to tailor my advice to the problem at hand, filtered by the perspective of the person asking the question. For example, if you want to totally eliminate all flanking noise, you are likely going to have to go to what most people would consider extreme lengths. Keep asking yourself if you can live with the current situation. It's easy to drink too much of the Kool-Aid on this forum sometimes and potentially put a much larger investment of money and time into a project than common sense would warrant. Most regulars here are probably OCD (myself included).


Thanks for the super quick responses!  

AS GG Acoustical Sealant seems to have a lot of shrinkage, I'm going to apply another layer of it around the perimeter. Once it's finally sealed, do I just mud over it as would be done on a normal wall, i.e. so the wall is smooth from top to bottom, side to side? 

Also, there will be baseboard going back in there, I was planning on gluing it to the wall, and applying acoustical caulk where it meets the other baseboard and have it 'sitting' on a thin strip of acoustical caulk, i.e. trying to minimize any mechanical connection. Does this work, or am I planning it wrong?


----------



## HT Geek

jjcook said:


> I get the theory, but due to their size the backer boxes seem less practical.
> 
> I'm still in the planning phase so to speak so this is just hypothetical for now. Lets discuss from a different perspective, for these large and heavy subwoofers (20-25 cuft, i.e., 2' x 2' x 6', ~200 lbs before backer box) how can I support the subwoofer and/or it's large backer box and keep it decoupled from the non-decoupled framing (outside the shell) besides supporting it with rubber mat strips (plus appropriate rubber sandwich screws to keep it from shifting around)? If I do the sub/backer decoupling correctly and build the subwoofer box as a backer box with double layers of material and green glue, then when not in use as a subwoofer it should be equivalent to a backer box, no? (properly caulked etc). And when used for high SPL < 40Hz bass I'm not expecting any backer box to make much of a difference, so why add the complexity of extra weight ~150lbs of a few addition sheets of material for backer to the subwoofer? Perhaps I'm discounting what a backer box can do for a subwoofer...


The gist of the backer box is to prevent sound leakage. I believe I see where you're going with this. Your position is that if the subs are properly sealed around their perimeter, they are effectively acting like a backer box. And since they'll be transmitting VLF, any backer box around them probably won't stop much of the signal unless extreme amounts of mass are used (reason no. 2 for a backer box is containment).

Well, I think if you can make sure there are no gaps then yes, it should work provided you don't mind the effect in the non-HT room space; though it appears to me that for you that is a non-issue.

How are you going to run the speaker wire to these? Active or passive amp power (built-in amp requiring 120vac or power via speaker cable from amp)?

Regarding decoupling... if I understand your thought process correctly... you intend to support the weight of these subs via existing structure of your home. So, you are wondering how to isolate the subs from that structure. If I've got that correct.... That's going to be exceptionally difficult to accomplish. LFE is tough to contain when it's inside a decoupled room to begin with. If in your case, the LFE source were directly attached to the structure of the home, I'm struggling to think of any product or design that would provide a meaningful dampening between the sub and your home's joists. The end result is really going to depend on how much the sub boxes resonate into the structure. Again, a backer box could help here because it would effectively increase the mass of the sub. Given the size of your subs, and using some kind of cement board sandwich, the end result would be exceptionally heavy, but may be worth the effort, depending on what end result you value the most.

At the very least... not using a backer box... you'd want to put as much mass as you can between the sub's "frame" per se and the structural framing of the house. So, for example if you built some "feet" for the sub to lay on... over top of the joists.... you'd want those feet to be really dense (heavy), so they would absorb a good chunk of the LFE before it entered the joists.

I can tell you that - speaking from experience - wood floor joists in typical homes in the USA are very good at transmitting LFE along their length axis (i.e. not good for HT enthusiasts).


----------



## HT Geek

1mageWIS said:


> Thanks for the super quick responses!
> 
> AS GG Acoustical Sealant seems to have a lot of shrinkage, I'm going to apply another layer of it around the perimeter. Once it's finally sealed, do I just mud over it as would be done on a normal wall, i.e. so the wall is smooth from top to bottom, side to side?


To clarify: apply the sealant around the _perimeter_, but not on the face (surface) of the drywall. The surface should be mudded as normal. You just want to plug the gaps, and drywall mud doesn't work well for that around the edges of the wall (perimeter). You also want a "bouncy" caulk that does not become rigid - thus the use of acoustical caulk. And good catch. Yes, it does tend to shrink a bit (the caulk), and it's wise to evaluate its condition after the first pass dries. There will likely be a few small gaps here and there. 

If you have more than about 1/4" of a gap, get yourself some caulk saver / backer rod and shove that in there first. It's an open cell material similar to styrofoam. For larger gaps it helps the caulk stay put so you use less of it and get the job done quicker. It's available at Big Box stores and comes in different thicknesses. Get the smallest thickness you need (e.g. 3/8" or 1/2" or whatever). It's cheap.




> Also, there will be baseboard going back in there, I was planning on gluing it to the wall, and applying acoustical caulk where it meets the other baseboard and have it 'sitting' on a thin strip of acoustical caulk, i.e. trying to minimize any mechanical connection. Does this work, or am I planning it wrong?


You can glue it. Or nail it as it would normally be. Just be mindful of nail length. Doing both is advised as you'll be better off with at least a few nails to ensure it stays put while the glue is drying. But that's your call if you believe the glue by itself will be sufficient. If you do that, put some spacers under it so it doesn't move.

Also, do you have the finished floor in yet? Make sure you allow proper room. Usually about 1/2" is good for most floor surfaces.

You shouldn't require acoustical caulk under the baseboard. If you're going to have carpet installed, don't caulk it first. It will make a mess of your carpet.

p.s. If you don't have the finished floor in yet and you're uncertain of clearance under the baseboard, go with 3/4". Also be aware if you get carpet installed after the fact, the installers are not likely to be kind to your baseboard. Better be some strong glue.


----------



## 1mageWIS

HT Geek said:


> To clarify: apply the sealant around the _perimeter_, but not on the face (surface) of the drywall. The surface should be mudded as normal. You just want to plug the gaps, and drywall mud doesn't work well for that around the edges of the wall (perimeter). You also want a "bouncy" caulk that does not become rigid - thus the use of acoustical caulk. And good catch. Yes, it does tend to shrink a bit (the caulk), and it's wise to evaluate its condition after the first pass dries. There will likely be a few small gaps here and there.
> 
> If you have more than about 1/4" of a gap, get yourself some caulk saver / backer rod and shove that in there first. It's an open cell material similar to styrofoam. For larger gaps it helps the caulk stay put so you use less of it and get the job done quicker. It's available at Big Box stores and comes in different thicknesses. Get the smallest thickness you need (e.g. 3/8" or 1/2" or whatever). It's cheap.


Yes, the sealant was only around the perimeter. Mud and tape was used on the first layer, then sanded flat, then the next layer was staggered, so no seams overlap. I'm already seeing shrinkage, so I'm going to add more. The same thing happened with the first layer of drywall, and those gaps were also sealed. 


As my GC friend won't be available until 8 days from now (long story) and I want to finish this before then, now I have to figure out how to get mud on the corners on top of the acoustical sealant and which mud to use... Any suggestions? 




> You can glue it. Or nail it as it would normally be. Just be mindful of nail length. Doing both is advised as you'll be better off with at least a few nails to ensure it stays put while the glue is drying. But that's your call if you believe the glue by itself will be sufficient. If you do that, put some spacers under it so it doesn't move.
> 
> Also, do you have the finished floor in yet? Make sure you allow proper room. Usually about 1/2" is good for most floor surfaces.
> 
> You shouldn't require acoustical caulk under the baseboard. If you're going to have carpet installed, don't caulk it first. It will make a mess of your carpet.
> 
> p.s. If you don't have the finished floor in yet and you're uncertain of clearance under the baseboard, go with 3/4". Also be aware if you get carpet installed after the fact, the installers are not likely to be kind to your baseboard. Better be some strong glue.


For clarification, this is a retrofit project, so everything is being done to just that one wall, everything else hasn't been removed or touched, so the floor is already in place. Here are a few pics (in reverse order, sorry about that) of the process: 

1) The wall pre-opening
2) The open wall with exposed CMUs. 
3) 25 ga metal stud frame installed not touching the brick wall (like 1/4" or 1/2" away from it), with Rockwool Safe n Sound fitted inside
4) Clips installed, with the long hat channel pieces. Smaller pieces were later added and attached together using 7/16" screws
5) The first layer of drywall, taped, muded, and perimeter sealed with acoustical sealant.

The right wall where the Rockwool is in the pic is where the flanking noise is coming from, the left wall has zero flanking noise. And you can see the ceiling fan I want to try to seal it using acoustical putty the upper hole on the ceiling where the wires connect to the fan.


----------



## jjcook

HT Geek said:


> The gist of the backer box is to prevent sound leakage. I believe I see where you're going with this. Your position is that if the subs are properly sealed around their perimeter, they are effectively acting like a backer box. And since they'll be transmitting VLF, any backer box around them probably won't stop much of the signal unless extreme amounts of mass are used (reason no. 2 for a backer box is containment).
> 
> Well, I think if you can make sure there are no gaps then yes, it should work provided you don't mind the effect in the non-HT room space; though it appears to me that for you that is a non-issue.


Yes that is the trade-off I must decide upon; its an attic above the HT space that is shared with the rest of the second floor, so the VLF/ULF subwoofers will only practically be for non-late night fun.



HT Geek said:


> How are you going to run the speaker wire to these? Active or passive amp power (built-in amp requiring 120vac or power via speaker cable from amp)?


They would be passively powered by rack mount amps.



HT Geek said:


> Regarding decoupling... if I understand your thought process correctly... you intend to support the weight of these subs via existing structure of your home. So, you are wondering how to isolate the subs from that structure. If I've got that correct.... That's going to be exceptionally difficult to accomplish. LFE is tough to contain when it's inside a decoupled room to begin with. If in your case, the LFE source were directly attached to the structure of the home, I'm struggling to think of any product or design that would provide a meaningful dampening between the sub and your home's joists. The end result is really going to depend on how much the sub boxes resonate into the structure. Again, a backer box could help here because it would effectively increase the mass of the sub. Given the size of your subs, and using some kind of cement board sandwich, the end result would be exceptionally heavy, but may be worth the effort, depending on what end result you value the most.
> 
> At the very least... not using a backer box... you'd want to put as much mass as you can between the sub's "frame" per se and the structural framing of the house. So, for example if you built some "feet" for the sub to lay on... over top of the joists.... you'd want those feet to be really dense (heavy), so they would absorb a good chunk of the LFE before it entered the joists.
> 
> I can tell you that - speaking from experience - wood floor joists in typical homes in the USA are very good at transmitting LFE along their length axis (i.e. not good for HT enthusiasts).


As the HT room is on the second floor, the subwoofers will be sitting on framing one way or another but I get your point. I will definitely consider multiple layers of rubber mat or other such density and resilient material to mitigate LFE transmission; I do plan those subwoofers to be dual opposed to cancel much of the moving mass vibration at least.

I'll get back to planning this out some more and provide some sketches when I'm satisfied with the structural aspects... if I don't instead decide to convert my home's crawlspace area into the HT (yikes! $$$)


----------



## MordredKLB

Sheetrock was being hung at my house today, and despite explicit instructions and trying to be around constantly to supervise, I discovered after they'd done the first wall that the sheetrock guy was using probably less than a tube of green glue per 4x8 panel. I'd like them to redo it, but I want to know what the ramifications are of taking the panels off the wall once they've gone up. Do the sheetrock panels need to be all new (and if so do the underlying ones need to be new too?) or can they use the existing ones? I'm concerned if the holes from the drywall screws through both panels matters at all (presumably the holes won't line up and there's no screw filling those holes seems it'd be bad from a sound isolation standpoint.

What do you guys recommend I tell my contractor?


----------



## mattztt

MordredKLB said:


> Sheetrock was being hung at my house today, and despite explicit instructions and trying to be around constantly to supervise, I discovered after they'd done the first wall that the sheetrock guy was using probably less than a tube of green glue per 4x8 panel. I'd like them to redo it, but I want to know what the ramifications are of taking the panels off the wall once they've gone up. Do the sheetrock panels need to be all new (and if so do the underlying ones need to be new too?) or can they use the existing ones? I'm concerned if the holes from the drywall screws through both panels matters at all (presumably the holes won't line up and there's no screw filling those holes seems it'd be bad from a sound isolation standpoint.
> 
> What do you guys recommend I tell my contractor?


Green Glue starts to set up within 15 minutes or so. It's still pretty gooey after a few hours but I'm not sure if you'll even be able to pull the drywall sheets apart without destroying them by 24 hours later. Try sliding them across each other to break the glue free. If you can get them apart you could probably get away with adding additional GG and putting them back up but it's not exactly a routine a lot of people have been through so no guarantees. I would not be worried about the screw holes.


----------



## MordredKLB

mattztt said:


> Green Glue starts to set up within 15 minutes or so. It's still pretty gooey after a few hours but I'm not sure if you'll even be able to pull the drywall sheets apart without destroying them by 24 hours later. Try sliding them across each other to break the glue free. If you can get them apart you could probably get away with adding additional GG and putting them back up but it's not exactly a routine a lot of people have been through so no guarantees. I would not be worried about the screw holes.


So sounds like if it's going to be fixed there's a good chance the entire wall will have to be redone. Not exactly an ideal scenario, but thanks for the info.


----------



## HT Geek

MordredKLB said:


> Sheetrock was being hung at my house today, and despite explicit instructions and trying to be around constantly to supervise, I discovered after they'd done the first wall that the sheetrock guy was using probably less than a tube of green glue per 4x8 panel. I'd like them to redo it, but I want to know what the ramifications are of taking the panels off the wall once they've gone up. Do the sheetrock panels need to be all new (and if so do the underlying ones need to be new too?) or can they use the existing ones? I'm concerned if the holes from the drywall screws through both panels matters at all (presumably the holes won't line up and there's no screw filling those holes seems it'd be bad from a sound isolation standpoint.
> 
> What do you guys recommend I tell my contractor?





mattztt said:


> Green Glue starts to set up within 15 minutes or so. It's still pretty gooey after a few hours but I'm not sure if you'll even be able to pull the drywall sheets apart without destroying them by 24 hours later. Try sliding them across each other to break the glue free. If you can get them apart you could probably get away with adding additional GG and putting them back up but it's not exactly a routine a lot of people have been through so no guarantees. I would not be worried about the screw holes.





MordredKLB said:


> So sounds like if it's going to be fixed there's a good chance the entire wall will have to be redone. Not exactly an ideal scenario, but thanks for the info.


 @*mattztt* is correct. It will remain somewhat viscous temporarily, but if you want a do-over you will have to resign yourself to literally starting over and trashing the drywall that was put up today. There's really no way around it. You'll just create a bigger mess if you have someone attempt to salvage what you have up right now.

@*MordredKLB* , if I understand the 2nd part of your question correctly.... you are curious/concerned about the prospect of removing the outer layer of a 2-drywall-layer-sandwich and whether or not the holes left behind might create an issue for sound transmission. Regarding that matter, I have a few thoughts:

1) See my prior comment regarding removal of the current panels; i.e. you will need to destroy what was put up to start over, and therefore your 2nd question becomes a non-issue
2) Theoretically speaking... if you could remove just the outer layer and put another outer (2nd) layer up... would the remaining screw holes matter? Practically speaking... no. There's 2 things going on here... a) mass; and b) blocking holes. The 2nd sheet would help with both. If you want to be REALLY anal about it then I suppose one could make the logical argument the holes would matter, but from a real-world practical standpoint, they would not as long as they were not completely through all sheets of drywall (but then you'd have an ugly hole in your finished wall.... which most people would prefer not to have... and I'll go out on a limb and presume you wouldn't want that either).

The bottom line is you're at a crossroads of deciding if you can live with a sub-par application of Green Glue due to either a misunderstanding or incompetence of your contractor or sub-contractor (I'll let you decide if it's the former or latter cause)..... 

IOW, does it matter if you've got


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## MordredKLB

HT Geek said:


> You'll need to decide if you are willing to start over to gain less than a 50% improvement in performance versus your no-cost-delta option which is to leave it as-is right now.
> 
> Unless the wall in question covers a particularly sensitive area, I'd be inclined to let it be and make sure proper techniques are utilized going forward. If the wall in question is critical, it might be worth a tear down and re-do if you have the extra resources and you don't care about time and cost.
> 
> Another thought... do triple-layer walls.... even just on that one wall... with another GG sandwich. That would make it a non-issue and might cost you less as well.
> 
> Good luck, and let us know what you decide.


Thanks for the input, and you're right from what I read. 1 tube is worth about 70% reduction in sound. I'm slightly concerned that it might be more like 3/4s of a tube per sheet.

It's one wall of a family/media room which is adjacent to my daughters bedroom, so of course it's the wall I considered most sensitive. That wall also extends well past the edge of her room, and covers a little arch/alcove way and a bathroom, neither of which needed the Green Glue there... but if we're ripping up the sheetrock that would also need to go too since the panels overlap.

I'm curious what the contractor will say, given that the crew didn't follow the instructions that I had given my contractor, the head of the sheetrock company, and the crew foreman. I think they might just eat the cost if I raise a stink about it.

I've got a solution though that could be workable, and save a lot of time and money. If I have them do the adjoining wall from the bedroom side it's a much smaller area. I know the GG is supposed to go on the side of the wall the noises are coming from... since there's already _some_ there, I'd think that installing it on the other side of the wall, the cumulative effect would be at least as effective as 2 tubes per panel on the correct side.


----------



## jrref

MordredKLB said:


> Thanks for the input, and you're right from what I read. 1 tube is worth about 70% reduction in sound. I'm slightly concerned that it might be more like 3/4s of a tube per sheet.
> 
> It's one wall of a family/media room which is adjacent to my daughters bedroom, so of course it's the wall I considered most sensitive. That wall also extends well past the edge of her room, and covers a little arch/alcove way and a bathroom, neither of which needed the Green Glue there... but if we're ripping up the sheetrock that would also need to go too since the panels overlap.
> 
> I'm curious what the contractor will say, given that the crew didn't follow the instructions that I had given my contractor, the head of the sheetrock company, and the crew foreman. I think they might just eat the cost if I raise a stink about it.
> 
> I've got a solution though that could be workable, and save a lot of time and money. If I have them do the adjoining wall from the bedroom side it's a much smaller area. I know the GG is supposed to go on the side of the wall the noises are coming from... since there's already _some_ there, I'd think that installing it on the other side of the wall, the cumulative effect would be at least as effective as 2 tubes per panel on the correct side.


So the more mass you have the better. I wouldn't tear down the rock already installed since it's probably not going to make that much difference and putting more mass on the other side will definetly be better. I would guess the best you can hope for is some discount from the contractor for not following instructions.

This example is why I went with Quiet Rock for my application even though it costs more. No worries about how much GG put on, application is perfect and 100% even, no having to micro manage the contractor.


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## lovingdvd

*Sound isolating a washer and dryer from the floor*

Hi guys - I'm changing my mudroom to a porcelain one. Currently it is a typical OSB floor with a very thin, super cheap carpet on top with no pad. So the installer will remove the carpet and add a layer of 1/4" Durock cement board on top of that, and install the 1/4" porcelain tile on top of that.

I'm looking for a very simple way to reasonably sound isolate the washer and dryer that will then sit on top of this new floor. The theater is not directly under it, but still I want to minimize the vibration in the surround areas that it may cause, since now it will be on a much harder surface. I'm not looking to have the installer do anything special to the subfloor. 

Ideally I'd like to do something basic like put a rubber mat on top of the porcelain that the washer and dryer can sit on. Can anyone recommend a particular mat or particular kind of mat that I can buy online or find at HD/Lowes? Maybe it is sufficient to get one of those rubber mats designed for people who stand a lot in the same place for their job?

Any ideas would be great. Thanks in advance!


----------



## niccolo

lovingdvd said:


> Hi guys - I'm changing my mudroom to a porcelain one. Currently it is a typical OSB floor with a very thin, super cheap carpet on top with no pad. So the installer will remove the carpet and add a layer of 1/4" Durock cement board on top of that, and install the 1/4" porcelain tile on top of that.
> 
> I'm looking for a very simple way to reasonably sound isolate the washer and dryer that will then sit on top of this new floor. The theater is not directly under it, but still I want to minimize the vibration in the surround areas that it may cause, since now it will be on a much harder surface. I'm not looking to have the installer do anything special to the subfloor.
> 
> Ideally I'd like to do something basic like put a rubber mat on top of the porcelain that the washer and dryer can sit on. Can anyone recommend a particular mat or particular kind of mat that I can buy online or find at HD/Lowes? Maybe it is sufficient to get one of those rubber mats designed for people who stand a lot in the same place for their job?
> 
> Any ideas would be great. Thanks in advance!


The better you can decouple the appliances, the more you'll reduce sound (with the caveat that you want to make sure the appliances are still stable, because if they're able to move too much due to decoupling that may have functional implications and sound implications, too). Just brainstorming here, but I wonder whether a sandwich of plywood or OSB with rubber sandwiched in between would work better than just having the appliances sit on rubber? That seems especially true if the appliances have feet or other small surface area contact points.


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## bws

Hi Everyone,
I have a ceiling that I'd like to soundproof. I using Roxul Safe & Sound but am looking for advice on which is the best way to go with the limited ceiling height I have.

I'd like to dampen the sound but lose as little ceiling height as possible.

Which would be best for my situation?

1. 2 layers of sheetrock with Green Glue
2. Quietrock sheet rock
3. Furring channel/Hat channel and sound absorbing clips (Forgive me if I don't know the difference in the channel solutions)

Any advice is appreciated.


----------



## Ladeback

bws said:


> Hi Everyone,
> I have a ceiling that I'd like to soundproof. I using Roxul Safe & Sound but am looking for advice on which is the best way to go with the limited ceiling height I have.
> 
> I'd like to dampen the sound but lose as little ceiling height as possible.
> 
> Which would be best for my situation?
> 
> 1. 2 layers of sheetrock with Green Glue
> 2. Quietrock sheet rock
> 3. Furring channel/Hat channel and sound absorbing clips (Forgive me if I don't know the difference in the channel solutions)
> 
> Any advice is appreciated.



The best way for the ceiling is Level 3 from Soundproofing Company. Two layers of 5/8" with Green Glue, pink fluffy, clips w/ channel and 2 layers of 5/8" with Green Glue. 

https://www.soundproofingcompany.com/spc-solution-3-soundproof-ceiling

Now you will want to do something about the walls as well, because sounds is going to travel up them to the next level. 

What you need to do for the best, from what I have read here is decouple, mass and absorption.

Check out more on their website. 

It all depends on your budget and what you want do.


----------



## bws

Ladeback said:


> The best way for the ceiling is Level 3 from Soundproofing Company. Two layers of 5/8" with Green Glue, pink fluffy, clips w/ channel and 2 layers of 5/8" with Green Glue.
> 
> https://www.soundproofingcompany.com/spc-solution-3-soundproof-ceiling
> 
> Now you will want to do something about the walls as well, because sounds is going to travel up them to the next level.
> 
> What you need to do for the best, from what I have read here is decouple, mass and absorption.
> 
> Check out more on their website.
> 
> It all depends on your budget and what you want do.



Since my ceilings are only 8 ft 3 I'd probably be close to crawling on my knees with each of those. How much height would I lose with channel and clips?

What is my 2nd best option other than channel and clips?


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## Ladeback

With the cheaper IB-1 clips, channel and two layers of drywall with Green Glue you would probably lose around 2.875" to 3" in height.

You could possibly use the IB-2 extension clips and move them up s little to maybe save a little not score how much. 

You could skip the clips and channel, your STC would go down though. Here are the three options on Soundproofing Company website. 

[https://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-ceilings]

Sent from my SM-N960U using Tapatalk


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## bws

Ladeback said:


> With the cheaper IB-1 clips, channel and two layers of drywall with Green Glue you would probably lose around 2.875" to 3" in height.
> 
> You could possibly use the IB-2 extension clips and move them up s little to maybe save a little not score how much.
> 
> You could skip the clips and channel, your STC would go down though. Here are the three options on Soundproofing Company website.
> 
> [https://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-ceilings]
> 
> Sent from my SM-N960U using Tapatalk


Thanks for the illustration. 

I you could only do 1 which would it be?

1. double drywall with Green Glue 
2. Or decoupling with 1 layer drywall


----------



## bws

Ladeback said:


> With the cheaper IB-1 clips, channel and two layers of drywall with Green Glue you would probably lose around 2.875" to 3" in height.
> 
> You could possibly use the IB-2 extension clips and move them up s little to maybe save a little not score how much.
> 
> You could skip the clips and channel, your STC would go down though. Here are the three options on Soundproofing Company website.
> 
> [https://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-ceilings]
> 
> Sent from my SM-N960U using Tapatalk


Thanks for the illustration. 

If you could only do 1 which would it be?

1. double drywall with Green Glue 
2. Or decoupling with 1 layer drywall


----------



## mattztt

bws said:


> Thanks for the illustration.
> 
> If you could only do 1 which would it be?
> 
> 1. double drywall with Green Glue
> 2. Or decoupling with 1 layer drywall


You could do just one, but they work together. Double drywall adds mass which helps to attenuate lower frequencies. The green glue adds dampens vibration, helping to keep it from transmitting to the other side of the wall. Decoupling prevents vibrations in the wall from transmitting to the structure. If I had to do only one of the your two options I'd go with the second because it would allow me to later add Green Glue and a second layer.


----------



## Ladeback

bws said:


> Thanks for the illustration.
> 
> If you could only do 1 which would it be?
> 
> 1. double drywall with Green Glue
> 2. Or decoupling with 1 layer drywall


Are your trying to keep sound from coming in from above or going out? I am looking into putting two layers of 5/8" drywall and Green Glue between the joist and either just 1 layer of 5/8' drywall in my ceiling with insulation in the cavity above. The other option is to the double layer between the joist and acoustical tile so I can move wires around if needed and so I can add Dolby Atmos at a later date.


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## bws

Ladeback said:


> Are your trying to keep sound from coming in from above or going out? I am looking into putting two layers of 5/8" drywall and Green Glue between the joist and either just 1 layer of 5/8' drywall in my ceiling with insulation in the cavity above. The other option is to the double layer between the joist and acoustical tile so I can move wires around if needed and so I can add Dolby Atmos at a later date.


I'm trying to keep sound from going out.


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## Ladeback

bws said:


> I'm trying to keep sound from going out.


The four main elements in soundproofing is decoupling, absorption, mass and damping. The three types are going to help with sound getting in or out, the question is what how much sound are you putting out? Do you listen at reference and have a lot bass? Then I would go with number 3. If you somewhere in the middle 2 or 1 may be good enough. If you want the room to be tight and nothing getting out, it can get expensive. Also it is hard to totally soundproof for bass. I would give the Soundproofing Company a call or send them an email and they will help you out. That's how I have learned and talking to others on here.

Here is Soundproofing 101 that might help. My theater is below our kitchen and living room and I don't crank it like I did when I was younger so my wife doesn't complain, but I do some to make sure she doesn't in the future if I go louder.

https://www.soundproofingcompany.com/soundproofing101


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## mhutchins

By using blocking between the joists, you can reduce the distance lost to just the thickness of your drywall + 1/2”. So for example, with 2 layers of 5/8” with Green Glue, clips and channel, the height lost would be 1-3/4”.

Mike


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## bws

mhutchins said:


> By using blocking between the joists, you can reduce the distance lost to just the thickness of your drywall + 1/2”. So for example, with 2 layers of 5/8” with Green Glue, clips and channel, the height lost would be 1-3/4”.
> 
> Mike


Hi Mike,
Can you tell me what blocking is?


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## mhutchins

I believe this came from the good folks at the Soundproofing Company:


Mike


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## doveman

Is it OK to use clips+channel+Rockwool+two layers of acoustic drywall on a bathroom ceiling?

As it's quite a small space with no windows it seems like a good place to test how effective this will be at blocking noise from above. I believe Rockwool has anti-mould properties that pink fluffy doesn't, so that might be OK and I guess if the drywall's properly sealed no moisture will be able to get to the drywall anyway but I don't know if the drywall itself will be OK in that environment.


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## impreza276

doveman said:


> Is it OK to use clips+channel+Rockwool+two layers of acoustic drywall on a bathroom ceiling?
> 
> As it's quite a small space with no windows it seems like a good place to test how effective this will be at blocking noise from above. I believe Rockwool has anti-mould properties that pink fluffy doesn't, so that might be OK and I guess if the drywall's properly sealed no moisture will be able to get to the drywall anyway but I don't know if the drywall itself will be OK in that environment.


Is it a half or full bath?


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## doveman

impreza276 said:


> Is it a half or full bath?


It's a full bath.


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## impreza276

doveman said:


> It's a full bath.


In that case use a moisture resistant drywall. Use two layers of 5/8 green board or equivalent with green glue on the ceiling. Pink insulation will be fine - by the time moisture becomes an issue with the insulation you will have had a whole lot of problem with the drywall already.


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## doveman

impreza276 said:


> In that case use a moisture resistant drywall. Use two layers of 5/8 green board or equivalent with green glue on the ceiling. Pink insulation will be fine - by the time moisture becomes an issue with the insulation you will have had a whole lot of problem with the drywall already.


Thanks. I'd not heard of green board before. Having just read this https://www.thespruce.com/what-is-greenboard-drywall-1822831 I'm not sure it would be ideal for a bathroom ceiling though, due to the lack of mold-resistance (I have problems in my bathroom with mold growing on the caulk and grout) and risk of it sagging and I don't think it has any particular soundproofing qualities, so maybe I'd be better off with some purple board like SoundBreak XP Drywall, which is moisture, mold and mildew resistance and sound resistant http://askforpurple.com/why-purple/ (not sure I can get that in the UK though), or Gyproc Soundbloc MR https://www.british-gypsum.com/products/gyproc-soundbloc-mr (seems strange they don't specify how much it reduces sound when it's sold as specifically for that), or Knauf Performance Plus https://www.knauf.co.uk/store/performance-plus/c-23/p-75 ?

Isn't it better to have the two layers different thicknesses, i.e. one 15mm and the other 12.5mm? Will green glue significantly improve the soundproofing in this situation? Obviously in a bathroom there won't be subwoofers generating loud bass and the noise coming from above is generally impact, floorboards squeaking, voices.


----------



## impreza276

doveman said:


> Thanks. I'd not heard of green board before. Having just read this https://www.thespruce.com/what-is-greenboard-drywall-1822831 I'm not sure it would be ideal for a bathroom ceiling though, due to the lack of mold-resistance (I have problems in my bathroom with mold growing on the caulk and grout) and risk of it sagging and I don't think it has any particular soundproofing qualities, so maybe I'd be better off with some purple board like SoundBreak XP Drywall, which is moisture, mold and mildew resistance and sound resistant http://askforpurple.com/why-purple/ (not sure I can get that in the UK though), or Gyproc Soundbloc MR https://www.british-gypsum.com/products/gyproc-soundbloc-mr (seems strange they don't specify how much it reduces sound when it's sold as specifically for that), or Knauf Performance Plus https://www.knauf.co.uk/store/performance-plus/c-23/p-75 ?
> 
> Isn't it better to have the two layers different thicknesses, i.e. one 15mm and the other 12.5mm? Will green glue significantly improve the soundproofing in this situation? Obviously in a bathroom there won't be subwoofers generating loud bass and the noise coming from above is generally impact, floorboards squeaking, voices.


Either green or purple board would work fine, as long as you go for high density 5/8, not the lightweight stuff. You want drywall that weighs at least 2.2lbs per sqft. The weight and the mold resistance are the important factors to look for, for your application. I used Purple XP for my basement. You do not need to look for 'soundproof' drywall if what you can get meets the weight criteria. From what I have read, different thicknesses do not make a difference. Have you read https://www.soundproofingcompany.com/soundproofing101 ?


----------



## Colton Walker

Hey all! First post here. I'm sorry if I'm not adhering to any rules I may have missed.

*I'm looking at DIY'ing (inexpensively) soundproofing for a condo basement in Canada.* I'm familiar with the basic concepts of soundproofing (mass=blocker, resonance is bad, viscoelasticity, etc), but need advice here.

Basically, *I have adjoined neighbors to the east and west.* I'm planning on *making the basement a theater room* (on a budget, since we both work part-time to support ourselves in volunteer work) *soundproofing the basement walls against my neighbors* to at least provide some level of sound dampening. *Not the ceiling*, since I won't be able to get access up there without major renovations, and I'm hoping the fact it'd need to travel through additional walls (the ceiling, floor, and then neighboring walls) will help avoid the need to touch the ceiling. The east wall is a straight 8' by about 10-12' stretch. Along the west wall has my mechanical room - this is basically a room within the basement, and this allows me currently to access the inside of that wall to insulate. I can also add drywall to the walls INSIDE the mechanical room since there isn't any as of yet. Total stretch would be about 14'-16', excluding the mechanical room?

*Basically, I'm down to 3 options.* I'm looking for *best "bang for your buck"*. I'd like to watch Interstellar, for example, at reasonable volumes with a proper soundsetup without worrying about my elderly neighbors in their upstairs bedroom. I want to mitigate as best as I can.

*1.* Tear down the east wall, add insulation (planning to use Rockwool), and replace with new drywall. Instead of 1/2 drywall ($12/sheet) or "soundproofing" drywall with a viscoelastic layer ($60/sheet)", I'm planning to use 5/8 Type X (firecode) drywall ($17/sheet), which is 100lb a sheet vs 40lb a sheet for regular drywall. *The drywall will be well over 1lb/ft.* Then insulate the back of the west wall with Rockwool. Leave the west wall itself as is. Not sure if there's resilient channel?

*2.* Tear down both the east and west walls, add Rockwool, and replace both walls with Type X drywall.

*3.* Leave the existing walls and add a new layer of drywall to both the east and west sides, possibly with MLV in between (most expensive by far, $241/100sqft from a local supplier where I pickup, so probably $500+ just in MLV). *I would have no idea how to do this*, or what hardware to use for spacing the drywall.

I'm not familiar with "green glue" or any other specialty building products for sound reduction. My expertise is in auto sound reduction, which isn't really "expert" by any means. What's my best option here...?

The existing flooring is carpet, and* I'm planning on redoing the floor with hardwood* as well. So if adding another drywall layer is best, how should I do the flooring...? First? Doing the flooring first might be slightly problematic since we have a painter already working through the house, I'd like to get this done before he gets to the basement (within a couple of weeks), and this will be a job I'm working on almost entirely in my off-time (evenings).


----------



## jrref

Colton Walker said:


> Hey all! First post here. I'm sorry if I'm not adhering to any rules I may have missed.
> 
> *I'm looking at DIY'ing (inexpensively) soundproofing for a condo basement in Canada.* I'm familiar with the basic concepts of soundproofing (mass=blocker, resonance is bad, viscoelasticity, etc), but need advice here.
> 
> Basically, *I have adjoined neighbors to the east and west.* I'm planning on *making the basement a theater room* (on a budget, since we both work part-time to support ourselves in volunteer work) *soundproofing the basement walls against my neighbors* to at least provide some level of sound dampening. *Not the ceiling*, since I won't be able to get access up there without major renovations, and I'm hoping the fact it'd need to travel through additional walls (the ceiling, floor, and then neighboring walls) will help avoid the need to touch the ceiling. The east wall is a straight 8' by about 10-12' stretch. Along the west wall has my mechanical room - this is basically a room within the basement, and this allows me currently to access the inside of that wall to insulate. I can also add drywall to the walls INSIDE the mechanical room since there isn't any as of yet. Total stretch would be about 14'-16', excluding the mechanical room?
> 
> *Basically, I'm down to 3 options.* I'm looking for *best "bang for your buck"*. I'd like to watch Interstellar, for example, at reasonable volumes with a proper soundsetup without worrying about my elderly neighbors in their upstairs bedroom. I want to mitigate as best as I can.
> 
> *1.* Tear down the east wall, add insulation (planning to use Rockwool), and replace with new drywall. Instead of 1/2 drywall ($12/sheet) or "soundproofing" drywall with a viscoelastic layer ($60/sheet)", I'm planning to use 5/8 Type X (firecode) drywall ($17/sheet), which is 100lb a sheet vs 40lb a sheet for regular drywall. *The drywall will be well over 1lb/ft.* Then insulate the back of the west wall with Rockwool. Leave the west wall itself as is. Not sure if there's resilient channel?
> 
> *2.* Tear down both the east and west walls, add Rockwool, and replace both walls with Type X drywall.
> 
> *3.* Leave the existing walls and add a new layer of drywall to both the east and west sides, possibly with MLV in between (most expensive by far, $241/100sqft from a local supplier where I pickup, so probably $500+ just in MLV). *I would have no idea how to do this*, or what hardware to use for spacing the drywall.
> 
> I'm not familiar with "green glue" or any other specialty building products for sound reduction. My expertise is in auto sound reduction, which isn't really "expert" by any means. What's my best option here...?
> 
> The existing flooring is carpet, and* I'm planning on redoing the floor with hardwood* as well. So if adding another drywall layer is best, how should I do the flooring...? First? Doing the flooring first might be slightly problematic since we have a painter already working through the house, I'd like to get this done before he gets to the basement (within a couple of weeks), and this will be a job I'm working on almost entirely in my off-time (evenings).


Since this is a basement, i'm assuming your have concrete or concrete block walls between the units and the floor will be concrete.

If this is the case, you probably don't need to do anything with the floor except going from carpet to hardwood will increase reflections vs absorbing sound. Adding mass to the walls is fine but I believe, after doing something similar in my basement, you need to be mainly concerned about sound transmitting through the ceiling up to the living space. If you do nothing with the ceiling, no only will you will get flanking through the rim joists but you will start vibrating the structure which will transmit to the rest of the unit. If you plan to use a subwoofer and play movies and music at reference levels, you have to soundproof the ceiling. If you can't tear down the existing ceiling, I would use a product like Quiet Rock or equivalent and put a layer of 5/8 on top of the existing ceiling sheetrock. This should give you a significant reduction in sound transmittal but at the end of the day don't expect 100% sound proofing if you plan to turn up the sub.


----------



## HT Geek

Colton Walker said:


> Hey all! First post here. I'm sorry if I'm not adhering to any rules I may have missed.
> 
> *I'm looking at DIY'ing (inexpensively) soundproofing for a condo basement in Canada.* I'm familiar with the basic concepts of soundproofing (mass=blocker, resonance is bad, viscoelasticity, etc), but need advice here.
> 
> Basically, *I have adjoined neighbors to the east and west.* I'm planning on *making the basement a theater room* (on a budget, since we both work part-time to support ourselves in volunteer work) *soundproofing the basement walls against my neighbors* to at least provide some level of sound dampening. *Not the ceiling*, since I won't be able to get access up there without major renovations, and I'm hoping the fact it'd need to travel through additional walls (the ceiling, floor, and then neighboring walls) will help avoid the need to touch the ceiling. The east wall is a straight 8' by about 10-12' stretch. Along the west wall has my mechanical room - this is basically a room within the basement, and this allows me currently to access the inside of that wall to insulate. I can also add drywall to the walls INSIDE the mechanical room since there isn't any as of yet. Total stretch would be about 14'-16', excluding the mechanical room?
> 
> *Basically, I'm down to 3 options.* I'm looking for *best "bang for your buck"*. I'd like to watch Interstellar, for example, at reasonable volumes with a proper soundsetup without worrying about my elderly neighbors in their upstairs bedroom. I want to mitigate as best as I can.
> 
> *1.* Tear down the east wall, add insulation (planning to use Rockwool), and replace with new drywall. Instead of 1/2 drywall ($12/sheet) or "soundproofing" drywall with a viscoelastic layer ($60/sheet)", I'm planning to use 5/8 Type X (firecode) drywall ($17/sheet), which is 100lb a sheet vs 40lb a sheet for regular drywall. *The drywall will be well over 1lb/ft.* Then insulate the back of the west wall with Rockwool. Leave the west wall itself as is. Not sure if there's resilient channel?
> 
> *2.* Tear down both the east and west walls, add Rockwool, and replace both walls with Type X drywall.
> 
> *3.* Leave the existing walls and add a new layer of drywall to both the east and west sides, possibly with MLV in between (most expensive by far, $241/100sqft from a local supplier where I pickup, so probably $500+ just in MLV). *I would have no idea how to do this*, or what hardware to use for spacing the drywall.
> 
> I'm not familiar with "green glue" or any other specialty building products for sound reduction. My expertise is in auto sound reduction, which isn't really "expert" by any means. What's my best option here...?
> 
> The existing flooring is carpet, and* I'm planning on redoing the floor with hardwood* as well. So if adding another drywall layer is best, how should I do the flooring...? First? Doing the flooring first might be slightly problematic since we have a painter already working through the house, I'd like to get this done before he gets to the basement (within a couple of weeks), and this will be a job I'm working on almost entirely in my off-time (evenings).





jrref said:


> Since this is a basement, i'm assuming your have concrete or concrete block walls between the units and the floor will be concrete.
> 
> If this is the case, you probably don't need to do anything with the floor except going from carpet to hardwood will increase reflections vs absorbing sound. Adding mass to the walls is fine but I believe, after doing something similar in my basement, you need to be mainly concerned about sound transmitting through the ceiling up to the living space. If you do nothing with the ceiling, no only will you will get flanking through the rim joists but you will start vibrating the structure which will transmit to the rest of the unit. If you plan to use a subwoofer and play movies and music at reference levels, you have to soundproof the ceiling. If you can't tear down the existing ceiling, I would use a product like Quiet Rock or equivalent and put a layer of 5/8 on top of the existing ceiling sheetrock. This should give you a significant reduction in sound transmittal but at the end of the day don't expect 100% sound proofing if you plan to turn up the sub.


I generally concur with @jrrefcomments, but I'll throw in some anecdotal thoughts. 

Are you unconcerned with sound permeation to your neighbors' basement levels, but just their upper floors? What's the basis for avoiding an improvement of the ceiling? Height???

It seems likely that with shared walls, sound is going to vibrate and traverse upward as well as outward, especially if there are shared studs. If there are not shared studs but a shared center, such as cinder blocks between two sets of studs (one on either side of the wall), then insulating the ceiling is likely more important than insulating the walls, though I would not discount making an improvement to the walls as well.

Furthermore, there is little point and ripping out existing 1/2" drywall simply to replace it with 5/8" drywall. The primary benefit of 5/8" vs. 1/2" is in layering. There's little damping difference between 1/2" and 5/8" (1-3 db, depending on what measurement you look at, and most are 1 db). However, when you start looking at say 2x 1/2" vs. 2x 5/8", or even 3x sheets thick, then you begin to see a wider divergence in performance (more mass = better). The thicker walls also are more effective in the sense of having a greater affect on shifting the resonant freq of the wall downward.

I'll throw out a couple other ideas for you:

1. Point being... you might as well just add another layer of drywall to your side walls if you won't be using any other method, and spend some of your budget on revisiting the ceiling. For instance, clips & channel to hang 1 or 2 sheets of drywall from the ceiling (ideally 2), plus just attach more mass to the side walls. 

2. Build an interior wall beside each east and west wall, and hang ceiling joists from it to create a partial "room within a room" effect. Strip old drywall off walls and ceiling first. This approach would be highly dependent on your height clearance. You would likely need 2x8 joists based on your room dimensions. You might be able to get away with 2x6's but they would have to be ~12" apart or so (I haven't done the math, but that is based on an educated guess) to support the span.

This all boils down to the fact if you're only going to add mass into the equation, you need to think about adding mass in 3 dimensions and not 2.

Regarding Green Glue, it is a visco-elastic binder. The name comes from its green appearance. The product takes roughly 15-45 days to cure, depending on climate, and helps by lowering the resonance of the surfaces its placed between. It acts as a sort of flexible binder and is particularly beneficial for low frequency absorption. 

Recommend against hardwood in an HT room. It will cause undesirable audio reflections. It may also cause some light reflection issues from your screen (depends on the flooring material and finish). If you don't want carpet, consider just concrete (could be stained to match your room) and throw down some rugs.

Back to sound proofing... one more idea... in a different direction... you may find sound absorbing blocks could be used, particularly in the corners where all 3 dimensions of sound waves interact. That approach could be used effectively to mitigate sound travel out of the room. If you want to explore that route, it is beyond my expertise and experience, but there are a number of folks on this forum who specialize in sound proofing via that method. The potential downsides include appearance and having the physical space to use them.


----------



## Colton Walker

Quick note: the basement is weirdly shaped. Pic attatched with all dimensions and a drawing. Entrance is on the bottom (currently no door, will have to be fixed of course).

Jrref:


Spoiler






jrref said:


> Since this is a basement, i'm assuming your have concrete or concrete block walls between the units and the floor will be concrete.
> 
> If this is the case, you probably don't need to do anything with the floor except going from carpet to hardwood will increase reflections vs absorbing sound. Adding mass to the walls is fine but I believe, after doing something similar in my basement, you need to be mainly concerned about sound transmitting through the ceiling up to the living space. If you do nothing with the ceiling, no only will you will get flanking through the rim joists but you will start vibrating the structure which will transmit to the rest of the unit. If you plan to use a subwoofer and play movies and music at reference levels, you have to soundproof the ceiling. If you can't tear down the existing ceiling, I would use a product like Quiet Rock or equivalent and put a layer of 5/8 on top of the existing ceiling sheetrock. This should give you a significant reduction in sound transmittal but at the end of the day don't expect 100% sound proofing if you plan to turn up the sub.






Concrete block walls in the basement I believe, yes. The floor is concrete as well. We may leave the carpet, due to the acoustical benefits it provides. The basement, with a 7ft ceiling, is directly below the living room which has a 16ft ceiling, and directly above that is bedrooms. The neighbors unit, once you get out of the basement, is separated only by drywall as far as I can tell (I haven't taken the wall apart, but when I look in behind the electrical boxes I can see brown paper backing of drywall board on all levels except the basement). 

I definitely plan on using a subwoofer - at the very least a front/center/sub system, and maybe up to 5.1 at some point.

I'm not totally against doing anything with the ceiling after seeing the feedback, but I have one 6'x6' area where the roof drops to between 6' and 6'4" high due to ducting. There's some weird ductwork in that room.

HT Geek:


Spoiler






HT Geek said:


> I generally concur with @jrrefcomments, but I'll throw in some anecdotal thoughts.
> 
> Are you unconcerned with sound permeation to your neighbors' basement levels, but just their upper floors? What's the basis for avoiding an improvement of the ceiling? Height???
> 
> It seems likely that with shared walls, sound is going to vibrate and traverse upward as well as outward, especially if there are shared studs. If there are not shared studs but a shared center, such as cinder blocks between two sets of studs (one on either side of the wall), then insulating the ceiling is likely more important than insulating the walls, though I would not discount making an improvement to the walls as well.
> 
> Furthermore, there is little point and ripping out existing 1/2" drywall simply to replace it with 5/8" drywall. The primary benefit of 5/8" vs. 1/2" is in layering. There's little damping difference between 1/2" and 5/8" (1-3 db, depending on what measurement you look at, and most are 1 db). However, when you start looking at say 2x 1/2" vs. 2x 5/8", or even 3x sheets thick, then you begin to see a wider divergence in performance (more mass = better). The thicker walls also are more effective in the sense of having a greater affect on shifting the resonant freq of the wall downward.
> 
> I'll throw out a couple other ideas for you:
> 
> 1. Point being... you might as well just add another layer of drywall to your side walls if you won't be using any other method, and spend some of your budget on revisiting the ceiling. For instance, clips & channel to hang 1 or 2 sheets of drywall from the ceiling (ideally 2), plus just attach more mass to the side walls.
> 
> 2. Build an interior wall beside each east and west wall, and hang ceiling joists from it to create a partial "room within a room" effect. Strip old drywall off walls and ceiling first. This approach would be highly dependent on your height clearance. You would likely need 2x8 joists based on your room dimensions. You might be able to get away with 2x6's but they would have to be ~12" apart or so (I haven't done the math, but that is based on an educated guess) to support the span.
> 
> This all boils down to the fact if you're only going to add mass into the equation, you need to think about adding mass in 3 dimensions and not 2.
> 
> Regarding Green Glue, it is a visco-elastic binder. The name comes from its green appearance. The product takes roughly 15-45 days to cure, depending on climate, and helps by lowering the resonance of the surfaces its placed between. It acts as a sort of flexible binder and is particularly beneficial for low frequency absorption.
> 
> Recommend against hardwood in an HT room. It will cause undesirable audio reflections. It may also cause some light reflection issues from your screen (depends on the flooring material and finish). If you don't want carpet, consider just concrete (could be stained to match your room) and throw down some rugs.
> 
> Back to sound proofing... one more idea... in a different direction... you may find sound absorbing blocks could be used, particularly in the corners where all 3 dimensions of sound waves interact. That approach could be used effectively to mitigate sound travel out of the room. If you want to explore that route, it is beyond my expertise and experience, but there are a number of folks on this forum who specialize in sound proofing via that method. The potential downsides include appearance and having the physical space to use them.






*I'll try to be more clear with my needs. This will be a home theater to entertain guests with movies.* Talking TRON:Legacy, Interstellar, the Batman trilogy, Inception, etc. Powerful films that need good sound to even come close to being fully appreciated. *I'm concerned mainly with the sound bothering my neighbors.* *The basement has shared centers* (cinder, I believe), but *above that is shared studs* as far as I can tell. Noise travelling inside my place isn't as big an issue as keeping it away from the neighbors, but I figure once the noise leaves the basement, it's going to *carry straight through my structure into their living space/bedrooms*. I seem to get from feedback here that the ceiling is core. *The issue is that there's a LOT of ducting in the ceiling*. About 80-90 sq ft of drywall just covering ducting. The room is 18' x 12', 7'1" with a 6' x 7' mechanical room. Taking out the mechanical room, the drywall needed for the ceiling works out to about 230sqft with a lot of cuts and corners.

*I'm willing to tear out all of the drywall if need be*, but my budget for the whole room is going to be around *$600 CAD MAXIMUM*. Lower is better, but I'll be doing all the work myself.

Side note:* the mechanical room doesn't even have drywall or insulation inside of it*. I'm assuming I should insulate and add drywall at a minimum - but is there anything else I can do for relatively little spend to keep the furnace noise down?

Some revised ideas based on the suggestions of you two. DEEPLY appreciated.

*1a. The drywall on the walls.* In line with some of the suggestions here - my painter has worked in construction for decades. He's worked with resilient channel before, and understands a bit about soundproofing with it. I understand that clips are better, but Clips are EXPENSIVE, and I doubt there's any way I can afford more than $150-$200CAD for hardware. Requiring gaps around the drywall when clipping, caulking the joints, etc...he suggested screwing resilient channel directly into the existing gypsum on the walls (I assume into the studs, but perhaps using wall plugs?), and then hang new Type X gypsum on top. The stuff here is about 3.2lb/sqft. He suggested Styrofoam to fill the gap between the two, but I assume that may do more harm then good. Not sure. Is this an acceptable option?

*1b.* Simply add another layer of drywall directly onto the existing walls, using Green Glue in between. Which option would offer better attenuation?

*1c.* Build a false wall around the whole perimeter. I'd need to take up the floor to do this I assume? That's a much bigger job, but I assume the best option.

Combine option of choice for 1 with:

*2a.* *The ceiling.* I can rent a drywall lift to hold it in place for me. I already have a clearance issue in the one spot of the room, the bottom in the diagram just to the right of the entrance. 6'. That goes up to 6'4" by the other end, but anyway. What should I do with this...? Take it down, insulate, add resonance control to the duct (if anyone is familiar with automotive sound deadening, I'd use CLD Tiles (one of the best viscoelastic stick-on materials around)), and then mount new drywall using (MAYBE) clips, or resilient channel? I have no idea how to handle all of the ductwork with this. Clips are likely way out of my budget. Resilient channel is cheap, and if instructed how to install it I'm sure I can do it properly.

*2b/c.* Mirroring 1a and 1b - either use resilient channel and add a layer, or green glue and add a layer of drywall.

*2c.* Lower the entire ceiling to about 6'4", in line with that ductwork. Add insulation. I could try to force some of that low ductwork higher up by modifying the ceiling. I mean, it's probably doable...? And may give the best result? But that could really mess up acoustics and make the room feel way too small. I don't know.

*2d.* Tear the entire ceiling out for the heck of it, then decide what to do.


----------



## HT Geek

Colton Walker said:


> Quick note: the basement is weirdly shaped. Pic attatched with all dimensions and a drawing. Entrance is on the bottom (currently no door, will have to be fixed of course).
> 
> ....
> 
> 
> 
> Concrete block walls in the basement I believe, yes. The floor is concrete as well. We may leave the carpet, due to the acoustical benefits it provides. The basement, with a 7ft ceiling, is directly below the living room ... The neighbors unit, once you get out of the basement, is separated only by drywall as far as I can tell (I haven't taken the wall apart, but when I look in behind the electrical boxes I can see brown paper backing of drywall board on all levels except the basement).
> 
> 
> ....
> 
> *I'm concerned mainly with the sound bothering my neighbors.* *The basement has shared centers* (cinder, I believe), but *above that is shared studs* as far as I can tell. Noise travelling inside my place isn't as big an issue as keeping it away from the neighbors, but I figure once the noise leaves the basement, it's going to *carry straight through my structure into their living space/bedrooms*. I seem to get from feedback here that the ceiling is core. *The issue is that there's a LOT of ducting in the ceiling*. About 80-90 sq ft of drywall just covering ducting. The room is 18' x 12', 7'1" with a 6' x 7' mechanical room. Taking out the mechanical room, the drywall needed for the ceiling works out to about 230sqft with a lot of cuts and corners.
> 
> 
> ....
> 
> *I'm willing to tear out all of the drywall if need be*, but my budget for the whole room is going to be around *$600 CAD MAXIMUM*. Lower is better, but I'll be doing all the work myself.
> 
> Side note:* the mechanical room doesn't even have drywall or insulation inside of it*. I'm assuming I should insulate and add drywall at a minimum - but is there anything else I can do for relatively little spend to keep the furnace noise down?



Double drywall layers on the walls of the mechanical room. Thoughtful positioning of door to the mechanical room. That's on the cheap end of the scale.


What are your thoughts on the portion of the room you envision as your HT area? Could you outline that space on your diagram and describe it?


What is the minimum ceiling height in the basement allowed by code? What is the minimum height acceptable to you?


I'm concerned your biggest issue is likely to be flanking noise from the corners where the walls and ceiling meet. Somewhere up there behind the walls will be a transition from concrete block to shared studs, with regards to your home and your neighbors'.


> *1a. The drywall on the walls....* my painter .... he suggested screwing resilient channel directly into the existing gypsum on the walls (I assume into the studs, but perhaps using wall plugs?), and then hang new Type X gypsum on top. The stuff here is about 3.2lb/sqft. He suggested Styrofoam to fill the gap between the two, but I assume that may do more harm then good. Not sure. Is this an acceptable option?


Normally, no. However, in your case I think you could reasonably do that. Since you have a concrete block wall anyway, attaching drywall to it directly is a bit unorthodox, but it can be done and there have been a (very) tests that looked at that as an option. The key is you should mud the wall first, as it were another layer of drywall. Seal all the crevices and layer a think coat of mud over the concrete blocks, then apply the drywall and secure it. The point of the mud is that without it, you will have tiny air gaps all over the place between the drywall sheet and the concrete. 

A better method would be to apply Green Glue on the back of those drywall sheets, and then slap them onto the concrete block. That would do 2 things for you: 1) you don't need to worry about the uneven surface of the concrete blocks, provided their raw surface dimples are shallower than the Green Glue layer (which ought to be the case); and 2) the properties of Green Glue will provide you additional improvement in reducing the resonance of the wall.

It's a bit unorthodox of an approach for purists, but every build is different and IMHO sometimes you have to be creative in adapting to the budget and circumstances of the homeowner, so there you have one suggestion for how to deal with the walls. 

Now... GG is expensive. It's going to run you around $10/tube or more. You will need a minimum of 1 tube per 4x8 drywall sheet. Minimum. And in this type of scenario, I would use at least 2 because of the texture of the concrete blocks. OR you could possibly try the mudding idea (smooth out the concrete surface), then layer GG + drywall sheet on top. More work. Possibly cheaper.

If you mud the walls first, take care to make them as uniform as possible before you allow it to dry and apply the drywall, using whichever method. Your goal is to add mass to the existing wall, such that you are not creating an air gap during the process of adding mass.

*



1b.

Click to expand...

*


> Simply add another layer of drywall directly onto the existing walls, using Green Glue in between. Which option would offer better attenuation?
> 
> *1c.* Build a false wall around the whole perimeter. I'd need to take up the floor to do this I assume? That's a much bigger job, but I assume the best option.


Correct. 1c would be the best approach. You would need to remove any floor finishing (i.e. carpet or hardwood, etc.). You must get to the bare concrete. You would also need to consider how the interior wall would be secured. It would be ideal to place the interior wall on a system of padded flooring, such as plywood/rubber mat/plywood, but I doubt that is realistic from the perspectives of room height and cost.



> Combine option of choice for 1 with:
> 
> *2a.* *The ceiling.* I can rent a drywall lift to hold it in place for me. I already have a clearance issue in the one spot of the room, the bottom in the diagram just to the right of the entrance. 6'. That goes up to 6'4" by the other end, but anyway. What should I do with this...? Take it down, insulate, add resonance control to the duct (if anyone is familiar with automotive sound deadening, I'd use CLD Tiles (one of the best viscoelastic stick-on materials around)), and then mount new drywall using (MAYBE) clips, or resilient channel? I have no idea how to handle all of the ductwork with this. Clips are likely way out of my budget. Resilient channel is cheap, and if instructed how to install it I'm sure I can do it properly.
> 
> *2b/c.* Mirroring 1a and 1b - either use resilient channel and add a layer, or green glue and add a layer of drywall.
> 
> *2c.* Lower the entire ceiling to about 6'4", in line with that ductwork. Add insulation. I could try to force some of that low ductwork higher up by modifying the ceiling. I mean, it's probably doable...? And may give the best result? But that could really mess up acoustics and make the room feel way too small. I don't know.


From the perspective of uniformity, that may be a good option. Moving the ductwork would depend on a number of factors. You might have to resize portions of it, and that could present building code issues or create other problems. All depends on its purpose and other factors. I hate to be so vague, but you just won't know unless you rip out the ceiling around it and examine the situation. Then you can determine your options.

Lowering the ceiling height won't mess up the acoustics, as you said, but psychologically if the room is disproportionately long, it may feel like you're in a tunnel. Height is one of those things that has a different effect for different people. It's also relative to your height (and your guests), of course. That said, you will be sitting down most of the time.

Another factor related to height is if you plan to use a projector, you need to consider where it would be mounted relative to pedestrian pathways and seating location. This is where creative placement of seats, door, etc. comes into play.




> *2d.* Tear the entire ceiling out for the heck of it, then decide what to do.



LoL  Sometimes, it's not a bad idea. It forces you to figure out a solution and you are able to see what is and isn't possible. Worst case scenario is you have to replace the ceiling in the exact same position/design.


I'm thinking before you go any further, you need to figure out where your screen is going to be, your seating plan, type and placement of speakers.


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## jrref

There is a lot of details in the above posts but you have to trust that unless you make the right decisions and treat your ceiling, your sub will vibrate the structure above the basement and everyone will be disturbed especially at night if there is no ambient noise. You have a typical basement ceiling height problem so you are probably best adding 5/8 quiet rock or equivalent to the ceiling and treat all the walls because even with all kinds of sound proofing treatments, if you play the sub at reference level, you will still hear it everywhere if you live in a condo or apartment and have neighbors. The only sure way to stop the sub is to build a room in a room and you don't have the space for that. The alternative is to treat the ceiling and walls and just don't turn the sub all the way up. From my experience if you live in a condo or apartment with neighbors, pretty much no matter what you do, your neighbors will hear the sub. I just turn mine down and have no problems.


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## Colton Walker

Looking at both those replies now and trying to formulate my options. Thanks a ton for the information.

Just a note, the walls are NOT bare concrete. That is only the one wall in the mechanical room. There are walls with (I believe) studs and existing drywall in the entire basement right now, built off of the concrete walls. So the layering is:

My basement>drywall>studs>concrete


----------



## jrref

Colton Walker said:


> Looking at both those replies now and trying to formulate my options. Thanks a ton for the information.
> 
> Just a note, the walls are NOT bare concrete. That is only the one wall in the mechanical room. There are walls with (I believe) studs and existing drywall in the entire basement right now, built off of the concrete walls. So the layering is:
> 
> My basement>drywall>studs>concrete


----------



## Colton Walker

jrref said:


> Right so if that is the case the simplest way to treat everything without tearing everything down is to just put 5/8 inch Quiet Rock or equivalent over the existing sheetrock on the walls and ceiling and call it a day. The extra mass will give you a significant reduction in sound transmittal and their is probably some sort of insulation in the walls. You could tear everything down and maybe make some tweaks by putting insulation in the ceiling but it would probably only be a minimal improvement.


Okay, that's good to know! Couple of questions.

1. Quiet rock has a viscoelastic core to kill resonance. It's also heavy. I understand how these things bring benefits. However, I'll need 18.5 (19) sheets of it to cover the walls and ceiling. I can only find viscoelastic board (SilentFX drywall) from Lowes here in Canada that I can see. It weighs 67lbs (2.1lb/ft), 1/2", and it's $85 a sheet. That's $1,400 in drywall alone. How much of a benefit would this be over Type X 5/8" drywall that costs $20 a sheet, with no viscoelastic layer, but at 109lb a sheet (3.4lb/ft)? That's $400. 

2. I could possibly budget for enough tubes of Green Glue if I can find a supplier; current supplier is Home Depot at $19 a tube, but that's too much I think. I have a company that supplies sound dampening hardware within an hour of me that might be considerably cheaper. Would this be worthwhile?

3. Would hanging the second layer off the ceiling using resilient channel (attatched to the drywall, or the joists THROUGH the existing drywall) help with dampening at all? Or should I stick to Green Glue?


----------



## jrref

Colton Walker said:


> Okay, that's good to know! Couple of questions.
> 
> 1. Quiet rock has a viscoelastic core to kill resonance. It's also heavy. I understand how these things bring benefits. However, I'll need 18.5 (19) sheets of it to cover the walls and ceiling. I can only find viscoelastic board (SilentFX drywall) from Lowes here in Canada that I can see. It weighs 67lbs (2.1lb/ft), 1/2", and it's $85 a sheet. That's $1,400 in drywall alone. How much of a benefit would this be over Type X 5/8" drywall that costs $20 a sheet, with no viscoelastic layer, but at 109lb a sheet (3.4lb/ft)? That's $400.
> 
> 2. I could possibly budget for enough tubes of Green Glue if I can find a supplier; current supplier is Home Depot at $19 a tube, but that's too much I think. I have a company that supplies sound dampening hardware within an hour of me that might be considerably cheaper. Would this be worthwhile?
> 
> 3. Would hanging the second layer off the ceiling using resilient channel (attatched to the drywall, or the joists THROUGH the existing drywall) help with dampening at all? Or should I stick to Green Glue?


If you want to accomplish soundproofing as you described you need the viscoelastic layer and it's best to be 5/8. Green Glue is fine but that means more labor for you. Using clips, resilient channel, etc, will use up more of your ceiling height and normally they are used with quiet rock or sheetrock with green glue.

Bottom line, if you want to blast music and movies without disturbing your neighbors you are going to need a soundproofing solution like many have described to you and it can get expensive depending on how large your room is.


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## doveman

impreza276 said:


> Either green or purple board would work fine, as long as you go for high density 5/8, not the lightweight stuff. You want drywall that weighs at least 2.2lbs per sqft. The weight and the mold resistance are the important factors to look for, for your application. I used Purple XP for my basement. You do not need to look for 'soundproof' drywall if what you can get meets the weight criteria. From what I have read, different thicknesses do not make a difference. Have you read https://www.soundproofingcompany.com/soundproofing101 ?


Thanks. I don't think I've seen those articles before, although I've looked at soundproofingcompany.com in the past.

On this page https://www.soundproofingcompany.com/soundproofing_101/building-a-room-within-a-room it says under "Mass: Adding drywall" "Different thicknesses of drywall are often recommended. Read this next section that describes damping, but if you do not damp the drywall, then consider mixing 1/2" and 5/8" drywall. Each will resonate at a different point. If you are planning to damp the drywall, then forget to mix the thicknesses. Just go with the thickest and heaviest drywall you can deal with." So I'll have to consider the pros and cons of mixing thicknesses of drywall compared to using Green Glue.

I also see here https://www.soundproofingcompany.com/soundproofing_101/building-materials-weights-guide that 5/8" Gypsum is about 2.2lbs per sqft, plywood is 1.5lbs per sqft and OSB is 2.08lbs per sqft. I'll need to use a small section of plywood or OSB in the centre of my ceilings to support the lampshades and I'll probably need to use wood for the first layer on the walls as well to allow for stuff to be screwed to them. Is there any disadvantage with using OSB for this instead of plywood? Should I specifically use OSB3 rather than OSB2?


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## impreza276

doveman said:


> Thanks. I don't think I've seen those articles before, although I've looked at soundproofingcompany.com in the past.
> 
> On this page https://www.soundproofingcompany.com/soundproofing_101/building-a-room-within-a-room it says under "Mass: Adding drywall" "Different thicknesses of drywall are often recommended. Read this next section that describes damping, but if you do not damp the drywall, then consider mixing 1/2" and 5/8" drywall. Each will resonate at a different point. If you are planning to damp the drywall, then forget to mix the thicknesses. Just go with the thickest and heaviest drywall you can deal with." So I'll have to consider the pros and cons of mixing thicknesses of drywall compared to using Green Glue.
> 
> I also see here https://www.soundproofingcompany.com/soundproofing_101/building-materials-weights-guide that 5/8" Gypsum is about 2.2lbs per sqft, plywood is 1.5lbs per sqft and OSB is 2.08lbs per sqft. I'll need to use a small section of plywood or OSB in the centre of my ceilings to support the lampshades and I'll probably need to use wood for the first layer on the walls as well to allow for stuff to be screwed to them. Is there any disadvantage with using OSB for this instead of plywood? Should I specifically use OSB3 rather than OSB2?


Here is the quote: "Different thicknesses of drywall are often recommended. Read this next section that describes damping, but if you do not damp the drywall, then consider mixing 1/2" and 5/8" drywall. Each will resonate at a different point. *If you are planning to damp the drywall, then forget to mix the thicknesses. Just go with the thickest and heaviest drywall you can deal with*". In other words, if you plan to use green glue - which you should - forget about mixing thicknesses. In many cases the new 1/2 inch drywall is half the density of 5/8.

OSB is harder to work with. You can go ahead and use it if you prefer to.


----------



## jrref

The basic physics behind this is the sound from your music translates to energy vibrating your wall, etc.. The more mass, the more energy is needed to vibrate the wall structure. Different frequencies have different energy levels which is why it's easier to block mid and high frequencies vs low frequencies. Decoupling also helps a lot and fits into the equation. What's difficult to overcome is when people get two of the most powerful subs they can afford for their system which translates to a lot of energy needed to be blocked and thus an more aggressive soundproofing system.

At the end of the day, I often wonder the wisdom of playing music or movies at reference levels when over time you are just permanently damaging your ears which you won't realize until you are older and can't do anything about it.

I live in an attached condo with neighbors and I've applied aggressive soundproofing to the common wall. What I've learned is although you get a certain amount of attenuation of sound transmission, it's attenuation, not 100% blocked which means if you turn up your sound system enough you will eventually exceed what the wall and ceiling, etc can block. I feel the only way to get near total soundproofing is to do a room in a room and use 3/4inch sheetrock with GG or equivalent like they do in sound studios.

For my specific situation, I've tested to see how loud I can play my system before my neighbors can just start to hear it and I set that as my limit and it's plenty loud, just not blasting.

Hope this helps.


----------



## impreza276

doveman said:


> Thanks. I don't think I've seen those articles before, although I've looked at soundproofingcompany.com in the past.
> 
> On this page https://www.soundproofingcompany.com/soundproofing_101/building-a-room-within-a-room it says under "Mass: Adding drywall" "Different thicknesses of drywall are often recommended. Read this next section that describes damping, but if you do not damp the drywall, then consider mixing 1/2" and 5/8" drywall. Each will resonate at a different point. If you are planning to damp the drywall, then forget to mix the thicknesses. Just go with the thickest and heaviest drywall you can deal with." So I'll have to consider the pros and cons of mixing thicknesses of drywall compared to using Green Glue.
> 
> I also see here https://www.soundproofingcompany.com/soundproofing_101/building-materials-weights-guide that 5/8" Gypsum is about 2.2lbs per sqft, plywood is 1.5lbs per sqft and OSB is 2.08lbs per sqft. I'll need to use a small section of plywood or OSB in the centre of my ceilings to support the lampshades and I'll probably need to use wood for the first layer on the walls as well to allow for stuff to be screwed to them. Is there any disadvantage with using OSB for this instead of plywood? Should I specifically use OSB3 rather than OSB2?



I must have been half asleep when I replied to you. Mixing thicknesses vs applying green glue are not alternative methods of achieving the same result. Using green glue with the thickest drywall available for both layers is unequivocally superior.

There is no disadvantage of using OSB over plywood as the first layer for your chandelier support areas .


----------



## HT Geek

jrref said:


> Right so if that is the case the simplest way to treat everything without tearing everything down is to just put 5/8 inch Quiet Rock or equivalent over the existing sheetrock on the walls and ceiling and call it a day. The extra mass will give you a significant reduction in sound transmittal and their is probably some sort of insulation in the walls. You could tear everything down and maybe make some tweaks by putting insulation in the ceiling but it would probably only be a minimal improvement.


+1 when you're on a budget. It's the most economical option.


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## Colton Walker

HT Geek said:


> +1 when you're on a budget. It's the most economical option.


I think this is what I'm going to do. Add a layer of 5/8 sheetrock on top of the 1/2 existing on the ceiling and walls. Only question I have is this: would I gain more from 

a) Fastening resilient channel to the joists through the existing gypsum board, attach the 2nd layer to the resilient channel, then use Green Glue Acoustic Sealant to plug all the gaps.

b) Fasten the 2nd layer of 5/8 drywall directly to the existing gypsum board, using Green Glue Soundproofing Compound between the two layers.


----------



## HT Geek

Colton Walker said:


> I think this is what I'm going to do. Add a layer of 5/8 sheetrock on top of the 1/2 existing on the ceiling and walls. Only question I have is this: would I gain more from
> 
> a) Fastening resilient channel to the joists through the existing gypsum board, attach the 2nd layer to the resilient channel, then use Green Glue Acoustic Sealant to plug all the gaps.
> 
> b) Fasten the 2nd layer of 5/8 drywall directly to the existing gypsum board, using Green Glue Soundproofing Compound between the two layers.


*b*

Please don't do "a", as you will create additional pathways for sound vibrations via the screws into the studs. You'd effectively be reducing the sound dampening properties of the original, pre-existing sheet of drywall. What you'd want to do - if you were to use RC - would be to first remove the pre-existing drywall layer and then attach the RC, then 1-2 layers of drywall to the RC.

RC is generally not recommended.


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## Buzniak

Is ther a very budget effective way you can soundproof a room that can compete with the most common way of proofing a room?


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## jrref

Buzniak said:


> Is ther a very budget effective way you can soundproof a room that can compete with the most common way of proofing a room?


No


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## HT Geek

Buzniak said:


> Is ther a very budget effective way you can soundproof a room that can compete with the most common way of proofing a room?


There really isn't a "common way" of sound proofing a room, unless you are talking about standard building practices, which are insufficient as far as anyone participating on this forum is concerned!

Every situation is unique. The optimal solution for anyone depends on a combination of goals and abilities (financial, know-how, available materials, etc.). I usually suggest first determining one's "must have" features or goals, and a set of "nice-to-haves." Then determine what would be required to meet each set of goals. Then evaluate your constraints, such as money, time, materials, and ability.

Most completed theater rooms end up somewhere between the minimum and the ideal. Also, those goal definitions nearly always shift during the transition from design to build, or during the build process, as unforeseen challenges are discovered.


----------



## jrref

HT Geek said:


> There really isn't a "common way" of sound proofing a room, unless you are talking about standard building practices, which are insufficient as far as anyone participating on this forum is concerned!
> 
> Every situation is unique. The optimal solution for anyone depends on a combination of goals and abilities (financial, know-how, available materials, etc.). I usually suggest first determining one's "must have" features or goals, and a set of "nice-to-haves." Then determine what would be required to meet each set of goals. Then evaluate your constraints, such as money, time, materials, and ability.
> 
> Most completed theater rooms end up somewhere between the minimum and the ideal. Also, those goal definitions nearly always shift during the transition from design to build, or during the build process, as unforeseen challenges are discovered.


And just to add, I've learned this from experience, if your goal it to play music and movies at reference levels, i.e. blasting, you automatically are going to need a costly and sophisticated solution and even then it won't be 100%. But if you are willing to limit the levels to a more reasonable level, then more cost effective solutions are available and you will also be saving your ears from cumulative permanent damage and still get an nice enjoyable sound field from your system.


----------



## Buzniak

HT Geek said:


> There really isn't a "common way" of sound proofing a room, unless you are talking about standard building practices, which are insufficient as far as anyone participating on this forum is concerned!
> 
> Every situation is unique. The optimal solution for anyone depends on a combination of goals and abilities (financial, know-how, available materials, etc.). I usually suggest first determining one's "must have" features or goals, and a set of "nice-to-haves." Then determine what would be required to meet each set of goals. Then evaluate your constraints, such as money, time, materials, and ability.
> 
> Most completed theater rooms end up somewhere between the minimum and the ideal. Also, those goal definitions nearly always shift during the transition from design to build, or during the build process, as unforeseen challenges are discovered.



Thank you very much for your input, will be doing some research and shopping around to find the most practical (affordable to me) materials out, The rooms is 100mm brick, so I might put in a offset wall then another wall (soft) (insulated/sound deadened) So in total 3 layers, It's the ceiling that has me worried, as I've been given some very good advice from Tedd on lowering the noise floor, the ceiling is going to be a tricky one.


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## swilson72

*Basement Ceiling*

I recently purchased a new house with an unfinished basement which I am putting a theater in. The drywall is almost finished, but I still haven't decided what to do with the ceiling. I don't want to put drywall on it because I have cables running through the ceiling that I may need access to. I am considering either a suspended ceiling, or just painting the unfinished ceiling black and putting acoustic foam tiles (https://www.amazon.ca/Arrowzoom-Sou...coustic+foam&qid=1553183656&s=gateway&sr=8-10) between most or all of the joists. So my question is, how much of a difference would there be in terms of room acoustics and soundproofing between these two options?


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## mhutchins

A suspended ceiling will offer better noise reduction and appearance than leaving the floor joists open and adding acoustic foam. The STC rating for a suspended ceiling is on the order of 12-15, whereas a standard ceiling with a single layer of drywall is around 37-40. With higher performance acoustic ceiling tiles you may be able to increase the STC into the low 20s.

Mike

NB: CAC is a very different measurement than STC but you will see most ceiling systems rated with a CAC. The primary difference is that STC measures the sound reduction of sound passing through the wall or ceiling (so just one pass through the sound absorbing layers). CAC measures the sound attenuation achieved when sound passes through the sound absorbing layers *twice* (once as the sound leaves the room and again when the sound enters the room next door through a common overhead plenum space with the same ceiling tiles).


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## Ladeback

swilson72 said:


> I recently purchased a new house with an unfinished basement which I am putting a theater in. The drywall is almost finished, but I still haven't decided what to do with the ceiling. I don't want to put drywall on it because I have cables running through the ceiling that I may need access to. I am considering either a suspended ceiling, or just painting the unfinished ceiling black and putting acoustic foam tiles (https://www.amazon.ca/Arrowzoom-Sou...coustic+foam&qid=1553183656&s=gateway&sr=8-10) between most or all of the joists. So my question is, how much of a difference would there be in terms of room acoustics and soundproofing between these two options?


A few other forum members has used cernteed theater black f ceiling tiles and I am as well. My room is 14'x26' and it roughly be about $680 with track wire and 2x2 tiles. 

Check this website out.
https://www.certainteed.com/acoustical-ceiling-panels/products/theatre-black-f/

I think these with some pink fluffy would be great. I am also thinking of put two layers of 5/8" drywall and Green Glue between the joists to help with noises coming from above.


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## swilson72

Ladeback said:


> A few other forum members has used cernteed theater black f ceiling tiles and I am as well. My room is 14'x26' and it roughly be about $680 with track wire and 2x2 tiles.
> 
> Check this website out.
> https://www.certainteed.com/acoustical-ceiling-panels/products/theatre-black-f/
> 
> I think these with some pink fluffy would be great. I am also thinking of put two layers of 5/8" drywall and Green Glue between the joists to help with noises coming from above.


Another idea that I am considering is to cut either drywall or ceiling tiles (or some of each) into strips and put them between the joists like in this picture. The picture is not my ceiling, but it looks just like that. I imagine drywall would be better but more difficult, and there are a few spots with ducting between the joists where I could proably fit in a tile, but probably not drywall. Perhaps I could cover the exposed portion of the joists with felt tape or something.










Basically I'm looking for something that I can do myself without any help, and that won't cost too much.


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## Ladeback

swilson72 said:


> Another idea that I am considering is to cut either drywall or ceiling tiles (or some of each) into strips and put them between the joists like in this picture. The picture is not my ceiling, but it looks just like that. I imagine drywall would be better but more difficult, and there are a few spots with ducting between the joists where I could proably fit in a tile, but probably not drywall. Perhaps I could cover the exposed portion of the joists with felt tape or something.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Basically I'm looking for something that I can do myself without any help, and that won't cost too much.


Not sure how much sound that will stop or slow down, but that is an interesting idea. I take it you have smart joist like I do. If you are trying to keep sound from going up or come from above you will need me mash. That's why I mentioned putting up 5/8" drywall with GG between the joists. You could do one layer then insulation and the drywall like you shown so you can access wires. You get both mass and convince to your wires. Others hopefully will chime in.


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## New Bob

*Room within a Room Question?*

I'm building a room within a room and inserting new I joist in between the existing upper ceiling joists and holding them 1- 1/2" lower. I'm thinking about blowing in insulation which is denser for sound then the light fluffy fiberglass stuff. The insulation would be touching the new joists and existing joists. Will I get sound transfer that way? I figured by blowing in insulation I would be getting over the top of the new joists and around all pipes much better. Is it o.k.not using green glue between the dd wall seeing the sound will not travel into the upper floor because of the 1-1/2" gap from the floor above anyway? Thanks in advance for your helpful replies! 



Thanks Bob Erickson.


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## HT Geek

New Bob said:


> I'm building a room within a room and inserting new I joist in between the existing upper ceiling joists and holding them 1- 1/2" lower. I'm thinking about blowing in insulation which is denser for sound then the light fluffy fiberglass stuff. The insulation would be touching the new joists and existing joists. Will I get sound transfer that way?


Not enough to warrant concern. In an ideal world, you'd have an air gap, but then that presents the potential for encouraging flanking in some situations, though that's likely also a remote possibility. Either way you look at it, you're likely better off filling the void with loosely applied insulation of whatever type.

If you prefer to use blown-in, go for it. I hate that stuff, personally. 



> I figured by blowing in insulation I would be getting over the top of the new joists and around all pipes much better.


Likely so unless you apply insulation before putting up the new ceiling and use kraft-paper backed so you can staple or find a similar method of securing it in place along the ceiling.



> Is it o.k.not using green glue between the dd wall seeing the sound will not travel into the upper floor because of the 1-1/2" gap from the floor above anyway? Thanks in advance for your helpful replies!


It's certainly "OK" under any circumstances, but if you wish to maximize sound insulation - and given the level-of-effort you are already going to - why would you want to skimp on the GG for your ceiling? I wouldn't. It's just another few hundred $ on a very expensive home improvement project!

Adding Green Glue will improve damping, especially for LFE. Another option would be to spend the $ on a 3rd layer of drywall, presuming the load bearing capability of your ceiling will take it (normally a non-issue).


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## doveman

impreza276 said:


> I must have been half asleep when I replied to you. Mixing thicknesses vs applying green glue are not alternative methods of achieving the same result. Using green glue with the thickest drywall available for both layers is unequivocally superior.
> 
> There is no disadvantage of using OSB over plywood as the first layer for your chandelier support areas .


No worries, I'm half asleep most of the time!

I didn't think that mixing thicknesses achieved the same result as applying green glue, although that website suggests it might by saying "If you are planning to damp the drywall, then forget to mix the thicknesses". That's the first time I've come across that advice, as previously I'd always read that varying the thickness of the drywall AND applying green glue was the ideal solution.

Even if applying green glue does address the resonance problem at least as effectively as using two different thicknesses of drywall though, there's still potential downsides to using two layers of 5/8" and green glue, such as the extra weight, loss of space and cost. So whilst it might be technically superior on paper, it might not be the right approach for my particular scenario.

I wish I had the space for chandeliers! Just simple lamp shades I'm afraid but good to know that OSB is as good as plywood for the first layer.


----------



## impreza276

doveman said:


> No worries, I'm half asleep most of the time!
> 
> I didn't think that mixing thicknesses achieved the same result as applying green glue, although that website suggests it might by saying "If you are planning to damp the drywall, then forget to mix the thicknesses". That's the first time I've come across that advice, as previously I'd always read that varying the thickness of the drywall AND applying green glue was the ideal solution.
> 
> Even if applying green glue does address the resonance problem at least as effectively as using two different thicknesses of drywall though, there's still potential downsides to using two layers of 5/8" and green glue, such as the extra weight, loss of space and cost. So whilst it might be technically superior on paper, it might not be the right approach for my particular scenario.
> 
> I wish I had the space for chandeliers! Just simple lamp shades I'm afraid but good to know that OSB is as good as plywood for the first layer.


That's interesting. I've never come across the varying thicknesses recommendation for soundproofing. I've only seen it used for taming resonances in, for example, speaker enclosures. If your space can accommodate two layers of varying thickness drywall, I see virtually no reason two layers of 5/8 cannot be used instead.

Edit: There should not be a huge difference in cost either, in the big picture.


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## doveman

impreza276 said:


> That's interesting. I've never come across the varying thicknesses recommendation for soundproofing. I've only seen it used for taming resonances in, for example, speaker enclosures. If your space can accommodate two layers of varying thickness drywall, I see virtually no reason two layers of 5/8 cannot be used instead.
> 
> Edit: There should not be a huge difference in cost either, in the big picture.


Yeah, the additional cost of green glue itself probably isn't that significant, it's probably more the additional labour costs for applying it and finding someone who knows how to apply it properly so I don't have to stand over them telling them what to do.

I'll have to check whether there's enough space for two layers of 5/8". For most of the room it's not an issue, it's just at the entrance to the room that it could be.


----------



## impreza276

doveman said:


> Yeah, the additional cost of green glue itself probably isn't that significant, it's probably more the additional labour costs for applying it and finding someone who knows how to apply it properly so I don't have to stand over them telling them what to do.
> 
> I'll have to check whether there's enough space for two layers of 5/8". For most of the room it's not an issue, it's just at the entrance to the room that it could be.


Sorry, I was referring just to the difference between using 5/8 +1/2 and using two layers of 5/8. I admit your space and cost concerns on using soundproofing techniques over not using any, are valid.


----------



## swilson72

Ladeback said:


> Not sure how much sound that will stop or slow down, but that is an interesting idea. I take it you have smart joist like I do. If you are trying to keep sound from going up or come from above you will need me mash. That's why I mentioned putting up 5/8" drywall with GG between the joists. You could do one layer then insulation and the drywall like you shown so you can access wires. You get both mass and convince to your wires. Others hopefully will chime in.


Another thought. The room is going to end up having a bit of an industrial look to it anyway - what if I were to paint 4 foot x 18" pieces of drywall black and instead of resting them between the joists, I could screw them to the joists, basically drywalling the ceiling, but without mudding. That way it would be drywalled (sort of), but if I needed to get at cables in the ceiling, it would still be fairly easy to remove the pieces I need. As far as soundproofing goes, how much difference would there be between mudded and un-mudded drywall on the ceiling? There is a good chance I will do a suspended ceiling later in the summer, but right now I have a bunch of extra drywall sheets in a pile in my basement that I want to use or get rid of before I move everything in, so I figured I would see if something like this might work, rather than just wasting the extra drywall.


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## doveman

I want to soundproof my windows but I'm not sure what the best approach would be.

One approach would be wooden plugs with acoustic foam backing, as shown here http://www.soundservice.co.uk/basic_window_soundproofing.html and here https://www.customaudiodesigns.co.uk/how-to-soundproof-windows.htm

I think I'd need to use three plugs to make it manageable in terms of weight and then I could just remove one plug for light or to open a window and leave the other two in place.

The attached photo of my (rather dirty, sorry!) window shows how I think I might need to do that. The window sill isn't level, projects beyond the wall and has a curved front edge, so I think I'd need to fix a batten along it that's flush with the wall, then vertical battens either side of the centre pane which won't get in the way of any of the window handles. I'm not sure if the two outer vertical battens and the one at the top (not shown) would be best inside the reveal or attached to the wall so that the plugs extend past the reveal a bit at the top and to the sides. I guess I'd get a bit extra depth if the plugs sit on the wall rather than sunk in the reveal but it might not be enough to make much difference. From the glass panes to the wall is about 12cm but the frames protrude more either side of the panes, so from the surrounding frame to the wall it's only about 9cm.

Would it be better to use OSB (2 or 3) to make the panels rather than MDF and what thickness? What foam should I use to back the plugs? What purpose does the foam along the top and bottom of the reveal between the window and the battens serve?

The other approach I've considered is magnetic strips and acrylic secondary glazing, like this http://www.soundproofing.org/infopages/magnetseal_windows.htm

That might be less heavy so that I could just use a single panel but it could still be a bit unwieldy, so I might still need to fit battens and create three panels. Obvious advantage is it will allow light in but if it won't provide decent soundproofing that's no good. That's not the only site that suggests secondary glazing can provide decent soundproofing but the others may use purpose built frames and glass which will work better than acrylic.


----------



## mattztt

doveman said:


> I want to soundproof my windows but I'm not sure what the best approach would be.
> 
> One approach would be wooden plugs with acoustic foam backing, as shown here http://www.soundservice.co.uk/basic_window_soundproofing.html and here https://www.customaudiodesigns.co.uk/how-to-soundproof-windows.htm
> 
> I think I'd need to use three plugs to make it manageable in terms of weight and then I could just remove one plug for light or to open a window and leave the other two in place.
> 
> The attached photo of my (rather dirty, sorry!) window shows how I think I might need to do that. The window sill isn't level, projects beyond the wall and has a curved front edge, so I think I'd need to fix a batten along it that's flush with the wall, then vertical battens either side of the centre pane which won't get in the way of any of the window handles. I'm not sure if the two outer vertical battens and the one at the top (not shown) would be best inside the reveal or attached to the wall so that the plugs extend past the reveal a bit at the top and to the sides. I guess I'd get a bit extra depth if the plugs sit on the wall rather than sunk in the reveal but it might not be enough to make much difference. From the glass panes to the wall is about 12cm but the frames protrude more either side of the panes, so from the surrounding frame to the wall it's only about 9cm.
> 
> Would it be better to use OSB (2 or 3) to make the panels rather than MDF and what thickness? What foam should I use to back the plugs? What purpose does the foam along the top and bottom of the reveal between the window and the battens serve?
> 
> The other approach I've considered is magnetic strips and acrylic secondary glazing, like this http://www.soundproofing.org/infopages/magnetseal_windows.htm
> 
> That might be less heavy so that I could just use a single panel but it could still be a bit unwieldy, so I might still need to fit battens and create three panels. Obvious advantage is it will allow light in but if it won't provide decent soundproofing that's no good. That's not the only site that suggests secondary glazing can provide decent soundproofing but the others may use purpose built frames and glass which will work better than acrylic.


All of the principles described in the first post of the thread for soundproofing a room will also apply to a window in isolation so an ideal solution includes the elements of decoupling, mass, damping, and absorption. The ideal solution (that does not involve removing the window) would consist of a plug with mass and damping similar to the wall structure in the room. I'm fortunate to not have neighbors very near to my windows so I haven't yet gotten around to building plugs but the plug design I've envisioned is a sheet of MDF with 1-2 layers of 5/8" drywall and green glue and an acoustically absorbent foam backing. I haven't settled on a plan for sealing the edges but it would likely be rubber or felt for some measure of decoupling.

A lightweight secondary glazing will likely do little to decrease the transmission of low frequencies.


----------



## robr

I've been reading up a lot trying to educate myself on soundproofing. I'm definitely not a DIYer but I like to understand how to correctly do something. I do have one question I haven't been able to find an answer to. I'm building my theater in an attic. 4 sides of the attic are exterior walls, below the attic is a tenant's bedroom and one section of a wall about 6' long has a hallway on the other side that my daughter's bedroom is off of.

Do I need to go nuts on the 4 exterior walls, or can I focus my $$$ on doing the floor, 6' wall section (and door in that section). It's a really strangely shaped house such that if you look at the roof line of the house from the top, the theater area is essentially in an elongated pyramid so that the roof and exterior walls do not share walls or a roof with the other rooms on that same top floor. Just that 6' section. Obviously the goal is to be able to not disturb my daughter or my tenant when they're in bed. I don't care about sound leakage to the outside. Thanks!


----------



## HT Geek

doveman said:


> Would it be better to use OSB (2 or 3) to make the panels rather than MDF and what thickness?



No. Use MDF. It will be easier to work with and accomplish your goal.





> What foam should I use to back the plugs?




Depends on your design and what is readily available. You can use "backer rod"; i.e. dense foam or rubber strips such as those used as door sweeps, or anything else that is of similar characteristics (flexible and blocks air/water/sound).




> What purpose does the foam along the top and bottom of the reveal between the window and the battens serve?



Blocking sound from penetrating the gap.


----------



## HT Geek

robr said:


> I've been reading up a lot trying to educate myself on soundproofing. I'm definitely not a DIYer but I like to understand how to correctly do something. I do have one question I haven't been able to find an answer to. I'm building my theater in an attic. 4 sides of the attic are exterior walls, below the attic is a tenant's bedroom and one section of a wall about 6' long has a hallway on the other side that my daughter's bedroom is off of.
> 
> Do I need to go nuts on the 4 exterior walls, or can I focus my $$$ on doing the floor, 6' wall section (and door in that section). It's a really strangely shaped house such that if you look at the roof line of the house from the top, the theater area is essentially in an elongated pyramid so that the roof and exterior walls do not share walls or a roof with the other rooms on that same top floor. Just that 6' section. Obviously the goal is to be able to not disturb my daughter or my tenant when they're in bed. I don't care about sound leakage to the outside. Thanks!



My advice is focus on the floor for the most part, but don't ignore the remainder - particularly the portion you describe relative to your daughter's room. And I presume you also want to have happy tenants as well.


A good way to approach your problem - presuming you can see all the joists in the attic right now - is to examine how the sides / exterior walls of your attic connect with the remainder of your home. Imagine you were vibrating those joists violently. What are they connected to that would also be vibrated? Follow those paths and you'll learn what will be affected by sound (mostly LFE) traveling along those same paths. Then you can determine which walls to pay more attention to / put more effort into sound proofing.


To some extent, you're going to get carryover of sound from one part of the room to the others so if you don't address the entire room from a sound-proofing standpoint then you may still get some sound transmission where you don't want it. However, those guidelines above should help you pinpoint the areas of greatest weakness, where sound transmission would be most pronounced, so I'd start with them. And if your budget is limited, that would be the route to begin your planning.


Another thought.... certain kinds of music product a lot of low, low frequencies. For instance, my teenage son likes to listen to rap loudly in my dedicated HT room. When his music is pushing my dual 18" subs down in the 18-30hz range for extended periods of time and loudly, you can hear it throughout much of my house in spite of my considerable efforts to have contained sound in the room. OTOH, I watched The Dark Knight with a friend a few weeks ago and my wife couldn't hear anything in our kitchen. The difference is the movie has occasional scenes that are loud and boomy, whereas the songs I mentioned are a constant drone for several minutes. My theater is on the 2nd floor.YMMV, but your usage will make a big difference in how it impacts others in your home.


----------



## robr

Thanks very much HTGeek, it is a finished space but I think understanding the roofline will help a contractor answer some of those questions. I definitely don't have unlimited budget so was hoping I could focus on the floor and that one wall, otherwise I don't think I could get the costs past the wife. Sounds like it may be possible but I will have a pro take a look. Room would be for TV/movies primarily and I do have a drum set I'll put in there, but I don't play after 8pm and my tenants have had to live with it coming through the walls for 12 years. I'm not even going to worry about that . I do have a 15" B&W ASW 5000 sub but I don't use that at night either. It would be nice to be able to, but LFE is definitely tough.

The yellow area is the theater, the reds are two rooms where you can see the roof line for the most part is disconnected from the theater with just a small area of wall sharing a hall/theater wall.
Red box on the left is daughter's room, on the right a tenant bedroom, in between are two stairwells coming up to the third floor.


----------



## HT Geek

robr said:


> Thanks very much AVGeek, it is a finished space but I think understanding the roofline will help a contractor answer some of those questions. I definitely don't have unlimited budget so was hoping I could focus on the floor and that one wall, otherwise I don't think I could get the costs past the wife. Sounds like it may be possible but I will have a pro take a look. Room would be for TV/movies primarily and I do have a drum set I'll put in there, but I don't play after 8pm and my tenants have had to live with it coming through the walls for 12 years. I'm not even going to worry about that . I do have a 15" B&W ASW 5000 sub but I don't use that at night either. It would be nice to be able to, but LFE is definitely tough.
> 
> The yellow area is the theater, the reds are two rooms where you can see the roof line for the most part is disconnected from the theater with just a small area of wall sharing a hall/theater wall.


Understood. So, I suspect the issue you're going to run into is depending on when your home was constructed and what techniques were used to build your roof. 

Without viewing the insdie of the attic in detail, I can give you a rough idea of what to look for. You need to trace the joists, rafters, and trusses and see how they interconnect. There's normally going to be one or more large beams that they will connect to and which will run the length or width of your home. This is how sound ends up traveling from one area to another. Basically, you want to get an idea of where your weak areas are going to be from the standpoint of what touches what. Regardless, it is very, very likely you're going to have to go to what most people would consider an extreme to do a good job of sound isolation, if you want that.

Isolating the floor is going to be the best thing you can do, regardless. I can tell you that from first-hand experience building a 2nd floor theater. If you want good floor isolation, you are going to have to find a way to truly de-couple the HT room floor in the attic from the joists on the floor of the attic. For example, RIM flooring. No matter how you do it, you will need a robust solution. Multiple layers of rubber mat, OSB, and hockey pucks won't cut it. They will help, but they won't do the job effectively against something like your drums. So, RIM would be a good route, combined with some other techniques. Another option would be springs with a 1-1/2" or thicker sub-floor on top of them. If you want good sound isolation, you will need something a little crazy like that.

On the lesser end of the scale, "good enough" sound proofing.... lower cost.... consider U-boats on the existing floor joists in the attic. Build yourself a layered system of sub-flooring on top of that using multiple layers of 3/4" plywood and rubber mat. You'll reduce the "touch points" to the joists underneath, add mass, and provide some damping. You will still hear the drums and loud LFE outside the room, but it will be muffled somewhat.

Your drums are going to require higher freq combating measures as well, but that's more easily dealt with versus LFE. Most cymbals in particular get up to around 5-6 Hz or so IIRC.


----------



## LDBaha

Hey guys. I currently have my Mini HT room in a bedroom on the second floor but I got complains from the neighbors.

So I decided to move it to the garage. 
I want to split my garage in 2: Storage + man cave. I want to do the whole *'room within a room' *thing. Something very simple just 4 walls. 

I've been reading about doing a double wall or a staggered stud wall but I was wondering if I needed to do that. 
My garage is built from concrete block walls and ceiling has wood joists with an attic space. Ceiling is finished. Floor is a concrete slab

Because I have concrete block walls do I need to do a staggered stud wall or a double wall? What would be best?
Please see quick plan I made below

I don't care if sound can be heard in my home. I want to block bass from bothering neighbors.

Any advice would be appreciated

Edit: plan is to do decoupled walls + double drywall + green glue.


----------



## HT Geek

LDBaha said:


> I've been reading about doing a double wall or a staggered stud wall but I was wondering if I needed to do that.
> My garage is built from concrete block walls and ceiling has wood joists with an attic space. Ceiling is finished. Floor is a concrete slab
> 
> Because I have concrete block walls do I need to do a staggered stud wall or a double wall? What would be best?


Generally speaking, with a concrete block wall, no you don't need to do staggered stud or double stud, provided there is not an existing stud wall right now. Just position a new stud wall with a gap between it and the concrete block (e.g. 1" gap). I would recommend you still use something like IB-3 brackets to secure it to the concrete block, so it remains attached to your home's foundation while still being de-coupled.

What is behind the concrete block? Earth? Is your garage underground?


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## LDBaha

HT Geek said:


> Generally speaking, with a concrete block wall, no you don't need to do staggered stud or double stud, provided there is not an existing stud wall right now. Just position a new stud wall with a gap between it and the concrete block (e.g. 1" gap). I would recommend you still use something like IB-3 brackets to secure it to the concrete block, so it remains attached to your home's foundation while still being de-coupled.
> 
> What is behind the concrete block? Earth? Is your garage underground?


Thanks for the advice!
I had planned on leaving a 4" gap between the concrete and the stud wall. I could do double stud wall because I have the space for it but if it's not necessary or wouldn't make that much of a difference then I'd rather save the money and work less!

However if it makes a difference I would rather do staggered stud walls. They don't seem too hard

The garage is a normal garage. Here in Florida all buildings located on the ground floor need to be built with concrete foundation and concrete walls. There is no drywall inside just painted blocks. 
Directly next to the garage is an open porch and a storage room. Neighbors to the left side of my house are about 17' away and the neighbors to the right are closer at 10' 

My main concern is the blocking the bass from the subs. I have 2x HSU VTF-3 MK5 HP that sound _awesome_ and I was told by my neighbors they could hear it pretty loud. Of course I have no sound proofing whatsoever in the room and the room is directly next to their master bedroom 10' away. It's also on a second floor where the walls are made of wood. 

See photos!

The only part I haven't figured out is how to attach the walls to the garage ceiling while having them being decoupled. I would rather not go through the hassle of building another ceiling


----------



## doveman

mattztt said:


> All of the principles described in the first post of the thread for soundproofing a room will also apply to a window in isolation so an ideal solution includes the elements of decoupling, mass, damping, and absorption. The ideal solution (that does not involve removing the window) would consist of a plug with mass and damping similar to the wall structure in the room. I'm fortunate to not have neighbors very near to my windows so I haven't yet gotten around to building plugs but the plug design I've envisioned is a sheet of MDF with 1-2 layers of 5/8" drywall and green glue and an acoustically absorbent foam backing. I haven't settled on a plan for sealing the edges but it would likely be rubber or felt for some measure of decoupling.
> 
> A lightweight secondary glazing will likely do little to decrease the transmission of low frequencies.


That's an interesting idea to use drywall layers on the MDF as well as foam. I feel it might be overkill for me, as most places suggest that MDF+foam is sufficient but if it turns out not to be I'll try your idea.

I did think acrylic glazing would be unlikely to be very effective, at anything other than mid->high frequencies at least but I wasn't sure after seeing it suggested in a few places.


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## doveman

HT Geek said:


> No. Use MDF. It will be easier to work with and accomplish your goal.


OK, thanks. I mainly asked as I need to get some OSB 3 to patch up my floorboards temporarily so I thought I might be able to use the same for the plugs but I'll stick with MDF for that.



> Depends on your design and what is readily available. You can use "backer rod"; i.e. dense foam or rubber strips such as those used as door sweeps, or anything else that is of similar characteristics (flexible and blocks air/water/sound).


I guess you're talking about the strips around the perimeter. I meant the foam that I'd stick to the window facing side of the MDF plugs. I guess something like these wouldn't be dense enough? https://www.amazon.co.uk/s?k=24+Pack+Acoustic+Panels+Studio+Foam+Wedges+1"+X+12"+X+12"

How about one of these 25mm or 32mm thick non-flammable foams? They're quite expensive though. http://www.soundservice.co.uk/prices_live.php#nonflammablefoam

I've seen advice to use non-flammable as it could get quite hot in the space and my windows are more or less south-facing, so I get sunlight all day and it gets hottest around noon onwards, so I need to be careful. Another suggestion was to put some tinting film on the windows but it would be nice to have a clear view when the plugs are removed.



> Blocking sound from penetrating the gap.


Which gap? I presume when fixing the battens I'd seal along where they meet the wall so there won't be any gaps there? As for the gap between the window and the batten, that still leaves a large empty space between the window and the foam attached to the MDF, as shown here https://www.customaudiodesigns.co.uk/how-to-soundproof-windows.htm so is it just because the MDF is touching the battens that we need foam between the battens and the windows to prevent sound reaching the battens and then transmitting through them and the MDF into the room?


----------



## HT Geek

doveman said:


> I guess you're talking about the strips around the perimeter. I meant the foam that I'd stick to the window facing side of the MDF plugs. I guess something like these wouldn't be dense enough? https://www.amazon.co.uk/s?k=24+Pack+Acoustic+Panels+Studio+Foam+Wedges+1"+X+12"+X+12"
> 
> How about one of these 25mm or 32mm thick non-flammable foams? They're quite expensive though. http://www.soundservice.co.uk/prices_live.php#nonflammablefoam
> 
> I've seen advice to use non-flammable as it could get quite hot in the space and my windows are more or less south-facing, so I get sunlight all day and it gets hottest around noon onwards, so I need to be careful. Another suggestion was to put some tinting film on the windows but it would be nice to have a clear view when the plugs are removed.
> 
> 
> 
> Which gap? I presume when fixing the battens I'd seal along where they meet the wall so there won't be any gaps there? As for the gap between the window and the batten, that still leaves a large empty space between the window and the foam attached to the MDF, as shown here https://www.customaudiodesigns.co.uk/how-to-soundproof-windows.htm so is it just because the MDF is touching the battens that we need foam between the battens and the windows to prevent sound reaching the battens and then transmitting through them and the MDF into the room?


Right. I was thinking you were asking about perimeter gaps.

If it's foam facing the window, do you envision that foam touching the window? What would you be trying to accomplish with this foam?


----------



## HT Geek

LDBaha said:


> Thanks for the advice!
> I had planned on leaving a 4" gap between the concrete and the stud wall. I could do double stud wall because I have the space for it but if it's not necessary or wouldn't make that much of a difference then I'd rather save the money and work less!


Well, there are lots of options. If you have the room, you could have a 4" gap as you suggest and plug the space between the block wall and wood studs with insulation. If you do, I'd suggest something along the lines of kraft backed fiberglass or backed mineral wool / OC 703 / OC 704. Something like that. 



> However if it makes a difference I would rather do staggered stud walls. They don't seem too hard


In your case it won't matter. Staggered stud and double stud walls purpose are to provide an air gap from a neighboring wall. In your case, there's no pre-existing wood stud wall. You effectively creating a double stud wall by leaving a gap between your concrete block wall and a new wood stud wall that you'll build.

if you already had a wood stud wall directly up against the concrete block wall, that's when you'd want to look at staggered stud vs. double stud. But again in your case that is overkill.



> The garage is a normal garage. Here in Florida all buildings located on the ground floor need to be built with concrete foundation and concrete walls. There is no drywall inside just painted blocks.
> Directly next to the garage is an open porch and a storage room. Neighbors to the left side of my house are about 17' away and the neighbors to the right are closer at 10'
> 
> My main concern is the blocking the bass from the subs. I have 2x HSU VTF-3 MK5 HP that sound _awesome_ and I was told by my neighbors they could hear it pretty loud. Of course I have no sound proofing whatsoever in the room and the room is directly next to their master bedroom 10' away. It's also on a second floor where the walls are made of wood.
> 
> See photos!


Thanks. It's super-helpful when photos are included with questions, when feasible.

Is your garage detached from your home? I can't tell from the photos.



> The only part I haven't figured out is how to attach the walls to the garage ceiling while having them being decoupled. I would rather not go through the hassle of building another ceiling


You really need to address the ceiling as well or your hard work on the walls is going to be wasted.

How tall is the ceiling in the garage right now? What are your rough dimensions at the moment (length x width x height)?

If you want a true "room within a room," it will need a ceiling.  Let's see how much space you have to work with and I can help you do the match on beam spans, loads, etc. if you like.


----------



## doveman

HT Geek said:


> Right. I was thinking you were asking about perimeter gaps.
> 
> If it's foam facing the window, do you envision that foam touching the window? What would you be trying to accomplish with this foam?


No I wouldn't have it touching the window. The stuff I've read so far suggests that it's better to leave a gap and that the purpose of the foam is to absorb/deflect some of the noise before it reaches the MDF. Without the foam I would imagine some noise from outside would travel through the MDF into the room. I'm not sure if the foam would have any effect in the other direction, i.e. absorbing noise generated in the room to prevent it reaching the window or if I'd need foam on the room-side of the MDF if I needed to do that but it may be unnecessary anyway and can always be added later.


----------



## LDBaha

HT Geek said:


> Thanks. It's super-helpful when photos are included with questions, when feasible.
> 
> Is your garage detached from your home? I can't tell from the photos.


That would be super helpful! I really appreciate it.

I wouldn't consider the garage being 'detached' but it's not directly against our 'living spaces' it's next to the open porch that has a storage room. The open porch and the basement share the same ceiling/attic but it's not connected to the attic from the house. So I will need to figure out the AC with either a Mini-Split or a Double-hose portable AC. There is a soffit on the garage so maybe I can make some sort of fan with a backing box to bring fresh air from outside in. *I attached a photo*. 



> Well, there are lots of options. If you have the room, you could have a 4" gap as you suggest and plug the space between the block wall and wood studs with insulation. If you do, I'd suggest something along the lines of kraft backed fiberglass or backed mineral wool / OC 703 / OC 704. Something like that.


I have about 20' long and I was happy in a 10x10 room so I have a lot of space to use for buffering. IF that helps of course. 




> You really need to address the ceiling as well or your hard work on the walls is going to be wasted.


I really wanted to avoid building the ceiling but it's due to being inexperienced with that but if it's not that complex I will give it a go! I thought I didn't need a ceiling because the garage has an attic and then there's the house's ceiling on top of that. But I don't want to do all of the walls and not get the results I wanted. 

I don't know if what I want is possible but I will give it my best. My idea is that the theater would be really hard to hear unless you're actually very very close to my garage. 



> How tall is the ceiling in the garage right now? What are your rough dimensions at the moment (length x width x height)?


Measurements:
The ceiling right now is at 116"
The garage is 20'x20'6". I will split it at around 12'x20' the rest will be used as storage (wife request). 
After building the walls with the air gap I think it should come down to around 10x18' or 11x19' not sure 

In Short: 20 x 12 x 9.6'height

I'm guessing we could build a ceiling around 8'


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## HT Geek

LDBaha said:


> That would be super helpful! I really appreciate it.
> 
> I wouldn't consider the garage being 'detached' but it's not directly against our 'living spaces' it's next to the open porch that has a storage room. The open porch and the basement share the same ceiling/attic but it's not connected to the attic from the house. So I will need to figure out the AC with either a Mini-Split or a Double-hose portable AC. There is a soffit on the garage so maybe I can make some sort of fan with a backing box to bring fresh air from outside in. *I attached a photo*.


Interesting. I didn't realize any homes in FL had basements!

Why not use your basement for your HT room?



> I have about 20' long and I was happy in a 10x10 room so I have a lot of space to use for buffering. IF that helps of course.
> 
> I really wanted to avoid building the ceiling but it's due to being inexperienced with that but if it's not that complex I will give it a go! I thought I didn't need a ceiling because the garage has an attic and then there's the house's ceiling on top of that. But I don't want to do all of the walls and not get the results I wanted.
> 
> I don't know if what I want is possible but I will give it my best. My idea is that the theater would be really hard to hear unless you're actually very very close to my garage.
> 
> Measurements:
> The ceiling right now is at 116"
> The garage is 20'x20'6". I will split it at around 12'x20' the rest will be used as storage (wife request).
> After building the walls with the air gap I think it should come down to around 10x18' or 11x19' not sure
> 
> In Short: 20 x 12 x 9.6'height
> 
> I'm guessing we could build a ceiling around 8'


Ok. I believe you previously mentioned your primary concern with noise is theater noise escaping out to where your neighbors hear it and complain. Based on that, and given the fact there is nothing above the room except an attic, I'm surmising you're going to have sound escaping from there that will bother your neighbors if you don't treat the ceiling. That's also based on your previous comment that the neighbors complain now. Therefore, clearly the way your home was built, your neighbors, and your HT room habits aren't all living well together atm. 

Based on all that, I'd suggest you treat the ceiling. If you're building stud walls to begin with, it's actually not a huge deal. But it does obviously require more work, time, and money than not doing it. And in your case, an alternative would be to reinforce your existing ceiling. Since you're not concerned with sound/vibrations above your garage to inside the rest of your home, you could simply add 1 or 2 additional layers of drywall to the ceiling (preferably with Green Glue in between them).

Depending on how your ceiling joists in the garage were built, it may not be wise to add more than 1 more layer of drywall to the existing ceiling. 

Just estimating... with a 12' span, you should be able to use 2x6 joists if you built a "new" ceiling using the room-within-a-room concept, and suspend it on top of your to-be-built wood stud walls. In that case, you'd still have roughly 9' tall ceilings. Even if you went with 2x8's or 2x10's, you're still well above 8'.

Then again, the soffit might change all that. The devil is in the details. 

Bottom line is I'm concerned an untreated ceiling will result in continuing neighbor complaints. IMHO, that possibility is not worth the risk, because if that does happen then trying to retrofit your new room is going to be a big pain. ;(


----------



## HT Geek

doveman said:


> No I wouldn't have it touching the window.


Ok.



> The stuff I've read so far suggests that it's better to leave a gap and that the purpose of the foam is to absorb/deflect some of the noise before it reaches the MDF.


Wow. Ok. That's a new one for me (i.e. never heard that before).



> Without the foam I would imagine some noise from outside would travel through the MDF into the room. I'm not sure if the foam would have any effect in the other direction, i.e. absorbing noise generated in the room to prevent it reaching the window or if I'd need foam on the room-side of the MDF if I needed to do that but it may be unnecessary anyway and can always be added later.


Normally, foam and gaskets, etc. are used to treat gaps around the window plug. And well designed window plugs make use of at least 2 sections. You end up with a sort of arrangement similar to Matryoshka dolls, in a way (or maybe that's just my odd way of looking at it; LoL). Anyhow, point is you have an inner and outer layer, starting from the room side.

I suppose if you had a particular external issue you were concerned about, that could play into a solution. Some people might have environmental noise concerns that necessitate additional layers. Either way, mass (MDF) and plugging any gaps between window plug layers are going to be your best bet for the vast majority of circumstances.


----------



## LDBaha

HT Geek said:


> Interesting. I didn't realize any homes in FL had basements!
> 
> Why not use your basement for your HT room?


Haha my phone is crazy and autocorrected whatever I was typing to basement. I wish I had a basement! I meant to say the open porch and garage share the same ceiling and it's not connected to the house.





> Ok. I believe you previously mentioned your primary concern with noise is theater noise escaping out to where your neighbors hear it and complain. Based on that, and given the fact there is nothing above the room except an attic, I'm surmising you're going to have sound escaping from there that will bother your neighbors if you don't treat the ceiling. That's also based on your previous comment that the neighbors complain now. Therefore, clearly the way your home was built, your neighbors, and your HT room habits aren't all living well together atm.


That is correct. My neighbors do not like my subwoofer habits. I do need to treat ceiling either by building a new one or beefing up the one from the garage. 

If I don't build a ceiling I would try to add another layer of drywall and maybe get in the attic and add more drywall on top of the joists? more mass could help. 



> Depending on how your ceiling joists in the garage were built, it may not be wise to add more than 1 more layer of drywall to the existing ceiling.


I could take a picture of that. I'm almost sure it could handle the weight 



> Just estimating... with a 12' span, you should be able to use 2x6 joists if you built a "new" ceiling using the room-within-a-room concept, and suspend it on top of your to-be-built wood stud walls. In that case, you'd still have roughly 9' tall ceilings. Even if you went with 2x8's or 2x10's, you're still well above 8'.


I see. 8' tall for me would be more than enough. Do you have any video/material/photos on how to build the ceiling? 

When you say suspend it on top. Do you mean it would rest on top of the 4 walls or is there another way? The walls would be load bearing thencorrect? Unless somehow float the new ceiling from the current structure. How/Where would I use the IB-3 brackets in this case?




> Then again, the soffit might change all that. The devil is in the details.


What do you mean?



> Bottom line is I'm concerned an untreated ceiling will result in continuing neighbor complaints. IMHO, that possibility is not worth the risk, because if that does happen then trying to retrofit your new room is going to be a big pain. ;(


This is my concern as well. At the minimum I would add drywall to the current ceiling
However since I'm building the whole thing I might just as well build the freaking ceiling

Thanks for all the help!


----------



## HT Geek

LDBaha said:


> If I don't build a ceiling I would try to add another layer of drywall and maybe get in the attic and add more drywall on top of the joists? more mass could help.
> 
> I could take a picture of that. I'm almost sure it could handle the weight
> 
> I see. 8' tall for me would be more than enough. Do you have any video/material/photos on how to build the ceiling?
> 
> When you say suspend it on top. Do you mean it would rest on top of the 4 walls or is there another way? The walls would be load bearing thencorrect? Unless somehow float the new ceiling from the current structure. How/Where would I use the IB-3 brackets in this case?


 You're better off adding additional drywall on the inside of the room, and not in the attic. On the attic side, consider adding extra insulation; though I wouldn't rush to do that. It could be done later if deemed necessary/helpful. If you do, I suggest using rolls or batts of pink fluffy (fiberglass) as it's cheap and effective.

*Existing Garage Ceiling Joists*

The concern I have with the joists in the attic (floor joists if you're in the attic / ceiling joists if you're in the garage) is because garages have less stringent load bearing requirements when there is no living space above them. Therefore, it's common for non-custom built homes to be built to the minimum required spec with regards to the garage ceiling.

It may be a non-issue, but you don't know until you investigate how it's built. It may be difficult to tell from photos, depending on what your attic looks like (e.g. existing insulation, stuff you're storing in there, etc.). The gist of it is you want to ascertain how the joists are laid out and how they are supported. For example, given the size of your garage, you're going to have either trusses or joists and beams. If you have joists and beams, they could be wood only or a combination of wood and steel. That's all presuming you don't have any support columns in the middle of your garage. Anyway, I hope you get the idea there are a variety of ways to build it, but in this case your situation is the only one that matters!

If you build walls, you might as well build a ceiling on top of it. Problem solved for relatively little effort. Since your dedicated room will occupy only a portion of your garage space, you could build it in such a way that only the HT room has the lowered ceiling. BTW, you should plan on a double stud wall between the HT room-within-a-room and the other finished area of what is now your garage. Again, it's one of those things where you might as well do it that way as it's little extra work and materials while you're doing everything else.

Your inner ceiling joists will just rest on top of the header for your inner walls. You'll need specially designed metal framing parts to secure them (available at any building supply store). This does not make the walls load bearing. More on that in a moment.


*Inner Wall Framing*

So, let's say you build a ceiling for a true room-within-a-room. Add 2 layers of drywall with Green Glue between them on all 4 walls and the ceiling and you'll be in good shape. Build your walls 4" off the concrete block outer walls as we discussed earlier and apply some OC 703 insulation or RockWool mineral wool insulation in that space. Use 3-3.5" thick insulation affixed to the concrete walls, leaving a small air gap of 1/2" to 1" between your wood studs and the concrete block walls.

The challenge I see next is how to secure your inner walls and ceiling to the structure of the garage. Do you want to do this? This is an area of mixed opinions. Personally, I favor the approach of attaching the inner room to the outer/structural room, using limited points of contact. Why? It binds the inner room to the remainder of your home. It is possible to build an inner room without doing that. Binding them to the remainder of the house ensures the structural rigidity of the inner room. Size of the room can also make a difference. With smaller and/or lower height rooms it tends to be less important. But again, this is my opinion to suggest it. You'll find equal numbers of people who say you do or don't, should or shouldn't do it. There is not a "wrong" way unless you live somewhere where your building codes require it (or if you suck at building plumb walls, LoL). 

A load bearing wall is one that supports something above it other than the ceiling, but including say, a roof or 2nd floor living space. Your inner room will not be load bearing if it's built as a room-within-a-room. Thus, it can be completely floating (not connected to anything except the floor of course).

If you choose to anchor your inner room walls and/or ceiling to the structural walls/ceiling, your best bet is something like the aforementioned IB-3 clips (they are L-shaped) and are designed for this purpose. Typically, you'd place them every 4-6 feet (horizontally) along your walls, as you go around the room, with one clip about every 4 feet vertically. Example: in a 10x10 foot room you'd use about 4-6 clips per wall, depending on your choice. If you do this, it will lock your inner walls to the outer/structural walls. While not ideal from a sound proofing perspective, the impact is minimal and in exchange your walls will never warp unless your entire house shifts (at which point you will have a whole bunch of issues). Another method is to only secure your wall corners to the structural walls. It takes a minimum of 4 clips per corner, or 16 minimum for a square room.


*Floating Floor*
You should consider floating the floor. Meaning you build an independent sub-floor on top of the concrete floor. The inner room walls get built on top of this floating floor. It helps isolate sound and vibration from the remainder of the structure. A common example would be a sandwich of 1/2" or 3/4" OSB or plywood with rubber mat, such as Concrete -> OSB -> Rubber -> OSB. It adds about 1-1/2" - 2-1/2" to the floor height, depending on implementation. Now, in your case this might not be practical since you're going to have an adjacent interior space. It would likely mean creating a step-up into the room. If you have to use the concrete floor as your HT room floor you'll be fine. Since you're on the ground floor it's not as big of a deal, though it's preferable if feasible.

And finally, going back to IB-3 clips and potentially attaching your inner room walls with them to the concrete block / outer walls, if you choose to do this AND have a 4" gap between walls, you will need longer clips (i.e. IB-3 extended) or come up with a jury-rig method (e.g. block of wood attached to outside of inner wall stud to make it closer to structural wall). Something to keep in mind when you are planning your building materials for the project.


----------



## doveman

HT Geek said:


> Wow. Ok. That's a new one for me (i.e. never heard that before).


I'm surprised, as every result that comes up when I search for window plugs seems to suggest much the same idea. Wooden board with soundproofing mat and/or foam attached, with a gap left in the space. It seems to be the same principle as fitting drywall over walls with pink fluffy in the gap but not totally filling it, so it makes sense.

http://www.soundproofing.org/infopages/windowplug.htm
https://www.customaudiodesigns.co.uk/how-to-soundproof-windows.htm
https://homerecordingpro.com/how-to-soundproof-a-window/
https://www.soundaway.com/window-plug-s/103.htm
https://aquietrefuge.com/soundproof-window/

For smaller windows it's even suggested to just use foam/mat cut larger than the reveal so that it's a snug fit when pushed in and the wooden backer board is only necessary for windows over 3' by 2' (which most of mine are but I have one small window I might just stuff foam in). Where battens are fitted in the reveal, the backer board just sits on top of them so I guess it's only the foam squeezed between the battens that holds the plug in place.

So I guess if I had the plugs recessed and contained within the reveal, as in my photo/drawing, I might not need battens at the far left and right or at the top as the foam would squash up against the wall but I'd need battens at the bottom because of the uneven sill and the two in the middle so that I can fit three separate plugs. If I made the plugs to sit above the reveal, which would increase the available space between them and the window, then I'd need battens at the far left and right and above the reveal as well to provide something for the foam to squash against, although I guess the backer board could be bigger than the foam so the board rests on the wall and foam still squashes inside the reveal to hold it all in place.

As most of the articles are from the US they link to US suppliers so I haven't found many UK sources of possible foams I could use. As the space will be about 4 to 4.5", ideally I'd want around 2" of foam but 1" might be enough. 

There's this 1mx0.6m 34mm thick sheet for £23.50. It has 100kg/m3 density and weighs 5kg/m2 and is class 0 fire-resistant.
https://www.customaudiodirect.co.uk/soundproofing/foam-barrier-composite-soundproofing-mat

This is a 1.2mx0.9m 32mm product for £55.70 with the same weight but lower density of 70-90kg/m3, so that's not very good value for money.
http://www.soundservice.co.uk/foam-laminate-FRFFB6.html

The only thicker product I've found so far is this 50mm/2" stuff in a 2mx1m sheet for £90. It's probably not worth paying nearly 4 times as much just to get something 50mm rather than 34mm thick though. 
https://www.acefoam.co.uk/store/products/1559-2/

I think they all have an option of foil-facing on the noise-facing side (for extra cost of course) but that's more for protecting it from oil, etc in engine rooms and for a window it might be better to fit a thin layer of something white to make it look nicer from outside.

I'll probably need to get someone in to make and fit the battens and board, as I haven't got the tools, time or skill really but I'll need to get the foam first so it's here ready to be stuck to the boards.


----------



## LDBaha

HT Geek said:


> You're better off adding additional drywall on the inside of the room, and not in the attic. On the attic side, consider adding extra insulation; though I wouldn't rush to do that. It could be done later if deemed necessary/helpful. If you do, I suggest using rolls or batts of pink fluffy (fiberglass) as it's cheap and effective.


Wow! Thank you so much for all the help. I really appreciate it and wish your kindness to comeback to you as good fortune!

After reading everything you recommended this is my plan.


Build 4 walls 4" (or 3") away from the concrete walls.
Wall that divides garage in 2 should be double stud.
Joist (2x6 or 2x4?) for the ceiling would be mounted with Joist hangers to the top plate or Joist connector brackets Like these? Would I need a double top plate?
Walls would be secured using IB-3 clips to the concrete (somehow). I'd rather do this as I feel it'll make things easier.
Double Drywall + Green glue
Carpet

And that's "just" it. I just have to figure out the AC and Lighting now. Otherwise I will use the room to kill myself during Florida's Summer 

I will consider the floating floor btw


----------



## HT Geek

LDBaha said:


> Wow! Thank you so much for all the help. I really appreciate it and wish your kindness to comeback to you as good fortune!


Very kind wishes of you. Thank you. 



> After reading everything you recommended this is my plan.
> 
> 
> Build 4 walls 4" (or 3") away from the concrete walls.


If you've got the space, I'd suggest a 4" gap, which would be 3-3.5" thick insulation (depending on type) plus 0.5-1" air gap between wood studs and insulation. The insulation should be attached to the concrete block wall.



> Wall that divides garage in 2 should be double stud.
> Joist (2x6 or 2x4?) for the ceiling would be mounted with Joist hangers to the top plate or Joist connector brackets Like these? Would I need a double top plate?


Actually, we didn't talk specifics on joist size yet. The size joists you'll need will depend on the distance traversed, material they're made of, and what will hang from them. In most cases, you're looking at 12' maximum span with joists every 24". That's maximum. You can improve that be either a) reduce width of space; b) space the joists closer together (such as every 18" or 12"); or 3) use taller joists (e.g. move up to 2x8's).




> Walls would be secured using IB-3 clips to the concrete (somehow). I'd rather do this as I feel it'll make things easier.
> Double Drywall + Green glue
> Carpet
> 
> And that's "just" it. I just have to figure out the AC and Lighting now. Otherwise I will use the room to kill myself during Florida's Summer
> 
> I will consider the floating floor btw


Otherwise, sounds good for a basic plan. As you said, you'll want to factor in HVAC and how it will enter the room, etc. Don't forget you can use the attic to help route some of those things. Just try to minimize the holes penetrating the inner room. Some are necessary (e.g. air conditioning ducts).

Next you'll have to factor in things such as how you're going to get A/C power into the room, where your equipment will be located, etc.

There is a clip called the RSIC-1-EXT04 that might work for connecting your walls to the concrete block. Just screw in one end to a wood stud and screw the other end into the concrete block wall. 

Here is a diagram:











You will need to think through how you can make the angle work, but with a bit of experimentation before attachment you'll get the hang of it. You don't need very many. BTW, it's important to be certain the stud is level when you do this. You don't want to pull the studs out of level. This can happen when - for example - your outer wall is not level (rare, but it can happen). If that were the case, I would find an alternative location to make a connection as I would not want to pull my inner room out of plumb/level.


EDIT: One more tip for you since you're still at the 10,000 Foot level of planning..... Don't build a perfectly square room. It's not good for acoustics. Rectangular is fine. If you search around this forum, you can probably find more detailed info on the numeric combinations to try and avoid. My brain is rusty on that part atm.


----------



## HT Geek

doveman said:


> I'm surprised, as every result that comes up when I search for window plugs seems to suggest much the same idea. Wooden board with soundproofing mat and/or foam attached, with a gap left in the space. It seems to be the same principle as fitting drywall over walls with pink fluffy in the gap but not totally filling it, so it makes sense.


It's possible I'm just not following your thought process and we're thinking of the same solution. Or it's possible this is a new-ish technique I hadn't read about yet. I'll look over the links you posted. Thanks for that.


----------



## LDBaha

HT Geek said:


> You will need to think through how you can make the angle work, but with a bit of experimentation before attachment you'll get the hang of it. You don't need very many. BTW, it's important to be certain the stud is level when you do this. You don't want to pull the studs out of level. This can happen when - for example - your outer wall is not level (rare, but it can happen). If that were the case, I would find an alternative location to make a connection as I would not want to pull my inner room out of plumb/level.
> 
> 
> EDIT: One more tip for you since you're still at the 10,000 Foot level of planning..... Don't build a perfectly square room. It's not good for acoustics. Rectangular is fine. If you search around this forum, you can probably find more detailed info on the numeric combinations to try and avoid. My brain is rusty on that part atm.


I need to plan AC. I have no access to my main AC and the split + maybe a silent bathroom exhaust and intake. I'll make a build thread when I'm ready to begin

Thanks for all the help. I think I read somewhere about a 'great acoustic ratio' and that's how a long time ago I came up with the 12x18 theater size. I might not hit it exactly but it'll be close.

I don't mind if the theater is simple and there's just a big ass screen and a nice chair. I just don't want people nagging me when I'm enjoying a nice quiet scene from Saving Private Ryan 

Here's a photo of my current mini-theater https://i.imgur.com/by02W7J.jpg


----------



## HT Geek

LDBaha said:


> I need to plan AC. I have no access to my main AC and the split + maybe a silent bathroom exhaust and intake. I'll make a build thread when I'm ready to begin
> 
> Thanks for all the help. I think I read somewhere about a 'great acoustic ratio' and that's how a long time ago I came up with the 12x18 theater size. I might not hit it exactly but it'll be close.


You bet. Glad to be of some help. 

FWIW, you will need some kind of HVAC system in there. Not 100% sure what you are contemplating, but an exhaust fan alone is not gonna work in Florida. 

IF you could split off your main HVAC, you might be able to do a split and create a zoned system. However, I would caution against that because you are going to be adding square footage to your home, and HVAC units are sized to the home when it's built. You don't want to over-stress your system. A mini-split may be your best bet for that space. You can even get a zoned mini-split and use it to control climate in the other space you're planning (in the garage).

It's almost undoubtedly going to be cheaper to install a mini-split system where you need it versus upgrade the whole-house HVAC and run flex pipe into the theater and adjacent room.

Some things for you to mull over. 




> I don't mind if the theater is simple and there's just a big ass screen and a nice chair. I just don't want people nagging me when I'm enjoying a nice quiet scene from Saving Private Ryan


I hear ya. 



> Here's a photo of my current mini-theater https://i.imgur.com/by02W7J.jpg


Not bad. Looks cozy!


----------



## LDBaha

HT Geek said:


> You bet. Glad to be of some help.
> 
> FWIW, you will need some kind of HVAC system in there. Not 100% sure what you are contemplating, but an exhaust fan alone is not gonna work in Florida.


No no, I meant the Mini-Split + exhaust/intake to circulate fresh air. I can't tap into my main HVAC. I wish I could but I can't. I would have to do something crazy and expensive.

I've been in rooms here in FL with just a mini-split and it works if it's 1 or 2 people but more than that without air circulation it can get uncomfortable. Imagine how it would be in a room within a room where everything is air tight!

I will try to get a Dual zone mini split but I need to get HOA approval for the outdoor unit -- oh my God HOAs never again, never again.
I think for the size of the room a mini-split should be sufficient providing I find a way to bring fresh air in. 



> Not bad. Looks cozy!


Thanks! It sounds so good that neighbors are complaining


----------



## HT Geek

LDBaha said:


> No no, I meant the Mini-Split + exhaust/intake to circulate fresh air. I can't tap into my main HVAC. I wish I could but I can't. I would have to do something crazy and expensive.
> 
> I've been in rooms here in FL with just a mini-split and it works if it's 1 or 2 people but more than that without air circulation it can get uncomfortable. Imagine how it would be in a room within a room where everything is air tight!
> 
> I will try to get a Dual zone mini split but I need to get HOA approval for the outdoor unit -- oh my God HOAs never again, never again.
> I think for the size of the room a mini-split should be sufficient providing I find a way to bring fresh air in.
> 
> 
> Thanks! It sounds so good that neighbors are complaining



Don't want to badger you too much with responses, but FYI... my belief is you can get decent A/C in the HT room. Get a ducted unit with beefy cooling BTU power and you should be GTG. Just get the room cooling off 1/2 hour or more beforehand. 

With a ducted model, noise will be non-issue, plus you can go big on BTU's and cool both rooms. Mitsubishi is the standard to compare any other brands to. Don't do a wall unit. They tap out around 12k cooling BTUs before they get noisy (by HT room standards).

BTW, I'm a Director on 2 HOA Boards! HOA's are a double-edged sword. However, they cannot tell you that you can't have an exterior HVAC unit. It would be equivalent to telling you that you can't have an A/C unit period. I only know of one HOA with such a restriction, and it's all condos built in the 1980's. They have a special HVAC system that is hidden in the side of each unit, along an exterior wall. Expensive to repair, and weird.

What they *can* do is force you to put some screening around it. They can also force you to re-locate it unless you fill out your architectural review form carefully. Do yourself a favor and get the installer to sign off on the bid for the HVAC that the ONLY place it can go - in his/her professional opinion - is where you want it to be. Case closed. 


Edit: PM me when you get around to filing the HOA paperwork if you get push back, and I'll give you some free consulting.


----------



## doveman

HT Geek said:


> It's possible I'm just not following your thought process and we're thinking of the same solution. Or it's possible this is a new-ish technique I hadn't read about yet. I'll look over the links you posted. Thanks for that.


Just to add, I noticed one of the reviews on this page https://www.soundaway.com/sound-dampening-foam-blocks-p/15005.htm says:

"I used this product as a window plug, after fitting this into the window frame it did a great job of reducing sound, however, be warned that this should NOT be used in a window that gets direct sunlight. The area between the foam and the window became so hot that it scorched/warped the vinyl window frame so badly that the entire window is going to have to be replaced. There really should be a warning about this in the description."

So even if the foam itself is fire-resistant, I would still have to find a way to prevent the sunlight heating up the space. Maybe tinted film would do the job, although it would be nice to find a solution that leaves a clear view when the plugs are removed. I certainly don't want to use reflective film as that will completely block the view out the windows.


----------



## mattztt

doveman said:


> Just to add, I noticed one of the reviews on this page https://www.soundaway.com/sound-dampening-foam-blocks-p/15005.htm says:
> 
> "I used this product as a window plug, after fitting this into the window frame it did a great job of reducing sound, however, be warned that this should NOT be used in a window that gets direct sunlight. The area between the foam and the window became so hot that it scorched/warped the vinyl window frame so badly that the entire window is going to have to be replaced. There really should be a warning about this in the description."
> 
> So even if the foam itself is fire-resistant, I would still have to find a way to prevent the sunlight heating up the space. Maybe tinted film would do the job, although it would be nice to find a solution that leaves a clear view when the plugs are removed. I certainly don't want to use reflective film as that will completely block the view out the windows.


You could experiment with foil film backing on the foam to reflect light back out rather than allowing the foam to absorb it.


----------



## Mr.Guvernment

*STC and frequencies below 125 Hz*

Amazing information here, still reading through it all. 

From some quick reading I have done, STC rating only apply to 125 Hz to 4k , not below 125 Hz which is where many sounds sit. ( https://www.soundproofingcompany.com/soundproofing_101/understanding-stc-and-stc-ratings)

Would the best way to dampen those frequencies still be a combination of the usual methods, detaching walls, layer, 5/8" drywall et cetera? Or is another application required to get those lower frequencies? Or we just have to accept that those lower frequencies will always find there way through?

[EDIT]
"Creating a decoupled structure is the only way to really kill the bass,”
https://www.soundandvision.com/content/soundproofing-101-how-keep-your-home-theater-quiet

[EDIT]

More and More reading and seems there are several ways to do it, all comes down to budget and time. I am likely just going to go with double 5/8 DW with green glue for the ceilings and possibly the walls around my furnace and such when i build out those walls.

Also be putting in a bathroom and bedroom down here so will seal those walls up as well, including insulation in the ceiling and walls (ceiling only filling to 70% or so as over that does not offer much more?)

Question, Being that my ceilings will be insulated and closed up, should I bother insulating separately my duct work as well? Would it also help with preventing sound from carrying through the house? Or would the 1-2 layers of pink insulation be enough (as well as keep the temp loss at a minimum)


----------



## HT Geek

Mr.Guvernment said:


> Amazing information here, still reading through it all.
> 
> From some quick reading I have done, STC rating only apply to 125 Hz to 4k , not below 125 Hz which is where many sounds sit. ( https://www.soundproofingcompany.com/soundproofing_101/understanding-stc-and-stc-ratings)



FYI, the best info is derived from perusing over lab reports where you can see the actual results at particular frequencies. STC isn't just a sub-set of the audio spectrum humans hear, it's also an amalgamation of test results. You can think of it like looking at someone's SAT score. The raw score doesn't tell you if they completely bombed one section of the test and are brilliant at another.



> More and More reading and seems there are several ways to do it, all comes down to budget and time. I am likely just going to go with double 5/8 DW with green glue for the ceilings and possibly the walls around my furnace and such when i build out those walls.
> 
> Also be putting in a bathroom and bedroom down here so will seal those walls up as well, including insulation in the ceiling and walls (ceiling only filling to 70% or so as over that does not offer much more?)
> 
> Question, Being that my ceilings will be insulated and closed up, should I bother insulating separately my duct work as well? Would it also help with preventing sound from carrying through the house? Or would the 1-2 layers of pink insulation be enough (as well as keep the temp loss at a minimum)


It's preferable to insert insulation - preferably loosely packed fiberglass insulation - in gaps such as between ceiling and floor above. It helps slow down sound waves better than open air. 

Metal ducts or flex-duct? It's wise to insulate around ductwork in/above/around the HT room to reduce noise coming into the room. It's also ideal (and perhaps more important) to design the duct-work in such a way that sound isn't likely to reflect in/out of your room via the ducts. The best method is to use flex duct and configure it in an S-shape or make several bends so there isn't a straight line for sound to reflect in/out of the HT room.


----------



## Mr.Guvernment

HT Geek said:


> FYI, the best info is derived from perusing over lab reports where you can see the actual results at particular frequencies. STC isn't just a sub-set of the audio spectrum humans hear, it's also an amalgamation of test results. You can think of it like looking at someone's SAT score. The raw score doesn't tell you if they completely bombed one section of the test and are brilliant at another.
> 
> 
> It's preferable to insert insulation - preferably loosely packed fiberglass insulation - in gaps such as between ceiling and floor above. It helps slow down sound waves better than open air.


Good way to put it, from more reading STC is more a group of methods to dampen sounds vs say "Insulation XYZ" has this STC rating..(why none do)



> Metal ducts or flex-duct? It's wise to insulate around ductwork in/above/around the HT room to reduce noise coming into the room. It's also ideal (and perhaps more important) to design the duct-work in such a way that sound isn't likely to reflect in/out of your room via the ducts. The best method is to use flex duct and configure it in an S-shape or make several bends so there isn't a straight line for sound to reflect in/out of the HT room.


Metal, already run,unfinished basement of an already built house. I could certainly change them to Flex-duct if it would be more beneficial. I was considering moving one of the ducts from where it is located. In our old place the wife also noted hearing up on the 2nd floor sound from my games coming out of the vent since it was a straight shot up from where i was and an open ceiling.

I wont have a high end HT system like most here do but there is a sub and i do like to enjoy movies, or even just gaming with my Monitor B&W speakers i use via a DAC so anything to help will be ideal!


----------



## HT Geek

Mr.Guvernment said:


> Good way to put it, from more reading STC is more a group of methods to dampen sounds vs say "Insulation XYZ" has this STC rating..(why none do)
> 
> Metal, already run,unfinished basement of an already built house. I could certainly change them to Flex-duct if it would be more beneficial. I was considering moving one of the ducts from where it is located. In our old place the wife also noted hearing up on the 2nd floor sound from my games coming out of the vent since it was a straight shot up from where i was and an open ceiling.
> 
> I wont have a high end HT system like most here do but there is a sub and i do like to enjoy movies, or even just gaming with my Monitor B&W speakers i use via a DAC so anything to help will be ideal!



Flex-duct is preferable. If you don't mind a weekend project or hiring it out, I'd recommend it. An upside is you'll be able to strategically place your supply and return vents in the room (hint: supplies should go up front, returns in the rear). Make sure the supply/return volumes are balanced (volume of air per minute). Another tip: wider/bigger duct = quieter experience in the room. If you face space restrictions that limit you going from say a 4" metal duct to an 8" flex duct, see if you can use a 6" duct and make it longer or use mufflers to mitigate the sound and speed of the air before it gets into your room.


Quieting the air is less important if you're the type of person who routinely watches loud content, though even then most loud movies also have quiet bits from time to time. I can tell you that - as an example - I have on my list to modify one of my amps because the fan is too noisy for my taste. I hate the fact I can hear it clearly during quiet movie scenes. If you're like me, air noise from the vents may bother you unless you take steps to ensure it is slowed down enough to where you won't hear it.


----------



## mhutchins

Also, if you are going to go to the trouble to replace your metal duct work, you should consider constructing dead vents where the duct work leaves or enters the theater. This will really help reduce sound transmission from the theater into the rest of the house.


Mike


----------



## HT Geek

Depending on the circumstances of the build. Dead vents are normally used when an in-line muffler (aka soffit muffler) is not practical or there is an HVAC supply issue to begin with (e.g. no supply lines in the room in the first place). Just depends. Sometimes it's not possible to use a muffler. Sometimes it's not possible to construct a dead vent. The key is to get the velocity of air below ~250 fpm (feet per minute).

But to Mike's point, there are a number of tools in the toolkit that can be used independently or together. Among them:




Flex duct
Larger diameter ducts
Mufflers
Dead vents
Extending the length of duct work (normally in conjunction with bends)
Increase surface area of vents
Y-splitter (have more vents off same duct branch); basically same as some of the other tips combined

Other than flex duct itself, they all have the same primary goal: increasing duct volume. As long as the speed of forced air entering the beginning of the duct branch doesn't change, the net effect is reduced airflow velocity at the other end of the duct (i.e. opening into the room for a supply vent). 

The same principles can be used to solve other climate control problems in a home. And the opposite is also true. If you need more velocity in a room (probably not your HT room), one way to do that is to swap out the duct with a smaller diameter.

Return vents are _usually_ a non-issue in this regard (noise), but I recommend treating them the same as your supply vents (i.e. draw from the same basket of tricks to _make sure_ they'll be quiet in your HT room).

There is a bit of science to all this. I suggest you become familiar with the attached document. First and foremost, you need to balance your CFM (cubic feet per minute) in the room. Air in should = air out. If you don't you will get unequal pressure and potentially other problems. Get it as close as you can to 1:1.

Next, velocity; which is mostly a supply vent concern. If > 250 fpm, see solution list above.

Hope that helps. 


EDIT: I'm not aware of any chart for velocity. Your best bet if you have a concern with velocity is try to rent an anemometer. Next best option, use your ears and guesstimate. No joke. Now, if you have a multi-stage fan compressor then things get more complicated and beyond scope of this post.


----------



## barfle

HVAC noise has always been my nemesis, so I appreciate the info. I just bought a house with a pretty good room for a HT, and fortunately it has flex duct going to it, along with a reasonable crawl space to allow a few bends in it. One thing I thought of is that the grates have vents that you can close, which, of course makes them noisier yet. I was wondering if there are control vanes that you could operate remotely. I suppose I could rig something, but it's getting complicated already.

Thanks in advance!


----------



## HT Geek

barfle said:


> HVAC noise has always been my nemesis, so I appreciate the info. I just bought a house with a pretty good room for a HT, and fortunately it has flex duct going to it, along with a reasonable crawl space to allow a few bends in it. One thing I thought of is that the grates have vents that you can close, which, of course makes them noisier yet. I was wondering if there are control vanes that you could operate remotely. I suppose I could rig something, but it's getting complicated already.


The old saying, "Nothing ventured, nothing gained" comes to mind. 

There are several approaches you could take that would solve your noise problem, but they will all require varying degrees of effort and inconvenience.

The best route would be to modify your existing HVAC duct work into/in the room. It's also likely to be the most work and you would need to plan it out well in advance before beginning construction.

A second option would be to install electronic dampers. You could leave the existing duct work in place. Also requires careful planning, including how you're going to be able to control the dampers remotely. There are a few good systems on the market that interface with the main HVAC system and can do some pretty cool stuff, such as cycling your heating/cooling air in the house if your system allows more than one thermostat to be hooked up (e.g. you want A/C in the HT room but heat remainder of the same floor of house).

Third, you can do a variation on the 2nd theme. Install remote dampers and control them remotely vai an IoT device.

There are manual dampers as well, but they would have to be installed and often don't work well (especially in flex ducts). I wouldn't go that route with flex duct. This solution is awkward because you must have unfettered access to the damper controls (e.g. on your ceiling).

Other options exist. That's a quick run-down of some off-the-shelf choices.


----------



## barfle

To be sure, I'll make mistakes with the HVAC stuff, but in my previous house, the HT was in the basement so outside noise was rarely a problem, but the vent was always a source of noise. And being in the basement in Virginia, turning off the fan simply wasn't an option. It took about an hour for the dampness to become irritating.

This time, the HT is in its own room over the garage, with the flex ducts (including cold air return) in a crawl space that, while not roomy, would allow me to play around with routing, so I'm looking forward to a quieter system. And I'll get big ducts and big grilles to slow down the air and quiet it some more. There are challenges galore in this project, including the fact that I'm doing everything except carpet installation myself. And since I'm past retirement age, I have the time but my body keeps telling me that I'm not 30 any more!


----------



## Ladeback

barfle said:


> To be sure, I'll make mistakes with the HVAC stuff, but in my previous house, the HT was in the basement so outside noise was rarely a problem, but the vent was always a source of noise. And being in the basement in Virginia, turning off the fan simply wasn't an option. It took about an hour for the dampness to become irritating.
> 
> This time, the HT is in its own room over the garage, with the flex ducts (including cold air return) in a crawl space that, while not roomy, would allow me to play around with routing, so I'm looking forward to a quieter system. And I'll get big ducts and big grilles to slow down the air and quiet it some more. There are challenges galore in this project, including the fact that I'm doing everything except carpet installation myself. And since I'm past retirement age, I have the time but my body keeps telling me that I'm not 30 any more!


HVAC is a main thing that has been holding me up to finishing my theater or the whole basement. My theater is in the basement and being in KC the basement is cool most of the time, but not humid. I have had a few estimates on a whole new second system that would cost close to $4000 and just adding duct work and dampers to the existing system that would be around $2000. I haven't gotten and estimate for a mini split yet, but the wife doesn't really seem to want to tell what she thinks and says they are all to high. 

My current HVAC system is over-sized for the house, but I worry if I tap into it for the basement the main level will suffer. Th last option I thought of was to close it all in and build a dead vent supply and return and pull air fro man unfinished room and and push to another unfinished room. I am looking at the Mr. Cool Mini split for at least the theater for now maybe.


----------



## HT Geek

Ladeback said:


> HVAC is a main thing that has been holding me up to finishing my theater or the whole basement. My theater is in the basement and being in KC the basement is cool most of the time, but not humid. I have had a few estimates on a whole new second system that would cost close to $4000 and just adding duct work and dampers to the existing system that would be around $2000. I haven't gotten and estimate for a mini split yet, but the wife doesn't really seem to want to tell what she thinks and says they are all to high.
> 
> My current HVAC system is over-sized for the house, but I worry if I tap into it for the basement the main level will suffer. Th last option I thought of was to close it all in and build a dead vent supply and return and pull air fro man unfinished room and and push to another unfinished room. I am looking at the Mr. Cool Mini split for at least the theater for now maybe.


Yeah, you've got several options.

Another idea is to create a zoned system in your home, where the HT room is an independent zone. My house is setup like that atm. The HT room is one zone, and the remainder of the 2nd floor is another. As is right now, the "main" zone (remainder of 2nd floor / non-HT room) gets heated/cooled when the HT room thermostat kicks in. This is because otherwise I'd be pumping way too much air into just the one room and burn out the HVAC motor.

The advantages to my current setup are: 1) isolation of climate in the HT room (e.g. when heat is on in remainder of 2nd floor, it can be off in HT room); and 2) ability to control HVAC from HT room. The HT thermostat is also a Zigbee thermostat, allowing it to be remote controlled.


----------



## Mr.Guvernment

Man, some epic information in here about all of this, processing it all and planning my basement even more! I will try to get some floor layouts of what my basement looks like and my ideal plans to get some feedback.

One more question for the pro's!

Insulation between my joists (basement ceiling to kitchen floor) One read I saw it noted you should not fill the space 100% with insulation but 70-80% is ideal as it creates a dense airspace, if you do more you are potentially "bridging the gap" which will transmit sound and defeat the purpose.

Some insulation I am looking at is either 6" thick or 5 1/2" thick. My joist are about 11 inches tall, so it would fill just about half, is 50% filled enough for good dampening, or should i try and do a dual layer with some thinner insulation but under the 70-80% if that matters?

With that, is wool based batt better than fiber glass, or is it purely the R-value that seems to be the main difference and the fire rating that is higher that fiber glass insulation?

One is 2 R higher, but is that worth almost twice the cost?


2 possible options:

*$0.79 / Sq. Ft.*
Johns Manville R20 120.1SF 23-in x 47-in Batt Insulation
Square Footage:	120.1sq. ft.
Width:	23 inches
Depth:	6 inches
Purchase Price:$94.99


*$1.38 / Sq. Ft.*
ROCKWOOL COMFORTBATT® R22 24-in O.C. for 2x6 Wood Studs
Square Footage:	37½sq. ft.
Thickness:	5½ inches
Width:	23 inches
Purchase Price:$51.89


----------



## HT Geek

Mr.Guvernment said:


> Man, some epic information in here about all of this, processing it all and planning my basement even more! I will try to get some floor layouts of what my basement looks like and my ideal plans to get some feedback.
> 
> One more question for the pro's!
> 
> Insulation between my joists (basement ceiling to kitchen floor) One read I saw it noted you should not fill the space 100% with insulation but 70-80% is ideal as it creates a dense airspace, if you do more you are potentially "bridging the gap" which will transmit sound and defeat the purpose.
> 
> Some insulation I am looking at is either 6" thick or 5 1/2" thick. My joist are about 11 inches tall, so it would fill just about half, is 50% filled enough for good dampening, or should i try and do a dual layer with some thinner insulation but under the 70-80% if that matters?
> 
> With that, is wool based batt better than fiber glass, or is it purely the R-value that seems to be the main difference and the fire rating that is higher that fiber glass insulation?
> 
> One is 2 R higher, but is that worth almost twice the cost?
> 
> 
> 2 possible options:
> 
> *$0.79 / Sq. Ft.*
> Johns Manville R20 120.1SF 23-in x 47-in Batt Insulation
> Square Footage:	120.1sq. ft.
> Width:	23 inches
> Depth:	6 inches
> Purchase Price:$94.99
> 
> 
> *$1.38 / Sq. Ft.*
> ROCKWOOL COMFORTBATT® R22 24-in O.C. for 2x6 Wood Studs
> Square Footage:	37½sq. ft.
> Thickness:	5½ inches
> Width:	23 inches
> Purchase Price:$51.89


I suspect you're going to get different answers to those questions from different people. Like visiting a doc for a 2nd and 3rd opinion. 

My advice is:


Use the cheapest insulation
If the insulation is loosely filled, it's doubtful - IMHO - that it will matter if you fill it 80% or 100%
The key is "loosely" filled
*IF* you were using mineral wool, then I'd say yeah the 80% rule is prolly good idea because you can't really keep that "loose" per se

There is almost no benefit to mineral wool vs. "pink fluffy." It's about 1 db better under some circumstances. Basically, you're better off spending the extra $ on another technique of sound proofing (e.g. more drywall/mass) or watching movies. 

The Rockwool is sometimes better simply from an application standpoint. For instance, if you have a 3" gap to fill versus 3.5". That kind of thing. Personal preference for some people as well. As another example, I can't stand blown-in insulation. I've dealt with it so much being in attics and itching like crazy, I hate it. Just me.


----------



## A.T.M.

Mr.Guvernment said:


> .





HT Geek said:


> *Use the cheapest insulation
> *If the insulation is loosely filled, it's doubtful - IMHO - that it will matter if you fill it 80% or 100%
> *The key is "loosely" filled
> **IF* you were using mineral wool, then I'd say yeah the 80% rule is prolly good idea because you can't really keep that "loose" per se
> 
> 
> The Rockwool is sometimes better simply from an application standpoint. For instance, if you have a 3" gap to fill versus 3.5". That kind of thing. Personal preference for some people as well. As another example, I can't stand blown-in insulation. I've dealt with it so much being in attics and itching like crazy, I hate it. Just me.


Pink fluffy (cheaper) or Rockwool (better for infernos and moisture but you said moisture wasn't an issue)
Don't forget you could also fill that 11" gap with DW/GG/DW on the ceiling (upstairs floor boards), to cut down on the space and help keep the sound in/ or out whatever the goal may be. Sound proofing company has a good visual of this on their site.

Aaron


----------



## doveman

I've got my 9mm ply backing boards cut for my window plugs now, just need to decide what foam/insulation to get to stick to them now.

In terms of non-flammable soundproofing foam, the available options seem to be this 27-30kg/m3 25mm foam which is £46.48 for 1mx1.5m
http://www.keepitquiet.co.uk/non-flammable-acoustic-foam/

this 75-90kg/m3 32mm foil-faced composite which is £66.84 for 1.2mx0.9m
http://www.keepitquiet.co.uk/non-flammable-acoustic-foam-frffb6/

or this 100kg/m3 34mm composite which is £28 for 1mx0.6m (plus £38 delivery but they have a depot near enough for me to collect from)
https://www.customaudiodirect.co.uk/soundproofing/foam-barrier-composite-soundproofing-mat

Any of those options gets rather expensive for the 4.5m2 I need though, so I'm wondering if I could just use Rockwool slabs instead?

This 45kg/m3 RWA45 is £22 for a pack of 9 1200x600x50mm slabs
https://www.insulationexpress.co.uk/rockwool-rwa45-acoustic-insulation-slabs

or 60kg/m3 RW3 is £30 for a pack of 8 1200x600x50mm slabs
https://www.insulationexpress.co.uk/rockwool-rw3-acoustic-insulation-slabs

and 100kg/m3 RW5 is £25 for a pack of 4 1200x600x50mm slabs.

Which density would be a good compromise to avoid excessive weight and potential problems with the slabs not sticking to the plywood?

My main concerns are will Rockwool be as non-flammable as the foam (I'm mostly concerned about it combusting in the heat from the sun), will it compress/expand enough to be able to squish a slightly oversized piece in tight against the reveal and remove it on a daily basis and will it stick to the plywood as well as the foam and not come unstuck as it drags against the reveal when being removed?

Obviously Rockwool doesn't have a foil face to reflect the sun but I'm sure I can get some tough foil and stick it on myself for that. 

My plugs need to be about 113-115mm x 63mm, so the rockwool slabs aren't quite wide enough but I figure if I cut them in the middle and stick each half to the board so it overhangs the side of the board slightly, then I can use the offcuts to fill the gap in the middle of the board.


----------



## warwwolf7

HT Geek said:


> A second option would be to install electronic dampers. You could leave the existing duct work in place. Also requires careful planning, including how you're going to be able to control the dampers remotely. There are a few good systems on the market that interface with the main HVAC system and can do some pretty cool stuff, such as cycling your heating/cooling air in the house if your system allows more than one thermostat to be hooked up (e.g. you want A/C in the HT room but heat remainder of the same floor of house).
> 
> Third, you can do a variation on the 2nd theme. Install remote dampers and control them remotely vai an IoT device.
> 
> That's a quick run-down of some off-the-shelf choices.


I've been looking for an of the shelf solution but I have found diy DZ that has been ported on raspberry pi, but that's is not really convenient if you want to sell the house eventually.

Can you propose some products for your option 2?

Thank you 

-Matt


----------



## HT Geek

warwwolf7 said:


> I've been looking for an of the shelf solution but I have found diy DZ that has been ported on raspberry pi, but that's is not really convenient if you want to sell the house eventually.
> 
> Can you propose some products for your option 2?


Matt,

Here are some suggestions.

*Controllers*
2 zones; $150: https://smartzoning.com/smartzone-lite.html
4-20 zones; $200 [4-zone]: https://smartzoning.com/smartzone.html (these can be daisy-chained; they are 4x zones per unit)
4 zone, Honeywell; est. $300+ depending on model and options: https://forwardthinking.honeywellhome.com/products/zoning/detail/truezone_panels.html

The Honeywell, you will pay $$$ for name brand. However, they have a robust system. I've used EcoJay. Weird name, but good quality. Made in USA (Texas).

*Dampers *(sometimes referred to as "dampners")

Honeywell makes complete solutions, including dampers. They also have wireless controllers that can be useful for retrofits.
https://forwardthinking.honeywellhome.com/products/zoning/

This is a good overview of damper types: https://smartzoning.com/dampers.html

Suggest you get electronic dampers with *Belimo* actuators. They are manufactured in Italy and should come with a 5 or 10 year warranty on the actuator motor and solenoid.


*Where to buy dampers?*

This is the tough part (finding a reputable place to buy them).

These look legit: https://zoningsupply.com/buy/power-zone-damper-round
Surprisingly, EBay can be a good source


EDIT: Just to set expectations, unless you use a system like Honeywell's wireless unit, you will need to hard-wire a thermostat in the HT room to the zone controller. And hard-wire your other thermostats using the same HVAC unit to the zone controller. Then you hard-wire the zone controller to the actual HVAC unit. And you hard-wire the electronic dampers to the zone controller. Whole lot of wires! It's a good idea to plan for that when you are mapping out where things will be located.

Regarding thermostats, I use a Zigbee thermostat. I have not looked at the Honeywell wireless unit in detail. I'd be concerned about interfacing with it from a universal remote controller. I wanted an option that worked with Z-Wave, ideally. Zigbee was close enough and I bought a Vera Plus IoT hub to manage it and my Z-Wave devices. It all works like a champ with the Vera acting as the traffic cop between all the devices. Allows me to adjust the thermostat remotely using iRule remote control.


----------



## Ladeback

HT Geek said:


> Matt,
> 
> Here are some suggestions.
> 
> *Controllers*
> 2 zones; $150: https://smartzoning.com/smartzone-lite.html
> 4-20 zones; $200 [4-zone]: https://smartzoning.com/smartzone.html (these can be daisy-chained; they are 4x zones per unit)
> 4 zone, Honeywell; est. $300+ depending on model and options: https://forwardthinking.honeywellhome.com/products/zoning/detail/truezone_panels.html
> 
> The Honeywell, you will pay $$$ for name brand. However, they have a robust system. I've used EcoJay. Weird name, but good quality. Made in USA (Texas).
> 
> *Dampers *(sometimes referred to as "dampners")
> 
> Honeywell makes complete solutions, including dampers. They also have wireless controllers that can be useful for retrofits.
> https://forwardthinking.honeywellhome.com/products/zoning/
> 
> This is a good overview of damper types: https://smartzoning.com/dampers.html
> 
> Suggest you get electronic dampers with *Belimo* actuators. They are manufactured in Italy and should come with a 5 or 10 year warranty on the actuator motor and solenoid.
> 
> 
> *Where to buy dampers?*
> 
> This is the tough part (finding a reputable place to buy them).
> 
> These look legit: https://zoningsupply.com/buy/power-zone-damper-round
> Surprisingly, EBay can be a good source
> 
> 
> EDIT: Just to set expectations, unless you use a system like Honeywell's wireless unit, you will need to hard-wire a thermostat in the HT room to the zone controller. And hard-wire your other thermostats using the same HVAC unit to the zone controller. Then you hard-wire the zone controller to the actual HVAC unit. And you hard-wire the electronic dampers to the zone controller. Whole lot of wires! It's a good idea to plan for that when you are mapping out where things will be located.
> 
> Regarding thermostats, I use a Zigbee thermostat. I have not looked at the Honeywell wireless unit in detail. I'd be concerned about interfacing with it from a universal remote controller. I wanted an option that worked with Z-Wave, ideally. Zigbee was close enough and I bought a Vera Plus IoT hub to manage it and my Z-Wave devices. It all works like a champ with the Vera acting as the traffic cop between all the devices. Allows me to adjust the thermostat remotely using iRule remote control.


I had an estimate to install ductwork in my basement for the theater, and two rooms with a damper and it was around $1800 and they said another $1800 for a electronic damper. If I could get a electronic damper cheaper that I may lean that way, am also looking at using a Mr. Cool Mini Split system for the three rooms.


----------



## HT Geek

Ladeback said:


> I had an estimate to install ductwork in my basement for the theater, and two rooms with a damper and it was around $1800 and they said another $1800 for a electronic damper. If I could get a electronic damper cheaper that I may lean that way, am also looking at using a Mr. Cool Mini Split system for the three rooms.


+$1800 to go from a single (manual) damper to a single electronic damper? Sounds expensive - and you're probably getting hosed at that rate - but I couldn't say for sure without reviewing the job site in detail. 

There is no difference in the labor portion of inserting a damper into an HVAC duct. However, there is wiring involved as I mentioned previously. Aside from the low-voltage HVAC wiring, there's powering the zone system in the first place. If a new outlet needs to be installed, that could run a few hundred $ by itself, depending on the details. 

Thinking about this some more.... My zoned system is in the attic, so if I need to change something it's not a huge deal. If your system is going to have living space above it, that makes the situation a bit more complicated. Another factor is the electronic dampers are larger in overall size than manual (non-electronic) dampers. The extra height/width needs to be accommodated if it's sitting between joists. This could reduce your maximum size duct, for example.

Plan for how to deal with a part failure, should one occur. For example if you have an electronic damper installed between floors, that's a potential risk. How would you access it to check on it or replace it?

The zone controllers need to be near a 120 VAC outlet. And that is another issue that can complicate things.

All that said, what it boils down to is if anything is going to be difficult to access, it will be the dampers. The rest of it should essentially boil down to extra wiring. So, in an unfinished environment, I'd expect the costs to be minimal (to add an electronic zoned system) other than the cost of the zoning system components themselves.

Sometimes, contractors will artificially inflate the cost of a job if they've never done it before or they don't want to do it. The latter happens in case they screw something up they know they probably won't lose money, and the latter is so they feel it's worth their time.

If you want to DIY the zoning, it's not very hard. The toughest part is splitting the duct and inserting the damper, securing the damper (their weight needs to be supported), and patching the duct. And that process is not difficult. Make sure you have all the parts and materials on hand before you begin, and do the work at a time of day when your HVAC doesn't normally run much, because you will need to turn it off during the install process.

To DIY a single damper, you should be looking at a total investment of about $450 max for parts. That's zone controller + damper + wiring + HVAC parts (e.g. mastic, zip ties, HVAC UL-listed tape, etc.). Add $35 or so if you need to add a new A/C power outlet (including buying new 14/2 or 12/2 wire).

The zone systems draw very little power. You can easily run them off the same circuit as the HVAC unit and run long lengths of (low voltage) thermostat wire to the zone controller if you need to.

One more caveat.... flex duct systems are much easier to work with vs. solid metal systems. The latter requires more specialized tools and is generally looked upon unfavorably for HT uses due to noise.


----------



## Ladeback

The $1800 to $1900 is to run new duct trunks off the existing system in the basement and run supplies off it to the three rooms. The electronic damper would be near the existing furnace that is in my storage area/AV room/workout room. I need to get other estimates to see what others think I need. Another estimate was for a whole separate system which was close to $3600. I have the room for it just want to give up the space. 

Another thought is to do a mini split in the theater and run new trunks for just the other two rooms and use a manual damper.

Sent from my SM-N960U using Tapatalk


----------



## HT Geek

Ladeback said:


> My theater is in the basement and being in KC the basement is cool most of the time, but not humid....
> 
> My current HVAC system is over-sized for the house, but I worry if I tap into it for the basement the main level will suffer.....


Maybe, but not necessarily. A bigger risk is the opposite; i.e. if you compartmentalize a zoned system too much such that you have a large HVAC trying to push air into a small space (e.g. only 1 or 2 rooms/zones).



Ladeback said:


> The $1800 to $1900 is to run new duct trunks off the existing system in the basement and run supplies off it to the three rooms. The electronic damper would be near the existing furnace that is in my storage area/AV room/workout room. I need to get other estimates to see what others think I need. Another estimate was for a whole separate system which was close to $3600. I have the room for it just want to give up the space.
> 
> Another thought is to do a mini split in the theater and run new trunks for just the other two rooms and use a manual damper.


Mini-splits are not my forte, so I can't comment on the Mr. Cool brand.

Given your existing HVAC situation, have you estimated the total load on the system atm and compared that to its rating? You don't need a perfect load estimate calc. Just enough to ballpark the correct size unit for right now versus now + newly finished basement. It sounds as if your unit was purposely up-sized. Perhaps in anticipation of finishing the basement and that adding to the total house volume at some point.

Tapping more branches off the main to accommodate your basement rooms will not necessarily be a problem for the main level. The full impact depends on multiple factors, but at the end of the day it's all about pull/push of air (pull thru returns/push thru vents).

It sounds as if you may be able to simply add some new branches off your air handler in the basement to the 3 rooms down there. 

If the basement and upstairs are large enough, you might be able to do something like an upstairs zone and downstairs zone. If you want a dedicated HT room thermostat, you will need to design your zone handling so the remainder of the basement (and possibly the main level) gets air when the HT room gets air, to prevent the zone you are trying to heat/cool from being too small and damaging the HVAC unit.

The whole thing requires some planning, but it can be done DIY. It's not especially difficult work.


----------



## doveman

mattztt said:


> You could experiment with foil film backing on the foam to reflect light back out rather than allowing the foam to absorb it.


Yeah, I think I'll try that approach first as it will leaves the windows clear when the plugs are removed. 

I'm still a bit concerned that heat could build up in the sealed gap between the foam and the window, as there won't be any fresh air circulating in that space to cool it down but maybe the foil will suffice to control the build up by preventing the foam absorbing and releasing heat, as long as the plugs are removed on a daily basis to allow fresh air in. If I find the space still gets too hot I'll just have to stick foil on the windows. Hopefully wherever I stick the foil it won't annoy my neighbours by reflecting the sun into their windows!


----------



## warwwolf7

HT Geek said:


> Matt,
> 
> Here are some suggestions.
> 
> *Controllers*
> 2 zones; $150: https://smartzoning.com/smartzone-lite.html
> 4-20 zones; $200 [4-zone]: https://smartzoning.com/smartzone.html (these can be daisy-chained; they are 4x zones per unit)
> 4 zone, Honeywell; est. $300+ depending on model and options: https://forwardthinking.honeywellhome.com/products/zoning/detail/truezone_panels.html
> 
> The Honeywell, you will pay $$$ for name brand. However, they have a robust system. I've used EcoJay. Weird name, but good quality. Made in USA (Texas).
> 
> *Dampers *(sometimes referred to as "dampners")
> 
> Honeywell makes complete solutions, including dampers. They also have wireless controllers that can be useful for retrofits.
> https://forwardthinking.honeywellhome.com/products/zoning/
> 
> This is a good overview of damper types: https://smartzoning.com/dampers.html
> 
> Suggest you get electronic dampers with *Belimo* actuators. They are manufactured in Italy and should come with a 5 or 10 year warranty on the actuator motor and solenoid.
> 
> 
> *Where to buy dampers?*
> 
> This is the tough part (finding a reputable place to buy them).
> 
> These look legit: https://zoningsupply.com/buy/power-zone-damper-round
> Surprisingly, EBay can be a good source
> 
> 
> EDIT: Just to set expectations, unless you use a system like Honeywell's wireless unit, you will need to hard-wire a thermostat in the HT room to the zone controller. And hard-wire your other thermostats using the same HVAC unit to the zone controller. Then you hard-wire the zone controller to the actual HVAC unit. And you hard-wire the electronic dampers to the zone controller. Whole lot of wires! It's a good idea to plan for that when you are mapping out where things will be located.
> 
> Regarding thermostats, I use a Zigbee thermostat. I have not looked at the Honeywell wireless unit in detail. I'd be concerned about interfacing with it from a universal remote controller. I wanted an option that worked with Z-Wave, ideally. Zigbee was close enough and I bought a Vera Plus IoT hub to manage it and my Z-Wave devices. It all works like a champ with the Vera acting as the traffic cop between all the devices. Allows me to adjust the thermostat remotely using iRule remote control.


Well, that's a very detailed answer. Thank you very much for your insight. It really is very appreciated.

Thank you 

-Matt


----------



## niccolo

HT Geek said:


> Maybe, but not necessarily. A bigger risk is the opposite; i.e. if you compartmentalize a zoned system too much such that you have a large HVAC trying to push air into a small space (e.g. only 1 or 2 rooms/zones).



What are the consequences of a large HVAC system trying to push air into a small space?


----------



## warwwolf7

niccolo said:


> What are the consequences of a large HVAC system trying to push air into a small space?


Risks :

With a constant speed blower you will have such a high airflow that it will be noisy. Because the airflow was planned for the entire house. Having only one output instead of maybe 10 ventilation outputs will cause major resistance. The heater element might heat up to much. The radiator for your ac might freeze. Your blower will be forcing.

With a constant static pressure type that uses a variable speed blower. The risks are really greater to overheat because of insufficient airflow at the heating element. The risks are also greater to freeze the ac radiator.

Now, the ac radiator will affect the ac compressor, I'm sure they are experts here that can chime in and explain it better or deeper.

To avoid those problems, you should either have a dump zone that is always open so that you never get into those situations. It also exists bypass dampers that will return the output of the furnace back to its intake when pressure gets too high. It's a safety feature that should not be overlooked.

That's a good question. A really good one. I'm glad you asked 

-Matt


----------



## HT Geek

niccolo said:


> What are the consequences of a large HVAC system trying to push air into a small space?


It's not good for the HVAC system. 

The air handler needs to "breathe" per se with comparable push/pull air ratios. When those systems become unbalanced for a period of time, they tend to break. That is partly why HVAC installers focus so much on "sizing" a system. The HVAC is designed to work with equal volumes of air in/out, at equal atmospheric pressure.

It might not be an issue. Really depends on implementation, but if one presumes the space is relatively air tight then it's likely to be an issue over time. 

For example, say you have a 3-ton residential system and you zone it so you're pushing conditioned air into a 20x20x8 room only. Even if the system is able to draw return air from the whole house, it has to blow that air (push) into only a 20x20x8 foot room. So, imagine you are taking the entire volume of air you'd normally move around the home and pushing it into that one room. At the same time, you need to pull air through the returns from the entire home.

So, you end up with significant air pressure differences between that room and the remainder of the home. Close the door to the HT room and it will be more pronounced. 

It's more complex than that. There are other important details such as static pressures, but this is about the extent of my knowledge on the matter, not being an HVAC person but having a rudimentary understanding of some mechanical engineering principles.


----------



## HT Geek

Matt, thanks. Glad you chimed in on this as well.



warwwolf7 said:


> Risks :To avoid those problems, you should either have a dump zone that is always open so that you never get into those situations. It also exists bypass dampers that will return the output of the furnace back to its intake when pressure gets too high. It's a safety feature that should not be overlooked.


FWIW, this is why my zoned system uses the entire 2nd floor as the dump zone atm. In my case, the HT room is its own zone, but it is designed to give me control over heating/cooling for that room regardless of remainder of the home. If opposite cycle is on in the rest of the home (e.g. heat while I want cooling in the HT room), the dampers in HT room shut. 

Now, my scenario can cause several unwanted situations for occupants of the remainder of my 2nd floor (i.e. outside the HT room), but that is an issue I was willing to accept in exchange for control in the HT room environment.

Back to the HVAC and not overloading it, that is why I don't direct the HVAC to my HT room only. I have a 5-ton system for my 2nd floor. If I diverted all that air into ONLY my HT room.... that would not be a good outcome on several levels. In the future, I plan to add more zones and that will give me the ability to re-evaluate the "dump zones" though I'll have to eval the situation for each zone.

It's not a perfect system, but it works for me and it was much cheaper than installing a dedicated HVAC unit just for one room.


----------



## Ladeback

HT Geek said:


> Matt, thanks. Glad you chimed in on this as well.
> 
> 
> 
> FWIW, this is why my zoned system uses the entire 2nd floor as the dump zone atm. In my case, the HT room is its own zone, but it is designed to give me control over heating/cooling for that room regardless of remainder of the home. If opposite cycle is on in the rest of the home (e.g. heat while I want cooling in the HT room), the dampers in HT room shut.
> 
> Now, my scenario can cause several unwanted situations for occupants of the remainder of my 2nd floor (i.e. outside the HT room), but that is an issue I was willing to accept in exchange for control in the HT room environment.
> 
> Back to the HVAC and not overloading it, that is why I don't direct the HVAC to my HT room only. I have a 5-ton system for my 2nd floor. If I diverted all that air into ONLY my HT room.... that would not be a good outcome on several levels. In the future, I plan to add more zones and that will give me the ability to re-evaluate the "dump zones" though I'll have to eval the situation for each zone.
> 
> It's not a perfect system, but it works for me and it was much cheaper than installing a dedicated HVAC unit just for one room.



My system is a 5 ton one to heat and cool about 2600 sqft on one level. That's why I was first figuring I could tie into it in our basement to heat and cool it. Would need two dampers for the basement, one for the theater and one for the other two rooms. There is already a manual damper built into the system for the upstairs I believe. This would probably be cheaper if I find the right company to do the work. I am handy, but not sure about making and installing duct work is one of them. It would all need to be done before much is done in the basement. I am not worry about the bathroom since it will be a half bath and you won't spend a lot of time in there. Just have to make sure there is a good gap at the bottom of the door.


----------



## HT Geek

Ladeback said:


> My system is a 5 ton one to heat and cool about 2600 sqft on one level. That's why I was first figuring I could tie into it in our basement to heat and cool it. Would need two dampers for the basement, one for the theater and one for the other two rooms. There is already a manual damper built into the system for the upstairs I believe. This would probably be cheaper if I find the right company to do the work. I am handy, but not sure about making and installing duct work is one of them. It would all need to be done before much is done in the basement. I am not worry about the bathroom since it will be a half bath and you won't spend a lot of time in there. Just have to make sure there is a good gap at the bottom of the door.


Actually, I would recommend you put a vent in the bathroom; for a couple reasons. First, you may regret it if you don't. Second, it gives you more vents to work with when you are figuring out balancing the HVAC load by zones and where your overflow vents are at. The challenge with zoning is normally with the supply vents. The return vents should be what the system normally uses. You don't want to mess with them.

The toughest part about the whole thing is the planning. The physical work is not difficult, but does require attention to detail. Presuming flex duct, you want to keep the duct as straight as you can. That's because when it sags too much, it causes the interior to become slightly restricted and increases resistance. Bends and curves increase resistance as well, but you can't help that 100%. 

The HT room portion is of course contrary logic. You want some bends in the HT room's ducts for the purpose of reducing sound. It really does make a difference in terms of air flow noise. I experimented with various designs in my room and I was shocked at how I could hear air flow noise in one duct (straight from HVAC unit) versus another that had 3x 90 degree bends and another 25 feet of duct before it got to the vent. Night and day noise difference. Anyway, point is of course adding those bends is contrary to what HVAC installers are taught. It also means you need to think about the fact those bends will slow down the airflow, and although that is again good for noise, from a comfort standpoint you don't want it slowed too much. It's a balancing act.

If you pay someone to do the work for you, pay close attention to what they are doing from the design standpoint, because they will have a tendency to want to do what you don't want in your HT room. I hope that makes sense. Same thing happens all the time with drywall installs in these rooms. You're asking people to think outside the box and do their work differently.

If you do the work yourself, it will take you the better part of a day but you will save hundreds, possibly thousands of $. Get a friend to help if you can and it will be easier (especially when holding stuff while you secure it with hanging straps as needed).

I'd suggest you get a 4-zone controller. Use one zone for your "main" (i.e. any part of the house not in a zone), one zone for HT room, and one zone for remainder of basement. That gives you one leftover for future use. $150-200. Suggest you plan on total budget $800-1,000 for DIY. That is without knowing full scope of the job. Most of that will be the flex duct. If your duct is 6" or less in diameter, cost should be lower. Widest duct you can use for HT room is ideal (reduced velocity) unless air flow/pressure is an issue (in which case do the opposite and use narrower size ducts).

This is all very general advice, btw. Much really depends on planning. Hate to keep repeating that, but it is true. Planning is paramount. Do your homework before you start working! 

Other thoughts:


*Dampers*
I'm not a big fan of manual dampers in general, but I understand your thoughts on this. Biggest issue I have with them is if you want one in a finished part of the home, there's no good way I've seen to make them not be an eyesore. Plus, after awhile it can be tough to remember which direction is which unless you want to draw arrows on your finished drywall to remind yourself. It's different when the damper is in the same room as the HVAC, where you find them in many older homes.

As I mentioned before, the physical work of installing an electronic one is almost the same. You do need to be mindful of how you'd service it should something go wrong (loose wire, etc. can happen), and you need to run the wires of course. But if the area is unfinished now, that can be dealt with. Worst-case scenario install a fake air return vent where the damper is located and you'll never have to worry about servicing it.

In your case, you could install an electronic damper where the 

The electronic dampers are low voltage (24 vac), so in a house you won't need any special wiring conduit, etc. You can run open wires in an unfinished space such as an attic, crawlspace, or joist cavity. You can use thermostat wires or whatever. I recommend 18-gauge or better. You need 3-wires per damper. Color code them so you know what goes where.


*Duct Work*
Psychologically, this is the hard part. When I spliced ducts, I used a combination of UL registered tape and mastic. No pro is ever going to do that. I used that approach because I didn't trust myself with mastic only, and I like over-engineering things.

Plan to spend ~$50 per 25 feet of duct (retail cost), plus another ~$150 on 48" Panduit duct tightening straps (trust me, just buy the long ones), a 100' hanging strap roll, bucket of mastic, UL 181-A tape, and a nylon tie tensioning tool, a couple thin and cheap paint brushes, and a box of industrial Nitrile gloves. 

Use the paint brushes to apply the mastic. Wear the gloves. Strive for thickness of a nickel. Skip the tape if you prefer not to use it. I would not use tape alone. From what I've observed, if I had to choose one or the other - tape or mastic - I would choose mastic. It's just easier to get into crevices and know there is something plugging the hole. The UL 181 tape is rigid.

I'll skip other tips for now.


*High Velocity and Air Volume*
If you have a situation where there's a high velocity and high volume of air coming into your HT room, you can deal with that by using duct mufflers. They can be bought or hand-made. I've done the latter. Again, not hard but planning is the key. It will take a weekend including allowing time for glue to dry, trips to a hardware store for MDF, cutting it, etc. But the end result is.... Quiet. 


*Low Velocity and Air Volume*
If you end up with the opposite problem, install an in-line duct fan. There are many too choose from. I recommend one made of metal and not the plastic ones. The latter are more quiet though and if the fan will be in close proximity to the room (or even inside it), you may have to go that route. Fantech makes some good metal ones w/5 to 10 year warranties. When you are researching, look for reviews by folks who operate grow farms (yes... the kind of grow farms you now find frequently in Colorado and California... LoL). Those guys run them 24/7 and usually want them quiet, so it's worth reading about their experiences when researching products. Setting expectations... a good 8" fan is going to set you back $200 or more. Don't go cheap on it. You don't want to have to ever replace the damn thing if you can help it.


----------



## niccolo

warwwolf7 said:


> Risks :
> 
> With a constant speed blower you will have such a high airflow that it will be noisy. Because the airflow was planned for the entire house. Having only one output instead of maybe 10 ventilation outputs will cause major resistance. The heater element might heat up to much. The radiator for your ac might freeze. Your blower will be forcing.
> 
> With a constant static pressure type that uses a variable speed blower. The risks are really greater to overheat because of insufficient airflow at the heating element. The risks are also greater to freeze the ac radiator.
> 
> Now, the ac radiator will affect the ac compressor, I'm sure they are experts here that can chime in and explain it better or deeper.
> 
> To avoid those problems, you should either have a dump zone that is always open so that you never get into those situations. It also exists bypass dampers that will return the output of the furnace back to its intake when pressure gets too high. It's a safety feature that should not be overlooked.
> 
> That's a good question. A really good one. I'm glad you asked
> 
> -Matt





HT Geek said:


> It's not good for the HVAC system.
> 
> The air handler needs to "breathe" per se with comparable push/pull air ratios. When those systems become unbalanced for a period of time, they tend to break. That is partly why HVAC installers focus so much on "sizing" a system. The HVAC is designed to work with equal volumes of air in/out, at equal atmospheric pressure.
> 
> It might not be an issue. Really depends on implementation, but if one presumes the space is relatively air tight then it's likely to be an issue over time.
> 
> For example, say you have a 3-ton residential system and you zone it so you're pushing conditioned air into a 20x20x8 room only. Even if the system is able to draw return air from the whole house, it has to blow that air (push) into only a 20x20x8 foot room. So, imagine you are taking the entire volume of air you'd normally move around the home and pushing it into that one room. At the same time, you need to pull air through the returns from the entire home.
> 
> So, you end up with significant air pressure differences between that room and the remainder of the home. Close the door to the HT room and it will be more pronounced.
> 
> It's more complex than that. There are other important details such as static pressures, but this is about the extent of my knowledge on the matter, not being an HVAC person but having a rudimentary understanding of some mechanical engineering principles.



This is really helpful, thanks both!


I have a somewhat unusual situation that this helps me think through, or at least be mindful of potential downsides. I live in temperate coastal California, where we make only modest use of heating during the winter months and where almost no one has central AC, though our house happens to have it. I'm in the process of putting together a lower-budget theater room upstairs, and my cooling options are 1) open windows to bring in cool air 2) put a fairly quiet window AC in if that proves necessary 3) find ways to use my full-house, two-zone (upstairs and downstairs) HVAC system.


That final one is tricky. For starters, if the rest of the house needs the heater going, then AC isn't happening. Even if the house doesn't need heat, if I run AC then I have to cool the full upstairs. I was mulling closing vents in upstairs rooms other than the home theater, possibly even with magnetic vents covers. But then the issues you've raised may manifest. A possible additional option is to have a three-zone controlled installed, to replace my current two-zone controller, and have a dedicated home theater zone. But it sounds like the same issues manifest, unless the AC can somewhat scale back its intensity under those circumstances.


The obvious solution is to install a dedicated mini-split for the home theater room, either on the wall or hidden in the ceiling/attic. The major issue here is cost. For that reason, this probably isn't on the agenda for the foreseeable future. If cooling is really an issue, a window AC that's on the quieter end of the spectrum is probably in the cards, though I recognize the noise it makes will be somewhat annoying (I'm not sure how the quietest window ACs compare with the noise produced by mini-splits, but I'm guessing mini-splits are a lot quieter because key noise-producing components are located away from the room).


----------



## HT Geek

niccolo said:


> I have a somewhat unusual situation that this helps me think through, or at least be mindful of potential downsides. I live in temperate coastal California, where we make only modest use of heating during the winter months and where almost no one has central AC, though our house happens to have it. I'm in the process of putting together a lower-budget theater room upstairs, and my cooling options are 1) open windows to bring in cool air 2) put a fairly quiet window AC in if that proves necessary 3) find ways to use my full-house, two-zone (upstairs and downstairs) HVAC system.


My first thought for your situation is a dead vent. Your climate should be amenable to that approach, and it's cheap. 

Of course, this is presuming you have the space, which is another logistical issue. If you are space constrained as well then it gets tricky because you don't want to use another room as a dead vent that isn't really a dead vent (i.e. compromising sound proofing to get air flow). So, I think if you _are _space constrained then some sort of forced air circulation is a must.

Even with a dead vent, an in-line blower fan would be a good idea to help promote air exchange.

If you want to get fancy with a zoned system, you could theoretically create a multi-zone system with your current HVAC and introduce an exhaust fan that blows conditioned air outside. This would solve the inverse cool/heat mode versus remainder of your home. However, you would need a fresh air input as well to balance the air pressure in your home. That means you'd need something like an electronic damper for each of 1) exhaust to outdoors vent; 2) fresh air intake vent; 3) HT room; 4) remainder of home. It gets complicated and potentially expensive and at that point, and may be wiser to have a dedicated single zone mini-split for HT room. On the mini-split route, depending on room size, I wouldn't go less than 12,000 BTU size unless the room is really small.

If you have concerns that a dead vent might not cut it; IOW if you can imagine you *could* decide you wanted climate control for the HT room in the future, I would take that into consideration now while you're in the planning stage and see if you can design and build the dead vent such that it would help rather than inhibit a changeover in the future if desired.

You need some kind of airflow no matter what or stale air will be an issue.


----------



## niccolo

HT Geek said:


> My first thought for your situation is a dead vent. Your climate should be amenable to that approach, and it's cheap.
> 
> Of course, this is presuming you have the space, which is another logistical issue. If you are space constrained as well then it gets tricky because you don't want to use another room as a dead vent that isn't really a dead vent (i.e. compromising sound proofing to get air flow). So, I think if you _are _space constrained then some sort of forced air circulation is a must.
> 
> Even with a dead vent, an in-line blower fan would be a good idea to help promote air exchange.
> 
> If you want to get fancy with a zoned system, you could theoretically create a multi-zone system with your current HVAC and introduce an exhaust fan that blows conditioned air outside. This would solve the inverse cool/heat mode versus remainder of your home. However, you would need a fresh air input as well to balance the air pressure in your home. That means you'd need something like an electronic damper for each of 1) exhaust to outdoors vent; 2) fresh air intake vent; 3) HT room; 4) remainder of home. It gets complicated and potentially expensive and at that point, and may be wiser to have a dedicated single zone mini-split for HT room. On the mini-split route, depending on room size, I wouldn't go less than 12,000 BTU size unless the room is really small.
> 
> If you have concerns that a dead vent might not cut it; IOW if you can imagine you *could* decide you wanted climate control for the HT room in the future, I would take that into consideration now while you're in the planning stage and see if you can design and build the dead vent such that it would help rather than inhibit a changeover in the future if desired.
> 
> You need some kind of airflow no matter what or stale air will be an issue.



It seems fairly clear that using a whole house system to try to cool one room, and not others, isn't a great option. Cooling the entire upstairs, or at least several rooms up there, is possibly an option, I'd have to get a handle on the minimum space I'd have to cool without the negative issues raised. I'll try to talk with an AC tech to get a handle on that. My best guess is that given budget constraints, I'll probably just end up getting a window air conditioner with fairly high capacity that's as quiet as possible.


----------



## niccolo

HT Geek said:


> My first thought for your situation is a dead vent. Your climate should be amenable to that approach, and it's cheap.
> 
> Of course, this is presuming you have the space, which is another logistical issue. If you are space constrained as well then it gets tricky because you don't want to use another room as a dead vent that isn't really a dead vent (i.e. compromising sound proofing to get air flow). So, I think if you _are _space constrained then some sort of forced air circulation is a must.
> 
> Even with a dead vent, an in-line blower fan would be a good idea to help promote air exchange.
> 
> If you want to get fancy with a zoned system, you could theoretically create a multi-zone system with your current HVAC and introduce an exhaust fan that blows conditioned air outside. This would solve the inverse cool/heat mode versus remainder of your home. However, you would need a fresh air input as well to balance the air pressure in your home. That means you'd need something like an electronic damper for each of 1) exhaust to outdoors vent; 2) fresh air intake vent; 3) HT room; 4) remainder of home. It gets complicated and potentially expensive and at that point, and may be wiser to have a dedicated single zone mini-split for HT room. On the mini-split route, depending on room size, I wouldn't go less than 12,000 BTU size unless the room is really small.
> 
> If you have concerns that a dead vent might not cut it; IOW if you can imagine you *could* decide you wanted climate control for the HT room in the future, I would take that into consideration now while you're in the planning stage and see if you can design and build the dead vent such that it would help rather than inhibit a changeover in the future if desired.
> 
> You need some kind of airflow no matter what or stale air will be an issue.



On the dead vent, that's an interesting idea. The room shares walls with:



- the outdoors (which is cool in the evenings most of the year), though I know that's not what you meant with a dead vent (though some sort of fan with a filter would be a great way to bring fresh air in and presumably pretty easy to either punch through the room wall or wall in the attic immediately above the theater room; 



- with a small storage room, on the other side of which is a home office; 



- and with a large two story open space at the core of the house. 



Sound leakage into the storage room is non-issue, sound leakage into the home office on the other side of the storage room is not ideal but maybe manageable, sound leakage into the open space at the core of the house would be problematic.


----------



## warwwolf7

niccolo said:


> This is really helpful, thanks both!
> 
> 
> I have a somewhat unusual situation that this helps me think through, or at least be mindful of potential downsides. I live in temperate coastal California, where we make only modest use of heating during the winter months and where almost no one has central AC, though our house happens to have it. I'm in the process of putting together a lower-budget theater room upstairs, and my cooling options are 1) open windows to bring in cool air 2) put a fairly quiet window AC in if that proves necessary 3) find ways to use my full-house, two-zone (upstairs and downstairs) HVAC system.
> 
> 
> That final one is tricky. For starters, if the rest of the house needs the heater going, then AC isn't happening. Even if the house doesn't need heat, if I run AC then I have to cool the full upstairs. I was mulling closing vents in upstairs rooms other than the home theater, possibly even with magnetic vents covers. But then the issues you've raised may manifest. A possible additional option is to have a three-zone controlled installed, to replace my current two-zone controller, and have a dedicated home theater zone. But it sounds like the same issues manifest, unless the AC can somewhat scale back its intensity under those circumstances.
> 
> 
> The obvious solution is to install a dedicated mini-split for the home theater room, either on the wall or hidden in the ceiling/attic. The major issue here is cost. For that reason, this probably isn't on the agenda for the foreseeable future. If cooling is really an issue, a window AC that's on the quieter end of the spectrum is probably in the cards, though I recognize the noise it makes will be somewhat annoying (I'm not sure how the quietest window ACs compare with the noise produced by mini-splits, but I'm guessing mini-splits are a lot quieter because key noise-producing components are located away from the room).


Do you have a constant speed motor or variable speed motor that's keeping the same static pressure? 

With a constant speed blower and your 2zones ctrller :

Look into a bypass damper that open when pressure is too high. So this will prevent your blower from working too hard by reducing the static pressure. This will allow the air to come back into the furnace, allowing enough air to go through the coil in your furnace. Thus preventing freezing of your coil. Coil needs airflow. The air coming out of your vent will become colder and colder as it cool (because cool air is coming back in the furnace) your room until your room reach its correct temp.

À bypass damper is installed between the supply(output) of the furnace and its return(input) . The further from the furnace as it can be.

With a constant pressure variable speed blower, you run a risk to have insufficient air flow. Even with a bypass damper. You would need a multi stage compressor I think. 


Here's some reading for you. 

https://www.pvhvac.com/blog/got-hvac-zones-you-might-need-a-bypass-damper-or-not

-Matt


----------



## HT Geek

@*niccolo*,

Good point above from @*warwwolf7*. I'd forgotten about that strategy. As he said, it has the advantage of cooling/heating faster because the return air gets closer to the ideal temp as it is running. You should be mindful of how close the bypass duct is to the blower. Either way, there are different ways to solve the problem. 

As far as a dead vent is concerned, how large is that adjacent storage area? And how large will your HT room be? (3-dimenion ballpark measurements, pls)


----------



## niccolo

warwwolf7 said:


> Do you have a constant speed motor or variable speed motor that's keeping the same static pressure?
> 
> With a constant speed blower and your 2zones ctrller :
> 
> Look into a bypass damper that open when pressure is too high. So this will prevent your blower from working too hard by reducing the static pressure. This will allow the air to come back into the furnace, allowing enough air to go through the coil in your furnace. Thus preventing freezing of your coil. Coil needs airflow. The air coming out of your vent will become colder and colder as it cool (because cool air is coming back in the furnace) your room until your room reach its correct temp.
> 
> À bypass damper is installed between the supply(output) of the furnace and its return(input) . The further from the furnace as it can be.
> 
> With a constant pressure variable speed blower, you run a risk to have insufficient air flow. Even with a bypass damper. You would need a multi stage compressor I think.
> 
> 
> Here's some reading for you.
> 
> https://www.pvhvac.com/blog/got-hvac-zones-you-might-need-a-bypass-damper-or-not
> 
> -Matt





HT Geek said:


> @*niccolo*,
> 
> Good point above from @*warwwolf7*. I'd forgotten about that strategy. As he said, it has the advantage of cooling/heating faster because the return air gets closer to the ideal temp as it is running. You should be mindful of how close the bypass duct is to the blower. Either way, there are different ways to solve the problem.
> 
> As far as a dead vent is concerned, how large is that adjacent storage area? And how large will your HT room be? (3-dimenion ballpark measurements, pls)



Home theater room is ~14x18x9 ft. Adjacent storage closet is maybe 8x10x9 ft.


----------



## HT Geek

niccolo said:


> Home theater room is ~14x18x9 ft. Adjacent storage closet is maybe 8x10x9 ft.



That's plenty big (for a dead vent space). Big enough you might be able to construct both a supply side and a return side (not ideal that close together, but potentially an option). Next question is how would you feel about venting in/out of your home office? 

It would be ideal if you were to vent out into the open 2-story space. That's presuming you could snake some flex duct sufficiently, and use a duct muffler and possibly an in-line fan. Then in the small closet, same thing with optional in-line fan. 

I'd recommend installing in-line fans (perhaps variable speed) so you can control airflow directly.


----------



## niccolo

HT Geek said:


> That's plenty big (for a dead vent space). Big enough you might be able to construct both a supply side and a return side (not ideal that close together, but potentially an option). Next question is how would you feel about venting in/out of your home office?
> 
> It would be ideal if you were to vent out into the open 2-story space. That's presuming you could snake some flex duct sufficiently, and use a duct muffler and possibly an in-line fan. Then in the small closet, same thing with optional in-line fan.
> 
> I'd recommend installing in-line fans (perhaps variable speed) so you can control airflow directly.



There's a spacious unfinished (including no floor) attic space right above the home theater room, with small vents to the outdoors, and in our temperate climate it's usually cool up there, so I suppose that's another place for venting (both to dump and/or to pull air). The furnace is up there and the interior components of the air conditioner and obviously the zone controller.



There's plenty of space in the attic to snake flex duct that terminates in the open 2-story space, if that were desirable. It sounds to me like you're suggesting using both the storage room and the open space, maybe one from which to pull air and one to dump air?


I guess my big question is if I'm investing a lot in moving air around, at what point does it make more sense to install a dedicated mini-split for the room instead?


----------



## HT Geek

niccolo said:


> There's a spacious unfinished (including no floor) attic space right above the home theater room, with small vents to the outdoors, and in our temperate climate it's usually cool up there, so I suppose that's another place for venting (both to dump and/or to pull air). The furnace is up there and the interior components of the air conditioner and obviously the zone controller.


Normally, I would advise you that venting into the attic is a bad idea. However, the main reason for that is if there is ANY possibility of the ambient air temperature dropping near freezing. Most climates in the U.S., that is a concern, Parts of California may be the only exception. Even Florida is not immune to unusual freezing weather. Now, all that said, I still won't recommend the practice.

There are other potential issues as well. Attics are dusty and dirty places. It may violate your local building code. etc.

And another negative is you'll make your HVAC work harder. HVAC systems expect to get conditioned air pulled back into the unit via return vents. The design is partly to keep air pressure normalized and partly because sucking back in the already conditioned air means the HVAC works more efficiently. The air in your home gets cooler/warmer faster. Otherwise, it's akin to driving down the road with your car windows open in the summer with your A/C blasting. You won't get as effective cooling.

Realizing your situation is different and unusual compared with what the HVAC designers had in mind, it could still work OK with careful planning, but I need to lay out the caveats. Plus you'd still need to suck fresh air in from somewhere (probably outdoors if you were dumping into attic or outdoors).



> There's plenty of space in the attic to snake flex duct that terminates in the open 2-story space, if that were desirable.


Good. That should be your return dead vent. Snaking flex duct can cause other problems if not handled well. You don't want to restrict the flow too much. Sharp turns are bad. Gradual bends over long runs are ideal. Something in between is what most people end up with. A longer run with some 90 degree bends is usually a good compromise if you have the space (sounds like you do). Space the bends out a bit and your flow should be fine. If flow is a problem, then add a duct fan (as far away from the HT room vent as practical).



> It sounds to me like you're suggesting using both the storage room and the open space, maybe one from which to pull air and one to dump air?


Yes. You should be able to structure it so there's still room for actual storage in the existing storage room and/or use it for HT equipment, etc.



> I guess my big question is if I'm investing a lot in moving air around, at what point does it make more sense to install a dedicated mini-split for the room instead?


Depends on your priorities. It's kind of watermelon vs. seedless watermelon. One is more work and less $; the other is less work but more $. A dead vent can also be totally silent. You could experiment with dead vents using no in-line fans but using duct mufflers for example. I would not recommend it because having a fan encourages air exchange in the room, which is a good thing. At the very least, put a fan in the supply side.

Two dead vents will be cheaper. You're going to have to deal with framing anyway. A mini-split needs the inside and the outside portion. Would you use a wall mount inside? Vented system?

Your biggest cost on a dead vent setup will likely be the in-line duct fan if used. Strongly suggest variable speed and figuring out a way to manage it remotely. That could be a wall switch in your home office if you want a simple but elegant solution. Or get fancy and use wireless relays, etc. You will need some basic understanding of motor electronics unless the fan you purchase has a built-in remote capability to attenuate the speed. Otherwise you need a certain type of voltage adjuster. For example, you cannot use a wall dimmer. You'll burn out either the dimmer or the fan.

Hope that all helps a bit. 

Bottom line is it's cost vs. time, and to some extent what you can do with a system in the future. You can get a mini-split which could be expanded in the future if desired. And don't forget maintenance. Dead vents should have zero, but make sure you can access any in-line fans in case something goes wrong with them.


----------



## FarriorMVP

I'm hoping that someone here can help me find the sweet spot for sound isolation given my space and goals. Here's where I'm at so far:

* I'm about to start a project to finish my basement and put in a home theater/media room as the focal point.
* The basement is completely unfinished now, so I have access to everything, but the house is 110 years old and sound seems to travel well inside the home.
* My sound isolation goal is to be able to listen to the system reasonably loud without waking the wife and kids, but I'm not trying to eliminate all noise as a goal.
* TV area is about 13' x 13' (see diagram)
* I have a quote from a contractor with the following approach:
- Drywall on resilient channels
- 1/2" Homasote on ceiling below joists (TV area only)
- Spray foam in between joists (TV area only)
- Roxul sound guard in the walls (TV area only)

My concern is that there's a fair amount of focus/money going into the TV area only and sound bleed to the other parts of the basement will make that a waste of resources. I also doubt the Roxul in the walls is an efficient use of money as the basement is fully subterranean and wouldn’t likely influence the sound levels 1 and 2 floors above as much as treating the ceiling.

An architect friend of mine suggested using Roxul batt in the ceilings for the entire finished space and scrapping some of the foam and wall treatments. 

So, I’m looking for advice. Should I scrap some of this? Add the same approach to the rest of the basement (with added cost)? Maybe pick 1 approach and spread it over wider areas as opposed to focused approach just in tv area?



Thanks!


----------



## HT Geek

FarriorMVP said:


> I'm hoping that someone here can help me find the sweet spot for sound isolation given my space and goals. Here's where I'm at so far:
> 
> * I'm about to start a project to finish my basement and put in a home theater/media room as the focal point.
> * The basement is completely unfinished now, so I have access to everything, but the house is 110 years old and sound seems to travel well inside the home.
> * My sound isolation goal is to be able to listen to the system reasonably loud without waking the wife and kids, but I'm not trying to eliminate all noise as a goal.
> * TV area is about 13' x 13' (see diagram)
> * I have a quote from a contractor with the following approach:
> - Drywall on resilient channels
> - 1/2" Homasote on ceiling below joists (TV area only)
> - Spray foam in between joists (TV area only)
> - Roxul sound guard in the walls (TV area only)
> 
> My concern is that there's a fair amount of focus/money going into the TV area only and sound bleed to the other parts of the basement will make that a waste of resources.


Inclined to agree in general with your statement.



> I also doubt the Roxul in the walls is an efficient use of money as the basement is fully subterranean and wouldn’t likely influence the sound levels 1 and 2 floors above as much as treating the ceiling.


Mmm..... depends. It may be helpful. It certainly won't hurt, provided it's not packed tightly.



> An architect friend of mine suggested using Roxul batt in the ceilings for the entire finished space and scrapping some of the foam and wall treatments.


Depends on your goals and why you started out with the plan above. However, again generally speaking... I am inclined to disagree with your friend. More on that after you answer questions below.



> So, I’m looking for advice. Should I scrap some of this? Add the same approach to the rest of the basement (with added cost)? Maybe pick 1 approach and spread it over wider areas as opposed to focused approach just in tv area?


 My primary concern is you've got the whole back of the room wide open into the bar area. So, right off the bat this is not a dedicated room per se. Therefore, let's backup a bit. Ideally, which portion of your home would you like to insulate (re: sound) from the remainder of the home? Perhaps the whole finished portion of the basement, since it all seems to be connected?


----------



## HT Geek

btw, what are your plans for isolating the sump pump area? Do you have a plan yet?


----------



## niccolo

FarriorMVP said:


> I'm hoping that someone here can help me find the sweet spot for sound isolation given my space and goals. Here's where I'm at so far:
> 
> * I'm about to start a project to finish my basement and put in a home theater/media room as the focal point.
> * The basement is completely unfinished now, so I have access to everything, but the house is 110 years old and sound seems to travel well inside the home.
> * My sound isolation goal is to be able to listen to the system reasonably loud without waking the wife and kids, but I'm not trying to eliminate all noise as a goal.
> * TV area is about 13' x 13' (see diagram)
> * I have a quote from a contractor with the following approach:
> - Drywall on resilient channels
> - 1/2" Homasote on ceiling below joists (TV area only)
> - Spray foam in between joists (TV area only)
> - Roxul sound guard in the walls (TV area only)
> 
> My concern is that there's a fair amount of focus/money going into the TV area only and sound bleed to the other parts of the basement will make that a waste of resources. I also doubt the Roxul in the walls is an efficient use of money as the basement is fully subterranean and wouldn’t likely influence the sound levels 1 and 2 floors above as much as treating the ceiling.
> 
> An architect friend of mine suggested using Roxul batt in the ceilings for the entire finished space and scrapping some of the foam and wall treatments.
> 
> So, I’m looking for advice. Should I scrap some of this? Add the same approach to the rest of the basement (with added cost)? Maybe pick 1 approach and spread it over wider areas as opposed to focused approach just in tv area?
> 
> 
> 
> Thanks!



The class four aspects of soundproofing--which work in concert with each other--are the way to think about this (and all other soundproofing projects). https://www.soundproofingcompany.com/soundproofing_101/4-elements-of-soundproofing


----------



## eighteenbit

*Some soundproofing guidance.*

Greetings kind people,

first of all I would like to apologize for hijacking the thread, if this is not the right place for this question, please redirect me to a better place for these kinds of questions and will delete it from here.

So for the first time in my life I have a place of my own. And since I've had really bad experiences with neighbors that are too noisy or ones that can't tolerate the slightest sound.
I've began gathering info on how soundproof the living rood and bedroom of my apartment. 

Since the principle for both rooms is the same I will only talk about the living room, my plan is as follows: 

- Ceiling is a 160mm thick reinforced concrete slab, I plan to do a decoupled suspended ceiling with 50mm of mineral wool for insulation above the two 12,5mm thick drywall sheets that are going to have Green Glue sandwiched between them. (After much reading I decided that this is the best way to go even thought Green Glue is really stretching my budget, but i did not find anything that would have the same effect, I did look into Silentboard (and other sound dampening drywalls), other Green glue alternatives such as QuietGlue or even carpet glue.)

- Second phase would be to do the same procedure with the other open walls in the room. (This will probably be done next year since Green glue is quite pricey especially in Bulgaria where I need to order it through another European country that has a distributor and they probably order it from the US, and as much as I value it soundproofing isn't priority number one when you move into a new home and you don't have a bathroom, bed or fridge.)

- This will leave the kitchen cabinet section which I will try to decouple as best I can from the walls and it will carry a lot of mass on it's own so It should stop a good deal of sound waves. 
Might add some mass loaded vinyl just for acoustics (to reduce eventual rattling). 

The idea for the walls and kitchen cabinets is to battle flanking sound waves, but my main concern is this, there are two huge 2,06 x 2,40 meter windows and a separate balcony door (this makes up a little under half of the surface of all of the walls in the 20m2 room). Now in my country they mount these PVC extruded window frames with double glazed windows with expandable polyurethane foam and a few long screws that go into a plastic anchor inserted into the brick wall. So the surface of these windows will gather a lot of vibrations if i play music, I could't find anywhere someone talking about how much sound do these kinds of windows actually transmit. 

Is there any point of me going through all of the trouble of soundproofing the ceiling and eventually walls if the sound flanks through the windows and the neighbors pay me a visit every time I play some music?

I am attaching a layout of the room for reference, I've market with green the walls that I plan to do drywall/green glue on when I'm done with the more essential parts of the apartment. Basically for the beginning I'm only doing the ceiling because after the kitchen cabinets get in it will be harder to do. 

Thank you and any advise will be helpful and much appreciated!


----------



## FarriorMVP

HT Geek said:


> Inclined to agree in general with your statement.
> 
> Mmm..... depends. It may be helpful. It certainly won't hurt, provided it's not packed tightly.
> 
> Depends on your goals and why you started out with the plan above. However, again generally speaking... I am inclined to disagree with your friend. More on that after you answer questions below.
> 
> My primary concern is you've got the whole back of the room wide open into the bar area. So, right off the bat this is not a dedicated room per se. Therefore, let's backup a bit. Ideally, which portion of your home would you like to insulate (re: sound) from the remainder of the home? Perhaps the whole finished portion of the basement, since it all seems to be connected?


Thanks for the quick reply. At least I'm not crazy with some of my concerns. As to your question on goals and how I got that plan above, my goal is to be able to have a movie on at night without waking up the rest of the house. I would like to insulate the sound from the basement from the rest of the house, but especially from traveling up 2 floors to where the bedrooms are. If that means I need to insulate and treat the entire finished basement, then I would like to make sure the approach is efficient to keep costs under control.

From a de-coupling perspective, is the resilient channels for the drywall a form of that?

To address the "mass" concern, I'm not sure whether spray foam, homasote, thicker drywall, or Roxul (or a combo) would be the best approach.

As for the sump pump, I was thinking of putting a solid core door there but haven't given much thought to the sound isolation approach for that area. Good question. 

Should I rip the whole plan up and go with a couple layers of drywall and green glue? 

Again, it doesn't need to be perfect from a sound isolation perspective. Just don't want to spend a lot of money on equipment and finishing the basement only to get yelled at by my wife the first time I throw a movie on.

One other question - I'm going to put 4 Atmos speakers in the ceiling as well. Do you recommend backer boxes in all scenarios? I understand that treating the whole ceiling and then putting 4 large holes in it isn't the best approach without some mitigation.


----------



## HT Geek

FarriorMVP said:


> I'm hoping that someone here can help me find the sweet spot for sound isolation given my space and goals. Here's where I'm at so far:
> 
> * I'm about to start a project to finish my basement and put in a home theater/media room as the focal point.
> * The basement is completely unfinished now, so I have access to everything, but the house is 110 years old and sound seems to travel well inside the home.
> * My sound isolation goal is to be able to listen to the system reasonably loud without waking the wife and kids, but I'm not trying to eliminate all noise as a goal.
> * TV area is about 13' x 13' (see diagram)
> * I have a quote from a contractor with the following approach:
> - Drywall on resilient channels
> - 1/2" Homasote on ceiling below joists (TV area only)
> - Spray foam in between joists (TV area only)
> - Roxul sound guard in the walls (TV area only)





FarriorMVP said:


> Thanks for the quick reply. At least I'm not crazy with some of my concerns. As to your question on goals and how I got that plan above, my goal is to be able to have a movie on at night without waking up the rest of the house. I would like to insulate the sound from the basement from the rest of the house, but especially from traveling up 2 floors to where the bedrooms are. If that means I need to insulate and treat the entire finished basement, then I would like to make sure the approach is efficient to keep costs under control.



Alright. This is what I was looking for. 

Now... let's talk about your home's architecture since you can see it in the basement right now. What you want to do - in order to accomplish your goal - is isolate your basement. There are three primary areas you should be concerned with:


 Basement wall
Basement ceiling
Stairwell / Access route between basement and remainder of home
I'll break them down for you in a moment. First, your other questions....



> From a de-coupling perspective, is the resilient channels for the drywall a form of that?


Yes. However, you might consider RC to be a "poor man's clips & channel," meaning RC is an inferior form of decoupling. 

RC gets a bad rap with some folks on AVS, however I've reviewed a lot of lab test results and would argue it's not _bad_. But there are _better _alternatives. RC is actually very good at high frequencies, but it's mediocre at blocking LFE. And to get the full benefits of RC you need to couple it with double-drywall and Green Glue to max your LFE benefits (though they'll still be mediocre compared with other solutions).

I suspect RC gets its poor reputation from the fact there are different versions of it. If you use RC, it's important to be sure you are using the proper gauge and design.



> To address the "mass" concern, I'm not sure whether spray foam, homasote, thicker drywall, or Roxul (or a combo) would be the best approach.


The only one of those choices that makes a difference for the 'mass' part of the equation is drywall.



> As for the sump pump, I was thinking of putting a solid core door there but haven't given much thought to the sound isolation approach for that area. Good question.
> 
> Should I rip the whole plan up and go with a couple layers of drywall and green glue?


Well, you've got three challenges there, actually.

1) You need to either treat the sump pump "closet" like it is the remainder of the home (i.e. you want it outside your sound-isolated "shell" which will be your new basement); or it's part of your 'shell' per se but you need to isolate it somewhat from the remainder of the basement.

2) Noise. Nothing worse than "clu-clunk-brrrr.... clu-clunk" while in the middle of a quiet part in a movie. 

3) You need to be able to access the pump.

Given those constraints, I'm thinking you should build your sound isolation around it and consider the sump pump closet to be part of the area you want to keep sound out of from your basement, as if it was a bedroom or something like that. This approach should help you solve issues 1 and 2.

To solve issue 3, of course you'll need a door of some sort. I agree solid core is ideal. However, I don't believe a normal solid door on its own will likely be sufficient. If you de-couple the walls to the closet properly (more on that below), then next you'll want more mass. As much as you can reasonably apply.

One option would be a double thick door. Glue and screw one identical door to another. Get yourself some Big Ass Hinges. Consider installing an automatic door bottom as well (installed on the opening side of the door).



> Again, it doesn't need to be perfect from a sound isolation perspective. Just don't want to spend a lot of money on equipment and finishing the basement only to get yelled at by my wife the first time I throw a movie on.
> 
> One other question - I'm going to put 4 Atmos speakers in the ceiling as well. Do you recommend backer boxes in all scenarios? I understand that treating the whole ceiling and then putting 4 large holes in it isn't the best approach without some mitigation.


Yes. Backer boxes for Atmos speakers should be considered a must-have. While we're on the subject, any can lights (recessed lights) should have backer boxes as well.

Now, let's talk about the walls and ceiling.

*Homasote, Spray Foam, Roxul*
You mentioned all of these above. 

*Homasote *is basically fiberboard. It's a building material primarily geared toward being "green" and fire resistant. More common in commercial builds vs. residential, but sometimes used in residential building construction. It's sound-proofing benefits are questionable. I suspect the reason that's mentioned in product literature is because it's not uncommon to see it in apartment buildings and row homes. If you're a builder, it's appealing as a multi-purpose product that is also the same thickness as 3/4" or 1-1/4" plywood or OSB. The fire resistance is the biggest plus for builders, followed by R-value of insulation.

For a proper home theater building, it's really not worth considering unless you have a situation where you are very space constrained AND need an insulator (for heat) that is greater than the R value of drywall, which I don't believe is the case for you. Otherwise, use another layer of drywall instead (which will provide you more mass for less $).

Contractors who don't specialize in sound proofing might recommend it because they think it has some magic sound proofing properties (based on product marketing literature).

*Spray Foam*
Will do nothing for you from a sound proofing perspective. *Might* be helpful to plug certain types of gaps, but there are superior alternatives. I would avoid it UNLESS you have a need from an insulation perspective. It's no good for sound proofing.

*Roxul*
Possibly useful. Discussed below re: insulation.

Now, back to your 3 problem areas:



Basement walls
Basement ceiling
Stairwell / Access route between basement and remainder of home

*Walls*
The main concern here is you should address all of your walls. Since your space is open, sound is going to bounce around. Sound proofing your ceiling is going to be more important than the walls, but you should not ignore the walls. 

There are two "best" options: 1) clips and channel or 2) wood studs with an air gap between them and the basement foundation walls. Do you have existing studs in the basement, or is your home resting on stone foundation? You mentioned it's 110 yrs old IIRC, so I am betting you don't have existing studs in there holding up the remainder of the home. That would be unusual.

Point is... if your stud walls in the basement will not be load bearing, that is helpful. Since you will need to build stud walls anyway, just leave about a 1" gap between them and the existing foundation walls. Adjust for uneven wall surfaces if necessary. Make sure there is an air gap. No touchy.

Plan on either 2x drywall sheets on the walls OR 2x drywall + Green Glue in between if you are willing to spend the $ and get minor but noticeable difference in improvement. Or use 3x drywall sheets if you like (with or without Green Glue). Only the outer layer needs mud and finishing. You should also apply sealant between juxtaposed drywall, for the interior drywall layers (i.e. not the layer being mudded and finished). Don't use mud on the interior drywall layers. The caulk is flexible (that's what makes it "acoustic" caulk) and will dry as a rubbery compound.

Personally, I'd say you could skip the Green Glue for your walls given your circumstances. It wouldn't hurt, but I'm not convinced the benefit is worth the cost. I would be inclined to use it between ceiling drywall layers though. That's all presuming your basement stud walls do not make physical contact with your foundation walls or the floor joists of the level above.

* Ceiling*
2-pronged approach. First, you're going to have gaps and crevices in your basement ceiling. Those should be addressed. You want to seal them with something appropriate, such as a suitable caulk/sealant. For larger cracks (> 1/4" or so), shove some backer rod in there - is a cellulose type of product, in a tube shape. Apply the caulk over it. The backer rod will "back" or support the caulk and allow you to seal the gap properly.

The same company that makes Green Glue also makes a suitable sealant. However, I recommend OSI SC175. It is just as effective and a fraction of the cost. It's also more readily available. Both apply easily. If you will DIY this part, get a 28/29 ounce pneumatic caulk gun or air-compressor powered caulk gun if you need an excuse to buy an air tool. Your wrists will thank me later. LoL. 

Now, with the gaps and crevices between floors dealt with, it's time to focus on the ceiling of your basement. There are three good approaches for your situation: 

1) construct a floating ceiling on top of your new stud walls. I'd have to revisit your diagram to see what the spans would be. This works well if you can use 2x6 or perhaps 2x8 joists. Bigger than that and they might take up too much headroom. You need a gap between the top of your ceiling joists and bottom of the floor joists above. If there are existing pipes, HVAC, etc. lines, they may dictate which way you run the floating ceiling joists to accommodate them, or may require re-routing. You might need to get creative, depending on circumstances.

2) 2nd option is to use clips & channel attached to the bottom of the floor joists from the floor above.

3) 3rd option would be staggered joists. Basically, you attach new joists to the existing ones, which lowers the ceiling. Your ceiling drywall attaches to them. I like this approach the least and don't recommend it. Your ceiling is coupled to the floor above. It really doesn't help much in your case. I almost didn't mention it at all.

Regardless of approach, plan to use 2x drywall with or without Green Glue. Use 3x drywall if you want even more effect. 

*Stairway/Entrance*
This is always a sore point. You need a solid core door on at least one opening (basement) or the other (first floor). Ideally, install a door at both positions. Solid core. You can leave the basement door open when not using as an HT room or not blaring the volume. Add an automatic door bottom to one door or the other if you think you need more blockage after you've got solid core doors installed on either end of the stairs.

*Insulation*
Plan to apply insulation in the walls, between studs, and in the ceiling between joists. "Pink fluffy" (fiberglass) is cheapest. Roxul is an option but more expensive with virtually identical performance to pink fluffy. The benes of Roxul are primarily moisture and mold resistance. If you have a concern about moisture in the walls or ceiling, use Roxul. More likely to be of value in the walls.


----------



## Ladeback

FarriorMVP said:


> Thanks for the quick reply. At least I'm not crazy with some of my concerns. As to your question on goals and how I got that plan above, my goal is to be able to have a movie on at night without waking up the rest of the house. I would like to insulate the sound from the basement from the rest of the house, but especially from traveling up 2 floors to where the bedrooms are. If that means I need to insulate and treat the entire finished basement, then I would like to make sure the approach is efficient to keep costs under control.
> 
> From a de-coupling perspective, is the resilient channels for the drywall a form of that?
> 
> To address the "mass" concern, I'm not sure whether spray foam, homasote, thicker drywall, or Roxul (or a combo) would be the best approach.
> 
> As for the sump pump, I was thinking of putting a solid core door there but haven't given much thought to the sound isolation approach for that area. Good question.
> 
> Should I rip the whole plan up and go with a couple layers of drywall and green glue?
> 
> Again, it doesn't need to be perfect from a sound isolation perspective. Just don't want to spend a lot of money on equipment and finishing the basement only to get yelled at by my wife the first time I throw a movie on.
> 
> One other question - I'm going to put 4 Atmos speakers in the ceiling as well. Do you recommend backer boxes in all scenarios? I understand that treating the whole ceiling and then putting 4 large holes in it isn't the best approach without some mitigation.


What room is above the theater, bedrooms, living room kitchen? My theater I am building is below my living room/kitchen eating area. I have it operational, but not complete. You can here sound coming from above when I am watching football or a movie, but I usually don't crank it when my wife is is above watching TV. Now I will hear my kid and dog running around and the sub woofer from our living room below. Have you tried to play music or something in the basement to see how loud it is upstairs? If you like a lot of bass it will take a lot to slow it down.

I have decided to try to get my room done and do as much as I can with just insulation and maybe double layers of drywall, my wife doesn't complain about me playing anything to loud so I don't see the reason go nuts with soundproofing.


----------



## HT Geek

eighteenbit said:


> - Ceiling is a 160mm thick reinforced concrete slab, I plan to do a decoupled suspended ceiling with 50mm of mineral wool for insulation above the two 12,5mm thick drywall sheets that are going to have Green Glue sandwiched between them. (After much reading I decided that this is the best way to go even thought Green Glue is really stretching my budget, but i did not find anything that would have the same effect, I did look into Silentboard (and other sound dampening drywalls), other Green glue alternatives such as QuietGlue or even carpet glue.)


 Agreed on Green Glue. It's either use it or don't. With the exception of substituting QuietRock, the alternatives you mentioned are not worthwhile.

What are your plans for suspension method (of the new drywall ceiling)?



> - This will leave the kitchen cabinet section which I will try to decouple as best I can from the walls and it will carry a lot of mass on it's own so It should stop a good deal of sound waves.
> Might add some mass loaded vinyl just for acoustics (to reduce eventual rattling).


This has been discussed before on AVS. You may want to try a search to find the thread(s).

Why do you wish to de-couple your cabinets? It's a lot of work. Speaking from experience having removed cabinets, it's very likely some damage will result in the process. So, if you insist on doing this, be prepared for the possibility of cabinet repairs. Primarily where they attach to the walls. It's not uncommon for the cheap particle board normally used on the back of cabinets to break during removal.



> The idea for the walls and kitchen cabinets is to battle flanking sound waves, but my main concern is this, there are two huge 2,06 x 2,40 meter windows and a separate balcony door (this makes up a little under half of the surface of all of the walls in the 20m2 room). Now in my country they mount these PVC extruded window frames with double glazed windows with expandable polyurethane foam and a few long screws that go into a plastic anchor inserted into the brick wall. So the surface of these windows will gather a lot of vibrations if i play music, I could't find anywhere someone talking about how much sound do these kinds of windows actually transmit.
> 
> Is there any point of me going through all of the trouble of soundproofing the ceiling and eventually walls if the sound flanks through the windows and the neighbors pay me a visit every time I play some music?


Have you considered using thick and heavy, backed curtains? You may want something to block out the light anyway. You could also build a removable window plug. That should be documented on AVS as well; likely in more than one thread.


----------



## ssdesigner

I do apologize if this has been brought up but, 104 pages man...oof.

Has anyone used a neoprene product like this in combination with hat-channel instead of clips?

https://rubbersheetwarehouse.com/pr...MI6LXho7GR4gIVCNbACh2_DAM_EAQYCiABEgI_X_D_BwE


----------



## lovingdvd

BTW guys - a few weeks ago I asked here what a good way was to get some isolation for my washing machine. I wound up just doing something simple - Lowes sells these little rubberized block cubes that are about 1.5" specifically for this purpose. I set the legs of the washing machine onto these cubes. Seems to work good enough. Probably the results would be even better if I had properly isolated the floor and done some other things, but it wasn't a major issue to begin with so I didn't want to go over-engineer a solution for it.


----------



## HT Geek

ssdesigner said:


> I do apologize if this has been brought up but, 104 pages man...oof.
> 
> Has anyone used a neoprene product like this in combination with hat-channel instead of clips?
> 
> https://rubbersheetwarehouse.com/pr...MI6LXho7GR4gIVCNbACh2_DAM_EAQYCiABEgI_X_D_BwE


I'm not aware of anyone who's tried that combo, but it's possible. You'd have to spend some time experimenting with search queries on AVS.

But perhaps more importantly, I'm not aware of any lab tests with that combo. 

How would you propose to use the material you mentioned in conjunction with hat channel? How would all the parts be positioned?


----------



## warwwolf7

ssdesigner said:


> I do apologize if this has been brought up but, 104 pages man...oof.
> 
> Has anyone used a neoprene product like this in combination with hat-channel instead of clips?
> 
> https://rubbersheetwarehouse.com/pr...MI6LXho7GR4gIVCNbACh2_DAM_EAQYCiABEgI_X_D_BwE


Well... To use that under the clip holding the channel?
I'm actually really interested in this! This could mean I could convert my ib-1 into a more efficient one.

If no one has anything to say about this, I'll make sur to make a test to see how well it react. I already have some to put under my doublewall to découple from the concrete floor 

-Matt


----------



## ssdesigner

HT Geek said:


> ssdesigner said:
> 
> 
> 
> I do apologize if this has been brought up but, 104 pages man...oof.
> 
> Has anyone used a neoprene product like this in combination with hat-channel instead of clips?
> 
> https://rubbersheetwarehouse.com/pr...MI6LXho7GR4gIVCNbACh2_DAM_EAQYCiABEgI_X_D_BwE
> 
> 
> 
> I'm not aware of anyone who's tried that combo, but it's possible. You'd have to spend some time experimenting with search queries on AVS.
> 
> But perhaps more importantly, I'm not aware of any lab tests with that combo.
> 
> How would you propose to use the material you mentioned in conjunction with hat channel? How would all the parts be positioned?
Click to expand...

I am planning to eliminate the clips entirely. They seem like an overpriced way to gain another 1/2” between studs and drywall. In the end it’s still drywall/metal/rubber. This rubber on a roll has the same harness as the pads on the clips and is also rated for sound vibrations.


----------



## HT Geek

ssdesigner said:


> I am planning to eliminate the clips entirely. They seem like an overpriced way to gain another 1/2” between studs and drywall. In the end it’s still drywall/metal/rubber. This rubber on a roll has the same harness as the pads on the clips and is also rated for sound vibrations.


Ok. I follow your logic. However, I'm not sure it's truly apples to apples. 

What I see missing with your suggestion is the structural support the clips provide. They keep the screw straight and provide a tunnel, per se; i.e. the screw travels through between the drywall and stud, through a narrow cavity. The design provides some measure of additional rigidity and weight reinforcement. Furthermore, the same portion of the design I'm referring to also - and perhaps more importantly - prevents the rubber from being over-compressed. 

Compressing the rubber too much could lead to short-circuiting your design. Plus, your walls will vibrate. The goal w/the clips and channel (or similar methods) is in part to allow that flexing or vibration to occur in such a fashion that the majority of the vibrations are not transferred to the structural studs of the building.

I suppose the bottom line is you could do it, but you'd be in uncharted waters AFAIK; versus going with a concept where you can be assured of the relative gain so long as you execute the plan correctly.

And btw, I don't see any mention of a harness. The product at the link you provided says in part, "Finish: Smooth Both Sides." The website you linked does indicate it's a hard rubber. It would be interesting to see how the 1" thick version would do in a lab.

I've handled a few different clip designs. Some, such as the Resilmount A237R have a rather hard rubber. Others are difficult to compress but the rubber has a bit more "squish" to it. Either way, I'm still thinking a lab test would be ideal. I don't know enough about rubber compounds to know if the one you're considering is more or less or equally effective compared to other compounds.


The diagram below gives an idea of what I was referring to with regards to the path of the screw being directed by the clip design. It is not meant as an installation guide.


----------



## ssdesigner

I get that there is more rubber area to help suppress the vibrations, but I’m going to be fine with whatever small difference that would make. The clips are just a bit more than I want to put into simply trying to avoid hearing the furnace a couple of rooms away. It’s just the wife and I in the house and we really don’t need everything air tight.


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## HT Geek

warwwolf7 said:


> I already have some to put under my doublewall to découple from the concrete floor



FYI, the recommended / best practice approach to de-coupling wall mounted drywall from the floor is with an a small air gap. Then caulk the gap with acoustic caulk.


----------



## HT Geek

ssdesigner said:


> I get that there is more rubber area to help suppress the vibrations, but I’m going to be fine with whatever small difference that would make. The clips are just a bit more than I want to put into simply trying to avoid hearing the furnace a couple of rooms away. It’s just the wife and I in the house and we really don’t need everything air tight.



I understand your thoughts on cost savings and being practical with regards to whether or not anyone else is going to be bothered by noise emanating from your HT room, but just to be clear on a couple of points....



It's not just about keeping sound from the HT room from spreading, it's also about preventing unwanted sounds from penetrating into your HT room. This is normally a concern during quiet scenes in a movie or music, and if there is any possibility of outside noise.
The clips don't necessarily have more rubber. That would depend on which thickness of the rubber product you chose. For instance, I noticed you can purchase up to 1" thick of the rubber product. That would be thicker than the rubber in any of the clips I've seen on the market. The point I was making is the clip designs facilitate some rigidity in the angle and path of the screw that goes through drywall, rubber, channel, and into a stud. The path the screw takes is also bounded by metal, which helps resist potentially over-torquing the screws. In other words, the clips provide boundaries that help ensure the rubber is not compressed too much, which could create a de-coupling short-circuit while at the same time ensuring the screw remains perpendicular to the wall during insertion.
 Just some things to take into consideration. They may or may not be a concern for you, personally. This whole business is all about trade-offs.


----------



## warwwolf7

HT Geek said:


> FYI, the recommended / best practice approach to de-coupling wall mounted drywall from the floor is with an a small air gap. Then caulk the gap with acoustic caulk.


I will have the infamous 1/4" filled with acoustic sealant. But since the drywall on that double wall won't be on clips and channel, because the gain for a double wall to add clip and channel is really minimal. I've been thinking a lot about on how to have a good way to soundproof the door. And really the best way is a double door. So my doublewall will have 2 doors facing each other. Some of the weak points in a doorway is the doorframe in itself. You can't really decouple the doorframe from the wall itself. Then, the handle which means you have to make a hole in the door. So, double wall kinda help on this by decoupling the doors and inserts a airgap between them. I'll use push/pull plate and auto closing system to avoid making a hole in the doors. 
Ok, double wall, drywall straight on the stud, non clips and channel. What If the floor is becoming a flanking path. So I decided that I will decouple the wall from the floor which will decouple the drywall as well because the wall and drywall are somewhat bonded together. I will install neoprene under the wall since it's not a load bearing wall, it won't "over compress" the neoprene. If it does, then it will act like a normal wall And thats it. Wasted 50$. No big deal. I'd prefer not to make a cut in the slab to separate it from the rest of the basement. 

To resume, double door brought me to make a double wall. Made no sense to add clip and channel on a double wall. Decided to add neoprene under the wall to decouple it from the floor.

Ill make some tests when I have time to check the neoprene under the clip and see if my accelerometer gets differents results from using neoprene or not. 

-Matt


----------



## eighteenbit

HT Geek said:


> Agreed on Green Glue. It's either use it or don't. With the exception of substituting QuietRock, the alternatives you mentioned are not worthwhile.
> 
> What are your plans for suspension method (of the new drywall ceiling)?


Thank you for the reply!

Basically I plan on doing what these guys did 
"watch?v=IojUL2fxFKg" I don't have enough posts to post a link, but this is an extension for an youtube video.

Using an acoustic hanger for the main frame and the side guiding channels are basically going to float over a layer of polyurethane foam which is going to separate them from the wall. There's going to be green glue between the drywall sheets, and sealant all around.

I think this should kill a lot of the direct noise, flanking is still a concern, I could consider heavy curtains for the windows. But window plugs, aren't an option there would be no where to store such devices designed for such big windows.


----------



## HT Geek

eighteenbit said:


> Basically I plan on doing what these guys did
> "watch?v=IojUL2fxFKg" I don't have enough posts to post a link, but this is an extension for an youtube video.


I watched the video. Interesting. Reminds me of Resilient Channel, though obviously different. Truly, it's more like attaching crisscrossed metal studs. And looks to me as if a triple leaf is being created. The poly foam won't do much of anything for sound proofing. If you use it, make sure that's acoustic caulk between it and the mounting surface.

Any idea what the product is called? I am skeptical it's worth the effort. Any independent lab test results you know of?


----------



## HT Geek

ssdesigner said:


> I do apologize if this has been brought up but, 104 pages man...oof.
> 
> Has anyone used a neoprene product like this in combination with hat-channel instead of clips?
> 
> https://rubbersheetwarehouse.com/pr...MI6LXho7GR4gIVCNbACh2_DAM_EAQYCiABEgI_X_D_BwE


Circling back on this, over the weekend I found some RSIC DC-04 clips I had in storage and measured the rubber portion of it. 3/4" thick. FYI comparison. 

That said, there are two different designs of that clip (oddly). The ones I have are from PAC International and are the same sold by The Soundproofing Company.


----------



## eighteenbit

HT Geek said:


> I watched the video. Interesting. Reminds me of Resilient Channel, though obviously different. Truly, it's more like attaching crisscrossed metal studs. And looks to me as if a triple leaf is being created. The poly foam won't do much of anything for sound proofing. If you use it, make sure that's acoustic caulk between it and the mounting surface.
> 
> Any idea what the product is called? I am skeptical it's worth the effort. Any independent lab test results you know of?


I'm using these acoustic dampeners to mount the frame to the ceiling, the screw goes through the center into the anchor on the ceiling and the frame is left floating, as the rubber disconnects vibrations going through it to the ceiling (Hopefully). And on the sides the foam is only meant to separate the frame from making direct contact with the walls. I'm planning to fill the gaps on the edges under the foam with sealant as well(the so called acoustic caulk).

The product is some sort of acoustic caulk, no independent lab tests for it(at least on the manufacturers website.


----------



## HT Geek

eighteenbit said:


> I'm using these acoustic dampeners to mount the frame to the ceiling, the screw goes through the center into the anchor on the ceiling and the frame is left floating, as the rubber disconnects vibrations going through it to the ceiling (Hopefully). And on the sides the foam is only meant to separate the frame from making direct contact with the walls. I'm planning to fill the gaps on the edges under the foam with sealant as well(the so called acoustic caulk).
> 
> The product is some sort of acoustic caulk, no independent lab tests for it(at least on the manufacturers website.


Understood. I'll try to elaborate a bit more. Here are my primary concerns:



Metal framing is attached directly to existing drywall
Insulation looks tightly packed between metal frame and drywall it's screwed into
No independent lab test data (that I've seen so far)

The first item on my list above is why I eluded to my belief in the video the installers are creating a "triple leaf." Now, granted I don't know what is beneath the original drywall they are attaching the metal studs to. Presuming it is some sort of framing and not concrete, and presuming there is an existing air gap behind the existing drywall, that may result in a triple leaf effect. Frankly, I'm not sure that it actually does because it's debatable whether or not an air gap is being created during the install of the framing, due to the fact the insulation material seems tightly packed in there (again, I'm speaking based on what I can see in the video since I don't have any other point of reference).

If there isn't a triple leaf (2 connected air gaps), then you'd have this scenario:

_Unknown structural material -> drywall -> insulation -> rubber/metal framing -> drywall x2_

I understand the idea is that there are limited points of contact where the metal framing is attached to the existing structure (unknown material -> drywall). And there is a rubber layer under the metal framing. *I'm still hung up on lack of independent lab analysis (unless someone can point me to one) for this configuration.*


*Conceptually, the idea is doing three (3) things differently from the clips & channel concept*:

1) Support system attachment to structural wall/ceiling studs

Clips & Channel : Direct attachment
Proposed Method: Attached through existing drywall over top of structural studs


2) Metal/Rubber position

Clips & Channel : Studs -> Metal -> Rubber -> Metal -> Rubber -> Drywall
Proposed Method: Studs -> Drywall -> Rubber -> Metal -> Drywall


3) Rubber layers

Clips & Channel : Two (2)*
Proposed Method: One (1)


FWIW, that is how I see it atm. 

Edit: Here is a link to the video FBO others: https://www.youtube.com/watch/?v=IojUL2fxFKg

Edit 2: Added footnote.

* Bit of an oversimplification on my part, as it depends on the clip. Technically, my original statement is not always true, but it is sometimes. Depends on the clip used.


----------



## HT Geek

@eighteenbit:

I performed a bit of quick research. It appears the product you've referenced uses Sylodyn, which is a registered trademark brand name for a synthetic material designed to absorb vibration, similar to Sorbothane, though the former has more of a cellular characteristic (physically) from what I've been able to gather.

I did find one sound attenuation chart. However, while it looks nice as marketing material on a web page, it's not technically informative or authoritative.

http://www.acoustic-group.com/products/sound_insulation/vibroflex_ks/

There is an interesting product data sheet found here

However, again it's not informative in a manner that folks on this forum are interested in. To be able to compare apples-to-apples, one needs lab test results from the same lab, with a similar setup so that different techniques can be compared properly. Unfortunately, that information is missing the vast majority of the time (such as now). This makes it impossible to accurately compare solutions to one another.










Taking a closer look, this is more like clips than I originally thought. It's difficult to tell from the video. Here is a photo of Vibroflex-KS from the website of the company Acoustic Group, who made the video you referenced.










As you can see, it is more alike to clips - in some respects - than I originally thought. The design is, of course, still different. However, it's a very interesting design. I would love to see some real lab tests with some products using this material. Even a product using rubber with the design of these brackets would be very interesting to compare against other methods. Unfortunately, the chart above is meaningless as it is presented (lack of detailed contextual information).


----------



## doveman

For my window plugs I was thinking of using clips and channel to isolate the new sill from the existing one and thus the structural wall but I realise that won't work now as the shortest clips (A237) and channel would come to 34.9mm and that doesn't leave enough space for the new sill, which will have to be fairly thick.

So what other method that won't require as much height could I use to provide a decent amount of dampening, if not proper isolation, between the existing and new sills, so that once I've soundproofed the wall and plugged the window, the sill isn't the weak point that transmits sound to/from the structure? Assuming I use 18mm ply for my new sill, I could have up to 27mm between the two sills without it obscuring the window pane at all. As the existing sill isn't straight I'll also have to use some spacers or something to make the new sill straight so I'll need to leave room for that.


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## mhutchins

A drawing or pictures would help our understanding.

Mike


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## doveman

Hopefully the attached picture will help.

So for this window I'm dividing it into three sections. The orange verticals are 44x44mm battens for the foam/rockwool plugs to press against. On the left and right of the reveal the foam will just squash against the wall.

I need to fit some wood to the sill and the top of the reveal because a) I'll need to fit the vertical battens into them using either mortise and tenon or dovetail joints, b) I need to isolate the vertical battens from the structural wall and c) the sill is very wonky and curves down quite a bit towards the right so I need to fit a new sill on top to level it out.

Using clips and channel on the sill and the top of the reveal to hold the horizontal battens would be the best way to isolate them from the structural wall but there's not enough space for that, so I need something else I can use between the reveal/sill and the horizontal battens to provide some isolation/dampening and which will also allow me to use something to level out the new sill. Some thin foam/mat (up to 27mm thick) is an option but I'm not sure how much effect that would have.

In order to seal off the existing sill to prevent it transmitting sound from in the room into the structural wall, I'm going to extend it out into the room and support it with legs at each end so that I can join other pieces of wood to it to basically box off the original seal and fill the space with pink fluffy. When I soundproof the wall the radiator will be refitted over the plasterboard so it will move it away from the sill and I'll refit it lower down on the wall if necessary to make room for the boxing.

I see that Rockwool have these Sound Insulation Slabs now but they don't specify the density unlike their RWA45 (45kg/m3), RW3 (60kg/m3) and RW5 (100kg/m3) products, which made me suspicious.
https://www.rockwool.co.uk/product-overview/trade-insulation-range/sound-insulation-slab-en-gb/

So I e-mailed them and they replied:

"The density of our Sound Slab is 35kg/m3, however, Higher density does not always mean a higher acoustic performance, it depends on the frequency of the sound; also, the sound slab is available at 400mm wide whereas the others are all 600mm wide, so if you have floor joists, there would be less wastage with the sound slab."

I dare say there's some truth in the suggestion that higher density may not provide much benefit at some (higher) frequencies but at lower frequencies I'm sure it would, so this seems like an inferior product from a soundproofing point of view, unless you only need to soundproof against mid-high frequencies I guess.

Do you think RWA45 with 45kg/m3 would suffice for window plugs or would you suggest something higher like RW3 or RW5? It seems like the window plugs will always be the weak point whatever I use. This 15mm plasterboard is 940kg/m3 https://www.insulationshop.co/15mm_gyproc_soundbloc_f_high_density_acoustic_board_1200_x_2400mm.html and 14.1kg/m2, so two layers would be 28.2kg/m2. 50mm thick RW5 is 100kg/m3 which I think works out to 5kg/m2 (0.05 * 100), so there'll be far less weight/density between the room and the window/reveal (which is part of the structural wall) than there will be between the room and the rest of the structural wall.


----------



## warwwolf7

doveman said:


> Hopefully the attached picture will help.
> 
> So for this window I'm dividing it into three sections. The orange verticals are 44x44mm battens for the foam/rockwool plugs to press against. On the left and right of the reveal the foam will just squash against the wall.
> 
> I need to fit some wood to the sill and the top of the reveal because a) I'll need to fit the vertical battens into them using either mortise and tenon or dovetail joints, b) I need to isolate the vertical battens from the structural wall and c) the sill is very wonky and curves down quite a bit towards the right so I need to fit a new sill on top to level it out.
> 
> Using clips and channel on the sill and the top of the reveal to hold the horizontal battens would be the best way to isolate them from the structural wall but there's not enough space for that, so I need something else I can use between the reveal/sill and the horizontal battens to provide some isolation/dampening and which will also allow me to use something to level out the new sill. Some thin foam/mat (up to 27mm thick) is an option but I'm not sure how much effect that would have.
> 
> In order to seal off the existing sill to prevent it transmitting sound from in the room into the structural wall, I'm going to extend it out into the room and support it with legs at each end so that I can join other pieces of wood to it to basically box off the original seal and fill the space with pink fluffy. When I soundproof the wall the radiator will be refitted over the plasterboard so it will move it away from the sill and I'll refit it lower down on the wall if necessary to make room for the boxing.
> 
> I see that Rockwool have these Sound Insulation Slabs now but they don't specify the density unlike their RWA45 (45kg/m3), RW3 (60kg/m3) and RW5 (100kg/m3) products, which made me suspicious.
> https://www.rockwool.co.uk/product-overview/trade-insulation-range/sound-insulation-slab-en-gb/
> 
> So I e-mailed them and they replied:
> 
> "The density of our Sound Slab is 35kg/m3, however, Higher density does not always mean a higher acoustic performance, it depends on the frequency of the sound; also, the sound slab is available at 400mm wide whereas the others are all 600mm wide, so if you have floor joists, there would be less wastage with the sound slab."
> 
> I dare say there's some truth in the suggestion that higher density may not provide much benefit at some (higher) frequencies but at lower frequencies I'm sure it would, so this seems like an inferior product from a soundproofing point of view, unless you only need to soundproof against mid-high frequencies I guess.
> 
> Do you think RWA45 with 45kg/m3 would suffice for window plugs or would you suggest something higher like RW3 or RW5? It seems like the window plugs will always be the weak point whatever I use. This 15mm plasterboard is 940kg/m3 https://www.insulationshop.co/15mm_gyproc_soundbloc_f_high_density_acoustic_board_1200_x_2400mm.html and 14.1kg/m2, so two layers would be 28.2kg/m2. 50mm thick RW5 is 100kg/m3 which I think works out to 5kg/m2 (0.05 * 100), so there'll be far less weight/density between the room and the window/reveal (which is part of the structural wall) than there will be between the room and the rest of the structural wall.


Hi, I don't see the attached picture 

-Matt


----------



## doveman

warwwolf7 said:


> Hi, I don't see the attached picture
> 
> -Matt


Sorry, not sure what happened there. You should be able to see it now.


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## warwwolf7

doveman said:


> Sorry, not sure what happened there. You should be able to see it now.


Edit: I can see it now

-Matt


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## mhutchins

War, could you draw in the legs and show where rigid attachments are made to the wall vs the isolated attachments. I'm still having a hard time trying to figure out where the clips and channel are going. It sounds like you want to isolate the plug from the wall, but that isn't necessary. Sorry if I'm being dense. It's probably too late for me to be thinking about this tonight.

Mike


----------



## FarriorMVP

HT Geek said:


> Given those constraints, I'm thinking you should build your sound isolation around it and consider the sump pump closet to be part of the area you want to keep sound out of from your basement, as if it was a bedroom or something like that.
> 
> One option would be a double thick door. Glue and screw one identical door to another. Get yourself some Big Ass Hinges. Consider installing an automatic door bottom as well (installed on the opening side of the door).


This is great advice. This is what I'll do for the sump area.



HT Geek said:


> There are two "best" options: 1) clips and channel or 2) wood studs with an air gap between them and the basement foundation walls. Do you have existing studs in the basement, or is your home resting on stone foundation? You mentioned it's 110 yrs old IIRC, so I am betting you don't have existing studs in there holding up the remainder of the home. That would be unusual.


There are no existing stud walls in the basement. Stone foundation walls that have been sealed for moisture control.

You've convinced me that clips and channel is the way to go instead of my original approach. I do have a couple questions, though:
--Do you have any recommendations on which clips to get and where to buy them? 
--Is there a material difference in the effectiveness of one clip vs another? I saw "whisper clips" on TM Soundproofing's site and they had others offerings that implied better/worse performance. Do you see a big difference between one brand vs another?
--You would do the clips and channel on both the ceilings and the walls, right?




HT Geek said:


> You should also apply sealant between juxtaposed drywall, for the interior drywall layers (i.e. not the layer being mudded and finished). Don't use mud on the interior drywall layers. The caulk is flexible (that's what makes it "acoustic" caulk) and will dry as a rubbery compound.


This is the same as the SC175 stuff you mentioned below, right?



HT Geek said:


> Personally, I'd say you could skip the Green Glue for your walls given your circumstances. It wouldn't hurt, but I'm not convinced the benefit is worth the cost. I would be inclined to use it between ceiling drywall layers though. That's all presuming your basement stud walls do not make physical contact with your foundation walls or the floor joists of the level above.
> 
> First, you're going to have gaps and crevices in your basement ceiling. Those should be addressed. You want to seal them with something appropriate, such as a suitable caulk/sealant. For larger cracks (> 1/4" or so), shove some backer rod in there - is a cellulose type of product, in a tube shape. Apply the caulk over it. The backer rod will "back" or support the caulk and allow you to seal the gap properly.


I will look into the green glue for just the ceiling layers.

I'm a little confused by the gaps and crevices you're talking about. Is this in reference to the gaps between the sheets of adjacent drywall?




HT Geek said:


> 2) 2nd option is to use clips & channel attached to the bottom of the floor joists from the floor above.


I should have mentioned that my ceiling is at 7.5" before I finish (dri-core on floor and carpet, plus lost height with whatever approach I choose).

I think 2nd option is my best bet.

As for insulation, I think the "pink fluffy" makes sense for me. The home was owned by an architect before us and he went all out to seal out moisture from the basement as he stored a lot of work-related materials down there. Hence, the extra benefit of Roxul in this case may not do me any good.

Last question - my contractor had put metal studs in the plan instead of wood. Do you have a sense for what is better for the soundproofing in light of the clips and channels approach I'll be taking? I saw some research on it that was more or less inconclusive on which was best.


----------



## FarriorMVP

Ladeback said:


> What room is above the theater, bedrooms, living room kitchen? My theater I am building is below my living room/kitchen eating area. I have it operational, but not complete. You can here sound coming from above when I am watching football or a movie, but I usually don't crank it when my wife is is above watching TV. Now I will hear my kid and dog running around and the sub woofer from our living room below. Have you tried to play music or something in the basement to see how loud it is upstairs? If you like a lot of bass it will take a lot to slow it down.
> 
> I have decided to try to get my room done and do as much as I can with just insulation and maybe double layers of drywall, my wife doesn't complain about me playing anything to loud so I don't see the reason go nuts with soundproofing.


Thanks - it sounds like our situations aren't that different.

Above the theater is the existing living room/tv room that we use regularly today. The tv-watching couch, though, is right next to an open stairwell to the 2nd floor and the kids bedroom doors are right at the top of the steps. That open stairwell/balcony area near the current tv and kids' bedrooms causes me to continually turn the volume down for sports and movies at night -- hence the need for a basement setup where I can crank it up a bit.


----------



## HT Geek

The AVS Forum quote/reply seems to be acting a bit weird atm, but I'll try to keep my reply in context to your last message.



FarriorMVP said:


> There are no existing stud walls in the basement. Stone foundation walls that have been sealed for moisture control.


Great. That will make things easier and possibly cheaper as well.



> You've convinced me that clips and channel is the way to go instead of my original approach. I do have a couple questions, though:
> --Do you have any recommendations on which clips to get and where to buy them?


In terms of performance, make sure you get clips that include rubber. Don't get the cheapo clips that are metal only (they work, but the clips with rubber isolators are superior).



> --Is there a material difference in the effectiveness of one clip vs another? I saw "whisper clips" on TM Soundproofing's site and they had others offerings that implied better/worse performance. Do you see a big difference between one brand vs another?


It's difficult to ascertain which clip might perform better than the others once you are comparing clips with rubber and similar designs. I have seen some slight variations between 2 or 3 brands in lab tests, but my recollection is the differences were negligible (perhaps 1 db).

I would recommend the cheapest clips that have a rubber isolator. That is typically going to be the Resilmount A237R or the PAC International RSIC-1. Plan on spending ~$4.50 to $5 per clip.

I don't want to steer you in any particular direction beyond what I stated above, as product availability near where you live may be different than where I live. However, I shall say that I have had a positive experience with the PAC INTL clips. I like the fact that PAC publishes lab results, they have thorough and well documented instructions, a variety of products, and their products seem well built and they work. I would say PAC probably has the best all-around support from clip manufacturers. If you run into a question or problem, you can reach out to them directly. I have found their customer service reps to be helpful. If you go with the Resilmount, make sure it has the -R designation on the product name (the "R" = "rubber').

Other options include the WhisperClip (also known as Green Glue Clips) as you mentioned. I have not used them before, but believe they are recommended by The Soundproofing Company, and based on that fact I'm sure they are good. They will run you ~$6 per clip. It's a different design philosophy. Instead of the hard rubber, they use a softer, thinner rubber and that manner in which the clip grips the hat channel is a bit different. They also attach to the studs with 2 screws instead of one, so I'd say that would ostensibly be a bit stronger. However, that's a non-issue if you follow the manufacturer instructions on mounting any clip (unless you know you're going to be loading with lots of extra weight... but in that case just use more clips).

You could also consider the GenieClip (manufactured by Pliteq), which will run you about $5 per clip.

I have experimented a bit with the Resilmount, but I can't offer a strong opinion on it one way or another. Based on the design, I don't see why it wouldn't work just as well as the PAC. Either way, those 4 that I mentioned are the standard selection of clips used by most people.

Now, you didn't ask but I feel compelled to also discuss Hat Channel while discussing clips. I say that because you need to be careful about which hat channel you select. Most of these clips require 25-gauge steel hat channel. However, the WhisperClip again takes a bit of a departure here and calls for 20-gauge steel. This is important because 25 or 26 gauge is the "standard" (if there really is such a thing) for hat channel gauge in the construction industry. Make sure you or your contractor are using the appropriate type. You could possibly just use 20-gauge steel on all of them, but the thicker steel might be too tight of a fit into the clips, so again I would go with the manufacturer recommendations for whatever clip you choose.



> --You would do the clips and channel on both the ceilings and the walls, right?


Ceiling, yes. Walls, no. I think you're better off with a hybrid approach. I'll explain why.

Ceiling first. Clips and channel definitely makes the most sense for your situation. You may want to consider PAC Intl's RSIC-1 Low Profile clip for the ceiling. I'm not sure what you'll find the cost at. May or may not be worthwhile as you're not super close to height limits, but you don't have much wiggle room either.

BTW, are there any pipes or other obstructions currently hanging below the current ceiling joists that you will need to work around? If so, can they be moved or are they going to impact your finished ceiling height?

Now, for the walls....

Since you have just the concrete walls right now, I would recommend you first install wood or steel studs. One of the main reasons for doing this is to ensure you have a straight wall (as old as your house is, it's unlikely those existing concrete walls in the basement are perfectly straight). Another reason is then you don't need clips and channel (save $$$)... well, actually you need fewer clips, but I'm sure you get the point. Leave an air gap between the stud wall and the concrete. Leave a minimum 1" space. This will allow for variations in the wall surface (i.e. it may be a bit less than 1" in some places). I'd use a level, square, and laser level to ensure your "new" walls are perfectly straight and not count on the 110 year old concrete walls being straight. 

Do not fill that gap with insulation. Do place insulation between your studs.

In addition to the new stud wall being bolted to the floor, I would use something like the RSIC DC-04 clips to secure the walls to the concrete walls behind them in strategic spots. You don't need a ton of them. Secure the corners of the room and about every 2 meters or so along the wall. In a 7-7.5' tall room you'll need 2 clips per position. It will add structural rigidity to your room while still decoupling it. I realize that doesn't eliminate using clips on the walls, but it will dramatically reduce how many you need. The studs are a lot cheaper than clips & channel.

You'll effectively be creating a double-stud wall, if you imagine the concrete foundation walls as your first wall.

You *could* also install a raised floor, but I don't see much point in that for your situation unless you want to insulate it thermally. If that is the case, something like rubber mat/wood or rubber/wood/rubber/wood is ideal. You'd leave a gap between the edge of the floor and the structural concrete walls (again, de-coupling) and mount your studs through that false floor (so the footers for the studs go on top of the false floor you created). I'd imagine you won't go this route due to your height restrictions, but thought I'd mention it.




> This is the same as the SC175 stuff you mentioned below, right?


When I mentioned acoustic caulk? Yes. That is the best value good caulk you are likely to find (~$75 for a case of 12x 29 oz. tubes).




> I will look into the green glue for just the ceiling layers.


IMHO that will be money well spent on your ceiling.



> I'm a little confused by the gaps and crevices you're talking about. Is this in reference to the gaps between the sheets of adjacent drywall?


Partly. I should have been clearer. What I was thinking originally was before you even got that far, that in a 110 year old house there's going to be some gaps here and there from settlement. However, you mentioned in your last post that the prior owner sealed the basement for water proofing purposes, so some of the gaps that could exist may have already been dealt with. Either way, what I was thinking of is there are normally air gaps between the basement ceiling and 1st floor above. Usually along the edges of the top of your basement, where it meets the bottom of the level above. Not a huge deal, but if you can take a look and plug any gaps that you find (within reason), every little bit helps in sound proofing. It might be a non-issue for you.

The other thing I was thinking of was yes, where you have corners of drywall abutting each other you want to be sure those corners get caulked. And along the bottom and top of the drywall sheets. When you hang the drywall, you want to leave about a 1/4" gap in the corners (i.e. between wall drywall and floor, wall drywall and ceiling drywall, etc.). Then you fill in those gaps with acoustic caulk. This allows the drywall to flex without it sending vibrations into adjacent corner surfaces.



> I should have mentioned that my ceiling is at 7.5" before I finish (dri-core on floor and carpet, plus lost height with whatever approach I choose).


Yep. Good to know. It's going to be a bit tight, but totally do-able to leave you with 7 feet. I am presuming that is minimum ceiling height to building code where you live (in some states it's 6' 8"). 



> Last question - my contractor had put metal studs in the plan instead of wood. Do you have a sense for what is better for the soundproofing in light of the clips and channels approach I'll be taking? I saw some research on it that was more or less inconclusive on which was best.


Actually, there is some research that indicates metal is slightly superior - about 1 db, IIRC - and there is some that has showed no difference. Either way, metal studs won't hurt. The nice thing about them is you're guaranteed they are straight. They usually cost more to install.


----------



## HT Geek

mhutchins said:


> War, could you draw in the legs and show where rigid attachments are made to the wall vs the isolated attachments. I'm still having a hard time trying to figure out where the clips and channel are going. It sounds like you want to isolate the plug from the wall, but that isn't necessary. Sorry if I'm being dense. It's probably too late for me to be thinking about this tonight


Actually, it's @doveman's build.


----------



## HT Geek

doveman said:


> Using clips and channel on the sill and the top of the reveal to hold the horizontal battens would be the best way to isolate them from the structural wall but there's not enough space for that, so I need something else I can use between the reveal/sill and the horizontal battens to provide some isolation/dampening and which will also allow me to use something to level out the new sill. Some thin foam/mat (up to 27mm thick) is an option but I'm not sure how much effect that would have.
> 
> In order to seal off the existing sill to prevent it transmitting sound from in the room into the structural wall, I'm going to extend it out into the room and support it with legs at each end so that I can join other pieces of wood to it to basically box off the original seal and fill the space with pink fluffy. When I soundproof the wall the radiator will be refitted over the plasterboard so it will move it away from the sill and I'll refit it lower down on the wall if necessary to make room for the boxing.


So, if you are going to box in the window and support the box with legs, how is that going to impact the overall design of that wall? Are you going to have a bulge out from the wall?



> I see that Rockwool have these Sound Insulation Slabs now but they don't specify the density unlike their RWA45 (45kg/m3), RW3 (60kg/m3) and RW5 (100kg/m3) products, which made me suspicious.
> https://www.rockwool.co.uk/product-overview/trade-insulation-range/sound-insulation-slab-en-gb/
> 
> So I e-mailed them and they replied:
> 
> "The density of our Sound Slab is 35kg/m3, however, Higher density does not always mean a higher acoustic performance, it depends on the frequency of the sound; also, the sound slab is available at 400mm wide whereas the others are all 600mm wide, so if you have floor joists, there would be less wastage with the sound slab."
> 
> I dare say there's some truth in the suggestion that higher density may not provide much benefit at some (higher) frequencies but at lower frequencies I'm sure it would, so this seems like an inferior product from a soundproofing point of view, unless you only need to soundproof against mid-high frequencies I guess.
> 
> Do you think RWA45 with 45kg/m3 would suffice for window plugs or would you suggest something higher like RW3 or RW5? It seems like the window plugs will always be the weak point whatever I use. This 15mm plasterboard is 940kg/m3 https://www.insulationshop.co/15mm_gyproc_soundbloc_f_high_density_acoustic_board_1200_x_2400mm.html and 14.1kg/m2, so two layers would be 28.2kg/m2. 50mm thick RW5 is 100kg/m3 which I think works out to 5kg/m2 (0.05 * 100), so there'll be far less weight/density between the room and the window/reveal (which is part of the structural wall) than there will be between the room and the rest of the structural wall.


Without getting into excruciating details, I'd say anything you do is going to be an improvement. They may be a weak point, however considering the lengths you are going to, your end result is going to be superior to what 99.9% of the population would do.


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## doveman

HT Geek said:


> In terms of performance, make sure you get clips that include rubber. Don't get the cheapo clips that are metal only (they work, but the clips with rubber isolators are superior).
> 
> It's difficult to ascertain which clip might perform better than the others once you are comparing clips with rubber and similar designs. I have seen some slight variations between 2 or 3 brands in lab tests, but my recollection is the differences were negligible (perhaps 1 db).
> 
> I would recommend the cheapest clips that have a rubber isolator. That is typically going to be the Resilmount A237R or the PAC International RSIC-1. Plan on spending ~$4.50 to $5 per clip.
> 
> I don't want to steer you in any particular direction beyond what I stated above, as product availability near where you live may be different than where I live. However, I shall say that I have had a positive experience with the PAC INTL clips. I like the fact that PAC publishes lab results, they have thorough and well documented instructions, a variety of products, and their products seem well built and they work. I would say PAC probably has the best all-around support from clip manufacturers. If you run into a question or problem, you can reach out to them directly. I have found their customer service reps to be helpful. If you go with the Resilmount, make sure it has the -R designation on the product name (the "R" = "rubber').
> 
> Other options include the WhisperClip (also known as Green Glue Clips) as you mentioned. I have not used them before, but believe they are recommended by The Soundproofing Company, and based on that fact I'm sure they are good. They will run you ~$6 per clip. It's a different design philosophy. Instead of the hard rubber, they use a softer, thinner rubber and that manner in which the clip grips the hat channel is a bit different. They also attach to the studs with 2 screws instead of one, so I'd say that would ostensibly be a bit stronger. However, that's a non-issue if you follow the manufacturer instructions on mounting any clip (unless you know you're going to be loading with lots of extra weight... but in that case just use more clips).
> 
> You could also consider the GenieClip (manufactured by Pliteq), which will run you about $5 per clip.
> 
> I have experimented a bit with the Resilmount, but I can't offer a strong opinion on it one way or another. Based on the design, I don't see why it wouldn't work just as well as the PAC. Either way, those 4 that I mentioned are the standard selection of clips used by most people.
> 
> Now, you didn't ask but I feel compelled to also discuss Hat Channel while discussing clips. I say that because you need to be careful about which hat channel you select. Most of these clips require 25-gauge steel hat channel. However, the WhisperClip again takes a bit of a departure here and calls for 20-gauge steel. This is important because 25 or 26 gauge is the "standard" (if there really is such a thing) for hat channel gauge in the construction industry. Make sure you or your contractor are using the appropriate type. You could possibly just use 20-gauge steel on all of them, but the thicker steel might be too tight of a fit into the clips, so again I would go with the manufacturer recommendations for whatever clip you choose.


I've been comparing the various clips recently, so I'll share what I've found in case it's useful to anyone else.

As you say, there doesn't appear to be much difference between the various clips. I saw the attached image on another forum but I see it is taken from the end of this data sheet for the Whisper clip https://www.tmsoundproofing.com/products/WCR/WCR_TechData.pdf and shows the STC varies by only 2-3 points between even the most basic, non-rubberised, RSIC-V and the other clips.

RSIC-V looks much the same as the A237, which can be bought for $1.89 each. I can't get these in the UK but even with the international shipping and taxes this may still be the cheapest option for me and they also have the advantage of having the least height of all the clips, as the clip plus 25 gauge 7/8" high channel totals 1-3/8" (34.925mm). Maximum dead load capacity is 55 lbs
https://www.tmsoundproofing.com/Resilmount-A237-Resilient-Sound-Isolation-Value-Clip.html

IsoMax seem to be essentially the same height, even with the added rubber. The drawing on the website actually shows a combined height of 1.32" (33.528mm) which is less than the A237, but the installation guide shows 1/2" from the edge of the clip to where the 7/8" channel starts, which gives 1-3/8" (34.925mm). Load capacity of 36 lbs with 25 gauge channel or 48 lbs with 22 gauge channel.
https://kineticsnoise.com/arch/isomax.html

US prices are around $5.95 but I can get these in the UK for £5.39 so it's probably no cheaper to import them.
https://www.soundaway.com/kinetics-IsoMax-sound-isolation-clip-p/13001.htm
https://flooringwarehousedirect.co.uk/product/isomax-clip/

A237R have the second lowest height when used with 7/8" channel of 1-5/8" (41.275mm). They're about 2.5 times more expensive than A237 at $4.79 and the max load is lower at 36 lbs.
https://www.tmsoundproofing.com/Resilmount-A237R-Resilient-Sound-Isolation-Clip-With-Rubber.html

The information could be clearer, as the image on that page shows the combined height as 1-5/8", which seems consistent with the specs given at the end of this PDF showing the clip height as 1-1/8" and the rubber height as 3/8" for a total of 1-4/8" (38mm) (meaning the channel protrudes 1/8" past the clip) but the first page of the PDF shows the clip height as 1-11/16".
https://www.tmsoundproofing.com/products/Studco/TMS_A237RProductSpecsodg.pdf

A possible alternative to the A237R that is available in the UK is the MuteClip for £3.90 with max load 36 lbs. It says it has a height of 1-9/64" (29mm) but that seems unlikely as that's essentially the height of the A237 without any rubber part, so if the MuteClip is 29mm including the rubber part then the metal part would have to be less deep than the A237 and presumably the channel will protrude more. So I'm not sure what the combined clip+channel height would be for this.
https://www.ikoustic.co.uk/products/wall/muteclip

Whisper clips with 7/8" channel have a height of 1-3/4" (44.45mm). These don't seem to be available in the UK and US prices are $5.34 when buying 20 or more or $4.55 for 200+. Recommended load is 36 lbs, max safe load 46 lbs.
https://www.tmsoundproofing.com/whisper-clips-green-glue.html

Genie clips with 7/8" channel have a height of 2-1/64" (51mm) and are available in the UK for £3.79 or £3.48 for 100+. Max load 36 lbs.
https://www.soundstop.co.uk/ZGENIECLIP.php

So considering that there doesn't appear to be much difference in STC between the products (I imagine the performance of A237R, MuteClip and Genie clips will be much the same as RSIC-1 as they're all very similar construction) and the fact I need to minimise space loss I'd probably use A237/RSIC-V on my walls and for my ceiling, where I can afford to lose a bit more space and which is more problematic in terms of noise transmission than my walls, I might use A237R/RSIC-1/Genie clips or Whisper clips. I think STC only measures attenuation of airborne noise though, so that table may not be that useful for deciding what to use on a ceiling, where impact noise is a problem but I imagine something with a rubber component would work better for that than something without.


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## doveman

HT Geek said:


> So, if you are going to box in the window and support the box with legs, how is that going to impact the overall design of that wall? Are you going to have a bulge out from the wall?


It will protrude a bit but once I've fitted clips+channel+30mm plasterboard to the wall around the window the box won't actually protrude that much. I might even be able to hide the legs behind the plasterboard if I use something with a small enough diameter but even if they have to sit in front of the plasterboard, they'll be either side of the radiator so won't really be in the way.



> Without getting into excruciating details, I'd say anything you do is going to be an improvement. They may be a weak point, however considering the lengths you are going to, your end result is going to be superior to what 99.9% of the population would do.


Sure and if I was only making window plugs I wouldn't worry about it but it seems somewhat illogical to put 27kg/m2 of soundproofing over most of the wall but then leave part of it (the window reveal) with only 5kg/m2 of soundproofing between it and the room. In fact that's the weight of the 50mm rockwool between the room and the window and the rockwool will be stuck to 9mm ply which will add some more weight to that path but sound hitting the edges of the plugs will only have to travel through the ply and a few mm of rockwool to reach the wall/reveal and even if I fitted clips+channel around the reveal so it also had to travel through those to reach the wall, it still will have avoided the 30mm plasterboard covering the rest of the wall. It may be there's nothing that can be done about it, unless one's willing to permanently seal off the windows by extending the plasterboard over them but that doesn't change the fact that having less soundproofing over part of the wall is an issue.


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## doveman

I'm looking for acoustic caulk for a 3mm perimeter around my floor and between the floor and the skirting board.

I was going to get this as it seemed a good price for 900ml but then I realised it doesn't say anything about fire-resistance
https://www.toolstation.com/ac50-trade-acoustic-sealant-adhesive/p29734

So would either of these do instead?
https://www.toolstation.com/ac95-intumescent-trade-acoustic-sealant-adhesive/p59088
https://www.toolstation.com/fire-mate-intumescent-acrylic-sealant-310ml/p58145

Also, how would I calculate how much I'd need to do approx. 9m of 3mm *2 (one line for the floor and one line for the skirting)? I'm sure 900ml would be more than enough but then I'd have to buy a 900ml sealant gun as well for about £15, so using 310ml tubes might be a better option for me. I know I could re-use a 900ml gun for Green Glue later but I think I might just buy a bucket of that instead of the tubes.


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## JustDingus

Hey guys 

I'm sorry if this has been asked in the thread already but i'm lookin to do some sound proofing in my living room

I'm trying to add some panels to the vault in my living room.. I just wanna know what kind of panels should I look for? what shape is the best to get? (egg crate/ Pyramid/ Square/ Wedge) so on and so on... how thick do I want it? how dense should it be? whats a good way to hang it? 

Basically I have NO freakin idea what I should be getting or how to do it hahah... Any links or places to suggest would be awesome...


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## HT Geek

doveman said:


> I'm looking for acoustic caulk for a 3mm perimeter around my floor and between the floor and the skirting board.
> 
> I was going to get this as it seemed a good price for 900ml but then I realised it doesn't say anything about fire-resistance
> https://www.toolstation.com/ac50-trade-acoustic-sealant-adhesive/p29734
> 
> So would either of these do instead?
> https://www.toolstation.com/ac95-intumescent-trade-acoustic-sealant-adhesive/p59088
> https://www.toolstation.com/fire-mate-intumescent-acrylic-sealant-310ml/p58145
> 
> Also, how would I calculate how much I'd need to do approx. 9m of 3mm *2 (one line for the floor and one line for the skirting)? I'm sure 900ml would be more than enough but then I'd have to buy a 900ml sealant gun as well for about £15, so using 310ml tubes might be a better option for me. I know I could re-use a 900ml gun for Green Glue later but I think I might just buy a bucket of that instead of the tubes.


You may be able to handle that with one 900ml tube. I would buy 2.

3mm is quite small. Really depends on how adept you are at caulking. 

Any of those caulks should work. Is fire retardation a requirement? They are almost all fire resistant or retardant to some extent. Either way, to be quite frank it's a moot point. If your home catches on fire, it won't make any difference what kind of caulk you have. It's the interior furnishings that really get house fires going. And once they get a foothold, you are S.O.L. For example, the only thing "fire retardant" drywall does is to slow down the combustion process, and very minimally at that. It won't stop it.

The drafts you're preventing by using caulk in the first place will be more effective than any other characteristic of the caulk, with regards to fire proofing.


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## HT Geek

JustDingus said:


> Hey guys
> 
> I'm sorry if this has been asked in the thread already but i'm lookin to do some sound proofing in my living room
> 
> I'm trying to add some panels to the vault in my living room.. I just wanna know what kind of panels should I look for? what shape is the best to get? (egg crate/ Pyramid/ Square/ Wedge) so on and so on... how thick do I want it? how dense should it be? whats a good way to hang it?
> 
> Basically I have NO freakin idea what I should be getting or how to do it hahah... Any links or places to suggest would be awesome...


You'll need to provide more details if you want constructive feedback. What are you trying to accomplish? What are your goals? And what is the background on your project / current status?


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## doveman

HT Geek said:


> You may be able to handle that with one 900ml tube. I would buy 2.
> 
> 3mm is quite small. Really depends on how adept you are at caulking.
> 
> Any of those caulks should work. Is fire retardation a requirement? They are almost all fire resistant or retardant to some extent. Either way, to be quite frank it's a moot point. If your home catches on fire, it won't make any difference what kind of caulk you have. It's the interior furnishings that really get house fires going. And once they get a foothold, you are S.O.L. For example, the only thing "fire retardant" drywall does is to slow down the combustion process, and very minimally at that. It won't stop it.
> 
> The drafts you're preventing by using caulk in the first place will be more effective than any other characteristic of the caulk, with regards to fire proofing.


Thanks, I'll get two 900ml tubes to be safe then.

Yeah, checking the bathroom sealant which I did myself that's 15mm so 3mm is very small but I think having a 15mm wide line of sealant around the floor (and at the edges of the drywall) would look strange and it needs to be kept as small as possible to avoid creating a weak point that undermines the soundproofing. I guess it won't be visible around the floor as it will be hidden under the 15mm thick skirting board I'm going to fit and once I fit drywall to the walls it will be hidden under those but even so, if I want to do a small line around the edges of the drywall I might as well practice trying to do that on the floor!

I guess the fire resistance is probably just a building requirement but anything that slows down the spread of fire, even if only a little, is a good thing and it's not like it really costs any more to get a fire resistant sealant. The AC95 says it provides up to 5 hours of fire resistance but I guess it depends on how long the drywall would last, as if that catches fire in 5 minutes the sealant's irrelevant really, although I suppose it might help stop the fire getting to the pink fluffy behind the drywall for a bit. 

I presume any of these sealants are suitable from a sound proofing point of view and I don't need to be looking for something that specifically says it's for sound proofing, although the AC95 does say it's an acoustic sealant anyway?


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## HT Geek

doveman said:


> I presume any of these sealants are suitable from a sound proofing point of view and I don't need to be looking for something that specifically says it's for sound proofing, although the AC95 does say it's an acoustic sealant anyway?



I would get one that says "acoustic" if possible. Alternatively, anything that says something like, "40-year caulk" will work. The gist of it is you are looking for caulk that is designed to be flexible and not crack easily with minor movements in the adhered surfaces. That means a caulk that does not harden, but remains pliable over time.


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## jconjason

Subscribed.


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## barfle

*Risers on a floating floor?*

I'm just starting a new HT build, and I intend to put in a floating floor, probably OSB over a foam pad, but I'm not sure how to go about putting in a riser for the second row. Should I put in the floating floor, then install the riser over it, or install the riser on the existing subfloor and float the surface of the riser?

The room is over a garage, so my purpose is to keep the sound out of the HT.


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## doveman

HT Geek said:


> I would get one that says "acoustic" if possible. Alternatively, anything that says something like, "40-year caulk" will work. The gist of it is you are looking for caulk that is designed to be flexible and not crack easily with minor movements in the adhered surfaces. That means a caulk that does not harden, but remains pliable over time.


OK, thanks. I'll probably get the AC95 unless I come across something much cheaper that fits the criteria.

I've been thinking a bit more about my window plugs and I've knocked up a couple of drawings to try and illustrate the problem.

The attached picture shows what I was originally going to do, with the space divided into three using two vertical battens (probably joined to planks of wood running along the top of the reveal and the sill, not shown here), then the foam/rockwool (yellow) would squash against the battens and the edges of the reveal/sill (or the wooden planks at the top and bottom but they would be directly coupled to the reveal/sill) and the foam would be stuck to a piece of 9mm plywood (orange) cut slighter smaller than the foam so that the wood doesn't touch the structural wall.

The potential problems with this approach is that at the edges where the plywood doesn't extend to, any sound has an easier path to get through as it doesn't have to pass through the plywood before reaching the foam and it also has a short path into the structural wall, except for the edge that's against the vertical batten but that is joined to wooden planks that are coupled to the structural wall.

Even where the plywood is covering the foam, anywhere outside of the red zone it has a shorter path to the structural wall. With 50mm thick foam, inside the red zone any sound has to travel through the plywood and then 50mm foam before reaching the air gap between the foam and the window and it also have to travel through the plywood and at least 50mm of foam before reaching the reveal/structural wall.

Outside of the red zone however, the sound has an increasingly shorter path to the reveal/structural wall.

The question is whether this is actually a problem. Assuming the plywood is 5mm short of the foam, maybe 5mm is too narrow for low frequency soundwaves to travel through but maybe it could still allow troublesome mid-high frequencies to travel enter or exit the room via the structural wall? As for the area outside the red zone, could that be an issue in that it presents a shortcut where sound only has to travel through 9mm plywood and anywhere between 49mm down to 6mm of foam (depending on where the sound hits the plug) before reaching the structural wall?

I've thought of another way of doing the plugs which I think might solve these problems, which I'll explain in another post.


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## doveman

So this is my alternative window plug approach.

As shown in the first attached drawing, it involves fitting battens (orange) to the wall outside the reveal using clips+channel so the battens aren't coupled to the structural wall and then the foam (yellow) is squashed in between the battens. The foam would be stuck to 9mm plywood, as shown in the second drawing and the plywood would cover the foam and extend past it so it sits over the battens. There could be a rubber strip between the battens and the plywood but it's probably unnecessary as the battens aren't coupled to the wall anyway.

As the third drawing shows, looking at it from the top down, the depth of the reveal (i.e. the gap between the wall (black) and the window (white)) is about 90mm. Then the 35mm clips+channel (blue) and 40mm battens bring the frame 75mm forward from the wall, so the 50mm foam still sits about 25mm away from the wall.

Obviously sound hitting the plywood outside of the red zone still has a shorter path to travel to reach the battens but as they're decoupled from the wall it shouldn't matter.

There's also a larger gap between the foam and the window with this method, about 115mm versus 40mm if the foam is fitted inside the reveal but there's probably no real benefit from that.

The frame will stick out a bit past the walls once they're fitted with clips+channel+two layers of 15mm drywall, as that will be about 65mm whereas the frame is 75mm. I don't think that really matters but I guess I could use 30mm battens instead of 40mm to make it all flush.

The snag with this approach is the window sill. If I have the foam squashed against that it rather undermines the whole point of having the other three sides squashed against decoupled battens. I did think of fitting clips and channel and an internal decoupled sill but there's not enough height space for that and the sill is only about 75mm deep and the clips are about 100mm, so they wouldn't fit anyway. The sill extends about 35mm from the wall, which is about the depth of the clips+channel, so I could fit a batten to the wall underneath the sill (I'd have to move the radiator down first though to make space and that's quite a major operation as the pipes would need to shortened) but with 40mm battens and 50mm foam, that would still leave 10mm of foam in contact with the sill.

The only thing I can think of is to fit some 25mm rigid foam/rubber to the sill and then put a new internal sill on top that is screwed into the original sill. It won't be properly decoupled as the rigid foam will transmit sound (I think it needs to be rigid otherwise the sill will move when weight is put on it and the foam compresses) as will the screws but maybe it will be enough. If it's still going to undermine the rest of the decoupled frame however, I might as well just fit battens on foam inside the reveal for the other three sides too, instead of using clips+channel.


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## AnnapolisSony

*Calling all AVS HT room soundproofing gurus!*

I am in the planning stages of my “2.0” at this time and I am looking for some general soundproofing advice before I move any further along (I haven’t even started an official thread yet). Final thickness of walls and ceilings will obviously affect my construction/framing plans so I am turning to experienced forum members for advice so that I can continue moving forward planning with my contractor.

I am up against a few challenges using this space - the biggest one being lower-than-normal ceiling joists @ 91” throughout my basement.  The overall dimensions of this space will be *12’ 5” W x 21’ 5” L*…give or take a few inches and it will be more of a dedicated room this time around. When I built my room in my former house back in 2013, I began with mostly already-finished walls and ceilings and the space was a more open living space with a home theater set up within it (it was at least 2 1/2 times larger with 8’ ceilings). 

*The #1 priority for me is soundproofing this room and I hope to be able to do it without breaking the bank.* It does not need to be to the triple drywall standard that some high-dollar theater rooms here on AVS have achieved but I would like to try to minimize sound out/sound in as much as possible to please the wife upstairs (on the 1st floor) and because we have a furnace and a laundry area just outside of the space. The good news is that I have some flexibility in terms of building out my walls, adding additional layers of drywall, ceilings, adding insulation, etc. because not one existing wall of the room is built up against an exterior/foundation wall. There are some ducts/returns in between ceiling joists in the room so I’ll just have to do my best with additional insulation and drywall. Not the most ideal to have ducts in the ceiling but relocating the vent ducts/returns is not an option. I have recently removed the god-awful drop ceiling/grid and I intend to go back with new lighting and a finished drywall ceiling. Central air/heat is being added to both the finished and unfinished areas of our basement and rough in work for that will take place when my contractor modifies a couple of the walls that I mention below. 

Below are two sketches of the plan as it is today. The only difference being that the top sketch does not show the 1st row of theater seats and the 2nd one does. I have lettered each wall (A-F) so that you all know which wall I am referring to in my descriptions below: 






















*Wall A*

This is the wall I am proposing for the front of the room. The back of this wall is insulated with R11 in stud bays but does not have drywall on the backside. Nor will I be able to add any - it is too tight back there. The bad news is that I have approximately 18” between it and the exterior foundation wall behind it. I know, no bueno for soundproofing. This thread here is proof.  That said, the finished wall continues across my basement - to the other side - with the same amount of space running behind it the entire way. When natural gas was added years ago, they ran 2 gas lines straight through the space and secured both of them to the back of the exposed studs about 80” above grade. 

I am hesitant to install in-wall speakers on Wall A for obvious reasons (even will backer boxes) so the plan for now is to go with on-wall Triads for the front L-C-R. I have not given up on the possibility of in-walls behind an AT screen (if I go the PJ route) but I have to get this soundproofing issue resolved before I can even consider that. I put in a contingency for an additional 4.25" inside Wall A in the event that it is recommended that I build another wall for soundproofing. It will be virtually impossible to build another wall between the existing wall and the foundation wall due to the gas lines and a water line that run behind. Ceiling height in the front section of the room should be somewhere around 89-90” depending on how thick I go on ceiling. 

What is the best way to approach soundproofing Wall A? 

*Wall B*

This wall is obviously yet to be constructed but it’s purpose is obviously to close off the room from the other half of the basement (and staircase). A 30” doorway will be installed in this wall with a solid core door (this will be the only door in and out of the room). 

Should I build Wall B with DD? 

*Wall C*

This is currently the only finished wall in the room that I cannot gain access to from behind because it is the finished edge of the stairs. 

Would it make any sense to add an additional layer of drywall over top of the existing drywall to give myself more mass? Building another wall in front of the existing wall is not an option here because I am very limited on width in the room and sacrificing another 4-5” is just not possible.

*Wall D*

Similar to Wall B above, this wall’s purpose will be to close off the room from the other side of the basement in the back of the room. 

Should I build Wall D with DD as well? 

*Wall E*

As shown on the sketch, this wall is being modified a bit so that I can square out the back left corner of the room. Expanding that space will expose a lally column in this wall so I will most likely have to just box it out on the back wall so it is out of sight. I can access the backside of this entire wall (large unfinished storage area behind it) and I could in fact build another wall behind it. This existing wall has R11 in stud bays but does not have drywall on the backside. 

What would be the best approach to soundproof Wall E? 

*Wall F*

This wall is being slightly modified (to meet Wall E). I cannot build to much behind this wall due to the location of my gas furnace (the new wall will already be about 4-5” from it) and because we are roughing in a laundry area and powder room for construction at a later date. A 30” solid core door will be installed on this wall so that we can access the new laundry room and the storage area. This existing wall also has 3-in. R11 in stud bays but does not have drywall on the backside. I could probably add a layer of drywall (or 2) to the backside of this entire wall without too much trouble. 

What would be the best approach to soundproof Wall F? 

*Ceiling*

The plan is to finish the ceilings with drywall as well. Old drop ceiling and grid are down. The bays above are all insulated with R11 and, for the time being, I re-secured all insulation with new supports.

Should I consider using GG and DD (5/8”) for the finished ceilings? And what is the recommendation for the finished ceiling/bulkhead that is only 80” off the slab in the back of the room? Would it be effective if I added another layer of 5/8” drywall over top of the existing with GG? 

As shown on the drawing, a boxed out beam (1/2” DW) crosses through the middle of the room approx. 80” above grade. Is it worth wrapping this in another layer of 5/8” DW as well or just leave as is?

Of course this gear list is subject to change but below is my proposed A/V gear as it stands today:

*Plan A: PJ - Researching feasibility of short-throw PJs at this time
Plan B: SONY 85” XBR-85X900F TV
AVR: Denon AVR-X4500H
BR: Panasonic DP-UB820
Power Cond: Panamax M-5300
Amps: TBD (if necessary)
Fronts: Triad On-wall Bronze 4 LCR x 3 
Surrounds: Triad On-wall Bronze 4 SURROUND x 2
Rear Surrounds: Triad On-wall Bronze 4 LCR x 2 
Apple TV 4K
Sonos Connect
XBOX One*

Thanks in advance for your insight and opinions.


----------



## ronny31

AnnapolisSony said:


> I am in the planning stages of my “2.0” at this time and I am looking for some general soundproofing advice before I move any further along (I haven’t even started an official thread yet).


Sounds like you're going to be using home grade speakers, and I assume home grade subwoofers? Then you will probably get rather standard advice. Because you won't be outputting 110db+ midbass and compression-driver high frequencies. 

What's the gross height of the ceiling as is? 91 inches to the bottom of the joists? Is the area between the joists already filled with rockwool/glasswool/fiberglass insulation, and how tall are the joists? How's the floor on top of that? 

A neat trick I've seen with such low ceiling is narrow-angle horns with compression drivers for LCRs, and put them high up towards the ceiling, angled down (aimed slightly lower down than the listener's head). This helped the sound quality from less ceiling reflection and reduced sound transmission to the second floor. The screen was acoustically transparent and placed very high on the wall (the top of the image was barely an inch from the ceiling). With the LCRs behind that screen. This might make it difficult to find matching side and rear speakers if you want in-wall speakers because the LCR horns will make home grade tweeters sound like an asthmatic mouse whisper. But if you already have the LCRs then I guess this is not an option. 

I think if you want to make this not break the bank you should focus on the ceiling, door and ventilation. So more info on the ventilation situation would be good, so the experts on that can chime in. 

PS: I would definitely put all the equipment outside the theater, because no one wants to look at that blinky crap anymore  Also opens the possibility of using PA grade amplifiers in the future (they have noisy fans).


----------



## HT Geek

AnnapolisSony said:


> I am in the planning stages of my “2.0” at this time and I am looking for some general soundproofing advice before I move any further along (I haven’t even started an official thread yet). Final thickness of walls and ceilings will obviously affect my construction/framing plans so I am turning to experienced forum members for advice so that I can continue moving forward planning with my contractor.


Hey there. This looks like it's going to be an interesting build. Before I dive in with my 2 cents, allow me to mention two house-keeping items: 1) Thank you for doing such a great job framing your scenario and questions right out of the gate. I'm sure the fact this is going to be HT v2.0 for you has a lot to do with it, but I'm sayin' that anyway. Nice diagram too. 2) It's a tough time of year right now to get folks' attention on these matters (myself included). It seems like most of my neighborhood is on vacay this week, and I don't blame them!

Now... to the topics at hand....



> I am up against a few challenges using this space - the biggest one being lower-than-normal ceiling joists @ 91” throughout my basement.  The overall dimensions of this space will be *12’ 5” W x 21’ 5” L*…give or take a few inches and it will be more of a dedicated room this time around. When I built my room in my former house back in 2013, I began with mostly already-finished walls and ceilings and the space was a more open living space with a home theater set up within it (it was at least 2 1/2 times larger with 8’ ceilings).
> 
> 
> 
> Width is a little tight, but do-able. Are those your gross dimensions (stud-to-stud) and joist-to-concrete floor? Just wondering how much will be shaved off for various things.
> 
> Do you know what your state/local municipal required minimum floor-to-ceiling height is, whether it is measured finished or unfinished, and what the criteria for measuring are? It would be good to know ahead of time. Don't count on your contractor for that. The homeowner is on the hook (even if you paid someone to screw it up for you). If you plan on not getting a final inspection, it may be a non-issue. I'm not here to preach to anyone about building inspections. Just sayin' those are things you should take into consideration.
> 
> 
> 
> 
> *The #1 priority for me is soundproofing this room... without breaking the bank.... minimize sound out/sound... please the wife upstairs (on the 1st floor)... furnace and a laundry area just outside of the space. *
> 
> 
> 
> *
> 
> Priorities: $, WAF, noise. Check.
> 
> 
> 
> 
> ... have some flexibility... not one existing wall of the room is built up against an exterior/foundation wall.... ducts/returns in between ceiling joists in the room.... relocating the vent ducts/returns is not an option..... new lighting.... Central air/heat... rough in work....
> 
> Click to expand...
> 
> HVAC... lighting... the whole 9-yards. Good.
> 
> 
> 
> 
> .... I have lettered each wall (A-F) so that you all know which wall I am referring to in my descriptions below:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Click to expand...
> 
> Before we get into that, what is on the outskirts of the room-to-be? You mentioned Wall A and the 18" gap w/gas lines. What about the other spaces. I'm especially interested in better understanding the "south" wall (bottom of diagram) that says, "staircase edge wall." Please elaborate more on what is (or will be) on the other side of your perimeter walls, other than Wall A.
> 
> 
> 
> 
> Wall A
> 
> ... front of the room. The back of this wall is insulated with R11 in stud bays but does not have drywall on the backside.... I have approximately 18” between it and the exterior foundation wall behind it. I know, no bueno for soundproofing. This thread here is proof.
> 
> Click to expand...
> 
> Unless I missed something, I believe you may be reading too much into that thread. You do not have a triple-leaf scenario if I understand you correctly, but I'd like to verify. My understanding is on Wall A you do or will have, layered from inside the theater, out:
> 
> - Drywall -
> - Green Glue??? -
> - Drywall -
> - Stud wall -
> - 18" air gap -
> - Foundation wall -
> 
> Is that correct? If so, you are GTG. What you want to avoid is something you mentioned you cannot do anyway - applying drywall to the outside of the stud wall of Wall A (nearest the foundation wall). That would give you a triple-leaf situation and bad juju.
> 
> In fact, an 18" air cavity there is a bonus. You could stuff it with insulation and make it even better, but I would advise against it since it is contrary to your rule no. 1 (minimizing cost). That's a lot of insulation. Plus, it is likely unnecessary. Some insulation would be a good idea (I would say required, to reduce reverb off the concrete wall behind your screen), but you don't need 18" + 3.5" stud wall thickness worth.
> 
> 
> 
> 
> That said, the finished wall continues across my basement - to the other side - with the same amount of space running behind it the entire way. When natural gas was added years ago, they ran 2 gas lines straight through the space and secured both of them to the back of the exposed studs about 80” above grade.
> 
> Click to expand...
> 
> Ok. Now, here is the part where my antenna go up. The NG line. You MUST ensure you can access that if you ever need to. Nothing fancy, but you need a plan (at least). It doesn't have to be an easy plan, but you need a contingency plan. It's no different than if you had to rip out a wall elsewhere in your house in the future for whatever reason, except it's your HT room and this room will be built differently from the rest of your home. I would suggest that at a bare minimum you have drawings that show where things are, so you know what to do should that ever become an issue.
> 
> Also, please make sure the pipe is properly protected per code (just saying this since I don't know exactly how it's run atm).
> 
> 
> 
> 
> I am hesitant to install in-wall speakers on Wall A for obvious reasons (even will backer boxes) so the plan for now is to go with on-wall Triads for the front L-C-R.
> 
> Click to expand...
> 
> Why? You have an excellent cavity that many people would be jealous of. Speaking of which... have you considered the option of moving the wall further back toward the concrete foundation wall (obviously including moving the gas line)?
> 
> As-is, it sounds like a great space for in-wall speakers (unless I'm missing something, as previously mentioned).
> 
> 
> 
> 
> I have not given up on the possibility of in-walls behind an AT screen (if I go the PJ route) but I have to get this soundproofing issue resolved before I can even consider that. I put in a contingency for an additional 4.25" inside Wall A in the event that it is recommended that I build another wall for soundproofing. It will be virtually impossible to build another wall between the existing wall and the foundation wall due to the gas lines and a water line that run behind.
> 
> Click to expand...
> 
> And to that point, perhaps moving Wall A is not an option, period (aside from potentially being a cost you don't want to take on).
> 
> Either way, if you can fit backer boxes in the stud-Wall A, I would do it. I don't see any reason not to unless there is an encroachment where you would want to place them. BTW, I have also drunk the Triad Kool-Aid. They work very well (Triad in-walls). Speaking from experience.
> 
> 
> 
> 
> Ceiling height in the front section of the room should be somewhere around 89-90” depending on how thick I go on ceiling.
> 
> What is the best way to approach soundproofing Wall A?
> 
> Click to expand...
> 
> Ceiling height should be OK.
> 
> The big concern I have for Wall A (besides the utilities behind it) is that I would bet the wall is built like a normal house wall. Is it load bearing? I would presume not, but it's not good to be presumptuous about such things. So, here's the clincher... are you interested in building a true "room-within-a-room," or no? And if yes; clips or double stud???
> 
> See above for other suggestions on Wall A. Other than above, the usual double-drywall-Green Glue sandwich recommendation.
> 
> 
> 
> 
> Wall B
> 
> This wall is obviously yet to be constructed but it’s purpose is obviously to close off the room from the other half of the basement (and staircase). A 30” doorway will be installed in this wall with a solid core door (this will be the only door in and out of the room).
> 
> I need to break here for a late dinner, and will return w/response to remaining questions in a few. LoL.
> 
> Click to expand...
> 
> *
> 
> Click to expand...
Click to expand...


----------



## HT Geek

AnnapolisSony said:


> *Wall B*
> 
> This wall is obviously yet to be constructed but it’s purpose is obviously to close off the room from the other half of the basement (and staircase). A 30” doorway will be installed in this wall with a solid core door (this will be the only door in and out of the room).
> 
> Should I build Wall B with DD?


Yes. I would say that's a given for all internal walls. Ideally, a double wall or clips & channel as well. Insulation inside stud cavity.



> *Wall C*
> 
> This is currently the only finished wall in the room that I cannot gain access to from behind because it is the finished edge of the stairs.
> 
> Would it make any sense to add an additional layer of drywall over top of the existing drywall to give myself more mass? Building another wall in front of the existing wall is not an option here because I am very limited on width in the room and sacrificing another 4-5” is just not possible.


Yes; I would. Green Glue sandwich. Preferably with clips and channel as well if that is feasible. Insulation inside stud cavity.



> *Wall D*
> 
> Similar to Wall B above, this wall’s purpose will be to close off the room from the other side of the basement in the back of the room.
> 
> Should I build Wall D with DD as well?


Yes. Green Glue sandwich. Preferably with clips and channel as well if that is feasible (or double wall). Insulation inside stud cavity.

I would also consider doubling up drywall on the other side of the wall (with or without Green Glue).



> *Wall E*
> 
> As shown on the sketch, this wall is being modified a bit so that I can square out the back left corner of the room. Expanding that space will expose a lally column in this wall so I will most likely have to just box it out on the back wall so it is out of sight. I can access the backside of this entire wall (large unfinished storage area behind it) and I could in fact build another wall behind it. This existing wall has R11 in stud bays but does not have drywall on the backside.
> 
> What would be the best approach to soundproof Wall E?


Perhaps a double wall. It sounds as if you don't need to be concerned with sound on the other side (unfinished storage). However, you should still be concerned with flanking noise traversing upstairs. Thus, sticking with the motif of double wall (with interior wall de-coupled) and DD/GG sandwich seems prudent. Clips and channel a possibility as well if that is feasible (vs double wall).

Also seems like a good candidate area on the other side for and adjacent equipment closet. 



> *Wall F*
> 
> This wall is being slightly modified (to meet Wall E). I cannot build to much behind this wall due to the location of my gas furnace (the new wall will already be about 4-5” from it) and because we are roughing in a laundry area and powder room for construction at a later date. A 30” solid core door will be installed on this wall so that we can access the new laundry room and the storage area. This existing wall also has 3-in. R11 in stud bays but does not have drywall on the backside. I could probably add a layer of drywall (or 2) to the backside of this entire wall without too much trouble.
> 
> What would be the best approach to soundproof Wall F?


This looks like another area where preserving future access (or at least a plan for access) needs to be a focal point. I see there is also mention of a sump pump area to the NE of the diagram.

DD/GG on the inside. I suggest at least one layer (preferably 2) on the outside (laundry room side) in case you're ever doing laundry while using HT room.

Preferably double wall or clips and channel. Insulation inside stud cavity.

Looks as if the doors facing each other across the room is most practical approach from standpoint of LR ease of use/access.



> *Ceiling*
> 
> The plan is to finish the ceilings with drywall as well. Old drop ceiling and grid are down. The bays above are all insulated with R11 and, for the time being, I re-secured all insulation with new supports.
> 
> Should I consider using GG and DD (5/8”) for the finished ceilings?


Yes, I would; on clips and channel.



> And what is the recommendation for the finished ceiling/bulkhead that is only 80” off the slab in the back of the room? Would it be effective if I added another layer of 5/8” drywall over top of the existing with GG?
> 
> As shown on the drawing, a boxed out beam (1/2” DW) crosses through the middle of the room approx. 80” above grade. Is it worth wrapping this in another layer of 5/8” DW as well or just leave as is?


I would suggest to do what you can. GG + 5/8" DW, you will lose another 3/4". Not much. Given your starting point, going from 80" down to 78" or so (after flooring) is where you're going to be no matter what you do. Just how it is.



> Of course this gear list is subject to change but below is my proposed A/V gear as it stands today:
> 
> *Plan A: PJ - Researching feasibility of short-throw PJs at this time
> Plan B: SONY 85” XBR-85X900F TV
> AVR: Denon AVR-X4500H
> BR: Panasonic DP-UB820
> Power Cond: Panamax M-5300
> Amps: TBD (if necessary)
> Fronts: Triad On-wall Bronze 4 LCR x 3
> Surrounds: Triad On-wall Bronze 4 SURROUND x 2
> Rear Surrounds: Triad On-wall Bronze 4 LCR x 2
> Apple TV 4K
> Sonos Connect
> XBOX One*
> 
> Thanks in advance for your insight and opinions.


Thoughts on equipment:


PJ could be partially hidden in front of the front bulkhead.... possibly
Other option on PJ would be back wall, but you'd need a long throw
PJ would likely be too short if above the seating area... would avod placing there since it would need to shoot under bulkhead
You will need amps with those Triads to get the best performance out of them
If I understood Wall A correctly in my last post, consider going with AT screen and moving speakers and subs behind it - provided you could do a false wall for screen and decoupled wall behind them
AT screen decision depends partly on whether or not the appearance would be desirable/beneficial; might not make sense


----------



## HT Geek

ronny31 said:


> PS: I would definitely put all the equipment outside the theater, because no one wants to look at that blinky crap anymore  Also opens the possibility of using PA grade amplifiers in the future (they have noisy fans).


+1

FWIW, my room has PA amps (class AB). Class D amps are quieter, but they are not all quiet. For instance, I also have a class D amp that is not quiet either. Just don't presume any amp you get will be quiet and you won't be disappointed. LoL. 

Some people don't care about amp noise. You will generally only hear it during quiet scenes. Still, it can be annoying/distracting. In my case, I performed a fan mod on one of my amps to resolve the noisiest offender.

My rack is in the back of the room, due to architectural constraints. If I could have placed it inside a separate space with no view from the room, I would have. Almost all my controls of my system are wireless.


----------



## AnnapolisSony

HT Geek said:


> +1
> 
> FWIW, my room has PA amps (class AB). Class D amps are quieter, but they are not all quiet. For instance, I also have a class D amp that is not quiet either. Just don't presume any amp you get will be quiet and you won't be disappointed. LoL.
> 
> Some people don't care about amp noise. You will generally only hear it during quiet scenes. Still, it can be annoying/distracting. In my case, I performed a fan mod on one of my amps to resolve the noisiest offender.
> 
> My rack is in the back of the room, due to architectural constraints. If I could have placed it inside a separate space with no view from the room, I would have. Almost all my controls of my system are wireless.


 @HT Geek:

First and foremost, thank you for taking the time to respond to my post and my questions. I know it took a considerable amount of your time and I really appreciate that.

I am in the London airport right now after a family vacation to London and Copenhagen so I am just reading these posts now and will be back stateside later this evening. I am going to try to respond to your questions and your input sometime tomorrow or over the 4th holiday at the latest.

Due to another renovation project that my wife is getting ready to kick off in our kitchen, I have plenty of time to plan this room out and, most importantly, DO IT RIGHT. To say that that project is sucking funds out of my HT room project in the basement would be an understatement!   My last build took me 16 months so it won’t be the end of the world if this one takes that long as well. Although I do have a little more urgency than last time because my kids are 11 & 13 now as opposed to 5 & 7! I really want them to be able to enjoy this room with my wife and I and, most importantly, with their friends. 

Again, thank you much for your input and I look forward to continuing the conversation with you and others here on AVS. I may just start a thread soon so I don’t jam up this thread too much. If I do, I will be sure to post a link to it here.


----------



## AnnapolisSony

ronny31 said:


> Sounds like you're going to be using home grade speakers, and I assume home grade subwoofers? Then you will probably get rather standard advice. Because you won't be outputting 110db+ midbass and compression-driver high frequencies.
> 
> What's the gross height of the ceiling as is? 91 inches to the bottom of the joists? Is the area between the joists already filled with rockwool/glasswool/fiberglass insulation, and how tall are the joists? How's the floor on top of that?
> 
> A neat trick I've seen with such low ceiling is narrow-angle horns with compression drivers for LCRs, and put them high up towards the ceiling, angled down (aimed slightly lower down than the listener's head). This helped the sound quality from less ceiling reflection and reduced sound transmission to the second floor. The screen was acoustically transparent and placed very high on the wall (the top of the image was barely an inch from the ceiling). With the LCRs behind that screen. This might make it difficult to find matching side and rear speakers if you want in-wall speakers because the LCR horns will make home grade tweeters sound like an asthmatic mouse whisper. But if you already have the LCRs then I guess this is not an option.
> 
> I think if you want to make this not break the bank you should focus on the ceiling, door and ventilation. So more info on the ventilation situation would be good, so the experts on that can chime in.
> 
> PS: I would definitely put all the equipment outside the theater, because no one wants to look at that blinky crap anymore  Also opens the possibility of using PA grade amplifiers in the future (they have noisy fans).


 @ronny31:

Thx for the input. I will get back to you with some answers as well when I get back to the U.S. and behind a computer!


----------



## HT Geek

AnnapolisSony said:


> @HT Geek:
> 
> First and foremost, thank you for taking the time to respond to my post and my questions. I know it took a considerable amount of your time and I really appreciate that.
> 
> I am in the London airport right now after a family vacation to London and Copenhagen so I am just reading these posts now and will be back stateside later this evening. I am going to try to respond to your questions and your input sometime tomorrow or over the 4th holiday at the latest.
> 
> Due to another renovation project that my wife is getting ready to kick off in our kitchen, I have plenty of time to plan this room out and, most importantly, DO IT RIGHT. To say that that project is sucking funds out of my HT room project in the basement would be an understatement!   My last build took me 16 months so it won’t be the end of the world if this one takes that long as well. Although I do have a little more urgency than last time because my kids are 11 & 13 now as opposed to 5 & 7! I really want them to be able to enjoy this room with my wife and I and, most importantly, with their friends.
> 
> Again, thank you much for your input and I look forward to continuing the conversation with you and others here on AVS. I may just start a thread soon so I don’t jam up this thread too much. If I do, I will be sure to post a link to it here.


Sounds good. Have a safe return trip!

When you are back, if you could upload photos of Wall A, that would be helpful. Food for thought.


----------



## HT Geek

doveman said:


> So this is my alternative window plug approach....
> 
> 
> ...The snag with this approach is the window sill. If I have the foam squashed against that it rather undermines the whole point of having the other three sides squashed against decoupled battens.


 Unless you are going for an extreme level of detailed sound-proofing, IMHO you are probably over-thinking this issue. It's common for window plugs to have foam contacting the sides of a window cavity. The key is normally ensuring there is no flanking path by using a layered materials approach to construction, such that any seams on an outer layer are covered by an inner layer (where inner = room side of the plug). Furthermore, the mass of the inner layer should be designed to help dampen sound moving in/out of the window.

As an example, my room's window plugs consist of foam insulation on the "outside" (adjacent to the glass) that fill the entire cavity, and multiple overlapping layers of different density material on the "inside" (room side). They are effective.


----------



## AnnapolisSony

HT Geek said:


> +1
> 
> FWIW, my room has PA amps (class AB). Class D amps are quieter, but they are not all quiet. For instance, I also have a class D amp that is not quiet either. Just don't presume any amp you get will be quiet and you won't be disappointed. LoL.
> 
> Some people don't care about amp noise. You will generally only hear it during quiet scenes. Still, it can be annoying/distracting. In my case, I performed a fan mod on one of my amps to resolve the noisiest offender.
> 
> My rack is in the back of the room, due to architectural constraints. If I could have placed it inside a separate space with no view from the room, I would have. Almost all my controls of my system are wireless.


 @HT Geek,

As I mentioned, I am going to start a build thread and I am going to start it off with my original post (here) but slightly revised. In that first post you will see some answers to your questions on certain topics as well as a video walk-thru of the room that I will upload to YouTube. That video will clear a lot up as well - especially what is going OUTSIDE of the room behind the walls. I am going to shoot the vid today and hopefully get it uploaded to YT and a new thread started by this afternoon/evening. I will post a link to the thread back here - it will be called the _Belleview Park Theater Room._


----------



## barfle

*Risers on a floating floor?*

@HT Geek

I'm just starting a new HT build, and I intend to put in a floating floor, probably OSB over a foam pad, but I'm not sure how to go about putting in a riser for the second row. Should I put in the floating floor, then install the riser over it, or install the riser on the existing subfloor and float the surface of the riser?

The room is over a garage, so my purpose is to keep the sound out of the HT. 

Thanks in advance!


----------



## HT Geek

barfle said:


> @HT Geek
> 
> I'm just starting a new HT build, and I intend to put in a floating floor, probably OSB over a foam pad, but I'm not sure how to go about putting in a riser for the second row. Should I put in the floating floor, then install the riser over it,


YES

When you say "foam pad," what do you mean exactly? Do you have a particular product in mind? If so, what is it?



> or install the riser on the existing subfloor and float the surface of the riser?


NO



> The room is over a garage, so my purpose is to keep the sound out of the HT.


Gotcha. What sort of sounds do you wish to prevent emanating from the garage into the HT room? Is there an electric garage door opener beneath your future HT room? Are your garage doors metal or wood? Are they relatively heavy? How many garage door openers are in your garage? Do you have any beams in the garage? What's the floor of the future HT room/ceiling of garage like? Trusses???


----------



## AnnapolisSony

My apologies if this has been asked before but can someone recommend where to purchase clips and channel in the MD/DC/VA area? I am not quite at that point yet but it is something that I would like to add into my construction budget. Or is this something that is typically ordered online and shipped?

I am sure there are many diff. varieties of clips and channel out there as well so feel free to recommend away. I am located in the Annapolis area halfway between Baltimore and DC (30 min drive to each). Thanks in advance!


----------



## Sundodger

New question - I'm curious about your experience soundproofing for serious bass. 

On my next dedicated theater build (still in planning stage, probably ~2000 cu.ft.; sealed, dedicated room) I am thinking about a couple DIY subs (18"s?). This will be a LOT stronger than my previous theater (well soundproofed with help from SoundproofingCompany, but only had a couple cheap 10" subs) and I worry about WAF from noise leakage and being able to watch movies at all after bedtime.

I am familiar with the standard techniques and likely will employ decoupled walls, DD w/ GG, clips and channels for ceiling (DDGG too), etc, but I guess I just want to know if those measures allow for some serious bass. This will be a basement build down to foundation and exposed ceiling.

Thanks!


----------



## Mr.Guvernment

So, question because i can not seem to find a definitive, or any answer. Duct work, bunch of it is mounted almost center in the joist, so my insulation wil either fit above it or below it.

Is it safe to have pink fluffy insulation making direct contact with duct work?


----------



## niccolo

I'm working on a poor man's home theater and music room on the second floor of a wood framed house, above the master suite. I'm not doing anything approaching proper room-within-a-room construction. 

But I am thinking of putting down a layer of rubber (e.g. horse stall mat) and floating another subfloor (OSB or plywood or higher-density fiberboard) over that, as a way to reduce sound transmission into the master suite below and other parts of the house. I'm cognizant that with untreated walls and ceiling, this is likely to yield only modest improvements in sound isolation, but my guess is it's worthwhile nonetheless. Comments on that welcome.

Secondarily, there is no insulation between the first and second floor, and I'm wondering whether it makes sense to blow something fluffy into the cavities below the home theater/music room to reduce the drum-like resonance of those enclosed spaces and improve sound isolation. We have engineered joists, I think every 16", so I'd need to cut an access port in the subfloor between each joist to blow insulation in. Again, the question is whether the labor and cost of doing this are warranted.

So I guess there are three options:

1) Just put hardwood over an underlayment or carpet over a pad down on the existing subfloor.

2) Put a layer of thicker rubber down and float a second subfloor and put either hardwood/underlayment or carpet/pad over that.

3) In addition to rubber and second subfloor, also blow fluffy stuff into the cavities in the floor.

Obviously there are escalating costs (money and time) associated with these options, so the question, which I recognize is hard to answer, is what's worth it. Comments welcome!


----------



## barfle

*Thanks for the advice!*



HT Geek said:


> When you say "foam pad," what do you mean exactly? Do you have a particular product in mind? If so, what is it?


I'm probably going to be using two layers of carpet padding, the densest I can get. There's already one layer in the room, which is a chopped-up foam rubber. It's definitely not the crummy little bubble stuff.



HT Geek said:


> What sort of sounds do you wish to prevent emanating from the garage into the HT room?


The furnace is in there, and the garage door openers (2). The doors are metal. Of course, cars, although it's likely I'll be in one of the cars when it's moving in or out.



HT Geek said:


> Do you have any beams in the garage?


There's nothing that shows in the garage - it has a drywall ceiling with the GDOs hanging from it and a few lights.



HT Geek said:


> What's the floor of the future HT room/ceiling of garage like?


The floor is OSB with a pad and carpet. I'll be removing the carpet to put the extra soundproofing and riser in, as well as shelves for a fairly extensive record collection and the standard (and a little non-standard) equipment.



HT Geek said:


> Trusses???


The room is built with "bonus room" trusses. They're pretty heavy (at least 2x8s and maybe 2x12s - I'll check tomorrow) with fiberglass insulation between the joists. Right now, the GDOs make the most noise if it's not me in the garage. But I have a report that the vacuum cleaner running in the theater room is quite noticeable in the garage if there's no other noises.

Thanks for the advice. I'm a little concerned (which is not quite worried) about the floor load I'll be putting in the room. The garage span is three cars wide and 27' deep, but I've poked around in the crawl spaces beside the room and there's a lot of wood there!


----------



## HT Geek

barfle said:


> I'm probably going to be using two layers of carpet padding, the densest I can get. There's already one layer in the room, which is a chopped-up foam rubber. It's definitely not the crummy little bubble stuff.
> 
> The furnace is in there, and the garage door openers (2). The doors are metal. Of course, cars, although it's likely I'll be in one of the cars when it's moving in or out.
> 
> There's nothing that shows in the garage - it has a drywall ceiling with the GDOs hanging from it and a few lights.
> 
> The floor is OSB with a pad and carpet. I'll be removing the carpet to put the extra soundproofing and riser in, as well as shelves for a fairly extensive record collection and the standard (and a little non-standard) equipment.
> 
> The room is built with "bonus room" trusses. They're pretty heavy (at least 2x8s and maybe 2x12s - I'll check tomorrow) with fiberglass insulation between the joists. Right now, the GDOs make the most noise if it's not me in the garage. But I have a report that the vacuum cleaner running in the theater room is quite noticeable in the garage if there's no other noises.
> 
> Thanks for the advice. I'm a little concerned (which is not quite worried) about the floor load I'll be putting in the room. The garage span is three cars wide and 27' deep, but I've poked around in the crawl spaces beside the room and there's a lot of wood there!



Thanks for the info. Thoughts/feedback. I am presuming you float the floor in the HT room and use either clips & channel on the walls or double stud wall.

First off, don't worry about the trusses and their load bearing capabilities unless you are going to extreme lengths of adding lots of weight up there. They should be rated for over 50 psf for that room, plus a margin. Now, having said that.... Don't be surprised if you notice some cracks in a few places during or post-construction. Notably, 



exterior wall of the room if your home's exterior is stone
ceiling of your garage (cracks along drywall seams)
less likely: garage floor

If you see those, do not panic! This is normal. You have to realize your house has already settled, but you are about to restart the construction process, and adjustments to weight here and there will shift things around. This does not mean it's not structurally sound (it is). This means the load balancing in that part of your home will shift, and because the rest of the home doesn't need to do that, sometimes people notice these minor changes. Do not get alarmed if you do as well. The biggest hassle is the cosmetic fixes to drywall tape/mud if the ceiling sheets in the garage form cracks. Also, you likely won't notice any of this for months, if it happens at all. 

One more area where you *might* see a change is with your headers over the garage door entrance. They may bow very slightly in the center, again due to the shift in weight and the fact there is a lot of stress on those beams. That is a non-issue unless you begin to get an inordinate amount of flex (exact amount of what that means depends on the span). I'll skip the civil engineering discussion on that for the moment. LoL. Point is... this is again something that is common, even in new homes, so a small amount of flex is not going to raise any alarm bells. But you are adding more weight, so don't be surprised if you see this happen over time. You may never notice this, or you may notice it years later.

None of those alerts for you above will be sudden. They may or may not show up over time. Sometimes, during construction you will find cracks forming along the garage ceiling. That's just because you are banging the heck out of the structure up there. Again, not something to be concerned about other than cosmetics (but don't fix it until a few months after the room is finished, or you will probably need to re-fix it).

Now, let's talk about sound in the HT room from the garage:



If you can currently hear/feel the GDOs (Garage Door Openers) in your future HT room, you will likely continue to do so post-construction, but they will be less pronounced
Below in the garage, you will hear bass from the HT room
You should not hear the sound of vehicles (unless they have the windows open and blaring music very loudly, plus a quiet scene in the HT room... then perhaps you might)
You will still hear vacuuming in the HT room (below, from inside the garage), but it will be muffled
The worst part is going to be the GDOs. Since your garage doors are metal, they are not as heavy as wood doors and that is a plus. It means you *could* install quieter GDOs if they aren't already quiet (e.g. screw drive instead of chain driven). I'm ad-libbing a bit here since I know nothing about what sort of GDOs you have currently, nor your exact weight of your garage doors. I'm just going on experience here re: typical U.S. home.

How important is blocking all sound and vibration from the garage into the HT room? Is it a priority? Or not a huge issue? If it is a priority and you want true silence, you will have to kick-it-up-a-notch on the flooring. If you're OK with what I've described above, then with regards to the garage you'll be GTG.


----------



## niccolo

niccolo said:


> I'm working on a poor man's home theater and music room on the second floor of a wood framed house, above the master suite. I'm not doing anything approaching proper room-within-a-room construction.
> 
> But I am thinking of putting down a layer of rubber (e.g. horse stall mat) and floating another subfloor (OSB or plywood or higher-density fiberboard) over that, as a way to reduce sound transmission into the master suite below and other parts of the house. I'm cognizant that with untreated walls and ceiling, this is likely to yield only modest improvements in sound isolation, but my guess is it's worthwhile nonetheless. Comments on that welcome.
> 
> Secondarily, there is no insulation between the first and second floor, and I'm wondering whether it makes sense to blow something fluffy into the cavities below the home theater/music room to reduce the drum-like resonance of those enclosed spaces and improve sound isolation. We have engineered joists, I think every 16", so I'd need to cut an access port in the subfloor between each joist to blow insulation in. Again, the question is whether the labor and cost of doing this are warranted.
> 
> So I guess there are three options:
> 
> 1) Just put hardwood over an underlayment or carpet over a pad down on the existing subfloor.
> 
> 2) Put a layer of thicker rubber down and float a second subfloor and put either hardwood/underlayment or carpet/pad over that.
> 
> 3) In addition to rubber and second subfloor, also blow fluffy stuff into the cavities in the floor.
> 
> Obviously there are escalating costs (money and time) associated with these options, so the question, which I recognize is hard to answer, is what's worth it. Comments welcome!



Hoping HTGeek, Big, or others might weigh in. And to modify the above slightly: I _did_ built a new wall to enclose a loft space and create the room with staggered studs, double drywall on the inside, and Green Glue between the double drywall. But the existing walls weren't modified. My thinking on doing soundproofing in the new wall is that 1) since I was building the wall anyway, the marginal cost of some soundproofing wasn't that high; 2) it gives me the option of going back and doing the other room walls and ceiling properly in future; and 3) the new wall separates the room from the interior of the house, whereas the existing walls separate it from the outside of the house. That only goes so far, obviously, because the framing will still transmit sound to other rooms in the house. But it seemed worth clarifying for anyone (like Big and HTGeek) who helpfully advised me when I was debating how to construct the new wall.


----------



## barfle

*Good info!*



HT Geek said:


> Thanks for the info. Thoughts/feedback. I am presuming you float the floor in the HT room and use either clips & channel on the walls or double stud wall.


The nice thing about this room is that it shares no walls with other rooms. It is entirely above the garage, and is in sort of a "gable" with a window over the garage doors. There's a small hallway entering the room that shares a fairly small wall with the master bedroom, and I'll probably fill that up with insulation and a sound-isolating board. There might be room to stagger-stud that wall. It's about 8' by 8', and I'm also planning on a recording studio door between the room and the little hall. There's a good 8 to 10 feet between the wall of the theater room and an adjacent bedroom. Yeah, drawings would help, but I'm still moving in and I have no idea what pile of stuff my scanner is in!



HT Geek said:


> First off, don't worry about the trusses and their load bearing capabilities unless you are going to extreme lengths of adding lots of weight up there. They should be rated for over 50 psf for that room, plus a margin. Now, having said that.... Don't be surprised if you notice some cracks in a few places during or post-construction. Notably,
> 
> 
> 
> exterior wall of the room if your home's exterior is stone
> ceiling of your garage (cracks along drywall seams)
> less likely: garage floor


The exterior is a painted hardboard faux siding, so that's not going to be a problem. The ceiling of the garage is drywall and it looks like crap, but I'll hold off on tidying that up until spring maybe.




HT Geek said:


> Now, let's talk about sound in the HT room from the garage:
> 
> If you can currently hear/feel the GDOs (Garage Door Openers) in your future HT room, you will likely continue to do so post-construction, but they will be less pronounced
> Below in the garage, you will hear bass from the HT room
> You should not hear the sound of vehicles (unless they have the windows open and blaring music very loudly, plus a quiet scene in the HT room... then perhaps you might)
> You will still hear vacuuming in the HT room (below, from inside the garage), but it will be muffled


 I'm not all that worried about what sound leaks into the garage, because nobody is going to be doing serious listening in there. It wouldn't surprise me if my wife opened the door while I'm using the room, but the noise won't last all that long, after all.



HT Geek said:


> The worst part is going to be the GDOs. Since your garage doors are metal, they are not as heavy as wood doors and that is a plus. It means you *could* install quieter GDOs if they aren't already quiet (e.g. screw drive instead of chain driven). I'm ad-libbing a bit here since I know nothing about what sort of GDOs you have currently, nor your exact weight of your garage doors. I'm just going on experience here re: typical U.S. home.


There's a two-car door and a one-car door. The openers are hung from steel angle lagged into the joists. They are chain drive, fairly noisy but again, it won't be lasting very long.



HT Geek said:


> How important is blocking all sound and vibration from the garage into the HT room? Is it a priority? Or not a huge issue? If it is a priority and you want true silence, you will have to kick-it-up-a-notch on the flooring. If you're OK with what I've described above, then with regards to the garage you'll be GTG.


I'm already thrilled about the space I have available. In my previous house, I had a tiny bedroom in the basement, and the SAF for the subwoofer was minimal. This house I intend to do a better job of isolating the room (and no doubt making several mistakes, but I'm here trying to keep that down to a dull roar). I'm going to have a few HVAC issues, but noise from the unit doesn't seem a problem - it's hiding the registers! I have a few ideas, which may end up as plans, and then built.


----------



## HT Geek

niccolo said:


> Hoping HTGeek, Big, or others might weigh in. And to modify the above slightly: I _did_ built a new wall to enclose a loft space and create the room with staggered studs, double drywall on the inside, and Green Glue between the double drywall. But the existing walls weren't modified. My thinking on doing soundproofing in the new wall is that 1) since I was building the wall anyway, the marginal cost of some soundproofing wasn't that high; 2) it gives me the option of going back and doing the other room walls and ceiling properly in future; and 3) the new wall separates the room from the interior of the house, whereas the existing walls separate it from the outside of the house. That only goes so far, obviously, because the framing will still transmit sound to other rooms in the house. But it seemed worth clarifying for anyone (like Big and HTGeek) who helpfully advised me when I was debating how to construct the new wall.


Well, I hate to say this, but from your description the improvements you are suggesting are likely to disappoint when it comes to sound transmission between the man-cave and master bedroom below. Damping joists or trusses between floors (from above) and achieving a notable difference in attenuation is quite a challenge in general. They are efficient at carrying vibration, unfortunately (especially up and down). Not suggesting you don't do anything, but trying to prep you for potential disappointment. It depends very much on how your home is built; what type of beams and supports exist and where they are, what's connected to them, etc. Even though homes are mostly built in the same pattern, the weak points and transmission routes vary depending on where all the parts line up.

Now, with regards to side-to-side vibrations and sound transmission along the floor (i.e. on upper level), you should notice a bigger gain from floor treatments. I fear flanking noise is going to overcome any benefits between floors, and you might not even perceive a benefit at all (in room below).

If you want to improve your chances, you'd need to look at using something like a 2-4" thick Kinetics RIM product. The thicker the better. They manufacture one specifically for wood floors.

Regarding blowing in insulation between floors.... Unless you specifically want to focus on mitigating higher frequency sound transmission between floors (e.g. voices and higher pitches), I'm not sure i'd bother. In and of itself, it won't affect the LFE at all under your circumstances. Cumulatively with a floating floor, I don't think it's worth the effort given the bigger picture. However, if impact noise is a concern then I would reconsider doing it after all (e.g. high heels on hardwood floor). Again though, the real benefit would be minimal and I'm not so sure the cost would be worthwhile (probably not).

If you have the $ to blow (pun intended) on insulation, find out what a suitable roll of RIM would cost and consider going the latter route instead and skipping the insulation between floors. But before you spend $ on either one, ask yourself if it's still worthwhile if your perception of the final result is that it hasn't appreciably improved the situation. Unless you have plans for a re-do in the future with more involved soundproofing methods, I would stick with a minimalist approach (cost and time).

Hate to say all that, but endeavouring to be realistic here.


----------



## HT Geek

barfle said:


> I'm going to have a few HVAC issues, but noise from the unit doesn't seem a problem - it's hiding the registers! I have a few ideas, which may end up as plans, and then built.


Sounds good. Let us know when you're able to start a build thread. 

Regarding HVAC... climate control is very important. Make sure you give it due consideration. Take a look at linear diffusers for registers/vents. They look nice, blend in well, and function well. Your best bet is to order custom-sized ones to fit your needs. HVAC is often one of the most complex pieces of the puzzle, especially when converting unfinished to finished space.


----------



## Ladeback

Mr.Guvernment said:


> So, question because i can not seem to find a definitive, or any answer. Duct work, bunch of it is mounted almost center in the joist, so my insulation wil either fit above it or below it.
> 
> Is it safe to have pink fluffy insulation making direct contact with duct work?
> 
> https://www.youtube.com/watch?v=GLjhrXFo0Kw


I don't think having the insulation touch the duct work would be an issue, but not sure it is going to help that much. Are you talking about adding insulation around duct supply runs in you joist? Then yes that is done a lot. If you are concerned about sound from the lines you can put them in duct mufflers and replace the metal ducts with flexible ducts.

I watched the video you posted and one thing I would not do that he did in the video is to build a wall, put drywall on it then built another wall in front of it with a small gap. That will cause a triple leaf effect. Building to walls is good, but don't put drywall between the tow walls. Also better to decouple the wall inside the room at the top from the joist with clips so sound doesn't travel up so easily.

This is a good read and they are very helpful if you have questions.
https://www.soundproofingcompany.com/soundproofing101


----------



## niccolo

HT Geek said:


> Well, I hate to say this, but from your description the improvements you are suggesting are likely to disappoint when it comes to sound transmission between the man-cave and master bedroom below. Damping joists or trusses between floors (from above) and achieving a notable difference in attenuation is quite a challenge in general. They are efficient at carrying vibration, unfortunately (especially up and down). Not suggesting you don't do anything, but trying to prep you for potential disappointment. It depends very much on how your home is built; what type of beams and supports exist and where they are, what's connected to them, etc. Even though homes are mostly built in the same pattern, the weak points and transmission routes vary depending on where all the parts line up.
> 
> Now, with regards to side-to-side vibrations and sound transmission along the floor (i.e. on upper level), you should notice a bigger gain from floor treatments. I fear flanking noise is going to overcome any benefits between floors, and you might not even perceive a benefit at all (in room below).
> 
> If you want to improve your chances, you'd need to look at using something like a 2-4" thick Kinetics RIM product. The thicker the better. They manufacture one specifically for wood floors.
> 
> Regarding blowing in insulation between floors.... Unless you specifically want to focus on mitigating higher frequency sound transmission between floors (e.g. voices and higher pitches), I'm not sure i'd bother. In and of itself, it won't affect the LFE at all under your circumstances. Cumulatively with a floating floor, I don't think it's worth the effort given the bigger picture. However, if impact noise is a concern then I would reconsider doing it after all (e.g. high heels on hardwood floor). Again though, the real benefit would be minimal and I'm not so sure the cost would be worthwhile (probably not).
> 
> If you have the $ to blow (pun intended) on insulation, find out what a suitable roll of RIM would cost and consider going the latter route instead and skipping the insulation between floors. But before you spend $ on either one, ask yourself if it's still worthwhile if your perception of the final result is that it hasn't appreciably improved the situation. Unless you have plans for a re-do in the future with more involved soundproofing methods, I would stick with a minimalist approach (cost and time).
> 
> Hate to say all that, but endeavouring to be realistic here.



Appreciate the thoughts.

My goal is to attenuate sound at all frequencies, not just bass. It would be nice, for example, to be able to listen to music or watch a movie or TV with my tower speakers, minus the sub, and not bleed a lot of sound into the rest of the house. (Separately, I wonder if I could set up different modes on my AVR so that I had a movie mode that used the sub and another one for music that didn't. But I'm also prepared to use headphones at times.) I don't really care about footfall noise, it's music and movie noise I'm trying to contain.

I have a bare subfloor now, so I'm in a position to do something fairly easily. My hunch has been that putting down a layer of horse stall rubber, and floating another subfloor over that, before putting down either carpet or hardwood, was pretty cost effective and likely to make a meaningful difference. I get that the exterior walls that are untreated, and the untreated ceiling (above which is an attic) will send a considerable amount of low frequency sound into the framing, though my guess is even there a floating floor would make a significant difference. The higher the frequency got, the more I'm guessing the floating floor would help. But I'm open to being persuaded it's not worth the effort and cost to do the floating floor.

My hunch is that something like RIM adds a lot of cost over something like horse stall mat, so that becomes even harder to justify under the circumstances. Any sense of where to look for prices on the RIM stuff?

On blowing fluffy insulation into the cavities between the floor joists, my guess is the difference would be minimal and it's probably not worth the cost and effort, whether I float a subfloor or not.


----------



## Mr.Guvernment

Ladeback said:


> I don't think having the insulation touch the duct work would be an issue, but not sure it is going to help that much. Are you talking about adding insulation around duct supply runs in you joist? Then yes that is done a lot. If you are concerned about sound from the lines you can put them in duct mufflers and replace the metal ducts with flexible ducts.
> 
> I watched the video you posted and one thing I would not do that he did in the video is to build a wall, put drywall on it then built another wall in front of it with a small gap. That will cause a triple leaf effect. Building to walls is good, but don't put drywall between the tow walls. Also better to decouple the wall inside the room at the top from the joist with clips so sound doesn't travel up so easily.
> 
> This is a good read and they are very helpful if you have questions.
> https://www.soundproofingcompany.com/soundproofing101


Hello,

Thanks for the reply. This is solely just to get insulation in the joist and the vent runs down almost the middle in height. I wanted to be sure that the insulation touching the duct wasn't a possible fire hazard once the ceiling is all sealed up. There is about 6 inches above the duck so the insulation is not too compact, otherwise i could shape the insulation around it better cutting down the middle of the insulation and almost wrapping it around the duct.


----------



## HT Geek

niccolo said:


> Appreciate the thoughts.
> 
> My goal is to attenuate sound at all frequencies, not just bass. It would be nice, for example, to be able to listen to music or watch a movie or TV with my tower speakers, minus the sub, and not bleed a lot of sound into the rest of the house. (Separately, I wonder if I could set up different modes on my AVR so that I had a movie mode that used the sub and another one for music that didn't. But I'm also prepared to use headphones at times.) I don't really care about footfall noise, it's music and movie noise I'm trying to contain.
> 
> I have a bare subfloor now, so I'm in a position to do something fairly easily. My hunch has been that putting down a layer of horse stall rubber, and floating another subfloor over that, before putting down either carpet or hardwood, was pretty cost effective and likely to make a meaningful difference. I get that the exterior walls that are untreated, and the untreated ceiling (above which is an attic) will send a considerable amount of low frequency sound into the framing, though my guess is even there a floating floor would make a significant difference. The higher the frequency got, the more I'm guessing the floating floor would help. But I'm open to being persuaded it's not worth the effort and cost to do the floating floor.



Yes, it will help more with higher freqs vs. LFE. 



> My hunch is that something like RIM adds a lot of cost over something like horse stall mat, so that becomes even harder to justify under the circumstances. Any sense of where to look for prices on the RIM stuff?


Horse stall mats and rubber mats in general are helpful, and they will mitigate some of the sound. However, loud and deep bass is going to pass through easily. It's really tough to say ahead of time if you'll be satisfied with the result. I can tell you IMHO, with a 2nd floor theater room, the floor in the HT room is the biggest challenge. Your best bet with that floor would be to rip out the sub-floor and de-couple the room's floor. I know that is a huge pain and easier said than done.

Presuming you don't do that, even with a floating floor, you're going to get considerable pass-thru sound (LFE in particular). Lay down a double-layer osb/rubber/osb/rubber combination (or similar) if you have the means. Anything you do above and beyond a normal floor will help. Thick carpet pad would be helpful as well. Just don't expect a miracle.  

You'd have to contact Kinetics and ask them if they have a reseller local to you, or if they would sell direct. It's not cheap, but thought I'd throw that out as an option.



> On blowing fluffy insulation into the cavities between the floor joists, my guess is the difference would be minimal and it's probably not worth the cost and effort, whether I float a subfloor or not.



I concur.


----------



## HT Geek

Ladeback said:


> I don't think having the insulation touch the duct work would be an issue, but not sure it is going to help that much. Are you talking about adding insulation around duct supply runs in you joist? Then yes that is done a lot. If you are concerned about sound from the lines you can put them in duct mufflers and replace the metal ducts with flexible ducts.
> 
> I watched the video you posted and one thing I would not do that he did in the video is to build a wall, put drywall on it then built another wall in front of it with a small gap. That will cause a triple leaf effect. Building to walls is good, but don't put drywall between the tow walls. Also better to decouple the wall inside the room at the top from the joist with clips so sound doesn't travel up so easily.
> 
> This is a good read and they are very helpful if you have questions.
> https://www.soundproofingcompany.com/soundproofing101


Glad you re-posted that. I had not seen that video. That is a mix of good and bad info. He doesn't apply the GG to spec either, though I would not fault him for that as there is some debate over whether the manufacturer's spec is necessary or overkill.

Agreed that insulation around the supply HVAC runs is - generally speaking - not an issue. In fact, it is encouraged, presuming it's done properly (which is more a function of the ductwork and not the insulation itself).


----------



## Mr.Guvernment

HT Geek said:


> Glad you re-posted that. I had not seen that video. That is a mix of good and bad info. He doesn't apply the GG to spec either, though I would not fault him for that as there is some debate over whether the manufacturer's spec is necessary or overkill.
> 
> Agreed that insulation around the supply HVAC runs is - generally speaking - not an issue. In fact, it is encouraged, presuming it's done properly (which is more a function of the ductwork and not the insulation itself).



Good to know, why I never like to rely on 1 single source of truth, also trying to find things that apply to Canadian code as well vs U.S Code.

For the insulation,based on my picture, would i be better off to cut down the middle of that insulation and have it more "wrap" over/under the duct work vs having it slightly compressed above it? The insulation is 6" thick it notes, but above the duct it may be compressed down a bit to more like 5".


----------



## niccolo

HT Geek said:


> Yes, it will help more with higher freqs vs. LFE.
> 
> 
> Horse stall mats and rubber mats in general are helpful, and they will mitigate some of the sound. However, loud and deep bass is going to pass through easily. It's really tough to say ahead of time if you'll be satisfied with the result. I can tell you IMHO, with a 2nd floor theater room, the floor in the HT room is the biggest challenge. Your best bet with that floor would be to rip out the sub-floor and de-couple the room's floor. I know that is a huge pain and easier said than done.
> 
> Presuming you don't do that, even with a floating floor, you're going to get considerable pass-thru sound (LFE in particular). Lay down a double-layer osb/rubber/osb/rubber combination (or similar) if you have the means. Anything you do above and beyond a normal floor will help. Thick carpet pad would be helpful as well. Just don't expect a miracle.
> 
> You'd have to contact Kinetics and ask them if they have a reseller local to you, or if they would sell direct. It's not cheap, but thought I'd throw that out as an option.
> 
> 
> 
> 
> I concur.



Why would ripping out the existing subfloor and decoupling a new subfloor from the joists necessarily be better than leaving the existing subfloor and decoupling it from a secondary subfloor laid over it?


My impression is that the primary reason _not_ to put down a secondary decoupled subfloor is that I've got some untreated walls that will create a flanking issue, especially for lower frequency sound.


And if I had to guess, putting down rubber-second subfloor-rubber-third subfloor would yield only marginal improvements over the more basic rubber-second subfloor. If anything, if I were looking for a more involved floor treatment, I'd think rubber-second subfloor-Green Glue-additional subfloor sandwich would be a better bet, creating a single more massive suspended subfloor and damping it to boot. Anyway, this is all hypothetical, because if the case for a simpler floor treatment is tenuous, it's all the more so for a more involved treatment.


----------



## HT Geek

niccolo said:


> Why would ripping out the existing subfloor and decoupling a new subfloor from the joists necessarily be better than leaving the existing subfloor and decoupling it from a secondary subfloor laid over it?
> 
> My impression is that the primary reason _not_ to put down a secondary decoupled subfloor is that I've got some untreated walls that will create a flanking issue, especially for lower frequency sound.
> 
> And if I had to guess, putting down rubber-second subfloor-rubber-third subfloor would yield only marginal improvements over the more basic rubber-second subfloor. If anything, if I were looking for a more involved floor treatment, I'd think rubber-second subfloor-Green Glue-additional subfloor sandwich would be a better bet, creating a single more massive suspended subfloor and damping it to boot. Anyway, this is all hypothetical, because if the case for a simpler floor treatment is tenuous, it's all the more so for a more involved treatment.


It's a matter of degree. As in... to what degree you think you want to mitigate sound leaving or entering the HT room, and to what degree you are willing to invest the money and/or time in attaining the goal? And of course, what are the ramifications if you miss your goal?

Your floor is the biggest surface that is going to resonate most directly toward the area in which you (I believe) would prefer to mitigate sound traveling (i.e. to the room below). 

Yes, you're still going to have side-flanking issues. I was thinking of ideals (re: floor). If you are directly below the room, you will hear it better than almost anywhere else in the house.

Are you thinking it's not worth it to invest a lot of effort into the floor because you've already decided not to go all out with the walls and ceiling? I'd say it's a reasonable argument to ask whether it's worth bothering with just one surface if you're not truly addressing the other surfaces. But, again it's a factor of degree. You *might* get some benefits through partial treatments here and there, but then again it might be a waste of time and resources. There's really no way to know unless you're going to try and conduct a true A/B test (almost impossible outside a lab).

Perhaps we are splitting hairs here, but I was just trying to point out that unless you are willing to go to extremes, the benefits (re: floor) are going to be very limited no matter what you do.


----------



## HT Geek

Mr.Guvernment said:


> Good to know, why I never like to rely on 1 single source of truth, also trying to find things that apply to Canadian code as well vs U.S Code.
> 
> For the insulation,based on my picture, would i be better off to cut down the middle of that insulation and have it more "wrap" over/under the duct work vs having it slightly compressed above it? The insulation is 6" thick it notes, but above the duct it may be compressed down a bit to more like 5".


Cut it and wrap it. You should avoid compressing it. 

I'll try and give you a brief primer on the relevant theory. Insulation - when loosely packed - reduces the velocity of sound waves traveling through it (good for HT rooms). However, if you squish that insulation together and compress it, then it functions more like a solid, which tends to be better at resonating (conducting) sound (bad for HT rooms).

Likewise, loose insulation around your HVAC ducts will help to muffle any normal operating noise emanating from them, and help keep sound in your room from vibrating the ducts.


----------



## Mr.Guvernment

HT Geek said:


> Cut it and wrap it. You should avoid compressing it.
> 
> I'll try and give you a brief primer on the relevant theory. Insulation - when loosely packed - reduces the velocity of sound waves traveling through it (good for HT rooms). However, if you squish that insulation together and compress it, then it functions more like a solid, which tends to be better at resonating (conducting) sound (bad for HT rooms).
> 
> Likewise, loose insulation around your HVAC ducts will help to muffle any normal operating noise emanating from them, and help keep sound in your room from vibrating the ducts.


Perfecto! Shall cut and wrap where needed!


----------



## ckronengold

*Soundproofing an Existing Finished Basement*

Thanks to some sloppy craftsmanship and general shortcut-taking, I'm looking at needing to tear down my HVAC soffit and the surrounding ceiling to replace some HVAC ducts. 

As long as I'm going to be tearing "some" down, I'm considering whether I should tear the whole thing down and do some soundproofing. 

Room is 7'2" high, so I'm not sure I can even consider decoupling and using double sheetrock / green glue. At a bare minimum, I know I can at least use Roxsul to fill the cavities, despite knowing this isn't a very good solution at all. 

There's current zero insulation between floors. But there's also plumbing and electrical to consider. My primary consideration is limiting sound from the basement leaking upstairs. I'm not too concerned about impact noise from the floor above. 

Wondering if this fine forum might have some tips on how to think about the issue and get the wife on-board.


----------



## Harkon

Simple question (I hope).

If you double layer plasterboard or, as I’m planning, OSB then Plasterboard, how do you fix the second layer? 

Presumably the uprights at 16’’ centres and associated noggins are correctly placed for the first layer. If you stagger the layers then the second layer will miss the studs. 

If I use OSB, can I fix the plasterboard layer to the OSB or does it need to fit a stud? 

No channel etc involved as it’s an isolated stud frame.


----------



## warwwolf7

Harkon said:


> Simple question (I hope).
> 
> If you double layer plasterboard or, as I’m planning, OSB then Plasterboard, how do you fix the second layer?
> 
> Presumably the uprights at 16’’ centres and associated noggins are correctly placed for the first layer. If you stagger the layers then the second layer will miss the studs.
> 
> If I use OSB, can I fix the plasterboard layer to the OSB or does it need to fit a stud?
> 
> No channel etc involved as it’s an isolated stud frame.


Hi,
With 2layers of drywall, both layer have to hit the channel or 2x4 or 2x10 behind the 1rst layer. You have to carefully mark them. The cnrc have a example of the screw pattern they used for their testing of the wall isolation. Look it up.

With osb as the first layer, I think you still should screw the 2nd layer directly into the joist to avoid any sagging. It's even more important if you are using hats and channel because the connection of screws and channel are not that strong. On the walls you could screw the 2nd layer with no respect to where your studs are behind because the lateral force are very little. 

Now the fun thing with 1layer osb is that you can add anything and screw anywhere and it will hold. 

It takes a little bit more time to do properly, but I the end, I think it's worth not having to fix it. 

-Matt


----------



## HT Geek

Harkon said:


> If you double layer plasterboard or, as I’m planning, OSB then Plasterboard, how do you fix the second layer?


You still need to screw it into the studs. Alternate your screw offset. Ceilings normally have more screws, but depends on the installer.

Either way, as an example, offset 6" from ceiling and put a screw every 12" or so. Then on your 2nd layer, start at a 2 or 3 inch offset and alternate 12". Using that technique, you can use fewer screws in the 1st sheet if you like since the 2nd layer screws go through the first. 1" + drywall thickness for 1st layer and (+ drywall thickness for 2nd layer). Figure 1-5/8" and 2-1/2" screws respectively, or perhaps something close in wood screws for first layer. Drywall screws usually work well enough tho under the circumstances (1st layer). Make sure you dimple the 2nd layer screws. There are special drill bits you can find that make it easier.



> If you stagger the layers then the second layer will miss the studs.


You just need to line everything up where you can. If you use enough screws where there are studs, it won't be an issue. Use some extra screws if you have fewer joists to attach to.



> If I use OSB, can I fix the plasterboard layer to the OSB or does it need to fit a stud?


Yes, it still should be attached directly to a stud. BTW, using OSB for the 1st layer is more challenging than it might seem beforehand. It's more difficult to cut and line up compared with drywall, and it's more challenging to create smooth seams. I would recommend staggering the drywall over top of it.

Also, it does not help you from a sound proofing standpoint. There is a benefit to hanging things, as you mentioned.


----------



## HT Geek

ckronengold said:


> Thanks to some sloppy craftsmanship and general shortcut-taking, I'm looking at needing to tear down my HVAC soffit and the surrounding ceiling to replace some HVAC ducts.
> 
> As long as I'm going to be tearing "some" down, I'm considering whether I should tear the whole thing down and do some soundproofing.
> 
> Room is 7'2" high, so I'm not sure I can even consider decoupling and using double sheetrock / green glue. At a bare minimum, I know I can at least use Roxsul to fill the cavities, despite knowing this isn't a very good solution at all.
> 
> There's current zero insulation between floors. But there's also plumbing and electrical to consider. My primary consideration is limiting sound from the basement leaking upstairs. I'm not too concerned about impact noise from the floor above.
> 
> Wondering if this fine forum might have some tips on how to think about the issue and get the wife on-board.


There's a lot of, "Well, it depends..." thoughts going through my head based on your comments. If you're looking for general advice, I would suggest you stuff some "pink fluffy" insulation in there after you complete repairs rather than Roxul. It's cheaper and more malleable in that type of situation.

If it's unclear what you are going to do with this space in the future, I'd stop there for now.


----------



## ckronengold

HT Geek said:


> ckronengold said:
> 
> 
> 
> As long as I'm going to be tearing "some" down, I'm considering whether I should tear the whole thing down and do some soundproofing.
> 
> Wondering if this fine forum might have some tips on how to think about the issue and get the wife on-board.
> 
> 
> 
> There's a lot of, "Well, it depends..." thoughts going through my head based on your comments. If you're looking for general advice, I would suggest you stuff some "pink fluffy" insulation in there after you complete repairs rather than Roxul. It's cheaper and more malleable in that type of situation.
> 
> If it's unclear what you are going to do with this space in the future, I'd stop there for now.
Click to expand...

So that's pretty much where I'm at, and my major concern is just having to do demo and reno twice.


----------



## HT Geek

ckronengold said:


> So that's pretty much where I'm at, and my major concern is just having to do demo and reno twice.


So, do you have plans for this room to be converted to a home theater room?

Based on the constraints you described previously, I'd suggest considering a drywall/Green Glue/drywall sandwich. It can be done within 2". That would limit your height loss and keep you within 7', which will satisfy building codes in most of the country. 

OR

Another option is to wait. There are some short height clips out there. You could do clips + hat channel + 1 sheet of 5/8" = 2"


----------



## Harkon

HT Geek said:


> You still need to screw it into the studs. Alternate your screw offset. Ceilings normally have more screws, but depends on the installer.
> 
> Either way, as an example, offset 6" from ceiling and put a screw every 12" or so. Then on your 2nd layer, start at a 2 or 3 inch offset and alternate 12". Using that technique, you can use fewer screws in the 1st sheet if you like since the 2nd layer screws go through the first. 1" + drywall thickness for 1st layer and (+ drywall thickness for 2nd layer). Figure 1-5/8" and 2-1/2" screws respectively, or perhaps something close in wood screws for first layer. Drywall screws usually work well enough tho under the circumstances (1st layer). Make sure you dimple the 2nd layer screws. There are special drill bits you can find that make it easier.
> 
> 
> 
> You just need to line everything up where you can. If you use enough screws where there are studs, it won't be an issue. Use some extra screws if you have fewer joists to attach to.
> 
> Yes, it still should be attached directly to a stud. BTW, using OSB for the 1st layer is more challenging than it might seem beforehand. It's more difficult to cut and line up compared with drywall, and it's more challenging to create smooth seams. I would recommend staggering the drywall over top of it.
> 
> Also, it does not help you from a sound proofing standpoint. There is a benefit to hanging things, as you mentioned.


Appreciate all the input. That’s much clearer thank you. 

I know osb makes no difference for sound proofing but figure it’ll make fixing soffit and wall mounted surround speakers a lot easier. Appreciate dry wall cuts easy but hopefully not too bad with decent circular saw etc.

If I stagger all the seams and top layer is drywall hoping seams shouldn’t present an issue?


----------



## HT Geek

Harkon said:


> Appreciate all the input. That’s much clearer thank you.
> 
> I know osb makes no difference for sound proofing but figure it’ll make fixing soffit and wall mounted surround speakers a lot easier. Appreciate dry wall cuts easy but hopefully not too bad with decent circular saw etc.
> 
> If I stagger all the seams and top layer is drywall hoping seams shouldn’t present an issue?


Yes, it can be a plus for certain things. Really depends on the details, but it may be helpful. Regarding cutting and fitting it, what you'll likely find is it's the detailed trimming that becomes a pain, such as in a corner. With drywall, you can cut and snap in place much of the time. Even if you can't do that, it's quicker and easier as you don't need a saw, etc. Another factor is you can patch the drywall if you nick a bit here and there, if necessary. YMMV. I have been there, done that and I would probably not do it again. It was just more work. I do agree that especially on the walls it can be a plus, but only if you know you will be hanging things and want/need the extra support vs. 2x drywall layers.

The OSB seams don't line up quite as nicely as drywall, but since you will have the drywall over top if it, should be non-issue regarding the finished product. With respect to the OSB seams, they're not smooth like drywall and they aren't as easy to seal as drywall seams (e.g. sound proofing caulk).

Just plan to spend more time installing the OSB than you would for a drywall layer and you should be OK.


----------



## ckronengold

HT Geek said:


> So, do you have plans for this room to be converted to a home theater room?
> 
> Based on the constraints you described previously, I'd suggest considering a drywall/Green Glue/drywall sandwich. It can be done within 2". That would limit your height loss and keep you within 7', which will satisfy building codes in most of the country.
> 
> OR
> 
> Another option is to wait. There are some short height clips out there. You could do clips + hat channel + 1 sheet of 5/8" = 2"


Very helpful. Guess the next question is if one is a much better option than the other? I've been doing as much reading as I can on the subject, and wondering if clips might be better for "impact noise" but the double layer w/ Green Glue might be better for "airborne noise"? 

I'm not turning the room into a dedicated theater, but it is a media room / kids play room that I'd love to be as quiet as possible (within reason). I'd like to be able to watch a movie or listen to music at night without the sound travelling to the 3rd floor. Not too concerned with foot traffic. 

With the limited wiggle room I have on the ceiling height, I could consider something like a low-profile clip, which might give me the space I need for a double layer. https://www.acousticalsurfaces.com/rsic_clips/rsic-1-low-profile.html

I realize there are a few ways to approach the issue, and you're 110% right. "It depends" is all over the place. It depends on how much of the ceiling really needs to come down to fix the HVAC. If its ultimately "not that much," then tearing the whole ceiling (and possibly walls) down seems like a bad investment of time and money. 

Thanks @HT Geek. I really appreciate your input and thoughtful consideration.


----------



## mhutchins

You can also install raised blocking between the joists for mounting your clips and channel and can reduce height loss to only 1/2" plus the thickness of the drywall layers. See the image below from the Soundproofing Company for an explanation.


----------



## clausdk

Hi all

Airgap importance?

Trying to decide on:

Solid wall (light concrete) + airgap(rockwool) + clips/channels + dual plasterboard + GG

*Difference airgap 2" vs 4"?*

And how about a 3rd layer of plasterboard?

Basicly I am trying to make the slimmest possible soundproofing "cost no object", and I cannot find any way to calculate the benifit of a larger airgap?

Any other solution I should look at other than what I often see used here which is 2 by 4's + clips/channels and plaster/GG?

/Regards


----------



## warwwolf7

clausdk said:


> [...]
> 
> Any other solution I should look at other than what I often see used here which is 2 by 4's + clips/channels and plaster/GG?
> 
> /Regards


Well... If you want to see a different approach, there's is this guy that is using mud and stray bale. 

https://r.tapatalk.com/shareLink?ur...hare_tid=2997154&share_fid=47413&share_type=t

-Matt


----------



## HT Geek

warwwolf7 said:


> Well... If you want to see a different approach, there's is this guy that is using mud and stray bale.
> 
> https://r.tapatalk.com/shareLink?ur...hare_tid=2997154&share_fid=47413&share_type=t


Soon to be known on this forum as "brown scratchy," cousin of "pink fluffy" and coming soon to AVS... "The Hay-Fever Theater Build."

Building inspectors around here would just love the Romex sandwiched in between straw whilst we're in the midst of burn ban and the air is 100+ and about 25% humidity. 

LMAO when she gets out the chainsaw. I might have to try that the next time I need to cut some drywall... not.

https://youtu.be/A7u76MyqR6s?t=300

I also don't understand why she mentions CO as an issue. I think that would be the last of my concerns. At least unless it's a by-product of the house being on fire. Hmm..... 

Hopefully, no one in the house is a smoker... better have a good electrician too... would hate to have a short or loose wire... sheesh.... Drywall is a bad enough "fire resistant" material (B.S.)... I'll stick with my 30-90 seconds to GTFO out of a burning house, thank you. Better than zero.


----------



## HT Geek

clausdk said:


> Hi all
> 
> Airgap importance?
> 
> Trying to decide on:
> 
> Solid wall (light concrete) + airgap(rockwool) + clips/channels + dual plasterboard + GG
> 
> *Difference airgap 2" vs 4"?*
> 
> And how about a 3rd layer of plasterboard?
> 
> Basicly I am trying to make the slimmest possible soundproofing "cost no object", and I cannot find any way to calculate the benifit of a larger airgap?
> 
> Any other solution I should look at other than what I often see used here which is 2 by 4's + clips/channels and plaster/GG?


To answer your core question, there is no benefit to a 4" air gap vs. 2". I would not consider anything less than 1/2" absolute minimum. You need a bit of space to allow for variations in materials. A 1" gap is a good general guideline for most builds.


----------



## HT Geek

ckronengold said:


> Very helpful. Guess the next question is if one is a much better option than the other? I've been doing as much reading as I can on the subject, and wondering if clips might be better for "impact noise" but the double layer w/ Green Glue might be better for "airborne noise"?


Do you mean clips with 1 layer of drywall vs. 2x drywall/GG sandwich directly attached to studs and no clips?

Without digging up lab tests to get a definitive answer... I would say your best bet for both problems is likely to be doing both: i.e., 2x drywall/GG sandwich attached to clips. They can hold the weight with no issues when the clips are spaced properly.


----------



## clausdk

HT Geek said:


> Do you mean clips with 1 layer of drywall vs. 2x drywall/GG sandwich directly attached to studs and no clips?
> 
> Without digging up lab tests to get a definitive answer... I would say your best bet for both problems is likely to be doing both: i.e., 2x drywall/GG sandwich attached to clips. They can hold the weight with no issues when the clips are spaced properly.


Yes correct 2 x drywall/GG - and I was then wondering how big an impact the airgap to the solid wall will have? My house has solid walls in cinderblock type concrete.

Also, will another layer of drywall outperform a slighter larger airgap?


----------



## HT Geek

clausdk said:


> Yes correct 2 x drywall/GG - and I was then wondering how big an impact the airgap to the solid wall will have? My house has solid walls in cinderblock type concrete.
> 
> Also, will another layer of drywall outperform a slighter larger airgap?


Another layer of drywall would be a better performer vs. a larger air gap, yes.

However, I'm concerned we ought to level-set regarding more details about your build. Clips and channel vs. no clips is totally different line of thinking vs. an air gap choice between 2" and 4", or anything close to that.

What exactly are you trying to compare? Pros and cons of Plan A vs. Plan B perhaps? And if so, what are you thinking in terms of the potential trade-offs? (e.g. clips & channel vs. double stud walls in front of your cinder block wall)


----------



## clausdk

HT Geek said:


> Another layer of drywall would be a better performer vs. a larger air gap, yes.
> 
> However, I'm concerned we ought to level-set regarding more details about your build. Clips and channel vs. no clips is totally different line of thinking vs. an air gap choice between 2" and 4", or anything close to that.
> 
> What exactly are you trying to compare? Pros and cons of Plan A vs. Plan B perhaps? And if so, what are you thinking in terms of the potential trade-offs? (e.g. clips & channel vs. double stud walls in front of your cinder block wall)


In all cases there is a solid wall made of light concrete, sort of cinderblock type. 

A)

Studs to form the airgap of X size/depth + clips/channels + 2 x drywall/GG


B)

Same as above but smaller airgap and 3 x drywall.

C)

Studs of a given size/depth with 2-3 drywall directly onto it and GG - the studs would obviously not touch the inner wall.

X) 

And in general, how much effect does the airgap have in general.


----------



## HT Geek

When you have a small gap (such as the type you're discussing), its purpose is to disrupt vibrations in the walls between the drywall and studs (inner wall) and the structural (outer) wall.

If you had a choice between direct contact (inner wall to outer wall) versus [inner wall] + [air gap] + [outer wall] then you want the air gap. That is where it is beneficial. It is more difficult for sound waves to traverse the air gap (even a really small one) versus vibrate one wall surface into another one.


----------



## ckronengold

HT Geek said:


> Do you mean clips with 1 layer of drywall vs. 2x drywall/GG sandwich directly attached to studs and no clips?
> 
> Without digging up lab tests to get a definitive answer... I would say your best bet for both problems is likely to be doing both: i.e., 2x drywall/GG sandwich attached to clips. They can hold the weight with no issues when the clips are spaced properly.


Agreed that both is the right / best way. But I'm just trying to plan for as many scenarios as I can. 

I'd imagine the GG sandwich is better for airborne sound and the clips are better for separating the structural noise. Your gut feeling is plenty good. You don't need to dig up any lab tests. 

Seems like if I used the low profile clips and/or the blocking between the joists, I could do the hat and clips without giving up any additional height. But given the problem I'm trying to solve, that might not be the right choice. Adding another 5/8" should be manageable. 

If I can't do both, is one a better approach than the other?


----------



## ckronengold

mhutchins said:


> You can also install raised blocking between the joists for mounting your clips and channel and can reduce height loss to only 1/2" plus the thickness of the drywall layers. See the image below from the Soundproofing Company for an explanation.


Thats an awesome suggestion, too. Guess I'll have to talk to my contractor about the amount of time / money to do raised blocking vs using those L-shaped low-profile clips (https://www.acousticalsurfaces.com/rsic_clips/rsic-1-low-profile.html) But its always great to have options. 


Thanks, @mhutchins!


----------



## warwwolf7

clausdk said:


> In all cases there is a solid wall made of light concrete, sort of cinderblock type.
> 
> A)
> 
> Studs to form the airgap of X size/depth + clips/channels + 2 x drywall/GG
> 
> 
> B)
> 
> Same as above but smaller airgap and 3 x drywall.
> 
> C)
> 
> Studs of a given size/depth with 2-3 drywall directly onto it and GG - the studs would obviously not touch the inner wall.
> 
> X)
> 
> And in general, how much effect does the airgap have in general.


When using clip and channel, you have an air gap, you don't need to add another one. When doing 3layers of drywall with an air gap, you then dont need the channel because the 2walls are already not "connected". Unless you have a complete room within a room, you should use channels where you only have 1 wall. Like on your ceiling.

I have never seen any data on a double wall with resilient channel on them. When you have a air gap between 2walls you don't use resilient channel.

A, When you say stud to form air gap, you mean the studs are not filled with fiberglass and is separated from you cinder block? If you use resilient channels, fille the cavity with fiber glass or rockwool, don't leave air gap. 

B, you have to make sure that the spacing is correct to support all the weight of the drywall, 3layers is heavy. Don't put airgap between the students and the cinder block if you use resilient channel. Fille the students with fiberglass or rockwool 

C airgap of 1" fill the stud with fiberglass or rockwool. Use use isolating clips to decouple the wall (like ib-3 for example) 2layers will give you a good stc. A third layer will help but the return on investment is not that much. You will get better bass isolation as your wall get heavier. Some will say you third layer drywall more or less equal 2layer with Gg

How does an air gap impact the isolation
Here's an example
(all have fiberglass filled stud, 5/8" type x drywall) 
Dd + stud + dd : stc36
Dd +resilient + stud + dd : stc 54
Dd + resilient + stud + resilient + dd : stc60
Dd + stud + airgap 1" + stud + dd : 69

The airgap is having a good effect on pretty much all frequencies , including the lower frequencies. 

I hope this helps 




-Matt


----------



## HT Geek

ckronengold said:


> Agreed that both is the right / best way. But I'm just trying to plan for as many scenarios as I can.
> 
> I'd imagine the GG sandwich is better for airborne sound and the clips are better for separating the structural noise. Your gut feeling is plenty good. You don't need to dig up any lab tests.


I'm thinking the clips & channel with 1 sheet of drywall is going to be a better performer vs. DD/GG sandwich attached directly to surface for both impact and airborne noise. Stuff some pink fluffy loosely in the cavity as well and it will help muffle higher pitch sounds in particular (e.g. high heels on hardwood floor above, human voices). You're going to benefit in both cases from the "springiness" provided by the hat channel and clips.

That meets 2" max drop (using 5/8" Type X drywall) if you have to go that route, to keep you at 7'. If you can squeeze in another 5/8" sheet + GG, you will lose another 3/4" total. 

If you will get the room inspected at some point.... Some ideas so you can sleep well at night.... If your building code is 7' min height in that room (some codes are 6' 8" and some don't specify, presuming this room is in a basement).... One trick if the ceiling to floor distance becomes an issue... say you have a difficult building inspector... tell them you're doing stained concrete floor and carpet will be removed. That will get you another 3/4" - 1" or so. That's an extreme case. Some state codes specify whether the measurement is from the "finished floor" or just from the "floor," and some do not specify. Some inspectors would make you rip the carpet before they pass it just to be difficult. Most are pretty cool about it (especially these days... those guys are super busy here at least). It's all over the map.


----------



## ckronengold

HT Geek said:


> I'm thinking the clips & channel with 1 sheet of drywall is going to be a better performer vs. DD/GG sandwich attached directly to surface for both impact and airborne noise. Stuff some pink fluffy loosely in the cavity as well and it will help muffle higher pitch sounds in particular (e.g. high heels on hardwood floor above, human voices). You're going to benefit in both cases from the "springiness" provided by the hat channel and clips.
> 
> That meets 2" max drop (using 5/8" Type X drywall) if you have to go that route, to keep you at 7'. If you can squeeze in another 5/8" sheet + GG, you will lose another 3/4" total.


Awesome. Thanks. 



HT Geek said:


> If you will get the room inspected at some point.... Some ideas so you can sleep well at night.... If your building code is 7' min height in that room (some codes are 6' 8" and some don't specify, presuming this room is in a basement).... One trick if the ceiling to floor distance becomes an issue... say you have a difficult building inspector... tell them you're doing stained concrete floor and carpet will be removed. That will get you another 3/4" - 1" or so. That's an extreme case. Some state codes specify whether the measurement is from the "finished floor" or just from the "floor," and some do not specify. Some inspectors would make you rip the carpet before they pass it just to be difficult. Most are pretty cool about it (especially these days... those guys are super busy here at least). It's all over the map.


Depends on the day around me. If they were with jerks before they come to you, you may get screwed.


----------



## austtam

Hi All,

Wondering if I can get some input. This isn't a dedicated theater, but it is a soundproofing question. My house is connected on both sides with neighbors to my left and right. I'd like to limit as much sound as I can in my second floor living room room area (garage underneath) and I'm planning on treating the walls marked in red. I was planning on doing rockwool safe & sound, rsic clips, double 5/8 drywall and green glue. 










I don't have the budget to treat every surface. I'm wondering if I should even bother with the rsic clips knowing that there'll be flanking noise transmission through the ceiling and floor.


----------



## niccolo

austtam said:


> Hi All,
> 
> Wondering if I can get some input. This isn't a dedicated theater, but it is a soundproofing question. My house is connected on both sides with neighbors to my left and right. I'd like to limit as much sound as I can in my second floor living room room area (garage underneath) and I'm planning on treating the walls marked in red. I was planning on doing rockwool safe & sound, rsic clips, double 5/8 drywall and green glue.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I don't have the budget to treat every surface. I'm wondering if I should even bother with the rsic clips knowing that there'll be flanking noise transmission through the ceiling and floor.



My layman take: The higher frequencies are likely to be significantly contained by just treating the adjoining walls, and not doing the floor, ceiling, or non-adjoining walls. Lower frequencies, on the other hand, are going to travel pretty readily through coupled framing structures.


----------



## Misha_J

Good Day AVS!

I'm a long time lurker. I have read over different threads multiple times over the last year and a half. I have learned a lot, and I think that I understand the basic concepts. My initial motivation was to soundproof the garage so that I could do my woodworking any time and not bother anyone in the house (that is still ongoing due to budget cuts).
I have a question, it is not about building a home theater, but about soundproofing a suite in my house. I apologize for this, and totally understand if my post gets removed, I do not know of a better place to ask though. This thread and Gearslutz has been the most informative I have found with anything soundproofing. But who knows, maybe one day, I will be able to afford a little theater in my house. Then all this experience will come in handy.

My situation. 
Downstairs we have a rental suite which consists of living room 2 bedrooms, and the worst form of sound control imaginable. This sound situation has been brewing for a while, and I feel that we are at a tipping point. We want to borrow a bit of money, reno the suite and rent it out for more (it is quite below market value right now anyway). The suite has very high ceilings, and I want to employ the decoupling concept here to reduce our footsteps, run a bit of ventilation between the ceiling and floor, and overall kill sound transfer. The plan was to drop the ceiling, then use DD 5/8" with GG. I was planning on double studded wall on one of the walls bordering the garage, but no such arrangement for any other walls. The one thing that I do not understand is the triple leaf effect, and how it will affect my situation. If I drop the ceiling in all 3 rooms, it will create a giant void space between all the rooms. Will this worsen my situation? Below is a quick drawing of what I mean with the void illustrated in yellow and layout of the suite with proposed double stud wall. 
Questions:
1. Would installing blocking between studs at the ledger joist (and insulating them with acoustic caulking) help the situation?
2. If I do as described (and I am only concerned with sound between floors), do I need to install DD and GG on the walls or would doing this on the ceiling and blocking mentioned be sufficient? I am worried about flanking, but would blocking take care of that? Adding second layer and GG on all walls takes the estimated cost up 3.5 thousand. 
3. Should I leave drywall (or install new) in the void space to keep the rooms separated?
4. Can the void be too big? (I am planning 4 inches between new and old joists. Bottom joists will have to be 2x10, top joists are 2x12 i think.

Any advice, insight and wisdom is greatly appreciated guys! Again, I apologize this is not about an actual theater.
PS I should add, main source of noise is the living room, this is what I REALLY want to isolate, but with flanking I feel like I have to soundproof the whole suite.


----------



## Misha_J

Misha_J said:


> Good Day AVS!
> 
> I'm a long time lurker. I have read over different threads multiple times over the last year and a half. I have learned a lot, and I think that I understand the basic concepts. My initial motivation was to soundproof the garage so that I could do my woodworking any time and not bother anyone in the house (that is still ongoing due to budget cuts).
> I have a question, it is not about building a home theater, but about soundproofing a suite in my house. I apologize for this, and totally understand if my post gets removed, I do not know of a better place to ask though. This thread and Gearslutz has been the most informative I have found with anything soundproofing. But who knows, maybe one day, I will be able to afford a little theater in my house. Then all this experience will come in handy.
> 
> My situation.
> Downstairs we have a rental suite which consists of living room 2 bedrooms, and the worst form of sound control imaginable. This sound situation has been brewing for a while, and I feel that we are at a tipping point. We want to borrow a bit of money, reno the suite and rent it out for more (it is quite below market value right now anyway). The suite has very high ceilings, and I want to employ the decoupling concept here to reduce our footsteps, run a bit of ventilation between the ceiling and floor, and overall kill sound transfer. The plan was to drop the ceiling, then use DD 5/8" with GG. I was planning on double studded wall on one of the walls bordering the garage, but no such arrangement for any other walls. The one thing that I do not understand is the triple leaf effect, and how it will affect my situation. If I drop the ceiling in all 3 rooms, it will create a giant void space between all the rooms. Will this worsen my situation? Below is a quick drawing of what I mean with the void illustrated in yellow and layout of the suite with proposed double stud wall.
> Questions:
> 1. Would installing blocking between studs at the ledger joist (and insulating them with acoustic caulking) help the situation?
> 2. If I do as described (and I am only concerned with sound between floors), do I need to install DD and GG on the walls or would doing this on the ceiling and blocking mentioned be sufficient? I am worried about flanking, but would blocking take care of that? Adding second layer and GG on all walls takes the estimated cost up 3.5 thousand.
> 3. Should I leave drywall (or install new) in the void space to keep the rooms separated?
> 4. Can the void be too big? (I am planning 4 inches between new and old joists. Bottom joists will have to be 2x10, top joists are 2x12 i think.
> 
> Any advice, insight and wisdom is greatly appreciated guys! Again, I apologize this is not about an actual theater.
> PS I should add, main source of noise is the living room, this is what I REALLY want to isolate, but with flanking I feel like I have to soundproof the whole suite.


Sorry Images did not upload, trying again:


----------



## ckronengold

Hey @BIGmouthinDC (or anyone else who feels like weighing in)....

Can you recommend any builders / contractors in Northern New Jersey? I'm most likely going to need to tear down my basement to the studs (maybe even take down the framing) in order to properly waterproof. 

As long as I'm tearing it down and putting it back together, I may as well sound proof it, too. Our current contractor is more than capable of rebuilding with clips and channels and green gluing two layers together, but I'm not sure that he's going to see all the little details and hidden obstacles to the soundproofing. 

Looking for some names to contact to discuss the project. 

Thanks!


----------



## mkiv808

I have to be honest, the amount of soundproofing information out there is kind of overwhelming.

My situation: basement theater build from studs up. It’s an above ground basement. We are near water so the second floor is actually the main floor. Not in a flood zone but this is just the style of homes here.

3 of the walls are exterior. One neighbor is somewhat close. Maybe 25’ from my wall. 

The interior wall abuts a storage closet, a hallway with stairs that go upstairs, and another closet that will house the electronics. Beyond that space is the garage. 

Above the theater room is a dining room and kitchen.

I’m trying to mostly keep the room silent, but also keep bass from traveling up to the 3rd floor bedrooms. I’d like to blast a movie without bothering people 2 floors up. 

I don’t need a bank vault, and would like to keep a moderate budget and also not lose a ton of room space. 

So here’s my current plan. And keep in mind this changes constantly as I do more research.

Insulation: Pink R13 is already in side walls. Add Roxul Safe and Sound to ceiling.

Ceiling: use low profile clips (to save space) and hat channel with 1 layer of 5/8” drywall.

Walls: 2 layers of 5/8” drywall with green glue. 

Acoustic caulk for seams 

Maybe acoustic putty for boxes? Not sure if worth it. 

Anything that can be done with HVAC vents to lessen sound transmission? Line them with something? There’s a few in the ceiling.

There’s a wall with a concrete half wall. Was going to just build another framed walled in front of this. I’m wondering if there’s anything I can do to “float” this new wall? Maybe to the point where I could avoid green glue on this wall. This is the wall that is closest to the nearest neighbor.


----------



## niccolo

mkiv808 said:


> I have to be honest, the amount of soundproofing information out there is kind of overwhelming.
> 
> My situation: basement theater build from studs up. It’s an above ground basement. We are near water so the second floor is actually the main floor. Not in a flood zone but this is just the style of homes here.
> 
> 3 of the walls are exterior. One neighbor is somewhat close. Maybe 25’ from my wall.
> 
> The interior wall abuts a storage closet, a hallway with stairs that go upstairs, and another closet that will house the electronics. Beyond that space is the garage.
> 
> Above the theater room is a dining room and kitchen.
> 
> I’m trying to mostly keep the room silent, but also keep bass from traveling up to the 3rd floor bedrooms. I’d like to blast a movie without bothering people 2 floors up.
> 
> I don’t need a bank vault, and would like to keep a moderate budget and also not lose a ton of room space.
> 
> So here’s my current plan. And keep in mind this changes constantly as I do more research.
> 
> Insulation: Pink R13 is already in side walls. Add Roxul Safe and Sound to ceiling.
> 
> Ceiling: use low profile clips (to save space) and hat channel with 1 layer of 5/8” drywall.
> 
> Walls: 2 layers of 5/8” drywall with green glue.
> 
> Acoustic caulk for seams
> 
> Maybe acoustic putty for boxes? Not sure if worth it.
> 
> Anything that can be done with HVAC vents to lessen sound transmission? Line them with something? There’s a few in the ceiling.
> 
> There’s a wall with a concrete half wall. Was going to just build another framed walled in front of this. I’m wondering if there’s anything I can do to “float” this new wall? Maybe to the point where I could avoid green glue on this wall. This is the wall that is closest to the nearest neighbor.


Did you mean to list clips for the walls, too? If you're hoping to blast music, especially lower-frequency sound, and not have it travel through the framing, you're going to need isolation/decoupling (drywall clips or framing clips or dual stud or staggered stud). Green Glue will damp wall vibration, but isn't a substitute for isolation/decoupling.


----------



## mkiv808

niccolo said:


> Did you mean to list clips for the walls, too? If you're hoping to blast music, especially lower-frequency sound, and not have it travel through the framing, you're going to need isolation/decoupling (drywall clips or framing clips or dual stud or staggered stud). Green Glue will damp wall vibration, but isn't a substitute for isolation/decoupling.


Actually intentionally only did clips on ceiling. 

Saving some time and money there, and space by just doing dual drywall and GG on walls.

I guess my logic was ceiling would be main transmission point for bass. 

If I’m conserving the size of the room, I have also considered just doing clips and a single layer of 5/8” everywhere and skipping DD/GG. Probably would be cheaper. Could also do dual drywall, low profile clips, and save money by skipping GG. So many options!


----------



## niccolo

mkiv808 said:


> Actually intentionally only did clips on ceiling.
> 
> Saving some time and money there, and space by just doing dual drywall and GG on walls.
> 
> I guess my logic was ceiling would be main transmission point for bass.
> 
> If I’m conserving the size of the room, I have also considered just doing clips and a single layer of 5/8” everywhere and skipping DD/GG. Probably would be cheaper. Could also do dual drywall, low profile clips, and save money by skipping GG. So many options!


Bass travels through coupled framing really well, so treating the ceiling and not the walls is going to give you huge "flanking" issues, i.e. the vibrations bypassing the decoupled ceiling.


Given a choice between clips and one layer of drywall versus no clips but two layers of drywall with Green Glue, I'm guessing most would choose the former. But once you're doing one layer of drywall, the second one doesn't add that much cost and you lose minimal room volume. You can save money and effort by skipping the GG between the drywall layers if needed.


----------



## mkiv808

niccolo said:


> Bass travels through coupled framing really well, so treating the ceiling and not the walls is going to give you huge "flanking" issues, i.e. the vibrations bypassing the decoupled ceiling.
> 
> 
> Given a choice between clips and one layer of drywall versus no clips but two layers of drywall with Green Glue, I'm guessing most would choose the former. But once you're doing one layer of drywall, the second one doesn't add that much cost and you lose minimal room volume. You can save money and effort by skipping the GG between the drywall layers if needed.


Yeah that latter option might be smart. Wondering how well low profile clips work and ease of install


----------



## niccolo

mkiv808 said:


> Yeah that latter option might be smart. Wondering how well low profile clips work and ease of install


Others can answer that better than I can.


But if you're already going down to the studs, it seems like a raging no-brainer to me to go ahead with clips on the walls, i.e. what folks call a "room within a room."


Whether the floor warrants some isolation, too, is worth thinking about, but that's a far lesser concern than the walls.


----------



## mkiv808

Whew. The low profile clips are not cheap. Almost 4x more expensive than some A237 on eBay. 

I may just do the low profile on the ceiling to maintain ceiling height. 

Then do the regular clips on the wall. 

With a single layer of 5/8” drywall. 

In theory, I could do that, test it with subwoofers and some speakers, and determine if it’s sufficiently stopping sound or if I need another layer of drywall? Only problem is concrete floor will probably not help.


----------



## mkiv808

Also, seems like Purple XP drywall has minimal benefit over standard drywall?


----------



## niccolo

mkiv808 said:


> Whew. The low profile clips are not cheap. Almost 4x more expensive than some A237 on eBay.
> 
> I may just do the low profile on the ceiling to maintain ceiling height.
> 
> Then do the regular clips on the wall.
> 
> With a single layer of 5/8” drywall.
> 
> In theory, I could do that, test it with subwoofers and some speakers, and determine if it’s sufficiently stopping sound or if I need another layer of drywall? Only problem is concrete floor will probably not help.



You can also get a lower profile effect by mounting the clips on secondary pieces of framing that are slightly recessed between the primary framing. I know people do that for ceilings; I haven't heard of anyone doing it on walls. That adds some labor and materials, of course, so I'm not sure it would save you anything over going with low-profile clips (but the higher profile clips might have marginally better performance?).


Testing with one layer of drywall and seeing if it's satisfactory seems like a good plan, even if imperfect (e.g. will a door be hung? Backer boxes in place for canned lights? Etc.). The conventional wisdom is that the second layer of drywall is pretty cheap relative to the benefits, but of course, it's easy to drive up the budget by doing a few things that individually are pretty cheap and collectively end up not so cheap. One way to justify it is that the extra mass of the second layer works synergistically with the isolation provided by the clips, so they're each more valuable in combination with the other. Of course, then you've got the additional question of Green Glue, and that drives the cost up yet further. Decisions, decisions...


----------



## mkiv808

I’m building a wall on top of an existing wall and concrete half wall.

It will connect with the old wall about every 3 joists with a shim. That should help sound transmission a bit, but is there anything I can do to damp wood on wood? 

I saw Green Glue tape for floor joists, would that do anything for the wall?


----------



## niccolo

mkiv808 said:


> I’m building a wall on top of an existing wall and concrete half wall.
> 
> It will connect with the old wall about every 3 joists with a shim. That should help sound transmission a bit, but is there anything I can do to damp wood on wood?
> 
> I saw Green Glue tape for floor joists, would that do anything for the wall?



Hopefully BIG or others will chime in.


You can isolate the wall either with clip and channel (isolating the drywall from the framing) or with clips that isolate the framing from the ceiling.


Green Glue damps resonant layers, but provides much less isolation, in part because mechanical fasteners are still coupling the layers through the Green Glue.


----------



## mkiv808

niccolo said:


> Hopefully BIG or others will chime in.
> 
> 
> You can isolate the wall either with clip and channel (isolating the drywall from the framing) or with clips that isolate the framing from the ceiling.
> 
> 
> Green Glue damps resonant layers, but provides much less isolation, in part because mechanical fasteners are still coupling the layers through the Green Glue.



Interested in what clips are used for frame on frame?


----------



## mkiv808

Looks like Isomax clips are a good inexpensive low profile option. 

https://kineticsnoise.com/arch/isomax.html


----------



## OJ Bartley

I have a quick question about drywall type... I know mass is the key to reducing sound transmission. Since my room is narrow, every inch counts and I was going to use two layers of 1/2 inch with green glue in between throughout the theatre. Would it be worth the extra cost (basically twice the price per sheet) to use the heavier fire rated type for one layer? It isn't double the weight, but it might be about 50% heavier than the usual lightweight stuff.

I have considered a layer of 5/8" as well, but the seats I'm looking at will be extremely tight in the back row and I don't want to lose even that 1/2 inch if it won't be a substantial improvement.


----------



## niccolo

OJ Bartley said:


> I have a quick question about drywall type... I know mass is the key to reducing sound transmission. Since my room is narrow, every inch counts and I was going to use two layers of 1/2 inch with green glue in between throughout the theatre. Would it be worth the extra cost (basically twice the price per sheet) to use the heavier fire rated type for one layer? It isn't double the weight, but it might be about 50% heavier than the usual lightweight stuff.
> 
> I have considered a layer of 5/8" as well, but the seats I'm looking at will be extremely tight in the back row and I don't want to lose even that 1/2 inch if it won't be a substantial improvement.



5/8 is a lot more massive than 1/2". Especially when you're also doing other things (Green Glue, and hopefully some form of decoupling like clip and channel or staggered stud), extra mass makes a big difference. And when you factor in labor and the cost of the theater more generally, it doesn't add much cost. And the thickness difference is pretty minimal--you really want to trade off reduced soundproofing for that tiny increment of additional room volume?


----------



## niccolo

mkiv808 said:


> Looks like Isomax clips are a good inexpensive low profile option.
> 
> https://kineticsnoise.com/arch/isomax.html



Sorry, I don't recall what the clips that are used to decouple framing, rather than drywall, are called. BIG and some others sporadically mention them on here, hopefully someone will chime in. They're used to decouple the top of a framed wall, and then the bottom should also be decoupled as much as possible, e.g. with a layer of rubber under the footers (though fasteners will still couple to a considerable degree). One thing I'm not clear on is how decoupling the framing interacts with building code, though.


----------



## OJ Bartley

niccolo said:


> 5/8 is a lot more massive than 1/2". Especially when you're also doing other things (Green Glue, and hopefully some form of decoupling like clip and channel or staggered stud), extra mass makes a big difference. And when you factor in labor and the cost of the theater more generally, it doesn't add much cost. And the thickness difference is pretty minimal--you really want to trade off reduced soundproofing for that tiny increment of additional room volume?


Thanks niccolo, I'll try to work it so that I have one layer of 5/8". Going from light 1/2" to fire rated 5/8" should make enough of a difference to be worthwhile. I'm not using clip and channel, but the one wall shared with the rest of the basement is staggered stud. For the rest I'm relying on DD+GG with insulation in all wall and ceiling cavities.


----------



## niccolo

OJ Bartley said:


> Thanks niccolo, I'll try to work it so that I have one layer of 5/8". Going from light 1/2" to fire rated 5/8" should make enough of a difference to be worthwhile. I'm not using clip and channel, but the one wall shared with the rest of the basement is staggered stud. For the rest I'm relying on DD+GG with insulation in all wall and ceiling cavities.



You're mostly skipping decoupling, which means vibrations, especially lower-frequency ones, will travel through the framing to other parts of the house. Cost and space considerations may warrant that, but it's worth being aware of the implications. For what it's worth, I did similarly, in my case because taking existing walls and ceiling down to the studs and rebuilding decoupled ones wasn't in the budget. I also figure when others are home but not watching content the volume will need to be modest or headphones used.


----------



## pkinneb

niccolo said:


> 5/8 is a lot more massive than 1/2".


The fact that most home centers carry primarily light weight 1/2" from what I have seen makes it that much more important in my opinion.


----------



## mkiv808

So I already did the wall. It’s got 3 screws tacked into concrete and then 3 composite shims on every 3rd joist. Shouldn’t be too bad especially since I’ll have clips and hat channel on it.









My next area of interest is a drain pipe and HVAC. 

Some of the air handlers from upstairs go into this room. You can even see a little light from upstairs around them. Not great! Also, there’s a drain pipe that you can hear trickling.

Any ideas on how to mitigate these? Is there a way to seal around the vents? I’ve heard of mass loaded vinyl being used.


----------



## SED <--- Rules

I need some help guys. I want to buy a carpet for my home theater and am pondering what should I put under the carpet to help with sound absorption. I don't need extremes, just a cost effective way to at least help to absorb sound. What should I get? Just regular carpet padding? Or rubber underlayment? Or Felt underlayment? Thanks!


----------



## niccolo

[QUOTE="SED


----------



## OJ Bartley

niccolo said:


> You're mostly skipping decoupling, which means vibrations, especially lower-frequency ones, will travel through the framing to other parts of the house. Cost and space considerations may warrant that, but it's worth being aware of the implications. For what it's worth, I did similarly, in my case because taking existing walls and ceiling down to the studs and rebuilding decoupled ones wasn't in the budget. I also figure when others are home but not watching content the volume will need to be modest or headphones used.


Thanks again niccolo. You are right on the nose, this is (as are most) a cost and complication-constrained build, and I am looking for maximum return for "reasonable" input. We won't need full soundproofing, but I do want to make efforts to minimize what gets out. Right now we watch movies in the main floor open living room while the kids sleep upstairs and haven't had too many problems. Moving to a dedicated room in the basement with some basic sound control should be a big improvement.


----------



## Ladeback

niccolo said:


> Sorry, I don't recall what the clips that are used to decouple framing, rather than drywall, are called. BIG and some others sporadically mention them on here, hopefully someone will chime in. They're used to decouple the top of a framed wall, and then the bottom should also be decoupled as much as possible, e.g. with a layer of rubber under the footers (though fasteners will still couple to a considerable degree). One thing I'm not clear on is how decoupling the framing interacts with building code, though.


The clips used to decouple wall framing or backer boxes are IB-3 clips. The Soundproofing Company. I may be using these on my build if I can get going on a final plan.

https://www.soundproofingcompany.com/product_information/ib-3-decoupling-bracket


----------



## barfle

HT Geek said:


> Sounds good. Let us know when you're able to start a build thread.


Barfle’s bonus room bijou build is on the air!

https://www.avsforum.com/forum/15-g.../3095004-barfle-s-bonus-room-bijou-build.html


----------



## jjcook

I have seen quite a few transmission loss (STC) assembly test results for walls and ceilings but what about for carpeted HT floors -- specifically for non-concrete basement/slabs? I'd be interested in some data (or opinions) for the following configurations, i.e., the options for my second floor HT room where increasing the floor height by less than 1/2" is preferred and no more than 3/4 to 1" to meet code and aesthetics (even this requires some difficult but modest floor elevation change outside the room):

I'm starting with scenario (1) and clearly need to improve the floor -- rest of the room will be 5/8" DDW+GG on clips/channel and insulated and with DDW no clips for the other side of interior walls, thick heavy door with double seals, etc.

1) 3/4" TG osb + 12" I-joists + retrofit insulation (todo) + 1/2" lightweight drywall for ceiling below

2) 3/4" TG osb + GG + # 1

3) 3/4" rubber + DA5 glue + # 1

4) 5/8" TG osb + DA5 glue + 3/8" rubber + DA5 glue + # 1


----------



## niccolo

jjcook said:


> I have seen quite a few transmission loss (STC) assembly test results for walls and ceilings but what about for carpeted HT floors -- specifically for non-concrete basement/slabs? I'd be interested in some data (or opinions) for the following configurations, i.e., the options for my second floor HT room where increasing the floor height by less than 1/2" is preferred and no more than 3/4 to 1" to meet code and aesthetics (even this requires some difficult but modest floor elevation change outside the room):
> 
> I'm starting with scenario (1) and clearly need to improve the floor -- rest of the room will be 5/8" DDW+GG on clips/channel and insulated and with DDW no clips for the other side of interior walls, thick heavy door with double seals, etc.
> 
> 1) 3/4" TG osb + 12" I-joists + retrofit insulation (todo) + 1/2" lightweight drywall
> 
> 2) 3/4" TG osb + GG + # 1
> 
> 3) 3/4" rubber + DA5 glue + # 1
> 
> 4) 5/8" TG osb + DA5 glue + 3/8" rubber + DA5 glue + # 1


----------



## mkiv808

Posting again re: HVAC and drain pipe quieting. 

Would something like this help to wrap them in?

Thermal Aluminum Foil Foam Insulation- (2 Ft X 50 Ft Roll) Industrial Grade Radiant Barrier Great for Soundproofing, Automotive Insulation, Weatherproofing Roofs, Floors, Windows, Garages, RV's, More https://www.amazon.com/dp/B07LFL91CG/ref=cm_sw_r_cp_api_i_0esNDbY1KBBKB

Going to put acoustic caulk at the seams where I can see light coming through from upstairs.


----------



## jjcook

mkiv808 said:


> Posting again re: HVAC and drain pipe quieting.
> 
> Would something like this help to wrap them in?
> 
> Thermal Aluminum Foil Foam Insulation- (2 Ft X 50 Ft Roll) Industrial Grade Radiant Barrier Great for Soundproofing, Automotive Insulation, Weatherproofing Roofs, Floors, Windows, Garages, RV's, More https://www.amazon.com/dp/B07LFL91CG/ref=cm_sw_r_cp_api_i_0esNDbY1KBBKB
> 
> Going to put acoustic caulk at the seams where I can see light coming through from upstairs.


The foil you linked is only 0.08 pounds per square foot; while I didn't see your original post you will need more mass than that to reduce drain noise.


----------



## mkiv808

jjcook said:


> The foil you linked is only 0.08 pounds per square foot; while I didn't see your original post you will need more mass than that to reduce drain noise.




Any suggestions on something cost effective, and fire safe?


----------



## OJ Bartley

I've seen this before, but have never read about any actual experiences with it: 




I was planning to wrap the drain near my theatre in Dynamat and then stuff the rest of the cavity surrounding it with fluffy insulation, and then enclose that in DD+GG along with the rest of the room shell.


----------



## newtoavs_2018

Hi all sound experts! I would really appreciate your advice. I've digested the framework around soundproofing and at this point am wondering when you get diminishing returns on using soundproofing materials.

We are looking to soundproof walls. I'm considering Rockwool sound insulation + resilient channel + Quietrock + green glue + a second layer of Quietrock. I assume this may be overkill. When do we get diminishing returns? If it's overkill, we'd definitely prefer a route that is thinner (the RC and the double layer of Quietrock result in losing space in the room). Please help, and many thanks!!!


----------



## niccolo

newtoavs_2018 said:


> Hi all sound experts! I would really appreciate your advice. I've digested the framework around soundproofing and at this point am wondering when you get diminishing returns on using soundproofing materials.
> 
> We are looking to soundproof walls. I'm considering Rockwool sound insulation + resilient channel + Quietrock + green glue + a second layer of Quietrock. I assume this may be overkill. When do we get diminishing returns? If it's overkill, we'd definitely prefer a route that is thinner (the RC and the double layer of Quietrock result in losing space in the room). Please help, and many thanks!!!



The standard forum advice is hat channel and clips (not resilient channel), two layers of heavy 5/8" drywall sandwiching Green Glue, and standard fluffy pink insulation loosely placed in the cavities, and careful sealing of all other leak points (e.g. electrical boxes).


Rockwool likely adds only marginally over the cheap stuff.


Quietrock basically builds the Green Glue into each panel, at a significant additional cost.


Based on your suggesting Rockwool, resilient channel, and Quietrock, I'd say some time reading forum resources is probably in order, because I don't think you picked up any of that from the forum.


----------



## Ladeback

newtoavs_2018 said:


> Hi all sound experts! I would really appreciate your advice. I've digested the framework around soundproofing and at this point am wondering when you get diminishing returns on using soundproofing materials.
> 
> We are looking to soundproof walls. I'm considering Rockwool sound insulation + resilient channel + Quietrock + green glue + a second layer of Quietrock. I assume this may be overkill. When do we get diminishing returns? If it's overkill, we'd definitely prefer a route that is thinner (the RC and the double layer of Quietrock result in losing space in the room). Please help, and many thanks!!!


I would go with clips & channel with double 5/8" drywall and Green Glue, Rockwool or pink fluffy for inside the walls.

IMO, I would also check out The Soundproofing Company's website for more information and they have a 101 section on soundproofing. You need, mass, decoupling, absorption and damping. I think double layers of Quitrock is overlill and expensive. 



https://www.soundproofingcompany.com/


----------



## OJ Bartley

newtoavs_2018 said:


> Hi all sound experts! I would really appreciate your advice. I've digested the framework around soundproofing and at this point am wondering when you get diminishing returns on using soundproofing materials.
> 
> We are looking to soundproof walls. I'm considering Rockwool sound insulation + resilient channel + Quietrock + green glue + a second layer of Quietrock. I assume this may be overkill. When do we get diminishing returns? If it's overkill, we'd definitely prefer a route that is thinner (the RC and the double layer of Quietrock result in losing space in the room). Please help, and many thanks!!!


I think if you're willing to go that far, you can should be able to "step down" a bit like has been mentioned above by going to regular 5/8 (the heavy fire rated stuff) drywall, but what would benefit you the most is research into techniques and best practices. There is a TON to learn about soundproofing beyond the first steps of "decouple, add mass, damp panels, and insulate" and it sounds like you've got that part down. I'm certainly not an expert, but I've seen a lot of the little tricks like leaving a gap between the drywall panels and the floor/adjoining panel/etc., which you then use acoustic sealant to close up. Make sure you don't short-circuit your decoupling by screwing anything into studs.Make sure you seal ALLLLLL penetrations like electrical boxes and switches, use backer boxed for can lights, spray foam to seal up wire entry holes in the framing, etc. Figure out how you're going to handle your door... solid core with added mass? Automatic door bottom and perimeter seal kit?

When you're spending big money on the full package like you mentioned, you might as well go all the way in on the other items because they will make a difference.


----------



## mkiv808

Here’s a potentially dumb question.

I have clips and channel to decouple my walls. I’ll be leaving a 1/4” gap between all drywall to fill with acoustic sealer. 

The question is on crown molding. Since it essentially connects the ceiling and side wall, wouldn’t it hurt the decoupling? Any way around this or alternatives to get a similar look?


----------



## niccolo

mkiv808 said:


> Here’s a potentially dumb question.
> 
> I have clips and channel to decouple my walls. I’ll be leaving a 1/4” gap between all drywall to fill with acoustic sealer.
> 
> The question is on crown molding. Since it essentially connects the ceiling and side wall, wouldn’t it hurt the decoupling? Any way around this or alternatives to get a similar look?



Is your ceiling also decoupled, or just your walls? If your ceiling is decoupled, the crown molding is fully internal to the "room within a room," right?


Having said that, I think crown molding gets nailed into framing, not just drywall. If that's the case, it would at least couple with the wall framing and create at least a modest soundproofing liability. I'm not sure whether crown molding also gets nailed into the ceiling, probably depends on the particular molding.


Curious to hear others chime in.


----------



## mkiv808

Both ceiling and walls will be decoupled. I was under the impression that it’s better when they can “move” independently


----------



## noysboy

Flooring question: I've tried doing some searches, but havent found a lot when it comes to decoupling from a concrete floor.

Im in the early stages of planning a basement theater room-within-a-room on a concrete slab with other living spaces adjoining. The walls and ceiling will be decoupled but since the concrete floor is shared do I also need to lay down something like MLV and OSB, then build the walls on top of the subflooring?


----------



## pkinneb

noysboy said:


> Flooring question: I've tried doing some searches, but havent found a lot when it comes to decoupling from a concrete floor.
> 
> Im in the early stages of planning a basement theater room-within-a-room on a concrete slab with other living spaces adjoining. The walls and ceiling will be decoupled but since the concrete floor is shared do I also need to lay down something like MLV and OSB, then build the walls on top of the subflooring?


I used cut up mats (3 1/2” strips) I bought from Tractor Supply under my bottom plates.


----------



## noysboy

pkinneb said:


> I used cut up mats (3 1/2” strips) I bought from Tractor Supply under my bottom plates.


Are you concerned with bass vibrations through the floor to outside the room? or is a subfloor not needed?


----------



## pkinneb

noysboy said:


> Are you concerned with bass vibrations through the floor to outside the room? or is a subfloor not needed?


Hmm honestly I didn't think about it so hopefully others chime in on that one. However in a basement where water events can happen you would not want to put a wall on top of a base floor. If you ever had a flood you would need to remove the entire wall to get the floor up. I have read where folks have used horse mats or the mats I purchased on the whole floor but even there I would cut strips for under the base plates.

you can see in this pick the black under the inner wall, that is the mat.









A couple notes about my set up. First I will have less bass in my room than many folks. My rear riser is a BOSS platform so it is on rubber isolators with 4 JBL 12" subs and also one of my two HSU VTF-3 MK5's. The front row will have a mini BOSS with 4 JBL 12" subs but again on isolators. The only sub that is not on isolators is the front VTF-3 on my stage which is full of sand.


----------



## noysboy

pkinneb said:


> Hmm honestly I didn't think about it so hopefully others chime in on that one. However in a basement where water events can happen you would not want to put a wall on top of a base floor. If you ever had a flood you would need to remove the entire wall to get the floor up. I have read where folks have used horse mats or the mats I purchased on the whole floor but even there I would cut strips for under the base plates.
> 
> you can see in this pick the black under the inner wall, that is the mat.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> A couple notes about my set up. First I will have less bass in my room than many folks. My rear riser is a BOSS platform so it is on rubber isolators with 4 JBL 12" subs and also one of my two HSU VTF-3 MK5's. The front row will have a mini BOSS with 4 JBL 12" subs but again on isolators. The only sub that is not on isolators is the front VTF-3 on my stage which is full of sand.


Hmm, interesting point about building walls on the subfloor. Maybe I should do like you did and build the walls on rubber strips, then put an osb subfloor inside the room. 
My concern is that there is a bedroom that is close and Id like to try to isolate bass as much as possible.


----------



## pkinneb

noysboy said:


> Hmm, interesting point about building walls on the subfloor. Maybe I should do like you did and build the walls on rubber strips, then put an osb subfloor inside the room.
> My concern is that there is a bedroom that is close and Id like to try to isolate bass as much as possible.


You could definitely do mats under the subfloor hopefully others will chime in about the cost/work benefit of doing this.


----------



## Ladeback

Some people have put down the horse mats, then OSB on top of that. I was thinking of maybe using Dricore or DMX . Both create a barrier from the concrete floor below. You would cut it around a 1/4" from the side walls. It would go in after the walls are up. I am not to worried about my basement getting water in it unless we get a lit of rain and lose power for a day or more to where my sump pump can't pump the water out. Only hope close once in over 12 years. I to won't have a lot of base to start, but will plan to add more subs when I can. I am planning on the BOSS system as well.


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## jcr159

Ladeback said:


> Some people have put down the horse mats, then OSB on top of that. I was thinking of maybe using Dricore or DMX . Both create a barrier from the concrete floor below. You would cut it around a 1/4" from the side walls. It would go in after the walls are up. I am not to worried about my basement getting water in it unless we get a lit of rain and lose power for a day or more to where my sump pump can't pump the water out. Only hope close once in over 12 years. I to won't have a lot of base to start, but will plan to add more subs when I can. I am planning on the BOSS system as well.


Usually if you do dri core or similar, you build your walls on top of the subfloor since it’s providing a thermal break...


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## Ladeback

jcr159 said:


> Usually if you do dri core or similar, you build your walls on top of the subfloor since it’s providing a thermal break...


Not if you are worried about water eventually getting in and you have to remove the dricore. I used treated lumber for my bottom plates so not worried about the thermal break. I remember @BIGmouthinDC suggested not building the walls on top of dricore or something like it in the basement so if you ever have to remove it it not under the walls, but I could be wrong.


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## jcr159

Ladeback said:


> Not if you are worried about water eventually getting in and you have to remove the dricore. I used treated lumber for my bottom plates so not worried about the thermal break. I remember @BIGmouthinDC suggested not building the walls on top of dricore or something like it in the basement so if you ever have to remove it it not under the walls, but I could be wrong.


You are right that if moisture comes in it makes replacement easier, but if there’s enough moisture to force replacing dri core, the pressure treated bottom plates would be best to be replaced too... though theoretically they could be dried out... pressure treated isn’t water proof, but I understand the thought... from a comfort and thermal and capillary break perspective, I’d rather keep the walls out of contact with the concrete, but I’m fortunate to not have to worry about moisture. If I did, I’d probably think harder about how to go... from a sound containment perspective it really depends on how the walls are attached to the rest of the structure as to whether it matters much....

Interesting conversation and good for thought!


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## noysboy

jcr159 said:


> from a sound containment perspective it really depends on how the walls are attached to the rest of the structure as to whether it matters much....


In my case, im not worried about water, just sound containment..and especially bass. If I float the walls on some sort of rubber mat, and also float the stage that the subs will be on, will that be enough? It would be great if I dont need a subfloor, but I was assuming I did...which is why I posted here looking for advice!


----------



## jcr159

noysboy said:


> In my case, im not worried about water, just sound containment..and especially bass. If I float the walls on some sort of rubber mat, and also float the stage that the subs will be on, will that be enough? It would be great if I dont need a subfloor, but I was assuming I did...which is why I posted here looking for advice!


I think your approach for the floor sounds pretty good. I generally see advice for basements to just keep the walls detached from the concrete walls and to use IB3 clips to decouple the top plate from the floor joists above. After that I’ve heard anecdotal evidence that decoupling just each sub with isolation pads/feet/squishy stuff did enough to reduce the flanking through the concrete floor... that’s another way to go if you aren’t looking to do a full subfloor for other reasons... just decouple each sub individually... certainly less labor! 😆


----------



## htpc-geek

I posted this in my build thread, but haven't got any replies on it, so I'll try here.

I would really love some feedback on the clips/channel layout I came up with below. I planned ahead with my soundproof boxes and was able to get my atmos backer boxes and all (except one HVAC penetration in the AV closet) to land between the hat channel, so the channel lays out pretty smooth across the room.

However, my joists are 19.2" on center engineered 2x4 trusses. That kind of blows up up the standard 24" x 48" staggered clip spacing — unless I went crazy with 2x4 blocking. Furthermore, due to the atmos backers and 4 big HVAC joist silencers, there are several spots I can't even do blocking, so when I tried doing a 48" spaced layout in sketchup it looked like a mess. Instead, using a 24" x 38.4" staggered spacing is a lot cleaner. The clip count isn't that much more either (just a 10% difference).

With a 48" pattern, I get 89 clips, with 64 of them requiring blocking between the joists
With a 38.4" pattern, I get 97 clips, with only 25 of them requiring blocking (all of which are end clips where I don't have joists)

The ceiling area is 410 square feet, which is about 1800 lbs of 5x8" DD (plus whatever GG weighs). That puts 18.5 lbs on each clip.

Does this look like a good clip layout for the room, or am I missing something?


----------



## mhutchins

Have you considered increasing the spacing between the hat channels to maybe 30". You are well within the weight range for the clip loading, so you should be able to safely increase the spacing and eliminate one or two rows of hat channel. So rather than having 10% more clips than planned, actually go with less and save a little time and money. This may also somewhat improve the low frequency acoustics vs. the higher clip count.

Mike


----------



## htpc-geek

mhutchins said:


> Have you considered increasing the spacing between the hat channels to maybe 30". You are well within the weight range for the clip loading, so you should be able to safely increase the spacing and eliminate one or two rows of hat channel. So rather than having 10% more clips than planned, actually go with less and save a little time and money. This may also somewhat improve the low frequency acoustics vs. the higher clip count.
> 
> Mike


That would work for weight, but don't you want the edge of the drywall to land on hat channel? If I did 30" spacing, the 4'x8' drywall wouldn't land on the hat channel. The first sheet would hang 18" unsupported past it. The first channel is close to the starting wall, then there needs to be one 48" in from that wall for the drywall to screw into for support. Unless I'm missing something. I'll admit I haven't done a lot of drywall.


----------



## mkiv808

Can any acoustic putty be used on IC rated can lights?


----------



## mhutchins

htpc-geek said:


> That would work for weight, but don't you want the edge of the drywall to land on hat channel? If I did 30" spacing, the 4'x8' drywall wouldn't land on the hat channel. The first sheet would hang 18" unsupported past it. The first channel is close to the starting wall, then there needs to be one 48" in from that wall for the drywall to screw into for support. Unless I'm missing something. I'll admit I haven't done a lot of drywall.


Ahhhh, yes. You are exactly right. Obviously I haven't done this before...  Your layout looks great!

Mike


----------



## tcjohnsson

We are currently in the process of designing a house which abuts (walls are about 15 feet away from the actual roadway) a very loud section of road. The primary concern is isolating the interior of the home from the traffic noise which consists of very high and low frequency noise from modified mufflers on cars and motorcycles. I am constructing a home theater that also abuts this section of road. 

The exterior wall assembly is currently:

1/2" densglass sheeting with EIFS finish
1 sheet 3/4" plywood
green glue
1 sheet 3/4" plywood
2x4 stud with Roxul safe and sound insulation
5/8" drywall
green glue
5/8" drywall

I am not sure if it's necessary to install resilient sound isolation clips in this assembly (to reduce traffic noise) but I am leaning towards installing them in at least the bedroom and home theater. I would appreciate any recommendations on sound clips (Whisper, Genie, etc) which would be most effective in this application. 

Because a lot of this very loud traffic noise will also be entering through the roof/ceiling I am installing Roxul insulation in the roof rafters as well as the ceiling rafters. I will have two layers of drywall with green glue for the ceilings throughout the entire home and only plan on installing RSI clips in the ceilings in the home theater and bedrooms. Again, any recommendations for sound clips here would be very appreciated. Is it recommended to install additional drywall (e.g. on TOP of the ceiling rafters) or will the roof itself provide decent sound isolation into the attic so that a robust ceiling assembly is not necessary? 

There is no budget but I don't want to throw away money unnecessarily. Any feedback is much appreciated!


----------



## Tim Duggan

*Soundproofing a Basement Room - Is my plan sound? (pun intended)*

Hi All,

I'm hoping to get some feedback on my plan below ...there is also a question regarding the joists in there.

I have a room in my basement, appx 12' x 12', that I'm converting to be a drum room (my 10 year old son is learning) and rehearsal room (I play bass and hope to have the guys over to practice). 

The good news: the room is raw (unfinished), a very manageable size with mostly straight lines, has no duct work (radiant heat with asbestos covered pipes), and has concrete walls that have earth to about 3/4 of their height. 

The bad news: there are two windows (though not large ones), the living room (where we spend much of our time) is directly above, it abuts the staircase, and the ceiling is low .. 8" joists are at about 6' 11.5".

My plan is:

ceiling: One layer of 3" Sound and Fire mineral wool insulation against the flooring above. add 6" joists dropped 1" below existing joists and between them (under the insulation). Add one layer of 3" insulation between new floating joists flush with bottom (2.5" air gap between insulation layers). 1/2" drywall to edges of unframed room. Greenglued layer of 5/8" quietrock over that to edges of unframed room.

walls will be built up to drywall ceiling with any gaps filled with gg sealant

concrete walls: framed 2x4 stud wall with 5/8" drywall on one side, 3" mineral wool, 1/2" drywall on the other side, 2"+ gap between outside drywall and concrete ... special "plugs" will be made to deal with windows.

interior walls: double studded on 8x2" footer ... double insulation (3" min wool) in each set of studs with a gap between. double drywall (5/8" and 1/2") on each side....gap between these walls and existing walls/structure

door: bought heavy-weight hinges and will build a section of double wall in the same fashion that will swing inward (think secret bookcase door).

One Big Q: The floating joists I have are below the floor by 3 inches or so and don't touch the existing joists, but they are currently hung with toe-notches on the existing wall headers (old, hard, 1906 hardwood 2x8s). Given all the layers on them, will they transfer sound into the header, then the original joists, and give me significant noise? Do I need to consider cutting them to the interior wall (in a wall)? My BIGGEST need is to keep noise from travelling up...sideways is way less of a concern.

BTW - this is a free standing single family home. Thanks in advance!


----------



## mhutchins

Tim Duggan said:


> Hi All,
> .
> .... that I'm converting to be a drum room ....
> 
> My plan is:
> 
> ceiling: One layer of 3" Sound and Fire mineral wool insulation against the flooring above. add 6" joists dropped 1" below existing joists and between them (under the insulation). Add one layer of 3" insulation between new floating joists flush with bottom (2.5" air gap between insulation layers). 1/2" drywall to edges of unframed room. Greenglued layer of 5/8" quietrock over that to edges of unframed room.
> 
> Support the ceiling rafters on the walls you intend to build, mentioned below. Do not support them by the same header supporting the existing floor joists. Use *at least 2 layers of 5/8" Type X*, preferably 3 layers. Completely fill the space between the header of the new walls and the existing concrete walls with mineral wool to form a fire stop. (it's OK to leave an air gap between the new walls and the existing walls, except at the top, as mentioned above).
> 
> walls will be built up to drywall ceiling with any gaps filled with gg sealant
> 
> concrete walls: framed 2x4 stud wall with 5/8" drywall on one side, 3" mineral wool, 1/2" drywall on the other side, 2"+ gap between outside drywall and concrete ... special "plugs" will be made to deal with windows.
> 
> NO, do not add the 1/2" drywall between the new stud wall and the concrete. This will actually INCREASE the sound transmission. Instead, use 2-3 layers of 5/8" Type X on the inner surface only, for all of your new walls.
> 
> interior walls: double studded on 8x2" footer ... double insulation (3" min wool) in each set of studs with a gap between. double drywall (5/8" and 1/2") on each side....gap between these walls and existing walls/structure
> 
> door: bought heavy-weight hinges and will build a section of double wall in the same fashion that will swing inward (think secret bookcase door).
> 
> One Big Q: The floating joists I have are below the floor by 3 inches or so and don't touch the existing joists, but they are currently hung with toe-notches on the existing wall headers (old, hard, 1906 hardwood 2x8s). Given all the layers on them, will they transfer sound into the header, then the original joists, and give me significant noise? Absolutely!
> Do I need to consider cutting them to the interior wall (in a wall)? * YES *My BIGGEST need is to keep noise from travelling up...sideways is way less of a concern.
> 
> BTW - this is a free standing single family home. Thanks in advance!


Consider double communicating doors, as well, but you could easily add this later if you do the door rough-in during framing. You need to plan on some form of ventilation using separate supply and return ducts, otherwise the room will become unbearable in just a few minutes of aggressive drumming. The easiest solution is a pair of dead vents and a fan to circulate air between the practice room and the rest of the basement. And yes, use Green Glue between all layers of drywall and don't use light weight drywall. Mass is your friend!

Good luck with your build!

Mike


----------



## HT Geek

Tim Duggan said:


> My plan is:
> 
> ceiling: One layer of 3" Sound and Fire mineral wool insulation against the flooring above. add 6" joists dropped 1" below existing joists and between them (under the insulation). Add one layer of 3" insulation between new floating joists flush with bottom (2.5" air gap between insulation layers). 1/2" drywall to edges of unframed room. Greenglued layer of 5/8" quietrock over that to edges of unframed room.


Avoid the S&F mineral wool touching the floor above directly if at all possible. It's preferable to have a slight air gap to break the physical connection since that product is more "solid" than say "pink fluffy" (i.e. common pink fiberglass insulation).

I noticed in your photo that you appear to have staggered floor joists. That's a plus, as it means the ceiling of this room won't directly contact the floor joists above. Do you intend to float new joists off what appear to be the current ceiling joists (non-painted/stained joists with hangars shown in photo)?

I don't know enough about drum practice to understand how much bass you will have to deal with, but I would think most frequencies would be higher than the LFE freqs often discussed in this forum in terms of mitigation.




> walls will be built up to drywall ceiling with any gaps filled with gg sealant


Make sure you have backer rod on hand for larger gaps. You may already know that, but I'm stating it here for completeness and to (potentially) save you a trip to the hardware store at an inopportune moment.



> concrete walls: framed 2x4 stud wall with 5/8" drywall on one side, 3" mineral wool, 1/2" drywall on the other side, 2"+ gap between outside drywall and concrete ... special "plugs" will be made to deal with windows.


Are you thinking of placing drywall on both sides of a new stud wall, built adjacent to exterior concrete walls? Please don't do that. You'll be creating a triple-leaf design (bad). Leave the drywall off the concrete-facing side and maintain the remainder of your strategy. Instead, apply that drywall sheet to the inside of the room. Also, there is no (acoustic) need for a 2" gap to the concrete wall. 1" is a good benchmark to allow for variations while keeping your inner walls straight. Any gap width is fine (figure 1/4" or more). Choosing a uniform value (e.g. 1") simply allows for variation.




> interior walls: double studded on 8x2" footer ... double insulation (3" min wool) in each set of studs with a gap between. double drywall (5/8" and 1/2") on each side....gap between these walls and existing walls/structure


You've confused me here. Are you considering an 2x8 footer? Laid how? 8" perpendicular to the floor, so you have a 7.5" wide interior wall? Are you building a fortress??? LoL. 

Are you certain you wish to sacrifice that much space? Double studded on 2x8's would be 2x8 + air gap + 2x8. That's a hugely thick wall, and x2 with opposite walls, you're going to make the final room really small. I suspect it's more likely you are envisioning placing a double stud 2x4 configuration _on top of_ a 2x8, which would be a poor idea. You would be coupling your double stud wall, thereby defeating the purpose of it (you'd short circuit the benefit of the air gap between the wall sections).




> door: bought heavy-weight hinges and will build a section of double wall in the same fashion that will swing inward (think secret bookcase door).


A word of caution: mind the gaps. Conceptually, it's very cool. However, for it to function properly in terms of acoustic containment, it requires a design accommodating blocking sound from leaking through cracks. For example, a staggered shape or 2-piece system that allows the introduction of rubber stops into the design. Building a secret door that is properly designed for blocking light and sound penetration through it is challenging (but super cool).




> One Big Q: The floating joists I have are below the floor by 3 inches or so and don't touch the existing joists, but they are currently hung with toe-notches on the existing wall headers (old, hard, 1906 hardwood 2x8s). Given all the layers on them, will they transfer sound into the header, then the original joists, and give me significant noise? Do I need to consider cutting them to the interior wall (in a wall)? My BIGGEST need is to keep noise from travelling up...sideways is way less of a concern.


They are going to transmit sound and vibration as you surmised, yes, but only because (based on what I see in your photo) there seems to be a physical connection around the perimeter. Both old and new joists appear to connect to the same headers. However, you're currently starting from a position that is superior to a typical modern home (where the basement ceiling joists are the same as the 1st floor joists). That said, if I were in your position, I'd also be considering how to go about creating a superior isolation method between the floors. 

You could use what you already have. It will be a better-than-average solution. However, I suspect it would not meet your desired outcome. [idea no. 1]

You have several options. One would be clips and channel, suspended from the (more recently installed) ceiling joists. [idea no. 2]

You could remove the new (current) ceiling joists and build a true room-within-a-room by creating floating joists on top of your inner double-stud wall. [idea no. 3] The biggest disadvantage is reduced ceiling height in the final room. If that's not an issue, then I'd recommend going this route as it gives you maximum isolation from the room above. There will be no connection between the floor above and ceiling of this room. One catch is you must be conscientious of correctly calculating the load bearing requirements of your floating room. That's not difficult in your case as the room will be quite small. A safe bet is 2x6 joists. 2x4's may be possible, but would require calculating load and joist offsets to confirm whether it's an option. I generally don't like 2x4's as ceiling joists even for small rooms, simply because it is difficult to find enough truly straight 2x4's these days. You won't notice such minor imperfections in your walls, but you might in your ceiling.

I can help you run the engineering calcs for load bearing if you feel the need to seriously consider using 2x4's for a floating ceiling, and then you can decide if it's worthwhile. If you can live with the extra 2" of height lost from 2x6's then I'd just go the 2x6 route. As long as your spans are


----------



## CanVanMan

Hi there. I have a new house with a truss floor system. There is a hardwood in the main floor and I have a finished basement. However there is zero soundproofing between the floors. Basically I have a huge open cavity between the main floor and the basement. How should I address this?

1) rip out drywall ceiling. 
2) green glue rigid insulation between the joists to the subfloor
3) add insulation bats
4) add channels
5 replace drywall ceiling. 

Or should I blow in loose insulation?



Also. What is the best underpad for impact noise for my second floor where I have carpeting.


----------



## HT Geek

CanVanMan said:


> Hi there. I have a new house with a truss floor system. There is a hardwood in the main floor and I have a finished basement. However there is zero soundproofing between the floors. Basically I have a huge open cavity between the main floor and the basement. How should I address this?
> 
> 1) rip out drywall ceiling.
> 2) green glue rigid insulation between the joists to the subfloor
> 3) add insulation bats
> 4) add channels
> 5 replace drywall ceiling.
> 
> Or should I blow in loose insulation?
> 
> Also. What is the best underpad for impact noise for my second floor where I have carpeting.


Hate to tell you this, but that's kind of a loaded question on this forum. LoL.  IOW, most answers to that question are either going to be "yes" or "it depends."

First off, don't use blown-in insulation. At least personally, I absolutely hate that stuff. If you ever decide you want/need an alternate solution for any reason, it's such a pain to deal with. Furthermore, from a sound-proofing perspective it's not worthwhile to mess with it. Blown-in insulation was developed by the construction industry to save time and make applying insulation more efficient. Just remember that. It has nothing to do with helping you out as a homeowner. In fact, I would argue the only "good" type of blown insulation is the industrial stuff that is applied to exposed metal surfaces as a fire retardant (which is "good" for obvious reasons). And even that is not really insulation (even though it is often mistakenly called that).

Now, back to your home....

What are your goals?


----------



## CanVanMan

Thanks. I want to reduce the sound of the waking above and voices. It doesn’t need to be “perfect” but it needs to be muted.


----------



## HT Geek

CanVanMan said:


> Thanks. I want to reduce the sound of the waking above and voices. It doesn’t need to be “perfect” but it needs to be muted.


Understood. More questions:

What type of flooring is on the 1st floor?

Is your only concern muting sound from 1st floor into basement, or do you also want to mute the reverse (noise from basement emanating through the floor to 1st level)?

Will you be performing the work yourself or hiring a contractor?

How large is the space to be sound proofed? A single room? Entire basement?

Is the current basement finished or unfinished?


----------



## CanVanMan

It’s a plywood subfloor with oak hardwood. 
It is a large open space. 18x35. 
It’s finished but I’m willing to pull down the dry wall ceiling. 
Sound from below up is a benefit too. 
My dream is to sit down there and barely hear walking or other noises from above.


----------



## macming

Question for the experts. I'm in the process of building a theatre room and I've taken some steps to ensure sound proofing:

Insulation batts in the ceiling cavity
Two interior walls with 1" air gap
I have acoustic caulk & green glue ready
2 layers of 5/8" drywall on all interior surfaces

I'm debating between the best sound proofing solution for the ceiling:


option 1: Sonopan + 5/8" drywall
option 2: 2 layers of 5/8" drywall + green glue

Which option would be more effective? Is it possible to use green glue between Sonopan and 5/8" drywall? I'm not sure if I should just introduce option 3 at this point - Sonopan + 2 layers of 5/8" drywall + green glue. 

There is also an option to use Reflex-or between the two sheets of 5/8" drywall instead of green glue, but I don't know if that is a proven option at all. 

Many thanks,

Ming


----------



## Ladeback

macming said:


> Question for the experts. I'm in the process of building a theatre room and I've taken some steps to ensure sound proofing:
> 
> Insulation batts in the ceiling cavity
> Two interior walls with 1" air gap
> I have acoustic caulk & green glue ready
> 2 layers of 5/8" drywall on all interior surfaces
> 
> I'm debating between the best sound proofing solution for the ceiling:
> 
> 
> option 1: Sonopan + 5/8" drywall
> option 2: 2 layers of 5/8" drywall + green glue
> 
> Which option would be more effective? Is it possible to use green glue between Sonopan and 5/8" drywall? I'm not sure if I should just introduce option 3 at this point - Sonopan + 2 layers of 5/8" drywall + green glue.
> 
> There is also an option to use Reflex-or between the two sheets of 5/8" drywall instead of green glue, but I don't know if that is a proven option at all.
> 
> Many thanks,
> 
> Ming



I had to look up Sonopan, I had never heard of it. From what I have learned you want decoupling, mass, absorption and damping. I would think if you use the Sonopan it should go on the last layer I am guessing. for my theater I was going to do 2 layers of 5/8" drywall between the joist with Green Glue, clips and hat channel, 2 more layers of 5/8" drywall and Green Glue.

Like this for Level 3:

https://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-ceilings

I would think drywall would be better and cheaper then the Sonopan stuff. That's just my two cents on it. Others may chime in after the holiday's are over.


----------



## mhutchins

I looked up Sonopan but the manufacturer did not include any test data that I could find on their web page. As a result of no test data and substantially less mass than 5/8 Type X drywall, I think the double drywall with Green Glue option will give you better results. Option 3 is what is shown on the Mfg’s web page, but I suspect a 3rd layer of drywall would be cheaper and more effective.

Mike


----------



## warwwolf7

mhutchins said:


> I looked up Sonopan but the manufacturer did not include any test data that I could find on their web page. As a result of no test data and substantially less mass than 5/8 Type X drywall, I think the double drywall with Green Glue option will give you better results. Option 3 is what is shown on the Mfg’s web page, but I suspect a 3rd layer of drywall would be cheaper and more effective.
> 
> Mike


Between
A: sonopan + drywall 
B: drywall + drywall
Choose b to reduce noise transmission.

Sonopan is more expensive if I recall correctly. It's not as dense as 5/8 type x drywall. Maybe the panels would be better used as part of an assembly for acoustic panel, but not to reduce acoustical transmission

Cheers 

-Matt


----------



## HT Geek

macming said:


> I'm debating between the best sound proofing solution for the ceiling:
> 
> 
> option 1: Sonopan + 5/8" drywall
> option 2: 2 layers of 5/8" drywall + green glue
> 
> Which option would be more effective? Is it possible to use green glue between Sonopan and 5/8" drywall? I'm not sure if I should just introduce option 3 at this point - Sonopan + 2 layers of 5/8" drywall + green glue.
> 
> There is also an option to use Reflex-or between the two sheets of 5/8" drywall instead of green glue, but I don't know if that is a proven option at all.


Option 3: 5/8" drywall + green glue + 5/8" drywall + green glue + 5/8" drywall

Per comments above, it's unfortunate, but you are going to find a lot of snake-oil salesmen in the A/V business. The prevailing wisdom on this forum is no published independent lab test results = don't even consider it. Furthermore, once you have tackled decoupling, mass is the most significant factor (i.e. add more drywall is the best choice under most circumstances).


----------



## HT Geek

CanVanMan said:


> Thanks. I want to reduce the sound of the waking above and voices. It doesn’t need to be “perfect” but it needs to be muted.


The "devil is in the details" in the sense every custom room has a unique set of variables. However, setting that fact aside for a moment....

What you'll be endeavoring to do is mute two types of sound effects: airborne noise (HT room up to room above) and impact noise (1st floor into HT room). Therefore, you need a solution that works well under both circumstances.

The tried-and-true methods on this forum will apply to you. Your best bet is going to be a combination of:

1. Room-within-a-room (dedicated and isolated HT room in the basement); preferably double stud walls and floating ceiling; 2x 5/8" drywall / Green Glue sandwich on the interior of the interior stud wall
2. If no. 1 is not an option, look at clips & channel or a combination of clips & channel and staggered or double stud walls. For instance, clips & channel ceiling if you are height constrained in the HT room.
3. In your case I would strongly recommend applying drywall sheets in the joist cavities of your basement (below the 1st floor); i.e. 5/8" drywall + Green Glue + 5/8" drywall sandwich
4. After you've done no. 3 above, apply "pink fluffy" (i.e. fiberglass) or mineral wool (Roxul) insulation bats between the pre-existing ceiling joists (basement ceiling), under the drywall sandwiches

You'll need to remove the existing ceiling in your basement.


----------



## macming

Thanks everyone for your insightful feedback. I ended up going with option 3: Sonopan + 5/8 drywall + green glue + 5/8 drywall. During my early days of research, I was told unless if I wanted to do infloor heating and remove all heating ducts in the room, it doesn't make too much difference with my sound proofing treatments. Instead the video suggested to shoot for a solution that offered STC50 or so. 

I found a bit of stats on Sonopan, but it may not mean too much because the document is not readily available on the Sonopan site. 



Ladeback said:


> I had to look up Sonopan, I had never heard of it. From what I have learned you want decoupling, mass, absorption and damping. I would think if you use the Sonopan it should go on the last layer I am guessing. for my theater I was going to do 2 layers of 5/8" drywall between the joist with Green Glue, clips and hat channel, 2 more layers of 5/8" drywall and Green Glue.
> 
> Like this for Level 3:
> 
> https://www.soundproofingcompany.com/soundproofing-solutions/soundproofing-ceilings
> 
> I would think drywall would be better and cheaper then the Sonopan stuff. That's just my two cents on it. Others may chime in after the holiday's are over.


I've never heard of Sonopan until I saw a FB ad either. I contemplated doing level 3 with my theatre, but my contractor refused to attach drywall to the subfloor because the sheets could fall off and get in the way if I ever want the floor upstairs replaced. 




mhutchins said:


> I looked up Sonopan but the manufacturer did not include any test data that I could find on their web page. As a result of no test data and substantially less mass than 5/8 Type X drywall, I think the double drywall with Green Glue option will give you better results. Option 3 is what is shown on the Mfg’s web page, but I suspect a 3rd layer of drywall would be cheaper and more effective.
> 
> Mike


After I had Sonopan installed, I suspect that it may not do that much either. If I were to do it again, I'll prob opt for 3 sheets of drywall with Green Glue. 



warwwolf7 said:


> Between
> A: sonopan + drywall
> B: drywall + drywall
> Choose b to reduce noise transmission.
> 
> Sonopan is more expensive if I recall correctly. It's not as dense as 5/8 type x drywall. Maybe the panels would be better used as part of an assembly for acoustic panel, but not to reduce acoustical transmission
> 
> Cheers
> 
> -Matt


I have 2.5 sheets of Sonopan left over, and I think the dimples will work as a diffusor of some sort - similar to how TAD panels may work. I'm going to try to use the left over as the room facing layer of acoustic panels. This would be interesting! 



HT Geek said:


> Option 3: 5/8" drywall + green glue + 5/8" drywall + green glue + 5/8" drywall
> 
> Per comments above, it's unfortunate, but you are going to find a lot of snake-oil salesmen in the A/V business. The prevailing wisdom on this forum is no published independent lab test results = don't even consider it. Furthermore, once you have tackled decoupling, mass is the most significant factor (i.e. add more drywall is the best choice under most circumstances).


Agreed!



HT Geek said:


> The "devil is in the details" in the sense every custom room has a unique set of variables. However, setting that fact aside for a moment....
> 
> What you'll be endeavoring to do is mute two types of sound effects: airborne noise (HT room up to room above) and impact noise (1st floor into HT room). Therefore, you need a solution that works well under both circumstances.
> 
> The tried-and-true methods on this forum will apply to you. Your best bet is going to be a combination of:
> 
> 1. Room-within-a-room (dedicated and isolated HT room in the basement); preferably double stud walls and floating ceiling; 2x 5/8" drywall / Green Glue sandwich on the interior of the interior stud wall
> 2. If no. 1 is not an option, look at clips & channel or a combination of clips & channel and staggered or double stud walls. For instance, clips & channel ceiling if you are height constrained in the HT room.
> 3. In your case I would strongly recommend applying drywall sheets in the joist cavities of your basement (below the 1st floor); i.e. 5/8" drywall + Green Glue + 5/8" drywall sandwich
> 4. After you've done no. 3 above, apply "pink fluffy" (i.e. fiberglass) or mineral wool (Roxul) insulation bats between the pre-existing ceiling joists (basement ceiling), under the drywall sandwiches
> 
> You'll need to remove the existing ceiling in your basement.


For my interior walls, I managed to convince my contractor to build 2 layers of walls and cover 3 surfaces with 5/8" drywall. Every surface inside the HT room has at least two layers of 5/8" drywall with green glue. 

I couldn't convinced my contractor to install drywall in the joist cavities so I ended up with 3 layers in the ceiling. Hopefully that's good enough anyways.


----------



## Ladeback

I don't see how the sheets would fall off between the joists when Green Glue and screws are used to attach them. When contractors don't understand something they come up with some funny ideas. This is why I plan to do most of my work myself. Hope it all works. I think my wife understands why I want to soundproof my theater after I was watching Aquaman yesterday while her mom and her were putting Christmas decorations away. I only have one 12" sub running powered by 200 watts. If I ever get my 15" subs working it is really going to drive her nuts.

I hope to plan on doing level 3 from Soundproofing company for the ceiling. I will decouple walls with IB-3 clips and double drywall with Green Glue. 

Sent from my SM-N960U using Tapatalk


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## macming

Ladeback said:


> I don't see how the sheets would fall off between the joists when Green Glue and screws are used to attach them. When contractors don't understand something they come up with some funny ideas. This is why I plan to do most of my work myself. Hope it all works. I think my wife understands why I want to soundproof my theater after I was watching Aquaman yesterday while her mom and her were putting Christmas decorations away. I only have one 12" sub running powered by 200 watts. If I ever get my 15" subs working it is really going to drive her nuts.
> 
> I hope to plan on doing level 3 from Soundproofing company for the ceiling. I will decouple walls with IB-3 clips and double drywall with Green Glue.
> 
> Sent from my SM-N960U using Tapatalk


I totally get where you're coming from. Time is hard to come by these days. Otherwise, I'd totally do it myself. 

I'm going to run two 18" LMS Ultra with 7000 watts peak, so I think I'm going to have a problem regardless of what I do.


----------



## HT Geek

macming said:


> I couldn't convinced my contractor to install drywall in the joist cavities so I ended up with 3 layers in the ceiling. Hopefully that's good enough anyways.


You will likely be fine. The purpose of drywall in between the original ceiling joist cavities in the basement was primarily to add additional muffling of impact noise from the floor above the HT room. However, with a room-within-a-room double stud configuration and a thick ceiling within that inner room, it's not very likely you will have any issues regardless.

Now, having said that, I don't quite understand the reluctance on the part of your contractor to add the drywall between the joists. It sounds as if he may have misunderstood the concept. I can't see how it would have any possible impact on the flooring of the 1st floor above, since it would be attached to the underside of what is the sub-floor for your 1st floor level (basement facing side). There would be no reason to - for example - rip out your 1st floor's sub-floor when replacing the finished floor material at some future date. The only reason sub-floor is ever replaced is when there's something wrong with it. The most common reason for that is water damage from a burst pipe. All scenarios that have nothing to do with the underside of that sub-floor. Even if you ever did need to replace it, big whoop. You would be yanking some additional drywall with it (from beneath).




Ladeback said:


> I don't see how the sheets would fall off between the joists when Green Glue and screws are used to attach them. When contractors don't understand something they come up with some funny ideas. This is why I plan to do most of my work myself. Hope it all works.


+1 !


----------



## Ladeback

@HT Geek, to save a little money would just adding one layer between the joist with Green Glue help? If I keep my room around 14'x25' the cost isn't as bad as if I go larger. 

Sent from my SM-N960U using Tapatalk


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## HT Geek

Ladeback said:


> @HT Geek, to save a little money would just adding one layer between the joist with Green Glue help? If I keep my room around 14'x25' the cost isn't as bad as if I go larger.


I've forgotten the details of your plan. 

Presuming ground floor (no living space below) and a room-within-a-room design, I think it depends on what you're dealing with in terms of floor noise from above into HT room or vice-versa. If there's say hardwood or tile floors above, then impact noise from above into HT room might be a concern. If that is true then I'd do it (drywall in between structural ceiling joists). 

If the concern is more airborne sound from HT room emanating upward into room/floor above, I'd be more inclined to go with an additional layer of drywall (mass) in the ceiling of your "inner" HT room.

If airborne noise from floor above moving down into HT room is the concern (vs. impact), I'd be inclined to add the additional mass in between structural ceiling joists. And for that matter, even if you have no concerns, it won't hurt.

I think it all depends on your use case. You will never regret adding more damping (from a performance perspective). However, at some point we all have to think about the cost and effort vs reward. At least drywall is cheap, so if you perform the labor yourself it's mostly a concern of the Green Glue's cost. It's a chore to add that mass in the ceiling if you intend to be meticulous about sealing gaps (though again, what is your use case)? If the primary concern is impact noise from above, personally I would say even if you are not anal retentive about sealing the perimeter of the drywall pieces inside the joists, that extra mass will help significantly because you're damping that impact noise directly at the source with more mass. If the concern is airborne noise and it's a high priority (presumably why you'd want to take on this extra work in the first place), then I'd be more inclined to take my time and do a good job of sealing the perimeters. You won't get a 2nd chance to add improvements in that space (between joists).


----------



## Ladeback

My room is in my basement under my kitchen and most of my living room. I am thinking of doing it for kind of both reasons you talked about. To help with noise coming in from above when people are walking and to help some with the bass. I know it wont stop it, but should help slow it down. The plan is to decouple the walls to the ceiling above, clips and channel on the ceiling. Double drywall all around with Green Glue. I have one working 12" sub powered only with 200 watts and my wife and mother in law were commenting that it was pretty loud when I was watching Aquaman. I wasn't even near reference. The cost of the Green Glue is what I will have a hard time getting the wife to but off on, but she will understand when its done.

Sent from my SM-N960U using Tapatalk


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## HT Geek

Ladeback said:


> My room is in my basement under my kitchen and most of my living room. I am thinking of doing it for kind of both reasons you talked about. To help with noise coming in from above when people are walking and to help some with the bass.


Gotcha. Coming back to me now. 

I would do the drywall between ceiling joists; especially given you have the kitchen above.

As far as GG is concerned, you will get 80% of the benefit even if you cut the amount of Green Glue in 1/2. For example, one tube per 4x8 drywall sheet instead of the recommended two.


----------



## macming

HT Geek said:


> You will likely be fine. The purpose of drywall in between the original ceiling joist cavities in the basement was primarily to add additional muffling of impact noise from the floor above the HT room. However, with a room-within-a-room double stud configuration and a thick ceiling within that inner room, it's not very likely you will have any issues regardless.
> 
> Now, having said that, I don't quite understand the reluctance on the part of your contractor to add the drywall between the joists. It sounds as if he may have misunderstood the concept. I can't see how it would have any possible impact on the flooring of the 1st floor above, since it would be attached to the underside of what is the sub-floor for your 1st floor level (basement facing side). There would be no reason to - for example - rip out your 1st floor's sub-floor when replacing the finished floor material at some future date. The only reason sub-floor is ever replaced is when there's something wrong with it. The most common reason for that is water damage from a burst pipe. All scenarios that have nothing to do with the underside of that sub-floor. Even if you ever did need to replace it, big whoop. You would be yanking some additional drywall with it (from beneath).
> 
> 
> 
> 
> +1 !


I guess time will tell! My contractor was worried about walking above might make the drywall fall down. I know it's all BS excuses because he's also recommending a single door instead of communicating door (two layers of single doors into the HT). 

Either way, you have to draw the line somewhere and I'm curious to see how my room will turn out.


----------



## Ladeback

macming said:


> I guess time will tell! My contractor was worried about walking above might make the drywall fall down. I know it's all BS excuses because he's also recommending a single door instead of communicating door (two layers of single doors into the HT).
> 
> Seriously, he thought that drywall glue and screwed under the sub floor would fall when walking on the floor above? Sorry I would laughed at him and said how is that possible. I think he didn't want to do it and came up with a silly answer. His thinking is flawed in that there are less screws in ceiling drywall for a two story home and it doesn't fall off the ceiling.
> 
> Either way, you have to draw the line somewhere and I'm curious to see how my room will turn out.
> 
> Glad you are good with it and hope it works for you. It should make a difference.


----------



## pkinneb

macming said:


> I guess time will tell! My contractor was worried about walking above might make the drywall fall down. I know it's all BS excuses because he's also recommending a single door instead of communicating door (two layers of single doors into the HT).
> 
> Either way, you have to draw the line somewhere and I'm curious to see how my room will turn out.


If foot fall above is a concern I would do it. In my room I did hat channel and clips with one layer of OSB, GG, and one layer of 5/8" firerock. You can hear faint footfall from the master bath above. having said that its not a huge issue for us since its our bedroom but if this was a high traffic area I would be bummed.


----------



## HT Geek

macming said:


> I guess time will tell! My contractor was worried about walking above might make the drywall fall down.


Is that your drywall contractor? Have they installed a ceiling before?  

When in doubt, use more screws. The drywall stuck to the underside of ceiling joists need not be finished or pretty. No one will ever see it.



> I know it's all BS excuses because he's also recommending a single door instead of communicating door (two layers of single doors into the HT).


2x single doors constructed how, exactly? Glued together to make a denser, single door? Or one opening in and one opening outward and facing back to back?

I would not do the latter. Unless implemented very thoughtfully, that approach is going to 1) be inconvenient for you (usability/human factor); and 2) make 2x more gaps for sound to leak through if not mitigated (i.e. either more sound leaks or more work to prevent more sound leaks).

The purpose of communicating doors is to create an air pocket that helps to isolate sound on either side of the room. If you can't do that, you're better off with a single heaving massively heavy door (or as close to that as you can get).


----------



## macming

HT Geek said:


> Is that your drywall contractor? Have they installed a ceiling before?
> 
> When in doubt, use more screws. The drywall stuck to the underside of ceiling joists need not be finished or pretty. No one will ever see it.
> 
> 
> 
> 2x single doors constructed how, exactly? Glued together to make a denser, single door? Or one opening in and one opening outward and facing back to back?
> 
> I would not do the latter. Unless implemented very thoughtfully, that approach is going to 1) be inconvenient for you (usability/human factor); and 2) make 2x more gaps for sound to leak through if not mitigated (i.e. either more sound leaks or more work to prevent more sound leaks).
> 
> The purpose of communicating doors is to create an air pocket that helps to isolate sound on either side of the room. If you can't do that, you're better off with a single heaving massively heavy door (or as close to that as you can get).


I'm referring to the latter where _one opening in and one opening outward and facing back to back?_ For the single door, he agreed to attach MDF to both sides of a solid core door and add some more strips of MDF to make a shaker design. For what it's worth, that's good enough for now.

My HT is below the kitchen, but it won't be in use until the kids go to bed. I don't think foot steps will be a huge issue.


----------



## pkinneb

macming said:


> I'm referring to the latter where _one opening in and one opening outward and facing back to back?_ For the single door, he agreed to attach MDF to both sides of a solid core door and add some more strips of MDF to make a shaker design. For what it's worth, that's good enough for now...


You may want to pic a door you like and then add both layers of MDF to one side, may save some effort and money by only having to modify one side of the door.


----------



## macming

pkinneb said:


> You may want to pic a door you like and then add both layers of MDF to one side, may save some effort and money by only having to modify one side of the door.


Good call! Let me ask my contractor.


----------



## Harkon

On the inside of the theatre should I fit 5/8 PB or 5/8 Acoustic PB?
To be fitted to decoupled studs with OSB first layer - probably using Green Glue inbetween the layers.
I'm in the UK but the stated mass and price is as follows:


Standard 5/8 PB 

6.3Kg/m2 
$9-10

Acoustic PB 
11kg/m2 
$14.40


----------



## htpc-geek

Harkon said:


> On the inside of the theatre should I fit 5/8 PB or 5/8 Acoustic PB?
> To be fitted to decoupled studs with OSB first layer - probably using Green Glue inbetween the layers.
> I'm in the UK but the stated mass and price is as follows:
> 
> 
> Standard 5/8 PB
> 
> 6.3Kg/m2
> $9-10
> 
> Acoustic PB
> 11kg/m2
> $14.40


Definitely get the Acoustic. Math says it's the same weight as fire rated type X here in the states, which is what we generally use. Mass is your friend.


----------



## Harkon

Having never used clips and channel before (and I doubt my builder has either), is it straight forward? 

I can afford and have no issues fitting clip and channels, beyond the fact that it makes the build more specialist / complex. Part of me wants to just screw that double PB in to the joists for simplicity. Do you use special screws fit screwing in to the channel? And it holds just like a screw would in a joist? Just looks so thin and flimsy.... -_-

And then, mounting the projector. If my first layer is 3/4 inch OSB, then 5/8 PB, then add extra clips near the projector and just mount to the OSB. Ignore the joists?


----------



## Ladeback

Harkon said:


> Having never used clips and channel before (and I doubt my builder has either), is it straight forward?
> 
> I can afford and have no issues fitting clip and channels, beyond the fact that it makes the build more specialist / complex. Part of me wants to just screw that double PB in to the joists for simplicity. Do you use special screws fit screwing in to the channel? And it holds just like a screw would in a joist? Just looks so thin and flimsy.... -_-
> 
> And then, mounting the projector. If my first layer is 3/4 inch OSB, then 5/8 PB, then add extra clips near the projector and just mount to the OSB. Ignore the joists?



I will try an answer this, but @HTGeek would be a better person to answer.

The easiest answer is to work with a company like The Soundproofing Company and buy their products and they will help you out on what to do. You give them your room dimensions and they will help you with a plan as to where to put the clips. You would install all the clips first, then the hat channel. Make sure to overlap the channels and put some screws in it.

https://www.soundproofingcompany.com/

There are different types of clips, but they all screw into a joist and they should sell you the correct screws for the clips. The correct hat channel is plenty strong to hold up 3 layers of 5/8" drywall with 2 layers of green glue.

You could do your 1st layer with OSB, but I have heard it can be difficult to deal with at times. Again The Soundproofing company could help you out with this as well. You can send them an email and ask them questions. 

Here is an installation video I found.

https://www.google.com/search?q=how...ive&ssui=on#kpvalbx=_lTgeXu66HpP0tAbtnbn4Aw32


----------



## HT Geek

Harkon said:


> On the inside of the theatre should I fit 5/8 PB or 5/8 Acoustic PB?
> To be fitted to decoupled studs with OSB first layer - probably using Green Glue inbetween the layers.
> I'm in the UK but the stated mass and price is as follows:
> 
> 
> Standard 5/8 PB
> 
> 6.3Kg/m2
> $9-10
> 
> Acoustic PB
> 11kg/m2
> $14.40


What is PB? Particle Board? I hope not. It practically crumbles if you even point the business end of a screw at it.




Harkon said:


> Having never used clips and channel before (and I doubt my builder has either), is it straight forward?
> 
> I can afford and have no issues fitting clip and channels, beyond the fact that it makes the build more specialist / complex. Part of me wants to just screw that double PB in to the joists for simplicity. Do you use special screws fit screwing in to the channel? And it holds just like a screw would in a joist? Just looks so thin and flimsy.... -_-
> 
> And then, mounting the projector. If my first layer is 3/4 inch OSB, then 5/8 PB, then add extra clips near the projector and just mount to the OSB. Ignore the joists?


Depends on a variety of factors. Most modern PJs are light enough to mount to double drywall, OSB, or a combination, etc. However, I would suggest you consult the PJ manufacturer's recommendations. I personally prefer mounting it directly to a joist or cross-member, but that requires careful pre-planning and a build strategy that allows for it (e.g. floating ceiling; aka Room-within-a-Room / double studs).




Ladeback said:


> The easiest answer is to work with a company like The Soundproofing Company and buy their products and they will help you out on what to do. You give them your room dimensions and they will help you with a plan as to where to put the clips. You would install all the clips first, then the hat channel. Make sure to overlap the channels and put some screws in it.
> 
> https://www.soundproofingcompany.com/
> 
> There are different types of clips, but they all screw into a joist and they should sell you the correct screws for the clips. The correct hat channel is plenty strong to hold up 3 layers of 5/8" drywall with 2 layers of green glue.


Agreed. Though since @Harkon is in the UK, he/she may not want to buy from SPC due to shipping costs. I have heard there are decent suppliers of Green Glue products in the UK, but I cannot vouch for any from experience.




> You could do your 1st layer with OSB, but I have heard it can be difficult to deal with at times. Again The Soundproofing company could help you out with this as well. You can send them an email and ask them questions.


I would recommend you avoid using OSB, plywood, or particle board for walls and ceiling unless you have a good reason to do so. Some people use a few sheets as the inner layer to provide additional support where they know it will be needed (e.g. projector, light fixtures). The use of PB is controversial. It's very heavy - which is of course nice except for the part where you have to lift it - but my hangup personally is I feel it tends to partially disintegrate when screws are run through it. That makes me nervous. I'd be particularly concerned with using it on a ceiling, where gravity is constantly trying to rip it off. If you are going to use it, I'd suggest to be very conscientious in your application.

I used to think it was a good idea to use OSB or plywood all over, however after further research and listening to the experience of others on this forum, I have come around to recommending all drywall as an alternative. Relatively equal mass and cost (to OSB where I live; cheaper than plywood), more consistent audio damping results, less messy/easier to work with (e.g. drywall is much easier to cut during installation), and almost as sturdy when it comes to securing most objects.

EDIT: _I used OSB as the first layer in my room's walls and ceiling. It was a massive P.I.T.A. to work with when it was necessary to trim boards. Drywall is so much easier. With the latter you can use a knife and you can leave a little overage while test fitting, trim a bit off with a sander or the knife, re-test, etc. With OSB, trimming very thin bits off when you've almost but not quite got the right dimensions is very challenging without overdoing it._

If you _do_ feel a need for a wood-based inner layer, I would favor plywood. It catches screws much better. Particle board is the worst (IMHO). OSB is in between. YMMV and others may disagree. I won't argue with them. It's a touchy subject based on one's personal experiences. This is just my opinion, FWIW.

In my room, above my PJ is 2" of plywood supporting it (Green Glued together). I could probably hang a 300 lb. PJ from it and it would be fine. I used that in two locations during the build (18" square plywood sections) because I had not made a final decision on PJ placement. The 18x18 inch PJ supports are attached to my ceiling joists, which I would ordinarily not recommend (I know, I'm a bit of a hypocrite in this regard), but my current room starting point was not ideal and it was not worthwhile financially to make it perfect. It's also top floor with attic above, so I was not terribly concerned about the space above in the center of the room where those PJ mounts are located. I also wanted the ability to hang ANY projector in the future without worrying about it. I traded overkill in one area (PJ weight support) for a sacrifice in another (coupling those PJ mounts to the original ceiling joists). All I can say now is it's worked out quite well. No complaints from me or the neighbors. LoL.


----------



## Harkon

Thanks for all the input. OSB was mainly to make building a soffit/pelmet alot easier as I wouldn't have to hit joists to secure it. 

To explain 'PB' is plasterboard not particle board (What you guys call Drywall on your side of the pond- I'm in the UK).

I thought I'd done well changing my metric measurements in to inches but I missed that one sorry. Sorry to cause confusion.

Will have a think about using two layers of 'drywall' rather than OSB. OSB seems to work out quite alot more expensive as well so needs tome thought.


----------



## pkinneb

Harkon said:


> Thanks for all the input. OSB was mainly to make building a soffit/pelmet alot easier as I wouldn't have to hit joists to secure it.
> 
> To explain 'PB' is plasterboard not particle board (What you guys call Drywall on your side of the pond- I'm in the UK).
> 
> I thought I'd done well changing my metric measurements in to inches but I missed that one sorry. Sorry to cause confusion.
> 
> Will have a think about using two layers of 'drywall' rather than OSB. OSB seems to work out quite alot more expensive as well so needs tome thought.


I actually did the first layer of my ceiling in OSB followed by GG and a layer of 5/8" fire rock for that reason. Made installing my soffits much easier as I could screw anywhere I wanted. I have read many posts about how hard OSB is to work with and I'll admit it takes more time than drywall but I didn't find it to be any big deal either.


----------



## HT Geek

macming said:


> For the single door, he agreed to attach MDF to both sides of a solid core door and add some more strips of MDF to make a shaker design. For what it's worth, that's good enough for now.


That works.


----------



## moray84

*soundproofing condo common wall*

Hey everyone, 

I've read most of this incredibly detailed thread to educate myself about a common bedroom wall in my condo. Removing the drywall presents a pretty big challenge due to HOA hurdles, so I really prefer a retrofit solution.

Currently I can barely hear noises coming through the bedroom wall. If the neighbors yell at their dog or the dog barks, I can probably hear that. I can hear doors slamming, but I cannot hear general conversations. Problem is, I am a light sleeper and once I'm on edge, it's hard to fall back asleep. 

Obviously this thread seems to always push one of two recommendations: 1) remove existing drywall and add clips (not possible for me) or 2) add additional drywall with green glue sandwiched in. 

I am thinking of having a contractor add 5/8 inch QuietRock or SilentFX with two tubes of GG per panel. That seems to be the standard recommendation of this thread, but then I'll see an occasional response saying that the only correct answer is to install clips. 

Can anyone who has experience in retrofitting chime in? I'm curious to hear the results from someone who's actually done this. Thanks!


----------



## jrref

moray84 said:


> Hey everyone,
> 
> I've read most of this incredibly detailed thread to educate myself about a common bedroom wall in my condo. Removing the drywall presents a pretty big challenge due to HOA hurdles, so I really prefer a retrofit solution.
> 
> Currently I can barely hear noises coming through the bedroom wall. If the neighbors yell at their dog or the dog barks, I can probably hear that. I can hear doors slamming, but I cannot hear general conversations. Problem is, I am a light sleeper and once I'm on edge, it's hard to fall back asleep.
> 
> Obviously this thread seems to always push one of two recommendations: 1) remove existing drywall and add clips (not possible for me) or 2) add additional drywall with green glue sandwiched in.
> 
> I am thinking of having a contractor add 5/8 inch QuietRock or SilentFX with two tubes of GG per panel. That seems to be the standard recommendation of this thread, but then I'll see an occasional response saying that the only correct answer is to install clips.
> 
> Can anyone who has experience in retrofitting chime in? I'm curious to hear the results from someone who's actually done this. Thanks!


I've had this same situation and the easiest and best solution is to add a layer of 5/8 inch Quiet Rock. You can use GG but if you are going to have someone do it for you, the cost might be a wash. Quiet Rock is expensive but the soundproofing is uniform and very easy for a contractor to install. GG you have to watch them, more labor, unless they have worked with it and have experience. In my case I was able to remove the existing sheetrock, take out all the insulation, replace it with Roxell sound insulation, seal all the outlets, etc, then put back 5/8 inch Quiet Rock. It worked great. I got about a 55db reduction in sound transmission. You won't hear voices or ordinary noise any more.


----------



## moray84

jrref said:


> I've had this same situation and the easiest and best solution is to add a layer of 5/8 inch Quiet Rock. You can use GG but if you are going to have someone do it for you, the cost might be a wash. Quiet Rock is expensive but the soundproofing is uniform and very easy for a contractor to install. GG you have to watch them, more labor, unless they have worked with it and have experience. In my case I was able to remove the existing sheetrock, take out all the insulation, replace it with Roxell sound insulation, seal all the outlets, etc, then put back 5/8 inch Quiet Rock. It worked great. I got about a 55db reduction in sound transmission. You won't hear voices or ordinary noise any more.


Awesome, so basically you are of the opinion that Quiet Rock is good at blocking sound. Did you install it on the studs or with clips? 

To be clear, my proposal is to use green glue between the existing drywall and the Quiet Rock. So I would have a double dry wall, plus green glue inside. From the videos I've watched, I sort of trust that my contractor can figure out how to apply the GG, but I guess you never know. 

If I were to take out the drywall I would incur a ton more expenses to get my HOA on board, plus they have all kinds of dumb rules about trash because I guess I can't just put the old drywall in the dumpster lmao.


----------



## niccolo

moray84 said:


> Awesome, so basically you are of the opinion that Quiet Rock is good at blocking sound. Did you install it on the studs or with clips?
> 
> To be clear, my proposal is to use green glue between the existing drywall and the Quiet Rock. So I would have a double dry wall, plus green glue inside. From the videos I've watched, I sort of trust that my contractor can figure out how to apply the GG, but I guess you never know.
> 
> If I were to take out the drywall I would incur a ton more expenses to get my HOA on board, plus they have all kinds of dumb rules about trash because I guess I can't just put the old drywall in the dumpster lmao.



If you're planning to add a layer of drywall, with Green Glue in between, I'm not sure substituting QuietRock makes much sense. QuietRock is an alternative to drywall with Green Glue sandwiched in between. Instead, I'd just get the heaviest drywall you can get. But be aware that you're not doing any isolation (e.g. clips and channel or dual wall), so especially lower frequencies will travel more readily through the framing.


----------



## moray84

niccolo said:


> If you're planning to add a layer of drywall, with Green Glue in between, I'm not sure substituting QuietRock makes much sense. QuietRock is an alternative to drywall with Green Glue sandwiched in between. Instead, I'd just get the heaviest drywall you can get. But be aware that you're not doing any isolation (e.g. clips and channel or dual wall), so especially lower frequencies will travel more readily through the framing.


I knew that QR has its own glue sandwiched in between but sort of assumed that QR would outperform regular dry wall even with the green glue applied in between. Am I totally wrong on that? 

Also aware that the clips are strongly recommended but I feel like my hands are tied due to the existing wall. Is there anything that could go over an existing wall without creating a triple leaf? Or just stick to the GG and/or QR combo?


----------



## niccolo

moray84 said:


> I knew that QR has its own glue sandwiched in between but sort of assumed that QR would outperform regular dry wall even with the green glue applied in between. Am I totally wrong on that?
> 
> Also aware that the clips are strongly recommended but I feel like my hands are tied due to the existing wall. Is there anything that could go over an existing wall without creating a triple leaf? Or just stick to the GG and/or QR combo?



I'm not aware of any studies of QR used in a sandwich configuration with either conventional drywall or another sheet of QR, and I'd be surprised if anyone's done the study. My hunch is that you're better off using the heaviest drywall you can, and maybe even two layers of it if that's feasible, on top of your existing drywall layer, rather than QR. But maybe Big or others have actual experience or can speculate in a more informed way?


Nope, there's no way for you to use clips of any kind to create isolation without removing existing drywall and without creating a triple leaf. I think you're better off adding as much mass as possible, i.e. one or two layers of drywall on top of the existing drywall. My hunch is that the benefit of GG is lower without isolation, but there should should still be some benefit.


----------



## moray84

niccolo said:


> moray84 said:
> 
> 
> 
> I knew that QR has its own glue sandwiched in between but sort of assumed that QR would outperform regular dry wall even with the green glue applied in between. Am I totally wrong on that?
> 
> Also aware that the clips are strongly recommended but I feel like my hands are tied due to the existing wall. Is there anything that could go over an existing wall without creating a triple leaf? Or just stick to the GG and/or QR combo?
> 
> 
> 
> 
> I'm not aware of any studies of QR used in a sandwich configuration with either conventional drywall or another sheet of QR, and I'd be surprised if anyone's done the study. My hunch is that you're better off using the heaviest drywall you can, and maybe even two layers of it if that's feasible, on top of your existing drywall layer, rather than QR. But maybe Big or others have actual experience or can speculate in a more informed way?
> 
> 
> Nope, there's no way for you to use clips of any kind to create isolation without removing existing drywall and without creating a triple leaf. I think you're better off adding as much mass as possible, i.e. one or two layers of drywall on top of the existing drywall. My hunch is that the benefit of GG is lower without isolation, but there should should still be some benefit.
Click to expand...

I guess I thought all the posts in this thread were referring to QR sandwiched on top with GG. It wasn’t clear that it was an either/or proposition, so that’s interesting! I learned something new. 

And thanks for confirming that clips can’t go on top of existing drywall. I sort of assumed that from the context but some previous posts were unclear for a newbie like me haha. 

So basically GG + 5/8 drywall is probably my best bet, huh?


----------



## niccolo

moray84 said:


> I guess I thought all the posts in this thread were referring to QR sandwiched on top with GG. It wasn’t clear that it was an either/or proposition, so that’s interesting! I learned something new.
> 
> And thanks for confirming that clips can’t go on top of existing drywall. I sort of assumed that from the context but some previous posts were unclear for a newbie like me haha.
> 
> So basically GG + 5/8 drywall is probably my best bet, huh?



I'm a consumer of content on here with only limited experience myself, but...


I've never heard of QR sandwiched with GG. But someone, somewhere has presumably tried it. I've read some of the studies that get shared here and haven't seen it referenced. In general, the consensus among knowledgeable folks on here thinks QR is harder to justify versus sandwiching heavy drywall with GG.


Clips on existing drywall is a big no-no, given triple leaf dynamics. As you might imagine, people come to the forum sporadically asking about exactly this.


Bear in mind that if you just treat one wall, there is likely to be some flanking noise, e.g. via the ceiling, floor, side walls, as vibration travels through the framing. The lower the frequency, the more it travels.


----------



## moray84

niccolo said:


> the consensus among knowledgeable folks on here thinks QR is harder to justify versus sandwiching heavy drywall with GG.


Gotcha... QR is harder to justify in what sense? Like, money, or results? Because between QR and GG, I can probably afford either, or both, for this project.


----------



## moray84

niccolo said:


> moray84 said:
> 
> 
> 
> I guess I thought all the posts in this thread were referring to QR sandwiched on top with GG. It wasnâ€™️t clear that it was an either/or proposition, so thatâ€™️s interesting! I learned something new.
> 
> And thanks for confirming that clips canâ€™️t go on top of existing drywall. I sort of assumed that from the context but some previous posts were unclear for a newbie like me haha.
> 
> So basically GG + 5/8 drywall is probably my best bet, huh?
> 
> 
> 
> 
> I'm a consumer of content on here with only limited experience myself, but...
> 
> 
> I've never heard of QR sandwiched with GG. But someone, somewhere has presumably tried it. I've read some of the studies that get shared here and haven't seen it referenced. In general, the consensus among knowledgeable folks on here thinks QR is harder to justify versus sandwiching heavy drywall with GG.
> 
> 
> Clips on existing drywall is a big no-no, given triple leaf dynamics. As you might imagine, people come to the forum sporadically asking about exactly this.
> 
> 
> Bear in mind that if you just treat one wall, there is likely to be some flanking noise, e.g. via the ceiling, floor, side walls, as vibration travels through the framing. The lower the frequency, the more it travels.
Click to expand...

By the way, here is some random link purporting to get good results with GG and QR combined. However he doesn’t test as compared to Gg and regular drywall so it could be the same result.


----------



## niccolo

moray84 said:


> Gotcha... QR is harder to justify in what sense? Like, money, or results? Because between QR and GG, I can probably afford either, or both, for this project.





moray84 said:


> By the way, here is some random link purporting to get good results with GG and QR combined. However he doesn’t test as compared to Gg and regular drywall so it could be the same result.



I think you're asking, if money is no object, is QR or heavy drywall the better choice?


If money really is no object, deal with demolishing the existing drywall and isolating the wall, either via clip and channel, or clips that isolate the wall up top plus some sort of rubber isolation at the bottom, or built a non-triple leaf dual wall. Assuming that's off the table...


How does the mass of QR compare to heavy drywall? I'm guessing the damping of QR happens at somewhat different frequencies than the damping of GG between layers of QR, so it's at least plausible that a QR and GG build will be more damped. Of course, damping is most effective when it's combined with isolation (not just additively, they reinforce each other).


I'm genuinely curious what some of the more knowledgeable folks on here would say. Maybe they'll weigh in?


----------



## jrref

moray84 said:


> Awesome, so basically you are of the opinion that Quiet Rock is good at blocking sound. Did you install it on the studs or with clips?
> 
> To be clear, my proposal is to use green glue between the existing drywall and the Quiet Rock. So I would have a double dry wall, plus green glue inside. From the videos I've watched, I sort of trust that my contractor can figure out how to apply the GG, but I guess you never know.
> 
> If I were to take out the drywall I would incur a ton more expenses to get my HOA on board, plus they have all kinds of dumb rules about trash because I guess I can't just put the old drywall in the dumpster lmao.


So you don't need to use GG AND Quiet Rock. They both are solutions that accomplish the same results. In my solution I didn't use clips but just installed it to the studs. I have and you probably have a decoupled common wall if the construction is relatively new. I'm not an expert but I do know you get the most sound reduction from the initial increase of mass to the wall. i.e., more sheetrock or Quiet Rock or GG. Everything else gives incremental increases on top of that initial improvement. In a condo, depending on the construction, you can use everything on your common wall and still get bass frequencies transmitted through the floor structure which is incredibly difficult or near impossible to mitigate. But if you want to control normal music, voices, TV, etc, Quiet Rock or GG will work well. The only reason why I like QR is because I had a contractor do the work and the labor to make the GG sheetrock sandwich made up for the extra cost of the QR. Also I know the layer in-between the QR is 100% consistent vs my contractor messing up when applying the GG. If you are going to DIY, then GG makes more sense and will be cheaper. No right or wrong, just depends on your individual situation. One thing I did do was applied the GG or you can use the QR equivalent sealant on the studs before mounting the Rock. Getting everything sealed, the outlets, etc., helps a lot as well.


----------



## moray84

jrref said:


> So you don't need to use GG AND Quiet Rock. They both are solutions that accomplish the same results. In my solution I didn't use clips but just installed it to the studs. I have and you probably have a decoupled common wall if the construction is relatively new. I'm not an expert but I do know you get the most sound reduction from the initial increase of mass to the wall. i.e., more sheetrock or Quiet Rock or GG. Everything else gives incremental increases on top of that initial improvement. In a condo, depending on the construction, you can use everything on your common wall and still get bass frequencies transmitted through the floor structure which is incredibly difficult or near impossible to mitigate. But if you want to control normal music, voices, TV, etc, Quiet Rock or GG will work well. The only reason why I like QR is because I had a contractor do the work and the labor to make the GG sheetrock sandwich made up for the extra cost of the QR. Also I know the layer in-between the QR is 100% consistent vs my contractor messing up when applying the GG. If you are going to DIY, then GG makes more sense and will be cheaper. No right or wrong, just depends on your individual situation. One thing I did do was applied the GG or you can use the QR equivalent sealant on the studs before mounting the Rock. Getting everything sealed, the outlets, etc., helps a lot as well.


Hmm, well it looks like QR may be heavier than drywall, so maybe QR makes a good second layer on that basis alone. Dumb question - in this context, is there a difference between dry wall and sheet rock?


----------



## bobbyg53

moray84 said:


> Hmm, well it looks like QR may be heavier than drywall, so maybe QR makes a good second layer on that basis alone. Dumb question - in this context, is there a difference between dry wall and sheet rock?



Two things we became aware of about drywall sheets that were not obvious to us -

1). Fire and building safety codes usually require *fire-rated drywall for use on common walls* separating dwelling units in condo/townhome buildings. This is to slow fire penetration through either side of the common wall with your neighbor.

2). Beware of modern “ultralight” vs. “classic” weight drywall panels. “Ultralight” panels have air added to the gypsum mix to make them lighter weight for shipping and handling; you can hear everything through them.

https://www.homedepot.com/s/drywall%20sheets?NCNI-5


----------



## moray84

bobbyg53 said:


> Two things we became aware of about drywall sheets that were not obvious to us -
> 
> 1). Fire and building safety codes usually require *fire-rated drywall for use on common walls* separating dwelling units in condo/townhome buildings. This is to slow fire penetration through either side of the common wall with your neighbor.
> 
> 2). Beware of modern “ultralight” vs. “classic” weight drywall panels. “Ultralight” panels have air added to the gypsum mix to make them lighter weight for shipping and handling; you can hear everything through them.
> 
> https://www.homedepot.com/s/drywall%20sheets?NCNI-5


I am aware of the requirement for fire-rating. But keep in mind, since I am not removing the old dry wall, aren't I already "fire safe?" In any event, do you think this would be a good choice for dry wall, from your link to HD:  USG Sheetrock Brand 5/8 in. x 4 ft. x 12 ft. Firecode X Panels


----------



## niccolo

moray84 said:


> I am aware of the requirement for fire-rating. But keep in mind, since I am not removing the old dry wall, aren't I already "fire safe?" In any event, do you think this would be a good choice for dry wall, from your link to HD: USG Sheetrock Brand 5/8 in. x 4 ft. x 12 ft. Firecode X Panels



5/8 Type X is the heavy stuff, that's good. It's my understanding the fire code-compliant stuff is denser/heavier, that's what makes it fire-code compliant (slows down how fast a fire can burn through it).


Sheetrock is just another term for drywall, actually a brand name like Xerox or Kleenex.


Argument for QR (no concern about consistent application of GG and less labor) is reasonable, too. Assuming QR is comparable in mass to regular drywall, then it just comes down to price (including factor in labor), plus the possibility that QR may indeed be marginally more effective. If you do go QR, then there's the question about whether to use GG with it, too. At this point, I think you've got your info to weigh various factors.


----------



## moray84

niccolo said:


> At this point, I think you've got your info to weigh various factors.


Yeah, I think I am about ready to get this project moving in the spring. Thanks for all your thoughts...last question, how challenging is a 5/8 QR to work with? I would be getting help from a contractor who is really handy but who doesn't have experience with QR.


----------



## niccolo

moray84 said:


> Yeah, I think I am about ready to get this project moving in the spring. Thanks for all your thoughts...last question, how challenging is a 5/8 QR to work with? I would be getting help from a contractor who is really handy but who doesn't have experience with QR.



Don't know, but logically, I don't see why QR would be any different to work with than equivalently heavy drywall. Maybe it's a tad more delicate?


----------



## jrref

niccolo said:


> moray84 said:
> 
> 
> 
> Yeah, I think I am about ready to get this project moving in the spring. Thanks for all your thoughts...last question, how challenging is a 5/8 QR to work with? I would be getting help from a contractor who is really handy but who doesn't have experience with QR.
> 
> 
> 
> It’s pretty heavy so you probably need two people to hang it. I’m your case just put it right on top of your existing Sheetrock, tape, sand, paint and you are done. If you want to use that acoustic caulking around all the seams before taping, even better.
Click to expand...


----------



## mkiv808

Hey all, need some advice. I was quoted $3900 for the following by a drywall installer recommended to me 

28x13.5x8 Room

1 door, 1 patio door, 1 small window 

All channel/clips are already up 

Labor:
Install 1 5/8” drywall layer on walls
Install 1 5/8” and 1 1/2” drywall layers on ceiling, with Green Glue in between 
Acoustic caulk at perimeter 
Mud/tape 

Material:
Drywall and mud/tape

I have already bought the Green Glue and acoustic caulk.

Fair price? I really don’t have much to compare against.


----------



## pkinneb

mkiv808 said:


> Hey all, need some advice. I was quoted $3900 for the following by a drywall installer recommended to me
> 
> 28x13.5x8 Room
> 
> 1 door, 1 patio door, 1 small window
> 
> All channel/clips are already up
> 
> Labor:
> Install 1 5/8” drywall layer on walls
> Install 1 5/8” and 1 1/2” drywall layers on ceiling, with Green Glue in between
> Acoustic caulk at perimeter
> Mud/tape
> 
> Material:
> Drywall and mud/tape
> 
> I have already bought the Green Glue and acoustic caulk.
> 
> Fair price? I really don’t have much to compare against.


So that includes the cost of the drywall, hanging the drywall, and taping the drywall, if yes, that does not seem out of line to me. 

One question though why 1/2" as the second layer on the ceiling and no second layer on the walls? Seems like a lot of work and expense to go 60% of the way.


----------



## mkiv808

pkinneb said:


> So that includes the cost of the drywall, hanging the drywall, and taping the drywall, if yes, that does not seem out of line to me.
> 
> 
> 
> One question though why 1/2" as the second layer on the ceiling and no second layer on the walls? Seems like a lot of work and expense to go 60% of the way.


Just saving some space on room dimensions. The room is a bit narrow/long and I didn’t want to lose more width. Plus none of the walls share a living area so not as important to dampen. Hopefully flanking will be limited by channels + gap and acoustic sealant at edges. 

I know, not a big difference in dimensions...


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## skunker

Hey guys, have a ton of questions about soundproofing, but I'll focus on one right now:

I am building a detached garage and going to make one of the car bays a dedicated media room. I was reading soundproofingcompany.com and saw that the best soundproofing solution for me may be a double wall solution as mentioned here: https://www.soundproofingcompany.co...ndproof-walls/spc-solution-3-double-stud-wall

My question is....how do I handle the double wall solution with a wall that is facing to the external world? If it was internal, I'd treat the wall with drywall, but not sure what to do externally. Would I do a plywood layer over building paper? Obviously I would not put drywall there. But, do I lose the benefit of that second wall and might as well just only do DD/GG in the interior side instead of the double wall approach?

Here's a sketch I did and there is a blue color on the sides I am talking about:

Here's what I think I need to do (see double wall sketch: took the original image from soundproofingcompany.com and added my illustration)


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## skunker

Got it figured out thanks to the awesome Ted/BigMouthinDC!


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## OrangePhile

Hi, I'm restarting my HT build, next step is to plan my soundproofing. See my build thread here.


I'm currently trying to get together a few options for the ceiling. My master bedroom is right above that, so it needs to be as good as I can get. I don't have thousands of $s to spend, but before I decide on my exact budget I want to weigh up my options. I can stretch out my project(as I have been) so I can spend a bit every few months, it doesn't all have to be one big splash of cash. My biggest issue is those 2x10 beams, they are pretty old. Many of them I had to double up and I did 2 additional lines of cross bracing to strengthen the whole structure and avoid flex and sag, there was a lot! Point is, I'm not sure how much extra weight I can or want to attach to them for the HT ceiling. With that in mind, what do you think about my options?


Most likely I'll need to do clip and hat channel isolation with 5/8 board and cavities filled with safe&sound? Two layers of GG will be best I know, but that will be extremely heavy, twice as heavy as just one layer.


Any other ideas thoughts?


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## mhutchins

Depending on the span, those joists should be fine. 

Here is a little math - With 16" on center (OC) joist spacing, double 5/8" Type X drywall is about 6# per linear foot of joist. Therefore, a 20' span would be holding 120#. Do a quick test and hang from the center of the span while someone measures the sag. Most floors are spec'ed to sag L/360, so for a 20' span, that is about 5/8". If you weigh 180#, that is a 50% load factor over the drywall weight. You have even more safety factor as your weight is concentrated midspan, which is a worse case scenario vs. the drywall weight which is evenly distributed along the full length of the span, increasing your safety margin even more.

Mike


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## OrangePhile

mhutchins said:


> Depending on the span, those joists should be fine.
> 
> 
> 
> Here is a little math - With 16" on center (OC) joist spacing, double 5/8" Type X drywall is about 6# per linear foot of joist. Therefore, a 20' span would be holding 120#. Do a quick test and hang from the center of the span while someone measures the sag. Most floors are spec'ed to sag L/360, so for a 20' span, that is about 5/8". If you weigh 180#, that is a 50% load factor over the drywall weight. You have even more safety factor as your weight is concentrated midspan, which is a worse case scenario vs. the drywall weight which is evenly distributed along the full length of the span, increasing your safety margin even more.
> 
> 
> 
> Mike




Interesting and very scientific, thank you. I just checked and my OC distance is 12”. I guess that makes it even stronger. Do you perhaps have a link to an online calculator where you get this? Or do you know it from memory being and old school Engineer! I spent 3minutes and found a span calculator on awc.org. 


Sent from my iPhone using Tapatalk


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## mhutchins

OrangePhile said:


> Interesting and very scientific, thank you. I just checked and my OC distance is 12”. I guess that makes it even stronger. Do you perhaps have a link to an online calculator where you get this? Or do you know it from memory being and old school Engineer! I spent 3minutes and found a span calculator on awc.org.
> 
> 
> Sent from my iPhone using Tapatalk


I have been doing a lot of these calculations lately for my own theater design, but for floor loading. I'm not an engineer, but you got the *old* part right... 

Mike


----------



## AnnapolisSony

As a little added insurance, I have decided to install pieces of 5/8" DW in between the studs on what will be part of the left wall in my HT room. 










Where I have indicated in red below, the pieces will be adhered to the back of the existing 1/2" DW that is actually the backside of the stairwell wall that leads upstairs.










I carefully measured and cut all of the pieces this past weekend - here they sit on the floor. 










Yes, I would have liked to have cut just one piece the full length in each stud bay but it just wasn't possible because there was too much variance in width in some of the bays as the studs were not always perfectly plumb (I am using existing framing in this part of the wall).

Eventually I will be putting Roxul safe-n-sound in the bays along this wall and then 5/8" DD/GG on clips and channel on the inside of the room. I just wanted a little extra "mass" within the wall since the stairwell will want to act as an echo chamber and carry sound upstairs. I also plan to have my DW contractor install two layers of DW on the bottom part of the wall - below the diagonal of the stairs (the area under the stairs will be used for storage but it is equally important to keep sound out of there as well - hence doubling up the DW under there too).

For obvious reasons, I am trying to avoid screwing each of these pieces in place so I am thinking about using a bunch of 1-in "L" brackets to sort of wedge the pieces in after I have generously covered the backs of them with GG and put them in place. I would screw the "L" brackets to the studs just beside the face of the DW and then the side of the other end of the bracket would be wedged up against the DW - hopefully - keeping each in place. If I put 3-4 brackets up for each DW piece, I would think they would hold for a few days before I can remove them. Am I correct in thinking that the GG should hold these in place after a good 4-5 days of set up?

Also, I was planning to caulk each piece in place with some acoustical sealant so I don't have any small gaps between the studs and the pieces of DW. Is that a good idea or overkill?

Any input or suggestions would be appreciated.


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## mkiv808

What do you all recommend for access panels?

Example: I have a shut off valve for water outside. I haven’t done any drywall yet. Is there a soundproof way to do an access panel/door? The panel would be on the wall behind my screen, so no worries on aesthetics.


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## OJ Bartley

mkiv808 said:


> What do you all recommend for access panels?
> 
> Example: I have a shut off valve for water outside. I haven’t done any drywall yet. Is there a soundproof way to do an access panel/door? The panel would be on the wall behind my screen, so no worries on aesthetics.


I have the same issue in my room, and have been looking at options. I think what I will probably do is go with a gasketed access door (either drywall or steel?) and layer the back with extra drywall and/or a full covering of Dynamat. Something like these:

https://accessdoorscanada.ca/8-x-8-gasketed-access-door/ 

https://accessdoorscanada.ca/8-x-8-flush-access-door-with-drywall-bead-flange-acudor/

I haven't looked at these in person yet, so I can't say how sturdy they are. Basically I'm going to try to maximize thickness and have some kind of perimeter seal, either built-in or something I add myself. I'd love to see some examples of what others have done.


----------



## mkiv808

OJ Bartley said:


> I have the same issue in my room, and have been looking at options. I think what I will probably do is go with a gasketed access door (either drywall or steel?) and layer the back with extra drywall and/or a full covering of Dynamat. Something like these:
> 
> https://accessdoorscanada.ca/8-x-8-gasketed-access-door/
> 
> https://accessdoorscanada.ca/8-x-8-flush-access-door-with-drywall-bead-flange-acudor/
> 
> I haven't looked at these in person yet, so I can't say how sturdy they are. Basically I'm going to try to maximize thickness and have some kind of perimeter seal, either built-in or something I add myself. I'd love to see some examples of what others have done.


I'm surprised there's not more conversation around this, or a standard way of doing it. It seems like it would be such a common issue in basements.

Wonder if mass loaded vinyl would be more effective than Dynamat?


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## OrangePhile

OrangePhile said:


> Hi, I'm restarting my HT build, next step is to plan my soundproofing. See my build thread here.


OK, so after a few more days of what feels like near constant reading an researching - I'm ready to pull the trigger and spend a few $. (by this I mean I've been sharing some ideas with my wife and she hasn't said no)

I'm now stuck deciding what materials and supplier to go with...hear me out. It feels like there's 10 out there, each promising their system or pricing to be the best.

Can I ask for this here? I want some guidance on which supplier and product to use?? My ceiling is 28 x 16 and then I have to do the walls(just shy of 8' high) and two doors. I want to follow best practice and do 2x 5/8 drywall boards with GG. This is going to cost me a ton after adding the Safe&sound and hat and channel.

For the Safe&Sound and 5/8 drywall I'll go to my local big box hardware store, that's easy, right?!?!. 

Where it gets complicated is 
- The 25 ga 7/8 furring channel, seems pretty standard, might just do big box store with coupons? 
- What about the green glue? Where for best price?
- Who has the best bang for buck clips? Can anybody guide me to some current decent options for my requirements. I'm seeing Whisper clips and eb1 clips and resilient clips, and then there's different suppliers.

I want to do this right, but I am cost sensitive and don't just want to buy from the first supplier who sends me a quote or who has an online purchase option.

*I'm really asking for help on my analysis paralysis wrt product/supplier.* I've spent days now and my spreadsheet is starting to take shape but if I can save some time and simply go with general consensus, I'd be happier. 

Any thoughts, pointers? even if you just PM them to me? I'm tired of googling searching and being indecisive on the best value for money option (TO THE ADMINS: I really hope I'm not overstepping the the line here, please let me know and I'll delete this post).


----------



## mhutchins

Hey Orange,

Many builders have had good results ordering drywall from commercial building supply companies rather than the big box stores, especially when you factor in delivery and carrying the drywall up or down stairs into the theater area. The 25ga hat channel is not so common, be careful, many suppliers stock 20ga and will "upgrade" you to the 20ga "for free as a favor". The all-metal IB-1 sound isolation clip will deliver much of the performance of the higher priced clips. Many people purchase their Green Glue from the SoundProofing company, not because of price, but because of their customer support. Beware of substitutes for Green Glue, few have actual test data to support their claims.

Here is a chart comparing the performance of sound isolation clips:


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## jcr159

OrangePhile said:


> OK, so after a few more days of what feels like near constant reading an researching - I'm ready to pull the trigger and spend a few $. (by this I mean I've been sharing some ideas with my wife and she hasn't said no)
> 
> I'm now stuck deciding what materials and supplier to go with...hear me out. It feels like there's 10 out there, each promising their system or pricing to be the best


Quick reminder to make it worse probably.. any DIYer can’t register for a ProXtra account (pro desk account) at Home Depot. Any order totaling more than $1500 can get sent to the bid room for additional discounting...

The more you order, the more the discount typically. They’ll also do job site delivery. I just ordered 3/4 XPS foamular 150, and 3/4 subfloor to overlay my concrete basement, a boatload of tapcons, 2” foamular for the walls, plus adhesive and tape. Order was about $2400. Most stuff was regular or bulk prices posted, but I literally paid half for the tapcons after it bid out. 

Good luck!


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## OJ Bartley

mkiv808 said:


> I'm surprised there's not more conversation around this, or a standard way of doing it. It seems like it would be such a common issue in basements.
> 
> Wonder if mass loaded vinyl would be more effective than Dynamat?


I was kind of surprised too. Maybe we'll be the pioneers in hose shutoff access doors here. Lol.

I'm not sure about the efficacy of MLV vs Dynamat, but I do have a few sheets of Dynamat left from some earlier efforts at treating a few vents and problem areas. I will probably try to find a door that allows for a drywall finish on the outside to disguise it as well as get some mass, layer the inside with Dynamat, and add a foam gasket to try for a good seal. I'm hoping to get to drywall this spring, so I will be sure to post my solution when it happens.


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## HT Geek

OrangePhile said:


> OK, so after a few more days of what feels like near constant reading an researching - I'm ready to pull the trigger and spend a few $. (by this I mean I've been sharing some ideas with my wife and she hasn't said no)
> 
> I'm now stuck deciding what materials and supplier to go with...hear me out. It feels like there's 10 out there, each promising their system or pricing to be the best.
> 
> Can I ask for this here? I want some guidance on which supplier and product to use?? My ceiling is 28 x 16 and then I have to do the walls(just shy of 8' high) and two doors. I want to follow best practice and do 2x 5/8 drywall boards with GG. This is going to cost me a ton after adding the Safe&sound and hat and channel.
> 
> For the Safe&Sound and 5/8 drywall I'll go to my local big box hardware store, that's easy, right?!?!.
> 
> Where it gets complicated is
> - The 25 ga 7/8 furring channel, seems pretty standard, might just do big box store with coupons?
> - What about the green glue? Where for best price?
> - Who has the best bang for buck clips? Can anybody guide me to some current decent options for my requirements. I'm seeing Whisper clips and eb1 clips and resilient clips, and then there's different suppliers.
> 
> I want to do this right, but I am cost sensitive and don't just want to buy from the first supplier who sends me a quote or who has an online purchase option.
> 
> *I'm really asking for help on my analysis paralysis wrt product/supplier.* I've spent days now and my spreadsheet is starting to take shape but if I can save some time and simply go with general consensus, I'd be happier.
> 
> Any thoughts, pointers? even if you just PM them to me? I'm tired of googling searching and being indecisive on the best value for money option (TO THE ADMINS: I really hope I'm not overstepping the the line here, please let me know and I'll delete this post).


Well, first off accept the fact there's no one-stop shopping for this stuff. Sounds like you already know that, but I'm just reiterating.

My general recommendation is to visit a contractor drywall shop. There are four reasons for this:


On large orders, you can negotiate prices
Most will deliver, including inside delivery/place stuff wherever you want
They can get most things you need
Most have free delivery if you order above a certain threshold (which should be much lower than what you're going to need)

For instance, there is a shop near me from which I can order drywall, acoustic sealant (not Green Glue), PAC/RSIC clips, and hat channel. They will deliver it inside a home, wherever I want. That is as close to one-stop shopping as I have found.

As Mike mentioned above, you could go through Home Depot and leverage their Pro programs. Be warned though, in the past HD would only deliver curbside. It's been at least 2 years since I even considered their delivery service, so I don't know how it is today. They normally contract it out, whereas Lowes has employees and company owned vehicles make the deliveries. I'm telling you though, if you find a small contractor shop locally who wants your business more, the experience for you will be much smoother and easier. 

Next, insulation. Call around to wholesalers until you find one you can talk into selling to you direct. Regardless of what they are supposed to do, I guarantee unless you live in a tiny town that you'll find at least one who will do business with you and set you up as a "contractor." This will get you access to the stuff you won't find at the big box stores, such as thicker varieties of Roxul for example.

Green Glue is kind of the wildcard of sorts. Do you value convenience of application (tubes), value (buy it in buckets and get an applicator/squirt gun), cost, or time? The cheapest option is normally to order from someone like the Sound Proofing Company (SPC). However, the downside is you'll usually wait longer (time), you must pay freight (not too bad though), and you'll need to get the squirt gun thingee (extra cost). The most convenient method is to order 12-packs of it from a retailer such as Amazon. You could also order the 12-pack tubes (29 oz. each) via SPC or another similar wholesale vendor.

IMHO, the GG situation usually boils down to 1) when you need it; and 2) whether you can realistically apply it all at once or not. If you're doing your walls and ceiling in stages, the tubes make more sense as you need to clean the applicator in between uses and it's just generally a P.I.T.A. for a typical homeowner unless you do it all at the same time. The tubes cost more by volume, but are much more convenient for most people doing this as DIY. If cost is a factor, the buckets are significantly cheaper, even after allowing for shipping costs. Like many other things, the more you buy at one time, the lower your average cost per bucket.

As far as the clips are concerned, you can find all kinds of opinions on this forum about which ones are "best." My personal opinion is the best ones for you are the ones that are

Readily available
Use rubber in their construction (or similar material)
$6 or less per clip
Design is conducive to your ability to apply them (e.g. shape, etc.)
The fact is folks are "splitting hairs" when it comes to judging which is best from an acoustic perspective. Clips are just one part of the equation. Your effort and focus on how important their performance is relative to all other clips should be commensurate with how much money and effort you are putting into everything else. If acoustic damping is a really big concern, I recommend going the route of using more clips and channels (as necessary to support the weight) and adding more drywall and Green Glue layers, rather than spending more $ on a marginally superior clip. That said, I suggest you avoid the clips that don't have any sort of rubber. The cheapo clips are not worthwhile IMHO (I'm talking about the $1.50 - $2 variety that are metal only).

p.s. Don't use Quiet Glue. Terrible product. Green Glue is popular for a (good) reason.


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## jcr159

Strong points by HT Geek for sure. HD will deliver into my garage where I am, but the reality is sheet goods like drywall and ply are a pain to move. I’ll hire out the Sheetrock work, so no biggie, but carrying lots of heavy things sucks... good to pay people for that... I paid a grand to a concrete pumping outfit to put a yard in my basement for a reason... carrying 85 bags of quickcrete and mixing 4 at a time wasn’t going to cut it, let alone the dust mess..


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## OrangePhile

Thanks @HT Geek and @jcr159. 

Lowe's typically delivers into my garage with a forklift(three times in the past for various projects). Right now there's a gift card deal at dollar store for 20% off lowe's gift cards. I saw it on slickdeals and will try it out this weekend. If I can do that and get another 10% coupon somewhere random that makes it a 30% discount. I wonder if any other wholesaler can match that, I'm trying though? Sent a few quote requests around. It seems like unless you know for a fact that they sell a particular product you have to phone and ask. Their websites are generally not very detailed when it comes to these larger contracting places. 


Sent from my iPhone using Tapatalk


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## jconjason

OrangePhile said:


> Thanks @HT Geek and @jcr159.
> 
> Lowe's typically delivers into my garage with a forklift(three times in the past for various projects). Right now there's a gift card deal at dollar store for 20% off lowe's gift cards. I saw it on slickdeals and will try it out this weekend. If I can do that and get another 10% coupon somewhere random that makes it a 30% discount. I wonder if any other wholesaler can match that, I'm trying though? Sent a few quote requests around. It seems like unless you know for a fact that they sell a particular product you have to phone and ask. Their websites are generally not very detailed when it comes to these larger contracting places.
> 
> 
> Sent from my iPhone using Tapatalk


Check out eBay for codes for Lowe's. Last I checked they were selling for a couple bucks for the codes. If youre a Slickdeals follower, I'm sure youre familiar with the now debunked Lowes generator. Some people sell those codes on eBay.

Good luck!


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## pjp

*Need advice for sound deadening with subwoofers between basement wood ceiling joists* 

In my basement I have an invisible 5.1 system with 3 small subwoofers hidden between the wood ceiling joists. There is *very* limited space between the joists, so I can only use very small subs. I have one "Artison Nano 1", one 8" "underseat" car sub, and one 10" underseat car sub. They sound very good and produce more than enough bass for the basement, but (as you can probably guess) -- having the subs surrounded by wood slats in the joists means there are frequencies where the surrounding wood vibrates and there is a lot of bleed-through to the floor above. 

Would applying the 2mm think sound deadening material shown below to all the surrounding wood work? (it's a bit like Dynamat). Is there something better I should consider? Whatever I use, it needs to be dark black or brown in color.

*Picture of 2mm thick Sound Deadening material*:











*Pictures of the subs between wood ceiling joists*:


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## flynfish

What do people think about these mats for use under wall bottom plates rather than the rubber horse stall mats normally recommended?

https://www.harborfreight.com/4-piece-anti-fatigue-foam-mat-set-94635.html


Sent from my iPhone using Tapatalk Pro


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## mhutchins

flynfish said:


> What do people think about these mats for use under wall bottom plates rather than the rubber horse stall mats normally recommended?
> 
> https://www.harborfreight.com/4-piece-anti-fatigue-foam-mat-set-94635.html
> 
> 
> Sent from my iPhone using Tapatalk Pro


To my knowledge, there is no performance testing of any of these products in that role. Therefore, there is no real way to make a determination of what product will work better vs. another product. My understanding of the theory (though likely flawed) is that the lower the resonance point of the spring-mass system, the lower frequency isolation that can be achieved. It follows then, that a lower durometer/softer product should have a lower resonance point than a higher durometer/harder product, *provided* the material is not compressed beyond its working range.

Kinetics claims a STC drop of up to 10 points through a wall assembly due to flanking paths via the floor/ceiling joints if the wall is not properly isolated. To do it properly, however, requires isolation at every anchor point as well as between the top and bottom plates as you are planning.

Mike


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## OrangePhile

jconjason said:


> Check out eBay for codes for Lowe's. Last I checked they were selling for a couple bucks for the codes. If youre a Slickdeals follower, I'm sure youre familiar with the now debunked Lowes generator. Some people sell those codes on eBay.
> 
> Good luck!




I bought 2x $500 Lowe’s GCs at dollar general with 15% coupons and a 10% discount coupon, saved quite a bit, thank goodness. 

Will be ordering my items from soundproofingcompany this week. 

Been contemplating what I need to do for Doors. Exterior door with weather strips etc plus interior solid core door?? No frame will fit properly given the clips, channel and double drywall. Is my only option to make a custom build with 2 or 3 layers of MDF? Need to do more research here on the forum and I’ve seen some serious custom build, not sure if I need that unless its out of necessity 


Sent from my iPhone using Tapatalk


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## jconjason

OrangePhile said:


> I bought 2x $500 Lowe’s GCs at dollar general with 15% coupons and a 10% discount coupon, saved quite a bit, thank goodness.
> 
> Will be ordering my items from soundproofingcompany this week.
> 
> Been contemplating what I need to do for Doors. Exterior door with weather strips etc plus interior solid core door?? No frame will fit properly given the clips, channel and double drywall. Is my only option to make a custom build with 2 or 3 layers of MDF? Need to do more research here on the forum and I’ve seen some serious custom build, not sure if I need that unless its out of necessity
> 
> 
> Sent from my iPhone using Tapatalk


I've been doing some research on doors lately as well. From some of it, I've read that exterior doors aren't necessarily better at sound proofing.

So far, I've found that Jeld-Wen Tria C series solid core doors are fairly decent with an STC of 37. Not the best but for the price pretty good.

Hopefully someone with much more knowledge can chime in on doors!


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## mhutchins

OrangePhile said:


> .
> .
> .
> Been contemplating what I need to do for Doors. Exterior door with weather strips etc plus interior solid core door?? No frame will fit properly given the clips, channel and double drywall. Is my only option to make a custom build with 2 or 3 layers of MDF? Need to do more research here on the forum and I’ve seen some serious custom build, not sure if I need that unless its out of necessity
> 
> Sent from my iPhone using Tapatalk


I've been discussing doors lately with Nyal Mellor and he has suggested buying the heaviest 1-3/4" solid core door slab I can find (typically mineral core doors have higher STC than wood cores), then adding a layer of 1/2-5/8" drywall topped with a 1/2-5/8" layer of MDF (with Green Glue between each layer, of course). Then add a good seal set such as the Pemko STCSET-2E. For my application, Nyal has recommended cam-lift hinges combined with the threshold seal rather than an automatic door bottom. We have not discussed latch sets or door closers as I recall, so I can't comment on those aspects of door construction.

Somewhere I came across the comment that the door frames should be constructed from the inside out for best acoustic performance, thus avoiding the use of shims and the necessary air gap these create. I took this to mean that you don't build a rough-in opening when you do your framing but instead build the structure as you install the door. Also, because our walls are thicker than standard walls, the first structural member attached to the door frame is an oversized 2x that is ripped to the finished width of the wall. For example a 2x4 wall with 2 layers of 5/8" drywall on each side with one side utilizing clips and channel would have a finished width of ( 5/8" + 5/8" + 3-1/2" + 1-5/8" + 5/8" + 5/8") 7-5/8". The first layer of the frame would be 3/4" pine or MDF backed by a 2x10 that is ripped to a width of 7-5/8" (some people like to use finger-jointed studs or engineered lumber such as LSL or LVL because it is straighter than typical 2x lumber). Then you would have additional jack studs and king studs for the strength desired. The drywall would then abut the face of the 2x10, rather than overlapping the stud and abutting against the back side of the pine or MDF frame.

Here is a link to BIGmouthinDC's drawing of what I described above and attached is a typical home door frame assembly.


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## OrangePhile

mhutchins said:


> I've been discussing doors lately with Nyal Mellor and he has suggested buying the heaviest 1-3/4" solid core door slab I can find (typically mineral core doors have higher STC than wood cores), then adding a layer of 1/2-5/8" drywall topped with a 1/2-5/8" layer of MDF (with Green Glue between each layer, of course). Then add a good seal set such as the Pemko STCSET-2E. For my application, Nyal has recommended cam-lift hinges combined with the threshold seal rather than an automatic door bottom. We have not discussed latch sets or door closers as I recall, so I can't comment on those aspects of door construction.
> 
> 
> 
> Somewhere I came across the comment that the door frames should be constructed from the inside out for best acoustic performance, thus avoiding the use of shims and the necessary air gap these create. I took this to mean that you don't build a rough-in opening when you do your framing but instead build the structure as you install the door. Also, because our walls are thicker than standard walls, the first structural member attached to the door frame is an oversized 2x that is ripped to the finished width of the wall. For example a 2x4 wall with 2 layers of 5/8" drywall on each side with one side utilizing clips and channel would have a finished width of ( 5/8" + 5/8" + 3-1/2" + 1-5/8" + 5/8" + 5/8") 7-5/8". The first layer of the frame would be 3/4" pine or MDF backed by a 2x10 that is ripped to a width of 7-5/8" (some people like to use finger-jointed studs or engineered lumber such as LSL or LVL because it is straighter than typical 2x lumber). Then you would have additional jack studs and king studs for the strength desired. The drywall would then abut the face of the 2x10, rather than overlapping the stud and abutting against the back side of the pine or MDF frame.
> 
> 
> 
> Here is a link to BIGmouthinDC's drawing of what I described above and attached is a typical home door frame assembly.




Thanks @mhutchins, even the perceivable simple things become complicated when trying to do it right. This is the answer I was looking for though, thanks. As with everything it’s a trade off between cost-time-effort-results. 


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## mhutchins

Here is a picture I found from I think TMcG's buid thread. Note how the innermost jack studs extend beyond the rest of the framing.

Mike


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## searvy

I am in the flight path of an Air Force base. Even though they are so high in the air that you can barely see them they are extremely loud. I know I can't eliminate the sound, but I want to reduce it to a tolerable level for me. I also have a home theater and I want to keep the sound from disturbing my neighbors. I'm researching soundproofing my house and I need some advice.

I am able to hear my windows transmit the most noise so I am going to replace them first. I am in the process of getting quotes to install Milgard Quiet line windows. After the windows are replaced I'm sure the drywall will be the next weak link. I am predicting I will need to add another layer of drywall later (after I save enough money).

Now for my first question, are there any considerations I should consider when installing the windows to make a second layer of drywall installation easier at a later date? Or is there anything else I should consider? Now my last question, I remember seeing instructions somewhere on how to install and soundproof a window, can anyone provide me the link? I want to know how the installer needs to install the windows.

I apologize if this has been asked before.

Thank you in advance!


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## stealthtt24

Hi guys! Looking for a little bit of direction. Long story short, need some help reducing sound in the basement from 1st floor. Upstairs we put some area rugs and added more furniture which definitely helped but looking to spend some money and reduce impact noise (even airborne noise is bad honestly.)


Current setup on basement ceiling is some insulation bags (not completely covering the ceiling area) and a suspension ceiling with regular lightweight tiles, pictures attached. Just fyi I bought the place like this. I've done quite a bit of research and torn between what type of drywall to put up. Two 5/8 with GG in between with resilient channels or CertainTeed silentFX 5/8 and resilient channels? Either way I figured I'd add more insulation. Approximately 500 sq feet needs to be done.



Talked to two general contractors so far. One recommended just adding rockwall insulation and sheetrock vinyl ceiling tiles to retain the original drop ceiling. The other said to add Thermafiber insulation and see how it is and go from there. I don't mind spending some money on drywall install and lose an inch or so in the ceiling height. I just need to reduce the noise coming from the first floor. Let me know if you'd like more pictures. Thanks so much!


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## stealthtt24

Cant add photos to the original post.


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## stealthtt24

There's about 2 to 3 inches from the beam to the drop ceiling.


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## mhutchins

I would do 2 layers of Type-X 5/8" drywall with Green Glue between the joists, up against the bottom of the flooring. Then fill the joist cavities nearly full with inexpensive insulation batts. Install clips and channel to the bottom of the joists and install two layers of Type-X 5/8" drywall with Green Glue to the hat channel. Stagger all the seams and caulk all the corner intersections between the ceiling and the walls.

Other than adding more layers of drywall, that is about the best you can do.

Mike


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## stealthtt24

mhutchins said:


> I would do 2 layers of Type-X 5/8" drywall with Green Glue between the joists, up against the bottom of the flooring. Then fill the joist cavities nearly full with inexpensive insulation batts. Install clips and channel to the bottom of the joists and install two layers of Type-X 5/8" drywall with Green Glue to the hat channel. Stagger all the seams and caulk all the corner intersections between the ceiling and the walls.
> 
> Other than adding more layers of drywall, that is about the best you can do.
> 
> Mike



Thanks for that info Mike. Seems like every time I have a contractor out they shy away from drywall and just advise on more/better batts. I've got one more coming out today or tomorrow. I'm at a point where I might just come up with a game plan (something like what you advised) and tell my trusted handyman/contractor (I can tell isn't an expert on soundproofing) to execute it. I assume it won't be cheap.


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## mhutchins

Even internet experts don't really understand the intricacies of proper sound isolation. The drywall between the joists is the real PITA. Its main purpose is to cut down the impact noise from the floor above. The floating ceiling does most of the heavy lifting with regards to decreasing the transmission of airborne sound. These blogs are filled with stories of contractors screwing up the details, so plan on being present as much as possible to make sure the job is done right.


Mike


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## stealthtt24

Thanks, yeah I could see it being a lot of time just to install drywall against the bottom of the floor. Def sounds effective though. It would be okay to put the screws into the bottom of the floorboard then? I will def be here for the contractor, probably help them. Still waiting on the one contractor to set up a time. Probably have a conversation with my main guy tomorrow. He seemed reluctant at first though.


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## mhutchins

stealthtt24 said:


> ..... It would be okay to put the screws into the bottom of the floorboard then?......


It's not optimum, but it's what most people do. The alternative is to tack two strips, one supporting each edge of the drywall, to the side of the joists so that it forms a ledge beneath the drywall that holds it firmly against the underside of the floor. Theoretically, this method would be less likely to "short circuit" the drywall and create a flanking path. Don't forget the Green Glue between each layer of drywall.

Mike


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## stealthtt24

Got it thanks. Have one last contractor coming tomorrow. Side note. I went to an open house this weekend and was in the basement. I noticed a hole in the ceiling and I was curious of there method. I found this. Anyone done this before? Looks like a bracket attached to another bracket attached to the joist. Wonder if this helps?


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## stealthtt24

Pics


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## mkiv808

I got these lights

https://www.amazon.com/Nadair-Reces..._rd_w=N2Vt4&pd_rd_wg=Gaeat&ref_=pd_gw_cr_simh

So, now I'm trying to figure out how the heck to secure them when I have 2 thick layers of drywall to mount them in. 

Ideas?


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## mkiv808

mhutchins said:


> Even internet experts don't really understand the intricacies of proper sound isolation. The drywall between the joists is the real PITA. Its main purpose is to cut down the impact noise from the floor above. The floating ceiling does most of the heavy lifting with regards to decreasing the transmission of airborne sound. These blogs are filled with stories of contractors screwing up the details, so plan on being present as much as possible to make sure the job is done right.
> 
> 
> Mike


Would echo this. I just had contractors doing drywall. A very competent team but first time with a project like this (double drywall, Green Glue, clips/channel). 

I made a thorough list of specs and printed it for them, down to the gaps on the floor and edges, the length and type of drywall screws, everything. I drew speaker cutouts on vapor barrier around the room. And I prepped everything to a T. 

Went great. But I have no doubts that without doing the above, something would've gotten overlooked.


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## stealthtt24

Would laying carpet and a thick underlayment in the floor above make a difference? Pricing everything out this might be the most practical option. Especially since I may need access to the pipes and wiring in basement ceiling in the future and drywall would make that a tougher option.


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## mhutchins

stealthtt24 said:


> Would laying carpet and a thick underlayment in the floor above make a difference? Pricing everything out this might be the most practical option. Especially since I may need access to the pipes and wiring in basement ceiling in the future and drywall would make that a tougher option.


Carpet and pad absolutely makes a difference. Will it offset the open ceiling in the basement, no, but it is better than nothing.

Mike


----------



## mkiv808

Now that I have drywall up, I'm thinking about weak points. 

1. There's one door that connects the room with the rest of the house. I did not install the door, but I'm pretty sure it's solid core as it has some heft. All the doors in my house have weight to them. The house was built by a builder, for himself. My old house interior doors, which was new construction in 2010, had much lighter doors. So I think I'm good. However, I do want to seal it off. I don't like the ugly automatic bottoms. What else is recommended to seal the threshold area that isn't so ugly/obtrusive? I plan on sealing the jamb with something like this: https://acousticalsolutions.com/product/door-jamb-bubble-seal/

2. The drywall guys did an excellent job, but in the ceiling they punched a hole for the smoke detector that was too big. It's like 1" or slightly bigger when it only needed to fit some tiny wires. Any suggestions on blocking that up? It's dual drywall.


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## stealthtt24

Thanks Mike. I'm doing that this week hopefully as it wont cost too much. I'll report my findings back.


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## OrangePhile

All, maybe not the correct thread and I'll likely start my own thread for more detail, bit for now just in principle : when you soundproof and install theaters(like we do here in the soundproofing thread) do you get permits for your work? 

I'm asking as I'm doing it all myself but my permit was rejected until I update my plans with a a.lot more detail. I don't mind that, I want to be in compliance etc. But I rarely see guys here talking about permits. 


Sent from my iPhone using Tapatalk


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## pkinneb

OrangePhile said:


> All, maybe not the correct thread and I'll likely start my own thread for more detail, bit for now just in principle : when you soundproof and install theaters(like we do here in the soundproofing thread) do you get permits for your work?
> 
> I'm asking as I'm doing it all myself but my permit was rejected until I update my plans with a a.lot more detail. I don't mind that, I want to be in compliance etc. But I rarely see guys here talking about permits.
> 
> 
> Sent from my iPhone using Tapatalk


Yes I pulled permits for both electrical and building. The building permit was more for the rest of the basement than the theater but they did sign off on the framing, fire blocking, and the insulation. Once done they will do a final on the building permit my electrical permit is closed out already.


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## OrangePhile

pkinneb said:


> Yes I pulled permits for both electrical and building. The building permit was more for the rest of the basement than the theater but they did sign off on the framing, fire blocking, and the insulation. Once done they will do a final on the building permit my electrical permit is closed out already.




Did you draw up the plans yourself? I did and got quite a few comments back for corrections. I will be asking for some advice here on the forum(different thread) later this week. 

Sorry, I actually think my questioning here shouldn't be on the soundproofing thread. Yet I continue typing....


Sent from my iPhone using Tapatalk


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## pkinneb

OrangePhile said:


> Did you draw up the plans yourself? I did and got quite a few comments back for corrections. I will be asking for some advice here on the forum(different thread) later this week.
> 
> Sorry, I actually think my questioning here shouldn't be on the soundproofing thread. Yet I continue typing....
> 
> 
> Sent from my iPhone using Tapatalk


I did but should share I live in rural MN so the requirements were pretty simple a stick drawing was all I needed. They were more concerned about having my septic system recertified then they were the plans.


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## BigRedd

Hey guys - I’m using my unexpected coronavirus downtime to jumpstart by long dormant basement (non-dedicated) home theater remodel.

The basement had already been finished when we bought the house but I ripped out the 6'10" drop ceiling in one end of the larger room to gain more ceiling height for a projection screen. Then the Pats made the Super Bowl...*in 2015*...and I "temporarily" put up a piece of Wilsonart laminate and lit up the projector for a Super Bowl party. Fast forward five years to today.

The walls are studded and drywalled up to the 6'10" height of the (former) drop ceiling. There is no drywall above that height. The bottoms of the 11 7/8" I-joists are 7'8" off the floor. Joists are insulated with R-19 fiberglass. The wall where the screen will go (which is at one end of a very long (>40') room) is studded nearly to the ceiling (there are 2x4 blocks I can remove and replace with IB-3 isolation clips). On the left side wall the studs stop at the 6'10" drywall height. That stud wall is in front of (inside of) a roughly hip high concrete exterior basement wall with standard framing on top of it. Hopefully the attached picture gives you an idea (the wall where the screen will go is on the right in the picture, the left side wall is on the left). I will be building a new partition wall that will form the right side of the theater. The back will be open to the larger room. Theater area after I put up the partition wall will be roughly 17'3" deep by 17'6" wide but the room extends 25+ feet behind the theater..

The kitchen is above the area where the theater goes so transmission through the ceiling in both directions is the priority. This will likely seem sacrilege to many here but I would probably be OK maintaining the current level of transmission in both directions...based on my experience with two 12" subs and 8" Klipsch Reference bookshelves and just the joists filled with R-19(!)...but I'd certainly like to improve it while applying the 80/20 rule. I fear I will make it worse if I just conventionally finish studs up to the joists and drywall everything direct to the studs/joists. I believe others have made the analogy that it's like skinning a drum.

My priorities are:
1) Minimizing loss of ceiling height. I want the largest screen possible (I"m thinking 130-135" - the Wilsonart is 125") at an appropriate viewing height. For this reason, I am very reluctant to do clips, channel, and two layers of 5/8 drywall and lose nearly three inches of ceiling height.
2) Value, which I define as an appropriate improvement in transmission loss for my investment of time/money. I admire those of you with the determination and perseverance to spend thousands of dollars and days of your time chasing another dB or two. I have much lower standards. 

Based on these priorities and my refreshed research today, my plan is as follows. Please tear it apart/comment/suggest as you see fit. Your feedback would be much appreciated.

1) I'm not planning to tear out anything existing.
a) On the left side wall, I plan to insert a mini-stud wall on top of the existing studs (that top out at 6'10"), stopping short of the ceiling and using IB-3 clips to decouple that wall from the ceiling. I will cover that mini-wall with drywall to match existing wall and then put a second layer of drywall over the entire wall (easier than dealing with full length seam). Not planning on GG.​b) On the front wall I will remove the 2x4 blocks that connect the wall to the ceiling and replace with IB-3 clips. I _*could*_ put a second layer of drywall on this front wall if it's worth it but it doesn't *need* it like the left wall will. If I do, no GG.​c) Right side wall would be built short of ceiling, connected/de-coupled with IB-3 clips, and either single or double rocked depending on if you guys tell me second layer is worth it. No GG.​
2) The ceiling is my big conundrum. I *really* do not want to lose the ceiling height that I would with clips plus channel plus two layers of 5/8 drywall. I'm trying to decide between three options but I'm all ears on others:
a) The cheap, low-profile, metal-only clips plus hat channel plus a single layer of 5/8 drywall. Does anybody know the thickness of the metal only clips (like IB-1) plus hat channel?​b) ISOMax clips plus hat channel, which is 1 3/8, plus a single layer of 5/8 drywall. ISOMax appear to be the lowest profile clips that incorporate rubber other than the clips that attach to the sides of the joists, which seem like they would be a complete nightmare to install.​c) No clips or channel but two layers of 5/8 drywall with GG in between (ceiling only).​
Any feedback would be appreciated. I hope you are all staying healthy and sane in these trying times. Thanks!


----------



## jcr159

BigRedd said:


> Hey guys - I’m using my unexpected coronavirus downtime to jumpstart by long dormant basement (non-dedicated) home theater remodel.
> 
> The basement had already been finished when we bought the house but I ripped out the 6'10" drop ceiling in one end of the larger room to gain more ceiling height for a projection screen. Then the Pats made the Super Bowl...*in 2015*...and I "temporarily" put up a piece of Wilsonart laminate and lit up the projector for a Super Bowl party. Fast forward five years to today.
> 
> The walls are studded and drywalled up to the 6'10" height of the (former) drop ceiling. There is no drywall above that height. The bottoms of the 11 7/8" I-joists are 7'8" off the floor. Joists are insulated with R-19 fiberglass. The wall where the screen will go (which is at one end of a very long (>40') room) is studded nearly to the ceiling (there are 2x4 blocks I can remove and replace with IB-3 isolation clips). On the left side wall the studs stop at the 6'10" drywall height. That stud wall is in front of (inside of) a roughly hip high concrete exterior basement wall with standard framing on top of it. Hopefully the attached picture gives you an idea (the wall where the screen will go is on the right in the picture, the left side wall is on the left). I will be building a new partition wall that will form the right side of the theater. The back will be open to the larger room. Theater area after I put up the partition wall will be roughly 17'3" deep by 17'6" wide but the room extends 25+ feet behind the theater..
> 
> The kitchen is above the area where the theater goes so transmission through the ceiling in both directions is the priority. This will likely seem sacrilege to many here but I would probably be OK maintaining the current level of transmission in both directions...based on my experience with two 12" subs and 8" Klipsch Reference bookshelves and just the joists filled with R-19(!)...but I'd certainly like to improve it while applying the 80/20 rule. I fear I will make it worse if I just conventionally finish studs up to the joists and drywall everything direct to the studs/joists. I believe others have made the analogy that it's like skinning a drum.
> 
> My priorities are:
> 1) Minimizing loss of ceiling height. I want the largest screen possible (I"m thinking 130-135" - the Wilsonart is 125") at an appropriate viewing height. For this reason, I am very reluctant to do clips, channel, and two layers of 5/8 drywall and lose nearly three inches of ceiling height.
> 2) Value, which I define as an appropriate improvement in transmission loss for my investment of time/money. I admire those of you with the determination and perseverance to spend thousands of dollars and days of your time chasing another dB or two. I have much lower standards.
> 
> Based on these priorities and my refreshed research today, my plan is as follows. Please tear it apart/comment/suggest as you see fit. Your feedback would be much appreciated.
> 
> 1) I'm not planning to tear out anything existing.
> a) On the left side wall, I plan to insert a mini-stud wall on top of the existing studs (that top out at 6'10"), stopping short of the ceiling and using IB-3 clips to decouple that wall from the ceiling. I will cover that mini-wall with drywall to match existing wall and then put a second layer of drywall over the entire wall (easier than dealing with full length seam). Not planning on GG.​b) On the front wall I will remove the 2x4 blocks that connect the wall to the ceiling and replace with IB-3 clips. I _*could*_ put a second layer of drywall on this front wall if it's worth it but it doesn't *need* it like the left wall will. If I do, no GG.​c) Right side wall would be built short of ceiling, connected/de-coupled with IB-3 clips, and either single or double rocked depending on if you guys tell me second layer is worth it. No GG.​
> 2) The ceiling is my big conundrum. I *really* do not want to lose the ceiling height that I would with clips plus channel plus two layers of 5/8 drywall. I'm trying to decide between three options but I'm all ears on others:
> a) The cheap, low-profile, metal-only clips plus hat channel plus a single layer of 5/8 drywall. Does anybody know the thickness of the metal only clips (like IB-1) plus hat channel?​b) ISOMax clips plus hat channel, which is 1 3/8, plus a single layer of 5/8 drywall. ISOMax appear to be the lowest profile clips that incorporate rubber other than the clips that attach to the sides of the joists, which seem like they would be a complete nightmare to install.​c) No clips or channel but two layers of 5/8 drywall with GG in between (ceiling only).​
> Any feedback would be appreciated. I hope you are all staying healthy and sane in these trying times. Thanks!


I'm in a similar situation... I think where I landed is... r19 between joists. boxes for all my can lights and speakers from here for $60/each
https://isostore.com/quietbox-recessed-light-soundproofing.html
Mass Loaded vinyl against the joists to seal everything up. then blocking between joists with Resilient Channel or clips and Hat with a single layer of type x fire rated 5/8. this will let me keep the drywall decoupled from the joists, and my damping layer is physically separated from the drywall since attached to the joists... it lets me seal up that layer better and work it around the boxes for the lights easier as well. 

Does this work as well as the typical recommended DD+GG? Probably not. Is it as good as I can do without killing myself or the bank, in my specific situation? yeah... and hopefully it mitigates enough. I'm not looking for silent... too many other weak links and not a dedicated room in my basement... Hopefully it is good enough!


----------



## Ladeback

BigRedd said:


> Hey guys - I’m using my unexpected coronavirus downtime to jumpstart by long dormant basement (non-dedicated) home theater remodel.
> 
> The basement had already been finished when we bought the house but I ripped out the 6'10" drop ceiling in one end of the larger room to gain more ceiling height for a projection screen. Then the Pats made the Super Bowl...*in 2015*...and I "temporarily" put up a piece of Wilsonart laminate and lit up the projector for a Super Bowl party. Fast forward five years to today.
> 
> The walls are studded and drywalled up to the 6'10" height of the (former) drop ceiling. There is no drywall above that height. The bottoms of the 11 7/8" I-joists are 7'8" off the floor. Joists are insulated with R-19 fiberglass. The wall where the screen will go (which is at one end of a very long (>40') room) is studded nearly to the ceiling (there are 2x4 blocks I can remove and replace with IB-3 isolation clips). On the left side wall the studs stop at the 6'10" drywall height. That stud wall is in front of (inside of) a roughly hip high concrete exterior basement wall with standard framing on top of it. Hopefully the attached picture gives you an idea (the wall where the screen will go is on the right in the picture, the left side wall is on the left). I will be building a new partition wall that will form the right side of the theater. The back will be open to the larger room. Theater area after I put up the partition wall will be roughly 17'3" deep by 17'6" wide but the room extends 25+ feet behind the theater..
> 
> The kitchen is above the area where the theater goes so transmission through the ceiling in both directions is the priority. This will likely seem sacrilege to many here but I would probably be OK maintaining the current level of transmission in both directions...based on my experience with two 12" subs and 8" Klipsch Reference bookshelves and just the joists filled with R-19(!)...but I'd certainly like to improve it while applying the 80/20 rule. I fear I will make it worse if I just conventionally finish studs up to the joists and drywall everything direct to the studs/joists. I believe others have made the analogy that it's like skinning a drum.
> 
> My priorities are:
> 1) Minimizing loss of ceiling height. I want the largest screen possible (I"m thinking 130-135" - the Wilsonart is 125") at an appropriate viewing height. For this reason, I am very reluctant to do clips, channel, and two layers of 5/8 drywall and lose nearly three inches of ceiling height.
> 2) Value, which I define as an appropriate improvement in transmission loss for my investment of time/money. I admire those of you with the determination and perseverance to spend thousands of dollars and days of your time chasing another dB or two. I have much lower standards.
> 
> Based on these priorities and my refreshed research today, my plan is as follows. Please tear it apart/comment/suggest as you see fit. Your feedback would be much appreciated.
> 
> 1) I'm not planning to tear out anything existing.
> a) On the left side wall, I plan to insert a mini-stud wall on top of the existing studs (that top out at 6'10"), stopping short of the ceiling and using IB-3 clips to decouple that wall from the ceiling. I will cover that mini-wall with drywall to match existing wall and then put a second layer of drywall over the entire wall (easier than dealing with full length seam). Not planning on GG.​b) On the front wall I will remove the 2x4 blocks that connect the wall to the ceiling and replace with IB-3 clips. I _*could*_ put a second layer of drywall on this front wall if it's worth it but it doesn't *need* it like the left wall will. If I do, no GG.​c) Right side wall would be built short of ceiling, connected/de-coupled with IB-3 clips, and either single or double rocked depending on if you guys tell me second layer is worth it. No GG.​
> 2) The ceiling is my big conundrum. I *really* do not want to lose the ceiling height that I would with clips plus channel plus two layers of 5/8 drywall. I'm trying to decide between three options but I'm all ears on others:
> a) The cheap, low-profile, metal-only clips plus hat channel plus a single layer of 5/8 drywall. Does anybody know the thickness of the metal only clips (like IB-1) plus hat channel?​b) ISOMax clips plus hat channel, which is 1 3/8, plus a single layer of 5/8 drywall. ISOMax appear to be the lowest profile clips that incorporate rubber other than the clips that attach to the sides of the joists, which seem like they would be a complete nightmare to install.​c) No clips or channel but two layers of 5/8 drywall with GG in between (ceiling only).​
> Any feedback would be appreciated. I hope you are all staying healthy and sane in these trying times. Thanks!


You can put in blocking between the joist so that the ceiling clip and hat channel only have about a 1/2" gap from the ceiling, but it looks like you have a gas line running through the room. If you can't reroute it, what I suggest can't be used. If you did put in the blocking between the joust you could use the IB-2 EXT Sound Isolation Clip and only lose about 1.75" so you ceiling height would be 90.25" or 7'-6 1/4". See IB-2 attached.

I am also adding Soundproofing Company's web page. 

https://www.soundproofingcompany.com/

Now a way to add mass to help with sounds from above is to put in two layers of 5/8" drywall with Green Glue between the joist. This will help with foot fall sounds. You could then add pink fluffy and a try a single layer of 5/8" drywall to see if it is good enough. I see right now you have Klipsch bookshelf's and 12" subs, at some point you may want to upgrade those for bigger speakers and if you do the soundproofing right first it may be better in the long run.


----------



## Ladeback

jcr159 said:


> I'm in a similar situation... I think where I landed is... r19 between joists. boxes for all my can lights and speakers from here for $60/each
> https://isostore.com/quietbox-recessed-light-soundproofing.html
> Mass Loaded vinyl against the joists to seal everything up. then blocking between joists with Resilient Channel or clips and Hat with a single layer of type x fire rated 5/8. this will let me keep the drywall decoupled from the joists, and my damping layer is physically separated from the drywall since attached to the joists... it lets me seal up that layer better and work it around the boxes for the lights easier as well.
> 
> Does this work as well as the typical recommended DD+GG? Probably not. Is it as good as I can do without killing myself or the bank, in my specific situation? yeah... and hopefully it mitigates enough. I'm not looking for silent... too many other weak links and not a dedicated room in my basement... Hopefully it is good enough!


Those QuiteBox's are nice, but building them yourself may save a little money. For my current room it would be around $900 or so. I think I could buy the material and Green Glue cheaper and build them. The Soundproofing company has a good installation SIM on how to build backer boxes for lights and speakers. Just another thought. This is probably what I will be doing.

https://www.soundproofingcompany.com/resources/soundproofing-installation-manuals-sim


----------



## jcr159

Ladeback said:


> Those QuiteBox's are nice, but building them yourself may save a little money. For my current room it would be around $900 or so. I think I could buy the material and Green Glue cheaper and build them. The Soundproofing company has a good installation SIM on how to build backer boxes for lights and speakers. Just another thought. This is probably what I will be doing.
> 
> https://www.soundproofingcompany.com/resources/soundproofing-installation-manuals-sim


yep, i agree, they are cheaper to build DIY for sure...

in my case, I'm looking to drop some cash to save labor, but not everyone is in the same boat.

I sorta tapped out a bit since the start of my project involved a wet saw, jackhammer, re-plumbing the full bath under the basement slab that the builder put in a stupid place... That was followed up with hauling a yard of concrete, and a yard of dirt up out of the basement to a couple bagsters... i don't recommend that... it sucked, lol.

I also ripped out the lally column in the center of my span and replaced it with two (engineering approved of course). Hauled 30 bags of quickcrete and a mixer down to my basement to pour new footings...

Finally, I drilled over 1000 tapcons to secure the subfloor... At this point, I'm running outta gas, otherwise I'd be building boxes! 

For everyone else, boxes aren't hard to build and if you are getting the supplies (GG) anyway, DIY ain't bad...


----------



## Ladeback

jcr159 said:


> yep, i agree, they are cheaper to build DIY for sure...
> 
> in my case, I'm looking to drop some cash to save labor, but not everyone is in the same boat.
> 
> I sorta tapped out a bit since the start of my project involved a wet saw, jackhammer, re-plumbing the full bath under the basement slab that the builder put in a stupid place... That was followed up with hauling a yard of concrete, and a yard of dirt up out of the basement to a couple bagsters... i don't recommend that... it sucked, lol.
> 
> I also ripped out the lally column in the center of my span and replaced it with two (engineering approved of course). Hauled 30 bags of quickcrete and a mixer down to my basement to pour new footings...
> 
> Finally, I drilled over 1000 tapcons to secure the subfloor... At this point, I'm running outta gas, otherwise I'd be building boxes!
> 
> For everyone else, boxes aren't hard to build and if you are getting the supplies (GG) anyway, DIY ain't bad...


An AVS member in my area moved into a new house a year or so ago and is building his theater under a suspended garage and he wanted more depth so he broke out concrete, dug down and put concrete back in. Here is the link to it. https://www.avsforum.com/forum/19-d...onstruction/2580921-cinema-midwest-2-0-a.html

I want to move one column in my plan, but my wife thinks it will cost a lot and doesn't even want me to look into it. I can probably work around it though depending on how orient the room. Right now have some walls framed to 14'x25'-10"x8'-10". I am thinking of moving one wall 3' and decoupling everything, adding mass and insulation. My wife doesn't get it, but I know if I do it right the room will sound better and then I will have to do treatments.

Good luck on your project.


----------



## jcr159

Ladeback said:


> An AVS member in my area moved into a new house a year or so ago and is building his theater under a suspended garage and he wanted more depth so he broke out concrete, dug down and put concrete back in. Here is the link to it. https://www.avsforum.com/forum/19-d...onstruction/2580921-cinema-midwest-2-0-a.html
> 
> I want to move one column in my plan, but my wife thinks it will cost a lot and doesn't even want me to look into it. I can probably work around it though depending on how orient the room. Right now have some walls framed to 14'x25'-10"x8'-10". I am thinking of moving one wall 3' and decoupling everything, adding mass and insulation. My wife doesn't get it, but I know if I do it right the room will sound better and then I will have to do treatments.
> 
> Good luck on your project.


thanks! it was a super pain in the butt... i got estimates, but they were in the ballpark of: i don't want to do it unless you make me rich in the process price range...

to do the 2 column footings no one would touch it for less than 5 grand...

to cut up the floor and rough in the full bath, 5-10 grand more...

i saved a lot of money, but my back and joints are paying for it, lol! good luck!


----------



## mkiv808

So we left a 1/4” gap between drywall and floor. Clips and channel. Going to do carpet and pad so that will cover the gap, but is acoustic sealant needed too?


----------



## mhutchins

mkiv808 said:


> So we left a 1/4” gap between drywall and floor. Clips and channel. Going to do carpet and pad so that will cover the gap, but is acoustic sealant needed too?



Absolutely!!


----------



## tdwpgtp

Good evening everyone, I am about to attempt to soundproof a basement room that currently has 2 exterior clay brick walls, and one interior clay brick wall, all already covered with one layer of drywall. The 2 exterior walls have some vapor barrier and carpet padding (?) behind the drywall, but the interior wall is just drywall on 3x2 over the brick, with a small gap between the studs and brick (see picture). This wall is significantly less sturdy, and acts like a large drum when you tap it. The 4th wall will be built staggered stud and a green glue sandwich. The ceiling will also be a green glue sandwich. My main goal is keeping the sound from going into the room above as much as I can within a fairly small budget. I know it is not going to be a vault. 

My questions are as follows:

1) is there anything I should do to that 2x3 studded wall other than a green glue sandwich? Should it be rebuilt or fix to the brick anywhere? Is flanking likely to occur through the drywall and then echo up into the ceiling cavity? I'm already cutting it close on the width of the room, so a staggers stud in that direction simply can't happen. A 2x4 wall is even pushing it



2) the same applies to the exterior walls, except I believe they are 2x4. Will a green glue sandwich be sufficient to prevent most flanking up into the room above? EDIT: These walls are actually just 2x2 "studs" over the carpet padding and vapor barrier. I'd like to replace them with proper 2x4, but as I stated elsewhere, space in that direction is a serious issue.

3)does the order of drywall matter (walls or ceiling first)? I think I've read that the order should be ceiling layer, wall layer, ceiling layer, wall layer. Since my walls are already up, can I do the opposite or will it make some difference? I plan on using acoustic caulk either way. 

Please let me know if anyone needs any clarification, and I truly appreciate any input. I have attached a picture of the 2x3 interior wall, although it probably doesn't show much.


----------



## OrangePhile

In an attempt to get my basement HT plan approved by my city to get a permit I was told that hat channel and clips are not approved/certified when holding up the weight of two layers of 5/8. Anybody else had similar issues or do we all really do it without approval? 


Sent from my iPhone using Tapatalk


----------



## mhutchins

Hey Orange,

Maybe if you show the inspector the specification sheet for the specific clips you intend to use and highlight the rated weight per clip (typically 30-35lbs). Also mention to the inspector that the spacing is closer to support the greater weight and still stay within the weight range for each clip. For example, the spec sheet attached for the Isomax clip states that each clip is rated to support 36lbs and that represents a 2.5x safety factor (See section 2.01(B)). Your inspector may only have experience with resilient channel, which is an entirely different animal.

Mike

Kinetics Noise Isomax Specification Sheet


----------



## lax01

Just starting to dig into sound proofing and unfortunately, I have a lot of constraints living in a rented apartment - I was hoping I could semi-sound proof our living room from our bedroom to cut down on noise with weather proofing and a door sweep - does anyone have any high value (i.e.: cheaper) / non-permanent solutions? 

I was looking at these two on Amazon but as I started reading more, it seems like these are just smoke and mirrors when it comes to sound isolation:
* https://www.amazon.com/dp/B07CG7BN5...olid=2B1P7254WEPG0&psc=1&ref_=lv_ov_lig_dp_it
* https://www.amazon.com/dp/B07H9Q8ZZ...olid=2B1P7254WEPG0&psc=1&ref_=lv_ov_lig_dp_it

I also found this but I *really* do not want to drill into the rental's door to install - https://www.amazon.com/dp/B010C5ZNSG?th=1 (can I install with strong double-sided tape?)

Any other / better solutions for sound-proofing in a rental apartment?

Thanks!


----------



## citsur86

Hey Everyone, I am in the process of having a home built in a development going up which is being built by a "custom builder". More on that in a minute. I am having the builder put a 20'x14' dedicated home theater room in the basement which will have a 3x3 front sound stage and a single platform as a seat riser. I asked about sound proofing and they said the most they'd do is batt insulation in the walls and ceiling. They aren't interested in doing, nor will they entertain doing any type of decoupling or other, better soundproofing techniques to prevent lower frequency transmission. Maybe they're more semi-custom builders than full custom. My main question for this group is this. With the celings in the basement, 1st floor, and 2nd floor all being 9ft+, how much sound transmission should i expect to reach the 2nd level of the home from the basement when playing movies at louder volumes. I have small children and one of my goals of the theater was to be able to put my kids to sleep and watch a movie/show at volume levels that are comfortable. In my current home, my living room home theater is right under my kids rooms so after their asleep, its basically lower listening levels (sometimes with subtitles on for quieter scenes) and I want to be able to avoid that. Do you all think i could get away with reasonably loud volumes for action movies "after dark" without the kids getting an earful or a bunch of vibrations up on the second floor? Any help or recommendations is greatly appreciated. Here are the renders for the proposed theater.


----------



## mhutchins

citsur86 said:


> .....*1)* how much sound transmission should i expect to reach the 2nd level of the home from the basement when playing movies at louder volumes. I have small children and one of my goals of the theater was to be able to put my kids to sleep and watch a movie/show at volume levels that are comfortable. In my current home, my living room home theater is right under my kids rooms so after their asleep, its basically lower listening levels (sometimes with subtitles on for quieter scenes) and I want to be able to avoid that.
> 
> *2) *Do you all think i could get away with reasonably loud volumes for action movies "after dark" without the kids getting an earful or a bunch of vibrations up on the second floor?


1) Whatever you builder does will probably result in the same poor isolation you have in your current home. How loud the perceived sound will be on the 2nd floor is dependent on a number of factors such as the layout of the home and flanking paths via HVAC, stairwells etc.

2) No. You will likely need to do substantial sound proofing in the basement to satisfy your expectations vs. waking up the kids and wife after the first explosion, car wreck or gunfight. The best thing your builder could do to help you is to eliminate the double doors and go with a single 36"x80" solid core door. If code will allow leaving the drywall off the walls in the theater, that will save you the mess of having to remove all the drywall, but that seems to be the limit of what your builder is willing to do that would help.

Mike


----------



## citsur86

mhutchins said:


> 1) Whatever you builder does will probably result in the same poor isolation you have in your current home. How loud the perceived sound will be on the 2nd floor is dependent on a number of factors such as the layout of the home and flanking paths via HVAC, stairwells etc.
> 
> 2) No. You will likely need to do substantial sound proofing in the basement to satisfy your expectations vs. waking up the kids and wife after the first explosion, car wreck or gunfight. The best thing your builder could do to help you is to eliminate the double doors and go with a single 36"x80" solid core door. If code will allow leaving the drywall off the walls in the theater, that will save you the mess of having to remove all the drywall, but that seems to be the limit of what your builder is willing to do that would help.
> 
> Mike


Thanks for the info - i didn't expect any different. They won't be able to leave the room partially unfinished because we wouldn't be able to get a CO otherwise. I did a lot of reading about damping/decoupling etc. It makes sense, but it does seem to be more expensive/effort than i can likely take on right now. I don't expect the batt to do much at all if anything. I'm thinking the house being on the larger side with the second floor quiet far away i will probably be able to get away with comfortable listening volumes but likely not reference/theater like audio in the night. Its just something I'll have to work around for a while. It will definitely be better than my current smaller homes living room home theater.


----------



## macming

citsur86 said:


> Thanks for the info - i didn't expect any different. They won't be able to leave the room partially unfinished because we wouldn't be able to get a CO otherwise. I did a lot of reading about damping/decoupling etc. It makes sense, but it does seem to be more expensive/effort than i can likely take on right now. I don't expect the batt to do much at all if anything. I'm thinking the house being on the larger side with the second floor quiet far away i will probably be able to get away with comfortable listening volumes but likely not reference/theater like audio in the night. Its just something I'll have to work around for a while. It will definitely be better than my current smaller homes living room home theater.


Regular drywall construction is probably not going to do a lot for sound proofing. Depending on how much bass you're running, I think it's best to at least attempt to put in some sound proofing solution. 

If your build isn't willing to run HAT channels, it's more likely they are willing to order 5/8" drywall with some green glue in between. Even if you can do that for the theatre room, it will go a long way without any other measure.


----------



## citsur86

macming said:


> Regular drywall construction is probably not going to do a lot for sound proofing. Depending on how much bass you're running, I think it's best to at least attempt to put in some sound proofing solution.
> 
> 
> 
> If your build isn't willing to run HAT channels, it's more likely they are willing to order 5/8" drywall with some green glue in between. Even if you can do that for the theatre room, it will go a long way without any other measure.




Thanks we have our pre construction meeting coming up so I’ll ask about a 2 drywall layer with green glue compound between. As of right now they have only agreed to use batt insulation in the walls and ceiling surrounding the theater. Any idea what a reasonable install of 2x 5/8 drywall with green glue compound between should run? Room is 14’6” x 19’ 6” x 9’. It’ll have two soffits on either side as well on the ceiling.


----------



## b_scott

if I do green glue and 5/8" drywall doubled up for my ceiling, how much green glue on average would I need for 300 square feet (ten 8x4' times two)


----------



## macming

citsur86 said:


> Thanks we have our pre construction meeting coming up so I’ll ask about a 2 drywall layer with green glue compound between. As of right now they have only agreed to use batt insulation in the walls and ceiling surrounding the theater. Any idea what a reasonable install of 2x 5/8 drywall with green glue compound between should run? Room is 14’6” x 19’ 6” x 9’. It’ll have two soffits on either side as well on the ceiling.


The conversation may go easier if you offer to purchase the green glue. I live in Canada and wasn't able to easily purchase a bucket, so I ended up using tubes of GG. At ~$20CAD/tube, I think I might've used 20 - 30 tubes for my theatre? Depending on what you're going for, I only used 1 tube per 4x8 sheet instead of the 2 tube recommendation. 

My theatre is a bit smaller than yours and I paid around $2-3K CAD extra for drywall and installation. 

I also picked up acoustical caulking from the same manufacturer as GG. My contractor caulked all the edges with this caulking in the theatre room. This is easy enough that you might be able to DIY and your builder should be open to it. 




b_scott said:


> if I do green glue and 5/8" drywall doubled up for my ceiling, how much green glue on average would I need for 300 square feet (ten 8x4' times two)


The reco is 2 tubes per 4x8. I cheaped out and only used 1. Then again, I used 1 sheet of Sonopan and 2 sheets of 5x8" drywall in the ceiling, plus double stud framing with double 5x8" drywall.


----------



## b_scott

macming said:


> The reco is 2 tubes per 4x8. I cheaped out and only used 1. Then again, I used 1 sheet of Sonopan and 2 sheets of 5x8" drywall in the ceiling, plus double stud framing with double 5x8" drywall.


Wow. $20 a tube too. Even if I only did one my 10 tube ceiling would cost $200 more.


----------



## macming

b_scott said:


> Wow. $20 a tube too. Even if I only did one my 10 tube ceiling would cost $200 more.


I'm in Canada, so it's a bit cheaper state side. FWIW, if I don't have my subs on, my wife can't hear ANYTHING in the kitchen that is directly above my theatre while I'm watching a movie downstairs. I'd easily spend the money on GG again if I were building another theatre.


----------



## b_scott

macming said:


> I'm in Canada, so it's a bit cheaper state side. FWIW, if I don't have my subs on, my wife can't hear ANYTHING in the kitchen that is directly above my theatre while I'm watching a movie downstairs. I'd easily spend the money on GG again if I were building another theatre.


My room won't be fully enclosed, since my basement stairs will be open to the room. Those stairs go up and meet the kitchen. I wonder if it's worth it


----------



## b_scott

What type of doors to people recommend? Looking for something prehung and ready to go that isn't a million dollars.


----------



## macming

b_scott said:


> What type of doors to people recommend? Looking for something prehung and ready to go that isn't a million dollars.


I just bought a solid wood core door with no pattern and I put a sheet of 3/4" MDF on both sides. It's working well and looks good with some trim.

The door ended up being over 100lbs, so I would plan mounting options appropriately.


----------



## b_scott

macming said:


> I just bought a solid wood core door with no pattern and I put a sheet of 3/4" MDF on both sides. It's working well and looks good with some trim.
> 
> The door ended up being over 100lbs, so I would plan mounting options appropriately.


thanks. I don't think I'll be putting anything on top of it but that's an idea. My wife will likely want something with a pattern. I will likely go solid wood or at least core.


----------



## jcr159

b_scott said:


> thanks. I don't think I'll be putting anything on top of it but that's an idea. My wife will likely want something with a pattern. I will likely go solid wood or at least core.


Without the door at (presumably) the top of the stairs, it won't be worth doing much at all...


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## b_scott

jcr159 said:


> Without the door at (presumably) the top of the stairs, it won't be worth doing much at all... /forum/images/smilies/smile.gif


There's a door at the top of the stairs. There will also be a door separating theater from utility basement, which is the one I need to buy.

Edit stairs pics below. Left is the outside, right is the door to the kitchen area.


----------



## jconjason

macming said:


> I just bought a solid wood core door with no pattern and I put a sheet of 3/4" MDF on both sides. It's working well and looks good with some trim.
> 
> 
> 
> The door ended up being over 100lbs, so I would plan mounting options appropriately.


Which door did you get?


----------



## jcr159

Quick question... I know this isn't the typical recommendation, but I'm building a basement general purpose room(s).

there will be 2 supply and one air return to the space, no dead vent in this situation.

ceiling will be drywall, potentially on RC or Hat channel. boxes behind Atmos speakers, r19 in joist bays above. No room for a drop ceiling.

Would adding a layer of MLV above the drywall help? I can either get backer boxes for all the can lights, or for the same price, basically put up a continuous barrier of MLV. Probably no point to decoupling the drywall with all the holes for the can lights, but the joists are level and need some blocking to level the ceiling, so i figure RC is as easy as lumber...

but with the HVAC vents, am I wasting my money?

Edit: only one layer of 5/8 drywall in all installations and no GG obviously. 

thanks!


----------



## schwock5

jcr159 said:


> Quick question... I know this isn't the typical recommendation, but I'm building a basement general purpose room(s).
> 
> there will be 2 supply and one air return to the space, no dead vent in this situation.
> 
> ceiling will be drywall, potentially on RC or Hat channel. boxes behind Atmos speakers, r19 in joist bays above. No room for a drop ceiling.
> 
> Would adding a layer of MLV above the drywall help? I can either get backer boxes for all the can lights, or for the same price, basically put up a continuous barrier of MLV. Probably no point to decoupling the drywall with all the holes for the can lights, but the joists are level and need some blocking to level the ceiling, so i figure RC is as easy as lumber...
> 
> but with the HVAC vents, am I wasting my money?
> 
> thanks!


i'm sort of in the extact same situation. I haven't asked Ted yet, was going to wait until i'm farther along, but was wondering atleast for the space in the cieling where the duct is and where the atmos speakers and backer boxes are, doe sit make sense atleast where those items are to put some MLV as well.

For the duct it owuld be between the duct and the channels/drywall.
for the atmos/backerboxes just using a MLV vinyl wrap around the backer bxes between them and the insulation or just in the joist cavity where they are.

also wondering if in the soffit where duct is as well putting MLV around that to limit the sound to only being within the duct nad not going through to the other side.


----------



## macming

jconjason said:


> Which door did you get?


My contractor bought it from his source.


----------



## macming

jcr159 said:


> Quick question... I know this isn't the typical recommendation, but I'm building a basement general purpose room(s).
> 
> there will be 2 supply and one air return to the space, no dead vent in this situation.
> 
> ceiling will be drywall, potentially on RC or Hat channel. boxes behind Atmos speakers, r19 in joist bays above. No room for a drop ceiling.
> 
> Would adding a layer of MLV above the drywall help? I can either get backer boxes for all the can lights, or for the same price, basically put up a continuous barrier of MLV. Probably no point to decoupling the drywall with all the holes for the can lights, but the joists are level and need some blocking to level the ceiling, so i figure RC is as easy as lumber...
> 
> but with the HVAC vents, am I wasting my money?
> 
> thanks!


I have regular HVAC in my theatre, and I did 1 layers of Sono plan, 2 sheets of 5/8" drywall with GG in between. The soundproofing worked better than I expected. However, if you are doing green glue, is there a need to also use MLV?


----------



## jcr159

macming said:


> I have regular HVAC in my theatre, and I did 1 layers of Sono plan, 2 sheets of 5/8" drywall with GG in between. The soundproofing worked better than I expected. However, if you are doing green glue, is there a need to also use MLV?


Good points on the GG. I should have mentioned that in all cases I’ll only have one layer of 5/8 drywall.


----------



## b_scott

Basement wall build:

I was just wondering - is there any way that putting a piece of rubber between where the top plate of my wall meets the joist about can serve as a sort of decoupling so that sound vibration isn't transferred upstairs as much? Does that make sense?


----------



## jcr159

b_scott said:


> Basement wall build:
> 
> I was just wondering - is there any way that putting a piece of rubber between where the top plate of my wall meets the joist about can serve as a sort of decoupling so that sound vibration isn't transferred upstairs as much? Does that make sense?


I suppose it is better than directly coupling, but barely... the screws/nails attaching the top plate will still directly transfer the energy...

you are better off building your wall a bit short of directly contacting the joists, and using IB3 style clips (there are many) to attach the top plate to the joists..

https://www.soundproofingcompany.com/product_information/ib-3-decoupling-bracket


----------



## b_scott

jcr159 said:


> I suppose it is better than directly coupling, but barely... the screws/nails attaching the top plate will still directly transfer the energy...
> 
> you are better off building your wall a bit short of directly contacting the joists, and using IB3 style clips (there are many) to attach the top plate to the joists..
> 
> https://www.soundproofingcompany.com/product_information/ib-3-decoupling-bracket


Thanks. Ideally I want to do clips, but they are really cost prohibitive. So I'm still thinking about them. I was just trying to think of other ways to help.

I keep hearing different opinions on hat channel + clips, or resilient channel only, or resilient channel + clips. There doesn't seem to be a solid answer on what to do there. Regardless of double drywall or green glue.


----------



## lax01

lax01 said:


> Just starting to dig into sound proofing and unfortunately, I have a lot of constraints living in a rented apartment - I was hoping I could semi-sound proof our living room from our bedroom to cut down on noise with weather proofing and a door sweep - does anyone have any high value (i.e.: cheaper) / non-permanent solutions?
> 
> I was looking at these two on Amazon but as I started reading more, it seems like these are just smoke and mirrors when it comes to sound isolation:
> * https://www.amazon.com/dp/B07CG7BN5...olid=2B1P7254WEPG0&psc=1&ref_=lv_ov_lig_dp_it
> * https://www.amazon.com/dp/B07H9Q8ZZ...olid=2B1P7254WEPG0&psc=1&ref_=lv_ov_lig_dp_it
> 
> I also found this but I *really* do not want to drill into the rental's door to install - https://www.amazon.com/dp/B010C5ZNSG?th=1 (can I install with strong double-sided tape?)
> 
> Any other / better solutions for sound-proofing in a rental apartment?
> 
> Thanks!


Hah - thanks for all the help - I experimented with this: https://www.amazon.com/gp/product/B084MM9BLH/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Couldn't close the door so it didn't really help - adhesive made a mess as well - guess it might help a little though haha

Still looking for suggestions! Thanks!


----------



## Ladeback

b_scott said:


> Thanks. Ideally I want to do clips, but they are really cost prohibitive. So I'm still thinking about them. I was just trying to think of other ways to help.
> 
> I keep hearing different opinions on hat channel + clips, or resilient channel only, or resilient channel + clips. There doesn't seem to be a solid answer on what to do there. Regardless of double drywall or green glue.


@b scott, I have been debating for a long time whether to decouple my walls and go with double drywall and Green Glue. I think the iB-3 clips are about $6 to $7 a piece and go on the ends of the walls at about 6" and can be spaced 4' apart, but make sure you have 2 over each door entry. To me the killer is the price of Green Glue. I am about to say the heck with it and just use 5/8" drywall and be done with it. My wife doesn't complain that much when I am downstairs watching a movie while she is above in our living room watching her shows. I have been told I could use the money for better better equipment like diy speakers and subs and sound treatments for the room.

As for HVAC I think I will try a supply and return dead vent for now. If that doesn't work may add a mini split. I have been thinking about my theater so long and try to figure out how to pay to soundproof it when my wife and kid don't really care much about it and it doesn't bother them. I think it is time to just get it done. 

Good luck on your decision.


----------



## b_scott

I'm right there with you. Thanks!


----------



## Ericadamwood

Hey all, I have a unique scenario I can’t seem to find any info directly surrounding. I am in the process of building a apartment over garage and am wrangling with the arc of the floor assembly between the two. I have reviewed all prescribed floor assemblies and can’t find one that compares. What I have now starting from bottom up is: 2x12 12” oc > 1-1/8 advantech > 3” full weight concrete slab

The slab is the finished floor in the apartment and can not have covering to maintain radiant performance. I’m wrangling With what to do in/under framing if anything. Floor damps sound now very well, but I’m trying to decide if mineral fiber and RC are a worthy addition before drywall goes on ceiling. This would be a no brainer with conventional floor construction , but do the extremely high mass of the floor system is throwing me for a loop. 

Any insights would be much appreciated.


----------



## mhutchins

Take a look here and here. and the Kinetics Noise Control website. Your current floor probably has an STC rating of ~50, but the impact noise rating is half that. Resilient channel won't gain you much improvement. Two layers of 5/8" Type-X drywall with Green Glue between the joists will improve the impact rating substantially in the room below, but won't do much for the STC. If you want to make a big difference in the STC, you need to do thick insulation batts between the joists then clips and channel for the ceiling with 2 layers of 5/8" Type-X drywall and Green Glue in between.


If the space below is staying as a garage, then impact noise won't be much of a concern, because these sounds can be easily blocked by the existing walls in the garage. For airborne noise, the clips and channel system is most effective.


I suspect the bigger problem you are facing is flanking noise through the slab into the framing. My guess is that no effort at decoupling the slab from the rest of the house was attempted, which is really a shame. You could have had a much quieter home had they put a resilient layer down on the floor (like horse stall mat) and a small border around the perimeter of the slab before the pour. Right now, that slab is perfectly coupled to the framing and concrete is an excellent conductor of sound.


You can limit airborne sound from coupling into the walls and ceiling of the new room, but your efforts will be compromised by the flanking sound related to the slab.


Mike


----------



## A.T.M.

b_scott said:


> ...So I'm still thinking about them...I keep hearing different opinions on hat channel + clips, or resilient channel only, or resilient channel + clips....


I thought resilient channel was a big no no.
I would definitely use the clips and two layers of DW with GG.

I agree with Mike below:



mhutchins said:


> ...Resilient channel won't gain you much improvement. Two layers of 5/8" Type-X drywall with Green Glue between the joists will improve the impact rating substantially in the room below.
> ...clips and channel for the ceiling with 2 layers of 5/8" Type-X drywall and Green Glue in between.
> ...For airborne noise, the clips and channel system is most effective.
> ...the bigger problem you are facing is flanking noise through the slab into the framing.


Aaron


----------



## jcr159

Resilient channel is just fine, but it holds less weight...

The main reason it is discouraged is that generally speaking the trade folks screw up the installation and short out they system. If you have a good installer/DIY and understand how it works, it is just fine.

Unless of course you want 2 layers of 5/8 type x w/GG. Then it isn’t rated for that weight.


----------



## b_scott

Thanks all. I bought some clips (non rubber) and I’ll be getting some hat channel. I may not do two layers of drywall but at least it’s something. GG is too expensive


----------



## noysboy

For tight budgets, consider using Roberts Carpet Glue instead of green glue. Search youtube and google, but there are some happy people that have used it and its a lot cheaper.


----------



## b_scott

noysboy said:


> For tight budgets, consider using Roberts Carpet Glue instead of green glue. Search youtube and google, but there are some happy people that have used it and its a lot cheaper.


Thanks!


----------



## Ladeback

The carpet glue seems to be around 75% to 80% cheaper. I am thinking about using if I go with two layers.


----------



## b_scott

Ladeback said:


> The carpet glue seems to be around 75% to 80% cheaper. I am thinking about using if I go with two layers.


IF I do DD, i'll probably use carpet glue. My only concern is how to apply. I assume tube would be best, but I'm not sure how I'd use it out of a bucket.


----------



## Ladeback

b_scott said:


> IF I do DD, i'll probably use carpet glue. My only concern is how to apply. I assume tube would be best, but I'm not sure how I'd use it out of a bucket.


Probably with a carpet glue trowel like this. Not sure it come in tubes. You would I guess apply it to the drywall then screw up on the ceiling and walls. It will add a little more mass, but not for sure how much. I am thinking about it as well, but would if double drywall would be good enough. There is just three of us in the house and my wife and kid don't complain to much about the the sound, but I only have one 12" sub running. Hoping to build more after the room is more complete.

https://www.homedepot.com/p/Roberts...oring-Trowel-with-Wood-Handle-49737/100197989


----------



## sk576c

I've been looking through the thread, doing searches and then reading results and pages associated with results and not making much progress. 

I am converting a 15x20 room into a home theater. Unfortunately directly upstairs from this room is the master bedroom. I am currently trying to address what to do with my hvac ducts in the ceiling (2 supply lines and 1 return). The walls in the room will be getting the typical double layer of drywall and green glue treatment. However on the ceiling I will be taking it down and adding in more insulation and clips to decouple the ceiling drywall from the floor joists. However Im unsure what to do with the hvac ducting. The room has its on ducting but of course it ties back into a main trunk that feeds this portion of the house where it branches off into this room and the upstairs room. I wont be adding a new HVAC system, or mini split etc. 

My current plan is to remove 10 ish feet of the metal ducting for the supply lines to this room and replace them with flexible "acoustical" ducting. I was also considering adding an air maze into each of the supply lines near the boot or whatever you call the area where the duct joins the actual vent at the end of the line. As far as the return line, it is actually in the far back of the room and has flex duct already so not sure what I can do there. 

Flex ducts Im looking at are 
http://www.flexmasterusa.com/Products/FlexibleDuct/Type6.aspx
https://www.homedepot.com/p/Master-...le-Duct-R6-Silver-Jacket-F6IFD6X300/100396935

I've basically got about a week to do something with this as that is when the drywall folks will be putting the ceiling back up. 

Any suggestions, am I wasting my time even putting the flex duct and or air mazes in ?


----------



## gimmepilotwings

sk576c said:


> I've been looking through the thread, doing searches and then reading results and pages associated with results and not making much progress.
> 
> I am converting a 15x20 room into a home theater. Unfortunately directly upstairs from this room is the master bedroom. I am currently trying to address what to do with my hvac ducts in the ceiling (2 supply lines and 1 return). The walls in the room will be getting the typical double layer of drywall and green glue treatment. However on the ceiling I will be taking it down and adding in more insulation and clips to decouple the ceiling drywall from the floor joists. However Im unsure what to do with the hvac ducting. The room has its on ducting but of course it ties back into a main trunk that feeds this portion of the house where it branches off into this room and the upstairs room. I wont be adding a new HVAC system, or mini split etc.
> 
> My current plan is to remove 10 ish feet of the metal ducting for the supply lines to this room and replace them with flexible "acoustical" ducting. I was also considering adding an air maze into each of the supply lines near the boot or whatever you call the area where the duct joins the actual vent at the end of the line. As far as the return line, it is actually in the far back of the room and has flex duct already so not sure what I can do there.
> 
> Flex ducts Im looking at are
> http://www.flexmasterusa.com/Products/FlexibleDuct/Type6.aspx
> https://www.homedepot.com/p/Master-...le-Duct-R6-Silver-Jacket-F6IFD6X300/100396935
> 
> I've basically got about a week to do something with this as that is when the drywall folks will be putting the ceiling back up.
> 
> Any suggestions, am I wasting my time even putting the flex duct and or air mazes in ?


I had a an HVAC company come out and that is the type of flex duct that they used for my room. I couldn't quite get a maze, but I got three turns in there.


----------



## b_scott

I had an HVAC company come and look at my vents to see if I could be more efficient with space in my basement ceiling and they said they wouldn't recommend doing anything since it would restrict airflow. And that's someone who could have made money off me to do it.


----------



## sk576c

b_scott said:


> I had an HVAC company come and look at my vents to see if I could be more efficient with space in my basement ceiling and they said they wouldn't recommend doing anything since it would restrict airflow. And that's someone who could have made money off me to do it.


What did you end up doing to resolve issues with sound escaping your room into the duct work? Assuming you had that issue as well.


----------



## b_scott

sk576c said:


> What did you end up doing to resolve issues with sound escaping your room into the duct work? Assuming you had that issue as well.


I'm still building soffits. But I'm not sure I'll have too much of that issue, as there is only one return and one supply to the upstairs which are the only vents I'm concerned about, and those will be fully enclosed in drywall. I'm doing clips and channel, so I'm hoping that helps. I may also stuff some rockwool in the cavities between the framing and steel. But there's not too much I can do about it without spending thousands, I think. I'm really only concerned about keeping family awake on the second floor when I'm watching movies late at night in the basement.

edit: I will have one supply and one return in the theatre. Those may carry sound. But I'm hoping it disperses over two floors. I guess we'll see.


----------



## sk576c

Ahhh ok thats make sense then. Ive got two supply lines going to my theater room that come off a main duct that supplies the upstairs master bedroom's 3 supply lines. The return line is already flex duct but literally Ys off 3 feet away from the return duct vent, the other side of the Y goes to the upstairs master bedroom return duct. Im doing the clips and rock wool in the ceiling. Worried all that effort will be wasted if the HVAC ducts just transfer the sound up to the master bedroom. So thats why Im looking at adding in some flex duct in place of the current metal ducting and perhaps even a short air maze in each of the supply lines to the room.


----------



## mhutchins

I think an air maze or serpentine box would give you the most bang for the buck. I recently just learned that if you build the maze out of wood, it will serve as a food source for mold. I plan to get around this issue by using a mold resistant paint for the inside before I add duct board to the interior walls. Zinsser brand makes a mold resistant paint that had some good internet reviews.

Mike


----------



## sk576c

mhutchins said:


> I think an air maze or serpentine box would give you the most bang for the buck. I recently just learned that if you build the maze out of wood, it will serve as a food source for mold. I plan to get around this issue by using a mold resistant paint for the inside before I add duct board to the interior walls. Zinsser brand makes a mold resistant paint that had some good internet reviews.
> 
> 
> Mike


On wow. Glad you mentioned that. I totally intended to use wood! 

Lowes has this thick plastic pvc board. 
On wow. 

https://www.lowes.com/pd/Royal-Buil...25-in-x-12-ft-Common-Board-PVC-Board/50092324

I wonder if this plastic board would be less susceptible to mold. Otherwise I'll be looking for some mold resistant paint for the wood. 

Thanks for the heads up!


----------



## bogaboga

does anyone know what kinda of soundproofing i should expect from walls made of 8" or 9" concrete blocks and the ceiling is poured concrete? i have an upstair neighbor.


----------



## mhutchins

Kinetics Noise Control has a lot of tests with concrete and various forms of noise abatements. You are looking at a floor STC in the range of 53-59 but the IIC is but a third of that due to concrete's excellent noise conduction properties. In practical terms, you may not hear the stereo upstairs, but you may hear every footfall if they are wearing shoes with hard heels. The STC of the partition wall will be ~49.  NRC Canada has a great online app for figuring out expected STC values for numerous types of construction.

Mike


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## b_scott

would putting 9.5" pink in my ceiling (plus clips/channel, one layer drywall - yes I know, but only one layer) do anything to diffuse sound to upstairs or am I just wasting $200?

https://www.homedepot.com/p/Owens-C...-Insulation-Roll-15-in-x-25-ft-RU70/202585906


----------



## bogaboga

mhutchins said:


> Kinetics Noise Control has a lot of tests with concrete and various forms of noise abatements. You are looking at a floor STC in the range of 53-59 but the IIC is but a third of that due to concretes excellent noise conduction properties. In practical terms, you may not hear the stereo upstairs, but you may hear every footfall if they are wearing shoes with hard heels. The STC of the partition wall will be ~49.  NRC Canada has a great online app for figuring out expected STC values for numerous types of construction.
> 
> Mike


you are correct i don't hear anything from them expect when their kids run or jump around, but i'm more worried about my subwoofer reaching them, since low frequencies can travel through walls pretty easily.


----------



## toddn149

b_scott said:


> would putting 9.5" pink in my ceiling (plus clips/channel, one layer drywall - yes I know, but only one layer) do anything to diffuse sound to upstairs or am I just wasting $200?
> 
> https://www.homedepot.com/p/Owens-C...-Insulation-Roll-15-in-x-25-ft-RU70/202585906



Thinking of doing the same but maybe 2 layers of 5/8” drywall and no green glue. Let me know if you notice a difference if you go this route


----------



## b_scott

toddn149 said:


> b_scott said:
> 
> 
> 
> would putting 9.5" pink in my ceiling (plus clips/channel, one layer drywall - yes I know, but only one layer) do anything to diffuse sound to upstairs or am I just wasting $200?
> 
> https://www.homedepot.com/p/Owens-C...-Insulation-Roll-15-in-x-25-ft-RU70/202585906
> 
> 
> 
> 
> Thinking of doing the same but maybe 2 layers of 5/8â€ drywall and no green glue. Let me know if you notice a difference if you go this route
Click to expand...

Ended up buying the 6.5” r19. I won’t really know if there will be a difference since I never had a ceiling down there to begin with. Can’t hurt I guess.


----------



## Ladeback

toddn149 said:


> Thinking of doing the same but maybe 2 layers of 5/8” drywall and no green glue. Let me know if you notice a difference if you go this route


I have thought of doing this. I seen on Soundproofing Company's website that two layers of 1/2" drywall and no Green glue on both sides of the wall is around 55 STC rating. A single layer of 5/8" on one side and two layers on the other side with Green Glue is 52 STC rating. I was going to go all in, but am thinking of just going with 5/8" drywall and pink fluffy and be done with it. My wife doesn't complain now, but I don't have a lot of bass in my room, but hope to add more subs later and would just turn them down if it bothers her when she is sleeping. My room is in the basement under our kitchen and living room and the main speakers are around 60' away from our bedroom on the other end of the house.


----------



## toddn149

Ladeback said:


> I have thought of doing this. I seen on Soundproofing Company's website that two layers of 1/2" drywall and no Green glue on both sides of the wall is around 55 STC rating. A single layer of 5/8" on one side and two layers on the other side with Green Glue is 52 STC rating. I was going to go all in, but am thinking of just going with 5/8" drywall and pink fluffy and be done with it. My wife doesn't complain now, but I don't have a lot of bass in my room, but hope to add more subs later and would just turn them down if it bothers her when she is sleeping. My room is in the basement under our kitchen and living room and the main speakers are around 60' away from our bedroom on the other end of the house.



Seems like we are on the same page then. It’s hard though cause once you’re done it’s not like you can go back and change it... cheaply at least


----------



## Ladeback

toddn149 said:


> Seems like we are on the same page then. It’s hard though cause once you’re done it’s not like you can go back and change it... cheaply at least


The only way I know how would be to not mud and tape the second layer of drywall and hook all your speakers up to see how much it helps. A bucket of Green Glue covers roughly 365 sqft or they suggest two tubes of green glue. You could see if going with one tube of Green Glue or spread not put two loads on a sheet of drywall to make it go farther, but you won't get the full effect. I also think that a room inside a room with an air gap between them and double drywall would be good and still cheaper then GG, but take up more room.

I have walls up I just may go with what I have and live with it. By not going with GG, I could maybe done the line build some DIY subs to add to my front.


----------



## b_scott

yeah I'm doing one 5/8" layer with channels and clips, and pink fluffy r-19 in the ceiling. Also Fire and Sound insulation between the theatre and the half of my room that contains the drain pipes and HVAC system.


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## da1duc

So question, looks like I can source super cheap isolation channel, aka single sided. Minus the potential failures, would it be worth using in the secondary spaces of a basement for the walls. Game space, guest suite area in my case. Already planning on clips and channels for the theater space.

D


----------



## jcr159

da1duc said:


> So question, looks like I can source super cheap isolation channel, aka single sided. Minus the potential failures, would it be worth using in the secondary spaces of a basement for the walls. Game space, guest suite area in my case. Already planning on clips and channels for the theater space.
> 
> D


Both types of channel are effective. Unless you are aiming for a crazy low noise floor and going all out on communicating doors, etc... and install it without shorting it out, you won’t notice a difference. The reason hat and clips is recommended so much is that it’s just plain easier to work with and not screw up.. especially if you’re hiring out drywall contractors... they can’t be bothered to sink half their screws into the stud, let alone follow a careful fastening schedule without shorting the channel...

As an aside, I’m trying a new product from isostore for my new build... should be interesting if it works well... I’ll be able to use a combination of slightly different techniques than with hat and channel... the channel ends up being furring strips... it’s also slightly cheaper when ordering bulk from them too... anyway, good luck!

https://isostore.com/hushframe-raft-connector.html


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## kmerhar

Hi all - 

I've tried some searching, but not having much luck since most people are smart and build them in basements  I have a question about adding some sound proofing to a second floor theater. What's the best method for me in regards to the floor? I've checked out the soundproofing company and even reached out to them multiple times, but not having much luck. 

Wondering if anyone has some experience they can share? Will the underlayment be enough? Or do I need to add a floating floor on top of an underlayment to really have any affect? How thick of an underlayment is recommended?


----------



## schwock5

kmerhar said:


> Hi all -
> 
> I've tried some searching, but not having much luck since most people are smart and build them in basements  I have a question about adding some sound proofing to a second floor theater. What's the best method for me in regards to the floor? I've checked out the soundproofing company and even reached out to them multiple times, but not having much luck.
> 
> Wondering if anyone has some experience they can share? Will the underlayment be enough? Or do I need to add a floating floor on top of an underlayment to really have any affect? How thick of an underlayment is recommended?


i'm surprised you haven't had much luck with soundproofing company, they were always very responsive with me (though i haven't contacted them recently, my build is on a slight pause right now). I'm by no means an expert, but based off what i've read (and i'm sure others will have more/better input), i think you need to also advise if you are looking to just reduce sound to the floor below, or vibration as well to the floor below/rest of the house.
if it's reducing vibration from a subwoofer, using a decoupler on the subwoofer itself could help, or it may be decoupling the whole floor somehow.
If it's just sound, then it may be some kind of MLV underlayment, or even some of the docs i've seen they had where it's reducing the sound from the floor below (double up the 5/8 and GG from below to stop sound from coming from above)


----------



## b_scott

I was going to say, I thought mass loaded vinyl underlayment was the gold standard around these parts for soundproofing floors.


----------



## kmerhar

schwock5 said:


> i'm surprised you haven't had much luck with soundproofing company, they were always very responsive with me (though i haven't contacted them recently, my build is on a slight pause right now). I'm by no means an expert, but based off what i've read (and i'm sure others will have more/better input), i think you need to also advise if you are looking to just reduce sound to the floor below, or vibration as well to the floor below/rest of the house.
> if it's reducing vibration from a subwoofer, using a decoupler on the subwoofer itself could help, or it may be decoupling the whole floor somehow.
> If it's just sound, then it may be some kind of MLV underlayment, or even some of the docs i've seen they had where it's reducing the sound from the floor below (double up the 5/8 and GG from below to stop sound from coming from above)


Same here. I've left a messaged, sent a couple emails, and tagged Ted in my theater build thread, but no luck so far. I know there's a lot going on right now, so hopefully they're just busy. At a minimum I am looking to reduce noise. The walls are getting the hat channel/DD/GG treatment, so we're putting in a decent amount of effort. Blocking bass would be great, but I am not able to get a good consensus of what I can expect from just a good underlayment vs some decoupling. And if I decouple, whether or not I can do it from above with 2 layers of OSB and GG.



b_scott said:


> I was going to say, I thought mass loaded vinyl underlayment was the gold standard around these parts for soundproofing floors.


It appears to be from the Soundproofing Companies website. But not sure how thick and if I need to decouple the floor for the improvement to be worth the effort.


----------



## Peter M

Have a look at RIM by Kinetics

Cheers,


----------



## jcr159

I'd give these a look as well...

I'm liking a lot of stuff from ISO Store...

https://isostore.com/stc-acoustic-sleeper-theater-studio-floor-stage-soundproofing.html


----------



## logan1833

*New Construction Advice*

We are still relatively early in the process of building a new rowhouse that will have an apartment in the basement. The basement apartment will be separately metered, so no shared ductwork. Still, I've been losing sleep about possible sound transmission, especially going downward and bothering my future tenants -- the media room will be directly overhead their bedroom 

So, yesterday we had a site visit with the GC and I decided to raise the issue. To my pleasant surprise, he was reasonably well informed and eager to help me combat this issue. Without any leading from me, he recommended the following:


Surface mount lights in the basement instead of recessed lights
Thin coat of OC foam in the basement ceiling to seal any small nail holes, etc. Followed by Rockwool Safe and Sound.
Resilient channel followed by two layers of 5/8 drywall on basement ceiling.
A second layer of Advantech OSB subfloor on the main level. These two layers of OSB will be topped by 3/4" hardwood flooring. (And we'll almost certainly have a large rug/rug pad, at least in the media room above the bedroom.)

Based on my reading here, this sounds like a very good start (and better than what I might have expected from a typical GC). What he didn't mention was GG. When I raised it, he was a bit dismissive -- said he didn't think it would add all that much. Is he right? Should I insist on it, and, if so, would it be better/cheaper/easier to put GG between the two layers of OSB or the two layers of drywall? Would swapping the second layer of Advantech subfloor with something like Quietwood be a good alternative to GG for damping (perhaps he wouldn't be as resistant)? 

Any other tweaks you would make to his proposal to improve performance? He also mentioned I could add MLV, but based on what I've read, that seems inferior to GG/Quietwood. Thanks much!


----------



## schwock5

I started my own thread for a theater but haven't really been updating it or getting any attention. I had a few questions as i move through my process (if people think i should link and post this to my theater thread, let me know) but i also think this information as a whole is beneficial to everyone.

Due to room size constraints i'm forced to change my surround speakers to in wall. obviously this creates sound proofing issue.
I also have duct work i need to work around as well.

there's 4 issues i'm looking for advice on right now before i seal things up.

1. Ted mentioned MLV isn't worth it to wrap the whole room, i was going to ask him as well about this specific scenario, but for in walls, since the cavity is much smaller than a ceiling joist and a backer box may be tougher to implement and could compromise the sound, does it make sense to just line the specific stud cavity where the speaker will be with MLV as an added layer behind the speaker if i don't do a backer box?

2. For my in ceiling atmos, i have metal klipsch boxes, doe sit make sense in these joist cavities as well to potentially line them as an additional layer?

3. also for the duct work, before we build the sofit, should i line the ceiling and wall behind the duct with MLV (as sound enters the vent this will now be an additional layer behind the duct tot he next room and above. I highlighted in yellow what i kind of mean. it would be like a 2 foot wide MLV running the length of the duct to cover the back and top of it since the front and bottom would have DD+GG wiht jsut a single opening for the vent letting sound it.

4. i also was wondering about hiding TV wires and power plug in the wall. there's concrete behind that area, but some gaps of open space behind the framing. i've seen items with brush holes (seems like that would let in sound), or i could do a hard HDMI port and outlet (but this could become absolute and need upgraded in wall as well). should i just try and box in that area with DD+GG around the edge and then just need cables in without issue? 

5. in addition when running speaker cable throughout the walls, for the terminations, does anyone recommend any specific products or are any of the generic wall terminations fine?

i attached some pictures, i can provide more information if needed (i'm sure it's not very clear from these pictures)


----------



## mhutchins

kmerhar said:


> Hi all -
> 
> I've tried some searching, but not having much luck since most people are smart and build them in basements  I have a question about adding some sound proofing to a second floor theater. What's the best method for me in regards to the floor? I've checked out the soundproofing company and even reached out to them multiple times, but not having much luck.
> 
> Wondering if anyone has some experience they can share? Will the underlayment be enough? Or do I need to add a floating floor on top of an underlayment to really have any affect? How thick of an underlayment is recommended?


I'm about to start construction on a 2nd floor theater where sound isolation is paramount. The absolute best method for controlling sound transmission through the floor is the Kinetics RIM system. I'm planning 2" pads supporting 2x4 s that in turn will have 1-2 layers of subfloor with a 3" Gypcrete floor. Next best would be just the 2" pads supporting a 2-layer wood subfloor. In both cases you place insulation in the space between the structural floor and the floating floor. The advantage of the Gypcrete is a huge increase in mass for better bass isolation. Depending on your room size this can add $5-10k just for the floor.

Next best would be a floating floor on either Serenity mat or horse stall mats. You could probably save money on the mats by using 2x4 sleepers and just placing the mat between the structural floor and the 2x4s, again with insulation in the space between the rows of 2x4s. Floating wood floors usually require 2 layers with offset seams to create a stable deck. Screw the 1st layer into the 2x4s and the second layer only has to be screwed into the 1st layer. Make certain your screws do not go through to the structural floor, otherwise you will have negated most of your work. The 2x4 sleeper will help the bass a little vs just placing the wood deck directly on the rubber underlayment. I have seen examples where 2 layers of drywall was sandwiched between the wood layers to increase the mass of the floor in an effort to improve bass isolation.

The Isostore boats that were recommended below require screwing the decking through the rubber isolator into the structural floor. That creates a strong short circuit and seems like it would negate much of the potential performance from the isolators....

Mike


----------



## jcr159

mhutchins said:


> The Isostore boats that were recommended below require screwing the decking through the rubber isolator into the structural floor. That creates a strong short circuit and seems like it would negate much of the potential performance from the isolators....
> 
> Mike


I agree the sleeper pads aren't as good a solution as your proposed, but is a more budget friendly alternative... 

I just wanted to clear up a misconception on the install... the pads are only to be attached to one of the subfloor layers. The second floor layer can then be floated or attached using whatever required fastening schedule (really depends on the codes and type of floor to be installed). Fastening the subfloor layers together on 24" or 48" spacing is probably ok, depending on the usage. Though if you open the PDF with the detailed installation, it specifies how to fully float the second layer of subfloor, and options to screw or staple the sleeper pad (with spacing schedule) on one layer. You are definitely not supposed to screw the 2 layers together through the pad! As you point out, that shorts out the system...

I'd also think the pads are superior to the horse mats as it reduces surface contact area, but I don't have any data to back that up... could be bunk, lol


----------



## mhutchins

Ahhh. You are right. I only looked at the images where it states to fasten through the pad into the flooring below. For fire rated floors, the manufacturer also recommends fastening through the rubber isolator to secure the layers, otherwise you can fully float the floor for best performance.

Mike


----------



## simplyderp

Any ideas how much it would cost to hire a contractor to soundproof a 3000 cu ft room that has windows, doors, A/C vents, lights, and fire sprinklers?

At this point I'm just plugging the windows and replacing doors, but I want to fully "soundproof" if possible within a year.

Looking for point of "diminishing returns" for home theater use. Seems like wall in wall is commonly recommended.

Current walls are 2x6 framing with I think R21 insulation.


----------



## gimmepilotwings

simplyderp said:


> Any ideas how much it would cost to hire a contractor to soundproof a 3000 cu ft room that has windows, doors, A/C vents, lights, and fire sprinklers?
> 
> At this point I'm just plugging the windows and replacing doors, but I want to fully "soundproof" if possible within a year.
> 
> Looking for point of "diminishing returns" for home theater use. Seems like wall in wall is commonly recommended.
> 
> Current walls are 2x6 framing with I think R21 insulation.


'Fully soundproof' is nearly impossible. When thinking of soundproofing, try to consider how much you can lower sound and how much you are willing to spend on those diminishing returns. I am shooting for STC67 for walls and STC56 for ceilings. Unless you are building a concrete bunker with 1 foot thick walls you aren't really going to be soundproof. With that said, are you treating all walls, ceiling, floors etc?



With that said, I can give you some of the prices that I am paying/have paid for my 2600 cu ft room. 

(I will be giving estimates of just the room in question, as I finished an entire basement) 

Built wall within wall/framer *$2500-$3000* in constructing new wall in basement and included covering an exsting window. 

Soundproofing company clips, brackets green glue, *$1500.*

2 layers of 5/8 inch drywall x 50 sheets. *$750-900*

Labor for clips, channel, double drywall + green glue installation. I was quoted $30-55 a sheet with my contractor. *$1500-2500*.

I am building my own backer boxes to enclose recessed lighting, in wall speakers etc., If you want to hire someone for that, expect *$50* a box, or buy them onlne for around *$60*.

I am not listing any floor treatments, because I am not needing any, other than padding and carpet.

HVAC is really hard to price out. It depends on what you are looking for.

Of course prices may vary depending on location and the contractor hired.

Hope this helps.


----------



## gimmepilotwings

I am looking to build backer boxes for speakers. I am considering the SVS Prime Elevation for my ceiling height speakers and need to enclose them in the ceiling. The dimensions | 9.25” (H) 5.4” (W) 7.9” (D) I am doing clips/channel/DD+GG, so they will need to hang 2 3/8 inches below the trusses to be level with the drywall installation.

Questions:

What size box do you recommend building? My ceiling trusses are 16OC and 12" deep.
How do you mount them inside of the box, does it need to be floating? (not directly touching any of the insides of the box, resting comfortably on pink fluffy?)

I have IB clips that I will mount from the outside of the box to the trusses.

Any other tips are suggested.


----------



## simplyderp

gimmepilotwings said:


> 'Fully soundproof' is nearly impossible. When thinking of soundproofing, try to consider how much you can lower sound and how much you are willing to spend on those diminishing returns. I am shooting for STC67 for walls and STC56 for ceilings. Unless you are building a concrete bunker with 1 foot thick walls you aren't really going to be soundproof. With that said, are you treating all walls, ceiling, floors etc?
> 
> 
> 
> With that said, I can give you some of the prices that I am paying/have paid for my 2600 cu ft room.
> 
> (I will be giving estimates of just the room in question, as I finished an entire basement)
> 
> Built wall within wall/framer *$2500-$3000* in constructing new wall in basement and included covering an exsting window.
> 
> Soundproofing company clips, brackets green glue, *$1500.*
> 
> 2 layers of 5/8 inch drywall x 50 sheets. *$750-900*
> 
> Labor for clips, channel, double drywall + green glue installation. I was quoted $30-55 a sheet with my contractor. *$1500-2500*.
> 
> I am building my own backer boxes to enclose recessed lighting, in wall speakers etc., If you want to hire someone for that, expect *$50* a box, or buy them onlne for around *$60*.
> 
> I am not listing any floor treatments, because I am not needing any, other than padding and carpet.
> 
> HVAC is really hard to price out. It depends on what you are looking for.
> 
> Of course prices may vary depending on location and the contractor hired.
> 
> Hope this helps.


Sorry what I meant by fully soundproof is committing to a full solution. I'll do all the walls, ceiling, floor, tear down drywall if needed.

This is very promising thanks.


----------



## gimmepilotwings

simplyderp said:


> Sorry what I meant by fully soundproof is committing to a full solution. I'll do all the walls, ceiling, floor, tear down drywall if needed.
> 
> This is very promising thanks.


No problem. If you want to soundproof as much as you can, you will need to tear down drywall.


----------



## Harkon

*Has anyone produced data showing the STC rating for a 2", 3" and 4" wall cavity?

I'd like to make an informed choice on what size timbers (or steel stud work) to spec, considering sound proofing vs maximising room dimensions.*

Inside the room I plan to have stud work completely isolated from the walls brick/block walls. 

My original plan was to use 2x4 studs, so 4" of fluffy insulation, and about 3/4" gap from stud work to the brick/concrete walls.

If I use smaller stud work framing (probably steel) but still use the same 2 layers of plasterboard (same mass), how far does this reduce the effectiveness of the wall?

All four walls are already brick or block (1 wall is 4" thick, the other 3 are exterior walls and 12" thick) so don't want to lose more space than I need to if the concrete will help with some of the Low Frequency anyway.


----------



## jcr159

gimmepilotwings said:


> 'Fully soundproof' is nearly impossible. When thinking of soundproofing, try to consider how much you can lower sound and how much you are willing to spend on those diminishing returns. I am shooting for STC67 for walls and STC56 for ceilings. Unless you are building a concrete bunker with 1 foot thick walls you aren't really going to be soundproof. With that said, are you treating all walls, ceiling, floors etc?
> 
> 
> 
> With that said, I can give you some of the prices that I am paying/have paid for my 2600 cu ft room.
> 
> (I will be giving estimates of just the room in question, as I finished an entire basement)
> 
> Built wall within wall/framer *$2500-$3000* in constructing new wall in basement and included covering an exsting window.
> 
> Soundproofing company clips, brackets green glue, *$1500.*
> 
> 2 layers of 5/8 inch drywall x 50 sheets. *$750-900*
> 
> Labor for clips, channel, double drywall + green glue installation. I was quoted $30-55 a sheet with my contractor. *$1500-2500*.
> 
> I am building my own backer boxes to enclose recessed lighting, in wall speakers etc., If you want to hire someone for that, expect *$50* a box, or buy them onlne for around *$60*.
> 
> I am not listing any floor treatments, because I am not needing any, other than padding and carpet.
> 
> HVAC is really hard to price out. It depends on what you are looking for.
> 
> Of course prices may vary depending on location and the contractor hired.
> 
> Hope this helps.



that's a crazy good price.... i'm finishing a basement too... and just for the "additional" work for soundproofing purposes you detailed out, and a room about double that size, add a zero to the end of your total... so, now i'm doing it myself... 

i'm guessing you found a contractor that wasn't scared of the job/had some familiarity... all of mine gave me prices in the... "i don't want your job, but if you pay me an insane amount of money i'll do anything" realm...


----------



## jcr159

Harkon said:


> *Has anyone produced data showing the STC rating for a 2", 3" and 4" wall cavity?
> 
> I'd like to make an informed choice on what size timbers (or steel stud work) to spec, considering sound proofing vs maximising room dimensions.*
> 
> Inside the room I plan to have stud work completely isolated from the walls brick/block walls.
> 
> My original plan was to use 2x4 studs, so 4" of fluffy insulation, and about 3/4" gap from stud work to the brick/concrete walls.
> 
> If I use smaller stud work framing (probably steel) but still use the same 2 layers of plasterboard (same mass), how far does this reduce the effectiveness of the wall?
> 
> All four walls are already brick or block (1 wall is 4" thick, the other 3 are exterior walls and 12" thick) so don't want to lose more space than I need to if the concrete will help with some of the Low Frequency anyway.


since you are physically decoupling your interior walls from the structural walls, it essentially won't matter, the decoupling is the primary factor here... though i'd be leery of 2"... most electrical stuff won't fit inside a wall cavity that small...


----------



## Ladeback

jcr159 said:


> since you are physically decoupling your interior walls from the structural walls, it essentially won't matter, the decoupling is the primary factor here... though i'd be leery of 2"... most electrical stuff won't fit inside a wall cavity that small...


I think the thinnest pink fluffy is 3" thick, so I wouldn't go much thinner than that. You could probably get by with a 1/2" air gap.


----------



## Harkon

Got concerns about creating a Three leaf wall.

The one wall in room will made up like this:

Plaster Skim
Drywall
Drywall
2x4" stud on 24" centres + insulation
Air gap
Concrete block wall
Drywall
Skim

I don't know if I'm over thinking things but that is technically a 3 leaf wall. There's the main planned air gap before the block wall but then another tiny air gap behind the finishing drywall on the other side of the drywall. It will only be less than 10mm thick, as drywall will be fixed on with dots of adhesive but is that going to cause problems?


----------



## warwwolf7

Harkon said:


> Got concerns about creating a Three leaf wall.
> 
> The one wall in room will made up like this:
> 
> Plaster Skim
> Drywall
> Drywall
> 2x4" stud on 24" centres + insulation
> Air gap
> Concrete block wall
> Drywall
> Skim
> 
> I don't know if I'm over thinking things but that is technically a 3 leaf wall. There's the main planned air gap before the block wall but then another tiny air gap behind the finishing drywall on the other side of the drywall. It will only be less than 10mm thick, as drywall will be fixed on with dots of adhesive but is that going to cause problems?


I see no problem and only 2 leafs. 

Plaster Skim
Drywall (1rst leaf) 
Drywall (1rst leaf) 
2x4" stud on 24" centres + insulation
Air gap
Concrete block wall (2nd leaf) 
Drywall (2nd leaf) 
Skim


Triple leaf would be if you put drywall on both side of your 2x4 wall. 

Enjoy 



Envoyé de mon LG-H873 en utilisant Tapatalk


----------



## gimmepilotwings

jcr159 said:


> that's a crazy good price.... i'm finishing a basement too... and just for the "additional" work for soundproofing purposes you detailed out, and a room about double that size, add a zero to the end of your total... so, now i'm doing it myself...
> 
> i'm guessing you found a contractor that wasn't scared of the job/had some familiarity... all of mine gave me prices in the... "i don't want your job, but if you pay me an insane amount of money i'll do anything" realm...


Yep, my contractor has installed hat channel before, which is good. Although I will be doing that here myself. (on the walls, it isn't that hard to make sure it is in a straight line) My theater is a bit on hold though. I am trying to finish other parts of the basement first.


----------



## b_scott

gimmepilotwings said:


> Yep, my contractor has installed hat channel before, which is good. Although I will be doing that here myself. (on the walls, it isn't that hard to make sure it is in a straight line) My theater is a bit on hold though. I am trying to finish other parts of the basement first.


I just called someone to come and give an estimate on taping/mudding my drywall. I told him I have hat channel and clips in the ceiling, and he said "what?" I repeated, and he said "oh, J channel?" No.


----------



## gimmepilotwings

b_scott said:


> I just called someone to come and give an estimate on taping/mudding my drywall. I told him I have hat channel and clips in the ceiling, and he said "what?" I repeated, and he said "oh, J channel?" No.


Sigh. Although, why would they need to know about hat channel and clips if they are just taping/mudding?


----------



## b_scott

gimmepilotwings said:


> b_scott said:
> 
> 
> 
> I just called someone to come and give an estimate on taping/mudding my drywall. I told him I have hat channel and clips in the ceiling, and he said "what?" I repeated, and he said "oh, J channel?" No.
> 
> 
> 
> Sigh. Although, why would they need to know about hat channel and clips if they are just taping/mudding?
Click to expand...

He changed tone when I said I built the room and said we would probably have to tear out spots and fix them. Which sounded pretty insulting when he didn’t know me. And the fact that he is a contractor and doesn’t know what that is.


----------



## gimmepilotwings

b_scott said:


> He changed tone when I said I built the room and said we would probably have to tear out spots and fix them. Which sounded pretty insulting when he didn’t know me. And the fact that he is a contractor and doesn’t know what that is.


I definitely wouldn't use them.


----------



## b_scott

gimmepilotwings said:


> b_scott said:
> 
> 
> 
> He changed tone when I said I built the room and said we would probably have to tear out spots and fix them. Which sounded pretty insulting when he didnâ€™️t know me. And the fact that he is a contractor and doesnâ€™️t know what that is.
> 
> 
> 
> I definitely wouldn't use them.
Click to expand...

Yeah I plan on using him as an estimate so I have an idea on cost vs others. But I don’t see me hiring him.


----------



## pkinneb

If your drywall is done and sealed up It shouldn't matter...but I would want to make sure they understand what you did with the clips and channel so they understand its not a normal setup underneath just in case they start throwing extra screws up there.


----------



## warwwolf7

pkinneb said:


> If your drywall is done and sealed up It shouldn't matter...but I would want to make sure they understand what you did with the clips and channel so they understand its not a normal setup underneath just in case they start throwing extra screws up there.


That's such a good point. You don't want anyone to mess with the drywall once it's installed. Mud and tape ON TOP but don't let them modify the drywall 

Envoyé de mon LG-H873 en utilisant Tapatalk


----------



## b_scott

warwwolf7 said:


> That's such a good point. You don't want anyone to mess with the drywall once it's installed. Mud and tape ON TOP but don't let them modify the drywall
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


Yes that's my thought too. Fill in gaps where needed but the drywall is solid. I cut around areas so that I was using the most continuous panels possible, least seams.


----------



## Peterl944

*Speaker Backer Boxes*

Has anyone ever built speaker backer boxes and just glued them in place on the top piece of drywall, then put it up in place as one unit? Seems a lot easier than a separately suspended box. I would add more clips in the area around it. But, maybe the weight would still be too much?


----------



## Snoochers

Let’s assume I’m starting with a basement foundation wall. How much wall thickness room is needed to create a finished and sound isolated Theatre room? Something that’s well sound isolated. I’m referring to the thickness of the 2x4s and drywall etc.


----------



## Ladeback

Snoochers said:


> Let’s assume I’m starting with a basement foundation wall. How much wall thickness room is needed to create a finished and sound isolated Theatre room? Something that’s well sound isolated. I’m referring to the thickness of the 2x4s and drywall etc.


What part of the world are you in? I am in the midwest, so I am putting up 1" of foam insulation, with 1" air gap, then 2x4 stud will. That's just general wall construction in our area for a basement. If you want to do soundproofing you could decouple the walls with IB-3 clips or clips and hat channel. Then 2 layers of Type x 5/8" drywall with Green Glue between the layers. If do this with the IB-3 clips you are looking at around 6.75" to 7" from the foundation wall lost. If you do the clips and channel you will about about 1 1/4" or so. 

Check out Soundproofingcompany.com for more information.


----------



## jcr159

Ladeback said:


> What part of the world are you in? I am in the midwest, so I am putting up 1" of foam insulation, with 1" air gap, then 2x4 stud will. That's just general wall construction in our area for a basement. If you want to do soundproofing you could decouple the walls with IB-3 clips or clips and hat channel. Then 2 layers of Type x 5/8" drywall with Green Glue between the layers. If do this with the IB-3 clips you are looking at around 6.75" to 7" from the foundation wall lost. If you do the clips and channel you will about about 1 1/4" or so.
> 
> Check out Soundproofingcompany.com for more information.


here a bit further north, i'm doing 2 in of foam insulation, 2x4 in front of that... fill with pink fluffy.

it's possible to do the ceiling and walls such that the ceiling is contiguous and sealed, but the walls don't need double drywall because that seal is kept on the ceiling... you essentially do the ceiling first, then drywall with double/gg... then the top plate of the wall is attached to the ceiling with IB3...


----------



## Snoochers

Ladeback said:


> What part of the world are you in? I am in the midwest, so I am putting up 1" of foam insulation, with 1" air gap, then 2x4 stud will. That's just general wall construction in our area for a basement. If you want to do soundproofing you could decouple the walls with IB-3 clips or clips and hat channel. Then 2 layers of Type x 5/8" drywall with Green Glue between the layers. If do this with the IB-3 clips you are looking at around 6.75" to 7" from the foundation wall lost. If you do the clips and channel you will about about 1 1/4" or so.
> 
> Check out Soundproofingcompany.com for more information.


Thanks man. I'm actually being super conservative in the end and say that it will all take 10" from foundation wall. So that is 10+10(insulation for two sides)+125"(four theatre seats with loveseat)+30+30(aisles)= 17', which is the width of the foundation pour. Cutting it a bit close but I think it is ok.


----------



## PersistentGroove

jcr159 said:


> As an aside, I’m trying a new product from isostore for my new build... should be interesting if it works well... I’ll be able to use a combination of slightly different techniques than with hat and channel... the channel ends up being furring strips... it’s also slightly cheaper when ordering bulk from them too... anyway, good luck!
> 
> https://isostore.com/hushframe-raft-connector.html


Hello!
Thanks for this link. I'm about a month or two out from needing to buy the clips & channel to put up the ceiling and these seem interesting. Would you mind posting about your experience?

Thanks!


----------



## jcr159

PersistentGroove said:


> Hello!
> Thanks for this link. I'm about a month or two out from needing to buy the clips & channel to put up the ceiling and these seem interesting. Would you mind posting about your experience?
> 
> Thanks!


I will do that shortly! I should be installing this weekend or next depending on how work goes... full steam ahead for me currently with work, so not a lot of time to make progress.... the shipment and ordering was great, and the customer quality seems good so far... I ordered 325 of them for my roughly 750 sq. Ft basement project. I need to get a build thread going one of these days. The principle is the same as hat and clips... instead of rubber and metal channel, these are bonded with a rubbery compound... theoretically they have even more damping material between the structural element and furring strip, but the big reason I want this route was ease of installation... I can screw the right to the side of my joists to get a 1/4” gap to the drywall... to do that with hat and clips would take blocking all over the place, all cut to different lengths, etc... (joists are twisted and uneven ). I’ll get some pics as I go through it and maybe Crete a dedicated thread for these... 

I won’t be able to comment on how well they work vs hat/clips, but I’m hopeful they are “good enough” given my other compromises. 

Thanks for asking!

And the prebuilt boxes (I got 4 for atmos speakers ) are very nicely built!


----------



## mhutchins

Peterl944 said:


> Has anyone ever built speaker backer boxes and just glued them in place on the top piece of drywall, then put it up in place as one unit? Seems a lot easier than a separately suspended box. I would add more clips in the area around it. But, maybe the weight would still be too much?


A quick, back of the napkin calculation shows a 12"x12"x6" deep backer box with 2 layers of plywood or drywall will weigh about 13-15Lbs. On a ceiling, drywall screws are spaced 12" apart when they go into studs, so each screw is supporting about 2Lbs. Strictly from a weight standpoint, you could make an argument for 6-8 extra screws to support the backer box weight. I think the bigger question is whether or not the extra weight will cause the drywall to sag.

It's not too hard to support your backer boxes on the back side (the side opposite from where the drywall mounts) of the hat channel. That way the drywall and backer box will move together and you will not have to worry about sag or screws pulling out. I'm not sure if screw spacing is different when you are screwing into 25g hat channel.

Mike


----------



## Peterl944

mhutchins said:


> A quick, back of the napkin calculation shows a 12"x12"x6" deep backer box with 2 layers of plywood or drywall will weigh about 13-15Lbs. On a ceiling, drywall screws are spaced 12" apart when they go into studs, so each screw is supporting about 2Lbs. Strictly from a weight standpoint, you could make an argument for 6-8 extra screws to support the backer box weight. I think the bigger question is whether or not the extra weight will cause the drywall to sag.
> 
> It's not too hard to support your backer boxes on the back side (the side opposite from where the drywall mounts) of the hat channel. That way the drywall and backer box will move together and you will not have to worry about sag or screws pulling out. I'm not sure if screw spacing is different when you are screwing into 25g hat channel.
> 
> Mike





Yeah it might be more trouble than it's worth... getting it aligned right, and making sure you catch enough near by hat channel to add extra screws. 



You're right, the easiest thing is to just bridge the top of the hat channel, but my problem is I am going to be recessing my clips and running the channel parallel to my joists. I am trying to lose as little ceiling height as possible. First layer of DW will only be about .300" below the original joists. 



I've come up with a way to mount the boxes. It can be done with an RS1c type bracket, but they're expensive and clunky. I am going to use small rubber isolation mounts mounted on right angle brackets. See my models attached. If anyone would like more details on this let me know. It works out a lot cheaper and I think a lot cleaner than using an RS1cDC04 type bracket.


In my situation, I am actually going to combine my speaker backer box and recessed light. Placement for me at least will work out ok, and I only have to mount 4 boxes.


----------



## mhutchins

Hey Peter,

Take a look at this post. It shows an alternate mounting method for backer boxes that may work for you.

Mike


----------



## Harkon

Has anyone got a link to construct the backer boxes? Been through a few threads tonight but not found anything yet. Seen the one of Bigs resting on the channel.


----------



## Peterl944

mhutchins said:


> Hey Peter,
> 
> Take a look at this post. It shows an alternate mounting method for backer boxes that may work for you.
> 
> Mike



Thanks Mike. That does seem like a good way to do it. I already ordered all the parts like I laid out, hopefully it works out.


----------



## Peterl944

Harkon said:


> Has anyone got a link to construct the backer boxes? Been through a few threads tonight but not found anything yet. Seen the one of Bigs resting on the channel.



Here is soundproofing company's write up. https://www.soundproofingcompany.com/wp-content/uploads/2011/06/CIM-backer-box-installation-web.pdf


They do OSB with cement board, GG in between. I suppose for fire code with can lights.


I'm doing MDF with 5/8DW, with GG. I figure the DW is fire rated, and I've seen others do it like this. I also feel like mdf with DW is denser for better soundproofing, that's just a guess though.


----------



## Jrsred10

*double drywall + GG between the joist*

Need some opinions on drywall between the joist in a room that is not going to be decoupled due to space limitation. All walls will just be double drywall and GG but the designer did mention i could do drywall between the joist for help with noise from the kitchen above. Should I be concerned about the weight of the drywall causing possible sag? Is it worth the effort? The kitchen is overhead but most of the time when watching movies nobody will be in there. When they are, its loud.
Thanks foe any recommendations.
john


----------



## b_scott

I feel like one layer and decoupling is better than two layers and no decoupling. Considering most of the sound transfer is through vibrations, which will be directly from the drywall to the joist to the upper floor. But i'll let sound masters jump in.


----------



## Jrsred10

b_scott said:


> I feel like one layer and decoupling is better than two layers and no decoupling. Considering most of the sound transfer is through vibrations, which will be directly from the drywall to the joist to the upper floor. But i'll let sound masters jump in.


Thanks for sharing!


----------



## Ladeback

b_scott said:


> I feel like one layer and decoupling is better than two layers and no decoupling. Considering most of the sound transfer is through vibrations, which will be directly from the drywall to the joist to the upper floor. But i'll let sound masters jump in.


I asked this question to the Soundproofing Company: "I was thinking of decoupling the walls with IB-3 clips and using clips and channel on the ceiling with two layers of 5/8" drywall. NO GREEN GLUE. Would be decoupling and adding the second layer of drywall help without the Green Glue? Or should I just build it like a normal room with one layer of 5/8" drywall. Trying to save where I can."

They recommend that if you're on a budget, just stick with fiberglass insulation and double 5/8" Type X drywall. If you skip the Green Glue, I'd skip the clips also. 

So I am leaning toward just using two layers of 5/8" Type X drywall. The extra mass in the second layer will help more then the decoupling. Guess it depends on your budget. By skipping Green Glue and clips/channel I can put the money towards other things.


----------



## b_scott

I was more concerned with footfall above, which the clips reduce greatly. So that's why I did clips and one layer. clips and two layers would have made the ceiling too low for me.


----------



## Jrsred10

b_scott said:


> I was more concerned with footfall above, which the clips reduce greatly. So that's why I did clips and one layer. clips and two layers would have made the ceiling too low for me.


How much height did you reduce with the clips and one layer?
I also really want to know if the double drywall between the hoist is worth it?


----------



## b_scott

Jrsred10 said:


> b_scott said:
> 
> 
> 
> I was more concerned with footfall above, which the clips reduce greatly. So that's why I did clips and one layer. clips and two layers would have made the ceiling too low for me.
> 
> 
> 
> How much height did you reduce with the clips and one layer?
> I also really want to know if the double drywall between the hoist is worth it?
Click to expand...

I mean 5/8” plus GG. But my ceiling is super low and I can’t afford much.


----------



## pkinneb

Jrsred10 said:


> How much height did you reduce with the clips and one layer?
> I also really want to know if the double drywall between the hoist is worth it?


There are ways to reduce the height loss by going between the joists more work but it can be done. If you go fully under the joist you are looking at about 3" with clips, channel, and 2 layers of 5/8" drywall.

Re DD between the joists I will share my experience. I did not do this and in my scenario, the theater is under the mstr bath/closet not a huge deal. Having said that you can faintly hear foot fall from the bathroom tile floor. Knowing this if the theater is going to be under a high traffic area that has, or will have, tile/hardwood, etc I would seriously consider doing it. If I had to do over I would have done it.


----------



## Jrsred10

pkinneb said:


> There are ways to reduce the height loss by going between the joists more work but it can be done. If you go fully under the joist you are looking at about 3" with clips, channel, and 2 layers of 5/8" drywall.
> 
> Re DD between the joists I will share my experience. I did not do this and in my scenario, the theater is under the mstr bath/closet not a huge deal. Having said that you can faintly hear foot fall from the bathroom tile floor. Knowing this if the theater is going to be under a high traffic area that has, or will have, tile/hardwood, etc I would seriously consider doing it. If I had to do over I would have done it.


Thanks! Looks like ill be doing it.


----------



## Scott May

*drywall in stud cavity to add mass?*

Hi y'all,
I'm soundproofing what was formerly a garage space. The exterior wall has cedar plank on the outside face, so doing double drywall isn't an option as its outdoors. 

What I'm wondering is if I could add a layer of 5/8" drywall in between the studs inside the cavity? Then I'd put in the insulation and add isolation clips/hat channel, 2 layers of 5/8" drywall with green glue for the wall inside the room. 

Is there any reason this would be a bad idea? I'd lose a little bit of the air space in the cavity, but would still have about 4" between the inner and outer drywall layers. 

Any other ideas how to add mass on that outside wall? The room isn't really big enough for double stud. 

Thanks!


----------



## jcr159

Scott May said:


> Hi y'all,
> I'm soundproofing what was formerly a garage space. The exterior wall has cedar plank on the outside face, so doing double drywall isn't an option as its outdoors.
> 
> What I'm wondering is if I could add a layer of 5/8" drywall in between the studs inside the cavity? Then I'd put in the insulation and add isolation clips/hat channel, 2 layers of 5/8" drywall with green glue for the wall inside the room.
> 
> Is there any reason this would be a bad idea? I'd lose a little bit of the air space in the cavity, but would still have about 4" between the inner and outer drywall layers.
> 
> Any other ideas how to add mass on that outside wall? The room isn't really big enough for double stud.
> 
> Thanks!


With you total plans for the space which includes decoupling, damping and added mass on the inside, I don’t think you’d get a lot of benefits, if any...

But I wouldn’t do it for another reason... the surface in contact with the outside is a thermal bridge... this will transfer heat and cold, but the cold is most concerning and will likely give an avenue for condensation to for on the drywall... drywall isn’t good when it gets damp and will mold, etc....


----------



## mkiv808

So, I finished my theater but the door is still a weak point. 

The door is solid core. Fairy hefty. 

I tried a rubber seal around the jamb but the door wouldn’t close without rubbing and damaging the paint. 

Not sure what to try next. Some of the automatic door thresholds are really ugly. 

Is there a simple solution that just sticks onto the bottom of the door I could use temporarily?


----------



## Scott May

jcr159 said:


> With you total plans for the space which includes decoupling, damping and added mass on the inside, I don’t think you’d get a lot of benefits, if any...
> 
> But I wouldn’t do it for another reason... the surface in contact with the outside is a thermal bridge... this will transfer heat and cold, but the cold is most concerning and will likely give an avenue for condensation to for on the drywall... drywall isn’t good when it gets damp and will mold, etc....


Thanks JCR. I hadn't considered that. glad I asked. Would you think something like MDF or Plywood would be a better choice? Or would you tend to stick with the fact that you don't think it's necessary to add any additional mass at all?

I'm just paranoid that once that inner wall construction with clips/double drywall is up I'll be disappointed with the STC and won't be able to turn back.


----------



## jcr159

Scott May said:


> Thanks JCR. I hadn't considered that. glad I asked. Would you think something like MDF or Plywood would be a better choice? Or would you tend to stick with the fact that you don't think it's necessary to add any additional mass at all?
> 
> I'm just paranoid that once that inner wall construction with clips/double drywall is up I'll be disappointed with the STC and won't be able to turn back.


I’d be more paranoid about the mold to be honest... you should probably do a quick search on energy vanguard and green building advisor... I don’t have links handy, but I’d probably insulate a lot like a basement... solid XP’s foam board like foamular against the wood, then fill the remainder with fluffy stuff... or do a spray foam that creates a vapor barrier...

That barrier should be on the outside wall in cold climates, read that as on the outside of the sheathing like zip system. But that isn’t likely the case for ya so you get as close as you can. 

All that said, the little benefits would probably be negated by any flanking so I wouldn’t worry...

This stuff makes me neurotic, lol! Too much to think about!


----------



## listenn

*STC Rating question*

Hi, im new to STC rating and trying to understand it. I have read some of the fourm and sound proofing 101; couple of questions:

1. I found this site (commercial-acoustics.com/soundproofing-calculator) is this STC rating pretty close to the real one(assuming everything was done right)?
2. Lets say you have 10'x10' box with 7'x3' door with good weather proofing. Staggered framing 12 o.c(24 on each side) with (1) 5/8 drywall inside and (1) 7/16in or 1/2in OSB on the ouside. What kind of rating to expected?


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## mhutchins

1. I tried the calculator you linked. The results seemed a little lower than expected, but that is probably real life....
2. The STC will be determined by the door, as that is always the weak link.

STC does not consider low frequency sound below 125Hz. Low frequency sound is very difficult to contain.

Mike


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## LDBaha

Hi guys. I have a soundproofing question and I figured this is the right place to ask!

I have (very) small dedicated theater room (very small 11x12) (see attached). For 2 years I never had an issue with my neighbors because we wouldn't watch movies late at night and only during the day. Because of the pandemic my neighbor is now working from home and she's complaining that the subwoofer is 'distracting' - she's annoying but not a total B**** so we asked her to let us know what was "tolerable" and this was volume at -10db on my AVR (I also moved the sub away from a corner and closer to the seats).

Her house is about 7' away from mine (yeah it sucks)

I was a total newb when I built this room and I had no idea a real (new) subwoofer would be so powerful. I had no idea sound would travel so easily to my neighbors. If I could do it again I would've not picked this room for a theater room. 

_note: My plan is to build a dedicated theater in my garage but it'll be quite sometime before I can do that. 
_
*The Plan: 
*I don't want to invest much on this because it would only be "temporary"

Not sure if this would work so that's why I am here. Here's a quick draft of my bedroom and neighbors house.
Above the room is my house attic. The sound could be escaping from there but I really doubt it. 

*I was wondering if I build 2 additional walls separated from current walls by a small gap with double 5/8 drywall and green glue. If that would be sufficient to stop some of the low frequencies? (See sketch attached) 
*
Maybe I can add some bass traps in the corners?
Could I also raise my Sub on cinder blocks to stop the floor from vibrating? 


I don't care if the room is 100% soundproof in my house. I just want to be able to play my movies (with sub) during the day at around -1db of volume and she can say that's 'tolerable' or inaudible (to her) at -10db.

_Note: neighbor claims she can't hear anything else other than the subwoofer. At the loudest volume she claims to only hear the explosions or the bass from the movies. "when it gets louder than that. It's not the noise, it's the heavy bass that carries"_

Thanks to everyone in advance for the help


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## Harkon

Are your neighbours detached from you?


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## mhutchins

Mass is key for the low frequencies. You need to think in terms of 3-4 layers of 5/8" Type-X and even then, you may only see 20-30dB of attenuation.

Mike


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## LDBaha

Harkon said:


> Are your neighbours detached from you?


Correct. These are family homes (not townhomes) so we are detached but houses are close to each other - I just measured it. It's 10 ft apart 
The thing is they're bedroom (I didn't know this) is right parallel to my small theater (not the wall with the window but the wall that has the TV). 



mhutchins said:


> Mass is key for the low frequencies. You need to think in terms of 3-4 layers of 5/8" Type-X and even then, you may only see 20-30dB of attenuation.
> Mike


Interesting. Should I do another layer of drywall+GG on the current existing wall and then 2 more with GG on the new wall? that would be 2 walls with layers of drywall on the wall directly 
I am also building the second wall to block the window side.

I'm just trying to figure out if the whole thing is worth it with only spending a few hundred $. I don't want to go all out on this bedroom because that's the plan for the garage on the following years.


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## mhutchins

Just the opposite, in fact. You want to *remove* the drywall from the existing wall as that creates what is known as a "Triple Leaf" effect which can actually *diminish* your sound isolation. Instead, add drywall between the studs onto the interior surface of the outer wall exterior sheathing to increase the mass of the outer "leaf". Fill both stud bays with insulation and you will have a proper double wall. 

The only thing is, your new inner walls need to be "decoupled" from the floor and ceiling, to minimize flanking paths that can re-energize the outer wall causing it to behave like a subwoofer. Lastly, you probably need to add some mass to the ceiling with a layer or two of drywall and Green Glue.

Mike


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## LDBaha

mhutchins said:


> Just the opposite, in fact. You want to *remove* the drywall from the existing wall as that creates what is known as a "Triple Leaf" effect which can actually *diminish* your sound isolation. Instead, add drywall between the studs onto the interior surface of the outer wall exterior sheathing to increase the mass of the outer "leaf". Fill both stud bays with insulation and you will have a proper double wall.
> 
> The only thing is, your new inner walls need to be "decoupled" from the floor and ceiling, to minimize flanking paths that can re-energize the outer wall causing it to behave like a subwoofer. Lastly, you probably need to add some mass to the ceiling with a layer or two of drywall and Green Glue.
> 
> Mike


Thanks for the help Mike.

I could remove the drywall from my current wall but not add to the outside layer since that would be the outside part of the house and it's on a second floor. (note: I'm not sure if it's a structural wall so I'd rather not mess with it lol)

_Edit: I guess I could add drywall sheets between the current studs it wouldn't be perfect but it's something to beef up that wall.
_
I could however build a second wall in front of it like you said. How would I decouple the wall from the floor? I could decouple the walls from side walls/ceiling using IB-3 brackets. 

I was trying to avoid adding drywall to the ceiling but that wouldn't be that much extra work anyway


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## mhutchins

The Soundproofing Company has a lot of good information:










Imagine the above picture is a wall with the joists vertical and the channel horizontal. Instead of the I-beam stye joists, imagine the 2x4s in your wall. See how the drywall is cut to fit between the studs on the inside of the wall? That is what I was trying to describe in my post above. In fact, a wall and ceiling like this is probably the best bet for your situation.

Mike


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## jcr159

Follow Mike’s advice... avoid a triple leaf..

If I were you... I’d go simple... if you are getting -10 dB as tolerable... you probably won’t get too much louder inside before it’s tolerable for yourself... I’d get green glue, and follow the 2 tubes per sheet recommendation. I’d either add another sheet of the heaviest stuff I could on your existing walls, or... add two layers of half inch drywall with GG to your existing walls.. it would be easier (maybe) than tearing out and doing hat channel for decoupling, and wouldn’t work as well... but.. it might be good enough to bump your master volume another 3-7 dB... (maybe more)


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## Wolf911

I was looking for some advise from the sound experts here on whether they thought I would need clips and hat channel on the inner walls and ceiling in this media room im building in my garage. I built a new inner 2x4 wall 3" off the 2x6 structural garage wall. The inner walls support the ceiling inner trusses pictured. The inner walls and the inner ceiling do not touch the outer structure anywhere except thru the ib3 clips you can see in the pictures. There is 2 layers of 3/4" osb and one layer of 5/8" drywall with GG on top of the truses which is about 30" below the original garage ceiling (pictured storage space above trusses)
Now my question is are the walls and ceiling decoupled or just considered disconnected from the structure? Do I need to still use clips and hat channel on the walls or ceiling? 
My thoughts are the ceiling needs clips and hat channel because there is sheet material on the top of the trusses and any sound hitting that will travel right thru the trusses to the interior if no clips,hat channel is used. On the wall I'm not certain if clips and hat channel is needed because there is no sheet material on the other side of the studs so no sound should travel thru to the inner drywall. Although I'm wondering if the sound traveling thru the trusses where they sit on the top plate will go down into the wall studs and travel into the inner drywall, so maybe clips and hat channel is needed on the walls also.
Any advise or opinions would be appreciated . I plan on three layers of sheet material on the ceiling(osb,drywall) and three on the walls unless I need clips ,hat channel on the walls then ill use only two layers on the walls. 
I'm just trying to get the most sound isolation I can from the point I'm at now going forward. Thanks 
If this isn't the right place for this question please advise on where I could post it


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## mkiv808

mkiv808 said:


> So, I finished my theater but the door is still a weak point.
> 
> The door is solid core. Fairy hefty.
> 
> I tried a rubber seal around the jamb but the door wouldn’t close without rubbing and damaging the paint.
> 
> Not sure what to try next. Some of the automatic door thresholds are really ugly.
> 
> Is there a simple solution that just sticks onto the bottom of the door I could use temporarily?



Bumping this to see if anyone has suggestions. Thanks!


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## warwwolf7

mkiv808 said:


> Bumping this to see if anyone has suggestions. Thanks!


Try with pictures, it will catch the attention for sure 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## warwwolf7

Wolf911 said:


> I was looking for some advise from the sound experts here on whether they thought I would need clips and hat channel on the inner walls and ceiling in this media room im building in my garage. I built a new inner 2x4 wall 3" off the 2x6 structural garage wall. The inner walls support the ceiling inner trusses pictured. The inner walls and the inner ceiling do not touch the outer structure anywhere except thru the ib3 clips you can see in the pictures. There is 2 layers of 3/4" osb and one layer of 5/8" drywall with GG on top of the truses which is about 30" below the original garage ceiling (pictured storage space above trusses)
> Now my question is are the walls and ceiling decoupled or just considered disconnected from the structure? Do I need to still use clips and hat channel on the walls or ceiling?
> My thoughts are the ceiling needs clips and hat channel because there is sheet material on the top of the trusses and any sound hitting that will travel right thru the trusses to the interior if no clips,hat channel is used. On the wall I'm not certain if clips and hat channel is needed because there is no sheet material on the other side of the studs so no sound should travel thru to the inner drywall. Although I'm wondering if the sound traveling thru the trusses where they sit on the top plate will go down into the wall studs and travel into the inner drywall, so maybe clips and hat channel is needed on the walls also.
> Any advise or opinions would be appreciated . I plan on three layers of sheet material on the ceiling(osb,drywall) and three on the walls unless I need clips ,hat channel on the walls then ill use only two layers on the walls.
> I'm just trying to get the most sound isolation I can from the point I'm at now going forward. Thanks
> If this isn't the right place for this question please advise on where I could post it


Hi
I would like to know why was the plywood and drywall installed on top the trusses? However, as long as they are sealing completely your ceiling and touching (not touching, but very closed and sealed with acoustic sealant) your exterior walls that should be fine like that and consider your ceiling done. If you add a solid layer under the trusses, you will put yourself into the tripleleaf situation. I suggest you read on this and define if you have a triple leaf situation or not. Does the storage area filled with stuff going to reverse the effects of the triple leaf. I don't know. Maybe the height of the storage can reduce this effect. I don't have that answer. Then decide whether you want to add a solid layer underneath. I would not. You can install some stretched material and hide cables there and recessed light. Really nice situation you got there. Most people have their ht a basement, so there is a room above and would have to rip the floor in order to have your triple layer. You, correct me if I'm wrong, but you have a solid layer a feet or two above the trusses? 
Wait a second, is there a cavity above the original garage ceiling?
Ht - trusses - dw - osb - osb - air - orignal garage ceiling - insulation - plywood - roofing?
That's already a triple leaf. Get back to us about that. I would have to read the article about triple leaf again to give you better insight, but I'm sure more educated forum members could help you on this better than me. I'm just opening the discussion. 


Let's move on to the wall. Since you are using ib-3, you don't need hat and channel for your drywall. You can, but they are providing the same benefit so using them both instead of just ib3 won't benefit you much. I mean very little.
However, you will want your drywall to go up to the ceiling, otherwise they are useless. So that means, if you don't add layers under your trusses, you will need to install your wall's drywall between your trusses so that the walls are completely sealed. I hope you like to apply acoustic sealant, because you will need to apply around all those cutout sections. You will need to make a full sealed room. Because you created a room within a room(that's a really good start) You need to seal that room completely. If you finally decide to add solid layers under the trusses you won't have to cut all of the sections to fill between the trusses to extend the wall layers up to the ceiling.
For your walls
Do you have
Ht - (solid layers to be decided) - 2x4 - 2x6 (insulation) - plywood - outside wall brick or other wall siding
OR
Ht - (solid layers tbd) - 2x4 - drywall - 2x6 (insulation) - plywood - outside brick or other siding

Because ideally, that's what I would do

Ht - 2 or 3 layer with or without Gg - 2x4 with insulation - 2x6 with insulation - plywood - brick or siding

On your outside walls, the inside layers has to go. Triple leaf effect here again. 
(I can't look at your pictures while replying on my phone. I'm sorry if it's clearly shown)


Envoyé de mon LG-H873 en utilisant Tapatalk


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## Wolf911

Thanks for the input. I'm aware of the triple leaf effect and from my understanding the ceiling does create a triple leaf but from all the info I could read I didn't have much of a choice. The original garage trusses holding that taped plywood layer you see in the storage Picture could not be loaded with any more sheet material(drywall, osb, etc) because of the dead load specs of the trusses. I had to add inside trusses to carry the weight of a loaded ceiling. The thoughts I gathered from the studio build threads was when faced with an option like that it was best to just build another two leaf ceiling below the original with a large air gap and plenty of mass. My understanding is that even tough its not ideal the results can still be pretty good. Also I couldn't see waisting the space above the trusses thus the layers added on the top. Since I'm thinking of the inside trusses with the top and bottom layers as a two leaf system thats why I thought clips and hat channel would be necessary. The way it is now seems like the same situation you'd have with a room in a basement and a main floor above it except for the size of the room above. Instead of 8ft in the room above for the air gap its 30". Of course I'm no expert maybe my assumptions are wrong.

The 2x6 garage structural walls are filled with roxul and have a sealed layer of 2" polyiso insulation over the studs then 1" gap to the interior 2x4 walls holding the inside trusses up. The walls shouldn't be triple leaf as there's nothing but insulation from the2x4 wall to the outside sheathing and steel siding. Yea that would be alot of work trying to get the triple layer drywall thru those trusses to catch the ceiling layers. im thinking inside layers on clips and channel much easier. 
My goal is to keep as much sound as I can from going up into the garage attic since I share that attic space and have noticed that sound travels easily thru that area.


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## LDBaha

mhutchins said:


> The Soundproofing Company has a lot of good information:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Imagine the above picture is a wall with the joists vertical and the channel horizontal. Instead of the I-beam stye joists, imagine the 2x4s in your wall. See how the drywall is cut to fit between the studs on the inside of the wall? That is what I was trying to describe in my post above. In fact, a wall and ceiling like this is probably the best bet for your situation.
> 
> Mike


Brilliant! That's exactly what I am going to do. Thanks for the help big time! 
I could also do this on the ceiling (from the attic) but not sure if weight of pieces of drywall would be too much - well that drywall is fixed to joists but I'm terrible at anything that has to do with construction lol


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## warwwolf7

Wolf911 said:


> Thanks for the input. I'm aware of the triple leaf effect and from my understanding the ceiling does create a triple leaf but from all the info I could read I didn't have much of a choice. The original garage trusses holding that taped plywood layer you see in the storage Picture could not be loaded with any more sheet material(drywall, osb, etc) because of the dead load specs of the trusses. I had to add inside trusses to carry the weight of a loaded ceiling. The thoughts I gathered from the studio build threads was when faced with an option like that it was best to just build another two leaf ceiling below the original with a large air gap and plenty of mass. My understanding is that even tough its not ideal the results can still be pretty good. Also I couldn't see waisting the space above the trusses thus the layers added on the top. Since I'm thinking of the inside trusses with the top and bottom layers as a two leaf system thats why I thought clips and hat channel would be necessary. The way it is now seems like the same situation you'd have with a room in a basement and a main floor above it except for the size of the room above. Instead of 8ft in the room above for the air gap its 30". Of course I'm no expert maybe my assumptions are wrong.
> 
> The 2x6 garage structural walls are filled with roxul and have a sealed layer of 2" polyiso insulation over the studs then 1" gap to the interior 2x4 walls holding the inside trusses up. The walls shouldn't be triple leaf as there's nothing but insulation from the2x4 wall to the outside sheathing and steel siding. Yea that would be alot of work trying to get the triple layer drywall thru those trusses to catch the ceiling layers. im thinking inside layers on clips and channel much easier.
> My goal is to keep as much sound as I can from going up into the garage attic since I share that attic space and have noticed that sound travels easily thru that area.


Well the clarification you are giving are pretty clear. I can only guess on the results. I would guess that overall it can be better to add a leaf under your trusses. Maybe the 30" of air is enough to remove the triple leaf effect. Although if I remember correctly, the 3leaf effect, is not incredibly bad. So it would be logical to think that 30" would actually help with the soundproofing and block the 3leafeffect. I hope it does reduce the sound enough so that it doesn't effect the neighbours. 

Look at the nrc wall stc rating irc-ir-761 pdf if you haven't. You can compare the effects of each type of layers and from there you can see the dB reduction per frequency. 

As per your walls, it all makes sense. 

Because you have built a room within a room, I don't think you need hat and channel for your ceiling and walls. It can add a little bit but I haven't found data on double wall with resilient channels. This is the only info I found which doesn't really list its reference http://johnlsayers.com/phpBB2/viewtopic.php?f=2&t=219
He basically says that it will help. If you have unlimited budget go for it. If you need to save somewhere that where you could. You said you wanted 3layers? Make sure you follow the screwing pattern because you could overload the hat and channel system. Even more important for your ceiling 



BIGmouthinDC said:


> OSB for the first layer when doing a coffered ceiling is a good idea but not mandatory. White Oaks didn't have it.
> I've done two 3 drywall layer theaters, Beast and Curve Frenzy. I think it helps but I can't give you an specific measured number. Beast actually went crazy, two layers under the subfloor and three layers hung on clips and channel. His hardwood family room was directly above.When doing three layers you space the channels 16OC versus 24OC. Same clips spacing of 48 inches.


Whatever you decide to do in your ceiling, do the same on your walls (or vice versa) otherwise the weaker of the 2 will leak into the upper layer of your new ceiling trusses. And doing more on the ceiling vs the wall will not do much because of the shared airspace between your double wall and the trusses. 

If you find anything in regard to double wall + resilient channel or hat and channel, please let me know. 


By the way, I say resilient channel because that's what they used in the nrc studies. But a lot of users of this forum recommends hat and channel and I would be one of them. 

I hope my post helps you a little bit. Good day 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## Wolf911

Thanks warwwolf7 for your insights and the link and reference. 
I do agree with you on your thoughts that clips and hat channel aren't necessary on a double wall setup (rwr) but my thought is that the ceiling with layers on top and bottom of the trusses would be considered just a standard wall with sheet material on both sides. Thus any sound hitting the top or bottom layers of the trusses would just transmit thru to the other side because they are coupled, thats why I think the clips and channel are necessary . I do think the walls are a true double wall setup and normally wouldn't require clips, hat channel but as you pointed out if I clipped the ceiling and the walls were different(not clipped) sound will still travel thru the trusses ends into the common airspace between them. Maybe you were referring to the number of layers on that point but it probably holds true for different arrangements on the ceiling vs walls also. 

Ill definitely do 16oc on the channel if I go with three layers and manufacturers screw pattern.

I'm not educated enough to know for sure on clips or no clips, so I'd rather error on the side of caution and clip everything unless someone can say for sure its not needed. I figure in the end at least ill know I did everything I could and will have to live with those results. I've done the clips and channel a few times before so no big deal. Thanks again for your insights.


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## mhutchins

With clips and channel with a first layer of OSB or plywood, it's still important to try to hit the channel with each subsequent layer. Although the pull-out strength of the OSB is probably sufficient with the correct schedule of fasteners that are all properly installed, why tempt fate. Plan to hit the channel with all of your fasteners for all your layers to maximize the strength of your connection to the channel. Be sure to use appropriate length fasteners for each layer so there is no chance of hitting the studs and ruining all your hard work to decouple the assembly.

Mike


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## Wolf911

After reading this old thread (link below) I've decided that the walls do not need clips but the ceiling does. In the thread Ted White gives a litmus test on how to determine if some assembly is decoupled. He says" if the two leafs can move independently from each other they are decoupled." So applying this to my situation the inner leaf of the walls can move independently from the exterior leaf thus the walls are decoupled but the ceiling will need clips because the outer layer of the two leaf assembly can not move independently from the inner leaf without clips. He also said in that thread it didn't matter if the joists touched the walls, acoustically they were still decoupled if the two leafs moved independently. Also I gathered from reading that its OK to have clips on ceiling and not walls and vice versa as long as all the assemblies are decoupled.

I added this post to help if someone stumbles upon this topic maybe it will help them

It wouldn't let me post the link to the old thread because I don't have enough posts but the name of the thread was "Honest opinions on soundproofing -whisper clips and hat channel worth it?"

Yes l will be very careful with three layers to hit the channel with every screw. In the past i always mark the channel placement on the wall on each end then run a string line or chaulk line so I know where to screw. Thanks for reminding me that all layers must be screwed into the channel not just into the base layer.


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## molar24

Great info everyone. This has been super helpful for us starting out. I appreciate everyone's time and effort in this forum!


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## jcr159

warwwolf7 said:


> And doing more on the ceiling vs the wall will not do much because of the shared airspace between your double wall and the trusses.


just a quick note for everyone out there...

Make sure you DON'T do this... Code requires fire blocking between the walls and adjoining spaces. You should typically use this safety requirement to create separation in the air spaces between the walls and ceiling for sound purposes as well...


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## warwwolf7

jcr159 said:


> just a quick note for everyone out there...
> 
> Make sure you DON'T do this... Code requires fire blocking between the walls and adjoining spaces. You should typically use this safety requirement to create separation in the air spaces between the walls and ceiling for sound purposes as well...


Are you saying that between the inner wall and the exterior wall there should be blocking? That would suck as it would defeat the purpose of a room within a room.

I know the codes in my area says that you need to have fire blocking within a wall when they are higher than 8'. I never read anything about "between walls".
Do you have more information on this?

Thanks 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## Wolf911

jcr159 said:


> just a quick note for everyone out there...
> 
> Make sure you DON'T do this... Code requires fire blocking between the walls and adjoining spaces. You should typically use this safety requirement to create separation in the air spaces between the walls and ceiling for sound purposes as well...


Do you have a picture of how this blocking would go on a double wall. It seems to me you would have to cut individual pieces to fit between the trusses where they meet the wall top plate and then you would have to make sure they don't short circuit the inner wall and outer wall of the double wall assembly. Just trying to understand how its done. Thanks


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## pkinneb

warwwolf7 said:


> Are you saying that between the inner wall and the exterior wall there should be blocking? That would suck as it would defeat the purpose of a room within a room.
> 
> I know the codes in my area says that you need to have fire blocking within a wall when they are higher than 8'. I never read anything about "between walls".
> Do you have more information on this?
> 
> Thanks
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


FWIW I placed Rockwool between them not wood blocking as that would defeat the purpose of room within a room. I passed inspection with no issues.


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## jcr159

See the second image in this link... he used drywall... essentially you need to block the air path from any wall cavity to the joist/ceiling cavity above. This slows fire and smoke spread. Can be done with any material pretty much... you could short the pieces and seal the gaps with fire rated sealant(fire rated foam works well) and will maintain the soundproofing...

http://www.ifinishedmybasement.com/framing-basement/fire-block/


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## Wolf911

pkinneb said:


> FWIW I placed Rockwool between them not wood blocking as that would defeat the purpose of room within a room. I passed inspection with no issues.


Thanks. Thats a good tip. Did you do the whole ceiling in rockwool for fire purposes. I love rockwool but I've read alot on sound forums and they always say its best to use the fluffy fiberglass stuff some even say do not use it it can bridge the sound connection. I have used it over the years on many projects (general construction) and think that it is superior to fiberglass as far as thermal control is concerned. I will probably use it as you described for the fireblock as putting a hard block into the cavity would be to difficult at this stage of the project. 
I looked at your theater build thread, very nice. As a guy who loves tools and building everything diy it was an inspiration.


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## Wolf911

jcr159 said:


> See the second image in this link... he used drywall... essentially you need to block the air path from any wall cavity to the joist/ceiling cavity above. This slows fire and smoke spread. Can be done with any material pretty much... you could short the pieces and seal the gaps with fire rated sealant(fire rated foam works well) and will maintain the soundproofing...
> 
> http://www.ifinishedmybasement.com/framing-basement/fire-block/


Thanks for the link and illustration. I understand the reasoning behind it and would have implemented it but at this stage it would be to difficult to do because the polyiso is against the studs already on the exterior walls and it would be a nightmare to try and cut it away to install the blocking. And even if I did cut away to the studs Id still have the exterior 2x6 wall cavity I couldn't reach to block, although those exterior walls do have fireblocking at 8ft on the 12 ft wall.


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## pkinneb

Wolf911 said:


> Thanks. Thats a good tip. Did you do the whole ceiling in rockwool for fire purposes. I love rockwool but I've read alot on sound forums and they always say its best to use the fluffy fiberglass stuff some even say do not use it it can bridge the sound connection. I have used it over the years on many projects (general construction) and think that it is superior to fiberglass as far as thermal control is concerned. I will probably use it as you described for the fireblock as putting a hard block into the cavity would be to difficult at this stage of the project.
> I looked at your theater build thread, very nice. As a guy who loves tools and building everything diy it was an inspiration.


I did not just two joist cavities to meet code. This side was three just becuase I had extra but most of the ceiling was 9" pink fluffy. Thanks for the kind words!!


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## warwwolf7

pkinneb said:


> FWIW I placed Rockwool between them not wood blocking as that would defeat the purpose of room within a room. I passed inspection with no issues.


Thanks for the pictures now I understand. The blocking at the top of the wall, not in between, but I guess this is limited by the code. Where I'm at it's 8'max between blocking.
Good to know that Roxul mineral wool works.

However, this will divide the airspace, but it's not a perfect barrier. If you have different layer material on your wall vs your ceiling, you will most likely get a result closer to you weakest link. In that case, just do both sections the same way. All that said, the concerned user answered that he will use the same layer method on the wall and ceiling

Thanks again pkinned 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## pkinneb

warwwolf7 said:


> Thanks for the pictures now I understand. The blocking at the top of the wall, not in between, but I guess this is limited by the code. Where I'm at it's 8'max between blocking.
> Good to know that Roxul mineral wool works.
> 
> However, this will divide the airspace, but it's not a perfect barrier. If you have different layer material on your wall vs your ceiling, you will most likely get a result closer to you weakest link. In that case, just do both sections the same way. All that said, the concerned user answered that he will use the same layer method on the wall and ceiling
> 
> Thanks again pkinned
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


NP. I should note that this pic was taken prior to adding r13 pink fluffy to the inside wall. In the walls I used Roxul where the stud cavities were less than 14 1/2" also of note is that while I used faced pink fluffy it was all slit so that it does not act as a vapor barrier.


----------



## Wolf911

pkinneb said:


> NP. I should note that this pic was taken prior to adding r13 pink fluffy to the inside wall. In the walls I used Roxul where the stud cavities were less than 14 1/2" also of note is that while I used faced pink fluffy it was all slit so that it does not act as a vapor barrier.


Did you countersink the screws on the osb layer into the hat channel? Did u also do a first layer of osb on the walls? You may have shown it it your build thread but I was probably distracted by the tool nirvana.


----------



## pkinneb

Wolf911 said:


> Did you countersink the screws on the osb layer into the hat channel? Did u also do a first layer of osb on the walls? You may have shown it it your build thread but I was probably distracted by the tool nirvana.


No becuase you do not want to strip the hat channel, just snug them up but don't let them spin, the drywall will cover them. RE OSB I only did the ceiling becuase of the soffits the walls are double layer 5/8 drywall with green glue and the ceiling was 5/8 OSB, 5/8 drywall, and green glue.


----------



## alangsk

pkinneb said:


> No becuase you do not want to strip the hat channel, just snug them up but don't let them spin, the drywall will cover them. RE OSB I only did the ceiling becuase of the soffits the walls are double layer 5/8 drywall with green glue and the ceiling was 5/8 OSB, 5/8 drywall, and green glue.


What screws did you use to attach the 5/8 OSB to the hat channel?


----------



## pkinneb

alangsk said:


> What screws did you use to attach the 5/8 OSB to the hat channel?


Fine thread drywall screws for metal studs.


----------



## alangsk

pkinneb said:


> Fine thread drywall screws for metal studs.



Thanks PK!

One last question, and I apologize if you already answered it, but did you pre-drill the OSB?


Sent from my iPhone using Tapatalk


----------



## pkinneb

alangsk said:


> Thanks PK!
> 
> One last question, and I apologize if you already answered it, but did you pre-drill the OSB?
> 
> 
> Sent from my iPhone using Tapatalk


No but unlike 1/2" dry wall you will not be able to pull it tight with the screws so you need it snug against the hat channel before you screw it. I used a lift so that was not an issue FWIW I found the 5/8" dry wall to be the same snug it up before you run the screw in. Final thought this was on the ceiling only my walls I did not use channels rather they are double walls so installation was the standard drywall installation.


----------



## Harkon

Two quick questions if anyone has a moment. 

My decoupled stud wall will sit on a concrete pad (ground floor). 
Is it necessary to isolate the stud work by fitting rubber or similar underneath the bottom plate? 

There will be no floating floor, the underlay and carpet will be laid straight on to the concrete so isolating the stud work seems pointless? 


Has anyone got a picture of backer rod being used to chalking corners etc? I see it mentioned a lot in Rod Gervais book (Nearly finished it) But unsure what this looks like in reality.


----------



## pkinneb

Harkon said:


> Two quick questions if anyone has a moment.
> 
> My decoupled stud wall will sit on a concrete pad (ground floor).
> Is it necessary to isolate the stud work by fitting rubber or similar underneath the bottom plate?
> 
> There will be no floating floor, the underlay and carpet will be laid straight on to the concrete so isolating the stud work seems pointless?
> 
> 
> Has anyone got a picture of backer rod being used to chalking corners etc? I see it mentioned a lot in Rod Gervais book (Nearly finished it) But unsure what this looks like in reality.


My theater is like your no floating floor but I did use Tractor supply horse stall mat under the walls per advice from my consultant. It only cost a few bucks so I figured why not










Backer rod pics


----------



## warwwolf7

*dudct going through ceiling of HT question*

Hi,
I have a quetsion regarding ducts going through the ceiling of my home theater room. Full question here (I don't want to duplicate)
https://www.avsforum.com/forum/19-d...ing-kontrol-ht-build-thread.html#post59983314


warwwolf7 said:


> Hi,
> I'll do a little introduction soon. When I have a little bit more time.
> 
> I'm in the process of redoing myself my entire ventilation(HVAC) system. Unfortunately I have 2 branches that have to go through the floor joist above the futur home theater (HT) room. The HT will be in the basement.
> 
> I went too fast and installed 6" metal round duct. I'm pretty sure that they will conduct and transmit sound more than if I used flexible duct. So after thinking about this a night, this morning I bought flexible duct in order to replace what I have.
> So the duct goes through the sidewall of the HT. That's the outside wall (2layers of 5/8 type x with GG) the drywall goes up to the underneath of the RC subfloor in between the floor joist. That where the duct enters. I plan on using metal duct there, so it's easier to seal with acoustical sealant. On either side of this short section it will be flexible duct.
> What do you think about this?
> Lets say I have 13' from where the duct goes in the sidewall of the HT to where its exits through the floor in the room above. How long do I have to have of flexible ducting? Do I have to make it the entire length? If I do only half?
> 
> Thanks,
> P. S. I know this is a rough intro, but I will do a proper one soon. I'm short on time this week. I got to get this done before I get my ac and start my new career.
> 
> 
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


----------



## AnnapolisSony

So I am placing my order for isolation clips relatively soon and long ago I had decided to go with the Resilmount A237R. I have found them online at $4.39 and I think that's as good as it is gonna get on pricing. I am sure this has been asked multiple times on this thread (and if so, please link me to post) but does anyone know of any research that shows that I am going to get _much_ better results from the rubber isolation piece on the A237R ($4.39 ea) vs. just the A237 direct fix without the rubber piece ($1.89 ea.)???? I've got the money budgeted for the A237R's but is it really going to make that much of a difference to justify the _additional_ $440 for 175 clips??? 

I should also preface this post by saying that my new room has two layers of 5/8" DW (with GG) on the exterior and I will be going two layers of 5/8" DW on walls and ceilings _inside_ as soon as I finish installing Roxul Safe-n-Sound and channel. The weakest link in the room now really is the ceiling IMO because I will only have two layers of 5/8" DW (with Roxul of course) between my HT and the ceiling/subfloor above. I should also mention that I did not decouple the walls because some were existing. Any thoughts on the clip performance would be greatly appreciated.


----------



## schwock5

there's been some posts shared earlier and i think also on soundproofingcompany.com comparing different clips and it looked fairly negligible and not worth the price, better spent elsewhere.
also the roxul wasn't much different in the wall vs pink stuff and budget better spent elsewhere


----------



## GrailWarCFB

Does anyone know the best under door noise stopper? This is what I‘ve been using, which helps but still isn’t great: 



https://www.homedepot.com/p/Frost-King-E-O-3-3-4-in-x-36-in-Brown-Double-Draft-Stop-for-Doors-or-Windows-DDS1/


----------



## PersistentGroove

jcr159 said:


> I will do that shortly! I should be installing this weekend or next depending on how work goes... full steam ahead for me currently with work, so not a lot of time to make progress....
> 
> And the prebuilt boxes (I got 4 for atmos speakers ) are very nicely built!


Howdy! I'm interested to hear if you've had the opportunity to get those isolation blocks up into your ceiling and how they worked out for you. Thanks!


----------



## jcr159

PersistentGroove said:


> Howdy! I'm interested to hear if you've had the opportunity to get those isolation blocks up into your ceiling and how they worked out for you. Thanks!


Ugh, me too! 

COVID has been in the way and stalled my progress... I have a couple weeks off later this month though and hoping that will get me over the hump. Long story short, the ceiling is complicated and needs a lot of soffit building/planning. Most of my other framing is done at this point though, so mechanicals and wiring can begin soon after. 

That said, the quality of the parts is pretty good looking. the elasomer bonding the two wood pieces together is somewhere between the consistency of dried rubber cement (something like E6000), and Dr. Marten's shoe sole material... I did just get my OmniMic from Parts express, and plan to do some measurements in the space and several places on the first floor before and after various stages as well.


----------



## jdsmoooth

Sound Proofing an Already Finished Room

Three years ago we finished our basement media room and now want to add on to it and sound proof it. 

My question is can I put a layer of MLV on the pre existing drywall, then hat channel, clips and two more layers of 5/8 and green glue. 
Then Similarly repeat the process on the walls. I oils remove all the trim and seal behind it also while doing underpayment on the floor and sealing the electrical boxes also.

Or is it best I gut to the studs? 

Thanks!


----------



## Ladeback

jdsmoooth said:


> Sound Proofing an Already Finished Room
> 
> Three years ago we finished our basement media room and now want to add on to it and sound proof it.
> 
> My question is can I put a layer of MLV on the pre existing drywall, then hat channel, clips and two more layers of 5/8 and green glue.
> Then Similarly repeat the process on the walls. I oils remove all the trim and seal behind it also while doing underpayment on the floor and sealing the electrical boxes also.
> 
> Or is it best I gut to the studs?
> 
> Thanks!


If you leave the drywall and install clips, channel and double drywall over it you are creating a triple leaf effect, which you don't want. I would go to the studs if you can. This will explain it better then I can. 








Understanding the Triple Leaf Effect and air cavity depth


The bottom line: For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key.



www.soundproofingcompany.com


----------



## queens770

Long time lurker and reader here, I've gone through much of this 178 page thread and haven't seen an exact scenario as mine. I live in a townhouse built in 1986 with below average builder grade. I have neighbors on each side of me and behind. It's a two story. I have a nice home theater-ish in my living room. looking for best solutions so I'm not a dick to my neighbors. My neighbors are awesome and rarely hear them, but I want to cut down noise from my end on movie nights. I have seen inside my walls and they are 24" OC staggered. Meaning, I have a set of 2x4's studs 24"OC and my neighbors also has 24" studs OC. Meaning they are technically 12" apart but not on the same side (if that makes sense). So basically there are 2 sets of 24" studs, they have 5/8 drywall on their side of the common wall and I have 5/8 drywall on my side. Obviously I don't turn up my stereo very loud out of respect for my neighbors but I would like to be able to turn it up a little bit more towards reference listening levels. I have planned on Roxul safe n sound, 5/8 quietrock, 1/2 dense drywall with GG sandwiched. I'll be treating both common walls and possibly ceiling as well. I've read of other methods here regarding channels and whatnot but I'm not really understanding my other options as others have talked about. This is a small townhouse so there's not a lot to treat per se, it's under 900sqft total including the upstairs. Any help would be greatly appreciated, thanks in advance.


----------



## jrref

queens770 said:


> Long time lurker and reader here, I've gone through much of this 178 page thread and haven't seen an exact scenario as mine. I live in a townhouse built in 1986 with below average builder grade. I have neighbors on each side of me and behind. It's a two story. I have a nice home theater-ish in my living room. looking for best solutions so I'm not a dick to my neighbors. My neighbors are awesome and rarely hear them, but I want to cut down noise from my end on movie nights. I have seen inside my walls and they are 24" OC staggered. Meaning, I have a set of 2x4's studs 24"OC and my neighbors also has 24" studs OC. Meaning they are technically 12" apart but not on the same side (if that makes sense). So basically there are 2 sets of 24" studs, they have 5/8 drywall on their side of the common wall and I have 5/8 drywall on my side. Obviously I don't turn up my stereo very loud out of respect for my neighbors but I would like to be able to turn it up a little bit more towards reference listening levels. I have planned on Roxul safe n sound, 5/8 quietrock, 1/2 dense drywall with GG sandwiched. I'll be treating both common walls and possibly ceiling as well. I've read of other methods here regarding channels and whatnot but I'm not really understanding my other options as others have talked about. This is a small townhouse so there's not a lot to treat per se, it's under 900sqft total including the upstairs. Any help would be greatly appreciated, thanks in advance.


I have a similar situation. No matter what you do, the bass will eventually transmit to your neighbors units via the structure of your unit as you increase your volume. The soundproofing will significantly help with all the other frequencies but don't expect to be able to turn your home theater at reference levels. You will get a significant attenuation in transmitted sound but that's about it.


----------



## queens770

jrref said:


> The soundproofing will significantly help with all the other frequencies but don't expect to be able to turn your home theater at reference levels. You will get a significant attenuation in transmitted sound but that's about it.


All the more reason to look for a single family home ha ha. I'm just trying to do all I can. Not a lot to work with though in my case.


----------



## b_scott

you may want to look into mass loaded vinyl as another barrier inside the wall.


----------



## queens770

b_scott said:


> you may want to look into mass loaded vinyl as another barrier inside the wall.


This is like a rubberized compound right? If so I've used stuff like this in my car audio days.


----------



## b_scott

queens770 said:


> This is like a rubberized compound right? If so I've used stuff like this in my car audio days.


it's basically sheets of very heavy black vinyl. Looks like a thick trash bag.


----------



## mhutchins

queens770 said:


> Long time lurker and reader here, I've gone through much of this 178 page thread and haven't seen an exact scenario as mine. I live in a townhouse built in 1986 with below average builder grade. I have neighbors on each side of me and behind. It's a two story. I have a nice home theater-ish in my living room. looking for best solutions so I'm not a dick to my neighbors. My neighbors are awesome and rarely hear them, but I want to cut down noise from my end on movie nights. I have seen inside my walls and they are 24" OC staggered. Meaning, I have a set of 2x4's studs 24"OC and my neighbors also has 24" studs OC. Meaning they are technically 12" apart but not on the same side (if that makes sense). So basically there are 2 sets of 24" studs, they have 5/8 drywall on their side of the common wall and I have 5/8 drywall on my side. Obviously I don't turn up my stereo very loud out of respect for my neighbors but I would like to be able to turn it up a little bit more towards reference listening levels. I have planned on Roxul safe n sound, 5/8 quietrock, 1/2 dense drywall with GG sandwiched. I'll be treating both common walls and possibly ceiling as well. I've read of other methods here regarding channels and whatnot but I'm not really understanding my other options as others have talked about. This is a small townhouse so there's not a lot to treat per se, it's under 900sqft total including the upstairs. Any help would be greatly appreciated, thanks in advance.


Don't forget to address all penetrations with caulk and/or putty pads. It sounds like you are removing the drywall on your side to add the rockwool insulation. While the wall is open, surround your neighbors switches and outlets with putty pads to make an air-tight seal. Do the same for your outlets and switches that are in common walls. Caulk all the joints between your new walls where they adjoin bounding edges such as floor, ceiling and adjacent walls (you might consider doing this to the backside of your neighbors walls, too). I would use 2-3 layers of 5/8" Type-X drywall with Green Glue for every common wall. Don't waste your time with 1/2" or mass loaded vinyl. You want *MASS*. Clips and channel will have some low frequency benefit, maybe as much as 5dB, but at the cost of more complexity, expense and an additional loss of space on the order of a 1-1/4" per wall.

Mike


----------



## jrref

mhutchins said:


> Don't forget to address all penetrations with caulk and/or putty pads. It sounds like you are removing the drywall on your side to add the rockwool insulation. While the wall is open, surround your neighbors switches and outlets with putty pads to make an air-tight seal. Do the same for your outlets and switches that are in common walls. Caulk all the joints between your new walls where they adjoin bounding edges such as floor, ceiling and adjacent walls (you might consider doing this to the backside of your neighbors walls, too). I would use 2-3 layers of 5/8" Type-X drywall with Green Glue for every common wall. Don't waste your time with 1/2" or mass loaded vinyl. You want *MASS*. Clips and channel will have some low frequency benefit, maybe as much as 5dB, but at the cost of more complexity, expense and an additional loss of space on the order of a 1-1/4" per wall.
> 
> Mike


But just remember at the end of the day you will be able to play your audio louder but eventually you will overcome the sound attenuation of your walls and your neighbors will start to hear everything. My Marantz has a system to attenuate the bass. You have different levels you can set. This is the only thing i've found that allows me to play my home theater louder without annoying my neighbors. The volume and frequencies of your bass are your enemy.


----------



## mkiv808

queens770 said:


> Long time lurker and reader here, I've gone through much of this 178 page thread and haven't seen an exact scenario as mine. I live in a townhouse built in 1986 with below average builder grade. I have neighbors on each side of me and behind. It's a two story. I have a nice home theater-ish in my living room. looking for best solutions so I'm not a dick to my neighbors. My neighbors are awesome and rarely hear them, but I want to cut down noise from my end on movie nights. I have seen inside my walls and they are 24" OC staggered. Meaning, I have a set of 2x4's studs 24"OC and my neighbors also has 24" studs OC. Meaning they are technically 12" apart but not on the same side (if that makes sense). So basically there are 2 sets of 24" studs, they have 5/8 drywall on their side of the common wall and I have 5/8 drywall on my side. Obviously I don't turn up my stereo very loud out of respect for my neighbors but I would like to be able to turn it up a little bit more towards reference listening levels. I have planned on Roxul safe n sound, 5/8 quietrock, 1/2 dense drywall with GG sandwiched. I'll be treating both common walls and possibly ceiling as well. I've read of other methods here regarding channels and whatnot but I'm not really understanding my other options as others have talked about. This is a small townhouse so there's not a lot to treat per se, it's under 900sqft total including the upstairs. Any help would be greatly appreciated, thanks in advance.


These are cheap and can make a big difference for the cost.









SVS SoundPath Subwoofer Isolation System


Reduce rattle and improve subwoofer bass with the SVS SoundPath Subwoofer Isolation System. Universal pad feet work with any brand or model.




www.svsound.com





I agree with others you can make a modest difference, but bass will still travel through the floor joists to the wall joists into the neighbor’s space.


----------



## queens770

mhutchins said:


> I would use 2-3 layers of 5/8" Type-X drywall with Green Glue for every common wall. Don't waste your time with 1/2" or mass loaded vinyl. You want *MASS*. Clips and channel will have some low frequency benefit, maybe as much as 5dB, but at the cost of more complexity, expense and an additional loss of space on the order of a 1-1/4" per wall.
> 
> Mike


I appreciate your response. I know I will only be able to do so much. Thank you for your reply and advice.


----------



## mkiv808

So I have an above ground slab basement with neighbors about 80’ behind me. 

They say they can hear a little bass, not too much but I feel bad. I have dual SVS cylinder subs. 

I did double drywall, green glue, clips/channel, and acoustic sealant. Even with that, should I expect that I’ll never fully contain bass? 

There’s a window and patio door on the wall facing their house. I’m guessing that’s where a lot of bass is escaping. I have heavy curtains on both but nothing more. 

Any suggestions on what I can do with those that won’t cost a fortune?


----------



## mhutchins

mkiv808 said:


> So I have an above ground slab basement with neighbors about 80’ behind me.
> 
> They say they can hear a little bass, not too much but I feel bad. I have dual SVS cylinder subs.
> 
> I did double drywall, green glue, clips/channel, and acoustic sealant. Even with that, should I expect that I’ll never fully contain bass?
> 
> There’s a window and patio door on the wall facing their house. I’m guessing that’s where a lot of bass is escaping. I have heavy curtains on both but nothing more.
> 
> Any suggestions on what I can do with those that won’t cost a fortune?



It might be worthwhile to purchase a sound level meter and measure the bass outside, especially near the two openings. Even better would be to run something like REW outside to see what frequencies are escaping. 

Then you could build a membrane absorber into the window and door plug to attenuate transmission of those frequencies, at least, I think that would work, but I am often wrong when it comes to acoustics. I modeled some membrane absorbers using Mass Loaded Vinyl and horse stall mats for the membrane and came up with these results:










Alternatively, you can build heavy, rigid plugs to fill the openings during movie time. The plugs need to be at least as massive as your walls, so double layer drywall if not triple layer.... 

Mike


----------



## blake

How much sound bleed (ex into adjacent rooms) would you experience with in-wall speakers that already have a back-box (ex M&K IW300)? Can you just insert the speakers in the joist space behind your screen (using the template to cut out the drywall) as per their instructions? Or is it preferable to make a back-box of sorts out of acoustical drywall, for the in-wall speaker to sit within (ex. sealing the wall cavity the speaker sits in) ?

Not really sure how much sound "escapes" from the sides and back of these type of speakers.


----------



## mkiv808

blake said:


> How much sound bleed (ex into adjacent rooms) would you experience with in-wall speakers that already have a back-box (ex M&K IW300)? Can you just insert the speakers in the joist space behind your screen (using the template to cut out the drywall) as per their instructions? Or is it preferable to make a back-box of sorts out of acoustical drywall, for the in-wall speaker to sit within (ex. sealing the wall cavity the speaker sits in) ?
> 
> Not really sure how much sound "escapes" from the sides and back of these type of speakers.
> 
> 
> View attachment 3034566


I can’t hear any sound escaping from my Triad speakers into other rooms.


----------



## mkiv808

mhutchins said:


> It might be worthwhile to purchase a sound level meter and measure the bass outside, especially near the two openings. Even better would be to run something like REW outside to see what frequencies are escaping.
> 
> Then you could build a membrane absorber into the window and door plug to attenuate transmission of those frequencies, at least, I think that would work, but I am often wrong when it comes to acoustics. I modeled some membrane absorbers using Mass Loaded Vinyl and horse stall mats for the membrane and came up with these results:
> 
> View attachment 3034326
> 
> 
> Alternatively, you can build heavy, rigid plugs to fill the openings during movie time. The plugs need to be at least as massive as your walls, so double layer drywall if not triple layer....
> 
> Mike


I don’t use the window or patio door at all, so it can be a semi permanent installation. Of course I don’t want to do anything that isn’t reversible if/when I sell the house.

Will any decent mic work with REW? I have a portable little laptop recording setup with Shure mics I could use.


----------



## mhutchins

If you can do a semi-permanent installation, I would build a plug using a 2x4 frame and 3-layers of 5/8" Type-X drywall with Green Glue on the room side of the plug and fill the cavity with pink fluffy or rock wool on the door/window side. I have read that you should allow for some air movement to prevent trapped moisture from becoming a problem. Convection will promote airflow from the bottom to the top, so that is where I would place the vents (make sure the insulation does not block the vents or impede airflow). I would try to place them inconspicuously on the bottom and top edges of the plug so they are out of site. I have no idea how big or how many vents are necessary, but remember that the greater the cross sectional area of the vents, the less effective the plugs become. Make the plugs a tight fit in the recess of the door or window frame and make a gasket out of felt of dense foam to create an air-tight seal around the perimeter. Consider using a screw or 4 to secure them in place if needed.

Ideally you want a microphone with a calibration file, however, if you do the plugs like I just described, there is no need to measure outdoors, because you likely won't be able to make it any quieter without doing a lot more work to the walls themselves. In other words, if you have maximized the remediation, there is no point in measuring with the thought of improving the remediation unless you just want to document the degree of sound reduction achieved. Check the specs on the Shure mics and see what kind of frequency response they have, or, just play a white noise signal on your system and use REW to chart the frequency response of your recording and reproduction chains with the mic indoors (without a calibration file, you can't separate the influence of the two signal chains). Then go outside and remeasure to see what the differences are before and after adding the plugs.


----------



## mkiv808

mhutchins said:


> If you can do a semi-permanent installation, I would build a plug using a 2x4 frame and 3-layers of 5/8" Type-X drywall with Green Glue on the room side of the plug and fill the cavity with pink fluffy or rock wool on the door/window side. I have read that you should allow for some air movement to prevent trapped moisture from becoming a problem. Convection will promote airflow from the bottom to the top, so that is where I would place the vents (make sure the insulation does not block the vents or impede airflow). I would try to place them inconspicuously on the bottom and top edges of the plug so they are out of site. I have no idea how big or how many vents are necessary, but remember that the greater the cross sectional area of the vents, the less effective the plugs become. Make the plugs a tight fit in the recess of the door or window frame and make a gasket out of felt of dense foam to create an air-tight seal around the perimeter. Consider using a screw or 4 to secure them in place if needed.
> 
> Ideally you want a microphone with a calibration file, however, if you do the plugs like I just described, there is no need to measure outdoors, because you likely won't be able to make it any quieter without doing a lot more work to the walls themselves. In other words, if you have maximized the remediation, there is no point in measuring with the thought of improving the remediation unless you just want to document the degree of sound reduction achieved. Check the specs on the Shure mics and see what kind of frequency response they have, or, just play a white noise signal on your system and use REW to chart the frequency response of your recording and reproduction chains with the mic indoors (without a calibration file, you can't separate the influence of the two signal chains). Then go outside and remeasure to see what the differences are before and after adding the plugs.


I don’t think there quite enough depth on the sliding patio door for that setup. Anything shallower?


----------



## mhutchins

mkiv808 said:


> I don’t think there quite enough depth on the sliding patio door for that setup. Anything shallower?


What about 2x2 instead of 2x4?


----------



## mkiv808

mhutchins said:


> What about 2x2 instead of 2x4?


Possible. I’ll have to measure. I know for sure I’m not getting 3 layers of drywall but maybe 2.

Any other materials folks use for door/window plugs?


----------



## mkiv808

Would something like a layer of mass loaded vinyl and Rock Wool be one way to try a window/door plug?


----------



## doublemazaa

If I'm building a room within a room, does it make sense to treat the walls/ceilings of out the outer room?

I am building a room within a room in my basement. It's going to be a small office/vocal booth. There is a lot of footfall noise from the hardwood floor from the floor above that I am hoping to not hear inside my quiet room.










I see this "best" assembly suggests putting drywall/green glue in the joist bays. If I completely decouple the ceiling of my room by hanging it from different structure that are below the joists, how meaningful would the drywall/green glue of the floor above be? I ask because my room within a room is quite small, compared to the floor above. To prevent flanking, I would need to treat an area about 15-20x bigger than my small room within a room.


----------



## mhutchins

The double drywall with Green Glue in the ceiling joist bays is the most effective treatment for eliminating footfall noise. Typically, only the floor area above the room-in-room area receives the stud bay treatment. 

With regards to your comment above, are you saying that there are no outer walls adjacent to the inner room And that the inner walls of the room-in-room are exposed to footfall noise from the full floor above? If that is the case, I would fill all the other bays with insulation and seal them up with two layers of drywall with Green Glue, either suspended from clips and channels (best) or attached directly to the bottom of the floor joists (almost as good). The idea is to attenuate the foot fall noise as much as possible without creating a triple leaf above the inner room.










Mike


----------



## JMAX2016

Curiosity question...

I'm from PA, and Lowe's carries Rockwool safe and sound. How does that compare to say DD with green glue? Have there been any tests? I have used it in the past, and it really seems to work. (And isn't that expensive).


----------



## AnnapolisSony

Has anyone ever shimmed a few of their sound isolation clips during their build? I am getting ready to start mounting clips and channel this week and, while marking out clip locations on walls and ceilings last evening, I realized that I may need to bring a couple a little further out to make them flush with others down the channel (all studs are not perfectly aligned). I'm not talking about shimming them much...but maybe a 1/4" - 3/8" max in a couple of spots. I am planning to mount all Resilmount A237R clips with the recommended #8 2 1/2" coarse thread screws. I will be going double layer of 5/8" DW with GG. If anyone has done this sort of thing your input would be greatly appreciated!


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## gimmepilotwings

I'm starting up my theater build again after a delay. I spent a few months building the other half of the basement. (wet bar area, game room, bed room)

I am having paralysis by analysis and that is the biggest reason I haven't been doing any work. I am afraid that I will do something wrong and the the soundproofing that I am doing DD + GG + clips + MLV will be for not. Theater is still down to the studs. My plan at the moment is to have a front false wall stage to hide the front speakers, and then hang the other speakers on the DD. Here are my assumptions and tell me if they are right.

1. Drill holes in the drywall for the speaker wire to be only big enough to allow the wires through and seal them with acoustic caulk. Avoid using boxes.
2. Use remodel boxes after the drywall is installed for the electrical to prevent the sound from going up the studs. Still use putty pads?
3. Use backer boxes for any lighting.
4. Install 2 ceiling recepticles in the ceiling for future proofing projector.

Here are a couple pictures of what I am working with. (excuse the mess)

Unfortunately I have two exits to the theater as the back room will be my office. I had planned a two door solution for sound proofing each exit, but not sure I will stick with that.

What should be my biggest concerns before I jump down this rabbit hole?


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## Snoochers

Would people recommend putting drywall between ceiling joists under the subfloor like this? It is a fair bit of work but I could maybe do it


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## pkinneb

Snoochers said:


> Would people recommend putting drywall between ceiling joists under the subfloor like this? It is a fair bit of work but I could maybe do it
> 
> View attachment 3042731


If I had to do it again I would definitely do it. Our master bath is above the theater and I can hear faint footsteps on the tile floor. Not a big deal for me since there is rarely anybody in there if we're watching a movie but I think the dd between the joist would solve that.


----------



## Blitzkrieg_CJH

JMAX2016 said:


> Curiosity question...
> 
> I'm from PA, and Lowe's carries Rockwool safe and sound. How does that compare to say DD with green glue? Have there been any tests? I have used it in the past, and it really seems to work. (And isn't that expensive).


I was wondering the same thing. My mechanical room is next too my family room/theatre with only one layer of drywall separating them. So anytime the furnace/central air/hot water heater/water softner turns on I can hear it and have to turn my receiver up. I was thinking about putting some Rockwoo S&S in the cavities & ceiling of the mechanical room to at least knock the noise down some.

Thoughts?


----------



## Snoochers

pkinneb said:


> If I had to do it again I would definitely do it. Our master bath is above the theater and I can hear faint footsteps on the tile floor. Not a big deal for me since there is rarely anybody in there if we're watching a movie but I think the dd between the joist would solve that.


Ok. Noted! It is a fair bit of work though. It isn't like just adding a layer of drywal, this will involve me making a LOT of 16" wide sections haha. Haven't done the math but must be like 100.


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## Ph8te

Snoochers said:


> Ok. Noted! It is a fair bit of work though. It isn't like just adding a layer of drywal, this will involve me making a LOT of 16" wide sections haha. Haven't done the math but must be like 100.


Do it right the first time and you won’t wonder “what if” or wish you had just done it all when everything was open. If I’ve learned anything from this thread is that you should do soundproofing right the 1st time when all the walls are down and it’s “easy”


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## pkinneb

Snoochers said:


> Ok. Noted! It is a fair bit of work though. It isn't like just adding a layer of drywal, this will involve me making a LOT of 16" wide sections haha. Haven't done the math but must be like 100.


LOL I hear you that is exactly why I didn't do it but now when I hear it, typically during football games becuase my wife doesn't like sports, I think you know it was a two fricken year project would it really have added that much time to it  

Having said that you really have to be listening for it and it has to be quiet in the room as well.


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## Snoochers

Ph8te said:


> Do it right the first time and you won’t wonder “what if” or wish you had just done it all when everything was open. If I’ve learned anything from this thread is that you should do soundproofing right the 1st time when all the walls are down and it’s “easy”


It is also worth asking how effective that addition would even be. My guess it is would help with noise from above, but I'm not sure how much sound it would stop from the actual theatre. Only one way to find out I suppose!


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## Snoochers

I was able to find a comparison of double drywall + resilient channel VS. double drywall + resilient channel + GREEN GLUE. 



http://www.greenglue.ca/greenGlue-vs-RC.pdf



As I suspected the utility of green glue is substantially diminished if you are using sound isolation clips or channels. This is a great document because it also shows some examples that have poor installation.


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## mhutchins

If you decide to go the Full Monty and add the drywall between the stud bays, don't assume the bays are all the same width or that the joists are parallel! Many AVSers have been gooned by this assumption...

Mike


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## gigging

I have a 28x20’ room that I want to build a room within a room in for my theater. I have a window in the room, is it ok to build a wall in front of that window for the new room within a room?

Thank you


Sent from my iPhone using Tapatalk


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## doublemazaa

In the case where you're adding double drywall into the joist bays on the underside on the subfloor, what purpose does the green glue serve?

Aren't the drywall screws holding the drywall to the subfloor short circuiting the layers of green glue?


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## mhutchins

The Green Glue provides visco-elastic damping that converts relative motion between drywall layers into heat. This damping can add several dB of sound isolation to most wall (floor/ceiling) structures without resorting to additional layers of drywall. This document from Green Glue provides a very good description of the impact of Green Glue in common wall assemblies.

In the case of Drywall + Green Glue in the stud bays, you are only relying on 2 aspect of the 4 pillars of soundproofing - Mass and Damping. This construction method is particularly effective in diminishing footfall noise. The other two pillars, Decoupling and Absorption are added later when you install the ceiling drywall. Acoustic short circuiting is a primary concern when dealing with Decoupled structures, such as Double Drywall (+/- Green Glue) suspended from clips and channel to Decouple the drywall layers from the supporting framing behind.

Mike


----------



## Elies

I want to soundproof my living room from my neighbors (1 one the same floor, and 1 downstairs). I'm going to put DD+green glue on the walls and rubber mat+OSB on the floor. Do I also need to do something with the ceiling? I'm on the last floor.


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## jcr159

Elies said:


> I want to soundproof my living room from my neighbors (1 one the same floor, and 1 downstairs). I'm going to put DD+green glue on the walls and rubber mat+OSB on the floor. Do I also need to do something with the ceiling? I'm on the last floor.


as always, "it depends", but probably... without doing the ceiling, you'll have a significant flanking path to the walls/floor that will make your other efforts less effective in the bass frequencies. 

The biggest part of "it depends" here is what your goals are... if it is to just quiet things enough that you can watch a movie in the early evening at -20 or -15 db without completely irritating your neighbors you might be ok... If the goal is to eliminate any noise to the neighbors because they call the police anytime they can hear anything from your place, then even doing the ceiling might not be enough, and you need to build a room within a room, etc.... expected outcomes are a big factor here. proper advice though would say to do the ceiling


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## Bryanlion

I have a projector set up in my basement. The basement has a drop ceiling that I would like to get rid of. The problem is that there's nothing above it except floor joists and the plywood subfloor. I took the ceiling down in one room and it went from "I can tell someone is yelling or stomping" to "we can have a conversation between floors if we raise our voices." As far as sound goes the current setup has been acceptable if not ideal.
I'm not trying to keep people upstairs from knowing there's a movie on downstairs, but I would like to not hear everything that gets said upstairs while I'm down there. Anyway, I'm wondering if sticking acoustic foam or some sort of batting (or anything else you might recommend) to the ceiling between the joists would provide a decent amount of sound absorption.
Any help or advice would be appreciated.


----------



## Elies

I found out that my subfloor is not directly on the joists, but is floating above them (see attached pictures). I live on the third floor of an old building and they probably had to float the current floor to compensate for the fact that the foundation moved/sunk. 

If I'm not mistaken, I have a triple leaf effect with the floor, right? How to mitigate that, should I blow some insulation or leave it empty?


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## VAMatt

I have a couple questions regarding moderate soundproofing of a basement entertainment space (not a dedicated theatre, not housing audiophile equipment, and not needing super high volumes at midnight) that will double as a guest room.

First, if I am limited to these options for drywall, what is likely to perform the best:

1) Double 1/2" ultralight drywall with GG
2) Single layer of Quietrock 500
3) Single layer of 5/8" firecode drywall

If it makes any difference to you, the reason for the limitation to these options is the incredible difficulty of getting 4*8 sheets of drywall into the space. They mathematically just barely fit, after doing some serious gymnastics. QR and 5/8" are so heavy that I'm simply not willing to get two layers worth of that into the space. 1/2" UL is light enough that I don't mind doing two layers worth. 

I am confident that a single layer of 5/8 is not a good idea. But, I figured I'd put it out here to confirm. 

And, yes, I have considered cutting down sheets to manageable sizes. But, that increases the linear footage of seams which I understand is not desirable from a soundproofing perspective, and is definitely not desirable from a drywall finishing perspective. So, I've ruled that option out at this point. 


Second question:

I am installing a coffered ceiling, and will be mounting other heavy-ish things to the ceiling. So, for moderate decoupling purposes, I'd like to use wood furring strips placed perpendicular to the joists. I understand that RC would be better. But, I think there is close to zero chance that we'll not short circuit it in a handful of places. I'll also have to do a lot more work to rig up stuff to support the coffered ceiling stuff and other items. With that in mind, is RC better enough to be worth the work of having to rig up other stuff for connecting of my coffered ceiling and other items. 

For what it's worth, hat channel and clips are out of the budget. There's just too many square feet of drywall for that. 

Thanks in advance for your input


----------



## mhutchins

I would go with Option #1. It has the most mass and Constrained Layer Damping.

Mike


----------



## VAMatt

Situation: a townhouse party wall made of standard 2 chamber concrete block, with wood furring strips nailed and glued to it, covered by 5/8 drywall that will then have a thin clay brick (actual clay brick, approximately 1/2-5/8" thick) "veneer" (installed like any normal tile) as the finish. I do not know what is on the neighbors' side of the walls.

The space will not be a dedicated home theatre, and will not be subject to reference level sound of audiophile equipment use. However, it will have entry level (maybe a step or two better) HT equipment that will be used probably 50% for gaming, 50% for movies and TV. 

Question:. What benefit, if any, is there to filling the approximately 5/8" void behind the drywall (the thickness of furring strips) with insulation? 

Does the same apply to the back wall, constructed the same way, that does not have a neighbors house on the other side (90ish percent of the height of that wall is below grade)?

Question: is there a readily available material that would be better for use in this scenario than fiberglass or mineral wool insulation (assuming that there is a real benefit to that)?


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## schwock5

I believe you are not supposed to fill that area as it would negate the purpose of the strips. The strips are to decouple the wall and by stuffng insulation you could create a path for the vibration to carry straight through


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## VAMatt

I have one more question..... On my ceiling I have double drywall with green glue. Over (or under, as the case may be) that will be a layer of 1/4" hardboard (high density fiberboard) beadboard that will become part of a coffer d ceiling. Does green glue make sense between the drywall and the beadboard? Is there likely to be real benefit from it? I'd probably keep it to 1-1.5 tubes per sheet for budget reasons, but don't want to spend that money unless it's likely to yield improvement worth the $400 or so that it will cost me.

Also, I'm assuming that the added mass of the beadboard is a good thing. There's not some factor that in overlooking that would make this beadboard a problem, right?


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## Harkon

Room is ready for me now to build the stud work. Using 2x4 decoupled studs and double drywall and greenglue. 

Need to purchase the insulation for the cavities. As I'm in the UK most use Rockwool which comes in large slabs.

The most common used are RWA45 (45kg per m3) or RW3 (60 kg per m3)

Does it matter what I use? I think some in the UK go for the denser insulation but surely that's not needed as it's the mass of the drywall that is dong that part.


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## jrref

VAMatt said:


> Situation: a townhouse party wall made of standard 2 chamber concrete block, with wood furring strips nailed and glued to it, covered by 5/8 drywall that will then have a thin clay brick (actual clay brick, approximately 1/2-5/8" thick) "veneer" (installed like any normal tile) as the finish. I do not know what is on the neighbors' side of the walls.
> 
> The space will not be a dedicated home theatre, and will not be subject to reference level sound of audiophile equipment use. However, it will have entry level (maybe a step or two better) HT equipment that will be used probably 50% for gaming, 50% for movies and TV.
> 
> Question:. What benefit, if any, is there to filling the approximately 5/8" void behind the drywall (the thickness of furring strips) with insulation?
> 
> Does the same apply to the back wall, constructed the same way, that does not have a neighbors house on the other side (90ish percent of the height of that wall is below grade)?
> 
> Question: is there a readily available material that would be better for use in this scenario than fiberglass or mineral wool insulation (assuming that there is a real benefit to that)?


I have the same situation and i can tell you, unless your floor is concrete or decoupled from your neighbor, no matter what you do, you will get some level of flanking sound transmission through the floor. So if you are playing your system at reference levels with lots of bass, the bass will be heard by your neighbors. The neighbor on the other side where you are below grade will probably be fine. I would soundproof that wall as well if you can. I'm a firm believer if you want to play your music and or home theater at reference levels you need to live in a private house because the bass will always be an issue.


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## VAMatt

jrref said:


> I have the same situation and i can tell you, unless your floor is concrete or decoupled from your neighbor, no matter what you do, you will get some level of flanking sound transmission through the floor. So if you are playing your system at reference levels with lots of bass, the bass will be heard by your neighbors. The neighbor on the other side where you are below grade will probably be fine. I would soundproof that wall as well if you can. I'm a firm believer if you want to play your music and or home theater at reference levels you need to live in a private house because the bass will always be an issue.


I am soundproofing all walls to some extent. All are below grade. This is the bottom floor of a three level home. One is an interior wall that partitions the basement (I call this the front wall), it's wood framed like any other interior wall. One is an exterior wall that is not shared with a neighbor (I call this the back wall). The two side walls are shared with neighbors. The side walls and back walls are concrete block with wood furring strips attached. The floor is carpet over concrete slab. 

I'm basically just trying to figure out if it makes sense to fill the small void between furring strips on the block walls with insulation (or something else). 

I agree with you complete that one needs to be in a detached home to be able to comfortably play stuff with substantial bass at high volumes. But, we gotta do the best we can with what we have.


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## Ladeback

VAMatt said:


> I am soundproofing all walls to some extent. All are below grade. This is the bottom floor of a three level home. One is an interior wall that partitions the basement (I call this the front wall), it's wood framed like any other interior wall. One is an exterior wall that is not shared with a neighbor (I call this the back wall). The two side walls are shared with neighbors. The side walls and back walls are concrete block with wood furring strips attached. The floor is carpet over concrete slab.
> 
> I'm basically just trying to figure out if it makes sense to fill the small void between furring strips on the block walls with insulation (or something else).
> 
> I agree with you complete that one needs to be in a detached home to be able to comfortably play stuff with substantial bass at high volumes. But, we gotta do the best we can with what we have.



Even if you live in a home that is detached from your neighbor they could still feel the bass depending on what you are using for subs, power and what type of soil or rock is between your houses. I remember a member in my area tried out of the first JTR ULF 4000's and neighbors a block away thought it was an earthquake.. My wife doesn't think I need much soundproofing because she says its not to bad. What she doesn't realize all my subs are old and need to be replaced. they don't put out a lot at all.


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## vintagevancity

I am soundproofing 2 basements suites so we cannot hear our future tenants from above. We are doing resilient channel and 2 layers of 5/8th drywall with green glue on the ceiling. Walls will be full of acoustic insulation and perimeter sealed with acoustic sealant. The goal is to create an air-tight seal of the room. My big dilemma/question is: what do I do with the lighting? It seems impossible not to break the seal to add overhead lighting. I'm not opposed to track lighting, but leaning toward flush mount lights. Apparently pot lights/recessed lighting undermines the soundproofing altogether. But how does adding track lighting not do the same thing? Again, what are the options with lighting? Any suggestions greatly welcomed! Thanks in advance!


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## ItsNate

vintagevancity said:


> I am soundproofing 2 basements suites so we cannot hear our future tenants from above. We are doing resilient channel and 2 layers of 5/8th drywall with green glue on the ceiling. Walls will be full of acoustic insulation and perimeter sealed with acoustic sealant. The goal is to create an air-tight seal of the room. My big dilemma/question is: what do I do with the lighting? It seems impossible not to break the seal to add overhead lighting. I'm not opposed to track lighting, but leaning toward flush mount lights. Apparently pot lights/recessed lighting undermines the soundproofing altogether. But how does adding track lighting not do the same thing? Again, what are the options with lighting? Any suggestions greatly welcomed! Thanks in advance!


Backer boxes are commonly used I believe:


https://www.soundproofingcompany.com/wp-content/uploads/2019/10/CIM-backer-box-1.pdf


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## VAMatt

I made backer boxes of 3/4" MDF lined with 5/8" drywall (with GG). Seem to work well.

As for track lighting.... If all you have is a single J box to connect a track light fixture, that's a lot better than 8 recessed cans, for example.


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## Harkon

I'm not sure whether this is more appropriate here or the Acoustic Treatment thread. 

Most people suggest filling the soffit with fluffy insulation. I'm guessing it reduces vibrations and resonance at the very least, at best it might act as a large bass trap. 

I'm hoping to make my soffit with removable panels to allow future cabling, access to fans/duct, pelmet sockets etc if it is ever needed.

With that in mind I'm not massively keen on using loose insulation. I'm sure I saw someone on AVS use pillows instead! Similar material and can be pulled out and put back in if needed, without covering everything with fiberglass/mineral wool insulation. 

Has anyone done this or seen it done? Any reason to not do it?


----------



## VAMatt

Harkon said:


> I'm not sure whether this is more appropriate here or the Acoustic Treatment thread.
> 
> Most people suggest filling the soffit with fluffy insulation. I'm guessing it reduces vibrations and resonance at the very least, at best it might act as a large bass trap.
> 
> I'm hoping to make my soffit with removable panels to allow future cabling, access to fans/duct, pelmet sockets etc if it is ever needed.
> 
> With that in mind I'm not massively keen on using loose insulation. I'm sure I saw someone on AVS use pillows instead! Similar material and can be pulled out and put back in if needed, without covering everything with fiberglass/mineral wool insulation.
> 
> Has anyone done this or seen it done? Any reason to not do it?


Unless your pillows are full of fiberglass or mineral wool, theyre definitely not the same as using batt insulation. Pillows are generally going to be a lot more dense than insulation. They also arent going to fill the void in the same way. 

How often do you expext to need access to the soffits? One or twice per year, maybe? I'd just use proper insulation and spend a few.minites vacuuming after each of the few times you open up the soffits. 

On a similar note, wouldn't it make mose sense to just run lots of wire now (a couple extra pairs than you expect to need), maybe even leaving a loop of excess every several feet so that you can pull to wherever needed, then build the soffits properly? There is no practical way to get the same level of soundproofing out of removable panels that you can get from fixed materials. I had planned to put a handful of access panels around my room as well, until I really dug into soundproofing research. I eventually realized that it's a bad idea. Instead, I wired my room up for 7.X.4, even though I'm only running 5.1 now. Even built and installed boxes for in-ceiling speakers, just in case I later decide to go that route.


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## Harkon

It won’t affect sound proofing as it’s inside the room. I’ve done extra cable, left service loops of cable and built backer boxes.
Daydream theatre (a build thread on here) used large pillows instead of fibreglass. Took me a while to found where I’d seen it.


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## Harkon

Should I chalk the gaps between the second layer of drywall or will the mud cover it?


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## jcr159

Since the soffits would only be acting as bass traps, pillows are just fine. The performance difference in the bass frequencies wouldn't be enough to worry about...

you SHOULD be concerned about how you design the openings to the soffit though... done poorly, you'll end up creating a Helmholtz resonator rather than a bass trap. You'll likely want to wrap a large portion of the soffit with AT cloth or something along those lines... If you just put an opening in both ends, it'll resonate like a port/bottle...


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## Harkon

I’ve no idea what a Helmholtz resonator is but doesn’t sound good. I can make all the side panels of the soffit out of black acoustic fabric and just the underside out of MDF, so it’s completely open on one side.


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## jcr159

Harkon said:


> I’ve no idea what a Helmholtz resonator is but doesn’t sound good. I can make all the side panels of the soffit out of black acoustic fabric and just the underside out of MDF, so it’s completely open on one side.


yeah, do that with the fabric... as for the resonator, think blowing over the mouth of a coke/beer bottle....


----------



## Snoochers

Has anyone ever heard of or used these sound isolation clips? They're a lot cheaper than alternatives and still seem to include rubber which is nice compared to the cheaper IB-1 or the like.


















Resilient Sound Insulating Drywall Clip EVOLUTION (100 pack) | eBay


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www.ebay.com


----------



## Rjloper9

Do wall corners need to be decoupled where they meet or can they be joined together as long as they’re decoupled from the ceiling?


Sent from my iPhone using Tapatalk


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## pkinneb

Rjloper9 said:


> Do wall corners need to be decoupled where they meet or can they be joined together as long as they’re decoupled from the ceiling?
> 
> 
> Sent from my iPhone using Tapatalk


If I understand your question correctly you are asking if the inside walls of a room inside a room can be attached to each other and the answer would be yes. the four walls would be decoupled from the ceiling with clips and from the outer walls with a 1" ish air gap.


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## JNayAV

Going to be finishing basement for dedicated theater room. Planning decoupled room within a room, clips and channel ceiling.
Question I have is that there is insulation on the concrete walls already. Can I leave the insulation and offset new studs and be okay, or should I take current insulation down first?

Plan to also put rockwool in new stud cavities in addition to leaving current insulation unless it would cause problems.


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## pkinneb

It will be fine you just don't want another vapor barrier on the inner wall as long as what you put up can breath you are ok. 
Here is what I started with








I then used paper backed pink fluffy/ Rockwool on the inner wall. It's hard to tell here but I slit the paper all over to insure I didn't trap moisture between two vapor barriers. I used paper backed for ease of use in the full width stud bays.


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## Rjloper9

pkinneb said:


> If I understand your question correctly you are asking if the inside walls of a room inside a room can be attached to each other and the answer would be yes. the four walls would be decoupled from the ceiling with clips and from the outer walls with a 1" ish air gap.


That is correct and thank you!

One more question. I’ve read BIG and others recommend spacing the IB-3 brackets every 48”. Is that starting from one corner to the next or is there another way to do it?

My front wand back walls will be about 16’. If I start at one corner and go every 48” I’d end up with 5 brackets on each of the front and back walls?

And for the side walls, would I start in the corners there as well and essentially have each wall’s corner ib-3 brackets side by side attaching them to the proper floor joists?

Thanks!


Sent from my iPhone using Tapatalk


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## pkinneb

Rjloper9 said:


> That is correct and thank you!
> 
> One more question. I’ve read BIG and others recommend spacing the IB-3 brackets every 48”. Is that starting from one corner to the next or is there another way to do it?
> 
> My front wand back walls will be about 16’. If I start at one corner and go every 48” I’d end up with 5 brackets on each of the front and back walls?
> 
> And for the side walls, would I start in the corners there as well and essentially have each wall’s corner ib-3 brackets side by side attaching them to the proper floor joists?
> 
> Thanks!
> 
> 
> Sent from my iPhone using Tapatalk


IIRC I used 5 on my 17'2" walls and 4 on the 14'9" walls I also started in a one stud bay since the corners were attached I didn't see a need for any right on the corners.


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## VAMatt

Here's something for you too chew on:

My basement has very tight access. You cannot get 4*8 sheets of drywall into the space. Even working with 4*4 pieces is tough, but lighter stuff is much easier. With this in mind, and thinking that I don't need perfection, I decided to go with double 1/2" drywall (with GG).

To make a long story short, once the drywall was finished, it was immediately apparent that this wasn't enough. So, I've since added a layer of 5/8" to it. Now I have about the same mass as I would have had I done two layers of 5/8" to start with, but I've done quite a bit more work to get there. I also lost 3/8" of space, which is significant with my already less than ideal ceiling height. I do now have an additional damping layer, so that's a small silver lining. My understanding is that this is likely not worth much, and certainly not worth the work of installing drywall overhead an extra time, not to mention the added cost (I'm taking whatever silver linings I can get out of that extra work though).

The moral of this story is don't be a dumbass like me. Do it right the first time. Cut your sheets down to 32" if needed, so you can handle the weight.


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## jcr159

VAMatt said:


> Here's something for you too chew on:
> 
> My basement has very tight access. You cannot get 4*8 sheets of drywall into the space. Even working with 4*4 pieces is tough, but lighter stuff is much easier. With this in mind, and thinking that I don't need perfection, I decided to go with double 1/2" drywall (with GG).
> 
> To make a long story short, once the drywall was finished, it was immediately apparent that this wasn't enough. So, I've since added a layer of 5/8" to it. Now I have about the same mass as I would have had I done two layers of 5/8" to start with, but I've done quite a bit more work to get there. I also lost 3/8" of space, which is significant with my already less than ideal ceiling height. I do now have an additional damping layer, so that's a small silver lining. My understanding is that this is likely not worth much, and certainly not worth the work of installing drywall overhead an extra time, not to mention the added cost (I'm taking whatever silver linings I can get out of that extra work though).
> 
> The moral of this story is don't be a dumbass like me. Do it right the first time. Cut your sheets down to 32" if needed, so you can handle the weight.


interesting... I have a boatloat of compromises, and currently plan 2 layers of 1/2" with GG, and using decoupled mounts.. what was it you weren't satisfied with? what levels do you listen to, what were your goals? are you at room within a room level of isolation? 

Thanks for any additional insight!


----------



## VAMatt

jcr159 said:


> interesting... I have a boatloat of compromises, and currently plan 2 layers of 1/2" with GG, and using decoupled mounts.. what was it you weren't satisfied with? what levels do you listen to, what were your goals? are you at room within a room level of isolation?
> 
> Thanks for any additional insight!


My room is room is not finished yet, so I haven't given it a real test. I am slightly decoupled, but not well enough that I'd call my room decoupled (wood furring strips run perpendicular to existing framing). I am in an interior unit townhome, below grade. 3 walls are exterior (neighbors behind two of those walls). The exterior of the house is standard hollow concrete block. 

When I had the space completely opened up during demo, I could easily hear my neighbors talking at normal volume. I couldn't understand the words, but I think we were very close to the point where that would be possible. After the first round of drywall, if my room was totally quiet, and I paid attention, I could still hear the neighbors talking at what seems to be a normal volume. I was expecting better than that. 

Incidentally, I had better performance within my home, presumably because of the insulation in joist and stud cavities (not present on the side wall because the cavity was only 5/8"deep), and because of the floor and wall coverings on other surfaces. My guess is that this particular neighbor has an unfinished basement (i can't hear the neighbors on the other side, even though I know them to be louder). 

Now that there's a layer of 5/8 going on, things seem much better. However, this layer is currently unfinished, and I haven't given it any real testing.


----------



## jcr159

VAMatt said:


> My room is room is not finished yet, so I haven't given it a real test. I am slightly decoupled, but not well enough that I'd call my room decoupled (wood furring strips run perpendicular to existing framing). I am in an interior unit townhome, below grade. 3 walls are exterior (neighbors behind two of those walls). The exterior of the house is standard hollow concrete block.
> 
> When I had the space completely opened up during demo, I could easily hear my neighbors talking at normal volume. I couldn't understand the words, but I think we were very close to the point where that would be possible. After the first round of drywall, if my room was totally quiet, and I paid attention, I could still hear the neighbors talking at what seems to be a normal volume. I was expecting better than that.
> 
> Incidentally, I had better performance within my home, presumably because of the insulation in joist and stud cavities (not present on the side wall because the cavity was only 5/8"deep), and because of the floor and wall coverings on other surfaces. My guess is that this particular neighbor has an unfinished basement (i can't hear the neighbors on the other side, even though I know them to be louder).
> 
> Now that there's a layer of 5/8 going on, things seem much better. However, this layer is currently unfinished, and I haven't given it any real testing.


wow... that seems... strange... something clearly went awry if you could hear neighbors talking with 2 layers of 1/2" with GG between... makes me nervous though, that's for sure. I'm not looking for bunker level quiet, but i wasn't thinking I'd be at that level either...


----------



## VAMatt

jcr159 said:


> wow... that seems... strange... something clearly went awry if you could hear neighbors talking with 2 layers of 1/2" with GG between... makes me nervous though, that's for sure. I'm not looking for bunker level quiet, but i wasn't thinking I'd be at that level either...


Like i said (or meant to say), it was much better with the drywall up than it was pre-drywall. It just wasn't close to where I wanted it to be.

Incidentally, I've taken some additional measures to help in my specific case. I didn't include them in my comments earlier because I didn't want to confuse things, and they're specific to my space. But, you can take this to mean that I was so dissatisfied that I revisited the design to add in much more mass.


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## howiee

Hey all. What do you do with chasing cables through walls to stop sound escaping? Is it a simple case of sealent at the point they stick trhough?


----------



## Snoochers

I want three layers of drywall on an upcoming ceiling using clips like the RSIC-1. I've had a chat with people who sell these types of clips and some recommend 16" between channels and 48" between clips (as seen here https://pac-intl.com/pics/i-guide/rsic-panel-4.jpg). However, I spoke to another guy who sells these and he suggested keeping 24" between channels and putting 32" between clips. The number of clips required appears to be the same, but in the second case I would need fewer channels and save a bit of money.

Does it matter?


----------



## Rjloper9

Snoochers said:


> Has anyone ever heard of or used these sound isolation clips? They're a lot cheaper than alternatives and still seem to include rubber which is nice compared to the cheaper IB-1 or the like.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Resilient Sound Insulating Drywall Clip EVOLUTION (100 pack) | eBay
> 
> 
> Find many great new & used options and get the best deals for Resilient Sound Insulating Drywall Clip EVOLUTION (100 pack) at the best online prices at eBay! Free shipping for many products!
> 
> 
> 
> www.ebay.com


Have you pulled the trigger on these or found anyone who has? If they’re legit, they’d be a huge cost savings.


Sent from my iPhone using Tapatalk


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## Snoochers

Rjloper9 said:


> Have you pulled the trigger on these or found anyone who has? If they’re legit, they’d be a huge cost savings.
> 
> 
> Sent from my iPhone using Tapatalk


I got a couple hundred of them... They seem fine. Basically they're from Aliexpress I think and probably no different from the more expensive ones.


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## IrishODocks

Hey there! Hopefully not hi-hacking an ongoing conversation, but was not really able to search and find a thread on my specific question, so here goes.

I am getting a 85" TV for my new HT room and at this size, I was not able to find a floor stand (or even a stand that would rest on a piece of furniture) for it. Therefore I am left with 2 options: wall-mounting it or putting it directly on a (higher?) piece of furniture.

What would be your favored option? And if wall-mounting is the way to go for easier adjustments after, will it screw up my soundproofing efforts (also recognizing I will have to screw the mount through approx 2 1/4" inch of drywall, resilient channels and acoustic panels)?

Thank you!


----------



## mhutchins

A TV that size would have a sizable weight to support via the drywall. I would not consider trying to support the weight with a drywall screw that also goes through soft acoustic panels. This would create a lever arm that would tend to pry the screw out of the drywall. On the other hand, you don’t want to screw through the drywall all the way to the wall studs, which would eliminate the decoupling you worked so hard to achieve.

I would use wood spacers that are the same thickness as the acoustic panels to provide a rigid connection to the drywall but is level with the surface of the acoustic panels. At a minimum, I would want the wood spacers to be 3-4” square and held in place with at least 2 toggle bolts and construction adhesive bonding the spacer to the drywall. These could be configured as French cleats if you want easy mount/dismount of the television. I would make every effort to avoid capturing the resilient channel with the toggle bolt unless you can be certain of capturing it dead center.

Mike


----------



## IrishODocks

Hi Mike,

Thanks for your reply. Just so I can visualize your suggestion, I will be displaying my immense CGI talents below. Green is the acoustic panel, the little grey arrows represent the resilient channels, then you have 2 layers of drywall. The blue beads in-between represents the acoustic compound.

Are you saying I should glue+bolt little pieces of woods behind the first layer of drywall, making sure the piece of wood falls in-between studs and resilient channels (in other words, does not touch anything else than the drywall)? Then those pieces would serve as reinforcement to the drywall into which I will drive my wall-mount screws, so whenever this lever effect happens, it will not pull the screws straight out of the drywall but hold on to the wood. The way I see this is the wood spacers would effectively be like enlarged wings of toggle bolts, distributing the force exerted by the wall-mount on a larger area?

I might be totally off track here as I must admit I was not too certain what you meant by having the wood spaces be the same thickness as the acoustic panels and level to them. 

Thanks again!


----------



## mhutchins

Here are a few drawings to save me a 1000 words. 

Note that the toggle bolts don't interfere with the hat channel and that they are short enough not to contact the studs. Ideally they would be placed in the stud bays away from the studs. For a large TV you might need 6 or more blocks. Alternatively, you could use two continuous horizontal blocks (2x4 or 2x6) spanning the width of the TV mount to spread the load over a broader area. Also, you should use additional clips to support the added weight of the TV. Most clips can support 30-40Lbs each.


----------



## jjcook

@IrishODocks If your walls are not already built, you can add acoustical blocking to attach the TV to, e.g.:


----------



## IrishODocks

Welp, I have a weird feeling my drawings are not up to par on this thread haha!



mhutchins said:


> Here are a few drawings to save me a 1000 words.
> 
> Note that the toggle bolts don't interfere with the hat channel and that they are short enough not to contact the studs. Ideally they would be placed in the stud bays away from the studs. For a large TV you might need 6 or more blocks. Alternatively, you could use two continuous horizontal blocks (2x4 or 2x6) spanning the width of the TV mount to spread the load over a broader area. Also, you should use additional clips to support the added weight of the TV. Most clips can support 30-40Lbs each.


Thank you, that is much clearer now, but this raises another question for me. The order in which the wall layers are laid out in your drawings are different than what I was planning for. I was going for (innermost to outermost) studs, acoustic panels, resilient channels and 2 layers of drywall. In your drawings, drywall goes first, then the channels and the acoustic panels on the outside. Is there a reason for this or is it a matter of preference? Also, in your configuration, would you finish the walls with a 3rd layer of drywall or some kind of felt/carpet?

At the end of the day, I think I can still replicate your design with my reversed order, but just curious about the configuration itself and the pros and cons for each.



jjcook said:


> @IrishODocks If your walls are not already built, you can add acoustical blocking to attach the TV to, e.g.:


Very interesting! Would you happen to have the name of those floating clips? I have raised the walls already, but I haven't laid out the panels yet, so I could still potentially attach those acoustic blocks to the studs. Thanks!

Edit: Nevermind me, I looked up the picture details and found what I was looking for; RSIC DC04 clips. Now on to find them in Canada.. that's a whole other challenge


----------



## mhutchins

IrishODocks said:


> Welp, I have a weird feeling my drawings are not up to par on this thread haha!
> 
> Thank you, that is much clearer now, but this raises another question for me. The order in which the wall layers are laid out in your drawings are different than what I was planning for. I was going for (innermost to outermost) studs, acoustic panels, resilient channels and 2 layers of drywall. In your drawings, drywall goes first, then the channels and the acoustic panels on the outside. Is there a reason for this or is it a matter of preference? Also, in your configuration, would you finish the walls with a 3rd layer of drywall or some kind of felt/carpet?
> 
> At the end of the day, I think I can still replicate your design with my reversed order, but just curious about the configuration itself and the pros and cons for each.
> .
> .
> .


Hey Irish,

I had assumed your walls were already finished. Normally, acoustic panels are on the outside of the wall facing the theater occupants. Acoustic panels are generally installed inside the room to cure/prevent problematic reflected sounds. Inside the stud cavity, you want to install regular insulation such as fiberglass or rockwool batts to minimize resonance inside the stud cavity and to slightly attenuate noise transmission through the wall.

If you haven't built your walls yet, or at least haven't hung the drywall, I would recommend a different solution. I would install 2-3 extra clips to support the added weight of the TV then attach plywood sheets as the first layer attached to your hat channel in the area of the wall intended to support the TV. The second layer of drywall would go up with Green Glue over the plywood the same as the rest of the wall. Now you have a solid, weight-bearing wall that can support a large Flat Panel TV with nothing more than a few spacers blocks screwed into the plywood to space the TV out away from the acoustic panels/wall treatments.

Mike


----------



## schwock5

If the wall isn't established yet the easier and cheaper solution is to decouple the wall itself and not even have to use clips and channels and then you can use any stud as normal


----------



## IrishODocks

schwock5 said:


> If the wall isn't established yet the easier and cheaper solution is to decouple the wall itself and not even have to use clips and channels and then you can use any stud as normal


Sometimes the most simple solutions are the best. As much as I hated the idea of finally not being done with building the partition walls, I must admit this idea is probably the best due to its simplicity and effectiveness. I will just bite the bullet, go buy a dozen additional 2x3s and build this decoupled wall in front of my soundproofed wall and wall mount the TV without being worried about drilling through the studs. Thanks!


----------



## Gavin Byrne

I am looking to reduce the noise coming from my basement through the ceiling. When watching a movie at the levels I like you can clearly hear the muffled dialog and explosions in the rooms above and also in the bedroom above that. I don't need to block all noise from the room above but want to reduce it enough that it can't be heard in the bedroom above it.

The ceiling is just like this image










I am wondering if the best bang for buck is to add another layer of drywall with green glue to the existing drywall? Has anyone done just this and noticed an improvement? I'd prefer not to rip down the existing drywall if possible, and am wondering if adding extra layers is the most practical.











The wall behind the screen is concrete with a gap of an inch or two to a wooden frame wall with drywall attached and has loose insulation. Should this wall be OK or could it also benefit from an extra layer of drywall? I am thinking of sound travelling up through the wall to the floors above, and that this wall is the same wall our bed is against in our master bedroom.

There are a couple of in ceiling speakers which initially added to the noise but I then added rubber backing boxes which helped.

Not shown in the picture is an SVS PB-2000 to the left of the front left speaker which was recently added and has definitely increased the complaints from the bedroom at night. I have ordered the SVS SoundPath Subwoofer Isolation System to see if that helps but haven't got it yet to try it.

As you can see from the picture below there is a soffit around HVAC ducts on the left and another around a steel I beam on the right. Would there be a benefit in just adding the extra layer of drywall and green glue to the non soffit areas of the ceiling or would you need to do everything to get any benefit?

Possibly a silly question but is it straightforward to adjust the light fixtures and HVAC returns to account for the extra layer of drywall?










Thanks


----------



## jcr159

Gavin Byrne said:


> I am looking to reduce the noise coming from my basement through the ceiling. When watching a movie at the levels I like you can clearly hear the muffled dialog and explosions in the rooms above and also in the bedroom above that. I don't need to block all noise from the room above but want to reduce it enough that it can't be heard in the bedroom above it.
> 
> The ceiling is just like this image
> 
> View attachment 3071950
> 
> 
> I am wondering if the best bang for buck is to add another layer of drywall with green glue to the existing drywall? Has anyone done just this and noticed an improvement? I'd prefer not to rip down the existing drywall if possible, and am wondering if adding extra layers is the most practical.
> 
> View attachment 3071953
> 
> 
> 
> The wall behind the screen is concrete with a gap of an inch or two to a wooden frame wall with drywall attached and has loose insulation. Should this wall be OK or could it also benefit from an extra layer of drywall?
> 
> There are a couple of in ceiling speakers which initially added to the noise but I then added rubber backing boxes which helped.
> 
> Not shown in the picture is an SVS PB-2000 to the left of the front left speaker which was recently added and has definitely increased the complaints from the bedroom at night. I have ordered the SVS SoundPath Subwoofer Isolation System to see if that helps but haven't got it yet to try it.
> 
> As you can see from the picture below there is a soffit around HVAC ducts on the left and another around a steel I beam on the right. Would there be a benefit in just adding the extra layer of drywall and green glue to the non soffit areas of the ceiling or would you need to do everything to get any benefit?
> 
> Possibly a silly question but is it straightforward to adjust the light fixtures and HVAC returns to account for the extra layer of drywall?
> 
> View attachment 3071949
> 
> 
> Thanks


So... Short answer, you would see some improvement by adding GG and a layer of drywall on the ceiling, but might not be happy with the result.

Longer answer... IF, you are "on the edge" of tolerability, treating only the ceiling with the plan outlined will likely help enough.

Probably though, you are going to need to do more... the issue is two-fold. you don't have any decoupling from the walls to ceiling, or ceiling to joists... second, you have a transmission path through the HVAC system. 

If it were me, I'd consider doubling ALL the ceiling drywall with GG layer, and see where I was, knowing that the next step is a lot of rip out and throw away work for what I just did.

Alternatively, you could rip ALL the ceiling out, stuff the joist cavities with R19, install clips/hat or hushframe raft to decouple (HushFrame Raft), and 2 layers drywall with GG, and acoustic sealant around the perimeter... essentially, "float" the ceiling. This would involve sealing all the penetrations like can lights, etc as well. it won't get you to where a dedicated theater will be, but will be much more effective. Anything you can do to address HVAC paths will help too. (and mousepads work well while waiting on the isolation feet... or a thick comforter folded up just to test...)

Many here will tell you that's a lot of work for a compromised solution... and it is... but it is kinda reasonable, and more effective, as you likely have a lot of unsealed penetrations right now, and drywall right on joists which basically acts like a drum...


----------



## Gavin Byrne

jcr159 said:


> So... Short answer, you would see some improvement by adding GG and a layer of drywall on the ceiling, but might not be happy with the result.
> 
> Longer answer... IF, you are "on the edge" of tolerability, treating only the ceiling with the plan outlined will likely help enough.
> 
> Probably though, you are going to need to do more... the issue is two-fold. you don't have any decoupling from the walls to ceiling, or ceiling to joists... second, you have a transmission path through the HVAC system.
> 
> If it were me, I'd consider doubling ALL the ceiling drywall with GG layer, and see where I was, knowing that the next step is a lot of rip out and throw away work for what I just did.
> 
> Alternatively, you could rip ALL the ceiling out, stuff the joist cavities with R19, install clips/hat or hushframe raft to decouple (HushFrame Raft), and 2 layers drywall with GG, and acoustic sealant around the perimeter... essentially, "float" the ceiling. This would involve sealing all the penetrations like can lights, etc as well. it won't get you to where a dedicated theater will be, but will be much more effective. Anything you can do to address HVAC paths will help too. (and mousepads work well while waiting on the isolation feet... or a thick comforter folded up just to test...)
> 
> Many here will tell you that's a lot of work for a compromised solution... and it is... but it is kinda reasonable, and more effective, as you likely have a lot of unsealed penetrations right now, and drywall right on joists which basically acts like a drum...


Thanks for the reply, and it all makes sense to me. I think I have somewhere close to around 1000 square feet of ceiling surface so need to figure out the cost difference to see whether it makes sense to try the "floating" ceiling option.


----------



## jcr159

Gavin Byrne said:


> Thanks for the reply, and it all makes sense to me. I think I have somewhere close to around 1000 square feet of ceiling surface so need to figure out the cost difference to see whether it makes sense to try the "floating" ceiling option.


yep, good luck! that's a lot of ceiling... honestly, if you have can lights without backer boxes, that's killing you more than anything...

Though there's a trick you can use with the new super thin led lights to avoid backer boxes, you'll need to rip the entire ceiling out either way...


----------



## VAMatt

I am definitely not an expert, but I have studied this stuff pretty thoroughly over the last 6 months and I'm just now wrapping up a moderately soundproofed room as part of a basement remodel. Here's what I can tell you for sure about your room:

If you want to achieve any significant improvement, you're either going to need to treat the entire contiguous space, or subdivide the room and treat the entire theater area. If you just treat the ceiling in the theater area right now, considering that it is open to the adjacent spaces, you are going to achieve close to zero. So, I don't think there's really any reason to even consider that option. It just isn't going to do enough. 

I learned this the hard way. I treated only the ceiling in my room. That was double drywall with green glue, insulation, backer boxes for the lights, etc. I did add insulation in the walls of the room, but no double drywall or anything else like that. Then, when the room was mostly complete, I did some testing. It was immediately obvious that the walls needed to be treated. So, I went back, added double drywall with green glue there, treated outlets, etc. At this point, it is very obvious that there is a major sound leakage at the end of the hallway entering the space. This will get a door once we've moved furniture into the room. But, you can tell right now that this door negates probably 70% of the soundproofing that's been done. You can still hear sound in the room directly above the theater area even though the future doorway to the theater area is not below that room. In other words, it's a major flanking path. And, that's what you're going to have if you don't treat the entire contiguous space.

If you're not looking for more than a 50% improvement, you might be able to skip one of the four basic soundproofing steps. But, you cannot do anything less than three of the four if you want to achieve something worthwhile. Believe me, I've tried. The above was just the simplified version of my story. I experimented with various corner cutting methods, only to learn that all of them resulted in too big of a loss. Corners cannot be cut to any substantial degree.


----------



## jcr159

Fair points... i was assuming that it was a basement space, and therefore had a door to close to the upstairs.... make sure that is a solid core door with weatherstrip/sealing around it... for me, my walls are decoupled from the joists for the most part, and that helps a lot too... reduces the need for 2 layers of of drywall, though it still helps plenty....

remember, what matters most is your goal.... there are a lot of ways to get "some" improvement, but if you want to watch a movie at-15 or louder, and not hear anything upstairs, you need to do a LOT more work... if the goal is to kill conversations/tv watching "mostly", then you can do less and get most of the way there...


----------



## Gavin Byrne

VAMatt said:


> I am definitely not an expert, but I have studied this stuff pretty thoroughly over the last 6 months and I'm just now wrapping up a moderately soundproofed room as part of a basement remodel. Here's what I can tell you for sure about your room:
> 
> If you want to achieve any significant improvement, you're either going to need to treat the entire contiguous space, or subdivide the room and treat the entire theater area. If you just treat the ceiling in the theater area right now, considering that it is open to the adjacent spaces, you are going to achieve close to zero. So, I don't think there's really any reason to even consider that option. It just isn't going to do enough.
> 
> I learned this the hard way. I treated only the ceiling in my room. That was double drywall with green glue, insulation, backer boxes for the lights, etc. I did add insulation in the walls of the room, but no double drywall or anything else like that. Then, when the room was mostly complete, I did some testing. It was immediately obvious that the walls needed to be treated. So, I went back, added double drywall with green glue there, treated outlets, etc. At this point, it is very obvious that there is a major sound leakage at the end of the hallway entering the space. This will get a door once we've moved furniture into the room. But, you can tell right now that this door negates probably 70% of the soundproofing that's been done. You can still hear sound in the room directly above the theater area even though the future doorway to the theater area is not below that room. In other words, it's a major flanking path. And, that's what you're going to have if you don't treat the entire contiguous space.
> 
> If you're not looking for more than a 50% improvement, you might be able to skip one of the four basic soundproofing steps. But, you cannot do anything less than three of the four if you want to achieve something worthwhile. Believe me, I've tried. The above was just the simplified version of my story. I experimented with various corner cutting methods, only to learn that all of them resulted in too big of a loss. Corners cannot be cut to any substantial degree.


Appreciate the insights from your own experience, I'll definitely take all this into account. 

Thanks


----------



## warwwolf7

howiee said:


> Hey all. What do you do with chasing cables through walls to stop sound escaping? Is it a simple case of sealent at the point they stick trhough?


I'm also very close to be making the holes for the cables and I'm wondering the same.
Do you guys make an "S" shape with the conduit? 

Envoyé de mon LG-H873 en utilisant Tapatalk


----------



## cako

Hello everybody.

My wife is a singer and she has to train her voice daily with a digital piano accompanying her (not loudly). We have to live in an apartment floor with concrete ceilings and floors. We don't have any same floor neighbors but our upper and lower floor neighbors might be disturbed by the singing and piano playing.

Is there such a thing as soundproofing the ceiling and floor only? Or do we have to soundproof all the walls? We don't need absolute silence, only a moderate amount of reduction is enough. No bass response, because we won't play any drums or bass.

Thanks a ton!

PS. I'm sorry if this is not the proper place to ask this question.Mods, please move this to anywhere you see it fit.


----------



## DIY Guy

cako said:


> Hello everybody.
> 
> My wife is a singer and she has to train her voice daily with a digital piano accompanying her (not loudly). ...


Hi Cako,

Have you thought about a portable vocal booth? Here's a link to get you started... Vocal Booths


----------



## cako

DIY Guy said:


> Hi Cako,
> 
> Have you thought about a portable vocal booth? Here's a link to get you started... Vocal Booths


Hi Steve,

Thank you for your answer, we thought of going that route but we need to fit the piano in the booth too, she plays the piano for accompaniment and pitch reference. And booths are a little hard to ventilate afaik. She needs a lot of breath for singing etc.


----------



## DIY Guy

cako said:


> Hi Steve,
> 
> Thank you for your answer, we thought of going that route but we need to fit the piano in the booth too, she plays the piano for accompaniment and pitch reference. And booths are a little hard to ventilate afaik. She needs a lot of breath for singing etc.


Maybe sound absorption blankets would be a better idea? Blanket ideas


----------



## VAMatt

warwwolf7 said:


> I'm also very close to be making the holes for the cables and I'm wondering the same.
> Do you guys make an "S" shape with the conduit?
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


I made penetrations as small as possible and used green glue sealant to overfill the holes. I'm sure curves in any conduit that you use would be helpful as well. I'm not really qualified to make this statement, but it seems to me that it would also help if you covered the backside of the penetration with putty. I believe that would have roughly the same effect as puttying the backside of an outlet box.


----------



## warwwolf7

VAMatt said:


> I made penetrations as small as possible and used green glue sealant to overfill the holes. I'm sure curves in any conduit that you use would be helpful as well. I'm not really qualified to make this statement, but it seems to me that it would also help if you covered the backside of the penetration with putty. I believe that would have roughly the same effect as puttying the backside of an outlet box.


I could do small holes for each cables, but I'd like to future proof by using conduit. So if I want to add wires later on, it will be an easy task.

I will look into te putty option. Thank you 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## Matt Muncher

Hi People - Could I please get some advice

I am currently working on organising my theatre room for my house, it's a 19.8 x 12.3 wide room and want to soundproof it for the rest of the people in the house and the neighbours while watching movies. My layout to the rest of the house is I have a room that separates this room from the main living room and then further back is where people sleep so I don't need to really have it soundproofed for the very next room over and my neighbours are at least 30 feet away from the ext wall. I have 2 walls that are internal to the house and 2 that are external that have brick on the outside (that face the street and neighbours). It's a single story house on a concrete slab. 

My Intiatial system was going to be 


Fibreglass insulation
3mm (One Pound) Mass Loaded Vinyl
Whisper Clips Ceiling and walls with Hat Channel
2 Layers of 5/8 Frychek Gyprock (Drywall) with Green Glue
Mini Split Air Con
All speakers are in room.

(which Terry Whites website is about 67 STC plus I have added the Mass Vinyl)

So I have a decision to make, If I go with the whisper clips, I going to have a smaller screen then I wanted (only by 5 inches and my back row of seats needs to be reduced from by one from 4 to 3 because of sight lines of speakers just in front of the screen which is a little painful)

So my questions is how much of a difference is the clips going to make, my expecatation is I want to listen to movies at a level I at least feel the bass a little (don't need my body rocking) without it affecting the people around me as much). Has anybody got the setup without the clips and does it still work?

Thanks Heaps


----------



## VAMatt

Matt Muncher said:


> Hi People - Could I please get some advice
> 
> I am currently working on organising my theatre room for my house, it's a 19.8 x 12.3 wide room and want to soundproof it for the rest of the people in the house and the neighbours while watching movies. My layout to the rest of the house is I have a room that separates this room from the main living room and then further back is where people sleep so I don't need to really have it soundproofed for the very next room over and my neighbours are at least 30 feet away from the ext wall. I have 2 walls that are internal to the house and 2 that are external that have brick on the outside (that face the street and neighbours). It's a single story house on a concrete slab.
> 
> My Intiatial system was going to be
> 
> 
> Fibreglass insulation
> 3mm (One Pound) Mass Loaded Vinyl
> Whisper Clips Ceiling and walls with Hat Channel
> 2 Layers of 5/8 Frychek Gyprock (Drywall) with Green Glue
> Mini Split Air Con
> All speakers are in room.
> 
> (which Terry Whites website is about 67 STC plus I have added the Mass Vinyl)
> 
> So I have a decision to make, If I go with the whisper clips, I going to have a smaller screen then I wanted (only by 5 inches and my back row of seats needs to be reduced from by one from 4 to 3 because of sight lines of speakers just in front of the screen which is a little painful)
> 
> So my questions is how much of a difference is the clips going to make, my expecatation is I want to listen to movies at a level I at least feel the bass a little (don't need my body rocking) without it affecting the people around me as much). Has anybody got the setup without the clips and does it still work?
> 
> Thanks Heaps


Why are you going to lose so much to the clips? There should be a way to lose almost nothing, generally by recessing them on blocks so that they extend just beyond the regular studs/joists.


----------



## jcr159

VAMatt said:


> Why are you going to lose so much to the clips? There should be a way to lose almost nothing, generally by recessing them on blocks so that they extend just beyond the regular studs/joists.


very true, though an alternative is to use the hush raft blocks from isostore

that said, when you use their system you typically need a one by three or one by four to hang the drywall and end up losing that 3/4 of an inch also.


----------



## AudioVideoManiac

I've been lurking around here now for a little while and please forgive me, I couldn't find an answer to all my questions. First theater build here, so newbie questions. I'm getting close to have the electrician come in and do some wiring for the new theater. I've framed it with double 2x4 walls on 2 of the sides with a 1 1/2" gap between them, and the other two are up against concrete in the basement and are about 2-3 inches away from the concrete up against insulation. My thoughts were using 5/8" DD with GG between them on resilient channel. Questions I have are:

Are isolation clips going to make a tremendous amount of difference for the money?
Can I install the 2x2 framing for the "cove" ceiling around the outside of the room before I drywall? I have an exposed duct I have to work around.
What outlet boxes or light fixture boxes are you using that will extend far enough out to cover the thickness of all of these?

Any help would be greatly appreciated. Tia.

Pete














?


----------



## VAMatt

AudioVideoManiac said:


> I've been lurking around here now for a little while and please forgive me, I couldn't find an answer to all my questions. First theater build here, so newbie questions. I'm getting close to have the electrician come in and do some wiring for the new theater. I've framed it with double 2x4 walls on 2 of the sides with a 1 1/2" gap between them, and the other two are up against concrete in the basement and are about 2-3 inches away from the concrete up against insulation. My thoughts were using 5/8" DD with GG between them on resilient channel. Questions I have are:
> 
> Are isolation clips going to make a tremendous amount of difference for the money?
> Can I install the 2x2 framing for the "cove" ceiling around the outside of the room before I drywall? I have an exposed duct I have to work around.
> What outlet boxes or light fixture boxes are you using that will extend far enough out to cover the thickness of all of these?
> 
> Any help would be greatly appreciated. Tia.
> 
> Pete
> View attachment 3079333
> View attachment 3079334
> ?
> 
> View attachment 3079333
> View attachment 3079334


I'm far from a soundproofing expert, but I did just complete (mostly) a build, and I am a professional home improvement contractor. So, I know at least a little bit. 

In theory, you do not need clips on double stud walls. The double stud construction has already taken care of the decoupling. However, I can see in your pictures that your wall framing is attached to the joists. So, you've negated much of that decoupling. In that case, you may want to use clips and channel. Also, I see no decoupling done to the ceiling, so you'll want clips and channel there. 

I don't quite understand your question about "cove" ceiling. But, if you're talking about boxing around a duct, you're likely not going to have a choice, you'll have to frame that out before drywall because you won't be able to drywall behind a duct. Like everything, you'll want to make sure that your framing is decoupled in some way. 

Final note - I did a lot in the way of soundproofing, except for decoupling. I did very little decoupling. I made this decision to save time and money, and I am happy with my performance (I was looking for about a 50% reduction in sound leaving my room, achieved more than that). However, it is clear to me after testing that decoupling is very important if you want to achieve great isolation. It isn't just something that these hardcore theatre guys on here talk about for the hell of it. It really does have to be done and done well if you want to get maximum performance out of your soundproofing solution. So, even if you have to backtrack to fix mistakes, do it, if you want great soundproofing.


----------



## Matt Muncher

VAMatt said:


> Why are you going to lose so much to the clips? There should be a way to lose almost nothing, generally by recessing them on blocks so that they extend just beyond the regular studs/joists.


The Clips and Hat Channel add 3.3 Inchs (8cms) to the room and i can't believe it but that 8cms is the difference between the screen I want the next size down (including frame). Yeah I could block them but for 150+ clips does seem painful. I am limited to the tpyes of clips I can get because I live in Australia and there aren't many local dealers here that do them and not everyone ships from the US (re the hush raft blocks)

So from reading the thread (a good 5 hours), it does seem that clips are a big part of the system (around 15 to 20 STC) and help with the low frequencies even with the distances I'm working with to the neighbours and family, would that be right? I also learnt that MLV is actually not going to add much value once I have done, clips, DD+GG, is that also right (couldn't find any research/STC stats to back that up) but if that is right with it not adding much, it would save me $3000 Australian, which is a big saving.


----------



## warwwolf7

Matt Muncher said:


> The Clips and Hat Channel add 3.3 Inchs (8cms) to the room and i can't believe it but that 8cms is the difference between the screen I want the next size down (including frame). Yeah I could block them but for 150+ clips does seem painful. I am limited to the tpyes of clips I can get because I live in Australia and there aren't many local dealers here that do them and not everyone ships from the US (re the hush raft blocks)
> 
> So from reading the thread (a good 5 hours), it does seem that clips are a big part of the system (around 15 to 20 STC) and help with the low frequencies even with the distances I'm working with to the neighbours and family, would that be right? I also learnt that MLV is actually not going to add much value once I have done, clips, DD+GG, is that also right (couldn't find any research/STC stats to back that up) but if that is right with it not adding much, it would save me $3000 Australian, which is a big saving.


Gg is probably the first one in the list you could drop if you want to save money.

Dd and clip+channels will make the most difference.

It's been test a lot, and as long as you fill the entire surface of the joist cavity, with at least 50% of the depth with mineral wool, that will give you good return on investment.

Then if you have more money, the double drywall under the above floor.
More money? 
Then add green glue

The poster above was mixing soundproofing and isolation. Those are 2 completely different aspects. Sprayed urethane is good for isolation, soundproofing, not so much.


For your duct, whatever you do to hide it, treat it exactly as the rest of your ceiling. If you are using clip+channel, do the same there. Other, you are probably not going to get much value in installing clip and channel for the rest 9f the ceiling

1 : Mass = drywall 
2: Decoupling = clips and channel 

This provides Very little soundproofing, but very important step to prevent cavity resonance 
3: Mineral wool = absorption 

Then, the least effective in my opinion. (I bought it even though I'm not 100% convinced, but I didn't want to live with an "what if I did gg?" 
4 : Green glue = damping

This is also very important. If you neglect it it will after the entire work : Flanking path. If your room is not sealed, or you have "sound conductive material" that shares the home theater and another room, the soundproofing will be compromised. I illustrate that lime this :
It only takes a small percentage of opening a window on a car to get 90% of the sound level outside of the car. 


Choose carefully, attention to details will define the end result of the soundproofing of your room. If you really want that size of screen AND best money return, do the blocking between the joist. I'm sure you don't have 150clips on the ceiling. Unless your room is 25' x 30'.

Happy soundproofing 

Envoyé de mon LG-H873 en utilisant Tapatalk


----------



## Matt Muncher

warwwolf7 said:


> Gg is probably the first one in the list you could drop if you want to save money.
> 
> Dd and clip+channels will make the most difference.
> 
> It's been test a lot, and as long as you fill the entire surface of the joist cavity, with at least 50% of the depth with mineral wool, that will give you good return on investment.
> 
> Then if you have more money, the double drywall under the above floor.
> More money?
> Then add green glue
> 
> The poster above was mixing soundproofing and isolation. Those are 2 completely different aspects. Sprayed urethane is good for isolation, soundproofing, not so much.
> 
> 
> For your duct, whatever you do to hide it, treat it exactly as the rest of your ceiling. If you are using clip+channel, do the same there. Other, you are probably not going to get much value in installing clip and channel for the rest 9f the ceiling
> 
> 1 : Mass = drywall
> 2: Decoupling = clips and channel
> 
> This provides Very little soundproofing, but very important step to prevent cavity resonance
> 3: Mineral wool = absorption
> 
> Then, the least effective in my opinion. (I bought it even though I'm not 100% convinced, but I didn't want to live with an "what if I did gg?"
> 4 : Green glue = damping
> 
> This is also very important. If you neglect it it will after the entire work : Flanking path. If your room is not sealed, or you have "sound conductive material" that shares the home theater and another room, the soundproofing will be compromised. I illustrate that lime this :
> It only takes a small percentage of opening a window on a car to get 90% of the sound level outside of the car.
> 
> 
> Choose carefully, attention to details will define the end result of the soundproofing of your room. If you really want that size of screen AND best money return, do the blocking between the joist. I'm sure you don't have 150clips on the ceiling. Unless your room is 25' x 30'.
> 
> Happy soundproofing
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


Thank you, so mass loaded vinyl is a waste then?

Is more the width i need for the room, doing this on the walls and ceiling.


----------



## VAMatt

Matt Muncher said:


> Thank you, so mass loaded vinyl is a waste then?
> 
> Is more the width i need for the room, doing this on the walls and ceiling.


I don't think anyone would say its a waste, as it does add mass. It just isn't the preferred method of adding mass. 

I used MLV to wrap some ducts inside the ceiling of my room. It's good for that kind of thing.


----------



## Elill

Matt Muncher said:


> The Clips and Hat Channel add 3.3 Inchs (8cms) to the room and i can't believe it but that 8cms is the difference between the screen I want the next size down (including frame). Yeah I could block them but for 150+ clips does seem painful. I am limited to the tpyes of clips I can get because I live in Australia and there aren't many local dealers here that do them and not everyone ships from the US (re the hush raft blocks)
> 
> So from reading the thread (a good 5 hours), it does seem that clips are a big part of the system (around 15 to 20 STC) and help with the low frequencies even with the distances I'm working with to the neighbours and family, would that be right? I also learnt that MLV is actually not going to add much value once I have done, clips, DD+GG, is that also right (couldn't find any research/STC stats to back that up) but if that is right with it not adding much, it would save me $3000 Australian, which is a big saving.


Don't skimp on it. Its the single most important element. Mass and damping can be added later. Effective isolation cant.

Rondo make a good clip - Acoustic Assemblies | Rondo


----------



## cako

DIY Guy said:


> Hi Cako,
> 
> Have you thought about a portable vocal booth? Here's a link to get you started... Vocal Booths


Hi again!

Sorry for the long pause. After some thinking, the conclusion was to build a room inside a room, with the cheapest options in hand.

So we had it done.



Now we are finishing the room, covering the cracks with plaster. I also started building some panels for the reverberation.





After everything is done, if the absorption is not enough I will try to find some EPDM membranes.

Not what I intented at first but sometimes there's no easy way.

Cheers!


----------



## VAMatt

cako said:


> Hi again!
> 
> Sorry for the long pause. After some thinking, the conclusion was to build a room inside a room, with the cheapest options in hand.
> 
> So we had it done.
> 
> 
> 
> Now we are finishing the room, covering the cracks with plaster. I also started building some panels for the reverberation.
> 
> 
> 
> 
> 
> After everything is done, if the absorption is not enough I will try to find some EPDM membranes.
> 
> Not what I intented at first but sometimes there's no easy way.
> 
> Cheers!


How big will the room be?

At the end of the day, you now have a great solution. Lots of work, sure. But, much better than a portable vocal booth, I'd say.


----------



## Nj6964

*Soundproofing below subfloor nails:*
I’m finishing my basement and will include a home theater. I have to use a drop ceiling due to accessing items in ceiling and future modifications.

I’d like to put 2 layers of 5/8” drywall against the subfloor from below but there are a million nails poking an inch through due to my hardwood floor on 1st floor.

My plan is to put the double drywall w greenglue sitting just below those nails. I’m wondering should I leave empty air in this nail space or pack in fiberglass insulation or rockwool? If the drywall isn’t greenglued right up against the subfloor will this plan even work?

Also, my main concern is noise from above being bothersome. No so much noise escaping from the basement.

Thanks for any advice!
Mike


----------



## jcr159

Does anyone have experience with the GenieMatt product?









GenieMat® RST


Can be installed under all flooring types Used to isolate impact footfall and airborne noise Lead Time: Small orders of GenieMat RST02, RST05, RST10, and RST12 ship from our warehouse in Indiana for delivery within 1-5 business days. Larger orders might ship direct from the manufacturer in Canada.




isostore.com





my basement is finished, technically in the process of being finished, and next is to replace the floors upstairs and above it. The floors above are a mixture of hardwood and carpet. Wondering if adding this product will make much difference overall.


----------



## rfbrang

Matt Muncher said:


> s seem that clips are a big part of the system (around 15 to 20 STC) and help with the low frequencies even with the distances I'm working with to the neighbours and family, would that be right? I also learnt that MLV is actually not going to add much value once I have done, clips, DD+GG, is that also right (couldn't find any research/STC stats to back that up) but if that is right with it not adding much, it would save me $3000 Australian, which is a big saving.


It looks like others have already spoken to the clips and channel being a good idea, so I will comment on the mlv. Price wise it does not makes sense unless you need something that will fit in 1/4" space and be more flexible than drywall. Dynamat is about the same price, works for pipes, is equally heavy, and sticks well if you need something fairly flexible.

- If you only have access to one side of a wall, you can cut up mlv and glue it to the back of the neighbors wall between the studs. I would contact your neighbors before you try that because construction adhesive might smell bad for a while. We have a basement stairwell with 1/2" sheetrock installed by our builder. I added 2 layers of sheetrock with gg between the studs since our stairwell does not have the room to add another layer within the stairwell. Got the idea from Brolic Beast, he has a video series showing the install. (maybe Brolic media on youtube???) 

- 1lb mlv on the back of your 2 layers of sheetrock + gg will not do much. I don't remember the specifics of it, but there is a curve that says something about doubling the weight to get 1 or 2 octaves lower. So if you only have access to your side, it would be 4 layers of sheetrock to double the weight. 

- As you make your walls thicker to get an improvement you might or might not be able to hear, you give up the flexibility of the sheetrock which is needed for internal cancellation of energy that the green glue facilitates. So your assembly becomes less effective, you have to pay for the additional weight, and it doesn't add very much bang for your buck.

- My immediate use case for MLV is in flooring assemblies for impact noise. if you are putting down hardwood and have a theatre below.

- You can technically use many layers of MLV glued together for very heavy and extremely expensive walls.

- There is another use case with a 1ft thick wall filled with many layers of MDF, MLV, and activated carbon. One online vendor suggests this, but I have not seen any independent testing at all, and the materials seem like a toxic spill if there was ever a water or fire event. I did buy diffuser plans from that site which are interesting, but they are filled with build errors between the purchase parts page and where it actually references parts to be installed.


----------



## rfbrang

jcr159 said:


> Does anyone have experience with the GenieMatt product?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> GenieMat® RST
> 
> 
> Can be installed under all flooring types Used to isolate impact footfall and airborne noise Lead Time: Small orders of GenieMat RST02, RST05, RST10, and RST12 ship from our warehouse in Indiana for delivery within 1-5 business days. Larger orders might ship direct from the manufacturer in Canada.
> 
> 
> 
> 
> isostore.com
> 
> 
> 
> 
> 
> my basement is finished, technically in the process of being finished, and next is to replace the floors upstairs and above it. The floors above are a mixture of hardwood and carpet. Wondering if adding this product will make much difference overall.


For carpet, compare it against memory foam carpet pads. I would think it is not a good solution.

For hardwood, yes. But you need to plan out how the additional height to the subfloor will effect your trim, doors, and transitions between hardwood and carpet.


----------



## rfbrang

Nj6964 said:


> *Soundproofing below subfloor nails:*
> I’m finishing my basement and will include a home theater. I have to use a drop ceiling due to accessing items in ceiling and future modifications.
> 
> I’d like to put 2 layers of 5/8” drywall against the subfloor from below but there are a million nails poking an inch through due to my hardwood floor on 1st floor.
> 
> My plan is to put the double drywall w greenglue sitting just below those nails. I’m wondering should I leave empty air in this nail space or pack in fiberglass insulation or rockwool? If the drywall isn’t greenglued right up against the subfloor will this plan even work?
> 
> Also, my main concern is noise from above being bothersome. No so much noise escaping from the basement.
> 
> Thanks for any advice!
> Mike



For airborne noise between floors, it works well. For kids running around like a bull, doesn't do much. 
Spend the time and bang the staples flat before you attempt to install. You do want the green glue to be touching both the subfloor and sheetrock for the green glue to dampen the energy in the floor. If it is just hanging between the joists like on I-joist blocking, the green glue cannot do its job. 
Last I looked,Ted said the caulking at the edges doesn't do much as the subfloor is already sealed for air. Can do it if you want.
You want insulation in there for resonance, 3-6" is all you need. 
If you have ductwork, you can either replace sections with flex duct before it goes upstairs, or use dynamat before it turns upstairs and on the main trunk lines. 
Do yourself a favor and verify your joists can hold the extra weight. Live vs dead load.


----------



## rfbrang

warwwolf7 said:


> I'm also very close to be making the holes for the cables and I'm wondering the same.
> Do you guys make an "S" shape with the conduit?
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


Have the conduit terminate in a box. Use putty pads on the outside of a electric box and up the first few inches of the conduit. Only use low voltage cables in the box and stuff a bit of fiberglass in the neck of the conduit to prevent sound.

Prior suggestions is to just run the wires through the wall shell and caulk them with acoustic caulk. Conduit is for future expansion.

If you are going full theatre with soffits and columns. Build your shell as close to 100% as you can and use the soffits and columns to run the conduit and power inside the shell. Should only have 4 penetrations. Door, air in, air out, small opening for wires to go inside and outside your theatre. All but the door should open behind the soffit and the soffit should be filled with insulation to prevent the conduit from resonating.


----------



## mhutchins

Nj, you really want your drywall up against the bottom of the flooring, which means you need to address those nails. Ideally you need to cut them flush with the underside of the subfloor. There are a number of ways to do this, but I think the most common is to use a small angle grinder to cut/abrade them off flush. You want to bond the first layer of drywall with Green Glue to the underside of the subfloor to achieve maximal impact isolation. If you leave the drywall proud of the nails, you run the risk of creating a “third leaf” effect which can actually reduce your sound isolation.

Mike


----------



## VAMatt

Nj6964 said:


> *Soundproofing below subfloor nails:*
> I’m finishing my basement and will include a home theater. I have to use a drop ceiling due to accessing items in ceiling and future modifications.
> 
> I’d like to put 2 layers of 5/8” drywall against the subfloor from below but there are a million nails poking an inch through due to my hardwood floor on 1st floor.
> 
> My plan is to put the double drywall w greenglue sitting just below those nails. I’m wondering should I leave empty air in this nail space or pack in fiberglass insulation or rockwool? If the drywall isn’t greenglued right up against the subfloor will this plan even work?
> 
> Also, my main concern is noise from above being bothersome. No so much noise escaping from the basement.
> 
> Thanks for any advice!
> Mike


When I asked about this a few months ago, I was advised to cut all of the nails off. I assume these are from hardwood flooring above, correct? If so, a grinder should make quick work of those nails. We're talking a fraction of a second each. I'm a professional contractor, but I don't think it should be particularly difficult for anyone with sufficient skills to DIY a basement to handle this. Of course, you'll want good eye protection (critical if you want to be able to see in the future), and maybe a ski mask type thing or something else for general face protection (nice if you want to slow down the flying nails).

This is a very important step for reducing noise from above, especially if you're not doing DD/GG for your ceiling. I'm not an expert on soundproofing, but I do not think you would get anywhere near the same results by floating that drywall below the existing nails. But, if you were to do that, I think packing insulation in the void would make sense. 

Now that I'm thinking this through, it seems to me that it would be easier to cut off all the nails than it would be to float the drywall below the nails. 

Good luck!


----------



## Nj6964

Thanks everyone for the quick responses. Sounds like the solution is to grind off the nails.

On the soundproof co website they show DD/GG against the subfloor as part of the Best solution, however they don’t show it alone. Will the drywall against subfloor provide sufficient soundproofing from footfall noise that it’s worth it even with a drop ceiling below? Also, would this help dampen noise from my creaky almost 100 year old floor?

edit: I’m glad rfbrang mention checking the floors capacity. My 2x10 joists are almost 100 yrs old. I see online that most floors are made for 10-12 lb/sf. Hardwood flooring 2.8 + 3/4 pine subfloor 1.9 = ~5 lb/sf. 2 layers of 5/8=4.4. Add on the ceiling brings me very close to 10 or 11 lb/sf. Before considering any framing load of my 2nd floor in certain areas.

2 questions:
-is this analysis ridiculous and I likely have nothing to worry about.
-Any other, less ideal solutions that won’t add so much weight? Is it not even worth it to use 2 layers of thinner drywall say 1/4 or 3/8”.
-would it make sense to use one layer of quiet rock w GG against the subfloor? That’s basically the same as 2 layers of 1/4” right, but with the middle viscoelastic layer perfectly distributed.

thanks again!


----------



## VAMatt

Nj6964 said:


> Thanks everyone for the quick responses. Sounds like the solution is to grind off the nails.
> 
> On the soundproof co website they show DD/GG against the subfloor as part of the Best solution, however they don’t show it alone. Will the drywall against subfloor provide sufficient soundproofing from footfall noise that it’s worth it even with a drop ceiling below? Also, would this help dampen noise from my creaky almost 100 year old floor?
> 
> edit: I’m glad rfbrang mention checking the floors capacity. My 2x10 joists are almost 100 yrs old. I see online that most floors are made for 10-12 lb/sf. Hardwood flooring 2.8 + 3/4 pine subfloor 1.9 = ~5 lb/sf. 2 layers of 5/8=4.4. Add on the ceiling brings me very close to 10 or 11 lb/sf. Before considering any framing load of my 2nd floor in certain areas.
> 
> 2 questions:
> -is this analysis ridiculous and I likely have nothing to worry about.
> -Any other, less ideal solutions that won’t add so much weight? Is it not even worth it to use 2 layers of thinner drywall say 1/4 or 3/8”.
> -would it make sense to use one layer of quiet rock w GG against the subfloor? That’s basically the same as 2 layers of 1/4” right, but with the middle viscoelastic layer perfectly distributed.
> 
> thanks again!


You'd need an engineer to really evaluate that. But, I can tell you that it is highly unlikely that you're going to have trouble, unless you already know of or suspect something isn't right. 

Think about this - if you and your family stand upstairs and hug each other, are you going to worry about falling through the floor? If you have a party and there are 20 people in that room, are you going to be concerned?

Your 100 year old joists are not concerning to me, unless you believe them to be in bad shape. They're probably actual 2x10, rather than 1.5x9.25 like modern framing. If you have a bathtub above, or those joists span a long distance, or you have noticeable deflection in the floor above, you may want to think a bit more about it. But, I'd bet heavily, with no more information than I have right now, that you can add DD+GG to the subfloor, DD+GG from the bottom of the joists, put a grand piano on the floor above, have your whole family get in the room and jump up and down, and nothing bad would happen.


----------



## Nj6964

VAMatt said:


> You'd need an engineer to really evaluate that. But, I can tell you that it is highly unlikely that you're going to have trouble, unless you already know of or suspect something isn't right.
> 
> Think about this - if you and your family stand upstairs and hug each other, are you going to worry about falling through the floor? If you have a party and there are 20 people in that room, are you going to be concerned?
> 
> Your 100 year old joists are not concerning to me, unless you believe them to be in bad shape. They're probably actual 2x10, rather than 1.5x9.25 like modern framing. If you have a bathtub above, or those joists span a long distance, or you have noticeable deflection in the floor above, you may want to think a bit more about it. But, I'd bet heavily, with no more information than I have right now, that you can add DD+GG to the subfloor, DD+GG from the bottom of the joists, put a grand piano on the floor above, have your whole family get in the room and jump up and down, and nothing bad would happen.


Thanks! I’m likely being overly cautious.
Another question I had was in low profile decoupling. I’m going to be using a drop ceiling system that screws to the bottom of the joists for only a 1” drop. Would it make sense to put mass loaded vinyl or green glue between this drop ceiling member and the joist? Or is this a waste of time?


----------



## mhutchins

Waste of time. You’d be much better off screwing drywall to the joists than a drop ceiling system, but you probably know that.....


----------



## Nj6964

mhutchins said:


> Waste of time. You’d be much better off screwing drywall to the joists than a drop ceiling system, but you probably know that.....


Yes you’re 100% right, I’d much rather put drywall on the joists but I want to maintain accessibility to all the stuff in my ceiling for the future.


----------



## Rjloper9

I built the front wall, which will be behind my screen baffle wall, using 24 oc framing with the idea of only doing 2 layers of 5/8” drywall.

Now I’m considering doing a 3rd layer. Could I get away with this if I add some blocking between the vertical studs or should I just stick with 2?










Sent from my iPhone using Tapatalk


----------



## howiee

Hey guys. We're building a room within a room and I'm trying to work out whether to keep the speaker cabling internal, or chase it through the walls and treat the holes. We were advised to keep penetration points to a minimum and use on wall power sockets etc and i'm guessing this applies to speaker cabling too. The rack and equipment are inside the room, so if any cabling were to be chased through the walls it'd have to leave the room and come back in. The concern is neatness - chasing internal wiring through conduit won't look that great (although the plan is to eventually cover everything in fabirc so that will be hidden) - vs compromising the effort spent in soundproofing.

Any thoughts or suggestions to minimise the impact if chasing cabling through the wall? Is there a standard approach?


----------



## pkinneb

Standard outlet boxes with putty pads and Green Glue Acoustical sealant (or similar) for direct intrusions. BTW if you still have the opportunity I would rethink the equipment rack inside the room. Heat and noise issues can be solved much cheaper and easier by having it outside the theater.


----------



## mhutchins

howiee said:


> Hey guys. We're building a room within a room .....


I would stick with on-wall power outlets as much as possible, same with switches, especially since you are planning to hide it all behind fabric at some point. I would not rely on in-wall outlets with putty pads if your goal is to maximize isolation. Rather, use backer boxes built to the same specs as your wall and use long-life caulk where the wires come through the backer box.

I agree with @pkinneb about moving your rack outside your room enclosure, especially if any of your equipment has cooling fans. If you really want to keep the equipment inside the room, build a closet that you can soundproof to minimize the noise. Of course, this will mean that you have to ventilate/cool the closet, but that can be accomplished using known techniques. Moving your gear outside the room will increase the number of penetrations through the envelope, but small holes with just one wire can be easily caulked with minimal loss of sound isolation.

Mike


----------



## Rjloper9

Can an isolated 16’x9’ wall built with 24” oc framing support the weight of 3 layers of 5/8” drywall?


Sent from my iPhone using Tapatalk


----------



## howiee

pkinneb said:


> Standard outlet boxes with putty pads and Green Glue Acoustical sealant (or similar) for direct intrusions. BTW if you still have the opportunity I would rethink the equipment rack inside the room. Heat and noise issues can be solved much cheaper and easier by having it outside the theater.


Thanks pkinneb. Having the rack outside the room would solve an issue for sure and there's a spare room behind the cinema space that could potentially house one. This would mean going down the rabbit hole of controlling things remotely, though, which I have zero experience in. We plan on having various game consoles and an htpc which might be an issue. I suppose they could stay in the cinema with hdmi leads feeding to the rack and then back in?












mhutchins said:


> I would stick with on-wall power outlets as much as possible, same with switches, especially since you are planning to hide it all behind fabric at some point. I would not rely on in-wall outlets with putty pads if your goal is to maximize isolation. Rather, use backer boxes built to the same specs as your wall and use long-life caulk where the wires come through the backer box.
> 
> I agree with @pkinneb about moving your rack outside your room enclosure, especially if any of your equipment has cooling fans. If you really want to keep the equipment inside the room, build a closet that you can soundproof to minimize the noise. Of course, this will mean that you have to ventilate/cool the closet, but that can be accomplished using known techniques. Moving your gear outside the room will increase the number of penetrations through the envelope, but small holes with just one wire can be easily caulked with minimal loss of sound isolation.
> 
> Mike


Cheers Mike and noted re. power outlouts and light switches. I'm a bit confused re. backer boxes. Do you mean for speakers?

I must admit I hadn't thought about heat and noise from the rack (grey box next to the back row). We are having an mvhr unit which will be pumping in fresh air, but i'm not sure how much if any impact that will have on keeping equipment cool.


----------



## mhutchins

howiee said:


> .
> .
> Cheers Mike and noted re. power outlouts and light switches. I'm a bit confused re. backer boxes. Do you mean for speakers?


Here is a post from BIGmouthinDC that shows backer boxes for lighting and putty pads around outlet boxes. The concept for backer boxes around outlet boxes is the same, just use a smaller box. The wood box is lined with cement board or drywall to provide a degree of fire proofing. Green Glue is used between the wood and drywall layers of the backer box. A flange is added (as seen in the overhead backer box) for caulking between the backer box and the first layer of drywall. 

Larger boxes are connected directly to the hat channel, whereas smaller outlet boxes can be screwed directly to the drywall when the 1st layer of drywall is installed. You can also use DC04 clips to support the backer boxes from the framing, which will keep everything decoupled.

Mike


----------



## VAMatt

Rjloper9 said:


> Can an isolated 16’x9’ wall built with 24” oc framing support the weight of 3 layers of 5/8” drywall?
> 
> 
> Sent from my iPhone using Tapatalk


Assuming you're using 2x4 framing, the answer is yes. Honestly, 2x4 walls can hold any amount of drywall that you might reasonably want to put on them, even at 24"oc.


----------



## pkinneb

howiee said:


> Thanks pkinneb. Having the rack outside the room would solve an issue for sure and there's a spare room behind the cinema space that could potentially house one. This would mean going down the rabbit hole of controlling things remotely, though, which I have zero experience in. We plan on having various game consoles and an htpc which might be an issue. I suppose they could stay in the cinema with hdmi leads feeding to the rack and then back in?


The reason I bring it up is it was the biggest mistake I made in my build, and in my case @BIGmouthinDC advised me to do it but it was the one thing I didn't do becuase I too was concerned about operating equipment from another room, which I had never done. Funny thing is now with my NAS storage we rarely use physical media and I run everything off my iPhone via the Harmony Elite Hub. Which is really quite simple once you get the activities set up.

FWIW the issues I had were heat and light, both have been solved but I had to throw money and time at it that would not have been necessary had I just heeded BIG's advice


----------



## Technology3456

Can anyone advise, for a projector shelf in the very limited options available for the size I'm looking for, what type of material would be best for:

1. limiting heat
2. limiting sound from (two) projectors?

All of them are very open shelves, and most the shelves are wire so even they ventilate, others are solid shelves but open everywhere else. but I would still like to pick the best material for these two things. The choices are:

1. Heavy duty steel shelving Heavy Duty Metal Shelving, Heavy Duty Steel Shelving in Stock - ULINE
2. Industrial steel shelving Steel Storage Shelves, Industrial Steel Shelving in Stock - ULINE
3. Whatever this one is made of Heavy-Duty Boltless Shelving in Stock - Uline
4. Chrome wire shelving Chrome Shelving, Chrome Wire Shelving, Chrome Wire Storage in Stock - ULINE
5. Black wire shelving Black Shelving, Black Wire Shelving, Black Wire Racks in Stock- ULINE
6. Epoxy wire shelving Epoxy Wire Shelving, Epoxy Coated Wire Shelving in Stock - ULINE
7. Solid galvanized steel shelving Solid Galvanized Steel Shelving in Stock - ULINE
8. Solid stainless steel shelving Solid Stainless Steel Shelving in Stock - ULINE
9. Stainless steel wire shelving Stainless Steel Shelves, Stainless Steel Wire Shelving in Stock - ULINE

All of these come in similar sizes or I can probably add more shelves to the one that doesn't, and these are really the only thing I can find that come in the size I need. Which would you recommend?


----------



## howiee

mhutchins said:


> Here is a post from BIGmouthinDC that shows backer boxes for lighting and putty pads around outlet boxes. The concept for backer boxes around outlet boxes is the same, just use a smaller box. The wood box is lined with cement board or drywall to provide a degree of fire proofing. Green Glue is used between the wood and drywall layers of the backer box. A flange is added (as seen in the overhead backer box) for caulking between the backer box and the first layer of drywall.
> 
> Larger boxes are connected directly to the hat channel, whereas smaller outlet boxes can be screwed directly to the drywall when the 1st layer of drywall is installed. You can also use DC04 clips to support the backer boxes from the framing, which will keep everything decoupled.
> 
> Mike


Cheers again Mike. That's very handy! Recessed lights have been a concern this looks like the way to go.



pkinneb said:


> The reason I bring it up is it was the biggest mistake I made in my build, and in my case @BIGmouthinDC advised me to do it but it was the one thing I didn't do becuase I too was concerned about operating equipment from another room, which I had never done. Funny thing is now with my NAS storage we rarely use physical media and I run everything off my iPhone via the Harmony Elite Hub. Which is really quite simple once you get the activities set up.
> 
> FWIW the issues I had were heat and light, both have been solved but I had to throw money and time at it that would not have been necessary had I just heeded BIG's advice


I have the same concern - controlling equipment from another room. Did you move your rack in the end? We use a nas with nvidia shield/Plex for watching most content, so that would likely work. I'd like to add an HTPC into the mix and some gaming consoles too whixch might be more tricky.


I've been looking at whether we can put the rack in the bedroom behind the cinema and it may be possible. Controlling the equipment is another matter and something i'm looking into. If it isn't and we have to have all the cabling leave the cinema room and come back in again, do you guys think it would be best to have a backer box big enough to cater for all the speaker/hdmi/power leads etc that need chasing and somehow seal them in the box? This is becoming a bit of a stickign point atm. Life will be much easier to keep everything in the room. No issues adding cabling/equipment down the line as everything is self contained. It just won't look that great!


----------



## pkinneb

howiee said:


> Cheers again Mike. That's very handy! Recessed lights have been a concern this looks like the way to go.
> 
> 
> 
> I have the same concern - controlling equipment from another room. Did you move your rack in the end? We use a nas with nvidia shield/Plex for watching most content, so that would likely work. I'd like to add an HTPC into the mix and some gaming consoles too whixch might be more tricky.
> 
> 
> I've been looking at whether we can put the rack in the bedroom behind the cinema and it may be possible. Controlling the equipment is another matter and something i'm looking into. If it isn't and we have to have all the cabling leave the cinema room and come back in again, do you guys think it would be best to have a backer box big enough to cater for all the speaker/hdmi/power leads etc that need chasing and somehow seal them in the box? This is becoming a bit of a stickign point atm. Life will be much easier to keep everything in the room. No issues adding cabling/equipment down the line as everything is self contained. It just won't look that great!


Ultimately I did not move the rack, with the room complete I wasn't willing to do that. I ended up installing some additional ACinfinity fans in the rack (top and bottom) and then played with the settings for quite some time to get them dialed in. I also added a damper to the HVAC supply and now I have it under control. For the lighting I was able to turn down the brightness on the Denon receiver but not the amp I have so I will probably take the door into a tint shop and have tint applied to the glass door. The nvidia sheild/Plex/Nas will definitely work I am not familiar with gaming or HTPC so can't help you there.


----------



## howiee

pkinneb said:


> Ultimately I did not move the rack, with the room complete I wasn't willing to do that. I ended up installing some additional ACinfinity fans in the rack (top and bottom) and then played with the settings for quite some time to get them dialed in. I also added a damper to the HVAC supply and now I have it under control. For the lighting I was able to turn down the brightness on the Denon receiver but not the amp I have so I will probably take the door into a tint shop and have tint applied to the glass door. The nvidia sheild/Plex/Nas will definitely work I am not familiar with gaming or HTPC so can't help you there.


Couldn't you just stick something over the receiver lights? That's what I did in my last place. Tinted glass door sounds cool tho!

I'd prob keep the consoles and pc in the room - so it'd be a case of chasing 4 or so hdmi cables in, which shouldn't be too hard to seal. Cheers for the advice - i've got plenty to think about.


----------



## Technology3456

Edit: deleted because not a big enough difference between options I was considering to wait on a decision any longer, so no need to ask anymore about it.


----------



## T-Bone

Technology3456 said:


> Projector stand final faceoff. Which material will reflect less light and sound?
> 
> Chrome Shelving, Chrome Wire Shelving, Chrome Wire Storage in Stock - ULINE
> 
> *VERSUS*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Black Shelving, Black Wire Shelving, Black Wire Racks in Stock - ULINE
> 
> 
> Uline stocks a wide selection of Black Wire Shelving. Order by 6 p.m. for same day shipping. Huge Catalog! Over 40,000 products in stock. 12 Locations across USA, Canada and Mexico for fast delivery of Black Wire Shelving.
> 
> 
> 
> 
> www.uline.com
> 
> 
> 
> 
> 
> Shelves are adjustable if anyone is looking for the same thing, and you can add an extra shelf I think.


This is the soundproofing master thread. You would be doing better if you post in the appropriate thread.

-T


----------



## Technology3456

T-Bone said:


> This is the soundproofing master thread. You would be doing better if you post in the appropriate thread.
> 
> -T


T-Bone I totally understand your reaction, and I confess I had no idea where to post it. There are only two major differences between the materials, and one of them is how much it reflects sound, so that's why I hoped this would be the best place to post it. If you know a better thread, I will delete the content of the comment and post there.


----------



## Chuck Miller

I'm building my theater as a "room within a room" using double stud configuration. Where there are doors in the room (I have too many, but can't avoid it), and I'm going to install solid doors with seals all around, does it matter if the door is installed in the HT wall or in the wall on the other side? I can imagine that installing on the HT side might reduce noise to the adjacent area, but with also wanting to reduce noise coming into the HT, does it really matter? 

Thanks,

Chuck


----------



## Chuck Miller

Also, I need to treat this large ductwork that will be behind a screen wall. I'm thinking I can isolate it with clips & soffit, insulate it well and use
DD with GG. I can't tackle replacing it all with flexible duct. As long as I decouple it from the walls, it should be OK, in my opinion. Do I need to cover it with Dynamat or is that redundant and unnecessary? Other thoughts? I know it's not ideal...










I'm also looking for resources to determine how to balance air flow in the HT. I'll for sure be installing a dead vent to pull air out of the space. But I'm not sure if I need to install a similar dead vent to supply air to the room? Or should I just leave my HVAC fan running continuously to supply air?

Cheers!

Chuck


----------



## Technology3456

Chuck Miller said:


> Also, I need to treat this large ductwork that will be behind a screen wall. I'm thinking I can isolate it with clips & soffit, insulate it well and use
> DD with GG. I can't tackle replacing it all with flexible duct. As long as I decouple it from the walls, it should be OK, in my opinion. Do I need to cover it with Dynamat or is that redundant and unnecessary? Other thoughts? I know it's not ideal...
> 
> View attachment 3087941
> 
> 
> I'm also looking for resources to determine how to balance air flow in the HT. I'll for sure be installing a dead vent to pull air out of the space. But I'm not sure if I need to install a similar dead vent to supply air to the room? Or should I just leave my HVAC fan running continuously to supply air?
> 
> Cheers!
> 
> Chuck


The other stuff is above my pay grade. Even this is but I will weigh in. If you have the option at this stage to get air in and out of the room, not just out, I would probably take that. I dont see any reason you'd regret having it... you could just cover the vent if you did... but you might regret not having it. A lot of people finish their theaters and then when it's too late they wish they'd done various things such as this. Some even tear parts down just to put the thing back in. You can just do it now, so might be worth it. But if there are downsides that cannot be fixed by covering it in the event you don't like it, others can chime in because I wouldn't know about that.


----------



## mhutchins

You definitely want a dedicated supply and return for air circulation in the theater.

With regards to the long duct run through the theater: your best bet is to enclose the duct in a soffit built to the same standards as the theater walls. For example, if you are using double 5/8" Type-X drywall with Green Glue for the walls, then the duct enclosure should be constructed the same way.

Mike


----------



## VAMatt

I did as Mike suggests - built a soffit around the duct to the same standard as the rest of my room. It definitely does not seem to be a weak point in my soundproofing.


----------



## Chuck Miller

Thanks guys. You've confirmed my plan!


----------



## zafta

Hello guys,

Regardless the price, I want to decide between these 2 layouts to get the best results for soundproofing my neighbor mid-wall, which is a 2x4 with 5/8 drywall on each side and glass fiber. As my neighbor doesn't want to open on his side, I will improve the wall only on my side by opening it to soundproof electrical box and even adding a tyvek. Building a second wall is not an option as it would take too much space. Total thickness after stud shall not be no more than 3-1/8"

Glass fiber batt (or mineral wool?) to fill entire studs. Having Roxul (a.k.a. Sound n' safe Rockwool) seams not a good idea as the batt is 1/2" smaller than studs and won't fill all the gap... so it could lead to the triple effect leave as in the 2 possible layouts, there will be hat channel.

a)
MDF board 1/4" on studs (1.1 lbs/sqft)
Mass loaded vinyl 1/8" on MDF (1 lbs/sqft)
Clip + hat channel (1-5/8")
Cement board 1/2" (2.24 lbs/sqft)
Green Glue
Quietrock EZ 5/8" (2.6 lbs/sqft)

Total thickness : 3-1/8"
Approx total weight per sqft : 6.94 lbs

Or...

b)
MLV 1/4" on studs (2 lbs/sqft)
Clip + hat channel (1-5/8")
Quietrock 5/8 (2.6 lbs/sqft)
Green glue
Quietrock 5/8 (2.6 lbs/sqft)

Total thickness : 3-1/8"
Total accurate weight per sqft : 7.2 lbs

The first layout seams to be a little less dense than the second one, but there are more various materials which further break frequencies... that should be an argument in favor of that layout.

Any advice or adding different materials are mostly welcome.

thanks!


----------



## mhutchins

zafta said:


> Hello guys,
> 
> Regardless the price, I want to decide between these 2 layouts to get the best results for soundproofing my neighbor mid-wall, which is a 2x4 with 5/8 drywall on each side and glass fiber. As my neighbor doesn't want to open on his side, I will improve the wall only on my side by opening it to soundproof electrical box and even adding a tyvek. Building a second wall is not an option as it would take too much space. Total thickness after stud shall not be no more than 3-1/8"
> 
> Glass fiber batt (or mineral wool?) to fill entire studs. Having Roxul (a.k.a. Sound n' safe Rockwool) seams not a good idea as the batt is 1/2" smaller than studs and won't fill all the gap... so it could lead to the triple effect leave as in the 2 possible layouts, there will be hat channel.
> 
> a)
> MDF board 1/4" on studs (1.1 lbs/sqft)
> Mass loaded vinyl 1/8" on MDF (1 lbs/sqft)
> Clip + hat channel (1-5/8")
> Cement board 1/2" (2.24 lbs/sqft)
> Green Glue
> Quietrock EZ 5/8" (2.6 lbs/sqft)
> 
> Total thickness : 3-1/8"
> Approx total weight per sqft : 6.94 lbs
> 
> Or...
> 
> b)
> MLV 1/4" on studs (2 lbs/sqft)
> Clip + hat channel (1-5/8")
> Quietrock 5/8 (2.6 lbs/sqft)
> Green glue
> Quietrock 5/8 (2.6 lbs/sqft)
> 
> Total thickness : 3-1/8"
> Total accurate weight per sqft : 7.2 lbs
> 
> The first layout seams to be a little less dense than the second one, but there are more various materials which further break frequencies... that should be an argument in favor of that layout.
> 
> Any advice or adding different materials are mostly welcome.
> 
> thanks!


If it were me, I would start by opening up the wall as you have done. Then I would seal all air leaks from the neighbors side of the wall. One trick you can try is to turn all your lights off when your neighbor is home and has their lights on. Seal any areas where the light leaks through. Wrap all outlets and switches in putty pads, for both sides of the wall. 

Common areas where leaks occur is between the sill plate and the floor and where the drywall abuts the sill pate. Likewise at the top plate. Next I would add a layer of 5/8” type-X Drywall with Green Glue to the backside of your neighbors drywall. You can use small strips of wood nailed to the side of the studs to hold the edges of the drywall in place while the Green Glue dries.

Roxul Safe-N-Sound is available in appropriate widths for both wood stud and steel stud walls with either 16” On Center (“OC”) or 24” OC spacing, so you should be able to find batts that will fit your wall. There seems to be a marginal benefit of rock wool over fiberglass insulation, so that is what I would use.

I would not add Tavel, but the heavier M


----------



## mhutchins

Ooops, fat fingers......

I would not add Tyvek, but the heavier MLV may offer some minor improvement. I would attach the MLV like you would a vapor barrier on the outer face of the studs facing your room. Then clips and channel as you are planning. Then 2 layers of 5/8” Type-X drywall with Green Glue. I’ve heard Quietrock is quite expensive and offers little benefit over Type-X. Having said that, there is Abuse Resistant (“AR”) drywall available that has the same density as QuietRock and may be less expensive than the QuietRock. I would use the AR drywall if I could find it for a reasonable price in my area.

That’s what I would do. More labor intensive than your two choices above, but probably less expensive and just as effective.

Mike


----------



## zafta

mhutchins said:


> Ooops, fat fingers......


Thanks for you input Mike. Yes, I will consider MLV as a vapor barrier and seal it as it will be. I already starting to put caulking on stud...


----------



## mhutchins

zafta said:


> Thanks for you input Mike. Yes, I will consider MLV as a vapor barrier and seal it as it will be. I already starting to put caulking on stud...


Be careful about vapor barriers on external walls. Their use varies with climate zones and improper use can result in mold and mildew problems and potential structural damage to the walls. For interior walls, it shouldn't be a problem.

Mike


----------



## squared80

So I have excess Foamboard and Batt insulation, so I'm going to use them. Question.

I am basically building a room within a room to help with decoupling. For the outermost wall that I am going to build a wall in front of, how would you suggest putting this excess insulation on. These are interior walls, not exterior or against the foundation.

Option 1 is to cut and fill each cavity with foamboard, then put batt on top of the foamboard.









Option 2 is to fill each cavity with batt, then put the entire foamboard over the entire wall.









Option 2 is much easier and preferred but I wasn't sure if there was a reason I should do it the other way. I would also ask the same question about the ceiling (it's a basement remodel). Would you put the batt into the cavity above you first, then cover with foamboard?


----------



## jcr159

squared80 said:


> So I have excess Foamboard and Batt insulation, so I'm going to use them. Question.
> 
> I am basically building a room within a room to help with decoupling. For the outermost wall that I am going to build a wall in front of, how would you suggest putting this excess insulation on. These are interior walls, not exterior or against the foundation.
> 
> Option 1 is to cut and fill each cavity with foamboard, then put batt on top of the foamboard.
> View attachment 3090247
> 
> 
> Option 2 is to fill each cavity with batt, then put the entire foamboard over the entire wall.
> View attachment 3090248
> 
> 
> Option 2 is much easier and preferred but I wasn't sure if there was a reason I should do it the other way. I would also ask the same question about the ceiling (it's a basement remodel). Would you put the batt into the cavity above you first, then cover with foamboard?



if the foamboard is xps (like owens corning foamular 150/250), then... DON'T. you said interior wall, so I assume you don't need the R value for heating/cooling. This stuff isn't for soundproofing, but is wonderful for insulating concrete slabs and block wall... infact, I used the stuff against my block walls to create vapor barrier and eliminate thermal bridging/mold in the basement (then filled the 2x4 cavities build IN FRONT of it with fluffy pink stuff...

If it's OC 703, then whatever, though i'd just fill the cavities and be done with it... Though i don't think 703/5 is rated for compression load and your second image would squish it under the drywall...


----------



## squared80

It's 2" 250 Owens Corning. Like I said, it's all extra I don't want to throw away or bring back. Is there a reason I shouldn't do it? Won't it still help a little with soundproofing? And again, I am building a wall in front of this wall, so there's no compression anywhere.


----------



## jcr159

squared80 said:


> It's 2" 250 Owens Corning. Like I said, it's all extra I don't want to throw away or bring back. Is there a reason I shouldn't do it? Won't it still help a little with soundproofing? And again, I am building a wall in front of this wall, so there's no compression anywhere.


yeah, it won't help at all with soundproofing... it isn't permeable, so it won't absorb ANY sound. it will create a reflective layer and create a nice triple leaf effect though... best to save it for another project. it doesn't provide any soundproofing benefit. bummer i know!

you want stuff that the sound can permeate and get absorbed inside the space between the walls...


----------



## Snoochers

I watched this video showing how to install perimeter door seals. I noticed they installed the seals on top of the door stops. I was under the impression that sometimes people used these adjustable door seals AS the door stops, instead of installing them on top of the door stops. Is this true, or am I mistaken?

My contractor will be installing door stops so I could just tell him to hold off and use these as door stops if possible. Probably doesn't matter either way but would save him a bit of trouble.


----------



## VAMatt

squared80 said:


> It's 2" 250 Owens Corning. Like I said, it's all extra I don't want to throw away or bring back. Is there a reason I shouldn't do it? Won't it still help a little with soundproofing? And again, I am building a wall in front of this wall, so there's no compression anywhere.


XPS will not do anything for sound in this application. Return it, give it away, whatever. Just don't use it as soundproofing insulation. 

As another commenter mentioned, it may be worse than zero (depending on a bunch of other factors), and there is no possibility of a favorable outcome.


----------



## vin-avforums

I had a thread about my layout here and received some really good advice. I was told to create a new thread for soundproofing questions. I thought I will start here instead.
Copying from that thread:
I see following items when I am thinking about soundproofing:

Roxul safe and sound insulation
Sound isolating clips with resilient channel
Quietrock
Double regular drywall with green glue
Anything else?
I prefer not doing double wall or the room in room thing as it will further reduce the width of the HT.
The room next to the HT is supposed to be a guest bedroom.
I am particularly concerned about sound coming from basement to upper levels.
I think I can definitely do the Roxul safe and sound insulation throughout the basement ceiling and the wall between HT and bedroom (doesn't add a lot to the cost as I was planning to do some insulation anyway).
What is the next item I should be investing in? Sounds clips + resilient channel seems better than double drywall or Quietrock. Thoughts?
The total ceiling square footage across all rooms is about 700 sqft and about 150 sqft of that interior wall between bedroom and HT and about 250sqft of exterior concrete wall around the HT.






View attachment 3090345


----------



## VAMatt

vin-avforums said:


> I had a thread about my layout here and received some really good advice. I was told to create a new thread for soundproofing questions. I thought I will start here instead.
> Copying from that thread:
> I see following items when I am thinking about soundproofing:
> 
> Roxul safe and sound insulation
> Sound isolating clips with resilient channel
> Quietrock
> Double regular drywall with green glue
> Anything else?
> I prefer not doing double wall or the room in room thing as it will further reduce the width of the HT.
> The room next to the HT is supposed to be a guest bedroom.
> I am particularly concerned about sound coming from basement to upper levels.
> I think I can definitely do the Roxul safe and sound insulation throughout the basement ceiling and the wall between HT and bedroom (doesn't add a lot to the cost as I was planning to do some insulation anyway).
> What is the next item I should be investing in? Sounds clips + resilient channel seems better than double drywall or Quietrock. Thoughts?
> The total ceiling square footage across all rooms is about 700 sqft and about 150 sqft of that interior wall between bedroom and HT and about 250sqft of exterior concrete wall around the HT.
> 
> 
> 
> 
> 
> 
> View attachment 3090345


If you want people to be able to use the bedroom while others are using the theater at high volumes, you're going to need to do everything, and do it all perfectly, and provide your guests some ear plugs. If you just care about reducing the amount of sound getting out of the theater by 50% or so, you can probably skip the decoupling. But, once you skip that decoupling, it's done. You can't go and change your mind later unless you're going to redo the room. So, if you're unsure, and you can't do all of the steps, do the decoupling and skip the double drywall. You can come back and do that later if you realize you need it.


----------



## vin-avforums

VAMatt said:


> If you want people to be able to use the bedroom while others are using the theater at high volumes, you're going to need to do everything, and do it all perfectly, and provide your guests some ear plugs. If you just care about reducing the amount of sound getting out of the theater by 50% or so, you can probably skip the decoupling. But, once you skip that decoupling, it's done. You can't go and change your mind later unless you're going to redo the room. So, if you're unsure, and you can't do all of the steps, do the decoupling and skip the double drywall. You can come back and do that later if you realize you need it.


Thanks for the reply. Any thoughts on the ceiling? I have more concern about noise/vibration traveling up.

I agree no one is sleeping in the bedroom when HT is in use. I don't I need that level of isolation for the bedroom. I was thinking just staggered studs (that wall already needs to be 6" because of a beam) with double drywall/green glue for that wall.


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## SaskCanesFan

Just been doing some reading in different places to try and get a plan together for when the time comes to tear apart and soundproof my basement theatre room, and I had a few questions:

1) There are some heavier soundproof/damped drywalls on the market, are these worth the extra $ over just doing 2 layers of regular 5/8 drywall with Green Glue in between? I'm thinking 2 regular GG layers would be better than one layer of the "soundproof" stuff, but has anyone decided to spend the extra money and do 2 layers of the more expensive soundproof drywall in tandem with Green Glue? Can't tell if that'd be worth the investment or a waste

2) I see a lot of people mention using Rockwool Safe n Sound insulation, and that was my original plan as well. But I've read from Soundproofing solutions for the real world | Soundproofing Company that regular pink insulation is just as good in conjunction with decoupling and damping as the Rockwool would be. So if that's truly the case I'd probably save some $ on the insulation and allocate it somewhere else. Is there a consensus on here about different insulations? 

3) I won't have the room to do two separate walls, so my options for decoupling are either staggered studs or soundproofing clips and hat channel. Is one option markedly better than the other, or are they regarded as roughly the same effectiveness? I'd prefer to go with the clips and hat channel if the performance will be roughly equal as it seems easier than staggering studs. Either one would be used together with insulation from question 2, and two layers of drywall with Green Glue in between

4) I've also read that doing 3 layers on the ceiling instead of two is recommended, and I've seen that some people like to use a layer of plywood as it makes it easier to screw the drywall anywhere. I like that idea, so is a plywood layer, then two layers of drywall, all with Green Glue between, equally as effective as doing 3 layers of drywall?

Thanks


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## pkinneb

Regarding #2 I think you will find that the general consensus is that pink fluffy is adequate. I used some rockwool in my build but only where i could utilize its stiffness and also as a fire block where the wall met the ceiling as a code requirement. Save some bucks you will find somewhere else to spend it


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## mhutchins

#1 Most of the special drywalls on the market are just two thin layers of drywall with a Green Glue type mastic in between. In general, they work well for their mass, but most do not weigh as much as 2 layers of 5/8" Type-X and therefore will have sub par low frequency performance; and they are expensive. There is one product that has multiple layers, is 1-3/8" thick and weighs more than 2 layers of Type-X, but it is insanely expensive to purchase and to ship. If you really must have the ultimate of the ultimate, this may be the ticket, but I suspect 3 layers of Type-X with Green Glue will do just as well, if not better.

#2 There may be a marginal performance gain of Rockwool, but you probably need to be an acoustics engineer to prove/hear the benefit.

#3 Clips and channel provide superior decoupling over staggered studs, provided the drywall crew does not "short circuit" the decoupling, such as by using screws that are too long. and hitting the studs. Staggered stud is more fool proof and really is easier to install and less expensive than clips and channel.

#4 Extra layers beyond the first two layers are all about improving the low frequency performance of the system by adding mass. Compared to 5/8" Type-X drywall which weighs 74# for a 4'x8' sheet, 5/8" OSB weighs 58# (22% less) and 5/8" plywood weighs 48# (35% less). Only 5/8" MDF weighs more than Type-X, but by a paltry 7%. And MDF has poor mechanical properties compared to OSB and plywood.

Although you do give up a small amount of mass by using plywood as a first layer, it does simplify subsequent construction. On the other hand, BIGmouthinDC, states that 2 layers of drywall is more than strong enough to support just about anything you would typically hang from a wall or ceiling in a home theater. Probably the more important structural consideration is to have adequate channel spacing and an appropriate number of clips for the increased loads anticipated. Most clips are rated for an optimum load of 30-35#, but have ultimate strengths of 3-5x the design load. Exceeding the design load, however, will compromise the acoustical properties.

So, does 1 layer of plywood followed by two layers of drywall provide equal isolation to 3 layers of drywall? Probably not, but you may not be able to measure the difference in your theater due to other isolation losses such as doors, air leaks, flanking paths, etc.

Mike


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## VAMatt

Note that I am a soundproofing noob. But, I am a professional remodeling contractor.

1) From reading here and elsewhere, I can confidently say that the consensus is that for any remotely normal home theater use case, the expensive pre-damped drywalls like Quiet Rock provide little to no benefit, and definitely do not provide a benefit equal to their additional cost. 

2) As others have mentioned, the consensus is that the benefits of rockwool over standard fiberglass are minimal if any. With that said, when I purchased it a few months ago the price difference was tiny. Less than 10%. So, I went ahead and used it anyway. It sucks to work with though, because it creates an incredibly annoying dust.

3) Not much chance you're going to screw up a staggered stud construction. Much greater chance of screwing up clips and channel. So.....

4) Working with OSB sucks. But, if you were going to do something like triple layer drywall (or two layers over your OSB) the benefit for ease of installation of the subsequent layers may make it worthwhile. I used some because I was installing a coffered ceiling and doing OSB on the ceiling made that easier. It's hard for me to imagine any realistic scenario where it makes sense to use OSB on walls.


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## SaskCanesFan

Thanks for the replies guys, that clears a few things up for me!

In regards to #1 then, I'll definitely save the money and go with 2 layers of 5/8" regular drywall with Green Glue instead of any of the fancy stuff, just wanted to make sure I wasn't missing out on anything substantial. Same with #2, I'll just look for the regular pink insulation in the case of a noticeable price difference, though if it is 10% or less like for VAMatt I may opt to do the same. Will keep an eye on prices and see what the savings are, at least its nice to know I don't "need" to splurge if the $ difference is significant.

Regarding #3, I'm quite surprised that you guys said staggered studs is actually the easier install than clips and channel, I would have assumed the opposite from my uneducated point of view. Though are you guys saying that with the assumption of building new walls, or even on existing ones? The house I bought already has the room framed and finished, so I'll just be tearing the existing drywall off to add insulation and finishing from there, not framing any new walls. I figured since the walls were already up that it would be easier and quicker to just screw the clips onto the existing studs than to cut and weave new studs in between the existing ones and then ripping 2x1 around the perimeter. But since I've never done either I'm open to being corrected haha.

For #4, to be clear the third layer would be going on the ceiling only, as I read that soundproofingcompany.com recommended a third layer on the ceiling. OSB/plywood seemed like a nicer first layer just because of the ease of putting screws anywhere in the drywall for layers 2 and 3. If I were doing two layers I'd stick to both being 5/8 drywall so that I don't lose any mass, but if I do end up going with 3 layers I feel like the 22% mass loss with OSB on layer 1 is still worth the trade off for ease of installation, and obviously still more total mass than just 2 drywall layers.


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## VAMatt

For #3..... If the room already exists, clips and channel will be easier. Still, it is relatively easy to "short circuit" that system by putting a drywall screw through the channel and into a stud, while it is very unlikely that you would accidentally short circuit staggered studs. With that said, choosing a proper screw length for your drywall can help reduce the risk substantially. 

Knowing that the room is already built, if I were in your position, I would do clips and channel.


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## warwwolf7

VAMatt said:


> 3) Not much chance you're going to screw up a staggered stud construction. Much greater chance of screwing up clips and channel. So.....
> 
> L.


I strongly disagree with #3. It's not that easy to mess it up. 
Clip and channel, using Ib-1 clips for example, you have 1" of space between the drywall and the clip. If you are messing this up, maybe you shouldn't do anything that requires a 1/2" precision.

With 5/8 drywall, the first layer should have a screw that is 1" to 1 1/2" long and you won't have any problem. The channel is quite thin and doesn't require more than 1/4" inch of screw hanging on the other side of the channel. 
For the second layer, it depends if you are using green glue or not. Use a 1 3/4" or 2" screw long.

@BIGmouthinDC wrote the proper screw length multiple times in this forum. I suggest you look it up.

Hat and channel has been done hundreds of times in this forum, and I'm sure the majority is not all of whom used that method would recommend it over staggered stud.

Cheers 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## VAMatt

warwwolf7 said:


> I strongly disagree with #3. It's not that easy to mess it up.
> Clip and channel, using Ib-1 clips for example, you have 1" of space between the drywall and the clip. If you are messing this up, maybe you shouldn't do anything that requires a 1/2" precision.
> ..........
> Hat and channel has been done hundreds of times in this forum, and I'm sure the majority is not all of whom used that method would recommend it over staggered stud.
> 
> Cheers
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


So, you think it is more likely that one would short circuit staggered studs than clips/channel? If so, I'd be interested to know how you come to that conclusion.

I agree with you that clips/channel are not particularly difficult to get right. But, there is no question that the chance of short circuiting clips/channel is much higher than staggered studs, assuming they're spaces properly (which i suppose is something that one could screw up). 

You'd have to be several inches off the mark to hit the wrong stud, versus simply using too long of a screw with clips/channel. Plus, your screw would almost certainly pull through the drywall when hitting the wrong stud, thus indicating that you screwed up. In normal construction (building most anything other than a soundproofed room) it is very common to use much longer screws than a clips/channel job calls for. In some situations, screws are required to be long enough to penetrate by much more than the thickness of hat channel. So, screws that you can't use very likely are hanging around any jobsite, and it is not uncommon to grab the nearest drywall screws and get hanging your drywall. It _is_ very uncommon to put screws several inches away from the place they need to be, then fail to realize that your screw is traveling through a bunch of air before hitting the stud, then not have it rip through the drywall.


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## BIGmouthinDC

Staggered studs are not isolated at the top and bottom. Clip and channel isolates the entire wall of drywall. Correct length screws for 5 /8 drywall on clips and channel is 1 1/4 and 2 inches.


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## brcannon

Hi there! I've been researching and reading up on this forum for several month as I plan to insulate the ceiling in my 13'x14' Airbnb that is below my bedroom. I wanted to share my plan to see if anyone had any feedback. We rent full time in a beach town and deal with noisy drunk guests constantly at all hours especially through the summer so we're not worried about cost, just looking to get the most reduction possible. Our subfloor is the cheap panels kind.

A couple questions I had as well,

We're adding a ceiling fan, will that just require putty on the box and sealant?
If we install quiet boxes around the six recessed lighting
will there still be a significant loss in sound reduction? should we consider just removing them all together and relying on the ceiling light?
do the existing lights need to be IC rated to put in a box?

We're removing the carpet and installing porcelain tile in the bedroom above and I understand this will also reduce sound reduction, we're currently considering adding MLV on the subfloor then cement board, any recommendations on what else we can do without adding too much height? The tile has to be flush with the tile in the adjacent bathroom and living room. I've already planned to add DDGG to subfloor from the ceiling below.

Current plan

After removing the existing drywall, have structural engineer determine weight limit for ceiling and floor above
acoustic putty pads on outlets and junction boxes, Green Glue acoustic sealant in cracks/holes, around outlet boxes
Two ⅝ inch drywall layers with Green Glue acoustic adhesive between, sealed with Green Glue acoustic sealant installed on subfloor between joists
Six quiet boxes around recessed lighting decoupled from studs with clip (new recessed lighting may need to be installed if existing are not IC rated)
Building guide: https://www.soundproofingcompany.com/wp-content/uploads/2011/06/CIM-backer-box-installation-web.pdf
With DC-04 clips RSIC-DC04 Sound Isolation Clip www.TMsoundproofing.com 

Or Pre-built: How To Install the QuietBox With GenieClip® LB 

Rockwool Safe n Sound insulation between joists , above/around recessed lighting https://images.homedepot-static.com/catalog/pdfImages/ed/ed82a9d2-0ccd-478d-90ab-656345df0718.pdf 
Mass Loaded Vinyl on studs https://www.tmsoundproofing.com/How-to-Install-Mass-Loaded-Vinyl.html 
Whisper clips and hat channels on studs
ttps://www.tmsoundproofing.com/whisper-clips-green-glue.html?sku=WCR-10
High Quality Metal Furring Hat Channel for Resilient Sound Clips | TMsoundproofing.com

Two ⅝ inch drywall layers with Green Glue acoustic adhesive between, sealed with Green Glue acoustic sealant 
Green Glue acoustic sealant in cracks/holes, around outlet boxes
Replace interior door next with solid core, seals, rubber sweep


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## warwwolf7

VAMatt said:


> So, you think it is more likely that one would short circuit staggered studs than clips/channel? If so, I'd be interested to know how you come to that conclusion.
> 
> I agree with you that clips/channel are not particularly difficult to get right. But, there is no question that the chance of short circuiting clips/channel is much higher than staggered studs, assuming they're spaces properly (which i suppose is something that one could screw up).
> 
> You'd have to be several inches off the mark to hit the wrong stud, versus simply using too long of a screw with clips/channel. Plus, your screw would almost certainly pull through the drywall when hitting the wrong stud, thus indicating that you screwed up. In normal construction (building most anything other than a soundproofed room) it is very common to use much longer screws than a clips/channel job calls for. In some situations, screws are required to be long enough to penetrate by much more than the thickness of hat channel. So, screws that you can't use very likely are hanging around any jobsite, and it is not uncommon to grab the nearest drywall screws and get hanging your drywall. It _is_ very uncommon to put screws several inches away from the place they need to be, then fail to realize that your screw is traveling through a bunch of air before hitting the stud, then not have it rip through the drywall.


If someone is ending in this thread for soundproofing, they should be aware, just by reading the 1rst post that soundproofing requires attention on every details.

I understand your point that staggered stud soundproofing are harder to mess up than hat and channel.
The point I was trying to make was that it doesn't take that much attention to detail to make a proper hat and channel installation. It requires minimal preparation.

If the workers cant follow a plan with screw lengths, then I wouldn't trust them on important task like installing vapor barrier or even screwing the drywall into the studs behind. I had a team to redo my supporting wall in my basement. They messed up the 16" center to center spacing... Some were 15,some were 18" appart. I had to move them in order to be able to install my drywall. So I do understand what you mean. In my case I took the cheapest quote, I wasn't expecting much.

Hat and channel, if you follow the instructions, everything will be fine. Pretty much like everything in life. If you don't follow, lower your expectations

Thanks for chiming in about the screw length in my previous post @BIGmouthinDC 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## BIGmouthinDC

typo earlier the first layer screws on channel should be 1 1/4 not 1 1/2


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## SaskCanesFan

Thanks again. I understand what you mean about short circuiting the clips if you are being careless or not using the right screw length, but that's something I'd be very aware of. Wouldn't be starting the job without making sure I had the right information and tools available, so its not an issue I anticipate having. Being that the walls are already up that's the way I'll look to go.

Are most people just using the IB-1 clips? I see there are IB-2 and Whisper Clips available as well that look a little more substantial and have rubber isolators built in.


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## warwwolf7

SaskCanesFan said:


> Thanks again. I understand what you mean about short circuiting the clips if you are being careless or not using the right screw length, but that's something I'd be very aware of. Wouldn't be starting the job without making sure I had the right information and tools available, so its not an issue I anticipate having. Being that the walls are already up that's the way I'll look to go.
> 
> Are most people just using the IB-1 clips? I see there are IB-2 and Whisper Clips available as well that look a little more substantial and have rubber isolators built in.


You gain a little bit in the stc by using the higher end model of the ib1, like the one you stated.
Im not too familiar about the gain of the other clips because I choosed ib1, I don't want to regret the choice that I made because I can't change it. 

There is a cheaper ib-2 copy available on the market, I saw the link somewhere on avs. I can't comment on it.

There are a bunch of little thing that, summed together makes a significant difference. Choosing a better bracket, green glue, minimizing the holes in the walls, decoupling the walls, etc... The more you do, the better the chances are that you will get better results. I took ib-1 because of the money I had available at that moment, otherwise I would not have been able to buy the 5buckets of green glue.
I'm still in progress, so I can't talk about the results.

I hope the best for you and your project 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## poopiehead

I am having a debate with my contractor

The install is in a townhome. Two opposing walls that adjoin to a neighbour.

Currently it’s two walls with staggered studs (C) and the plan was one sonopan and a drywall with inwall speakers using the OEM Kef metal speaker boxes.

FYI Sound Barrier Technology | Noise Stop Technology | Soundproofing

Custom Installation Rear Enclosure

Understanding the Triple Leaf Effect and air cavity depth | Soundproofing Company

The contractor believes I will NOT meet code if I don’t have a dry wall behind the speaker box and says I need a third wall. I believe having the metal box actually makes my in wall speakers to code. When looking into it there is the three leaf rule apparently with a third wall

If I was to build the extra wall, scenario A doesn’t use sonopan, B uses sonopan on the inner wall and scenario D uses it on the inner wall. Which solution is correct?


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## VAMatt

poopiehead said:


> I am having a debate with my contractor
> 
> The install is in a townhome. Two opposing walls that adjoin to a neighbour.
> 
> Currently it’s two walls with staggered studs (C) and the plan was one sonopan and a drywall with inwall speakers using the OEM Kef metal speaker boxes.
> 
> FYI Sound Barrier Technology | Noise Stop Technology | Soundproofing
> 
> Custom Installation Rear Enclosure
> 
> Understanding the Triple Leaf Effect and air cavity depth | Soundproofing Company
> 
> The contractor believes I will NOT meet code if I don’t have a dry wall behind the speaker box and says I need a third wall. I believe having the metal box actually makes my in wall speakers to code. When looking into it there is the three leaf rule apparently with a third wall
> 
> If I was to build the extra wall, scenario A doesn’t use sonopan, B uses sonopan on the inner wall and scenario D uses it on the inner wall. Which solution is correct?
> 
> View attachment 3095206


This is a question for your local code enforcement agency. There are fire barrier concerns in partition walls that may make your contractor's thinking correct. But, you may be able to get around that by building your own backer box that is lined with 5/8 drywall. The feasibility of this, and whether it will do the job, depends on the type of partition wall used in your house and how it will be viewed by the inspector. 

Also, generally speaking, your contractor, if they're qualified to do the job, will know the code for this stuff, as well as any local quirks. So, I would suggest that you rely on the contractor rather than people in a forum that have no idea of your situation. The collective internet is an idiot. Most of the US utilizes the International Residential Code for the basics. But, there are state and local supplements to that code, jurisdictions use different IRC years, and localities focus on and interpret things differently. Also, some multi-family housing types rely on commercial code. Further, I see that you're in Canada, where there are some code differences. Put it all together, and there just isn't a way to get good code advice on something like this in a forum like this one.


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## poopiehead

VAMatt said:


> This is a question for your local code enforcement agency. There are fire barrier concerns in partition walls that may make your contractor's thinking correct. But, you may be able to get around that by building your own backer box that is lined with 5/8 drywall. The feasibility of this, and whether it will do the job, depends on the type of partition wall used in your house and how it will be viewed by the inspector.
> 
> Also, generally speaking, your contractor, if they're qualified to do the job, will know the code for this stuff, as well as any local quirks. So, I would suggest that you rely on the contractor rather than people in a forum that have no idea of your situation. The collective internet is an idiot. Most of the US utilizes the International Residential Code for the basics. But, there are state and local supplements to that code, jurisdictions use different IRC years, and localities focus on and interpret things differently. Also, some multi-family housing types rely on commercial code. Further, I see that you're in Canada, where there are some code differences. Put it all together, and there just isn't a way to get good code advice on something like this in a forum like this one.


I've spent a couple hours looking into it and the third wall will most likely be needed since the OEM Kef boxes (called Kef support) are not fire rated. Kef suggested I purchase fire rated back boxes adhering to the minimum volume and sell the Key boxes

I've decided to build a nook for the TV with the new wall and use the Kef boxes. Now I have to decide on Scenario A, B or D. Also do I have to worry about the triple leaf rule or I have more than enough air gap to not be an issue?


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## jrref

poopiehead said:


> I am having a debate with my contractor
> 
> The install is in a townhome. Two opposing walls that adjoin to a neighbour.
> 
> Currently it’s two walls with staggered studs (C) and the plan was one sonopan and a drywall with inwall speakers using the OEM Kef metal speaker boxes.
> 
> FYI Sound Barrier Technology | Noise Stop Technology | Soundproofing
> 
> Custom Installation Rear Enclosure
> 
> Understanding the Triple Leaf Effect and air cavity depth | Soundproofing Company
> 
> The contractor believes I will NOT meet code if I don’t have a dry wall behind the speaker box and says I need a third wall. I believe having the metal box actually makes my in wall speakers to code. When looking into it there is the three leaf rule apparently with a third wall
> 
> If I was to build the extra wall, scenario A doesn’t use sonopan, B uses sonopan on the inner wall and scenario D uses it on the inner wall. Which solution is correct?
> 
> View attachment 3095206


First i would check to see if there are any restrictions to modifying the common wall. In my townhouse complex it's not allowed for some of the reasons your contractor is pointing out. The purpose of a fire wall is to keep the fire at a certain temperature for a specified amount of time from spreading to the next unit. I doubt the metal box will contain the heat like 5/8 inch fire rock will. And if you modify the wall in such a way that causes a potential fire to spread to the next unit you will be liable for any property damages and or loss of life.


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## poopiehead

jrref said:


> First i would check to see if there are any restrictions to modifying the common wall. In my townhouse complex it's not allowed for some of the reasons your contractor is pointing out. The purpose of a fire wall is to keep the fire at a certain temperature for a specified amount of time from spreading to the next unit. I doubt the metal box will contain the heat like 5/8 inch fire rock will. And if you modify the wall in such a way that causes a potential fire to spread to the next unit you will be liable for any property damages and or loss of life.


The best solution is B









The adjoining walls will not be disturbed nor changed structurally to accommodate the speaker boxes (wider than the stud spacing) and there will be two dry walls on on my side. Sucks that I have to eat 10-12" of the room width but I plan to build a nook with the new space eaten up.


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## warwwolf7

poopiehead said:


> I am having a debate with my contractor
> 
> The install is in a townhome. Two opposing walls that adjoin to a neighbour.
> 
> Currently it’s two walls with staggered studs (C) and the plan was one sonopan and a drywall with inwall speakers using the OEM Kef metal speaker boxes.
> 
> FYI Sound Barrier Technology | Noise Stop Technology | Soundproofing
> 
> Custom Installation Rear Enclosure
> 
> Understanding the Triple Leaf Effect and air cavity depth | Soundproofing Company
> 
> The contractor believes I will NOT meet code if I don’t have a dry wall behind the speaker box and says I need a third wall. I believe having the metal box actually makes my in wall speakers to code. When looking into it there is the three leaf rule apparently with a third wall
> 
> If I was to build the extra wall, scenario A doesn’t use sonopan, B uses sonopan on the inner wall and scenario D uses it on the inner wall. Which solution is correct?
> 
> View attachment 3095206


Can't you adapt the installation and install the speakers in the room on the wall? Is it a design choice that can't be changed? 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## jrref

I live in a townhouse with a common party wall which has 5/8 inch Quiet Rock installed. If i mount a flat screen TV on the wall the mount will need to be screwed into the studs. Will this compromise the sound proofing of the Quiet Rock installed? If so, are there any options in mounting the TV?


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## jcr159

jrref said:


> I live in a townhouse with a common party wall which has 5/8 inch Quiet Rock installed. If i mount a flat screen TV on the wall the mount will need to be screwed into the studs. Will this compromise the sound proofing of the Quiet Rock installed? If so, are there any options in mounting the TV?


To directly answer your first question, it probably will impact things some, the question is if it will be enough that it matters. It probably won’t.

To avoid the situation altogether, you could purchase a three in one stand like this:





Whalen Furniture 3-in-1 Console for Most Flat-Panel TVs Up to 65" Brown Cherry BBXL54NV - Best Buy


Shop Whalen Furniture 3-in-1 Console for Most Flat-Panel TVs Up to 65" Brown Cherry at Best Buy. Find low everyday prices and buy online for delivery or in-store pick-up. Price Match Guarantee.




www.bestbuy.com


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## poopiehead

This is the front wall. Three in wall speakers for HT (2 surround also on the opposing wall) and my two channel will be a separate system (If I chose to move it to this new space). 

The issue has always been the in wall speakers and how to install, minimize noise to my neighbors and still meet code.


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## jcr159

poopiehead said:


> This is the front wall. Three in wall speakers for HT (2 surround also on the opposing wall) and my two channel will be a separate system (If I chose to move it to this new space).
> 
> The issue has always been the in wall speakers and how to install, minimize noise to my neighbors and still meet code.
> 
> View attachment 3095584


Have you looked into any of the RBH, KEF, Klipsch, Revel (M8?) on wall options? There are some slim options that look pretty good, and would make things a whole lot simpler... not exactly the same look, but seems like a big win in simplicity!


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## jrref

poopiehead said:


> This is the front wall. Three in wall speakers for HT (2 surround also on the opposing wall) and my two channel will be a separate system (If I chose to move it to this new space).
> 
> The issue has always been the in wall speakers and how to install, minimize noise to my neighbors and still meet code.
> 
> View attachment 3095584


When i see an installation like this, i wonder how you can open the wall and mount speakers and still have the same sound isolation to your neighbors as if the speakers were mounted in front of the wall? As i mentioned, i live in a Townhouse with a common wall. Several years ago with my neighbors permission i took my side of the common wall down and put new roxul safe and sound in his wall, sealed all the outlets, did the same on my side then installed 5/8 inch quiet rock on my side. The result was i got about a 50 db reduction in sound transmission which gives us good isolation but when my neighbor turns up his bass, you can start to hear it because its vibrating the structure. I was thinking of putting a layer of 5/8 inch Quiet Rock over his common wall to minimize the work on his side. Any idea how much this might help?


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## poopiehead

jcr159 said:


> Have you looked into any of the RBH, KEF, Klipsch, Revel (M8?) on wall options? There are some slim options that look pretty good, and would make things a whole lot simpler... not exactly the same look, but seems like a big win in simplicity!


Unfortunately, I committed all the in wall speakers already along with buying the OEM Kef metal back boxes. 

With three walls, two air gaps, back boxes and 4 sheets of drywall between I assume my ATC is >70


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## DHelmet

I have been wanting to build a home theater for years and I have been reading this forum for months. After recently spending hours reading through pkinneb's Full Circle Theater build (Full Circle Cinema Build) I am inspired to start my project. My goal is to have the theater sound-proofed as much as possible and the information I have found on here is invaluable. Nonetheless I think the more I read the less confident I am that I will get it right. 

So before I start building walls, I am looking for some help: To give you an idea of the space, the walls in the room are 10" poured concrete and there are no rooms on the same level that I need to isolate for sound. There is a room above the theater that I want to isolate as much as possible. (So of course the ceiling is a different story and I am sure I will have questions about that later.) 

For the walls my initial thought is to build standard 2x4 walls filled with R13/15 insulation with a single layer of drywall with no clips or staggered walls. I plan to use 1/2" 'pink' foam board behind the studs as the vapor barrier against the poured foundation and to also gain a little R-value. Since I am not worried about horizontal noise penetration is this an acceptable solution?


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## warwwolf7

DHelmet said:


> I have been wanting to build a home theater for years and I have been reading this forum for months. After recently spending hours reading through pkinneb's Full Circle Theater build (Full Circle Cinema Build) I am inspired to start my project. My goal is to have the theater sound-proofed as much as possible and the information I have found on here is invaluable. Nonetheless I think the more I read the less confident I am that I will get it right.
> 
> So before I start building walls, I am looking for some help: To give you an idea of the space, the walls in the room are 10" poured concrete and there are no rooms on the same level that I need to isolate for sound. There is a room above the theater that I want to isolate as much as possible. (So of course the ceiling is a different story and I am sure I will have questions about that later.)
> 
> For the walls my initial thought is to build standard 2x4 walls filled with R13/15 insulation with a single layer of drywall with no clips or staggered walls. I plan to use 1/2" 'pink' foam board behind the studs as the vapor barrier against the poured foundation and to also gain a little R-value. Since I am not worried about horizontal noise penetration is this an acceptable solution?


Hi,

Flanking path is a s.o.b. If you don't treat your wall with double drywall, the sound will travel from your walls and up.

You want the best soundproofing possible, right?

Use the best version of the ib1=> Ib2 I think or the other alternative that we're suggested across this thread multiple times.


I would suggest double drywall between the floor joist of the room above with green glue. If your joist are not straight like mines were, it was a pain to measure.
Then hat and channel, using your favorite clip.

Now remember that the ceiling drywall will end at the top of your 2x4walls. So anything that goes through your drywall on your walls will possibly go up. Your 2x4 will most likely be connected with nails to the floor joist of your room above. If you don't use clips and channel on your wall, you are not decoupling your wall from the floor of your room above.

If you are to put 1single layer of drywall directly on your wall, then maybe you would be wasting money going all in for the ceiling.

My 2 cents 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## pkinneb

@DHelmet first I am really glad my build was helpful! I used this forum for my inspiration and knowledge building so its great to know that I was able to be helpful to someone else. A couple of things re soundproofing, this is not scientific necessarily, that is out of my wheel house, but rather personal experience. First soundproofing and acoustical treatments have a lot to do with the sound in the room as well as outside of it. Another point I would make is that while you can build to suit from my experience you really can't skip a step and still solve the problem. For instance I can almost assure you if you only soundproof the ceiling there will be noise escaping the sidewalls and making their way to the upper levels. My room is far from perfect but one thing I do notice is I decided not to put double drywall and green glue between the joists, just seemed like a lot of work and I wasn't sure I needed it since above our room is the master bath. Although rare, every time my wife walks across that floor I think you know I wish I would have done that under the tile floor. Again a big deal? Not at all but its also not something I can really go back and fix. I've said it before on this forum and will say it again here these rooms are expensive and sometimes we have to cut costs just make sure where you are cutting is easily solvable later. Upgrading an amp, sub, chair is way easier then upgrading the soundproofing or acoustics of a room


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## DHelmet

@pkinneb and @warwwolf7 thank you so much for your replies. Quite frankly I keep delay the start of actually building becasue I am really stressed out about getting this right...my wife thinks I'm nuts and I guess I have no grounds to argue against her! 

Wall treatments are definitely part of the plan. I need to figure out who to consult to get an idea on how to successfully accomplish that.

Pkinneb, regarding the DD, GG between the joists....I was SO afraid you were going to say that... . The room above has radiant floor heating and when I built the room I glued foam insulation to the top of the I-joints to keep the heat in. Also, over the past two weekends I already put in insulation and installed the hat clips and channel. If (oh who am I kidding...) WHEN I tear out the foam, remove the insulation and Hat and install drywall between the joinsts my wife is going to have me committed!

Anyway, although I am concerned about the wall construction at the moment I did leave out one key point. I plan to build a room within a room by building the ceiling first, (using A234 clips, 25G Hat Channel, 5/8 OSB, GG, 5/8 DW) and then attaching the walls to to the "floating" ceiling and sealing the gap between the ceiling and wall with acoustic caulk. Since the walls are floating, do you think 5/8 drywall attached directly to the wall studs would be as good as DD, GG and clips for wall construction in this particular case? I also saw someone mention that 1/2" foam behind the studs can cause some "bad" acoustical affects. @pkinneb, I believe you used some of this in your build. Were you advised against it? Or does the foil facing on what you iused change things?


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## warwwolf7

DHelmet said:


> @pkinneb and @warwwolf7 thank you so much for your replies. Quite frankly I keep delay the start of actually building becasue I am really stressed out about getting this right...my wife thinks I'm nuts and I guess I have no grounds to argue against her!
> 
> Wall treatments are definitely part of the plan. I need to figure out who to consult to get an idea on how to successfully accomplish that.
> 
> Pkinneb, regarding the DD, GG between the joists....I was SO afraid you were going to say that... . The room above has radiant floor heating and when I built the room I glued foam insulation to the top of the I-joints to keep the heat in. Also, over the past two weekends I already put in insulation and installed the hat clips and channel. If (oh who am I kidding...) WHEN I tear out the foam, remove the insulation and Hat and install drywall between the joinsts my wife is going to have me committed!
> 
> Anyway, although I am concerned about the wall construction at the moment I did leave out one key point. I plan to build a room within a room by building the ceiling first, (using A234 clips, 25G Hat Channel, 5/8 OSB, GG, 5/8 DW) and then attaching the walls to to the "floating" ceiling and sealing the gap between the ceiling and wall with acoustic caulk. Since the walls are floating, do you think 5/8 drywall attached directly to the wall studs would be as good as DD, GG and clips for wall construction in this particular case? I also saw someone mention that 1/2" foam behind the studs can cause some "bad" acoustical affects. @pkinneb, I believe you used some of this in your build. Were you advised against it? Or does the foil facing on what you iused change things?


If you plan on doing another sets of wall. Then you can skip the hat and channel on those wall. However I think you should use Ib3 clip (or something similar) to attach the top of the wall to the joist. Before any drywall is installed. Then proceed with the ceiling drywall, layer1, then the drywall layer 1 on the wall. Repeat for the second layer.

Adding a second set of wall is more effective than using hat and channel for decoupling. However you still need dampening and mass. A second layer of drywall is your next step. Then if you want to go further, you add the green glue to dampen even more.


I'm my basement, I had urethane sprayed on every one of the exterior walls. This has the negative effect of connecting all the studs very solidly together. But I choosed that insulation for multiple reasons years ago. I'm adding 1" of rockwool on top to reduce the cavity resonance. Sprayed glue and rockwool and its done.

If you are afraid of that rigid insulation you have, I would look if you have space to add a little bit of rockwool on top. But your 2nd set of walls should also be filled with rockwool and should reduce the resonance of cavity quite a bit. Remember that Rockwool is efficient at reducing resonance not really at blocking sound. From the nrc cnrc, they conclude that the most important thing when installing Rockwool in a wall is to cover the entire area. Filling the entire depth of a wall vs half the depth of the wall makes very little difference.

From this, you could conclude that if you have a room within a room. The inner wall and outside walls shared space is one cavity. Filling the inner wall cavity will most likely provide sufficient absorption. If you can add more on the inner side of the outer wall, it will not hurt.

I hope this helps.

If you haven't already, I suggest you look for the nrc cnrc papers on soundproofing. They are very well done and free. 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## warwwolf7

warwwolf7 said:


> If you plan on doing another sets of wall. Then you can skip the hat and channel on those wall. However I think you should use Ib3 clip (or something similar) to attach the top of the wall to the joist. Before any drywall is installed. Then proceed with the ceiling drywall, layer1, then the drywall layer 1 on the wall. Repeat for the second layer.
> 
> Adding a second set of wall is more effective than using hat and channel for decoupling. However you still need dampening and mass. A second layer of drywall is your next step. Then if you want to go further, you add the green glue to dampen even more.
> 
> 
> I'm my basement, I had urethane sprayed on every one of the exterior walls. This has the negative effect of connecting all the studs very solidly together. But I choosed that insulation for multiple reasons years ago. I'm adding 1" of rockwool on top to reduce the cavity resonance. Sprayed glue and rockwool and its done.
> 
> If you are afraid of that rigid insulation you have, I would look if you have space to add a little bit of rockwool on top. But your 2nd set of walls should also be filled with rockwool and should reduce the resonance of cavity quite a bit. Remember that Rockwool is efficient at reducing resonance not really at blocking sound. From the nrc cnrc, they conclude that the most important thing when installing Rockwool in a wall is to cover the entire area. Filling the entire depth of a wall vs half the depth of the wall makes very little difference.
> 
> From this, you could conclude that if you have a room within a room. The inner wall and outside walls shared space is one cavity. Filling the inner wall cavity will most likely provide sufficient absorption. If you can add more on the inner side of the outer wall, it will not hurt.
> 
> I hope this helps.
> 
> If you haven't already, I suggest you look for the nrc cnrc papers on soundproofing. They are very well done and free.
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


IMPORTANT 
About adding insulation on top of already existing insulation.

You don't want to move the dew point 9f the insulation inside the insulation behind the vapour barrier. I'm not really informed about this phenomenon, but it's goes close to this.


Of your outside wall is cement-3inch insulation-vapor barrier and you add 4inches of insulation on top. You are moving the dew point inside the insulation near the vapor barrier.

Im rather sure adding 1" of rockwool won't be a problem at all. But read about that phenomenon before adding more insulation in front of your current insulation. I don't want to be promoting back practice. 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## pkinneb

DHelmet said:


> @pkinneb and @warwwolf7 thank you so much for your replies. Quite frankly I keep delay the start of actually building becasue I am really stressed out about getting this right...my wife thinks I'm nuts and I guess I have no grounds to argue against her!
> 
> Wall treatments are definitely part of the plan. I need to figure out who to consult to get an idea on how to successfully accomplish that.
> 
> Pkinneb, regarding the DD, GG between the joists....I was SO afraid you were going to say that... . The room above has radiant floor heating and when I built the room I glued foam insulation to the top of the I-joints to keep the heat in. Also, over the past two weekends I already put in insulation and installed the hat clips and channel. If (oh who am I kidding...) WHEN I tear out the foam, remove the insulation and Hat and install drywall between the joinsts my wife is going to have me committed!
> 
> Anyway, although I am concerned about the wall construction at the moment I did leave out one key point. I plan to build a room within a room by building the ceiling first, (using A234 clips, 25G Hat Channel, 5/8 OSB, GG, 5/8 DW) and then attaching the walls to to the "floating" ceiling and sealing the gap between the ceiling and wall with acoustic caulk. Since the walls are floating, do you think 5/8 drywall attached directly to the wall studs would be as good as DD, GG and clips for wall construction in this particular case? I also saw someone mention that 1/2" foam behind the studs can cause some "bad" acoustical affects. @pkinneb, I believe you used some of this in your build. Were you advised against it? Or does the foil facing on what you iused change things?


Yeah I would be with your wife probably not worth tearing out what you have there for it  

Yes I did room within a room with IB3 clips no need for channel, that I am aware of, in that design. I have 1" foam glued to the foundation walls but it is an 1" away from the inner stud wall which is also insulated. I don't recall ever seeing anything that stated that would/could be a problem. The big thing is you do not want to trap moisture so only one moisture barrier on the outer wall. If you use faced insulation like I did in some spots for ease of installation just make sure you slit it liberally once installed to allow air movement.


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## mhutchins

One possible solution is to build the ceiling first, sealing it against the concrete walls all around the perimeter with each layer of drywall. Clips and channel have been mentioned, and that would be a good choice. But, rather than using the traditional RSIC-style clip, you might consider the Kinetics Wave Hanger. I believe it has a lower resonant frequency than other clips, and should therefore do a slightly better job at isolating the lower frequencies, which are the hardest to control. Furthermore, with the Wave Hanger, kinetics shows completing the ceiling all at once, rather than the typical interlocking pattern of alternating layers between the ceiling and the walls.

So for your situation, you would finish the ceiling first, before starting the walls. Where the top plate of the new walls meet the ceiling, I would put a thick layer of caulk on the top plate before tipping the wall into place. I would do this by tilting the top of the wall into position first, then slide the bottom into place, thus compressing the caulk against the ceiling. I would try to use a sill plate gasket as well between the sill plate and the concrete floor. Then I would stuff a foam backer rod between the top plate and the ceiling and then do another thick bead of caulk between the ceiling and the top plate. Lastly, I would caulk around the full perimeter of the new wall as each layer of drywall is installed, making sure to seal all gaps between the stud wall and the adjoining concrete walls and ceiling.

This is all just theory though, as I haven't built anything yet. 

Mike


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## DHelmet

warwwolf7 said:


> If you plan on doing another sets of wall. Then you can skip the hat and channel on those wall. However I think you should use Ib3 clip (or something similar) to attach the top of the wall to the joist. Before any drywall is installed. Then proceed with the ceiling drywall, layer1, then the drywall layer 1 on the wall. Repeat for the second layer.
> 
> Adding a second set of wall is more effective than using hat and channel for decoupling. However you still need dampening and mass. A second layer of drywall is your next step. Then if you want to go further, you add the green glue to dampen even more.
> 
> 
> I'm my basement, I had urethane sprayed on every one of the exterior walls. This has the negative effect of connecting all the studs very solidly together. But I choosed that insulation for multiple reasons years ago. I'm adding 1" of rockwool on top to reduce the cavity resonance. Sprayed glue and rockwool and its done.
> 
> If you are afraid of that rigid insulation you have, I would look if you have space to add a little bit of rockwool on top. But your 2nd set of walls should also be filled with rockwool and should reduce the resonance of cavity quite a bit. Remember that Rockwool is efficient at reducing resonance not really at blocking sound. From the nrc cnrc, they conclude that the most important thing when installing Rockwool in a wall is to cover the entire area. Filling the entire depth of a wall vs half the depth of the wall makes very little difference.
> 
> From this, you could conclude that if you have a room within a room. The inner wall and outside walls shared space is one cavity. Filling the inner wall cavity will most likely provide sufficient absorption. If you can add more on the inner side of the outer wall, it will not hurt.
> 
> I hope this helps.
> 
> If you haven't already, I suggest you look for the nrc cnrc papers on soundproofing. They are very well done and free.
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


Thank you Warwwolf. I definitely plan to add insulation on top of the rigid foam board and I will now likely add a second layer of drywall to the walls. I am still thinking about the IB3 clips and if I need to do this if I attach the walls to the ceiling which is floating...hmmmm.



pkinneb said:


> Yeah I would be with your wife probably not worth tearing out what you have there for it
> 
> Yes I did room within a room with IB3 clips no need for channel, that I am aware of, in that design. I have 1" foam glued to the foundation walls but it is an 1" away from the inner stud wall which is also insulated. I don't recall ever seeing anything that stated that would/could be a problem. The big thing is you do not want to trap moisture so only one moisture barrier on the outer wall. If you use faced insulation like I did in some spots for ease of installation just make sure you slit it liberally once installed to allow air movement.


This is exactly the information I was looking for! Thank you very much. And I think I will heed your advice about tearing down what I already have and save it for another battle...Like what I want to spend on equipment!  I am stil in awe over how good your theater looks and how you accomplished what you did in such a short amount of time. I am barely out of the starting blocks and keep tripping over my own feet!
By the way, I saw you used GG on the ceiling, did you use it on the walls as well?



mhutchins said:


> One possible solution is to build the ceiling first, sealing it against the concrete walls all around the perimeter with each layer of drywall. Clips and channel have been mentioned, and that would be a good choice. But, rather than using the traditional RSIC-style clip, you might consider the Kinetics Wave Hanger. I believe it has a lower resonant frequency than other clips, and should therefore do a slightly better job at isolating the lower frequencies, which are the hardest to control. Furthermore, with the Wave Hanger, kinetics shows completing the ceiling all at once, rather than the typical interlocking pattern of alternating layers between the ceiling and the walls.
> 
> So for your situation, you would finish the ceiling first, before starting the walls. Where the top plate of the new walls meet the ceiling, I would put a thick layer of caulk on the top plate before tipping the wall into place. I would do this by tilting the top of the wall into position first, then slide the bottom into place, thus compressing the caulk against the ceiling. I would try to use a sill plate gasket as well between the sill plate and the concrete floor. Then I would stuff a foam backer rod between the top plate and the ceiling and then do another thick bead of caulk between the ceiling and the top plate. Lastly, I would caulk around the full perimeter of the new wall as each layer of drywall is installed, making sure to seal all gaps between the stud wall and the adjoining concrete walls and ceiling.
> 
> This is all just theory though, as I haven't built anything yet.
> 
> Mike


Thanks Mike. More great advice. Of all the sound clips that I found while researching I had never seen these before. These guys have some pretty cool stuff but I can't find a price on-line. I may give them a call just to see. Nevertheless since I already have the A237R clips I will probably stick with those. I think rather than trying to seal each stud to the concrete walls (since I have the foam board against it), I will make sure that any gaps between the ceiling and concrete walls are well sealed and also seal the along the top plate as you described. I am also planning to follow pkannib's lead and use horse mat under the bottom plate.

So when is the time to start an official build page?


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## VAMatt

DHelmet said:


> So when is the time to start an official build page?


The time is now!


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## poopiehead

jrref said:


> When i see an installation like this, i wonder how you can open the wall and mount speakers and still have the same sound isolation to your neighbors as if the speakers were mounted in front of the wall? As i mentioned, i live in a Townhouse with a common wall. Several years ago with my neighbors permission i took my side of the common wall down and put new roxul safe and sound in his wall, sealed all the outlets, did the same on my side then installed 5/8 inch quiet rock on my side. The result was i got about a 50 db reduction in sound transmission which gives us good isolation but when my neighbor turns up his bass, you can start to hear it because its vibrating the structure. I was thinking of putting a layer of 5/8 inch Quiet Rock over his common wall to minimize the work on his side. Any idea how much this might help?


I think that was why ultimately we left the two adjoining walls and didn't install anything into the walls. We double walled (5/8ths each) on my side and then added a third wall that the in-walls go into. I won't know the impact to my neighbors but will run a sound test to know the limits I can crank it up to.


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## AussieInSeattle

I'm in the planning stages of my build and am trying to maximize the finished height of my ceiling while still soundproofing. My height is 8' (with no finishes) from the slab to underside of 2x12 joists that are 12" OC. My room is 17' x 24' with the joists running parallel to the 17' walls.

What options are there for minimizing the height loss while still getting 60+ STC? Double drywall and green glue is assumed at 1.375". I dont really want to go the isolation clip mounted on the under side of the floor joists route as I would lose ~2.5" with double drywall with greenglue?

This is what I've found so far:
1. isolation clips with channel mounted on cross members I add between the ceiling (floor above joists) - assuming 1/4" gap I would lose 1.625" - lots of work to add the 60+ cross members for the clips though to pick up the inch in height.

2. iso-mount clips - have not seen these mentioned anywhere (I did a search) but the install time seems the same as a normal clip based approach directly to your floor joists (no cross members) - this would get me to 1.625" lost too I think with a 1/4" gap:





Iso-Mount Type1 | Soundproof Ceiling | Oscar Acoustics


Our Oscar Iso-Mount Type1 system is a perfect way to soundproof a room that suffers from noisy upstairs neighbours with minimum ceiling height loss.




www.oscar-acoustics.co.uk




Pricey though at $450+ for 63 clips shipped within the UK (more to the US I assume)


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## Nj6964

I’m planning to put up drywall w/ GG up against my subfloor after cutting off the hardwood nails. I saw my local lumber yard has Certainteed SilentFX in 5/8”. I believe it’s just 2 layers of 5/16” w GG between.

I know 2 layers of 5/8” w GG is the best. However I’m incurious, given the option: Is there any advantage of using 1 layer of plain 5/8 vs 1 layer of SilentFX, GG to the subfloor? Thanks all!


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## TonyHT

As far as putting fiberglass insulation in the wall and ceiling cavities, I know it’s R19 for the ceiling and R13 in the walls. But should it be faced or unfaced?


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## warwwolf7

DHelmet said:


> Thank you Warwwolf. I definitely plan to add insulation on top of the rigid foam board and I will now likely add a second layer of drywall to the walls. I am still thinking about the IB3 clips and if I need to do this if I attach the walls to the ceiling which is floating...hmmmm.
> 
> ?


If it's a budget restriction, look for the "Chinese" ib-3 alternative. I think they have been mentioned in this thread. They are probably exactly the same, but don't take my word for it. 


Envoyé de mon LG-H873 en utilisant Tapatalk


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## kevlo911

Snoochers said:


> Has anyone ever heard of or used these sound isolation clips? They're a lot cheaper than alternatives and still seem to include rubber which is nice compared to the cheaper IB-1 or the like.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Resilient Sound Insulating Drywall Clip EVOLUTION (100 pack) | eBay
> 
> 
> Find many great new & used options and get the best deals for Resilient Sound Insulating Drywall Clip EVOLUTION (100 pack) at the best online prices at eBay! Free shipping for many products!
> 
> 
> 
> www.ebay.com



Hey, I actually just bought some. They seem pretty robust and I'll be buying more. The metal fail safe us the correct size incase the rubber fails and the metal that holds the hat channel seems robust. I'll buy a hat channel or 2 and confirm the fit before I order more. But my initial thoughts are good.


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## Snoochers

kevlo911 said:


> Hey, I actually just bought some. They seem pretty robust and I'll be buying more. The metal fail safe us the correct size incase the rubber fails and the metal that holds the hat channel seems robust. I'll buy a hat channel or 2 and confirm the fit before I order more. But my initial thoughts are good.
> 
> View attachment 3110202
> View attachment 3110203
> View attachment 3110204


I used about 200 of these in my theater !


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## mhutchins

Nj6964 said:


> I’m planning to put up drywall w/ GG up against my subfloor after cutting off the hardwood nails. I saw my local lumber yard has Certainteed SilentFX in 5/8”. I believe it’s just 2 layers of 5/16” w GG between.
> 
> I know 2 layers of 5/8” w GG is the best. However I’m incurious, given the option: Is there any advantage of using 1 layer of plain 5/8 vs 1 layer of SilentFX, GG to the subfloor? Thanks all!


The SilentFX is about 20% more dense than typical Type-X, which is a nice bonus. The density is comparable to most Abuse-Resistant ("AR") drywall products. The big disadvantage is cost. The SilentFX costs ~5x the cost of plain, 5/8" Type-X drywall. If you add the cost of a single tube of Green Glue* (at typical internet prices ~$15.83/tube) the Silent FX only costs twice as much as plain Type-X. 2 layers of Type-X + 1 tube Green Glue costs about 1/3 as much as 2 layers of SilentFX (with no extra Green Glue between layers. 

All of the above comparison assumes no labor charges, which we know is not true in the real world, even when it is DIY. I would expect the SilentFX assembly would outperform the standard Type-X assembly by a small margin (a guess, for sure), but I doubt the difference would be more than 1 STC point (primarily due to the greater density). If it were my room and my money, I would do standard Type-X with Green Glue. I would use the heavier AR drywall if I could find it, provided the cost delta was less than 30% vs. standard Type-X.

Mike

* I only factored in the cost of 1 tube because my assumption (be careful) is that the Certainteed product is only using the equivalent of 1 tube (or less) to cut costs. All my drywall cost estimates were based on a single supplier that carried both the SilentFX and normal Type-X.


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## Rjloper9

kevlo911 said:


> Hey, I actually just bought some. They seem pretty robust and I'll be buying more. The metal fail safe us the correct size incase the rubber fails and the metal that holds the hat channel seems robust. I'll buy a hat channel or 2 and confirm the fit before I order more. But my initial thoughts are good.
> 
> View attachment 3110202
> View attachment 3110203
> View attachment 3110204


I’m planning on using these for my ceiling. Glad to hear they’re well made. Wish they made IB-3 brackets too. Had to buy 50 at $5.99 each


Sent from my iPhone using Tapatalk


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## jrref

poopiehead said:


> I think that was why ultimately we left the two adjoining walls and didn't install anything into the walls. We double walled (5/8ths each) on my side and then added a third wall that the in-walls go into. I won't know the impact to my neighbors but will run a sound test to know the limits I can crank it up to.


Please report back on how your tests go.


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## poopiehead

jrref said:


> Please report back on how your tests go.


won't be able to test the sound until mid April. 

I did add another panel of the sound deadening sheet (Sonopan) behind the back boxes. Doubt that will do much but it was left over.


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## SaskCanesFan

kevlo911 said:


> Hey, I actually just bought some. They seem pretty robust and I'll be buying more. The metal fail safe us the correct size incase the rubber fails and the metal that holds the hat channel seems robust. I'll buy a hat channel or 2 and confirm the fit before I order more. But my initial thoughts are good.
> 
> View attachment 3110202
> View attachment 3110203
> View attachment 3110204





Snoochers said:


> I used about 200 of these in my theater !


Huh, glad I saw these. Cheap, and located quite close to me, and easy to source. If you guys say you like the look/trust them that's probably what I'll go with. Much easier than trying to get things from the US currently. Only thing is making sure they'll hold enough weight as I was thinking of doing 3 layers on the ceiling - plywood first then double drywall just for good measure.


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## MinHeadroom

Not sure if this should be in it’s own topic, but an interesting article on sound proofing windows while allowing air flow was in Nature:









Broadband noise insulation of windows using coiled-up silencers consisting of coupled tubes - Scientific Reports


It has been demonstrated that a staggered window achieves better noise reduction performance than a traditional single glazing one at middle to high frequencies while maintaining a degree of natural ventilation. There is, however, little improvement in the low frequency range. In contrast, this...




www.nature.com


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## warwwolf7

SaskCanesFan said:


> Huh, glad I saw these. Cheap, and located quite close to me, and easy to source. If you guys say you like the look/trust them that's probably what I'll go with. Much easier than trying to get things from the US currently. Only thing is making sure they'll hold enough weight as I was thinking of doing 3 layers on the ceiling - plywood first then double drywall just for good measure.


Remember to follow the right pattern for the clips. You need more clips when you install 3 layers of drywall 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## vintagevancity

Needing help with our soundproofing in our basement.
Here is the plan: We are doing Rockwool safe'n'sound, clips and channel, putty pads on boxes, 2 layers of 5/8, green glue, and acoustic caulking. We have already done the insulation, clips, channel, and putty pads. First layer of drywall is up. Here's where we run into problems...

Help/question 1: Do we *acoustic caulk* around the whole room now? Green glue instructions say if you're in a time crunch don't bother. Does that mean we don't need to and just get it on the 2nd layer?

Help/question 2: The lighting. Yes, we did *ceiling junction lighting boxes* - about 1-4 per room with the plan to install flush LED lighting - on the advice of many and now realizing this might have been a huge mistake. But here we are - no going back now. There's putty pads already installed on all of them. However, when we put up the first layer of drywall and cut out around the boxes, there's gaps. Any suggestions for the best way to fill these gaps? Also, is it necessary to install extenders? And should I put putty pads on those? Alternatively, do I cut my losses here, drill a small hole in the 2nd layer of drywall and thread the lighting wiring through the hole and mount the lighting (which is extremely light) directly to the gypsum?

Help/question 3: There are gaps in between where we've hung the gypsum board and the studs. Should we have cut the gypsum board to fit in there? Any ideas for solutions as this is a huge gap.

Photos ...























Thank you so much in advance!


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## carlobenavidesahavia

Hi guys if I were to design a new house. What would be cheaper and more effective for soundproofing. Design a house with a basement and just soundproof the ceiling or just sound proof a normal room?

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## ambesolman

MinHeadroom said:


> Not sure if this should be in it’s own topic, but an interesting article on sound proofing windows while allowing air flow was in Nature:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Broadband noise insulation of windows using coiled-up silencers consisting of coupled tubes - Scientific Reports
> 
> 
> It has been demonstrated that a staggered window achieves better noise reduction performance than a traditional single glazing one at middle to high frequencies while maintaining a degree of natural ventilation. There is, however, little improvement in the low frequency range. In contrast, this...
> 
> 
> 
> 
> www.nature.com


That’d be a great quarantine project


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## pkinneb

vintagevancity said:


> Needing help with our soundproofing in our basement.
> Here is the plan: We are doing Rockwool safe'n'sound, clips and channel, putty pads on boxes, 2 layers of 5/8, green glue, and acoustic caulking. We have already done the insulation, clips, channel, and putty pads. First layer of drywall is up. Here's where we run into problems...
> 
> Help/question 1: Do we *acoustic caulk* around the whole room now? Green glue instructions say if you're in a time crunch don't bother. Does that mean we don't need to and just get it on the 2nd layer?
> 
> Help/question 2: The lighting. Yes, we did *ceiling junction lighting boxes* - about 1-4 per room with the plan to install flush LED lighting - on the advice of many and now realizing this might have been a huge mistake. But here we are - no going back now. There's putty pads already installed on all of them. However, when we put up the first layer of drywall and cut out around the boxes, there's gaps. Any suggestions for the best way to fill these gaps? Also, is it necessary to install extenders? And should I put putty pads on those? Alternatively, do I cut my losses here, drill a small hole in the 2nd layer of drywall and thread the lighting wiring through the hole and mount the lighting (which is extremely light) directly to the gypsum?
> 
> Help/question 3: There are gaps in between where we've hung the gypsum board and the studs. Should we have cut the gypsum board to fit in there? Any ideas for solutions as this is a huge gap.
> 
> Photos ...
> View attachment 3113627
> View attachment 3113628
> View attachment 3113629
> 
> 
> Thank you so much in advance!


Do you have backer boxes behind the boxes? If not probably the best thing to do is fill with acoustical caulk at this point.


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## warwwolf7

vintagevancity said:


> Needing help with our soundproofing in our basement.
> Here is the plan: We are doing Rockwool safe'n'sound, clips and channel, putty pads on boxes, 2 layers of 5/8, green glue, and acoustic caulking. We have already done the insulation, clips, channel, and putty pads. First layer of drywall is up. Here's where we run into problems...
> 
> Help/question 1: Do we *acoustic caulk* around the whole room now? Green glue instructions say if you're in a time crunch don't bother. Does that mean we don't need to and just get it on the 2nd layer?
> 
> Help/question 2: The lighting. Yes, we did *ceiling junction lighting boxes* - about 1-4 per room with the plan to install flush LED lighting - on the advice of many and now realizing this might have been a huge mistake. But here we are - no going back now. There's putty pads already installed on all of them. However, when we put up the first layer of drywall and cut out around the boxes, there's gaps. Any suggestions for the best way to fill these gaps? Also, is it necessary to install extenders? And should I put putty pads on those? Alternatively, do I cut my losses here, drill a small hole in the 2nd layer of drywall and thread the lighting wiring through the hole and mount the lighting (which is extremely light) directly to the gypsum?
> 
> Help/question 3: There are gaps in between where we've hung the gypsum board and the studs. Should we have cut the gypsum board to fit in there? Any ideas for solutions as this is a huge gap.
> 
> Photos ...
> View attachment 3113627
> View attachment 3113628
> View attachment 3113629
> 
> 
> Thank you so much in advance!


What we see on the pics is the first layer of drywall? Do you have your second layer up already?

If the answer is no, the best solution would be to take the drywall down. install backerbox like @pkinneb said. Then install the drywall back up. Since it's already cut to size, it will go back up much faster than it went up the first time.
If you are putting do much money into this, you should really consider this. Otherwise, you are creating a weakness in the installation and your results will be diminished. To what extent, hard to tell.

You won't get a second chance to get this right once you install the second layer.



Envoyé de mon LG-H873 en utilisant Tapatalk


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## VAMatt

warwwolf7 said:


> What we see on the pics is the first layer of drywall? Do you have your second layer up already?
> 
> If the answer is no, the best solution would be to take the drywall down. install backerbox like @pkinneb said. Then install the drywall back up. Since it's already cut to size, it will go back up much faster than it went up the first time.
> If you are putting do much money into this, you should really consider this. Otherwise, you are creating a weakness in the installation and your results will be diminished. To what extent, hard to tell.
> 
> You won't get a second chance to get this right once you install the second layer.
> 
> 
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk


Agreed. Pulling sheets at this point is pretty easy. Building backer boxes is pretty easy. If you're capable of finishing your own basement, you should be able to knock out 15; 20 backer boxes in a day, and you can probably pull a drywall, install the boxes, and put drywall back up in a single day with a helper.


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## JoelCarlson

I just finished adding a layer of 5/8th drywall to the space between the joists above my theater room. I'm under the assumption that the key thing about adding the drywall between the joists is to add mass. Is there any reason to caulk between the drywall and joists? Some have a gap of around 1/4 inch. As for my theater ceiling itself, I'll be decoupling with a hat channel and adding two layers of 5/8 drywall, making it air tight (along with the wall).


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## warwwolf7

JoelCarlson said:


> I just finished adding a layer of 5/8th drywall to the space between the joists above my theater room. I'm under the assumption that the key thing about adding the drywall between the joists is to add mass. Is there any reason to caulk between the drywall and joists? Some have a gap of around 1/4 inch. As for my theater ceiling itself, I'll be decoupling with a hat channel and adding two layers of 5/8 drywall, making it air tight (along with the wall).


Honestly I don't know,but I applied acoustic sealant around both drywall layer between my joist. I hated every second of it. I had sealant on my arm every time I was applying it above my head. Uuugghhh...

Better put long sleeves in addition to gloves and a hat. I did find that "baby oil" was good at removing sealant on my skin. A lot better for the skin than the traditional paint thinner. 

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## mhutchins

It's not necessary to caulk the seams of the drywall mounted between the joists. That was an old recommendation and further study has shown this to be of no benefit. The primary purpose of the drywall between the joists is to prevent the transmission of impact noise from the floor above. In this case, the performance is not enhanced by caulking the seams. For airborne noise, caulking is absolutely necessary.

Mike


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## da1duc

Did half of the basement with caulk and half without. No difference noticed, not worth the time. Would totally recommend doing the drywall in the ceiling though, HUGE improvement compared to without.


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## squared80

da1duc said:


> Did half of the basement with caulk and half without. No difference noticed, not worth the time. Would totally recommend doing the drywall in the ceiling though, HUGE improvement compared to without.


Specifically, do you mean a huge improvement regarding keeping the floor sound from above getting in, or sound from the theater going up?


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## da1duc

Huge improvement in IIC aka footfall. We have oak flooring on the first floor, three boys, three cats, and a 70 lb dog. Was really noticable half way through doing it. That was when I stopped doing the sealant. Did not hear any difference. 

Now it was an absolute pain to do but cheaper than new floor upstairs.

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## Rjloper9

da1duc said:


> Huge improvement in IIC aka footfall. We have oak flooring on the first floor, three boys, three cats, and a 70 lb dog. Was really noticable half way through doing it. That was when I stopped doing the sealant. Did not hear any difference.
> 
> Now it was an absolute pain to do but cheaper than new floor upstairs.
> 
> Sent from my Pixel 4 using Tapatalk


The area directly above my dedicated room is our master bedroom and bathroom. Bedroom is carpeted and bathroom is ceramic tile.

I’m not overly concerned about the footfall noise from directly above the room, but the adjacent flooring above the theater room is engineered hardwood flooring.

Would you recommend drywall between the joists inside the room in this situation or should that not be a problem bc it’s “outside” the actual footprint of the room?


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## schwock5

i just finished my basement, haven't gotten the subwoofer yet to test that, but went upstairs, and using my remote turned the volume up on music until i could just barely hear it. 
went back down and the sound was so loud in there it would not be a volume i'v even listen to consistently (just peaks during movies). 

i used 2 layers of 5/8 with green glue and clips and channel. the only holes were for atmos speakers which had backer boxes. 
there was also a center light that was put in using one of those blue round boxes cut into the drywall after the fact with putty on one side.
in the ceiling is a flex duct that leads out to the room above as well that could transmit sound.
i did not put drywall within the joist. so just an indicator of the effectiveness what was done.

i will say that as of right now, the weakest part of the room is the door..
went with the thicker door and weather sealing around it. still need to see if it's the door itself or the seal around it, but i think it's just the door.
it's not super loud outside the door, but louder than i was expecting.


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## da1duc

Rjloper9 said:


> The area directly above my dedicated room is our master bedroom and bathroom. Bedroom is carpeted and bathroom is ceramic tile.
> 
> I’m not overly concerned about the footfall noise from directly above the room, but the adjacent flooring above the theater room is engineered hardwood flooring.
> 
> Would you recommend drywall between the joists inside the room in this situation or should that not be a problem bc it’s “outside” the actual footprint of the room?
> 
> 
> Sent from my iPhone using Tapatalk



It is hard for me to say as I have no direct experience yet and I have a lot of flanking with the ceilings still open. Looking at the STC numbers it does go up which makes sense as it increases the mass:










And for my goals it was worth it for the time. Killing ALL of the flanking is going to be fun. 

If you do it recommendations:


Use damaged drywall sheets to lower costs!
Use a load bar to hold one side of the sheet up
it does not need to be pretty
if you are doing two layers you will need two different screw lengths


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## TonyHT

I’m just finishing up with installing my hat channel. When I was looking at my work I realized that I didn’t install the isolation clips with the correct pattern. I basically offset each row of hat channel clips by one stud, but I went back and forth with the offsetting in the same direction for each row.

I wanted to know if this will be fine, or if I should take it all down and redo the isolation clip layout.

I have attached a picture for reference.


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## mhutchins

Personally, I would pull out the channel and redo the spacing. Here are some diagrams. Spacing depends on the number of drywall layers and stud spacing.


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## Eggmanslc

I've tried to browse through here the best I can, admittedly without looking at every single post. But my general question is where do you see the most bang for you buck?

I'm interested in isolation a basement media room/theater room from our main floor kitchen/great room area. I've read about the green glue, double drywall, hat channel, clips, Rockwool (sp?), etc. However, this is not a dedicated space. I have HVAC vents running through it. Currently the room is unfinished, so I have the option to do any number of things, I just don't want to invest the time and money if the HVAC vents will make it all for naught.

I'm interested in both eliminating footfall traffic from above and then isolating the sound from movies below from reaching the area above it, the best I can.

I'm also already dealing with a basement ceiling height of 7' 8", so if I go with double drywall (1 1/4") hat channel (7/8") and isolating clips (5/8"?), then I'm losing 2 3/4", roughly. Perhaps I could scale back and use 1/2" drywall rather than 5/8"... anyway, again, my main concern will be the open HVAC vents that essentially run straight back to our HVAC unit. But maybe that sound gets lost traveling through the ductwork...

Anyway, I'll keep reading, but if any quick replies, come to mind, let me know.


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## mhutchins

As you suggested in your post, soundproofing is only as strong as the weakest link. The HVAC duct sound transmission can be addressed through the use of dead vents for the supply and return ducts for the theater. Good door seals are critical for achieving good sound isolation from the door, which is the usual weak link in any wall. Mass is king when it comes to soundproofing/isolation, so plan on 2 layers of 5/8" Type-X drywall. There has been some experimentation with Henry's carpet glue as an alternative to Green Glue for panel damping. Decoupling also plays a crucial role. If you are on a tight budget, the all metal A237 sound isolation clip is a good value and can be purchased for less than $2 each. Footfall isolation is accomplished by installing two layers of drywall to the bottom of the floor above between the floor joists (Green Glue is the standard here, but there has been some success with carpet glue). Finally, the cheapest fluffy insulation is sufficient to limit resonance within the wall and ceiling cavities.

Mike


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## Eggmanslc

Anyone have any suggested drawings for an air maze? As I can tell, it doesn't go directly in the duct work but just the vent at the end, right?


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## Eggmanslc

mhutchins said:


> As you suggested in your post, soundproofing is only as strong as the weakest link. The HVAC duct sound transmission can be addressed through the use of dead vents for the supply and return ducts for the theater. Good door seals are critical for achieving good sound isolation from the door, which is the usual weak link in any wall. Mass is king when it comes to soundproofing/isolation, so plan on 2 layers of 5/8" Type-X drywall. There has been some experimentation with Henry's carpet glue as an alternative to Green Glue for panel damping. Decoupling also plays a crucial role. If you are on a tight budget, the all metal A237 sound isolation clip is a good value and can be purchased for less than $2 each. Footfall isolation is accomplished by installing two layers of drywall to the bottom of the floor above between the floor joists (Green Glue is the standard here, but there has been some success with carpet glue). Finally, the cheapest fluffy insulation is sufficient to limit resonance within the wall and ceiling cavities.
> 
> Mike


Also, we have an open theater area. More of a family room, so not sure the dead vent approach is really that applicable. 

Plus, I'm looking at these two ceiling options:

















Any opinions about, rather than two layers of drywall directly next to the ceiling as well as below the joists, having one layer next to the ceiling and one suspended is better than 2 suspended?


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## mhutchins

Take a look at the attached files. They may help you decide which way to go.


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## Rjloper9

Snoochers said:


> I used about 200 of these in my theater !


Hey guys. Just bought some myself and won’t be arriving until 5/3.

I’m hoping to get some ceiling drop down measurements prior to their arrival so I can get rolling.

Do either of you know how much depth these add when 7/8” channel is clipped into them?

Thanks!


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## jcr159

Eggmanslc said:


> I've tried to browse through here the best I can, admittedly without looking at every single post. But my general question is where do you see the most bang for you buck?
> 
> I'm interested in isolation a basement media room/theater room from our main floor kitchen/great room area. I've read about the green glue, double drywall, hat channel, clips, Rockwool (sp?), etc. However, this is not a dedicated space. I have HVAC vents running through it. Currently the room is unfinished, so I have the option to do any number of things, I just don't want to invest the time and money if the HVAC vents will make it all for naught.
> 
> I'm interested in both eliminating footfall traffic from above and then isolating the sound from movies below from reaching the area above it, the best I can.
> 
> I'm also already dealing with a basement ceiling height of 7' 8", so if I go with double drywall (1 1/4") hat channel (7/8") and isolating clips (5/8"?), then I'm losing 2 3/4", roughly. Perhaps I could scale back and use 1/2" drywall rather than 5/8"... anyway, again, my main concern will be the open HVAC vents that essentially run straight back to our HVAC unit. But maybe that sound gets lost traveling through the ductwork...
> 
> Anyway, I'll keep reading, but if any quick replies, come to mind, let me know.


i'll say you need to think about goals...

if you really are looking for very quiet, isolated, watch a movie at reference, or 5-10 db from that with a hot bass curve, then you need to do all the things...

here's my experience... caveat, the theater isn't installed yet, but the contractors are still running miter saws, air compressors, sanders, shop vac's, and nailers in the basement.

I have hardwood on the 1st floor above the basement, and PVC drain lines that are noisy when flushed. I was worried because you could hear a lot of foot traffic, and if you just put on a tv or had a conversation in my unfinished basement you could hear the entire conversation upstairs.

what i did:

iso store hush raft "clips" with 1x4 poplar. 
2 layers of 1/2 lightweight drywall with Green Glue. 
Canless LED lights everywhere
3 supply and 2 air returns to HVAC throughout the space
Mitsubishi mini-split
solid core doors including the top of my basement entrance and utility room entrance where my HVAC unit is located
drop seal and weather stripping on door at top of stairs
r19 in joists above ceiling, 2" foamular against wall, studs in front, filled with r13
3/4" foamular on floor, covered with 3/4" OSB

Why I did what I did:

hush raft allowed me to save ceiling height vs traditional clips and channel. it was less labor than recessing clips between the joists with traditional installs and worked well since my joists weren't level anyway.
1/2 inch still let me add damping. damping is more important than the mass unless you can get a lot of it... After some other concessions I realized I needed to make, it made sense to save ceiling height, and labor costs by using smaller, lightweight drywall. Does it impact the bass performance... yep, probably a lot. was I going to notice? nope
As noted above. I needed to add ventilation to the space (air supplies and returns). Dead vents suck... seriously, don't do it... they don't perform well. If you need to do a dead vent, don't... install an ERV/HRV unit to provide fresh air exchange separately to the space, and add a mini split. way better solution. If that is too noisy for you... you can hire someone to install a completely separate ducted system, with the ERV/HRV attached away from the space.
I installed about 25 LED "canless" lights... the thin puck style. I didn't build, buy, or install backer boxes. Why? labor, and expense.. total pain in the butt. the lights are sealed around the edge with gaskets since they are wet location rated. but they don't have the mass that drywall or a backer box would. they saved me a week and thousands of dollars. and what's the point if i have 5 holes for HVAC?
Mini-split isn't very loud. by not very loud, i mean not louder than the PJ fan... i wasn't going to build a hush box, so.... 
insulation on floor walls and ceiling do their job... greatly lowers load calculations for heat/cooling. floor insulation/vapor barrier (plus radon system and sub-slab work when building) allow me to install hardwood below grade. I have exceptional humidity and temp control. it was a crap ton of work, but not as much work as jackhammering the floor to relocate bathroom stub outs, main beam support columns, drilling and rebar, and busting out the wall to pump concrete to fill it all back in.
Since I knew I wasn't completely decoupling everything, I skipped decoupling the walls. no DD+GG on the walls. Walls are standard construction, no putty pads, and directly coupled to the joists above. Soffits are directly coupled to the joists as well where I built them.
only the ceiling and soffits got DD+GG.

what are the results?:

As I said, the theater isn't in yet, but I can comment on some of what I hear (or don't, lol). 

Water, flushing, pipe noises are completely gone... can't hear it at all.
Door isn't installed at the top of my steps, so it's still hollow core, with a 1.5" gap cut on the bottom. Most noise coming from the basement is through the door. 
I can hear some noise on the 1st floor through the vents... things like tools, shop vac, etc, can be heard, but not loudly. Conversation cannot be heard, nor can the contractors "boom box". You wouldn't be able to tell anything is going on from the second floor.
My basement is not "open concept" in that it's not one big room, but the theater area is around a couple corners and as far from the stairs as possible. I only mention that to say that noise generated from that area travels less than activity happening near/in the stairwell.
Footfall activity is gone unless folks are jumping/dancing/tik tok upstairs... good enough for me
Based on how much noise has been damped, the door at the top of the stairs and seals should make for "good enough" for me
All in all, I had enough concessions I needed to make that it wasn't worth it to try and get that level of soundproofing where I could watch a movie at -10 or louder without anyone noticing in the rest of the house. But I think I have enough reduction that on the first floor, it will be tolerable, and on the second floor probably noticeable from the bass, but not obnoxious. Turn it down to -15 or -20 at night, and folks will be able to sleep just fine. The cost, and more the time, wasn't worth it to me. and I realized the use case of needing to watch a movie full tilt wen the rest of my family was asleep doesn't happen enough to justify the expense... My driving factor was that my kids are at the stage where they are starting to do sleep overs and all night video game marathons with friends... as long as I don't hear them keeping me up, good enough... but I don't want it too quiet, lol

Many will think I wasted money with the GG, but I do think it made a noticeable difference. If you can't swing the cost of GG, the hush raft was worth it since I couldn't attach drywall right to the joists anyway... they are frequently less level than ya think....


----------



## Eggmanslc

mhutchins said:


> Take a look at the attached files. They may help you decide which way to go.


These are fantastic resources. Thank you.


----------



## Eggmanslc

I've had 3 drywallers come bid my basement and I've asked them about sound isolation. One guy suggested one layer of acoustical drywall directly up against the joists, resilient channel, and then a layer of standard drywall. Has anyone come across this option before? It seems to be what they recommend for max noise isolation. They have done the dual sheets with green glue as well, but seem to recommend this other option (I'm sure they like it better as it is less labor intensive).

I'm not planning on doing much in my walls, just the ceiling, as there is where I want to isolate noise primarily. In addition to this drywall configuration, I will have blown cellulose throughout.

Will this proposed drywall construction create a "triple leaf"? This post would seem to suggest it is.









Understanding the Triple Leaf Effect and air cavity depth


The bottom line: For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key.



www.soundproofingcompany.com





So perhaps just having them layer both drywall layers together off channel is better.


----------



## Eggmanslc

jcr159 said:


> i'll say you need to think about goals...
> 
> if you really are looking for very quiet, isolated, watch a movie at reference, or 5-10 db from that with a hot bass curve, then you need to do all the things...
> 
> here's my experience... caveat, the theater isn't installed yet, but the contractors are still running miter saws, air compressors, sanders, shop vac's, and nailers in the basement.
> 
> I have hardwood on the 1st floor above the basement, and PVC drain lines that are noisy when flushed. I was worried because you could hear a lot of foot traffic, and if you just put on a tv or had a conversation in my unfinished basement you could hear the entire conversation upstairs.
> 
> what i did:
> 
> iso store hush raft "clips" with 1x4 poplar.
> 2 layers of 1/2 lightweight drywall with Green Glue.
> Canless LED lights everywhere
> 3 supply and 2 air returns to HVAC throughout the space
> Mitsubishi mini-split
> solid core doors including the top of my basement entrance and utility room entrance where my HVAC unit is located
> drop seal and weather stripping on door at top of stairs
> r19 in joists above ceiling, 2" foamular against wall, studs in front, filled with r13
> 3/4" foamular on floor, covered with 3/4" OSB
> 
> Why I did what I did:
> 
> hush raft allowed me to save ceiling height vs traditional clips and channel. it was less labor than recessing clips between the joists with traditional installs and worked well since my joists weren't level anyway.
> 1/2 inch still let me add damping. damping is more important than the mass unless you can get a lot of it... After some other concessions I realized I needed to make, it made sense to save ceiling height, and labor costs by using smaller, lightweight drywall. Does it impact the bass performance... yep, probably a lot. was I going to notice? nope
> As noted above. I needed to add ventilation to the space (air supplies and returns). Dead vents suck... seriously, don't do it... they don't perform well. If you need to do a dead vent, don't... install an ERV/HRV unit to provide fresh air exchange separately to the space, and add a mini split. way better solution. If that is too noisy for you... you can hire someone to install a completely separate ducted system, with the ERV/HRV attached away from the space.
> I installed about 25 LED "canless" lights... the thin puck style. I didn't build, buy, or install backer boxes. Why? labor, and expense.. total pain in the butt. the lights are sealed around the edge with gaskets since they are wet location rated. but they don't have the mass that drywall or a backer box would. they saved me a week and thousands of dollars. and what's the point if i have 5 holes for HVAC?
> Mini-split isn't very loud. by not very loud, i mean not louder than the PJ fan... i wasn't going to build a hush box, so....
> insulation on floor walls and ceiling do their job... greatly lowers load calculations for heat/cooling. floor insulation/vapor barrier (plus radon system and sub-slab work when building) allow me to install hardwood below grade. I have exceptional humidity and temp control. it was a crap ton of work, but not as much work as jackhammering the floor to relocate bathroom stub outs, main beam support columns, drilling and rebar, and busting out the wall to pump concrete to fill it all back in.
> Since I knew I wasn't completely decoupling everything, I skipped decoupling the walls. no DD+GG on the walls. Walls are standard construction, no putty pads, and directly coupled to the joists above. Soffits are directly coupled to the joists as well where I built them.
> only the ceiling and soffits got DD+GG.
> 
> what are the results?:
> 
> As I said, the theater isn't in yet, but I can comment on some of what I hear (or don't, lol).
> 
> Water, flushing, pipe noises are completely gone... can't hear it at all.
> Door isn't installed at the top of my steps, so it's still hollow core, with a 1.5" gap cut on the bottom. Most noise coming from the basement is through the door.
> I can hear some noise on the 1st floor through the vents... things like tools, shop vac, etc, can be heard, but not loudly. Conversation cannot be heard, nor can the contractors "boom box". You wouldn't be able to tell anything is going on from the second floor.
> My basement is not "open concept" in that it's not one big room, but the theater area is around a couple corners and as far from the stairs as possible. I only mention that to say that noise generated from that area travels less than activity happening near/in the stairwell.
> Footfall activity is gone unless folks are jumping/dancing/tik tok upstairs... good enough for me
> Based on how much noise has been damped, the door at the top of the stairs and seals should make for "good enough" for me
> All in all, I had enough concessions I needed to make that it wasn't worth it to try and get that level of soundproofing where I could watch a movie at -10 or louder without anyone noticing in the rest of the house. But I think I have enough reduction that on the first floor, it will be tolerable, and on the second floor probably noticeable from the bass, but not obnoxious. Turn it down to -15 or -20 at night, and folks will be able to sleep just fine. The cost, and more the time, wasn't worth it to me. and I realized the use case of needing to watch a movie full tilt wen the rest of my family was asleep doesn't happen enough to justify the expense... My driving factor was that my kids are at the stage where they are starting to do sleep overs and all night video game marathons with friends... as long as I don't hear them keeping me up, good enough... but I don't want it too quiet, lol
> 
> Many will think I wasted money with the GG, but I do think it made a noticeable difference. If you can't swing the cost of GG, the hush raft was worth it since I couldn't attach drywall right to the joists anyway... they are frequently less level than ya think....


This is fantastically helpful. So appreciated. I'll look at those hush rafts. Which LED's did you go with? You're still recessing in the drywall, right? So you have holes cut? A contractor friend suggested placing putty pads on the back of this style light. 

Also, if you happen to have a picture of your ceiling assembly pre-drywall, let me know. Would love to see how those hush rafts work with the poplar you suggested.


----------



## Eggmanslc

jcr159 said:


> i'll say you need to think about goals...
> 
> if you really are looking for very quiet, isolated, watch a movie at reference, or 5-10 db from that with a hot bass curve, then you need to do all the things...
> 
> here's my experience... caveat, the theater isn't installed yet, but the contractors are still running miter saws, air compressors, sanders, shop vac's, and nailers in the basement.
> 
> I have hardwood on the 1st floor above the basement, and PVC drain lines that are noisy when flushed. I was worried because you could hear a lot of foot traffic, and if you just put on a tv or had a conversation in my unfinished basement you could hear the entire conversation upstairs.
> 
> what i did:
> 
> iso store hush raft "clips" with 1x4 poplar.
> 2 layers of 1/2 lightweight drywall with Green Glue.
> Canless LED lights everywhere
> 3 supply and 2 air returns to HVAC throughout the space
> Mitsubishi mini-split
> solid core doors including the top of my basement entrance and utility room entrance where my HVAC unit is located
> drop seal and weather stripping on door at top of stairs
> r19 in joists above ceiling, 2" foamular against wall, studs in front, filled with r13
> 3/4" foamular on floor, covered with 3/4" OSB
> 
> Why I did what I did:
> 
> hush raft allowed me to save ceiling height vs traditional clips and channel. it was less labor than recessing clips between the joists with traditional installs and worked well since my joists weren't level anyway.
> 1/2 inch still let me add damping. damping is more important than the mass unless you can get a lot of it... After some other concessions I realized I needed to make, it made sense to save ceiling height, and labor costs by using smaller, lightweight drywall. Does it impact the bass performance... yep, probably a lot. was I going to notice? nope
> As noted above. I needed to add ventilation to the space (air supplies and returns). Dead vents suck... seriously, don't do it... they don't perform well. If you need to do a dead vent, don't... install an ERV/HRV unit to provide fresh air exchange separately to the space, and add a mini split. way better solution. If that is too noisy for you... you can hire someone to install a completely separate ducted system, with the ERV/HRV attached away from the space.
> I installed about 25 LED "canless" lights... the thin puck style. I didn't build, buy, or install backer boxes. Why? labor, and expense.. total pain in the butt. the lights are sealed around the edge with gaskets since they are wet location rated. but they don't have the mass that drywall or a backer box would. they saved me a week and thousands of dollars. and what's the point if i have 5 holes for HVAC?
> Mini-split isn't very loud. by not very loud, i mean not louder than the PJ fan... i wasn't going to build a hush box, so....
> insulation on floor walls and ceiling do their job... greatly lowers load calculations for heat/cooling. floor insulation/vapor barrier (plus radon system and sub-slab work when building) allow me to install hardwood below grade. I have exceptional humidity and temp control. it was a crap ton of work, but not as much work as jackhammering the floor to relocate bathroom stub outs, main beam support columns, drilling and rebar, and busting out the wall to pump concrete to fill it all back in.
> Since I knew I wasn't completely decoupling everything, I skipped decoupling the walls. no DD+GG on the walls. Walls are standard construction, no putty pads, and directly coupled to the joists above. Soffits are directly coupled to the joists as well where I built them.
> only the ceiling and soffits got DD+GG.
> 
> what are the results?:
> 
> As I said, the theater isn't in yet, but I can comment on some of what I hear (or don't, lol).
> 
> Water, flushing, pipe noises are completely gone... can't hear it at all.
> Door isn't installed at the top of my steps, so it's still hollow core, with a 1.5" gap cut on the bottom. Most noise coming from the basement is through the door.
> I can hear some noise on the 1st floor through the vents... things like tools, shop vac, etc, can be heard, but not loudly. Conversation cannot be heard, nor can the contractors "boom box". You wouldn't be able to tell anything is going on from the second floor.
> My basement is not "open concept" in that it's not one big room, but the theater area is around a couple corners and as far from the stairs as possible. I only mention that to say that noise generated from that area travels less than activity happening near/in the stairwell.
> Footfall activity is gone unless folks are jumping/dancing/tik tok upstairs... good enough for me
> Based on how much noise has been damped, the door at the top of the stairs and seals should make for "good enough" for me
> All in all, I had enough concessions I needed to make that it wasn't worth it to try and get that level of soundproofing where I could watch a movie at -10 or louder without anyone noticing in the rest of the house. But I think I have enough reduction that on the first floor, it will be tolerable, and on the second floor probably noticeable from the bass, but not obnoxious. Turn it down to -15 or -20 at night, and folks will be able to sleep just fine. The cost, and more the time, wasn't worth it to me. and I realized the use case of needing to watch a movie full tilt wen the rest of my family was asleep doesn't happen enough to justify the expense... My driving factor was that my kids are at the stage where they are starting to do sleep overs and all night video game marathons with friends... as long as I don't hear them keeping me up, good enough... but I don't want it too quiet, lol
> 
> Many will think I wasted money with the GG, but I do think it made a noticeable difference. If you can't swing the cost of GG, the hush raft was worth it since I couldn't attach drywall right to the joists anyway... they are frequently less level than ya think....


Oh, do your 1x4 poplar pieces create the grid that you actually hung drywall from?


----------



## jcr159

Eggmanslc said:


> Oh, do your 1x4 poplar pieces create the grid that you actually hung drywall from?


yep, and the cans are just cut through both layers. I wouldn’t putty the back as it will likely mess with the cooling and overheat the LED’s...


----------



## jcr159

Btw, you shouldn’t use faced insulation if you can avoid it.. I let the contractor use it cause it saved him time and it won’t make a huge difference in my side walls... the joist cavities are stuffed pretty good though


----------



## Snoochers

Eggmanslc said:


> I've had 3 drywallers come bid my basement and I've asked them about sound isolation. One guy suggested one layer of acoustical drywall directly up against the joists, resilient channel, and then a layer of standard drywall. Has anyone come across this option before? It seems to be what they recommend for max noise isolation. They have done the dual sheets with green glue as well, but seem to recommend this other option (I'm sure they like it better as it is less labor intensive).
> 
> I'm not planning on doing much in my walls, just the ceiling, as there is where I want to isolate noise primarily. In addition to this drywall configuration, I will have blown cellulose throughout.
> 
> Will this proposed drywall construction create a "triple leaf"? This post would seem to suggest it is.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Understanding the Triple Leaf Effect and air cavity depth
> 
> 
> The bottom line: For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key.
> 
> 
> 
> www.soundproofingcompany.com
> 
> 
> 
> 
> 
> So perhaps just having them layer both drywall layers together off channel is better.


Yep that sounds like triple leaf to me. My drywall guys suggested the same thing but I told them to just put three layers on the resilient channel.


----------



## Snoochers

Rjloper9 said:


> Hey guys. Just bought some myself and won’t be arriving until 5/3.
> 
> I’m hoping to get some ceiling drop down measurements prior to their arrival so I can get rolling.
> 
> Do either of you know how much depth these add when 7/8” channel is clipped into them?
> 
> Thanks!
> 
> 
> Sent from my iPhone using Tapatalk


I think the dimensions are identical or almost identical to the competitor sound clip with the black rubber. I based it on that.


----------



## Rjloper9

My room has several long runs of flex duct running through the upstairs floor joist cavities.

I’m am doing 3 layers of 5/8” on clips and channel on my ceiling.

Do I need to worry about boxing in these long runs of flex duct or will stuffing the ceiling with insulation and the 3 layers of drywall be sufficient to keep sound from traveling through all of them?








In the pic....looking from front of the room to the back. The square duct is the end of the main line. There’s 2 lines splitting off towards the front of the room and 3-4 splitting off towards the back of the room to other areas of the house.

Thanks!


Sent from my iPhone using Tapatalk


----------



## jcr159

Rjloper9 said:


> My room has several long runs of flex duct running through the upstairs floor joist cavities.
> 
> I’m am doing 3 layers of 5/8” on clips and channel on my ceiling.
> 
> Do I need to worry about boxing in these long runs of flex duct or will stuffing the ceiling with insulation and the 3 layers of drywall be sufficient to keep sound from traveling through all of them?
> 
> 
> 
> 
> 
> 
> 
> 
> In the pic....looking from front of the room to the back. The square duct is the end of the main line. There’s 2 lines splitting off towards the front of the room and 3-4 splitting off towards the back of the room to other areas of the house.
> 
> Thanks!
> 
> 
> Sent from my iPhone using Tapatalk


If that ductwork is connected to the rest of your house, you are wasting money on the 3 layers... 

the easiest path for deep bass to travel will be the ductwork. The only real reason to add more mass in the assembly is to lower the resonant frequency and reduce deep bass transmission. But the ductwork is a much more effective path for that type of sound To travel. I’m a believer how in the targeted approach unless you can separate the air handling... in other words, my approach above has a lot of obvious holes lol. But I dis 2 layers of lightweight 1/2 inch with green glue because the damping does have effect at vocal frequencies, and with all my compromises bass was never going to be contained. So I made life easier and live with the consequences. If you can’t live with compromise, follow the drill... separate hvac/dead vents, the whole 9 yards...


----------



## Rjloper9

jcr159 said:


> If that ductwork is connected to the rest of your house, you are wasting money on the 3 layers...
> 
> the easiest path for deep bass to travel will be the ductwork. The only real reason to add more mass in the assembly is to lower the resonant frequency and reduce deep bass transmission. But the ductwork is a much more effective path for that type of sound To travel. I’m a believer how in the targeted approach unless you can separate the air handling... in other words, my approach above has a lot of obvious holes lol. But I dis 2 layers of lightweight 1/2 inch with green glue because the damping does have effect at vocal frequencies, and with all my compromises bass was never going to be contained. So I made life easier and live with the consequences. If you can’t live with compromise, follow the drill... separate hvac/dead vents, the whole 9 yards...


I had already conceded on not being able to keep the low frequency from escaping, but wanted to mitigate as much as I could.

It’s been suggested to go with 3 on my ceiling from several top contributors on here so I figured the extra $150-175 for a third layer of 5/8” drywall would be worth it.


Sent from my iPhone using Tapatalk


----------



## jcr159

Rjloper9 said:


> I had already conceded on not being able to keep the low frequency from escaping, but wanted to mitigate as much as I could.
> 
> It’s been suggested to go with 3 on my ceiling from several top contributors on here so I figured the extra $150-175 for a third layer of 5/8” drywall would be worth it.
> 
> 
> Sent from my iPhone using Tapatalk


It won’t hurt, lol!


----------



## TonyHT

How do you soundproof around the projector? I plan on mounting it to the ceiling, but I will need to soundproof around the HDMI cable and power cable. Do most people have an outlet installed in the ceiling for the projector?


----------



## jcr159

TonyHT said:


> How do you soundproof around the projector? I plan on mounting it to the ceiling, but I will need to soundproof around the HDMI cable and power cable. Do most people have an outlet installed in the ceiling for the projector?


Yeah, you should do that... further, you should run that outlet to an equipment area and install a male outlet which creates an in wall, to code, extension cord. Then locate your battery backup with the equipment to protect the PJ and let it run the cooling fan if you lose power.


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## Eggmanslc

jcr159 said:


> Btw, you shouldn’t use faced insulation if you can avoid it.. I let the contractor use it cause it saved him time and it won’t make a huge difference in my side walls... the joist cavities are stuffed pretty good though


I'm going to be doing blow in cellulose in my basement. It's mostly been wired previous to our moving in and then there are existing ducts. I figure that will be the easiest to fit in around all the existing stuff that's already there in certain joists. Your room is looking very nice!


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## jcr159

Eggmanslc said:


> I'm going to be doing blow in cellulose in my basement. It's mostly been wired previous to our moving in and then there are existing ducts. I figure that will be the easiest to fit in around all the existing stuff that's already there in certain joists. Your room is looking very nice!


good call on blown in!

and thanks!


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## Pultzar

Hello!

I am currently reading through this thread about 15% of the way through. Tons of great info here, thank you everybody! I couldn't wait to start asking questions though.

My wife and I are in the process of building a new custom home which includes a very large space for a bar+projector room+theater currently labeled as "unfinished storage". The plan is for the house to be finished for move-in first, then we will build out this space.

The three exterior walls are concrete and a mix of above/below grade. My plan is to do a room-within-a-room construction with interior walls along the top/bottom and then a new set of joists going across to hang a ceiling from. The floor is concrete insulated from below and will probably end up with a sub floor/carpet for most of the space.

Like most of you, I'm trying to mitigate sound travelling through the house and to neighbors. This is a dead quiet neighborhood and I like to listen loud at night.

Current questions:

1) Concrete walls + 2x4 framing + insulation + DD GG - How does this perform?
2) The wall next to the stairs - should this be a double wall? The stairs lead all the way to bedrooms. Plumbing and electrical will probably make its way through this wall. How is that handled?
3) HVAC - Should I be venting with the main house or have a totally independent system that vents to the outside directly? Or some combo like fresh air from the main house and temperature control via mini-split systems?
4) This house is a very expensive project. Are there good consultants who my architects can work with on the fine details? The last thing I want to do is hit 95% and then a weak link makes the sound proofing efforts fail for unknown reasons. I'm learning all I can though.

I'm planning on a door from Overly then a short hallway to the theater then another door.










Since I'm dealing with a rectangle in new construction I'm hoping the solution path is simpler than a retrofit, but it needs to be done properly.


----------



## squared80

Pultzar said:


> Hello!
> 
> I am currently reading through this thread about 15% of the way through. Tons of great info here, thank you everybody! I couldn't wait to start asking questions though.
> 
> My wife and I are in the process of building a new custom home which includes a very large space for a bar+projector room+theater currently labeled as "unfinished storage". The plan is for the house to be finished for move-in first, then we will build out this space.
> 
> The three exterior walls are concrete and a mix of above/below grade. My plan is to do a room-within-a-room construction with interior walls along the top/bottom and then a new set of joists going across to hang a ceiling from. The floor is concrete insulated from below and will probably end up with a sub floor/carpet for most of the space.
> 
> Like most of you, I'm trying to mitigate sound travelling through the house and to neighbors. This is a dead quiet neighborhood and I like to listen loud at night.
> 
> Current questions:
> 
> 1) Concrete walls + 2x4 framing + insulation + DD GG - How does this perform?
> 2) The wall next to the stairs - should this be a double wall? The stairs lead all the way to bedrooms. Plumbing and electrical will probably make its way through this wall. How is that handled?
> 3) HVAC - Should I be venting with the main house or have a totally independent system that vents to the outside directly? Or some combo like fresh air from the main house and temperature control via mini-split systems?
> 4) This house is a very expensive project. Are there good consultants who my architects can work with on the fine details? The last thing I want to do is hit 95% and then a weak link makes the sound proofing efforts fail for unknown reasons. I'm learning all I can though.
> 
> I'm planning on a door from Overly then a short hallway to the theater then another door.
> 
> View attachment 3129690
> 
> 
> Since I'm dealing with a rectangle in new construction I'm hoping the solution path is simpler than a retrofit, but it needs to be done properly.


You should create a new dedicated thread for your build. Easier to track and for people to help.


----------



## Pultzar

squared80 said:


> You should create a new dedicated thread for your build. Easier to track and for people to help.


Done!









Final Answer - Build Thread


After man years, I recently finished a beautiful black velvet home theater in my existing house. During this time I always told my wife it was "The Prototype" and she laughed. I wasn't kidding. We are in the process of building a new custom home which includes a very large space for a...




www.avsforum.com


----------



## squared80

I was ready to buy a bunch of OC 703 for my build, but after some last minute comparisons, it looks like 4" Roxul Rockboard can give me just about the exact same results as 4" OC 703 for half the price. I am putting it behind my front stage, and also as bass absorbers in my corners. And maybe my ceiling and walls.

Two questions.
1) I've seen the reported sound absorption coefficients, but does anyone have real world experience they can speak to when using Roxul Rockboard vs OC 703? How about Roxul AFB?
2) I have a room within a room. The outer walls have 3.5" R-13 batt insulation. I was going to do the same with my inner walls AND my ceiling between the joists, but would I get a better result by using Roxul Rockboard or Roxul AFB instead of standard batt?

Small room. 24Lx10Wx8H. 9.2.6 setup w/ RF-7 III as LCR and dual HSU VTF3 MK5's.


----------



## AnnapolisSony

When my drywall contractor pulled my front stage speaker wires and coaxial subwoofer cables through the double gang box, they picked up quite a bit of green glue. He finished his work a little over a week ago so the GG has had some time to set up on the wires/cable. What is my best bet to clean them off? Acetone? Goof Off?

The Cat6 line at my PJ location (coming in through ceiling) was the only casualty from GG as I forgot to tape up the end (thankful that the fiber optic HDMI made it out unscathed). Thank God Big had suggested to run a conduit in the ceiling from my PJ location - it was a piece of cake to pull another 50-foot Cat6 through and replace it!


----------



## warwwolf7

AnnapolisSony said:


> When my drywall contractor pulled my front stage speaker wires and coaxial subwoofer cables through the double gang box, they picked up quite a bit of green glue. He finished his work a little over a week ago so the GG has had some time to set up on the wires/cable. What is my best bet to clean them off? Acetone? Goof Off?
> 
> The Cat6 line at my PJ location (coming in through ceiling) was the only casualty from GG as I forgot to tape up the end (thankful that the fiber optic HDMI made it out unscathed). Thank God Big had suggested to run a conduit in the ceiling from my PJ location - it was a piece of cake to pull another 50-foot Cat6 through and replace it!


Clean green glue with acetone. Use gloves, and use a little as possible on a rag. 

Envoyé de mon LG-H873 en utilisant Tapatalk


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## squared80

I'm not sure if it's been posted in here, but for soundproofing the inside of the walls (mostly for lower frequencies), Rockwool AFB performs fantastic and measures better than some far more expensive options. I couldn't find it cheaper anywhere than Insulation4US (link below). The biggest key here is shipping charges, which was only $60 for 12 bags of 2" Rockwool AFB (192 batts). Check it out!









Insulation4US - Wholesale Insulation For Sale


Insulation4US offers top-quality insulation products and accessories. We offer fast delivery and affordable prices. Call us today at (786) 224 0029




insulation4us.com


----------



## warwwolf7

squared80 said:


> I'm not sure if it's been posted in here, but for soundproofing the walls, Rockwool AFB performs fantastic and measures better than some far more expensive options. I couldn't find it cheaper anywhere than Insulation4US (link below). The biggest key here is shipping charges, which was only $60 for 12 bags of 2" Rockwool AFB (192 batts). Check it out!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Insulation4US - Wholesale Insulation For Sale
> 
> 
> Insulation4US offers top-quality insulation products and accessories. We offer fast delivery and affordable prices. Call us today at (786) 224 0029
> 
> 
> 
> 
> insulation4us.com


Can you provide the study or the paper with the measurements where you got that information that AFB perform fantastic and measured better? Thank you
The insulation inside the cavity is the factor that make the least difference amongst the four.
Using cheap pink fluffy stuff or rockwool makes very little difference in soundproofing and it does cost more.



Envoyé de mon LG-H873 en utilisant Tapatalk


----------



## jcr159

warwwolf7 said:


> Can you provide the study or the paper with the measurements where you got that information that AFB perform fantastic and measured better? Thank you
> The insulation inside the cavity is the factor that make the least difference amongst the four.
> Using cheap pink fluffy stuff or rockwool makes very little difference in soundproofing and it does cost more.
> 
> 
> 
> Envoyé de mon LG-H873 en utilisant Tapatalk



True, but more importantly.... If lower frequencies get "into" the wall... you've already lost the battle... 

keeping them from escaping the room shell is the name of the game...


----------



## squared80

jcr159 said:


> True, but more importantly.... If lower frequencies get "into" the wall... you've already lost the battle...
> 
> keeping them from escaping the room shell is the name of the game...


Right, but before channels and DDGG and 4-6" of acoustical panels, if you plan on filling the cavities with something, get a product designed for low frequency, not high. And products like AFB or Thermafiber excel in that arena compared to other fiberglass products.


----------



## jcr159

squared80 said:


> Right, but before channels and DDGG and 4-6" of acoustical panels, if you plan on filling the cavities with something, get a product designed for low frequency, not high. And products like AFB or Thermafiber excel in that arena compared to other fiberglass products.


I don't disagree, but would simply say that to echo another earlier post...

there's not enough measurable difference (in any 3rd party testing I've seen) to tell me the cavity insulation type makes any difference in low frequencies.

I'll baseline by defining low frequencies as anything below say 100ish Hz. At those frequencies, you'd need at least 8" of cavity insulation to absorb much of anything which just isn't there in most construction envelopes... It's also such a small percentage of the sound control (for low frequencies), you are effectively throwing money away. Any benefit at higher frequencies is moot, as regular pink fluffy in a 2x4 cavity already addresses that adequately.

The extra expense would be better spend to do other things that are more helpful, like dead venting (don't do it! lol), installing a mini split, room within a room, more putty pads, more backer boxes, more green glue, etc... 

that said, it's not my theater, or wallet...  
there's great value in peace of mind!


----------



## calincole

I am in the planning and prepping phase of a build and I have a question that I haven't been able to find explicit answers too.

When building a room within a room where the top plate of the walls are connected with DC04 clips, how are the bottom plates handled? Are the secured to the floor with screws/nails as in normal construction? if not, how are they fixed in place? I've seen reference to some kind of underlayment, what is typically used? 

Any insight on this would be appreciated, thanks.


----------



## jerrolds

Hey everyone - HT room is framed (double wall on interior walls)











*Questions*
1. Can i get away with just double 5/8" drywall + GG on the North and East wall? In other words, do i need a hat channel (and clips?)
2. Will Sonopan boards be as effective as 5/8" + GG. Stud -> Sonopan + 5/8" - or is Sonopan just a gimmick
3. Since West/South walls are exterior walls (they have vapor barrier as well), is double drywall (or sonopan + drywall) still needed?

Thans`ks


----------



## squared80

The hat channels are about decoupling the drywall from the wood frame and the rest of the house, as you know. Any direct connections will negate some of the results you've worked so hard to implement. Don't go in half-assed at this point! I say do it all or not at all.


----------



## mhutchins

calincole said:


> I am in the planning and prepping phase of a build and I have a question that I haven't been able to find explicit answers too.
> 
> When building a room within a room where the top plate of the walls are connected with DC04 clips, how are the bottom plates handled? Are the secured to the floor with screws/nails as in normal construction? if not, how are they fixed in place? I've seen reference to some kind of underlayment, what is typically used?
> 
> Any insight on this would be appreciated, thanks.


Yes, typically the bottom plate is attached as in normal construction, however, this creates a flanking path through the floor/slab into the rest of the house. Best practice is to use an isolation layer between the bottom plate and the mounting surface. Typically this is a dense rubber or fiberglass product designed for this purpose. Horse stall mats have also been suggested as a less expensive isolation material between the bottom plate and the floor/slab. If you go to the trouble of isolating the bottom plate, don’t short circuit the isolation by failing to use isolation washers between the anchor and the bottom plate. Here is a drawing by Kinetics Noise Control showing the isolation material between the bottom plate and the floor as well as an isolation grommet assembly for the anchor. This example is for a steel stud wall, but the same method can be used with wood framing.

Mike


----------



## mhutchins

squared80 said:


> *The hat channels are about decoupling the wood frame from the rest of the house*, as you know. Any direct connections will negate some of the results you've worked so hard to implement. Don't go in half-assed at this point! I say do it all or not at all.


I think you misspoke about the decoupling purpose of hat channel (in the phrase I highlighted above). I think you meant to say that it’s purpose is to decouple the drywall from the framing, thus preventing a direct connection between the sound in the theater from the rest of the house. 

DC04 clips are often used as a means to brace the interior framing of a room-in-room design to the outer framing or structure while limiting the degree of sound transmission through such attachments. 

I just didn’t want any confusion to enter the discussion through an unintended misstatement.

Mike


----------



## Rjloper9

calincole said:


> I am in the planning and prepping phase of a build and I have a question that I haven't been able to find explicit answers too.
> 
> When building a room within a room where the top plate of the walls are connected with DC04 clips, how are the bottom plates handled? Are the secured to the floor with screws/nails as in normal construction? if not, how are they fixed in place? I've seen reference to some kind of underlayment, what is typically used?
> 
> Any insight on this would be appreciated, thanks.


I used the 3/4” horse stall mats under my bottom plate as recommended by @BIGmouthinDC. They cut easily with a fresh box cutter blade. Secured them to the bottom plate with 1 1/4” cabinet screws and then the whole assembly to the floor with 3 1/4” tapcons










Sent from my iPhone using Tapatalk


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## squared80

mhutchins said:


> I think you misspoke about the decoupling purpose of hat channel (in the phrase I highlighted above). I think you meant to say that it’s purpose is to decouple the drywall from the framing, thus preventing a direct connection between the sound in the theater from the rest of the house.
> 
> DC04 clips are often used as a means to brace the interior framing of a room-in-room design to the outer framing or structure while limiting the degree of sound transmission through such attachments.
> 
> I just didn’t want any confusion to enter the discussion through an unintended misstatement.
> 
> Mike


Correct, decoupling drywall from the wood frame and the rest of the house. Thanks.


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## squared80

Rjloper9 said:


> I used the 3/4” horse stall mats under my bottom plate as recommended by @BIGmouthinDC. They cut easily with a fresh box cutter blade. Secured them to the floor with 3 1/4” tapcons


No code issues with that?


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## Rjloper9

squared80 said:


> No code issues with that?


Not that I’m aware of. I have seen this done on several other builds as well. I still used pressure treated for my bottom plate as well.


Sent from my iPhone using Tapatalk


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## BIGmouthinDC

squared80 said:


> No code issues with that?


Like what? Various barriers have been placed under the sill plates for years and those are load bearing exterior walls. These are interior partition walls.


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## calincole

Appreciate the response guys, very helpful. I am sure I will have more questions to come as the planning progresses.


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## squared80

BIGmouthinDC said:


> Like what? Various barriers have been placed under the sill plates for years and those are load bearing exterior walls. These are interior partition walls.


Right, but I hadn't seen a partition that thick before (I've seen tar paper-like things), and I didn't know if this was a load bearing wall or not, either. Just asking questions because I don't know.


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## jcr159

BIGmouthinDC said:


> Like what? Various barriers have been placed under the sill plates for years and those are load bearing exterior walls. These are interior partition walls.


thumbs up to Matt's videos...

good info in there for all sorts of topics... watch up folks... recently i saw an interesting video showing an interview with door manufacturers on the difference between "solid core" doors, and others... not exactly what you think. "solid wood" is what most of us think "solid core" is... if i remember the terminology correctly! marketing trickery!


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## BIGmouthinDC

Never thought solid core was a solid piece of wood, more like MDF inside. You don't want a solid piece of wood.


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## jcr159

BIGmouthinDC said:


> Never thought solid core was a solid piece of wood, more like MDF inside. You don't want a solid piece of wood.


True, but looking at the inside of some of the MDF slurry inside some of the other doors makes it look like there are plenty of voids…. It was interesting nonetheless!


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## pkinneb

squared80 said:


> Right, but I hadn't seen a partition that thick before (I've seen tar paper-like things), and I didn't know if this was a load bearing wall or not, either. Just asking questions because I don't know.


I had no code issues (it was inspected and signed off on) with my walls which I used the horse mat rubber under, none were bearing walls. Having said that its unlikely you would be building a theater using a bearing wall. Typically you either have room within a room or clips and channel on existing construction.


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## warwwolf7

jerrolds said:


> Hey everyone - HT room is framed (double wall on interior walls)
> 
> 
> View attachment 3138056
> 
> 
> *Questions*
> 1. Can i get away with just double 5/8" drywall + GG on the North and East wall? In other words, do i need a hat channel (and clips?)
> 2. Will Sonopan boards be as effective as 5/8" + GG. Stud -> Sonopan + 5/8" - or is Sonopan just a gimmick
> 3. Since West/South walls are exterior walls (they have vapor barrier as well), is double drywall (or sonopan + drywall) still needed?
> 
> Thans`ks


Double wall is pretty much a better equivalent of hat and channel. You can add hat and channel, but the return on investment is minimal. You'd be better off spending that money on a third layer of drywall on that double wall. 

Envoyé de mon SM-G986W en utilisant Tapatalk


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## batlin27

My contractor will be placing open-cell spray foam at the exterior walls and under the side of the roof deck of air-conditioned spaces. My theater will have interior walls, Exterior and Exterior to garage walls. So the plan would be R11 (or whatever is best) on the interior walls and then they plan on open-cell spray phone on the Garage and exterior walls.

I have read that you should stay away from Spray Foams due to them transferring sound more efficiently than pink fluffy. I live in Texas and it gets HOT in the Garage and Out Side and I don't want to compromise the rest of my houses energy efficiency by telling my contactor to not spray foam the exterior walls in the theater

Another note, the room is setup as a room within a room / chase walls


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## jcr159

batlin27 said:


> My contractor will be placing open-cell spray foam at the exterior walls and under the side of the roof deck of air-conditioned spaces. My theater will have interior walls, Exterior and Exterior to garage walls. So the plan would be R11 (or whatever is best) on the interior walls and then they plan on open-cell spray phone on the Garage and exterior walls.
> 
> I have read that you should stay away from Spray Foams due to them transferring sound more efficiently than pink fluffy. I live in Texas and it gets HOT in the Garage and Out Side and I don't want to compromise the rest of my houses energy efficiency by telling my contactor to not spray foam the exterior walls in the theater
> 
> Another note, the room is setup as a room within a room / chase walls
> 
> View attachment 3141806


id say you don’t want open cell. You need vapor barrier, hence closed cell….


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## batlin27

jcr159 said:


> id say you don’t want open cell. You need vapor barrier, hence closed cell….


From a structural standpoint, we doing a ZIP system so that should take care of the vapor barrier... I think...


----------



## jcr159

batlin27 said:


> From a structural standpoint, we doing a ZIP system so that should take care of the vapor barrier... I think...


My bad, was thinking the walls were below grade. Most places started that below grade you need vapor barrier on the inside insulation…. Not that it’s always a good idea depending on how the building envelope is constructed. 
from a sound perspective though, don’t count on any help from open or closed cell foam. You’ll get a bit from open cell, but pink fluffy will be a better solution. 
from a heat transfer perspectiv, you’ll get probably double the performance from spray foam, mostly related to installation quality. Check out GBA though youll probably need to pay for access to read a lot of the articles.


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## b_scott

what's everyone's favorite way to soundproof the back of a door? trying to not buy a new door, so I have the original which is only 1 3/8" thick around the edges (solid) with the center being decorative thinner wood. Thinking MLV, or quilted fiberglass, or pads of some sort. Looking for best ideas. Thanks!

edit: ok I purchased some MLV to cover it, but I also want to put some soft damping material over that if anyone has good ideas. thanks!


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## calincole

Are there any additional sizing considerations when framing the rough opening for a doorway in a double wall setup? Obviously I will have to deal with the thickness of the doorway is much more than normal, but is there a need to make it wider or taller than the standard size rough opening for the door size of your choice?


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## Technology3456

My HT room was not planned, and sound travels through the walls. I am worried about the sound from subwoofers and speakers traveling out the space. Any ideas what can be done _*on*-_wall, and thin (i.e., fits behind curtains, more or less. Some bumps in the curtains is not a big deal though), to prevent that? There are 2 separate issues, really: 1. Sound treatment to improve audio quality (for both speakers and subs). 2. Treatment to keep the sound traveling out of the room. I will be having black "velvet" curtains everywhere, but have heard different takes whether this will have any effect by itself. Appreciate any advice.


----------



## da1duc

batlin27 said:


> From a structural standpoint, we doing a ZIP system so that should take care of the vapor barrier... I think...


You are doing a double wall correct? If so have them do a flash and batt setup. Just did closed cell and rockwool on 3.5" walls for my full basement. Only had a few sections that the spray foam was too thick. Just watch that with the double wall and foam (closed or open) it will lock the two walls together (even open will). You need that to be completely decoupled.


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## warwwolf7

Technology3456 said:


> My HT room was not planned, and sound travels through the walls. I am worried about the sound from subwoofers and speakers traveling out the space. Any ideas what can be done _*on*-_wall, and thin (i.e., fits behind curtains, more or less. Some bumps in the curtains is not a big deal though), to prevent that? There are 2 separate issues, really: 1. Sound treatment to improve audio quality (for both speakers and subs). 2. Treatment to keep the sound traveling out of the room. I will be having black "velvet" curtains everywhere, but have heard different takes whether this will have any effect by itself. Appreciate any advice.


Hi, I'm not an expert.

Curtains will do nothing soundproofing wise in the bass region. It might reduce the higher frequency transmission but not by much and it depends on how its installed. It will reduce the sound reflection in the room, but I don't know much in that area.

One way To reduce sound transmission outside of the room without opening your wall, would require you to add 1 or 2 layer of drywall on top of the one already installed. However, the return on investment might be lower than stripping everything and installing hat and channel and 1 layer. Look for the cnrc papers on the stc for different wall types.
You might be better if you remove current drywall and add hat-channel + 1x 5/8 typex vs adding 1layer 5/8type X.
Do you have Rockwool or pink fuffly stuffy inside the cavity of your wall?


If you don't want to open your wall, don't expect too much by adding drywall on top. You won't have decoupling, you will have a little bit more mass, your wall cavity might be empty, so no absorption there, no dampening.

If you don't want to rip the drywall. You could add green glue behind the second layer of drywall. You would then have a little bit of damping. 


Soundproofing Principles




Manage your expectations, and you might end up happy with the result. Soundproofing is tricky. You miss one pt and the entire effort and money is wasted. 

Also, do you have a door in your room? If soo, it could become your weakest link. Make sure to upgrade it to a solid core door.

If you haven't done yet, Read the first 200 posts of this thread. They contain a gold mine of information.

I hope this help you to narrow your search. 

Envoyé de mon SM-G986W en utilisant Tapatalk


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## Technology3456

warwwolf7 said:


> Hi, I'm not an expert.
> 
> Curtains will do nothing soundproofing wise in the bass region. It might reduce the higher frequency transmission but not by much and it depends on how its installed. It will reduce the sound reflection in the room, but I don't know much in that area.
> 
> One way To reduce sound transmission outside of the room without opening your wall, would require you to add 1 or 2 layer of drywall on top of the one already installed. However, the return on investment might be lower than stripping everything and installing hat and channel and 1 layer. Look for the cnrc papers on the stc for different wall types.
> You might be better if you remove current drywall and add hat-channel + 1x 5/8 typex vs adding 1layer 5/8type X.
> Do you have Rockwool or pink fuffly stuffy inside the cavity of your wall?
> 
> 
> If you don't want to open your wall, don't expect too much by adding drywall on top. You won't have decoupling, you will have a little bit more mass, your wall cavity might be empty, so no absorption there, no dampening.
> 
> If you don't want to rip the drywall. You could add green glue behind the second layer of drywall. You would then have a little bit of damping.
> 
> 
> Soundproofing Principles
> 
> 
> 
> 
> Manage your expectations, and you might end up happy with the result. Soundproofing is tricky. You miss one pt and the entire effort and money is wasted.
> 
> Also, do you have a door in your room? If soo, it could become your weakest link. Make sure to upgrade it to a solid core door.
> 
> If you haven't done yet, Read the first 200 posts of this thread. They contain a gold mine of information.
> 
> I hope this help you to narrow your search.
> 
> Envoyé de mon SM-G986W en utilisant Tapatalk


Tyvm. I was hoping there were thin panels you could hang on the wall that would keep noise from escaping the room. Or maybe some type of carpet on the upper floor that would keep some of the sound from going through the carpet. It sounds like there is nothing that can do this? The back half of my room has a ton of concrete, it's sealed in, but the rest including the ceiling is pretty thin.

Assuming I have can't do a thing about it, but I still want to watch movies at reference levels (using two HSU Research VTF-2 MK5 12 inch subwoofers), how loud is it going to be on the floor above, and how how far outside of the house is it going to still be a problem? The next house five feet to the side of mine is going to hear it, or not? 100 meters away, they will hear it, or not? Just trying to get a rough idea. First rodeo.


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## warwwolf7

Technology3456 said:


> Tyvm. I was hoping there were thin panels you could hang on the wall that would keep noise from escaping the room. Or maybe some type of carpet on the upper floor that would keep some of the sound from going through the carpet. It sounds like there is nothing that can do this? The back half of my room has a ton of concrete, it's sealed in, but the rest including the ceiling is pretty thin.
> 
> Assuming I have can't do a thing about it, but I still want to watch movies at reference levels (using two HSU Research VTF-2 MK5 12 inch subwoofers), how loud is it going to be on the floor above, and how how far outside of the house is it going to still be a problem? The next house five feet to the side of mine is going to hear it, or not? 100 meters away, they will hear it, or not? Just trying to get a rough idea. First rodeo.


Too much variable to take into consideration (that are not described here) to give you any hypothesis.
If you say you want to listen to reference level and ceiling is pretty thin. Then expect it to be very audible. On the floor above. That's as precise of a guess you'll get. 
The bass, is the one that's most likely going to be annoying to your neighbors. But it depends on how low your system can go.


Again, read the first 200 posts of this thread you will learn a lot.

Maybe other members will chime in with other solutions, I don't posses the complete soundproofing knowledge, only a small portion.

Read the first 200 post of this thread if you haven't already. You will have answers to your questions and, to the question you did not think of yet. I won't comment any further until you do your homework 

Envoyé de mon SM-G986W en utilisant Tapatalk


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## Technology3456

warwwolf7 said:


> Too much variable to take into consideration (that are not described here) to give you any hypothesis.
> If you say you want to listen to reference level and ceiling is pretty thin. Then expect it to be very audible. On the floor above. That's as precise of a guess you'll get.
> The bass, is the one that's most likely going to be annoying to your neighbors. But it depends on how low your system can go.
> 
> 
> Again, read the first 200 posts of this thread you will learn a lot.
> 
> Maybe other members will chime in with other solutions, I don't posses the complete soundproofing knowledge, only a small portion.
> 
> Read the first 200 post of this thread if you haven't already. You will have answers to your questions and, to the question you did not think of yet. I won't comment any further until you do your homework
> 
> Envoyé de mon SM-G986W en utilisant Tapatalk


Thanks for giving your best guess. I am reading the early pages of the thread right now. Thanks for pointing me to them.


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## jcr159

Technology3456 said:


> Thanks for giving your best guess. I am reading the early pages of the thread right now. Thanks for pointing me to them.


unfortunately, the hardest thing to contain is the bass... it's also the most annoying part to people in other parts of the house/neighbors...

it's actually the "reference" level part that is going to cost you a lot of money as well... I DON'T have an all in solution... only a lot of stuff "mostly" done right, and can listen at -10 or so, with my subs running hot without bothering my family 2 floors above too much. Can they hear it? yep. but not enough to ask me to turn it down. That said, if I pulled the bass back a little bit and turned it down to -15, I can probably watch after folks go to bed in my house without issues.

and i don't have separate HVAC systems, in fact it's my weakest point. But 2 floors up is the big factor. 1 floor up is a different story. Had I needed to finish my basement to totally isolate to that level, I would have needed a totally separate HVAC system, including fresh air exchange, 30 more backer boxes, and rebuilding 2 stair cases to my upper floors to get them decoupled from the structure entirely... 

Don't let anyone convince you to dead vent btw... I don't think they work that well. I added a mini- split, and it is crazy quiet. don't cheap out and get a good mitsubishi unit. that said, if you seal things up that well, you still need fresh air, just install an ERV/HRV depending on where you are that is isolated. it keeps fresh air in the space, and the mini conditions the air.


----------



## Technology3456

jcr159 said:


> unfortunately, the hardest thing to contain is the bass... it's also the most annoying part to people in other parts of the house/neighbors...
> 
> it's actually the "reference" level part that is going to cost you a lot of money as well... I DON'T have an all in solution... only a lot of stuff "mostly" done right, and can listen at -10 or so, with my subs running hot without bothering my family 2 floors above too much. Can they hear it? yep. but not enough to ask me to turn it down. That said, if I pulled the bass back a little bit and turned it down to -15, I can probably watch after folks go to bed in my house without issues.
> 
> and i don't have separate HVAC systems, in fact it's my weakest point. But 2 floors up is the big factor. 1 floor up is a different story. Had I needed to finish my basement to totally isolate to that level, I would have needed a totally separate HVAC system, including fresh air exchange, 30 more backer boxes, and rebuilding 2 stair cases to my upper floors to get them decoupled from the structure entirely...
> 
> Don't let anyone convince you to dead vent btw... I don't think they work that well. I added a mini- split, and it is crazy quiet. don't cheap out and get a good mitsubishi unit. that said, if you seal things up that well, you still need fresh air, just install an ERV/HRV depending on where you are that is isolated. it keeps fresh air in the space, and the mini conditions the air.


My problem is I cant HVAC at all, I cant dead vent, I cant do anything. Its a multi-purpose room being converted into a makeshift home theater. I can hang stuff on the wall, that's about it. And maybe staple to the ceiling. Nothing can go in the wall or the ceiling thats not already there. I think its just dry wall, wood, and normal insulation.

Edit: and I will have black "velvet" curtains on the ceiling and walls. Can choose between Whaley's and SY Triple Black Velvet in various places. That's it.


----------



## jcr159

Technology3456 said:


> My problem is I cant HVAC at all, I cant dead vent, I cant do anything. Its a multi-purpose room being converted into a makeshift home theater. I can hang stuff on the wall, that's about it. And maybe staple to the ceiling. Nothing can go in the wall or the ceiling thats not already there. I think its just dry wall, wood, and normal insulation.
> 
> Edit: and I will have black "velvet" curtains on the ceiling and walls. Can choose between Whaley's and SY Triple Black Velvet in various places. That's it.


bummer. been there for sure. 

unfortunately, without being able to attach something structural, you won't have much luck. Anything that you can "hang" or put in the room won't help outside the room. it will probably make things sound a lot better to you in the room though! 

One thing that may help "some" depending on how much sympathetic vibration you are getting, is decouplers for your subs. something squishy under the subs helps decouple any vibration from the sub from the floors. I use Neoprene camping mat cut to size from Amazon. but mouse pads work fine. If you wanna just test to see if it helps at all, a folded up comforter is a good stand in temporarily. And you want to play bass sweeps from 20-120 hz on repeat, then move around in and outside the room. 

You may want to look into a nice headphone option. Not being snarky, but maybe during the daytime when neighbors/housemates can tolerate the noise, you just crank it and say it will be over in 2 hours... but after dark, switch to a really nice set of headphones? 

Otherwise, bust out the tools unfortunately. If it's a rental, sometimes you can negotiate to make changes on your dollar if it won't affect the value of the unit. Worth looking into if it's that important to ya...

trying to give ya some options, good luck!


----------



## Technology3456

jcr159 said:


> bummer. been there for sure.
> 
> unfortunately, without being able to attach something structural, you won't have much luck. Anything that you can "hang" or put in the room won't help outside the room. it will probably make things sound a lot better to you in the room though!
> 
> One thing that may help "some" depending on how much sympathetic vibration you are getting, is decouplers for your subs. something squishy under the subs helps decouple any vibration from the sub from the floors. I use Neoprene camping mat cut to size from Amazon. but mouse pads work fine. If you wanna just test to see if it helps at all, a folded up comforter is a good stand in temporarily. And you want to play bass sweeps from 20-120 hz on repeat, then move around in and outside the room.
> 
> You may want to look into a nice headphone option. Not being snarky, but maybe during the daytime when neighbors/housemates can tolerate the noise, you just crank it and say it will be over in 2 hours... but after dark, switch to a really nice set of headphones?
> 
> Otherwise, bust out the tools unfortunately. If it's a rental, sometimes you can negotiate to make changes on your dollar if it won't affect the value of the unit. Worth looking into if it's that important to ya...
> 
> trying to give ya some options, good luck!


Thanks for the help. I understand you can hang sound absorption on the walls to lower reflections and make the audio in the room clearer, but if they are absorbing sound, doesnt that mean less is reflecting back out of the room, or something? Or maybe I could hang one sound absorption panel, and then one panel made of material to absorb the sound and keep it traveling out of the room, (edit: and alternate throughout the room, I mean. Obviously just one would do nothing). 

Basically, whatever people put inside their walls in 12 inches thick chunks, maybe I could hang panels with 2 inch chunks of it all over the walls? Only 15%-20% as much, but maybe it will help a little?

I'm just looking to do what I can, even if it only helps 15% or 20%. Something is better than nothing. But from what you're telling me, there may be no way to even achieve that without going into the walls. But if there is anything at all I can hang or put on the ceiling, without it sticking out 6 inches+, to help even 15% or 20%, that would be my first step.


----------



## jcr159

Technology3456 said:


> Thanks for the help. I understand you can hang sound absorption on the walls to lower reflections and make the audio in the room clearer, but if they are absorbing sound, doesnt that mean less is reflecting back out of the room, or something? Or maybe I could hang one sound absorption panel, and then one panel made of material to absorb the sound and keep it traveling out of the room, (edit: and alternate throughout the room, I mean. Obviously just one would do nothing).
> 
> Basically, whatever people put inside their walls in 12 inches thick chunks, maybe I could hang panels with 2 inch chunks of it all over the walls? Only 15%-20% as much, but maybe it will help a little?
> 
> I'm just looking to do what I can, even if it only helps 15% or 20%. Something is better than nothing. But from what you're telling me, there may be no way to even achieve that without going into the walls. But if there is anything at all I can hang or put on the ceiling, without it sticking out 6 inches+, to help even 15% or 20%, that would be my first step.


I guess to put it simply... will it help? maybe. How much? you'll need a measurement mic to tell. your ears won't hear a difference. That would be the level probably... unless you essentially construct a room inside your existing room that doesn't attach. 

That said.... if you for example lined all the walls with 6 inches of insulation (and it would need to be all, including the ceiling, otherwise sound would hit that surface at full intensity and resonate the panel), it might control some of the vocal region and higher such that voices wouldn't propagate.

but remember what i said about bass? yeah, it wouldn't do a thing pretty much, and all the annoyance is still there...


----------



## calincole

HVAC question:

I am evaluating a basement room I have and trying to formulate a plan to deal with HVAC issues. The room is already on the central air system. While I would prefer to remove it from that system and install a minisplit, that may not be viable given the location and air circulation requirements. If I cannot accomplish that, and I must leave the room serviced by the existing central air system, how would I go about soundproofing this and what level of success could I expect?

I would have complete access to the ductwork and be able to treat it in most any way, up to and including completely replacing it. There is a section of the main supply and return trunks located in the ceiling of this space that also servers the living room above, it cannot be removed but it can be altered/replaced to an extent. My goal is entirely about keeping sound generated in the room in it. I understand the benefits of lowering the noise floor and such, but my real goal here is to be able to use the space to the fullest extent while minimizing disturbance to others in the house. Assume that the rest of the room will be built with decoupled framing and DD+GG and pink stuff etc.

Any insight is appreciated and let me know any additional details needed.


----------



## squared80

calincole said:


> HVAC question:
> 
> I am evaluating a basement room I have and trying to formulate a plan to deal with HVAC issues. The room is already on the central air system. While I would prefer to remove it from that system and install a minisplit, that may not be viable given the location and air circulation requirements. If I cannot accomplish that, and I must leave the room serviced by the existing central air system, how would I go about soundproofing this and what level of success could I expect?
> 
> I would have complete access to the ductwork and be able to treat it in most any way, up to and including completely replacing it. There is a section of the main supply and return trunks located in the ceiling of this space that also servers the living room above, it cannot be removed but it can be altered/replaced to an extent. My goal is entirely about keeping sound generated in the room in it. I understand the benefits of lowering the noise floor and such, but my real goal here is to be able to use the space to the fullest extent while minimizing disturbance to others in the house. Assume that the rest of the room will be built with decoupled framing and DD+GG and pink stuff etc.
> 
> Any insight is appreciated and let me know any additional details needed.


I'm in the same boat. The reality is, any HVAC running through that room that's connected to the main system is not going to be able to prevent sound from traveling throughout the system.

First, I eliminated almost all the plenum and replaced it with flexduct. I then opened up the giant return structure and lined it with dampening, and also put in a rat maze of 'egg crate' foam padding. I covered the outside of the return vents with more dampening. Then it will all be covered in Rockwool RFB and closed up in the DD+GG.

There are great resources on these forums; check the build threads, too. Most will say to run a mini-split, or to create dead vents (which I personally don't think are worth it), but there are plenty of options to help the issue.

But again, if your main system is running through the room, you can't avoid sound escaping.


----------



## mhutchins

Within the HVAC literature, the two concepts that you are addressing are noise "Breakin" and "Breakout". Noise breakin is the process of noise from the environment "breaking in" or entering the ductwork from the external environment. 

In your situation, noise breakin will occur in the ducts that pass through the area above the ceiling over the theater. The amount of breakin is a function of the surface area of the duct exposed to the noise, the loudness of the noise and the transmission loss of the noise as it passes through the duct wall into the interior of the duct. Most insulated ducts offer little resistance to low-mid frequency breakin. 

The best way to eliminate breakin is to reroute the ductwork away from the theater, but this is often impractical. The next best thing is to decrease the loudness of the noise impinging on the duct through the wall or ceiling adjacent to the duct run. Typical methods include the 4 tenets of sound proofing: mass, decoupling, damping and absorption. The more you can reduce the noise transmission through your ceiling to the area where the ductwork is located, the less noise that will enter the ductwork. 

The next area to address to minimize breakin is to reduce the transmission through the duct wall itself. This is accomplished the same way as reducing sound transmission through your walls: mass, decoupling, damping and absorption. This is typically more difficult than reducing the sound transmission through the ceiling due to space limitations and the geometry of the ducts themselves. Note that flexduct is relatively ineffective at reducing breakin.

Once the noise has entered the duct, absorption is the primary means of reducing noise transmission through the duct to the rest of the HVAC system. This is where dead vents and mufflers are used to try to absorb as much of the noise as possible before it reaches the rest of the HVAC system. Any ductwork that terminates in the theater has the additional consideration of noise transmission through the grille into the ductwork in addition to noise that may enter the duct via breakin.

Finally, breakout is the transmission of noise inside the duct into areas where it is not desired. It is addressed in the same ways as breakin noise is prevented.

One other source of HVAC noise is airflow noise from turbulence of the air as it travels through ducts and grilles or diffusors. This source of noise is most readily addressed through minimizing air velocity and through proper selection of grilles and diffusors.

Mike


----------



## calincole

squared80 said:


> I'm in the same boat. The reality is, any HVAC running through that room that's connected to the main system is not going to be able to prevent sound from traveling throughout the system.
> 
> First, I eliminated almost all the plenum and replaced it with flexduct. I then opened up the giant return structure and lined it with dampening, and also put in a rat maze of 'egg crate' foam padding. I covered the outside of the return vents with more dampening. Then it will all be covered in Rockwool RFB and closed up in the DD+GG.
> 
> There are great resources on these forums; check the build threads, too. Most will say to run a mini-split, or to create dead vents (which I personally don't think are worth it), but there are plenty of options to help the issue.
> 
> But again, if your main system is running through the room, you can't avoid sound escaping.


Thanks Squared80. I am guessing from the way you phrased this that your work is ongoing and you haven't been able to see how well it has worked yet, is that right? If not, how successful has this been for you?



mhutchins said:


> Within the HVAC literature, the two concepts that you are addressing are noise "Breakin" and "Breakout". Noise breakin is the process of noise from the environment "breaking in" or entering the ductwork from the external environment.
> 
> In your situation, noise breakin will occur in the ducts that pass through the area above the ceiling over the theater. The amount of breakin is a function of the surface area of the duct exposed to the noise, the loudness of the noise and the transmission loss of the noise as it passes through the duct wall into the interior of the duct. Most insulated ducts offer little resistance to low-mid frequency breakin.
> 
> The best way to eliminate breakin is to reroute the ductwork away from the theater, but this is often impractical. The next best thing is to decrease the loudness of the noise impinging on the duct through the wall or ceiling adjacent to the duct run. Typical methods include the 4 tenets of sound proofing: mass, decoupling, damping and absorption. The more you can reduce the noise transmission through your ceiling to the area where the ductwork is located, the less noise that will enter the ductwork.
> 
> The next area to address to minimize breakin is to reduce the transmission through the duct wall itself. This is accomplished the same way as reducing sound transmission through your walls: mass, decoupling, damping and absorption. This is typically more difficult than reducing the sound transmission through the ceiling due to space limitations and the geometry of the ducts themselves. Note that flexduct is relatively ineffective at reducing breakin.
> 
> Once the noise has entered the duct, absorption is the primary means of reducing noise transmission through the duct to the rest of the HVAC system. This is where dead vents and mufflers are used to try to absorb as much of the noise as possible before it reaches the rest of the HVAC system. Any ductwork that terminates in the theater has the additional consideration of noise transmission through the grille into the ductwork in addition to noise that may enter the duct via breakin.
> 
> Finally, breakout is the transmission of noise inside the duct into areas where it is not desired. It is addressed in the same ways as breakin noise is prevented.
> 
> One other source of HVAC noise is airflow noise from turbulence of the air as it travels through ducts and grilles or diffusors. This source of noise is most readily addressed through minimizing air velocity and through proper selection of grilles and diffusors.
> 
> Mike


Appreciate the detailed run down, thanks.


----------



## vlotty

Have done a lot of reading and understand basic principles, but most of the discussion has been around home theater and studio applications which is to be expected here, haha.

I’m having trouble translating the principles to what is worth it for just a shared wall between rooms in a high rise with concrete slab ceiling and subfloors, that share an exterior wall that’s been framed and drywalled (one layer 5/8”) and with doors that are near each other (catty-corner). There is mineral rock insulation and metal studs, no back to back electrical boxes because the wall isn’t thick enough due to studs. Also no shared vents/ductwork. 

The goal is not total soundproofing, just muffled or low audible sound from loud talking and reasonable TV/music sound.

Thinking about doing just double 5/8” drywall on one side (due to space), maybe with GG, but not sure if just DD would be sufficient for this application, or if none of it will matter because I’m not able to seal off the entire room (no putty, acoustical caulk, hat clips etc due to cost/implementation and space)?

Basically does only doing DD on one side of a shared interior wall make any difference? If it would make an appreciable difference, in this setup would GG add any real life noticeable dampening?

Thanks for any thoughts!


----------



## jcr159

vlotty said:


> Have done a lot of reading and understand basic principles, but most of the discussion has been around home theater and studio applications which is to be expected here, haha.
> 
> I’m having trouble translating the principles to what is worth it for just a shared wall between rooms in a high rise with concrete slab ceiling and subfloors, that share an exterior wall that’s been framed and drywalled (one layer 5/8”) and with doors that are near each other (catty-corner). There is mineral rock insulation and metal studs, no back to back electrical boxes because the wall isn’t thick enough due to studs. Also no shared vents/ductwork.
> 
> The goal is not total soundproofing, just muffled or low audible sound from loud talking and reasonable TV/music sound.
> 
> Thinking about doing just double 5/8” drywall on one side (due to space), maybe with GG, but not sure if just DD would be sufficient for this application, or if none of it will matter because I’m not able to seal off the entire room (no putty, acoustical caulk, hat clips etc due to cost/implementation and space)?
> 
> Basically does only doing DD on one side of a shared interior wall make any difference? If it would make an appreciable difference, in this setup would GG add any real life noticeable dampening?
> 
> Thanks for any thoughts!


just drywall will do very little. Another layer with green glue will probably take care of everything other than low frequencystuff like vibrations, footfall type noise, deep bass. But it will be a noticeable improvement. Though the door situLatino makes me nervous without seeing a sketch it’s hard for me to grasp.


----------



## vlotty

jcr159 said:


> just drywall will do very little. Another layer with green glue will probably take care of everything other than low frequencystuff like vibrations, footfall type noise, deep bass. But it will be a noticeable improvement. Though the door situLatino makes me nervous without seeing a sketch it’s hard for me to grasp.


So in your estimation just a 5/8” DD wall (three layers total on the wall) with mineral wool insulation with steel studs and no GG wouldn’t have much effect but if I add GG then it will achieve the goal?

Here’s a (very rough) sketch of the layout if it helps, thanks!


----------



## jcr159

vlotty said:


> So in your estimation just a 5/8” DD wall (three layers total on the wall) with mineral wool insulation with steel studs and no GG wouldn’t have much effect but if I add GG then it will achieve the goal?
> 
> Here’s a (very rough) sketch of the layout if it helps, thanks!
> 
> View attachment 3148168


sketch is awesome! Helps a lot.

how well it works depends on goals. If you are willing to hang a layer of Sheetrock, the benefits are a lot greater with GG. Especially above 250Hz or so….

talking, yelling, TV, “adult activities” will be blocked pretty well that way. Bass from your sub? It will help, but not as much as you’d want…


----------



## vlotty

jcr159 said:


> sketch is awesome! Helps a lot.
> 
> how well it works depends on goals. If you are willing to hang a layer of Sheetrock, the benefits are a lot greater with GG. Especially above 250Hz or so….
> 
> talking, yelling, TV, “adult activities” will be blocked pretty well that way. Bass from your sub? It will help, but not as much as you’d want…


Those would pretty much cover what we’re trying to block/minimize. One thing that I’m still not sure about is what the impact is of the single 5/8” drywall on metal studs (attached to the exterior concrete wall) that’s shared, with there being like 2-3” of space between drywall and exterior wall all long the exterior face will be. I’m not sure if we can still add insulation (maybe spray foam?) or if we have the budget to add double drywall to that face (and if that will make any difference?). Would the metal studs attached to the concrete be basically transferring most of the energy into the exterior walls rather than the air in the cavity?

Am I right that most of the sound we’re concerned about would be attenuated by the DD and GG shared wall still?

Appreciate your thoughts!


----------



## ambesolman

Finally getting the waterproofing needed for my basement done tomorrow. They’ll be installing a French drain along this outer wall, around the fireplace with the sump pump in the corner to the right of the fireplace under the window.

My plan is to build a room within a room using clips, channel and ddgg. However, I’m kind of at a loss as to the best way to do this because of the fireplace. Framing the walls an inch off the existing walls will already be further out than the brick surrounding the fireplace. 

Any thoughts or suggestions?



















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## squared80

So... you're keeping the fireplace in your home theater that's full of heat and smoke and soot sensitive equipment that already requires a lot of HVAC work to clear out noxious gases and replenish with fresh air? Or did I misunderstand.

If so, you just dismantle the base, close off the chimney stack (professionally), then seal up the hole. You have some pipes on that wall so it looks like you may need to start your wall a few inches out from the foundation, anyway, so the wall will just go in front of what's left of the fireplace brick after you've removed that big base. Get the sledgehammer warmed up!

I would suggest creating your own build thread in the appropriate forum.

Link: Dedicated Theater Design & Construction


----------



## ambesolman

squared80 said:


> So... you're keeping the fireplace in your home theater that's full of heat and smoke and soot sensitive equipment that already requires a lot of HVAC work to clear out noxious gases and replenish with fresh air? Or did I misunderstand.
> 
> If so, you just dismantle the base, close off the chimney stack (professionally), then seal up the hole. You have some pipes on that wall so it looks like you may need to start your wall a few inches out from the foundation, anyway, so the wall will just go in front of what's left of the fireplace brick after you've removed that big base. Get the sledgehammer warmed up!
> 
> I would suggest creating your own build thread in the appropriate forum.
> 
> Link: Dedicated Theater Design & Construction


Build thread should be in my sig though they don’t appear in Tapatalk if you’re using that too.

Thanks for your suggestion. It’s definitely the right way to do it from a soundproofing standpoint and have kicked the same idea around myself. We had the chimneys cleaned before moving in since the inspector said he wouldn’t build a fire in there until they had been. Said it looked like a lot of pine had been burned in there too causing a potentially hazardous buildup.

We’ve never used the fireplace in the four years we’ve been here, but the room’s pretty much been in the state you see now. I was unsure if anyone would suggest removing the base (hearth?) and just making a removable plug that could be removed “in case of emergency” and I needed to build a fire (however unlikely that might be). Any idea how the chimney would be permanently sealed?

There’s a crawl space on the other side of the far yellow wall that’d had a water leak for years from an uncapped P trap coming off the main drainage line you mentioned in the pics. I ripped the room apart to see how much damage there may be, but I got lucky and didn’t see any coming through that wall from the crawl space.


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## squared80

ambesolman said:


> Any idea how the chimney would be permanently sealed?


In order to have it sealed so nothing will get in or out (specifically, water or animals), I would have a professional do it for ease of mind, if anything. $200-300. But it's not difficult and you can certainly do it yourself, just check out YouTube and Google. But do it right or you will pay the price later. That's why I'd pay a pro and just be done with it.


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## calincole

ambesolman said:


> Any idea how the chimney would be permanently sealed?


With the disclaimer that I have no idea about codes in your area and your home and your comfort with this type of thing and all that, I will tell you what I did. 

I have 2 flues that exhaust from the chimney right next to each other. This caused a problem where when one was used and the other not, it would suck smoke back down into the home through the unused flue (also, less visibly, constant stream of outside air, bad for maintaining temp and comfort). Since one of the fireplaces was never ever used, I sealed it by capping the flue with a flat concrete block and caulk. No animal or water infiltration at all, complete air seal, total cost about $5. If I decide to I can reverse it completely with a box cutter and 2 minutes.

Also fwiw I am in the early stages of a build myself and I have been presented witht he same open hearth issue as you. I have chosen to remove the brickwork and hearth, seal the opening and frame over it.


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## jcr159

if the flue for the fireplace isn't connected to any other fireplaces, you're ok... if there is another fireplace upstairs connected to the same chimney/flue, i wouldn't bother with anything other than DD+GG...


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## ambesolman

jcr159 said:


> if the flue for the fireplace isn't connected to any other fireplaces, you're ok... if there is another fireplace upstairs connected to the same chimney/flue, i wouldn't bother with anything other than DD+GG...


It is. Two pipes, one chimney. Looks like I’ll be busting up that hearth  


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## Technology3456

I'm converting a multi-purpose room to a HT, with no ability to go inside the walls. I am worried soundproofing is pretty bad and I wont be able to listen to my HT close to "Reference" levels, especially the bass, without disturbing the neighbors. So I asked what I can do to soundproof the room without putting stuff in the walls, and so far the answers I got all said there is nothing I can do that will have much effect except going "in-wall.

However, I did come across an old comment from someone who said he used a sound barrier membrane between two layers of 1/2 inch panels that were wrapped with SoundSwede fabric, covering all four walls. He made no mention of anything in-wall, just this solution on the wall and it apparently made a big difference. Does anyone have any knowledge about this or any similar "on-wall" solution to the problem? Thank you.


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## gullfo

the challenge is that sound is 3D. so you need to isolate from all directions. the weakest isolation is going to negate a significant portion of the cost and effort. so a couple of things can be done - adding decoupled mass to your walls and ceiling - one option is a layer of Homasote 440 (or equiv fibrous board) and 2x 16mm type-x drywall. or isolation clips and hat channel (this will result in an additional ~50mm or so of space reduction in the room per surface. fill with roxul or other mineral wool, and 2x 16mm type-x drywall. this latter will likely give you more isolation that the soundboard layer approach. adding Green Glue (or equiv viscoelastic damper compound).
besides the walls and ceiling - windows, pipes, ducts, flues, and of course the floor and all related structure can carry sound to your neighbors - windows - sound can exit and wrap around into the neighbors - so adding a heavy "storm window" type secondary window can help. shared ducts and pipes can bridge the structure even when the main structure are separated - not much you can do there without re-working things. and the floor - one option is to get your speakers and subwoofer off the floor with isolation mounts or platforms to reduce direct transfers (air to structure will still occur, and for subwoofers this is still about 80% of the energy making it to the floor). but, that is still a reduction in level.
the next level is where you're discussing sound level attenuation - placing sufficient absorption around the room to reduce the levels which are hitting the boundary surfaces. and here again the floor will be the weak point in structure transfer.
so - some considerations: 1) test. verify how much sound is actually making its way out of your space and into the neighbors - this is best accomplished by asking your neighbors to participate - then running some sound sweeps and music etc at reference levels and using a sound meter to assess levels in the other spaces. having a mechanics stethoscope or contact sound level meter will let you check structure transfer. 2) turn down the volume after applying the absorption so you don't disturb your neighbors...


----------



## Technology3456

gullfo said:


> the challenge is that sound is 3D. so you need to isolate from all directions. the weakest isolation is going to negate a significant portion of the cost and effort. so a couple of things can be done - adding decoupled mass to your walls and ceiling - one option is a layer of Homasote 440 (or equiv fibrous board) and 2x 16mm type-x drywall. or isolation clips and hat channel (this will result in an additional ~50mm or so of space reduction in the room per surface. fill with roxul or other mineral wool, and 2x 16mm type-x drywall. this latter will likely give you more isolation that the soundboard layer approach. adding Green Glue (or equiv viscoelastic damper compound).
> besides the walls and ceiling - windows, pipes, ducts, flues, and of course the floor and all related structure can carry sound to your neighbors - windows - sound can exit and wrap around into the neighbors - so adding a heavy "storm window" type secondary window can help. shared ducts and pipes can bridge the structure even when the main structure are separated - not much you can do there without re-working things. and the floor - one option is to get your speakers and subwoofer off the floor with isolation mounts or platforms to reduce direct transfers (air to structure will still occur, and for subwoofers this is still about 80% of the energy making it to the floor). but, that is still a reduction in level.
> the next level is where you're discussing sound level attenuation - placing sufficient absorption around the room to reduce the levels which are hitting the boundary surfaces. and here again the floor will be the weak point in structure transfer.
> so - some considerations: 1) test. verify how much sound is actually making its way out of your space and into the neighbors - this is best accomplished by asking your neighbors to participate - then running some sound sweeps and music etc at reference levels and using a sound meter to assess levels in the other spaces. having a mechanics stethoscope or contact sound level meter will let you check structure transfer. 2) turn down the volume after applying the absorption so you don't disturb your neighbors...


The guy who did this:



> he used a sound barrier membrane between two layers of 1/2 inch panels that were wrapped with SoundSwede fabric, covering all four walls. He made no mention of anything in-wall, just this solution on the wall and it apparently made a big difference.


What do you think it means by "panels"? Just 1/2 thick foam sound absorption panels you buy off amazon, or it means wood? I am trying to avoid construction, but just want to hang stuff on the wall, or maybe use double-sided tape on the corners of each panel. Maybe some thin foam type of material I can buy in really big panels, then use doublesided tape to wrap soundswede fabric around them, then more doublesided tape, or "fabric fastener" (never used this before), to attach them to the walls. 

Something simple to put on, and simple to take off, with minimal holes on the walls or paint pulled off. Cheap, simple, etc. I dont need 100% results, just decent results. Whatever this guy did with just thin panels on the walls and ceilings, wrapped in a fabric, that would be great for me _if _it really works well at all. 

And for the floor above the ceilings, any type of carpetting that would make a big difference? Absorb the sound on that end instead of just from this end?


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## gullfo

unfortunately, there is little to be done without mass/spring/damping + absorption. a carpet will likely make your highs and upper mids disappear but not much for isolation. thin absorption on the walls and ceiling - same. i've seen some work using various foams and drywall and construction adhesives, but that doesn't address to desire to minimize damage to existing surfaces. maybe try isolation components on the speakers to decouple from direct transfers and reduce overall room sound levels (say 78db instead of 85db) along with deeper absorbers on walls and ceiling (say 4" thick and on ceiling hung down 4" from ceiling) to try and attenuate the overall room levels.


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## Technology3456

gullfo said:


> unfortunately, there is little to be done without mass/spring/damping + absorption. a carpet will likely make your highs and upper mids disappear but not much for isolation. thin absorption on the walls and ceiling - same. i've seen some work using various foams and drywall and construction adhesives, but that doesn't address to desire to minimize damage to existing surfaces. maybe try isolation components on the speakers to decouple from direct transfers and reduce overall room sound levels (say 78db instead of 85db) along with deeper absorbers on walls and ceiling (say 4" thick and on ceiling hung down 4" from ceiling) to try and attenuate the overall room levels.


Do you recommend against acoustic panels in general, even for making the sound better _inside _the room? Or am I misunderstanding what you're talking about when you say it will make the highs and upper mids disappear? If I cant keep sound from going outside the room, I at least want to make it sound better inside the room. I thought acoustic panels on the walls, mixed with diffusers every so often, was the way to do this? And carpet?

I must also confess, I don't know where to put bass traps, where to put acoustic panels, where to put diffusers, etc. I havent gotten to this yet but it's coming up in the future so I want to pin it down.


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## da1duc

Interesting potential new product:









Ingenious Drywall Screw Cuts Noise Transmission in Half


Noise is a huge disincentive to multi-family living, but this Swedish design can help.




www.treehugger.com





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----------



## squared80

da1duc said:


> Interesting potential new product:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Ingenious Drywall Screw Cuts Noise Transmission in Half
> 
> 
> Noise is a huge disincentive to multi-family living, but this Swedish design can help.
> 
> 
> 
> 
> www.treehugger.com
> 
> 
> 
> 
> 
> Sent from my Pixel 4 using Tapatalk


Thanks for the share. Would love to see some real testing and comparisons at some point. And I wonder what the price point would be.


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## gullfo

or even if the screw can somehow retrofit poorly built housing unit by preventing flanking from the floors, pipes, ducts, window transmissions, or shared party walls  or if it will pass building code testing to assure it addresses strength, fire resistance, etc ;-) mmm one can almost smell the snake oil in the air... lol


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## ambesolman

gullfo said:


> or even if the screw can somehow retrofit poorly built housing unit by preventing flanking from the floors, pipes, ducts, window transmissions, or shared party walls  or if it will pass building code testing to assure it addresses strength, fire resistance, etc ;-) mmm one can almost smell the snake oil in the air... lol


Snake oil’s a great lubricant


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## markmon1

Has anyone seen these new spring drywall screws?








New Spring-Loaded Screw Turns Drywall Into Sound-Absorbing Panels


"Sound Screws" might one day be an easy way to tune out noisy neighbors.




gizmodo.com


----------



## ambesolman

markmon1 said:


> Has anyone seen these new spring drywall screws?
> 
> 
> 
> 
> 
> 
> 
> 
> New Spring-Loaded Screw Turns Drywall Into Sound-Absorbing Panels
> 
> 
> "Sound Screws" might one day be an easy way to tune out noisy neighbors.
> 
> 
> 
> 
> gizmodo.com


Yep, three post back


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## Triggaaar

Eggmanslc said:


> Understanding the Triple Leaf Effect and air cavity depth
> 
> 
> The bottom line: For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key.
> 
> 
> 
> www.soundproofingcompany.com


I've not seen that link before, thanks for posting.

If I've understood correctly, then it's saying that having 3 leaves isn't actually a problem, it's only having small air cavities that are the issue.


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## Snoochers

I'm looking to make some diffusers. I have about 28" of depth so I can make them pretty big. I could conceivably make a giant semi-cylinder or a half hexagon or something. Would something like this need to be filled with insulation to prevent resonating frequencies, or can I leave it empty assuming it is dense enough to have most sound reflect off?


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## mhutchins

You'll need something in there to prevent it from behaving like an organ pipe. I would place a few rigid semicircle dividers and fill the cavities with fiberglass or rockwool.

Mike


----------



## Snoochers

Is there any data on insulation thickness and frequency absorption below 100hz? I've seen a bit of data but not much. I can get my hands on cheap insulation and could go up to 28" in depth but I don't know at what point that becomes a useless effort. I see here http://downloads.bbc.co.uk/rd/pubs/reports/1992-10.pdf that 10" of mineral wool does really really low in frequency, but haven't had much luck finding data otherwise.


----------



## squared80

Snoochers said:


> Is there any data on insulation thickness and frequency absorption below 100hz? I've seen a bit of data but not much. I can get my hands on cheap insulation and could go up to 28" in depth but I don't know at what point that becomes a useless effort. I see here http://downloads.bbc.co.uk/rd/pubs/reports/1992-10.pdf that 10" of mineral wool does really really low in frequency, but haven't had much luck finding data otherwise.


Like this?





http://www.bobgolds.com/AbsorptionCoefficients.htm


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## flyers10

I'm going to be making a small HT in a 10'3"W x 14'9"L x 9'H room. Sharing the side walls is guest bathroom on left side and kitchen(stove and dishes cabinets) on the right. Room is already finished so can't install insulation in the walls.Is there any value for the cost in adding a sheet of drywall with green glue to these side walls.


----------



## Snoochers

squared80 said:


> Like this?
> 
> 
> 
> 
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm


No, sorry! This only goes down to 125hz for the most part. Exactly what I'm getting at!


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## Snoochers

flyers10 said:


> I'm going to be making a small HT in a 10'3"W x 14'9"L x 9'H room. Sharing the side walls is guest bathroom on left side and kitchen(stove and dishes cabinets) on the right. Room is already finished so can't install insulation in the walls.Is there any value for the cost in adding a sheet of drywall with green glue to these side walls.


Absolutely adding drywall would have a great effect, assuming there are no holes in the walls. If you got electrical plugs and lights and shared ventilation you're going to have issues.


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## flyers10

Snoochers said:


> Absolutely adding drywall would have a great effect, assuming there are no holes in the walls. If you got electrical plugs and lights and shared ventilation you're going to have issues.


There are existing electrical outlets and some networking jacks.


----------



## TakeAimAtSin

Has any had any success soundproofing a basement window?


----------



## galivluv

Hi,
I have a soundproofing problem in my home and I would love to get some good advice about it.
We have a guest room that's separated from the main house by a wall of the following structure: heavy gypsum board (one layer on each side), and a steel frame with poorly installed mineral wool.
We can hear normal speech and sounds through the wall very clearly.
One option we considered is applying 5mm cork sheet to the drywall on the main-house side of the wall, as we read good things about cork's performance. However we are still not 100 percent sure and wouldn't want to spend to much money on a non-effective solution. Do you think cork applied like that can block the sound or should we consider other options?
Best wishes


----------



## warwwolf7

galivluv said:


> Hi,
> I have a soundproofing problem in my home and I would love to get some good advice about it.
> We have a guest room that's separated from the main house by a wall of the following structure: heavy gypsum board (one layer on each side), and a steel frame with poorly installed mineral wool.
> We can hear normal speech and sounds through the wall very clearly.
> One option we considered is applying 5mm cork sheet to the drywall on the main-house side of the wall, as we read good things about cork's performance. However we are still not 100 percent sure and wouldn't want to spend to much money on a non-effective solution. Do you think cork applied like that can block the sound or should we consider other options?
> Best wishes


I think cork has 0 value soundproofing wise. If its the same stuff that was Installed in my basement on some of the wall. Cork had dried up. Was full of hole. It had been installed as a "decorative" element.

Edit
{
However it might have an effect on the acoustic of the room, but I know nothing about acoustic 
} 

Out of curiosity, did you read the first 5 or 10 pages of this thread?


----------



## jerrolds

I cant figure out how to search this thread :/

Question: Would anyone mind pointing me to how other ppl have solved the problem of lighting in a decoupled/DD+GG ceiling? Backer boxes? Surface mount? Led Strips thats connected to a light switch?

Thanks!


----------



## warwwolf7

jerrolds said:


> I cant figure out how to search this thread :/
> 
> Question: Would anyone mind pointing me to how other ppl have solved the problem of lighting in a decoupled/DD+GG ceiling? Backer boxes? Surface mount? Led Strips thats connected to a light switch?
> 
> Thanks!


HI,
I got you.

Here are 4 posts answering your questions I believe. I'm not copying or quoting them because I can't multi quote on my phone. I hope this helps

Soundproofing master thread - specific post#1

Soundproofing master thread - specific post #2

Soundproofing master thread - specific post #3

Symington Theater

@granroth maybe this info could be added in the first post. What do you think? By searching in this thread I realized that this subject came on the table a lot.


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## HzDownLow

Post moved


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## squared80

Why not just get 5 gallon pails? Cheaper than that many tubes.


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## AllexxisF1

Good morning Fellas,
I've been an avid fan of these forums for over a decade, and finally, we bought our home with a dedicated space for a proper home theater. I'm heading into the planning phase, and I'm trying to figure out a sound management plan that fits. On one end of the spectrum is a full soundproof build, the other is the middle way that might get the decibels to where I want without the need for the former.

My question is in regards to the new partition wall that will be separating the home theater and the kid's living room. *If I leave the current construction as is within the home theater room, is it worth putting a sizeable effort into that partition wall to help reduce the decibels?

So is it worth a 2x6 wall, with HushFrame connectors, insulation, 2x layers of 5/8th drywall, green glue, and a solid door, if the ceiling and other walls in the theater are standard construction? Will this reduce the sound in the rest of the house by a small margin?

Any help is well appreciated. Wow, I can't believe this is actually happening, a thirty-year dream.

Room:
18x18.5
Ceiling 7' 9"
2x4 (24" spacing) construction outer two walls (underground).
"Screen Wall" 2x4 will be baffle and speakers behind the screen.


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## mhutchins

I think it would be worthwhile. Remember, the wall will work both ways, so when the kids are playing, it will help keep their noise out of the theater room.


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## AllexxisF1

Thanks M. after spending a week thinking it over, I'm going to go all-in and soundproof the theater.


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## squared80

I plan on making some simple boxes, 3/4" MDF, layer of GG, layer of cement board, treat seams with acoustical, then throw some pillow filling in there. But some questions, because I have all kinds of gas and water lines I'm trying to work around, so I can't just built any size box I want and install it.

Is there an equation to determine how large or small my backer boxes should be, ideally, for my 8" in-ceiling speakers? I've heard about 1.0 cu. ft. is good. In general, bigger is better?

Looking at two design options, really. One is a box that goes to the drywall. One is a box that goes to the 2x4 strapping.


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## Whiteknight55

Hi, I'm currently constructing a new theater room in my basement. Two of the walls are exterior and partially below grade. The other two are staggered stud walls in which I intend to install Safe 'n' Sound or something similar. The ceiling will get insulation and likely whisper clips and double drywall (maybe with green glue?) but I'm certainly open to suggestions. The door will be solid with an auto sealing bottom.

I've spent a good bit of time reading up on sound mitigation techniques here and on other sites, but I'm not totally clear on what my best bang for the buck is regarding additional steps and how the combination of various soundproofing elements adds up.

One option is to go all the way - double drywall, green glue, whisper clips/hat channel, etc on all of the walls and the ceiling. However, while I do want to do this "right", I don't have an unlimited budget. i.e. I don't want to drop another $1000 in glue or clips to only achieve an STC improvement of a couple points. Which of those techniques offer the best bang for the buck in addition to my existing staggered walls?


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## Rjloper9

squared80 said:


> I plan on making some simple boxes, 3/4" MDF, layer of GG, layer of cement board, treat seams with acoustical, then throw some pillow filling in there. But some questions, because I have all kinds of gas and water lines I'm trying to work around, so I can't just built any size box I want and install it.
> 
> Is there an equation to determine how large or small my backer boxes should be, ideally, for my 8" in-ceiling speakers? I've heard about 1.0 cu. ft. is good. In general, bigger is better?
> 
> Looking at two design options, really. One is a box that goes to the drywall. One is a box that goes to the 2x4 strapping.
> 
> View attachment 3175487


Are they open or closed back speakers?


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## da1duc

squared80 said:


> I plan on making some simple boxes, 3/4" MDF, layer of GG, layer of cement board, treat seams with acoustical, then throw some pillow filling in there. But some questions, because I have all kinds of gas and water lines I'm trying to work around, so I can't just built any size box I want and install it.
> 
> Is there an equation to determine how large or small my backer boxes should be, ideally, for my 8" in-ceiling speakers? I've heard about 1.0 cu. ft. is good. In general, bigger is better?
> 
> Looking at two design options, really. One is a box that goes to the drywall. One is a box that goes to the 2x4 strapping.
> 
> View attachment 3175487


If the speaker manufacturer supplies backer boxes use that for the volume. Otherwise contact them directly, they will usually have the recommended volume. 

As for style, the ones that fit in between and sit flush to drywall is easier to seal. 

Had to work around a LOT of plumbing and wiring, good luck.

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## squared80

Rjloper9 said:


> Are they open or closed back speakers?


Open. Klipsch PRO-180RPC and Klipsch PRO-180RPC LCR.


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## Rjloper9

squared80 said:


> Open. Klipsch PRO-180RPC and Klipsch PRO-180RPC LCR.


As far as the in-ceilings go, Klipsch makes their own backer boxes. I’d probably buy from Crutchfield if you didn’t wanna make your own. 









Klipsch ME-800-C


Metal pre-construction enclosure for Klipsch Reference Series in-ceiling speakers with 8" woofers




www.crutchfield.com






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## squared80

Rjloper9 said:


> As far as the in-ceilings go, Klipsch makes their own backer boxes. I’d probably buy from Crutchfield if you didn’t wanna make your own.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Klipsch ME-800-C
> 
> 
> Metal pre-construction enclosure for Klipsch Reference Series in-ceiling speakers with 8" woofers
> 
> 
> 
> 
> www.crutchfield.com


Right, but those won't work for my LCR versions, which have what would normally be a very convenient SecureFit installation system.


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## Rjloper9

squared80 said:


> Right, but those won't work for my LCR versions, which have what would normally be a very convenient SecureFit installation system.


I’d email Klipsch and see what they recommend.

Sent you a message.


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## warwwolf7

Whiteknight55 said:


> Hi, I'm currently constructing a new theater room in my basement. Two of the walls are exterior and partially below grade. The other two are staggered stud walls in which I intend to install Safe 'n' Sound or something similar. The ceiling will get insulation and likely whisper clips and double drywall (maybe with green glue?) but I'm certainly open to suggestions. The door will be solid with an auto sealing bottom.
> 
> I've spent a good bit of time reading up on sound mitigation techniques here and on other sites, but I'm not totally clear on what my best bang for the buck is regarding additional steps and how the combination of various soundproofing elements adds up.
> 
> One option is to go all the way - double drywall, green glue, whisper clips/hat channel, etc on all of the walls and the ceiling. However, while I do want to do this "right", I don't have an unlimited budget. i.e. I don't want to drop another $1000 in glue or clips to only achieve an STC improvement of a couple points. Which of those techniques offer the best bang for the buck in addition to my existing staggered walls?


Hi,
I'm very short on time otherwise I'd give you a more complete answer.

Search for cnrc soundproofing article more specifically "IRC-IR-761". This is an paper regrouping a lot of soundproofing wall tested. They are using a very repeatable process to test and it makes their test very valid. If I remember correctly They use a process describe on page 5 to ensure Repeatability. I have a lot of trust in those papers.

That should be a good start. Comme back here with you 3 favorite choice and we could start with from there

However green glue is not part of this study, but We can assume that green glue is probably not most cost effective option if that's what you are after, I'm afraid


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## ambesolman

I’m looking for the best way to soundproof my basement ceiling while providing access to existing electrical junction boxes. 

We just completed a big electrical project of bringing the house up to code and upgraded the service to 200A which took 5 days. We had a great experience with the company and highly recommended.

I know ddgg on channels is ideal just not sure how to accomplish that. I also can’t figure out how to lower the ceiling to encompass what’s below the joists either. I kinda hate the idea of a drop ceiling…












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## Rjloper9

ambesolman said:


> I’m looking for the best way to soundproof my basement ceiling while providing access to existing electrical junction boxes.
> 
> We just completed a big electrical project of bringing the house up to code and upgraded the service to 200A which took 5 days. We had a great experience with the company and highly recommended.
> 
> I know ddgg on channels is ideal just not sure how to accomplish that. I also can’t figure out how to lower the ceiling to encompass what’s below the joists either. I kinda hate the idea of a drop ceiling…
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk


@BIGmouthinDC would probably know best, but maybe you could build something like a backer box for the junction boxes to keep your soundproof shell, etc.

Not sure if that meets code though. Big will know.


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## calincole

Looking for some quick on putty pads for electrical boxes. Is there a difference in those marketed as acoustic vs fire stop? Are there recommended brands, or sources? I see prices ranging from about $3 per to about $7 which is a big range.

For example Lowes (close and convenient to me has These marketed as just fire stop, would they be effective as acoustic stop also? Best price I have found is This but without fire stop protection. Any opinions welcome.


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## squared80

calincole said:


> Looking for some quick on putty pads for electrical boxes. Is there a difference in those marketed as acoustic vs fire stop? Are there recommended brands, or sources? I see prices ranging from about $3 per to about $7 which is a big range.


Don't overspend on these things. I found a good deal here: ATS Acoustics Putty Pads


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## AllexxisF1

That's an awesome price.


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## Whiteknight55

warwwolf7 said:


> Hi,
> I'm very short on time otherwise I'd give you a more complete answer.
> 
> Search for cnrc soundproofing article more specifically "IRC-IR-761". This is an paper regrouping a lot of soundproofing wall tested. They are using a very repeatable process to test and it makes their test very valid. If I remember correctly They use a process describe on page 5 to ensure Repeatability. I have a lot of trust in those papers.
> 
> That should be a good start. Comme back here with you 3 favorite choice and we could start with from there
> 
> However green glue is not part of this study, but We can assume that green glue is probably not most cost effective option if that's what you are after, I'm afraid


Thank you. I reviewed the article and I'm intending to use staggered stud walls for my two interior walls. They will have clips and channel, plus two layers of DW with green glue. One of the exterior foundation walls has pre-existing framing that butts up against the block, so I am intending to use clips, channel, 2xDW and GG there as well. The last exterior foundation wall is already framed with 1"+ between the studs and the wall, so my understanding is I don't need to use clips there. Is that correct? If I have sufficient extra clips and channel is there any reason not to use them? Regardless, that wall also gets 2xDW and GG.

The ceiling will get clips and channel, plus 2xDW and GG. The ceiling and two interior staggered stud walls will get Roxul, and the two exterior walls will get regular fiberglass insulation.

Am I missing anything here regarding the walls? I'm still working on the approach for my ducts.


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## warwwolf7

Whiteknight55 said:


> Thank you. I reviewed the article and I'm intending to use staggered stud walls for my two interior walls. They will have clips and channel, plus two layers of DW with green glue. One of the exterior foundation walls has pre-existing framing that butts up against the block, so I am intending to also use clips, channel, 2xDW and GG there as well. The last exterior foundation wall is already framed with 1"+ between the studs and the wall, so my understanding is I don't need to use clips there. Is that correct? If I have sufficient extra clips and channel is there any reason not to use them? Regardless, that wall also gets 2xDW and GG.
> 
> The ceiling will get clips and channel, plus 2xDW and GG. The ceiling and two interior staggered stud walls will get Roxul, and the two exterior walls will get regular fiberglass insulation.
> 
> Am I missing anything here regarding the walls? I'm still working on the approach for my ducts.


For your stud spaced 1" from the foundation. I Would believe you could skip the hat and channel if the wall is not nailed with your floor joist above and is connected with something like the ib-3. Otherwise you would need to decouple your drywall from your house structure with hat and channel

Make sure to consult your local code on how to install your vapor barrior and make sure to install one on your exterior walls

I'm curious to know why you would be using regular fiberglass on the wall but roxul in the ceiling.


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## Whiteknight55

warwwolf7 said:


> For your stud spaced 1" from the foundation. I Would believe you could skip the hat and channel if the wall is not nailed with your floor joist above and is connected with something like the ib-3. Otherwise you would need to decouple your drywall from your house structure with hat and channel
> 
> Make sure to consult your local code on how to install your vapor barrior and make sure to install one on your exterior walls
> 
> I'm curious to know why you would be using regular fiberglass on the wall but roxul in the ceiling.


My understanding is that Roxul isn’t intended for exterior foundation walls. Is that inaccurate?


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## warwwolf7

Whiteknight55 said:


> My understanding is that Roxul isn’t intended for exterior foundation walls. Is that inaccurate?


I don't know about that. I would think that roxul with proper water barrier should be fine. Your local code inspector should be able to guide you better than me though


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## Rjloper9

warwwolf7 said:


> For your stud spaced 1" from the foundation. I Would believe you could skip the hat and channel if the wall is not nailed with your floor joist above and is connected with something like the ib-3. Otherwise you would need to decouple your drywall from your house structure with hat and channel
> 
> Make sure to consult your local code on how to install your vapor barrior and make sure to install one on your exterior walls
> 
> I'm curious to know why you would be using regular fiberglass on the wall but roxul in the ceiling.


BIG advised me that I could forgo the clips and channel on the walls with a 1” air gap off the foundation walls while utilizing IB-3 clips to isolate from the floor joists.

I also used 3/4” horse stall mats from Tractor supply under my bottom plates.


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## Whiteknight55

Rjloper9 said:


> BIG advised me that I could forgo the clips and channel on the walls with a 1” air gap off the foundation walls while utilizing IB-3 clips to isolate from the floor joists.
> 
> I also used 3/4” horse stall mats from Tractor supply under my bottom plates.
> 
> 
> Sent from my iPhone using Tapatalk


Unfortunately that foundation wall framing is pre-existing and does contact the floor joists above. There’s no way I can get IB-3 clips in there so despite the 1” gap from the foundation I think I’ll just treat it like all the other walls and use clips and channels there too.


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## Rjloper9

Whiteknight55 said:


> Unfortunately that foundation wall framing is pre-existing and does contact the floor joists above. There’s no way I can get IB-3 clips in there so despite the 1” gap from the foundation I think I’ll just treat it like all the other walls and use clips and channels there too.


All may not be lost here. I’m pretty sure @luv2fly3 accidentally did this and then cut his studs an inch short and added the IB-3 clips as an afterthought. His build has a lot of great info. The Spartan Theater Build.


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## luv2fly3

Whiteknight55 said:


> Unfortunately that foundation wall framing is pre-existing and does contact the floor joists above. There’s no way I can get IB-3 clips in there so despite the 1” gap from the foundation I think I’ll just treat it like all the other walls and use clips and channels there too.





Rjloper9 said:


> All may not be lost here. I’m pretty sure @luv2fly3 accidentally did this and then cut his studs an inch short and added the IB-3 clips as an afterthought. His build has a lot of great info. The Spartan Theater Build.


I did have that exact issue. I framed my walls with an air gap against the foundation walls, but made the mistake of going all the way to the floor joists when I first started my room. By the time I realized my mistake, I had no choice but to do a little retro fitting. It wasn't bad at all, and I'm glad I was able to use IB-3 clips. 

Here's the exact post on my build thread where I shared some pics and info on that part of my build. I just used a reciprocating saw to cut the nails between the header plate and top of the studs. Then I used a circular saw to cut each stud shorter, while they were in place. With the studs shorter, I just pulled the top plate off the joists and reattached it to the top of the studs and I was done. It was well worth the effort, and again it really wasn't too bad to do. Just use a good blade if you are going to do it. With your walls detached from your joists, you just eliminate having to use clip and channel on the side walls. I didn't, just green glue and double drywall. I only used clip and channel on my ceiling areas.


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## Rjloper9

luv2fly3 said:


> I did have that exact issue. I framed my walls with an air gap against the foundation walls, but made the mistake of going all the way to the floor joists when I first started my room. By the time I realized my mistake, I had no choice but to do a little retro fitting. It wasn't bad at all, and I'm glad I was able to use IB-3 clips.
> 
> Here's the exact post on my build thread where I shared some pics and info on that part of my build. I just used a reciprocating saw to cut the nails between the header plate and top of the studs. Then I used a circular saw to cut each stud shorter, while they were in place. With the studs shorter, I just pulled the top plate off the joists and reattached it to the top of the studs and I was done. It was well worth the effort, and again it really wasn't too bad to do. Just use a good blade if you are going to do it. With your walls detached from your joists, you just eliminate having to use clip and channel on the side walls. I didn't, just green glue and double drywall. I only used clip and channel on my ceiling areas.


Not to mention, the clips are very expensive (IMHO) and the hat channel is $13.32 per 10’ piece in my area at HD. The manual labor of fixing the existing wall has to outweigh the cost of needing to use clips and channel on the walls too.


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## jerrolds

Im planning on extending the 2 heat/AC 5" ducts with flexible ducting to try and absorb some of that sound - something like this https://www.homedepot.ca/product/du...insulated-ducting-5-inch-x-25-foot/1000107496

sould snaking it the full 25ft be best or can i do something like 12.5 for both - i also dont want to kill air flow

Mimicing something like this: https://www.soundproofingcompany.com/wp-content/uploads/2018/12/dead-vent-diagram-profile.jpg altho i dont want to install a fan, cuz if it ever broke id be screwed

Thanks


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## Javs

Need some thoughts.

I am planning to do clip and channel, double drywall + GG for my cinema room in the new house I am building, but the screen wall on the outside of the house has huge windows (front facade so need them there due to street code), of which I will need to make huge window plugs or drywall over the top of, or both. but also there are numerous weep holes in the brick which are supposed to let mousture out... Am I fighting a losing battle here? With all the effort I am going through in the room it makes me think these weep holes are going to negate the benefits of the brick wall's mass. 

Any thoughts? Tell me its all going to be ok lol. 

These windows are going to need some of the best window plugs seen on this website I know that much. The amount of firepower thats going to be sitting right on the other side of it is quite a lot. Most of the effort is to minimise as much as possible noise travel to my neighbours rather than keeping noise out of the room, thats an added benefit.


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## Apgood

Javs said:


> Need some thoughts.
> 
> I am planning to do clip and channel, double drywall + GG for my cinema room in the new house I am building, but the screen wall on the outside of the house has huge windows (front facade so need them there due to street code), of which I will need to make huge window plugs or drywall over the top of, or both. but also there are numerous weep holes in the brick which are supposed to let mousture out... Am I fighting a losing battle here? With all the effort I am going through in the room it makes me think these weep holes are going to negate the benefits of the brick wall's mass.
> 
> Any thoughts? Tell me its all going to be ok lol.
> 
> These windows are going to need some of the best window plugs seen on this website I know that much. The amount of firepower thats going to be sitting right on the other side of it is quite a lot. Most of the effort is to minimise as much as possible noise travel to my neighbours rather than keeping noise out of the room, thats an added benefit.


The number of weep holes in that wall seems overkill. Builder worried about water getting into the brickwork / cavity because of the widow opening in the wall?

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## Javs

Apgood said:


> The number of weep holes in that wall seems overkill. Builder worried about water getting into the brickwork / cavity because of the widow opening in the wall?


I agree its overkill and its quite annoying, at the very least I think I will fill in the ones immediately under the window as its totally protected by the balcony anyway and I do believe they are not required as per the building standards. Also Ive seen a few examples of this exact house design and nobody has high up weep holes like I do. Something to bring up with my building inspector to put in his report.


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## Apgood

Javs said:


> I agree its overkill and its quite annoying, at the very least I think I will fill in the ones immediately under the window as its totally protected by the balcony anyway and I do believe they are not required as per the building standards. Also Ive seen a few examples of this exact house design and nobody has high up weep holes like I do. Something to bring up with my building inspector to put in his report.


It shouldn't have much if any impact from a sound getting out, based on my experience with same sort of thing on a cavity brick house.

What I would do is just use some sika flex from bunnings to fill in the excess weep holes. 

You can always monitor the moisture levels in the cavity and/or room and remove the sika if necessary or get a dehumidifier for the room / let the air con run in dry mode if you find the room to humid. Personally I would think if there's a humidity / damp issue in the room them there are more fundamental issues with the construction and its dampproofing.

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## Javs

Apgood said:


> It shouldn't have much if any impact from a sound getting out, based on my experience with same sort of thing on a cavity brick house.
> 
> What I would do is just use some sika flex from bunnings to fill in the excess weep holes.
> 
> You can always monitor the moisture levels in the cavity and/or room and remove the sika if necessary or get a dehumidifier for the room / let the air con run in dry mode if you find the room to humid. Personally I would think if there's a humidity / damp issue in the room them there are more fundamental issues with the construction and its dampproofing.
> 
> Sent from my SM-N986B using Tapatalk


The house is still being built though, so I can tell them to fill in the ones that are not required so that's good, I would prefer it to be fully rendered over cleanly.

I will put weep hole guards in the lower ones which are little metal grates with tiny holes, that will help more too. The house has a wall wrap moisture barrier, and the lower weep holes will do their job if needed, of course I wouldn't expect zero, I just think 11 on one wall is getting out of control.

I do worry about when I seal that window in maybe there will be a humidity issue in the sealed window space. But Ill cross that bridge when I get to it.


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## Apgood

Javs said:


> The house is still being built though, so I can tell them to fill in the ones that are not required so that's good, I would prefer it to be fully rendered over cleanly.
> 
> I will put weep hole guards in the lower ones which are little metal grates with tiny holes, that will help more too. The house has a wall wrap moisture barrier, and the lower weep holes will do their job if needed, of course I wouldn't expect zero, I just think 11 on one wall is getting out of control.
> 
> I do worry about when I seal that window in maybe there will be a humidity issue in the sealed window space. But Ill cross that bridge when I get to it.


If it's a sliding window you can probably remove the clip latch so you can open it from the outside from time to time for cleaning and ventilation.
Since you will have it sealed it isn't like it will be a security risk.

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## mhutchins

I have seen suggestions on the forums that sealing windows with plugs or permanent construction requires small vents at the top and bottom to allow air circulation for both humidity and temperature control. The vents are placed on or near the top and bottom sill plates and are vented to the inside of the house so conditioned air circulates through the space behind (indoor side) the window. With the vents at the top and bottom, convection currents should facilitate air circulation in the space behind the window.

The real questions in my mind regarding these vents are:

How small can they be and still be effective?
How large can they be without compromising the noise reduction rating of the wall?
How many are needed to be effective?
Is there a formula or ratio based on window surface area or enclosed volume between the window and plug for determining vent size?
Are there construction methods for these vents that optimize airflow while minimizing noise transmission (I'm thinking something along the lines of a miniature dead vent)?
Mike


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## warwwolf7

mhutchins said:


> I have seen suggestions on the forums that sealing windows with plugs or permanent construction requires small vents at the top and bottom to allow air circulation for both humidity and temperature control. The vents are placed on or near the top and bottom sill plates and are vented to the inside of the house so conditioned air circulates through the space behind (indoor side) the window. With the vents at the top and bottom, convection currents should facilitate air circulation in the space behind the window.
> 
> The real questions in my mind regarding these vents are:
> 
> How small can they be and still be effective?
> How large can they be without compromising the noise reduction rating of the wall?
> How many are needed to be effective?
> Is there a formula or ratio based on window surface area or enclosed volume between the window and plug for determining vent size?
> Are there construction methods for these vents that optimize airflow while minimizing noise transmission (I'm thinking something along the lines of a miniature dead vent)?
> Mike


I'm not expert, but it seems completely counter intuitive to have small holes to let the window breath.
There are 3 area
Outside, in wall, inside(conditionned space) 

On cold days, If the conditioned air of inside touches a surface that is between outside and Inside it needs some form of insulation on one side or the other to prevent condensation. Insulation is not enough, it needs to be airtight otherwise the inside air will "leak" through the insulation and warm the air in the insulation. When the temperature difference between outside and inside is to big, a slight leak in your insulation will warm the air in the insulation( or leak to the cold surface) enough to create condensation inside the wall on the cold side of the insulation. You do not want to create any air movement in your wall. If you feel your walls are too humid, maybe your window isn't sealed properly. Same thing applies to basement wall, if they are made of concrete, they could transmit water through, sprayed foam would be ideal to prevent water to get into the fiberbatt insulation. So your window will have to be watertight. 

If you want air on your surface go all in or not at all. By all in I mean not covered at all, no insulation with plenty of air movement 

I'm not an expert. But it's cold here, and it doesn't take much to have condensation. There is a reason why exterior wall that are covered with drywall are required per code(code being the lowest level of quality you need to achieve, its far for the best practices in the construction world. So if it's in there, make sure you follow it) to have vapor barrior.

I'm not an expert and I could be wrong. Verify with an expert


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## calincole

Hi, I am hoping to get some opinions or suggestions regarding an HVAC issue. I am working on converting a basement room, ill be doing DD+GG etc. The ceiling of this room contains several runs of duct that service both this area, and more importantly, some of the living space above it. Because it services that space, it is not feasible to completely remove all the ducts from the ceiling so I have to deal with it somehow. 

Right now, as you can see in this pic here, the existing system uses 6" round metal duct. The joists are only 7 1/4 so with those in in place there is very little room for insulation. So, whats my play to handle this best as I can? 

I have considered converting it to a stack duct that is around a 3" tall rectangle, this then gives me space to at least add rockwool to the joist bay. Another option that is much much simpler is to leave the register boot in place but replace the length of the run with flex duct. My only concern there is reducing the effectiveness of the duct, although I think that just doing quality work should alleviate that.

I am open to other suggestions that I may not have considered as well of course. Thanks.


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## squared80

calincole said:


> Hi, I am hoping to get some opinions or suggestions regarding an HVAC issue. I am working on converting a basement room, ill be doing DD+GG etc. The ceiling of this room contains several runs of duct that service both this area, and more importantly, some of the living space above it. Because it services that space, it is not feasible to completely remove all the ducts from the ceiling so I have to deal with it somehow.
> 
> Right now, as you can see in this pic here, the existing system uses 6" round metal duct. The joists are only 7 1/4 so with those in in place there is very little room for insulation. So, whats my play to handle this best as I can?
> 
> I have considered converting it to a stack duct that is around a 3" tall rectangle, this then gives me space to at least add rockwool to the joist bay. Another option that is much much simpler is to leave the register boot in place but replace the length of the run with flex duct. My only concern there is reducing the effectiveness of the duct, although I think that just doing quality work should alleviate that.
> 
> I am open to other suggestions that I may not have considered as well of course. Thanks.


Not a lot you can do, other than taking down the metal tubes, and replacing them with flexduct, then trying to isolate/insulate them as best you can. Flexduct install was very easy - did it myself. You could run soffits around the tops of your room, if size permits, and run flexduct through there, too.


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## warwwolf7

calincole said:


> Hi, I am hoping to get some opinions or suggestions regarding an HVAC issue. I am working on converting a basement room, ill be doing DD+GG etc. The ceiling of this room contains several runs of duct that service both this area, and more importantly, some of the living space above it. Because it services that space, it is not feasible to completely remove all the ducts from the ceiling so I have to deal with it somehow.
> 
> Right now, as you can see in this pic here, the existing system uses 6" round metal duct. The joists are only 7 1/4 so with those in in place there is very little room for insulation. So, whats my play to handle this best as I can?
> 
> I have considered converting it to a stack duct that is around a 3" tall rectangle, this then gives me space to at least add rockwool to the joist bay. Another option that is much much simpler is to leave the register boot in place but replace the length of the run with flex duct. My only concern there is reducing the effectiveness of the duct, although I think that just doing quality work should alleviate that.
> 
> I am open to other suggestions that I may not have considered as well of course. Thanks.


I was told by @BIGmouthinDC that flex duct in a concealed and unaccessible area might not be up to code in certain area. Make sure to validate that before going forward with flex duct


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## mhutchins

calincole said:


> Hi, I am hoping to get some opinions or suggestions regarding an HVAC issue. I am working on converting a basement room, ill be doing DD+GG etc. The ceiling of this room contains several runs of duct that service both this area, and more importantly, some of the living space above it. Because it services that space, it is not feasible to completely remove all the ducts from the ceiling so I have to deal with it somehow.
> 
> Right now, as you can see in this pic here, the existing system uses 6" round metal duct. The joists are only 7 1/4 so with those in in place there is very little room for insulation. So, whats my play to handle this best as I can?
> 
> I have considered converting it to a stack duct that is around a 3" tall rectangle, this then gives me space to at least add rockwool to the joist bay. Another option that is much much simpler is to leave the register boot in place but replace the length of the run with flex duct. My only concern there is reducing the effectiveness of the duct, although I think that just doing quality work should alleviate that.
> 
> I am open to other suggestions that I may not have considered as well of course. Thanks.


I think the rectangular duct option has the greatest potential for improving sound isolation. I would increase the duct cross sectional area 10-20% to offset the decreased flow efficiency of the rectangular duct vs the round duct (see table below). I would add an extra two layers of drywall (+/- Green Glue or similar) inside the cavity to seal the duct completely then I would use an insulation batt in the cavity below the duct. The extra layers of drywall will help eliminate break-in noise from entering the ductwork from the theater and transmitting noise into the rest of the house. Although this joist bay creates a triple-leaf, I suspect the small area relative to the rest of the ceiling makes the effect inconsequential to the overall sound isolation of the ceiling. 

If you use the bay itself as the duct, be sure to paint the wood and drywall paper exposed to the airflow with a mold/mildew resistant paint such as Zinsser Perma-White Mold & Mildew-Proof Exterior Paint.

Mike


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## calincole

mhutchins said:


> I think the rectangular duct option has the greatest potential for improving sound isolation. I would increase the duct cross sectional area 10-20% to offset the decreased flow efficiency of the rectangular duct vs the round duct (see table below). I would add an extra two layers of drywall (+/- Green Glue or similar) inside the cavity to seal the duct completely then I would use an insulation batt in the cavity below the duct. The extra layers of drywall will help eliminate break-in noise from entering the ductwork from the theater and transmitting noise into the rest of the house. Although this joist bay creates a triple-leaf, I suspect the small area relative to the rest of the ceiling makes the effect inconsequential to the overall sound isolation of the ceiling.
> 
> If you use the bay itself as the duct, be sure to paint the wood and drywall paper exposed to the airflow with a mold/mildew resistant paint such as Zinsser Perma-White Mold & Mildew-Proof Exterior Paint.
> 
> Mike
> View attachment 3190829


Mike, Thanks for the detailed response, I appreciate it very much. This type of thing seems like the more effective solution, albeit much more work than the flex duct. My biggest obstacle is sourcing the parts to get the connection right with the existing trunk and registers. Thanks again for your input.


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## Chuck Miller

I posted this in my build thread, but thought I would ask here as well...

I'm designing the stage and rear riser for the theater and it has raised a few questions I hope you can help to answer. I see in other build threads, many supported by BIG, the stage is installed, then filled with sand before covering with plywood. For risers, it appears the common practice is to install it, then stuff with insulation before covering. So a couple of questions:

Should both stage and riser be built on 16" centers? It's hard to tell from the pictures I've seen. Or, considering the price of lumber, would 24" suffice? There will be no real heavy loads on the stage with three Klipsch LaScalas and two Tuba HT subwoofers. They are large and heavy, but not excessively so that would overstress 24" on center construction, I don't believe..
What's the purpose of the sand in the stage? Is it to dampen sounds, primarily I assume from subwoofers that are typically placed there?
And the purpose of the insulation in the riser is to similarly dampen sounds, kind of like a bass trap?
If I am on the right track with the above two questions, should I plan to fill the riser with sand also, since there will be two subwoofers installed there?
Again, considering the price of lumber, is there any reason not to use OSB instead of plywood for the covers of the stage and riser?
Thanks for your shared knowledge and experience!

Chuck


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## mhutchins

The weaker the structure, the stronger the sheathing needs to be. If you go with 24" spacing, you may need to use thicker panels over the structure.
Yes, sand is an excellent sound damper in these structures. Acoustic testing showed little-to-no difference between sand and insulation, however, I believe pounding on the deck with an object will produce a difference that is easily distinguished between sand vs insulation.
Yes.
Yes and no - you may like the added tactile response through the decking which the sand would more effectively limit. Alternatively, you can isolate the subs where they interface with the decking to isolate any vibration from the sub from energizing the decking. Isolation pads, felt, fiberglass, mineral wool, memory foam will all work to some degree to provide isolation from the riser.
None whatsoever. Even before lumber prices skyrocketed, builders were using OSB for riser and stage decking.
Mike


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## Chuck Miller

Thanks Mike. I've purchased lumber based on 16" centers. And was planning on using insulation in both stage and riser, but you have me reconsidering sand for the stage. 

Is 30# the correct roofing felt to build the stage and riser on? I will use green glue between the decking.


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## Rjloper9

Chuck Miller said:


> Thanks Mike. I've purchased lumber based on 16" centers. And was planning on using insulation in both stage and riser, but you have me reconsidering sand for the stage.
> 
> Is 30# the correct roofing felt to build the stage and riser on? I will use green glue between the decking.


30 is what I’ll be using


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## liebes29

Hello!

I'm looking for what, if any, additional soundproofing I need to do.

I'm finishing my basement and I'm planning (eventually) to put a better sound system in my basement rec room. This is where I will watch movies (which I like to watch loud) because my wife gets real triggered by sound when either A. the kids are sleeping, or B. she is sleeping. Fortunately, all the bedrooms are on the 2nd floor of the house. Right now I only intending on putting normal R-12 fiberglass insulation and 1/2 drywall on the ceiling of my basement. The main floor has 8ft high ceilings, and theres a 2ft thick floor in between the main and 2nd floors with engineered trusses. Because of the distance between the basement and the 2nd floor bedrooms, will just fiberglass and drywall be enough? I'm not at all worried about people on the main floor hearing any of the sound.

I've attached a picture of the planned basement design. The picture is only about 2/3rds of the basement, as the other 1/3rd is remaining an unfinished utility room. The "tv area" is the bottom left portion as is approximately 12x12. I'm also not worried about the guest bedroom next to the tv room in the picture, as I won't be watching movies loud after guests go to bed.

Thanks!
Alex


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## warwwolf7

@liebes29

HI.

Do you have a door to enclose your basement from the 1rst floor? This door should be solid core and with door threshold ideally. Same for the guest room downstairs or they will become the weak link. That is assuming that the bedroom doors of the room on the 2nd floor are standard door with gaps all around. Those doors will attenuate the sound outside of their room but not by much.
The additionnal floor in between the rooms and your rec room will help. No Doubt.
However it's hard to even guess by how much because we would also need the floor plan to see where the mid and high frequency will need to go through before reaching the rooms. Mid and high frequency will likely bounce on the wall in order to get to the room above. For the mid bass and bass. That's another story. I you have a lot of bass, the 1/2 drywall will do very little to reduce the transmission of bass. Have you ever heard in your basement a car with too much subwoofer, playing Loudly while it passed in front of your house? And we are talking 2 different structures, one of them isolated from the group and it still manages to go through a lot. If your expectations are low regarding mid bass and bass, then maybe it will be enough or maybe you will have to lower the bass when the kids are asleep. (my kid is well used to us listening to TV, so it does not affect its sleep at all. We made sure to not lower the volume when watching TV, to make sure et gets use to it from the get go.) 


Remember that insulation between your joist is the least effective item in the list for soundproofing. It's an essential part of an good soundproofed room, don't get me wrong but not the most effective by itself alone. If the budget is an issue. Then at least try to install 5/8 drywall typeX, Not the lightweight 1/2" for the ceiling. Mass is important when you are trying to stop low frequency. Mass, decoupling, damping. Look here if you haven't already seen that. https://www.soundproofingcompany.com/soundproofing_101/4-elements-of-soundproofing

Remember that your house is a solid structure that will transmit low frequency to all its framing. Transmission of vibration will be reduced each time it change from a piece to another one.

Can you make a test with the basement door closed at the volume you want to listen and evaluate the current sound level in the bedrooms on the 2nd story? . Make sure to choose a chapter of a movie with a lot of action. What do you hear? High frequency? Mid frequency? Deep bass? Do you feel the deep rumble? Maybe it ain't to bad. That information is critical for the planning phase 

We just can't assume with the amount of the details you have provided. Finally, everyone expectation and definition of loud or quiet enough is very subjective.


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## Chuck Miller

mhutchins said:


> The weaker the structure, the stronger the sheathing needs to be. If you go with 24" spacing, you may need to use thicker panels over the structure.
> Yes, sand is an excellent sound damper in these structures. Acoustic testing showed little-to-no difference between sand and insulation, however, I believe pounding on the deck with an object will produce a difference that is easily distinguished between sand vs insulation.
> Yes.
> Yes and no - you may like the added tactile response through the decking which the sand would more effectively limit. Alternatively, you can isolate the subs where they interface with the decking to isolate any vibration from the sub from energizing the decking. Isolation pads, felt, fiberglass, mineral wool, memory foam will all work to some degree to provide isolation from the riser.
> None whatsoever. Even before lumber prices skyrocketed, builders were using OSB for riser and stage decking.
> Mike


Is there a thread that discusses the pros and cons of insulation vs. sand in the stage? In my case, I'll be using the SVS Subwoofer Isolation Feet on all my subs. I doubt they will have any impact if installed with sand in the stage, but might with 10" of insulation instead. I've read that some have used insulation instead of sand, so I'm curious if the tradeoff would be substantial.

The reason I ask is the stage is pretty large with a cavity volume of about 80 cubic feet. That's 160 bags of sand/4,000 lbs./$550. If I use sand in the riser, another 150 bags required.

I'd rather spend that money elsewhere. And the insulation would be a lot easier to install. But....I don't want to cut any major corners, hence my desire to understand potential tradeoffs.

Note that two subwoofers and the equipment rack will be sitting on the riser.

Thanks,

Chuck


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## mhutchins

Chuck Miller said:


> Is there a thread that discusses the pros and cons of insulation vs. sand in the stage?
> .
> .
> Thanks,
> 
> Chuck


I'm not aware of any where there is a significant discussion. Another question you need to consider is whether you want to spend $1350 on sand and haul 310 bags = *7-3/4* *TONS* of sand from your driveway to its final destination in the theater?

One other comment with regards to sand vs. insulation in your stage and riser - The purpose is to reduce resonance of these structures _*inside*_ the theater. The impact on noise transfer into the rest of the house will be minimal at best. So, if you are considering sand as a soundproofing measure for the rest of the house, save your money - and your back!

Mike


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## Chuck Miller

Thanks for your comments Mike. I realize that stage and riser construction isn't really a soundproofing question, but I've been trying to find some experience with those using insulation, as I'm told sand in the stage is "best practice". Then I read with interest how some/many design their risers as bass traps, using vents on top at the wall boundaries to reduce reflections. Now, my riser setup is very similar to the stage, using an acoustically transparent screen. Both will have two subwoofers directly sitting on them. The stage will also have LCR speakers on it. The riser will have two rear surround speakers installed above it and the equipment rack will be sitting on it as well. And, of course, some seating. What I don't understand is why these to components would be treated differently. I could argue that the stage should be designed like the riser because using it as a bass trap would be expected to provide the same impact to standing waves as the riser would. And, conversely, if sand is best practice for the stage, why not the riser? I'm not interested in schlepping more sand by any means and am truly not sure the value for the stage is worth the effort.

I take it from your comments that you are not in the camp of recommending a sand filled stage. If you have a stage in your theater, how was it designed and how to you like the result?

Thanks,

Chuck


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## Newbie789

jerrolds said:


> Im planning on extending the 2 heat/AC 5" ducts with flexible ducting to try and absorb some of that sound - something like this https://www.homedepot.ca/product/du...insulated-ducting-5-inch-x-25-foot/1000107496
> 
> sould snaking it the full 25ft be best or can i do something like 12.5 for both - i also dont want to kill air flow
> 
> Mimicing something like this: https://www.soundproofingcompany.com/wp-content/uploads/2018/12/dead-vent-diagram-profile.jpg altho i dont want to install a fan, cuz if it ever broke id be screwed
> 
> Thanks


Typical rule of thumb is 3 turns for a flex duct and it will stop the sound. Running the full 25ft would be a question for the ac guy, because the longer the run the more resistance...reducing the amount of cold/hot air out of the vent.


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## jerrolds

Newbie789 said:


> Typical rule of thumb is 3 turns for a flex duct and it will stop the sound. Running the full 25ft would be a question for the ac guy, because the longer the run the more resistance...reducing the amount of cold/hot air out of the vent.



Thanks maybe ill do 4 turns and chop it - dont want the theater to be unbearable - thanks for the tip


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## Newbie789

jerrolds said:


> Thanks maybe ill do 4 turns and chop it - dont want the theater to be unbearable - thanks for the tip


To be safe I'd Confirm with hvac guy that 4 turns won't be an issue with airflow. Don't know enough to weigh in on that.


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## randman

I'm putting in a home theater in an unfinished part of my basement. Right above the home theater is a bedroom. So, the plan is to put two 5/8" layers of drywall with green glue for the ceiling. Three of the walls are interior walls and will also have two 5/8" drywall with green glue. The fourth wall is an exterior wall. For the exterior wall, I was planning on just one layer drywall. Is it "diminishing returns" to double drywall and green glue the exterior wall? I'd rather save the $$ if I can.

EDIT: Regarding the exterior wall, I'm not concerned about Home Theater sound that leaks to outside the house (neighbor is very far away), and I'm not concerned about outside sound leaking into the Home Theater. I'm really mainly concerned about sound leaking to the bedroom above. But wondering if it's worth spending the $$ to double-drywall/Green glue an exterior wall (in case sound might transfer to the bedroom above via the exterior wall). Yeah, it's easy to say "just do it", but trying to save $$ here...


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## warwwolf7

randman said:


> I'm putting in a home theater in an unfinished part of my basement. Right above the home theater is a bedroom. So, the plan is to put two 5/8" layers of drywall with green glue for the ceiling. Three of the walls are interior walls and will also have two 5/8" drywall with green glue. The fourth wall is an exterior wall. For the exterior wall, I was planning on just one layer drywall. Is it "diminishing returns" to double drywall and green glue the exterior wall? I'd rather save the $$ if I can.
> 
> EDIT: Regarding the exterior wall, I'm not concerned about Home Theater sound that leaks to outside the house (neighbor is very far away), and I'm not concerned about outside sound leaking into the Home Theater. I'm really mainly concerned about sound leaking to the bedroom above. But wondering if it's worth spending the $$ to double-drywall/Green glue an exterior wall (in case sound might transfer to the bedroom above via the exterior wall). Yeah, it's easy to say "just do it", but trying to save $$ here...


Hi,
That exterior wall you are talking about. It's a standard 2x4 in front of your cement bloc or poured concrete?
In that case if you choose to reduce the soundproofing, more sound will go through. But sound will not only go through the foundation wall of your basement. It will travel up to the bedroom. Flanking path is a b*tch.

The more you reduce the sound before it get in the wall, the less it will travel elsewhere. So if you decide to save a buck and install only 1 layer this will become your weakest link.


If I were to save bucks. I would skip green glue and install hat and channel and double drywall every where. I think you could even go with ib-2 instead of ib-1 for the hat and you would still be under the price of the green glue. (get a quote for both options and you will see by yourself). Hat and channel gives a better result than green glue if you have to choose between them.

I hopes this helps.


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## randman

warwwolf7 said:


> Hi,
> That exterior wall you are talking about. It's a standard 2x4 in front of your cement bloc or poured concrete?
> In that case if you choose to reduce the soundproofing, more sound will go through. But sound will not only go through the foundation wall of your basement. It will travel up to the bedroom. Flanking path is a b*tch.


Thanks for the info. The exterior wall is about 2' to 4' high (varies in height) and is composed of concrete blocks, with the remainder of the wall above the concrete blocks composed of 2x4's. So basically it's concrete blocks and then wood above the concrete blocks. To be clear, you're saying that, despite being an exterior wall, a lot of sound will still travel up the wall and into the room above?


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## Rjloper9

randman said:


> I'm putting in a home theater in an unfinished part of my basement. Right above the home theater is a bedroom. So, the plan is to put two 5/8" layers of drywall with green glue for the ceiling. Three of the walls are interior walls and will also have two 5/8" drywall with green glue. The fourth wall is an exterior wall. For the exterior wall, I was planning on just one layer drywall. Is it "diminishing returns" to double drywall and green glue the exterior wall? I'd rather save the $$ if I can.
> 
> EDIT: Regarding the exterior wall, I'm not concerned about Home Theater sound that leaks to outside the house (neighbor is very far away), and I'm not concerned about outside sound leaking into the Home Theater. I'm really mainly concerned about sound leaking to the bedroom above. But wondering if it's worth spending the $$ to double-drywall/Green glue an exterior wall (in case sound might transfer to the bedroom above via the exterior wall). Yeah, it's easy to say "just do it", but trying to save $$ here...


If you run out of green glue for the exterior wall, I’d still do the second layer of 5/8”. At around $13 per sheet, it’d be worth minimal extra cost.

I’ve been dreading using green glue as well and have been trying to find every reason not to use it, but it’s always seen as “best practice.”


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## mhutchins

Chuck Miller said:


> Thanks for your comments Mike. I realize that stage and riser construction isn't really a soundproofing question, but I've been trying to find some experience with those using insulation, as I'm told sand in the stage is "best practice". Then I read with interest how some/many design their risers as bass traps, using vents on top at the wall boundaries to reduce reflections. Now, my riser setup is very similar to the stage, using an acoustically transparent screen. Both will have two subwoofers directly sitting on them. The stage will also have LCR speakers on it. The riser will have two rear surround speakers installed above it and the equipment rack will be sitting on it as well. And, of course, some seating. What I don't understand is why these to components would be treated differently. I could argue that the stage should be designed like the riser because using it as a bass trap would be expected to provide the same impact to standing waves as the riser would. And, conversely, if sand is best practice for the stage, why not the riser? I'm not interested in schlepping more sand by any means and am truly not sure the value for the stage is worth the effort.
> 
> I take it from your comments that you are not in the camp of recommending a sand filled stage. If you have a stage in your theater, how was it designed and how to you like the result?
> 
> Thanks,
> 
> Chuck


Hi Chuck,

You pose some very good questions! Let me try to answer based on my limited understanding.

*"Then I read with interest how some/many design their risers as bass traps, using vents on top at the wall boundaries to reduce reflections."* - Just for clarity - Room modes in a theater are determined by the shape and dimensions of the room in a complex interaction. It is not simple reflections but more of a resonance effect where certain frequencies are amplified or canceled by the room itself causing peaks and nulls in the in-room frequency response (as I recall, Keith Yates performed CFD analysis of the Hahn Theater to model the room modes). Using the riser as a bass trap is an attempt to capitalize on the relatively higher pressure caused by a peak and diverting some of that "extra" energy into the heavily damped volume contained by the riser, thus diminishing the amplitude of the peaks measured in the room. Remember that at the theater boundaries, pressure is maximum, but particle velocity is at a minimum. From my limited understanding, the riser is acting as a Helmholtz Resonator and is thus "tuned" by the size and number of openings and by the contained volume of the riser. I believe that's why the "Pros" only recommend a small number of vents into the riser chamber rather than just opening up the whole perimeter of the riser.

*"I could argue that the stage should be designed like the riser because using it as a bass trap would be expected to provide the same impact to standing waves as the riser would. And, conversely, if sand is best practice for the stage, why not the riser?"* - Chuck, I think the design dichotomy stems from the common practice of having speakers resting on the stage, but only people seated on the riser. The average riser does not have subwoofers resting on the deck of the riser. Therefore the riser decking is not energized by direct contact with the subwoofer enclosure and thus less prone to resonate from the bass frequencies. Conversely, the stage is typically in direct contact with both the main speakers and often the subwoofers as well, and is therefore at a much greater risk of resonating at certain frequencies.

Another consideration is that risers tend to be taller than stages, thus the volume of sand would be even greater. One member designed a hybrid stage where only the section beneath the subwoofers was sand filled while the rest of the stage had insulation. I believe the sand filled "islands" were decoupled from the rest of the stage as much as possible to prevent direct energy transfer through shared elements in the framing and decking. Both still rested on the same flooring, however...

*"I take it from your comments that you are not in the camp of recommending a sand filled stage. If you have a stage in your theater, how was it designed and how to you like the result?" *I don't have a dedicated theater yet, although I have architectural plans and I have consulted with Nyal Mellor on a sound isolation design. I'm building an addition on top of my attached garage but I didn't want to start such a project with all the supply chain uncertainties and concomitant price gouging that is taking place. I have very demanding sound isolation requirements in order to meet WAF standards. As a result, I will be floating a 3" concrete or Gypcrete slab on a Kinetics RIM system and then building a completely isolated inner room on the floating slab. For now, however, it is on hold....ARGGHHH!

If I had a different design, I would consider a sand filled stage or area behind the baffle wall. I'm not against them, but I'm skeptical of their performance. If Nyal told me I needed a sand filled stage, then I would build a sand filled stage. At this point, we haven't had that discussion.

Mike


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## warwwolf7

randman said:


> Thanks for the info. The exterior wall is about 2' to 4' high (varies in height) and is composed of concrete blocks, with the remainder of the wall above the concrete blocks composed of 2x4's. So basically it's concrete blocks and then wood above the concrete blocks. To be clear, you're saying that, despite being an exterior wall, a lot of sound will still travel up the wall and into the room above?


Are you going to install a stud wall in front of that exterior wall? Otherwise how are you going to attach the drywall to concrete blocks?

I was picturing a stud wall in front of your exterior wall. The sound that will go through your that wall will travel upstairs after. To a lesser extent.
This is the route of the sound through your ceiling

Speakers = > drywall => drywall => insulation => subfloor

For that exterior wall
Speakers => drywall => insulation =>subfloor
It also might have to go through the top plate depending on how tight it is to the exterior wall. 

Sound might be affected by how much space is between your stud wall and the exterior wall. But you are creating an area that is weaker in term of soundproofing. Sound does travel upward, dowward, horizontally. It creates pressure according to the speakers dispersion before the room reflection. Once the room is pressurized it pretty much pushes in all directions with a decrease of pressure based on distance mostly. So yes it can go up in a wall. Flanking path are real. Cnrc did a white paper on that. I'll try to find it

Remember when you are on the highway and you open ever so slightly your window. (Purely fictitious numbers) if you open your window
Close 50dB
5% you get 80dB of outside noise
10% 82db
50% 84dB
100% 85dB
It doesnt take much to ruin soundproofing. If you are trying to save money and skip here and there. Lower your expectations. You don't save much. And honestly. If I were you. I'd skip gg and add that second layer of drywall. 


Then if you have more money I would add hat and channel. If still have money Then I would add green glue. Green glue is not going to give you a result as good as hat and channel. No reason to go that route without hat and channel in my opinion. I know I'm repeating.


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## flyers10

I was looking at the Zero automatic door bottom. Door will be opening out and theater will have carpet while entry area is tile. Is there anything else I need for this to work? Like a threshold plate or anything.


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## warwwolf7

flyers10 said:


> I was looking at the Zero automatic door bottom. Door will be opening out and theater will have carpet while entry area is tile. Is there anything else I need for this to work? Like a threshold plate or anything.


This I what I think. 

Automatic door bottom is a very good step. Ideally, it would seal on something straight and not on carpet in order to get a good seal. But I believe, even on carpet that is going to be good upgrade. 

Door jamb seal all around the door would be another good step. A threshold plate would be another step above, But with diminishing return I don't think it will add a lot if there are no "leaks" at the bottom with the automatic door bottom.


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## impmonkey

Anyone have any experience with this type of clip. I might have a line on some for a decent deal.








Kinetics IsoMax Sound Isolation Clip


Soundproof your room or building with Kinetics IsoMax clips. IsoMax sound isolation clips are durable, easy to install, and qualify for bulk discounts!




www.buyinsulationproductstore.com


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## nathan_h

Assuming one is building a new structure, and has enough space, double walls/double studs with an air gap appears to be very effective, relatively simple to communicate to a contractor, etc. And there are lots of good pictures one can point to to illustrate it.





































But in my search for similar images for a ceiling, I have come up empty. Maybe I don't know the right terms to use for searching?

I'd appreciate being educated or pointed in the right direction.


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## mtbdudex

flyers10 said:


> I was looking at the Zero automatic door bottom. Door will be opening out and theater will have carpet while entry area is tile. Is there anything else I need for this to work? Like a threshold plate or anything.





warwwolf7 said:


> This I what I think.
> 
> Automatic door bottom is a very good step. Ideally, it would seal on something straight and not on carpet in order to get a good seal. But I believe, even on carpet that is going to be good upgrade.
> 
> Door jamb seal all around the door would be another good step. A threshold plate would be another step above, But with diminishing return I don't think it will add a lot if there are no "leaks" at the bottom with the automatic door bottom.


It’s really easy to add full perimeter seal 

Here the big 48” solid core door framed in, no mtg for seals, that’s my seals and auto bottom in box
This was 2015









I ripped my own wood to mount the 3 sides to.
Also you need a simple flat surface for auto bottom, not carpet. Any gap sound will get by. It’s easy to do it right.



























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## squared80

mtbdudex said:


> It’s really easy to add full perimeter seal
> 
> Here the big 48” solid core door framed in, no mtg for seals, that’s my seals and auto bottom in box
> This was 2015
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I ripped my own wood to mount the 3 sides to.
> Also you need a simple flat surface for auto bottom, not carpet. Any gap sound will get by. It’s easy to do it right.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone 11Pro using Tapatalk


What model auto door seal is that.


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## Rjloper9

mtbdudex said:


> It’s really easy to add full perimeter seal
> 
> Here the big 48” solid core door framed in, no mtg for seals, that’s my seals and auto bottom in box
> This was 2015
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I ripped my own wood to mount the 3 sides to.
> Also you need a simple flat surface for auto bottom, not carpet. Any gap sound will get by. It’s easy to do it right.
> 
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> Sent from my iPhone 11Pro using Tapatalk


In reference to the use of the automatic door bottom requiring a flat surface rather than Capet…

My room will be completed before the rest of my basement. I was planning on running carpet to the door threshold and just outside the theater room door would be the concrete slab.

Could I run the carpet to the edge of the doorway and then cover it with some sort of flat metal doorway threshold plate to create a nice seal for the auto door bottom?


Sent from my iPhone using Tapatalk


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## mtbdudex

squared80 said:


> What model auto door seal is that.


It’s from the soundproofing company, bought early 2015, what I paid then



Soundproof Automatic Door Bottoms | Drop Down Acoustical Bottom Seals | TMsoundproofing.com





















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## mtbdudex

Rjloper9 said:


> In reference to the use of the automatic door bottom requiring a flat surface rather than Capet…
> 
> My room will be completed before the rest of my basement. I was planning on running carpet to the door threshold and just outside the theater room door would be the concrete slab.
> 
> Could I run the carpet to the edge of the doorway and then cover it with some sort of flat metal doorway threshold plate to create a nice seal for the auto door bottom?
> 
> 
> Sent from my iPhone using Tapatalk


I documented what I did in build thread , link to the “add a door” project below. I had a 6 foot open space 2008-2015, wanted kids easy play / usage rec room to HT.
In late 2014 decided to add a door, so had to frame 6 feet down to 4 feet , hang big door, etc. seems similar to your situation, room transaction etc.









"The Envelope" Home Theatre 2014: Mike...


I got the pricing back from my special order to Milliken Millwork; wood solid core interior door into exterior frame with seals. It would be a drop in place pre-hung door solid core door with same seals as used for exterior. The below does not reflect the added 25% sale I had them quoted...




www.avsforum.com






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## rhklein

Happy Holidays All!

I was hoping to find some recommendations regarding my HT build. I have a dedicated 16x22x8 room in the basement. When the house was being built I had asked that the builder did not finish this room but he stated that code was that we had to have at least the ceiling drywalled and I had so much else going on at the time that it did not occur to me to ask that he at least do hat channels before drywalling.

In any case, the deed was done. I was planning on using hat channels, double drywall with GG in between for all the walls. However, I still have the ceiling to deal with...

Is there a way to effectively sound proof the room adding to the existing ceiling drywall with say a mass loaded vinyl, hat channels or GG or any combo of the three, then adding another layer of drywall? I am hoping that I don't have to demo the existing ceiling!

Thanks,

Randy


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## nathan_h

rhklein said:


> mass loaded vinyl


Is not very effective for bass. 



rhklein said:


> GG


Helps a bit.



rhklein said:


> hat channels


Best bet.

But leaving the existing drywall will reduce the effectiveness of isolating the basement.

Similar concept. See how having less drywall in the cavity helps reduce transmission?


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## mhutchins

nathan_h said:


> Assuming one is building a new structure, and has enough space....
> .
> .
> But in my search for similar images for a ceiling, I have come up empty. Maybe I don't know the right terms to use for searching?
> 
> I'd appreciate being educated or pointed in the right direction.


The images below are from the Soundproofing Company. 

*STC 76 / IIC 64*










*STC 66 / IIC 56*









*STC 52 / IIC 39*


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## rhklein

Thanks for the replies. Yes, I have really resigned myself to having to demo the existing ceiling if I am to do this right. I will go on the soundproofing company's website but am I rightly assuming that the above post is from best to worst?


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## nathan_h

Thanks. 

Luckily, I don't have ANY subfloor. It's just open attic space.

In other words, what's the right way to build a ceiling when it is just a structure across a room that doesn't touch anything other than the inner wall of a double stud wall for support? 

Sorry, I should have probably written my post that way. That might make it more clear what I am trying to find.

I'm guessing I need joists of a particular 2x[something dependent on space length]. This is a room within a room. There will be a 100% air gap between the ceiling and the building around it. The Soundproofing company is connecting the ceiling to the floor above, and showing that hat channel or clips is the best decoupler. Since I'm not coupled to anything, no floor above, so the diagram would look more like:










Though obviously with some wood frame to connect with ONE SIDE these walls:










Maybe it's so dead simple that no one has bothered to document it, but this is AVS  Someone has documented everything imaginable.




mhutchins said:


> The images below are from the Soundproofing Company.
> 
> *STC 76 / IIC 64*
> View attachment 3212169
> 
> 
> 
> *STC 66 / IIC 56*
> View attachment 3212170
> 
> 
> *STC 52 / IIC 39*
> View attachment 3212171
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> View attachment 3212174
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> View attachment 3212175


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## nathan_h

rhklein said:


> Thanks for the replies. Yes, I have really resigned myself to having to demo the existing ceiling if I am to do this right. I will go on the soundproofing company's website but am I rightly assuming that the above post is from best to worst?


Although @mhutchins wrote their post as a reply to mine, yes, those diagrams are "exactly" your situation. (I mean, there may be a little variation in terms of what your joists look like etc.) And yes, the higher the STC number, the better the isolation.

(STC is a sort of short hand for Sound Transmission Coefficient that doesn't tell you the whole story, since bass travels better than treble, and STC seems to care most about attenuating the vocal range. But in general, better STC is the way to go and is directionally useful.)


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## mhutchins

Yes, Best is at the top and worst is at the bottom.

Mike


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## mhutchins

nathan_h said:


> Thanks.
> 
> Luckily, I don't have ANY subfloor. It's just open attic space.
> 
> In other words, what's the right way to build a ceiling when it is just a structure across a room that doesn't touch anything other than the inner wall of a double stud wall for support?
> .
> .


You will have to span the inner walls with joists that are strong enough to support all of the ceiling drywall and any Atmos speakers you plan to install. Also, if you are planning a ceiling cloud or acoustic treatments, don't forget to include these in you span calculations for the joists. Attach the IB-1 clips (or similar) to the bottom of the joists and fill the area between the joists with rolls of insulation. Since there is no lip to support the bottom of the insulation, you will probably need to install netting across the bottom of the joists to keep the insulation from falling down onto the drywall.

Mike


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## nathan_h

mhutchins said:


> You will have to span the inner walls with joists that are strong enough to support all of the ceiling drywall and any Atmos speakers you plan to install. Also, if you are planning a ceiling cloud or acoustic treatments, don't forget to include these in you span calculations for the joists. Attach the IB-1 clips (or similar) to the bottom of the joists and fill the area between the joists with rolls of insulation. Since there is no lip to support the bottom of the insulation, you will probably need to install netting across the bottom of the joists to keep the insulation from falling down onto the drywall.
> 
> Mike


Thanks for the details.

Question: I figure the joists SHOULD be sized such that there COULD be a room on top of it, ie, just like regular ceiling joists, even though there won't be a room on top. My naive assumption is that that size joist work could easily handle drywall, speakers, acoustic treatment. The place that might become an issue is if I put the subs in the upper corners of the room!

Question: Why include the clips on the joists? The joists aren't attached to the rest of the building. They are just resting on the room walls, which don't connect to the building (other than the concrete floor (unless there is also a way to decouple the bottom of a wall...)

Question: Many homes are built with the insulation sitting on the drywall that constitutes the ceiling in a room, especially if there is attic space above it. Is that a poor practice?


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## squared80

rhklein said:


> the above post is from best to worst?


Take a look at the STC/IIC numbers. Higher is better.


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## mhutchins

nathan_h said:


> Thanks for the details.
> 
> Question: I figure the joists SHOULD be sized such that there COULD be a room on top of it, ie, just like regular ceiling joists, even though there won't be a room on top. My naive assumption is that that size joist work could easily handle drywall, speakers, acoustic treatment. The place that might become an issue is if I put the subs in the upper corners of the room!
> Sizing the joists for a room above will require substantially stronger joists. These will require more vertical clearance above as they will be much taller. Often this requires lowering the ceiling of the theater to accommodate the height of the ceiling joists. Since we are almost always trying to have as tall a ceiling as possible, this would be undesirable. Furthermore, stronger joists will be more expensive.
> 
> Question: Why include the clips on the joists? The joists aren't attached to the rest of the building. They are just resting on the room walls, which don't connect to the building (other than the concrete floor (unless there is also a way to decouple the bottom of a wall...)
> Using clips and channel on the ceiling is optional, however the added decoupling will substantially improve the ceiling STC by 10+ points. Keep in mind that many homes have a common attic space shared by many rooms, thus sound transmission through the shared attic space can create a significant flanking path for theater noise to easily enter adjacent rooms. If possible, consider enclosing the attic above the theater to minimize this flanking path, and/or adding the clips and channel. Finally, Nyal Mellor has told me there are acoustic benefits beyond sound isolation derived from adding decoupled drywall to a room-in-room design.
> 
> Question: Many homes are built with the insulation sitting on the drywall that constitutes the ceiling in a room, especially if there is attic space above it. Is that a poor practice?
> Maybe. There is the potential, albeit small, for the insulation to transmit some of the sound energy from the drywall into the framing if it is in contact with an otherwise decoupled surface. I don't recall any studies that have addressed this directly, so I may be spreading a myth.


*Mike*


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## nathan_h

mhutchins said:


> @Nyal Mellor has told me there are acoustic benefits beyond sound isolation derived from adding decoupled drywall to a room-in-room design.


I‘d surmise it has to do with flex.

That is, a room with drywall walls sounds better than one with concrete walls since the drywall flexes a bit and absorbs / passes some bass out of the room, lessening room mode extremes.

Since decoupled drywall flexes even more than drywall installed the normal way, it probably does that even better.



> Sizing the joists for a room above will require substantially stronger joists. These will require more vertical clearance above as they will be much taller. Often this requires lowering the ceiling of the theater to accommodate the height of the ceiling joists. Since we are almost always trying to have as tall a ceiling as possible, this would be undesirable. Furthermore, stronger joists will be more expensive.


Makes sense and fair enough. I should have called out my build thread where this is going it a detached garage. Still have some eventual constraints and any savings on construction is money that can be used elsewhere, so this is good to think about.

Looks like a double ceiling just like the walls is the best, followed by floating joists if that’s not possible.


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## jerrolds

I have 2 solid core doors - and while the inside frame isnt done, and no sealing around and no carpet installed lol - i think this still will be the weak link. I can feel sound permeating through the 2nd door itself and wondering if theres anything else i can do to add mass. 

I've seen heavy blankets that could help but theyre installed outside the door frame which isnt an option 

thanks for any ideas


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## mtbdudex

jerrolds said:


> I have 2 solid core doors - and while the inside frame isnt done, and no sealing around and no carpet installed lol - i think this still will be the weak link. I can feel sound permeating through the 2nd door itself and wondering if theres anything else i can do to add mass.
> 
> I've seen heavy blankets that could help but theyre installed outside the door frame which isnt an option
> 
> thanks for any ideas



Kudos on the double doors , Have you been to HT with them? I have 3 separate builds.
Yes, the “weakest link”, but overall % wise acceptable.
With full perimeter seals and auto bottom door 

If you desire the most heaviest door , get this “mineral core” solid door and sell / return normal solid core doors.









I’ve seen people get over obsessed (imo) and add either DD+GG (messy as the GG does not stop flowing) or add QuietRock. Screw it on, frame it’s edges with wood, Paint.









Nothing will stop the ultra LFE.


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## ambesolman

Looks like this is what I’ll have to do to address the few things hanging below my floor joists to have clips and channels. Anyone done this? Use just screws or bolts and just leave gaps for any conduits, etc?











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## nathan_h

You have stuff hanging BELOW the joists that you need to work around? I think that was one of the reasons SoundProofingCompany gave for NOT using floating joists. 

For example, the floating joist connects to the plates at the side that also support the regular joists.

So, in theory, if you have stuff BELOW the existing joists, then you have stuff below the plates on the sides, and you won't be able to put the floating joists in because they will be below the stuff that is below the existing joists and therefor below the plates on the side they would need to connect to.

A picture of your situation might help...

(My solution is a new set of joists for the theater, that rest on the decoupled walls of the theater. But it is unusual that one has that might height to spare.


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## ambesolman

nathan_h said:


> You have stuff hanging BELOW the joists that you need to work around? I think that was one of the reasons SoundProofingCompany gave for NOT using floating joists.
> 
> For example, the floating joist connects to the plates at the side that also support the regular joists.
> 
> So, in theory, if you have stuff BELOW the existing joists, then you have stuff below the plates on the sides, and you won't be able to put the floating joists in because they will be below the stuff that is below the existing joists and therefor below the plates on the side they would need to connect to.
> 
> A picture of your situation might help...
> 
> (My solution is a new set of joists for the theater, that rest on the decoupled walls of the theater. But it is unusual that one has that might height to spare.












Old pic, but it mainly just a few electrical cables and small pipes. The lights and ducting will be rerouted. I’m trying to avoid another drop ceiling like I took out so I can do clips and channel, dd+gg.


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## nathan_h

Re routing so you have direct access to those joists for using clips seems like a good approach, though I suspect those walls may allow a lot of flanking noise anyway unless they are redone as decoupled walls?


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## jerrolds

mtbdudex said:


> Kudos on the double doors , Have you been to HT with them? I have 3 separate builds.
> Yes, the “weakest link”, but overall % wise acceptable.
> With full perimeter seals and auto bottom door
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If you desire the most heaviest door , get this “mineral core” solid door and sell / return normal solid core doors.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I’ve seen people get over obsessed (imo) and add either DD+GG (messy as the GG does not stop flowing) or add QuietRock. Screw it on, frame it’s edges with wood, Paint.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Nothing will stop the ultra LFE.
> 
> 
> Sent from my iPhone 11Pro using Tapatalk



Thanks for this - i would have to find extra long screws for the handles but having DD+GG on both doors looks interesting lol - can probably use sealant so the GG doesnt ooze out


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## warwwolf7

jerrolds said:


> Thanks for this - i would have to find extra long screws for the handles but having DD+GG on both doors looks interesting lol - can probably use sealant so the GG doesnt ooze out


I don't understand the reference to gg leaking. The gg never oozed out when I installed my drywall on the walls


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## mtbdudex

jerrolds said:


> Thanks for this - i would have to find extra long screws for the handles but having DD+GG on both doors looks interesting lol - can probably use sealant so the GG doesnt ooze out



Or, you leave the door handle an access zone , like I did when adding acoustic treatments to my door 










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## mtbdudex

warwwolf7 said:


> I don't understand the reference to gg leaking. The gg never oozed out when I installed my drywall on the walls


Understood, however you did not have open edge like a door would.
Now if after applied door is flat for 45 days, sure. 
(I read this actually happened in a full DIY door build …)

From their FAQ
6. I added drywall and Green Glue onto my wall and I do not hear that much improvement.

You have to Wait 7 days before attempting to listen for improvement. When Green Glue is applied it is in a very liquidity form so the only improvement your wall/ceiling has is the added layer of drywall. Once the Green Glue starts drying and becoming elastic you begin to have the damping factor improvement. That starts at 7-8 days after application and lasts up to 45 days when you get the full benefit of the Green Glue.


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## warwwolf7

mtbdudex said:


> Understood, however you did not have open edge like a door would.
> Now if after applied door is flat for 45 days, sure.
> (I read this actually happened in a full DIY door build …)
> 
> From their FAQ
> 6. I added drywall and Green Glue onto my wall and I do not hear that much improvement.
> 
> You have to Wait 7 days before attempting to listen for improvement. When Green Glue is applied it is in a very liquidity form so the only improvement your wall/ceiling has is the added layer of drywall. Once the Green Glue starts drying and becoming elastic you begin to have the damping factor improvement. That starts at 7-8 days after application and lasts up to 45 days when you get the full benefit of the Green Glue.
> 
> 
> Sent from my iPhone 11Pro using Tapatalk


Thanks for clarifying. 

Did you play with gg yourself? Once applied, it's not liquid like water. It's liquid, and will drip if you leave your drywall vertically for too long before installing. But once it's in sandwich between the 2 sheets. It ain't moving. 
When I applied on the wall, I did left a very small gap at the bottom that I later filled with acoustical sealent. I'm pretty sure gg didn't drip at all. Because I left the project sit a while between each step, I took me a couple of days before I could applied the sealent at the bottom.

I took a picture of the second layer. 2 tubes (of the recommended caulking gun from the soundproofing company) per sheet of 4x8 with the recommendation of not applying on the 1-2" outer edge of the sheet. 
No a single drip.
Hard to tell from this picture but here it is anyway. The gg had been applied for More than 45days ago. 
If it dripped for another user, they must have used more than the recommended amount. 

Nonetheless, for you door, I'm sure you wouldn't want to leave the edge of the drywall exposed. Framing around it is a must in this case in my opinion.


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## ambesolman

nathan_h said:


> Re routing so you have direct access to those joists for using clips seems like a good approach, though I suspect those walls may allow a lot of flanking noise anyway unless they are redone as decoupled walls?


Oh yeah, walls being redone too. Clips and channel on inside walls, ddgg on outer walls. All room within a room construction. Plan on busting up that hearth and plugging up the fireplace too.

With what you see below my joists, do u think there’s room enough for clips and channel without having to lower the joists?

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## nathan_h

I’m not an expert and the photos aren’t clear enough to me. Maybe measure the specific items that won’t be rerouted and ask SoundProofingCompany.com?


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## Gurot123

My theatre area is in the basement. I am attempting to dd+gg the subfloor in between the joists of the room above. Using 5/8 inch drywall. From my best attempts at measuring the thickness of the subfloor it looks like it is 5/8 inch. The hardwood is on top of the subfloor. I just did my first joist area. I used 1 and 1/4 inch coarse drywall screw for the first layer drywall. I used 1 and 5/8 for the second layer, but it didn't grab much. I changed to a 2 inch drywall screw and it grabbed. What risk is there to the hardwood floor if the screw is just a little bit too long? I was looking at 1 7/8 inch drywall screws, but they aren't readily available. In my head the section of hardwood in the room above feels different than before...I think it is all in my head but wanted to double check if the potentially slightly longer screw would cause any upward pressure on the hardwood planks. Mods please move this if I posted in the wrong thread. Thanks


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## drumminj

Hey all..finally finished reading through this thread in its entirety (only took a few months!) as we finalize the plans for our custom house build. Learned a ton (thank you all who contributed!), and now would like to get feedback on my plan for the media room in our house.

To clarify up front, this is not a dedicated theater room, but instead a multi-use media room. The goals are:

Function as a “living room” in most cases, with easy access to wander in with coffee + breakfast in the morning to sit and read, surf the internet, etc. (hence the French doors/wide opening)
House the “good” media equipment – 65” OLED tv and my 5.1 setup (L+R floor standers, two subs, wall-mounted surrounds likely to be replaced with another pair of floor standers)
Minimize bleeding of sound into other areas of the house when system is in use, presumably with doors closed. Don’t need 100% sound insulation, but cutting 40-50dB or more if possible.
Note that in general I don’t listen at reference levels – normal movie watching is at ~43 on my Marantz, or ~62 when listening loudly. I’m primarily concerned about sound going to the master bedroom, “Bedroom 3” upstairs, and the Great Room.

*Planned approach:*

Clips + channel on the ceiling (IB-1 or similar clips)
Staggered stud 2x6 walls for shared interior walls (see highlighted walls on floorplan). Going with staggered studs vs clip + channel on walls for easier wall mounting of surrounds, panels, etc.
Standard 2x6 framing for exterior walls
5/8” Type X drywall throughout the house
DD + green glue on walls and ceiling of media room, with staggered seams between layers and appropriate caulking of gaps
Rockwool S&S or R13 pink fluffy in walls and ceiling
Acoustic caulk under and at edge of bottom plates
Putty pads on outlets and switches, ensuring interior and exterior receptacle on shared walls are in different stud bays
Backer boxes for in-ceiling lighting fixtures
Solid core doors with the best STC rating I can find , floor + jamb seals
SVS isolation feet on subs
I know folks will immediately say “ditch the French doors”, but these are critical to how we want to use the space/make it feel like a common/casual space.

*Anyone see any area I’m over- or under-investing in?* I know the doors will be the weak link, so tried to balance the efforts and investment being made. Is there a need to do more with the shared wall with the garage, or the exterior wall?

All thoughts appreciated!


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## squared80

You're going way overboard and spending far too much time and money on that room if you're going to use French doors.

Think about driving down a highway in your car. When you crack the window even an inch, think about how loud that is. You're not just letting in a tiny bit of sound... you're letting in most of it. Same thing applies to a sealed room that isn't sealed (generally speaking).

There are still benefits to many of the things you want to do, but if you're not sealing that thing like a shell, then save your money. Seriously.


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## drumminj

squared80 said:


> You're going way overboard and spending far too much time and money on that room if you're going to use French doors.
> 
> ...
> 
> There are still benefits to many of the things you want to do, but if you're not sealing that thing like a shell, then save your money. Seriously.


I appreciate the response/thoughts. In your opinion, what is overkill and what is worthwhile? From what I've seen on this thread, ~STC40 doors are available. Is it the staggered studs and clips + channel you think are overkill? Or even DD + GG?

I do honestly appreciate any/all feedback. The french doors are fundamental (though I expect to customize them a bit/possibly add mass via gluing on MDF or sheetrock on inside), so am looking for thoughts on what's worthwhile and what's not -- what's the best I can do with that constraint.


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## Gurot123

Finally added a few layers of drywall between a portion of the joists in the ceiling. Happy to report the screws being an eight of an inch too long did not impact the hardwood flooring in the room above. You guys weren't kidding when you mentioned how much of a pain it is to cut down the staples protruding through the subfloor. My oscillating tool initially showed promise, but did not pan out. Ended up using my klein cutters. It was a lot faster, but it did reveal how I have lost grip strength over the years! Still a lot of work to go, but noticed that when walking on the hardwood floor in room above, there is less noise in the dining room and there isn't as much movement in the dishes in the hutch.


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## squared80

Gurot123 said:


> Finally added a few layers of drywall between a portion of the joists in the ceiling. Happy to report the screws being an eight of an inch too long did not impact the hardwood flooring in the room above. You guys weren't kidding when you mentioned how much of a pain it is to cut down the staples protruding through the subfloor. My oscillating tool initially showed promise, but did not pan out. Ended up using my klein cutters. It was a lot faster, but it did reveal how I have lost grip strength over the years! Still a lot of work to go, but noticed that when walking on the hardwood floor in room above, there is less noise in the dining room and there isn't as much movement in the dishes in the hutch.


Good for you. This task gets results, but it is a major PITA.


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## Gurot123

squared80 said:


> Good for you. This task gets results, but it is a major PITA.


Tell me about it. Takes so much time and initially I was just going to redo the bulkhead in the room. All I have done with the bulk head is take it down the old one and then foil tape all the seams in the duct work and put some Frost king on it. Oh yeah, I also sealed up the hole in the cold air return line. That reduced some of the hvac noise already. But the most time so far has been cutting those staples. I can only imagine what a room that is fully done (not what I will end up with) would sound (or rather not sound) like. My sore back!


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## warwwolf7

Gurot123 said:


> Tell me about it. Takes so much time and initially I was just going to redo the bulkhead in the room. All I have done with the bulk head is take it down the old one and then foil tape all the seams in the duct work and put some Frost king on it. Oh yeah, I also sealed up the hole in the cold air return line. That reduced some of the hvac noise already. But the most time so far has been cutting those staples. I can only imagine what a room that is fully done (not what I will end up with) would sound (or rather not sound) like. My sore back!


I used a grinder to cut the nails from the hard floor. It went really fast with a thin cutting disk. However, it creates hots nails that will fall down. Full glasses. Ear protection, long sleeves, hat and a clear floor underneath is a must whenever you are working with a grinder. Even more when it's above your head. Make sure you work on a very stable platform. You don't want to fall with a grinder 

Also if the disk touches the subfloor, it will leave burn marks, creates a little bit of smokes. Keep a water spray bottle just in case.

Took me 5-10min per joist cavity. They were 13' wide. For staples It would have been a joke to cut. My house was built in 1960 and they used nails. Flooring staples are nothing compared to those in terms of cutting with a grinder.

This method might not be for everyone. But it is very fast. If you use this method, be on the safe side.


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## Gurot123

Funny you mentioned the fallen nails. I had a few of the cut staples that found some uncovered carpet and melted to the carpet! Thankfully there were only a few pieces of exposed carpet that evaded all the tarp on the ground.


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## warwwolf7

Gurot123 said:


> Funny you mentioned the fallen nails. I had a few of the cut staples that found some uncovered carpet and melted to the carpet! Thankfully there were only a few pieces of exposed carpet that evaded all the tarp on the ground.


Oh! With carpet underneath, Klein cuter was probably the best idea.
I can't imagine working with carpet in a room. I'm soo messy, I would ruin that carpet on the first reno day!


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## ambesolman

nathan_h said:


> You have stuff hanging BELOW the joists that you need to work around? I think that was one of the reasons SoundProofingCompany gave for NOT using floating joists.
> 
> For example, the floating joist connects to the plates at the side that also support the regular joists.
> 
> So, in theory, if you have stuff BELOW the existing joists, then you have stuff below the plates on the sides, and you won't be able to put the floating joists in because they will be below the stuff that is below the existing joists and therefor below the plates on the side they would need to connect to.
> 
> A picture of your situation might help...
> 
> (My solution is a new set of joists for the theater, that rest on the decoupled walls of the theater. But it is unusual that one has that might height to spare.





ambesolman said:


> Old pic, but it mainly just a few electrical cables and small pipes. The lights and ducting will be rerouted. I’m trying to avoid another drop ceiling like I took out so I can do clips and channel, dd+gg.
> 
> 
> Sent from my iPhone using Tapatalk?


Hers a drawing of the basement in question. The few pipes and power cables would protrude no more than 2” below the joists. Would they fit in the gap created by the clips and channel?











Sent from my iPhone using Tapatalk?


----------



## warwwolf7

ambesolman said:


> Hers a drawing of the basement in question. The few pipes and power cables would protrude no more than 2” below the joists. Would they fit in the gap created by the clips and channel?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk?


The hat and channel with the ib1 clip will provide a clearance of 1.25"


----------



## squared80

What's the best way to soundproof where the speaker wires come through the drywall. I don't want to cut holes all over my DD+GG, but the holes have to be big enough so I can actually get to and pull my speaker wires through it. Do I build backer boxes for these areas, too, just like I did for everything else? And then just fill the hole going into the backer box with acoustical after I've pulled it through?

Wondering how you got your speaker wire through the drywall and closed up the holes without compromising your shell.


----------



## Chuck Miller

squared80 said:


> What's the best way to soundproof where the speaker wires come through the drywall. I don't want to cut holes all over my DD+GG, but the holes have to be big enough so I can actually get to and pull my speaker wires through it. Do I build backer boxes for these areas, too, just like I did for everything else? And then just fill the hole going into the backer box with acoustical after I've pulled it through?
> 
> Wondering how you got your speaker wire through the drywall and closed up the holes without compromising your shell.


I used acoustical sealant around all the wires coming through the drywall and into the backer boxes. It's the recommended approach for where the speaker or power wires enter a backer box, so I deduced it should be appropriate for the wires coming through the drywall as well.


----------



## Mr_Whatsit

The cold air returns in my basement are made up of joists, subfloor and sheet metal. The sheet metal tends to reverberate with footfall, but the system is otherwise quiet. I'm planning on sound isolation clips/hat channel/DD/GG on the ceiling & walls. I'm sure that the sheet metal sounds will come through even if GG/DD is in place. Can I replace the sheet metal with with drywall installed inbetween the joists to eliminate the reverberations? Or is there a better solution?


----------



## nathan_h

Flexible duct might be a good replacement for the rigid ducting.


----------



## warwwolf7

nathan_h said:


> Flexible duct might be a good replacement for the rigid ducting.


@Mr_Whatsit 

Use rigid duct and stick dynamat on it or an equivalent product it will prevent the resonance of the metal sheet.

Look for the local code if you can conceal flexible duct. Chances are it is not.

You can replace your metal sheet with joist liner (like the thermopam joist liner as en example I'm. Not sur of the proper name). I don't know that product, it could be your solution if it's allowed in your area. 

In conclusion, I don't think drywall is a recommended practice, neither flexible duct in a concealed area


----------



## nathan_h

warwwolf7 said:


> Look for the local code if you can conceal flexible duct


Good reminder. No matter what you decide to do, check with local code and get it permitted and signed off, otherwise future insurance claims issues might become a real problem. (And it's safer, as well, to comply with code and get it inspected.)


----------



## Mr_Whatsit

warwwolf7 said:


> @Mr_Whatsit
> 
> Use rigid duct and stick dynamat on it or an equivalent product it will prevent the resonance of the metal sheet.
> 
> Look for the local code if you can conceal flexible duct. Chances are it is not.
> 
> You can replace your metal sheet with joist liner (like the thermopam joist liner as en example I'm. Not sur of the proper name). I don't know that product, it could be your solution if it's allowed in your area.
> 
> In conclusion, I don't think drywall is a recommended practice, neither flexible duct in a concealed area


Thanks, this I think led me down the right path. I'd rather redo the existing work with something promising to cut the noise down, rather than installing new ducting and wrapping it in an insulator. I have 3 of those panned floor joist cavities partially passing through the ceiling of the theater, so Thermo-Pan seems to be the product for the job, and they bill themselves as the "no noise" sheet metal. Sized perfectly. Anyone have experience with it?









ULTRA FIRE RESISTANT


Spec Sheet FIRE-RESISTANT THERMO-PAN™ is a high-quality “No Noise” sheet metal alternative for constructing return air ducts No duct noise Satisfied homeowners Excellent for open web trusses Lightweight and easy to install Will not sustain combustion Airspace created provides R-Value = 5 No...




thermopan.com


----------



## Lasalle

drumminj said:


> I appreciate the response/thoughts. In your opinion, what is overkill and what is worthwhile? From what I've seen on this thread, ~STC40 doors are available. Is it the staggered studs and clips + channel you think are overkill? Or even DD + GG?
> 
> I do honestly appreciate any/all feedback. The french doors are fundamental (though I expect to customize them a bit/possibly add mass via gluing on MDF or sheetrock on inside), so am looking for thoughts on what's worthwhile and what's not -- what's the best I can do with that constraint.


You can get "sound proof" French doors, but they are very expensive and heavy. They also include and integrated frame.


----------



## Lasalle

drumminj said:


> Hey all..finally finished reading through this thread in its entirety (only took a few months!) as we finalize the plans for our custom house build. Learned a ton (thank you all who contributed!), and now would like to get feedback on my plan for the media room in our house.
> 
> To clarify up front, this is not a dedicated theater room, but instead a multi-use media room. The goals are:
> 
> Function as a “living room” in most cases, with easy access to wander in with coffee + breakfast in the morning to sit and read, surf the internet, etc. (hence the French doors/wide opening)
> House the “good” media equipment – 65” OLED tv and my 5.1 setup (L+R floor standers, two subs, wall-mounted surrounds likely to be replaced with another pair of floor standers)
> Minimize bleeding of sound into other areas of the house when system is in use, presumably with doors closed. Don’t need 100% sound insulation, but cutting 40-50dB or more if possible.
> Note that in general I don’t listen at reference levels – normal movie watching is at ~43 on my Marantz, or ~62 when listening loudly. I’m primarily concerned about sound going to the master bedroom, “Bedroom 3” upstairs, and the Great Room.
> 
> *Planned approach:*
> 
> Clips + channel on the ceiling (IB-1 or similar clips)
> Staggered stud 2x6 walls for shared interior walls (see highlighted walls on floorplan). Going with staggered studs vs clip + channel on walls for easier wall mounting of surrounds, panels, etc.
> Standard 2x6 framing for exterior walls
> 5/8” Type X drywall throughout the house
> DD + green glue on walls and ceiling of media room, with staggered seams between layers and appropriate caulking of gaps
> Rockwool S&S or R13 pink fluffy in walls and ceiling
> Acoustic caulk under and at edge of bottom plates
> Putty pads on outlets and switches, ensuring interior and exterior receptacle on shared walls are in different stud bays
> Backer boxes for in-ceiling lighting fixtures
> Solid core doors with the best STC rating I can find , floor + jamb seals
> SVS isolation feet on subs
> I know folks will immediately say “ditch the French doors”, but these are critical to how we want to use the space/make it feel like a common/casual space.
> 
> *Anyone see any area I’m over- or under-investing in?* I know the doors will be the weak link, so tried to balance the efforts and investment being made. Is there a need to do more with the shared wall with the garage, or the exterior wall?
> 
> All thoughts appreciated!
> 
> View attachment 3215882
> View attachment 3215883


If you are worried about sound traveling past the room, you'll need to deal with your HVAC vents. The larger the opening the lower the frequency that will be transmitted through them. You can use multiple smaller supplies , but you'll probably need to build a muffler on each return. If you're on a first floor slab the floors are fine, otherwise they need to be sound proofed as well.


----------



## Rodzilla

I'm looking to build out a basement home theater where the current space is unfinished, I have wood joists above (hardwood floor for the main section of the house), and three of the walls are concrete block foundation walls where the fourth wall would be into the still-unfinished part of the basement. Primarily looking to make sure I can lock-in the final build dimensions of the room and wanted to make sure I'm on the right track with both soundproofing and moisture issues. 

My main questions on soundproofing are:

How much do I need to care about soundproofing the walls I'll frame off the concrete block? Will the block act as a flanking path into the rest of my house (directly above the theater is my main living room and dining room)?
Do I need to care about the concrete foundation floor? Will that act as a path for sound to resonate into the rest of the house?
My plan for the build was as follows, but I want to make sure I'm not going overboard on the walls, that my plan for vapor barriers is sufficient, and that I'm not skimping on the floor:

Basement framing plan for all walls (ceiling would be the same except no rigid foam)

1.5” rigid foam insulation against concrete walls - Owens Corning FOAMULAR NGX F-150 1.5 in. x 4 ft. x 8 ft. SSE R-7.5 XPS Rigid Foam Board Insulation-88WDNGX - The Home Depot 
Tape between insulation panels - TYVEK HomeWrap 2 in. x 164 ft. Housewrap Installation Tape-D13841470 - The Home Depot 
Pressure treated 2x4 on floor
2x4 wood framing
R-13 fiberglass insulation between studs
Recessed Genieclip LB3 (adds 0.5”) for sound isolation - https://isostore.com/pub/media/specs/GenieClip-LB3-Guide.pdf
Furring hat channels into clips - Furring Hat Channel 6' 
⅝” fire-rated drywall hung on furring hat channels
Green glue
⅝” fire-rated drywall
Basement flooring plan

½” floor underlayment - DMX Air Gap 44-1/2" x 50' Flooring Underlayment Kit or maybe even thinner? - https://decorner.com/products/abate-underlayment 
Plywood (or OSB?) on top
Carpet on top

The space is roughly 159" (w) x 300" (l) x 92" (h) so I'm trying to strike a balance between not losing much width or height while still having it properly soundproofed and not moldy.


----------



## squared80

Rodzilla said:


> I'm looking to build out a basement home theater where the current space is unfinished, I have wood joists above (hardwood floor for the main section of the house), and three of the walls are concrete block foundation walls where the fourth wall would be into the still-unfinished part of the basement. Primarily looking to make sure I can lock-in the final build dimensions of the room and wanted to make sure I'm on the right track with both soundproofing and moisture issues.
> 
> My main questions on soundproofing are:
> 
> How much do I need to care about soundproofing the walls I'll frame off the concrete block? Will the block act as a flanking path into the rest of my house (directly above the theater is my main living room and dining room)?
> Do I need to care about the concrete foundation floor? Will that act as a path for sound to resonate into the rest of the house?
> My plan for the build was as follows, but I want to make sure I'm not going overboard on the walls, that my plan for vapor barriers is sufficient, and that I'm not skimping on the floor:
> 
> Basement framing plan for all walls (ceiling would be the same except no rigid foam)
> 
> 1.5” rigid foam insulation against concrete walls - Owens Corning FOAMULAR NGX F-150 1.5 in. x 4 ft. x 8 ft. SSE R-7.5 XPS Rigid Foam Board Insulation-88WDNGX - The Home Depot
> Tape between insulation panels - TYVEK HomeWrap 2 in. x 164 ft. Housewrap Installation Tape-D13841470 - The Home Depot
> Pressure treated 2x4 on floor
> 2x4 wood framing
> R-13 fiberglass insulation between studs
> Recessed Genieclip LB3 (adds 0.5”) for sound isolation - https://isostore.com/pub/media/specs/GenieClip-LB3-Guide.pdf
> Furring hat channels into clips - Furring Hat Channel 6'
> ⅝” fire-rated drywall hung on furring hat channels
> Green glue
> ⅝” fire-rated drywall
> Basement flooring plan
> 
> ½” floor underlayment - DMX Air Gap 44-1/2" x 50' Flooring Underlayment Kit or maybe even thinner? - https://decorner.com/products/abate-underlayment
> Plywood (or OSB?) on top
> Carpet on top
> 
> The space is roughly 159" (w) x 300" (l) x 92" (h) so I'm trying to strike a balance between not losing much width or height while still having it properly soundproofed and not moldy.


Sounds like you should create a build thread. Where do you live? I'd always recommend going with the 2" XPS.


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## Rodzilla

squared80 said:


> Sounds like you should create a build thread. Where do you live? I'd always recommend going with the 2" XPS.


TBH I wasn't sure if this belonged in the master soundproofing thread as it's mostly soundproofing specific questions or in my year-old build thread so I posted in both, sorry for the duplication - Starting the design process


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## nathan_h

Soundproofingcompany.com has great info for floors walls and ceilings. The question is how much sound attenuation is enough versus your budget.


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## Rjloper9

I recently put double layers of 5/8 drywall between the ceiling floor joists inside my room.

Due to budget and wanting to keep the room moving along I opted not to use green glue between these layers. Another reason for not doing green glue between these layers is because I quickly realized it was impossible to get perfect cuts on the drywall pieces and the joists weren’t perfectly parallel either. Therefore, I figured green glue would’ve been “wasted” in this step.

Once I got the ceiling done, I then filled all the joist bays with R19 insulation.

After it was completed, I turned on my portable Bluetooth speaker and went upstairs in our master bedroom above. I was very surprised at how little sound was transmitting through to the room above.

Granted there’s little to no bass coming out of the speaker, but I was very impressed at the suppression of the high frequencies. I had to really focus to hear what sounded only like a whisper conversation going on below me.

Happy camper currently and hoping it only works better as the ceiling gets completed and the GG is incorporated.


Sent from my iPhone using Tapatalk


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## warwwolf7

Rjloper9 said:


> I recently put double layers of 5/8 drywall between the ceiling floor joists inside my room.
> 
> Due to budget and wanting to keep the room moving along I opted not to use green glue between these layers. Another reason for not doing green glue between these layers is because I quickly realized it was impossible to get perfect cuts on the drywall pieces and the joists weren’t perfectly parallel either. Therefore, I figured green glue would’ve been “wasted” in this step.
> 
> Once I got the ceiling done, I then filled all the joist bays with R19 insulation.
> 
> After it was completed, I turned on my portable Bluetooth speaker and went upstairs in our master bedroom above. I was very surprised at how little sound was transmitting through to the room above.
> 
> Granted there’s little to no bass coming out of the speaker, but I was very impressed at the suppression of the high frequencies. I had to really focus to hear what sounded only like a whisper conversation going on below me.
> 
> Happy camper currently and hoping it only works better as the ceiling gets completed and the GG is incorporated.
> 
> 
> Sent from my iPhone using Tapatalk


For anyone doing drywall between floor joist. I would recommend you make a jig like this. 










King Kontrol HT build thread


Current state I’m from Canada, I’m French (you’ll probably read grammatically wrong sentences, excuse me in advance)I work in the event industry, projection, ledwall, mapping, system integration, etc. I’m not an expert, but I have been around the technology and event industry for the last...




www.avsforum.com





Is was able to mimic the curvature of the joists and I was able to make very tight fits.


----------



## Rjloper9

warwwolf7 said:


> For anyone doing drywall between floor joist. I would recommend you make a jig like this.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> King Kontrol HT build thread
> 
> 
> Current state I’m from Canada, I’m French (you’ll probably read grammatically wrong sentences, excuse me in advance)I work in the event industry, projection, ledwall, mapping, system integration, etc. I’m not an expert, but I have been around the technology and event industry for the last...
> 
> 
> 
> 
> www.avsforum.com
> 
> 
> 
> 
> 
> Is was able to mimic the curvature of the joists and I was able to make very tight fits.


Awesome idea


Sent from my iPhone using Tapatalk


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## ellsworth

Couple of random soundproofing questions...

1) Will placing an open back in-ceiling speakers in a backer box like the design from the Soundproofing Company negatively affect its performance?

2) How do you determine the correct jamb width for a door? Should it be equal to the thickness of the wall?


----------



## Trawbreaga

My question may veer into room treatment territory but can a DIY vocal booth achieve:

Decoupling
Adding Mass
Damping
Absorbing
...or even part way, with good materials, equipment and some good lateral thinking? I saw one user say that for 50% of the way to expect maybe a 25% effectiveness/improvement in return, so I do want to take it as far as I can using any means available to me on my - what will be very limited - budget.

I have plenty of space in my living room for such a thing. However there may be the issue of having to make it also collapsible for convenience - and to make it possible to get through the very normal sized front door.

Anyone ever constructed a vocal booth for outside use? Still get noise coming in I guess, plus disturbances and aggro from neighbours, I suppose.

Any help is appreciated. Trying to learn about this and other stuff so I assure you I am trying to take in as much as I can.

Seeking to isolate as much as I can for me and for neighbours as it is metal vocals I wish to record. Any and all kinds of metal barring the more extreme end. So your basic heavy/power/thrash I am trying to record in relative peace if at all possible.


----------



## DrDon

Trawbreaga said:


> My question may veer into room treatment territory but can a DIY vocal booth achieve:
> 
> Decoupling
> Adding Mass
> Damping
> Absorbing
> ...or even part way, with good materials, equipment and some good lateral thinking? I saw one user say that for 50% of the way to expect maybe a 25% effectiveness/improvement in return, so I do want to take it as far as I can using any means available to me on my - what will be very limited - budget.
> 
> I have plenty of space in my living room for such a thing. However there may be the issue of having to make it also collapsible for convenience - and to make it possible to get through the very normal sized front door.
> 
> Anyone ever constructed a vocal booth for outside use? Still get noise coming in I guess, plus disturbances and aggro from neighbours, I suppose.
> 
> Any help is appreciated. Trying to learn about this and other stuff so I assure you I am trying to take in as much as I can.


I don't have a full-size vocal _booth_, per se, but I do have a cheap-and-dirty enclosure that works better than expected and is very portable.

For mine, I took a large, plastic storage tub and lined it with textured foam rubber. I used a combination of the egg-carton foam from hard drives I had shipped to the house along with textured foam rubber Walmart sells for cot bedding. I use an SM-5B that sits in the enclosure on a desk stand with a windscreen. When I need a TelePrompTer, I fit a Lenovo Yoga Book C930 (folded out flat) behind the microphone. It's Florida, so the room I work in is fitted with hurricane windows, which cuts the outside sound down tremendously. I had considered putting moving van blankets on stands behind me to cut the room ring, but with my upper body blocking most of the enclosure's opening, I found that unnecessary. Since it's a storage tub, I can disassemble the microphone, fold up the computer and fit it all - including the microphone processor and the Scarlett interface box - into the tub for transportation. My master audio production computer is a Lenovo X1 Extreme Gen 4, so it's portable, as well.

I haven't tried the enclosure, outdoors, but I imagine I could sit it on a picnic table in a quiet park and my clients would never know the difference.

I guess it all depends on your objective. For me, it's voicing commercials, narrating documentaries or video presentations, and voice-tracking radio shows.

Doc


----------



## Trawbreaga

Wow, that was quick! Thanks, Doc. Is it voiceover work you do? I meant this for recording vocals to music so trying to create as much peace for me and for neighbours as possible - but that sounds perfect for quick voiceover parts which I would like to do as well.


----------



## nathan_h

ellsworth said:


> Couple of random soundproofing questions...
> 
> 1) Will placing an open back in-ceiling speakers in a backer box like the design from the Soundproofing Company negatively affect its performance?
> 
> 2) How do you determine the correct jamb width for a door? Should it be equal to the thickness of the wall?


1. Unlikely but it is worthwhile asking the specific speaker manufacturer. 
2. I am not sure I understand your question Or at least I don’t know a reason to do otherwise.


----------



## DrDon

Trawbreaga said:


> Wow, that was quick! Thanks, Doc. Is it voiceover work you do? I meant this for recording vocals to music so trying to create as much peace for me and for neighbours as possible - but that sounds perfect for quick voiceover parts which I would like to do as well.


Well, your post ended up in the approval queue and I just happened to be the mod to catch it. Yeah, I do voicework from some of the clients and friends I amassed during a few decades in Radio/TV. I actually make more from the writing than the voicing. The only thing that messes things up is when lawn crews break out the leaf blowers.... which they always seem to do 15 minutes before a deadline.


----------



## ellsworth

nathan_h said:


> 2. I am not sure I understand your question Or at least I don’t know a reason to do otherwise.


Thanks for reply nathan_h. I've read in older posts regarding doors that one should determine the correct jamb size. So, stupid question: How do you determine that?


----------



## schwock5

ellsworth said:


> Couple of random soundproofing questions...
> 
> 1) Will placing an open back in-ceiling speakers in a backer box like the design from the Soundproofing Company negatively affect its performance?
> 
> 2) How do you determine the correct jamb width for a door? Should it be equal to the thickness of the wall?


When i was going with the Klipsch 5800 for in-wall surrounds and cieling heights i asked them about that.
Since they are "infinite baffle" speakers, they are created with the intent of a standard 16 inch on center cavity with insulation acting as the speaker enclosure.
I didn't built backer boxes, but bought those pre-fab metal fire proof ones that i then wrapped with additional sound proof material.

Klipsch stated that i'd probably see the bass affected and drop off earlier using a small cavity like that box.
I can't tell you from a box vs non box comparison, but when i ran audyssey and verified from when I ran REW, i can tell you the 5800 surrounds needed a 120 hz crossover (the boxes were 4 inches deep for a standard wall depth). the in-ceilings had a 6 inch depth box because the joist cavity is bigger and needed a 100hz crossover. so it may potentially be due tot he boxes curbing the bass.

In real-world usage, i couldn't tell if i'd notice a difference or not if there was no box with a lower crossover vs what I have.

What would impact is that i run my subwoofer hot, so the added bass being crossed to the sub for those speakers would also then be a little hotter as well.


----------



## nathan_h

ellsworth said:


> Thanks for reply nathan_h. I've read in older posts regarding doors that one should determine the correct jamb size. So, stupid question: How do you determine that?


Might be worth hitting up the folks that posted that guidance. I suspect in general household construction practices a little gap behind the trim is considered no problem but for sound attenuation you’d want to minimize that possible gap and fill that with caulk too.


----------



## cricket9998

I designed some semi permanent window plugs. It’s plywood (painted white so it doesn’t look poor from the outside) cut to fit right on the actual window. I put down some thin foam so it’s not directly touching the frame. That piece has MLV stapled to it. Then I got thicker plywood also with MLV and screwed that into the window trim such that it seals up the entire window. I then put acoustic sealant on the entire thing. With 2 layers of MLV and a small air gap it seems to stop all noise except a plane which is fine.


----------



## cricket9998

cricket9998 said:


> I designed some semi permanent window plugs. It’s plywood (painted white so it doesn’t look poor from the outside) cut to fit right on the actual window. I put down some thin foam so it’s not directly touching the frame. That piece has MLV stapled to it. Then I got thicker plywood also with MLV and screwed that into the window trim such that it seals up the entire window. I then put acoustic sealant on the entire thing. With 2 layers of MLV and a small air gap it seems to stop all noise except a plane which is fine.


After finishing this I have some thoughts. It definitely helped a lot of the higher pitched road noise but in a dead quiet room you can still hear the road. Also didn’t do anything for loud boomy exhausts. I designed it to minimize window modifications but I wish I acoustically sealed the entire window first and completely sealed the first layer of plywood. I would also add way more mass to it but I ran out of MLV. you need at least 3 layers to do the job.


----------



## ambesolman

cricket9998 said:


> After finishing this I have some thoughts. It definitely helped a lot of the higher pitched road noise but in a dead quiet room you can still hear the road. Also didn’t do anything for loud boomy exhausts. I designed it to minimize window modifications but I wish I acoustically sealed the entire window first and completely sealed the first layer of plywood. I would also add way more mass to it but I ran out of MLV. you need at least 3 layers to do the job.


Is the first layer of plywood right up to the glass or is there a gap? I saw a suggestion once where someone installed blinds (only thing visible through the window) then put a layer of insulation behind it. Then put what you made over that? Just a thought, but depends on space available.


Sent from my iPhone using Tapatalk?


----------



## cricket9998

ambesolman said:


> Is the first layer of plywood right up to the glass or is there a gap? I saw a suggestion once where someone installed blinds (only thing visible through the window) then put a layer of insulation behind it. Then put what you made over that? Just a thought, but depends on space available.
> 
> 
> Sent from my iPhone using Tapatalk?


It’s as close to the glass as it can but not touching it. It’s painted white so from the outside it looks like closed blinds.


----------



## mhutchins

cricket9998 said:


> After finishing this I have some thoughts. It definitely helped a lot of the higher pitched road noise but in a dead quiet room you can still hear the road. Also didn’t do anything for loud boomy exhausts. I designed it to minimize window modifications but I wish I acoustically sealed the entire window first and completely sealed the first layer of plywood. I would also add way more mass to it but I ran out of MLV. you need at least 3 layers to do the job.


Drywall is a cheap form of mass. Buy a sheet of 5/8" Type-X drywall and a tube of Green Glue. Adding a few layers of drywall with Green Glue might give you better bass isolation, depending on how the plug is constructed.

Mike


----------



## flyers10

Looking at getting an automatic door bottom. I see a few different companies selling their versions. Any recommended model and best to get one that is built into the door (routed channel) or one that gets screwed on one side of the door?


----------



## squared80

flyers10 said:


> Looking at getting an automatic door bottom. I see a few different companies selling their versions. Any recommended model and best to get one that is built into the door (routed channel) or one that gets screwed on one side of the door?


Plenty out there. Check out Trademark Soundproofing: 







Trademark Soundproofing: Automatic Door Bottoms


High quality Automatic Door Bottoms from trademark Soundproofing that will create a tight seal and soundproof the gap at the bottom of doors.



www.amazon.com


----------



## nathan_h

flyers10 said:


> Looking at getting an automatic door bottom. I see a few different companies selling their versions. Any recommended model and best to get one that is built into the door (routed channel) or one that gets screwed on one side of the door?


I've found at least three different places that offer these. Unfortunately, none seem to have objective data to assess which works best. I'm guessing that installation prowess impacts effectiveness more than the unit itself?

I would love to have a objective performance reason to consider one over another, otherwise the reason to pay more appears to be for the visual aspect/look.

Options I have found:

ONE
Zero 31 Door Gasket | TMHardware.com

















TWO
Zero International perimeter door seals automatic door bottom.

THREE
Soundproofing company.














































FOUR
PEMKOSTCSET-2D
PEMKOSTCSET-2D


----------



## DBlink

Hello,

I own a condo and am looking to soundproof my ceiling mainly from impact noise (and some minor airborne noise) coming from above. The ceiling is concrete slab with a thin coat of plaster (i.e. no joists). I figure the best way to go about this is to decouple the concrete ceiling with sound clips + hat channel, DD/GG. My main questions I would greatly appreciate some advice on are:

1. Given there are no joists on the concrete ceiling, should I attach the sound isolation clips directly to the concrete slab with tapcon screws, or should I first install a framing member like a hat channel (or similar) to the concrete slab, then attach the resilient clips with hat channel running perpendicular to the frame? The clip manufacturers all seem to indicate they can be mounted directly on the slab, but I have not really read about anyone actually doing that.

2. How much space between the concrete slab and first layer of drywall is required to achieve a decent result (I would likely add some insulation in there too). Obviously I would like to drop the ceiling as little as possible, but I still want to drop it enough to get good results. I understand the bigger the air gap, the better the results, but is there a minimum recommended gap, below which there would be little point in trying?

Looking forward to hearing what advice may be out there.

Thanks!


----------



## calincole

Quick question about DC04 clips. I am getting ready to put up walls and plan to use DC04's to attach the top plate of the new walls to the joists (walls and joists are wood framing). Basically as seen in this: http://www.soundproofingcompany.com/wp-content/media/rsic-dc04/rsic-dc04-instructions.pdf

Other than spacing them no further than 48 apart I don't see any indications on what best practices are for how close they should be and what if any weight considerations I should take into account. The bottom plate of the walls will be going into a concrete slab if it is relevant. I do plan to have some sections of the walls with built in book and media shelving, so I there will be some weight attached to the walls. 

Any tips and tricks on using these would be appreciated as well. Thanks.


----------



## nathan_h

DBlink said:


> Hello,
> 
> I own a condo and am looking to soundproof my ceiling mainly from impact noise (and some minor airborne noise) coming from above. The ceiling is concrete slab with a thin coat of plaster (i.e. no joists). I figure the best way to go about this is to decouple the concrete ceiling with sound clips + hat channel, DD/GG. My main questions I would greatly appreciate some advice on are:
> 
> 1. Given there are no joists on the concrete ceiling, should I attach the sound isolation clips directly to the concrete slab with tapcon screws, or should I first install a framing member like a hat channel (or similar) to the concrete slab, then attach the resilient clips with hat channel running perpendicular to the frame? The clip manufacturers all seem to indicate they can be mounted directly on the slab, but I have not really read about anyone actually doing that.
> 
> 2. How much space between the concrete slab and first layer of drywall is required to achieve a decent result (I would likely add some insulation in there too). Obviously I would like to drop the ceiling as little as possible, but I still want to drop it enough to get good results. I understand the bigger the air gap, the better the results, but is there a minimum recommended gap, below which there would be little point in trying?
> 
> Looking forward to hearing what advice may be out there.
> 
> Thanks!


I am not an expert in that kind of construction, so you may want to ask the SoundProofingCompany via their web site, but I would surmise that hat channels and clips, connected to the concrete, and then 3/8" drywall connect to that, would be a good start. Then GG and another layer of drywall, if you can.

The trouble could be that the sound from above may ALSO be traveling down the walls, especially if there is deep bass noise up there (like someone playing music or movies).

I would surmise that even if the air gap is just the size needed for the channels and clips, that would be a good step in the right direction. I just fear that there may be other ways that noise is going to bother you.


----------



## nathan_h

calincole said:


> Quick question about DC04 clips. I am getting ready to put up walls and plan to use DC04's to attach the top plate of the new walls to the joists (walls and joists are wood framing). Basically as seen in this: http://www.soundproofingcompany.com/wp-content/media/rsic-dc04/rsic-dc04-instructions.pdf
> 
> Other than spacing them no further than 48 apart I don't see any indications on what best practices are for how close they should be and what if any weight considerations I should take into account. The bottom plate of the walls will be going into a concrete slab if it is relevant. I do plan to have some sections of the walls with built in book and media shelving, so I there will be some weight attached to the walls.
> 
> Any tips and tricks on using these would be appreciated as well. Thanks.


They are really good at providing additional installation details for all of their products if you send them a note.


----------



## Rjloper9

calincole said:


> Quick question about DC04 clips. I am getting ready to put up walls and plan to use DC04's to attach the top plate of the new walls to the joists (walls and joists are wood framing). Basically as seen in this: http://www.soundproofingcompany.com/wp-content/media/rsic-dc04/rsic-dc04-instructions.pdf
> 
> Other than spacing them no further than 48 apart I don't see any indications on what best practices are for how close they should be and what if any weight considerations I should take into account. The bottom plate of the walls will be going into a concrete slab if it is relevant. I do plan to have some sections of the walls with built in book and media shelving, so I there will be some weight attached to the walls.
> 
> Any tips and tricks on using these would be appreciated as well. Thanks.


I used these as well. The 48” spacing and securing the bottom plate to the concrete floor do a rather surprising job of holding the wall securely in place.

If you have a pretty good idea of your room layout, it wouldn’t hurt to add an additional clip or two in that general area of the shelving in an evenly spaced fashion with the rest.


Sent from my iPhone using Tapatalk


----------



## 168gr

Quick (I hope) question -

Is there worthwhile benefit to using both MLV and sound isolation clips in the same wall or ceiling?

I figured yes, duh, of course, extra mass and isolation are great ...


However, these guys say in their FAQ



isostore said:


> SHOULD I INCLUDE MASS LOADED VINYL IN A CLIPPED ASSEMBLY?
> 
> No, not at all. Sound tests have shown adding MLV to resilient sound clip systems provides little to no gains. It may help slightly with resonance in lightweight wall assemblies. However, this can also be resolved with additional mass at a fraction of the cost.
> 
> 
> 
> 
> 
> 
> Faq
> 
> 
> 
> 
> 
> 
> 
> isostore.com


This is surprising to me. Any comments?

If using both, which would be the better arrangement:
1) wood studs, MLV, sound isolation clips + hat channel, drywall
2) wood studs, sound isolation clips + hat channel, MLV adhered to drywall


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## JebTurq

Hey everyone! I’m new here!

So first off, I hope it’s okay for me to post. You see, I am not actually building a home theater but a recording studio! I work as a voice actor and my in home studio is a big source of income for me, however, I am planning to move soon which will require the construction of a new studio. I made a lot of mistakes with my first one and I really want to do better this go around, and every time I sit down to research soundproofing I end up directed to this forum, so here we are. You all really seem to know your ****.

I have several questions and will try to be as brief and concise as possible.

1) Due to certain space constraints, I have decided sound isolation clips/furring channels to be the best choice for my project. In researching this method I came across a video made by a local soundproofing retailer that detailed such an installation. In their video, after filling the stud bays with insulation but before installing the clips, they hung a layer of 1/8” MLV from the studs. From what I’ve read, this kind of setup would create a triple leaf, however a representative from said company told me that MLV lacks the rigidity to contribute to this effect. This representative seemed quite knowledgeable and sure of himself, but as I cannot find anything else on this specific setup ANYWHERE, I thought it might be a good choice to check with some other sources. Thoughts?

*this was all typed out just as the previous post was being made - seems we have the same basic question here lol

2) I was considering perhaps using a third layer of drywall just to make sure this job was done adequately the first time. The installation guide from the aforementioned retailer has a diagram for this setup that uses channels spaced 16” vertically as opposed to 24”. However, in addition to raising the cost of the project, the same representative explained to me that increasing the number of clips might (MIGHT) in some perhaps small way actually reduce their effectiveness (this would seem to make sense intuitively but real world physics is so often counterintuitive). So my questions here are… is this correct that additional clips might actually reduce effectiveness? If so, would this reduction be outweighed by the added layer of drywall? And lastly, is the idea of adding a third layer of drywall just plain overkill? (I admittedly have a habit of overdoing things)

3) Speaking of drywall, a different representative from a different company told me that I might achieve better results from using one layer of 5/8” and one layer of 1/2” drywall as the different thicknesses are better at filtering out different frequencies. This is yet another thing I can find zero information on outside of this lone source and also the thing I am most skeptical of. Any evidence to back this up? If it matters to the question, the sheets will be separated by a layer of green glue.

4) Lastly, the room I am going to use has a window and a closet in it. I am planning to cover the window and am willing to cover the closet, but would like to avoid that if possible – the space would be useful for storage and I don’t want to deal with the hassle of uncovering it when I eventually decide to sell the house, but needless to say I also want to avoid a glaring hole in my soundproofing. Is it possible to just fill the closet with stuff or can someone suggest a less permanent, perhaps moveable barrier that would be effective? My current plan is to simply cover it and suffer the loss of space.


Again, I hope my questions are not unwelcome here. I did try my best to search for the answers both here and elsewhere on the internet, but I have thus far had no luck. Any tips and advice are welcome and I thank you all so much in advance for your knowledge and your help.


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## nathan_h

For the MLV questions, I would ask them to show you the data, ie, lab tests that demonstrate the measured efficacy of their approach. Good vendors like Soundproofingcompany will be happy to give you the test data that quantify the various approaches impact to sound transmission.

Which bring us to a third layer of drywall. I looked into this and using elastic compound between two 5/8“ layers measures better than using three layers of drywall, or mixing different thickness of drywall. All this stuff has been measured. If your vendor can’t prove their claims with data, that’s a red flag.

Finally a closet is like any wall. Treat it for isolation like all the other walls, floor and ceiling. Otherwise you have built an aquarium with hole in it.


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## mhutchins

nathan_h said:


> .
> .
> Which bring us to a third layer of drywall. I looked into this and using elastic compound between two 5/8“ layers *measures better* than using three layers of drywall, or mixing different thickness of drywall. All this stuff has been measured. If your vendor can’t prove their claims with data, that’s a red flag.
> .
> .


Hey Nathan,

I'm curious about the details when you say "..measures better.." Do you have a reference or test report that shows this? Although it is only estimated, this table from the Green Glue Company shows improvement with up to 4 layers layers of drywall per side (the full document is attached).








Generally, added mass improves the low frequency performance of most assemblies, though this improvement may not be reflected by STC numbers due to the limited frequency range that is used to determine an STC rating.

The attached document also has some good data regarding the use of MLV in wall assemblies.

Mike


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## nathan_h

Great data and this is what I mean. The improvement is tiny when you get beyond DDW+GG. And using extra drywall instead of GG (what the op described?) is a big step down.


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## JebTurq

First of all, thank you so so much for your reply. This is exactly the kind of information I've been needing.



nathan_h said:


> Which bring us to a third layer of drywall. I looked into this and using elastic compound between two 5/8“ layers measures better than using three layers of drywall, or mixing different thickness of drywall. All this stuff has been measured. If your vendor can’t prove their claims with data, that’s a red flag.


I am actually considering a triple layer of drywall with a double layer of green glue on the interior of the room. This exact setup is illustrated in the PDF mhutchins posted above but only in the cost/benefit analysis section and thus far I have been unable to find any testing data. I suspect the third layer even with the GG would provide rather diminishing returns but would be willing to take on the cost if I thought it would help to nudge my STC rating above a certain threshold.



nathan_h said:


> Finally a closet is like any wall. Treat it for isolation like all the other walls, floor and ceiling. Otherwise you have built an aquarium with hole in it.


Just to be sure I read you correctly, you are suggesting that I use isolation clips and and double drywall all around the interior of the closet as well? To be frank, the closet isn't quite large enough to warrant that kind of effort - I'd rather just seal it over, but in that case wouldn't the closet cavity itself form a triple leaf? Especially seeing as the rest of that wall makes up the closet for the adjoining bedroom.

Edit: also, mhutchins, thanks for the PDF. I will eschew the MLV. You just saved me a fair chunk of change!


----------



## nathan_h

JebTurq said:


> I suspect the third layer even with the GG would provide rather diminishing returns but would be willing to take on the cost if I thought it would help to nudge my STC rating above a certain threshold.


Worth asking the SoundProofingCompany why they don't measure a triple wall. I would guess they did informal evaluations and decided it wasn't worth it. Probably something like it increases the cost of the wall by 25% but changes the STC by only 1 or 2 db, or something? But thats just a guess. Of maybe that at the point of 3 layers on each side, the doors necessary to match that STC end up costing more than 10k dollars.... since handling doorways usually costs as much as all the other efforts in the room combined in terms of price, already.



JebTurq said:


> Just to be sure I read you correctly, you are suggesting that I use isolation clips and and double drywall all around the interior of the closet as well?


Correct. The walls of the closet would need the same level of attention as all the other walls. And it will be fiddly due the geometry of the closet.

I dont know whether walling over the closet creates triple leaf. At some point the distance is substantial enough that may not matter. If it does matter then removing the drywall in the closet before walling it off might be useful. But I would guess that the size of the closet means you don't have to worry about that. That is, many people use a airlock door setup that is no larger than a closet (often smaller) and don't seem to worry about it, but maybe that's a false equivalence. 

In the absence of scientific data, Id probably not rip out the drywall but I would stack (loosely) batts of cheap insulation in there.


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## JebTurq

I seriously cannot thank you enough for helping me. Final thoughts/questions I swear...



nathan_h said:


> Worth asking the SoundProofingCompany why they don't measure a triple wall. I would guess they did informal evaluations and decided it wasn't worth it. Probably something like it increases the cost of the wall by 25% but changes the STC by only 1 or 2 db, or something?


So I just ran across this page on the Sounproofing Company website (surprised I haven't seen it there before):

https://www.soundproofingcompany.com/soundproofing-solutions/soundproof-walls/spc-solution-1-green-glue-wall

As you can see, the triple layer of drywall has been tested, just apparently not on the resilient clips, or at least not anywhere I can find. Your guess would seem to be largely correct - the addition of a third layer of drywall only succeeded in changing the STC from 56 to 59. With this in mind, and if those results would transfer more or less 1 to 1 between methods, I don't see that a third layer would be useful to me - if the data is to be trusted then the DDW+GG combo will already put me at an STC of 67 which should be sufficient. 




nathan_h said:


> Correct. The walls of the closet would need the same level of attention as all the other walls. And it will be fiddly due the geometry of the closet.


Okay, so again referencing the above link (and also acknowledging that it clearly states that method is not advised for walls with 16" OC studs) in your opinion, would you think it sufficient to forego the clips on the interior of the closet and simply use the combination of insulation+DDW+GG with the drywall screwed directly to the studs? That combined with a good solid door maybe? Or would that still significantly weaken the soundproofing of the overall room?

I would also be curious to know your thoughts on the idea of creating a small channel between the back wall of the closet and the adjoining room through which I could pass wires. It would probably be something like 1.5" wide with those little rubber wire hider grommet thingies at both ends and a short length of drain tubing or something between them. It would be super awesome if I could keep the computer that runs my equipment in another room but I'm unsure how much a tiny breach like this would impact my soundproofing.

You are so gracious for answering my questions and I thank you immensely for your time. I swear I will leave you alone after this lol


----------



## nathan_h

JebTurq said:


> I seriously cannot thank you enough for helping me. Final thoughts/questions I swear...
> 
> 
> 
> So I just ran across this page on the Sounproofing Company website (surprised I haven't seen it there before):
> 
> https://www.soundproofingcompany.com/soundproofing-solutions/soundproof-walls/spc-solution-1-green-glue-wall
> 
> As you can see, the triple layer of drywall has been tested, just apparently not on the resilient clips, or at least not anywhere I can find. Your guess would seem to be largely correct - the addition of a third layer of drywall only succeeded in changing the STC from 56 to 59. With this in mind, and if those results would transfer more or less 1 to 1 between methods, I don't see that a third layer would be useful to me - if the data is to be trusted then the DDW+GG combo will already put me at an STC of 67 which should be sufficient.
> 
> 
> 
> 
> Okay, so again referencing the above link (and also acknowledging that it clearly states that method is not advised for walls with 16" OC studs) in your opinion, would you think it sufficient to forego the clips on the interior of the closet and simply use the combination of insulation+DDW+GG with the drywall screwed directly to the studs? That combined with a good solid door maybe? Or would that still significantly weaken the soundproofing of the overall room?
> 
> I would also be curious to know your thoughts on the idea of creating a small channel between the back wall of the closet and the adjoining room through which I could pass wires. It would probably be something like 1.5" wide with those little rubber wire hider grommet thingies at both ends and a short length of drain tubing or something between them. It would be super awesome if I could keep the computer that runs my equipment in another room but I'm unsure how much a tiny breach like this would impact my soundproofing.
> 
> You are so gracious for answering my questions and I thank you immensely for your time. I swear I will leave you alone after this lol


I'm still learning about wire chases and conduit methods. Please share what you discover.

Regarding the closest: The room will only be as good as the weakest link. In your plan, the closet would be that link (or maybe the door of course depending) so the general consensus is that you would be "throwing away" the work on the other walls if some of the walls are not done up as well. Maybe its not black and white but I think the principle is accurate. 

(That's why people spend lots of time and effort on doors, building them in special ways, making airlocks, etc: If the door isn't as good as the walls, the sound still gets in and out. All it takes is one good leak and the bucket doesn't hold water.)


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## warwwolf7

Snoochers said:


> Has anyone ever heard of or used these sound isolation clips? They're a lot cheaper than alternatives and still seem to include rubber which is nice compared to the cheaper IB-1 or the like.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Resilient Sound Insulating Drywall Clip EVOLUTION (100 pack) | eBay
> 
> 
> Find many great new & used options and get the best deals for Resilient Sound Insulating Drywall Clip EVOLUTION (100 pack) at the best online prices at eBay! Free shipping for many products!
> 
> 
> 
> www.ebay.com


Do they still exist? I can't find them anywhere. I wanted to recommend them to a friend to save cost.


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## mhutchins

JebTurq said:


> I seriously cannot thank you enough for helping me. Final thoughts/questions I swear...
> 
> So I just ran across this page on the Sounproofing Company website (surprised I haven't seen it there before):
> 
> https://www.soundproofingcompany.com/soundproofing-solutions/soundproof-walls/spc-solution-1-green-glue-wall
> 
> As you can see, the triple layer of drywall has been tested, just apparently not on the resilient clips, or at least not anywhere I can find. Your guess would seem to be largely correct - the addition of a third layer of drywall only succeeded in changing the STC from 56 to 59. With this in mind, and if those results would transfer more or less 1 to 1 between methods, I don't see that a third layer would be useful to me - if the data is to be trusted then the DDW+GG combo will already put me at an STC of 67 which should be sufficient.
> 
> Jeb, Bear in mind that STC does not test the lowest octaves and only goes down to 125Hz. Below 125Hz, sound isolation is in the "Mass Controlled region" meaning that increasing mass is the primary means to improve isolation performance. Also note that at 80Hz, the lowest frequency shown in the graphs in the document attached above, the DD+GG wall only has 23dB of sound isolation. Worse, it is trending downward at lower frequencies. Also remember that most people run their bass "hot" by 10+dB. Given all these factors, you can see why bass isolation is such a problem. What's my point? - even 2-3 dB of additional isolation below 80Hz is a significant improvement, so don't be so quick to skip that extra layer of drywall ! Lastly, read the notes in the above report - the walls with 3+ layers of drywall were limited by flanking paths in the test setup and would have performed better with a better test rig (although such a test may have required using a different test lab altogether).
> 
> Okay, so again referencing the above link (and also acknowledging that it clearly states that method is not advised for walls with 16" OC studs) in your opinion, would you think it sufficient to forego the clips on the interior of the closet and simply use the combination of insulation+DDW+GG with the drywall screwed directly to the studs? That combined with a good solid door maybe? Or would that still significantly weaken the soundproofing of the overall room?
> 
> I concur with Nathan's comments on this.
> 
> I would also be curious to know your thoughts on the idea of creating a small channel between the back wall of the closet and the adjoining room through which I could pass wires. It would probably be something like 1.5" wide with those little rubber wire hider grommet thingies at both ends and a short length of drain tubing or something between them. It would be super awesome if I could keep the computer that runs my equipment in another room but I'm unsure how much a tiny breach like this would impact my soundproofing.
> 
> You are so gracious for answering my questions and I thank you immensely for your time. I swear I will leave you alone after this lol
> 
> In regards to your wiring question, sealed conduit between rooms is fine, just make sure there is no rigid contact between the walls and the conduit. To accomplish this, drill oversize holes and fill the gap between the walls and the conduit with acoustic caulk. After you have run your wires, stuff each end of the conduit with insulation to limit acoustic noise transmission through the conduit itself. And of course, don't mix high power cables (120/240VAC or speaker cables) with low voltage analog source cables. Digital cables are more immune to noise than analog cables but can still be a source for ground loops. If you have to run power adjacent to signal cables, use rigid metal conduit if the runs are in close proximity. EMT, flexible metal conduit and plastic conduit offer virtually no shielding from radiated/induced noise and should be avoided.


Mike


----------



## MinHeadroom

Hey All,
Hopefully a quick question from friends who just bought a house abutting a skateboard park; i was flattered they thought i might know the best way to cut down on sound transmission into their house.

Relevant details:

skateboard park starts about 20 feet from their house
the MBR has a 4x5 bay window, facing said skatepark
no music from skatepark except for occasional jams, with which they are cool and supportive
skate ramps are made of WOOD (not concrete)
the most disturbing/ startling noises are the sounds of ollies and, perhaps more so, boards coming down hard on the wooden ramps, which act like drums
the sounds of people talking/ yelling are not that problematic

I know I could take my laptop and REW to the park and measure frequencies, but unfortunately for this friend, my time is super limited, and I don't necessarilly trust me and my Umik outside my theater.

Does anybody have immediate thoughts on how to cut down sound transmission through the windows, preferably something tried and tested? My friends have already beeen given a bunch of quotes form "soundproofing companies" of questionable methodology.

Any leads greatly appreciated!

-Min


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## nathan_h

Tell us more about the windows? Double pane? Triple pane? Does the budget allow replacement of the windows?


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## MinHeadroom

I am told they are definitely not triple, either single or double. They are certainly willing to spend a large amount of money on replacing the entire thing, but they are appropriately skeptical of spending a lot of money if it’s not going to give decent results. What are your thoughts?


----------



## nathan_h

Dual pane windows


MinHeadroom said:


> I am told they are definitely not triple, either single or double. They are certainly willing to spend a large amount of money on replacing the entire thing, but they are appropriately skeptical of spending a lot of money if it’s not going to give decent results. What are your thoughts?


I guess you can test whether the window is the issue by placing a LOT of thick blankets and comforters over the windows and see how the skatepark sounds. If that helps then the window is the point of incursion, which seems likely.

In such a case, even window manufacturers have ideas: https://www.jeld-wen.com/en-us/discover/reference/acoustic_performance_in_windows

You might want to contact the SoundProofingCompany for ideas as well: Contact us


----------



## warwwolf7

MinHeadroom said:


> I am told they are definitely not triple, either single or double. They are certainly willing to spend a large amount of money on replacing the entire thing, but they are appropriately skeptical of spending a lot of money if it’s not going to give decent results. What are your thoughts?


There is another option that could be considered. I have never heard good or bad things about this, so you should do your own research

Window inserts. They might work because we are not talking about low frequency, but mostly mids. 

Here is an example, but there are a lot offer on the market. I think it needs to be rather tight in order to work. I don't know how they get those measurements. 









Acoustic Window Inserts | Sound Reducing Window Inserts | Indow


Indow soundproof window inserts are a great solution that helps you avoid window replacement. Learn how they are priced and how they work.




indowwindows.com





I don't know how this would perform, but cost wise, it sure is less expensive than a new triple layer hurricane grade window.


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## Rjloper9

warwwolf7 said:


> Do they still exist? I can't find them anywhere. I wanted to recommend them to a friend to save cost.


I used these and still need about 40 more. I tried to find them everywhere to no avail.

The common ones are very steep price wise so I think I’m just gonna use the A237 clips for the back (lobby) portion of my room.


Sent from my iPhone using Tapatalk


----------



## warwwolf7

Rjloper9 said:


> I used these and still need about 40 more. I tried to find them everywhere to no avail.
> 
> The common ones are very steep price wise so I think I’m just gonna use the A237 clips for the back (lobby) portion of my room.
> 
> 
> Sent from my iPhone using Tapatalk


OK, so this might have been a one shoot deal. Too bad. It was a steal.


----------



## Rodzilla

I've tried searching this thread for an answer but just can't find what I'm looking for... 

I'm planning on a clips, channels, DD+GG install on all 4 walls and ceiling. I know the recommendation for electrical outlets on this setup is either all in room with holes acoustically sealed just for romex, or putty pads on normal electrical boxes nailed into the studs. I'm not sure my columns will be able to fit the outlets the way I'm installing them and the acoustic panels next to them, so I had a question on how to do the normal boxes with putty pads... 

Wouldn't nailing the box into the stud like normal and then affixing it to the inside of the drywall via a cut hole couple the drywall to the stud? Isn't this just as bad as an accidental drywall nail short circuiting the install of the drywall? Also, should acoustical caulk be used around the edges of the electrical box and the hole in the drywall?


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## nathan_h

Rodzilla said:


> Wouldn't nailing the box into the stud like normal and then affixing it to the inside of the drywall via a cut hole couple the drywall to the stud?


I will be interested to hear from others, but yes, I think that risk exists.

What about: Don't use new work boxes. If you have to put an electrical outlet in the wall, use an old work box, that connects only to the drywall and not to the 2x4?

That is what I would do if I wasn't able to surface mount the boxes in the room.


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## Rodzilla

nathan_h said:


> I will be interested to hear from others, but yes, I think that risk exists.
> 
> What about: Don't use new work boxes. If you have to put an electrical outlet in the wall, use an old work box, that connects only to the drywall and not to the 2x4?
> 
> That is what I would do if I wasn't able to surface mount the boxes in the room.


I thought about that but old work boxes are completely open on the back, so wouldn't that be even worse?


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## nathan_h

Rodzilla said:


> I thought about that but old work boxes are completely open on the back, so wouldn't that be even worse?


They shouldn’t.









and they should be covered with acoustic putty anyway.



Acoustical Putty Pads | Trademark Soundproofing



But as I say hopefully someone else chimes in.

In my last theater I did two walls so the 2x4 didn’t connect with the rest of the building so new work boxes were fine. In my next one, I’ll do double walls again and use surface mounted boxes inside the inner shell.

So I haven’t had to solve this in my own space.


----------



## jehlinge

nathan_h said:


> They shouldn’t.
> 
> View attachment 3245564
> 
> and they should be covered with acoustic putty anyway.
> 
> 
> 
> Acoustical Putty Pads | Trademark Soundproofing
> 
> 
> 
> But as I say hopefully someone else chimes in.
> 
> In my last theater I did two walls so the 2x4 didn’t connect with the rest of the building so new work boxes were fine. In my next one, I’ll do double walls again and use surface mounted boxes inside the inner shell.
> 
> So I haven’t had to solve this in my own space.


I was thinking of doing the same thing with the old work boxes. At least in my google searches, the process for adding the putty pads have the exterior of the boxes covered completely with the pads (top, bottom, sides, back). Seems like it would be difficult not to disturb the putty on the exterior of the box while getting the old work box put into the drywall with an appropriate sized/cut rectangular hole??


----------



## jehlinge

Question for the experts on doing duct mufflers for ventilation in my soon to be built theater. The theater will be climate controlled with an independent mini split (i.e. no air exchange for heating/cooling from the rest of the house HVAC). I plan on adding some sort of forced air exchange to the theater for ventilation (both intake and exhaust). I ran across this guide from soundproofingcompany.com:










Since I have 8 foot ceilings, I really don't want to put soffits in. Is it ok to essentially turn this around? I am thinking about building the duct muffler (the soffit in their picture) and then placing that duct muffler between the ceiling/floor joists in the ceiling above. Of course, I would attach that muffler/box to the back side of the furring channels and not the ceiling/floor joists at the appropriate depth so that the 2 layers of ceiling drywall can be sealed against it.

Thoughts?


----------



## nathan_h

jehlinge said:


> Question for the experts on doing duct mufflers for ventilation in my soon to be built theater. The theater will be climate controlled with an independent mini split (i.e. no air exchange for heating/cooling from the rest of the house HVAC). I plan on adding some sort of forced air exchange to the theater for ventilation (both intake and exhaust). I ran across this guide from soundproofingcompany.com:
> 
> View attachment 3245571
> 
> 
> Since I have 8 foot ceilings, I really don't want to put soffits in. Is it ok to essentially turn this around? I am thinking about building the duct muffler (the soffit in their picture) and then placing that duct muffler between the ceiling/floor joists in the ceiling above. Of course, I would attach that muffler/box to the back side of the furring channels and not the ceiling/floor joists at the appropriate depth so that the 2 layers of ceiling drywall can be sealed against it.
> 
> Thoughts?


I was looking at doing something similar, but then learned that if I do a ducted mini split, instead of a ductless one, it is quieter in the room (since the blower is outside the room) and some models offer a fresh air intake/exchange, obviating the need for a separate air exchange. (Caveat: I haven't actually done this yet, its just my current plan for the space I am working on.)


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## jehlinge

nathan_h said:


> I was looking at doing something similar, but then learned that if I do a ducted mini split, instead of a ductless one, it is quieter in the room (since the blower is outside the room) and some models offer a fresh air intake/exchange, obviating the need for a separate air exchange. (Caveat: I haven't actually done this yet, its just my current plan for the space I am working on.)


Yeah that ship has sailed already. I have a ductless minisplit sitting in the garage already. A ducted would have been nice, but no where to put it without tearing apart the rest of my basement. It's all about compromises I guess.


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## nathan_h

Makes sense and not a deal breaker. Just thought I would mention it.

I would assume it an go in the joists.

The other thought is that Soundproofing company has plans/examples of the air exchange (dead vent) that is completely outside the theater space.


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## Jesse Christman

Hi all, I've read about 500 posts of this thread and haven't come across an answer yet, but now I've run out of time and need to order my soundproofing supplies. 

I'm building a recording studio in my basement with a control room and a vocal booth. One wall of the outer control room is shared with a home theater area and another wall is shared with the mechanical room. I am just now finishing up insulation (Rockwool Safe n Sound) and am having a debate on whether to use clips/channels for the walls. I absolutely will on the ceiling due to foot fall noise, but I'm concerned about outlets and boxes not being able to be stubbed out far enough for clips/channels, plus the existing door jamb will need extended significantly. My outer wall and ceiling construction is planned as follows:

Existing DW | 2x4 Studs 16" O.C. (existing) | Insulation | 1lb mass loaded vinyl | Whisper Clips / 20ga hat channels | 5/8" DW | GG | 5/8" DW | Then acoustical treatments as needed with Rockwool

Unfortunately, I am tight on space (the whole room is only 11.5 x 14.5 feet) and with the above-mentioned concerns with electrical boxes and door jamb, I'm not sure I should use the clips/channels on the walls. I am not looking to build an anechoic chamber, just need to keep my music contained and the theater sound out of my recordings as much as possible. Will the clips/channels on the walls provide that much of an improvement over GG + double DW + MLV + Rockwool?


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## squared80

If you want it done right, and effectively, use hat channels and clips. Simple. All depends on how much time/money you want to put into doing it "right" or just "good enough". My situation directed me to the latter, and that's perfectly fine with me.


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## Jesse Christman

Are you happy with how your build turned out? Subjectively, how much of a sound reduction did you experience after doing double DW and GG? I'm wondering how much of a difference MLV will make as well.


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## nathan_h

Jesse Christman said:


> Will the clips/channels on the walls provide that much of an improvement over GG + double DW + MLV + Rockwool?


Yes assuming you don’t have other flanking paths.

For example, if the ceiling is decoupled but the walls are not, then the bass will travel through the walls to other places in the building. Or, if the ceiling and walls are decoupled but the door is not taken care of, the sound will escape through the door (and vice versa). Or if the ceiling, and walls are decoupled, and the door is designed correctly, but the floor is a regular floor on joists, the bass will travel in and out via the floor vibrating.

Think of it this way, the weakest link will be the level of isolation you achieve, so pay attention the that. 

So should you worry about the walls? Maybe but perhaps only if you do the floor ceiling and door correctly. Based on experience, the door will be the place that undermines all the other effort.


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## Jesse Christman

nathan_h said:


> Yes assuming you don’t have other flanking paths.
> 
> For example, if the ceiling is decoupled but the walls are not, then the bass will travel through the walls to other places in the building.


Thank you. So clips/channels (and other physical decoupling methods) are mostly just used for isolation of bass frequencies?


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## nathan_h

Bass is the hardest to contain and requires physical decoupling. Higher frequencies also benefit a lot, perhaps most, from physical decoupling but it’s the “only” way to contain bass.


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## reed_wright

Question for you guys on the "weakest link" thing about soundproofing. The best room in the house for an HT is our garage, but I am concerned about disturbing the neighbors (nearest ones being 15' from the garage). Our downstairs bonus room is actually less ideal, but maybe still worth considering if it offers significant soundproofing advantages. Our two-story house is built on a property that slopes downward in the direction of the back yard; the front door opens to the top story. The bottom story is built into that hill, so one side is completely underground. There is also an unfinished basement on one side of the room. So if you were sitting in it and looking at the hypothetical screen, it is enclosed by basement at the rear, entirely underground on the left side, solid stucco and drywall behind the screen.

On the right hand wall, there is a window in the front and a sliding glass door in the back. Obviously these would need to be treated somehow. This sliding glass door leads into the backyard which is 0.3 acres or so in size. Neighbors in all directions have similar size yards.

How significant are these in terms of sound reduction to neighbors? Though we could do specific treatments for the windows and sliding glass door, I imagine there will still be some pretty weak links in the chain. Intuitively it sure seems like the natural soundproofing of this room is pretty strong, but some of this stuff is pretty counterintuitive.


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## nathan_h

When I buildt a theate in a garage I build a room inside the garage, and the theater in that room. Since none of the walls or ceiling of the new room touched the garage walls or a garage ceiling, and I following the guidelines about well sealed doors, etc, it was possible to hear muffled sound outdoors but little else when the theater was going. It was quieter than my neighbor talking on the phone in her backyard.


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## Rjloper9

If I’m boxing around ductwork in my room and then fill that “soffit” with insulation on either side of the ductwork and it comes into contact with the floor joists will it ruin my decoupled ceiling?


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## nathan_h

Rjloper9 said:


> and it comes into contact


Depends on what “it” refers to.

But the concept may guide you: if anything rigid in the room touches anything rigid outside the room, that’s an issue.

So if the duct framing is in the room …and that is what you mean by “it”…..and it touches the floor joists outside the room then yes that is an issue.


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## gumbygto

Jesse Christman said:


> My outer wall and ceiling construction is planned as follows:
> 
> Existing DW | 2x4 Studs 16" O.C. (existing) | Insulation | 1lb mass loaded vinyl | Whisper Clips / 20ga hat channels | 5/8" DW | GG | 5/8" DW | Then acoustical treatments as needed with Rockwool


I thought the use of insulation and clips/hat channels for the DW eliminated the need for the MLV? Its acceptable practice to do both??

Our basement theater is a dedicated room with 2 of the 4 walls that are interior facing. I have to do the ceiling too. Most of the time its going to be the wife and I or both of us and friends. I'm looking to get the best STC I can without doing a room within a room - our theater is only 12-3 wide (stud to stud) which to me is a little narrow but its what we have to work with.

If I can do a single layer of Quietrock on hat channels with Rockwool and MLV, would that be the same as double drywall on hat channels and rockwool insulation? 

Thanks.


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## cricket9998

gumbygto said:


> I thought the use of insulation and clips/hat channels for the DW eliminated the need for the MLV? Its acceptable practice to do both??
> 
> Our basement theater is a dedicated room with 2 of the 4 walls that are interior facing. I have to do the ceiling too. Most of the time its going to be the wife and I or both of us and friends. I'm looking to get the best STC I can without doing a room within a room - our theater is only 12-3 wide (stud to stud) which to me is a little enarro but its what we have to work with.
> 
> If I can do a single layer of Quietrock on hat channels with Rockwool and MLV, would that be the same as double drywall on hat channels and rockwool insulation?
> 
> Thanks.


No double drywall with GG is one of the highest stc ratings and they have data to back it up. MLV will help but it’s not as effective. Of course doing both is best… 

However your system would be cheaper and likely almost as effective.


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## Rjloper9

nathan_h said:


> Depends on what “it” refers to.
> 
> But the concept may guide you: if anything rigid in the room touches anything rigid outside the room, that’s an issue.
> 
> So if the duct framing is in the room …and that is what you mean by “it”…..and it touches the floor joists outside the room then yes that is an issue.


“It” would be the batt insulation that I planned on stuffing (not compressing) the soffit with.


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## nathan_h

As far as I know, the batt insulation, left loose and not compressed, is fine to bridge between the two different spaces.


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## jrref

gumbygto said:


> I thought the use of insulation and clips/hat channels for the DW eliminated the need for the MLV? Its acceptable practice to do both??
> 
> Our basement theater is a dedicated room with 2 of the 4 walls that are interior facing. I have to do the ceiling too. Most of the time its going to be the wife and I or both of us and friends. I'm looking to get the best STC I can without doing a room within a room - our theater is only 12-3 wide (stud to stud) which to me is a little narrow but its what we have to work with.
> 
> If I can do a single layer of Quietrock on hat channels with Rockwool and MLV, would that be the same as double drywall on hat channels and rockwool insulation?
> 
> Thanks.


Quietrock and double sheetrock with GG is very close. Quietrock is easier to use but more expensive. Just a tradeoff.


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## ambesolman

It seems to just be a Canadian product, but has anyone used sonopan? I’ve recently watched a few videos of it being used and one builder said he prefers it to ddgg and thought it worked just as well without the mess. It doesn’t seem to have nearly the mass of drywall, but could easily be used in backer boxes too. Can’t seem to find any measurements comparing ddgg vs drywall+sonopan either.


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## mhutchins

Skip the Sonopan and go for the more massive drywall. Double drywall + Green Glue will give you superior results.

Mike


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## warwwolf7

mhutchins said:


> Skip the Sonopan and go for the more massive drywall. Double drywall + Green Glue will give you superior results.
> 
> Mike


2nd layer of drywall will cost less than sonopan for a better result


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## ambesolman

Kind of a moot point anyway since it’s not available in the states, but I appreciate the confirmation. It’s a shame we don’t have something else similarly simple that could beneficial in other areas of construction.

I’m meeting with my builder next week to finally get the ball rolling in our basement HT. I’m planning on the usual best methods mentioned throughout avs for the build out like room within a room, clips and channels, ddgg, backer boxes for speakers and lights, etc. I’ll be getting another quote to replace the three support poles with a steel beam as well, but still suspect that will be out of my price range. If so, then I’ll just use the room as is.

In the spirit of soundproofing, I’m thinking that constructing the rear wall just before the sump pump, parallel to the stairs. I’ll lose a couple feet on the length of the room, but I won’t have to figure out how to retain access to it while keeping the soundproof shell intact. I’ll also break up the hearth of the fireplace and seal it up to frame closer to the outer wall.

If the poles stay, and I don’t want to see them, could I frame a wall to incorporate them by leaving spaces in the wall’s bottom plate for the poles since I’ll have clips and channels to support the ddgg that will helps the wall together? Effectively having separate framed walls between the poles tied together with the drywall if that makes sense.

Here’s a sketch of the room…











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## cricket9998

ambesolman said:


> Kind of a moot point anyway since it’s not available in the states, but I appreciate the confirmation. It’s a shame we don’t have something else similarly simple that could beneficial in other areas of construction.
> 
> I’m meeting with my builder next week to finally get the ball rolling in our basement HT. I’m planning on the usual best methods mentioned throughout avs for the build out like room within a room, clips and channels, ddgg, backer boxes for speakers and lights, etc. I’ll be getting another quote to replace the three support poles with a steel beam as well, but still suspect that will be out of my price range. If so, then I’ll just use the room as is.
> 
> In the spirit of soundproofing, I’m thinking that constructing the rear wall just before the sump pump, parallel to the stairs. I’ll lose a couple feet on the length of the room, but I won’t have to figure out how to retain access to it while keeping the soundproof shell intact. I’ll also break up the hearth of the fireplace and seal it up to frame closer to the outer wall.
> 
> If the poles stay, and I don’t want to see them, could I frame a wall to incorporate them by leaving spaces in the wall’s bottom plate for the poles since I’ll have clips and channels to support the ddgg that will helps the wall together? Effectively having separate framed walls between the poles tied together with the drywall if that makes sense.
> 
> Here’s a sketch of the room…
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk?


There is an American distributor but they “don’t sell to residential customers”.


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## DaveN

My HT has 2 glass insert double doors that transmit quite a lot of sound. I am thinking of adding another set of doors behind the original doors using MP Doors 72 in. x 80 in. Left-Hand Low E White Finished Composite Shaker Gliding Double Prehung Patio Door with Nickel Handle G60LLCG20122NN. The sliding door appears quite stout. Would these two sets of doors with air gap between solve my problem?


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## nathan_h

Probably not, though the idea of creating an air lock kind of setup, with two sets of doors separated by an air gap, is a good one.

You don't mention what the rest of the room's isolation features are, nor how much reduction is considered enough in your case. Typically, the recommendation is


A door should be a 1 3/4 inch thick solid core, as in “solid core 1 ¾" (commercial thickness) flush/slab interior doors” -- not pocket doors but hinged.
Sealing: Around the edges of the door use rubber seals. On the bottom of the door, use a mechanical seal that will press down on the floor when the door is closed, like excellent weather sealing.
Soundproofingcompany has some good guides, and a few products, that would be worth considering. And useful advice like:


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## DaveN

nathan_h said:


> Probably not, though the idea of creating an air lock kind of setup, with two sets of doors separated by an air gap, is a good one.
> 
> You don't mention what the rest of the room's isolation features are, nor how much reduction is considered enough in your case. Typically, the recommendation is
> 
> 
> A door should be a 1 3/4 inch thick solid core, as in “solid core 1 ¾" (commercial thickness) flush/slab interior doors” -- not pocket doors but hinged.
> Sealing: Around the edges of the door use rubber seals. On the bottom of the door, use a mechanical seal that will press down on the floor when the door is closed, like excellent weather sealing.
> Soundproofingcompany has some good guides, and a few products, that would be worth considering. And useful advice like:


That is good info, thanks. I am limited by townhome from using solid doors that don't match others. The second set of doors would be installed with no gaps at edges and the rubber seals between the doors appear to be very solid. I'm looking to prevent any traffic noise from intruding.


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## squared80

What is a good threshold to use for an automatic one, and for a *carpet to carpet* transition?


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## nathan_h

You have carpet in the door jamb area? Can you place a plank/wood/metal at the base of the jamb instead? Carpet directly under the closed door is going to be porous no matter what sealing you do down there.


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## flyers10

If get a solid core door but don't do an automatic bottom, is there a cheaper alternative to help block light and some sound? Or just leave door as is?

Also, if the wall where that door is going could have some basic insulation put in, is it a waste of money or noticeable help with the solid door? (half wall will be open when installing door but other half won't)


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## nathan_h

Weather stripping can help.

Insulation loosely added to a wall is useful but won’t make a big difference…..though it does help a bit.


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## mhutchins

flyers10 said:


> If get a solid core door but don't do an automatic bottom, is there a cheaper alternative to help block light and some sound?
> .
> .


You can use a raised threshold that seals against the bottom (lower face) of the door.

Mike


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## nathan_h

That's true. At that point, I might just buy a pre-hung solid core exterior door, which already has that built in.

I guess we should note that you should make sure your room has a return air vent, because many domestic rooms rely on the gap under the door as a return air vent pathway, and you are sealing that up....


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## marjen

So I have a question. I have a first floor theater. The main wall that connects to a hall is actually double framed, 2 2x4 walls with about 1/2“ in between as a gap. Its filled with About 8” of roxul. One Other wall that is part exterior part interior is 2x6 with fix of spray foam and 6” roxul. Other interior wall is standard 2x4. The joists are I joists. The interior of the theater is 5/8 single layer drywall. The backside of that is 1/2” drywall.

Right now the biggest sound leaker is the doorway. Its 36” opening with a sliding barn door. I am looking to try and work in a real door. Its just the location of the door is in a really bad spot so a swinging door just isn’t going to work well which is why I still dont have one. But assuming I deal with that and put in a solid door, maybe even exterior door, is there any practical gain to be made by adding another layer of drywall with gg between? I guess the thing I am wondering is if the bass and low frequencies are just going to travel via the floor since this is not a basement with concrete floor And really negate any positives i might gain by adding the additional layer of drywall thus making it not worth spending the money? Thanks.

Oh would something like the SVS soundpath subwoofer feet actually do anything do decouple the subs? Wondering if they are more snake oil than viable solution.


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## nathan_h

Isolation feet work. They don't eliminate sound transmission, and if you want to test for cheap, you can pick up the isolation pads made for industrial equipment like clothes washers, for $3 or $4 each and see if that helps a bit.

But yes, even after solving your door, the floor will continue to be an issue. 

But solving your door may help more than you think.

Note that "solid core" is half the battle. The other half is "air sealed" like with weather stripping.

Once you've got the door done, you can decide where the next weak link is and whether you want to address it. It might be the floor, and the wall, that you specify. It might be the ceiling. It might be the HVAC ductwork.

(An iterative piece meal process is not the best from a cost and effectiveness standpoint, but I infer that you don't have the goal of "perfection" nor the interest in spending that much time and money doing a huge remodel. Which is fair and where I am at with my temp room as well.)


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## marjen

nathan_h said:


> Isolation feet work. They don't eliminate sound transmission, and if you want to test for cheap, you can pick up the isolation pads made for industrial equipment like clothes washers, for $3 or $4 each and see if that helps a bit.
> 
> But yes, even after solving your door, the floor will continue to be an issue.
> 
> But solving your door may help more than you think.
> 
> Note that "solid core" is half the battle. The other half is "air sealed" like with weather stripping.
> 
> Once you've got the door done, you can decide where the next weak link is and whether you want to address it. It might be the floor, and the wall, that you specify. It might be the ceiling. It might be the HVAC ductwork.
> 
> (An iterative piece meal process is not the best from a cost and effectiveness standpoint, but I infer that you don't have the goal of "perfection" nor the interest in spending that much time and money doing a huge remodel. Which is fair and where I am at with my temp room as well.)


I agree starting with the door seems to make the most sense and see where I stand.

I was thinking of making a door out of MDF. Maybe 3/4MDF + fill with 2” of roxul or maybe and inch of sand + another 3/4 layer of MDF. Is doing something like that going to give me a much better STC level that just buying a solid cord door? I know either way the seals are going to be the biggest issue but just looking at the door construction itself as well.


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## nathan_h

marjen said:


> I agree starting with the door seems to make the most sense and see where I stand.
> 
> I was thinking of making a door out of MDF. Maybe 3/4MDF + fill with 2” of roxul or maybe and inch of sand + another 3/4 layer of MDF. Is doing something like that going to give me a much better STC level that just buying a solid cord door? I know either way the seals are going to be the biggest issue but just looking at the door construction itself as well.


I don't think sand or Roxul make much sense. Maybe a thick sandwich of layers of MDF with green glue between each layer is useful. From what I have seen, it almost seems like the heavier the door, the better, but the weak link will be the seals and the framing directly around the door. Soundproofing company has good detailed white papers on how to optimize the door and doorway's performance. 

Rather than building a custom door, I would build an airlock, but I understand that you may not have that much space....and that may be overkill based on other factors in the room.


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## Ed Mullen

marjen said:


> So I have a question. I have a first floor theater. The main wall that connects to a hall is actually double framed, 2 2x4 walls with about 1/2“ in between as a gap. Its filled with About 8” of roxul. One Other wall that is part exterior part interior is 2x6 with fix of spray foam and 6” roxul. Other interior wall is standard 2x4. The joists are I joists. The interior of the theater is 5/8 single layer drywall. The backside of that is 1/2” drywall.
> 
> Right now the biggest sound leaker is the doorway. Its 36” opening with a sliding barn door. I am looking to try and work in a real door. Its just the location of the door is in a really bad spot so a swinging door just isn’t going to work well which is why I still dont have one. But assuming I deal with that and put in a solid door, maybe even exterior door, is there any practical gain to be made by adding another layer of drywall with gg between? I guess the thing I am wondering is if the bass and low frequencies are just going to travel via the floor since this is not a basement with concrete floor And really negate any positives i might gain by adding the additional layer of drywall thus making it not worth spending the money? Thanks.
> 
> Oh would something like the SVS SoundPath subwoofer feet actually do anything do decouple the subs? Wondering if they are more snake oil than viable solution.


The SoundPath Subwoofer Isolation feet will reduce the amount of mechanical energy transmitted to the flooring surface. This can in-turn reduce floor boom/resonance and buzz/rattle which is excited by mechanical energy. The SoundPath Isolation feet will not reduce the acoustic output of the subwoofer, nor will they reduce any buzz/rattle which is excited by acoustic sound pressure. 

Deep bass frequencies are notoriously good at passing through walls and other barriers, so installing a stronger/denser door will improve its acoustic transmission/reflectivity to more closely match that of your interior/exterior walls.


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## clipghost

Would appreciate any guidance in my thread here, thank you so much! - Insulation and Drywall help wanted for in wall speakers


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## ambesolman

I had a thought that stacked, dark colored rock on the walls of the theater I want to build would look nice. The idea is that I’d get an acoustic treatment plan for the room, know where the panels would need to be, mark them out and then rock around the panels. This would recess the panels a bit into the wall and potentially give it a cleaner look and save me some space. It would also substantially add to the weight of the walls which I’d think would help with the sound isolation.

I’m planning on a room within a room in the corner of my basement. The interior walls (rear and 1 side wall) would be dbl stud. The front and other side wall would be standard 2x4 1” off the foundation walls. The rock would only be on the rear and side walls up to within a few feet of the screen since I plan to black out the front area with velvet.

Since the rock would need to be installed on cement board, could I use that as my second layer over a first layer of osb? This would leave the front wall and ceiling with ddgg on clips and channels.

Also, would I need clips and channels on the front wall if it’s against a foundation wall?


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## nathan_h

If there is a solid path between the theater and any wall, floor, ceiling then sound (especially bass) will travel that path to escape.

The one time I was told by an expert (ie, Ted at the SoundProofingCompany) that this doesn't apply was when the floor is a concrete slab. In that case he said building a floating floor wasn't required for sound isolation. 



ambesolman said:


> I’m planning on a room within a room in the corner of my basement. The interior walls (rear and 1 side wall) would be dbl stud. The front and other side wall would be standard 2x4 1” off the foundation walls.


You dont mention the ceiling but this is important too. It should not touch the joists above (except via isolation devices if you have to go that way) but would ideally sit on those decoupled walls, imo.



ambesolman said:


> The idea is that I’d get an acoustic treatment plan for the room, know where the panels would need to be, mark them out and then rock around the panels.


Keep in mind that a plan is an educated guess, and that leaving some flexibility for adjustment once the room is built and measured is helpful, if possible.


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## ChadCT73

Hey all - I'm curious if someone can share some expertise with me. I've poured through this thread over and over and still coming up with some questions re: soundproofing.

My existing space (15x24x9 basement room) has existing drywall on the walls, and open ceiling. Based on the research I have done, it seems best to rip out the existing drywall (two sides have insulation, two do not). My confusion starts when I'm trying to determine various options in rebuilding.

My current plan is to add staggered studs on the walls all around, fill with pink fluffy (based on Steven Smith suggesting there is no real benefit to rock wool over pink fluffy), put a layer of Homosote 440 Sound Barrier, then a layer of 5/8 drywall attached to the sound barrier NOT the studs behind it....

Of course I can't just let it go... and I'm wondering - should I add furring channel behind the soundboard? Will it impact things that much?

On the ceiling I'm pretty confident I'll add the furring channel like it shows here, but - do I need to do it on the walls, too? Is it overkill??

The two wall assemblies below have a 2 STC difference - both without using channel or channel & clips. Can an average person really tell a 2 STC difference? And, if I add channel to the walls, how much benefit is there???


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## nathan_h

ChadCT73 said:


> it seems best to rip out the existing drywall


Yep. And the ceiling.



ChadCT73 said:


> Homosote 440 Sound Barrier


Never heard of it, but from your photos it looks like Green Glue works better, and GG is what most of the pros seem to use.



ChadCT73 said:


> should I add furring channel behind the soundboard?


Some people add things like hat channel, furring, etc, but usually that is what they use when they *can't* do a decoupled wall with a new set of studs that don't touch the old studs. 

I suppose doing both is useful, and I'll bet the SoundProofingCompany has it in one of their white papers on their web site. (May have to ask them.)



ChadCT73 said:


> Can an average person really tell a 2 STC difference


Nope. And chances are good your door (unless they are double, airlock style, solid core, weather sealed doors), maybe your HVAC, and possibly your floor will have a lower STC value than the walls and ceiling, anyway.


----------



## plasmasomanychoices

I'm not looking to build a specialized theater, but was hoping people here might be able to help.

I'm building a new home and I'm curious as to what would be the best approach for general sound isolation between bedrooms/bathrooms and living areas because we'll have 6 people living in 2500-3400 sqft. Since the living/kitchen/dining room don't have doors, it's probably more about reducing the levels of sound exiting bathrooms and entering bedrooms.

There will be one bedroom on the first floor with the living areas and the rest will be upstairs.

From what I have read, double stud walls with double drywall and green glue may be the most economical choice for a general approach because the clips and associated labor are expensive. However I'm wondering if this is still true with the crazy lumber prices we've had in the last two years.

Double stud walls do seem appealing just from the perspective that a builder is not likely to get too confused by them.


----------



## nathan_h

plasmasomanychoices said:


> I'm not looking to build a specialized theater, but was hoping people here might be able to help.
> 
> I'm building a new home and I'm curious as to what would be the best approach for general sound isolation between bedrooms/bathrooms and living areas because we'll have 6 people living in 2500-3400 sqft. Since the living/kitchen/dining room don't have doors, it's probably more about reducing the levels of sound exiting bathrooms and entering bedrooms.
> 
> There will be one bedroom on the first floor with the living areas and the rest will be upstairs.
> 
> From what I have read, double stud walls with double drywall and green glue may be the most economical choice for a general approach because the clips and associated labor are expensive. However I'm wondering if this is still true with the crazy lumber prices we've had in the last two years.
> 
> Double stud walls do seem appealing just from the perspective that a builder is not likely to get too confused by them.


Double stud walls (or isolation clips and channels, etc) may be overkill or not effective on their own with out doing lots of other work, and may not be what your use case requires.*

Since you are specifying for a builder, I would explore the following options with them:

1). Using "party walls" for the bedrooms and bathrooms. I think the term comes from "partition wall" and not the other meaning of "party" but it's an easy way to think about it:









2. Staggered stud walls. These are not as thick, expensive, or complex as dual stud walls -- nor are they quite as effective -- but they might be easier to achieve and they can help a lot.


*Whatever you do:

1. Please fill all those internal walls with fluffy insulation batts. It doesn't stop bass, but it really helps with conversation level noise, in my experience.
2. Please use solid core doors, not the flimsy hollow ones that are standard issue, for all the doors in the house. 
3. Make sure every bedroom has an HVAC air return duct. (In a high end theater, the duct can be a problem for sound transmission, but in a normal room, a duct mostly means you don't need to leave the door ajar in order to have good HVAC performance in the room.)*


-----
*Double stud walls are great. You'll have to do the math to determine costs of labor versus materials. But in general, people choose clips and channels etc because it uses less space so you lose less square footage, not because it is necessarily cheaper. *That being said, a double stud wall for a room with a normal door doesn't do much. Its like a fish tank with hole in it. *


----------



## plasmasomanychoices

nathan_h said:


> 1). Using "party walls" for the bedrooms and bathrooms. I think the term comes from "partition wall" and not the other meaning of "party" but it's an easy way to think about it:


Gypsum Fire-Wall Construction in Townhouses I think that's more about fire safety and often entails the undesirable triple leaf design.



nathan_h said:


> 2. Staggered stud walls. These are not as thick, expensive, or complex as dual stud walls -- nor are they quite as effective -- but they might be easier to achieve and they can help a lot.


We thought about this but it seems they are not recommended by some people? "Staggered Stud Walls: Acoustical Reference Only. We do not suggest installing Staggered stud walls due to the shared top and bottom plate. This causes problems in acoustic performance." from soundproofingcompany.com

Since about a third of the second floor will have an ADU we were thinking of going whole hog to get more separation between the first floor living room / one of the bedrooms / one of the bathrooms and the ADU above.



nathan_h said:


> 1. Please fill all those internal walls with fluffy insulation batts. It doesn't stop bass, but it really helps with conversation level noise, in my experience.


I think this will definitely be the bare minimum, especially since it's something we can theoretically do ourselves once the framing is done.



nathan_h said:


> *2. Please use solid core doors, not the flimsy hollow ones that are standard issue, for all the doors in the house.
> 3. Make sure every bedroom has an HVAC air return duct. (In a high end theater, the duct can be a problem for sound transmission, but in a normal room, a duct mostly means you don't need to leave the door ajar in order to have good HVAC performance in the room.)*


Yes we were definitely planning on these. It will have an ERV so every bedroom (and the living room) will have supply ducts. Bathrooms and the kitchen will have exhaust ducts.


----------



## nathan_h

Sure, if you can do double stud walls and decoupled ceiling, that is great. I misunderstood your post and thought you were looking for cheaper ways to attenuate sound.

The open hallways to the bedrooms will be a weak link that is hard to assess. It might end up being a like a bucket with a nice hole (hallways) in it. 

I’ve not lived with an ERV, but I’ve learned the hard way that every room should have a supply duct *and* a return duct. Cheap buildings simply leave a two inch gap under the door and pretend that is adequate for a return path instead of installing an air return duct in each bedroom. A gap under the door is not enough, and in your case a gap will allow excessive sound transmission.


----------



## mhutchins

An Energy Recovery Ventilator (“ERV”) is not a substitute for a return air duct. An ERV is a means to bring fresh air into a room or home while conserving some of the energy expended by the HVAC system to treat the indoor air. An ERV will attempt to match the incoming air temperature and humidity with the outgoing air. For example, here in Austin TX, that would mean cooling and dehumidifying the incoming air. I have read that many of the better ERVs can achieve 40-65% energy recovery, depending on the indoor vs. outdoor conditions.

Mike


----------



## mhutchins

Repeat post…


----------



## nathan_h

hopefully @plasmasomanychoices is still reading this to see that


----------



## batlin27

Have an issue with my build and would like to open to broader audience. Cross posting from my build thread
Basically, do I omit the serenity Mat and 3/4OSB sub floor to bring fix this issue (and save some cash at the same time) or do I lower my riser by a half inch by using a 2x4 on end and a 2x4 on its side... 

I will be doing double stud walls with .5-1" airgap and double 5/8 dry wall. My room shares the screen wall with the exterior, one side is garage, other side is a closet and the rear wall shared with pantry. I am not going full Monty on sound proofing, but just trying to add some to help reduce sound across the house. 

----

Slab was poured on Friday and I went out today to take a look and do some measurements. I am a little upset because although I requested an 8" slab drop, the actual slab drop is 7 3/8" which really screws with a lot of things. I am up for some suggestions here
Originally I had planned











Which would have been flush with the rest of the house and allow for a seamless transition between theater and hallway. So now I will have a 5/8" higher theater than the rest of the house. Only thing I can think of is rather than using a 2x6 on end (5.5" nominal) I will need to use a 2x4 on end (3.5") + a 2x4 on its side (1.5") to get my self to a 7.5" drop.

Blue pipes are conduit to AV closet to be able to run usb cables, calibration microphone etc. and of course they are sticking into the room a little more than I would like....

Any thoughts?
Other than that, the slab looks great


----------



## plasmasomanychoices

nathan_h said:


> hopefully @plasmasomanychoices is still reading this to see that


Each bedroom will also have return ducts, yes.


----------



## nathan_h

I do not know all the details of your build but Ted at sound proofing company told me that if my floor was on a slab, I didn’t need to make it a floating floor to isolate it from the rest of the structure.

There is still the need to not connect any piece of the room with the rest of the structure, other than I suppose the shared concrete.



batlin27 said:


> Have an issue with my build and would like to open to broader audience. Cross posting from my build thread
> Basically, do I omit the serenity Mat and 3/4OSB sub floor to bring fix this issue (and save some cash at the same time) or do I lower my riser by a half inch by using a 2x4 on end and a 2x4 on its side...
> 
> I will be doing double stud walls with .5-1" airgap and double 5/8 dry wall. My room shares the screen wall with the exterior, one side is garage, other side is a closet and the rear wall shared with pantry. I am not going full Monty on sound proofing, but just trying to add some to help reduce sound across the house.
> 
> ----
> 
> Slab was poured on Friday and I went out today to take a look and do some measurements. I am a little upset because although I requested an 8" slab drop, the actual slab drop is 7 3/8" which really screws with a lot of things. I am up for some suggestions here
> Originally I had planned
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Which would have been flush with the rest of the house and allow for a seamless transition between theater and hallway. So now I will have a 5/8" higher theater than the rest of the house. Only thing I can think of is rather than using a 2x6 on end (5.5" nominal) I will need to use a 2x4 on end (3.5") + a 2x4 on its side (1.5") to get my self to a 7.5" drop.
> 
> Blue pipes are conduit to AV closet to be able to run usb cables, calibration microphone etc. and of course they are sticking into the room a little more than I would like....
> 
> Any thoughts?
> Other than that, the slab looks great


----------



## batlin27

nathan_h said:


> I do not know all the details of your build but Todd at sound proofing company told me that if my floor was on a slab, I didn’t need to make it a floating floor to isolate it from the rest of the structure.


Awesome, thank you!


----------



## batlin27

nathan_h said:


> I do not know all the details of your build but Ted at sound proofing company told me that if my floor was on a slab, I didn’t need to make it a floating floor to isolate it from the rest of the structure.
> 
> There is still the need to not connect any piece of the room with the rest of the structure, other than I suppose the shared concrete.


If I omit the floating floor, should I put anything under the riser in-between the wood and the slab?


----------



## nathan_h

I am not a construction expert but assume a vapor barrier at a minimum would be required.


----------



## jaypapek

Hi soundproofing experts,

I have a box of RSIC-1 sound clips, and a low ceiling. Before I got around to installing them, I discovered the solution here for a low-profile installation: Low ceilings & RSIC. In brief, the idea is to mount your hat channel parallel to each joist with the drywall-receiving surface sitting just a little below the joist. This seems like a great approach.

Has anyone discovered any drawbacks to this strategy? Everywhere I look says to run hat channel perpendicular rather than parallel to joists, but no one ever explains why.

Also, does anyone know if you can buy just the extensions for these clips, or do I have to sell my existing clips and buy the new ones? If finding extensions to add to my clips is not possible, what if I just installed each RSIC-1 to a block of wood and then that to the side of the joist? It would be a pain to sell my 100 clips and then hunt down a good price on very similar ones, but I have more offcuts than my woodstove can keep up with...


----------



## calincole

jaypapek said:


> Hi soundproofing experts,
> 
> I have a box of RSIC-1 sound clips, and a low ceiling. Before I got around to installing them, I discovered the solution here for a low-profile installation: Low ceilings & RSIC. In brief, the idea is to mount your hat channel parallel to each joist with the drywall-receiving surface sitting just a little below the joist. This seems like a great approach.
> 
> Has anyone discovered any drawbacks to this strategy? Everywhere I look says to run hat channel perpendicular rather than parallel to joists, but no one ever explains why.
> 
> Also, does anyone know if you can buy just the extensions for these clips, or do I have to sell my existing clips and buy the new ones? If finding extensions to add to my clips is not possible, what if I just installed each RSIC-1 to a block of wood and then that to the side of the joist? It would be a pain to sell my 100 clips and then hunt down a good price on very similar ones, but I have more offcuts than my woodstove can keep up with...


This is interesting to me and something I might consider doing. However, one problem that stands out when orienting the channel this way is that it will severely complicate anything that you need to place in the ceiling such as lights or speakers. You no longer have natural openings in the grid to place those items.


----------



## jaypapek

calincole said:


> This is interesting to me and something I might consider doing. However, one problem that stands out when orienting the channel this way is that it will severely complicate anything that you need to place in the ceiling such as lights or speakers. You no longer have natural openings in the grid to place those items.


Hmm, that is a great point.


----------



## stamina1914

How often does someone consult with an interior designer to help design their basements and HT. In other words my basement is completely bare and if all I wanted to do is put up drywall, then I would be fine. But lets say I wanted to really design my basement and I need help with envisioning what I want, who should I contact.


----------



## nathan_h

This isn't really the thread to get into details, but here is an overview:



stamina1914 said:


> How often does someone consult with an interior designer to help design their basements and HT.


Don't use an "interior designer" if what you want is a good performing home theater. Rather, consult with a "theater designer."



> In other words my basement is completely bare and if all I wanted to do is put up drywall, then I would be fine. But lets say I wanted to really design my basement and I need help with envisioning what I want, who should I contact.


This depends in part on what your budget is -- that is, your budget for your theater itself (are you looking to spend 10k or 50k or 500k?), and your budget for design services (are you looking to spend 1k, 5k or 20k?).

At the higher end of the spectrum are people like:











High End Home Theater, High End Audio, Home Recording Studio Setup


Acoustic Frontiers offers high end home theater and high end audio solutions. Learn how we can help you with home theater, audio system, or home recording studi




www.acousticfrontiers.com




PMI Performance Media Industries, Ltd. Acoustical Engineering (Anthony Grimani's company)






Erskine Group







www.erskine-group.com





But if you aren't looking to built a six figure theater, their services might be overkill. In that case, consider the services of places like:


HTGurus (@*cdy2179 *here on AVS. I can't find his web site.)









HTE Pro Layout


HTE Pro Layout Service If you've ever done any large home improvement projects, you know how much work it is. Building a home theater is certainly no exception. The planning is as time-consuming as the actual construction. There are dozens of questions you need to answer and so many of the...




htenthusiasts.com


----------



## adrift02

Hi all — I’m planning to convert a W15’xH21’ bonus room into a dedicated theater this summer (house currently being built). I have little control over the initial build, so I’ll be working with a finished/carpeted room with two windows (fully insulated at least).

My question is, about how much space will I lose with a double stud air gap? For the side walls I’m planning either that or maybe an adjoined 2x4+acoustically insulated wall — goal is to minimize sound leakage — but am concerned about how much space I’ll lose in this already small room. Also wondering if I’ll run into moisture issues re: the windows?


----------



## cricket9998

adrift02 said:


> Hi all — I’m planning to convert a W15’xH21’ bonus room into a dedicated theater this summer (house currently being built). I have little control over the initial build, so I’ll be working with a finished/carpeted room with two windows (fully insulated at least).
> 
> My question is, about how much space will I lose with a double stud air gap? For the side walls I’m planning either that or maybe an adjoined 2x4+acoustically insulated wall — goal is to minimize sound leakage — but am concerned about how much space I’ll lose in this already small room. Also wondering if I’ll run into moisture issues re: the windows?


You will lose at minimum 3.5” for the stud and 5/8 for single drywall, plus the air gap. If space is a concern you can look into MLV plus double drywall with green glue. I believe you can staple the MLV to existing drywall then do GG layer. MLV is expensive and ****ing HEAVY so be warned, it’s a major PIA but gets good results

I would also completely block the windows if this is a dedicated room. I did a layer of plywood painted white to the outside, safe n sound and MLV, then two layers of plywood flush with the wall. You can eliminate noise and light very easily. You can make plugs if you want but I made mine permanent. If your windows aren’t leaking, no moisture issues.


----------



## nathan_h

adrift02 said:


> Hi all — I’m planning to convert a W15’xH21’ bonus room into a dedicated theater this summer (house currently being built). I have little control over the initial build, so I’ll be working with a finished/carpeted room with two windows (fully insulated at least).
> 
> My question is, about how much space will I lose with a double stud air gap? For the side walls I’m planning either that or maybe an adjoined 2x4+acoustically insulated wall — goal is to minimize sound leakage — but am concerned about how much space I’ll lose in this already small room. Also wondering if I’ll run into moisture issues re: the windows?


If space is a concern, the best method is to remove the existing drywall in the room, at clips/channels, and then put up drywall on those.....ideally two layers of drywall with GG in between.

This is quite expensive. The other downsides: just doing the walls is not enough. You need to do this on the ceiling and something similar on the floor, and deal with the door, HVAC, etc.

This issue applies even if you choose a cheaper less effective method like just adding layers of drywall. 

So you may want to review the good/better/best options are SoundProofingCompany.com and decide how much attenuation you need versus how much money you have available to spend. You don't have to buy your stuff there (though IIRC their price on GG is about the cheapest around) but they have done a very good job of documenting the effectiveness of each possible technique.


----------



## mhutchins

Another option to the double stud wall is a staggered stud wall. It has relatively good performance but doesn't give up as much space. The cost and performance of a double stud wall without clips and channel may compare favorably with a thinner wall that uses clips and channel for decoupling. In either case, a constrained layer damping product like Green Glue or Kinetics Sound Damp 2 should be applied between drywall layers for optimum performance.

Mike


----------



## adrift02

cricket9998 said:


> You will lose at minimum 3.5” for the stud and 5/8 for single drywall, plus the air gap. If space is a concern you can look into MLV plus double drywall with green glue. I believe you can staple the MLV to existing drywall then do GG layer. MLV is expensive and ****ing HEAVY so be warned, it’s a major PIA but gets good results
> 
> I would also completely block the windows if this is a dedicated room. I did a layer of plywood painted white to the outside, safe n sound and MLV, then two layers of plywood flush with the wall. You can eliminate noise and light very easily. You can make plugs if you want but I made mine permanent. If your windows aren’t leaking, no moisture issues.


Typical air gap is 1"? Thanks for the window suggestions. Yes this will be dedicated so the plywood solution looks good. My main concern with MLV is it's not very effective on low frequencies, right? I'll be running two FV18s so the bass will be a problem before anything else. 



mhutchins said:


> Another option to the double stud wall is a staggered stud wall. It has relatively good performance but doesn't give up as much space. The cost and performance of a double stud wall without clips and channel may compare favorably with a thinner wall that uses clips and channel for decoupling. In either case, a constrained layer damping product like Green Glue or Kinetics Sound Damp 2 should be applied between drywall layers for optimum performance.
> 
> Mike


Thanks! GG seems like a must. Clips/channels too. Staggered vs double stud...I need to do more research but seems like I'd be saving 2" (1" air gap, 1" on 2x6 vs 2 2x4)? STC looks comparable at least.



nathan_h said:


> If space is a concern, the best method is to remove the existing drywall in the room, at clips/channels, and then put up drywall on those.....ideally two layers of drywall with GG in between.
> 
> This is quite expensive. The other downsides: just doing the walls is not enough. You need to do this on the ceiling and something similar on the floor, and deal with the door, HVAC, etc.
> 
> This issue applies even if you choose a cheaper less effective method like just adding layers of drywall.
> 
> So you may want to review the good/better/best options are SoundProofingCompany.com and decide how much attenuation you need versus how much money you have available to spend. You don't have to buy your stuff there (though IIRC their price on GG is about the cheapest around) but they have done a very good job of documenting the effectiveness of each possible technique.


Thx for the soundproofing site rec, that's great. Given the low frequency concern, I feel like decoupling in some way should be a priority. Since apparently the STC numbers don't mean as much with low frequency, I'm still wondering what the difference would be between 1" air gab double stud (Lvl3) versus clips/channels (Lvl2). Looks like I'd be losing ~6" with the air gap on each side, bringing me to 14' width, which isn't ideal but could work. Am I missing something on cost or seems like I could do double stud walls with channel/GG/etc. for ~3-4k? 

For the rest... yeah it's an issue. I'd planned on a drop ceiling, so I could insulate/sound proof that I think? An insulated attic is above. As for the floor... it's installed and not insulated. It would be difficult to do anything structural other than an additional layer to the floor. I don't care about sound transfer down to the family room... but sounds like it's worse than that. The room has HVAC installed, but I don't have many details (house is being built in another state) other than I assume it's part of the upstairs' (split) central system and would be difficult to change. The room has a solid core door installed which I can further sound proof.

So given all that -- what would you do? Save the space and go with the extra layers+GG+channel/clips/etc. since I can only do so much about the rest? A kids room is maybe 8' away across the hall.


----------



## nathan_h

adrift02 said:


> Typical air gap is 1"? Thanks for the window suggestions. Yes this will be dedicated so the plywood solution looks good. My main concern with MLV is it's not very effective on low frequencies, right? I'll be running two FV18s so the bass will be a problem before anything else.
> 
> 
> 
> Thanks! GG seems like a must. Clips/channels too. Staggered vs double stud...I need to do more research but seems like I'd be saving 2" (1" air gap, 1" on 2x6 vs 2 2x4)? STC looks comparable at least.
> 
> 
> 
> Thx for the soundproofing site rec, that's great. Given the low frequency concern, I feel like decoupling in some way should be a priority. Since apparently the STC numbers don't mean as much with low frequency, I'm still wondering what the difference would be between 1" air gab double stud (Lvl3) versus clips/channels (Lvl2). Looks like I'd be losing ~6" with the air gap on each side, bringing me to 14' width, which isn't ideal but could work. Am I missing something on cost or seems like I could do double stud walls with channel/GG/etc. for ~3-4k?
> 
> For the rest... yeah it's an issue. I'd planned on a drop ceiling, so I could insulate/sound proof that I think? An insulated attic is above. As for the floor... it's installed and not insulated. It would be difficult to do anything structural other than an additional layer to the floor. I don't care about sound transfer down to the family room... but sounds like it's worse than that. The room has HVAC installed, but I don't have many details (house is being built in another state) other than I assume it's part of the upstairs' (split) central system and would be difficult to change. The room has a solid core door installed which I can further sound proof.
> 
> So given all that -- what would you do? Save the space and go with the extra layers+GG+channel/clips/etc. since I can only do so much about the rest? A kids room is maybe 8' away across the hall.


Since you can't effectively isolate the floor and the ceiling in your current situation, my approach would be to not go overboard on the walls. Think of it is this way: If you build an aquarium, but one side is open air and has no glass, does it hold water well? Does it make sense to work hard on some walls and not have a bottom?

That's a little bit over the top for a comparison, but bass travels through any path. In the situation you described, no matter how well you decouple the walls, the bass will travel through the ceiling, through the floor, through the HVAC ducts, and even through the closed door.

So, personally, I probably would do less on the walls, and put some budget to the floor and the ceiling. The soundproofing company has examples of "floating floors" (essentially putting a thick pad between the floor in the room and the original floor). I know you don't care about the room below hearing sound, but bass will travel to every other room on the same level of the house via the floor.

The ceiling, as well, can be "de-coupled". 

Yes, STC numbers don't accurately reflect bass but as a general guideline, they can help you to invest in similar levels of isolation in different places. So, if you are following a guideline to achieve an STC of 55 on the ceiling, then following a guideline to achieve an STC of 65 on the walls doesn't make sense. And if you don't build the doorway to achieve an STC of 55, then having achieved that on the walls and ceiling is largely defeated by the acoustic leakage at the door......


----------



## adrift02

nathan_h said:


> Since you can't effectively isolate the floor and the ceiling in your current situation, my approach would be to not go overboard on the walls. Think of it is this way: If you build an aquarium, but one side is open air and has no glass, does it hold water well? Does it make sense to work hard on some walls and not have a bottom?
> 
> That's a little bit over the top for a comparison, but bass travels through any path. In the situation you described, no matter how well you decouple the walls, the bass will travel through the ceiling, through the floor, through the HVAC ducts, and even through the closed door.
> 
> So, personally, I probably would do less on the walls, and put some budget to the floor and the ceiling. The soundproofing company has examples of "floating floors" (essentially putting a thick pad between the floor in the room and the original floor). I know you don't care about the room below hearing sound, but bass will travel to every other room on the same level of the house via the floor.
> 
> The ceiling, as well, can be "de-coupled".
> 
> Yes, STC numbers don't accurately reflect bass but as a general guideline, they can help you to invest in similar levels of isolation in different places. So, if you are following a guideline to achieve an STC of 55 on the ceiling, then following a guideline to achieve an STC of 65 on the walls doesn't make sense. And if you don't build the doorway to achieve an STC of 55, then having achieved that on the walls and ceiling is largely defeated by the acoustic leakage at the door......


Thanks again for all the great advice. I'm going to do clips/channels and GG for walls, then the equivalent for floors and ceiling. I was able to save on the extra insulation cost anyways ($700+ for two interior walls!!) since I can just do it myself after ripping off the drywall -- they unfortunately won't leave the room unfinished. Fun project ahead I suppose.


----------



## cricket9998

Is cellulose blow in insulation with an r-19 value worth blowing in for soundproofing? I don’t want to take the drywall down and I will be blowing it around the house already so figured I can buy a little extra and put it in the theater


----------



## nathan_h

cricket9998 said:


> Is cellulose blow in insulation with an r-19 value worth blowing in for soundproofing? I don’t want to take the drywall down and I will be blowing it around the house already so figured I can buy a little extra and put it in the theater


It helps attenuate some high frequency noise, but does nothing for bass. It doesn't hurt anything, but don't expect big results. 

Replacing your door with a solid core door and weather stripping may help a bit.


----------



## cricket9998

nathan_h said:


> It helps attenuate some high frequency noise, but does nothing for bass. It doesn't hurt anything, but don't expect big results.
> 
> Replacing your door with a solid core door and weather stripping may help a bit.


I built a soundproof door already which helps most of the noise just want to cover that extra bit for late night sessions.

door is not perfect and I would do it differently but it’s basically the original door, wooden spacers 3”, safe n sound, then drywall. It’s amazing how soundproof it is. I’m going to take it apart and redo it with plywood though drywall is just too hard to work with for this application


----------



## mhutchins

In one of the Canada National Research Council ("NRC") studies, they found that insulation in contact with both sides of a partition wall, there was a degree of added sound transmission due to the insulation. By extension, it is probably the case that blown-in insulation is somewhat less effective than batt insulation that does not contact the drywall on each side of the wall. Conversely, blown-in insulation is probably better than no insulation. So the hierarchy is no insulation < blown-in insulation < batt insulation. The caveat to batt insulation, is that it must be properly installed with no voids and should not contact both sides of the wall.

Mike


----------



## nathan_h

I think we are pointing at the same thing.

Yes if the two walls were otherwise decoupled, then adding too much insulation could actually couple them.

In this instance, the OP's walls are *completely coupled already*. In that case, I wouldn't worry about insulation making that worse. It's already in the worse category. But the insulation may help higher frequency sound transmission reduction, which is useful, imo (but far from sound proofing, of course).


----------



## Greygoos3

Any recommendations how to detach a support for a projector without having to reattach directly to the studs. I am using clips and channels and trying to figure out a good idea to detach the projector from the ceiling.


----------



## mhutchins

The best way to mount the projector is to mount its support plate to a piece of plywood or 2x blocking between two adjacent studs above the ceiling. Then, drill a hole through the drywall 1/2"-1" larger in diameter than the support post. Bring the post through the ceiling drywall without making contact with the drywall and caulk around the perimeter of the support post to seal the hole made through the drywall. Now you have a projector mount that will not bounce as much as the ceiling during heavy bass passages yet is strong enough to support any size projector your mount is rated for. I believe @MississippiMan has a drawing of this in one of his many posts.

Mike


----------



## Greygoos3

mhutchins said:


> The best way to mount the projector is to mount its support plate to a piece of plywood or 2x blocking between two adjacent studs above the ceiling. Then, drill a hole through the drywall 1/2"-1" larger in diameter than the support post. Bring the post through the ceiling drywall without making contact with the drywall and caulk around the perimeter of the support post to seal the hole made through the drywall. Now you have a projector mount that will not bounce as much as the ceiling during heavy bass passages yet is strong enough to support any size projector your mount is rated for. I believe @MississippiMan has a drawing of this in one of his many posts.
> 
> Mike


Thanks


----------



## cldsk

*Seeking advice for Best Option*
I have a shared wall between two renter's rooms, I am planning on adding a bunch of soundproofing to the wall to prevent as much noise as possible from transferring between the two spaces.

*On one side (where I have some room to play with) I plan on:*

Adding Roxul Safe and Sound (yes I know that many say fiberglas is just as good, but there are other qualities besides the sound dampening that I like for the Roxul)
2lb MLV
Isolation Clips/Hat Channels
2 x 5/8ths plaster board with Green Glue
Putty pads on outlets and acoustic sealant on all gaps.

*The other side of the wall I only have about a 1/2" or so to play with (about an inch after I take out existing drywall).*

I already purchased enough 2lb MLV for each side, so I plan on using that and either going with:
a single sheet of 5/8ths drywall
a single sheet of 1/2" QuietRock -OR- 5/8th if I can find it
_-OR- if I have enough room:_
a single sheet of 1/2" Quiet Rock with green glue and either 1/2" plasterboard or 5/8ths whatever I have room for
2 sheets of 1/2" plasterboard or 5/8ths or a combination of both depending on what I have room for with Green Glue.


Which of the above do you think would give best results? I don't have exact measurements yet, but I know there is only a small gap between wall and where the doorframe ends on the adjoining wall, so my plan is to take the shared wall to the door's trim and not have the small gap anymore. The wall itself is 9' high x 12' wide with wood studs 16" a part.

Thanks in advance for your suggestions!


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## nathan_h

cldsk said:


> *Seeking advice for Best Option*
> I have a shared wall between two renter's rooms, I am planning on adding a bunch of soundproofing to the wall to prevent as much noise as possible from transferring between the two spaces.
> 
> *On one side (where I have some room to play with) I plan on:*
> 
> Adding Roxul Safe and Sound (yes I know that many say fiberglas is just as good, but there are other qualities besides the sound dampening that I like for the Roxul)
> 2lb MLV
> Isolation Clips/Hat Channels
> 2 x 5/8ths plaster board with Green Glue
> Putty pads on outlets and acoustic sealant on all gaps.
> 
> *The other side of the wall I only have about a 1/2" or so to play with (about an inch after I take out existing drywall).*
> 
> I already purchased enough 2lb MLV for each side, so I plan on using that and either going with:
> a single sheet of 5/8ths drywall
> a single sheet of 1/2" QuietRock -OR- 5/8th if I can find it
> _-OR- if I have enough room:_
> a single sheet of 1/2" Quiet Rock with green glue and either 1/2" plasterboard or 5/8ths whatever I have room for
> 2 sheets of 1/2" plasterboard or 5/8ths or a combination of both depending on what I have room for with Green Glue.
> 
> 
> Which of the above do you think would give best results? I don't have exact measurements yet, but I know there is only a small gap between wall and where the doorframe ends on the adjoining wall, so my plan is to take the shared wall to the door's trim and not have the small gap anymore. The wall itself is 9' high x 12' wide with wood studs 16" a part.
> 
> Thanks in advance for your suggestions!


What kind of sound are you hoping to isolate? If you are trying to capture bass sounds, like music or movies, then neither solution will help much because the bass will travel via the floor and ceiling and through the doors.

If you are trying to lower the sound of voices, then what you describe are all likely to help somewhat. The SoundProofingCompany has a chart that tells you what each combination achieves in terms of STC rating (which doesn't help with bass sounds but can help with voices).

Personally, what you describe as choices are all so similar I would go with whatever is easiest cheapest and realize you will still be able to hear things between the rooms well. You can't build a fish tank with a single wall.


----------



## cldsk

nathan_h said:


> What kind of sound are you hoping to isolate? If you are trying to capture bass sounds, like music or movies, then neither solution will help much because the bass will travel via the floor and ceiling and through the doors.
> 
> If you are trying to lower the sound of voices, then what you describe are all likely to help somewhat. The SoundProofingCompany has a chart that tells you what each combination achieves in terms of STC rating (which doesn't help with bass sounds but can help with voices).
> 
> Personally, what you describe as choices are all so similar I would go with whatever is easiest cheapest and realize you will still be able to hear things between the rooms well. You can't build a fish tank with a single wall.



Thanks so much for the response! I do appreciate it! While I am definitely looking to block as much of all sounds as possible, I know that the low frequency will be challenging. Since I am not looking/able to do anything with the floors or ceilings just yet, I am hoping that acoustical sealant on the frame/etc. will help a little with that. I appreciate the lead with the chart on TheSoundProofingCompany - I will check that out! I have seen a lot of mixed reviews on the effectiveness of QuietRock vs double drywall with the Green Glue, so I am wondering if you or anyone has had any real world experience with QuietRock and think it is worth it? Since I don't have a lot of space on the one side, I would be willing to splurge for that, but I would hate to get it and find that it has the same real-world effectiveness as a 5/8th sheet of gypsum! lol


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## Harkon

So, I’m after suggestions to reduce the fan noise from my two inline fans to recycle air in the room. There are two of these. Big 5’’, S&P in-line fans. They are marketed as the one of the quietest on the market but in they are still too noisy. No vibrations or air noise from the set up, but I can hear the whine of the motor/blades. Both are housed in the soffits within the room, as there was no option to get them out of the room. 










I added sound proofing around the fans originally. The fan attaches to the wall via a rubber mount to reduce vibrations.
The soffits are 12mm MDF on all sides. The vertical parts also have 12mm or 18mm OSB, forget which. All soffits are filled with fibreglass insulation. I then made this panel to sit loose under the fan. 2 x 12mm MDF and two layers of lead. They were really heavy!












If I remove that panel I’ll have about an inch around most of the fan. What can I do?

I've not used TECSOUND but seen others use it.
What are your thoughts on sticking multiple layers over the fan. Is it self adhesive? Would lots of layers of this be better than the loose insulation?

Only other options are buy a different fan (big expense) or just not use them, waste of money. I’m also then worried that the projector would over heat without an air supply at the back, even if I use an AC Infinity USB fans to remove air at the front.

The first fan draws air from the adjacent room and then vents it behind the projector intake vents. Lefthand side, pipe not attached yet in this picture.


----------



## AndreNewman

Harkon said:


> So, I’m after suggestions to reduce the fan noise from my two inline fans to recycle air in the room. There are two of these. Big 5’’, S&P in-line fans. They are marketed as the one of the quietest on the market but in they are still too noisy.


 I have one of those, very impressed with it but I'm only using it to ventilate our bathrooms.

I can't see in the picture what the fan brackets are attached to?

I found with mine that was originally attached to a board attached to the ceiling (by previous owner) that the fan was vibrating the whole ceiling, amplifying the motor vibrations. I changed it to hang the fan by it's isolating brackets from a much more rigid roof truss, much much quieter.

If yours is attached to the soffit or the ceiling, maybe something similar is occurring, I'd attach it to the wall assuming that's a solid bring or block wall, UK ones usually are, maybe re-position the fan so it's on a different more solid wall if some are internal plasterboard.

Otherwise as I did at a friend's place a few weeks ago, don't screw the fan to anything, loosely support it with a few pieces of soft foam, works wonders.


----------



## Harkon

Thanks for your input. Currently it's bolted to the outside concrete block wall using frame fixing bolts, so it's a solid fixing. I could just sit it on foam or even hang it, but currently it has no contact at all with the soffit which I thought would be better. 

We aren't talking loud either. Room noise floor is 30db. With both fans on it's 36db. I just want to close that gap.


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## nathan_h

The lab meaurments I have seen show it is better than regular drywall but not quite as good as double drywall with green glue in between (and more expensive).

But even double drywall is disappointing if the studs are shared, or the floor or ceiling joists are shared, between rooms. If space and money is tight then decoupling devices like clips and channels are better than either, in my view.

But you can review the data and decide.



cldsk said:


> Thanks so much for the response! I do appreciate it! While I am definitely looking to block as much of all sounds as possible, I know that the low frequency will be challenging. Since I am not looking/able to do anything with the floors or ceilings just yet, I am hoping that acoustical sealant on the frame/etc. will help a little with that. I appreciate the lead with the chart on TheSoundProofingCompany - I will check that out! I have seen a lot of mixed reviews on the effectiveness of QuietRock vs double drywall with the Green Glue, so I am wondering if you or anyone has had any real world experience with QuietRock and think it is worth it? Since I don't have a lot of space on the one side, I would be willing to splurge for that, but I would hate to get it and find that it has the same real-world effectiveness as a 5/8th sheet of gypsum! lol


----------



## nathan_h

Harkon said:


> Thanks for your input. Currently it's bolted to the outside concrete block wall using frame fixing bolts, so it's a solid fixing. I could just sit it on foam or even hang it, but currently it has no contact at all with the soffit which I thought would be better.
> 
> We aren't talking loud either. Room noise floor is 30db. With both fans on it's 36db. I just want to close that gap.


If there is an air intake outside the room why can’t the fan go there?

Where is the room’s exhaust?


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## Harkon

nathan_h said:


> If there is an air intake outside the room why can’t the fan go there?
> 
> Where is the room’s exhaust?


Intake is from the kitchen area and no space for the large size of the fan. This enters the room at the back of the projector hush box to create positive pressure. A second fan (in another soffit) draws air from above the rack (in room, no space outside), and vents outside. UK room, only 12ft by 13ft after sound proofing, so less options on placement of things.


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## AndreNewman

Harkon said:


> Thanks for your input. Currently it's bolted to the outside concrete block wall using frame fixing bolts, so it's a solid fixing. I could just sit it on foam or even hang it, but currently it has no contact at all with the soffit which I thought would be better.
> 
> We aren't talking loud either. Room noise floor is 30db. With both fans on it's 36db. I just want to close that gap.


I found your thread on AVF just now so I won't suggest anything already suggested there.

These fan units are sized to fit between floors, have you considered putting it in the ceiling but outside the cinema room?

Oh and ours gets noisier when it hasn't been cleaned for a while...


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## nathan_h

Harkon said:


> Intake is from the kitchen area and no space for the large size of the fan. This enters the room at the back of the projector hush box to create positive pressure. A second fan (in another soffit) draws air from above the rack (in room, no space outside), and vents outside. UK room, only 12ft by 13ft after sound proofing, so less options on placement of things.


Sounds challenging….no pun intended.

If you can’t fasten a box mounted fan outside on the side of the building where this exhausts, I’d guess the other option would be a larger muffler box where the fan is suspended in the middle of fiberglass batting (assuming that is fire safe) like this but with a fan in the middle:













…. or at least decouple the fan from the wall and run it more slowly if replacing it is not an option?


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## cldsk

I have a contractor doing my soundproof install. I just noticed that instead of the acoustic sealant (which I provided) they were using the green glue (which I provided for the drywall) to “seal” the mlv seams. I know green glue won’t do that job and I intend to have them do it right, I am assuming they would be able to wipe away the green glue at the seams then apply the sealant and retape? No harm would come to the wall assembly if any green glue remains???

sadly, it looks like 6 tubes of green glue were wasted - glad I caught the error before they got further!


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## squared80

They owe you for that mistake. Green Glue is expensive, man. Directions are not hard to follow - didn't we all learn to do that by 4th grade?


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## cldsk

squared80 said:


> They owe you for that mistake. Green Glue is expensive, man. Directions are not hard to follow - didn't we all learn to do that by 4th grade?


I agree - def going to have them pay for the replacement Green Glue - just curious on course of cleanup/applying the sealant correctly over the mistake areas.


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## dkscism

Hello All, 
I have done a fair amount of research and reading from this thread. First, I am not installing a home theatre. I am adding an residential apartment above a commercial retail space and simply want to isolate the spaces. I have almost 2200 square feet of floor/ceiling assembly. 
My objective is to limit the walking/impact as well as airborne sound that travels through the floor/ceiling assembly. 
The downstairs ceiling will be drywall, so I am planning on using isolation clips in combination with hat channel to de couple the drywall from the floor joists. The space between the floor/ceiling will have R19 insulation.
In addition to this I am planning on having two layers of subfloor on top of the joists with an underlayment (serena mat?) between the two layers. 
The space between the floor/ceiling will have R19 insulation.
I'm curious if you all think this will be effective for my purposes. 

I have one fundamental question as well: Are any of these methods more effective at eliminating sound traveling in a certain direction? In other words, is one method better than others at stopping sound from getting in vs going out (traveling from upstairs to downstairs, or vice versa)?


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## squared80

dkscism said:


> Hello All,
> I have done a fair amount of research and reading from this thread. First, I am not installing a home theatre. I am adding an residential apartment above a commercial retail space and simply want to isolate the spaces. I have almost 2200 square feet of floor/ceiling assembly.
> My objective is to limit the walking/impact as well as airborne sound that travels through the floor/ceiling assembly.
> The downstairs ceiling will be drywall, so I am planning on using isolation clips in combination with hat channel to de couple the drywall from the floor joists. The space between the floor/ceiling will have R19 insulation.
> In addition to this I am planning on having two layers of subfloor on top of the joists with an underlayment (serena mat?) between the two layers.
> The space between the floor/ceiling will have R19 insulation.
> I'm curious if you all think this will be effective for my purposes.
> 
> I have one fundamental question as well: Are any of these methods more effective at eliminating sound traveling in a certain direction? In other words, is one method better than others at stopping sound from getting in vs going out (traveling from upstairs to downstairs, or vice versa)?


How about double drywall with Green Glue between the joists, then R19 below that.


----------



## dkscism

Thanks for the advice. A small change of plans after talking with The Soundproofing Company over the phone.
For the ceiling downstairs I will use clips+channel to decouple two layers of drywall with green glue between.
Upstairs I will have two layers of subfloor with GG between. 
One question, is it beneficial from a soundproofing perspective to use a Gypcrete product instead of toungue and groove subfloor?


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## Eggtuary

warwwolf7 said:


> 2nd layer of drywall will cost less than sonopan for a better result


I have been wondering about this as well. Our builder is still only building spec homes until material availability and pricing becomes less volatile, so we are probably multiple years out from having a home where it makes sense to put in a home theater. But I have been intrigued with what I have seen about Sonopan, and wondered if it could be a good option one day, assuming they eventually sell to homeowners in the States. Both of you say Green Glue and heavy drywall are better. Is that based on studies? I haven’t seen any. I’m not saying you’re wrong. I was just hoping Sonopan would come close as I am probably going to DIY, and it seems a lot easier to work with.


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## nathan_h

Eggtuary said:


> I have been wondering about this as well. Our builder is still only building spec homes until material availability and pricing becomes less volatile, so we are probably multiple years out from having a home where it makes sense to put in a home theater. But I have been intrigued with what I have seen about Sonopan, and wondered if it could be a good option one day, assuming they eventually sell to homeowners in the States. Both of you say Green Glue and heavy drywall are better. Is that based on studies? I haven’t seen any. I’m not saying you’re wrong. I was just hoping Sonopan would come close as I am probably going to DIY, and it seems a lot easier to work with.


Its not quite apples to apples, since the GG chart isn't showing dual drywall and GG on both sides of the stud, but the Sonopan is showing sheets on both sides, but you can see they are in the ballpark....with the GG solution on ONE side of the wall, slightly best the Sonopan solution on both sides in terms of STC.

STC is not the only way to measure, but this is conceptually useful. 





















So then the question becomes one of cost and ease of install. Personally,* if I was trading cost for ease of install*, I'd probably get quiet rock (the 545 model). It's effective, available, and straightforward. You pay for that in materials cost, but that's sometimes a fine tradeoff. (Its basically like drywall with a layer of GG built into the middle of it.)


----------



## mhutchins

5/8" Type-X Gypsum wall board is 2.7x heavier than 3/4" SONOpan (70Lbs vs. 26Lbs). The added mass of the Type-X will provide better low frequency performance than the lighter SONOpan. Remember that STC does not consider bass frequencies below 125Hz. Furthermore, STC determinations allow low frequency transmission from 125HZ-200Hz to be anywhere from 18-24dB louder than the STC number and still be within spec. For example, the STC 53 SONOpan wall could have only 19db transmission loss at 125Hz and still be in compliance with the STC 53 spec whereas the Type-X wall with Green Glue has nearly double that transmission loss at 125Hz (without seeing the actual STC curve for SONOpan, the performance comparison is conjecture, however, low frequency performance is much more dependent upon mass vs. the higher frequencies).

Since the low frequencies are the hardest to control in terms of transmission loss through a partition, I would always recommend the denser product for a home theater application.

Mike


----------



## Eggtuary

mhutchins said:


> 5/8" Type-X Gypsum wall board is 2.7x heavier than 3/4" SONOpan (70Lbs vs. 26Lbs). The added mass of the Type-X will provide better low frequency performance than the lighter SONOpan. Remember that STC does not consider bass frequencies below 125Hz. Furthermore, STC determinations allow low frequency transmission from 125HZ-200Hz to be anywhere from 18-24dB louder than the STC number and still be within spec. For example, the STC 53 SONOpan wall could have only 19db transmission loss at 125Hz and still be in compliance with the STC 53 spec whereas the Type-X wall with Green Glue has nearly double that transmission loss at 125Hz (without seeing the actual STC curve for SONOpan, the performance comparison is conjecture, however, low frequency performance is much more dependent upon mass vs. the higher frequencies).
> 
> Since the low frequencies are the hardest to control in terms of transmission loss through a partition, I would always recommend the denser product for a home theater application.
> 
> Mike


Thanks, Mike. In my situation, I wasn’t thinking about replacing the ⅝” drywall with Sonopan. I was only considering replacing the Green Glue with Sonopan. But you raise very interesting points about the STC standard at low frequencies, which is exactly what I’m most concerned about controlling. I knew STC didn’t go below 125 Hz, but I hadn’t heard that about the 125 to 250 Hz octave.


----------



## ambesolman

I’ve got a question that I haven’t seen any info about. I’m planning my build doing a room within a room, clips, channel, gg, etc. I’m wanting to do a little something different for the walls by adding stacked rock. I don’t know if I’ll do the whole walls stacked floor to ceiling with rock or just the lower half. I’m leaning towards the first layer being osb.

My question is, if the stacked rock would have to be applied to a layer of cement board, could that just be my second layer while using gg between it and the osb?


Sent from my iPhone using Tapatalk?


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## bob53

Hello all -

We completed our new home this past December and I am about to start on the only room I did not have finished - the basement theater room. I was hoping for some advice/guidance on practical soundproofing. The drywall was hung in this room (but not taped) despite the fact I asked them not to do this. I'm fairly handy and so removing drywall is no big deal. I suspect I will need to do this anyway to make minor framing adjustments. I've attached some photos of the basic floorplan, how this plan fits in with the home and adjacencies to other rooms, and a photo of the current status of the room (apologies on all the junk as this is where all of the unused construction materials have been stored).

Some basic information:
Room dimensions - 16' wide x 25'6" deep x 10'2" tall (with lots of soffits that drops this down to 8' at the doorway and 9'2" at the screen wall (see photos)).
Location - basement of walkout home. Theater is located in location of home where it is fully underground.
Floor - Poured concrete with hydronic heat. There is a 1'2"-1'3" drop built into floor for stadium seating. Riser needs to be rebuilt for final design.

Wall Construction details:

standard 2x4 framing, all walls in home have 5/8" firecode drywall (for level 5 finish).
Screen wall and right side wall abut a 10" poured concrete foundation wall.
Rear and left walls are load bearing framed 2x4 walls. Rear wall abuts living space. Left wall abuts mechanical room that is fully finished with drywall and is sealed to remainder of the home with single hinged door.
All foundation wall framing was spaced away from foundation by 1/2" to 1" but spray foam likely bridges this gap in some places.

Ceiling Construction details:

14" TJIs joists with 1" thick subfloor, 1-1/2" gypcrete (in floor heat), ditra uncoupling membrane, and 3/4" (total) thick mortar bed and natural stone floor above on main level.
All joists throughout basement ceiling filled with batt-like fiberglass insulation to maximize efficiency of infloor heat above.
drop soffits are both decorative (see photos) and also used to give space to transmit ductwork in home (this is true in rear of theater). These are not currently filled with insulation.

Doors: 

All doors in home are Trustile solid core doors with thick decorative veneer (in my case - walnut). Each theater door weighs 200 lbs!
Doors to theater are a pair of Trustile doors (I can hear the collective groans  ). We have the astragal and door seal hardware to seal the doors when they close...

HVAC: 
- The supply and return for this room runs through dedicated acoustic mufflers (rat maze design) before joining up with the main ducts that supply half the basement only. I built these mufflers and they attenuate sound nicely. 

Assumptions (please correct these if incorrect)
1. STC of ceiling overhead should already be reasonable with the mass and thickness of the gypcrete and tile floor. I might already be at STC 50?
2. Soundproofing into adjacent mechanical room is less critical as this space can be sealed off and adds some attenuation of sound coming out of this room into the living space.
3. Soundproofing of screen wall is not as important as a THX baffle wall is going to be created and will have an air gap between the two framed walls.
4. Soundproofing should focus most on the walls that are in direct communication with the living space.

My questions:
1. From a pragmatic viewpoint, what are the best ways to modify the existing construction/plan to minimize "shrinking" the room too much? I'd like to preserve the existing dimensions as much as I can. I am open to yanking out all of the drywall and placing MLV, adding staggered studs (slightly), etc. My drywallers were not thinking about soundproofing when they put up the drywall. They also glued all of the drywall to the studs in addition to screwing. 
2. Can I achieve reasonable STCs (55-60) without needing to decouple the drywall walls and ceiling? Can I add MLV, drywall, green glue, and drywall to achieve this? 
3. How does decoupling with staggered studs compare with resiliant channel with regard to real world performance?
4. Is there a low profile version of the drywall clip/resiliant channel systems to decouple the walls from the framing to minimize the amount of lost space?

Thanks for your help,

Bob


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## nathan_h

Looks like a nice space.



bob53 said:


> Assumptions (please correct these if incorrect)
> 1. STC of ceiling overhead should already be reasonable with the mass and thickness of the gypcrete and tile floor. I might already be at STC 50?
> 2. Soundproofing into adjacent mechanical room is less critical as this space can be sealed off and adds some attenuation of sound coming out of this room into the living space.
> 3. Soundproofing of screen wall is not as important as a THX baffle wall is going to be created and will have an air gap between the two framed walls.
> 4. Soundproofing should focus most on the walls that are in direct communication with the living space.
> 
> My questions:
> 1. From a pragmatic viewpoint, what are the best ways to modify the existing construction/plan to minimize "shrinking" the room too much? I'd like to preserve the existing dimensions as much as I can. I am open to yanking out all of the drywall and placing MLV, adding staggered studs (slightly), etc. My drywallers were not thinking about soundproofing when they put up the drywall. They also glued all of the drywall to the studs in addition to screwing.
> 2. Can I achieve reasonable STCs (55-60) without needing to decouple the drywall walls and ceiling? Can I add MLV, drywall, green glue, and drywall to achieve this?
> 3. How does decoupling with staggered studs compare with resiliant channel with regard to real world performance?
> 4. Is there a low profile version of the drywall clip/resiliant channel systems to decouple the walls from the framing to minimize the amount of lost space?


Before tearing things apart maybe run a test? Bring in a subwoofer and play some bass heavy music? 

1. I would guess 40 max and less effective for bass.
2-4. Not really. Bass travels through solid structures.

1-4. Pull off the drywall on walls and ceiling and use hat channels and clips or similar would likely be the biggest improvement with the smallest loss of space if done right. 

The trouble with staggered studs is that the ceiling plate is still a conduit for sound. It helps but may not be worth the loss of space.

This web site has great info and white papers:


----------



## bob53

nathan_h said:


> Looks like a nice space.
> 
> Before tearing things apart maybe run a test? Bring in a subwoofer and play some bass heavy music?
> 
> 1. I would guess 40 max and less effective for bass.
> 2-4. Not really. Bass travels through solid structures.
> 
> 1-4. Pull off the drywall on walls and ceiling and use hat channels and clips or similar would likely be the biggest improvement with the smallest loss of space if done right.
> 
> The trouble with staggered studs is that the ceiling plate is still a conduit for sound. It helps but may not be worth the loss of space.
> 
> This web site has great info and white papers:


Nathan -

That's a good idea re: running a test. 

I'm find with clips and channels as it looks like there is a way to install some in a low profile fashion where it would only add 0.5" to the wall thickness. The top ceiling can drop and inch or two without much consequence. My only concern are the drop soffits on the ceiling extending out to the room entrance as they were framed before any drywall was added and also, in some locations, carry ductwork, wires, PEX, etc... The clearances between the soffit ceiling and top of the door jamb is such that we do not have more than another 5/8" to 3/4" before the ceiling would be too low. 

Any advice on these soffits? Should I just add a sandwich of 5/8-GG-5/8 drywall in these locations and just accept these as an acoustic weak point or is there some other solution? MLV? Add drywall to the framing "windows" to create a very thick sandwich of drywall in the void space of the framing? I cannot, for practical purposes, reframe these soffits and even if I did, the HVAC ducts in the back that transgresses this space (but does not supply or return here) cannot be moved.


----------



## nathan_h

bob53 said:


> Nathan -
> 
> That's a good idea re: running a test.
> 
> I'm find with clips and channels as it looks like there is a way to install some in a low profile fashion where it would only add 0.5" to the wall thickness. The top ceiling can drop and inch or two without much consequence. My only concern are the drop soffits on the ceiling extending out to the room entrance as they were framed before any drywall was added and also, in some locations, carry ductwork, wires, PEX, etc... The clearances between the soffit ceiling and top of the door jamb is such that we do not have more than another 5/8" to 3/4" before the ceiling would be too low.
> 
> Any advice on these soffits? Should I just add a sandwich of 5/8-GG-5/8 drywall in these locations and just accept these as an acoustic weak point or is there some other solution? MLV? Add drywall to the framing "windows" to create a very thick sandwich of drywall in the void space of the framing? I cannot, for practical purposes, reframe these soffits and even if I did, the HVAC ducts in the back that transgresses this space (but does not supply or return here) cannot be moved.


At some point very soon a “weak point” is like a hole in a bucket: it is small and just one little area…..and it renders the bucket not so functional.

Before giving up, and before tearing into walls, run the test.

Hopefully the results will be acceptable! 

I suspect your (understandable) constraints will leave you only middling choices but knowing specifically where and what sounds are escaping will help focus on what those problems might indicate as next steps, if any.


----------



## iron4044

Hi All,

I'm just jumping into this so here's a simple question. We have an existing home theater room that we want to upgrade. Instead of tearing down current drywall and reinstalling, it looks like (link below) we could add another layer of drywall but with a space between with respective insulation. I'm not even looking to sound proof but more sound leasing to other rooms.

Am I understanding this correctly?

Edit: I didn't notice there is an actual 6" gap between two separate walls. DUH... I thought it was simply running a 2x6 along current drywall and then putting up another layer of drywall.









Soundproofing Your Home Theater Part Two: Building a Room Within a Room


Part two of our advice on how to soundproof a room: building a room-within-a-room to isolate sound.




www.axiomaudio.com


----------



## nathan_h

iron4044 said:


> Hi All,
> 
> I'm just jumping into this so here's a simple question. We have an existing home theater room that we want to upgrade. Instead of tearing down current drywall and reinstalling, it looks like (link below) we could add another layer of drywall but with a space between with respective insulation. I'm not even looking to sound proof but more sound leasing to other rooms.
> 
> Am I understanding this correctly?
> 
> Edit: I didn't notice there is an actual 6" gap between two separate walls. DUH... I thought it was simply running a 2x6 along current drywall and then putting up another layer of drywall.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Soundproofing Your Home Theater Part Two: Building a Room Within a Room
> 
> 
> Part two of our advice on how to soundproof a room: building a room-within-a-room to isolate sound.
> 
> 
> 
> 
> www.axiomaudio.com


I don't think axiom has done their homework. They are proposing two complete walls with drywall on both sides. So while a room within a room is a great idea, doing it their way will create multiple leaf effects and perhaps create as many issues as it solves.....and eat up more space and money then other solutions.

Take a look at Home where you can see better vetted and tested approahes.

TLDR: to do something useful in terms of reducing sound transmission, first, make sure your door is solid core and has at least weather sealing. Second, especially if you want to deal with something other than voices (ie, bass is touch to reduce) you will find you likely need to remove the drywall on all the walls and the ceiling. But if you share more details about your current room, folks here may have other ideas to help.


----------



## iron4044

Thanks. I will share more soon. We're moving in and don't have the exact dimensions yet.


----------



## mhutchins

bob53 said:


> Hello all -
> 
> We completed our new home this past December and I am about to start on the only room I did not have finished - the basement theater room.
> .
> .
> Wall Construction details:
> .
> .
> Ceiling Construction details:
> 
> 14" TJIs joists with 1" thick subfloor, 1-1/2" gypcrete (in floor heat), ditra uncoupling membrane, and 3/4" (total) thick mortar bed and natural stone floor above on main level.
> All joists throughout basement ceiling filled with batt-like fiberglass insulation to maximize efficiency of infloor heat above.
> drop soffits are both decorative (see photos) and also used to give space to transmit ductwork in home (this is true in rear of theater). These are not currently filled with insulation.
> Doors:
> .
> .
> HVAC:
> .
> .
> My questions:
> .
> .
> Thanks for your help,
> 
> Bob


Hi Bob,

Your ceiling construction is fairly good, however, you may have issues with footfall noise. A simple test is to have someone drop a marble on the stone floor above and see how loud it is in the basement. The Level 3 Ceiling that has the drywall and Green Glue placed in between the floor joists is a good solution for this type of noise. It is relatively low cost, but labor intensive.

As to the soffits, often times these are framed quickly without concern for minimizing wasted space. It would probably be worthwhile to remove a 2' x 4' section near the doors with low clearance to see if you can gain a few inches of ceiling height in the soffits. There are several ways to build soffits with minimal framing that can save a lot of space.

Mike


----------



## bob53

mhutchins said:


> Hi Bob,
> 
> Your ceiling construction is fairly good, however, you may have issues with footfall noise. A simple test is to have someone drop a marble on the stone floor above and see how loud it is in the basement. The Level 3 Ceiling that has the drywall and Green Glue placed in between the floor joists is a good solution for this type of noise. It is relatively low cost, but labor intensive.
> 
> As to the soffits, often times these are framed quickly without concern for minimizing wasted space. It would probably be worthwhile to remove a 2' x 4' section near the doors with low clearance to see if you can gain a few inches of ceiling height in the soffits. There are several ways to build soffits with minimal framing that can save a lot of space.
> 
> Mike


Hi Mike -

I hear nothing when a marble is dropped from above nor any footfall noise in the room(s) over the theater so that is a good sign. That said, since I am going to be probably tearing out drywall, perhaps this is a good time to install the drywall between the joist spaces as you suggest. A few additional STC points cannot hurt.

Regarding the sofitts - I know how these were constructed and unfortunately all of the soffits in the rear of the theater hide transiting HVAC sheet metal duct and at best there is 1/2" clearance between the 2x4 framing and this ducting. I was wondering if I could soundproof this much like the level 3 ceiling by adding sandwiched drywall to all of the "windows" created by the soffit ladder frame. It would be a ton of work but it might be my only option. I could tear out the other soffits in the room but I'd prefer to find a workaround.

My ceiling also poses one other potential challenge (maybe there is some benefit here too?) - the recessed lights are from a brand called Tech Lighting. The boxes are completely sealed but open to the air in the room. The issue is that the trim rings are meant to be mudded/plastered in to create a seamless look. Given that the boxes are sealed, can I get away with not building a box around them or am I going to transmit lots of sound through these? 

With the walls, I think I am fairly convinced I should spend the time and money to add the clip/channel system to isolate the room.

With the ceiling, am I better off just GG'ing another sheet of 5/8" drywall or should I go the extra step and add clips/channel (potentially parrallel with the joists for low profile install)? What would you do if it were your space?

Finally, what acoustic treatments should I consider, if anything, for the concrete subfloor? The finished floor will be carpet. Is there any benefit to the expensive "acoustic" underlayments like Serena to use in addition to or instead of carpet pad? MLV under the pad?


----------



## mhutchins

bob53 said:


> Hi Mike -
> 
> *1. *I hear nothing when a marble is dropped from above nor any footfall noise in the room(s) over the theater so that is a good sign. That said, since I am going to be probably tearing out drywall, perhaps this is a good time to install the drywall between the joist spaces as you suggest. A few additional STC points cannot hurt.
> 
> *2. *Regarding the sofitts - I know how these were constructed and unfortunately all of the soffits in the rear of the theater hide transiting HVAC sheet metal duct and at best there is 1/2" clearance between the 2x4 framing and this ducting. I was wondering if I could soundproof this much like the level 3 ceiling by adding sandwiched drywall to all of the "windows" created by the soffit ladder frame. It would be a ton of work but it might be my only option. I could tear out the other soffits in the room but I'd prefer to find a workaround.


I just have time to comment on these two points:

If you don't hear anything from the marble test nor any footfall noise, I doubt doing the drywall between the joists is going to be worth the effort. Your floor seems to be very quiet and you should be glad you can safely skip this step and instead focus on eliminating the transmission of lower frequencies like da bass.
Would rebuilding the soffits using the method pictured below save you enough room to add a decoupled ceiling? If not, what about changing the duct profile to a rectangular duct that is flatter in height? Or, running two smaller ducts that are shorter in height but provide a slightly greater cross sectional area (110-120% larger) than the duct they are replacing?


----------



## adrift02

Hi friends -- I'm moving into my new home next month and will be converting the finished bonus into a theater. I know what A/V equipment I need and have an old friend who's hooking me up with the design + acoustic treatment products, but I don't have a contractor to do the soundproofing (replace existing sheetrock with 2x/GG on channel/clips, etc.). 

I know most A/V pros go in assuming they're doing the full job (product/design) and you have a contractor, and then a typical contractor wouldn't really know about channels/clips, green glue, etc., so in this situation how should I go about finding a contractor? FYI nobody is listed in the ID/Boise area in that thread from what I see and I don't know anyone in the area.

I'm randomly reaching out but honestly am lost re: _where_ I should be looking. Drywall/insulation companies? General contractors?


----------



## calincole

I'm hoping to get some input on Atmos speakers and backer boxes. Currently building my theater for 7.2.4 Will be doing DD+GG on clip and channel. I had planned to to in ceiling speakers for Atmos, something along the lines of the the RSL C34E MKII (seems like a good price/performance ratio). As I was getting into the details of it though, I find that these speakers are pretty big and so I went back and really started checking in ceiling speakers and the ceiling I am working with, and I have an issue. 

My ceiling joists are 2x8's (older home) so the max depth I have 7 1/4. Some areas have stuff in the bays, but not a ton. However I was planning on building backer boxes for soundproofing. It seems that all the speakers I have found specify the internal volume of backer boxes to be at least 1 cubic foot, or more. The RSL for example I see 1.2-1.5 recommended. The more I look, the more it seems that hitting internal volumes at those sizes will be pretty unwieldy given my shallow depth. So, I have a couple questions:

In general are people building backer boxes of those sizes? Or are results fine when scaling them down for this kind of application?
Are there recommended speakers for small volumes that I just don't know about?

My alternative is to do on ceiling speakers of some kind which I am currently researching, so any recommendations on that would also be appreciated. Final ceiling height is gonna be about 93 inches so I need low profile.


----------



## nathan_h

adrift02 said:


> Hi friends -- I'm moving into my new home next month and will be converting the finished bonus into a theater. I know what A/V equipment I need and have an old friend who's hooking me up with the design + acoustic treatment products, but I don't have a contractor to do the soundproofing (replace existing sheetrock with 2x/GG on channel/clips, etc.).
> 
> I know most A/V pros go in assuming they're doing the full job (product/design) and you have a contractor, and then a typical contractor wouldn't really know about channels/clips, green glue, etc., so in this situation how should I go about finding a contractor? FYI nobody is listed in the ID/Boise area in that thread from what I see and I don't know anyone in the area.
> 
> I'm randomly reaching out but honestly am lost re: _where_ I should be looking. Drywall/insulation companies? General contractors?


I suppose it depends on budget. Some of the best installers in the business fly in a crew to do the work, so your location doesn't really matter much. Of course, that would be a room budget in the six figures.

To find local talent, I'd probably ask the people at any AV store in town about crews or companies that have expertise in this area.

Here on AVS, you might get the most "hits" from searching for Boise in the construction area (Search results for query: Boise) which will pull up posts by people mentioning Boise.


----------



## nathan_h

calincole said:


> I'm hoping to get some input on Atmos speakers and backer boxes. Currently building my theater for 7.2.4 Will be doing DD+GG on clip and channel. I had planned to to in ceiling speakers for Atmos, something along the lines of the the RSL C34E MKII (seems like a good price/performance ratio). As I was getting into the details of it though, I find that these speakers are pretty big and so I went back and really started checking in ceiling speakers and the ceiling I am working with, and I have an issue.
> 
> My ceiling joists are 2x8's (older home) so the max depth I have 7 1/4. Some areas have stuff in the bays, but not a ton. However I was planning on building backer boxes for soundproofing. It seems that all the speakers I have found specify the internal volume of backer boxes to be at least 1 cubic foot, or more. The RSL for example I see 1.2-1.5 recommended. The more I look, the more it seems that hitting internal volumes at those sizes will be pretty unwieldy given my shallow depth. So, I have a couple questions:
> 
> In general are people building backer boxes of those sizes? Or are results fine when scaling them down for this kind of application?
> Are there recommended speakers for small volumes that I just don't know about?
> 
> My alternative is to do on ceiling speakers of some kind which I am currently researching, so any recommendations on that would also be appreciated. Final ceiling height is gonna be about 93 inches so I need low profile.


This isn't the thread to get deep into speaker recommendations, but you should specify a budget for your solution. This thread discusses almost all the best candidates for in ceiling speakers (List of angled in-ceiling speakers (and why you need them) for Immersive Sound formats (Atmos, Auro, DTS:X)) and quite a few are more shallow than your ceiling and have backer boxes already included.


----------



## calincole

nathan_h said:


> This isn't the thread to get deep into speaker recommendations, but you should specify a budget for your solution. This thread discusses almost all the best candidates for in ceiling speakers (List of angled in-ceiling speakers (and why you need them) for Immersive Sound formats (Atmos, Auro, DTS:X)) and quite a few are more shallow than your ceiling and have backer boxes already included.


Sorry, the end of this got away from me. What I am really asking here is the use of backer boxes for soundroofing and what tolerances there in sizing backer backer boxes. If this sir not appropriate for that Ill keep looking. In terms for budget I would stay under 200 per speaker for these not counting any materials cost. I will read that linked thread as well, thanks.


----------



## nathan_h

Every speaker is different. So checking with the manufacturer for ideal back box size is a good idea. Usually if you go smaller you lose some output and extension. Not a tragedy for Atmos speakers. That being said, unless you are building the backer boxes yourself (sweat equity) or you require a specific model that doesn’t have a built in enclosure, I would just buy one of the many speakers that include a backer box.


----------



## nathan_h

Just ran across this YouTube video which pretty much summarizes best practices with regarding to acoustic isolation, otherwise known colloquially as "soundproofing". Only real flaw is that he fails to mention you need to do all these things together, not just pick and choose some of them.


----------



## calincole

What is the best practices for sealing holes with plumbing penetrations? Is acoustical sealant fine to handle the temp change hot or cold lines? What about where an opening is 1 inch diameter with a small pipe in it? stuff it with something like rockwool or what?


----------



## nathan_h

Read the caulk manufacturer specs closely to see what the heat ratings are. I’m guessing you’ll be fine though in any application trying to fill more than a 1/4” is not a good idea.


----------



## calincole

nathan_h said:


> Read the caulk manufacturer specs closely to see what the heat ratings are. I’m guessing you’ll be fine though in any application trying to fill more than a 1/4” is not a good idea.


Thanks, Will do. 

Separate question, I am insulating my ceiling soon, how much insulation is appropriate? My joists are 2x8s 16 on center, so really the question is should I use a single layer of insulation, or double it up to fill the cavity? This is a basement ceiling so thermal is unimportant, will be clips and channel with DD/GG in the end.


----------



## nathan_h

calincole said:


> Thanks, Will do.
> 
> Separate question, I am insulating my ceiling soon, how much insulation is appropriate? My joists are 2x8s 16 on center, so really the question is should I use a single layer of insulation, or double it up to fill the cavity? This is a basement ceiling so thermal is unimportant, will be clips and channel with DD/GG in the end.


I would fill it (but not tightly) within an inch or two of its capacity. So I'm going by memory but it would be either R21 or R25 fiberglass batts/rolls, I think.


----------



## themihai

Hey guys! I'm trying to build a baffle wall and right now I'm in the research phase.
For the front wall decoupling I would like to use clips with U/_Hat_ Channels. I'm not aware of any well regarded manufacturer in Europe so I found this [0] company ( Senor ) from Spain. Any idea if it's up for the job?
I'm a bit concerned as in their installation video [1] they seem to fail to decouple the wall from the floor and from the ceiling.They put some rubber clips at the top and bottom but they don't use it. The vertical U/HAT channels are coupling with the floor and the ceiling. Am I missing something?

[0] 3- 3802/03-TD1
[1]


----------



## nathan_h

Baffle wall is a completely different thing than decoupling the shell of the room from the rest of the building.

Are you looking for a company to do the installation or just a company to buy the supplies from?


----------



## themihai

nathan_h said:


> Baffle wall is a completely different thing than decoupling the shell of the room from the rest of the building.


 How different? I assumed they are very similar(sealed, decoupled multi-layer wall using constrained layer damping techniques) except on baffle wall you have an extra layer of sound absorbing material on the baffle wall.



nathan_h said:


> Are you looking for a company to do the installation or just a company to buy the supplies from?


Just for a reliable company to buy quality supplies from.


----------



## nathan_h

themihai said:


> How different? I assumed they are very similar(sealed, decoupled multi-layer wall using constrained layer damping techniques) except on baffle wall you have an extra layer of sound absorbing material on the baffle wall.


I may misunderstand what you are trying to do. If so, I apologize.

Traditionally, a "baffle wall" is a wall with speakers embedded in it.










Such a wall is NOT part of the shell of a theater, if the theater is designed as acoustically isolated. 

Rather, the wall is sitting WITHIN the shell of the acoustically isolated theater. Hence my comment that a baffle wall is a different piece of the puzzle than the acoustic isolation of the room.

That being said, yes, there can be damping, extra mass and a face of absorption on them when built well....which make them share some construction techniques with the shell of a theater. *But for the shell of the room to be effective as a method to acoustically isolate the room, the baffle wall is a completely separate item from the shell of the room.*




> Just for a reliable company to buy quality supplies from.


I apologize. I don't have specific experience with any of these companies but Saint Gobain has a good dealer finder tool on their web site for acoustic isolation products: Distributors and I believe Saint Gobain world wide headquarters is in France....

The one company the list near Paris seemed more interested in setting up recording studios, but this place in Belgium looks like a possibility?









Productgamma akoestische geluidsisolatie


Geluidsisolatie wil het lawaai of geluid van de bron, b.v.b een motor, gesprekken van anderen,.. tegenhouden.




www.akoestixproducts.be





AVS is quite USA-centric, as you may notice! And for general concepts, that is usually okay. But sometimes for gear and construction topics, this is a liability/challenge. You may want to search for some forums or discussion groups in Europe that focus on "home recording studios" to get good information about companies in Europe selling construction materials.


----------



## HTownTheater

Seeking advice... sorry for the long winded post but I'm trying to give you as many specific details as I can to my situation hoping it helps.

I've begun my home theater remodel and I'm second guessing my original plan (as many of us do) and wanted to get your feedback.


*Room location:*

Second story.
what is above it? attic shared with whole second story of home (although the immediate vicinity is the game room. bedrooms are on the other end of the floor.)
what is below it? master bathroom
what is beside it ? (using floor plan orientation attached):














top wall: attic that is above master bedroom
right wall: outside with windows
bottom wall: game room
left wall: two story living room (high ceiling) and this is a "double wall" although coupled that has air ducts running through it

I've also taken pictures of the room currently demoed that show you the studs.



























































*
Prior to removing the sheet rock and carpet I took the following sound measurements throughout the house:*









The attached table shows a few different test, the two to focus in on are the 90db full range noise (this is with front, center, right, and two 15" subs). then playing Tron legacy during the light cycle grid scene at -10 (in room peaks at 96db)

Both kids bedrooms had surprisingly good results 44-48db during full range pink noise that was barely noticeable unless you were really listening for it. During the Tron Legacy scene you could here nothing but the loudest peaks from the bass. As I mentioned, they are on the other end of the first floor. results were such that I could easily watch a movie at -10 and not disturb their sleeping (significantly better then my previous open theater). And I am perfectly happy with the room as is from these two locations, so anything added is just gravy.

The problem areas: main living room and master bedroom. Again, improved over my last home theater but not as good as kids bedrooms  Full range pink noise at 90db in theater measured 63-69db depending on location with the master bath directly below the theater being the worst, which bleeds sound to the master bedroom.

*
My Goals:*
I would like to see the full range pink noise under 48 in the master bath and master bedroom, this should give me a similar experience to kid1 and kid2 rooms. this is around a 20db improvement in these locations.


*Original plan, that I am currently at the beginning of and still time to correct if needed.*

Remove sheet rock from the three interior walls (highlighted in attached)
Leave half inch sheet rock (and insulation) currently on back wall and ceiling in place
Three highlighted walls:
use big stretch caulk to seal every nook and cranny I can find between the studs, ceiling plates, base plates etc.
remove all outlets from from inside the theater walls and run outlets either in conduit drops behind screen and in columns to be added after sheetrock. removing as many holes as possible
seal outlets that are in shared game room wall facing game room with putty packs and caulk gaps.
insulation (standard r13 or safe 'n sound not decided)
two layers of 5/8 type x heavy dry wall, caulking all seems and perimeter of first layer. 

Top wall:
you will see there is an attic access hole, I've re-framed this to be above where the future riser is and will build a semi permanent plug that will be removed in emergency access needs only not for attic storage use. construction method tbd, but likely osb and two layers of 3/4 mdf, screwed in place and caulked around. this will be covered by fabric panels in the end.

Back wall:
caulk around outlets and perimeter
add a layer of 5/8 type x heavy dry wall on top of existing 1/2"
build window plugs (construction tbd but inline with what many have done here)

ceiling
Caulk and fill all gaps along perimeter and around air ducts (AC guy left big wholes that will be patched and caulked.
Add layer of 5/8 type x heavy dry wall to ceiling
build backer boxes for all lights that will be installed.
fan will be removed, backer box installed over existing electrical box.

Floor:
1/2" horse stall mats (tractor supply company)
2 layers of 1/2 OSB glued and screw together floating not touching walls
caulk gap between floated floor and walls
raised threshold for door seal from game room
riser built on top of floating floor, not touching walls
carpet pad and carpet.

Door: 
1-3/4" solid core slab with seals and automatic door bottom
fill gap between studs and door jamb with rubber seal
run double 5/8 directly to door jamb
caulk

AC: move supply vents to back of room and add return with filter, all use long runs of insulated flex duct (already done) you can hear no noise through vents in the other rooms.

*Constraints:*

I'm really not willing to tare down or change the ceiling, the way they framed it is integral to the room. it does couple in via 2x6 ceiling joists that rest on the shared wall to game room, and the game room raised ceiling is framed in the same way. I also don't believe this is a weak point and could go with two additional layers of 5/8 instead of just one if recommend. But, am also curious in your feedback. here are some pics from inside room and from attic:


































You will see in my original plan there is no mention of green glue. the cost of green glue has sky rocketed. I estimated I would need 3 5 gallon buckets to do the walls, ceiling, floor lamination at a cost of ~$1200! This is higher then the sheetrock costs for the entire room!! but again, im curious in your feedback.

*Questions:*

will my original plan meet my goals (approx 20 db improvement in master bath/bed and living) or do I need more?
since I am not willing to tear down the sheetrock of the roof and decouple does it make sense to even consider decoupling the walls with clips and hat channel? If i did go this route I would take the extra step of removing sheetrock on the back wall so that all four walls got clips, channel, DD 5/8".
given the current price of green glue (3 5 gal buckets will cost me (~1200) which is more then all of the sheet rock for this build will cost (~$650)) I don't see how an additional $1200 is justifiable, and believe I would be better off spending the money decoupling without green glue, if i were to do anything additional, am I wrong?

If anyone actually reads this monstrous post and takes the time to understand it and give feedback, I will truly be thankful!!​​


----------



## warwwolf7

HTownTheater said:


> Seeking advice... sorry for the long winded post but I'm trying to give you as many specific details as I can to my situation hoping it helps.
> 
> I've begun my home theater remodel and I'm second guessing my original plan (as many of us do) and wanted to get your feedback.
> 
> 
> *Room location:*
> 
> Second story.
> what is above it? attic shared with whole second story of home (although the immediate vicinity is the game room. bedrooms are on the other end of the floor.)
> what is below it? master bathroom
> what is beside it ? (using floor plan orientation attached):
> 
> View attachment 3334246
> View attachment 3334245
> 
> top wall: attic that is above master bedroom
> right wall: outside with windows
> bottom wall: game room
> left wall: two story living room (high ceiling) and this is a "double wall" although coupled that has air ducts running through it
> 
> I've also taken pictures of the room currently demoed that show you the studs.
> 
> View attachment 3334260
> View attachment 3334259
> View attachment 3334257
> View attachment 3334258
> View attachment 3334262
> 
> 
> View attachment 3334256
> View attachment 3334261
> View attachment 3334255
> View attachment 3334254
> 
> 
> *
> Prior to removing the sheet rock and carpet I took the following sound measurements throughout the house:*
> View attachment 3334244
> 
> 
> The attached table shows a few different test, the two to focus in on are the 90db full range noise (this is with front, center, right, and two 15" subs). then playing Tron legacy during the light cycle grid scene at -10 (in room peaks at 96db)
> 
> Both kids bedrooms had surprisingly good results 44-48db during full range pink noise that was barely noticeable unless you were really listening for it. During the Tron Legacy scene you could here nothing but the loudest peaks from the bass. As I mentioned, they are on the other end of the first floor. results were such that I could easily watch a movie at -10 and not disturb their sleeping (significantly better then my previous open theater). And I am perfectly happy with the room as is from these two locations, so anything added is just gravy.
> 
> The problem areas: main living room and master bedroom. Again, improved over my last home theater but not as good as kids bedrooms  Full range pink noise at 90db in theater measured 63-69db depending on location with the master bath directly below the theater being the worst, which bleeds sound to the master bedroom.
> 
> *
> My Goals:*
> I would like to see the full range pink noise under 48 in the master bath and master bedroom, this should give me a similar experience to kid1 and kid2 rooms. this is around a 20db improvement in these locations.
> 
> 
> *Original plan, that I am currently at the beginning of and still time to correct if needed.*
> 
> Remove sheet rock from the three interior walls (highlighted in attached)
> Leave half inch sheet rock (and insulation) currently on back wall and ceiling in place
> Three highlighted walls:
> use big stretch caulk to seal every nook and cranny I can find between the studs, ceiling plates, base plates etc.
> remove all outlets from from inside the theater walls and run outlets either in conduit drops behind screen and in columns to be added after sheetrock. removing as many holes as possible
> seal outlets that are in shared game room wall facing game room with putty packs and caulk gaps.
> insulation (standard r13 or safe 'n sound not decided)
> two layers of 5/8 type x heavy dry wall, caulking all seems and perimeter of first layer.
> 
> Top wall:
> you will see there is an attic access hole, I've re-framed this to be above where the future riser is and will build a semi permanent plug that will be removed in emergency access needs only not for attic storage use. construction method tbd, but likely osb and two layers of 3/4 mdf, screwed in place and caulked around. this will be covered by fabric panels in the end.
> 
> Back wall:
> caulk around outlets and perimeter
> add a layer of 5/8 type x heavy dry wall on top of existing 1/2"
> build window plugs (construction tbd but inline with what many have done here)
> 
> ceiling
> Caulk and fill all gaps along perimeter and around air ducts (AC guy left big wholes that will be patched and caulked.
> Add layer of 5/8 type x heavy dry wall to ceiling
> build backer boxes for all lights that will be installed.
> fan will be removed, backer box installed over existing electrical box.
> 
> Floor:
> 1/2" horse stall mats (tractor supply company)
> 2 layers of 1/2 OSB glued and screw together floating not touching walls
> caulk gap between floated floor and walls
> raised threshold for door seal from game room
> riser built on top of floating floor, not touching walls
> carpet pad and carpet.
> 
> Door:
> 1-3/4" solid core slab with seals and automatic door bottom
> fill gap between studs and door jamb with rubber seal
> run double 5/8 directly to door jamb
> caulk
> 
> AC: move supply vents to back of room and add return with filter, all use long runs of insulated flex duct (already done) you can hear no noise through vents in the other rooms.
> 
> *Constraints:*
> 
> I'm really not willing to tare down or change the ceiling, the way they framed it is integral to the room. it does couple in via 2x6 ceiling joists that rest on the shared wall to game room, and the game room raised ceiling is framed in the same way. I also don't believe this is a weak point and could go with two additional layers of 5/8 instead of just one if recommend. But, am also curious in your feedback. here are some pics from inside room and from attic:
> 
> View attachment 3334274
> View attachment 3334275
> View attachment 3334255
> View attachment 3334255
> View attachment 3334254
> 
> 
> 
> You will see in my original plan there is no mention of green glue. the cost of green glue has sky rocketed. I estimated I would need 3 5 gallon buckets to do the walls, ceiling, floor lamination at a cost of ~$1200! This is higher then the sheetrock costs for the entire room!! but again, im curious in your feedback.
> 
> *Questions:*
> 
> will my original plan meet my goals (approx 20 db improvement in master bath/bed and living) or do I need more?
> since I am not willing to tear down the sheetrock of the roof and decouple does it make sense to even consider decoupling the walls with clips and hat channel? If i did go this route I would take the extra step of removing sheetrock on the back wall so that all four walls got clips, channel, DD 5/8".
> given the current price of green glue (3 5 gal buckets will cost me (~1200) which is more then all of the sheet rock for this build will cost (~$650)) I don't see how an additional $1200 is justifiable, and believe I would be better off spending the money decoupling without green glue, if i were to do anything additional, am I wrong?
> 
> If anyone actually reads this monstrous post and takes the time to understand it and give feedback, I will truly be thankful!!​​


Hi,

I would have a question for you. During your sound test, could you tell where most of the sound was coming from in your master bedroom? Ceiling? Wall? Door? 

If it's the ceiling, than maybe the place you should consider your weak point and invest more in would be your floor. There are other options that horse stall Matt with better efficiency, but your design will sure make a good difference. Most ht here are in the basement where sound escaping through the floor is barely a concern, but the ceiling is of most importance. You are somewhat lucky that no rooms are upstairs, otherwise you'd have to take care of you ceiling a little bit more. Maybe other members with more experience on floor sound insulation could chime in

The rest of the text consider that the sound leaking in your living room is not much of a concern. If its not the case, then your ht - ceiling might become the weak point. 

However, since the theater is above the room, I would suspect that the framing around your room is transmitting most of the sound to your master room.

If the bass resonates the walls in your ht because the drywall is coupled to your framing, the vibration goes to drywall to framing to framing of your room below, then the drywall of your room then the air of your room.
If you install hat and channel on the 4 walls but not on the ceiling, you are making the vibration flanking path longer.

It now has to go to your ceiling drywall the ceiling joist, then it will follow the path I described above. So it's an improvement. I don't believe your master bedroom will be affected by the sound leaking in the attic. The neighbors might. Some of the sound will still go through drywall on the wall, then the second layer, then hat and channel, and then framing, framing, masters bedroom's drywall but that will be reduced. 

If you had to choose between green glue and hat and channel, I would go with hat and channel without hesitation. To me green glue is really only the last item on the soundproofing item list if budget allows.

Domt under estimate what a good solid core door could do to help reduce the sound leaking into your master room 

For your double wall, you could avoid the hat and channel if it's not to solidly attached the walls on each side, but I doubt that the case. 

That's only my opinion, I'm no expert.

Envoyé de mon SM-G986W en utilisant Tapatalk


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## HTownTheater

warwwolf7 said:


> Hi,
> 
> I would have a question for you. During your sound test, could you tell where most of the sound was coming from in your master bedroom? Ceiling? Wall? Door?


for the master bath/bed: most comes through the floor (ceiling of the master bath) which you hear in the master bedroom. secound (but much more "subdued") would be the master bedroom wall. If I put my ear to that wall I can hear the sound traveling in it. but I believe that this is because sounds transfers from the floor joist to the master bedroom wall that they are resting on. which is why I knew i needed to make an investment in flooring materials even at a slight incoveniance of a rasied floor comming through the entrance.

For the living room: it was actually hard to tell BUT it seemed it was more flanking noise coming through the game room wall and hollow core door into the shared space vs just coming through the wall that is in the living room.

Thank you for the additional conversation. I am currently leaning towards clips & channel on all 4 walls since it wont be to much more work now that I am already to studs and seems to be well worth the investment on paper from an STC standpoint.

If you have better ideas on the floor please let me know as I know this is an area that must be addressed. I am following this guide from the soundproofing company but picked up on a suggestion that Big had with the 1/2" horse mats being more economical at the trade off of more height. I may not get the full 82 STC spec'd here since I'm not using green glue (maybe I should invest on floor at least?) and there is no insulation in floor. I don't know how easy it would be to pull sub-floor and insulate. looking at the sub-floor, it doesn't look strait forward and may have to actually be cut out since it goes under the framed walls and appears to be tung and groove.


----------



## warwwolf7

HTownTheater said:


> for the master bath/bed: most comes through the floor (ceiling of the master bath) which you hear in the master bedroom. secound (but much more "subdued") would be the master bedroom wall. If I put my ear to that wall I can hear the sound traveling in it. but I believe that this is because sounds transfers from the floor joist to the master bedroom wall that they are resting on. which is why I knew i needed to make an investment in flooring materials even at a slight incoveniance of a rasied floor comming through the entrance.
> 
> For the living room: it was actually hard to tell BUT it seemed it was more flanking noise coming through the game room wall and hollow core door into the shared space vs just coming through the wall that is in the living room.
> 
> Thank you for the additional conversation. I am currently leaning towards clips & channel on all 4 walls since it wont be to much more work now that I am already to studs and seems to be well worth the investment on paper from an STC standpoint.
> 
> If you have better ideas on the floor please let me know as I know this is an area that must be addressed. I am following this guide from the soundproofing company but picked up on a suggestion that Big had with the 1/2" horse mats being more economical at the trade off of more height. I may not get the full 82 STC spec'd here since I'm not using green glue (maybe I should invest on floor at least?) and there is no insulation in floor. I don't know how easy it would be to pull sub-floor and insulate. looking at the sub-floor, it doesn't look strait forward and may have to actually be cut out since it goes under the framed walls and appears to be tung and groove.
> 
> 
> View attachment 3334671


Your floor system will be a good improvement. I cant recommend any floor system because I need to get to work, but I saw avs members use other products, I wouldn't know about the cost or models. I'm sure you'll be able to find it. 

If you want to fill the floor joist cavity, maybe it's easier to do it from your room bellow and replace the drywall. Maybe the amount of work is less than removing tongue and groove subflooring...
There will be points in a project where the pain of doing something is not worth the reward. Maybe that's one.
There is a product that product that is blow insulation. If you want to fill the joist cavity, you could cut the middle section of your sebfloor let's 1 ou 2 feet wide(wide enough to make room for the blower conduit) and the length of your room. Remove that section of subfloor, blow insulation by pushing the conduit as far as you can in the joist cavity to fill the furthest point and pull the conduit as it gets filled. You could be blocked by the blocking in between the joist depending on where they are. Then reinstall the subfloor. 
Beware if you have recessed lights in your room bellow you might need to have the metal box around them or else you might burn your house down. That's code whenever you have recessed light and insulation I think anyway. 

You could also wait to hear the results of your soundproofing before filling the cavity. And If it's not enough, then remove the drywall in your master and fill the joist cavity 


Envoyé de mon SM-G986W en utilisant Tapatalk


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## Rodzilla

With modern thin LED lights what's the current best practice other than backer boxes? I've read Ted White's posts from long ago about using an octagon electrical box with a putty pad on the back but all the lights I'm seeing these days use flippers and have their own junction box - 

6 Pack Recessed Lighting 4 Inch with Junction Box, 5CCT 4 Inch Black LED Recessed Lights Dimmable 2700K/3000K/4000K/5000K/6000K, 9W 700lm Ultra Thin Recessed Lighting - ETL and Energy Star Certified https://a.co/92x2N01










Could I just cut a hole through the bottom layer of drywall and then cut a couple notches in the side for the flippers? Then I'd just run the small wire through the top layer of drywall when it goes up and bury the junction box behind it? Or can I just slap a putty pad on the back of the light itself before putting it up in a hole cut through both layers?


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## nathan_h

HTownTheater said:


> for the master bath/bed: most comes through the floor (ceiling of the master bath) which you hear in the master bedroom. secound (but much more "subdued") would be the master bedroom wall. If I put my ear to that wall I can hear the sound traveling in it. but I believe that this is because sounds transfers from the floor joist to the master bedroom wall that they are resting on. which is why I knew i needed to make an investment in flooring materials even at a slight incoveniance of a rasied floor comming through the entrance.
> 
> For the living room: it was actually hard to tell BUT it seemed it was more flanking noise coming through the game room wall and hollow core door into the shared space vs just coming through the wall that is in the living room.
> 
> Thank you for the additional conversation. I am currently leaning towards clips & channel on all 4 walls since it wont be to much more work now that I am already to studs and seems to be well worth the investment on paper from an STC standpoint.
> 
> If you have better ideas on the floor please let me know as I know this is an area that must be addressed. I am following this guide from the soundproofing company but picked up on a suggestion that Big had with the 1/2" horse mats being more economical at the trade off of more height. I may not get the full 82 STC spec'd here since I'm not using green glue (maybe I should invest on floor at least?) and there is no insulation in floor. I don't know how easy it would be to pull sub-floor and insulate. looking at the sub-floor, it doesn't look strait forward and may have to actually be cut out since it goes under the framed walls and appears to be tung and groove.
> 
> 
> View attachment 3334671


In general the soundproofing company quantifies the different approaches so you can see what different approaches achieve….and you can make sure you are not creating awesome walls and a crappy ceiling, ie, a bucket with holes that lets the water out. STC isn’t a perfect measure. But using a design for each part of the room with a similar STC is usually the best approach. In many cases they also publish data showing more specifics about performance than a single STC number, and paying attention to bass frequencies can be very useful. 

Especially with bass


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## batlin27

batlin27 said:


> Have an issue with my build and would like to open to broader audience. Cross posting from my build thread
> Basically, do I omit the serenity Mat and 3/4OSB sub floor to bring fix this issue (and save some cash at the same time) or do I lower my riser by a half inch by using a 2x4 on end and a 2x4 on its side...
> 
> I will be doing double stud walls with .5-1" airgap and double 5/8 dry wall. My room shares the screen wall with the exterior, one side is garage, other side is a closet and the rear wall shared with pantry. I am not going full Monty on sound proofing, but just trying to add some to help reduce sound across the house.
> 
> ----
> 
> Slab was poured on Friday and I went out today to take a look and do some measurements. I am a little upset because although I requested an 8" slab drop, the actual slab drop is 7 3/8" which really screws with a lot of things. I am up for some suggestions here
> Originally I had planned
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Which would have been flush with the rest of the house and allow for a seamless transition between theater and hallway. So now I will have a 5/8" higher theater than the rest of the house. Only thing I can think of is rather than using a 2x6 on end (5.5" nominal) I will need to use a 2x4 on end (3.5") + a 2x4 on its side (1.5") to get my self to a 7.5" drop.
> 
> Blue pipes are conduit to AV closet to be able to run usb cables, calibration microphone etc. and of course they are sticking into the room a little more than I would like....
> 
> Any thoughts?
> Other than that, the slab looks great


Cross posting here from my build thread for more visibility


Revisiting this topic. we are getting close to drywall and then it will be time for the risers / stage.

I had originally decided not to do the Serenity Mat / Rubber Mat + OSB and just build on the slab. There was another thread on here about Bass disturbing a neighbor Need Help with Bass traveling to neighbor's house

Would having a Rubber Mat help at all with transfer of Bass energy to my neighbors?
The exterior wall where by subs will be will be about 30' from my neighbors house.

If I stand up a 2x6 + 2 layers of OSB for the platform top that will give me a height of 6.9" and a step of about 1/2" to the main house.
Which should I do
Options
a) Just build the stage on the slab and have builder make it work - *No Cost*
b) 1/2" Rubber Mat + 2x6 (5.5") + 2 Layers OSB (1.4") which would put my at ~7.4" and match the entrance step nearly perfectly. This would then have Carpet Pad on top and then Carpet (NO OSB Subfloor) Slab + Rubber + 2x6 + 3/4 OSB + 3/4 OSB - ~*$2K*

Thoughts / Advice?
BTW I am looking at U.S. Rubber Acoustical Underlayment


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## nathan_h

Ted from the Soundproofing company told me it wasn't worth adding anything special to a slab, as long as the floor on top of the slab isn't attached to the walls, that was adequate. (I am paraphrasing, but in my case his conclusion was that Serena mat didn't add a lot of value for my room, which is on a concrete slab, even though I am doing double walls and a completely decoupled ceiling. The likely weak point will still be the doors, even though they are double doors, ie, communicating doors, and not the floor, apparently.)


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## madtapper

nathan_h said:


> Ted from the Soundproofing company told me it wasn't worth adding anything special to a slab, as long as the floor on top of the slab isn't attached to the walls, that was adequate. (I am paraphrasing, but in my case his conclusion was that Serena mat didn't add a lot of value for my room, which is on a concrete slab, even though I am doing double walls and a completely decoupled ceiling. The likely weak point will still be the doors, even though they are double doors, ie, communicating doors, and not the floor, apparently.)


Similar situation here, and am curious about "order of operations." I have a slab but don't know which assembly to build first to achieve the room within a room. Is it walls then ceiling then floor?


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## batlin27

nathan_h said:


> Ted from the Soundproofing company told me it wasn't worth adding anything special to a slab, as long as the floor on top of the slab isn't attached to the walls, that was adequate. (I am paraphrasing, but in my case his conclusion was that Serena mat didn't add a lot of value for my room, which is on a concrete slab, even though I am doing double walls and a completely decoupled ceiling. The likely weak point will still be the doors, even though they are double doors, ie, communicating doors, and not the floor, apparently.)


Thank you Nathan, I just wanted to make sure that this was the case and it didn't make sense.

Thanks!


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## Black hole son

!


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## nathan_h

madtapper said:


> Similar situation here, and am curious about "order of operations." I have a slab but don't know which assembly to build first to achieve the room within a room. Is it walls then ceiling then floor?


Well, you have to build the ceiling sitting on the walls so the ceiling comes after the walls….

But whether you build the walls onto the slab or a floating floor depends a bit it seems.

In my case, I don’t have a floating floor so the answer was easy.


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## nathan_h

Ekimtoor1 said:


> I couldn’t find “new post”, I only find “post a reply” at the end of the thread. Please tell me if I did it wrong. Thanks! I'll post my question anyway.
> 
> I have built a 7’x9’x8’ room-in-a-room in the corner of my garage on slab. The house is built on the same slab.
> 
> It’s constructed of 2”x4” framing 24” on center on the walls and 16” on the ceiling. Two layers of 5/8” drywall with green glue are installed all four walls, ceiling and roof inside and out.
> 
> One wall faces a concrete block outside wall and another wall faces an inside BR wall. There is a two inch air gap between the room and these walls. There is an 18” air gap between the roof and the garage ceiling.
> 
> The door is constructed the same as the walls and weighs 300 pounds. Without clouding my current question, let me leave the details of how the door works out of it for now. It’s a great door, seals tight and works well.
> 
> My result is very good except for one shortcoming. There is quite a bit of low end leak through the BR wall. A 100db sound source in the room leaks about 45db of mostly low frequencies into the BR.
> 
> How could I improve this problem?


Hard to picture what you have done but I would guess that the slab and the door are the weak points, without seeing pictures of the construction.…. But that is just a guess.

And I guess it should be said that 100db for anything more than a short quick period is unhealthy. Movie refence level is 85db average and most people find that painful and intolerable fete a while, since peaks can reach 105db. So I’d be surprised if you really want to play 100db content much.

But even so, 45 db of sound in another room as a max is darn close to the normal domestic room background noise which is in the 30s….punctuated by traffic noise, neighbors, etc, that raises background sound into the 40s, right? ie, someone can tell there is something going on at that level, in the background, but not what it is, kind of like traffic outside, right?


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## Black hole son

!


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## nathan_h

Ekimtoor1 said:


> Hey thanks for the reply. I’m sure you’re right about the door and the slab but you gotta have a door and I’m not clear on just how much travel there is through a slab. I thought of adding some neoprene under the plate and building a multilayered floor of some kind. I just don’t want to do a bunch of stuff that won’t be worth it.
> The room is for a drum kit which will be over 100db in such a small space, but I’ll be wearing headphones.
> the leak in the BR is all low end so even though it’s only 45db, it’s enough to piss off my granddaughter. So I’m hoping to find some changes I could make to reduce the low end leak.


Bass drum is usually about 50hz, so MAYBE adding a floating floor (slab -> rubber mat -> plywood) will help a bit. But I cannot say that with confidence. 

I'm not clear on your wall construction. Did you build a 2x4 shell and put double dry wall and green glue on BOTH sides of the 2x4 stud wall? If so, then this idea wont work, but if not, then building a second 2x4 stud wall, an inch outside the current one, and a second ceiling, resting on that second wall, will attenuate the sound even more....

...But this assume the door is not the weak link. If you have a single door, I would look into building communicating doors, like an airlock. (I'm assuming you have gaskets on the door.)

But I'm just spit balling. Key details about the construction of the existing room are not clear to me from your description. Photos would help to clarify. And when you say that "bass" is the problem, it would be really good to figure out what frequencies are the issue, using test tones.


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## Black hole son

!


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## nathan_h

Ekimtoor1 said:


> Thanks again for the input.
> 
> Yes, two layers of 5/8” with GG in between, all around inside and out. It is a continuous envelope. The bays of the frame are filled with rock wool. Both layers were sealed with acoustic caulk. I didn’t put GG on the studs themselves because GG says there is no value in doing so. This one of the recipes that GG recommends and they publish lab data to support it. The room has a two inch air gap on the two walls it is facing. I think it was Sound Cow that told me a 1” gap would be enough to decouple the room, so I doubled that.
> 
> The build is finished, so I can’t do a double wall and even if I could, I don’t have room. I literally have only a 7x9 space to work with. A double wall would reduce my drum bubble to a vocal booth and I don’t sing very well.
> 
> I can add an interior door, but I’m working these other details first. I haven’t yet tested specific frequencies. Just my ears for now.


Yeah, I can only speculate. Its not clear to me what the weak link is for sure. Assuming the shell is the shell, and no construction there is appropriate, that leaves just tinkering with the door (ie, a second door) or the floor. But before doing those, figuring out if those are going to make a difference is key, and I am not knowledgable enough to predict that with 100% accuracy without measurements. 

I suppose it is even possible that adding a layer of mass or insulation to the outside of the shell could help. 

Maybe someone else can guess better than me, without measurements.


----------



## Black hole son

!


----------



## jkboatman

Hello all - I'm building a basement theatre area and appreciate some feedback on my thoughts to try to reduce noise coming from the room above.

In order to maximize ceiling height, I am opting to not include a drywall nor drop ceiling. Instead I plan to spray black paint on the underside of the subflooring overhead and floor joists/plumbing. The room above is hardwood floors on top of plywood subfloor and I'd like to attempt to reduce the sound transmission between the theatre and room above. Would it be worthwhile to install 14.5" wide strips of drywall to the underside of the subfloor (between the floor joists) using Green Glue? I've never used the stuff before, not sure what I could expect.

Any other ideas on things I can try to reduce the noise transmission? I'm mainly interested in higher frequency mitigation (ie human voice, not too worried about LF from the subwoofer).

Thank you!


----------



## nathan_h

jkboatman said:


> Hello all - I'm building a basement theatre area and appreciate some feedback on my thoughts to try to reduce noise coming from the room above.
> 
> In order to maximize ceiling height, I am opting to not include a drywall nor drop ceiling. Instead I plan to spray black paint on the underside of the subflooring overhead and floor joists/plumbing. The room above is hardwood floors on top of plywood subfloor and I'd like to attempt to reduce the sound transmission between the theatre and room above. Would it be worthwhile to install 14.5" wide strips of drywall to the underside of the subfloor (between the floor joists) using Green Glue? I've never used the stuff before, not sure what I could expect.
> 
> Any other ideas on things I can try to reduce the noise transmission? I'm mainly interested in higher frequency mitigation (ie human voice, not too worried about LF from the subwoofer).
> 
> Thank you!


If you are trying to stop the sound of people walking and talking, I'd consider something like:

1. On the floor above, some people add area rugs, ideally with thick pads. It won't make a big difference, in my experience, but if you have some rugs already that you can test with, you might find it helps a bit. Really the best solutions would involve rebuilding the floor: Soundproofing A Floor

2. On the ceiling, if you really want to leave the joists exposed, you don't have a ton of options. But yes, adding mass to the ceiling between the joists may help a little bit. But only just a little bit from what people say, ie, you will still hear everything, it will just be a little less loud. If you are serious about getting good results, then you'd want to put insulation batts up there, and do hat channel+clips, and add drywall, probably dual layers with damping between them if you are already going to all this effort: Soundproofing a Ceiling


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## Black hole son

*


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## squared80

Ekimtoor1 said:


> I don’t think installing drywall between the joists will get you much. Sound will transmit right through them in both directions.


Incorrect.


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## Black hole son

*


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## Rodzilla

For a clips and channel install does it matter if the channels make contact with each other in the corner?


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## Rjloper9

Rodzilla said:


> For a clips and channel install does it matter if the channels make contact with each other in the corner?
> 
> View attachment 3347187


My only concern would be the slight possibility of them rubbing and creating some sort of audible “squeak.”

Can you put horizontal blocking between vertical studs on one side and attach to that instead?


Ryan


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## Coreybrawner

Can anyone please provide guidance for best steps to "soundproof" a standalone workshop to prevent sound outside the shop as much as possible? I fully understand some differences between a theater setup vs. a workshop, namely, I will be fastening some cabinets etc., to walls and cannot use decoupling strategies. In addition to carefully sealing the room, I was thinking double-layered dry wall would help. Does anyone have experience adding a layer of something like MLV between the dry wall layers, or other ideas to most effectively deaden sound that would "lead" outside the shop?


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## nathan_h

Coreybrawner said:


> Can anyone please provide guidance for best steps to "soundproof" a standalone workshop to prevent sound outside the shop as much as possible? I fully understand some differences between a theater setup vs. a workshop, namely, I will be fastening some cabinets etc., to walls and cannot use decoupling strategies. In addition to carefully sealing the room, I was thinking double-layered dry wall would help. Does anyone have experience adding a layer of something like MLV between the dry wall layers, or other ideas to most effectively deaden sound that would "lead" outside the shop?


I would go with a double STUD wall. I have seen abysmal results from simply putting up two layers of drywall. Before doing that, I would prefer a staggered stud wall, if a double stud wall is not viable. And remember, the CEILING should be separated from the building exterior, as well (ie, not attached to the outside walls and roof) to be effective. 

This is a good video about the techniques.


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## Rodzilla

For a dead vent exterior to the theater room, how should the inner vent be connected through the double drywall to the outer dead vent box? Won't cutting a hole and running just a standard duct allow for sound to leak through the duct into the stud bay before the dead vent can do its job?


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## nathan_h

I haven't done a dead vent myself, but I am interested in this question. The illustrations and example builds I have seen show the dead vent directly abutting the room....so it's not just standard flex duct but flex duct surrounded by insulation, surrounded by a box.

eg:


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## samk1244

Hello,

I am currently in search of a condo apt where I can play music at reasonable volumes without disturbing my neighbors.

When I go to see a unit, here's what I'm looking for:


live on first floor (no neighbour's below)
concrete everywhere (floors, ceilings, walls)
if walls are drywall, consider adding an extra layer of drywall with green glue
if possible, contact residents to ask about their experiences with noise transfer

I'd appreciate any feedback / advice you can provide me in my search.


----------



## nathan_h

samk1244 said:


> Hello,
> 
> I am currently in search of a condo apt where I can play music at reasonable volumes without disturbing my neighbors.
> 
> When I go to see a unit, here's what I'm looking for:
> 
> 
> live on first floor (no neighbour's below)
> concrete everywhere (floors, ceilings, walls)
> if walls are drywall, consider adding an extra layer of drywall with green glue
> if possible, contact residents to ask about their experiences with noise transfer
> 
> I'd appreciate any feedback / advice you can provide me in my search.


1. Helpful
2. Useful
3. Won’t really help
4. Fine data

Consider investing in good headphones for late night listening sessions……


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## samk1244

nathan_h said:


> 1. Helpful
> 2. Useful
> 3. Won’t really help
> 4. Fine data
> 
> Consider investing in good headphones for late night listening sessions……


Thanks for your suggestions! My plan is to find a unit that checks all the right boxes, and if my neighbour's still complain, I'll switch to headphones.

Based on your response to 3, should I not consider any unit with a shared drywall? There is on unit in particular where the sidewalls are drywall, but the size of the space is larger than the concrete units I am considering (22 foot width vs 15 foot width)


----------



## nathan_h

samk1244 said:


> Thanks for your suggestions! My plan is to find a unit that checks all the right boxes, and if my neighbour's still complain, I'll switch to headphones.
> 
> Based on your response to 3, should I not consider any unit with a shared drywall? There is on unit in particular where the sidewalls are drywall, but the size of the space is larger than the concrete units I am considering (22 foot width vs 15 foot width)


Concrete isnt perfect. Bass can actually travel through it well in some cases. 

But in almost all instances it is going to better than what you can do with drywall, I suspect.

Certainly in my experience, even if you completely tear out the drywall, and build a new second 2x4 wall separated from the old studs by an inch, and then put dual layers of drywall and green glue on it.....the concrete wall is likely to more effective, in my experience. 

I suppose this may not be true in all cases, and it partly depends on what the OTHER walls, the floor and the ceiling are doing, since sounds can travel around a wall etc.

I would be curious to hear about what other people think.


----------



## cavitycr33p

Random question, and I've seen various answers, so I need a bit of clarity before I start in the spring haha. 

I'm doing room inside a room for walls, hat channel/clips for ceiling. Am I right in believing that the new walls drywall should not come in contact with the new ceiling drywall (on channel/clips) at all, and just caulk the space in between? Thank you in advance!


----------



## mhutchins

cavitycr33p said:


> Random question, and I've seen various answers, so I need a bit of clarity before I start in the spring haha.
> 
> I'm doing room inside a room for walls, hat channel/clips for ceiling. Am I right in believing that the new walls drywall should not come in contact with the new ceiling drywall (on channel/clips) at all, and just caulk the space in between? Thank you in advance!


Correct! In general, you don't want drywall touching at any of the intersections, including walls, floor, ceiling, door frames, window frames, etc. Larger gaps should be stuffed with foam backer rods and then caulked while smaller gaps only need the caulk.

Don't forget to seal beneath the bottom plates for your walls as well. For new walls, consider using both sill plate gasket material as well as caulking the mating surfaces to ensure an airtight seal.

Mike


----------



## aaron186

Putting my theater into an already finished room that was built by builder with nothing special done to it. I’m building a riser decoupled from wall. Is there anything else simple I can do that doesn’t involved removing all of my dry wall?


----------



## squared80

aaron186 said:


> Putting my theater into an already finished room that was built by builder with nothing special done to it. I’m building a riser decoupled from wall. Is there anything else simple I can do that doesn’t involved removing all of my dry wall?


Not really, no. You can put another layer of drywall up with Green Glue between the sheets, but you've still got swiss cheese cutouts all around the room with outlets, HVAC, switches, lights, etc., so may not be worth the price of admission.


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## nathan_h

Yeah that second layer of drywall on a conventional wall won't do much and I wouldn't bother. I was recently in a room like that with two extra layers on drywall on a conventional wall, and one could still readily hear through the wall.

For an existing room like that, the weakest link is almost always the door. (I'm not saying the walls aren't a problem but that they aren't the worst problem, and they are very hard to fix without a substantial amount of demo and rebuilding.). But you can help things a bit by using a solid core door, with gaskets around it. It won't solve bass rattling outside, but will help with higher frequencies more than any other single thing, in my experience.

And if the room was created with IN WALL speakers, you will help things by removing those in wall speakers and at least creating backer boxes for them -- but, better yet, just drywall the holes and use in room or on wall speakers instead. (You could even re-use the in wall speakers if you build a column in the room to house them.)


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## aaron186

squared80 said:


> Not really, no. You can put another layer of drywall up with Green Glue between the sheets, but you've still got swiss cheese cutouts all around the room with outlets, HVAC, switches, lights, etc., so may not be worth the price of admission.


 The room is upstairs. I’m more worried about sound leaking downstairs. Would something on the floor help before I carpet?


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## squared80

aaron186 said:


> The room is upstairs. I’m more worried about sound leaking downstairs. Would something on the floor help before I carpet?


You're mainly talking about lower frequencies, so not really. But higher frequencies can be easier to tame in a room, keeping in mind that HVAC and doors can be the biggest issues.


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## aaron186

squared80 said:


> You're mainly talking about lower frequencies, so not really. But higher frequencies can be easier to tame in a room, keeping in mind that HVAC and doors can be the biggest issues.


So just save my money or redo the whole room basically? Thanks for the advice


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## nathan_h

aaron186 said:


> So just save my money or redo the whole room basically? Thanks for the advice


Yeah that's probably the safest route. To get more ideas, you would need to post some good photos of the existing room, including the door, and diagrams of what is around it (ie, the rooms you are worried about getting sound into), as well as some audio measurements from outside the room when test signals are played inside the room.

That data would help to pinpoint problem areas and opportunities to improve things -- if there are any.

A betting person would estimate that the door is the single biggest opportunity to improve things, in the "under $1,000 range".

The other opportunity to improve things: If you have "in wall" speakers, remove them from the walls and close those holes.

Finally, you didn't mention what kind of subwoofers you have and how you are handling bass management. Assuming the subwoofers to all the bass work (ie, all speakers are set to "small" in your system) then using isolation feet on the subwoofers can help reduce vibrations being physically transferred to the floor/structure.

So, if your budget is under $10k, the above items are what I would look at (and they won't cost that much but I use that number because any steps above what I describe would cost a lot more).

----

In my old house, I had a similar issue. I realized that watching movies when people were awake and or with other household members meant it didnt really matter if it was noisy elsewhere in the house. That is, sound isolation/"proofing" didn't matter too much.*

The issue was when watching late at night, when other people had gone to sleep, I could not turn my system up the way I wanted. So.......I got a killer pair of headphones. It worked great. And these days, with the virtual surround systems like what Apple has created, it sounds even better.



-----
*Sound "proofing" is not just about sound escaping the room. But since that is what you are asking about I am just talking about that aspect. The older I get the more I realize keeping sound OUT of the room is one of the most important aspects to high fidelity. But that's not what you are working on here.


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## mhutchins

nathan_h said:


> .
> .
> .
> The issue was when watching late at night, when other people had gone to sleep, I could not turn my system up the way I wanted. *So.......I got a killer pair of headphones.* It worked great. And these days, with the virtual surround systems like what Apple has created, it sounds even better.
> .
> .


This!!

I had a good pair of headphones with an open back design, but my wife still complained about the noise when I was using them in the open loft over our living room. I ended up buying a decent pair of closed back headphones and I've been pretty happy so far and they have a much higher WAF!

Mike


----------



## nathan_h

mhutchins said:


> This!!!
> 
> 
> 
> This!!
> 
> I had a good pair of headphones with an open back design, but my wife still complained about the noise when I was using them in the open loft over our living room. I ended up buying a decent pair of closed back headphones and I've been pretty happy so far and they have a much higher WAF!
> 
> Mike


Those are good cans. If you use an AppleTV for your source, I can highly recommend trying their headphones (especially the over the ear ones) with the spatial audio and head tracking. It is so realistic, I sometimes wonder whether I have accidentally left the speakers on when the movie starts up. (After that, it is not going to full a home theater buff into thinking they are listening to their main system....but it is so much more satisfying that listening to a quiet home theater turned down to avoid disturbing other people. WAAAY more satisfying.)


----------



## Sakic

Hi - I’m wondering if I install velvet for light treating overtop of those acoustic sound dampening drywall pieces and mount them to my exiting drywall/roof will there be the same advantages?

my theatre build is in my profile; I have no acoustic treatment currently and no light treating so trying to kill two birds with one stone (and with little construction).


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## ambesolman

nathan_h said:


> Those are good cans. If you use an AppleTV for your source, I can highly recommend trying their headphones (especially the over the ear ones) with the spatial audio and head tracking. It is so realistic, I sometimes wonder whether I have accidentally left the speakers on when the movie starts up. (After that, it is not going to full a home theater buff into thinking they are listening to their main system....but it is so much more satisfying that listening to a quiet home theater turned down to avoid disturbing other people. WAAAY more satisfying.)


Is there any way to do this but keeping your subs or even transducers active at the same time? It’d be cool to have some tactile feedback to go along with it.


Sent from my iPhone using Tapatalk?


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## nathan_h

Sakic said:


> Hi - I’m wondering if I install velvet for light treating overtop of those acoustic sound dampening drywall pieces and mount them to my exiting drywall/roof will there be the same advantages?
> 
> my theatre build is in my profile; I have no acoustic treatment currently and no light treating so trying to kill two birds with one stone (and with little construction).


That stuff does neither thing particularly well, from the measurements I have seen.

Assuming this is your build thread (Dedicated Room (pre-built) - Slowly Converting to Full...) I would say:

Nice space. Good use of screen to room ratio.

Sound "proofing" is not an option without major re-work. But if you haven't got a solid core door with at least some weather stripping, that might help a little.

On the other hand, acoustic treatment to improve the sound inside the room is totally doable. There are some great threads about that. (This thread isn't one of them.). A simple set of eight 2'x4'x4" fiberglass or rock wool panels on the walls in there, and something thicker in the open space behind the screen, would likely make a world of difference.


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## nathan_h

ambesolman said:


> Is there any way to do this but keeping your subs or even transducers active at the same time? It’d be cool to have some tactile feedback to go along with it.
> 
> 
> Sent from my iPhone using Tapatalk?


Keeping the subs active would completely defeat the purpose. Bass waves would travel longest and most annoyingly throughout the house.

Transducers like a butt shaker, on the other hand, I have ready about people using with headphones. But I haven't tried it and don't know much about how well it works. But if I was using headphones frequently, I would look into it. Seems like it MIGHT work well.


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## Sakic

nathan_h said:


> That stuff does neither thing particularly well, from the measurements I have seen.
> 
> Assuming this is your build thread (Dedicated Room (pre-built) - Slowly Converting to Full...) I would say:
> 
> Nice space. Good use of screen to room ratio.
> 
> Sound "proofing" is not an option without major re-work. But if you haven't got a solid core door with at least some weather stripping, that might help a little.
> 
> On the other hand, acoustic treatment to improve the sound inside the room is totally doable. There are some great threads about that. (This thread isn't one of them.). A simple set of eight 2'x4'x4" fiberglass or rock wool panels on the walls in there, and something thicker in the open space behind the screen, would likely make a world of difference.


Okay - yeah I’ve been looking at those as well. I’m just needing to figure out a way to attach the velvet to the walls so seeing if I can save myself some extra effort.


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## Mr.337

just trying to finish up the room in my new house. I told contractors I wanted a double wall on the back wall of room. I'll have 2 solid doors for the walls. Im also going to do rsic clips and hat channels with 2 sheets of 5/8 sheetrock and green glue on the staggered stud wall.

I know this isn't what I was supposed to get for a 24oc staggered stud wall but I'm thinking less is better?

The rsic clips show 48" oc horizontal which is what the studs measure and ill add extra vertical clips instead. 

My main question is do I need to add more studs on the 24oc wall if I only am hanging the 2 sheets drywall and nothing ever else from that wall?


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## nathan_h

That's interesting. Yes, many clip installation guides show 48" between clips, but they are sometimes staggered and assume 24" spacing....which you have BUT sicne it is staggered half the studs are not "reachable".

I would ask the manufacturer of your particular clips and channels about this. 

In the absence of their guarantee that it will work, I woud ask your contractors to build out those recessed studs, to be safe.

But hopefully someone here has done what you propose and can tell you it works fine! (I can't. Hence my answer errors on the safe side.)


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## BobParmala

Hello. Building a new room in the basement for kids to hang out, nice movie watching (not a HT purist) and playing games / D&D with buddies without disturbing the rest of the house. Approx. 10.5' x 22'. Epoxied & sealed concrete floor to joist is 9ft (108"). Metal studs, using IB-1 clips, and 25 gauge hat channel. I'm planning to do the "level 2" ceiling from www[.]soundproofingcompany[.]com/soundproofing-solutions/soundproofing-ceilings

Tl; dr ( insulate between joists, IB-1, hat channel, 5/8" drywall [DW], GG, 5/8")

3 of the 4 walls are against basement walls below grade. 10" block, rebar, and concrete poured in the spaces. Vapor barrier, 2" XPS foam board. I didn't plan to decouple those, but will double up the 5/8 and GG. The wall facing the steps to the main section of the house will have IB-1, DW, GG, DW.

I really want some ceiling lights and have been eyeballing the thin 4" or 6" LED lights that take the place of cans. As such, I'm strongly considering putting a drop ceiling BELOW the drywall ceiling just for the lighting and hide some cable runs that will occur over time. Plenty of space to still have an 8ft ceiling (for VR arm waving).

My question is- what's the best way to anchor the drop ceiling support wires to the joists/hat channel/drywall above? Will I lose a considerable amount of STC rating by anchoring the eye bolts into the joists ( through the DW/GG/DW), essentially nullifying any STC gains by the expensive GG?

Thanks!


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## nathan_h

I would shoot for the hat channel and not the joists, just to be safe. I have seen people hang even heavier stuff from a decoupled ceiling so hopefully someone can chime in, or you can find examples in the build threads. 

But taking a step back: you didn’t mention what the walls are like. If the walls are not decoupled from the rest of the building, then it may not matter how careful you are on the ceiling, anyway.


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## BobParmala

nathan_h said:


> I would shoot for the hat channel and not the joists, just to be safe. I have seen people hang even heavier stuff from a decoupled ceiling so hopefully someone can chime in, or you can find examples in the build threads.
> 
> But taking a step back: you didn’t mention what the walls are like. If the walls are not decoupled from the rest of the building, then it may not matter how careful you are on the ceiling, anyway.


Thank you! Post updated with wall info. Pics coming soon.


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## nathan_h

I would be more worried about clips and hat channels for the walls. If you aren't doing that on the walls, then I'm not sure how much difference it will make on the ceiling, since the wall framing directly touched the ceiling joists.


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## NTT0101

Hello everyone. First post here.

I wonder if this is possible to completely isolate this closet for vocal practice. I wouldn’t be playing music…only practice vocals… so that is the specific grange I need to isolate. I am rather loud when I sing and often belt when performing

I am the owner of the home and do not care if I end up with a tiny 3x4 ish room. I just want to be sure that it isn’t possible to hear me from the outside. This is the whole point so I cannot settle for much less.

My home is a typical 2x4/drywall constructed house on a concrete foundation.

Think it’s doable? What kind of budget am I looking at? Any suggestions or advice would be welcome.

NOTE: I cannot get Sonopan. I live in US


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## nathan_h

NTT0101 said:


> I just want to be sure that it isn’t possible to hear me from the outside.


At all? 

I'm not sure what that would take. Usually the goal is to reduce sounds.

What's the budget?

Are you going to do the construction yourself or hire it out?

The soundproofingcompany.com has some good construction instructions.


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## NTT0101

Sudden news change for me which makes my whole post pointless. 

I will bow be getting a shed from another property of mine that is 6x8. All I have to do is replace the door, delete some windows, insulation and drywall. I can place the shed ~50 ft from any ears. 

I think green glue, 2nd drywall layer, and maybe MLV. Should provide more than my needs


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## NTT0101

Something I am having trouble with is actually determining the best/optimal materials for exclusively the human vocal range. I don’t care about bass frequencies and I’m no soprano.

My actual vocal range is from about 100- 6/700 hz. 

Thoughts?


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## nathan_h

Six inches of fiberglass or rock wool should do the trick. Any material listed with greater than 1.0 absorption coefficient at 125hz will like do just fine. 



https://www.bobgolds.com/AbsorptionCoefficients.htm



Cover it in something like muslin to make it look nicer and contain any fibers.

The rigid insulation panels are easier to work with, but may require you go to an HVAC supply company since Home Depot and similar stores seldom carry it.


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## Stbby

I’m aiming to soundproof the ceiling of my 1300 sq ft open floor plan basement without covering up the ceiling joists, as adding drywall in the standard way reduces the ceiling height too much and makes the space feel super claustrophobic. My understanding from one soundproofing contractor is that if I cut two sheets of 5/8 drywall to fit between the joists and do a green glue sandwich, I should be able to get a good reduction in noise transfer. What I’m a lot less clear on are all the edge cases: what are my options when there’s HVAC stuff in the between-joist spaces? What are my options for the area around the one room that DOES have a drywall ceiling, the bathroom? Are there soundproofing professionals (or experienced DIYers) I could hire just to help give me detailed guidance on all those edge cases? I’m thinking of spending the next month or two doing this project mostly full time and I don’t want to make huge mistakes via ignorance. Thoughts on how to get the right information/guidance?


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## nathan_h

Stbby said:


> I’m aiming to soundproof the ceiling of my 1300 sq ft open floor plan basement without covering up the ceiling joists, as adding drywall in the standard way reduces the ceiling height too much and makes the space feel super claustrophobic. My understanding from one soundproofing contractor is that if I cut two sheets of 5/8 drywall to fit between the joists and do a green glue sandwich, I should be able to get a good reduction in noise transfer. What I’m a lot less clear on are all the edge cases: what are my options when there’s HVAC stuff in the between-joist spaces? What are my options for the area around the one room that DOES have a drywall ceiling, the bathroom? Are there soundproofing professionals (or experienced DIYers) I could hire just to help give me detailed guidance on all those edge cases? I’m thinking of spending the next month or two doing this project mostly full time and I don’t want to make huge mistakes via ignorance. Thoughts on how to get the right information/guidance?


I don't think you'll get a good reduction in noise transfer except perhaps for things above the human vocal range. Most dramatic movie content will vibrate right through that drywall mass, in my experience.

Assuming you are going to buy some materials from them, the soundproofingcompany.com will probably answer some questions for you. And they have some excellent guides on their website for free.


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## KPS2525

Lots of good info in this thread. So far, I've read pages 150-212 (exhausted). It's given me a good idea of what I need to do for a basement space with concrete walls/floor in order to try and contain the sound as best I can. Main concern (as with most) is bass traveling throughout the house. We won't be listening at really loud levels.

Plan to decouple the ceiling with clips/channel...Walls decoupled from ceiling joists with clips...DD+GG throughout. Here are a few questions I have about what I've read so far.

1) If you only had 2.5" of space below the ceiling joists to work with for installing a ceiling system, what is the best compromise? The ideal RSIC clip/hat channel, 5/8 DD+GG comes in at just under 3". I could use the non-rubber clips that are lower profile, but I gather those are much less effective. I've also come across these clips that seem like they could be installed higher up in the joist and take off a half inch or so. My builder is suggesting clips/channels, MLV, 1 layer drywall....but man that MLV is pricey and I'm not sure of its effectiveness after reading through this thread.

2) Is there any additional benefit to putting DD+GG up between the ceiling joists against the subfloor...outside of reducing footfall noise? I am not concerned about footfall noise coming into the basement, but would consider this if it had any marginal benefit to keeping bass from escaping the basement (guessing it doesn't).

3) My flooring will be luxury vinyl (product includes a small cork backer) applied over a thin vapor barrier directly on the concrete floor. Given that I'm not really isolating the room from the concrete floor, does installing a rubber membrane (eg. horse cargo mat) under the base plate of the walls do anything for me? (guessing it doesn't)

4) Are there any cons to doing 24" OC spacing for wall studs?

5) I'm in Chicago-area, where code requires metal conduit for the electric wires...typically 3/4" or 1" EMT pipe. Any special considerations for that beyond putty padding back of the boxes? All of the piping is behind the walls.

6) We have a mechanical closet in the space (HVAC, water heater, A/V rack, etc.) that will need to be vented, and I can't treat the ceiling in that space for sound isolation given all the plumping pipes and HVAC ducts (on joists, between joists, and floating below joists). Anyone run across this problem and have suggestions on how to handle the venting? I can build the walls around the mechanical closet appropriately and put in a proper solid core door, but I gather it will be pretty worthless given the vents that will need to be installed. This closet will be located against an exterior wall if that creates any options.

Thanks all.


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## nathan_h

1). You can look at the different ratings that the SoundProofingCompany.com gives various combinations. I would infer from their data that clips and channels are the most useful place to start. I have actually read that whether the clips have rubber or not makes relatively little difference (though maybe that was in the context of walls and not ceilings so I don’t know if that changes anything) so if you need the space, I wouldn’t both with rubber unless you find something definitive.

From all the available data, the DD+GG seems more useful than MLV but I haven’t actually used MLV so I may be prejudice.

Those cow clips look really cool. If they work like they would seem to, I guess that buys you maybe half an inch? 

2). Any mass it helpful but I don’t think the additional drywall is a huge value there. Certainly if budget is a factor it wouldn’t be high on my list.

3). I would still try to do something under the walls. The more than can absorb and dissipate vibrations the better.

4). For sound isolation, the 24” OC is better than 16” OC, just make sure to head the clip and channel manufacturer details as well.

5). If it were me and it were easy and allowed, anywhere there is a conduit attached to a wall I would try to use a rubber gasket rather than metal on metal or metal on wood.

_6). I can’t quite picture what you are describing, but it sounds on first blush like a giant hole in your room that undercuts all the other efforts. *I would not proceed if that is the case*. Maybe post a drawing, or photo, of the situation._


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## KPS2525

nathan_h said:


> 6). I can’t quite picture what you are describing, but it sounds on first blush like a giant hole in your room that undercuts all the other efforts. *I would not proceed if that is the case*. Maybe post a drawing, or photo, of the situation.


Thanks much Nathan for all of the responses. Here is a drawing of the space. The mechanical room is in the upper section. You can also see all of the other challenges I'm facing (stairs, doors, open bar area, etc.). Trying to balance effort with expectations.

One other question I had in terms of decoupling...You can see that I'll have two small walls in the middle of the space underneath an I-Beam. Is there a product for decoupling those top plates from the bottom of the I-Beam?


----------



## nathan_h

That is a complex one but it looks like it will be a nice space.

I have seen but not used these clips that sound like they might be what you seek: IB-3 Decoupling Bracket

In terms of how to handle the mechanical room, personally, I'd try to make the red area my shell:










Not ideal, because this still put the bar area (a potential sound of noise) inside the shell. You may want an outlet that turns off the fridge etc while watching movie.

And I can't see what happens at the bottom of the stairs. If there is no door there, then I wouldn't both with the shell. Even if there is a door there, the stair well is still looking like a big hole in the shell?

Assuming you can put an awesome door (or doors) at the base of the stairs, since that seems to be an entry directly into the theater space, then what I would try to do is make this the shell by adding a wall, with I guess another door to access the rest of the basement.

This is a guesstimate, not a definitive approach, ie, more like what I would explore rather than a final plan -- especially since I can't see what's going on at the bottom of the stairs etc.










You may want to start a "build thread" with a few more angles of the layout revealed, to gather more data. I know there are several experienced people that don't keep up with this particular thread, but do check out new build threads.


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## batlin27

da1duc said:


> You are doing a double wall correct? If so have them do a flash and batt setup. Just did closed cell and rockwool on 3.5" walls for my full basement. Only had a few sections that the spray foam was too thick. Just watch that with the double wall and foam (closed or open) it will lock the two walls together (even open will). You need that to be completely decoupled.



Back to a post last year.. we finally got insulation and the Spray Foam was sloppy (or they didn't follow directions) I posted this in my Build thread but wanted insight from this thread as well...

The request was the the Spray foam NOT couple the walls together. That the spray foam only reside in the outer wall with the exterior and garage. From the photos you can see this was not done / done very sloppy.

Question.. How much of an issue is this?
I am not looking for / or expecting total isolation. I am just look to reduce the amount of noise that escapes. This was a verbal request from me to my contactor and not in writing so I figure it will cost time and $$$ to get them to redo and right now both are tight 

This is Open Cell Spray Foam

I still have scheduled to have the interior walls installed with R-13 Insulation

Below is a diagram where the spray foam is and where it bleed over into the inner walls.


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## wonman73

this is korea I'm trying to soundproof a private vocal practice room. Due to the difference in building materials and the lack of space on site, we are thinking about various types. Please comment on which type of sound insulation will have a good STC rating.


----------



## nathan_h

batlin27 said:


> Question.. How much of an issue is this?


I don’t know how to quantify it. Rather than rip it out I’d probably use clips and hat channel on the walls that aren’t decoupled, instead.

But I cannot say that is based on an informed cost benefit analysis.


----------



## nathan_h

wonman73 said:


> View attachment 3370689
> 
> 
> this is korea I'm trying to soundproof a private vocal practice room. Due to the difference in building materials and the lack of space on site, we are thinking about various types. Please comment on which type of sound insulation will have a good STC rating.


I am not sure what the #2&3 ones really mean. The #1 is typically considered very very good. With #1, the door will leak more sound than the wall and ceiling. In other words I believe option #1 is adequate.

And then you need to look at other elements like the door, any windows, electrical outlets and cable inputs,etc.


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## batlin27

nathan_h said:


> I don’t know how to quantify it. Rather than rip it out I’d probably use clips and hat channel on the walls that aren’t decoupled, instead.
> 
> But I cannot say that is based on an informed cost benefit analysis.


Unfortunately we are locked at this point and I can't add hat channel, I wish I could as my ceiling is not decoupled so although I have double walls and double 5/8" Drywall with GG I my ceiling joists just go to the attic. 

I am trying to figure out if there will be an impact in the house from the house and hearing what is going on in the Theater. Since the two walls are exterior will that factor in much to the overall construction and sound reduction?


----------



## nathan_h

Yes, but even fixing those walls won't solve the ceiling so it's a tough call. 

If budget is an issue, I would not be inclined to spend it re-doing that insulation. But you may find it useful to hire a professional like Poe's Acoustics to give you their advice before making a final decision.


----------



## Rjloper9

Mr.337 said:


> View attachment 3359813
> 
> View attachment 3359814
> just trying to finish up the room in my new house. I told contractors I wanted a double wall on the back wall of room. I'll have 2 solid doors for the walls. Im also going to do rsic clips and hat channels with 2 sheets of 5/8 sheetrock and green glue on the staggered stud wall.
> 
> I know this isn't what I was supposed to get for a 24oc staggered stud wall but I'm thinking less is better?
> 
> The rsic clips show 48" oc horizontal which is what the studs measure and ill add extra vertical clips instead.
> 
> My main question is do I need to add more studs on the 24oc wall if I only am hanging the 2 sheets drywall and nothing ever else from that wall?





















Sent from my iPhone using Tapatalk Pro


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## Mr.337

Rjloper9 said:


> Sent from my iPhone using Tapatalk Pro



Ya I ended up fixing the 24" on center staggered to just normal 24" on center and got my clips installed last night ill work on the hat channel this week. The room is the only 1 upstairs so we ended foaming the ceiling rafters and the flooring underneath 5 1/2" of open cell and putting roxul on the pony walls false ceiling will also get roxul and the back walls. Ive also added the fire puddy pads behind each of thr boxes and will sound proof further with the accoustic caulk sealing compound.


----------



## KPS2525

Nathan...thanks again for the responses. Really appreciate everyone's help.



nathan_h said:


> In terms of how to handle the mechanical room, personally, I'd try to make the red area my shell:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Not ideal, because this still put the bar area (a potential sound of noise) inside the shell. You may want an outlet that turns off the fridge etc while watching movie.


Agreed...I think that will be the plan, but not sure on how to vent the mechanical room (don't think I'm allowed or want to seal it due to HVAC and AV equipment rack). The HVAC noise could be a distraction...maybe I could build some kind of vent box with a few bends and line it with MLV or something similar.



nathan_h said:


> And I can't see what happens at the bottom of the stairs. If there is no door there, then I wouldn't both with the shell. Even if there is a door there, the stair well is still looking like a big hole in the shell?
> 
> Assuming you can put an awesome door (or doors) at the base of the stairs, since that seems to be an entry directly into the theater space, then what I would try to do is make this the shell by adding a wall, with I guess another door to access the rest of the basement.


The stairs is certainly a hole here. I added some pictures below of the stairs. I don't think we'd entertain the idea of putting a door at the bottom of the stairs. My challenge with this entire project is that this basement is meant to be an entertaining space first a foremost, and a home theater secondarily. To that end, I know I'll have significant compromises when it comes to the home theater build portion (particularly the sound isolation aspect). We don't watch at very loud volumes, so I'm just hoping to mitigate the bass from traveling throughout the house. From what I've researched, I do think I can realize some noticeable benefit by decoupling the space from the rest of the house via clips/channels (even the stairwell...more on that later likely). At this point, I'm not sure the benefits of a 2nd drywall layer and green glue will be worth the cost/effort given all the compromises with the room and the holes we'll put in the shell for in-wall speakers, outlets, etc....oh, and not to mention the existing HVAC ducts.




















nathan_h said:


> You may want to start a "build thread" with a few more angles of the layout revealed, to gather more data. I know there are several experienced people that don't keep up with this particular thread, but do check out new build threads.


This is a good idea. I'll be contracting out this work, but feel like I will need to stay close to these guys to be sure I get exactly what I want/need. Will certainly be helpful to get input on that along the way. Given that this is not a "dedicated" home theater, do you think I should put my build thread on the General Home Theater forum or still put it in the Dedicated Theater Design and Construction forum? Now I have to come up with a catchy title...


----------



## nathan_h

The dedicated theater design thread should be fine. Yes, given your goals and parameters, I would not bother with clips and channels and double dry wall and green glue. It would be like building a fish tank with one side missing. Not useful. Too many openings and alternate ways for the sound and vibration to travel, imo.


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## littlefish3

I'm having a hard time making a choice between inwall/inceiling vs onwall/onceiling speakers for surrounds and atmos with a soundproofing perspective in mind.
Considering a room that I want to be as soundproof as possible using the following : IB1 clips, furring channels, double 5/8" drywall + green glue, R13 for walls and R19 for ceiling.
Would inwall/inceiling speakers with built-in backerboxes (for example Triad's inwall and inceiling Sat series) be very detrimental to the effort put in for soundproofing?
If they are not problematic for soundproofing, is there anything special to consider during installation? Simply cut holes in the double drywall and screw the speakers to the studs/joists?


----------



## nathan_h

littlefish3 said:


> I'm having a hard time making a choice between inwall/inceiling vs onwall/onceiling speakers for surrounds and atmos with a soundproofing perspective in mind.
> Considering a room that I want to be as soundproof as possible using the following : IB1 clips, furring channels, double 5/8" drywall + green glue, R13 for walls and R19 for ceiling.
> Would inwall/inceiling speakers with built-in backerboxes (for example Triad's inwall and inceiling Sat series) be very detrimental to the effort put in for soundproofing?
> If they are not problematic for soundproofing, is there anything special to consider during installation? Simply cut holes in the double drywall and screw the speakers to the studs/joists?


Much better, given how much effort you have put into the shell of your room, to mount them INSIDE the shell of your room. A very popular solution is to build columns for the side surrounds and the rears.


----------



## calincole

Does anyone have experience with Structural Composite doors? I have 2 door options I am looking at, normal Solid core and structural composite core, both 1 3/4 thick. SCC is apparently similar to lvl lumber and I would assume a fair bit more dense than normal solid core. It is also double the cost, $550 vs $260 (just he slab here, building my own jamb, 

Anyone got experience using this? Any sense on if it would provide added value, or just added complication?


----------



## littlefish3

nathan_h said:


> Much better, given how much effort you have put into the shell of your room, to mount them INSIDE the shell of your room. A very popular solution is to build columns for the side surrounds and the rears.


I had not thought about columns. I'll look into how I could integrate those in the build, but my room is not very wide (only 12'9" wide), which is why I was considering in-walls. I'm wondering if columns might make the room feel "cramped in".
Just to make sure I understand you correctly, do you put in-wall types of speakers inside the columns or on-wall types?

Is there any similar solution for the height speakers, or are on-ceiling speakers the only alternative to in-ceilings?


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## nathan_h

calincole said:


> Does anyone have experience with Structural Composite doors? I have 2 door options I am looking at, normal Solid core and structural composite core, both 1 3/4 thick. SCC is apparently similar to lvl lumber and I would assume a fair bit more dense than normal solid core. It is also double the cost, $550 vs $260 (just he slab here, building my own jamb,
> 
> Anyone got experience using this? Any sense on if it would provide added value, or just added complication?


I haven't seen data on SCC doors. But for that price difference, they would have to be quite good. I'd personally much rather have two of the $260 doors, set up as an airlock. That is quite effective. 

And keep in mind that proper gaskets for the doors will likely set you back as much or more than the door itself.


----------



## nathan_h

littlefish3 said:


> I had not thought about columns. I'll look into how I could integrate those in the build, but my room is not very wide (only 12'9" wide), which is why I was considering in-walls. I'm wondering if columns might make the room feel "cramped in".
> 
> Is there any similar solution for the height speakers, or are on-ceiling speakers the only alternative to in-ceilings?


I have seen people place "in ceiling" speakers on the surface of the ceiling instead of inside it.

Yes, columns could make the room feel a fit cramped. They would eat up 4" on each side (at their location). It's one of those balancing acts where you have to decide what matters most, and where some compromise is acceptable -- and the answer is not the same for everyone.


----------



## littlefish3

nathan_h said:


> I have seen people place "in ceiling" speakers on the surface of the ceiling instead of inside it.
> 
> Yes, columns could make the room feel a fit cramped. They would eat up 4" on each side (at their location). It's one of those balancing acts where you have to decide what matters most, and where some compromise is acceptable -- and the answer is not the same for everyone.


I'm sorry I edited my post right at the moment you were replying !

From the dimension you wrote (4"), I presume that columns can be used to hide in-wall types of speakers and not on-wall speakers right? On-wall speakers would usually have more than 4" of depth.


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## nathan_h

littlefish3 said:


> I'm sorry I edited my post right at the moment you were replying !
> 
> From the dimension you wrote (4"), I presume that columns can be used to hide in-wall types of speakers and not on-wall speakers right? On-wall speakers would usually have more than 4" of depth.


Right. You mentioned Triad speakers, so I assumed (perhaps incorrectly) you could be surface mounting a Triad in wall speaker and hiding it in a column.


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## calincole

nathan_h said:


> I haven't seen data on SCC doors. But for that price difference, they would have to be quite good. I'd personally much rather have two of the $260 doors, set up as an airlock. That is quite effective.
> 
> And keep in mind that proper gaskets for the doors will likely set you back as much or more than the door itself.


Yeah, I can't seem to find much information on them at all. I don't mind paying more for better, and its not like it has to be 1 for 1 but I try not to pay more for nothing. I def plan on seals for the door though, that is a requirement.


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## Stylez777

I just redid my lower floor and we couldn't put a door at the bottom of the stairs to the lower floor due to space / design. So there is an open floor from level 1 and level 2 via the stair case and all the sound just travels right up the stairs between both levels. I'm not worried about sound through the ceiling/floor, if both TV are on in level 1 and level 2 there is tons of cross sound from the stairs.

So since I cannot build a wall or put a door I wanted to put a 7ft floor to ceiling x 3ft wide (the opening to the 1st level) Sound Proof panel. I didn't want to put anything massively heavy making it too hard to move when needed but I was wondering if getting 2 pieces of 1/2" foam board like the corning foam insulation boards, use green glue in between, layer each side of the board with a sheet of MLV and then wrap it in fabric, if that would work to help keep the sounds from traveling up and down the stair case? I know the more mass the better it would be but I want to try to keep the panel light enough to moved into place when the area is in use.

I thought of doing a frame out of 1x4 put Rockwool Sound Proofing inside then MLV on each side then wrap in fabric but I wasn't sure if that would work better or not. I don't care about acoustics in the room, I really just need to block sound from moving up and down the stair case and there is no way to do it on level 2 as it is an open concept at the stairs.

Will either of these work? Is one better than the other? Is there a better way to do this? Thanks!


----------



## nathan_h

Stylez777 said:


> I just redid my lower floor and we couldn't put a door at the bottom of the stairs to the lower floor due to space / design. So there is an open floor from level 1 and level 2 via the stair case and all the sound just travels right up the stairs between both levels. I'm not worried about sound through the ceiling/floor, if both TV are on in level 1 and level 2 there is tons of cross sound from the stairs.
> 
> So since I cannot build a wall or put a door I wanted to put a 7ft floor to ceiling x 3ft wide (the opening to the 1st level) Sound Proof panel. I didn't want to put anything massively heavy making it too hard to move when needed but I was wondering if getting 2 pieces of 1/2" foam board like the corning foam insulation boards, use green glue in between, layer each side of the board with a sheet of MLV and then wrap it in fabric, if that would work to help keep the sounds from traveling up and down the stair case? I know the more mass the better it would be but I want to try to keep the panel light enough to moved into place when the area is in use.
> 
> I thought of doing a frame out of 1x4 put Rockwool Sound Proofing inside then MLV on each side then wrap in fabric but I wasn't sure if that would work better or not. I don't care about acoustics in the room, I really just need to block sound from moving up and down the stair case and there is no way to do it on level 2 as it is an open concept at the stairs.
> 
> Will either of these work? Is one better than the other? Is there a better way to do this? Thanks!



Covering the opening in this way isn't going to make a lot of sense. It will be awkward and not much more effective than:

Just hang lots of panels on the walls of the stairs, ceiling of the stairs, etc. Basically, if I understand you correctly, the stairway the place you hear the sound from. So, if you turn the stairway into a muffler, by handing acoustic panels on the walls and ceiling of the stairs, you'll likely greatly reduce the sound passing from one floor to another via the stairwell.

Photos of the stairwell, and the top and bottom open would help confirm that idea.

(And as you already noted, the best way to solve this would be a door at the top or bottom of the stairs. It should be solid core, like 1 3/4" thick or thicker, and have whether stripping or gaskets around it to really help.)


----------



## Stylez777

nathan_h said:


> Covering the opening in this way isn't going to make a lot of sense. It will be awkward and not much more effective than:
> 
> Just hang lots of panels on the walls of the stairs, ceiling of the stairs, etc. Basically, if I understand you correctly, the stairway the place you hear the sound from. So, if you turn the stairway into a muffler, by handing acoustic panels on the walls and ceiling of the stairs, you'll likely greatly reduce the sound passing from one floor to another via the stairwell.
> 
> Photos of the stairwell, and the top and bottom open would help confirm that idea.
> 
> (And as you already noted, the best way to solve this would be a door at the top or bottom of the stairs. It should be solid core, like 1 3/4" thick or thicker, and have whether stripping or gaskets around it to really help.)



I really been trying to figure out how to put a door but there is just no easy way to put one as you can see from the picture it is tight and there is already a door to the garage. The open space into the room is 37" I wouldn't want to put a smaller door as getting furniture in and out would be really difficult. Down the road I probably will section of this level into 2 other rooms and build walls and make it less open, but right now I am not going to get into all that. I just need a way to stop the sound traveling through that open way and up the stairs. Using a panel is def clunky but I don't mind a moveable panel if it can lessen or muffle the sound. You can see the pictures of how the stair case is and the bottom of the stairs and the opening into the lower level.






























Any suggestions are welcome!


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## nathan_h

The best solution would be to put a door here (from what I can see) if CODE allows that.











However, if that is not an option right now, then lining the area with panels on the walls (and one on the ceiling at the base of the stairs will create a muffler that will help a bit.


















You might also consider a heavy curtain (like VERY thick and heavy, like almost as thick as a rug) over the opening where ideally a door would go. It will probably help with a bit of the treble. Not nearly as good as a door, but better than nothing.










Finally, if it meets with household approval, a few panels on this wall wouldn't hurt:











-----

There are nice printed panels these days with artwork on them. You can upload your own family photos and they can be printed on the panels. Etc.


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## Stylez777

nathan_h said:


> The best solution would be to put a door here (from what I can see) if CODE allows that.
> 
> 
> However, if that is not an option right now, then lining the area with panels on the walls (and one on the ceiling at the base of the stairs will create a muffler that will help a bit.
> 
> 
> 
> 
> You might also consider a heavy curtain (like VERY thick and heavy, like almost as thick as a rug) over the opening where ideally a door would go. It will probably help with a bit of the treble. Not nearly as good as a door, but better than nothing.
> 
> 
> 
> Finally, if it meets with household approval, a few panels on this wall wouldn't hurt:
> 
> -----
> 
> There are nice printed panels these days with artwork on them. You can upload your own family photos and they can be printed on the panels. Etc.


I appreciate the reply! Yeah I want a temporary solution because in maybe 2-3 years I will section off the lower level into 2 rooms and when I frame the walls I will be bale to add solid core thick door sinto each room and add more mass and sound proof to those walls and won't have to worry about sound travel up since the floor will be more used for kids rooms instead of an open common area that it going to be used for at this point. I am going to look into those artistic type of panels, that would be pretty cool and make the wife happy. Is there any kind of specs or type of panels I want to look for?

As for the curtain if it even slowed or muffled the voice sounds from a TV show (bass I don't care, it the voices) that would help. Is there something specific to search for? I've look at sound proof curtain blankets etc but stuff labeled sound proof, really ain't sound proof at all from what I read. Would making something be better? I got a seamstress in the family, get her to sew some fabric over MLV filled pockets? Something like that work if it was thick and heavy enough?


----------



## nathan_h

In terms of curtains, I would just seek something like those heavy curtains that restaurants in cold places put in their entry way to prevent a blast of cold air from entering the room when people open and close the door. 

You can get crazy and get fancy but I'm not sure it will be much better.

For panels, two inch thick (minimum) fiberglass or rock wool panels are the most cost effective choice. GIK acoustics. Acoustimac. These are the places I would look for panels. I know GIK lets you do custom art. Both of them also have stock art, some of which is pretty nice.


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## Stylez777

nathan_h said:


> In terms of curtains, I would just seek something like those heavy curtains that restaurants in cold places put in their entry way to prevent a blast of cold air from entering the room when people open and close the door.
> 
> You can get crazy and get fancy but I'm not sure it will be much better.
> 
> For panels, two inch thick (minimum) fiberglass or rock wool panels are the most cost effective choice. GIK acoustics. Acoustimac. These are the places I would look for panels. I know GIK lets you do custom art. Both of them also have stock art, some of which is pretty nice.


Awesome thank you for the help. One last question if you don't mind. Do you think it would make any difference, if I did the curtains twice, one at the base of the stairs and one where you said so the sound would have to travel twice through? I'm just thinking if that helps muffle it even more I would mind that temporarily for a year or 2 to I redo things. Also do you think adhering some MLV to the curtain would help at all or just not worth the cost? Thanks!


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## nathan_h

Yes, a second set of curtains likely makes some difference, certainly worth trying. 

I can't answer the MLV question well. My guess would be that it may not be worth it but wouldn't hurt, and if it is easy for you, why not try?


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## stealthmoe

I’m starting the design phase of a home theater in a dedicated room which is on the 2nd floor of my house and sits above my living room at the middle of my floor plan.

I have a local GC which I’ve been tossing some ideas to and he comes back with rough pricing. I sent him the links from soundproofingcompany.com and according to him, the costs would be VERY high and likely not all that effective. I spoke to him about the room within a room concept and he’s skeptical of the efficacy too.

The room is quite big (18’x25’ with 11’ ceilings) and it has a ton of potential. How much thought and resources should I consider for soundproofing?


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## nathan_h

As much as you want and can afford? 

Your contractor is right, very expensive versus traditional construction…maybe 3x the cost of a normal room…and wasted money if done wrong. Really depends on your needs and budget.


----------



## wonman73

nathan_h said:


> I am not sure what the #2&3 ones really mean. The #1 is typically considered very very good. With #1, the door will leak more sound than the wall and ceiling. In other words I believe option #1 is adequate.
> 
> And then you need to look at other elements like the door, any windows, electrical outlets and cable inputs,etc.


Thank you for your answer... The comments are late. The original wall is a 1.5-inch glass-wool wall, and after removing one part of the plasterboard, you make another wall. 

Option one consists of a 1.5 inch glass wool, an inch air layer, and another 1.5 inch mineral wool 

Option two is to thicken the second wall with three inches of mineral wool instead of one and a half inches of mineral wool.

Option 3 is to make the medium 1 inch air layer a little smaller and create a small air layer between the 3 inch mineral wool walls to reinforce the medium 1 inch or less air layer in the middle. 

I would like to ask you which wall is more efficient.


----------



## nathan_h

wonman73 said:


> Thank you for your answer... The comments are late. The original wall is a 1.5-inch glass-wool wall, and after removing one part of the plasterboard, you make another wall.
> 
> Option one consists of a 1.5 inch glass wool, an inch air layer, and another 1.5 inch mineral wool
> 
> Option two is to thicken the second wall with three inches of mineral wool instead of one and a half inches of mineral wool.
> 
> Option 3 is to make the medium 1 inch air layer a little smaller and create a small air layer between the 3 inch mineral wool walls to reinforce the medium 1 inch or less air layer in the middle.
> 
> I would like to ask you which wall is more efficient.


I would choose option one. And if you have more time and money to invest I would consider using that a better floor and ceiling and door. Options two and three don’t seem likely to be as beneficial as a better door and other measures. 









Soundproofing A Wall


Sound damping, sound isolation and noise reduction. Soundproof walls for commercial, condos, apartments, home theaters, recording studios, and more.



www.soundproofingcompany.com












Soundproofing a Ceiling


Complete solutions for soundproofing ceilings - commercial and residential. Recommended for home theaters, recording studios and neighbor noise.



www.soundproofingcompany.com












Soundproofing A Floor


The Soundproofing Company offers a variety of solutions for soundproofing floors in homes, condos, commercial spaces, home theaters, recording studios and more.



www.soundproofingcompany.com













IsoDoor | Sound Control Doors for Offices | Home Theaters | Recording Studiosd


IsoDoor models for all types of assemblies and projects, including offices, home theaters, and recording studios.




isodoor.net












Best Interior Soundproof Doors for Room Acoustics | ASI


ASI's soundproof interior doors for recording studios and other applications have an STC value of up to 56. Order your studio door today!




www.acousticalsurfaces.com


----------



## stealthmoe

What's the STC rating of adding two 5/8" drywall layers with green glue to existing 1/2" walls and no insulation added? If I don't have to demo the entire room's drywall, it'll save me a ton, but I don't want to be a penny wise and a pound foolish.


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## nathan_h

Remember STC is not an applicable number for all frequencies. It doesn't tell you about BASS containment, which is the #1 challenge of a home theater. 

That being said, the link in the post before yours to the sound proofing company approximately answers your question about STC:










But removing the existing drywall is twice as useful in terms of STC:










And the nitty gritty (same web site, details page) though you probably have 16" OC studs.










TLDR: My friend who simply added drywall layers was sorely disappointed with the results. He wasn't even sure it was any better than before.


----------



## stealthmoe

nathan_h said:


> Remember STC is not an applicable number for all frequencies. It doesn't tell you about BASS containment, which is the #1 challenge of a home theater.
> 
> That being said, the link in the post before yours to the sound proofing company approximately answers your question about STC:
> 
> View attachment 3375069
> 
> 
> But removing the existing drywall is twice as useful in terms of STC:
> 
> View attachment 3375070
> 
> 
> And the nitty gritty (same web site, details page) though you probably have 16" OC studs.
> 
> View attachment 3375071
> 
> 
> TLDR: My friend who simply added drywall layers was sorely disappointed with the results. He wasn't even sure it was any better than before.


I'm all over that website, but I'm still a total idiot with the concepts. Expand on your friends experience if you could. Did he rip out the existing drywall and do just the 2 drywall layers? Did they use the green glue or the clips? Also, my ceiling is an attic. Would I need to do the ceiling?


----------



## thrillhouse763

Stylez777 said:


> Awesome thank you for the help. One last question if you don't mind. Do you think it would make any difference, if I did the curtains twice, one at the base of the stairs and one where you said so the sound would have to travel twice through? I'm just thinking if that helps muffle it even more I would mind that temporarily for a year or 2 to I redo things. Also do you think adhering some MLV to the curtain would help at all or just not worth the cost? Thanks!


I have the _EXACT_ same problem as you and I'm trying to solution for something temporary. My theater is directly to the right of the stairs and all the sound travels right up those stairs. That entry way is already very tight for some furniture so adding a door is no go unless I can trim back some of that drywall to make it flush with the wall running up the stairs. That might negate what I would lose from adding a door.

Anyway, can you let me know if you found and tried out some curtains? That might be my next solution.


----------



## wonman73

nathan_h said:


> I would choose option one. And if you have more time and money to invest I would consider using that a better floor and ceiling and door. Options two and three don’t seem likely to be as beneficial as a better door and other measures.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Soundproofing A Wall
> 
> 
> Sound damping, sound isolation and noise reduction. Soundproof walls for commercial, condos, apartments, home theaters, recording studios, and more.
> 
> 
> 
> www.soundproofingcompany.com
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Soundproofing a Ceiling
> 
> 
> Complete solutions for soundproofing ceilings - commercial and residential. Recommended for home theaters, recording studios and neighbor noise.
> 
> 
> 
> www.soundproofingcompany.com
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Soundproofing A Floor
> 
> 
> The Soundproofing Company offers a variety of solutions for soundproofing floors in homes, condos, commercial spaces, home theaters, recording studios and more.
> 
> 
> 
> www.soundproofingcompany.com
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> IsoDoor | Sound Control Doors for Offices | Home Theaters | Recording Studiosd
> 
> 
> IsoDoor models for all types of assemblies and projects, including offices, home theaters, and recording studios.
> 
> 
> 
> 
> isodoor.net
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Best Interior Soundproof Doors for Room Acoustics | ASI
> 
> 
> ASI's soundproof interior doors for recording studios and other applications have an STC value of up to 56. Order your studio door today!
> 
> 
> 
> 
> www.acousticalsurfaces.com


Thank you for your answer
Korean insulation (mineral wool) has a basic thickness of less than 2 inches. It is smaller than the 3 1/2 inches used in the US.

I'm considering installing an additional installation to reinforce the small insulation, but your opinion is that it's better to invest in the ceiling or door rather than installing an additional one?

Is there a recommended size of air gap between the insulation?

And do you have any recommendations for how much insulation should fit inside the air cavity?
And do you have any data to confirm the test results?


----------



## wonman73

I have more questions while studying.
When adding a layer using green glue, there is a gain of 7 stc points for walls.
However, in the case of the ceiling, there is only a 3 point benefit...
Can someone please explain?


----------



## wonman73

wonman73 said:


> Thank you for your answer
> Korean insulation (mineral wool) has a basic thickness of less than 2 inches. It is smaller than the 3 1/2 inches used in the US.
> 
> I'm considering installing an additional installation to reinforce the small insulation, but your opinion is that it's better to invest in the ceiling or door rather than installing an additional one?
> 
> Is there a recommended size of air gap between the insulation?
> 
> And do you have any recommendations for how much insulation should fit inside the air cavity?
> And do you have any data to confirm the test results?


----------



## stealthmoe

For home theaters on the 2nd floor of a two story home, is there any consideration for sound proofing the ceiling? Sorry for what might be a silly question.


----------



## nathan_h

stealthmoe said:


> I'm all over that website, but I'm still a total idiot with the concepts. Expand on your friends experience if you could. Did he rip out the existing drywall and do just the 2 drywall layers? Did they use the green glue or the clips? Also, my ceiling is an attic. Would I need to do the ceiling?


He just added two additional layers of drywall, on top of existing drywall. No GG, and didnt remove anything to add clips and channels.

Were he to do it again, he said he'd either not bother at all, or he would rip out the existing drywall and do clips and channels, and then drywall over that. (At that point I'd personally ALSO do GG and a second layer of drywall.)

His OTHER problem is that one you wil have if you skip the ceiling and floor: Sound is like water. It doesn't care where it gets out, it just wants out. If you don't decouple the ceiling from the attic, then the attic will carry the sound to every other room that shares the attic.

The folks at the soundproofing company are happy to advise you about your specific room as well.


----------



## nathan_h

wonman73 said:


> I have more questions while studying.
> When adding a layer using green glue, there is a gain of 7 stc points for walls.
> However, in the case of the ceiling, there is only a 3 point benefit...
> Can someone please explain?
> View attachment 3375416
> View attachment 3375417


I wish I had better knowledge of the reasons for those differences. I do not have that knowledge. I could speculate but that probably doesn't help.

As far as I know, the key to the gap between walls is the air space, and that while more space is better, a gap of just one inch should be enough to get more of the benefit of the air gap. From the data I have seen, the insulation amount is less critical but usually fills all the space EXCEPT the air gap between the two walls.


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## nathan_h

stealthmoe said:


> For home theaters on the 2nd floor of a two story home, is there any consideration for sound proofing the ceiling? Sorry for what might be a silly question.


Not silly. The ceiling is important because it is a direct pathway to all the other rooms on the same story.


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## wonman73

Thank you for your answer
I have one more question. Now the photo is a cross section of the wall and ceiling construction.

Figure 1 first creates a wall with an appropriate size air cavity.
It is to make the ceiling from the drywall of the wall

The second picture opens the air cavity of the wall and ceiling to communicate with each other.
The interior is covered with drywall.
Seal the room and isolate it.
Then you will have a very large Air Cavity including the walls and ceiling.

Which option is effective for sound insulation?

And can the large air cavity of option 2 have a positive effect on soundproofing?


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## nathan_h

I'm not 100% sure of all those details but #2 looks better to me. Think of the walls and ceiling as a room inside of another room where none of the interior room walls & ceiling touch the exterior room walls and ceiling.

The floor is a little harder, and the door of course is a big challenge, too.


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## wonman73

nathan_h said:


> I'm not 100% sure of all those details but #2 looks better to me. Think of the walls and ceiling as a room inside of another room where none of the interior room walls & ceiling touch the exterior room walls and ceiling.
> 
> The floor is a little harder, and the door of course is a big challenge, too.
> 
> 
> Thank you for your comments.
> Currently, Door plans to invest more.
> However, the floor finishes without working due to money problems.
> After checking the soundproofing results, if it is insufficient, we plan the floor construction afterwards.


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## batlin27

I am sure this has been gone over before but all I found was the topics about can lights and whisper 
clips and resilient channel. 

I have 4” new construction can lights (I think the brand is Juno) and double dry wall 5/8” being installed on the ceiling. Will recessed can lights work with the thick layer of dry wall?


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## nathan_h

Every model may be different but the ones I have seen allow for ceiling drywall depth of up to 1.75". You or your contractor will need to check the spec sheet foryour specific can. 

I'd be more worried about the fact that new constrution can lights fasten to the ceiling joists....messing up your decoupling plans if used in that way.....and that building the backer boxes can be tedious (but it is doable).


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## batlin27

nathan_h said:


> Every model may be different but the ones I have seen allow for ceiling drywall depth of up to 1.75". You or your contractor will need to check the spec sheet foryour specific can.
> 
> I'd be more worried about the fact that new constrution can lights fasten to the ceiling joists....messing up your decoupling plans if used in that way.....and that building the backer boxes can be tedious (but it is doable).


Thank you nathan_h, this is what I was hoping to hear!


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## wonman73

Thank you for answering my many questions.

Every time I treat drywall edges, I ask if I have to treat them with acoustic sealant or if Drywall Joint Paper Tape is sufficient.
Or is it acoustic sealant for large holes or Drywall Joint Paper Tape for small holes?


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## nathan_h

Acoustic caulk is preferred.
Note that THIS is not caulk. This is foam. This is NOT the way to do it.


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## wonman73

nathan_h said:


> Acoustic caulk is preferred.
> Note that THIS is not caulk. This is foam. This is NOT the way to do it.
> 
> View attachment 3376996



Thank you... I found it while searching for pictures, so I used it, but I understand.

So, is Drywall Joint Paper Tape used only for interior finishing?

Is the acoustic sealant used only for joints?
Are you using only the ceiling to wall seam intersection?
Do I have to apply acoustic sealant to all the seams of the gypsum board?


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## nathan_h

These are two brands popular in the US:












The approach I like, based on what other experts here have shared, is listed below. I am not sure this is the best or only way. Note that the OSB layer can be a drywall layer (and usually is a drywall layer). This is instructions for doing it without clips and hat channels, assuming there is a double stud wall (similar to what you are doing, I think).


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## wonman73

nathan_h said:


> These are two brands popular in the US:
> 
> View attachment 3377062
> 
> 
> 
> 
> The approach I like, based on what other experts here have shared, is listed below. I am not sure this is the best or only way. Note that the OSB layer can be a drywall layer (and usually is a drywall layer). This is instructions for doing it without clips and hat channels, assuming there is a double stud wall (similar to what you are doing, I think).
> 
> View attachment 3377063
> 
> 
> 
> View attachment 3377064
> 
> 
> 
> View attachment 3377068
> 
> 
> 
> 
> View attachment 3377070



So you're saying all the gaps should be blocked with acoustic sealants?
And the Drywall Joint Paper Tape is for internal finishing...
Okay. Thanks.


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## batlin27

When it comes to Double Drywall and GG. How much benefit is there to doing DD+ GG on the interior and exterior walls of the Theater compared to doing DD + GG on the interior only walls?


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## nathan_h

Not as much since you are not creating a decoupled room on the outside. Remember sound doesn’t just go through the wall, it escapes a room. If you have extra funds after decoupling floor walls and ceiling then using it on the door and hvac system makes much more impact.


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## ryan239

Happy New Year to all! I am in the midst of a slow basement remodel, which includes adding a small-ish dedicated theater space. Largely inspired by many of the fine threads here, naturally. 
In any event, I have the following plan: decoupled walls (IB-3 clip attachments to joists, bottom of wall installed over 3/4" horse stall mat), and using clips/channel on the ceilings, for the entire finished portion of the basement. I have most of the stud walls up, and will be starting soon on the ceilings. 

I bought IB-1 clips from the Soundproofing company, and locally got the channel from a lumber supplier. Of course, I bought the wrong channel; I wound up with RC-2 1/2" resilient channel, not the 7/8" furring channel. Thankfully a relatively inexpensive mistake, and I should be able to return it.
Before I return the wrong stuff and get the right stuff, I just wanted to confirm my mistake, and confirm that I should swap them out. 

What I've got:

















The RC-2 fits fine in the clips, but I'd rather do it right.

I do plan on DD/GG in the theater on walls and ceiling, and I was thinking I would do the same in the outside play space, although I don't know if that will be overkill or not. The kids can be pretty loud, and I assume that they will only get louder as they age... 
The walls in/surrounding the theater will be double walls, with the previously mentioned decoupled walls in the rest of the space. A rough layout is below, not entirely to scale but the mostly accurate concept I'm working off of. 

I haven't really dialed in speaker positions yet, aside from the bump-out in the 'front' of the room for my speakers. My plan long term is for a projector and screen, but initially I'll use the TV and equipment I have until the budget opens up. I'll start a build thread relatively soon!










Thanks!


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## nathan_h

ryan239 said:


> Happy New Year to all! I am in the midst of a slow basement remodel, which includes adding a small-ish dedicated theater space. Largely inspired by many of the fine threads here, naturally.
> In any event, I have the following plan: decoupled walls (IB-3 clip attachments to joists, bottom of wall installed over 3/4" horse stall mat), and using clips/channel on the ceilings, for the entire finished portion of the basement. I have most of the stud walls up, and will be starting soon on the ceilings.
> 
> I bought IB-1 clips from the Soundproofing company, and locally got the channel from a lumber supplier. Of course, I bought the wrong channel; I wound up with RC-2 1/2" resilient channel, not the 7/8" furring channel. Thankfully a relatively inexpensive mistake, and I should be able to return it.
> Before I return the wrong stuff and get the right stuff, I just wanted to confirm my mistake, and confirm that I should swap them out.
> 
> What I've got:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The RC-2 fits fine in the clips, but I'd rather do it right.
> 
> I do plan on DD/GG in the theater on walls and ceiling, and I was thinking I would do the same in the outside play space, although I don't know if that will be overkill or not. The kids can be pretty loud, and I assume that they will only get louder as they age...
> The walls in/surrounding the theater will be double walls, with the previously mentioned decoupled walls in the rest of the space. A rough layout is below, not entirely to scale but the mostly accurate concept I'm working off of.
> 
> I haven't really dialed in speaker positions yet, aside from the bump-out in the 'front' of the room for my speakers. My plan long term is for a projector and screen, but initially I'll use the TV and equipment I have until the budget opens up. I'll start a build thread relatively soon!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks!



My notes about channel says: "The hat channels should be a minimum of 25 gauge steel, between 7/8” and 1-1/2” deep and have a 1-1/4” crown to seat the drywall against." I'd guess I wrote this down based on something in a white paper, manufactuer spec, or one of @BIGmouthinDC excellent construction descriptions. I would probably NOT use the stuff you bought, unless the folks at SoundProofingCompany reply to your question and explicitly say it will work fine.

---

Looking over your drawing, I can't tell which wall is which, but two concerns I would have are that the wine storage may introduce noise or break the shell of the room letting sound escape. And the throw distance for your projector looks like it will be about 11 feet from lens to screen which will limit your screen size to under 120". That may be fine, but it also might not be something you considered. 

If it were my space and I had the option, I would put the projector and gear in the Kids Mayhem Area, to keep the noise and heat out of the theater, and it would give you another 2 feet of throw for the projector.

---

Yeah, a build thread is a great idea!


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## madtapper

nathan_h said:


> If it were my space and I had the option, I would put the projector and gear in the Kids Mayhem Area, to keep the noise and heat out of the theater, and it would give you another 2 feet of throw for the projector.



Been wondering about the above.....how audible are PJs nowadays? Building a first theater with a projector and concerned about the noise and heat in that order. I have an old RS1 from JVC that I've been experimenting with and it's awful on both accounts. Super loud and super hot. I was assuming current models, NZ7 for instance, are much better, but maybe that's wishful thinking on my part?


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## nathan_h

Still noisy and hot.


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## hokeyplyr48

I can’t use eshiftx on my NZ8 or run it in high laser as it’s way too loud. Hush box or medium/eshiftX off are my only options.


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## madtapper

Unfortunate, but good to know what to expect. Thanks.


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## hokeyplyr48

FWIW there are some folks who say they can run in high laser with eshiftX on. I don’t know how, but they say they do. It’s purely subjective and I think there’s sample variance. You might fall into that camp, you might not. It’s a lottery like everything else with projectors. Might have bright corners, it might sound like a jet engine, etc.


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## ryan239

nathan_h said:


> My notes about channel says: "The hat channels should be a minimum of 25 gauge steel, between 7/8” and 1-1/2” deep and have a 1-1/4” crown to seat the drywall against." I'd guess I wrote this down based on something in a white paper, manufactuer spec, or one of @BIGmouthinDC excellent construction descriptions. I would probably NOT use the stuff you bought, unless the folks at SoundProofingCompany reply to your question and explicitly say it will work fine.
> 
> ---
> 
> Looking over your drawing, I can't tell which wall is which, but two concerns I would have are that the wine storage may introduce noise or break the shell of the room letting sound escape. And the throw distance for your projector looks like it will be about 11 feet from lens to screen which will limit your screen size to under 120". That may be fine, but it also might not be something you considered.
> 
> If it were my space and I had the option, I would put the projector and gear in the Kids Mayhem Area, to keep the noise and heat out of the theater, and it would give you another 2 feet of throw for the projector.
> 
> ---
> 
> Yeah, a build thread is a great idea!


Thanks for the input, @nathan_h 

I will definitely return the RC-2 and get the 7/8ths hat channel; this week is a bit busy but I should be able to get it done by the weekend. 

In regards to the wine storage area, I have a 4x4 bump out in the foundation there, which sits underneath my kitchen sink. I want to keep access to that area, so I thought if I did a double wall and paid attention to the door(s), it would be ok from a sound escape perspective (I may be wrong on that). The wall to the theater will be DD/GG, and I can build a secondary wall inside that space for further isolation. Might be a little tight on door space if I put in two, but I think I have the room. I left space in the framing for up to a 30" door, but I can always make it smaller.

The advice on the projector location is good. I have a steel beam running across the basement, right where I had initially laid out the 'back' wall. However, I can push the wall back a bit into the kids mayhem space, making room to move the projector back. The PJ would still be in the theater proper, so I'll have to build a vented hush box, but due to the beam I will be putting a soffit in anyways, so I think that should be fine, and it gives me more space for the rear speakers. That will also make the room slightly larger, 14' 6.75" front to back, and 14' 2.75" left to right. Plus another 2' of depth with the bump out into the mechanical room, which will be for the front speakers/sub. 

It may be a year or two after I complete the theater before I wind up with a projector and screen, but I think 120" or so should be fine for size. Before the basement got wet and I gutted it to start this project, we had been using a 65" TV, so going quite a bit larger will be an upgrade no matter what. I think I'll use the TV for awhile though, as a big piece of my theater budget got diverted into a 'rebuild my blown up race car engine' budget recently, hehe.

I'll see if I can start a build thread this week. Thanks again!


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## Stylez777

Hey all I'm back again seeking some info on what I should do / best way forward from where I am currently at (I'll attach what pictures I can to the thread to help)

So I redid most of my bottom floor which is half below grade (cinderblock underground) and the other half which is above grade (the wood house part). I sort of rushed so I didn't do any kind of soundproof clips or hat channel for the walls. I used Rockwool inside the exterior facing walls and used 1/2" sheetrock over since I was using 4' x 12" pieces to limit my cuts. The Ceiling is 1/2"drywall that I left and the cavity is empty between floors. The entrance/exit of the floor is a staircase which goes up to the 2nd floor, I have since had a solid core door hung in this space. I have sealed the gaps around the install with Great-Stuff Window/door flex foam.

So where I need help is the ceiling. Right now I am unsure what route I should take and what my expectations should be based on time/money result.

Option 1 - is to just leave the cavity in the existing ceiling empty between floors and just install new 5/8" drywall over the existing 1/2" drywall. This probably my cheapest option but probably won't do much for impact noise from kids running on hardwood floor upstairs or jumping off the couch doing "cannonballs", but I assume the extra 5/8" drywall will help with talking, TV sounds moving between floors?

Option 2 - Rip out the existing drywall. Now that the cavity is exposed I can either go nuts and attach pieces of 5/8" drywall to the subfloor from underneath, then use that green glue stuff add another 5/8" drywall over it, then add some insulation to the cavity. When that is done I can use the Sound Clips on the joists, use the 7/8"hat channel to decouple and then add 2 layers of 5/8" drywall to the hat channel. I am sure this will give very good results but is there any way to gauge if all this effort and $ will give vastly superior results than doing option 1? Is there anyway to do some sort of test to figure out if going option 2 fully will yield worthwhile results vs option 1?

I am trying to curb my expectations and know that sound will move, I get it no way to totally eliminate it but I just want to dampen the travel of music, tv, talking from 1 floor to the next when I want to watch TV on 1 floor and the kids are downstairs fortniting or robloxing. The impact noise I can live with so it isn't the biggest of deals to me and it seems the decoupling will be the most costly portion, as about 100 sound clips are $400 alone.

The dimension of my room are 12'x14' on 1 side and 12' x 18' on the other side. Any opinions or advice on what would be a worthwhile route to take would be appreciated. I'd def like to save $ if I could.


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## Stylez777

thrillhouse763 said:


> I have the _EXACT_ same problem as you and I'm trying to solution for something temporary. My theater is directly to the right of the stairs and all the sound travels right up those stairs. That entry way is already very tight for some furniture so adding a door is no go unless I can trim back some of that drywall to make it flush with the wall running up the stairs. That might negate what I would lose from adding a door.
> 
> Anyway, can you let me know if you found and tried out some curtains? That might be my next solution.
> 
> View attachment 3375318


I tried 4 different curtains and none of them did anything. I ended up installing a Solid Core door and it did wonders. I am now redoing the ceiling


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## nathan_h

Stylez777 said:


> I tried 4 different curtains and none of them did anything. I ended up installing a Solid Core door and it did wonders. I am now redoing the ceiling


Yep that sounds like the laws of physics are still working! Glad you found a path forward.


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## Stylez777

nathan_h said:


> Yep that sounds like the laws of physics are still working! Glad you found a path forward.


The biggest problem going down this rabbit hole is trying to weed through what works and what doesn't but more so what results you get for cost-time invested. I keep reading about MLV MLV. Prob I keep coming across is that it is not cost friendly at all! 1lb per sqft MLV is like $2.50 a sqft. Green glue looks to be about $1.5 a sqft. To decouple the ceiling seems to cost about $2 a sqft with clips and 7/8 channel. Insulation in cavity is about $1 a sqft. 5/8 X drywall is .50 a sqft.

So a lot of me is trying to take an approach as to what is worth the cost vs the result I'm going to get out of this. I'd love to use the MLV on the ceiling studs but at $2.5 a sqft not really sure the cost for result is there. I've read most results show it gives 4-6 STC increase in best case scenarios when used on wood studs and that is with the 2lb really expensive stuff, not even the 1lb stuff. Since I have the ceiling open once, I want to do the best I can for within a reasonable budget for acceptable results. I also need to curb the fact that I only put Rockwool in the exterior walls and only used 1/2" drywall. So no matter how much I beef up the ceiling the walls will still be the weak areas to carry sound between floors as well as the Solid Core door being another weakness.

Impact noise doesn't really bother me much, I got kids they going to bang and jump like crazy people. I care most about cross sounds from TV's or when kids are upstairs and i'm downstairs with the guys watching football or playing cards, we can limit the cross travel of sounds that can get annoying.


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