# sound proofing walls



## dberladyn

Do what ever you want. Yes, pink fiberglass insulation will cut down noise. There are a lot of ways to sound proof. If I was you and I was thinking of an additional layer of drywall I would use 5/8's drywall.


----------



## leungw

Look up Green Glue if you are adding a new layer of drywall on top of the existing. I have never used it but many people on avsforum swear by it.

http://www.greengluecompany.com/upgradingExistingWalls.php


----------



## acerunner

There are many options with large cost range. A good answer depends on your budget and time. You can use insulation, quiet rock, double walls, staggered studs, resilient channel.

The idea is to add mass and/or physically decouple the walls. Also, make sure there are no penetrations in the walls that will allow a path for sounds to travel.


----------



## rightit

The soundproof sites I've read say that the acoustic insulation is not much more effective than the run of the mill pink stuff. A completely decoupled wall (2 separate walls) is the most effective method for soundproofing, but I'm not quite clear on how your 2 walls are set up. If you have 2 walls with drywall only on the living space side of each wall, perfect. However, if it is two walls with 3 or 4 sides drywall, it is creating what is called the 'Triple Leaf Effect'. Here's a link:

http://www.soundproofingcompany.com/library/articles/triple_leaf_effect/

And here's more:
http://www.soundproofingcompany.com/library/articles/

http://www.greengluecompany.com/technicallibrary.php


Lots of info at these sites. I did much research for soundproofing a wall between two rooms. I'm using double layers of drywall with Green Glue in-between the layers. The sound dampening is serious. I also have a case of acoustic sealant (caulk) and putty pads for electrical outlets.

There's really too much information to convey in one post, but the links above will be useful.


----------



## Ted White

I'd also be interested in hearing more details about exactly how the walls are built.


----------



## diy-581

I wonder how well silicone sealant stacks up against the Green Glue stuff. Their site gives a chart against regular construction adhesive, but not silicone.

Also, I wonder how well cinder block walls (hollow or filled with sand, gravel, or concrete) is compared to sheetrock wall construction (with and without the Green Glue)....

I'm getting ready to build a hangar and apartment at an airpark and even though I don't find the noise of an aircraft all that irritating when I'm outside, I would prefer to minimize it inside when I'm trying to sleep...


----------



## Ted White

diy-581 said:


> I wonder how well silicone sealant stacks up against the Green Glue stuff.


People have wondered for the past 10 years. It's an urban legend. It's far too stiff and elastic. Plus, you'll likely find silicone costs more on a per-ounce basis.



diy-581 said:


> Also, I wonder how well cinder block walls (hollow or filled with sand, gravel, or concrete) is compared to sheetrock wall construction (with and without the Green Glue)....


A solid block wall filled with concrete would do well


----------



## Leah Frances

Wouldn't a hollow block wall do better than a solid one? Being that sound travels better through denser medium.....


----------



## Ted White

No. Mass is the primary driver in sound isolation.


----------



## Leah Frances

Ted White said:


> No. Mass is the primary driver in sound isolation.


That makes sense. Is it the same for rigid mass as flexible mass?


----------



## Ted White

Yes it is, although flexible mass will not have a resonance point that we can hear. Rigid mass will have an audible resonance point (called a coincidence point) which is why we damp that rigid mass.


----------



## dberladyn

There's lots of ways to sound proof, some of these although sound means of doing so are over kill in my opinion. For the sound seperation of two suites, an insulated wall with 5/8 drywall (and acoustical sealant) on either side should suffice. Want more preotection add another layer of 5/8's drywall. If you really want to ensure you don't hear anything as the poster above mentioned build both sides as seperate untouching walls.


----------



## Ted White

I think that's generally true. 

As a side note, insulation in a single stud (coupled) wall can drop the noise but not by much. Tests would show you'll get more bang by adding the drywall as you say.


----------



## rightit

Ted White said:


> I think that's generally true.
> 
> As a side note, insulation in a single stud (coupled) wall can drop the noise but not by much. Tests would show you'll get more bang by adding the drywall as you say.


Any comments on insulation in a 5" staggered wall (created from an existing 2x4 wall)? I plan on pink 3.5" paper-backed (paper facing toward the new space..."new staggered stud side"), stapled between the 'pre-existing' studs (about 8" cavities, unless I compress it behind the new staggered studs, which seems counter-productive). Is there a more efficient way to do this?

Thanks,
Mark


----------



## Ted White

Hi Mark,

Many people are inclined to install the insulation horizontally, essentially weaving the insulation back and forth between the staggered studs. This causes compressed pinch points when the drywall is installed. Much better to install the insulation vertically as best as you can. R13 is the insulation you want. You can use kraft paper faced insulation also. 

Just avoid compressing, and remember that you simply want the least expensive insulation you can find. Anything that says "acoustic" is likely sold at a premium.

Thanks,

Ted


----------



## rightit

Ted White said:


> Hi Mark,
> 
> Many people are inclined to install the insulation horizontally, essentially weaving the insulation back and forth between the staggered studs. This causes compressed pinch points when the drywall is installed. Much better to install the insulation vertically as best as you can. R13 is the insulation you want. You can use kraft paper faced insulation also.
> 
> Just avoid compressing, and remember that you simply want the least expensive insulation you can find. Anything that says "acoustic" is likely sold at a premium.
> 
> Thanks,
> 
> Ted


Hi Ted, thanks for your remarks. I'm actually planning on installing it vertically (cutting 8" strips) between the existing wall studs and the staggered studs. Also, I intend to place it against the existing hung drywall of the adjacent room, stapling it against the studs, paper facing the new space. 
Any problem with this? Should I bring it farther out to avoid contact with the existing sheetrock, sort of 'floating'? I've been so obssessive about sealing every possible path for sound, I may as well obssess over the insulation too. .

Thanks again,
Mark


----------



## dberladyn

Just don't compress the insulation and you'll be fine. If anything try to "fluff" it up as you install it.


----------



## Ted White

dberladyn said:


> Just don't compress the insulation and you'll be fine. If anything try to "fluff" it up as you install it.


There ya go!


----------



## rightit

rightit said:


> Hi Ted, thanks for your remarks. I'm actually planning on installing it vertically (cutting 8" strips) between the existing wall studs and the staggered studs. Also, I intend to place it against the existing hung drywall of the adjacent room, stapling it against the studs, paper facing the new space.


Believe it or not, I'm just getting the time to get back to this project and am determined to finish the entire addition in the next month. I'm about to get my framing rough-in inspection, so insulating is next. 

_Refresher: Staggered stud wall on 2x6 plate, double 5/8 sheetrock w/GreenGlue on both sides of the wall, acoustic sealant for seams, putty pads for outlets._


I plan on blown-on cellulose on the outside walls and, frankly, would like as simple of solution for the staggered wall I mentioned earlier in the thread (this wall will require a lot of cutting and fitting for the r-13 pink).

The worry is that the cellulose might 'short circuit' the decoupled wall if it's touching both sides of the stagger.

So the question is:

1) Is cellulose or foam as effective as R-13 pink if thickness is limited so as not to touch both sides of the staggered wall?

2) If it's not as effective, how much difference in STC at the given frequency are we talking about?

Thanks!


----------



## Ted White

If the cellulose was a low-density blow, you'd be fine. The concern regarding cellulose is when it's blown in to an existing wall or ceiling. The insulaton can get hung up and compress in spots, allowing conduction to occur, partially re-coupling the two sides of the wall.

Foam is to be avoided at all costs when soundproofing. While foam is superior to fiber insulation for thermal purposes, both open and closed cell foam is too dense and rigid for what we want.


----------



## rightit

Ted White said:


> If the cellulose was a low-density blow, you'd be fine. The concern regarding cellulose is when it's blown in to an existing wall or ceiling. The insulaton can get hung up and compress in spots, allowing conduction to occur, partially re-coupling the two sides of the wall.
> 
> Foam is to be avoided at all costs when soundproofing. While foam is superior to fiber insulation for thermal purposes, both open and closed cell foam is too dense and rigid for what we want.


Thanks for the fast response, Ted! I may just have to deal with the pink, then. As much effort and research as I've put into the soundproofing aspect of the wall, it'd be a shame to reduce its effectiveness and the 11th hour .

Thanks again,
Mark


----------



## Ted White

Sure thing. Again, the cellulose isn't a risk in open walls as you have (they're still open, right?) as long as the installer knows we want a light, low-density application. Otherwise, cellulose is excellent. If I were you, that's what I'd use, not fiberglass. The guys will be there pumping, and I'd just have them do the staggered stud wall, too.


----------



## rightit

Ted White said:


> Sure thing. Again, the cellulose isn't a risk in open walls as you have (they're still open, right?) as long as the installer knows we want a light, low-density application. Otherwise, cellulose is excellent. If I were you, that's what I'd use, not fiberglass. The guys will be there pumping, and I'd just have them do the staggered stud wall, too.


Now that makes my day . Again, thanks for your expertise!


----------



## Ted White

Sure is my pleasure. More questions = a better result


----------



## rightit

Original text deleted.


----------



## rightit

Another question. I bought my Greenglue a year ago last march. I've recently used a bit, but the company I bought it from said it would stay good for about a year. I'm going to be sheetrocking in the next month or so. I think it'll be OK. ANy opinions to the contrary?

Also, is using adhesive in addition to screws a good or bad idea as far as sound transfer? 5/8 rock, doubled on two walls.

Thanks!


----------



## Ted White

You should be good.


----------



## rightit

Ted White said:


> You should be good.


Thanks, Ted!


----------



## rightit

Hi Ted. If you haven't tired of my questions yet, here's another .

I'm about to sheetrock and am wondering if there is any advantage to applying GG or Silenseal to the studs before drywalling? 

This question occurs because I was pressing my ear against the existing wall studs and the staggered studs with a TV (with sound system) on (volume up) in the next room. 

While the existing studs definitely telecscoped more sound, there still was a surprising amount of sound when my ear was pressed to the isolated studs. The current state of the wall is 5/8" drywall and GG over existing 1/2" in the adjacent space and 1.5" mineral wool between existing studs (mostly not touching the staggered studs and not compressed). 

I'm sure that the the double drywall and GG I'll be hanging in the new space will make a difference, but want to make sure _all_ the bases are covered while they can still be covered...

Thanks for all of your help!

Mark


----------



## sbkim

Hi Ted - thanks for the valuable info. Any thoughts on the type of caulk with drywall to further enhance soundproofing? I know some companies offer fancy caulk for soundproofing but wasn't sure if I can use standard caulk?


----------



## Gary in WA

While you are waiting for Ted's reply, sit back and enjoy some soothing music: http://www.youtube.com/watch?v=I5NayResUUA

Gary
P.S. Keep the volume low....


----------



## Ted White

Wow. That was soothing... Not a good comparison, just FYI. Walls and floors are bounded by mass layers. In a wall you'd want cheap fiberglass.

You can use standard caulk, but you may find a quality acoustical sealant for the same price per fluid oz. as a quality 50 year latex painters caulk.


----------



## sbkim

Ted White said:


> Wow. That was soothing... Not a good comparison, just FYI. Walls and floors are bounded by mass layers. In a wall you'd want cheap fiberglass.
> 
> You can use standard caulk, but you may find a quality acoustical sealant for the same price per fluid oz. as a quality 50 year latex painters caulk.




Thanks Ted. That's exactly what John H told me today  any suggestions on which areas require caulking other than the obviously seams at the top and bottom of drywall? Thanks


----------



## Ted White

That's funny. Aside from the perimeter when both layers are done, you will seal outlets and other penetratons. Also, as you're drywalling, if there are gaps 1/4" or larger, put a bit of sealant in there as well.


----------



## sbkim

Ted - one more question if you don't mind. I presume many acoustical caulks (such as USG and OSI) are not water based so more difficult to work with vs. 50 yr latex caulk? I just want to provide fool proof items for my builder to avoid any hassles and errors. 

Thanks


----------



## Ted White

I would recommend using the product designed for a specific application. I would not use bath caulk on windows, and would recommend acoustical sealant for this application.

Most acoustical sealants are water based.


----------

