sound proofing walls

18287 Views 36 Replies 10 Participants Last post by Ted White, May 30, 2012

tiki16

Discussion Starter · May 4, 2011

HI, I am renovating an existing reno in a basement. There are 2 bachelor apts adjacent to each other. There are 2 walls between them. 1 wall consists of 1/2 inch drywall on each side and pink insulation with vapor barrier in the middle.

Should I tear out this wall and put soundproofing insulation in place of the pink fiberglass? Or just put up another layer of 1/2 inch drywall to cut down on the noise? Does r12 fiberglass provide any noise proofing?

The other wall was framed with 2x3" studs and 1/2 inch drywall. I wanted to put in roxul sound/fire proof insulation. Will it fit a 2x3 or does it have to be 2x4?

Thanks
Steve

1 - 20 of 37 Posts

dberladyn

· #2 · May 5, 2011

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

· #3 · May 5, 2011

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

· #4 · May 5, 2011 (Edited)

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

· #5 · May 6, 2011

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.

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Ted White

· #6 · May 6, 2011

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

diy-581

· #7 · May 6, 2011

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

· #8 · May 9, 2011

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

· #9 · May 9, 2011

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

Ted White

· #10 · May 9, 2011

No. Mass is the primary driver in sound isolation.

Leah Frances

· #11 · May 9, 2011

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

· #12 · May 9, 2011

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.

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dberladyn

· #13 · May 9, 2011

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

· #14 · May 9, 2011

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

· #15 · May 10, 2011

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

· #16 · May 10, 2011

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

· #17 · May 12, 2011

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

· #18 · May 13, 2011

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

Ted White

· #19 · May 13, 2011

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

· #20 · Dec 30, 2011

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!

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