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sound proofing walls

19K views 36 replies 10 participants last post by  Ted White 
#1 ·
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
 
#4 · (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.
 
#5 ·
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.
 
#7 ·
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...
 
#8 ·
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.

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
 
#13 ·
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.
 
#15 ·
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
 
#16 ·
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
 
#17 ·
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. :eek:.

Thanks again,
Mark
 
#21 ·
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.
 
#23 ·
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.
 
#27 · (Edited)
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!
 
#30 ·
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
 
#32 ·
#33 ·
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.
 
#36 ·
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
 
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