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Rincon 03-05-2008 08:11 AM

Interior wall sound dampening insulation
Any ideas on what to use as a sound barier in bathroom walls. I am thinking fiber glass would not be the best choice due to moisture and it is in the basement. I am using the foam board on my exterior walls so would this work for the interior walls around our bathroom as well? If foam board is the best in this application would I hang drywall on one side of the wall then attach the foam board with adhesive to the drywall before hanging the other side of the wall. Only purpose would be to keep it from shifting even though it would be cut to fit tightly.

handyguys 03-05-2008 08:19 AM

Insulation is not that good at stopping sound. You would be better off putting two layers of drywall on (plus the insulation). Double drywall on both sides is even better. We can make it even quieter but that would involve a more complex approach.

I actually have results of a very detailed study on what is best to help control sound. The study used scientific measurements and ratings for different materials used alone and in combination with different techniques.

Let me know, here, on in link in my sig, if you want the full blown conclusions.

travelover 03-05-2008 11:57 AM

I agree with handyguys - adding additional drywall is best for stopping noise. You want different thicknesses of drywall on opposite sides of the wall. This decouples the two walls. Fiberglass insulation in between will absorb high frequency noise. Also seal all holes, like around outlets.

mudmixer 03-05-2008 02:07 PM

Fiberglass is not very effective. Rock wool is much better.

Staggered studs also do a great job.

Daryl in Nanoose 03-05-2008 09:17 PM

Roxual safe ans sound works very well. We just did some walls around a furnace room and even drywalled on both sides of the wall and I couldn't believe the difference.

OtbHunter 03-06-2008 02:32 AM

Principal of Sound Conduction = The more dense the object - the faster and better sound travels thru it. i.e. Sound travels thru steel better than wood.
If you want a really quiet room - build the main frame (ends - top - bottom) using 2 X 6 stock... then add staggered 2 X 4 stock as needed to line up with the drywall. You will use more 2 X 4s this way but drastically reduce the sound conduction that occurs thru the drywall screws to the 2 x 4 to the opposite drywall screw.
As long as your 2 x 4s are staggered - the sound transmitted to the interior of the wall will not be sent thru to the next room but trapped in the baffled cavity you have created. Insulation is not needed but you can add it for piece of mind if you wish.
Hope this explaination makes sense to you... some insulation around the end 2 x 6s will be helpful as you will screw into this piece from both sides.

Rincon 03-12-2008 05:13 PM

Thank You all for the assistance. I have to say, WOW! More to this whole sound dampening thing than I ever thought. Not sure I want to go through it all though just to save a few embarrasing moments in the bathrrom due to noise. Think I will just stick to the single piece of drywall on each side of the studs. Thanks again.

triple D 03-12-2008 08:19 PM

Hey Rincon
If it's only a few embarrasing moments, just get a cheap noisy exhaust fan and no one will hear a thing. Just another thought......

handyguys 02-27-2009 04:29 PM

Sorry to dig up an old thread. I just covered soundproofing in my most recent podcast at
Episode #54 - Keeping the noise out

I Hope this helps somone

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