Author Topic: Soundproofing existing walls with injected foam  (Read 22052 times)

han555

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Soundproofing existing walls with injected foam
« on: November 05, 2009, 01:07:31 AM »
I just bought a condo and the walls are very thin so my neighbor can hear me watching movies late at night.  Her bedroom shares the wall with my living room :(  I don't want to bother my neighbors but I also don't want to have to turn off the TV at 11pm.  I also play guitar and would love to be able to play at night.  Are any of these foams that you inject into the walls and ceilings any good?  Is there anything I can do short of building a second wall in the apartment that would significantly reduce the noise transmitted through the walls?  I don't have a huge budget to work with so I was hoping I could do the foam project myself.  If that wont work, what am I looking at?  Roughly how much would it be to contract professionally soundproofing a 20' wall and a 10' wall?

Chris J

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Re: Soundproofing existing walls with injected foam
« Reply #1 on: November 05, 2009, 02:11:34 PM »
framing and building a second wall should be an easy and relativly inexpensive job......a handy person could do it in a few hours.  insulate, hang new drywall and you're there....if it's still a problem you could then cap the new wall with an extra layer of sheetrock applying green glue or MLV in between. this i think would be the most proactive approach.

I'm about to skip to the latter and cap my existing walls with GG and 5/8th's sheetrock to soundproof for traffic noise. If you did this you're looking at the cost of the sheetrock 7 or 8 bucks a sheet and the MLV or GG. I believe you can price those items out on this website. Again a handy man type should be able to do this in a few hours....

han555

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Re: Soundproofing existing walls with injected foam
« Reply #2 on: November 06, 2009, 02:23:14 AM »
The problem is that I live in Brooklyn and don't want to lose the space.  Was hoping there's a way to do something with the existing walls because the area is already very small.

Chris J

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Re: Soundproofing existing walls with injected foam
« Reply #3 on: November 06, 2009, 05:04:19 AM »
you'd only lose 5/8th of an inch.....

han555

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Re: Soundproofing existing walls with injected foam
« Reply #4 on: November 06, 2009, 05:21:35 AM »
Oh, I thought you meant I needed to build a wall within a wall.  Will just screwing new drywall onto the existing drywall really make that much difference?  Is there anything I can add between layers that will help even more?  I just read up on green glue... is there anything to use with that to improve the results further?

What about the ceiling?  Would foam be of any use for that?

Chris J

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Re: Soundproofing existing walls with injected foam
« Reply #5 on: November 06, 2009, 02:03:52 PM »
i dunno anything about foam.....i haven't even tried the MLV or GG sheetrock sandwhich...if you went that rout though you could just keep adding more layers until the problem is solved. if you scower this forum you will certainly find some success stories and failures. seems like you have it pretty easy though, you're not dealing with say the rumbling of a semi-truck idling in traffic in front of your house.

Randy S

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Re: Soundproofing existing walls with injected foam
« Reply #6 on: November 06, 2009, 04:17:38 PM »
Your on the right track, If your just dealing with T.V. , people talking etc. then you can add a layer of 1/8" MLV w/psa followed by green glue and 5/8" drywall. This is a common system for ambient noise, if you are dealing with low frequency (bass) it would need to be decoupled for best results.
Total loss of wall space with this system would be 7/8" and cost for soundproofing materials would be around $3.60sqft. not including freight.
Fairly simple to install if you can hang drywall.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

Randy S

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Re: Soundproofing existing walls with injected foam
« Reply #7 on: November 06, 2009, 04:19:27 PM »
Spray in foams are for thermo applications...when it comes to sound you can actually cause more transmission paths in the wall if the foam expands contacting both sheets of drywall. Blown in insulation would be better than a foam.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

han555

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Re: Soundproofing existing walls with injected foam
« Reply #8 on: November 06, 2009, 06:02:22 PM »
Ok, great.  Thanks for all the info guys.  Definitely very helpful.  Do you think it would make much difference if I only did the walls?  Or will the sound just travel through the ceiling and be just as loud next door?

Randy S

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Re: Soundproofing existing walls with injected foam
« Reply #9 on: November 06, 2009, 07:08:02 PM »
This is known as "Flanking noise" and yes chances of it accuring are there, however it would be at a lower db level.
Most likely that will do the job unless footfall, impact or low bass are involved.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

han555

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Re: Soundproofing existing walls with injected foam
« Reply #10 on: November 06, 2009, 07:10:45 PM »
Terrific.  I'm going to give this a shot.  Thanks so much.  Will post my results!

han555

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Re: Soundproofing existing walls with injected foam
« Reply #11 on: December 12, 2009, 11:02:48 PM »
I haven't gotten around to doing any of this yet, but I'm finally about ready.  Had to save up some money first :)  Was reading up on the MLV and GG combo technique and it seems to contradict what is said on the GG site about applying it between two rigid layers.  If you apply the GG to the MLV, is it a problem that the MLV isn't as rigid as drywall?  Or will MLV and GG always outperform just GG?

han555

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Re: Soundproofing existing walls with injected foam
« Reply #12 on: December 12, 2009, 11:17:09 PM »
Also, what MLV is ideal for wall application?  With or without the foam?  I was thinking that properly installing drywall on top of the foam kind would be much more difficult.  And if I don't get the kind with the adhesive on the back, is simply stapling it near the ceiling and letting it hang down sufficient or do I need to stale it flat to the wall before applying the drywall with GG?  Seems like the drywall would just flatten it out and make it flush with the original wall, no?

 

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