How effective is just a second layer of drywall at soundproofing via /r/DIY


How effective is just a second layer of drywall at soundproofing

Hi everyone,

I just bought a new condo, and I'm kind of dismayed by the amount of noise I can hear through the walls. It's not a ton, but it's enough that I can hear my neighbor having loud conversations (muffled), putting away dishes, or watching movies (muffled, but enough noise to disturb me).

I've looked at the wall, and what I think I have is a standard drywall-wood stud w/ insulation-drywall setup between us. I've been doing research, and what I've found is that there are really a few options:

1) Add mass via adding more drywall layers

2) Add mass via another drywall layer w/ green glue

3) Go all out, demo the existing drywall, and put in a staggered wall, probably with two layers of 5/8" drywall on my side.

Space is at a premium, and I don't have a massive budget. Several contractors have come over and suggested putting resilient channel or hat channel overtop the existing wall, but I'm pretty sure that creates a triple-leaf, which is not a great idea for soundproofing.

So I guess my question is:

How effective is another layer of drywall on its own? Or two? I'm not opposed to adding two more layers: 1/2" and 5/8", to create a drywall-stud with insulation-drywall drywall drywall wall. I've read the NRC reports and done tons of research online and I get confusing answers. A lot of STC tests report a minimal increase in STC (2-5 dB) for a second drywall layer, making it seem like GG is a must to acheive noticable decrease in noise. But when I read A/V forums, I see that a second layer of drywall, with no GG, is probably the best bang for the buck. So I'm confused on whether just a standard double (or triple) drywall layer will actually help without any kind of acoustic material like GG or soundboard.

Also, if I do decide to add a staggered wall, should I try metal studs? That'd wind up mixing and matching wood and metal studs, and I have no idea if that kind of thing is done or is even a good idea. But I'm curious about metal studs because they are extremely effective at sound reduction.

Finally, resilient/hat channels are out of the question because my furniture is mostly wall mounted and very heavy (one wall-mounted bookshelf will hold 400 books, totaling several hundred pounds, which I guess adds a ton of mass to one wall).

Alternatively, I could just finish renovations, sell the condo, and move back into my old apartment that was actually soundproof…

Submitted May 05, 2021 at 09:04PM by Auerilas
via reddit

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