Author Topic: Will this final step make a difference? (soundproofing apt ceiling)  (Read 1053 times)


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I manage a rental property for a family member and will living in one of the units soon (also helped oversee lot of renovations to building), and we're trying to maximize soundproofing to avoid disturbing the tenant above, and limit noise heard from below. I'm OK with a little noise myself but we want it to be OK for other tenants in future. The current assembly from the apartment above to apartment below is as follows:

Hardwood flooring (older, has some gaps; 3/4" thick sanded down to close to the nails)
2x10 or 2x12 joists with R-19 fiberglass batts
5/8 drywall (DensArmor; long story)
Green Glue (has not yet cured; installed 5-6 days ago; only one tube used per sheet)
5/8 drywall (regular type X)
Green Glue (has not yet cured; installed about 3 days ago; only one tube used per sheet)
5/8 drywall (")
On 2nd and 3rd drywall layer, gaps were sealed with caulk (Smoke N Sound) and extra spackle.

[Due to an unusual layout, there is not much at all in the way of plumbing above, and where there is, it's in good condition (as is electric) and easy to locate, though yes, I know it will be a bear and a dusty mess to get to it if needed. I also realize there is a lot of weight on the joists, but the area is divided into several very small rooms where 2x4 walls are supporting joists (where there are not many full sheets installed), and part of it is hanging on huge and very well-supported center beam, so I don't think there's a structural risk.]

In spite of all this, foot impact is still fairly loud (though I was expecting that), and some airborne noise (coughing, loud music [and not just the bass], very loud talking) is still passing through.

My questions are these:
1) Did we shoot ourselves in the feet by adding all that mass and not using 2+ tubes of GG per sheet? (I suspected, perhaps wrongly, that this might be excessive and intended to sell as much GG as possible)
2) Is there a very big difference after the curing of GG (especially since only used 1 tube)? Or put another way, does GG have much/any effect before it cures?

As a last ditch strategy, if after GG curing it still isn't enough, could the following work?

*Glue up a final 1/4" drywall sheet with generous amounts of both drywall adhesive and GG (2 tubes/sheet), and see if it will hold with short screws screwed into the drywall (not the joists), and 2x4s to press the sheets up while the adhesive dries - or perhaps even anchor it into drywall above with screw anchors? The goal would be to further isolate impact noise by not continuing to make contact with the joists, and block airborne noise further. I know this may be a dumb idea that won't work for a ceiling, and would appreciate any feedback.*

The idea with this final step would be to create an assembly similar to QuietRock 545 which looks like is composed mainly of 1/4" drywall. The apartment is very small (about half the size of one above; only about 340 sq ft), so there isn't a ton of labor and material involved in doing one more pass with 2 tubes GG/sheet, which can get for $15/tube; and wouldn't necessarily be needed in all rooms. Would probably cost about $400-700 total to do the 1/4" + GG install depending how many rooms covered.

I know lot of mistakes/sub-optimal choices have been made and we probably should've hired a pro to do it right from the beginning, but at this point we're looking to move forward the best way possible.

PS: I'm new here and wanted to reach out to moderators to change the verification process. One question is 'stopping annoying noise means?' (two words). I tried 'shutting up' 'quieting down' and shut/quiet. Now I think the answer may have been 'sound proofing' ? Yet the website itself spells soundproofing as one word. Second one was 'how many robots?' I said none, answer was zero. This is probably costing them members; then 'girl's favorite color?' Pink is not correct. Kind of annoying; I think they should stick to simple math questions.