Reducing flanking noise transmission in through shared condo wall from...

kernel_kate

The party wall between my unit and my neighbor’s has two layers of 5/8" Type X drywall floor to ceiling, but above my bathroom and kitchen there are mezzanine crawl spaces where the second drywall layer was left with inconsistent gaps above the plywood deck — most likely sloppy finishing since it’s a mostly inaccessible space. I’ve been having significant sound transmission issues in these areas – I’m able to clearly hear everything my neighbors...

Originally asked by taylor018 on Stack Exchange (diy) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

I would use DMX underlayment on top of the plywood, then the 5/8" drywall and perhaps a 1/4" plywood screwed through to the joist just to protect the drywall. Use the Green Glue to seal the joints between the vertical and horizontal members. In this configuration, the DMX acts as a resilient channel. Green Glue has an STC of 16. DMX is 72.

Full answer by DelphicOracle: https://diy.stackexchange.com/a/330423 (CC BY-SA 4.0).

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