Author Topic: stc rating for newly constructed wall  (Read 6713 times)


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stc rating for newly constructed wall
« on: April 01, 2009, 07:02:48 PM »
i am building a high end apt.building in nyc and i am looking to get an stc rating on a wall assembly that we installed. The wall is constructed as follows. The wall is 3 5/8 stud framed from slab to slab. There is a framed ceiling about one foot down from the slab. We sheetrocked the ceiling then insulated the wall and sheetrocked the wall with the wallboard stopping at the drywall ceiling and not continuing to the slab. The bottom of the wall is caulked with sound caulkimg. The drywall on the ceiling is 5/8 as well as the dryall on the wall. This application is the same on both sides of the wall. The void on the 3 5/8 wall above the framed and rocked ceiling is not rocked or insulated. any help in this area is greatly appreciated.

Randy S

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Re: stc rating for newly constructed wall
« Reply #1 on: April 02, 2009, 03:54:20 PM »
Double leaf 5/8" drywall and 2"x4" wood studs / no insulation..real life results and not lab results....STC Rating 18 - 20 if your lucky. I wouldnt be surprised if regular speach is audible and inteligible.

If your looking to improve your situation, I would recommend adding MLV w/psa followed by a new layer of 5/8" drywall with Green glue sandwiched in between.

MLV link.
Green glue link

This system will address airborne noise and some vibration, if you are dealing with LF (bass) then we will have to take another approach.


  • Guest
Re: stc rating for newly constructed wall
« Reply #2 on: April 09, 2009, 07:21:52 PM »
Well, you'll certainly get better than STC 20 (equivalent to a hollow-core door - a single piece of drywall by itself rates a 26) but if, as you said, you're building 'high-end', the wall assembly you've built won't cut it, not even close.  You'll have every one of your residents screaming for their money back!  Maybe suing, too.

The building code calls for STC 50 between units, and a high-end unit should probably shoot for 60, minimum.

I'd recommend tearing out the old work and converting the walls into staggered studs, insulated, with 2 or even 3 layers of 5/8" drywall, sealed well.  Hang the ceiling resiliently with Iso clips (aka SSP clips) and hat channel.  Double layers of 5/8" drywall on the ceiling, too.  Take great care in sealing gaps and you should approach a 60.