Date: Wed Mar 7, 2001 5:01 am
Subject: Re: Two layer drywall thicknesses
--- In acoustics@y..., SRF7@a... wrote:
> In a message dated 3/6/01 2:29:37 PM Eastern Standard Time,
> sjoerd@n... writes:
> > Scott seems to know the size of the job, I don't! So for what it
> > worth, its better to use 2 different thicknesses, or the same
> > thickness but different densities, like for instance one layer of
> > "normal" drywall, one layer of fire rated drywall
> Not really ... I'm guessing ... its imaterial really ... I'm just
> on how things go wrong on the job when you give the installer too
> choices and too many ways to run out of something.
> sjoerd is correct, differential materials work better .. that's a
> but since our choices were either both sides 5/8ths or 5/8ths and
> not so sure that differentiation would offset the loss of mass,
> if LF loss is considered more important.
> That said, even if the different flavor combo did work marginally
> we are cutting it close enough to worry that two layers of 5/8ths
> row of RC won't do the job unless we switch to 1/2" on one of the
> I'm thinking we need to beef the whole thing up ... because at best,
> to 1/2" isn't going to help much.
> Differential materials is a proven general design rule but I suspect
> effect would be small in the example cited (perhaps even a loss for
> damping). Maybe we should think about adding a layer of OSB, or
> (well caulked) underneath the RC .. then the two sides are very
> we've added quite a bit of mass for little cost.
> You are stuffing this wall with insulation aren't you? Maybe you
> us the run down on the entire wall system ... what kind of studs,
> scheme, etc.
> Do you have a target STC?
> Good Luck
> Scott R. Foster
> [Non-text portions of this message have been removed]
Thanks for the info thus far!
I'm attempting to reduce the sound coming from an exterior wall
in a room in my house. Not too far away is a railroad track -thus
the desire for a low frequency barrier.
I'm hoping to get an STC of >55.
Thus far the wall system consists of:
It's already much better than the orignal wall, but I was going for
the maximum possible with this setup. I'm going to have to replace
the siding in the near future. Should I have another layer of OSB
added to the outside?
Any other hints are appreciated. Thanks.