Cohousing-L Mailing List: Re: How to soundproof ... floors/ceilings

[James Kacki (jimkacki]

From the Canadian Code: (the data will be the very much the same in  
the US)

2 separated wood stud walls with 1 layer of drywall each side of the  
total assembly =STC 45 (can go up to STC 57 if acoustic insul. is  
used in the walls)

I layer of 8" conc. block alone =STC 50

So both are close and much depends on the detailing of the wall  
(resilient channels, acoustic insul., # of layers of drywall, etc.
All of this info. on STC ratings for various wall designs are  
available somewhere: municipal codes, internet, your architect, etc.,  
so best to look it up before designing your wall.
Yours in silence,
James

On 29-Jan-08, at 9:00 AM, Michael Barrett wrote:

>  "Michael Black" <mblack [at] mblackarchitect.com> said:
> At Yulupa Cohousing we used 2 separate 2x4 walls separated with 1"  
> min. of
> air space.   . . . . . .  This system is supposed to offer
> better sound control than masonry  . . . .
>
> ---------------------------------------------------------------------- 
> ----------
>
>
> Interesting since this is contrary to my experience living with  
> both kinds.
> While I have been unable to find any published numbers to support  
> (or deny) my experience but there is some data at
> http://www.practical-home-theater-guide.com/support-files/making- 
> walls-quiet.pdf
>
> In the table from the link - (which lost its formatting in the copy  
> and paste) - the number before the word "Note" is the STC- Sound  
> Transmission Coefficient . The higher the STC rating, the greater  
> the sound attenuation of the acoustical barrier: that is, a higher  
> number is better.  The link notes that the numbers don't add if you  
> add attenuating elements together, i.e. two walls 5/8" Drywall both  
> sides (at STC = 34) don't make an STC of 68.
> I have no connections with any of the products being discussed.
>
> Michael Barrett
>
> ---------------------------------------------------------------------- 
> ----------
>
> Construction Method - 2x4 wood studs, R13, with:
>
> 5/8" Drywall both sides 34 Note 4
>
> Double 1/2" Drywall on both sides 38 Note 4
>
> 1lb Vinyl under 5/8" drywall 43 Note 5
>
> Resilient Channel 24" OC, ½" drywall 43 Note 4
>
> Homasote® SoundBarrier® under 5/8" drywall under both sides 45 Note 1
>
> Resilient Channel 24" OC, 5/8" drywall 48 Note 4
>
> QuietRock 525 on 1 side, std. 5/8" opp. side 51 Note 5
>
> QuietRock 530 over 5/8" gyp on both sides 56 Note 5
>
> Construction Method - 8" Cinder Block Wall 43 Note 2
>
> Construction Method - 3.5" steel studs, R13, with:
>
> 5/8" Drywall both sides 45 Note 4
>
> Resilient Channel 24" OC, ½" drywall 49 Note 4
>
> Homasote® SoundBarrier® under 5/8" drywall both sides 51 Note 1
>
> QuietRock 525 both sides 53 Note 5
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