According to your plans (downstairs and upstairs), you've got several places where it appears you intend to "bridge" your decoupled walls together -- which defeats the purpose of their being decoupled. Is this an optical illusion?
Also, you're planning to use 1.25 centimeters (1/2") of plasterboard on your studio walls? Really? That's all?
sharward wrote:According to your plans (downstairs and upstairs), you've got several places where it appears you intend to "bridge" your decoupled walls together -- which defeats the purpose of their being decoupled. Is this an optical illusion?
Also, you're planning to use 1.25 centimeters (1/2") of plasterboard on your studio walls? Really? That's all?
Doh, dodgy early plans tastic bat man!
Those plans do show bridging between the walls as you pointed out and that is totally NOT what we're going to do!
Also, we're planning on two layers of plasterboard on the walls, one of 12.5mm and another of 9.5mm.
RichT wrote:Also, we're planning on two layers of plasterboard on the walls, one of 12.5mm and another of 9.5mm.
Ideally, what would you recommend?
I'm unfortunately not brilliant enough around here to be making recommendations for that sort of thing. But I can tell you that I'm going to be using at least 3 layers of 5/8" stuff for each of my leaves (almost 5cm) for my little garage space, and maybe more.
I suppose the question goes back to you in asking how you came up with those figures. Did you do TL calculations to determine what your likely results will be? Or are you just guessing?
RichT wrote:Also, we're planning on two layers of plasterboard on the walls, one of 12.5mm and another of 9.5mm.
Ideally, what would you recommend?
I'm unfortunately not brilliant enough around here to be making recommendations for that sort of thing. But I can tell you that I'm going to be using at least 3 layers of 5/8" stuff for each of my leaves (almost 5cm) for my little garage space, and maybe more.
I suppose the question goes back to you in asking how you came up with those figures. Did you do TL calculations to determine what your likely results will be? Or are you just guessing?
--Keith
Well, our wall design is based on John's double wall idea (plasterboard, plasterboard, stud, rockwool, air gap, rockwool, stud, plasterboard, plasterboard) which in theory achieves 63 STC.
Hopefully this will achieve what we see as an acceptable amount of 'bleed' between the rehearsal rooms.
Rich, that STC 63 layout has been around for a while, but to get that performance you need two layers of 5/8" each side (15mm) not 9 and 12 - you'd be losing quite a few dB of isolation (TL) at lower frequencies with the thinner stuff, depending on the space between inner and outer leaves.
Also, 63 dB STC sounds like a lot but that's at 500 hZ; the center range for the STC specification. Building that wall using 1/2" gypsum would only be 1 dB lower STC than building it with 5/8, but the TL at 50 hZ would change by about 5 dB due to the increased mass of the heavier drywall.
TL at low end, BTW, would only be about 28-35 dB - human hearing at that frequency requires about 50 dB just to be audible, so you'd be good on kick drum frequencies up to about 90 dB SPL, beyond which it would start to be audible outside.
Doing a double frame wall using 9 and 12mm drywall each side would result in approx. 4 dB worse than using either 12 or 15mm, and about 7 dB worse TL at 50 hZ than using two layers of 15mm drywall each side, in all cases assuming a 200mm total air space (from drywall surface to drywall surface inside the wall)
HTH... Steve
Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...
As we've yet to order the plasterboard for the internal walls I think we'll be upping it to the 15mm. It'd be silly not to as the cost difference is tiny.
That's all? 
