John Sayers' Recording Studio Design Forum Archive

Hey guys..need some advice on some things. Recently finished building a drum booth onto the side of my studio, using wood frame floor w/ plywood, 2x4 framed walls, double 1/2" drywall on the inside, double 1/2" plywood on the outside. The room is built under a pre-existing awning with a tin roof, and the ceiling of the drum room is decoupled from the tin roof, with insulation stuffed between the two for absorbtion. Of course, this design didn't give much isolation, and that brings me to the new design...we are planning on building another wall all the way around this room(except the side that is connected to the rest of the studio), decoupled about 1 1/2 feet from the inner walls. We will put 4x4 posts into the ground, stabilized by concrete, and put 2x4's vertically between these (sorta like a resilient channel, only made of wood) and screw 3/4" plywood to the 2x4's on the inside, and on the outter side do the same, but use partical board (compressed sawdust), and sandwich insulation in the middle. We will then extend the tin roof to connect to this wall as its roof. Would this method work? Also, would we need to make another ceiling for the new "shell"...or would the tin roof do the trick? There will be no holes in the new wall, except that for a door. Please let me know if this would help, it was recommended by my teacher (mediatech institute/dallas sound lab) Thanks guys.
Bryan

Your teacher and you both should read everything on this page

http://www.domesticsoundproofing.co.uk/tloss.htm

especially the part starting with Mass-Air-Mass - then, check out the graphic at the bottom of the page, and note the difference in materials used between the 40 dB wall and the 63 dB wall - NONE !!!

Basically, what you are proposing is the equivalent of the 40 dB wall, when for the same amount of material you could have even BETTER than the 63 dB performance, because you're talking about a much wider air space.

What you really need to do is REMOVE the panels on the outer side of the existing frame and relocate them to the inner side, making more layers on just the one side of the old frame - then build your new frame and put your paneling ONLY on the OUTSIDE of that frame, stuffing the inner stud cavities with insulation. That will give you the best isolation for your time/money, period.

I know this seems counterintuitive, but it really works. Here are some general rules, etc, on wall construction techniques that also might help you -

http://johnlsayers.com/phpBB2/viewtopic.php?t=598

Come on back after you read this stuff, and I'll try to answer any further questions... Steve

Thanks Steve...sounds good..and not too much harder. Only question i have left is, what do i do about connecting the tin roof to the new wall? Will this make the transmission loss suffer? Do i need to add a new ceiling? Thanks again.
Bryan

Yeah, sound LOVES the "weakest link" theory - This will give you some idea of what works best - scroll down to the bottom for ceiling ideas -

http://www.saecollege.de/reference_mate ... 0Chart.htm

Unfortunately, those are for inside downstairs rooms with living space above. Still, the general idea is there.

Without a picture or drawing, I'd think you would be better off considering that tin roof only for weather, leaving it "breathable" by venting, and building a new ceiling under it that meets the "Two leaf, one air space" rule. You could put a couple layers of OSB or Waferwood (different thicknesses is best) on the outside of the new ceiling frame, then put Resilient channel (Dietrich RC Deluxe if you can find it locally)

http://www.dietrichindustries.com/bigdp ... sories.htm

Put the RC on the inside (search this forum for RC and Resilient, there are several threads) then suspend two layers of sheet rock from the RC, caulk with acoustic sealant, and rock on...

If you can, post a drawing of some kind with dimensions (including ceiling height) and enough detail to tell what's what - it will make it easier (possible, even) to help you figure out exactly what to do... Steve

Oh, you didn't say what kind of span you're talking about for the roof/ceiling, but I'd go one size larger for joists if you're going to hang several layers of sheet rock -

If you like, go here

http://www.cwc.ca/design/design_tools/

and download the portable version of Spancalc 2002 - it's a html calcuator for spans of floor, ceiling, roof, etc - be sure and use the US species setiings. As I said, I would increase framing size by one notch (8" instead of 6", for example to allow for the extra layers... Steve