John Sayers' Recording Studio Design Forum Archive

SINGLE WALL GARAGE CONSTRUCTION QUESTIONS

First of all, thanks for creating and maintaining such a valuable resource for studio-builders.

Here's my scene:
Soon, I'll be moving into a house with a detached garage I can use as a studio. My sound isolation needs are relatively lightweight. I'll mostly be tracking and mixing electronic music and electric guitar, probably no live drums. The garage as it stands is single-car, on concrete slab. Wood stud walls; don't know exactly what's on the outside under the stucco, but there is a layer of drywall, unsealed, on the inside (walls and ceiling) I'm hoping to make this work without removing that layer, and only building one more wall, in front of the garage door.

(The site, and my resources , are far from ideal. I'm trying to make my half-assed situation at least 2/3 assed, and trying to avoid putting scarce time and money into measures that are useless.)

I've been reading a lot on the site, and reading some of the cited docs. There is a bit of conflicting or developing info and opinions, some things I haven't found, which leave me with some questions, and some things need confirmation. Here they come:

On the existing drywall: is it correct that I should mud and tape all sheet to sheet seams, and acoustic caulk all perimeters? Is there's a wide interior gap, maybe that should be caulked?

On putting more mass onto the existing drywall: One post said that another layer of drywall would be so coupled to the existing drywall that it would only raise the isolation a few db. If that's true, it almost doesn't seem worth it. But, what about a layer of fiber soundboard, or the GAF TP-4 rubber roofing roll (but is that the flammable stuff?) then more drywall?

If a second layer of drywall (in opposite orientation) is adhered to the first, is it correct that it should be screwed only (with the right screws) to the first, avoiding the studs?

On the bottom gap and caulk, would one be any use if the existing layer is resting on the slab, as I suspect it will be? I could possibly carve some off the existing layer...

On the door, is anyone familiar with that Owens-Corning "Quietzone" door? It's attractive because it's pre-hung and has some kind of sealing, but I don't know the cost. It's rated at STC 25 - don't know if that's good for a door or not. I've hung solid-core doors and used magnetic refrigerator door seals on a studio before, and could again.. Or, the O-C door could be beefed up...

Perhaps that's enough for part 1 - I've got a few more q's to come. Thanks in advance for any advice.

scodav

On the existing drywall: is it correct that I should mud and tape all sheet to sheet seams, and acoustic caulk all perimeters? Is there's a wide interior gap, maybe that should be caulked?

True on the first part - wide gaps don't work with caulking, not sure what you mean by "interior" gap -

On putting more mass onto the existing drywall: One post said that another layer of drywall would be so coupled to the existing drywall that it would only raise the isolation a few db. If that's true, it almost doesn't seem worth it.

Mass law states that it takes a doubling of mass to improve TL by 5-6 dB - this is true whether resilient mounted or not, just a fact of physics.

But, what about a layer of fiber soundboard, or the GAF TP-4 rubber roofing roll (but is that the flammable stuff?) then more drywall?

Again, mass law - gypsum layers are generally your cheapest, best, least flammable mass short of concrete. Using different thicknesses can help eliminate coincidence dips @ around 2500 hZ, but overall mass is what works.

If a second layer of drywall (in opposite orientation) is adhered to the first, is it correct that it should be screwed only (with the right screws) to the first, avoiding the studs?

USG states that you can do this, using their Type G screws - however, Rod Gervais and I have hashed this over privately quite a bit and came to the agreement that there were too many ways to screw this up - as such, we don't recommend it. If you are building either RC decoupled single frame walls, or non-RC DOUBLE frame walls, the slight bit of flanking that could be caused by screws penetrating both layers of wallboard on either side, will be absorbed by using proper (2.5 to 4 PCF) glass or mineral wool insulation.

On the bottom gap and caulk, would one be any use if the existing layer is resting on the slab, as I suspect it will be? I could possibly carve some off the existing layer...

Unless the existing wallboard layer is already mounted to Resilient mounting, this would be of little value. I'd just add the second layer using 1/4" shims, then pull the shims after fastening and caulk thoroughly.

On the door, is anyone familiar with that Owens-Corning "Quietzone" door? It's attractive because it's pre-hung and has some kind of sealing, but I don't know the cost. It's rated at STC 25 - don't know if that's good for a door or not.


A single, solid core exterior door panel 1-3/4" thick, would test at around STC 28-30 - the seals would be the weak spot in any case. I've yet to see anything about the "quiet zone" stuff that's impressive, other than the cost (and, as you mentioned, the looks)

I've hung solid-core doors and used magnetic refrigerator door seals on a studio before, and could again.. Or, the O-C door could be beefed up...

If you've already done this successfully, I'd go that way unless you found something you didn't like about it - it's hard to argue with success... Steve

Hey, thanks Steve, for your time on this. (Your comments starred).

By "interior gap" I was trying to ask about whether to caulk or mud any gaps between sheets on the existing layer. I'm guessing now that the acoustic caulk is to avoid passing vibrations from one plane to another, or to the floor slab, and mud's the thing mid-wall?


**Mass law states that it takes a doubling of mass to improve TL by 5-6 dB - this is true whether resilient mounted or not, just a fact of physics.

Sounds like a second layer of drywall is worth doing. In addition to the 5-6 dB, it'll act as a super-seal on the existing layer.


**If you are building either RC decoupled single frame walls, or non-RC DOUBLE frame walls, the slight bit of flanking that could be caused by screws penetrating both layers of wallboard on either side, will be absorbed by using proper (2.5 to 4 PCF) glass or mineral wool insulation.

I'm just talking about adding a second layer of drywall to existing walls - no RC or double frame walls. Should the second layer screws penetrate the studs?

Hey, thanks again - this is an invaluable resource!

scodav




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First part - check this thread -

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2765

last part - if you're not removing the old wallboard, you would need to screw into studs for second layer - before that, find ALL fasteners and put masking tape on the adjacent surfaces so you can mark where they go - if it's a small wall, you might be able to just make a chart of x-y coordinates, but you don't want to hit any of the existing screws with new ones.

You will get some flanking through the screws into frame, but we've come to the conclusion that those special "laminating" screws are not something many people (including me) can reliably get away with, so I don't see much choice. If your needs aren't extreme you won't notice it anyway... Steve

Thanks, I think I've got it. That thread on drywalling and caulking is excellent - very clear.

scodav

Just a FYI. I've been looking into the Owens corning Quietzone products. The prehung door is an inside-only door for bedrooms and such. It's a composite material that is still light and attractive as an interior door. They also sell Quietzone Caulk, insulation, rubber sheets and drywall in that series.

Yeah, I've looked at that line also - while they're undoubtedly quieter than the average home building materials, they don't seem to be up to studio standards at all - I'm not saying they wouldn't help a bit, but I think you can do better for less as far as sound control is concerned... Steve

scodav wrote:**Mass law states that it takes a doubling of mass to improve TL by 5-6 dB - this is true whether resilient mounted or not, just a fact of physics.

Sounds like a second layer of drywall is worth doing. In addition to the 5-6 dB, it'll act as a super-seal on the existing layer. "

Scodav,

The mass law relates to the wall as a whole......... on the building exterior you have Stucco over some type of sheathing, and on the interior the existing drywall..........

Adding a single layer of drywall on the buildings interior will not double the mass.......

Thus in order to acheive the additional 6db of reduction you will have to take the exterior mass into account as well.

Understand that the exterior also (most probably) is nowhere near air tight - completely sealing this would go a long way towards helping you as well.

Rod