QuietRock Nailed to Studs vs. Sheetrock/Green Glue/Z-Channel

[greatmagnet]

Hey Folks...brand new member here...very first thread! Be kind, be kind...

So, as you can probably tell from the title of my post, I am in the midst of my studio build and it is not (because of budget and space issues) the kind of build where one does the true room-within-a-room thing: for a while now we'd been operating under the assumption that we'd be hanging Z-channels (or hat for ceiling) from the studs, then covering the hat channel with 2 staggered layers of sheetrock with copious green glue in-between the layers. The other side of said studs connect with the outer walls of my garage and we've insulated in-between the studs with standard R13 fiberglass, tucking it in nicely to allow the hat channel air gap.

So, where I live in Santa Rosa, CA we are fortunate enough to have a local supplier who carries not only green glue but also QuietRock...which I'm sure many here have heard of and seen the literature for. QuietRock, being a multilayer sheetrock which incorporates a layer of ceramic as well as the usual gypsum, CLAIMS to be as effective as TEN layers of sheetrock, and it seems that...perhaps because of this...the contractors around here have always been asked to nail it directly to the studs...not separated from by hat channel.

At $57/sheet, the QuietRock is still a bit more expensive than two layers of standard sheetrock plus green glue, plus hat channel....marginally. But the idea of skipping all those extra step is of course ***y...but will it work? I myself am really doubtful and wonder if anyone has seen any measured comparisons or has any real-world experience with either technique?

From what I've read in both the Rod Garvais book as well as at the GreenGlue site, it seems that the idea of acoustically isolating the 'rock from the studs with the hat channel and also creating an air gap between the sheetrock and the underlying insulation/stud/outer wall unit is absolutely critical in stopping those waves. It seems like nailing QuietRock directly to studs...even knowing how non-transmissive that stuff is...couldn't possibly be that effective?

One of the walls of my garage adjoins our house and so it's absolutely critical that within the confines of my budget I get some appreciable transmission loss, or I will be unable to run sessions without getting in constant dutch with the girlfriend!

Anyone who has any experience with this or can point me to some links please chime in!

Thanks,
Adam

[MadMax]

Welcome Adam!

I'm kinda', sorta, just a little bit familiar with Rod's design philosophy... :)

Having been building my place for a bit, <snork>, I can tell you that while I firmly believe hat and Z channel are very viable solutions, I think that there are other more viable solutions, that are a buttload cheaper, easier and probably at least as effective in most practical applications, and double, triple or more in a worst case scenario.

The problem with hat and Z channel is that you CANNOT short out a single screw, where you drive a screw too long and it shorts to the stud. POOF! All your work and money is shot to hell. Lovely, huh?

Do that a dozen times, and see what your TL and isolation numbers look like...

The reality of physics is that mass is your best friend.

My walls are 3/4" OSB with 2 layers of 5/8" FR gypsum with green glue. Then acoustic treatment over that.

The OSB can be swapped out for anything 3/4"... plywood, MDF, etc.

The 3/4" sheet goods offer a lot of structural stiffening, which drives the f0 down. And you get the added bonus that it doesn't matter where you drive your screws, and you can drive more screws, in tighter patterns.

My humble $.02 worth
Max

[Rod Gervais]

MAx (my friend)

you ignore that face completely that he is using one wall construction - and although the mass will help to am extent -you still have the issue of decoupling the mass from the outer sid of the wall.....

Adam,

Your best bet under this scenerio would be to use RICS clips - with hat channel - which makes it impossible to short out (Max's concern above) and then drywall with green glue - and all that for a hell of a lot cheaper than the Quietrock.

[MadMax]

MAx (my friend)

you ignore that face completely that he is using one wall construction - and although the mass will help to am extent -you still have the issue of decoupling the mass from the outer side of the wall.....

OOOPS, I misread the detail of single stud, into using Room in Room... guess I read that first paragraph too fast and skipped the MINOR detail of the word "not";
"I am in the midst of my studio build and it is not (because of budget and space issues) the kind of build where one does the true room-within-a-room thing:"

My apologies, but I stand corrected. Thank you for catching that!

I hate giving bad information, and especially when it can cause an expensive mistake!

Max