John Sayers' Recording Studio Design Forum

Hi:
New guy on this block, howdy all.
I'm rebuilding the wall separating my control room from my main tracking room, due to water damage from a burst pipe. I really only need to replace the soggy drywall, not start from scratch. It is double studded, though the footers rest on a common cement slab. Separation has been quite good in the past, i.e. a sax player can warm up by playing into the glass on the studio side & I almost don't hear it on the control room side. So I don't have a problem in need of a solution, but if I can get a few db more attenuation I'd like to try it. I previously had one layer of 5/8" drywall on RC on both sides. My question is twofold (1) Is the RC really achieving anything worth going through the additional expense & trouble to recreate? Or does it buy me so little in additional transmission loss that I might as well just attach to the studs? And (2) has anybody ever used, or heard of the practice of using a layer of backer board (AKA Hardieboard) in conjunction with the drywall to get a lot more mass in place? Does backer board seem sensible or just stupid?
Thanks,
Scott Fraser

Greetings; I’m new to this too, getting ready to start my build!

Everything I’ve read here and elsewhere suggest the RC is key, as it helps decouple the drywall from the wall frame, thus limited transmission. If what you had worked well, I’d stick with that, but it appears to be standard to have two layers of 5/8" drywall; put Green Glue between the layers for added benefit on each side (ensure second layer overlaps seems of the first). I"ll be using RISC clips with Hat Channel, which I take to be even better than RC. As far as Hardieboard, I've not heard of or read of its use -- my sense is the best advice is to stick with tried and tested methods (e.g., what Gervais says). Make sure that you seal everything, caulk, etc., as folks appear to forget this detail.

Good luck!

RC and clips, hat track or what have you are a means to decouple the walls assembly, one side from the other to break the path of vibration.


Now, in the event, that you have a "double studded" assembly, there was no need for rc...and you will not find support for that thinking here or anywhere on the Net that deals with hard data. Facts prove that this is actually a waste of your money and labor since the gained received is less than already existed with a fully decoupled wall assembly.

To both of you, but mostly to MJG, get your facts correct, and move forward according to those facts, since neither of you are correct in this respect.

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Brien Holcombe
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Sound: You can't stop it, you can only try to contain it.

To clarify, my incorrectness was in originally using RC on a double studded wall?
Any thoughts or opinions on the use of backer board?

Thanks,
Scott Fraser

Well, clearly I misunderstood what a double-studed wall was and how it functioned (and possibly changed my own design)! Looked it up, very helpful. Thanks Brien!

correct - no RC or isolation clip/hat channel on double walls - only on single walls. you could use backing boards like Homasote 440 which can add some damping and helps with any rubbing on the framing but you could also just use 1" felt tape on the studs and joists too. or simply skip and go directly on the frame. it usually comes down to how far you want to go with the details and your budget.

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Glenn

Great. Thanks for that confirmation.



I can't add too much thickness, since there is an existing window sill in the control room wall, which was undamaged. I have about 1/2" to play with on each side, in addition to the 5/8" drywall. And I have to get this built pretty quickly, since this is a busy studio, & I've been canceling sessions scheduled for weeks now.
Thanks for the pointers,
Scott Fraser

Great. Thanks for that confirmation.

[quote]

The confirmation was available from a clear research done on the Internet after it as explained to you both that you were in correct in your attempts.

So let me address the backer board, and maybe either you will research it, it will make sense or you will look for confirmation from another source, either way, it is your time and money.


A typical framing layout will be 16 inch increments. Typical backer board comes in 3' X 5' sheets.
To accommodate this would mean a change in framing layout that would be a challenge to the diy home studio construction person.

But where is the data that supports not only the backer board, which was surely gleaned from the same source that said rc and double framing is a good idea, but even to suggest that there is some measure of relief by installing what is a typical friction damping reduction from either tapes, or homosote, or what have you in this respect.

If it has not support outside of people who are selling it, then it should be viewed with a more cautious eye, since the labor involved and the cost....with no hard data to prove this effect either one way or the other, only prove to support that someone said something, and you listened, but it does not make it a fact that should find continued support.


I build things everyday and if I guessed or simply took a webpage and considered it truth, just because some guy said it, most of what I build would have failed either inspection or over a time frame.

Neither has happened in my life time, since I do not buy into ad copy but I continue to be educated in a construction field I work in, not that I just type in a forum about.



If you would like to review the data that supports the double framed double sided 5/8 inch fire rated wall assembly versus the same wall with RC and what reductions you will incur in your transmission loss/STC, I will get the link for you once at the home station.

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Brien Holcombe
_____________________________________________
Sound: You can't stop it, you can only try to contain it.

Hi Scott. I'm coming in a bit late on this, and you might already be finished with the repairs, but here's a couple of comments that might help:

As the others already said, the RC is a waste of money, and buys you nothing at all. If the wall is properly decoupled with two separate stud frames, then it is already decoupled: you cannot decouple it any more by also adding RC. Whoever did that original design doesn't have much clue as to how isolation works. So leave out the RC for sure. Waste of time, money and space.

If you are leaving off the RC, then you will be gaining a lot of space, so that should not be a problem.

However! Leaving off the RC (or clips + hat channel) on both sides of the wall means that your air gap (cavity inside the wall) will be smaller, which raises the MSM resonant frequency of the wall, thus reducing isolation in the low end. Probably the effect won't be that great in your case, since you'll still have about 8 inches of air space in there, so I wouldn't sweat it too much. It would only be an issue if the air gap got down below about 4" or so.

On the other hand, the extra space gained by taking off the RC / clips+channel means that you have plenty of room to add a second layer of drywall on each side, and that will make a huge difference to your isolation. Two layers of 5/8" drywall over an 8" gap with plenty of insulation inside is going to give you excellent isolation, and is well worth doing. And if you can afford the extra expense, adding a layer of Green Glue between the sheets of drywall will improve things even more, in the low end. Forget the backer board, and go the proven path with more drywall and GG.

One more caveat: since you had flooding from a broken pipe, I would take care to inspect the framing and insulation inside very carefully, to make sure that there is no water damage in there, and also make sure it is all thoroughly dried out before putting in the new drywall.

My 0.02...

Let us know how it worked out, too! And even better, post photos!


- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.