How about concreteboard for room treatment

[MikeSp]

I was wondering if some kind of 1/4-1/2 inch concrete board (Hardibacker or other brand) such as used in bathrooms under floor or wall tile, could be used effectively under the drywall on the ceiling and walls as a means to keep sound in?

MikeSp

 

[jaxvon]

I was wondering if some kind of 1/4-1/2 inch concrete board (Hardibacker or other brand) such as used in bathrooms under floor or wall tile, could be used effectively under the drywall on the ceiling and walls as a means to keep sound in?

MikeSp

I'm not sure about that, but in addition to thick material you should use some thick mineral wool and go for the room within a room design. Some of the largest benefits are reaped by mechanically isolating the listening room from the surrounding walls.

 

[audiofox]

Offset wall studs would be much more effective than Wonderboard or any other material-as jaxvon pointed out, mechanical isolation is the most effective way of decoupling sound energy in our out of a room. Don't forget the doors!

 

[Alex2507]

I did some work for a guy a few years back who was building a recording studio. According to him different thicknesses of drywall block different frequencies. So using 1/2" and 5/8" together would block a wider range of frequencies than 2 layers of 5/8".

Using a product called resiliant channel helps to de-couple the layers. It also is somewhat flexible or mobile allowing it to absorb low frequencies somewhat rather than just transmitting them.

If it was me I would hang & tape the 5/8 first. Then install the resilliant channel horizontally 2' on center. Lastly the 1/2" would get hung and taped.
Notice that concrete board isn't mentioned here. Everything the other fellows said sounded right also. If you go with the double wall (1 5/8" metal studs would be my choice on account of size alone) you could frame the walls with 2' on center studs. Stagger the stud placement on the second wall and then weave fiberglass insulation inbetween the studs. That's how cicuit city use to do it anyway.

I hope that helps.

 

[Scott R. Foster]

You can probably add more mass per $ using drywall versus that cement board.... and highly massive walls are highly isolative.. even if they aren't decoupled.

But when you add a large air gap full of absorbent [pink fluffy will do], and mechanical decoupling between the two sides of the wall, and high mass [several layers of drywall on each side], you really got something.

 

[Alex2507]

You can probably add more mass per $ using drywall versus that cement board.... and highly massive walls are highly isolative.. even if they aren't decoupled.

But when you add a large air gap full of absorbent [pink fluffy will do], and mechanical decoupling between the two sides of the wall, and high mass [several layers of drywall on each side], you really got something.

Would decoupling the drywall layers with resiliant channel on the inside of the room take away some of the problems associated with bass? Like transferance and reflection? Resiliant channel is cheap, easy to install and has always been well reguarded for sound issues. An idea for a really massive wall section is shaft wall assembly aka core board. Very cool stuff and it doesn't tie up a bunch of space. It would add to the varied material thicknesses due to it's 1" thick core board.

 

[Scott R. Foster]

Would decoupling the drywall layers with resiliant channel on the inside of the room take away some of the problems associated with bass? Like transferance and reflection? Resiliant channel is cheap, easy to install and has always been well reguarded for sound issues. An idea for a really massive wall section is shaft wall assembly aka core board. Very cool stuff and it doesn't tie up a bunch of space. It would add to the varied material thicknesses due to it's 1" thick core board.

That's an interesting question Alex.

I believe the answer is that the absorptive qualities of the wall system will be different.. but not necessarily better. The bottom line is that you are shifting around the resonance peak of the wall system not accomplishing broadband absorption. Here's an ineresting article on a series of experiments that explore related concepts.

http://www.greengluecompany.com/soundAbsorption.php

I suggest that if you design your walls to meet your structural and transmission loss needs and design your interior acoustic treatments to meet your absorption /diffusion needs - you'll get better results for less work/money.

Also, getting RC and the overlying panels installed properly is not trivial - many an RC wall was in the end a waste of time because someone ran long screws through the RC into the stud below or hung the channel wrong.

 

[bpape]

Agreed. In addition, the RC is highly unpredictable in terms of what it will do to the absorbtion inside the room. RSIC-1 and hat channel is much more predictable and IMO a much better solution.

Doing a wall with RSIC and hat, double drywall, and GG, that's about as good as you're going to get in terms of broadband isolation.

Bryan

 

[Alex2507]

What is RSIC?

I have to agree that if you use RC in all the wrong ways your results are not going to be so hot. Same thing applies to packing parachutes.

I'm going to need a lot of time and maybe a degree in something to get through Green Glue's test data. I did notice that they started selling their product in 2004. That would explain why I've never heard of it. USG is probably crying over lost market shares.

 

[bpape]

http://www.pac-intl.com/rsic.htm

Bryan

 

[Alex2507]

http://www.pac-intl.com/rsic.htm

Bryan

Cool product but IMO you could use that space to just builb a completely seperate wall out of metal studs and fill the cavities with 1 1/2" mineral wool. RC is only 1/2" thick. It's absorbtive properties were called unpredictable but not absorbing low frequency is predictably bad. Bass traps are a tough sell on the wife and DIY bass traps are a PITA. The way I see it RC is an easy, cheap,space conserving, effective and insulation free DIY bass trap. And the wife won't even know it's there.

 

[bpape]

Your call.

Yes - it's going to absorb some bass, the question is where and how much. It's totally dependent on exactly how you construct everything else and as was stated earlier, it's WAY too easy to short out. Don't take my word for it. Ask respected room desingers like Terry Montlick and Dennis Erskine. Neither of them recommend using RC in any audio related room.

As for the space, yes, it takes a little. But, not nearly as much as a separate wall structure and the extra space is part of what makes it more effective by dropping the resonant frequency of the cavity.

Lastly, the RSIC system will also provide some absorbtion in the bottom end. Now, if you want a poor mans way to replicate a % of this performance, you can just use slatting perpendicular to the stud faces and mount the drywall to that. I'd recommend this over the RC. At least I know in advance what it's going to do.

Good luck.

Bryan

 

[dhark]

Would decoupling the drywall layers with resiliant channel on the inside of the room take away some of the problems associated with bass? Like transferance and reflection? Resiliant channel is cheap, easy to install and has always been well reguarded for sound issues. An idea for a really massive wall section is shaft wall assembly aka core board. Very cool stuff and it doesn't tie up a bunch of space. It would add to the varied material thicknesses due to it's 1" thick core board.

I am surprised you know what Core board is I am a union carpenter, really a union drywaller and use this stuff regularly. Yes the 1 inch thick board would help but it is still a single wall assembly and would transfer sound to the other side via the studs, unlike 2 seperate wall systems staggered and insulated. The 1 layer taped and then resilant channel and another layer I think would be superior. You can also get sound caulking for the floor, I would put it under the floorplate or metal track and again run a bead under each layer of drywall, and it might even be a good idea to caulk all the joints on the first layer instead of taping. I am sure the caulk is more soundproof tham mud.

 

[Alex2507]

As for the space, yes, it takes a little. But, not nearly as much as a separate wall structure and the extra space is part of what makes it more effective by dropping the resonant frequency of the cavity.



Bryan

One of my points was that the space it takes up is exactly the same as a separate wall structure of 1 5/8" metal studs.

Shorting out a drywall installation on RC is kind of like running a screw into a copper water line. It can be done easily enough. I have personally done it. More than once but that's what happens when you have your head up your a$$.

The point of the thread is that wonder board is not the way to go and we all seem to agree on that.

 

[Scott R. Foster]

Shorting out a drywall installation on RC is kind of like running a screw into a copper water line.

or hang the RC upside down...

LOL

If you want something done right...

But seriously, the RSIC clips are very efficient [just add clips versus a complete new wall frame- and can yield a lower resonsnace frequency than a new frame] thus they are a viable option. But then so is RC. RC is used to build millions of feet of high transmission loss walls in theaters and hotels, etcetera every year. When installed correctly its performance is well understood [backed up with test data] and functional.

Its all good if you know what you are trying to achieve, pick the right design, and install it right. Like you say the only real point here is we agree that drywall is propbably cheaper per unit mass than other choices, and there are lots of ways to frame /stuff high TL wall.

 

[Alex2507]

or hang the RC upside down...

LOL

Uh oh.....You can hang it upside down? .........I really hope that the connecting edge goes at the top......

They hire me from the neck down.

 

[Alex2507]

I am surprised you know what Core board is I am a union carpenter, really a union drywaller and use this stuff regularly. Yes the 1 inch thick board would help but it is still a single wall assembly and would transfer sound to the other side via the studs, unlike 2 seperate wall systems staggered and insulated. The 1 layer taped and then resilant channel and another layer I think would be superior. You can also get sound caulking for the floor, I would put it under the floorplate or metal track and again run a bead under each layer of drywall, and it might even be a good idea to caulk all the joints on the first layer instead of taping. I am sure the caulk is more soundproof tham mud.

Post #4 describes what I would do. If a massive wall section was the oject the core board would be the heavy hitter but not my personal recommendation unless space was of no consequence but when does that ever happen? That is why post #4 refers to using 1 5/8" metal stud. I too hang and bang for the Union.

 

[Vanhoecke]

Alex,
In post #4 I think you meant that you would put the RC under both layers of drywall. Otherwise wouldn't you potentially get a triple leaf affect by having drywall, RC, drywall >> insulation>> and drywall (on the other side of the wall)? Maybe I'm missing something?

 

[Alex2507]

Alex,
In post #4 I think you meant that you would put the RC under both layers of drywall. Otherwise wouldn't you potentially get a triple leaf affect by having drywall, RC, drywall >> insulation>> and drywall (on the other side of the wall)? Maybe I'm missing something?

You aren't missing anything. That triple leaf term threw me but I read what I wrote and I agree with myself. I can't back this up with #'s and designers nor can I explain why worth beans. I can say that I've done it this way to meet some incredible sound proofing dilema's once for a CC and once for a guy building a recording studio.

I want to stress that on the inside of the room the 1/2" layer gets installed last. I'm going to do stuff to my condo so I read up on some sound proof paint and carpet. Since I don't do paint and carpet for a living and don't feel I know much about it, I don't run around talking much about it.

I thought I ran into one of your threads on this room. I had the impression that you're not some kid monkeying around in his parents basement. Take it to an architect. You need a building permit and an electical inspection any way.

 

[bpape]

I missed post 4 completely. Not to be difficult but you defnintely do not want to do it this way if there is drywall on the other side of that stud wall. While the triple leaf as you described can help at some frequencies, it will absolutely, positively, every time make noise transmission worse at other frequencies - usually in the bass.

Bryan