Wall construction in new room?

[Droff]

I'm building (actually finishing an upstairs room) theater room, and it won't be dedicated to HT only. I was planning on drywall as the wall and ceiling material but read somewhere, Crutchfield I think, that drywall absorbs a lot of sound leaving the bass weak among other things. The recommendation was to install plywood and then the drywall over that.
How concerned should I be with this and is it worth the extra money to install the plywood and the drywall? Can OSB be used instead of plywood?
Thanks

 

[mtrycrafts]

I'm building (actually finishing an upstairs room) theater room, and it won't be dedicated to HT only. I was planning on drywall as the wall and ceiling material but read somewhere, Crutchfield I think, that drywall absorbs a lot of sound leaving the bass weak among other things. The recommendation was to install plywood and then the drywall over that.
How concerned should I be with this and is it worth the extra money to install the plywood and the drywall? Can OSB be used instead of plywood?
Thanks

What other purpose will that room serve besides HT?
Is that room isolated from the rest of the house so that bass at very high level will not pass throughout the house. Or, you will just not play it that loud?

I bet you can find a sub that will play in there plenty loud for you even with sheet rock, but, I'd recommend 5/8" X type anyhow.

 

[Scott R. Foster]

Drywall on studs
63 125 250 500 1k 2k 4k 8k / Category / Material

0.30 0.30 0.12 0.08 0.06 0.06 0.05 0.05 Ceiling \ Wall - Plasterboard on frame, 13 mm boards, 100 mm cavity filled with mineral wool
0.15 0.15 0.10 0.06 0.04 0.04 0.05 0.05 Ceiling \ Wall - Plasterboard double 13mm on steel frame, 50 mm mineral wool in cavity, surface painted

I suggest you might want to vary the wall profile by beefing it up - but not to dminiish the low frequency absorption curve. The absorption curve for an insulated drywall partition is probably beneficial for most small room applications being weighted as it is in LF's. The typical reasons for beefing it up are greater transmission loss [less noise in - less noise out], typically done by adding more layers of drywall, decoupling devices [such as resilient channel], or a constrained damping layer like GreenGlue or folks sometimes add elements to wall profiles striving for a stouter wall system in order to resist rattling at even very high sound levels - very low in the band.

 

[Droff]

mtry -
The room is an upstairs bonus room, roughly 26'Lx14'W with stairs at about the 20' mark. It'll be a video game room, a TV room, whatever else we decide to do in there, but it won't be just an HT room, but we will be watching movies in there and I want it to be a good experience. I'm not real concerned with there being too much noise going throughout the house, I just want to make sure I have a good sound when I want it, loud not being the only criteria.

Scott -
I'm lost on what you posted.

 

[Vanhoecke]

Droff,

If you are talking about a bonus room that is in the attic above your bedrooms, you might want to reconsider your willingness to accept noise throughput the house. You will get a significant amount of sound being transmitted to the lower levels -- especially the level just below the room.

Most folks break their discussion of sound treatment done into two categories -- sound isolation (i.e., sound entering or leaving the room) and Acoustics (e.g., improving the quality of the sound inside the room by addressing the issue of sound reflection). Scott was suggesting that you would get better sound isolation if you use double dry wall with a damping material like GreenGlue. You should check out the GreenGlue site it is loaded with information (www.greenglue.org). The incremental cost of double dry wall and GG is worth it. It will cost you much more to fix the noise problem later.

Also, if I'm correct and your bonus room is upstairs over the bedrooms, you should really consider isolating the floor. This will not only reduce the low frequence (i.e., bass) noise that will transmit down into the bedrooms it will also reduce the noise from foot traffic upstairs. I have four kids and I can tell your from personal experince they will create a lot of noise while playing their video games. This will be the last thing that you want to hear on Saturday morning when you and the wife are trying to sleep in.

Regarding the sound quality in the room. This is contolled by using different types of acoustical panels that absorb or diffuse the sound. These are installed at different locations in the room depending on they desired sound treatment. There are several good articles and posts on this site that discuss various ways to accustically treat a room, you should look at those postings and articles. I have not heard of anyone recommending the installation of sheetrook over plywood as a means of improving the accustical sound quality in the room.

Save you money on the plywood and do the double drywall with GG instead. After the room is constructed you can buy (or make) a few accustical panels that will hang on the walls which will improve the room accoustics. These panels are not expensive -- especially if you make them yourself. The big issue is the proper placement of the panels.

Good Luck

 

[mtrycrafts]

mtry -
The room is an upstairs bonus room, roughly 26'Lx14'W with stairs at about the 20' mark. It'll be a video game room, a TV room, whatever else we decide to do in there, but it won't be just an HT room, but we will be watching movies in there and I want it to be a good experience. I'm not real concerned with there being too much noise going throughout the house, I just want to make sure I have a good sound when I want it, loud not being the only criteria.

For that purpose, you will be fine with 5/8" rock. As also mentioned, if this room is above bedrooms, you would have to watch the sub volume is someone wants to sleep. If it is over a garage, not an issue.

 

[mgripy]

reply

See if you can find some QUITROCK.
Replacement for sheetrock, perfect for HT rooms.

 

[no. 5]

Originally Posted by Scott R. Foster
Drywall on studs
63 125 250 500 1k 2k 4k 8k / Category / Material

0.30 0.30 0.12 0.08 0.06 0.06 0.05 0.05 Ceiling \ Wall - Plasterboard on frame, 13 mm boards, 100 mm cavity filled with mineral wool
0.15 0.15 0.10 0.06 0.04 0.04 0.05 0.05 Ceiling \ Wall - Plasterboard double 13mm on steel frame, 50 mm mineral wool in cavity, surface painted

Scott -
I'm lost on what you posted.

it looks to me like he posted the sound absorption coefficients of two construction methods.

 

[Scott R. Foster]

it looks to me like he posted the sound absorption coefficients of two construction methods.

sorry for the confusion... what 5 said is a correct translation.

Also, you might want a better isolation wall to keep noise from leaking in/out, and some folks want tighter walls because they fear rattles at high sound levels.. but forget about plywood, whatever you are trying to do with the wall there are better/cheaper ways to do it.

and... don't worry about drywall sucking up all the lows... any wall system you are likely to build will leave enough room low frequency resonances to cause you to want more absorptive treatment for HT useage - not less.