I need some "sound" advice

[shaneoneill]

Okay. I have a general purpose combination media/sports room on the second floor of my house, which is being built as I write this. The two sections of the room are "separated" by a step down from the sports/bar area to the theater area. The total size is 40' long by 25' wide (in most places).

I have 2x4 staggered wall construction along the inner wall shared with the "private space" of the second floor, e.g. two bedrooms. The entire space is insulated as well.

I am having the builder put double 1/2" drywall on ALL walls and ceilings in this room. In between layers of drywall will be GREEN GLUE.

My question is this: I have two options for the floor. 1) Put green glue down on the subfloor and put another 1/2" subfloor on top or 2) Have the ceilings of the rooms on the first floor below the theater/sports areas double drywalled with green glue.

Can you all provide some suggestions? Any comments here?

Regards
Shane O'Neill

[aud19]

I'd say the floor. I'd think stopping the soundwaves sooner would be better. You should be able to get "most" of the sound with the floor I'd mix width's too if you can say 1/2" and 5/8" or 3/4" subfloor) and then whatever's left will have to still go through insulation and drywall. The earlier you can stop the sound, the better

[Markmm]

Is two dry wall layers better than using drywall + a layer of partical board? Thought I read on here somewhere that partical or rather large chip board should be used. Just curious, planning my room.

[aud19]

Drywall's denser and has more mass so it should perform better though OSB would tackle different frequencies. Which reminds me, use as dense of material as available for the subfloor no matter what the thickness Shane

[shaneoneill]

Awesome - thanks for the help jason and others. Builder said to be careful not to go all the way to 3/4" because I could get into buckling or sway effect (he used another term, but not sure what it was when you get lots of weight..although this room is engineered for strength, he said too much may cause cushy type feeling) Anyhow, would green glue be applied just like on walls for the subfloor?

Thanks for the help fellas

[aud19]

Well if he uses screws instead of nails in conjunction with the green glue I don't see how it would buckle or cup.... but anyhow.... Still if you and he feel more comfortable using 1/2" and 5/8" that's fine but I still recommend two different thicknesses :T

I assume you'd apply it in the same method but probably best to check with the manufacturers install instructions

[Chris D]

Hi, Shane, it looks like you've thought of most of the biggest things. Dennis Erskine designed my theater that I've been building and featuring in Home Theater Builder Magazine. He specified that my two layers of drywall are 1/2" and 5/8". I've heard people say that using two different thicknesses will cut down on the two resonating together at the same frequency.

As for the floor, ceiling, I would do both, especially if it's above a regularly occupied living space where other people will commonly be. Double-drywall the ceiling below. What's that going to cost you, maybe $100 and 1/2" of headroom? No brainer. As for the floor, I did a floating floor, where on the subfloor, I put down a layer of rubber matting called Acoustik Mat. Then on top of that, I put down another plywood subfloor layer, not coupling them together at all with nails or anything. Just glue.

[RobP]

Shane, I wouldnt worry about the drywall cupping on multiple layers like that, if it installed correctly it will be fine. Hell, in alot of the movie theatres the layers can be up to five panels thick and I have never seen a problem there.

Also, make sure that they alternate the panels, if the first layer goes side to side, then the second layer of panels should go up and down.

[LikeCoiledSteel]

Hi Shane,
While you are still building, I second the recommendation of 2 different thicknesses of shettrock. Use 1/2" and 5/8". You should also use resilient channels. These are inexpensive metal channels that decouple the wall from the frame. Also check out mass loded vinyl sandwiched in between the rock. Staggered studs are a great start.

Check out www.soundproofing.org for more ideas. I soundproofed a condo I had and used all the above methods for good success. Remeber to caulk every gap and crevice. Sound is like poison gas that will get in at any hole. A floating floor will help also. Good luck.
Steel

[aud19]

Hi Shane,
Also check out mass loded vinyl sandwiched in between the rock. Staggered studs are a great start.

Green Glue performs the same function, if not better as the vinyl

[Chris D]

Yes, I put Acoustiblok in the walls, woven between the staggered studs. It's a VERY heavy vinyl/rubber sheet.

Be careful with resilient channel. If it's not installed properly, it'll make things worse, not better.

[aud19]

I've heard some experts say to simply avoid RC because of that Chris and that spending time/money elswhere will give you as good or better results

[Chris D]

Yup, that's why I chose not to use it. Spent my time and effort on other things to accomplish soundproofing.

[shaneoneill]

Great everyone, thanks a lot. It's being built this week and I'll be sure to report back in on the final specs. I have taken a lot of these recommendations into play here.

Thanks!
Shane

[David Meek]

Shane, one other item to consider is the sizing on your joists. If the builder is using 2x12 wood, equivalent PSLs (parallel strand laminate) or equivalent trusses/I-beams you can go with multiple layers on the floor AND ceiling sides without worry. But, if the builder is using smaller joists (sometimes allowed by local codes :nonod: ) then make sure you are well within the load limits of the joists for the layers you are adding.

FWIW, I'm not aware of ANY codes allowing a 25' joist span with anything less than 2x12s.

[shaneoneill]

I'm okay on the joists, my builder used 2x16s! (We have a fairly large home and it's custom). Thanks again all. I'm in the house now and ready to post some pics as soon as the media room/bar area is done. I think you all may like it

Shane