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Second Floor Theater

post #1 of 66
4/1/11 at 12:18pm
Thread Starter 
Hello,
I am curious what guys who are building theaters on the second floor are doing with their sub floor. My second floor "bonus" room is actually ~950ft/sq with 15'x20.5'x9 of it, the theater area. The area is stud only with the "exterior" walls sheeted into the attic area. The walls are obviously sitting on the sub-floor, which is 1 1/8" Advantech. Sound transmits quite easily to the bottom floor at this point. Oh, the cavity is insulation filled, however, i know this does basically nothing. Removing the sub-floor is not an option. Will using Green Glue between another layer of 3/4" sub-floor (or two?) going to do a nice job? I am thinking of Whisper Clips on the walls and ceilings to help isolate the existing walls from the hard attachment to the existing floor.
Any thoughts would be great
Thanks
Eric
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post #2 of 66
4/2/11 at 5:38am
Doing another layer of subfloor (or two) will help because of adding mass. Doing GG between will also help. Adding padding and carpet will also help. If you, caulking the seams on each layer of the subfloor (and I think the drywall) with acoustic caulk will also help.

Not being able to decouple the floor will lessen how much those steps will help. The real question is how important is the isolation? If it is critical, to the point that every decibel matters - taking those steps you suggested are a no-brainer.

If bang for the buck is more important, not being able to get into the subfloor will reduce your results - and isolation is generally only as good as your weakest link. On this subject however, anything you can do will be an improvement. If that improvement turns out to be fewer decibels than you are looking for, you will still be closer to what you want than not doing that.

The question is how tight of a budget is it, and how does that compare to the reasons for wanting sound isolation?
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post #3 of 66
4/2/11 at 8:45am
Quote:
Originally Posted by Edge540 View Post

The walls are obviously sitting on the sub-floor, which is 1 1/8" Advantech. Sound transmits quite easily to the bottom floor at this point. Oh, the cavity is insulation filled, however, i know this does basically nothing. Removing the sub-floor is not an option. Will using Green Glue between another layer of 3/4" sub-floor (or two?) going to do a nice job? I am thinking of Whisper Clips on the walls and ceilings to help isolate the existing walls from the hard attachment to the existing floor.

That would be a good plan. Others like a heavy rubber compressible layer on top of the original subfloor, then double plywood (damped) floating on top. Screws cinch the ply together to compress the damping material. Screws don't penetrate the rubber layer.
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post #4 of 66
4/2/11 at 3:11pm
Thread Starter 
i think this is the plan. use http://http://www.lowes.com/pd_15383-33-A11240848096_0__?productId=3327496&Ntt=15383&pl=1&currentURL=%2Fpl__0__s%3FNtt%3D15383 under two 23/32" OSB plys which have GG between and screwed together. Screws will not penetrate the bottom OSB. Not so sure about the asphalt part of it though. i dont know if it has an odor.
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post #5 of 66
4/2/11 at 3:23pm
That would help but no real mass contribution.
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post #6 of 66
4/6/11 at 8:54am
Thread Starter 
I have attached a CADD drawing of my room for critique and sanity check. Room dimensions are to the inside of double 5/8" drywall w/ Green Glue mounted to V-Clips. The entrance door is not set in stone however my wife asked for it to be towards the rear of the room. Note that i would like to keep room orientation as is because the front and left side theater walls are unfinished attic space on the other side. I am waffling as to useing IB subs on the front wall.
any comments would be appreciated.
thanks
eric

 

floor_2.pdf 17.341796875k . file
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post #7 of 66
4/6/11 at 12:45pm
There are other 1-piece clips you might look at instead. Figure on clip + channel = 1 3/8" from stud
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post #8 of 66
4/6/11 at 12:55pm
Quote:
Originally Posted by Edge540 View Post

Hello,
I am curious what guys who are building theaters on the second floor are doing with their sub floor. My second floor "bonus" room is actually ~950ft/sq with 15'x20.5'x9 of it, the theater area. The area is stud only with the "exterior" walls sheeted into the attic area. The walls are obviously sitting on the sub-floor, which is 1 1/8" Advantech. Sound transmits quite easily to the bottom floor at this point. Oh, the cavity is insulation filled, however, i know this does basically nothing. Removing the sub-floor is not an option. Will using Green Glue between another layer of 3/4" sub-floor (or two?) going to do a nice job? I am thinking of Whisper Clips on the walls and ceilings to help isolate the existing walls from the hard attachment to the existing floor.
Any thoughts would be great
Thanks
Eric

Are you especially concerned about the low frequency noise down into the room below?

If so, then installing the clips and panel over the existing surfaces will actually cause a decrease in performance at the low frequencies unless you add quite a bit of mass over the clips.

What you can do to "fix" this is to punch holes in the existing drywall, then install the clips and panels.

I actually did this in a lab and we got large improvements in the low frequencies, over just installing the boards on the clips attached to existing drywall.
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post #9 of 66
4/6/11 at 1:12pm
Thread Starter 
Sorry for any confusion. This space is actually a portion of a completely unfinished 2nd floor. I had the carpenter install and sheet the exterior walls of the upstairs when the house was built a year ago. The interior of all the walls is stud only. I will take a photo this evening and post so it makes more sense.
thanks
eric
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post #10 of 66
4/6/11 at 1:14pm
Thanks Eric. That's what I understood
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post #11 of 66
4/6/11 at 1:20pm
Thread Starter 
Quote:
Originally Posted by Ted White View Post

There are other 1-piece clips you might look at instead. Figure on clip + channel = 1 3/8" from stud

Ted
I had picked the V-Clip over the Whisper Clip because it was 1/2" lower in profile and budget purposes. If the Whisper Clip is vastly better than V-Clip, i could sacrifice loosing another inch in room width/length and the extra dollars, about twice the money i think.
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post #12 of 66
4/6/11 at 1:23pm
The WhisperClip is an example of a two-piece clip. The V-clip is an example of a 1-piece clip. My point was that there are better performing, lower cost 1-piece clips. This clip I'm referring to is 1 3/8" from the stud after assembly with a 7/8" drywall Furring Channel. So it's not 1 5/8, rather it's 1 3/8"
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post #13 of 66
4/6/11 at 5:26pm
Thread Starter 
this is a photo of what will be the sceen wall. The short sloped ceiling section will be behind the screen wall.


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post #14 of 66
4/7/11 at 7:06am
As I mentioned the best approach is to decouple the walls and ceiling. Can be done with framing, clip&channel, or both.

For the floor you can either laminate more subfloor with damping compound, or add a massive rubber isolation mat to the floor and then double sheets of ply with damping compound. Dennis might have a comment on that, as he specs this in above grade room construction.

Plan the route of the sound controlled ventilation.

Plan for outlet seals, ceiling can lighting, and of course the doors.

Install insulation per local code. No foam, just standard fiberglass.
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post #15 of 66
4/7/11 at 7:19am
Quote:
Originally Posted by Ted White View Post

The WhisperClip is an example of a two-piece clip. The V-clip is an example of a 1-piece clip. My point was that there are better performing, lower cost 1-piece clips. This clip I'm referring to is 1 3/8" from the stud after assembly with a 7/8" drywall Furring Channel. So it's not 1 5/8, rather it's 1 3/8"

Are either UL listed? The old DC01 and DC04 have been UL tested and are good in the case of a fire.
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post #16 of 66
4/7/11 at 7:26am
The UL listing isn't required for this construction, but no, they are not. The WhisperClips are actually significantly over-engineered relative to the UL fire-rated clips:

The steel used is 10% thicker
The amount of steel holding the channel is 20% greater
The steel is annealed high carbon spring steel, post-stamp hardened. Much stronger and much more resistant to fatigue.

Despite all of this, it's still the Drywall Furring Channel that is the weak link in the entire process.
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post #17 of 66
4/7/11 at 7:44am
Thread Starter 
"Install insulation per local code. No foam, just standard fiberglass."

The rest of the house is and upstairs will be blown cellulose. Is this material suitable or too "coupling"? It, of course, will not touch the drywall which will be on clips. What about the ceiling, as it would be blown after drywall install, so it would be laying on drywall? Possibly the solution here is bats then blown on top but i kind of envision it settling onto the ceiling drywall eventually.
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post #18 of 66
4/7/11 at 7:54am
Cellulose is a fine material. The risks are:

Over-compaction and / or pressing on the clips and channel, and thereby reducing the requisite flex.

Batt fiberglass avoids all of this. We've been involved in several over-stuffed insulation problems over the years, so it definably happens. In fact we have a big warning in our installation manuals regarding this.
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post #19 of 66
4/7/11 at 12:26pm
Thread Starter 
trying the upload of room layout to make it easier to see.
thanks

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post #20 of 66
4/7/11 at 12:28pm
A double door that creates an airlock would help a lot
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post #21 of 66
4/10/11 at 9:26am
Thread Starter 
checking again if any of the experienced folks have an opinion on my proposed theater layout. For HVAC, i am planning two registers in the soffit at the front, one left, one right. For returns i plan on one on each side at the rear.
if more info is needed, pleae let me know
thanks!
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post #22 of 66
4/11/11 at 1:18pm
Thread Starter 
This is a drawing of the complete second floor.

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post #23 of 66
10/25/11 at 7:11am
Thread Starter 
Working slowly on my theater and upstairs in general. Im contimplating using 4ea- IB318 (18") drivers for an IB sub behind the screen wall. Behind this wall is attic space. The ceilings are 9' so total room volume is ~2800 sqft. I have not heard an IB sub before so im curious if this is too much or should i go with 15" drivers instead.
thanks
eric
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post #24 of 66
10/25/11 at 7:34pm
Are you going to sound proof the IB room/chamber too? If not, then they will be heard every where.
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post #25 of 66
10/25/11 at 7:47pm
Thread Starter 
There wasnt going to be an IB chamber; just vent into attic. Maybe i should rethink using IB at all. Need to come up with something that would fit behind the screen; about 22". DIY preferable. for mains and center im planing 4pi with 1pi as surrounds.
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post #26 of 66
12/7/11 at 12:39pm
Thread Starter 
well finally there has been progress, even if just a little. Currently working on installing WhisperClip RC's with channel. walls are completed with ceiling being done tonight. Walls are all blown cellulose. Netting is between cellulose and channels so no touching over time. Ceiling will be blown also. Netting was stretched tight and stapled horizontally in each bay. This should keep the cellulose from touching the channels and OSB. Ive decided to use 5/8" OSB, GG, and 5/8" drywall. The theater will be a sealed room with electrical on the inside of the room; no holes.
With the HVAC supply and returns, i will be using Duct Board starting collars installed into the 5/8" OSB. Around the resulting hole into the room, I will build a box plenum with register. The two 8" supply and one 14" return plenums will be 7/16" OSB lined with Linacoustic. The 8" supplies are located in the frount of the theater, one on each side, exiting the bottom of the soffit. The 14" return will exit the rear of the room in the center. I will build a six foot plenum in the center with a return register on each side.
Will start posting photos once there is a little more to look at. Photos will help explain my descriptions.
thanks
eric
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post #27 of 66
12/7/11 at 4:11pm
Quote:
Originally Posted by Edge540 View Post

There wasnt going to be an IB chamber; just vent into attic. Maybe i should rethink using IB at all. Need to come up with something that would fit behind the screen; about 22". DIY preferable. for mains and center im planing 4pi with 1pi as surrounds.

I originally considered IB as well, but decided not to - mainly because of not being able to contain the back wave (mine would have been in the attic, and there was no way I was going to DD/GG the entire attic space); but also because of placement flexibility - if you find you have modal problems with a sub, you can move it, not so easy to do so with an IB.

I ended up building a pair of THT LP subs - folded horns with 15" drivers - they lay flat behind my screen wall, underneath my LCRs. I also had just about 22" to work with behind my screen wall. They don't extend as low as an IB would (I get into the high teens before it drops off), but they do a heck of a job otherwise, and don't require much to power them. Also check out the F-20, which is conceptually similar.
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post #28 of 66
12/9/11 at 5:15pm
Thread Starter 
Brad, thanks for the reply. I have ruled out the IB for the same reasons. Thanks to you, im looking into the THT LP sub. Looks like what i want; a good sub which will hide behind an AT screen. I think two of them also.
I remember reading through your thread but back when you were starting, then i lost track. Now that ive seen the finished product, ive decided my color scheme. I was originally set on red/black, but i, and my wife, really like the dark brown/black scheme. Hopefully you dont mind much if i basicly model my theater after yours. Its really nice.
Im just at the begining and hopeing to have the room drywalled by christmas.
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post #29 of 66
12/11/11 at 11:17am
Thread Starter 
This is how we are today. This is the front wall:



This is the rear wall with the return in the center:



This is how i brought all the wiring into the room:

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post #30 of 66
12/14/11 at 7:12am
Thread Starter 
i was planning on using 5/8" OSB and 5/8" draywall. I have a stack large of 1/2" drywall already upstairs which is left over. I have not ordered OSB yet but want to today.
My question, what is the opinion of using the 1/2" with GG over the 5/8" OSB, or bumping the OSB to 3/4" and still using the 1/2"? Maybe the thicker OSB is too stiff?
thanks
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