Axiom Home Page Forums General Discussion Home Theater Lets plan a theater space

Green Glue is actually NOT an adhesive. Them using the word "Glue" in the product name was a dumb idea to me.

Not sure that I follow the 12" centers, oh wait, I meant centres?

6" is about as much overhang that you want the drywall to have from the channel.

I used Whisper Clips and Hat Channel using this guideline:
Whisper Clips and Hat Channel

Are you planning on Resilient Channel? Most people shy away from that anymore as it isn't as good, consistent, or reliable as the clips and hat channel. The Sound Proofing Company (highly regarded people in the industry) don't like it either. Not just because they don't sell it, but because it doesn't perform as well and has too many variables over clips and hat channel.
Is resilient channel OK for sound proofing?

Personally though, if you use a quality product it should work.
http://www.youtube.com/watch?v=-IfYuNnRLgU

For screws, I actually went a little lighter on the first layer (making careful note of where the clips/joists were as to not drive a screw through the channel and into a joist (defeating the purpose of the clips and channel). I ran one layer one direction, and then the second layer (with Green Glue in the middle) the other direction. This is more for a theoretically better "structural integrity" of the wall or ceiling, although running them all the same way, but offsetting one layer a foot or two from the other seems like a good option as well with minimal acoustical differences. I used the number of screws required by code for my area for the 2nd layer (thus the fewer number on the first layer) since you *need* the screws to go into the channel anyway. The 2nd layer screws were just longer to handle the 2 layers.

It was recommended to me that the ceiling should be last. It should be allows to hang fairly independent from the walls. This made me nervous at first as the ceiling actually could move up and down a little. After the 2nd layer, things settled nicely. Sure, you are "coupling" the ceiling and side walls when you mud/tape the corners, but for some reason it was recommended to do it that way.

Acoustical caulk should go up BETWEEN the 1st and 2nd layer of drywall. Someone told me that I could put it up AFTER the 2nd layer, and dang it was hard to get mud, primer, paint, ANYTHING to stick to the caulk. You just really want to seal up the 1st layer for anything that sneaks through the 2nd layer that you put up.

I had a flat ceiling to work with. I did put in some flexible insulated ductwork for my two HVAC feeds into the room. WOW did that stop sound from coming in or out of the theater. I ran the flexible duct from the vents to about 2 feet outside of the room, and then put up some extra insulation in the ceiling cavity around the duct. Nothing special.