Seal EACH layer?

[Steven]

Ok, sorry for the newbie questions... we're putting a 5/8 / Green Glue / 5/8 dry wall sandwich right over existing drywall.

We left 1/4" gap on all seams such as meetings between walls and meeting between floor and ceiling. We put the first layer of drywall in and then caulked the seams with USG acoustic sealant. Then we green glued the second drywall layer and slapped that up. Now we are going to go around and seal it again with acoustic caulk. Does this all sound right? Oh one more thing is rather then do the stair step sandwich with the ceiling and wall layers, the ceiling is just screwed to the stuff with a 1/4 air gap all around it which we plan on just caulking. Is this bad? Will this reduce isolation?

Steven

[Aaronw]

All sounds right.

After your first layer on the walls, caulk each gap. In the corners of walls, as you put the second layer on one wall, caulk there. And when you put the second layer on the other wall, caulk it too.

Ceiling, I did the same thing as you. Installed the walls first, then did the ceiling last. Just caulk after the first and second layers. After it dries, double check for any shrinkage or where the drywall dust is on the edges, sometimes it doesn't stick well, and you'll need to touch it up.

[sharward]

Don't forget backer rod. See Dan Fitzpatrick's recent post about it.