Basement Joists Drywall

Before constructing freestanding ceiling attached to booth structure, I was planning to put a layer of sheetrock attached to the exisitng subfloor above booth. Not sure if I'll have the space to do this and still have acceptable ceiling height in booth. If I am unable to do this, will it afect transmission of vibration in any way att all--or is it just a matter of deadening the sound from the floor of the room above, I'm planning to use R-19 insulation between the subloor and the top of the new booth ceiling Sorry if this is kind of a lame question, but I want to do the right thing

If I understand you right, that would mean that you are creating a three-leaf wall, which is not good. Far better to put that sheetrock in between the joists of that floor above you, cut to fit and pressed up tightly against the sub-floor, sealed all around the edges with plenty of caulk, and held in place safely with good cleats. If you can get two or three layers of sheetrock in there, plus another couple of layers of sheetrock on your booth ceiling, and plenty of insulation in the air gap (fiberglass or mineral wool), then you should be fine. However, you should check if your joists can safely take the extra weight of a couple of layers of sheetrock: that's a lot of mass! (Which is the point: you WANT lots of mass up there, but you need to make sure that the joists can handle it.) But you should definitely avoid creating three leaves if you possibly can. You want two leaves, and only two. - Stuart -

That's what I meant, just wasn't clear---Not sure I'll have room for the pieces of drywall attached to subfloor, so that was the question Thanks