exposed ceiling joists

i plan on leaving my ceiling joists exposed and filling the area in between with a combo of sheetrock and fiberglass as listed in the drawing below: this drawing is based on this thread: http://www.johnlsayers.com/phpBB2/viewt ... osed+joist i would prefer to leave a 6" gap between the bottom of the joist and 705 insulation. the ceiling is on the low side [9 ft to the top of the subfloor above] and the more space i can get above the better. noise leaking into the upstairs is a concern but not that huge of a deal, my parents are pretty cool with the noise issues [this studio is in my basement of my parents home] and there bedroom is 2 floors up from the basement. as of now they can barely hear anything when in there bedroom and all there is now is some 3 1/2" insulation between the joists and a standard drop ceiling with 1" fiberglass tiles. any potential problems with this type of ceiling?

That should work fine for what you want - if you're at all concerned with leakage, maybe a second layer of wallboard added to the first one. You may find (depending on what you're doing, and where in the room) that leaving that much of the joists exposed will cause excess diffusion and a slightly smeared stereo image - if so, you might put another layer of 705 just over the mix area, suspended just under the joists - I'd try it without, then if you're not happy with the sound experiment with the "cloud" ... Steve

does the area inbetween the joists that is parallel to the floor have to be a soft surface like 705? can it be sheetrock or plywood? or that would cause too many problems with reflection off the floor?

Sheetrock or plywood are hard reflective surfaces whereas the 705 is an absorptive surface. The intent of the 705 is to reduce/eliminate the reflection you will get off your floor. Bryan Giles