I live in a studio apartment and the ceiling does not have drywall only exposed rafters. I bought TUFF Sheeting Insulation can I use that for sound proofing on the ceiling and as a form of insulation as well? And do I need to fill the space (11 1/4 deep) completely with insulation or can I take the sheeting and fasten it to the bottom of the rafters and then cover with drywall? I am looking to do this in the most inexpensive way as possible. Anyone that could offer some insight.... it would be greatly appreciated.