Oh, for sure, because you dont need it to be flat or any of that. But from the looks of it You are only going to get about 6 inches of insulation in there.Just an idea to get more Rs. You could also insulate between rafters then glue and screw foamboard to the rafters then glue and screw your drywall to that. You will need a good vapor barrier behind your drywall. ANY condensation will accumulate and then freeze eliminating insulation and causing problems with mold and rot. Also it isnt just the change in temperature in the room when you raise the thermostat.. As the heat passes though the barrier( drywall, Insulation, plywood) it leaves behind the moisture particals that are present (in any air) that cant pass through with it. Heat goes toward cold. Then it will reach the cold and freeze.
Really even with 6" of insulation and then turning up the thermostat it will help a lot.(My disclaimer-Im not an insulation expert-just a think so-lol. Some people say dont use a vapor barrier-lol
Did your cousin use the foam? Drywall is definately cheap and makes all the difference in the world.

Last edited by JimT; Wed Feb 12 2014 07:43 AM.