foam insulation in rafters or not?????
Well i am about to have my shed roof addition spray foamed (open cell in 2×6 walls and 2×8 ceiling rafters. The discussion with my hvac and carpenter friends is weather to foam the rafters and create a “conditioned space” in the attic (20 x 20 x 3 1/2 high attic) or just foam the walls and do fiberglass in the ceiling joists. The foam contractor says he can build a “wall” over the ceiling joist to the rafters to close off the new shed dormers from the existing attic space. This leaves me with one traditionally vented attic with one gable vent and ridge vent, and a new non vented foamed rafter section. Oh, what to do, what to do? It’s a conundrum wrapped in insulation. Love the idea of using foam instead of fiberglass but I don’t want to _up the installation. We will be installing a 5/8″ drywall ceiling.
Replies
If you think you may ever want to run ductwork in the attic, it should be conditioned space. It's also a bit nicer if you plan to use can lighting in the ceiling - saves on boxing in and air infiltration issues. Otherwise, insulation between the joists is fine. That said, 7" of fiberglass may be a bit skimpy for a ceiling.
Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.