Our basement wall system is made of 9' high insulated precast concrete. Superior Walls manufactured and installed the system. It is their "Xi" wall with 2 1/2" of closed cell polystyrene insulation (Dow Styrofoam) = R12.5. Our builder installed (stuffed) faced 3 1/2" fiberglass batts (R11) in the remaining 6" deep cavities between the wall's metal studs.
We would like to now finish the walls by covering with 1/2" drywall. Will this work without causing condensation problems. The polystyrene should provide a vapor barrier and is more than 50% of the total R-value. Should the facing be removed from the batts prior to covering them?
I am aware that a more preferred (and more costly) method would be to install additional spray foam insulation, but I would like to minimize additional costs if at all feasible.
We live in the southern tier section of western New York state and at about 1400'elevation the winters do get cold. We have hot water radiant in-floor heating in the concrete floor and use a wood burning stove for supplemental heat. The basement is kept at 68 degrees minimum in the winter.
Thank you. Gary