2 inch XPS rigid insulation in garage
At the moment, I’ve got a 20′ x 24′ attached garage that shares the rear wall and ceiling with conditioned space. The rear wall is 4′ anove slab elevation, sharing a wall woth the crawlspace. I’m sealing that part later, currently fixing bulk water issues.
The garage and house are made of 2 x 4 framing with vinyl siding, thermoply and R-13 Kraft paper fiberglass batts. I have 96 sheets of 2″ XPS that I got for free. The garage has no drywall, just exposed fiberglass. I used the garage a lot as a shop and just keep the garage door closed with the living space door open. The A/C unit is a 4 ton unit for the whole 2200 SF living space, I think it’s oversized. The garage door is one of the most tight and insulated I’ve seen and the garage holds temp pretty well. If I attached the 2″ XPS over the studs on the inside (Kraft paper faces inward) and air seal th seams, could I have later moisture issues? Any other forseen issues? I know I could use this for the siding when replaced or roof, but they’re both pretty new, having been replaced by the previous owner in the past 2 years.
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