Flash and Batt with XPS on interior side of garage wall.
I’m replacing the mouse-compromised insulation in my 2 car under garage/workshop. I plan to get R19 garage doors. One wall is all concrete, the opposite wall is 3’6″ of concrete topped with 2×6 framing. I intend to use XPS on the interior of the concrete walls. But for the framed walls I would like to use closed cell spray foam 2″ thick, fiberglass for the remainder of the wall thickness and then 1″ of XPS on the interior. Then strapping and drywall. Is this a bad idea? My understanding is that 1″ of XPS is considered permeable and so the interior side of the closed cell foam should theoretically be able to dry to the inside.
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