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Basement insulation stack

FredJP | Posted in General Questions on

Im going to finish my basement. I’m located in zone 5A. Contractor wants to install a 2.5” steel stud wall 16” OC 1” away from solid cinderblock wall. Cavities filled with r15 fiberglass batts. 

1. Should I recommend he swap the airgap for 1.5” XPS R7.5 leaving it 6” off the ground?

2. Do I need to insulate the cinderblock wall and rim joist behind an attached, unheated garage? If so, R15 continuous same as the other walls?

3. I currently have fiberglass batts insulating my rim joist. Should I replace with spray foam?

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