I used 2” foam insulation panels as the “first coarse” on both my walls and the ceiling, followed up with bat insulation. The foam boards are re-purposed roof insulation purchased from roofing contractors (from school buildings, offices, etc), and it’s worked out great (and for only 40 cents on the dollar roughly compared to new)! In the gaps I used spray foam, and I gotta say- that building is TIGHT! Unfortunately I ran out of warm days to finish-up filling gaps with foam, so here I am….waiting.
Picture of some of the foam boards I bought from a local roofer:
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That’s exactly what I used on my walls. With air space it is close to 12R value. Your smart doing it on warm days, I was doing it last winter with no heat out there and I was freezing my *** off















