I’m looking to put heat in the shop for next winter. I’m getting bids on the heat but will insulate the attic myself. I’m not sure how to best insulate it. I live in central Illinois so R-38+ is my goal. The interesting component is my ceiling consists of garage door panels. I didn’t build the shop but we have a nearby garage door manufacturer and these panels were seconds. It’s a very clever ceiling design. It’s bright white and comes with an R8 value and each panel is airtight when locked together. The panels are 12’ long and my shop is 24’ long so there’s one gap/butt joint down the center that I will seal up with a can of spray foam. With garage doors as my base layer, do I need to worry about a vapor barrier before unrolling the batts, should I get paper backed insulation or use the unfaced insulation batts?
I’m not really interested in the hassle of renting and use loose fill unless there’s some significant advantages that I’m unaware.