Hello, I have an unvented roof assembly in northeast Iowa (zone 6) trying to figure the best way to insulate and air seal. Roof is sheathed with zip board and seams tape standing seam metal roof with vented ridge. I know the roof isn’t vented but hey I figured some heat can escape from the ribs out the ridge. Interior has an 18” mono truss with 6” of 1.5 pound spray foam. Vapor barrier after 4” and an r of 30. So I have around 12” left to fill up on in my truss. Would doing a flash and batt system be ok? Installing a 12” fibersss batt under the 6” of 1.5 pound spray foam and then installing intello smart vapor barrier? Any thoughts would be greatly appreciate! Thanks a lot!