Where should the air gap be?
The best way to think of this is: 1) The best way, 2) The second best way, and 3) The third best way. The best way: There are two air gaps of at least 1″ on both sides of the foil. The second best way: There is a 1″ air gap between the foil and the other building material (drywall, sheathing, roof, etc.). The placement of the gap will depend on where you live. If you live in a warm climate like California or Florida, the air gap should be toward the outside (i.e. between the wall insulation and the foil. There is not a major difference in performance between the first and second methods. If you’re stressing about it, don’t. The third best way: There is a 1″ air gap on the opposite side of #2. For example, you live in Florida, but you put No-Tear directly against your roof sheathing, rather than underneath your rafters.
