Originally posted by Dave Petrina:
I've asked this before but didn't get any response so I'll try again.
Has anyone designed/constructed a roof using rigid polyurethane foam insulation (not SIPs) applied directly over the T&G?
I'm interested in some of the details (ie: ridge, faschia, strapping for roof material).
I have done just what you described. Our layers were as follows (top to bottom):
-Shingles.
-#15 felt paper.
-1/2" plywood sheathing.
-2x4 strapping (flat) 16" OC.
-3 layers of 1-1/2" Firestone PolyISO polyurethane foam (staggered joints).
-1 layer of Ice & Water Shield directly on top of the pine t&g for our vapour barrier.
The 2x4 strapping was secured to the timbers with 10" screws (to sandwich the foam in place).
This proved to be an easy (and inexpensive) way to close in and insulate the roof system.
