The example of the failed roof with the polyiso on the interior.
It appears this sandwich had fiberglass in the roof cavity?
I was thinking of using 1" poly iso on a cathederal ceiling to give a thermal break to the framing. Spraying poly iso 4" closed cell 2# foam in the rafter bay. Then adding the additional inch of sheet foil faced on the interior. With the closed cell we have never had a moisture problem occur. Our location is north eastern Pennsylvania. The roof system has ice and water shield on it. Our feeling is that the closed cell foam doesn't let any air leaks occur, keeping moisture out of the interior to exterior sandwich.
Feed back please.
Posted Aug 11, 2010 8:11 AM ET
Other Questions in Energy efficiency and durability
Minisplit setup for New Jersey, 750 sq. ft. house over crawl. Bouncing my HVAC contractor's plan off you guys.