Replies

1. 
   Jon_R | May 20, 2021 04:18pm | #1

   With about 1.5" of closed cell spray foam and lots of EPS, it will perform well. And be able to dry inward somewhat. And satisfy IRC 806.5.4. But only above-sheathing rigid foam (no spray foam) would be even better.

1. 
   jason_v | May 20, 2021 04:23pm | #2

   thank you

2. Expert Member
   BILL WICHERS | May 20, 2021 09:08pm | #3

   You do end up with limited drying in an assembly like this, but it's done all the time anyway and works pretty well. I have a similar installation in my own home with some 6+ inches of closed cell spray foam on the underside of the sheathing and rolled roof (like a huge one-piece shingle) on the top. No real drying in either direction. My advice would be to maintain your roof properly to avoid potential future issues, but aside from that, you should be fine.

   Bill

1. 
   jason_v | May 21, 2021 04:10pm | #5

   thank you

3. 
   user-6184358 | May 20, 2021 10:33pm | #4

   Not on topic but - The truss looks incorrect. It should have a factory vertical element at the bearing point double top plate.

1. 
   jason_v | May 21, 2021 04:11pm | #6

   Thank you i will enquire with the designer.