I will be self-contracting my own residence. SIP walls and 1/4:12 slope roof, EPDM roofing material.

Unfortunately, when I have to explain to local builder/suppliers what a SIP is, any answer I get does not seem reliable.

So I have searched the web to find how the best approach, is but no luck yet. From my understanding, SIPs need to dry to the interior (gypsum board, no poly) and the exterior. The latter is the part I’m having trouble with. EPDM will not allow the outside OSB dry, right? Do I need to add a second roof deck over purlins, and apply the membrane on top? Any other ways to do this?

House to be built in Walla Walla, Wash. 99362

Thanks for your time,

Robert