Epdm roof with double vapor barrier
I’m in climate zone 2, hot and humid.
I have an EPDM flat roof on part of my house. The EPDM is glued directly to the plywood deck. There’s no exterior insulation under the epdm.
I now need to insulate my 2×6 rafter bays. My spray foam guy recommends using closed cell foam. He says in the winter time, interior moisture can travel through open foam and cause mold issues on the plywood by condensation, since no exterior insulation was added between plywood and epdm to keep the plywood warm enough.
While I do get his point, wouldn’t closed cell foam create a double vapor barrier since I have EPDM on the outside of the plywood? If the EPDM ever leaks, there would be no drying potential to either side, correct?
Should I got with open or closed cell foam?
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