Do I need to use R10 minimum on the roof deck in climate zone 4C in all cases?
I am detailing a low slope unvented roof. I will be using spray foam & then batt insulation to total R38 under the roof deck in Climate zone 4C. I could meet code just with that but would like to use rigid EPS board, R6, on top of the roof deck to prevent thermal bridging. This introduces a third insulation that is not covered in the code
– Do I need to use R10 to meet the minimum above deck value? Does this rule still apply since I’m using spray foam directly below the deck?