Will furring strips be needed over sheathing if using steel roofing?
I'm Zone 5 - upstate NY, planning to build 1050 s.f. ranch home, using r-20 superior wall basement, r-33 double wall cellulose.
If i build roof using 2x10, and gusset 2x4 underneath, filling with cellulose, and if i use 1" foam board to baffle/vent roof 1-1/2" beneath sheathing, i could obtain over r-43. here are my thoughts/questions
*would it be acceptable to "create" gap of 1-2" between 2x10 and 2x4 using ply gussets to break thermal transfer between 2-piece rafter? if so, that gap could be spray foamed or kept cellulose along with rest of cavity, correct? either one better than the other? 2" gap would then become r-50+roof.
*using 1" foam board as baffle/vent, does it really matter if i use xps, eps, or foil polyiso?
* And original question.....the sheathing above vent....if i use steel roof, do i really need vertical or horizontal furring strips, or will design of steel be enough air movement?
Posted May 21, 2012 8:52 PM ET
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