Insulating roof framing in overhangs
With help from members here, I have built up my roof system as detailed in the attached (which doesn’t necessarily show everything in the proposed assembly). This includes 3 layers of external polyiso along with 7 1/4″ of rockwool batts between the i-joists (not shown). The roof is a shed 2:12 with 24″ overhangs.
My question is in insulating the “exposed” i-joist ends and bottom flange. There’s lots of talk and ideas on stopping the thermal break on the roof deck – i.e. the top flange of the i-joists in my assembly, but I haven’t found information on insulating the ends or the exposed bottom flange of the i-joist. My idea is to use the same Zip-R 3.6 (1″) that I’m using for my wall sheathing to wrap the exposed ends and bottom flange of the i-joists. I am wondering if I could even use this Zip-R as my sub-fascia board (which is what I am showing) or would I need an additional (and more normal) 1x dimensional material for this.
Does this seem like a good approach? Am I missing something or going overboard?
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