Roof retrofit for non-cathedral, non-low slope roof
I’ve read several items about adding exterior insulation to existing roofs but haven’t found the detail that I’m looking for.
We have just purchased what amounts to a one story ranch home with a walk-out basement in Central WI built in 1985. The basement is block except for the walk-out wall. The walls are 2×6 stud construction with fiberglass and poly. The gable roof is framed with standard (not energy heel) trusses 2′ o.c at 4/12 pitch. There is a also a small intersecting gable addition with that roof framed on top of the original gable roof.
We are going to be replacing all windows and siding, soffits etc. as well as shingles. Our intent is to use at least 2″ of foam on the exterior of the walls and something similar to interior of basement walls (there is 1″ of foam on exterior block now).
Now the question: For the roof, which is currently vented and has a few inches of cellulose blown in I’d like to go to unvented and add rooftop foam. If I do that I’d also like to extend the gable overhangs from the current 11″ and raise the soffits on the sidewalls.
Does anyone have framing details figured out for that on a roof where 8″ of foam (minimum) is going to be added?
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