Rigid Foam on Roof with Added Overhangs
I apologize in advance for the drawing I’m going to attach to the bottom of the email. But as my initial house plans (zone 3 California’s High Desert) near completion, we’ve set our attention on the details regarding air sealing and insulation.
I remember watching Matt Risinger build a roof with a layer of external insulation on top of the WRB and there was a system of rafter tails outside the sealed sheathing that were notched to fit over what he called “monopoly framing.” That meant the house was built without overhangs…or rafters piercing the outside wall.
I have a feeling there are details for this somewhere on the site, but I can’t find them. So in trying to explain the concept to the structural engineers, I made this rough drawing. They said that forces of uplift on the false rafters would stress the narrower tails that were fastened through the roof deck, so this wasn’t actually a viable plan.
I know I’m not breaking new ground here…so that means that I’ve done something wrong in my drawing. It’s taken me 60 years, but I finally “know” when I “don’t know” something. Can anyone look at this drawing and see if there’s some fundamental aspect of the detail that I’ve left out?
thanks so much…I really appreciate the time you guys spend helping inform amateurs like myself.
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