High Performance Air Tight Build - How Do You Install Rigid Foam For Roof Insulation?

What do you do if you plan 9-inches of rigid foam roof insulation? I couldn't find any exact advice online or in magazines on how to frame this. This video details how I build an open cathedral type ceiling with taped rigid foam above it. How do you build a box around 9-inches of rigid foam? I wish I saw the recent Matt Risinger video where they air seal AROUND the overhang. I probably would of framed it different. This video goes over solution I figured out. It ends up fine in the end. Do you have a better way? Please leave a comment. I use PolyIso (Polyisocyanurate) and EPS (Expanded Polystyrene) over the roof rafters and 2x10s you see on the inside ceiling. I encapsulate the building in Huber Zip System 1/2-inch sheathing. I use a lot of Huber Zip Tape too. A lot. I use 11-inch screws to fasten everything together. I go over this design and why I think it was smarter this vs screwing into the rafters. I detail the tools and fasteners I used. I mention tools I wouldn't use again. This building using almost no electricity to heat and cool with a mini split. It is quieter inside and the air quality is better too. The next building I build will be different. Sponsor me for that build. Come on. Thanks for checking out this video. Please like and subscribe. Music by me