Rigid foam ceiling question
I’m building an ICF home in WV. I have my roof trusses on 24″ centers, 2×4 bottom chords, and 9’7″ from the floor to the bottom of the truss.
I would like to use rigid foam board for insulation and I’m wondering if it would be possible to use long screws with washers (Wind Lock) to screw through 6-8″ of foam into the truss? Cover it with an acrylic stucco and fiberglass mesh system.
If that isn’t a dumb idea, my follow up questions would be: What’s the best way to deal with the butt joints? Can I leave space between the sheets and then fill with spray foam? Just seems easier than taping. What about truss movement? Can’t I use the same techniques as I would with drywall? Should I use a metal lath instead of fiberglass? Is there just a better way to go about this?