What is the best way to insulate a Metal structure from the Inside?

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What is the best way to insulate a Metal structure from the Inside?

Jacky Surber May 2, 2021Last updated: May 25, 2021

Hello. I am very worried about the proper insulation of my all metal home kit I recently purchased, steel super structure and studs, roof and siding. The metal siding acts as the sheer wall and so I can't insulate between the siding and the exterior studs, besides a very thin foam vapor barrier that was included. I read all the articles here that say cavity insulation won't work well because of thermal bridging. What about close cell spray foam? Would that work over the studs & could the dry wall be screwed through the spray foam or would that mess up the thermal break? Or EPS foam sheets on the inside of studs before dry wall? I need R38 in roof (4:12 pitch)  and R21 in the 6" x 10' H exterior walls. Was planning on cathedral ceiling in most of the house (2,052 SF) and 9' ceilings over 685 SF. I'm so confused as to how this design passed title 24 here in CA, and stressing I'll have a bad design that won't pass 3rd party verification. Thanks so much for any help. 

Responses (2)

P McCavity May 8, 2021, 11:48 p.m.
I'm interested to see the response of the pros here too, I'd have said some low CFC spray foam but that's going to cost.