Insulating single slope metal roof with no attic
I am in zone 3 (DFW area) building a 16′ x 16′ conditioned room, using 2×6’s for walls and 2×10’s for the rafters. I have been reading a ton of articles on this site and elsewhere, trying to understand everything but am a little overwhelmed.
I have the walls covered in OSB. I was thinking about putting a layer of 3/4″ polyiso over that, wrapping, and attaching metal siding.
For the roof, I was thinking of covering in OSB or zip sheathing and taping and then 2 layers of 1/2″ polyiso (was a little confused if I need some other type of underlayment). Screw 1×4’s to the foam, running the length of the rafters and attaching metal roof to that. Not sure if the 1×4’s are needed and if I should do the walls too for some sort of rainscreen.
For the interior, I was originally going to spray open cell foam but not sure after all the reading. It seems like I see a lot of recommendations for blown in cellulose.
Am I going down the right track or do I need to do something different? Slowly learning and thanks for any help.
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