Sealed rigid foam board good enough drainage plane?
OK, I need your thoughts on this. I’m at home for a few weeks and I forgot to bring home my reference material for drainage planes from work. I’m tearing off old 90 year old siding and 15 # felt and replacing it with 1″ rigid foam and fiber cement board siding. I’m doing one side of my house per year. Last year I left the felt on,as a backup drainage plane and used weather-seal tape all around on the foam. On this side, the felt is poorly installed so my plan is to rip it all off. I realize I’ll have to pay great attention to all seams, but it would be a lot less work if I could put the foam directly on the underlayment sheathing. (some shiplap boards, some dropped siding used as sheathing)
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