Bathroom Shower Exterior Wall – Vapor Barrier or Not?

I’m in climate zone 5 with 2″ exterior polyiso at R13.5 and R21 Rockwool in the wall cavities. One of my shower walls is on a exterior wall. I’m planning… I’m in climate zone 5 with 2″ exterior polyiso at R13.5 and R21 Rockwool in the wall cavities. One of my shower walls is on a exterior wall. I’m planning…Read MoreGreenBuildingAdvisor