Redoing a bathroom where one of the shower walls is an exterior wall. Framing is done with 2x6 and I would like to replace the current insulation pictured with XPS foam board. Due to my location, the best I can get my hands on is 2” thick with an R10 value.
My plan is to double up since I have room and worth it in my opinion. Main question is should I put in a vapor barrier? House was built in 1984 and no vapor barrier anywhere else.