Recessed Medicine Cabinet on Exterior Wall. Insulation behind?
I’m trying to figure the best *if possible* way to install a recessed medicine cabinet on an exterior facing wall. Right now all I can think of is using 2×2 lumber to fir out my 2×6 wall, so that the medicine cabinet still allows 3.5″ of room for insulation behind it. (Assuming 3.5″ deep cabinet, and 2×6 + 2×2 = 7″ depth)
I would only use 2×2’s for the width of the vanity, and then return to standard 2×6 thickness so my linen cabinet would have the extra space, and the jog in the wall would not be noticeable with the cabinet fit in there.
I live in Zone 5, and am worried about the loss of insulation on top of the fact that the room is a humid environment. Would I be okay by using 3.5″ of rigid foamboard directly behind the box I build for the medicine cabinet, and then continuing my mineral wool in the rest of the wall cavities? With mineral wool I have to use the smart membrane, and wonder how I would detail this medicine cabinet “hole” compared to the standard studs? 3.5″ of XPS foam would not be vapor permeable, so I am concerned all the way around with my osb sheathing being able to dry if it needs to, while the wood in the cavity would only breath towards the medicine cabinet.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part