Insulation in Downstairs Bathroom

[EchoFM]

I've recently started to work on finishing my unfinished basement, which includes a downstairs bathroom. On the foundation wall I put 1.5 inch extruded polystyrene behind the studs. In the rest of the basement I'd planned to put kraft-backed insulation (as per what my inspector requires) between the studs on the exterior, but I'm not sure how to handle the bathroom.

Should I put up kraft-backed insulation on the outside wall the same as every other wall? What about the inside walls? Is there any benefit in a bathroom to using plastic as a vapor barrier instead of the kraft-backed insulation?

I plan to put mold and mildew resistant drywall on the whole thing as well. I really don't want to put all this work into it only to develop a mold problem in a couple of years, but there seems to be a lot of conflicting information out there with bathrooms in general.

 

[dovetail]

No. In bathrooms do not use kraft faced insulation. The kraft facing is a vapor barrier. Use of a vapor barrier in bathrooms (shower surround area) can result in moisture getting trapped in the wall cavity. The inspector should fail it if its present around in the shower area as that is a code violation. I would recommend using densarmor drywall (https://www.buildgp.com) in the entire basement. Also Remember that greenboard is no longer allowed in the shower/ bath area of the bathroom, tomeet the IRC requirements you must either install CFB (hardiboard/ durorock) or fiberglass matted drywall (densarmor: http://www.buildgp.com/densshield-tilebacker-board)