I have a brick house built in the 1920s. I'm installing a bathroom basement based on an existing layout, but I'm trying to keep the "wet" side (mechanical room with hot water heater, etc.) physically separate from the "dry" side (scrapbook room, home office). The new bathroom will have a shower, whereas the old bathroom did not.
I'm installing a 2×4 stud wall between the bathroom and home office. The home office side will have mold resistant 1/2" drywall on the walls. The bathroom side will have concrete board covered with a water barrier (Kerdi, more than likely) and tile in the shower and FRP in the non-shower bathroom area. Of course, I'm also installing a fan and venting to remove moisture from the air after a shower.
My question, and I'm planning on installing bat insulation in the wall, is:
Should I put a vapor barrier on the home office side, or will this eventually trap moisture/condensation in the wall?
Best Answer
No, there's no need to install a vapor barrier between two conditioned spaces. The purpose of a vapor barrier is to prevent warm moist air from traveling through the insulation and condensing on the cooler side, which can easily happen in cold climates. With a conditioned space on both sides, you can allow any moisture in the air to pass through.
There's also no need for insulation except for sound proofing (fires can pass through doors, as can any heat). For sound, make sure your insulation is designed for that, and also consider a resilient channel or similar product that will keep the drywall physically separate from the studs, which is how many sounds travel through walls.