Mold on the OUTSIDE of the vapor barrier in bathroom
The wallboard above our shower enclosure was starting to delaminate due (probably) to high humidity in the bathroom. Whoever lived here before us didn't caulk/seal between the wallboard and the shower enclosure in this bathroom. As I cut out the wallboard along an exterior wall, I could see dark black splotches in the pink rolled insulation through the vapor barrier. Further inspection revealed more dark splotches ON the vapor barrier on the side in contact with the insulation. There was no mold on the wallboard itself or on the side of the vapor barrier in contact with the wallboard. Has anyone seen anything like this before? My guess is that the humid air from the shower worked its way into the wall space through a small gap between the wallboard and the shower enclosure. Does that sound plausible? If so, then is it reasonable that I could eliminate the source of moisture by replacing the insulation, installing a new vapor barrier, and making sure the vapor barrier is sealed?
And yes, I will be installing a bathroom vent to get rid of the humidity.