I am remodeling a powder room in my house. When I stripped the wallpaper I noticed some mold on the face of the drywall. I then tore out the section of drywall that was molded and found mold on the inside of the stud bay. The wall is an exterior wall with a stone veneer. I don't believe there is an air space between the stud wall and the stone. Is there any way of keeping out the moisture that is getting into the stud bay, it is not water from a leak.