In your shower, one of the most crucial things to protect yourself from is mold and moisture damage. The CertainTeed Vapor Barrier uses an advanced technology of smart vapor retarder and air barrier film.CertainTeed MembraneOnly waterproofing your shower walls does not stop water vapor from getting behind your backer board and into your wall cavity behind. When you are waterproofing a shower, it stops liquid water from penetrating walls, but not vapor (steam). This looks like fog, and it happ …