A seam in an acrylic shower or a cracked grout joint or some missing caulk in a tile shower are all that is needed to let moisture get behind your shower enclosure.
Vapor barrier shower walls tile.
Water vapor that gets behind walls or travels up through light fixtures or hvac grilles into an attic will turn back into water when it cools off.
In a shower situation you recognize it as steam.
Moisture barriers stop that.
Water vapor is water in a gas form.
Steam stays in a gas form until it cools down or hits a barrier such as a shower door tile ceiling or a mirror.
It s usually a thin layer of plastic that sits between the drywall and the studs.
Use a minimal amount of staples to secure the vapor barrier to the walls studs.
Before tile can be installed on shower walls a moisture barrier must be secured so that any water that penetrates through the tile and grout does not get all the way through to the wooden wall.