Vapor Barrier Shower Wall Tile

If you re using greenboard or drywall for the walls of the shower you ll need to put the vapor barrier between the greenboard and the water.

Vapor barrier shower wall tile. But most residential showers don t generate enough water vapor to be problematic. This will be thick enough to hold the moisture effectively. 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. This is especially important in a shower located on an outside wall but also helps even if the shower is on an inside wall.

It s usually a thin layer of plastic that sits between the drywall and the studs. Because they will absorb moisture there should always be some sort of a moisture barrier when using these tile backer boards in a shower or other wet area. In a shower you can t have the vapor barrier on top of the greenboard. You have several options to choose from when choosing a vapor barrier and each affects your waterproofing strategy.

A good vapor barrier should be 10 to 15 millimeter polyethylene. But they do generate enough water to need moisture management. Either a vapor type barrier behind the board or a waterproofing membrane on the front. The benefit of this is that this closed cell insulation is 100 waterproof but it also provides a vapor stop to keep water vapor from entering the wall cavity.

Screws secure the cement board to the wall studs. This can take the form of a sheet membrane or a paint on liquid. 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. Tile is laid onto the cement board with thinset mortar or mastic.

In a shower situation you recognize it as steam. Then the cement board is installed on top of the plastic sheeting. First you have vapor barriers that are installed behind your tile substrate common materials that are used due to their availability and cost are a continuous plastic sheeting with a minimum thickness of 4 mils 15 lb or 15 felt paper some building codes require a minimum grade b building paper to qualify as a vapor resistant barrier. If you have a steam shower with a steam generator then a vapor retarder is required.

In the world of tile you need a vapor retarder when you have extreme amounts of water vapor that need to be managed. Moisture barriers stop that. Steam stays in a gas form until it cools down or hits a barrier such as a shower door tile ceiling or a mirror. In this highly convenient inexpensive and popular application a moisture barrier of 4 or 6 mil thick plastic is installed directly over the wall studs.