Plastic Vapor Barrier Bathroom Wall

Without a vapor barrier in place condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria.

Plastic vapor barrier bathroom wall.

Illustration by ian worpole. Complete air blockage is essential to provide a satisfactory moisture barrier and will also maximize the wall s energy efficiency. Use a minimal amount of staples to secure the vapor barrier to the walls studs. Holes in the vapor barrier that allow humid air through may allow a lot more water vapor into an assembly than the vapor barrier is stopping.

A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. Even if you use plastic vaper retarder over insulation and then drywall over it you can still trap moisture between the layers because that is where condensation starts when the temp on the interior side is greater than the temp in the wall cavity opposite sides of that vapor retarder. Install vapor barriers after the bathroom s plumbing electrical and insulation are complete. It s also a relatively easy option for diyers.

Not every type of insulation needs a vapor barrier. Seal all wall cracks and holes in the wall being vapor proofed to block air gaps. Vapor barriers sheets of plastic or kraft paper keep water vapor out of the wall cavity so the insulation stays dry. A vapor barrier reduces the movement of water vapor by diffusion.

Moisture barriers stop that water or vapor from getting any farther and potentially rotting your studs the drywall or greenboard installed behind the enclosure. Do not install a vapor barrier over an existing plastic sheeting this will promote condensation. Use special sealing tape to join sheets if polyethylene sheets are being used. Plastic specifically 6 mil polyethylene plastic is.

Not every wall does. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. But if it does the barrier should face inside in northern heating climates and outside in humid southern climates. Liquid barriers may also be used to prevent moisture from getting into the walls.

When a vapor barrier is on the side of a wall where the dry air is i e outside in winter or inside in summer moisture problems can occur. Plastic sheeting is used because of its low level of water permeability.