Plastic Vapor Barrier Bathroom Wall

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.

Plastic vapor barrier bathroom wall.

Run the height of the vapor barrier from the top all the way down into the shower pan make sure not cut too short before the water barrier. They are required beneath your. Plastic specifically 6 mil polyethylene plastic is. Vapor barriers sheets of plastic or kraft paper keep water vapor out of the wall cavity so the insulation stays dry.

Not every wall does. It s also a relatively easy option for diyers. Install vapor barriers after the bathroom s plumbing electrical and insulation are complete. Plastic sheeting is used because of its low level of water permeability.

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. Without a vapor barrier in place condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria. Illustration by ian worpole.

A vapor barrier reduces the movement of water vapor by diffusion. Whether or not you need a vapor retarder hinges on three main factors your climate your home and the location of the wall you re insulating. 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.

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. Moisture barriers stop that water or vapor from getting any farther and potentially rotting your studs the drywall or greenboard installed behind the enclosure. Not every type of insulation needs a vapor barrier. 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. Seal all wall cracks and holes in the wall being vapor proofed to block air gaps.