Plastic Vapor Barrier Bathroom Wall

Complete air blockage is essential to provide a satisfactory moisture barrier and will also maximize the wall s energy efficiency.

Plastic vapor barrier bathroom wall. 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. But if it does the barrier should face inside in northern heating climates and outside in humid southern climates. Vapor barriers sheets of plastic or kraft paper keep water vapor out of the wall cavity so the insulation stays dry. Without a vapor barrier in place condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria.

Use a minimal amount of staples to secure the vapor barrier to the walls studs. Not every wall does. It s also a relatively easy option for diyers. A vapor barrier reduces the movement of water vapor by diffusion.

Illustration by ian worpole. Do not install a vapor barrier over an existing plastic sheeting this will promote condensation. 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. Not every type of insulation needs a vapor barrier.

They are required beneath your. Plastic specifically 6 mil polyethylene plastic is. Plastic sheeting is used because of its low level of water permeability. Moisture barriers stop that water or vapor from getting any farther and potentially rotting your studs the drywall or greenboard installed behind the enclosure.

Use special sealing tape to join sheets if polyethylene sheets are being used. Install vapor barriers after the bathroom s plumbing electrical and insulation are complete. 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. Seal all wall cracks and holes in the wall being vapor proofed to block air gaps.

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. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.