Attaching vapor barrier to a concrete wall can help to prevent the movement of moisture through the concrete and into the building. Eliminating the movement of moisture into a building reduces the likelihood of mold and other problems caused by the buildup of water. Depending on your location, 6-mil vapor barrier can also be used as part of a termite prevention strategy.
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Clean the Wall
Before attaching the vapor barrier to the wall, it is essential that you wash the concrete to remove substances such as mold, grease or sand. To clean the wall, mix up a dilution of water and trisodium phosphate, or TSP, in a bucket. Follow the instructions on the TSP when measuring ratios of water to TSP. Dip a scrub brush into the bucket and scrub the wall thoroughly. Rinse the bucket and fill it with clean water. Dip a sponge or cloth into the clean water, wipe down the wall, and let it dry completely before proceeding.
Measure and Cut the Plastic
Before you purchase your plastic, measure the amount of space you need to cover. Add 6 to 8 inches to each length to allow for overlapping areas. Vapor barrier is sold in rolls. The average roll covers roughly 500 square feet. Larger rolls are also available. Once you've purchased the plastic, roll it out and trace your measurements onto the plastic with a marker first, if you're concerned about your ability to cut straight lines freehand. Cut the plastic with a utility knife or scissors.
Attach Plastic to Wall
Hold the plastic up over the wall you want to cover and use a utility knife to cut around extrusion such as windows and pipes. Apply construction adhesive to the wall. Start along the top edge with a thick bead of adhesive and work downwards. Apply the adhesive in short zigzags or waves. Also apply adhesive around all locations where you cut holes in the plastic. Press the plastic to the wall. Start at one of the top corners and move across and then down, stretching the plastic and keeping it tight and smooth as you go.
Flashing and Tape
If the wall is thoroughly cleaned ahead of time, construction adhesive should keep plastic securely fastened on its own. To further secure the plastic in place you can nail galvanized flashing or alkaline copper quaternary pressure-treated furring strips along the edges of the plastic. Use masonry nails approximately every 6 inches. Apply sheathing tape to edges where two pieces of plastic meet. Overlap one sheet over the other and then tape the edge of the top sheet to the bottom sheet.