How to Patch a Torn Basement Vapor Barrier

If you have fitted a basement vapor barrier, you will need to check it regularly for tears and holes. Any damage to the surface of the vapor barriers will prevent it from blocking moisture, and you may find your insulation becoming wet, moldy or rotting. The best way to prevent water damage to your insulation is to repair tears in your basement vapor barrier before they can harm your insulation.

Step 1 - Replacing the Vapor Barrier

Take the piece of vapor barrier which has been damaged, and trim it away using the razor knife. Cut a piece of vapor barrier material slightly larger than the hole you have just cut. Trim it to fit, and then place to one side.

Step 2 - Add a Layer of Mastic

Place some mastic onto a trowel, and then smear it into the space you have just created in the vapor barrier. Raise the mastic into small peaks, so that you will be able to press the plastic barrier down more firmly into it, and then leave to dry overnight.

Step 3 - Make the Patch

Once the mastic is dry, place the patch onto the space you have cut, and press down. Cover the edges with a layer of spray adhesive, and leave to dry in place.