Patching a damaged vapor barrier

Basement vapor barriers can be damaged in time, and this is why they need to be regularly checked. Having a deteriorated vapor barrier will make it ineffective and will allow water to infiltrate in your home. This will further lead to mold and mildew growth.

Immediately when you discover that the vapor barrier is torn or damaged, you should patch it or replace it.

Some of the tools and materials that you will need are:

  • Vapor barrier
  • Razor knife
  • Spray adhesive
  • Mastic

How to replace a barrier sheet

If the damage is more serious, then you should replace the entire barrier sheet. To do this you will need to use a razor knife and cut the entire barrier, or just cut the affected areas in rectangular or square forms. Then cut a new piece of vapor barrier a little large than the hole you’ve cut in the old sheet.


Use a trowel and place some mastic on it. Then, smear it into the space you have made in the vapor barrier. You will need to raise the mastic in small peaks to be able to fit them onto the barrier. Leave it to dry for 12 hours.


Only after the mastic has dried, place the patch on the hole and press it firmly. Use an adhesive spray to seal the edges of the patch. Then leave it to dry.

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