Sealing a Crawlspace Liner

To prevent moisture from the high water table from welling up through the liner, I applied fiberglass tape and mastic to the seams.

In spite of being taped, many of the joints in the CleanSpace liner were leaking liquid water, as evidenced by the dirt stains left behind.

Fiberglass mesh tape followed by a thick coating of duct mastic created rugged, waterproof seams.

The self-sticking mesh tape held the overlapping plastic sheets in place as the mastic set up.

After removing any loose tape, the authors applied mesh tape and mastic to every lap and cut around the piers.

To make sure they sealed every joint, they worked the piers as a team, positioning themselves on each side; this also reduced unnecessary movement on the membrane as the mastic set up.

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