Line Your Crawl Space to Protect It from Mold

Time: 1 day

You found your crawl space and checked it for mold and moisture. Congrats! You’re well on your way to resting (and breathing) easier — but not so fast. Level up your crawl space by installing a vapor barrier. This plastic lining will protect your crawl space from mold.

What's in it for you?

  • Eliminate odors
  • Protect your floor joists and foundation
  • Stop future mold growth

(Show me how)

Stop Future Mold and Moisture by Lining Your Crawl Space Floor

  1. Check for mold and moisture. If you already have mold in your crawl space, you’ll need to deal with that first. Same goes for excessive amounts of moisture on the ground. You don’t want to cover up the problem — that’ll just make it worse.

  2. Figure out how much plastic you need. Start by measuring the floor, then the perimeter walls. This will tell you how much plastic sheeting to buy. Don’t forget: each seam will have a six-inch overlap, so add that to your total.

  3. Prepare the materials. Head over to your local hardware shop and grab a roll or two of 6-mil or heavier plastic sheeting. While you’re there, pick up some double-stick butyl seal tape, vapor barrier seam tape, and wall fasteners. Sound scary? Don’t be afraid to ask someone for help.

  4. Line the edges. Apply a horizontal strip of double-stick butyl tape to the wall a few inches above the ground. Grab your roll of plastic sheeting and peel the protective backing off the tape. Don’t forget to leave several inches of sheeting on the ground. Fold the corners of this overlapping sheeting into a triangle and tape the edge to the ground.

  5. Install wall fasteners. Carefully hammer these through the plastic sheeting and the double-stick butyl tape. You want to space them approximately 24 to 30 inches apart.

  6. Line the pillars. Grab the double-stick tape and plastic sheeting. You’re going to repeat what you did for the walls. Once the sheeting is up, cut slits in the plastic starting from the bottom edge and going to the bottom of the pillar at each corner. The sheeting should lay flat. Hammer in some wall fasteners to keep everything in place.

  7. Seal the area around the pipes. Cut a circle out of your plastic sheeting, making sure it’s wide enough to give you several inches of overlap. Cut another hole in the center of your circle just big enough for the pipe. Last cut — a slit from the edge to center hole. Slide the plastic around the pipe and tape the seam and the center hole to the pipe.

  8. Finally, line the floor. Before you do, clean up any sharp debris so there’s nothing to pierce the plastic. Cover the floor with plastic sheeting, leaving at least six inches of overlap at every seam. Tape the seams with seam tape.

Pro Tip: Sweep the walls with a broom before putting the tape on. Dust-free walls make for better adhesion.

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