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How to install vapor barrier in crawl space

how do I install a vapor barrier in a crawl space?

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Posted 2013-11-11T18:00:52+0000  by dlhayn dlhayn

Howdy dlhayn,


Welcome to The Home Depot community for starters. This is the place where we exchange ideas, expertise, and even opinoins on all things home improvment. So let's get to your question about "installing a vapour barrier.


The crawl space elevates the home off the ground which can be a necessity in particularly damp or termite-prone locations. It can also house the plumbing and ductwork of a home and grants access to repair or service those systems. A qualified basement or crawl space contractor usually will be the homeowner’s best bet for finishing a crawl space. However if you have some "do it yourself" skills here's one way to install a vapour barrier in your crawl space.


  1. Create good drainage around your home to keep rainwater from flowing in under your house. Sloping the soil away from your home at about 1/2 in. per foot is usually the best thing you can do to reduce crawlspace moisture.
  2. Cover the dirt crawlspace with a plastic moisture barrier. Overlap any seams and tape them. And bring the plastic about 6 in. up the wall and fasten it there. Stake the plastic down with landscape fabric stakes to keep it in place. Chances are that someone will have to slide around in the crawlspace later to fix a pipe or run a new cable. A few holes won't make any difference in performance, and they'll drain puddles if a heavy rain or leaky pipe leaves water on the plastic.
  3. Cover exposed foundation walls with 1-1/2 in. of rigid, moisture-proof insulation. This not only insulates the walls but also keeps rising dampness in the concrete from getting into the crawlspace. Some spaces require an additional fire barrier. Other types may require a drywall covering.
  4. Insulate the rim joists. We used rigid insulation and caulked it in place to stop air leaks.
  5. Cap the interior of the foundation walls with a 6-mil layer of plastic and galvanized flashing both to block moisture and to serve as a termite barrier. There is no sure solution for termites; building codes may require different details for termite control in your region.

One thing to remember is that depending on your city, you may need to aquire a permit from your local city building department.


Happy crawling,


Posted 2013-11-11T19:53:47+0000  by Dave_HD_OC
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