Why Do You Need a Crawl Space Moisture Barrier?

A crawl space under a house.
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One big problem with a crawl space is high moisture levels. This can cause smells, dry rot, mold, and can also promote an invasion of insects. One preventative measure is a crawl space moisture barrier. If you have an earthen crawl space or one which is below the waterline, then you will need a device to keep your space dry. The barrier will help to prevent moisture from entering your crawl space.

How Moisture Barriers Work

A moisture barrier, also known as a vapor barrier, prevents water from traveling up from the soil, and from there into the walls or ceilings of the crawl space. While the material stops moisture from reaching the walls, it also encourages it to drain into the soil, so there is not a layer of water trapped just below your crawl space for long periods of time.

Types of Moisture Barrier

In order to discourage moisture from penetrating through to the surface of the crawl space, it is necessary to have a barrier around 2 inches thick. While some people choose to use a 2-inch thick concrete mud floor as their barrier, others use a vapor liner, which keeps the moisture below a sheet of thick plastic. Choosing the right type of crawl space moisture barrier can save you time and money on mold clean-up and wooden joist repair.

Other Tips

A basement vapor barrier can also be installed in a crawl space. The barrier keeps moisture from reaching the walls. It is usually made of a plastic sheet that is fitted to the area. Certain standards of practice apply to the installation of plastic sheeting on the floor of a crawl-space that must be adhered to.

A dehumidifier can also be used in the crawl space to prevent mold and mildew. When purchasing a dehumidifier for the area, make sure it has a large enough capacity to service the entire space.

If your crawl space already has a small amount of water in it, you can install a sump pump to move the water away from your home. If the crawl space has a large amount of water, you may need to repair the exterior footings of your home before installing a sump pump.