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What are the Best Tips for Crawl Space Drainage?

Amy Hunter
Amy Hunter

To improve crawl space drainage, place a moisture barrier on the ground, reduce the amount of moisture around the house, and provide a way for the moisture to drain from under the home. These three tips will eliminate moisture problems in most situations. If the home is built at the bottom of a steep slope or on the site of an underground spring, more aggressive measures may eventually be required to dry out the crawl space.

The first step in effective crawl space drainage is to reduce the amount of moisture around the base of the house. If the house does not have gutters, now is the time to install them. If the home does have gutters, they may need to be cleaned. Leaves and other debris can clog gutters, preventing water from following the gutter into the downspout. The overflowing gutters drip at the base of the house, allowing the water to run into the crawlspace.


Once the gutters are in place, check the condition of the downspouts. Many homes have downspouts that drain against the side of the house. This provides a stream of water directly at the base of the foundation, where it can interfere with crawl space drainage. Extend the downspouts away from the house and direct them to a low point so the water has an easy path away from the home.

Another way to improve crawl space drainage is to be careful when tending to the landscaping around the base of your home. Only water your plants enough to satisfy their needs. Water that is not immediately absorbed will drain against the house where it can create crawl space drainage issues. Keep mulch raked away from the foundation as well, since it can absorb moisture and add to a damp environment.

To provide a way for moisture to drain away from the house, grade the crawl space so that it slopes gently to a single low point. This will provide an exit for moisture. Make sure that the low point in the crawl space has an outlet to a low point in the yard. A gentle slope away from the house and to the lowest point in the yard will encourage crawl space drainage.

Once the drainage issues are corrected, use a thin sheet of plastic to create a moisture barrier. Cut the plastic to fit the crawl space area and secure it with lawn staples. This will prevent moisture from the ground from seeping up and entering the crawl space.

It is important to discourage moisture from accumulating in the crawl space area because the moisture under the house can lead to mold and mildew developing, create unpleasant smells and weaken the structure of the home if left unchecked. Crawl space drainage problems can typically be handled as a do it yourself project, however it is important to take the time to discover where the water is coming from in order to treat the situation. Once treated, check the crawl space regularly for signs of reoccurring moisture problems.

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