How to Waterproof Your Crawl Space and Make It a Dry and Useful Space in Your Home

8 November 2016
 Categories: Construction & Contractors, Articles


It can be frustrating when you have deal with a wet crawlspace or basement in your home, especially when you want to use the space for storing items without worrying about water damage. It is possible to waterproof your crawlspace or basement with the use of a few simple techniques to divert and prevent water seepage. Here are instructions to help you waterproof your crawlspace from its interior and exterior.

Waterproof Your Foundation's Exterior

It is important to add sufficient drainage around the exterior of your home to keep your crawlspace dry, as this is the main route water uses to seep from and into your home's crawlspace. There can be several reasons for this. Your home may be built on soil with a high water table, may be near a body of water, or may contain a layer of clay in the soil around its foundation, and all these things can cause water to seep into your basement crawl space.

Protect the outside of your home by installing a french drain around the perimeter of your home and on at least three sides of your home's exterior. This will capture any water flowing within the soil around your home and divert it into the drain and away from your basement foundation. 

To do this, you will need to excavate a trench around the outside of your foundation walls, approximately four to six feet from your home. The trench needs to be at least two feet in depth, but it is better if you excavate it to a depth just below the foundation footings of your crawlspace. The width of the trench will need to be at least six inches wide. 

It is important to make sure you use the right size of gravel for your drainage system. A medium-sized gravel with gravel pieces one to two inches in diameter is perfect, as this gravel will provide the path of least resistance for the water, allowing it to easily flow into the system, and the gravel will not clog the holes of your perforated drain pipe.

Pour a two-inch layer medium-sized gravel, then lay the perforated drain pipe onto the gravel within the trench around the exterior of your home. Cover the pipe with additional medium-sized gravel, filling the trench within five inches from the top of the surrounding soil. Cover the top five inches of space with a layer of topsoil and then sod or other matching landscaping material.

The natural slope to your yard will provide a slope to the perforated drain pipe buried in your yard. This slope allows gravity to drain the water into the lowest part of your yard and away from your home's foundation and crawlspace. 

Seal the Interior Crawlspace Walls

The second part of waterproofing your crawl space is to protect it from the inside. If you have had any moisture damage in the past on the interior of your crawl space, clean to remove any mold or mildew from the concrete walls and floor. Use a mold and mildew cleaner with a sponge to wipe the area clean. Allow the surface to air dry.

If there are any cracks down the concrete walls of your crawlspace, use a tube of hydraulic cement to fill each of them. Make sure all spaces within the crack are filled with the product and allow drying time according to the product's instructions.

Next, apply a concrete waterproofing paint onto the walls of your crawlspace with a paint roller, brush, or paint sprayer. Apply paint onto the floor as well if the floor is also concrete. As concrete is porous, it may be necessary to apply two to three layers of the waterproofing paint to make sure you seal up all holes on the surface of your concrete.

Use these two waterproofing steps to protect your crawlspace from its interior and exterior so you can have a dry crawlspace under your home.