5 Crawl Space Waterproofing Tips


Crawlspace waterproofing is an important investment for a clean, safe home. It will prevent floods, mold, and mildew, as well as infestation by water-loving insects. Learn more about how to effectively waterproof your crawlspace from the tips below.

Before You Build Your House

Carefully study the terrain where you plan to build your house or cottage before you commit to the location. Crawlspace floods are constant on a sites which rest just above the water table. Building on a slab with no basement or crawl space might solve the problem, but you would be wise to choose another site.

Keep Water Out - Exterior Drainage

If the soil is very damp or your property is near a body of water such as a lake, pond, or river, you must provide exterior drainage and waterproofing around the crawl space foundation exterior.

It should include a waterproofing agent applied to the concrete, a base of clean gravel the same depth as the foundation footing, and a tile drainage system around the entire footing. Cover the perforated plastic tile with more gravel and pour 5-inches of topsoil. Cover the top soil in sod.

Install a sump pump that is equipped with a battery backup inside the crawl space. Be sure to install adequate gutters and drain pipes to guide rainwater at least 8-feet from the house.

Remove Water From the Crawl Space - Sump Pumps

Removing standing water from a crawl space is a much more difficult project. If there is just a film of water less than .5-inches deep, install a sump pump with proper piping to direct the water away from the house. Get a pump rated for gallons per hour, not just the horsepower of the motor.

Sizes range from 3,000 to 7,500-gph. To keep your sump pump running during a power outage, buy one with a battery backup system. If your house is on a septic system, do drain the sump pump into the septic tank. Doing so degrades the septic tank environment and prevents it from processing waste properly.

Keep the Crawl Space Interior Air Dry

Use a dehumidifier to keep the air moisture to a minimum and reduce the air ventilation of the crawl space as much as possible. If the air is moist, it will encourage mold growth. Use a properly sized polyethylene vapor barrier to cover the interior walls and attach it to the concrete with a duct sealant to reduce moisture seepage through the concrete.

If the Crawl Space Becomes Flooded

If there is consistently more than 2-inches of water in the crawl space, check and repair the exterior footings as noted above. Hire a contractor to remove the water. Install a sump pump as a precaution to pump out any water that might seep into the space.