5 Crawl Space Waterproofing Tips

An important investment in a clean, safe home is crawl space waterproofing. It will prevent floods, mold and mildew buildup, as well as infestations of water-loving insects in your home. Learn more about how to effectively waterproof your crawl space 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 building there. Crawl space flooding problems will be constant on a site that is 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, provide exterior drainage and waterproofing around the crawl space foundation exterior. This should include a waterproofing agent applied to the concrete, a base of clean gravel the same depth as the foundation footing and 2 feet outward from it, and a tile drainage system around the entire footing. Cover the perforated plastic tile with more gravel, and pour in topsoil to about 5 inches deep. Lay sod on top.

Inside the crawl space, install a sump pump that is equipped with a battery backup that can drain water out to the water source. Be sure you install adequate gutters and drain pipes to drain away rainwater at a distance of 8 to 10 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 ½-inch 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, ensure you buy one with a battery backup system. If your house is on a septic system, do not install the sump pump piping so it drains into the septic tank. This will degrade the septic tank environment, and prevent it from processing waste properly.

Keep the Crawl Space Interior Air Dry

Use a dehumidifier to keep the moisture content of the air to a minimum, and reduce the air ventilation of the crawl space as much as possible. If moist, humid air can enter the crawl space, it will encourage mold growth. Measure sufficient polyethylene vapor barrier to cover the interior walls, and attach it to the concrete with a duct sealer 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, you will need to check and repair the exterior footings as noted above, and arrange to have the water pumped out by a flooding clean-up specialist. Install a sump pump as a precaution to pump out any water that might enter through seepage