Why are Crawl Spaces Damp?

Homes are vented thru the roof, to allow warm air to escape. The warm air inside your home rises and slowly escapes thru the roof. the same time, air is sucked into your home from the crawl space below. This process, known as the stack effect, brings moisture from the earth into your home. Damp crawl spaces can produce condensation, mildew, funghi, musty odors, and most of all, an unhealthy environment. Crawl space humidity allows mold to grow and release spores. A crawl space with humidity will have your home constantly filled with tiny invisible mold spores floating thru the air.

If there’s moisture, there’s a good chance that spiders, snakes, silverfish, rats or mice, even termites will make a home in the shady, damp crawl space under your home. The rot and decay from moisture can cause structural damage to your home. If there is mold, you’re likely to have dust mites as well.

How do crawl spaces get so damp? Roof water may be falling too close to your home. A typical roof can produce 1,250 gallons of water during a one-inch rainstorm. If this water is not properly drained away from the home, it can saturate the ground around your home. In the summer, excessive watering of the landscape and flowerbeds can create too much moisture around the foundation. If your home is on a slope, the rainwater will flow down the slope and pool next to your foundation. Even if there is not standing water, this moist soil will evaporate in to your crawl space, as the capillary action in described above.