Mold under a house in a crawl space can cause major structural damage and rotting, according to EnergyStar.gov. Mold generally grows in dark, moist environments. Treatment involves reducing moisture and removing mold that already exists. The most important thing is to identify where moisture is coming from and eliminate it.
Mold under a home is caused by high humidity levels. Large amounts of this humidity comes from soil under a crawl space. This can result from poor soil drainage and lack of ventilation within the crawl space.
The best treatment for mold under the house is to cover the dirt floor under a crawl space with a plastic sheet or vapor barrier. This will prevent soil from increasing humidity levels. If there is standing water in the soil already, it should be dried up before the plastic covering is placed over the soil. One way to do this is with ventilation fans. Another solution to mold under a house is to install perimeter drains. This will carry moisture away quickly from the bottom of your home.
Painting surfaces with mold-inhibiting paint is an excellent way to prevent mold from growing under your home. Paint can be applied with a brush or with a spray. Installing ventilation fans can also reduce humidity and prevent mold from growing in the first place.
Some people have supports for their home under their crawl space. If these supports are made of wood, they can have rot the wood and make the foundation of your home unstable.
Black mold is the most commonly found type of mold under a house. Most of the time the mold species found are Cladosproium and Stachybotrys. The most important part of solving a mold problem in a crawl space is to eliminate the source of moisture. Moisture is the direct cause of mold growth, and without eliminating it, you will have mold forever.