Root Causes
Crawl spaces are often overlooked by homeowners, but it is essential to pay attention to the area beneath your living space. Don't let your crawl space fall out of your mind.
The stack effect in a home refers to the natural circulation of air through the building. Warm air rises and increases pressure at the top of the building, causing hot air to be pushed out and cold air to be drawn in. This process is reversed in the summer, when cool inside air is pushed out and hot air is drawn in. In a home with a crawl space, this circulation can be especially problematic because the crawl space is often vented to allow for air drying. However, this ventilation can allow outside air to enter the crawl space and circulate through the rest of the home, potentially leading to comfort issues, moisture damage, and energy loss. It is important to consider the potential negative effects of vented crawl spaces on a home’s air quality and overall condition.
In moisture-rich areas, home engineers may recommend non-vented crawl spaces over ventilated crawl spaces because non-vented crawl spaces can help prevent moisture from entering the space and potentially damaging the home. When a crawl space is ventilated, outside air, which is often rich in moisture, can enter the space and contribute to high levels of dampness and humidity. This can lead to issues such as mold growth, weakened structural components, and rotting wood.
An unventilated crawl space, on the other hand, can help prevent this moisture from entering the space and potentially causing damage. In addition, an unventilated crawl space can help improve the air quality in the rest of the home by preventing this humid, potentially contaminated air from circulating through the home.
Water infiltration in a crawl space can occur through vents, plumbing leaks, or porous block walls. This water can attract pests, cause wood rot, and weaken support systems, as well as contribute to mold and mildew growth in the crawl space and throughout the home.
Humidity levels in a home should be kept between 35-40% for optimal living conditions. If the humidity is above 50%, it is recommended to use a dehumidifier to help reduce the moisture in the air.
High relative humidity and moisture in a crawl space can promote mold growth, especially on organic materials such as wood and insulation. In addition, the moisture that accumulates in a crawl space may pass into other parts of the building through cracks in walls, floors, and ceilings, contributing to mold growth in those areas as well.
According to the National Association of Home Builders (NAHB), having a properly functioning exterior drainage system can benefit homeowners with a crawl space in several ways.
First, an exterior drainage system helps to direct water away from the foundation of the home, which can help prevent water infiltration into the crawl space. By directing water away from the foundation, an exterior drainage system can help protect the crawl space and the rest of the home from these potential issues.
Second, an exterior drainage system can help to reduce the humidity in the crawl space. When water infiltrates the crawl space, it can increase the humidity levels, which can lead to mold growth and other issues. By directing water away from the foundation and crawl space, an exterior drainage system can help to reduce the humidity and improve the overall environment in the crawl space.
Overall, having a properly functioning exterior drainage system can help protect homeowners with a crawl space from water infiltration, humidity issues, and the various problems that these issues can cause. (Source: https://www.nahb.org/en/consumers/home-construction-and-building/crawl-space-basement-and-foundation/crawl-space-basement-and-foundation-drainage-systems.aspx)
