Moisture in a crawl space generally comes from two places: the ground and the air.
Ground moisture finds its way to into the crawl space due to the negative pressure atmosphere which exists under all houses. That moisture, especially in the summertime, becomes water vapor that moves upward into the house.
Water from the air can enter the crawl space through vents and holes around pipes and ducts. The summertime climate in Maryland and especially the Eastern Shore often provides high levels of relative humidity, allowing for more moisture to be circulated in and out of the crawl space. This source of moisture often leads to a tropical rain forest effect inside the crawl space. HVAC equipment, floor joists and insulation will become saturated with warm, moist air and begin to sweat.
Both sources of moisture in a crawl space can lead to lasting effects on homes and families. Long-term effects include mold and wood rot to the structure, upper respiratory and asthmatic symptoms for homeowners and continuous foul odors inside the home. Solving ground moisture issues is the first key step created a healthy indoor environment.