The first step in crawl space encapsulation is to seal the area, isolating it from external elements. This often involves covering the crawl space floor, walls, and sometimes even the ceiling with a durable vapor barrier. The vapor barrier is typically made of materials like reinforced polyethylene to prevent the entry of moisture and soil gases.

One of the primary objectives of encapsulation is to control moisture levels in the crawl space. Moisture can lead to various issues, including mold growth, wood decay, and structural damage. The vapor barrier acts as a barrier against ground moisture, preventing it from entering the crawl space. A dehumidifier may be necessary to keep the crawl space dry.

Traditional crawl spaces often have vents that allow outside air to circulate. In encapsulation, these vents may be sealed or modified to control airflow. The idea is to prevent humid air from entering the crawl space and disrupting the controlled environment.