For decades, building codes and conventional wisdom prescribed ventilating crawl spaces with outside air as the primary means to control moisture in crawl space foundation homes. Because of this, many homes built on crawl space foundations in the Southeastern United States have suffered from poor moisture management within the structure and also the ailments caused by excessive moisture.

Some of the common symptoms of excessive crawl space moisture are:

  • Mold or moisture damage in the crawl space or living area

  • Musty odors in the living area

  • Condensation ("sweating") on air conditioning ductwork or equipment

  • High humidity in the crawlspace and living area which can be seen as mold growth on surfaces

  • Condensation on insulation, water pipes or metal (rust) in the crawl space

  • Buckling hardwood floors

  • Doors and windows that stick due to swelling

  • Insect infestations such as termites and wood-boring beetles

  • Mold leading to rot in wooden framing members

Research and now actual usage has shown that closing the crawl space, so that the crawl space has NO ventilation to the outside, can provide greatly improved moisture control and results in significant energy savings when installed properly.



Actions taken:

  • Moisture sources reduced or eliminated

  • Ground barrier is installed

  • Vents are sealed

  • Insulation is added according to site conditions


Automatic Opening Type Vent

Always Open Vent

Conversion Process

Some of the structural alterations that will be done to convert a vented crawl space to a closed crawl space involve sealing vents and installing a sealed moisture barrier on the crawl floor. This barrier is extended up the interior foundation walls of the structure. All water or moisture sources must be dealt with. On some homes we may also install insulation on the interior foundation walls.