Frequently Asked Questions

Q – What is a crawl space?

A – A crawl space is an unoccupied, unfinished space within a building, between the ground and the first floor. The crawl space is so named because there is typically only enough room to crawl rather than stand.

Crawl spaces can be actively or passively vented, or closed. In regions with a humid climate, vents to the outside can also allow moist air to come in, which can then condense if temperatures (e.g.on cooler surfaces such as ductwork) drop below the dew point, creating a damp environment that is hospitable to indoor mold growth as well as infestations by rodents and insects, possibly including wood-damaging ones such as termites, or carpenter ants. Even without condensation, relative humidity above 80% can support mold growth and rot wooden structural materials such as floor joists. Humidity in some sealed crawl spaces is controlled using a dehumidifier. Encapsulation is sometimes used to prevent the passage of air from the crawl space to the living environment, to save energy and improve indoor air quality, since air in the crawl space might otherwise tend to rise due to the stack effect.

Encapsulation involves adding a vapor barrier to the floor, sealing off all openings to the outdoors, adding thermal insulation to the walls, and sealing off any remaining gaps and cracks (such as plumbing and wiring penetrations) between the crawl space and the floor of the home. A 2005 U.S. Department of Energy study of homes in the southeastern United States found that closed crawl spaces with sealed foundation wall vents, sealed polyethylene film liners and various insulation and drying strategies had significantly reduced space conditioning energy use compared to traditional wall-vented crawl spaces with perimeter wall vents and unsealed polyethylene film covering the ground surface. Crawl Space doors are generally insulated during this process.

The average annual percentage of humidity in the Charlotte region is: 67%

Q – How does moisture get into your crawlspace?

A – Up to 12.2 gallons per 1000 sf daily can come from the soil itself.
The amount that gets into the crawlspace from vents is directly related to the outside humidity. Humid air will naturally enter though your home’s foundation vents and wick their way through the building elements of your home. Lack of gutters and poor grade can also lead to moisture getting into your crawlspace.

Q- Why is moisture in your crawlspace a problem

A – As discussed above moisture in your crawl space can lead to fungal growth, insect activity as well as rotting of structural lumber and insulation damage. This can also lead to increased allergens within your home affecting the health of your family. Up to 50% of the air you breathe in your home comes from the crawlspace.