Resource Article

Where Does Crawl Space Moisture Come From?

Blake Heron

2. The Vents

Crawl space vents are designed to allow Earth’s moisture to escape. The problem occurs in the summer when the hot, humid air enters the crawl space through these vents. Since warm air can hold more moisture than cool air, the moisture in the air is basically squeezed like a sponge when it is cooled. When this hot, humid air meets the cool air in the crawl space, the relative humidity skyrockets leaving condensation to form on HVAC, fiber-glass insulation, and floor framing.

3. Standing Water

Standing water underneath a house is a big problem. It typically comes from groundwater after heavy rain. It is common in this area because of the composition of the soils (mostly clay!). This water is constantly evaporating into the air which maintains a very wet and humid environment. Standing water should be dealt with immediately either through additional sand or with a drainage system and sump pump. Sand can be used when the standing water is minimal in a low spot. Drainage is appropriate when standing water is moderate to severe. If crawl space flooding isn’t dealt with, it can result in foundation settlement, other foundation problems, wood rot, crawl space fungus, mold, sloping floors, cracked walls, cracked bricks, and more.

*This crawl space had no vapor barrier. 31 joists had to be repaired, 6×6′ sections of the main beam had to be replaced, and the wood had to be treated with a fungicide. It cost them over several thousand dollars… Would that have happened if they had taken the minimum precaution and had a vapor barrier installed? The damage would not have occurred or it would have been minimized.

Serving Virginia Beach, Chesapeake, Norfolk, Portsmouth, Suffolk, Hampton, Newport News, Yorktown, Poquoson, Smithfield, and Williamsburg in Virginia as well as Camden County, South Mills, Elizabeth City, Moyock, Currituck, and Knotts Island in North Carolina.

If you have any crawl space moisture or other issues, you should have them checked out.  Reach us through our contact page or call 757-460-0444 to have a professional check your crawlspace out.


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Written By Blake Heron

Blake has specialized in crawl space & foundation repairs for over 10 years (since 2012). His prior engineering and business degrees from James Madison University in VA prepared him for a mastery of problem solving with crawl space & foundation repair issues. He is one of America’s top experts on crawl space encapsulation. As Founder of both ‘BAY Crawl Space & Foundation Repair’ as well as ‘GridLock Foundations’ he is a leading industry expert on crawl space foundation repairs.

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