Crawl Space Ventilation

Learn why crawl space ventilation is not the answer, and what you can do to improve the health and safety of your home.

In the past, it was common practice to endorse crawl space ventilation. Accordingly, the idea was that venting the crawl space would keep it dry. However, we now know this just isn’t the case.

Crawl space ventilation, especially in humid areas, ends up doing more harm than good. The outside moisture that’s pulled into the crawl space creates the ideal environment for mold, mildew, insect infestations, and wood rot. According to the USDA, “experimental studies have shown that crawl space ventilation is usually counterproductive, especially in humid climates.”

In other words, mold and mildew are more likely in environments that have a relative humidity over 50%. It’s important to realize that outside moisture can cause a variety of problems, including pest infestations.

“Experimental studies have shown that crawl space ventilation is usually counterproductive, especially in humid climates.”

In fact, an Advanced Energy study found that crawl spaces with open vents stay above 70% relative humidity – well above the healthy humidity level of 50%. Furthermore, open vents can even become a problem when a vapor barrier has been installed.

Why Are Open Crawl Space Vents Bad?

Crawl space ventilation typically results in high humidity, which will:

Always encourage mold and mildew to grow.
Create the ideal environment for termites and other pests.
More than likely increase your heating and cooling bills.
Cause high indoor humidity, which will then invite dust mites in to stay.

As you can see, crawl space ventilation can lead to some major problems. Therefore, it’s a good idea to protect your home, family and health by having a professional seal your crawl space. To clarify, this is the only way to ensure that you won’t have a crawl space moisture problem.