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Crawl Space Ventilation

Crawl Space VentilationIn 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.

Crawl Space Ventilation

Why Are Open Crawl Space Vents Bad?

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

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.

Additional Resources:

Crawl Space Moisture Control

Crawl Space Encapsulation Code


i. USDA. Techline: Crawl Space Ventilation. 

ii. Advanced Energy. Housing Zone: To Vent or Not to Vent.

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After all, requesting your free inspection takes 60 seconds, and you can download your Free Homeowner’s Guide to Crawl Space Repair immediately!


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