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What Causes Crawl Space Condensation?

Condensation in your crawl space is a sign that you have a moisture problem. When the relative humidity in your crawl space reaches 100% - the point when the air can't hold any more moisture - condensation forms.

Condensation in your crawlspace can then lead to a number of problems, such as mold and mildew growth, unhealthy air circulating through your home causing health problems, and high electric bills, just to name a few.

What Causes Crawl Space Condensation?

Venting causes crawl space condensation. The open vents let outside air into your crawl space. Your crawl space is typically cooler than the outside air, and when the airs combine it creates moisture.

For example, if your crawl space is 65°F and the outside air is 95°F (with a relative humidity of 70%) there's a temperature difference of 30°F. For every degree that the air's cooled, the relative humidity goes up by 2.2%. So when the different temperature airs combine, the relative humidity will increase by 66%.

If you add the 66% of newly created humidity to the 70% of the 95°F air, there will be a relative humidity in your crawl space of 136%. "Typical wall vented crawl spaces contain liquid water, moisture vapor, and fungal spores." The air can only hold moisture up to 100% so that humidity will be given up as condensation. Typical wall vented crawl spaces contain liquid water, moisture vapor, and fungal spores. *

At this point you'll see condensation on your duct work, floor joists, walls and other exposed areas. The condensation creates the ideal environment for mold and wood rot.

Crawl Space Condensation Solutions

Numerous studies have concluded that the best way stop condensation in your crawl space is to seal or encapsulate it.

"Houses built on...closed crawl spaces will be notably drier, support less mold growth and surprisingly are more energy efficient than houses built over vented crawl spaces."*

Encapsulation involves completely sealing your crawl space from outside elements. A thick vapor barrier, like CleanSpace will be laid on top of the floor and up the walls. A 3-inch inspection gap will be left near the sill so that pest control companies can still inspect for termites and other pests.

Any outside openings like vents and loose doors will be sealed. This will prevent outside air from entering your crawl space and contributing to the relative humidity and condensation problem.

Benefits of Crawl Space Encapsulation

Minimizes insect and rodent invasions

Minimizes mold growth

Can save you up to 15% on your energy bills

Improves your indoor air quality

We're Experts in Crawl Space Repair

We're here to help you find the perfect solution for your home, and find out the source of your crawl space repair problems. Requesting your free inspection takes 60 seconds, and you can download your Free Homeowner's Guide to Crawl Space Repair immediately!

Our Homeowner's Guide to Crawl Space Repair is your resource for learning about why you have crawl space problems, and what to look for to see if you have a problem.

References:

Coulter, J., Dastur, C., Davis, B., Dixon, T., Malkin-Weber, M. (2008) Vented Crawlspaces as Mold Amplification and Delivery Systems? Measured Performance and a Dry Alternative. ASHRAE.org. Retrieved from http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/

pdfs/ASHRAE_IAQ_Paper.pdf

Dastur, C., Davis, B. (2005) Closed Crawl Spaces Do Double Duty. Home Energy. Retrieved from http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/

pdfs/Home%20Energy%20January%202005_low%20res2.pdf

Janesky, L. (2010) Crawl Space Science - What to Have Done... and Why. Seymore, CT: Basement Systems