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Crawl Space Vents – The Truth

~ By Jesse Waltz, Professional Engineer

Crawl space vents present a multitude of problems for homeowners. Open crawl space vents prevent controlling moisture under your crawl space due to the constant push/pull of the air throughout your home, also known as the stack effect.

Crawl Space Vents

The soil in your crawl space, regardless of whether the area appears dry, is constantly releasing moisture into the crawl space. Bacteria thrives in moist environments due to poor moisture management. According to the EPA, the key to mold control is moisture control. Because wet surfaces promote mold growth, fixing the water problem can improve your health and prevent additional damage.

Crawl Space Vents – The Studies:

Dominion Virginia Power recommends crawl space encapsulation with a polyethylene vapor barrier to combat crawl space moisture. A study by Advanced Energy shows that crawl space encapsulation is an energy-saving solution that reduces heating and cooling costs by 15 -18 percent annually.

A study by Advanced Energy shows that crawl space encapsulation is an energy-saving solution that reduces heating and cooling costs by 15 -18 percent annually.

This research has also been cited by US Department of Energy, and the results have impacted changes in the 2009 and 2012 International Residential Code (R408.3). A fully encapsulated crawl space (also known as a conditioned crawl space, sealed crawl space, closed crawl space, and unvented crawl space) involves completely sealing the area underneath your home from moisture and water damage. The process also helps homeowners avoid the growth of wood-rotting fungi and mold which can contribute to structural failure and poor indoor air quality.

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Crawl Space Vents and Crawl Space Encapsulation

To maintain a crawl space that is free of pests, insects and bacteria, you have to keep the moisture out. The crawl space must be properly isolated from the ground and humid air. We use CrawlSeal, a 20 mil vapor barrier, throughout the full length of the crawl space. It is placed over the dirt floor and concrete walls to keep moisture from entering the crawl space. The ends are secured to each wall for added durability. The heavy duty reinforced lining has an antimicrobial finish to block mold and mildew growth beneath the liner. To help drain water that may seep up from the ground, a drain mat can be installed under the vapor barrier. Some houses also require a sump pump to purge standing water from the crawl space.


Crawl Space Encapsulation – Before & After

It is important to note that simply laying a plastic liner will not resolve the root issue. However, installing a vapor barrier is one of the best ways to stop moisture and humidity from passing through to your home. The benefits of a conditioned crawl space outnumber the disadvantages of a dirt, vented one. The finished space also makes for a great storage area. If you want a healthier and more energy-efficient home, crawl space encapsulation is a worthy investment that over time will pay for itself. So remember – close your crawl space vents and seal your crawl space!

Get Your Free Homeowner’s Guide!

crawl space vents

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. If your crawl space vents are open, this is also a good resource for what to for regarding problems signs and symptoms.

Request your free crawl space repair inspection and download your own copy of the e-book immediately, as our thanks for putting your trust in JES.

Jesse Waltz

Jesse Waltz

Professional Engineer

Jesse Waltz, a Professional Engineer and a 1985 Virginia Military Institute graduate, is the founder of JES Foundation Repair. JES is a regional foundation repair, crawl space and basement waterproofing company with locations in Virginia Beach, Richmond and Northern Virginia.

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