Is Venting the Crawl Space a Good Idea?

open crawl space vent seen from interior

The crawl space is a popular feature in buildings across the U.S. It’s a cheaper alternative to the basement yet offers more function than a slab foundation. Plumbing, ductwork, and electrical systems are all conveniently located inside it. However, it’s prone to moisture and mold problems.

For many years, building codes required crawl spaces to be vented. People didn’t question the logic behind this requirement. However, things started changing in the mid-1980s when building scientists started investigating homes with moisture issues.

Should You Vent Your Crawl Space?

unsealed crawl space vent with brown cover seen from exterior

Crawl space ventilation is one of the most debated questions in the construction industry. Research has shown that venting your crawl space, especially in mixed or hot, humid weather is likely to increase crawl space moisture. Moisture buildup, in turn, instigates other problems within the home.

When warm, moist outside air enters your crawl space through the vents, it condenses or collects, causing your crawl space humidity levels to peak. The outcome is always unpleasant. Mold and mildew will grow, wood will rot, and metal will rust.

These openings also make moisture control difficult as moisture-laden air keeps flowing into the crawl space from the outside. When this air gets inside, it rises into the living space (the stack effect) where it changes the internal conditions. Floors and walls may feel cooler and moisture droplets may form on cooler surfaces.

Looking at the effects outside air has on your crawl space, it best to not leave it vented.

The Impacts of Open Crawl Space Vents

Other than high moisture content, there are many more concerns that arise because of crawl space ventilation. They include:

Wood rot and mold – Humid air enters your cooler crawl space through vents and condenses on the surfaces. The steady increase of moisture in your crawl space creates a great environment for mold and wood rot to thrive and eat away at important structures.

Water in the crawl space – Open vents create an easy pathway for water to leak through. After a rainy day in Florida, you might be left with standing water in your crawl space because of crawl space ventilation.

High energy bills – Crawl space vents bring the outdoor environment into your crawl space. Whether it’s a hot humid day or a cold winter day, your crawl space (and by extension, your floors) will emulate the outdoors. You’ll find yourself continually adjusting the internal conditions and higher energy bills.

Pest infestations – Vents provide an entryway for pests. When these critters come in, they may tear insulation, chew on wooden beams, and contaminate the air with urine and fecal matter.

Sealing Your Vents: The Best Solution

For these reasons, ventilating your crawl space may not be the best thing to do. Seal your vents with vent covers and encapsulate them with a plastic vapor barrier to isolate them from outdoor temperature and moist air.

With this extra protection, your crawl space will be better controlled and protected from moisture. For more information, watch the video from our friends at Groundworks.

Get a Free Crawl Space Inspection With Alpha Foundations

If you are concerned about the condition of your crawl space, get a safe and comprehensive crawl space inspection from Alpha Foundations. With years of experience maintaining and repairing crawl spaces, Alpha Foundations is your local crawl space team—serving homeowners everywhere in Florida since 2002.

We offer a full set of crawl space repair and maintenance services. No matter what you’re experiencing, you can count on us to provide lasting solutions. Do not hesitate to contact us today for a free inspection of your crawl space.

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Ted Dryce

Content Writer

Ted is an SEO Content Writer who has been with Groundworks since 2021. He’s covered home repair topics ranging from crawl space encapsulation to regional soil conditions. When he’s not working, Ted is performing improv comedy and working on his own creative projects.