The Crawl Space Argument: Vented vs. Encapsulated

Residential foundations vary widely from one home to another. While some builders prefer basements or slab foundations, others prefer a crawlspace– some homes even have all three!

Despite these preferences, if your home is over a crawl space, you could be subject to a variety of problems— mold, high humidity, and even standing water.

So the question becomes, should I encapsulate my crawl space? Read on to learn the difference between vented and encapsulated and what’s best for your home.

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The Origin of Crawl Space Vents

Old building science advocated crawl space ventilation was the solution to relieve humidity and moisture in homes. This involves installing numerous vented openings to allow circulation through the crawl space.

These vents typically have a fitted covering, usually a wooden, metal or mesh covering. They are sometimes installed to try to prevent infestations from rodents and animals, but cannot prevent small animals and insects, such as spiders, fleas and carpenter ants.

Although it was thought crawl space ventilation would allow a constant supply of fresh air circulating through the crawl space, homeowners found that vents actually bring unwanted moisture into your home and produce unwanted consequences, according to a study done for the Environmental Protection Agency (EPA) by Advanced Energy, a nonprofit energy consulting firm.

Vents Expose Your Crawl Space to Damage

Consider this: During the winter, frigid air fills your crawlspace, making the floor above cold. It also cools your hot water pipes, water heater, furnace and heating ducts. This causes your utilities to work harder in order to keep you warm –wasting energy.

During the summer, hot, humid air enters the crawl space and the earth cools it naturally. This humidity causes condensation on your pipes, wood and cool surfaces. When a crawl space has high moisture levels, it is likely to have high mold counts. This mold can travel up to the living space, which could lead to respiratory problems, such as asthma.

Air Comes From Your Crawl Space

Building professionals say that up to 50 percent of the air you breathe on the first floor of your home is air that came directly from your crawl space. Therefore, whatever is in your crawl space air is in your house, and you are breathing it.

Not only do vented crawl spaces invite moisture and toxic smells into your home, vented crawl spaces have demonstrated 15 percent to 18 percent more energy consumption for heating and cooling, according to a study conducted by the Building America Solution Center.

Also, if a home’s ducts are in a vented crawlspace, energy bills are likely to be higher. Leaks in a duct system allow unconditioned air to be drawn into the air conditioning system, increasing energy costs by 18 percent to 30 percent. Leaky crawlspace ducts can also contribute to indoor humidity levels.

Additionally, allowing moist air in your crawl space can cause damage to your home’s structural integrity. Since moist wood is more likely to rot, it could put your home’s footing at risk.

Should I Encapsulate My Crawl Space with FSM?

Today, crawl space science looks a lot different. To protect your crawl space, a closed or “encapsulated” crawl space is now preferred to an open, or vented crawl space.

Encapsulated crawl spaces are consistently better at controlling moisture that enters from the damp earth or from warm humid air.

Advanced Energy reports that encapsulated crawl spaces also maintain significantly lower levels of relative humidity (RH), or the amount of water vapor present in air. When excessive moisture is eliminated or reduced, your crawl space is less susceptible to wood decay and your home will remain structurally sound for years.

Encapsulating your crawl space also greatly reduces musty smells, reduces allergens, such as mold and dust mites and greatly improves indoor air quality throughout the entire home.

At Foundation Systems of Michigan, we offer a state-of-the-art crawl space sealing solution to increase your home’s energy efficiency and transform your damp, nasty crawl space into a dry, healthy, useable space.

Book your free inspection today to find out the many benefits an encapsulated crawl space can provide.

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Leah Leitow

Content Writer

Leah is a Content Writer for Groundworks with nearly ten years of experience working in the foundation repair industry. Her experience ranges from working with homeowners to find the right solution to training inspectors and staff. In her background as a Michigan journalist, she gained invaluable insight into people's lives throughout our state. Leah lives in metro Detroit with her husband and two sons.