Why You Should Consider Encapsulating Your Crawl Space

Mariel Loveland
Written by Mariel Loveland
Updated November 10, 2021
Cottage style house in suburban neighborhood
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  • Encapsulating a crawl space can prevent costly home issues

  • Its primary purpose is to keep moisture out of your home’s foundation

  • During the process, a contractor will install a vapor barrier, among other features

  • The average crawl space encapsulation costs $5,500

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When planning a home renovation, encapsulating your crawl space is probably low on your list, if it's even there at all. It’s not like you’re hanging out down there watching TV or hosting game night. But your crawl space is actually one of the most vulnerable places in your home. Encapsulating your crawl space can protect your house from serious (and expensive) issues down the line.

What is Crawl Space Encapsulation?

Encapsulation is just a fancy way to describe wrapping your crawl space in a thin, single-layer plastic liner called a vapor barrier. You can also add other protective features, like a dehumidifier, drainage trench or a specialized liner (e.g. a radon membrane, which helps reduce radon levels in your home). 

Why do it? Most crawl spaces are directly open to the soil—and that includes stuff like mold, animals, insects, weeds, and moisture. Leaving your crawl space unprotected would be like leaving your front door open and exposing your home to the elements. Eventually, the problems that begin in the crawl space extend to your living space. You may find critters in the home, and mold and musty air compromises indoor air quality, too.

Encapsulation often goes hand-in-hand with insulating your crawl space, but they’re not the same. Insulation helps increase your home’s energy efficiency, but it does not create a moisture-tight seal that prevents mold growth. You can have your crawl space insulated and encapsulated at the same time.

Benefits of Crawl Space Encapsulation

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Many homeowners believe the benefits outweigh the cost to encapsulate, especially when considering the repercussions of letting the outdoors in.

Protects Against Mold and Fungus

An open crawl space is a magnet for moisture, which fosters mold and fungus growth. Crawl space encapsulation can help snuff out the problem, and save you from costly and disruptive mold remediation.

Banishes Pesky Pests and Insects

Most of us don’t want to host a dinner party for termites, mice, and other pests—but an open crawl space is the perfect venue. Encapsulation helps prevent critters and creepy crawlies from sneaking up through your floors or finding their way into your walls. Yes, those cute fluffy looking squirrels can really do some damage

Increases Energy Efficiency

Encapsulation helps increase your energy efficiency by reducing energy loss, especially if you use cell foam insulation. It also solves the problem of bitterly frigid floors in the winter. Your bare feet will thank you.

Improves Indoor Air Quality

It may not seem like it, but you actually do breathe the air from your crawl space via ducts, cracks, and other openings. Encapsulation helps improve indoor air quality by preventing mold, pollen, pollution, and other contaminants from entering your home, so you can breathe easier.

Reduces Radon Levels

Radon is a dangerous radioactive gas that’s often found in basements and crawl spaces. Encapsulating your crawl space with a radon membrane can reduce radon levels in your home and eliminate related health issues.

Helps Prevent Structural Damage

Moisture can cause expensive structural damage over time, as can termites and other pests. Sealing up below your home can reduce the risk and also prevent your foundation from sinking.

How Much Does Encapsulation Cost?

The average homeowner will pay about $5,500 to encapsulate their crawl space, but there are a lot of factors that influence price including:

  • The size of your home

  • The condition of the crawl space

  • The thickness of the vapor barrier

  • The number of layers of vapor barrier

  • The type of insulation

  • The inclusion of add-on features (like sump pumps or drains)

  • Whether or not you have to seal vents

If you don’t need anything fancy, you may get by with a cost as low as $1,500. Crawl space encapsulation could cost as much as $15,000 if the area needs significant repairs and a drainage system.

How to Encapsulate a Crawl Space

Encapsulation isn’t considered a DIY job for most, unless you happen to be a highly skilled contractor. Most people hire a professional to ensure the job is done right. While the exact process will differ from space to space, your encapsulation pro will follow these general steps:

  • Install a vapor barrier, leaving no area exposed

  • Install a drainage system to route standing water or moisture in the ground away from your home

  • Secure the vapor barrier, closing every crack, hole and seam

  • Seal your crawl space vents so no outside air can enter the space

  • Condition the space by either installing an exhaust fan, a dehumidifier, or adding ducts so your crawl space receives air from the rest of your HVAC system

This type of job generally takes between one and two days depending on the complexity and size of your crawl space.

Should I Encapsulate My Crawl Space?

Many older homes have crawl spaces with vents, which contrary to popular belief, can actually make a moisture problem worse if left open. It’s generally a good idea for any homeowner who lives in an area with lots of humidity or moisture to encapsulate. It’s also popular among homeowners looking to increase their energy efficiency. 

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