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Crawl Spaces in the Home

By Tanner Sagouspe Rise Writer
May 27, 2021

When I was growing up, I remember peaking over my parent's shoulders as they descended into the crawl spaces beneath our home. At one point, I peaked my head beneath the floorboards and examined the dark and eerie area. I never left the entrance of the crawl space and quickly retreated after tangling myself in cobwebs. That moment was both the first and last time I explored the crawl space.

Now, as an adult, thinking back to that crawl space, I am met with another eerie thought: how could they have sealed the crawl space differently?

What Are Crawl Spaces?

Crawl spaces are hollow areas beneath the ground and the first floor of some homes. They have received their name because one enters the one-to-three-foot-high space by crawling. Crawl spaces are popular in the southwestern states but do not fair well in the southeast, often due to the high humidity levels.

Crawl spaces are more than open spaces under the home. They are helpful for housing pumps, ductwork, HRV/ERVs, and even electrical wiring and allow easy access to these features. But don't be fooled because crawl spaces can generate issues when not properly sealed.

StegoCrawl Wall
Starting to Seal on Walls of Crawlspace With StegoCrawl. Photo Credit: Stego

What Are Common Issues With Crawl Spaces?

Crawl spaces are dark and damp, making them the perfect location for hot, humid air to condense into water droplets along cool surfaces. This moisture leads to mold and rot, which directly affects the integrity of your crawl space and, thus, your home. On top of potential structural damage, the release of mold spores into the air can directly affect the home's air quality.

Without proper installation, pests can find their way into your crawl space. The comfortable microclimate beneath the house can create an ideal home. These pests can vary from rats and raccoons to carpenter ants, spiders, and termites. Quite a surprise if you're not expecting it!

Aside from damaging aspects, the residential coding system for crawl spaces will vary depending on the region and can lead to compliance issues when not done correctly. Though the International Residential Codes (IRC) give a baseline for building requirements, local codes can supersede these. Always be sure to check your region's unique code requirements before beginning a project to save yourself time and money with installation.

Why Would New Homes Build Crawl Spaces?

Crawl spaces are a convenient and cost-effective way to house the internal workings of your home that a basement traditionally houses. These inner workings can include but aren't limited to electrical wiring, insulation, and plumbing. Having these located in this space allows you easy access to them if any issues occur.

If your crawl space rests on open earth, adding a vapor barrier will prevent moisture from coming up from the ground into the room. The EPA recommends covering home basements or crawls spaces with dirt floors with a poly-barrier of at least 6-mils thickness to manage home moisture levels. Selecting a high-quality vapor barrier can prevent soil gasses, like methane and radon, from working their way from the soil into the home.

If you're thinking about including a crawl space in your new home, it is essential to remember that every home and climate is different. It is best to consult a local professional to determine if a crawl space is suitable for your home.

Basement Systems Vented Crawl Space CleanSpace
Vented Crawl Space Encapsulated With CleanSpace. Photo Credit: Basement Systems

What Are Vented And Unvented Crawl Spaces?

Crawl spaces in areas with excess moisture traditionally require ventilation. Without ventilation, water vapor can move from the ground into your house and turn your crawl space into a perfect home for fungi, mold, and pests. The growth of these moisture lovers can lead to poor air quality and adverse health effects. That said, the area within a crawl space is cool and damp, and when exposed to hot, humid air, moisture can begin to condense into water droplets. Improperly sealed surfaces can be prone to collect this moisture, resulting in long-term structural damage.

Traditionally, vented crawl spaces were used for moisture and radon control for open-ground crawl spaces. Problems occur when the coolness of the crawl space allows moisture to condense on wood components. The operable vents of the crawl spaces could be closed in the winter months to reduce heat loss, but this requires an extra level of interaction from homeowners.

Unvented crawl spaces have become a preferred option, with certain exceptions typically being flood-prone locations. By correctly encapsulating a basement, you save money on wasted heat, reduce time with vent maintenance, and create a protective layer against moisture.

While unvented, encapsulated crawl spaces are preferred, it is recommended to consult a professional before installation as local build codes may require different standards.

What Is An Encapsulated Crawl Space?

An encapsulated crawl space functions as a closed crawl space, sealing all gaps to the outside. An encapsulated crawl space prevents external air and moisture from entering the crawl space through a protective vapor barrier that lines both the ground and vertical walls. Some companies, like Stego, make vapor barriers specifically for this purpose - namely StegoCrawl. In addition, spray foam can fill pockets around the joist bands and properly insulated perimeter walls.

Installed StegoCrawl. Photo Credit: Stego

Why Should You Encapsulate Your Crawl Space?

By choosing to encapsulate your crawl space, you protect your home from the potential damage caused by moisture and mold. By preventing mold and mildew from growing, you raise the air quality of your home. It can even stop that humid, musty smell that can occur with some unprotected crawl spaces. And if that isn't enough, a properly maintained crawl space can a home's raise value when it is time to sell. So whether it is to prevent water damage and save you money or to up the resale value of the home, crawl space encapsulation may be something to discuss with your local professional.

Perminator WR Meadows
Perminator Crawl Space Vapor Layer. Photo Credit: WR Meadows

Should You Install A Vapor Barrier In Your Crawl Space?

If you don't have a vapor barrier installed in your crawl space, you may be experience issues and not even know. Problems can arise like stale odors entering your home, pest infestation, rotten wood, or standing water beneath your home could be a direct result of your crawl space choices. Installing a vapor barrier in your crawl space comes with numerous benefits. Professionals like Cross Roads Foundation Repair confirm that vapor barriers can help protect against mold and mildew. On top of that, they can improve energy efficiency, pipe preservation, structural protection, and mitigate the risks of wiring exposure to moisture.

Always be sure to consult a local professional before installing a vapor barrier. It is better to have a professionally installed vapor barrier in your crawl space to ensure that common issues, like microtears, are mitigated. Microtears can damage the integrity of the vapor barrier, allowing moisture to enter the opening. This oversight defeats the functionality of the vapor barrier. And, when left unmended, it can fail to protect your crawl space from the issues mentioned earlier.

StegoCrawl Sealing
Air Sealing StegoCrawl Vapor Barrier. Photo Credit: Stego

How Do You Install A Crawl Space Vapor Barrier?

Installing a crawl space vapor barrier is possible to do. Still, most sources recommend having a professional perform the task for you. This level of caution is because adequately encapsulating a crawl space can be tricky.

Aside from needing to level, clean, and dry out the existing crawl space, the installation requires careful measuring and placement of vapor barriers. Being sure to cut a 6-mil or thicker poly-barrier properly to fit the crawl space, including around any columns or inner support piers, and sealing it comes as the trickiest part. The installer must ensure that there is at least a 12-inch overlap of the seams and appropriate sealing tape is applied.

When laying the vapor barrier, you will need to be moving along the surface of the vapor barrier, which can result in microtears. Tears are why it is essential first to clear the crawl space of sharp rocks before laying your vapor barrier. These tears defeat the purpose of the vapor barrier, allowing moisture into the protected area.

Why Insulate A Crawl Space?

Insulating a crawl space will help prevent heat loss through the outer edge of the home's building enclosure and above-grade crawl space wall. Moisture can become a significant problem when insulating, so installing and sealing the crawl space with a vapor barrier is crucial.

When insulating your crawl space walls, you should make sure that you create as few seams as possible and tape those that you do have. Any break in your home's insulative armor is a spot where moisture could enter and begin to mold, mildew, or rot. A homeowner should seal any ventilation to the exterior and fill other visible cracks for the best encapsulation.

When paired with properly installed poly-barriers and insulation, homes with an unvented crawl space can quickly begin saving you money in the form of energy. The US Department of Energy's Building America program found that homes with unvented crawl spaces displayed a 15 percent to 18 percent reduction in home energy consumption over those with conventionally vented crawl spaces. Over time, that adds up, making the initial cost of installation worth it!

How Much Does Crawl Space Encapsulation Cost?

The estimate of installation cost will vary greatly depending on the specifics of the job. These prices will depend on your crawl space's square footage and condition, quality of polyethylene barrier, labor, permits, and additional features, like dehumidifiers or HRV/ERVs. Someone planning to encapsulate their crawl space can anticipate a price-point that ranges between $1,500 and $15,000.

Basement Systems CleanSpace
CleanSpace Vapor Layer. Photo Credit: Basement Systems

There are many ways homeowners can make their property more efficient and improve indoor air quality. One of the most overlooked of these efficiency fixer-uppers is the creepy crawl space that rests out of sight and out of mind. Until now! So, if your home has a crawl space and a vapor barrier, see how well it has withstood the test of time so you can replace or repair it before any issues arise.

And if you're interested in having one of these features added to your home - or a home you plan to build - check with a local professional to choose the best option for your climate.

Disclaimer: This article does not constitute a product endorsement however Rise does reserve the right to recommend relevant products based on the articles content to provide a more comprehensive experience for the reader.Last Modified: 2021-07-23T13:21:40+0000
Tanner Sagouspe

Article by:

Tanner Sagouspe

Tanner Sagouspe has a Masters in Environmental Management and is a Permaculture Designer who promotes tackling the climate crisis at home.