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Evolution of Crawlspace Building Practices: From Exposed Piers to Encapsulation

Tips from a Crawlspace Industry Expert

Most of you are aware of what a crawlspace is as it relates to a residential structure. Just like me, you have probably been in a few. The definition of a crawlspace, according to Merriam-Webster, is “a shallow unfinished space beneath the first floor or under the roof of a building, especially for access to plumbing or wiring.”

I thought it would be interesting to take a brief look at how building practices in regard to crawlspaces have evolved in the last 75 years. Crawlspaces are not just shallow spaces under the home anymore. They are built in many different heights, widths, and combinations. Additionally, we know there is more than plumbing and wiring found in crawlspaces today. You can find such things as HVAC ductwork, hot water heaters, pool pumps, sump pumps, lawn mowers, and all kinds of items the homeowner may be storing there.

It is also not uncommon to find other things in a crawlspace that we would rather not find. Of course, I’m referring to insects, rodents, and wild animals. And let’s not forget excessive moisture, which supports mold, mildew, and wood-decaying fungal growth. Let’s explore how crawlspace structures have evolved to deter these unpleasant findings.

Early Crawlspace Building Practices

Early building practices for residential houses featured a simple open crawlspace, with the structure rested on exposed support piers. This type of construction was not very energy-efficient at all, and while it was thought to help keep the structure drier and cooler in the summer, the house was very difficult to heat in the winter. Back to the drawing board!

The Rise of Crawlspace Foundation Vents

In the 1940s, building technology was improving. Innovations in house insulation along with new heating and cooling systems for houses were becoming popular to increase the comfort for the homeowner. Building a house with a foundation wall that enclosed the crawlspace and piers became more and more commonplace. But with the crawlspace encompassed by a foundation wall, the ventilation of the crawlspace became a concern. The solution? Foundation vent openings, installed in the foundation wall and spaced out around the house to allow the home to breathe. This type of crawlspace construction is still accepted by standard building codes today.

Benefits of a Closed Crawlspace

In the late 1900s and into the early 2000s, building practices started to evolve again. More focus on energy-efficient structures became very important. Out of that research, we learned that a closed, dry, well-insulated, and conditioned crawlspace does in fact make the house more energy-efficient, and it offers two important additional benefits: it helps reduce the potential for insect infestations and the potential for wood-decaying fungal growth.

What Is a Closed Crawlspace?

A closed crawlspace is where the crawlspace is still encompassed by a foundation wall but no foundation vent openings are installed. The inside walls of the crawlspace are sealed and insulated in place of the traditional between-the-joist insulation method. Some contractors choose to still insulate between the joists, and both methods are acceptable by code. The ground must be 100% covered with a moisture barrier of at least 6 mm and extended up the foundation wall a minimum of 6 inches then attached and sealed to the foundation wall. All overlapping seams in the moisture barrier must be tightly sealed and air in the crawlspace must be conditioned by a mechanical source, usually a dehumidifier. This option is becoming more and more popular with building contractors and homeowners.

If the house currently has a vented foundation crawlspace, a variation of the closed crawlspace method mentioned above can be applied to convert the vented crawlspace to a closed or encapsulated crawlspace that complies with codes. The same required codes have to be met with one additional requirement, which is to close and seal off the existing foundation wall vent openings.

Call the Crawlspace Experts

Pest control companies are adding this encapsulation service to their portfolio of services to better serve their clients. Other companies, like Your Crawlspace, are supporting the pest control industry with cutting-edge technology, training, and experience in crawlspace moisture remediation.

The Your Crawlspace team has developed patented products specifically for crawlspace moisture barriers and has everything you need to create a sealed crawlspace encapsulation system that’s proven to be effective and efficient. They offer support and training for you and your team whenever you need it and will even go into the field with your team to do one-on-one training.

For more information, visit the Your Crawlspace website at I hope this information is useful and I would love to hear your feedback, questions, or suggestions.

Don Richards ACE, CPI

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