Skip to Main Content

Crawl Space

Are you wondering whether your future home should have a crawl space? Find out everything you need to know about this type of foundation.

Schedule Free Inspection

About 15% of homes in the U.S. have a crawl space. This type of foundation is known for the hollow space beneath the house that acts as a buffer between the soil and the structure. While crawl spaces have the combined benefits of the basement and concrete slabs, they are not without imperfections. 

Crawl spaces are prone to moisture, which is why homeowners who live in humid areas tend to avoid them. Read on as we take a closer look at crawl spaces, their pros and cons, and how they are built. 

encapsulated crawl space

What Is a Crawl Space? 

Since you cannot stand up straight in a crawl space, it is easy to see how this type of foundation got its name. Unfortunately, unlike basements, crawl spaces are too small to be used as an additional living space. On the other hand, unlike concrete slabs, they do provide some storage room. They also provide a durable base for your home and convenient space for all your utility lines. 

Code Requirements for Crawl Spaces 

Different codes apply to unvented and vented crawl spaces. With a vented crawl space, you need to have a minimum of one square foot of vent for every 500 square feet of crawl space area. Different rules apply if the ground is covered with a 120-mil vapor barrier. According to codes the space between the joists and the ground needs to have outside ventilation. 

When it comes to unvented crawl spaces, these need to have a Class I vapor barrier with overlapping seals. This barrier must go six inches up the wall, while perimeter walls should have air seals. According to the regulations, homeowners need to install a continuously operating exhaust system or provide access to the conditioned air from the living area. Codes also claim that the interior needs to have a fire barrier, for example, a half-inch drywall. 

While in the 1950s, all homes with crawl spaces were built with vents, it has been proven that these openings leave your foundation exposed to outside air, water, moisture, and pests. This is why most contractors today recommend sealing the vents with vent covers and encapsulating the crawl space with a thick vapor barrier. In addition, placing a dehumidifier in the space can ensure better air quality and moisture reduction. 

How Crawl Spaces Are Built 

With a crawl space, the home is elevated 18 inches off the ground. The foundation is made of block walls and concrete footings. Sometimes, the walls are made of a combination of concrete blocks and bricks. 

Inside of the crawl space are wooden pillars, as well as pipes and electric wires. Apart from these fixtures, the crawl space is left rather empty. Of course, owners can always decide to insulate the crawl space. Most crawl spaces have dirt floors because this is a cheaper option than covering the ground with concrete. 

Cost of Building a Crawl Space 

Naturally, the price of a crawl space greatly depends on the size of the home and the quality of materials that are used. Usually, a crawl space for a typical family home costs between $10,000 and $20,000. 

Crawl Space Advantages 

Although crawl spaces can be tricky to build, they have numerous advantages that justify their popularity. 

Durability: Crawl spaces can adapt to all kinds of climates and provide stability during earthquakes. For example, this is not the case with a concrete slab. 

Level ground: It is almost impossible to buy a piece of land that is perfectly level. If you want to build a home on a sloping piece of land, you could do it without much hassle with a crawl space foundation. By varying the lengths of piers, you can easily create a uniform platform. 

Flexibility: Whether the soil on your property is soggy or expansive, a crawl space can be adapted to the situation. This type of foundation also responds better to hydrostatic pressure. 

Usable space: Crawl spaces are great for running your plumbing lines and electrical wires through. If you decide to encapsulate this area and keep it clean and dry, you can even use it for storage. Although crawl spaces are not as big as basements and you can’t place some large items down there, you can use it for smaller ones. 

Crawl Space Disadvantages 

Just like any other type of foundation, crawl spaces also have their disadvantages. 

Reduced energy efficiency: Since the area beneath your home is completely open, cold air can circulate freely through it. This means you will have to run the heater for a long time to warm up the crawl space. Fortunately, with proper insulation, you can cut down on costs. 

Pest infestation: Pests such as mice and rats are often drawn to moist and dark places, such as the crawl space. They could nest there and breed without being disturbed. Of course, they will damage everything that gets in their way, so they can even compromise the stability of your home. 

Moisture issues: The biggest problem with the crawl space is moisture. Since the air circulates freely, 

the interior of the crawl space will become damp, which will lead to mold growth, rot, and muggy air. This is why it is important to invest in proper waterproofing measures. 

When to opt for a Crawl Space Foundation 

If you cannot decide between a concrete slab and a crawl space, opt for the latter if you live in an area where floods and earthquakes often occur. Also, go with a crawl space if you wish to build a home on a sloped piece of land. 

If you wish to encapsulate your crawl space or just check whether everything is in order in this space beneath your home, contact the experts at AFS. After you schedule a free inspection, you can find out which waterproofing methods will suit you the most. 

Publish Date:

Last Modified Date:

AFS Coverage Map


Birmingham, AL

130 Interstate Commerce Crt. Bldg. 100 & 200
Alabaster, AL 35007

Chattanooga, TN

214 Industrial Park Dr.
Soddy-Daisy, TN 37379

Columbus, GA

2701 Opelika Road
Phenix City, AL 36870

Huntsville, AL

2415 Jordan Road
Huntsville, AL 35811

Knoxville, TN

3028 E Governor John Sevier Highway
Knoxville, TN 37914

Mobile, AL / Biloxi, MS

3131 Hamilton Blvd.
Theodore, AL 36582

Montgomery, AL

445 Dexter Avenue, Suite 4050
Montgomery, AL 36104

Nashville, TN

1519 Heil Quaker Blvd.
LaVergne, TN 37086