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What Is a Slab Foundation?: Pros and Cons

Side of a slab foundation.

Slab foundations are among the sturdiest and most popular types of foundations in the Southeast United States. They provide a solid base for homes and are naturally resistant to the region’s humid and often warm weather.

Still, slabs come with their own set of challenges, most of which can be overcome with the right tools. Let’s take a look at how slab foundations are built and explore their pros and cons.

Defining a Slab Foundation 

Concrete in a backyard.

A slab foundation is a structure found at the base of a building. With its internal steel rod supports and concrete structure, a slab foundation provides a ton of strength and stability to a building.

This type of foundation is built nearly level with the ground (professionals sometimes call them “slab-on-grade” foundations to reflect this) and tend to be four to eight inches thick. Its edges may be slightly thicker than the rest of the structure to add strength to the perimeter.

During construction, contractors pour a slab all at one time rather than in layers. After the concrete cures, a building can be constructed on top of it.

This type of foundation is mostly used in parts of the county with warmer climates and places close to sea level, like the coasts of Florida and Alabama. However, you can find these foundations all over the country.

How is a Slab Foundation Built?

When a slab foundation is being built, contractors will follow these steps: 

  • The contractors will determine the ideal width of the foundation. it should have the same dimensions as the structure that will sit on top of it. 
  • Builders will excavate soil and remove sticks, rocks, and roots to prepare the site for construction. 
  • Afterward, the slab area is framed with pre-made 2×12-inch boards as a sort of skeleton structure. 
  • Builders will dig foundation footings along the inside of the form, about three feet from the edge. 
  • Next, the soil will be compacted with a tamper. 
  • Builders will put rebar stakes into the trenches and tie them together, covering the whole area.
  • Once rebar stakes are in place, contractors will the concrete, pour it into the footers, and leave it to dry. 

This process is intensive and tends to take a while. Never attempt to build a slab foundation on your own, no matter how small. Without the proper tools or training, the foundation could be faulty and you could get hurt.

Pros of a Slab Foundation 

There are many reasons why a slab foundation benefits a home in the long run. Here’s a list of the best benefits:

More Economical

Since it doesn’t require so much construction material and it can be quickly built, the slab foundation is cheaper than other types of foundations. In addition, it requires very little maintenance to stay in a good shape. 

Easier to Construct

As mentioned, a slab foundation can be quickly constructed. This is because there is little excavation involved and builders use poured concrete that cures in a matter of days. Since contractors won’t stop the construction work to wait for the foundation to cure, there are no delays in the process, and homes are built much faster. 

Reduced Mold Growth and Pest Infestations

Mold clusters in a crawl space.

Mold growth and pest infestations are common in homes with other foundation types, such as basements or crawl spaces, where moisture and water can easily infiltrate, unlike slab foundations.

Pests can damage support beams and leave feces throughout the area. Mold spores contaminate the air in the home and may cause health problems.

With a slab foundation, you rarely (if ever) have to worry about these issues. Concrete slabs don’t have openings or empty space underneath, so it doesn’t give room for pests and mold to secretly thrive below your feet. 

Incredibly Durable

If high-quality materials are used and no mistakes are made during the construction, a slab foundation can last between 50 to 100 years. Concrete is one of the longest lasting construction materials out there!

Cons of Slab Foundations 

Of course, concrete slabs aren’t perfect. They also have downsides to be aware of: 

Foundation Cracks

Cracked concrete slab.

Unfortunately, concrete slab foundations can crack over time. Many factors can cause cracking, such as soil erosion, frozen ground, earthquakes, and tree roots. These cracks can compromise the structural integrity of your home. 

Lack of Storage Space

While homeowners who have basements and crawl spaces can use them to store things, homes with slab foundations do not have any storage space. It’s something to consider when looking for your perfect home. 

Foundation Settlement

Since slab foundations sit directly on the ground, they are more susceptible to settlement when the soil shifts. Sometimes, this happens due to heavy rain that erodes the soil surrounding the foundation.

Other times, it is due to dry periods making the soil dry, weak, and brittle. No matter how it happens, foundation settlement may lead to other issues in your home like wall cracks or uneven floors.

Work With AFS to Protect Your Slab Foundation

AFS work truck.

Slab foundations are popular for a reason. They’re easier to build, tend to last longer than other foundations, and keep your home stable.

However, if you have a problem with your slab foundation, don’t hesitate to call AFS Foundation Repair & Waterproofing Specialists. We serve homeowners in Tennessee, Alabama, Mississippi, Florida, Kentucky, and Georgia. Schedule a free inspection today to get started!

Slab Foundation FAQs

With rebar in place, the slab would be able to handle more pressure, making cracks a lot less likely. Still, it doesn’t stop the slab from settling. Even if the slab does not crack, the house will still sink if there are soil issues in your yard.

When your slab foundation settles, you may see cracks along the walls, both inside and outside. You might also see one side of the concrete slab sticking up more than the other, indicating movement.

Unfortunately, existing slab foundations cannot be waterproofed. Your home’s ductwork and pipes are under the slab, so any kind of tampering with the foundation can damage your HVACs ductwork and the drainage system around your home.

Related Resources

Ted Dryce

Ted Dryce

Content Writer

Ted is an SEO Content Writer who has been with Groundworks since 2021. He’s covered home repair topics ranging from crawl space encapsulation to regional soil conditions. When he’s not working, Ted is performing improv comedy and working on his own creative projects.

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