Crawl Space Foundation: Is It Better Than A Slab Foundation

Crawl Space Foundation: Is It Better Than A Slab Foundation

Crawl space foundations are becoming an increasingly popular choice for homeowners and builders. They offer a number of advantages over slab foundations, including improved accessibility, better ventilation, and reduced risk of moisture damage.


What Is A Crawl Space Foundation?

A crawl space foundation is a type of foundation in which the floor of the building is elevated above the ground, typically by about 18 inches to 3 feet. This creates a crawl space, or an area that is tall enough for a person to crawl through, but not tall enough to stand. This space is typically used for access to the plumbing, electrical, and HVAC systems located under the home, and for ventilation.

Crawl space foundations are typically constructed using a combination of concrete footings and walls, and a wooden floor framing system. The walls are typically made of poured concrete, cinder blocks, or pressure-treated lumber. The floor framing system is made of pressure-treated lumber and is designed to support the weight of the house above. A vapor barrier is typically installed on the ground to prevent moisture from entering the crawl space.

What Is A Slab Foundation?

This may be the most common type of foundation. A slab foundation is a type of foundation in which the floor of the building is constructed directly on top of a solid concrete slab. The slab is typically 4 to 6 inches thick and sits directly on the soil. There isn’t any access underneath the slab and all plumbing is built inside it or on top of it.

Slab foundations need to be very level and at least six inches thick in the center and about two feet around the perimeter. Any thinner and the slab foundation won’t be stable so this isn’t a foundation to slack on.

Things To Consider: Slab Foundation Vs Crawl Space

When deciding on whether to build a slab foundation or a crawl space foundation, there are a few things to consider.

Moisture Level

Moisture can also take its toll on foundations. So make sure your team considers this as well. A slab foundation can be slick when moisture seeps through but it is much better than a crawl space foundation for this.
That’s because, in humid areas, crawl space foundations allow mold and other bacteria to grow in the crawl space, not to mention, the mud. No one wants to crawl through the mud to check the plumbing.


Although you can add heat lamps and such under crawl space foundations, it’s a better idea to opt for slab foundations if this is your biggest concern. That’s because the crawl space allows more air to pass through the bottom.
Air and moisture barriers can definitely help with this so if you do get a crawl space foundation, make sure that you install a moisture barrier. This can work as an air barrier in many cases as well.


Let’s face it, price is always a concern. Though crawlspace foundations are considered high-end, they are much more expensive than slab foundations. That’s because you are paying for the slab and then some.
Some contractors know this and won’t charge much extra for the crawlspace if they think it is important. So talk to them beforehand about the differences in prices. You may only have to pay for the extra materials.

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