Slab vs. Crawl Space Foundations: Difference, Pros & Cons

You’ll find slab foundations and crawlspaces in homes across the country. But what’s the difference between the two? Where are they most common? What makes the most sense for your property? And ultimately, how do they do in severe weather?

In the end, the type of foundation you have usually comes down to the style of home and where it’s located.

What is a Crawlspace?

A crawlspace is a small space, not a full basement, underneath a home’s main floor. They’re typically no more than five feet tall. They “lift” the first floor off ground level, raising critical systems like wiring, HVAC systems, and plumbing above potential flood levels—and providing easy access. Because of this, crawlspaces tend to be found in in locations prone to flooding and urban areas.

The Different Types of Crawlspaces

There are two primary types of crawlspace foundations: block-and-base, and pier-and-beam.

A pier-and-beam crawlspace foundation features a continuous, ground-penetrating concrete or masonry beam supporting the entire perimeter of the house.

Conversely, a block-and-base crawlspace foundation have free-standing piers along the perimeter that are used under the middle of the home. There is often non-weight bearing skirting around the perimeter, which can be removed.

Air circulation is important with a crawlspace, and based on location and climate, there are three types of venting:

Actively Vented. In this type of crawlspace, vents and fans make sure air circulates easily. This type is often found in areas where the outside humidity is not very high.
Passively Vented. This crawlspace, common in areas with low humidity and moderate climates, uses natural airflow to help with moisture and air quality.
Conditioned (Encapsulated). This crawlspace is insulated and sealed, often used in places with extreme temperatures and high humidity.

What is a Slab Foundation?

A slab foundation features a concrete pad poured four to eight inches deep, on a level surface, with thicker concrete around the perimeter.

Slab foundations are often found in warmer climates since they can crack if exposed to cold temperatures. Slab foundations often include a layer of crushed gravel or sand, beneath the concrete, to help with drainage.

Pros and Cons of Crawlspaces

Various attributes of each foundation type make them ideal for specific situations. Some pros of crawlspaces:

Actively vented crawlspaces can help cool the area beneath your home.
Conditioned/encapsulated crawlspaces can improve indoor air quality, preventing or minimizing contaminants and allergens in your home.
Conditioned/encapsulated crawlspaces can assist with moisture and temperature control.
They can provide storage space.
They protect utilities (you can easily access plumbing and other pipes).
They’re ideal for sloped lots.

However, there are also cons:

They tend to be more expensive than slabs.
They can require more maintenance and monitoring than slabs to help ensure proper ventilation.
They tend to have a shorter lifespan than slabs.
Actively vented crawlspaces can attract bugs and other pests.
There can be moisture issues, depending on the type you use.
Your living space may become smaller by adding a crawlspace.
Passively vented crawlspaces might not be very effective in reducing moisture in flood-prone areas.

Pros and Cons of Slabs

The various pros and cons of slabs impact what sort of foundation is best for a particular home.

Some positive elements of slabs:

Slabs have a long lifespan.
They’re resistant to mold, mildew, and pest damage.
They’re durable.
They are typically less expensive than crawlspaces.
They’re relatively quick to build and can speed up overall construction.
There’s less risk of flood damage or gas leaking into your property.

Some potential downsides:

Slabs can’t be built on a slope.
There’s no extra space beneath them since they’re built directly on the ground. (Pipes and other elements are often built directly into the slab.)
They can crack.
Pests can enter through the walls since the house is closer to the ground than with a crawlspace.
Heating and cooling units need to be placed in an above-ground space, taking up room.
They can lead to cold floors since the concrete pad sits on the ground.

SERVPRO^® is Here to Help^® with Slab and Crawlspace Cleanup 24/7

Your home is more than just brick and mortar. Your precious memories and irreplaceable materials may be stored in crawlspaces. If your crawlspace, storage area, or slab foundation suffers damage and requires cleanup and restoration after a fire, water damage, or other severe weather event, SERVPRO is here to help make it “Like it never even happened.”