What Is Buying a House on a Concrete Slab?

The foundation that your house is built on can have a major impact on the structural integrity of your home. A slab foundation is made of concrete that is typically 4" to 6" thick in the center. The concrete slab is often placed on a layer of sand for drainage or to act as a cushion.

Houses built on a slab lack crawlspaces, and there is no space under the floor. If you are considering building or buying a home on a concrete slab, there are a number of benefits and drawbacks that need to be considered.

What You Need to Know About Buying a House on a Concrete Slab

Some houses don’t have a basement or crawl space under them but are simply built on a concrete slab—perhaps because the house sits on bedrock or a high water table. The concrete is poured onto the ground all at one time. Some foundations have post-tension cables or are reinforced with steel rods called rebar so that the slab can bear the weight of the house. The house is then constructed on top of this concrete foundation.

Slab foundations are more common in southern states with warm climates, where the ground is less likely to freeze and cause the foundation to crack. Here's a look at the pros and cons that come with a slab foundation.

Advantages of Concrete Slab Foundations

Here are five reasons to select this type of base for a house:

1. Less Time to Dry

It takes less time for a concrete slab to dry. Less downtime means that construction can move along without delay. There is no need to wait the several days it takes for the concrete in a poured basement to cure and dry.

2. Less Risk of Damage from Flooding or Leaking of Gasses

Slab foundations minimize the risk of damage from flooding or the leaking of gas, such as radon, from a basement or crawl space into the house.

3. Protection from Pests

A concrete slab can protect a home from termites or other insects as there are no open spaces underneath the house that provide access to wooden joists or supports insects could chew. Slabs can also be pre-treated with insecticides to be sure they do not nest underneath.1

4. Cost Savings

Cost savings is one of the biggest advantages. In many cases, the home buyer can shave as much as $10,000 off the cost of the house. If it is built on a slab there is no crawl space or basement to budget for.2 This is particularly true when a builder has to carve a basement out of solid rock—a very expensive proposition.

5. Less Steps

Slab homes are often built closer to the ground than homes with basements or crawl spaces, thus reducing the number of steps required to enter the home. Easy access is advantageous for those who are less physically able.

Disadvantages of Concrete Slab Foundations

Despite the advantages of this type of construction, a concrete slab is not for every house site or homeowner. Here are five reasons to consider passing it up:

1. Pests Can Still Enter Through Walls

Although termites and other pests cannot gain access directly beneath the house, they can enter through the walls since the house is typically closer to the ground. This is particularly true if the siding is made of wood and sits on the ground.

2. Ductwork Requires Insulation

Ductwork for heating and air conditioning is usually run through the ground-floor ceiling, which means that it must be heavily insulated to retain the proper temperature.

3. Heating and Cooling Units Use Above-Ground Space

An air-conditioning unit and furnace may also have to be installed on the ground floor, which means that they will take up room that might otherwise be used for other purposes.

4. Slab Cracks

One of the most significant potential disadvantages is if the slab cracks. This can substantially compromise the structural integrity of the house and be difficult and expensive to repair. Among the factors that can result in a slab cracking are tree roots, soil displacement, earthquakes, or frozen ground.

5. Some Consider a Slab House Unattractive

Some people find the lower-to-the-ground look of a slab house unattractive.