3 Foundation Types

A foundation is the base of something—the fundamental, first component upon which all else is built. That's why the foundation type you choose for your home, garage, or any other construction project is so important. If you're in the process of constructing a house, choosing between the three major basic foundation types may be one of the most important decisions you're ever going to make.

Basements

A basement with a window letting sunlight in.

Out of the main house foundation types, full and daylight basements are the deepest. A “full” basement is at least six feet high and typically matches the majority of the floor space of the level above it.

Full and daylight basements have structural walls that bear on foundation footings running along the perimeter of the basement. These footings typically extend below the line at which the ground freezes in winter, known as the "frost line."

The term “daylight basement” refers to a variation of a full basement. Here, the foundation is built along a slope and one or more of the foundation sides are fully embedded into the ground. As the slope descends, on applicable sides the foundation is exposed, allowing for large windows and doors so daylight can enter the space.

While older homes with basements of this sort commonly are made of stone walls and are typically shorter in height, more modern homes with this foundation are made of poured concrete or mortared concrete block.

Basement Advantages

This type of foundation has a range of benefits associated with it. First, it gives homeowners the power to convert the area to additional living space within their home. Finishing a basement can nearly double the amount of living space in some homes.

Basement Disadvantages

While this foundation type tends to be the most highly desired, there are some associated disadvantages. First, some basements are prone to flooding during heavy rain. Additionally, basements are the most expensive type of foundation to construct.

Crawlspaces

A man in a crawlspace looking with a flashlight and dust mask.

A crawlspace foundation creates a shallow opening beneath the house. This is made of short foundation walls that usually stand on footings. The name of this foundation type comes from the fact that since the space is so short, you have to crawl through it rather than walk. These foundation types are typically no more than four feet tall.

Crawlspaces are typically unheated and they often have ventilation via small vents that penetrate the foundation walls. Similar to full basements, this foundation is usually made with poured concrete or mortar concrete block.

A particular type of crawlspace, pier and beam foundations are often considered outdated, although they were very common in homes built before 1960. With this type of foundation, concrete piles or wooden pillars are driven into the ground at certain intervals.

The wooden joists of the house then sit upon these piers, which will keep the home off the ground. A concrete strip is normally formed around the perimeter of the house to prevent water from entering. Over the years, however, water will begin to get inside, causing problems with dampness for many pier and beam houses.

The most important thing for keeping your foundation in good condition is to ensure that drainage is sufficient. Water accumulation in the crawl space can cause the soil under the property to expand, resulting in serious problems.

Crawlspace Advantages

This type of foundation has several advantages. Crawlspaces provide access to plumbing pipes and other infrastructure under the home, which makes it easier to repair problems. This type of foundation is also more affordable, as it requires less excavation and less material to be built.

Crawlspace Disadvantages

One major disadvantage of this foundation type is that it doesn’t provide any additional living space as a basement will.

Concrete Slabs

The concrete slab foundation of a house.

The most common foundation used today is a solid slab of concrete. Concrete is a very strong, man-made material that's highly long-lasting and durable. This type of foundation is often referred to simply as a "slab." This type of foundation became common during the 1950s when concrete slabs were found to be a fairly quick and easy construction technique.

To make a concrete slab, a frame is first constructed from wood. When wet concrete is poured directly inside the frame, the wood holds it in place while it dries to form the slab. Metal reinforcements are typically added to strengthen the concrete. Concrete slabs are categorized into different types that determine the strength of the concrete and how much reinforcement it receives during construction.

While concrete is perceived as being very strong, it has some weaknesses. In very cold temperatures, water can penetrate the concrete. The water eventually freezes and causes cracks to form. Look for signs of damage after cold and extreme winter weather. The quicker you repair the damage, the easier it will be to fix your foundation problems. Slabs help prevent water from collecting under buildings, which is one strong benefit of using this foundation type.

Concrete Slab Advantages

This type of foundation is usually less expensive than its alternatives, which is a big advantage. This type of foundation can also offer better protection against termite infestation, which is more popular in warmer climates (where this foundation tends to exist most).

Concrete Slab Disadvantages

There is a recognized downside of slab foundations. In this construction method, water supply and drainage pipes are encased in the concrete. Should there be a problem with pipes in a home with this foundation, the concrete slab has to be cut into in order to gain access to the pipes.

All foundations should be sturdy, should act as a barrier to the outdoors, and should keep out groundwater. All of these do just that, so finding the best foundation type for you depends on the needs of your home and family.