15 Foundation Terms You Need to Know

When it comes to the foundation of your home, there’s probably a lot you’re not familiar with. It can be hard to make the right decisions if you don’t know enough about the subject. Here are 15 foundation terms that everyone should know when thinking about their foundation.

The first five are the main types of foundations that you find in most homes.

Basement Foundation

As the name suggests, this is a foundation built around a basement. The basement is dug out of the ground and then the foundation is poured beneath that. With basement foundations, the walls provide a majority of the structural support. These walls have footings that go further down below the floor into the ground below. The footings should go at least one foot below the rest of the house. They also need to go one foot below the frost line.

Basement foundations are expensive, but they add a considerable amount of living space to your house, raising its value tremendously.

Crawlspace Stem Walls

A house built on a crawlspace is elevated above the ground by a short distance – usually two or three feet. The walls of the crawlspace serve as the immediate foundation for the house, anchoring it into the ground.

Crawlspaces are popular choices because they allow easy access to plumbing and electrical systems. They also provide a measure of protection against natural concerns like termites or flooding. They can make a house prone to mold and mildew since crawlspaces often trap in moisture. It is crucial to make sure they are ventilated properly.

Concrete Slab Foundation

A concrete slab foundation is a flat, level slab of concrete. It is poured in one piece that stretches the entire length and width of the home. They provide strength and stability, in addition to being much cheaper than other concrete foundation options.

They do have downsides, though. In colder, wetter climates the weather can cause slabs to crack, leading to problems down the line. In addition, plumbing and electrical systems are put in place before the slab is poured around them. This means that any work you have to do on these systems can involve cutting into the slab.

Wood Foundation

Wood almost always provides a cheaper alternative to concrete and is incredibly durable. Wood foundations typically have crawlspaces similar to a stem wall design, but with wood providing the structural support.

These spaces can be insulated to provide just as much protection as concrete. The main problem with wood foundations comes from moisture. They can only be used in dry places where there is almost no water in the soil. Otherwise, the wood will quickly degrade. In general, wood foundations also don’t last quite as long as concrete, although there are some notable exceptions.

Pier and Beam Foundation

Pier and beam foundations are used in areas where the soil is less stable. These areas include coastal areas where it’s common for the ground to shift. A typical foundation won’t work in these areas because the shifting soil will quickly destroy the foundation and, eventually, the house.

Pier and beam foundations consist of long beams driven deep into the ground. In some cases, they go down 15 feet or more, until they reach stable ground that will not shift. Several beams are placed into the ground from all areas of the home. That way the weight of the house is dispersed evenly over a larger distance. Then, the house is placed on top of the beams.

These foundations are expensive and require much more extensive planning and expertise, so they are usually only used when necessary.

Beyond the five major types of foundations, here are some other important terms:

Load Path

The term “load” refers to the weight of the house. It’s vital that this weight is transferred to the strongest parts of the foundation that can handle it. Load path refers to the path of the weight as it travels down the house, the walls and the foundation.


Resistance refers to the strength of the foundation in resisting outside forces that bring pressure. There are two types of resistance that foundation design specialists take into account. Lateral resistance measures the strength of the walls as they resist side-to-side forces such as wind, rain and even earthquakes. These forces also can push up against the bottom of the foundation as well. The foundations’ ability to stand against this is known as uplift resistance. 


When a foundation loses the battle against uplift resistance, the resulting pressures can push it up and out of place. This usually happens in colder areas where freezing water underneath the foundation expands, slowly pushing up against the foundation. After enough time, the foundation is moved upward and out of place. This is just as big a problem as a sagging foundation and can lead to serious problems with the structure.

Water Table

In almost all soil, as you descend deeper you start to encounter water. The point at which you encounter this water is known as the water table. The level of the water table strongly impacts the foundation of your house. In places where the water table is close to the surface, certain types of foundations become more difficult to install. Basements, for example, are almost impossible in places with a higher water table. Lower water tables provide more options.


Joists are horizontal beams that provide structural support to the structure. They connect the house to the foundation. They are also used in ceilings and walls to provide overall support to all areas of the house. When your foundation is weak, your joists will weaken as well, resulting in sagging joists, bending walls and sagging floors. This in turn weakens the foundation even more, creating a downward cycle.


Grade is the angle of the ground. In a perfect world, all houses would be built on level ground. Sadly, this is not the case, and most houses are built on ground that is at least slightly slanted. The stronger the grade, the more challenges a construction project faces. In extreme cases, with extremely steep areas, houses might be built into the side of a steep hill. This has both advantages and disadvantages.


Bowing refers to the bending or sagging of walls. A bowing wall is never good, and almost always indicates a problem with flooring or foundation. In most cases, a bowing wall is not the problem itself, but a symptom of a much more serious problem. This is why a bowing wall should never be taken lightly.

Depending on the problem that’s causing the bowing, a number of solutions might be in order. However, it is impossible to tell without an expert to come in and assess the problem.


Concrete is similar to cement, but there are a few differences. It is a mixture of many materials, cement being one of them. In addition to cement, concrete contains sand, water, small rocks and other fillers. Different types of concrete will contain different amounts of sand and water. There’s really no problem with these variations. However,  if concrete has too much of any one substance it can weaken and lose its integrity quicker.


When a foundation begins to sag, it needs to be lifted as soon as possible. Mudjacking is a process where water and soil are forcibly pushed under a sagging slab. The pressure lifts the slab until it goes back into its desired position. In addition to raising the slab, the soil stays in place and acts as a new bedding for the foundation.

Active Zone

In any area, the top layer of soil is dependent on the outside world. Temperature, weather and other factors will cause the soil to move or shift. This layer of unstable soil is known as the active or seasonal zone. A solid foundation must be built deep enough to go beyond the active zone to the stable layers of ground underneath.

If you want more information, or are ready to talk to someone about your own foundation needs, we can help you. Please reach out and talk to us at Ray Arnold Masonry today. We are ready to apply our 70 years of experience to help you with all your foundation needs.