heavy equipment near an unfinished building - The Most Common Types of House Foundations Explained

Every house needs a foundation. Foundations serve the essential functions of keeping the home secure and stable, insulating it and protecting it from moisture.

Basements allow homeowners to expand their living space, add value and increase utility bill savings. However, they are susceptible to water damage and are more expensive to repair than other types of home foundations.

Concrete Slab Foundation

The concrete slab foundation, also known as a flat slab or monolithic slab, is the simplest type of house foundation. It consists of a single slab of concrete poured directly on the ground. It requires little construction time and no formwork to build. It is a popular choice for homes in warmer climates, where the soil doesn’t freeze and shift the foundation and home walls.

Slab foundations exploded in popularity during the building boom that followed World War II, as builders saw that they were faster and cheaper than framing a floor with posts, beams, joists and sheathing. They are ideal for flat lots with shallow bedrock that can’t be excavated to create a deep foundation.

While slab foundations have their benefits, they can pose challenges in cold climates where the ground freezes and expands. This movement can cause the slab to shift, crack and sink in the winter. This is why it’s important to choose the right soil for a foundation, even if you prefer a slab foundation.

A slab foundation also has the disadvantage of having no space for plumbing, electrical wires and storage beneath the house. These utilities must be run from above, which can add to construction costs. And while a slab foundation may last 50 years or more with minimal maintenance, its lifespan can be reduced by leaking water, soil changes and tree roots that move underneath the concrete.

In addition, a slab foundation isn’t as strong as other types of house foundations. The load-bearing soil must be solid, and if the concrete slab doesn’t sit on a bed of gravel, sand or crushed stone to promote drainage and prevent water from pooling in one area, it can crack and sink over time.

The best way to avoid problems with a slab foundation is to choose the right soil for your foundation, and have it tested by a professional. A soil test will determine the quality of your foundational soil, including its moisture content and compaction. It will also show whether the soil is prone to shifting and upheaval, which can lead to sagging ceilings, bowed walls and cracked exterior and interior walls. It will also indicate whether your site is prone to termites or freeze and thaw cycles that can weaken the foundation. If the results of your soil test are not favorable, consider a basement or stem wall foundation instead.

Crawl Space Foundation

Your house doesn’t stand by itself — it’s supported by a foundation. Yet, when most people think about a new home construction, they’re often more focused on big-ticket items and value-added amenities than the foundation beneath it all. That’s why it’s so important to consider the foundation type when deciding what to build.

According to a 2018 analysis by NAHB (National Association of Home Builders), crawl space foundations are the most popular type of foundation. That’s because they’re ideal for warm and dry climates, sloped lots that allow water to flow away from a structure, and homes that will be built on the ground level or above.

Crawl space foundations consist of exterior concrete walls that elevate the bottom of a home 18 inches or more above the ground. This gives a home more room to operate its mechanical systems and access for maintenance work. However, crawl spaces also make a home more vulnerable to leaks and mold.

To construct a crawl space foundation, contractors dig trenches that extend below the frost line, which keeps frost from damaging the walls of a structure. Next, builders install footings that transfer a home’s load to the ground and create a concrete slab on top of those footings.

After a concrete foundation is poured, contractors usually put down a layer of rock and sand for drainage and install a vapor barrier to prevent moisture problems. Then, they construct the rest of the crawl space, which can include a concrete floor or a dirt floor that’s covered with a vapor barrier and vents.

If the homeowner decides to turn the crawl space into a living area, the contractor will build a ceiling to provide support and protection from the elements. A vented crawl space will be insulated and conditioned for additional comfort, while a un-insulated or vapor-barrier-covered crawl space will be left open for storage or to allow utility lines to be easily accessible.

If a crawl space foundation is used to support a home in a flood plain, a higher-level drainage system should be installed to reduce the risk of flooding. Otherwise, a crawl space foundation could experience differential settling and upward soil expansion that negatively affects the home’s structural integrity. That’s why it’s best to avoid using this type of foundation in flood-prone areas unless a professional is willing to install an elevated drainage system and a flood control dike. To help prevent a flood, homeowners should also install gutters and ensure that their property is properly sloped to direct water away from the structure. Find a licensed foundation specialist near you to prep your land and build the right type of manufactured home foundations for your property. They can also help you understand the pros and cons of each foundation type and give you expert advice to ensure your project is a success.

house floor plan - The Most Common Types of House Foundations Explained
Basement Foundation

The basement foundation is the most common type of house foundation and it allows for a full-size space below the first floor that can be used as living space. Basements can be fully underground, or they can be exposed on one side – a walkout basement – that opens to a patio (or other outdoor area). Basements are the most costly house foundations since they are the most labor-intensive construction choice.

However, basements are durable and resistant to fire and extreme weather, as they’re below ground level. Moreover, basements expand the usable square footage of houses and increase their value. Additionally, basements can be easily insulated and heated, which saves on energy costs.

One drawback to a basement is that it’s below ground, making it susceptible to water damage and leaks. Moreover, basements are also vulnerable to mold and pest infestation. As such, homeowners should regularly inspect their basements for signs of moisture, mold and insect activity.

Another downside to a basement is that it lacks natural light. This can be a deterrent for many homeowners, especially those who plan to use the space as living space. However, homeowners can overcome this by using creative lighting solutions to brighten the space.

The pier and beam foundation is an older style of house foundation that relies on wood piers that support wooden floor joists. It was once a popular choice for house foundations, particularly in the Midwest and Northeast. However, these types of foundations are becoming less popular today due to a variety of reasons.

While pier and beam foundations are easy to install, they aren’t as durable as other foundation options. They’re also prone to moisture and rot. This makes pier and beam foundations an unsuitable option for homes in rainy climates.

The pier and beam foundation requires regular maintenance, including inspections for water leaks, cracks and rot. These kinds of issues can be addressed with the help of a professional.