8 Most Common House Foundation Types To Consider

Choosing the best foundation for your needs is the real trick. The most important things to keep in mind are budget, long-term use and site considerations.

The home’s foundation can be one of the most expensive aspects of a project. A slab-on-grade foundation may get the project off to a great start without a massive price tag, while a full basement will cost much more in time and labor but provide more flexibility for the homeowner in the long run.

You also only get one chance to build a house, so it’s important to consider the long-term use of the property. If it’s likely to be a “forever home,” the expense of a full basement may be worth it. However, if it’s an inexpensive home that the homeowner plans to live in and then rent or sell in a few years, a slab variation or crawl space may be best.

Finally, keep site considerations in mind. Some terrain won’t allow for a full basement, while other sites may require deeply-dug footings or flood provisions. In these cases, builders will likely have to consult an engineer to decide which foundation is best for the home.

The foundation of a house is crucial for several reasons, serving as the bedrock upon which the entire structure stands. It provides stability, ensuring that the house remains upright and secure, even under adverse conditions such as strong winds, earthquakes or heavy rainfall. A well-built foundation also helps distribute the weight of the house evenly, preventing uneven settling, which can cause structural issues over time. Additionally, the foundation acts as a barrier against moisture, protecting the home from potential water damage and mold growth. By maintaining a solid and durable foundation, homeowners can ensure the longevity and safety of their property.

Choosing the right foundation for your house is a critical decision that impacts the structural integrity, longevity and overall safety of your home. Several factors must be taken into account to ensure that the foundation you select meets the specific needs of your property and the conditions of the building site. Here are the key items to consider:

• Soil type: The type of soil on your property greatly influences the choice of foundation. Different soils have varying load-bearing capacities and drainage characteristics, which can affect the foundation’s stability and durability.
• Climate: Climate conditions, including temperature fluctuations, precipitation levels and potential natural disasters like earthquakes or floods, should be considered. Certain foundations perform better in specific climates and can provide better protection against environmental factors.
• Water table level: The water table level in your area can impact the type of foundation suitable for your home. High water tables may require special waterproofing measures or foundation types that are less susceptible to water damage.
• Budget: The cost of constructing a foundation varies depending on the type and complexity of the design. Your budget will play a significant role in determining which foundation type is feasible for your project, balancing cost with the desired durability and performance.
• Local building codes: Building codes and regulations vary by location and must be adhered to when selecting a foundation. These codes ensure that the foundation meets safety standards and is suitable for the local conditions.
• Future plans: Consider any future plans for the property, such as potential expansions or additional structures. The foundation should be able to accommodate these changes without compromising the integrity of the home.

As the name suggests, a poured concrete slab is simply an 8-inch-thick, flat section of concrete that is poured using wood forms. The forms hold the wet concrete in place until it dries. Slabs typically contain rebar (metal rods wired together to create strength), but they may not have footings (thick sections of concrete under load-bearing walls.

Pros

In general, poured concrete slabs are affordable and easy to install. They don’t require a lot of excavation or materials, and they can support quite a bit of weight. They’re especially popular in areas of the country like the south and southwest, where issues like the ground freezing and pushing the slab up isn’t a concern.

Cons

Poured concrete slabs aren’t as strong as some other foundation types as they typically don’t have footings to disperse the weight of the building. Also, if there are utilities or anything mechanical under the slab, any subsequent repairs will require you to break up the slab or excavate underneath.

A crawl space is a type of foundation with short walls (typically masonry) along the perimeter and footings underneath the center of the home. This creates a space below your abode with a dirt floor and just a few feet of clearance between the bottom of the house and the ground. These foundations have ventilation to prevent moisture build-up.

Pros

Crawl space foundations can be the best option in rocky soil on sloped ground, especially in areas where freezing is a concern. These foundations don’t require nearly as much excavation as a slab, making them relatively affordable.

Cons

Crawl spaces are unfinished and unconditioned. This can create pest control issues like termites or rodents, and if the area is not ventilated properly, moisture and mold can grow.

When we think of foundations, concrete may be the first material that comes to mind. But there are actually options compromised primarily of wood, and while this might seem impractical, there are some benefits. Traditional wood foundations were made with materials like cedar, redwood and cypress. However, today’s builders use pressure-treated lumber for its relative affordability and availability.

Pros

Wood foundations are very easy to build. They require simple construction techniques and relatively entry-level tools. They’re also ready to build upon as soon as they’re constructed, as there isn’t any drying time to deal with. They also require very little excavation, which makes these foundations ideal for sheds and very small buildings.

Cons

Wood foundations can’t support nearly as much weight as concrete foundations. Also, they do typically require some rot-resistant barrier between the foundation and the ground, such as concrete blocks, pavers, or gravel. And, as time goes on, even pressure-treated lumber will begin to degrade and attract pests.

Slab-on-grade foundations are heavy-duty concrete slabs with footings dug into the ground under the slab. They’re typically reinforced with rebar, and their wide footings disperse the weight of the building above. Concrete block walls can be built on top of the slab to create a basement or crawl space, or the builder can frame the main floor right on top of the slab.

Pros

Slab-on-grade foundations are much stronger than poured concrete foundations, allowing them to carry the weight of a larger structure. The wide footings spread the weight out while also locking the foundation into place, making them a suitable option for cold weather regions where frozen ground can cause heaving. And while these foundations do require more excavation than poured slabs, they’re still relatively affordable.

Cons

Slab-on-grade foundations are affordable, but they’re more expensive and require more time than a poured slab. Also, if any of the pipes or mechanicals are under the slab, the repairer will have to break up the slab or cut the utility and reroute it.

Full basement foundations consist of deeply-dug footings, walls that allow for standing room and a concrete slab. Standard options are buried below grade with small windows at ground level, while others have at least one wall above grade (known as daylight foundations). They can be finished to add usable space to the home, such as a playroom or family room, or left unfinished and used as storage.

Pros

Full basements are all about flexibility. They can be used for workshops, entertainment spaces, storage or even wine cellars. They’re generally easy to condition, as the masonry surfaces will stay cool in the summer and retain heat in the winter (once heated). And since their footings are dug so deeply, full basements are very strong and stable.

Cons

These basements are expensive. The excavation and formwork required are extensive, meaning increased labor costs. Additionally, these basements required the most concrete, driving up materials costs. They also take the longest to pour and cure before building upon.

Admittedly, stone foundations aren’t nearly as popular as they once were. Until the widespread use of concrete, however, folks would pull field stones from the ground around their property and pile them up to form walls. They may have been dry-stacked (with no mortar) or mortared in place.

Pros

Stone foundations are incredibly traditional, and many folks enjoy the classic look. In the past, this option was rather inexpensive to build as the homeowner typically pulled the stones from their own property. Many of these foundations still exist, proving their durability over time.

Cons

Very few jurisdictions will approve a traditional stone foundation these days. Also, since stones are naturally irregular, gaps and holes may exist where rodents and pests can enter the basement. Despite the thermal mass of large boulders, these foundations tend to insulate poorly.

Insulated concrete forms, or ICFs, are a modern approach to foundation building. These foundations consist of forms made from extruded polystyrene (think styrofoam) that interlock together like children’s building blocks. These forms are light as they have a gap between the two foam panels. Once the panels are place, the builder fills the resulting space with concrete.

Pros

ICFs are easy to install, and they’re actually stronger than traditional poured concrete walls. Also, they’re excellent insulators, retaining heat in the winter and keeping cool in the summer. The foam also can act as a vapor barrier, preventing moisture from penetrating the masonry walls.

Cons

The foam blocks that make up an insulated concrete form foundation are expensive. Moreover they require footings, and since most folks intend to use these types of foundations for basements, they need a slab as well. The costs add up, but this option may still be worth it to some homeowners.

Pier foundations are somewhat similar to crawl spaces in that they hold the home up from an unfinished surface underneath. However, unlike crawl spaces, these foundations don’t have masonry perimeter walls. Instead, they have deeply-dug footings at load-bearing points under the house. There are generally heavy-duty timbers that extend from the footings to the home, and this design helps keep the home dry and safe in coastal areas where flooding is common.

Pros

The overwhelming benefit of pier foundations is that they can resist flood waters better than other foundation types. Additionally, they can be the most practical option in unstable soil, as the builder can dig the footings as deeply as necessary to reach stable ground. This allows builders to construct homes in areas where it would otherwise be impossible.

Cons

Pier foundations require the planning and oversight of an engineer. The footings need to be sized properly, and the correct specifications for any hardware used is extremely important. For this reason, despite seeming like a rather sparse design, these foundations can be extremely expensive. Also, the wooden posts used in the construction can degrade over time and be susceptible to pests.