Foundations are integral to building and home construction, and choosing the right type of foundation greatly depends on the area’s soil, climate, and even the homeowner’s storage preferences. Almost all foundations are built partially underground to secure the footings in soil. However, buildings with basements require one step further––or one step deeper.
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What is a basement foundation?
Basement foundations function like standard foundations (without basements): They distribute a building’s weight evenly, secure it into the ground, and keep moisture out. The main difference is, standard foundation walls are built partially underground and therefore don’t create livable space below the first level. By contrast, basement foundation walls are fully submerged to make space for an underground floor.
Basement foundations take longer to build than standard foundations. Heavy-duty equipment like excavators, rollers, cranes, and forklifts are often needed to dig and reposition soil. And sometimes drills and specialized hammers are required to break up large rocks obstructing the area. Despite their difference in depth, the methods for building standard and basement foundation walls are the same. They use either poured concrete, block concrete, or precast concrete slabs.
There are several types of basement foundations to choose from, depending on topography and personal preference.
3 Types of basement foundations
Full basement foundations
Full basement foundations cover the building’s perimeter, and the entire basement floor is submerged on a level plane. Full basements can either be finished or unfinished; finished basements are insulated and installed with drywall and flooring, providing living and storage space. Unfinished basements are usually not insulated and their walls and floors are left bare.
Full basements lack windows, but if they have them, they’ll be small and emerge at ground level. Besides being the most expensive foundation, full basements are more susceptible to mold and moisture than the other types.
Daylight basement foundations
Daylight basements are built when the building rests on a slope: One side of the basement is fully submerged, while the other is aboveground. Daylight basements are ideal for homeowners who want patios or basement-accessible entrances, also called walkout basements. As their name suggests, daylight basements let in some natural light and aren’t as susceptible to mold or moisture.
Crawl space foundations
Though technically not a basement, crawl spaces are important to consider when choosing a foundation. Crawl space foundations are elevated several feet off footings, leaving a small protected space (usually three or four feet) between the ground and base of the building. The foundation walls are built partially underground and shorter than basement foundation walls, making crawl spaces a happy medium between standard foundations and basement foundations. They are deeper than standard foundations and more shallow than basements.
Though they eliminate the possibility of having a finished basement, crawl spaces provide easier access to piping or plumbing than standard foundations. They also encourage more airflow underneath the building, which helps keep things cool in warmer climates. Crawl spaces are the least expensive type of basement foundation since they don’t require as much excavation.
Advantages of basement foundations
- Boost home values. Basements provide additional living and storage space, which can maximize square footage without altering the building’s appearance.
- Energy-efficient. Because they’re not exposed to the elements, insulated basements use less energy to heat or cool rooms. This helps cut costs and is more environmentally friendly.
- Provide shelter. In a tornado or hurricane, it’s best to stay as close to the ground as possible. Basements can provide that secure space.
Disadvantages of basement foundations
- Risk of moisture and mold. Depending on their climate, basements are often exposed to more water than standard foundations. It’s important to have a sump pump installed to insulate water pipes during floods and keep the foundation crack-free to ward off moisture.
- More expensive. Compared to standard foundations, basements require more excavation, which can prolong construction times and raise costs.
- Less sunlight. Basement foundations lack natural light, which can be a deterrent to some homeowners. This is especially true if the basement is intended to be a high-traffic area. However, there are many options for indoor lighting, and getting creative with light is one of the trade-offs in having a basement.
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