House Foundations 101
Types of House Foundations
A full basement foundation begins with a hole of at least eight feet deep to accommodate an underground living space whose floor space matches most or all of the home’s ground level. You’ll place structural foundation walls on concrete footings that run the perimeter of the basement. You’ll then pour beams, erect foundation walls, and pour a cement slab inside the walls.
The obvious advantage of a basement foundation is the extra living space it can provide; in fact, it can double the home’s square footage if homeowners decide to finish it. They can be heated or air-conditioned with the rest of the house.
A basement is the most expensive foundation type, and unless you’re building a daylight basement—a basement built on a hillside that opens to the daylight on at least one side—this the space created by this type of foundation can feel cave-like, as it lacks natural light. For homes built on a slope, the daylight basement, which has at least one side embedded in the ground from floor to ceiling, can be a nice alternative to a full basement foundation, even allowing a separate entrance to the home.
Crawlspace Stem Walls :
Short foundation walls on concrete footings, or stem walls, form the foundations of houses with crawlspaces. They form a space that’s exactly as it sounds: a slightly elevated space below a house through which you can crawl.
A major advantage of crawlspace foundations is protection of the home. By lifting the base of the house, its walls are protected from flooding and other environmental hazards. The space allows easy access to plumbing, wiring and other mechanical systems.
While crawlspace foundations are more resistant to termites because of their elevation from the ground, they are prone to mold and mildew because of the moisture that can accumulate below them. While they’re a less expensive option than a basement, crawlspace foundations require maintenance: homeowners will need to make sure below-ground walls are free from cracks, check for leaks around plumbing components, and install vapor barriers to keep it dry.
Pier and Beam:
With pier and beam construction the home is built on horizontal beams that rest on top of piers that connect to the ground. These homes often have a “crawl space” underneath them where you can access the plumbing and other mechanicals. You’ll need to bring a structural engineer on board to oversee a project since they’ll need to do a soil analysis to make sure you’re building the structure in the right conditions.
They work in the same way an ocean pier does by fixing long pillars—often over 15 yards long to reach solid ground—into the deepest layers of stone and soil. Builders use them with heavier homes because the pillars displace the weight of the house over a large area, preventing the home from sinking.
Slab foundation homes sit on a large concrete base that matches the floor plate of the home. Most modern homes are built using a slab foundation. In this case the plumbing is often encased in concrete which makes it more difficult to make repairs. The main advantage of a monolithic foundation is that they’re less expensive and quicker to construct.
If a home has undergone a remodel or addition, you might find a mix of foundation styles. It’s not unusual to see an original pier and beam home with a slab addition, or a home with slabs of different ages. The mix of foundations creates its own unique set of issues.