The Three Basic Types of Home Foundation

There are three basic types of foundation that are used today in the construction of a house.

Slab foundations

A slab foundation is a foundation built directly on the ground with no basement or space between floors. Slab foundations are common in areas where soil conditions are not suitable for a basement and are the most common foundations found in warmer areas such as Florida, Arizona, California, and Texas, or anywhere where the depth between the stable soil and underlying rock is very shallow. Slabs are the fastest and cheapest foundation because they require less labor, skills, and material costs. They consist of a concrete slab that is typically 6 to 8 inches thick. Embedded within the slab is a support grid of ribbed metal rods known as a “rebar.” Even in places where basements prevail, slab foundations are usually laid as the foundation for structures such as garages, post barns, and sheds. Slabs are the least expensive of the three main foundation types, but they do not provide storage or utility space as the house actually sits directly on a large solid concrete deck. Slabs have the downside of being difficult and expensive to repair when they settle and crack, and plumbing lines that stick out of the ground up through concrete can also be expensive to repair. In areas where the underlying soil is thick or prone to excessive expansion and contraction, cables are embedded that can be tightened to provide better horizontal support and minimize the width of the cracks.

Crawling space foundation (pier and beam)

A column-and-beam foundation consists of vertical wooden or concrete columns (piers) that support floor beams or beams above the ground. The areas between the floor and the bottom of the house’s floor are known as crawl spaces. These foundations are built at ground level or over a shallow excavation that varies in depth, but is commonly between 36 and 40 inches deep. The best foundations for crawl spaces have a load-bearing concrete perimeter wall and concrete or steel piers, both with footings below the ground freeze line, along with a good above-ground barrier to keep moisture in check. . The less expensive versions have no load-bearing perimeter walls, shallow footing piers, and no full-floor moisture barrier. Crawling spaces that are enclosed by a wall or baseboards should have vents on each side to allow air to circulate and help keep the soil dry under the house. These vents should be set up to keep out rodents and snakes. Crawlspace foundations are most often used in areas where there is a high content of clay in the soil that can severely damage (crack) the slab foundations, or on flood-prone or waterfront construction sites where it must have the height of the floor necessary to avoid the penetration of water in the living space. be taller than a slab can normally provide. The main advantages of crawl space foundations are that plumbing lines are easily accessible for repairs and foundation settlement problems are easier and less expensive to correct than with slab foundations. A main disadvantage occurs when these foundations are not properly maintained or are built without adequate ventilation, allowing water or pests to cause damage. Crawling space foundations without proper insulation applied to the bottom of the home floor can be very energy inefficient in cold weather.

Basement foundation

A basement is a type of foundation that includes an accessible space between the ground and the base of the first floor of a home. This foundation provides living space under the house, below the elevation of the ground. It is basically a slab foundation with walls and a floor. Basements are most often built in cold climates, such as the Northeast, Midwest, and Rocky Mountains, and in places where the cost of digging is not prohibitive. Basements start with a hole approximately 8 feet deep, however some homeowners will opt for a 9 or 10 foot deep basement wall to increase the height and volume of the usable space. The floor and the walls are built, then the house itself is built on that. Basement foundations have the advantage of providing useful space for utilities, mechanical systems, and storage that is not available in the previous two types of foundations. The main disadvantage of basements is that because they are mostly below ground level, they are vulnerable to leaks, mold and flooding. Basements in humid climates should always have a floor-running drain and pump to combat flooding.