Concrete Foundation Footings

The specific dimensions for concrete foundation footers, as already mentioned, are a function of the soil type. They also vary depending upon the size and number of floors of the home. Finally, local building codes also dictate specific dimensions and concrete strength for concrete foundation footers.

The main purpose of concrete foundation footers is to spread the weight out of the home’s foundation walls. Typically concrete footings are 2-1/2 to 3 times as wide as the concrete foundation wall thickness. By distributing the weight of the foundation walls and home over a larger surface area there is less risk of the home settling. When a home settles cracks can form in foundation walls and drywall. Sometimes these cracks can simply be small nuisances, but other times they can create real structural concerns in the home. In addition, a cracked foundation wall is an easy entry point for ground water.

For typical soils concrete foundation footings are normally 16 to 22 inches in width and 6 to 16 inches in depth. If the soil type is such that it supports less weight, such as soft clay soil, then the concrete foundation footings may be constructed larger. In some cases, if the soil is of poor load bearing capacity, more of it may be removed and then replaced with compacted crushed and angular gravel.

When building the forms for concrete foundation footings, steel rebar should be included in the forms to improve the overall tensile strength of the concrete footings. The amount and placement of the steel rebar should be specified by a structural engineer to ensure a proper and strong concrete foundation footing. Ideally concrete foundation walls should be centered directly over the center of the concrete foundation footings, however with a standard house there can be some flexibility.

Often when installing concrete footings they are not always installed perfectly straight and perpendicular due to the confined space working in the trench to install the footing forms. As long as the foundation walls are resting entirely on the concrete footings, however, there is typically no issue.