Concrete Slab

A floating slab is a single chunk of concrete that sits directly on flat soil, while a monolithic slab is a single piece of concrete that includes built-in footings that reach several feet below where the majority of the slab sits. Monolithic slabs provide more support, so they’re suitable for home construction, whereas floating slabs get minimal support from the soil directly below and are more common under sheds and detached garages.

Both slab and pier and beam foundations have their place in home construction, and neither is universally better than the other. Slab foundations are superior to pier and beam in terms of installation cost, the lack of repairs typically required, and because they don’t house moisture or attract pests. However, pier and beam foundations are best in areas prone to flooding and on unlevel or sloped plots, and they’re better where the frost line sits a few feet below the ground. Pier and beam foundations also provide easy access underneath the home for storage and utilities. 

There’s no difference between a “slab foundation” and a “slab-on-grade foundation,” and contractors and homeowners use the terms synonymously. “Slab foundation” is just a shortened version of “slab-on-grade.” In both cases, the homebuilder will pour the concrete foundation into a mold they build directly on the ground. As such, these foundations require no expensive excavation.

A floating concrete slab is considered a footing since it distributes the weight of the structure to the soil, but not all concrete slabs are considered footings. For example, a T-shaped slab includes separate footings below the slab that support the concrete above and push the load further down into the ground. In that case, the slab would not be considered a footing.