A floating slab foundation is one in which the concrete that forms the foundation for a house is poured right on top of the ground. This type of foundation works most effectively on level sites in areas with warmer climates.
Before the concrete for the slab is poured, a layer of gravel 4 or 6 inches thick is added to the top of the soil, and a 4-millimeter sheet of plastic goes on top of the gravel. The main part of the concrete slab that goes on top of the plastic and gravel is 4 to 6 inches thick, while the concrete around the edges is formed into a beam that's about 2 feet deep. Wire mesh measuring 6 inches by 6 inches, along with steel reinforcing rods, is embedded in the concrete. The foundation is said to "float" on top of the ground, and the deeper concrete around the edges keeps it in place.