Slab-on-grade foundations are described as when a concrete floor slab is poured at grade level to provide a foundation for a home, building or structure.  Concrete slab on grade foundations are built on ground level with no crawl space or basement. Most modern homes in San Antonio, Texas are designed and built with a slab on grade foundation.  These slabs may be supported on continuous foundations, piers or piles and/or grade beams. These slab on grade foundations serve as the building structural floor, as well as the support for the weight of the house.  As an Alamo Heights concrete contractor, I call upon a registered Structural Engineer is called upon to design these slab on grade foundations. Depending on the soil conditions, the engineer could recommend a post tension slab or a pier and beam foundation. Geo-technical soil testing is often done to determine the contents of the soil and which type of foundation is best suited for that soil.