Slab-on-grade foundations are well-suited to southern U.S. climates IF the slab is built to a good standard of quality and performance. (Photo: Wikimedia Commons / Shakespeare CC by 3.0)

Slab-on-grade foundations are one of the most popular types of foundations in the U.S. They’re quick and inexpensive to build and are great in southern climates where the freezing depth in the soil is shallow. In these climates, slab-on-grade foundations work well, as long as the slab is built to a good standard of quality and performance.

Typically, the largest concern with slab-on-grade foundations is cracking. Concrete naturally experiences some cracking as it shrinks during the curing stage. These natural cracks are known as shrinkage cracks. Shrinkage cracks appear as a displacement or separation in the surface of the concrete and are hard to prevent.

Shrinkage cracks aren’t detrimental to the performance of a slab, but they can be unsightly and cause cosmetic damage to interior floor finishes. Concrete can also experience cracking when certain soil conditions are present. These soil conditions, which we’ll discuss in a minute, require additional measures to ensure the quality and performance of the slab. One such additional measure is to reinforce the slab through a process called post-tensioning.