The monolithic foundation means exactly that. It is poured in one stage and one unit rather than being poured in 3 stages and comprised of 3 units. Monolithic foundations are therefore poured in one day, require only one inspection, are less vulnerable to poor soil and relatively easy to repair if poor soil conditions manifest at a later date. More importantly, the accuracy of the monolithic technique is easier to control. Each foundation is inspected 3 times by our crew in the field for both square and grade before the concrete is poured.

The post-tensioned or monostrand technique is also a one unit foundation; however, it is much more structurally sound than the standard monolithic. The post-tensioned foundation utilizes cable in the concrete usually spaced four feet apart in a criss-cross or grid fashion. Each cable is subsequently stressed to 33,000 pounds after the concrete has reached sufficient strength.

Post-Tensioned Foundation Beginnings

After World War II, concrete slabs (referred to as "floating slabs") were used for foundations in many residential buildings. These slabs were ground supported with reinforcing that allowed the slab to "float" on top of the supporting soil. During the 1950's, with the development of concrete transportation trucks, the use of these slabs became increasingly common. However, it wasn't until the mid 60's that post-tensioning for ground supported slabs was developed by Bill Kelly in New Orleans, Louisiana patented as the Kelly System. 

Many of the first post-tensioned slab foundation installations were made in various parts of Texas and Louisiana. In 1967, the first FHA approved post-tensioned foundations were constructed in Houston, Texas and in 1968 the Department of Housing and Urban Development approved the use of post-tensioned slabs throughout the United States.