The foundation is perhaps the most important part of your new home. After all, your entire house sits on it. Given the unstable nature of Texas soils, you can be sure your foundation will shift and move as the soil underneath expands and contracts. In fact, this is normal. The key is to make sure the foundation moves as a single unit, otherwise the walls anchored to it could crack and separate. To ensure a foundation can withstand uneven forces from the soil, it is built using reinforced concrete. The reinforcement is provided by either embedding steel rebar (reinforcement bar) or using tensioned steel cables. In theory, both methods yield acceptable results. In practice, however, a post tension foundation is much more susceptible to human errors that can occur during the construction process.
To understand why, it helps to know a little bit about how foundations are built. First, form boards are set in place. This creates a giant "sandbox" into which concrete is poured. Before this happens, steel reinforcement must be added, because concrete alone lacks the tensile strength to withstand extreme forces from unstable Texas soils.
Reinforcement with Post Tension Cables
In the case of a post tension slab, steel cables are laid out in grid fashion inside the forms. The foundation gains tensile strength when the cables are tightened after the slab has been cast. The tricky part comes when concrete is poured into the forms. Great care must be taken to ensure the cables remain perfectly straight during the pour. Unfortunately, concrete is extremely heavy, and can easily displace the cables as it shoots into the forms. If the cables are shifted from their designed position, they won't perform the way they were supposed to. In fact, the tensioning (tightening) process can actually weaken the concrete if a cable is misaligned.
Reinforcement with Steel Rebar
The more conservative approach is to set steel rebar inside the forms. With rebar, there's nothing to tighten. Steel rebar doesn't move the way cables can when concrete is poured into the forms. In other words, a rebar foundation is inherently more forgiving of the typical conditions experienced at a construction site.
For these reasons, Antares Homes believes concrete reinforced with steel rebar provides a superior foundation system. Yes, it costs more, but we would rather spend a little more on the most important part of your new home, rather than run the risk of future problems.