Why Foundations Fail in Expansive Soils
Published on October 7, 2016
FOUNDATION REPAIR CONSULTANT
The soil is expansive, meaning it shrinks and swells with the addition and loss of moisture.
This movement of the soil causes the foundation, because of its design, to flex!
The house sitting on the flexible foundation is not designed to flex. Sheetrock flexes very little, bricks and mortar do not flex and hard floor covering and door frames do not flex.
This is, in a nutshell, what lets foundations fail in North Texas and other areas of expansive soils
Most damage in our area is relatively minor compared to areas of major earthquakes, sink holes, mud slides, subsidence and other acts of man and or nature.
Most North Texas foundations are poured during hot dry periods when the soil has shrunk. This would lead one to believe that most foundation movement is the result of areas of shrunken soil, expanding unevenly under and around the foundation.
And this is true in many instances.
As the soil expands it lifts parts of the foundation, causing the foundation to flex. As the foundation flexes, the home begins to be lifted, but, the home, being unable to fully flex, cracks begin to appear, door frames are pushed out of square and what we consider foundation damage is observed.
Here is where an authority is required. Where you need a check and balance. Where you do not rely on someone who makes a living selling piers.
Soils expand, but they also contract. Both expanding soils and contracting soils cause nearly the same problems. Without years of experience, you can not tell one from the other. You cannot use a levelling device to tell the difference without a benchmark. The benchmark would be elevations to sea level at the time of construction, which no one has.
The point is, shrinking soils have one cure and expanding soil has another cure. If you use piers on a foundation where the soil has expanded it will fail. If you try to cure shrinking soil problems with drainage correction, you will not be successful.
The answer is to get someone on your side who knows their stuff and will not profit from selling you a certain repair,