For those of us that live in areas that have expansive clay soils, foundation problems are as predictable as the rising sun. Expansive clay soils contain minerals such as smectite clays that are capable of absorbing water, hence they exhibit volume change. Expansive soils can cause heave and settlement depending on the time of year and overall moisture content of the soils.
Some movement is likely to occur in homes built on expansive soils. We can minimize cracking and major structural damage through maintaining more consistent soil moisture levels around our homes. Using some simple steps, outlined below, and common sense we can protect our homes from the potentially devastating effects of expansive soils.
A. Yard Drainage – All areas should drain away from the home. 5% slope within the first 10’ of the foundation and at least 1% after that.
B. Roof and Gutter – Gutters need to be maintained and downspouts should be routed beneath grade in PVC pipe at least 10’ away from the home.
C. Driveway and Sidewalk – Concrete areas should be slope away from the foundation and kept at or below grade to prevent ponding.
D. Plumbing – Unexplained increases in water consumption should be investigated immediately. Plumbing leaks are a very common cause of heaving beneath structures.
E. Subsurface Drainage – Maintain and or add foundation drain systems. Make sure pipes are free-flowing and drain into a sump basin or to daylight away from the foundation.
F. Trees and Bushes – Trees should be 1 – 1-1/2 times their height away from the structure. Trees are a major contributor to settling foundations.
By following the above steps you will decrease the effects of expansive soils. If water is your enemy, the solution is water management. By maintaining a constant soil moisture content, your home will remain stable and unaffected by the dramatic effects if expansive soils supporting homes are allowed to become too wet or too dry.