Expansive soils are soils that contain minerals such as certain types of clay that are able to absorb water. When the clay absorbs water, it will expand. The more water they absorb, the more they expand. Soils containing as little as 5% clay can exhibit expansive characteristics.
In my career, I have seen just about every degree of settling and every foundation problem that a home’s foundation can experience. I have also discovered that there is a difference between normal foundation settling and serious foundation problems.
Have you ever gone up into your attic on a hot summer day? If so, you know how hot it can get inside an attic. This heat buildup is one of the main reasons why proper attic ventilation is critical to maintaining the health of your home.
For homes built on expansive clay soils, changes in moisture level in the soil is the foundation’s worst enemy. During dry periods, the soil will contract and pull away from the foundation, leaving the edges of the foundation essentially unsupported. Since concrete slabs are flexible and not perfectly rigid, the foundation will actually sag along the edges. Then when it rains, the soil expands and pushes up against the foundation with extremely high forces.
Most of the homes that I have inspected have foundations that fall into the category of those that have experienced some typical settling while a small percentage have needed extensive foundation repairs. I am often asked by my client. “Does the home’s foundation need to be repaired?” I will try to answer that question in this blog.