Are Clay Soils Good for Foundations?

There are many different types of soils that are used as foundations in construction. One of the most common soils used are expansive soils. Expansive soils are those that contain a lot of clay in them, and because of their clay content, they expand when exposed to moisture, hence the name. Typically, contractors try to find a balance when choosing the soil for a foundation and go for a mix of clay, sand, and loam. Still, the existence of clay in the soil can cause a lot of problems for homeowners, especially if the region’s soil is already expansive like it is in Hickory.

Clay is used in foundation soils because many contractors believe the benefits outweigh the disadvantages. The structure needs to be supported by stable soil, which is why the soil needs to be compacted as it’s layered out. Compaction brings the soil particles closer together and makes it denser and tougher, and the more clay in the soil, the better it compacts. Because clay soils compact so easily, it saves a lot of time, something that many contractors prioritize. Other soils that have less clay are often more granular and don’t compact well, so they are less reliable as foundations for a home.

Despite how reliable they are, clay soils do cause a lot of problems because of their shrink-swell capacity. Expansive soil shrinks considerably once all the moisture content dries up, forming gaps as it shrinks into itself. Over time, these gaps grow significantly wider as the soil shifts around and the foundation no longer has dense soil holding it up. This causes the foundation to settle and slowly shift along with the loose displaced soil. Because all soil eventually shifts no matter how much clay it contains, the best you can do as a homeowner is simply waterproof and reinforce your foundation to protect it against the downside of expansive soils.