Why Is My Concrete Settling?

Concrete settling occurs when the soil underneath the concrete can no longer hold up the structure. In Kansas City, this happens due to shrinking and swelling. The Marshall soil of the region contains clay, causing the soil to expand when exposed to water. When that moisture dries up, the soil shrinks and compacts together. However, the soil is no longer the same size it was before: the soil has shrunk in size so much that it lost a significant amount of volume, so there is now a gap between the concrete and the soil.

Because there is now a void left, the concrete settles against the soil layer, which now rests lower than it did before. Concrete settling is most likely to occur in areas of the house that get exposed to an excess amount of water, such as your pool deck or driveway. Rainwater and melting snow seep through the concrete and saturate the soil, causing it to expand. This shrink-swell process that soil goes through takes place over a few years, so it’s up to you to spot the problem signs early to avoid excessive settling.

There isn’t much that can be done to prevent concrete settling besides just getting repairs done when the slab does start sinking. Replacing the soil won’t yield many results because sandy soils wash out when exposed to water. The best you can do is protect your slab and soil from excessive moisture by keeping snow away from it during the winter and improving your yard drainage.