What are expansive soils?

Expansive soils are a clay soil type which is prone to large volume changes (shrinking and swelling) due to changes in water content.

Why are expansive soils an issue?

Expansive soils will expand/swell when wet, and shrink when dry. The constant cycle of shrinking and swelling can lead to repetitive stress on a structure. If left unaddressed, this can lead to cracks within the foundation slab, basement or upper-level walls, or damage to the exterior facade. As with most foundation issues, the repair costs are often extremely high.

How do I know if my house is – or will be – affected?

For those living on the east coast, midwest, and most of the western part of the United States, you need not worry about expansive soils. However, for those located in the plains states, Texas, or parts of the southwest, you may want to do a bit of research on your native soil types.

The map shown below is from geology.com and depicts the at-risk areas of expansive soils in the United States.