Soil Shrinkage, Compaction, and Settling

Different types of soil have different load-bearing capacities. When a soil’s load-bearing capacity is exceeded, the soil will compact and settle.

It’s also possible for the soil beneath a slab to settle and compact of its own accord. Soil that contains large amounts of clay and/or silt will shrink substantially when it gets dry.

As the soil compacts underneath a concrete slab, the unsupported slab will sink as well, usually cracking in one or more spots.