Sinking Concrete Due to Soil Issues

Why Does Outdoor Concrete Sink?

Concrete is heavy! When the soils underneath a concrete slab are unable to support its weight, the slab will sink.

If part of the concrete slab is supported by soils and other sections are not, the unsupported pieces may crack away from the other section and result in unlevel concrete.

Tar Heel Basement Systems can inspect the condition of your concrete slab during an on-site estimate. Call us today to schedule a free quote in Lexington, Winston Salem, High Point, Greensboro, and surrounding areas.

Primary causes of sinking outdoor concrete

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.

Washout of Soils

The soil that is underneath your driveway, patio, or concrete steps may not necessarily remain there to provide adequate support for the concrete element. Soil washout can result in empty space beneath your concrete slab, unable to support it. This can lead to cracks and sink over time.

As water moves underneath your concrete slabs, it can wash away the soil that’s supporting the weight of the concrete. As this happens, it creates a void, or empty space, underneath. Over time, with nothing to support it, your concrete slab can begin to sink or cave in.