Why does concrete sink?

Concrete problems are common, and all concrete can fail at some point. Concrete slabs are heavy! When concrete is poured on top of soil, it runs the risk of sinking.

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

There are several reasons why concrete sinks:

Lack of slab support

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

Soil shrinkage and compaction

Soil shrinkage, compaction and settling all have an impact on sinking concrete. If the soil below the slab isn’t compact, the concrete can easily begin to sink as the soil beneath it solidifies and hardens. If the soil is too wet or too dry, this can also cause concrete to sink.

Types of soil

Different types of soil have different load-bearing capabilities. When a soil's load-bearing capacity is exceeded by the heavy concrete on top of it, the soil will compact and settle, causing the concrete to sink, crack, crumble and become uneven.

For example, if concrete is poured onto fill soil that surrounds a new build (compared to soil that is native to the area and well-compacted), the fill soil will become more compact over time and may cause the slab to sink.

It's also possible for the soil beneath a slab to settle and compact on 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 soil

Washout of soils is also a possible cause of sinking concrete. 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.

How to fix sinking concrete?

The good news is that you don't have to live with sunken concrete anymore!

We use a great product called PolyLevel® to lift and level sinking concrete. PolyLevel® comes with many advantages over the traditional mudjacking and concrete replacement options.

Learn more about concrete leveling with PolyLevel®.

Check out our before and after photo gallery to illustrate what PolyLevel® concrete lifting can do for your property!

Contact L.R.E. Ground Services, Inc. to fix sinking concrete

We would be happy to provide you a free inspection and cost estimate for PolyLevel® concrete repair in Lakeland, Sarasota, Clearwater, Bradenton, Kissimmee, Daytona Beach, Ocala and other local areas.

L.R.E. Ground Services, Inc. can inspect the condition of your concrete slab during an on-site inspection. Call today to schedule a free inspection in Tampa, Orlando, Saint Petersburg and surrounding areas.