Sinking concrete: what causes it?

by | Last updated Aug 3, 2020 | Published on Jul 30, 2020 | Concrete Settling

If you have a concrete driveway, floor or sidewalk, it can happen that you notice that the concrete starts sinking. What causes this? The answer is quite simple. Concrete is heavy. So when the soil underneath a concrete slab can’t support the weight anymore, the slab will sink. It can also be that parts of the concrete slab are not supported by soil. That way the unsupported parts can crack away from the supported parts which results in unlevel concrete. Sinking concrete is the result of a concrete slab that is not supported. So if you understand why sinking concrete happens, you can make sure it doesn’t happen again.

Reasons for sinking concrete

Be aware that cracked or sunken concrete will only get worse over time. Safety concerns can became a problem. As well as structural damage to other parts of your house, driveway or sidewalk. So it is important to get the concrete lifted again. Let’s have a closer look at the reasons for sinking concrete.

Expansion and shrinkage of soil

Changes in the weather can influence the amount of moisture in the soil. When it rains, the soil gets wet, holds water and will expand in size.When it dries again, it starts to shrink. This can create voids under the concrete slab.

Soil washout

Soil under a concrete slab may not always remain there. Heavy rain or for example a plumbing leak can result in a lot of water underneath your concrete slab. This can wash away the soil that is supporting the concrete and leave an empty space.

Quality of soil

The soil on which the concrete is poured, can be of different qualities. On soil that is loosely compacted, the concrete will be more likely to crack. Soil that contains for example a large amount of clay will shrink when it gets dry. As the concrete and the soil underneath it settle, voids can be created.

Load-bearing capacity of soil

Soils can have different load-bearing capacities. If this capacity is exceeded, the soil can compact and settle. Once this happens, parts of the concrete will be unsupported.


If you are experiences with sinking concrete, get a quote now to get it fixed. You don’t have to live with sinking concrete. We will check what causes the cracking or sinking of the concrete. And make a plan for our concrete lifting service in Calgary and surroundings. We can help you with your driveway, patio or sidewalk for example. We use concrete lifting foam, both for residential as commercial applications.