HomeownerHelpful Info: Home Maintenance

Concrete Leveling & Raising

Concrete Leveling & Raising Educational Content

When the soil supporting a concrete slab settles or washes away, the concrete may crack and sink. This uneven concrete is easy to see. Identifying areas that could crack in the future requires a keener eye. After especially wet or dry weather, take a look around your property for any unsupported concrete. Pay close attention to the edges of the driveway, sidewalk, walkway, patio, steps, and foundation. Take note of any voids or gaps in the surrounding soil, even if they’re small. It’s important to have uneven or sinking areas repaired promptly. These types of problems only worsen (and become more costly to correct) with time.

Inadequate grading, clogged gutters, and other drainage issues can all cause soil erosion. Soil washout can leave voids underneath concrete surfaces. Unsupported concrete slabs are likely to sink and crack over time. Settling soil layers can also be problematic for concrete. The ground beneath concrete is made up of different layers of soil. Each of these layers has its own properties, like density and moisture content. When these layers settle over the years, the concrete slabs above them can settle and crack. An improperly prepared soil base can also be the culprit of sinking concrete. Before a concrete slab is poured, the supporting soil must be compacted. This step prevents washout and erosion. This should be done with a mechanical tamping machine for best results.

Once you have any areas of sunken concrete lifted and repaired, be sure to stay on top of home maintenance. If you don’t take the necessary steps, the problem will happen again. Have your gutters cleaned at least twice per year—once in late spring, and again in late fall. Make sure that your home has an adequate number of downspouts. The downspouts also need to be long enough to take rainwater far away from your house. Contact a drainage specialist to correct any drainage problems in your yard. Make sure that the ground beneath any new concrete surfaces is properly prepared.

Contractors typically use either a synthetic or mortar-based material to fix unsupported slabs. The foam or liquid is pumped underneath the slab via a hose that connects to small injection holes. As the material fills the void, the sunken areas rise to meet the level of the surrounding concrete. The injection holes are patched and sealed once the process is complete. Foam materials typically cure faster and require smaller injection holes than mortar-based materials.