How to Repair a Cracked, Sinking Concrete Floor

cross section of a concrete slab
Concrete slab piers can extend deep below the floor to reach competent supporting soils and permanently stabilize the floor.

Do you have a concrete slab floor that is showing signs of sinking, sagging, or settling? Are the walls separating from the floor below or ceiling above? If you have a problem like this in your home, you could have a sinking or settling concrete floor slab. This problem can lead to cracks in floors and walls, uneven surfaces, and a weakened foundation. This article will help you identify the signs and causes of these issues, as well as how to repair them.nbsp;

Signs of Slab Settlement

When a floor slab settles, the damage can manifest itself in many ways. Along with cracks in the concrete, the floors can separate from the walls as they sink downwards. Alternatively, the interior wall may be pulled down with the floor, instead separating from the ceiling. Walls can also pull away from other walls, and interior wall cracks can form, commonly off the corners of interior doors. cracked concretecracked wallcracked door frame and wallshift in wood panelingsinking slab floorfloor seperationshift in floor from wallfloor leveling off

Causes of Settling Concrete Floor Slabs

When a concrete floor settles, it can mean serious damage to your home. The causes of floor slab settlement are almost always due to the soils underneath being unable to support the weight of the concrete. They often accompany other foundation problems in your home.The three most common causes of settling concrete floor slabs are as follows:

1) Drying & Shrinking of the Soil Under the Slab

HVAC (Heating, Venting, and Air Conditioning) systems may be installed beneath the floor slab. Over time, the ductwork can leak air, which can dry out the soil. As the soil dries and shrinks, gaps form under the floor slab, creating voids. Because the soil no longer supports the floor slab, the floor begins to crack and sink into the voids.

2) Washout of Soil Under the Slab

This is usually caused by plumbing leaks. If the plumbing leak is severe and there is a path for the water to flow through, it can wash soil out from under the slab. With a void underneath the floor, there's nothing supporting the concrete slab anymore. In time, it begins to crack and sink downwards.

3) Poor Compaction of Fill Soil

During construction of a new home, layers of soil are commonly moved around or spread out to get to the desired grade level. When the home is built, footings may be deepened to extend below weak fill soils and avoid a foundation settlement issue. The slab, however, remains on the fill soils. If the fill was poorly compacted, the fill soil compresses and settles, and a void is formed under the slab. In time, the slab cracks, breaks, and settles into the void.

How to Repair Cracked, Sinking Concrete Floors

At Thrasher, we use the Supportworks Slab Pier System to fix these issues. The Support works Slab Pier System stabilizes the concrete floor slab in your home, and it provides the best opportunity to relevel the floor and lift non-load bearing partition walls that may have settled along with the slab. To install our system, our contractor will take these six steps:

1) Prepare for Installation

Before the installation day, a representative from our company will have already inspected your foundation issue. At that time, a foundation repair proposal was put in writing. Your foundation repair experts will use that proposal to map out the locations where the slab piers will be installed. At the beginning of each slab pier installation, a small hole is cored through your concrete slab floor. This hole will create an access point for the slab piers that are about to be installed.

2) Position the Slab Bracket

To give the slab pier something to "lift," a slab bracket is positioned beneath the concrete slab. The Supportworks Slab Pier System uses a three-piece slab bracket that is assembled underneath your concrete floor, allowing for a much smaller hole to be cored in your concrete slab. Additionally, this larger bracket reaches across more area along your floor, creating a more even distribution of weight.

3) Install Steel Tubes

Steel tubes are hydraulically driven down through the bracket to the competent soils beneath. These steel tubes are the real strength of the foundation pier system and are responsible for transferring the home weight to strong supporting soils. To prevent corrosion, Thrasher has slab piers available that are designed using galvanized steel. This ensures the quality and long-lasting strength of your slab pier system.

4) Transfer the Slab Weight to the Soil

The weight of the concrete slab is transferred through the piers to the load-bearing strata underneath your home. As the system lifts your concrete slab floor upwards, the sinking movement of your floor will be permanently halted. Often, it will also be possible to lift the concrete slab back to a level position.

5) Inject Grout Fill

Once the concrete slab has been lifted, a void will be present underneath the removed floor. Additionally, if your floor had been sinking because of compacted soil or washout, a gap existed even before the installation. To address this, we carefully pump grout under the slab to fill in all empty spaces.

6) Cleanup

At Thrasher, we take pride in leaving your home looking clean and neat. Once the installation is completed, we repair all cored holes with concrete, making your final installation virtually invisible. Any debris generated during the installation is cleaned up and removed by us. And once we're done, you can rest easy, knowing that you have a 25-year warranty on manufacturer's defects, as well as a performance warranty from us.

Contact the Foundation Slab Repair Experts

At Thrasher, we provide proven solutions for concrete slab floor leveling, as well as other foundation repair solutions to homeowners throughout Nebraska, Iowa, and Missouri. We provide each of our customers with a free, no obligation slab repair quote, in writing, before any work is done. We proudly offer foundation repair services in Omaha, Lincoln, Sioux City, Kansas City, Wichita, Kearney, Grand Island, Council Bluffs, Bellevue, Norfolk, North Platte, Fremont and throughout the surrounding areas. To schedule your appointment, call or email us today!

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