Concrete rarely settles evenly; usually one end will sink more significantly than the other.  When this happens, the stress of the uneven support will sometimes crack the slab. At that point, you have high and low points on the concrete, and a crack or joint between slabs that will catch a pedestrian’s toe.  These are trip hazards and a liability issue.

Sometimes, an uneven slab can also cause damage to your home. It may redirect rainwater towards your house, instead of away from it. This leads to water damage to your foundation, and possibly to leaks in your basement or crawl space. Over time this extra moisture can cause serious damage. Water permeating into your home can cause rotting in the structural wood flooring system (sill plate, floor joists, etc) and allow mold to flourish and grow. 

Slab lifting is done by injection.  Small holes are drilled through the concrete slab, and material is injected below it.  This material fills the void underneath the concrete, and gradually the pressure of this filler being forced under the slab creates lift.  The type of fill material varies; many companies use a concrete or limestone slurry referred to as “mud” and this process is generally called mudjacking.  As the slurry hardens, it creates lift below the slab.

At Acculevel, we use a polyurethane foam.  In our experience, slabjacking provides a better and more reliable repair; once the foam is injected, the chemical reaction promptly begins to expand, and it’s this foam that does the lifting.  Since it’s more immediate than mudjacking, it allows for better control.

In this video, one of our knowledgeable experts explains why we choose to perform slabjacking:

Slabjacking uses specialized equipment, but it’s usually installed in a standard-sized service truck that can park in the driveway or street without issue.  Slabjacking repair work rarely requires an Acculevel crew driving across your lawn, or disturbing your landscape; the slabjacking equipment has a 250 foot injection hose to maximize our reach to the repair section.

In fact, there is very little mess generated at a slabjacking job site.  Generally, crews only need to clean up some dust generated from drilling through the concrete, and maybe trace amounts of foam from the injection site.

This is preferable to the messy process of replacing a slab.  Concrete demolition often involves the use of a jack hammer, which is noisy and creates debris that adds to landfills.  Re-pouring concrete requires building forms, a concrete truck, and the use of this equipment in close proximity to the work site.  This results in a significant amount of trash and upheaval on your property. The new slab can also be visually jarring, as it won’t match the other existing sections in color or texture.

Slabjacking works with the existing concrete slab, so the costs are limited.  They depend more on the size of the slab being lifted, and the amount of void under the slab. (The larger the gap, the more material is required.)  The costs to replace concrete can be double the price of slabjacking. For more details on costs, please review our article on costs comparisons.