Differential settlement is uneven sinking, where one part of a slab or structure settles more than another because the soil beneath it fails inconsistently, creating tilted surfaces, cracks, and trip hazards.
In depth
Soil rarely fails uniformly. A downspout may erode one corner while the rest of the slab stays supported, or a section over a tree root may drop while its neighbor does not. The result is a slab that is no longer level with itself or with adjacent slabs, which is what produces the classic raised-edge trip hazard and diagonal cracking.
Differential settlement is more damaging than uniform settlement because the twisting and shear it creates stresses the concrete. Targeted polyurethane injection re-levels only the low sections, restoring an even plane.
How Acme applies it. Acme diagnoses which sections have dropped and lifts them selectively so adjacent slabs align, eliminating the changes in level that create liability and code issues.
Related terms: Concrete Settlement, Trip Hazard, Change in Level, Concrete Cracking, Rocking Slab
Frequently asked questions
What is the difference between settlement and differential settlement?
Settlement is a slab sinking; differential settlement is a slab sinking unevenly, so parts drop more than others. The uneven version causes the trip hazards and cracking that most repairs target.
How is differential settlement corrected?
By injecting foam only under the low areas and lifting them back into alignment with the higher sections, restoring a level, continuous surface.