What Uneven Concrete Slabs Tell You About Your Concrete Repair
Uneven concrete slabs show as adjacent sections at different heights, across a driveway, patio, walkway, or garage floor, with lips, tilts, and gaps at the joints. The unevenness reflects soil beneath that has settled unequally, leaving some slabs supported and others dropping into voids. Across Alabama, expansive clay and washout create this differential settlement on all kinds of flatwork. Uneven slabs are trip hazards, they pond water, and they signal the support problem will continue until the voids are filled and the low slabs relifted to a common plane.
Expansive clay and washout create uneven, differentially settled flatwork throughout Alabama, so releveling driveways, patios, and walkways is core concrete work for APS across its markets.
What Causes Uneven Concrete Slabs in Alabama Homes
Differential Soil Settlement
The soil under flatwork settles unevenly because of variable compaction, moisture, and erosion, so some slabs drop while adjacent ones hold, creating the height difference.
Voids From Erosion and Washout
Water moving beneath the slabs carries soil away, leaving voids that individual sections settle into, which is what puts neighboring slabs out of plane.
Expansive Clay Movement
Alabama's clay lifts and lowers slabs as it swells and shrinks with moisture, gradually working sections out of alignment.
Poor Base Preparation
Flatwork poured over a base that was not uniformly compacted settles unevenly as the loose areas consolidate under load.
Signs You Should Not Ignore
- Adjacent slabs sitting at different heights
- Lips or steps at the joints between slabs
- Water pooling in the low sections
- Slabs tilting or rocking underfoot
- Gaps widening between slabs
How We Diagnose and Repair the Problem
- 1
Free On-Site Assessment
An APS technician visits your property, documents the symptom and severity, and reviews all related indicators to build a complete picture.
- 2
Root Cause Diagnosis
Polyurethane foam injection lifts the low slabs back into plane with the others by filling the voids beneath them, restoring a level surface without replacement. Grinding can trim minor lips.
- 3
Written Estimate
You receive a clear written scope of work and cost estimate before any repair begins. No obligation.
- 4
Repair With Transferable Warranty
All APS foundation repairs carry a warranty that transfers to future owners. Serving Birmingham, Mobile, Huntsville, and Columbus, GA.
“Uneven slabs are not a concrete problem, they are a dirt problem. We fill the voids and float the low slabs back up into plane.”
Frequently Asked Questions
Do uneven slabs need to be replaced?
Rarely. In most cases the low slabs can be lifted back into plane with polyurethane foam injection, which fills the void beneath and raises the concrete. That is faster and less costly than tearing out and repouring.
Why are my slabs uneven if the concrete is sound?
Because the problem is under the concrete, not in it. The soil settled unevenly and left voids, so some slabs dropped. The slabs themselves are usually fine and just need their support and elevation restored.
Are uneven slabs dangerous?
The lips between them are trip hazards, and the low spots pond water that can worsen the soil loss. Leveling removes the hazard and helps stop the ongoing settlement.
How long does slab lifting take?
Often a few hours for a typical area, and the surface can usually be used the same day. APS confirms the scope and timing in the written estimate.