Now Scheduling
(803) 236-2420
Understanding the real cause of settling slabs in the Lowcountry—and why some repair methods work while others waste your money.
You step out onto your driveway or patio and notice something's changed. The surface isn't level anymore. One section has dropped. There's a lip where two slabs meet that catches your foot. Water pools in places it didn't before. The concrete didn't crack—it sank.
This is one of the most common concrete problems in Charleston and throughout the Lowcountry. Slabs that were poured level gradually settle, creating uneven surfaces, trip hazards, and drainage problems. The concrete itself is often fine—the issue is what's happening underneath.
Understanding why this happens is the first step toward finding a solution that actually works.
The most common misconception is that sinking concrete means the concrete is bad. Homeowners assume the contractor used inferior materials or the slab was too thin. In reality, most settling has nothing to do with the concrete quality—it's about what the concrete is sitting on.
Another mistake is ignoring the problem because "it's just cosmetic." Sinking concrete creates trip hazards that increase liability. It causes drainage problems that direct water toward foundations. And it almost always gets worse over time, not better.
Some homeowners try to fix settling with topical solutions—concrete patching, self-leveling compounds, or even just adding more concrete on top. These approaches address the symptom without fixing the cause. The new material sinks right along with everything else.
Charleston's soil conditions create a perfect environment for concrete settlement. Here's what's really happening beneath your slabs:
Sandy coastal soil doesn't just compact under load—it erodes. Water moving through the soil carries particles away, creating voids beneath slabs. This is especially common near downspouts, along driveways where runoff concentrates, and anywhere water flows under the concrete.
If the soil beneath the slab wasn't properly compacted before pouring—or if fill material was placed without adequate compaction—settlement is inevitable. Sandy soil requires careful preparation that not every contractor provides. The settling may take months or years to become visible, but it was built into the job from day one.
Buried organic material—tree roots, stumps, vegetation—decomposes over time. As this material breaks down, it creates voids in the soil. This is common in areas where land was cleared for development without removing all organic matter.
The Lowcountry's high water table rises and falls with rainfall and seasonal changes. This fluctuation causes soil to expand and contract, loosening its structure over time. The result is gradual compaction and settlement, especially under heavy loads like driveways.
Once you understand why concrete sinks, the repair options make more sense. There are really only three approaches, and each has appropriate applications:
A cement-based slurry is pumped through holes drilled in the slab to fill voids and lift the concrete back to level. This is a proven technique that's been used for decades. It's cost-effective for larger slabs and provides good long-term support.
Works best for: Driveways, garage floors, large patios, and commercial slabs where the concrete itself is in good condition.
Expanding polyurethane foam is injected beneath the slab to fill voids and raise the concrete. The foam is lighter than cement slurry and cures quickly. It's effective but typically costs more than traditional mudjacking.
Works best for: Situations where weight is a concern, quick cure time is needed, or smaller precision lifts are required.
Sometimes the concrete is too damaged, too thin, or too extensively settled for leveling to make sense. In these cases, removal and replacement with proper base preparation is the only permanent solution.
Works best for: Badly cracked slabs, concrete with structural damage, or situations where the original installation was fundamentally flawed.
If you have concrete that has settled or sunk on your Charleston-area property, the first step is determining whether leveling makes sense or replacement is the better investment. This requires evaluating the concrete condition, the extent of settlement, and the underlying cause.
We provide concrete leveling and mudjacking services throughout Charleston and can assess your situation to recommend the approach that actually solves the problem—not just delays it.