Cracked or sunken concrete in Atlanta can often be repaired by lifting the slab with a cement slurry or polyurethane foam, sealing cracks, patching, or resurfacing. Replacement is better when slabs are badly broken. Any repair should also fix the cause, such as runoff washing out soil, and foundation cracks warrant a structural evaluation first.
Last updated
Not every cracked or sunken slab needs to be torn out. Depending on the cause and condition, concrete can often be lifted, patched, sealed or resurfaced for less disruption than a full replacement. The key is figuring out why it failed, because a repair that ignores the cause tends to fail again.
Why concrete cracks and sinks in Atlanta
- Settling soil. Loose fill placed during construction, especially near foundations and along driveway edges, can compress over time.
- Water. Downspouts and runoff can wash soil out from under slab edges, leaving voids.
- Clay movement. Clay-rich soils can swell when wet and shrink during dry spells, pushing slabs up or letting them drop.
- Tree roots. Roots lift walks and driveways, and dying roots can leave voids.
- Freeze-thaw and deicers. Atlanta's winters are mild, but repeated freezes and salt can cause surface scaling on concrete that isn't air-entrained or was finished poorly.
- Shrinkage. Some cracking is normal as concrete dries, especially where joints are too far apart.
Repair options
- Slab lifting (mudjacking): a cement-based slurry is pumped under a sunken slab through drilled holes to raise it and fill voids.
- Polyurethane foam lifting: an expanding foam is injected through smaller holes to lift the slab. It's lightweight and cures quickly.
- Crack filling and sealing: flexible sealants keep water out of cracks and joints, which slows further damage.
- Patching: spalled or broken spots can be patched with repair mortars, though patches rarely match perfectly.
- Resurfacing: a thin cement-based overlay can renew a surface that is scaled or worn but structurally sound.
- Section replacement: badly broken panels are cut out at joints and repoured.
When lifting makes sense
Lifting usually works best when the slab is mostly intact, has sunk as a unit, and the soil beneath has stopped moving. Badly broken slabs, or slabs over soil that is still being washed out, are often better replaced. Fixing the water source, such as extending downspouts or regrading, should be part of the plan either way.
Trip hazards
An uneven joint on a walkway or driveway is a common cause of falls. Contractors can lift the low side, grind down the high edge, or replace the panel. If the hazard is on a public sidewalk, check with your city or county about who is responsible and whether a permit is needed before work is done.
When it might be structural
Cracks in a garage floor or patio are usually not structural. But cracks in foundation walls, slabs that support the house, stair-step cracks in brick, or doors and windows that suddenly stick can signal foundation movement. In those cases, an evaluation by a structural engineer or a foundation repair specialist is the right first step, and that work may involve licensed contractors and permits.
Questions to ask
- What do you think caused the problem, and how will the repair address it?
- Will you lift, patch or replace, and why?
- How will the drill holes or patches look afterward?
- Is there a warranty on lifted slabs if they settle again?
Have a sunken slab or a trip hazard? Mark your request as urgent and request a concrete repair contractor.
Frequently asked questions
Is mudjacking or foam lifting better?
Both can lift sunken slabs. Cement-based slurry lifting is a long-established method; polyurethane foam uses smaller holes, is lighter and cures quickly. The right choice depends on the slab, the voids beneath and the contractor's experience.
Are cracks in my driveway or patio a structural problem?
Usually not. Shrinkage cracks in flatwork are common. Cracks in foundation walls, stair-step cracks in brick or sticking doors and windows can point to foundation movement and are worth a structural engineer's evaluation.
Can a scaled or flaking surface be repaired?
If the slab is otherwise sound, a cement-based resurfacing overlay can often renew it. Scaling is commonly linked to freeze-thaw cycles, deicing salts or finishing problems, so ask how to prevent it from returning.