Intact slab with a localized low area
- Likely next step
- Evaluate slab lifting
- Why it matters
- Preserving a sound slab may avoid demolition and replacement.
How Do You Repair Sunken Concrete?
Sunken concrete may be lifted by injecting cementitious grout or expanding polyurethane beneath an intact slab, but lifting is not automatically a permanent correction. First identify why support was lost. Erosion, leaking drainage, poorly compacted fill, soil shrinkage, roots, or continuing settlement can cause the slab to move again if the underlying condition remains active.
Start with the condition, not the product
Void beneath a level slab
- Likely next step
- Evaluate stabilization
- Why it matters
- Filling support loss is different from deliberately raising the slab.
Shattered or severely deteriorated slab
- Likely next step
- Evaluate replacement
- Why it matters
- Lifting does not restore concrete that no longer acts as a sound panel.
Continuing erosion or soil movement
- Likely next step
- Correct the cause first
- Why it matters
- Injected material cannot guarantee stable soil or stop ongoing water movement.
Find out why the slab lost support
Settlement describes the result, not the cause. Check grading, roof drainage, plumbing leaks, washout along slab edges, recently disturbed soil, drying clay, frost, and nearby roots. The repair scope should state which condition is known, suspected, or excluded.
- Redirect water before lifting when erosion is contributing
- Investigate sudden settlement near utilities or plumbing
- Document whether movement is continuing
- Confirm that lifting will not create a new drainage or threshold problem
Know the difference between lifting and stabilization
Slabjacking deliberately raises a settled panel. Slab stabilization fills voids to restore support without necessarily changing elevation. A quote should identify which outcome is intended because the hole layout, material volume, pressure, and quality controls may differ.
- Target elevation or tolerance
- Injection material and anticipated hole size
- How lift will be monitored
- How joints, cracks, edges, and injection holes will be treated
Know when replacement deserves a price
Replacement becomes more credible when the panel is badly cracked, surface deterioration is deep, the required lift would create binding or misalignment, or the base needs excavation. Ask for both alternatives when the remaining concrete condition is uncertain.
- Compare drainage and base correction in both scopes
- Ask what happens if the slab cannot be lifted to tolerance
- Clarify responsibility for new or widened cracks during lifting
Technical references and limitations
These references explain general repair principles. Residential conditions, local codes, product requirements, and structural significance vary. Use a qualified local professional for diagnosis and design where safety or structural performance is involved.