How Do You Repair Sunken Concrete?
Start with the condition, not the product
| What you observe | Likely next step | Why it matters |
|---|---|---|
| Intact slab with a localized low area | Evaluate slab lifting | Preserving a sound slab may avoid demolition and replacement. |
| Void beneath a level slab | Evaluate stabilization | Filling support loss is different from deliberately raising the slab. |
| Shattered or severely deteriorated slab | Evaluate replacement | Lifting does not restore concrete that no longer acts as a sound panel. |
| Continuing erosion or soil movement | Correct the cause first | 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.