Method comparison / slabs-on-ground
Level the concrete or replace it?
Start with the slab, not the sales method. Its condition, the cause of movement, the support below it, and the finished elevation all matter.
Side-by-side
The decision in practical terms.
ACI and FHWA guidance both begin with condition assessment. The table translates that principle into questions a homeowner can use when reviewing a scope.
Swipe horizontally to compare both approaches
| Decision point | Concrete leveling | Concrete replacement |
|---|---|---|
| Basic approach | Material is injected beneath a slab to fill voids and raise or support it. | The existing slab is removed, the base is prepared, and new concrete is placed. |
| Starting condition | Most relevant when the slab remains serviceable enough to move as a slab. | More likely when severe cracking, deterioration, structural damage, or the required redesign makes the existing slab a poor candidate. |
| Original cause | The settlement or loss of support still needs to be investigated. Raising the slab may not correct that cause. | Removal creates access to rebuild the base or change details, but the cause still has to be addressed. |
| Existing cracks | Cracks remain, and some may open during lifting. | The old slab and its cracks are removed. The new-slab scope should state how joints and crack control will be handled. |
| Decision record | Condition assessment, elevations, void or support findings, material, injection plan, and target outcome. | Condition assessment, demolition scope, base preparation, drainage details, reinforcement and joint plan, and concrete specification. |
Leveling may fit when
The slab can still do its job.
- The main problem is settlement or a loss of support below a slab-on-ground.
- The slab remains sound enough to move without relying on unsupported fragments.
- The target elevation and nearby thresholds, walls, steps, utilities, and drainage allow the movement.
- The cause has been assessed and any separate correction is included in the plan.
Replacement may fit when
The existing slab is the limiting factor.
- There is severe cracking, significant structural damage, or deterioration that lifting will not repair.
- The slab geometry, slope, joints, drainage, or base needs to be rebuilt rather than adjusted.
- Removal is needed to reach and correct the conditions below.
- The scope requires a new concrete design or a different finished surface.
Before choosing
Ask for six observations.
A credible scope should show why the slab is a candidate, what outcome is realistic, and what remains outside the repair.
- 01
A crack and condition map
Record crack locations, spalling, breakup, prior patches, joints, and any rocking sections.
- 02
Elevation readings
Identify low points, the proposed target, and the fixed edges that limit how far the slab can move.
- 03
The likely cause
Look for erosion, drainage, poorly compacted fill, washout, or another reason support was lost. Mark what is observed and what is still an inference.
- 04
The repair material and plan
FHWA guidance describes cementitious grout and expansive polyurethane as slabjacking material categories. The proposal should name the actual system, injection pattern, and intended result.
- 05
Expected crack behavior
Leveling does not erase cracks. FHWA guidance also cautions that existing cracks can open during slabjacking.
- 06
The work around the slab
Drainage, joints, base repair, patching, load restrictions, and finish expectations should not be left as verbal assumptions.
Important boundary
A basement slab is not automatically a routine leveling job.
This comparison is about slabs-on-ground. When the slab is inside a building, connected to structural work, covering utilities, or affected by foundation movement, the evaluation has to account for those conditions before a lifting method is selected.
Regional application note / contractor-owned source
603 Basement Solutions treats concrete leveling as a condition decision.
603 Basement Solutions publishes concrete leveling across New Hampshire, Maine, and Massachusetts. Its current page starts with slab condition: repairable settled concrete may be a leveling candidate, while badly broken or crumbling concrete may need replacement.
For basement floors, 603 limits the service description to uneven concrete that is not acting as the building’s structural slab foundation. The page does not name one required material for every job.
This is contractor-owned service guidance. It is not independent performance evidence or a recommendation from this Guide.
Read the 603 concrete-leveling pageContractor-owned source ↗Primary sources / checked September 10, 2026