Identify the slab and the problem
Make a simple plan showing the affected driveway, walk, patio, pool surround or floor. Mark joints, cracks and changes in height, then take photographs from several directions. Include nearby drains, downspouts, trees, walls and thresholds. Tell the contractor whether the change appeared recently, followed a plumbing leak, or has progressed over several seasons. These observations help define an inspection; they do not establish a cause.
Ask the assessor to distinguish a settled slab from an adjacent slab that has risen. Raising the wrong panel to chase a high edge can create a new step elsewhere. Where movement involves the building itself, request a separate explanation of structural assessment rather than treating all uneven concrete as ordinary flatwork.
Compare lifting, stabilization and replacement
Ask each bidder to describe the intended result in plain language. Lifting changes the slab’s elevation; stabilization may aim to fill loss of support without substantially raising it. Replacement removes and rebuilds the concrete. The Federal Highway Administration’s pavement preservation guide discusses stabilization and slab jacking as related but different procedures, and describes both cement grout and polyurethane materials. Its roadway guidance is background, not a design for your property.
Have the contractor explain why the selected method fits the slab’s condition. Extensive deterioration, awkward connections, or movement that cannot be corrected within available clearances may change the recommendation. Ask for the alternative of doing nothing temporarily, investigating further, or replacing selected panels instead of accepting a single predetermined solution.
Define the target elevation and drainage
A quote that promises to make everything level leaves an important question unanswered: level relative to what? Exterior concrete often needs a deliberate drainage direction. Ask where the contractor intends water to go and what will happen at the garage entrance, doorway, pool coping and adjoining walk. Have any practical limits recorded before injection begins.
For a larger area, request baseline measurements and agreed reference points. Describe whether the priority is reducing a trip edge, restoring a threshold transition, improving drainage, or recovering a particular elevation. These goals may not all be achievable together. A written explanation of the compromise is more useful than a broad promise of perfection.
Ask what happens below the surface
The visible depression is only part of the proposed work. Ask what information supports the estimated voids or loss of support, how the crew will monitor movement, and what would cause it to stop. A bidder should distinguish observations from assumptions and explain how unexpected material consumption is priced. Do not equate the number of injection holes with the completeness of the repair.
If a leak, erosion path or drainage defect is suspected, identify who investigates it and whether correction belongs in this contract. Lifting concrete while leaving an active source of soil loss unresolved may not address the full problem. Keep plumbing investigation, drainage changes and structural work as explicit responsibilities.
Compare the material and the scope
For foam proposals, request the product identification and an explanation of why it is appropriate for the application. For grout proposals, ask what mixture and placement approach are planned. Rather than trying to select a product from a sales brochure alone, compare the contractor’s assessment, control of the lift, cleanup obligations and response if the desired elevation cannot be reached.
Both quotes should identify the same panels and exclusions. Record access arrangements, protection of landscaping, injection-hole patching, joint treatment, crack repair and disposal. If a contractor proposes a separate surface coating, ask whether that is cosmetic and whether it would conceal cracks you need to monitor. Material names alone do not make two bids equivalent.
Check price assumptions without relying on an average
A useful price is tied to the actual work boundary. Ask whether the amount is fixed for the described result or depends on hours, material quantities, visits or additional holes. Have the bidder describe what counts as an unforeseen condition and how you approve extra work. A small low-priced repair can become difficult to compare when return trips, joint sealing and cleanup are excluded.
For several slabs, request enough itemization to distinguish essential work from optional panels. This also lets you discuss a staged approach without guessing which part of the quote disappeared. Do not assume that a neighbor’s total is a reliable benchmark when access, voids, slab condition and finishing differ.
Read the warranty against the actual problem
Separate a promise about materials from a promise about future movement. Ask what amount or type of movement triggers a return visit, how long coverage lasts, whether coverage transfers, and which conditions void it. Changes in drainage, plumbing failures, new loads or repairs by another contractor may be treated differently. Read the written terms rather than relying on a long headline warranty.
Also ask what happens if the agreed correction is not achieved during the original visit. A warranty is not a substitute for a completion standard. The contract should explain the remedy for incomplete lifting, damage, unacceptable patching or a new drainage conflict identified during the walkthrough.
Inspect the finished work
Walk the repaired route with the contractor before treating the job as complete. Compare the agreed reference points, check transitions at the edges of the work and look at injection-hole patches. Where drainage was part of the scope, ask how the contractor proposes to demonstrate the result without directing water into the building. Keep dated photographs and the written description of any remaining difference in elevation.
Get product records, final scope changes, invoice and warranty together. Ask when vehicles or normal use can return for the specific treatment installed; do not borrow a generic cure time from another product. Record any monitoring or maintenance the contractor recommends, including who should investigate movement beyond the repaired panels.
Sources and scope
Official sources support the regulatory and technical points identified below. General comparison advice is editorial guidance. Local examples apply only to their stated jurisdiction; a site assessment determines which conditions apply to your property.
- Federal Highway Administration ↗
Distinguishes slab stabilization from slab jacking and describes cement grout and polyurethane materials; highway context, not a residential specification.