Frequently Asked Questions
Answers about concrete slab repair, leveling, polyurethane slab jacking, project timing, costs, and maintenance.
What is slab jacking?
Concrete leveling, slab jacking, mudjacking, and concrete lifting are terms for processes that raise a settled concrete slab by injecting material beneath it.
What can be slab-jacked?
Many concrete surfaces can be slab-jacked, including driveways, steps, patios, pool decks, basement and garage floors, sidewalks, parking areas, loading docks, and warehouse floors. Severely broken concrete may be better suited for replacement, so an inspection is recommended.
How much money can I save with slab jacking?
Slab jacking can cost substantially less than removing and replacing concrete. Actual savings depend on the slab condition, access, settlement, and project size.
How long does slab jacking take?
Many slab-jacking projects take only a few hours. Larger or more complex projects may take longer, but residential work is often completed within one day.
How soon can my project be completed?
Scheduling depends on the current workload and project requirements. After an estimate is accepted, the team will provide an expected service date and project duration.
How much room do you need to work?
Space requirements depend on the project. Trucks can usually remain on the street, while compact pumping equipment can fit through most gates. Injection lines can also reach some interior or restricted areas.
Why level concrete instead of replacing it?
When the existing slab is structurally sound, leveling is generally faster, less disruptive, and more economical than demolition and replacement. It also keeps usable concrete out of landfills.
How long will slab jacking last?
A properly completed repair can last for many years. Long-term performance also depends on drainage, soil conditions, erosion, and whether the original cause of settlement has been addressed.
How does slab jacking compare with replacement costs?
Slab jacking is commonly less expensive than concrete removal and replacement because it requires less demolition, material, labor, and cleanup. A site inspection is needed for an accurate comparison.
When is slab jacking not appropriate?
Slab jacking may not be suitable when concrete is severely cracked or deteriorated, when attached structural elements prevent movement, or when nearby retaining walls create unacceptable constraints. Each site should be evaluated individually.
Is maintenance needed after concrete leveling?
Good drainage and sealed joints help protect the repaired area. Recommended maintenance depends on the slab, surrounding soil, and water conditions.
How can rodents create concrete problems?
Burrowing animals can create tunnels beneath slabs or near foundations. Water entering those tunnels may wash away supporting soil and contribute to settlement or void formation.
When can I drive on the repaired driveway?
Return-to-service time depends on the lifting material and project conditions. The crew will provide specific instructions after the repair is complete.
Will my concrete crack during lifting?
Existing concrete can crack as it is lifted, especially when hidden stress cracks or severe settlement are present. Careful measurement and controlled lifting reduce the risk, but no contractor can guarantee that an existing slab will never crack.
Will my yard or sprinkler system be damaged?
The process is designed to minimize disturbance. Soft ground can develop minor equipment ruts, and poorly placed sprinkler lines close to the slab may be vulnerable as the concrete moves.
Should I expect movement after the work is complete?
Minor movement may occur while materials cure. Continued movement after the curing period can indicate unresolved drainage, erosion, or soil-compaction problems and should be inspected.
Does concrete leveling make a lot of noise?
Drilling and pumping equipment create some noise, but the process is generally less disruptive than concrete demolition and replacement.
Does concrete leveling create dust or debris?
Drilling creates a limited amount of dust and debris. Dust-control equipment and cleanup procedures help keep the work area clean.
Will the patched holes match my existing concrete?
Injection holes are patched after lifting. New patch material may initially differ slightly in color from weathered concrete and usually blends in better over time.
Why does concrete sink?
Concrete commonly sinks when supporting soil settles, erodes, was not compacted properly, or develops voids. Poor drainage and repeated water movement can make settlement worse.
What problems can occur with slab jacking?
Potential issues include cracking during lifting, incomplete correction, or renewed settlement if drainage and soil problems continue. A proper inspection helps determine whether leveling is appropriate.
How does slab jacking work?
Small holes are drilled through the slab, lifting material is injected beneath the concrete, and the slab is raised in controlled increments. The holes are patched after the target position is reached.
How long has slab jacking been used?
Concrete-lifting methods have been used for decades. Modern polyurethane systems use lightweight expanding foam and smaller injection holes than traditional mudjacking.
What are the benefits of slab jacking over replacement?
Benefits can include lower cost, faster completion, less demolition, reduced waste, and a shorter interruption to normal use when the existing slab is suitable for lifting.
What is a void beneath concrete?
A void is an unsupported space beneath a concrete slab. Voids can form because of erosion, soil settlement, poor compaction, leaking water, or construction conditions.
Can any concrete slab or block be raised?
Many slabs can be raised or leveled, but suitability depends on concrete condition, reinforcement, access, nearby structures, and the underlying soil. Severely damaged concrete may require replacement.
Can concrete slabs be lowered?
Lowering a slab is less common than raising it and may require different techniques or partial replacement. The available options depend on the slab and surrounding structures.
Can sunken front steps be raised?
Many sunken concrete steps can be lifted and the resulting voids filled. An inspection is needed to confirm that the steps and attached structures can move safely.
Can a sidewalk lifted by tree roots be leveled?
Leveling may correct the immediate trip hazard, but the tree roots must also be evaluated. Continued root growth can move the sidewalk again.
Will injection holes differ in color from the existing concrete?
Fresh patch material may be slightly different in color from older concrete. Weathering generally makes the contrast less noticeable over time.
How and when is concrete grinding used?
Grinding removes small high spots and can reduce minor unevenness. It may be used when lifting is unnecessary or as a finishing method for limited surface transitions.
How many injection holes will there be?
The number of holes depends on slab size, thickness, settlement, void locations, and the lifting material. The crew plans hole placement to achieve a controlled lift.
What lifting material do you use?
Seattle Slab Jack uses project-appropriate materials selected for controlled lifting and stable support. The recommended approach depends on site conditions and the type of concrete being repaired.
How quickly does the lifting material cure?
Cure time varies by material. Polyurethane foam cures quickly, while cement-based slurry takes longer. Injection holes are patched after lifting is complete.
How will the work affect my landscaping?
The crew works to minimize disturbance and clean the work area after completion. Access conditions and soft soil can affect how much temporary disruption occurs.
What is mud filling for walls?
Mud filling uses a cementitious mixture to fill accessible gaps or voids. It is different from structural wall repair, and an inspection is required to determine the appropriate method.
What causes slabs to sink or develop voids?
Common causes include soil erosion, poor compaction, water movement, leaking drainage systems, organic material decay, and changes in the supporting soil.
Does slab jacking indicate a structural problem?
Not necessarily. Slab settlement often affects nonstructural concrete such as sidewalks, patios, and driveways. Structural concerns should be evaluated separately by an appropriately qualified professional.
How can I reduce the chance of future settlement?
Maintain positive drainage, repair leaks, seal appropriate joints, control erosion, and address soil-compaction problems. Prevention recommendations depend on the cause of the original settlement.
Are slab-jacking contractors licensed?
Licensing requirements vary by location and project type. Property owners should verify the contractor's current license and insurance before work begins.
Is a building permit required?
Permit requirements vary by jurisdiction and project scope. Check with the local building department or ask the contractor which requirements apply to the project.