Methods
Polyjacking: Polyurethane Concrete Lifting
Polyjacking raises a settled slab by injecting an expanding polyurethane beneath it. It is widely used, genuinely useful — and not automatically the right answer for every slab.
What polyurethane concrete lifting is
A two-component polyurethane is combined at the injection point and delivered under the slab. The components react, the material expands to fill the space it finds, and continued injection converts that expansion into controlled lift. Because the material travels into the void rather than being troweled into place, it can reach areas a crew cannot see.
The same material and process is marketed under many brand names. What matters when you compare quotes is the scope — where ports go, how the lift will be controlled, and what restoration is included.
How the injection works, step by step
- The settled area is assessed and the intended lift pattern is planned.
- Small-diameter ports are drilled through the slab at chosen locations.
- Material is injected in stages, starting where support has been lost.
- The void fills first; the slab begins to move once the space is taken up.
- Lift is monitored across the slab and injection is adjusted between ports.
- Ports are patched and joints addressed as agreed.
Typical applications
Driveways and aprons
Sidewalks
Garage floors
Patios and porch slabs
Void filling
Commercial walkways
Ports, cure time and void filling
Injection ports
Polyurethane is normally injected through small-diameter ports — smaller than the holes associated with slurry methods. They are patched afterwards and generally remain visible on close inspection. Ask how many ports your job needs and where they will fall.
Cure behaviour
The reaction is fast relative to a cement slurry, which is why same-day return to service is commonly discussed. Actual timing depends on the product, the conditions and the job, so treat it as something the provider confirms, not a fixed number you can rely on from a web page.
Filling voids
Because the material expands into the space available, polyurethane is often used where a void is the central issue. That does not mean every void requires foam — see void filling for the wider picture.
Advantages and limitations
Where it tends to help
- Lightweight fill compared with a cement slurry
- Small injection ports
- Fast set, often meaning short downtime
- Material travels into voids that are hard to reach
- Works well for controlled, incremental lift
Where it is limited
- Generally higher per-square-foot cost than mudjacking in national data
- Does nothing for concrete that has fragmented or deteriorated
- Does not correct a site drainage or grading problem
- Cannot restore support that keeps eroding away
- Not a substitute for evaluating why the slab moved
One thing we will not tell you
When another approach may be better
- Budget is the deciding constraint and the slab is a straightforward candidate for a slurry method — see mudjacking.
- The concrete is broken up rather than merely low — see leveling vs replacement.
- Water is the real story and the slab is a symptom — see water pooling.
What drives polyjacking cost
Material volume is the biggest variable, and it is a function of the void, not just the surface area. Beyond that: number of slabs, depth of settlement, number of injection locations, access, and any restoration in scope. National consumer datasets generally report polyurethane lifting at a higher per-square-foot cost than traditional mudjacking. Detailed ranges are on the cost guide.
Homeowner questions
How much does polyjacking cost per square foot?
National consumer reporting puts polyurethane lifting above traditional mudjacking per square foot, but the spread is wide because void volume drives material use. Our cost guide gives planning bands and explains why published ranges disagree.
Will polyjacking stop my slab from sinking again?
It restores elevation and fills the void it finds. Whether the slab stays level depends on whether the cause — usually water movement or unconsolidated fill — has been addressed.
Is polyurethane lifting safe around plants and soil?
This is a product-specific question and a fair one to put to the provider, along with a request for the product data sheet for the material they intend to use.
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