Polyjacking - lifting concrete with expanding foam

What is polyjacking?

Polyjacking (polyurethane foam slab jacking) lifts concrete by injecting a two-component polymer through small holes; the foam expands under the slab, fills voids and raises the panel with far less added weight than cementitious slurry. Ports are typically smaller, patches are less conspicuous, and many exterior slabs return to service quickly once the foam sets.

Signs you need polyjacking

• Sunken driveway, sidewalk, patio or pool-deck panels with the concrete still largely intact
• A garage floor or apron dropped at the threshold creating a gap or trip lip
• You want smaller injection ports than traditional mudjacking leaves
• Weak soils where adding heavy slurry mass is a concern
• A need to reopen a driveway or walk on a patio on a short timeline
• Hollow-sounding areas suggesting voids under an otherwise solid slab

Seeing something not on this list? Browse concrete problems by symptom →

How polyjacking actually works

1. 1

   Assess slab integrity and void pattern

   Foam can lift sound panels and knit support under them; it cannot glue together a slab that has shattered into many unstable pieces. The technician maps low spots, joints and likely void zones before drilling.

   Watch forFoam sold as a cure for severely spalled or fragmented concrete. Leveling does not restore surface durability.

2. 2

   Control water and identify washout

   Expanding foam fills space; it does not seal every soil pipe or stop a downspout that keeps carving channels. Causes get named before injection so the lift is not temporary.

   Watch forSame-day foam with zero conversation about drainage. That is product application, not problem solving.

3. 3

   Small-diameter ports in a planned grid

   Holes are drilled in a pattern that allows staged lifting. Diameter is typically much smaller than slurry ports, which is why polyjacking is popular on visible flatwork.

   Watch forExcessive holes "just in case". Pattern should match the low areas, not a default template for every job.

4. 4

   Inject, expand, and meter the lift

   The components mix at the gun, expand under the slab and generate lift. Crews watch elevations carefully - foam expansion continues briefly after injection, so experienced technicians stop short of the final target and let the material finish.

   Watch forAggressive over-injection. Overlift and pressure can crack panels, especially thin residential slabs.

5. 5

   Patch ports and reopen carefully

   Holes are filled flush. Foam typically reaches handling strength quickly compared with cementitious fills, which is a practical advantage for driveways and entries - still follow the crew's traffic guidance for your mix and temperature.

   Watch forPromises of "instant" heavy truck traffic in freezing weather without conditions. Chemistry still cares about temperature.

6. 6

   Seal joints and finish drainage work

   Open joints that fed the void should be addressed, and edge grading corrected so the next storm does not restart washout.

   Watch forFoam-only invoices with drainage marked "owner responsibility" in fine print you did not notice.

7. 7

   Plan access for hoses and equipment without wrecking landscaping

   Foam rigs need staging space. Protect lawns, irrigation heads and soft stone. Confirm whether furniture, vehicles and gates must be cleared before arrival so the crew is not improvising paths across planting beds.

   Watch forNo access plan on a backyard patio job with no side-yard width. That is how fences get cut without warning.

What does polyjacking cost?

Polyjacking is commonly priced by area lifted or by amount of foam used. Material cost per unit volume is often higher than slurry, but smaller ports, speed and low weight can make the installed job competitive - especially on driveways and slabs where downtime matters. Compare scope, warranty and drainage work, not foam brand slogans.

See the full polyjacking cost guide - by material, size and region →

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