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Polyjacking — lifting concrete with expanding foam

Polyurethane foam injection raises sunken slabs through small drilled ports. The foam expands to fill voids, adds little weight, and often lets you walk or drive sooner than cementitious slurry methods — when the slab and soil are right for it.

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In short

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.

Triggers

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

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The job

How polyjacking actually works

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 for: Foam sold as a cure for severely spalled or fragmented concrete. Leveling does not restore surface durability.
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 for: Same-day foam with zero conversation about drainage. That is product application, not problem solving.
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 for: Excessive holes "just in case". Pattern should match the low areas, not a default template for every job.
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 for: Aggressive over-injection. Overlift and pressure can crack panels, especially thin residential slabs.
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 for: Promises of "instant" heavy truck traffic in freezing weather without conditions. Chemistry still cares about temperature.
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 for: Foam-only invoices with drainage marked "owner responsibility" in fine print you did not notice.
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 for: No access plan on a backyard patio job with no side-yard width. That is how fences get cut without warning.

Money

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 →

Straight answer

When polyjacking is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

You need a stamped structural engineer for house foundation movement and were quoted foam for the basement walls without engineering. Wrong product category — stop and re-scope under foundation repair.
The concrete is at the end of its life structurally or cosmetically. You will own a level slab that still needs replacement soon.
Settlement is structural foundation movement. House foundations need foundation-repair methods, not flatwork foam marketing.
A large open washout is still active and unfixed. Foam in a river of fines is a short story.
You need bulk deep fill where a different civil approach applies. Some deep voids and under-sealing jobs are engineered differently than residential slab jacking.
Local fire or chemical concerns restrict certain foams in enclosed spaces and the area is interior with special rules — confirm product suitability.
A single-method foam company cannot explain when slurry would be better. Honest fit matters more than brand loyalty.

Your options

Types of polyjacking

Concrete leveling overview

Side-by-side method framing.

Mudjacking

Cementitious slurry lifting.

Concrete repair

Surface and crack work after lift.

Concrete demo

When panels should come out.

Compare concrete options side by side →

Before you sign

What to check when hiring for polyjacking

Why foam rather than slurry for this specific slab and soil?

Forces a site reason, not a brochure reason.
What foam density and system do you use, and is it appropriate under my slab type?

Not all polyurethane systems are identical in structure and reaction profile.
How do you prevent overlift during expansion?

The critical skill difference between careful and careless foam work.
What does the warranty cover if the panel settles again?

Clarify exclusions for drainage and owner grading changes.
When can I drive, park, or replace furniture?

Speed is a selling point — get it in writing for your weather window.
Are joint sealing and downspout corrections included?

Often the difference between a three-year and a ten-year result.
How will you protect adjacent walls, pool water and planting from foam or drill dust?

Site protection should be specific.
Can I see an example of port patches on a similar finish?

Sets cosmetic expectations honestly.

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Local pros

Polyjacking near you

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Related work

Often done at the same time

Concrete Leveling

Neutral method comparison

Mudjacking

Slurry-based lifting

Concrete Repair

After the slab is level

Patio Concrete

When replacement makes more sense

All concrete services →

FAQ

Polyjacking — questions people ask

Still have a question? Talk to our team →

Is polyjacking the same as mudjacking?

No. Both lift slabs by filling voids, but mudjacking uses cementitious slurry through larger holes, while polyjacking uses expanding polyurethane through smaller holes with much less added weight. They are competing methods for related problems, not two names for one process.

How small are the holes?

Foam ports are typically much smaller than traditional mudjacking holes — often described in the penny-to-nickel size class rather than larger slurry ports — then patched. Exact diameter depends on the contractor's equipment.

Does foam waterproof the soil?

Foam can densify and occupy voids; it is not a substitute for waterproofing a foundation or fixing plumbing leaks. Treat water sources separately.

How fast can I use the slab?

Many residential polyjacking jobs allow light use the same day and vehicle traffic soon after, subject to temperature and product. Ask your installer for the specific window rather than assuming marketing copy applies in cold weather.

Can foam lift a pool deck?

Often yes when panels are intact and access is safe. Equipment, chemical handling near water features and joint details need a crew experienced with decks — not every driveway foam crew is interchangeable.

Will polyjacking stop new cracks?

It addresses support voids. Cracks from shrinkage, overload or ongoing movement can still appear. Existing cracks may be sealed separately after elevations are correct.

Does polyurethane foam keep expanding forever?

No. Expansion is designed to complete during and shortly after injection. Crews account for that short continuation when they stop short of final grade. Uncontrolled ongoing expansion is not how these systems are supposed to behave; if something seems to keep moving days later, call the installer — that is not normal "settling in".

Is polyjacking messy compared with mudjacking?

Foam jobs usually leave smaller ports and less cement film, which is why they are popular on visible flatwork. There can still be drill dust, rinsed residue and protected landscaping. "Clean" is relative to slurry, not the same as zero site impact.

Can foam lift an interior basement slab?

Sometimes, when access, ventilation and product suitability allow. Interior work has different dust, odour and fire-code considerations than a driveway. Confirm the product and method are intended for enclosed residential spaces before you approve the visit.

What questions expose a foam-only sales pitch?

Ask when slurry would be better for your slab, what soil and water evidence they collected, and how they prevent overlift. Vague answers that only attack "the other method" without site specifics are a pitch. Method fit should sound like diagnosis, not brand loyalty.

Does foam help with insulation under a slab?

Some polyurethane systems have insulating properties, but residential slab jacking is primarily a structural support and void-fill service, not a substitute for designed under-slab insulation upgrades. Do not buy jacking solely for energy claims without a clear thermal design.

What temperatures limit polyjacking?

Very cold weather can slow reaction and change handling; extreme heat affects working time. Installers should state seasonal limits for their product. If they shrug at a freeze warning, get a second opinion.

How should I prepare for a polyjacking visit?

Move vehicles, unlock access gates, secure pets, and clear furniture from patio panels being lifted. Point out sprinkler heads and shallow private utilities. Ask where the crew will stage hoses so you can protect soft landscaping in advance.

Can polyjacking fix trip hazards on municipal sidewalks?

Sometimes private crews lift public walks under permit or municipal programmes; rules vary widely. Liability and permit ownership matter more than method. Do not assume a driveway foam crew can legally work on city sidewalk without authorisation.

Polyjacking — lifting concrete with expanding foam

What is polyjacking?

Signs you need polyjacking

How polyjacking actually works

What does polyjacking cost?

When polyjacking is the wrong call

Types of polyjacking

Concrete leveling overview

Mudjacking

Concrete repair

Concrete demo

What to check when hiring for polyjacking

Polyjacking near you

Often done at the same time

Concrete Leveling

Mudjacking

Concrete Repair

Patio Concrete

Polyjacking — questions people ask

Get polyjacking done right.

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