Facility managers researching a sunken slab eventually run into the same fork in the road: mudjacking or foam jacking. Both methods raise settled concrete back to grade. Both work by filling the void underneath. Beyond that, they’re different enough that the choice actually matters for a facility trying to minimize downtime and long-term maintenance costs.
Worth noting upfront: Poly-Mor does not offer mudjacking. We work exclusively with polyurethane foam injection, and this guide is written to give facility managers and engineers an honest, factual comparison rather than a one-sided pitch. You can review our approach on the slab lifting service page, but let’s get into what actually separates these two methods on a commercial job site.
Mudjacking, sometimes called slab jacking, pumps a slurry mix of soil, cement, and water beneath a settled slab through holes roughly one to two inches wide. The material is heavy and needs time to cure and gain strength once it’s in place.
Foam jacking uses a two-component polyurethane resin injected through much smaller holes, often less than an inch across. The two parts react on contact, expanding rapidly and reaching workable strength within minutes rather than days.
Both methods raise the slab. The mechanics of how they get there, and what they leave behind underneath the concrete, are where the real differences show up.
| Factor | Mudjacking | Polyurethane foam jacking |
|---|---|---|
| Load capacity added to soil | Heavy; slurry mix adds significant weight, which can stress already weak subgrade | Minimal; foam weighs only a few pounds per cubic foot, adding negligible load |
| Cure time | Typically 24 to 48 hours before full load can return | Reaches workable strength in 15 to 30 minutes |
| Longevity | Can settle again if underlying soil issues aren’t resolved, given the added weight | Tends to hold longer since it doesn’t add mass that can re-compress soil |
| Downtime for the facility | Extended; area often needs to stay clear of traffic for a full day or more | Short; area is typically ready for equipment or foot traffic same day |
| Hole size | 1 to 2 inches, more visible patching required | Under 1 inch, minimal patching |
| Precision of lift | Harder to fine-tune; slurry flow is less controllable | Highly controllable; technicians can adjust lift in small increments |
For a facility trying to keep a loading dock, production floor, or equipment pad operational, that downtime row carries a lot of weight in the decision. A day or two of restricted access in an active warehouse isn’t a minor inconvenience. It affects scheduling, staffing, and sometimes contractual delivery windows.
Here’s the part that often gets missed: the same soil weakness that caused the original settlement is still there after a mudjacking repair. Slurry mix adds real weight on top of that already-compromised ground. In some cases, that additional load accelerates renewed settlement, particularly under heavier commercial and industrial loads like racking systems, forklifts, or production equipment.
Polyurethane foam doesn’t carry that same risk. Because it’s so light, it fills the void and restores support without meaningfully adding to the load the subgrade has to bear. For a facility where the slab is already under repeated heavy use, that difference tends to matter more over a multi-year timeline than it does for a single lightly-loaded residential patio.
Picture a manufacturing facility outside Edmonton where a section of floor near a stamping press had settled just enough to throw off equipment leveling. The line had to be shut down periodically to reset calibration, a hidden cost that wasn’t showing up on any maintenance budget line but was quietly eating into production hours every month.
The facility’s engineering team weighed both options. Mudjacking would have meant clearing the area for at least a day, waiting on cure time, and accepting the additional weight sitting on soil that was already the root cause of the problem. Foam jacking let the crew work a weekend shift, inject through a handful of small entry points, and have the floor level and load-tested before the Monday shift started. The press was recalibrated once, and the fix has held without the recurring settlement the team had been bracing for.
Some contractors still use mudjacking, often because it’s a familiar, established method with lower material costs on paper. It can work adequately for lightly loaded, non-critical applications where downtime isn’t a major concern and the underlying soil isn’t a chronic problem. For a shed pad or a low-traffic sidewalk section, the tradeoffs matter less.
For commercial and industrial slabs carrying real operational weight, though, the downtime, added load, and cure-time factors tend to tip the decision toward polyurethane. That’s the honest reason Poly-Mor made foam jacking its focus rather than offering both methods.
If you’re evaluating quotes or proposals for a settled commercial slab, a few questions tend to surface the right answer faster than a generic comparison ever will. How much weight will the repair material itself add to soil that’s already shown it can’t fully support the slab? What’s the realistic cure time before the area can handle full equipment traffic again? And how many injection or fill points will the job need, since that number affects both patching visibility and how finely the lift can be controlled.
It also helps to ask what happens if the repair crew finds a larger void than expected once work starts. A contractor who can answer that clearly, rather than vaguely, is usually one who’s done this enough times to know what commercial slabs actually throw at them.
Neither method is a permanent guarantee against future settlement if the underlying soil or drainage conditions keep causing problems. What differs is how each method interacts with those ongoing conditions. Because foam doesn’t add meaningful weight, it doesn’t compound an existing soil weakness the way a slurry fill can. That’s part of why facilities dealing with chronic soil issues, rather than a one-time settlement event, tend to see more consistent long-term results with polyurethane injection.
The right choice depends on load requirements, how much downtime your operation can absorb, and what’s actually happening in the soil underneath your slab. A site assessment can tell you which factors matter most for your specific facility before you commit to either approach.
No. Poly-Mor works exclusively with polyurethane foam injection for concrete lifting. This guide compares both methods factually so facility managers can understand the tradeoffs, but our service and expertise are focused on the foam-based approach.
Polyurethane foam reaches workable strength in about 15 to 30 minutes, letting the area return to service the same day. Mudjacking slurry typically needs 24 to 48 hours to cure fully before it can safely bear full load again.
The soil beneath a settled slab is already weaker than it should be. Mudjacking’s slurry mix adds significant weight on top of that same soil, which in some cases can contribute to renewed settlement, especially under heavy commercial or industrial loads.
Yes, it’s commonly used for exactly this kind of application. Because the foam is lightweight and cures quickly, it’s well suited to production floors, loading docks, and equipment pads where minimizing added load and downtime both matter.
Typically much less disruptive than mudjacking. Smaller holes, faster cure time, and same-day return to service mean most commercial foam jacking projects can be scheduled during a slower shift or weekend without a full operational shutdown.
