What's the difference between mudjacking and polyurethane foam?

Mudjacking pumps a heavy cement-and-soil slurry through 1–2 inch holes to float a sunken slab back up; polyurethane foam (polyjacking) injects a two-part resin through smaller holes that expands in seconds to lift it. Foam is much lighter (about 2–4 lb/ft³ versus 100+ lb/ft³ for slurry), cures in minutes instead of 24–72 hours, is waterproof, and uses smaller holes — but it costs roughly 2 to 3 times as much. Mudjacking is cheaper and well suited to large, heavy slabs; foam wins where soil is weak, water is a concern, or you need the surface back in service fast.

Can mudjacking fix my house foundation?

No — and this is the most important thing to understand before anyone drills a hole. Slab jacking and foam are flatwork tools: they level sunken concrete by filling voids beneath it. They do not transfer a settling house's load to competent soil the way push piers or helical piers do, so they are not a fix for deep structural settlement of a loaded foundation. They're excellent for a sunken driveway, sidewalk, patio, or garage floor. If a contractor proposes mudjacking the perimeter of a settling house, that's the wrong method for the problem.

How long does mudjacking last?

Typically several years, sometimes much longer, but it isn't generally considered permanent. The cement slurry is heavy enough to burden weak soil and contribute to re-settlement, and it's susceptible to washout and erosion if water moves under the slab. Polyurethane foam lasts longer — commonly cited at 20+ years — because it's lightweight and doesn't erode. Crucially, neither addresses the underlying soil cause: if the void keeps reopening because of drainage or expansive clay, you'll be back. Fix the water, not just the slab.

How much does slab jacking cost?

Mudjacking runs about $3–$6 per square foot, with typical small jobs landing around $500–$2,500. Polyurethane foam for flatwork runs about $5–$25 per square foot — the higher density and material cost is why it's 2–3 times mudjacking. Both are dramatically cheaper than structural underpinning, which is exactly why the temptation to misuse them on a settling house exists. Price the job by what's actually moving: flatwork leveling for flatwork, piers for a settling foundation.

How soon can I use the surface after slab leveling?

Polyurethane foam cures in about 15–30 minutes, so a driveway can often take traffic the same day — one reason the U.S. DOT prefers it for highway slabs. Mudjacking's cement slurry needs roughly 24–72 hours to cure before heavy use. If returning a driveway, garage, or business surface to service quickly matters, that cure-time difference is often the deciding factor between the two methods.

Will the drill holes be visible afterward?

Somewhat, with either method, though foam is tidier. Mudjacking uses 1–2 inch holes that are patched after the slurry is pumped — visible on close inspection. Foam uses smaller holes (around 5/8 inch or less), so the patches are less noticeable. On decorative or stamped concrete, ask to see the installer's patching work on a previous job; neither method leaves an invisible result, and the patch pattern is part of what you're buying.

Mudjacking or foam for my driveway?

For a standard residential driveway on reasonable soil, mudjacking is the budget-friendly choice and works well on large, heavy sections. Choose foam when the underlying soil is weak (slurry weight could worsen settlement), when water intrusion or washout is a concern, when you want minimal-visibility holes, or when you need the surface back in use within hours. Foam's precision and light weight are worth the premium in those cases; otherwise mudjacking does the job for less.

Does slab jacking fix the underlying soil problem?

No. Both mudjacking and foam fill the void under a slab and restore its level, but neither corrects why the void formed — washed-out fill, poor drainage, or expansive clay shrinking away from the slab. That's why drainage correction and moisture management matter alongside any leveling: the most common reason a leveled slab re-sinks is unmanaged water. For a settling house (as opposed to flatwork), the underlying cause is diagnosed by an engineer and addressed with piers, not slurry.

Is mudjacking the same as foundation leveling?

It's one narrow part of it. Foundation leveling is an umbrella term covering piering and lifting a settled house, shimming a pier-and-beam home, and jacking flatwork. Mudjacking is only the last of those — leveling sunken concrete flatwork by filling voids. Calling mudjacking 'foundation leveling' without that qualifier is how homeowners end up with the wrong method on a structural problem. See our foundation leveling overview for how the methods actually map to the job.

Mudjacking vs Foam Slab Leveling: Cost & When to Use (2026)

Mudjacking (slab jacking) and polyurethane foam leveling lift sunken concrete by filling the voids beneath it — slurry pumped through 1–2 inch holes for mudjacking, expanding resin through smaller holes for foam. They're inexpensive, fast, and genuinely excellent for sunken driveways, sidewalks, patios, and garage floors. They are also the most misused methods in foundation repair, because filling a void under a slab is not the same as transferring a settling house's load to stable soil. This page covers how both work, what they cost, and — the part most pages skip — exactly where the flatwork-leveling line stops and real foundation underpinning begins.

Slab Jacking, Mudjacking, Foam: The Terms Untangled

The vocabulary is muddier than the methods. Here's the plain-English map:

Slab jacking — the general category: lifting a slab by injecting material underneath it.
Mudjacking (also "mud jacking," "slurry jacking," "pressure grouting") — slab jacking with a cement-and-soil slurry. The original, heavier, cheaper method.
Polyurethane foam leveling (also "polyjacking," "foam jacking," "poly leveling") — slab jacking with a light, expanding two-part polyurethane resin. The newer, lighter, pricier method.

All three describe leveling flatwork — concrete that sits directly on the ground and carries little structural load. None of them describes underpinning a house, which is the distinction the rest of this page keeps coming back to.

How Mudjacking Works (Cement Slurry)

Mudjacking is a four-step process, and understanding it tells you both its strengths and its failure modes.

Drill injection holes. The crew drills 1–2 inch holes through the sunken slab in a grid pattern over the voids.
Mix and pump the slurry. A cement-based slurry — water, soil or clay, sand, cement, sometimes crushed limestone — is mixed and pumped under pressure through the holes. The slurry is heavy, often 100+ lb/ft³.
Fill voids and float the slab. As slurry fills the void beneath the slab and pressure builds, the slab lifts back toward level. The crew works hole to hole, watching the lift.
Patch the holes. Once the slab is level, the holes are patched with mortar and the slurry is left to cure — typically 24–72 hours before heavy use.

The mechanism is also the weakness: the slurry that does the lifting is heavy enough to load already-weak soil, and because it's cement-and-soil based, it's susceptible to washout and erosion where water moves under the slab. That's why mudjacking is "several years," not "permanent."

How Polyurethane Foam Leveling Works

Foam leveling (polyjacking) swaps the heavy slurry for a light, expanding resin and shrinks everything about the process.

Small holes — around 5/8 inch or smaller — are drilled, and a two-part polyurethane resin is injected. It reacts and expands within seconds to a couple of minutes, filling voids, lifting the slab, and densifying loose soil as it presses outward. Technicians watch the lift in real time and stop when level. Cured high-density foam is roughly 2–4 lb/ft³ with a compressive strength commonly around 80–100 psi, it's hydrophobic (won't wash away), and it sets in about 15–30 minutes — fast enough that the U.S. DOT prefers polyurethane for highway-slab stabilization where lanes must reopen quickly.

The trade-offs: foam costs more (often 2–3× mudjacking), its rapid expansion takes skill to control (over-lifting is the classic error), and — like mudjacking — it levels the slab without fixing why the void formed. For the deeper-injection soil-stabilization use of polyurethane, see our polyurethane foam page.

Mudjacking vs Polyurethane Foam (Comparison Table)

Dimension	Mudjacking (cement slurry)	Polyurethane foam
Material weight	Heavy (~100+ lb/ft³)	Light (~2–4 lb/ft³)
Hole size	1–2 in	~5/8 in or smaller
Cure / return to service	24–72 hr	~15–30 min
Water resistance	Erodes / washes out	Hydrophobic, waterproof
Typical lifespan	Several years	20+ years
Reaches tight voids	Can miss them	Yes
Burdens weak soil	Yes — can worsen settlement	No
Cost	$3–$6 / sq ft	$5–$25 / sq ft
Best for	Large, heavy slabs on a budget	Weak soil, water concerns, fast return, precision
Mudjacking vs polyurethane foam for concrete flatwork leveling. Neither addresses the underlying soil cause of the void.

What These Methods Fix — and the Line They Don't Cross

Where these methods are exactly right: a garage floor that's dropped at one corner, an apron or driveway that's pitched toward the house, a settled patio or AC pad, a sunken sidewalk that's become a trip hazard. For the garage case specifically, see our garage foundation guide. In all of these the slab carries little structural load, the void is shallow, and restoring level is genuinely the whole job.

What It Costs (2026)

These are 2026 planning numbers for flatwork leveling, not quotes — and deliberately separated from structural underpinning costs, because conflating the two is how homeowners get sold the wrong thing.

Scope	Typical range	Notes
Mudjacking, small flatwork job	$500–$2,500	Driveway section, patio, sidewalk
Mudjacking, by area	$3–$6 / sq ft	Large/heavy slabs are mudjacking's sweet spot
Polyurethane foam, by area	$5–$25 / sq ft	2–3× mudjacking; light, fast, waterproof
Garage floor leveling	$600–$2,000	Method depends on soil + load

For comparison, structural underpinning of a settling house runs $15,000–$30,000 for a typical 8–14 pier job — a different category of work entirely. The national average foundation project (This Old House, 2026) is about $5,179, blending everything from flatwork to full underpinning. For a focused estimate, see our leveling cost guide.

Lifespan, Washout & Re-Settlement

The durability question for slab leveling is really a water question. A leveled slab re-sinks when the void under it reopens — and voids reopen because water washes out fill, drainage pitches toward the slab, or expansive clay shrinks away in a dry spell. Mudjacking's heavy slurry is itself vulnerable to that washout and can add load to soil that's already failing; foam resists erosion and weighs almost nothing, which is why it holds up longer (20+ years is the common figure).

But the most reliable way to make any slab-leveling job last is unglamorous: fix the drainage. Gutters and downspout extensions that carry roof water away, grading that slopes away from the slab, and keeping perimeter moisture consistent all do more for longevity than the choice between slurry and foam. Level the slab, then fix the water — or you'll be drilling the same holes again. For the symptom side, see sloping floors.

FAQ Note

The questions below are the ones homeowners ask most once they realize slab leveling and foundation underpinning aren't the same thing — the mud-versus-foam choice, cost, cure time, durability, and the one that matters most: can this fix my house? For a settling home, the answer starts with an engineer's report, not a slab-jacking quote.

Get Matched With a Vetted San Antonio Slab-Leveling Specialist

Whether you've got a sunken driveway that needs flatwork leveling or a settling slab home that needs a proper diagnosis first, we'll match you with a vetted San Antonio specialist for the work that actually fits the problem — and we'll tell you which one it is. The match is free, the quote is no-obligation, and we don't take a fee from you. For flatwork we screen for clean patching and realistic lifespan claims; for anything structural we screen for sealed-engineer design and a clean Bexar County permit record. If a quote misuses slab jacking on a structural problem, we'll say so. That's the only way an editorial matching service should work.

Slab Jacking & Mudjacking: What It Fixes (and What It Doesn't)