Two Ways to Lift Sunken Concrete

If your driveway, sidewalk, or patio has started to sink, you’ve probably come across two main options for fixing it: mudjacking and foam jacking (also called polyjacking or polyurethane foam leveling). Both methods lift settled concrete slabs back to their original position, but they take very different approaches to get there.

Understanding the differences matters because the method you choose affects how long the repair lasts, how much it costs over time, and how well it holds up in Minnesota’s demanding climate. Let’s break it down.

What Is Mudjacking?

Mudjacking is the older of the two methods, used since the 1930s. The process involves drilling large holes (typically 1 to 2 inches in diameter) through the sunken slab. A mixture of water, soil, sand, and cement — often called “slurry” or “mud” — is then pumped under the slab through those holes. The weight and volume of the slurry push the concrete back up to the desired level.

Once the slab is in position, the holes are patched with cement and the slurry cures over the following days.

What Is Foam Jacking?

Foam jacking uses high-density polyurethane foam instead of a cement slurry. The process starts with much smaller holes — typically 5/8 inch in diameter. A two-part polyurethane resin is injected beneath the slab, where it expands to fill voids and lift the concrete. The foam sets in about 15 minutes and reaches full strength within an hour.

This is the method we use at Inline Concrete for concrete leveling throughout the Twin Cities, and there are good reasons for that.

Head-to-Head Comparison

Here’s how the two methods stack up across the factors that matter most to homeowners.

Hole Size and Appearance

  • Mudjacking requires 1- to 2-inch holes, which are visible after repair and can be difficult to blend with existing concrete.
  • Foam jacking uses 5/8-inch holes — about the size of a dime. They’re far less noticeable once patched.

If curb appeal matters to you, foam jacking leaves a much cleaner result.

Weight of the Material

  • Mudjacking slurry is heavy — it can add significant weight beneath slabs that are already sitting on weak or poorly compacted soil. This added load can actually contribute to future settling.
  • Polyurethane foam weighs roughly 2 to 4 pounds per cubic foot, a fraction of what slurry weighs. It lifts the slab without overloading the soil beneath it.

This is one of the most important differences, especially for slabs on clay-heavy soils common in the Minneapolis-St. Paul area.

Cure Time and Usability

  • Mudjacking requires 24 to 72 hours before the repaired area can handle normal traffic.
  • Foam jacking cures in about 15 minutes. You can walk and drive on the repaired surface the same day.

For busy households, this difference alone can be a deciding factor.

Water Resistance

  • Mudjacking slurry is porous. It absorbs water over time, which causes it to break down, erode, and wash away — particularly problematic in areas with poor drainage.
  • Polyurethane foam is a closed-cell material. It doesn’t absorb water, period. It won’t erode, wash out, or deteriorate from moisture exposure.

In Minnesota, where we deal with snowmelt, heavy spring rains, and freeze-thaw cycles for months on end, this is a critical advantage for foam.

Longevity

  • Mudjacking repairs typically last 3 to 7 years before the slurry begins to break down or wash away, requiring re-leveling.
  • Foam jacking repairs are expected to last 10 years or more. The polyurethane material doesn’t shrink, decompose, or lose its structural integrity.

Precision

  • Mudjacking offers less control over the lift. The heavy slurry is harder to manage in small increments, which can lead to over-lifting or uneven results.
  • Foam jacking allows for precise, controlled lifting. Technicians can adjust in real time as the foam expands, dialing in accuracy down to fractions of an inch.

Pros and Cons at a Glance

Mudjacking

Pros:

  • Lower upfront cost in some cases
  • Widely available
  • Uses natural materials

Cons:

  • Heavy material can cause re-settling
  • Absorbs water and erodes over time
  • Larger, more visible drill holes
  • Longer cure time (24-72 hours)
  • Shorter lifespan (3-7 years)
  • Less precise lifting

Foam Jacking

Pros:

  • Lightweight material won’t overload soil
  • Waterproof and erosion-resistant
  • Tiny, barely visible drill holes
  • Cures in 15 minutes
  • Long-lasting (10+ years)
  • Extremely precise lifting
  • Effective void filling capability

Cons:

  • Slightly higher upfront cost than mudjacking
  • Requires specialized equipment and trained technicians

Cost Comparison

Mudjacking typically costs between $3 and $6 per square foot. Foam jacking generally runs $5 to $10 per square foot, depending on the scope of the project and the severity of the settling.

At first glance, mudjacking looks cheaper. But cost per square foot doesn’t tell the whole story.

When you factor in longevity, mudjacking’s lower upfront cost often leads to higher total cost over time. If a mudjacking repair lasts 5 years and needs to be redone, you’re paying twice (or more) for what a single foam jacking repair could have handled for a decade or longer.

Both methods cost significantly less than full concrete replacement, which typically runs $8 to $15 per square foot — and that doesn’t include the cost of demolition and disposal. For a full breakdown of what to expect, check out our guide on how much concrete leveling costs.

Why Foam Jacking Makes More Sense in Minnesota

Minnesota’s climate is tough on concrete and even tougher on the materials used to repair it. Here’s why foam jacking is the better choice for our region.

Freeze-thaw cycles. Water that seeps into mudjacking slurry expands when it freezes and contracts when it thaws. Over a Minnesota winter, this happens dozens of times, gradually destroying the slurry from the inside out. Polyurethane foam doesn’t absorb water, so freeze-thaw cycles have no effect.

Clay soils. Much of the Twin Cities sits on clay-heavy soil that expands when wet and contracts when dry. Adding thousands of pounds of heavy slurry on top of this unstable base is counterproductive. Lightweight foam avoids this problem entirely.

Spring runoff. Heavy snowmelt and spring rains can wash mudjacking slurry out from beneath slabs, especially if drainage is poor. Waterproof foam stays put.

Short construction season. Minnesota homeowners need repairs that last. Choosing a method that might need to be redone in a few years wastes both money and the limited window of good weather we have for outdoor work.

Which Method Should You Choose?

If you’re looking for the lowest possible upfront cost and don’t mind potentially re-doing the work in a few years, mudjacking can be a functional option. It’s a proven technique that has worked for decades.

But if you want a repair that lasts, looks better, cures faster, and stands up to everything Minnesota weather throws at it, foam jacking is the stronger choice on nearly every measure.

At Inline Concrete, we’ve seen both methods up close. We chose to specialize in polyurethane foam leveling because it delivers better, longer-lasting results for our customers. If you’re dealing with sunken concrete and want to know which approach makes sense for your situation, give us a call at 612-275-4086 or reach out online. We’re happy to take a look and give you an honest assessment.