Foam Concrete Leveling: Pros, Cons, and When It’s the Right Fix

Learn about the advantages and disadvantages of leveling your settled concrete with foam.

If you’ve watched a foam leveling video, it probably looked simple: drill a few holes, inject some foam, and the concrete slab floats right back into place. Foam can work really well in some situations, but the truth is… it can cause problems in others.

So we put together this article to walk you through exactly how foam concrete leveling works, where using it makes sense, where it struggles, and how to know if it’s the right fit for your concrete. Because there isn’t a “one-size-fits-all" solution, but you can pick the right tool for the job.

TL;DR

Foam concrete leveling is a fast and low-impact way to lift sunken slabs using expanding polyurethane foam. It works well in tight or indoor spaces and cures quickly with minimal mess. But it doesn’t always fill voids completely, and the chemical reaction can over-lift slabs if conditions aren’t ideal. Foam is best for specific use cases… not every situation.

In This Article:

• What Foam Actually Does
• Where Foam Falls Short
• Where Foam Works Best
• Pros & Cons at a Glance
• Should You Use Foam?
• FAQs

What Is Foam Leveling and How Does It Work?

Foam leveling, also called polyjacking, follows the same overall steps as other concrete leveling methods. But, it differs by lifting sunken concrete using a two-part polyurethane foam that expands underneath the slab. This chemical-based process follows three key steps:

1. Small holes (around ⅝”) are drilled through the slab.
2. The two-part liquid foam moves through separate hoses before combining as they’re injected underneath.
3. A chemical reaction causes the foam to expand, lifts the concrete, and cures in place.

Once the slab is back in position, the holes are patched and the surface is usually ready to use within an hour. That speed and minimal disruption are major reasons foam has become so popular.

Where Foam Falls Short

Much of what you see with foam is fun to watch… but what you don’t see is where foam’s weaknesses come into focus:

• It doesn’t always fill voids completely.

Foam follows the path of least resistance. Instead of filling the entire space under a slab, it can "pancake" into thin layers, leaving hollow pockets that create weak spots.

• The lift isn’t fully controllable.

Foam keeps expanding after it’s injected. That can lead to over-lifting: a slab pushed too high, with no easy way to bring it back down.

• It’s temperature-sensitive.

The chemical reaction that lifts the foam depends on very specific conditions set by the manufacturer. If it’s too hot, cold, or humid, the foam might cure unevenly or not reach full strength. Pairing that “weak” foam with unfilled voids can be a recipe for failure.

• Environmental considerations.

The foam typically used for leveling is petroleum-based and often non-recyclable. That means if your slab ever needs replaced, it may end up in a landfill instead of being recycled like standard concrete.

When Foam Works Best

It’s not all doom and gloom when it comes to polyjacking:

• Tight access areas

While many foam rigs are trailer-bound or operated out of a van or truck, foam concrete lifting can sometimes be done with portable units making it lightweight and portable, so they can go where large equipment can’t. The liquid foam also makes it easier to transport and carry more material for high-volume jobs in comparison to other materials like pulverized limestone.

• Fast turnaround

Depending on chemical formulation, most polyurethane foam products used in the polyjacking process reach an initial cure within one hour of injection. This allows concrete slabs to be used right away (typically within one hour).

• Decorative, delicate surfaces

Relative to other leveling methods, foam’s smaller drill holes may be less noticeable when the repair is complete. Especially after the patched holes are given time to weather.

• Indoor or sensitive environments

Foam is self-contained in nature. This means it is an ideal method for spaces that require clean, dust-free applications like surgical wings of hospitals.

Pros & Cons of Foam Leveling (At a Glance)

So… Should You Use Foam?

Foam is ideal when you need:

• A fast, low-impact solution
• Minimal surface disruption
• Repair in a tight or indoor location

But you might want a different method if:

• Your slab has deep or uneven voids
• You want more lift control
• You prefer a natural or eco-friendly material

How to Know if Foam Is the Right Option for Your Slab

Start with a professional walkthrough. If they can walk you through the logic behind the method, you’re on the right track. And if you’re still unsure, we’re happy to take a look. Some of our A-1 teams offer foam leveling, but all offer free onsite estimates… even if that means foam isn’t the answer. That’s because no single method works for every job.

Request a Free Estimate Today

Foam Leveling/Polyjacking FAQs

How long does foam leveling last?

Most polyurethane foam repairs can last for the life of your concrete. But longevity depends on a number of factors including:  the condition of the base soil, drainage patterns, and whether voids were fully filled during installation.

Can foam leveling be done in cold weather?

Some foam products are designed for colder conditions, but most require a specific temperature and humidity range. If the environment falls outside those specs, the foam may not cure properly.

Can I drive or walk on the concrete the same day?

Yes. Foam cures quickly (typically within an hour) so most slabs are usable the same day the repair is completed.

Is foam safe to use indoors?

When installed correctly, yes. Foam generates heat during curing and should be applied with proper ventilation and mixing ratios. In sensitive indoor spaces, its low-dust, water-free process is often a plus.

Still deciding?

• 5 Reasons Your Concrete is Settling & What to Do About It
• Concrete Leveling Methods Compared: Foam vs. Slurry vs. Mudjacking
• How Long Does Concrete Leveling Last?