Polyurethane foam concrete lifting
Small holes, a lightweight material that won't wash out, and a slab you can usually walk on within the hour.
Foam lifting uses a two-part polyurethane that's mixed at the injection gun and pumped beneath the slab as a liquid. It expands to fill the empty space, then keeps expanding against the underside of the concrete until the slab rises. The installer controls the lift by adding foam in short bursts and watching a level or laser.
Why do people choose foam?
- Small holes. Injection ports are about the size of a dime, so patches are hard to spot once they're filled.
- Light weight. Foam adds very little load to soil that has already shown it can settle.
- Quick cure. Most foams set within minutes, and many slabs can take foot traffic soon after.
- Doesn't absorb water. Closed-cell foam isn't washed away by the next wet spring the way loose fill can be.
Where does foam work well around Mankato?
Foam is common on front steps and stoops next to the foundation, on garage floors where a heavy material would add load, and on patios and walks where homeowners don't want big patches. It's also a good fit for slabs near basement walls, where you want as little added weight as possible.
What does the contractor check first?
- How far the slab has dropped, measured across each joint
- Whether cracks run all the way through, which affects how the slab will lift
- Where downspouts, sump lines and buried utilities run
- Whether the soil underneath is still moving, such as near an eroding slope
When is foam the wrong choice?
If the concrete is flaking or crumbling on top, foam won't fix the surface. If the slab is broken into many small pieces, it may not lift as one unit. And if water keeps running under it, any lift is temporary until the drainage is corrected.
What affects the cost?
- How much foam it takes to fill the void, which depends on its size
- The number and size of slabs
- How far each one needs to come up
- Sealing joints and cracks after the lift
Pricing comes from the contractor after an on-site look, because the size of the void and the reason the slab dropped drive the cost. We don't quote prices, and a phone estimate is only a rough guess until someone has measured the concrete.
Where we connect you with help
Common questions
How soon can I drive on a slab lifted with foam?
Many contractors say within an hour or so, because the foam cures quickly. Ask yours for the exact wait on your job.
Will foam work if my slab is next to a bluff or ravine?
It depends on whether the ground is still moving. Foam fills voids, but it can't hold back an eroding slope. A contractor should look at the site and may recommend a different approach.
Related services
- Mudjacking (slabjacking)
- Driveway and garage floor lifting
- Sidewalks, steps and patios
- Joint sealing and crack repair
More background: Mankato concrete lifting guide.
Slab dropped, tipped or pulling away from the house?
Call and a Mankato-area lifting contractor will come look and give you a quote.