Polyurethane Foam Concrete Lifting Terms Explained: A Plain-English Glossary
If you're getting quotes to fix a sunken driveway or an uneven sidewalk, the jargon piles up fast. This polyurethane foam concrete lifting glossary breaks down the terms you'll hear from contractors, see on quotes, and find in your own research, all in plain English. Use it to read an estimate line by line, ask better questions, and spot when someone is selling you more than you need. It's written for Des Moines homeowners, but the terms work anywhere concrete settles.
- Polyurethane foam injection: the foam-lifting method itself
- Slab jacking: the umbrella term for lifting concrete
- Mudjacking: the older cement-slurry lifting method
- Concrete leveling: making sunken concrete flat again
- Injection port: the small drilled hole foam goes through
- Lift: how far the slab rises
- Void: the empty gap under a slab
- Settling: why your concrete sank in the first place
- Expansive clay soil: the central Iowa soil that moves
- Freeze-thaw cycle: winter's push and pull on slabs
- Cure time: how long before you can use the slab
- Load-bearing capacity: how much weight the fix can hold
- Crack filling: sealing cracks so water stays out
- Self-leveling concrete: a pourable indoor floor fix
- Concrete resurfacing: a new top layer for ugly slabs
- Slab replacement: tearing out and pouring new
- Tripping hazard: the uneven edge that gets flagged
- Joint sealing: caulking the gaps between slabs
The Methods: How Sunken Concrete Gets Lifted
These are the fixes themselves. Most quotes you get will name one or more of these, and this section of the polyurethane foam concrete lifting glossary explains what each one actually does.
Polyurethane Foam Injection
Polyurethane foam injection is a repair method where a contractor pumps expanding foam through small holes in a sunken slab to raise it back into place. The foam starts as a liquid, expands underneath the concrete, and hardens within minutes. It's lightweight, so it doesn't add much weight to soil that's already struggling. If a quote mentions foam or "poly," this is the method, and the small hole size and fast cure time are its main selling points.
Slab Jacking
Slab jacking is the general term for lifting a sunken concrete slab from below instead of replacing it. Both mudjacking and polyurethane foam injection are types of slab jacking. The idea is the same either way: pump material under the slab until it rises back to level. Knowing this term helps because some contractors use it loosely, so always ask which material they plan to pump.
Mudjacking
Mudjacking is a lifting method that pumps a wet mixture of cement, soil, and water under a sunken slab to raise it. It's the older cousin of foam injection and uses bigger drilled holes and heavier material. Mudjacking often costs less per job, but the slurry adds weight, and it can take longer before the slab is ready for traffic. A straight-shooting contractor should explain when mudjacking fits your slab and when polyurethane foam concrete lifting is the better call, based on slab condition, load, and how fast you need to use it.
Concrete Leveling and Polyurethane Foam Lifting Solutions
Concrete leveling means restoring a sunken or tilted slab to a flat, even position. It's the outcome, not a specific technique; foam injection, mudjacking, and self-leveling concrete are all ways to get there. When you see "concrete leveling" on a quote, check the line items to learn which method they'll use. The method affects cure time, hole size, and how long the fix should hold.
Self-Leveling Concrete
Self-leveling concrete is a pourable cement mixture that spreads out and flattens itself over an uneven floor. It fixes the surface, not the ground underneath, so it works best indoors, like a wavy garage or basement floor. It won't lift a slab that has sunk, and it won't stop future settling. If a provider suggests it for an outdoor slab that's dropped two inches, ask why they aren't lifting the slab instead.
Concrete Resurfacing
Concrete resurfacing means applying a thin new layer of material over worn or flaking concrete to give it a fresh surface. It's a cosmetic fix for slabs that are structurally fine but look rough. Resurfacing doesn't correct sunken concrete; a slab that's low needs lifting first. Some jobs pair the two: level the slab, then resurface it so it looks as good as it sits.
Under the Slab: Why Concrete Sinks
You can't judge a fix without understanding the problem. These terms explain what's happening below your driveway.
Settling
Settling means the soil under a concrete slab has compressed or washed away, letting the slab sink. It's the root cause behind most sunken driveways, walkways, and patios. Settling can come from poorly compacted fill dirt, water erosion, or soil that shrinks in dry weather. A good contractor talks about why your slab settled, not just how they'll lift it, because the cause affects how long the repair lasts.
Void
A void is an empty space under a concrete slab where soil used to be. Water washing through, soil shrinking, or animals burrowing can all create voids. A slab over a void may look fine until it cracks or drops suddenly under weight. Filling voids is a core part of any lifting job; if a quote mentions "void filling," the contractor plans to pump material into those gaps, not just raise the surface.
Expansive Clay Soil
Expansive clay soil is soil that swells when wet and shrinks when dry, moving anything sitting on top of it. Central Iowa has plenty of it, which is a big reason Des Moines driveways and sidewalks settle and heave. The swell-shrink cycle opens gaps under slabs over time. A local contractor who mentions clay soil is telling you they understand the ground your concrete sits on, which matters more than a generic sales script.
Freeze-Thaw Cycle
The freeze-thaw cycle is the repeated freezing and thawing of water in and under concrete through the winter. Water expands when it freezes, so it pries cracks wider and shoves slabs around a little more each season. In Iowa, this cycle is a fact of life and a main driver of cracked, uneven concrete. It's also why sealing cracks and joints matters: the less water that gets in, the less winter can do.
Reading Your Quote: Process and Paperwork Terms
These are the words that show up on estimates and in conversations about scope.
Injection Port
An injection port is the small hole drilled through a slab so foam can be pumped underneath it. Foam ports are about the size of a large coin, smaller than the holes mudjacking needs. After the lift, the contractor patches the holes with cement. Ask how many ports the job needs and how they'll be patched; the answer tells you how visible the repair will be afterward.
Lift
Lift means the amount a slab is raised during the repair, usually measured in inches. A contractor might say a corner needs an inch and a half of lift to meet the garage floor. More lift generally means more material and more careful work, since raising a slab too fast can crack it. If your quote lists lift amounts by section, that's a sign the contractor measured instead of eyeballing.
Cure Time
Cure time is how long a repair material needs to harden before the slab can carry weight again. Polyurethane foam cures in minutes, so you can often walk or drive on the slab the same day. Mudjacking slurry takes longer, sometimes a day or more, before it reaches full strength. Cure time matters most on driveways and garage floors you need back in service quickly.
Load-Bearing Capacity
Load-bearing capacity is the amount of weight a material or repaired slab can support without failing. It matters when the slab carries something heavy, like a vehicle in a driveway or garage. Both cured foam and mudjacking slurry can support normal residential loads when the job is done right. If your slab holds an RV or a heavy trailer, say so up front, because load affects which method and how much material the job needs.
Crack Filling
Crack filling means sealing cracks in concrete with a flexible material so water can't get through them. It's often paired with lifting, because open cracks let water wash out the soil below and restart the settling. Crack filling won't rejoin a badly broken slab, but it protects a repaired one. A quote that includes crack repair alongside leveling is addressing the cause, not just the symptom.
Joint Sealing
Joint sealing means caulking the gaps between slab sections so water and debris stay out. Those joints are built into concrete on purpose, but open joints funnel rain straight to the soil below. Sealing them is a low-cost step that helps a lifting repair last through Iowa's wet springs and freezing winters. Many contractors offer it as an add-on line; it's usually worth asking about.
Slab Replacement
Slab replacement means tearing out the old concrete and pouring new in its place. It's the right call when a slab is crumbling, badly broken into pieces, or too damaged to lift in one piece. Replacement costs more and takes longer than leveling, including days of cure time before you can drive on it. An honest contractor will tell you when your slab is past lifting; be wary of anyone who says every slab can be saved, or that every slab must be replaced.
Tripping Hazard
A tripping hazard is a raised or sunken edge in a walking surface, usually where one slab sits higher than its neighbor. Even a small height difference between sidewalk sections can catch a toe. Cities flag these on public walkways, and homeowners often fix them for safety and liability reasons. Sidewalk leveling is one of the most common and fastest concrete lifting jobs for exactly this reason.
Using These Terms for Polyurethane Foam Concrete Lifting
That's what this polyurethane foam concrete lifting glossary gives you: enough working vocabulary to read a quote line by line and know what each item actually buys. When a contractor mentions ports, voids, or cure time, you can follow along and ask the next question instead of nodding. That alone puts you ahead of most homeowners comparing bids.
If you need concrete leveling, Des Moines Concrete Leveling Pros can help.
Prefer to talk it through? Call +15155828701 — a quick call is usually the fastest way to get a straight answer for your situation.