A low patio, a sunken walkway, a garage slab with a lip at the crack. The fix that often comes up first is “concrete leveling,” and for some of those problems it is a reasonable answer. For others it is a cosmetic answer to a structural question.
This post draws the line between the two. It is not a pitch for either one. The goal is to help you see what a proposal will actually change. If you have not yet sorted out which way the ground moved, start with the companion post on slab settlement vs soil movement. The direction of movement decides most of what follows.
Leveling changes where the concrete sits. Structural repair changes what holds the building up. Sometimes you need one, sometimes both, and sometimes neither until the cause is fixed.
Three different things called “leveling”
The word gets used for at least three unrelated kinds of work, and mixing them up causes a lot of confusion.
1. Slab lifting by injection. Mudjacking (also called slabjacking) pumps a cement-based slurry through holes drilled in the slab to fill voids and raise it. Polyurethane foam lifting does a similar job with an expanding polymer. Both act on the slab and the soil or void directly beneath it. This is what most people mean by “concrete leveling.”
2. Floor leveling compound. Self-leveling underlayment is poured over an existing slab or subfloor so new flooring has a flat surface. It changes the surface you walk on. It does not change support at all. A floor that slopes because the slab moved will still have a slab that moved under the new, flatter finish.
3. Raised-floor leveling. Shimming, adjusting posts and pads, or sistering joists under a wood-framed floor. That is a different system entirely; our older La Jolla raised foundations post covers it.
One more mix-up worth clearing: polyurethane lifting foam is not the same product class as the polyurethane crack injection resin used to stop water through a crack. Our post on epoxy vs polyurethane crack injection covers the crack resins, and foundation crack repair covers when cracks are the main complaint.
The rest of this post is about the first meaning, slab lifting, compared with structural repair.
What structural repair means
Structural repair is work that restores or changes the support and load path of the building, or corrects damage to the structure itself. For slab homes, the families you will hear about include:
- Underpinning with piers, piles, or caissons that carry load down to deeper, more competent soil (see underpinning explained for homeowners and what helical piers do)
- Partial slab replacement or sectioning where concrete is badly broken or must come out for plumbing
- Footing repair at thickened slab edges
- Drainage or plumbing correction paired with structural work when water is the driver
Structural work in the City of San Diego generally needs a Building Permit (San Diego Municipal Code §129.0202). Depending on the parcel and the soil, plans, calculations, and a geotechnical report may be required. City Information Bulletin 141, for example, calls for a geotechnical report when a building is supported on fill or on expansive soil.
Side by side
| Slab lifting (mudjacking / foam) | Structural repair | |
|---|---|---|
| Acts on | The slab and the void or soil just below it | The building’s support system and load path |
| Changes the cause of movement? | Not by itself | Sometimes (for example, deeper support), but usually paired with fixing water or drainage |
| Typical targets | Exterior flatwork; some interior slab voids | House slabs and footings with structural distress or active differential movement |
| Investigation first? | Often minimal for flatwork; more for house slabs | Usually elevation survey, often engineering, sometimes geotech |
| Permit path | Depends on what is lifted and where (see below) | Generally a Building Permit |
| Who is involved | Concrete or foundation-jacking contractor | Contractor plus engineer and/or geotechnical professional as triggered |
That table is a generalization. The point is the first two rows: lifting moves concrete, and it does not by itself change the reason the concrete moved.
When leveling can be a reasonable answer
Lifting tends to make sense when the problem is limited, the cause is understood, and the cause has been dealt with or has stopped:
- A walkway or patio panel that settled after a downspout was rerouted and the soil has stopped changing
- A driveway section with a trip lip, where the underlying soil is otherwise stable
- A void under a garage slab from a leak that has been repaired
On exterior flatwork, the stakes are different from the house. Driveways and walkways are usually not the building’s foundation. The San Diego Municipal Code exempts from a Building Permit “sidewalks and driveways that are 30 inches or less above adjacent grade, are not over any basement or story, and are not part of an accessible route” (§129.0203(a)(7)). Those exemptions do not apply on historical resources, on environmentally sensitive lands where a development permit is required, and in a few other cases, so it is still worth a parcel check. And that exemption covers sidewalks and driveways, not the structural slab of the house.
When leveling is the wrong first move
Lifting is a weak first step, or the wrong one, when:
- The movement is still active. If a leak is still running, irrigation is still soaking one edge, or the soil is cycling with the seasons, lifted concrete can keep moving.
- The “low” side is really the unmoved side. If part of the slab heaved, lifting the rest to match can chase the wrong problem. Expansive soil is the common culprit; the California Geotechnical Engineering Association’s homeowner guide notes that lower heave at the top of a slope “is often mistaken as settlement.”
- The movement is sideways. Near slopes, soil can expand outward or creep downhill. Vertical lift does not address lateral movement, and gaps between a patio and the house on a slope-side lot are a clue to look at that first. See hillside foundation repair.
- The house slab shows structural distress. Cracks with vertical offset through the living space, wall cracking that tracks the floor, racked doors, or separations at footings point toward a foundation inspection, not a quick lift.
- The slab is post-tensioned and nobody has confirmed it. Injection means drilling through the slab. Post-tensioned slabs contain steel tendons under high tension. Before anyone drills or cores, the slab type should be confirmed and tendon locations accounted for.
Our slab foundation repair page is direct about this: claims that mudjacking or foam “permanently stops movement” on bluffs, active slopes, or soils that swell and shrink with the seasons are not something this site will repeat. The CalGeo guide makes a related point from the soil side. Where expansive soil is present, some ground movement is unavoidable, and longer-term cyclical movement may continue with the seasons.
When it takes both
Some projects combine the two. A house slab may get deeper support at one corner through underpinning while exterior flatwork is lifted or replaced, and the drainage that started it all is corrected. Or a leak is repaired, a void under a section of house slab is filled as part of a permitted scope, and the floor is monitored afterward. The order matters: water and cause first, support second, cosmetics last.
If you are weighing a settlement repair proposal for the house itself, the foundation settlement repair and foundation underpinning pages cover those projects.
Five questions to ask before you accept a leveling bid
- What caused the void or drop, and has that cause been fixed? If the answer is “doesn’t matter, we’ll lift it,” keep asking.
- Is this flatwork or part of the house’s foundation? The risk and permit picture are different.
- Has anyone measured the whole slab, not just the low spot? You want to know whether you are looking at settlement, heave, or a sideways problem.
- Is the slab post-tensioned, and how was that confirmed? Get a straight answer before drilling.
- What permit applies, and what license classification does the contractor hold? The Contractors State License Board lists a D-30 Pile Driving and Pressure Foundation Jacking classification that includes “the injection of concrete or mortar into foundations for stabilization purposes,” alongside the C-8 Concrete classification. Holding a classification does not make a method right for your lot, but you can check any license on CSLB’s website.
Also ask what the proposal says about future movement. Any honest answer will be conditional.
Who should you call first?
If it is a sidewalk panel with a trip edge and an obvious, fixed cause, a qualified concrete contractor may be all you need. If it is inside the house, if cracks show offset, if doors and walls are reacting, if the lot is near a slope, or if you do not know why it moved, start with an evaluation of the cause before choosing between leveling and structural repair. A home inspector’s report is a useful screen. It is not an engineering opinion.
La Jolla Structural evaluates slab and flatwork movement for homeowners across La Jolla and we coordinate with licensed engineers as needed when soils, load path, or stamped plans are part of the answer. We do not publish invented license numbers, warranties, or project claims on this site.
Cost factors, not prices
We do not publish leveling or repair prices. Cost depends on what is being lifted or supported (flatwork vs house slab), how large and deep the voids are, access through flooring and finishes, whether the slab is post-tensioned, what investigation is needed, whether drainage or plumbing has to be fixed first, permits and parcel overlays, and restoring finishes afterward. A low number for a lift that does not address the cause is not a saving. See what drives foundation repair cost and our foundation repair cost page for the factors.
A practical next step
Before you sign anything, note what moved, when it started, and what water sources are nearby. Take a few dated photos with a tape measure in the frame. Then have someone look at the cause, not just the low spot.
Request a Free Quote for an on-site evaluation in La Jolla, or call (650) 739-6537. If you want the background on how slabs move in the first place, read the companion post on slab settlement vs soil movement.
Sources (accessed October 5, 2026)
- San Diego Municipal Code Chapter 12, Article 9, Division 2, §129.0202–§129.0203 (September 2026 edition)
- Contractors State License Board, D-30 Pile Driving and Pressure Foundation Jacking classification; Description of Classifications (C-8 Concrete)
- California Geotechnical Engineering Association, Coexisting with Expansive Soil: An Informational Guide for Homeowners
- City of San Diego Information Bulletin 141, Soil Bearing Capacity
- Post-Tensioning Institute, Slab-on-Ground (PTI DC10.5 design standard)
- California Residential Code (2022), Section R506