The Ardent argument
Lift, don’t replace
Demolition and repour of a sunk slab costs four to six figures, takes a week, and pours new concrete onto the same ground that just ate the old — the replacement inherits the cause. Lifting costs dollars the square foot, takes hours, addresses the void under the slab directly, and leaves you the concrete you already own, back where it was poured. We will say when a slab is past lifting — but that verdict belongs to a survey, not to a demolition quote written from the driveway.
Coldharbor & the Quay Flats, 2025 — 2026
Slabs we lifted
Six from last season’s book, photographed at the level-check — the work argues before the menu does, which is why this page runs backwards from every other contractor’s.
Services
The lift menu, numbered
01
Foam slab lifting — $8.40 / sq ft
Two-part polyurethane through 5/8-inch ports on a staggered grid, expanding to fill the void and lift in millimetre steps at two to four PSI. The material weighs four pounds a cubic foot against mudjacking’s hundred-plus, cures load-bearing in thirty minutes, and the slab takes forklift traffic the same afternoon.
02
Mudjacking — $6.90 / sq ft
The older brother: a sand-and-cement slurry pumped through larger holes, ideal for heavy sections, poor drainage under the slab and jobs where the foam would travel instead of set. More holes, more weight, slower cure — and for the fish market floors of the world, still the honest tool.
03
Void filling & joint stabilisation — $14 / lin ft
For slabs that have not sunk but have hollowed — the drum test thuds, the edges rock, the joint sealant has torn. Material injected through the joints to re-bed the slab before it settles unevenly, and the joints re-sealed on top of the repair instead of over the void.
04
Structural slabs — piers, $1,860 each
When the slab IS the foundation — a slab-on-grade home or a warehouse apron carrying columns — lifting the surface fixes nothing. Helical piers through the slab at engineered spacing, torqued to refusal, the slab re-levelled onto them and every pier logged. The twenty-five-year warranty follows the log.
The yard, in figures
How a slab comes back
The lift sequence
Five stations, the same on a back step as on a warehouse floor — the only variable is how many ports the map asks for.
The survey
Tap, map, measure
The chain-drag finds the hollows, the level and the string record where the slab sits against where it was poured, and the cause is traced — erosion, a settling trench, a drainage failure feeding it. The map prices the job; the cause, if ignored, re-prices it in three years.
The pattern
Ports on a grid
Five-eighth-inch holes drilled on a staggered pattern off the void map — close enough that no section lifts alone, far enough that the foam travels and sets as one bearing layer under the slab.
The lift
Millimetres at a time
Foam or slurry injected port by port at two to four PSI, the slab encouraged rather than jacked — watched with a level and, on big floors, a rotating laser. Concrete lifts, cracks close, doors that dragged at the threshold start latching again mid-afternoon.
The seal
Ports plugged, joints sealed
Injection ports plugged with concrete, the surface patched to match, joints re-sealed so the next rain carries nothing under the slab to start the cycle over. The cause from the survey gets its fix in the same visit wherever it is a gutter or a grade.
The check
Level, logged, warranted
The closing level readings printed beside the survey’s, the void map marked closed, and the five-year warranty filed against the pair. Heavy floors get a thirty-day re-check because settled foam, on the rare slabs that see it, shows inside a month.
The re-level clause
If a slab we lifted settles more than six millimetres inside five years, we return, re-survey at our cost and lift it again free — material, labour and the re-survey. The clause has been exercised four times in twenty-six years, three of them on slabs whose drainage fix the owner postponed. The cause is on the survey for exactly that reason.
The warehouse apron had a two-inch step the forklifts took like a bucking horse, and two quotes wanted it repoured — three weeks, six figures, the same fill underneath. Ardent lifted it back to level in one morning, the joints were sealed by four, and the trucks ran over it at nine the next day. The closing level sheet is taped to the foreman’s desk.
Our driveway walked a trench the utility crew backfilled loose. They void-filled and lifted the whole run in an afternoon for less than the demolition quote’s deposit — and they traced the downspout that had been feeding the void, which nobody else had even looked for.
The cottage slab was structure, and they were the only outfit who said so: foam under a load-bearing slab is theatre. Nine piers through the floor, the slab re-levelled onto them, the torque log in a binder — and the floors that had bounced for a decade went solid. The five-figure pier number hurt; the repour number was worse and fixed less.
Foam or mudjacking — which does my slab need?
Weight, access and what is under the slab. Foam is the default: four pounds a cubic foot, tiny ports, cures in thirty minutes, and it travels to fill a void before it sets — the right tool for driveways, garage floors, patios and anything you need back in service the same day. Mudjacking suits heavy sections, saturated ground and slabs where foam would travel too far to ever set — the fish market pours slurry and so do we, at $6.90 against $8.40. The survey picks, and both prices are on the menu.
How much can you actually lift?
Slabs come back anything from a finger’s width to four inches in a session; past that the concrete has usually taken a set it will not forgive, and the honest verdict is section replacement — which we also do, and which the survey will say before the foam is ordered. What we will not do is lift a slab back over a live cause: erosion still feeding, a drain still discharging under it. Fix the cause or watch the money leave twice.
Will the foam rot, settle or poison the ground?
It is an inert two-part polyurethane that cures into a closed-cell solid — the same family of material as rigid insulation board, formulated to stay rigid under load. It does not leach, it does not biodegrade on any calendar a warranty cares about, and at four pounds a cubic foot it adds almost nothing to the load on soils that just proved they dislike load. The mudjacking slurry, for the record, is sand, cement and water — nothing exotic either.
Can you lift a slab that is part of the foundation?
That is the one in twelve, and the menu’s fourth line. A slab-on-grade house or a floor carrying columns is structure: lifting its surface while its bearing fails underneath is paint on a sinking ship. Helical piers go through at engineered spacing, are torqued to refusal, and the slab is re-levelled onto them — the twenty-five-year warranty follows the torque log, and the price is per pier because houses do not come in packages.
When is replacement honestly better?
When the concrete itself has failed — shattered mesh, spalling through the depth, sections that move independently of one another — or when the level you would lift back to no longer matches the structure around it. Roughly one survey in nine ends there, and we say so with the demolition math attached. The other eight are physics problems, and physics problems have afternoon answers.
The shop line
Surveys within two days — a sunk slab with a trip hazard jumps the queue the same morning. The $240 survey, chain-drag map and closing sheet included, comes off any lift we then do. slab@ardentfooting.example
Trip-hazard surveys the same morning · warehouse lifts run weekends so the floor never closes · (555) 038-1290 · slab@ardentfooting.example
Put the ground back under it
Tell us what sank, roughly when, and what might have gone under it — a trench, a downspout, a drainage change. The $240 survey maps the void and prints the verdict, comes off any lift we then do, and the map is yours whoever raises the slab. slab@ardentfooting.example