Concrete Levelling and Slab Jacking Services VIC 2026 - Get Quotes

Why Victorian Slabs Sink

A concrete slab does not collapse under its own weight, it follows the ground beneath it. Where that ground drops away, the slab either bridges the gap until it cracks or settles into it, and in Victoria there are four common reasons the ground gives way. Understanding which applies to your property decides whether levelling will hold. Reactive clay is the first and the most distinctly Victorian. Soils across the basalt plains west and north of Melbourne swell as they take up water and shrink as they dry, so the ground beneath a slab rises through a wet winter and settles through a dry summer. Where a slab sits partly over ground shielded from rainfall and partly over exposed ground, the two sides move by different amounts and the slab tilts.

Poorly compacted fill is the second and it is widespread through the growth corridors. Sloping and subdivided sites are commonly built up with imported fill to create a level building platform, and where that fill was not compacted to the required standard it continues to consolidate under load for years afterward. Slabs poured over it settle progressively as it densifies. Erosion from water is the third cause and it is usually the cheapest to correct. A leaking water supply line, a cracked sewer or stormwater pipe, or a downpipe discharging at the edge of a slab will wash fine material out from underneath over time, leaving a void that the slab eventually drops into. Finding and repairing those is covered at pipe relining and drain repairs.

Tree roots are the fourth and they work by drying rather than washing. A mature tree drawing moisture from reactive clay within its root zone shrinks the soil locally, and that is most pronounced through a dry Victorian summer, so the side of a slab nearest a large tree can drop noticeably while the far side stays put. Removing the tree is not automatically the fix, because the clay can then take moisture back up and heave. Voids are what all four produce and voids are what levelling fills. A slab sitting on continuous support does not sink, so every settled slab has space beneath it that used to be soil, and the injected material is filling that space and then lifting.

Knowing which of the four created the void tells you whether it will form again. That is the question worth settling before any lifting happens. Levelling a driveway that sank because of a leaking pipe without repairing the pipe produces a driveway that sinks again, and the same applies to uncorrected drainage. Where seasonal clay movement is the cause the picture is different again, since that movement will continue regardless and the realistic goal is correcting the current position rather than preventing all future movement.

Polyurethane Injection and Mudjacking

Two established methods lift a settled slab and they work on the same principle with different materials. Both drill through the slab, inject something underneath that fills the void and generates lift, and then patch the holes. The differences between them decide which suits a particular job. Polyurethane injection is the modern approach and now the more common one. A two part resin is injected through small holes, it expands rapidly on mixing, fills the void and lifts the slab in a controlled way as the operator watches the level. The holes are small, typically around sixteen millimetres, and the resin reaches working strength within minutes.

Its main advantage on Victorian ground is weight. The cured resin is very light compared with the material it replaces, which matters on soft clay or poorly compacted fill where adding mass would simply push the problem down further. That makes it well suited to exactly the conditions that cause settlement here in the first place. Mudjacking is the traditional method and still has a place. A slurry of cement, soil and water is pumped under the slab through larger holes, typically around forty millimetres, filling the void and raising the concrete. The material is inexpensive and the technique is long proven, which keeps the cost per square metre lower on straightforward jobs.

The trade offs run the other way as well. Mudjacking holes are considerably more visible after patching, the slurry is heavy enough to cause further settlement on weak ground, and the slab generally needs a day or more before it carries traffic. On a driveway that needs to take a car the same evening, that difference matters. Grinding is a third option that does not lift anything. Where two slabs meet at a step, the high side can be ground down to remove the trip hazard, which is quick and inexpensive and leaves the levels wrong but safe.

It suits a small step on a path where lifting is not justified. Where the concrete itself has deteriorated rather than simply dropped, removing and repouring is the honest option. A new pour uses ready mixed concrete from a supplier such as Boral, Hanson or Holcim, ordered to a strength grade suited to the application. Concrete that is badly cracked, crumbling or has lost strength cannot be lifted as a unit and will break up under the attempt, so removing and repouring is the honest option. That work falls to concreting services, with breakout handled at concrete removal.

When Levelling Is the Right Answer

Driveways are the most common candidate and usually the most satisfying result. A concrete driveway that has settled near the crossover, dropped away from the garage threshold or developed a low point that holds water after rain is exactly what levelling addresses, and the slab itself is generally sound. New driveway construction is covered at concrete driveway. Paths and footpaths around a house are the second common case. A step where two slabs meet is a genuine trip hazard, particularly at an entry or along a route used at night, and lifting the low side restores both the level and the fall so water runs away rather than pooling. New path construction is covered at concrete pathway.

Garage and shed floors respond well where the slab has settled but not cracked badly. A floor that slopes enough for a car to roll, or that has dropped away from a wall leaving a gap, can generally be lifted back, and the fast cure of polyurethane means the space is usable the same day. Patios, alfresco areas and pool surrounds are worth including in the same conversation. Those slabs commonly settle at the outer edge where the ground is least supported, which tips the fall back toward the house and sends water where it should not go. Pool surround construction is covered at concrete pool surrounds.

Interior slabs can be levelled, though the assessment is different and more cautious. A settled internal floor in a house raises the question of whether the slab is structural and what the walls are doing, so it needs establishing that this is a surface problem rather than a footing problem before anybody drills. Flooring preparation is a separate question again. Void filling without lifting is a variation worth knowing about. Where a slab is still at the correct level but has lost support underneath, filling the void stabilises it and prevents the drop that would otherwise follow, which is preventative rather than corrective and usually cheaper than waiting.

Access is the practical advantage across all of these. Levelling is carried out from the top of the slab through small holes with no excavation, so garden beds, fencing, established landscaping and services underground are left undisturbed, which is frequently what makes it preferable to replacement even where both would work. That advantage grows on a property where the slab is hemmed in by fencing, a retaining wall or a mature garden. Replacement in those conditions means getting machinery in and putting everything back afterwards.

When Levelling Is the Wrong Answer

A slab that has broken up rather than settled cannot be lifted as a unit. Concrete that is extensively cracked, crumbling at the edges, spalling or has lost structural integrity will fracture further under the lifting pressure, and any operator proposing to lift it is setting up a worse outcome than the one you started with. Cracking through the house walls changes the question entirely. Where external brickwork is cracking, doors and windows are binding or floors inside have begun to slope, the issue is likely to be footing movement rather than a settled surface slab, and that needs an engineer rather than a levelling contractor. Booking a proper assessment is done through structural inspection.

An unresolved leak makes levelling a temporary result at best. Water washing fine material out from under a slab will keep doing so after the lift, and the void reforms, so the plumbing repair belongs first and the levelling afterwards. The order matters more than the choice of method. Poor site drainage falls in the same category. Ground sloping toward a slab, downpipes discharging at its edge or paving shedding water into the wrong place will keep saturating and eroding the material underneath, so correcting the drainage is part of the job rather than an optional extra. Putting that right falls to stormwater drainage plumbing.

Very recent fill on a new estate is worth a cautious conversation. Where a site was built up shortly before construction and the fill is still consolidating, a lift carried out early may need repeating, and an honest operator will say so rather than promising permanence they cannot deliver. Severely tilted slabs sometimes reach a point where replacement is the better value. Where the drop is very large, the required lift is substantial across a wide area or the slab was poorly constructed to begin with, the cost of levelling can approach replacement without delivering a slab that is actually better. Comparing both quotes honestly is the sensible approach.

Asbestos is worth a mention on older properties even though it is not a slab issue. Sheds, garages and outbuildings built before 1990 frequently have bonded cement sheet walls and roofing, and work around those needs identifying before anybody starts drilling or breaking anything nearby. Bonded cement sheet looks much like modern fibre cement from a few metres away, so the construction date is what settles it. Testing is inexpensive and worth doing before any work is scoped on a pre 1990 outbuilding.

What the Work Involves

A proper job starts with levels rather than with equipment. The operator establishes how far the slab has dropped and where, usually with a laser level, which produces a map of the settlement and determines where injection points need to go. Skipping that step is how a slab ends up lifted unevenly or in the wrong place. Drilling comes next and the hole size depends on the method. Polyurethane needs small holes around sixteen millimetres, mudjacking needs closer to forty, and the pattern of holes follows the settlement map rather than a fixed grid, with more where the void is deepest.

Injection is where the skill sits. Material is introduced progressively while the operator watches the slab with the level, lifting in stages rather than all at once, because too much pressure in one place cracks the concrete instead of raising it. On polyurethane the reaction is fast, so the control is in metering the flow. Monitoring during the lift is what separates competent work from guesswork. Good operators watch adjacent slabs, nearby walls and any services as the lift progresses, because pressure under one slab can affect what sits next to it, and stopping at the right point matters as much as starting.

Patching the holes finishes the visible work. The holes are filled with a mortar matched as closely as practical to the surrounding concrete, and on polyurethane jobs the smaller diameter means the result is considerably less noticeable, though on a decorative or coloured finish the patches will still be visible on close inspection. Timing is usually the appealing part for a homeowner. A typical residential driveway is a half day to a day of work, polyurethane generally allows traffic within hours, and there is no excavation, no spoil to remove and no landscaping to reinstate afterwards. Expectations about the finished result deserve setting properly. Levelling restores the position of the slab, it does not repair cracks, improve the surface finish or make an old slab look new, and where appearance matters as well, resurfacing is a separate consideration at concrete resurfacing.

Fixing the Cause

Levelling without addressing why the slab dropped buys time rather than a solution. That is the central judgement on any settled slab, and the honest version of the conversation separates causes that will continue from causes that can be removed. Both exist in Victoria and they need different expectations. Leaks and drainage are the removable ones and they should be dealt with first. A cracked stormwater or sewer line, a leaking supply pipe, a downpipe discharging at the slab edge or ground falling toward the concrete are all correctable, and once corrected the levelling has a reasonable prospect of holding. Correcting the falls and outlets is covered at drainage.

Seasonal clay movement cannot be removed and has to be accommodated instead. Reactive soil will keep swelling and shrinking each year regardless of what is done to the slab, so the realistic goal is correcting the current position and reducing how extreme the swing is by keeping perimeter moisture more even. Keeping moisture steady around a slab is the cheapest useful intervention available. Extending downpipe discharge well clear, making sure ground falls away, keeping heavy garden watering back from the edges and avoiding letting one side bake dry while another stays wet all reduce differential movement, and consistency matters more than quantity. Consolidating fill is a matter of time rather than treatment. Where poorly compacted fill is the cause, it will keep densifying until it reaches equilibrium, which is why levelling on a newer estate occasionally needs revisiting, and a warranty conversation is worth having upfront on those sites.

Trees need advice rather than a chainsaw. A large tree drying reactive clay is a genuine cause of slab settlement, and removing it can trigger heave in the opposite direction over the following years, so an arborist assessment should come before any decision, available through tree lopping and arborist services. Where cracking has appeared in the house as well as in the slab, the sequence changes completely. Engineering assessment comes first, any footing work follows, and surface levelling happens last, because lifting a driveway while the footings are still moving addresses the least important part of the problem. Rectification of the structure itself is covered at structural repairs.

Slab Settlement Across Victoria

The western growth corridor carries the most reactive ground in metropolitan Melbourne and a great deal of recent fill alongside it. Areas through Melton, Caroline Springs, Point Cook, Werribee and Tarneit combine highly reactive basalt clay with estates built on engineered platforms, so both of the main causes appear together. The northern corridor presents a similar combination. Craigieburn, Mickleham, Wollert and Epping include extensive reactive clay and a large volume of recent construction, which means settlement complaints there frequently involve fill still finding its final level as well as seasonal movement. Inner and middle Melbourne brings older slabs and different histories. Driveways and paths poured decades ago on ground that has been disturbed, built up and re landscaped repeatedly settle for reasons that can be hard to reconstruct, and leaking old drainage is a more common culprit in those suburbs than in new estates.

Ground through the bayside and eastern suburbs tends to be considerably more stable. Sandier soils and better drained profiles mean less seasonal movement, so a settled slab there is more likely to have a specific local cause such as a leak, an eroded edge or a nearby tree rather than general clay behaviour. Hillside suburbs through the outer east and the Dandenongs add slope to the equation. Cut and fill construction on sloping blocks means part of a slab frequently sits on undisturbed ground and part on fill, which is precisely the arrangement that produces differential settlement. Regional Victoria varies considerably by district. Geelong and the Bellarine include reactive ground and substantial new estate development, the Ballarat and Bendigo goldfields have heavily disturbed historic ground in places, and the Western District carries heavy clay across large areas.

What Concrete Levelling Typically Costs

Polyurethane injection on residential work commonly runs between $70 and $160 per square metre of slab being lifted, with the figure depending on how far the slab has to rise and how much void needs filling. A modest section of settled path frequently lands between $900 and $2,500 once mobilisation is counted. A typical residential driveway sits somewhere between $2,500 and $7,000 depending on area and the extent of the drop. That compares against replacement of the same driveway at considerably more once demolition, removal, preparation and repouring are added together, which is the comparison worth making rather than looking at the levelling figure in isolation. Mudjacking generally prices lower per square metre, often between $50 and $110, and remains a reasonable option where the ground is firm, the holes are not a visual concern and the slab can be out of use for a day or two. The saving is real though it is not always the better value once those constraints are weighed.

Minimum call out charges apply on nearly all of this work. Equipment and materials have to be brought to site regardless of how small the lift is, so a very small job frequently costs more per square metre than a large one, and grouping several areas into one attendance is usually worth doing. Engineering assessment sits outside the levelling quote and belongs in the budget where walls are involved. A structural engineer's inspection and report commonly runs $600 to $1,800, and on any property where cracking extends beyond the slab that is money spent before rather than after.

What to Look Out For

Be cautious about any operator willing to lift a slab without asking what caused it to drop. Levelling over an unrepaired leak or uncorrected drainage produces a slab that settles again, and the question about cause is the first thing a competent contractor raises rather than something you should have to prompt. Treat a proposal to lift badly cracked or crumbling concrete as a warning. Deteriorated concrete fractures further under lifting pressure, so an operator prepared to attempt it either has not assessed the slab properly or is prioritising the sale over the outcome. Ask whether the walls of the house have been looked at, particularly if you have cracking there too. Levelling contractors correct surfaces, and where footings are the actual issue the work needed is different and considerably more serious, so an operator who never raises it has looked at half the property.

Get the warranty in writing and understand what it covers. Some settlement causes will recur, consolidating fill in particular, so the terms around re levelling and the period covered matter more here than on most trades. Verify registration and consumer protections before committing. Domestic building work above the statutory value requires a registered builder and insurance, workplace safety duties are regulated by WorkSafe Victoria, and consumer guarantees are administered by the ACCC.

How to Get Useful Quotes

Measure the drop and say where it is worst. A straight edge or a string line across the settled area gives a figure in millimetres, and that single measurement tells an operator far more about the scope than a description of how it looks. Give the slab area and what it is used for. A driveway carrying vehicles, a path taking foot traffic, a garage floor and a pool surround each have different requirements, and area sets the base figure on every quote you will receive. Describe the condition of the concrete itself, not just the level. Whether it is sound, lightly cracked or crumbling at the edges determines whether lifting is even viable, and photographs of the worst section answer it quickly.

Say whether anything else on the property is cracking or moving. Wall cracks, sticking doors or sloping interior floors change the diagnosis entirely, and flagging them upfront gets you an honest answer rather than a levelling quote that misses the point. Mention any known leaks, drainage problems or large trees nearby. Those are the causes most likely to make a lift temporary, and an operator who knows about them can tell you what needs doing first. A whole property check is available through building inspection.

Have each quote state the method proposed, the expected lift, what happens if the slab cracks during the work, the warranty terms and whether any cause needs addressing first. Settling those five makes quotes genuinely comparable rather than merely similar looking. New slab construction is covered separately at concrete slab. The warranty clause is the one most worth reading closely before you sign anything.