Concrete slab cost in Australia sits between roughly $85 and $180 per square metre supplied and laid for the kind of slab most homeowners actually order: a shed floor, a garage, a driveway, a patio, or the base for a small extension. Where a quote lands inside that band depends on thickness, reinforcement, site access and finish rather than on the concrete itself.
Scope of this guide. This page covers non-house slabs only: sheds, garages, driveways, patios and small extensions. These are standalone slabs poured to support a light structure or a surface, not the structural footing system a house sits on.
If you are building a new home and pricing the structural slab under the dwelling, that is a different design problem with different engineering, different costs and a different approval path. Read the BUILTLY guide to waffle slab vs raft slab in Australia instead, and stop there. Nothing on this page should be used to price or specify a house slab.
The reason the distinction matters is that a house slab is engineered to a site classification, a soil report and a footing design signed off by a structural engineer. A shed or patio slab is generally built to a standard detail, poured in a single visit, and priced as a supply and lay item. The two are not comparable on a dollar per square metre basis, and quotes that blur them are usually a sign the contractor has not read the job properly.
Within the non-house category, the biggest single driver of price is what the slab has to carry. A patio carries people and furniture. A shed floor carries stored goods and sometimes a vehicle. A driveway carries a car every day and occasionally a delivery truck. Each step up in load means more thickness, more steel and more preparation underneath, and that is where the money goes.
For the wider context of how slab work fits into a residential build programme, the BUILTLY complete guide to building a house in Australia sets out the sequence from site preparation through to handover.
Cost by slab type and application
The ranges below are supply and lay rates for a level, accessible suburban site in 2026, including excavation to depth, formwork, mesh, plastic membrane where required, concrete and a standard finish. They exclude council fees, engineering, retaining, significant cut and fill, and pumping. Regional pricing varies, and small jobs carry a minimum charge that pushes the effective rate up sharply.
Shed slab
Expect $95 to $140 per square metre for a 100mm slab with SL72 mesh, which suits a garden shed or a general storage shed. A 3m by 3m slab is around $1,200 to $1,800 once the minimum charge is applied. A 6m by 9m farm style shed at 100mm sits near $5,500 to $7,500. If the shed will take a vehicle, a workshop hoist or heavy racking, the slab moves to 125mm or 150mm with SL82 mesh and thickened edge beams, which typically adds 15 to 30 percent.
Garage slab
A detached garage slab generally runs $120 to $170 per square metre. The slab is usually 100mm to 125mm with thickened edges to carry the wall structure, and it needs to be set out accurately because the frame or brickwork lands directly on it. A standard double garage of about 36 square metres commonly quotes between $4,500 and $6,500. Attached garages that tie into an existing dwelling cost more because of the junction detail and the need to match levels and manage water at the interface.
Driveway slab
Plain reinforced concrete driveways typically fall between $110 and $165 per square metre, rising to $150 to $230 for exposed aggregate and higher again for stamped or coloured work. Driveways carry repeated vehicle loading, need falls set to move water away from the house and towards a legal discharge point, and usually require a crossover to council specification at the kerb. That crossover is priced separately and often needs council approval and inspection. For a full breakdown of surface options and comparative rates, see the BUILTLY guide to driveway cost in Australia.
Patio slab
A plain patio or alfresco slab is the cheapest of the group at roughly $85 to $130 per square metre for 100mm with mesh and a broom finish. Loads are light, so the spec is modest. Cost climbs quickly with finish: exposed aggregate typically adds $40 to $70 per square metre, and coloured or stamped concrete adds $50 to $100. If the patio is an alternative to soft landscaping, it is worth comparing the whole of life cost against other surfaces such as those covered in the BUILTLY guide to artificial turf cost in Australia.
Small extension slab
A slab for a small extension, a granny flat base or an enclosed room addition is the most expensive per square metre of the group, commonly $140 to $220. This is habitable construction, so the slab requires engineering, a vapour barrier, termite management, edge beams sized to the wall loads and a mandatory pre-pour inspection. It also has to tie into the existing building at the correct level with proper articulation. The rate reflects design input and inspection as much as concrete volume.
What affects slab cost
Concrete itself is one of the smaller line items. Two quotes for the same slab can differ by thousands because of the work around the pour.
Site preparation and access
A truck that can reverse to the formwork and chute directly into the slab is the cheapest scenario. Where the pour is behind a house, up a slope or past a narrow side gate, the contractor needs a concrete pump, typically $700 to $1,500 for a domestic job, or has to barrow the load with additional labour. Removing existing paving, tree roots or an old slab adds demolition and tip fees. Backyard access is the single most common reason a patio slab quote comes in far above the headline rate.
Excavation and fall requirements
Every slab needs to sit on compacted material at the right level. On a sloping block that means cut and fill, and fill deeper than about 300mm generally needs to be engineered or the slab thickened to bridge it. Slabs also need fall, usually around 1 in 100, to shed water away from buildings. Getting fall right on a driveway that has to meet a fixed kerb level and a fixed garage level is a set out problem that takes time and occasionally requires a step or a grated drain, each of which adds cost.
Reinforcement: mesh or bar
Most domestic non-house slabs use a single layer of steel reinforcing fabric, commonly SL72 or SL82, supported on bar chairs at the correct height within the slab. Heavier applications use trench mesh in thickened beams, or in some cases individual reinforcing bars tied in place. Mesh is the cheaper option and covers the great majority of shed, patio and driveway work. Bar and trench mesh add material and labour, but they are what allows a slab to carry concentrated loads without cracking through.
Finish type
A broom finish is the default and the cheapest, giving a slip resistant surface suitable for driveways, sheds and patios. Exposed aggregate involves washing back the surface to reveal the stone and requires a larger crew working to a tighter window. Coloured concrete adds oxide through the mix or as a dry shake, and stamped concrete adds pattern work and sealing. Sealing decorative finishes is an ongoing maintenance cost that is easy to overlook when comparing quotes.
Thickness
Thickness drives concrete volume directly. Moving a 40 square metre slab from 100mm to 150mm adds two cubic metres of concrete plus the extra excavation, which on its own is a few hundred dollars. The larger cost is that thicker slabs usually come with heavier reinforcement and more preparation, so the increments compound. This is why a like for like comparison of quotes must confirm the thickness each contractor has allowed.
Reinforcement and thickness by application
A shed slab and a driveway slab look similar once finished, but they are solving different problems. A shed slab is a floor. Its load is spread reasonably evenly and it is protected from weather once the structure is up. A 100mm slab on compacted base with SL72 mesh handles that comfortably.
A driveway slab is exposed pavement. It takes a wheel load concentrated on a small contact area, repeatedly, in the same wheel paths, while expanding and contracting with temperature and drying out unevenly. That combination is why driveways are usually 100mm to 125mm minimum with SL72 or SL82 mesh, thickened at the edges where wheels track close to the boundary of the slab, and cut with control joints so the inevitable shrinkage cracking happens where it was planned rather than across the middle.
Patios sit at the light end and rarely need more than 100mm. Garage and small extension slabs sit at the heavy end because they carry walls, and a wall load concentrated along a line requires a thickened edge beam rather than a uniform slab. Termite management, vapour barriers and articulation joints become relevant as soon as the slab supports habitable space.
The detail of how that steel is placed, tied, chaired and lapped is trade level work, and getting it wrong is a defect that only shows up years later. Rather than repeat it here, see the BUILTLY guides to what a concreter does in residential construction and what a steel fixer does in residential construction for how the two trades divide the work and where the handover points sit.
A practical rule for homeowners: if a quote does not state slab thickness, mesh type and joint spacing, it is not a quote you can compare against another one. Ask for those three numbers in writing before you sign anything.
DIY vs professional installation
Small concrete work is one of the few trades where a capable owner-builder can realistically save money, but the window is narrower than most people expect. Concrete is unforgiving. Once the truck arrives you have a fixed period to place, screed, float and finish the whole pour, and there is no pausing to reconsider.
Where DIY is realistic
Slabs under about 15 square metres for a garden shed, a bin pad, an air conditioning condenser base or a simple flat patio are within reach of a competent owner with help. The work is level, the loads are light, the geometry is square and the consequences of a mediocre finish are cosmetic. Expect to save on labour but not on materials, and budget for at least three people on pour day.
Where it should always be professional
Driveways, garage slabs, any slab carrying a structure, any slab requiring a pre-pour inspection, and anything on a sloping or filled site should go to a licensed contractor. These slabs involve set out against fixed levels, engineered reinforcement, control joint planning and finish quality across a large area under time pressure. A driveway poured badly is a five figure problem to remove and replace, and it will be visible from the street for as long as you own the house.
Licensing thresholds vary by state and by the value of the work, and slabs attached to habitable construction almost always fall inside licensed building work. Before engaging anyone, confirm they hold a current licence for the class of work and that the licence covers concreting rather than a general trade. The BUILTLY guide to how to check a builder’s licence in Australia sets out the register to use in each state.
One middle path worth considering is doing the preparation yourself, excavation, formwork and base compaction, and bringing in a contractor to place and finish the concrete. Some contractors will accept this, others will not because they carry the risk if the preparation is wrong. Agree responsibility in writing before you start digging.
What to check before and after pouring
Before the pour
- Set out matches the approved plan and the intended structure, checked with a tape across both diagonals
- Excavation is to the correct depth and the base is compacted, not loose spoil raked flat
- Formwork is straight, braced and set to the correct falls, with a string line or level confirming it
- Mesh is the specified grade, lapped correctly and sitting on bar chairs, not resting on the ground
- Vapour barrier and termite management are in place where the slab supports habitable space
- Any required pre-pour inspection has been booked and passed, with the certificate recorded
- Concrete strength, slump and finish are confirmed on the docket against what was quoted
After the pour
- Surface is even, with no ponding water after rain or a hose test
- Falls run away from buildings and towards the intended discharge point
- Control joints are cut within the first day or two and at sensible spacing, generally no more than about 30 times the slab thickness apart
- Curing has been managed, whether by water, covering or a curing compound, rather than the slab left to dry out in the sun
- Edges are clean and consistent, with no crumbling or exposed mesh
- Finish matches what was specified, particularly for exposed aggregate and coloured work where variation is common
- Vehicles are kept off for 28 days
Fine surface cracking is normal in concrete and is not usually a defect. Cracks wider than about 1mm, cracks that step vertically, or cracks that run through the full slab thickness are worth raising with the contractor promptly while the work is fresh and the relationship is intact.
BUILTLY and lasting project records
Concrete work is easy to forget once it is covered by a shed, a car or an outdoor setting. The pre-pour photographs, the inspection certificate, the concrete docket and the finished result are the only evidence that the slab was built to the specification that was quoted.
BUILTLY is building a record of completed Australian homes that credits the builder, designers and trades behind each one.
Frequently asked questions
How much does a concrete slab cost per square metre in Australia?
For non-house applications such as sheds, garages, patios and driveways, most Australian homeowners pay somewhere between $85 and $180 per square metre supplied and laid, including excavation, formwork, mesh, concrete and a standard broom finish. The lower end of that range applies to simple, flat, easily accessed patio and shed slabs. The upper end applies to thicker garage and driveway slabs, sloping or restricted sites, and decorative finishes. Small slabs almost always cost more per square metre than large ones because setup, delivery and labour costs do not scale down.
How much does a slab for a 6m x 6m shed cost?
A 6m by 6m shed slab is 36 square metres. At typical rates of $95 to $140 per square metre for a 100mm slab with SL72 mesh on a level, accessible site, expect roughly $3,400 to $5,000 supplied and laid. Add cost if the site needs cut and fill, if a concrete pump is required because a truck cannot reach the pour, or if the shed will house vehicles or heavy equipment and the slab needs to go to 125mm or 150mm with heavier reinforcement.
Is a concrete slab cheaper than pavers for a patio?
A plain broom finished concrete slab is usually the cheapest permanent hard surface per square metre. Pavers cost more once bedding, edge restraint and laying labour are counted, though they are easier to lift and repair later. Exposed aggregate and stamped concrete finishes typically land in the same price band as mid range pavers, so the decision at that level is about appearance and maintenance rather than cost.
Do I need council approval for a concrete slab?
It depends on the state, the council and what the slab is for. A small at grade patio or garden slab is often exempt development. A slab that forms part of a shed, garage, carport or extension almost always sits inside a building approval for that structure, and the slab will be inspected before the pour. Anything that changes stormwater flow, sits over an easement or is close to a boundary usually needs approval. Check with your local council before you book concrete.
How long before you can use a new concrete slab?
You can normally walk on a slab after 24 to 48 hours depending on weather. Light loads such as shed frames are usually fine after about seven days. Vehicles should be kept off for 28 days, which is the standard period used to reach design strength. Driving on a slab early is one of the most common causes of premature cracking on domestic driveways.