What this page is for
Three quotes for one driveway can come back a third apart and all three can be honest, because each describes a different slab. The dearest may have a compacted base and mesh on chairs; the cheapest may have neither. Nothing on the surface tells you which. This page names the parts so you can ask for them. The relevant standards are AS 3727.1 for residential pavements, AS 3600 for concrete and AS 2890.1 for driveway grades, with each council's drawing taking over at the boundary; those drawings are compared in the Section 138 guide.
Ground first
Nothing else on this page matters until the ground has been read. Around Maitland there are four kinds. River alluvium, clay, silt and sand to great depth, under Central Maitland, Tenambit, the low parts of Morpeth and Bolwarra and the town of Raymond Terrace, which swells and shrinks with the seasons and can hold water near the surface. Residual clay on the low hills of Rutherford, East Maitland, Gillieston Heights and Chisholm, shallower but still reactive. Coalfield clay around Cessnock, Kurri Kurri and Greta, some of it over old workings. And the fine sand of the Tomago and Tomaree sandbeds under Medowie and Nelson Bay, which drains through and holds no edge. Add builder's fill on any estate lot, benched to make a flat pad. The Hunter clay guide takes the floodplain case further.
Under the slab
Topsoil, roots, soft clay and old surfacing are removed. The subgrade is trimmed to something firm and, where the ground wants it, a granular base is placed and compacted in layers, deeper over reactive clay and over fill. On sand the base has to be held in at the edges so it cannot walk. A plastic membrane goes under the slab where the ground is wet or salty. The base is shaped to the finished falls so no water can pond beneath the concrete. This is the step that a low quote leaves out, and the one you never see again.
The steel
Mesh restrains cracks only when it is in the middle of the slab, which means it sits on bar chairs at the right spacing before the pour and the concrete flows under it. Mesh dropped on the base and covered does nothing. SL72 is the usual residential driveway mesh; heavier sheets go where a caravan, a boat or a truck will stand. Extra bars are placed at re-entrant corners and around pits, and dowels tie a new slab to an old one where the two must stay level.
How thick
- Paths: 75 to 100 mm, and 100 mm with mesh anywhere a mower, a wheelbarrow or a car might cross.
- Driveways: 100 mm in 25 MPa or stronger concrete with SL72 mesh for cars; thicker and heavier for large vehicles.
- Council crossings: 125 mm in 32 MPa with SL72 in Maitland City; 125 mm in N32 with SL82 on 150 mm of DGS20 base in Cessnock City; to the drawing issued with the approval in Port Stephens.
- Patios and alfresco slabs: 100 mm, with a joint at the house.
Sheds and garages
The shed supplier's engineering is the specification, and the concreter pours to it. It gives the slab thickness, the mesh, the depth of the thickened edge under the frame and the hold-down positions. A rebate along the roller door line keeps rain outside. Where a hoist or a heavy vehicle will stand, the slab is thickened under it. Open carports get a slight fall. The house's own slab and any granny flat are certified building work outside this site. The rates and the common sizes are in the shed slab cost guide and the service is described under shed and garage slabs.
Beside the house
A path along a wall finishes below the damp course, falls away from the wall, leaves weep holes and vents open, and is separated from the house by a joint so the two can move on their own. Taps, downpipes and pits are boxed around rather than buried. On clay, a path that slopes towards a house is the start of a damp problem, so the levels are agreed before the concrete arrives.
Cracks, planned
Concrete will crack. The job of a joint is to decide where. Control joints are tooled in or saw cut at short intervals, at every change of width and at the porch and garage lines, and they are cut before the concrete has cracked on its own. Maitland City Council's footpath drawing puts dowelled expansion joints at 8 metre spacing and tooled joints at 2 to 4 metres depending on width, with a full depth expansion joint at the boundary; Cessnock City Council asks for expansion joints either side of a crossing. Isolation joints separate the slab from walls, footings and older concrete.
Where the water goes
Falls are set from levels taken on the day, not from a rule of thumb. Water leaves the slab towards the street, a pit or a grated drain and never towards the house, the garage or next door. Where a driveway falls to the garage, or sits below the road, Maitland City Council's driveway document calls for a grated trench drain at the low point. On the flat streets of the floodplain the drainage is the design.
On top
Broom finish for grip, coloured concrete with the oxide through the load, or exposed aggregate washed back to stone. Concrete keeps gaining strength for about four weeks; walking on it the next day is fine, driving on it usually waits a week or more, and Maitland City Council asks for a new crossing to be kept closed to traffic for seven days. Sealer suits coloured and exposed finishes inside the boundary. At the kerb, Maitland keeps the kerb, gutter and layback plain, Cessnock asks for plain uncoloured non-slip concrete, and Port Stephens accepts any non-slip finish.
Mine subsidence
Declared districts cover parts of the Maitland City and Cessnock City areas, including Maitland West, East Maitland, Louth Park, Greta, Tomalpin and Branxton. Flat concrete is rarely affected, because the Subsidence Advisory NSW exempt list clears driveways and hard stand spaces under every guideline except 4 and 5. Sheds and garages are cleared by size and guideline, so a large shed on a lot under a stricter guideline may need an approval that changes the slab. The NSW Planning Portal Spatial Viewer shows whether a lot is in a district. Port Stephens has no districts.
Reading a quote against it
Ask for thickness, mesh, concrete strength, base preparation, joint layout and falls to be written into the quote, along with who prepares and lodges any council application. Then set the quote beside this page, the cost guide and the calculator. Where old concrete is coming out first, removal and replacement explains what to expect once the slab is up, and patios and alfresco covers the slab that meets the house. When one quote is much cheaper, the difference is nearly always underground.