Concrete Driveway Thickness & Reinforcement — Perth Spec Guide

Standard Perth residential driveway specification

• Slab thickness: 100mm minimum for cars, 125mm for heavier vehicles (caravans, boat trailers, work utes).
• Reinforcement: SL72 mesh minimum for cars, SL82 for heavier loads and reactive clay ground.
• Base: 100mm of compacted road base (95%+ compaction), more on reactive clay.
• Concrete strength: 25 MPa minimum, 32 MPa preferable for honed and polished finishes.
• Control joints: Saw-cut within 24 hours of pour, 1/4 slab depth (25mm on 100mm slab), 3–4m spacing max.
• Thickened edge: Required where driveway carries heavier vehicles; adds 300mm depth around perimeter.
• Fall: 1:60 minimum away from the house for drainage.

When to upgrade from 100mm to 125mm

• Driveway carries a caravan, boat trailer or heavy work ute regularly.
• Ground is reactive clay (eastern corridor Perth: Ellenbrook, Aveley, Byford foothills).
• Driveway supports a workshop building or car hoist point loads.
• Long driveway (over 20m) where centre-line deflection matters.
• Property is in an area with heavy service vehicle access (bins, delivery trucks).

SL72 vs SL82 mesh — what's the difference?

The numbers refer to bar diameter and centres. SL72 has 7mm bars at 200mm centres. SL82 has 8mm bars at 200mm centres. SL82 gives roughly 30% more reinforcement area per m² and better crack control on reactive ground. The cost difference is small ($6–$10 per m²) and worth spending on any driveway that will see more than passenger car loads or that sits on clay.

When to add a thickened edge

A thickened edge is a beam of concrete 300mm deep and 300mm wide cast around the perimeter of the slab (or along the vehicle-loaded edges). It stops the edge lifting under wheel loads and stops the slab settling at the edges. Required for driveways carrying anything heavier than a passenger car; strongly recommended even for standard driveways on reactive clay. Adds roughly $450–$800 flat to a typical driveway.

AS 3727.1 residential pavement guidance

Australian Standard AS 3727.1 (Residential pavements — Concrete pavements) provides the technical framework for residential driveway design in Australia. It covers slab thickness, reinforcement, joint spacing, subgrade preparation and finishing tolerances. Any competent Perth concreter will design and pour to AS 3727.1 without needing to be prompted. If a quote is silent on the standards being followed, ask — it's a fair question and reveals a lot about the operator.

How to check your quote isn't under-specced

• Ask what thickness. If the answer is under 100mm, walk away.
• Ask what mesh grade. Vague answers ("standard mesh") suggest they're guessing.
• Ask about joint spacing. "We'll saw-cut appropriately" isn't good enough — you want 3–4m max.
• Ask about the thickened edge. If your driveway will carry a caravan or boat trailer, this should be mentioned unprompted.
• Ask about MPa. 25 MPa minimum. 32 MPa if honed or polished finish specified.
• Ask about base thickness and compaction. Should be 100mm+ of road base, plate-compacted to 95%+.