Concrete driveway thickness — what's right for your job?
100mm, 125mm or 150mm? The right slab thickness depends on what's driving on it — and getting it wrong is the most expensive mistake in residential concreting.
Thickness is the cheapest insurance in a concrete driveway. An extra 25mm adds maybe 8% to a quote and roughly doubles the structural life of the slab. Here's how to pick the right number for your job.
100mm: standard residential
100mm is the minimum we'll pour on a residential driveway, and it's appropriate for daily-driver cars, small SUVs and light foot traffic. It must sit on a properly compacted sub-base with SL72 mesh in the upper third. Drop below 100mm and you're pouring a pathway, not a driveway — it will crack.
125mm: caravans, dual-cabs and boats
If you're parking a caravan, a 4WD with a loaded canopy, a boat trailer, or your tradie ute with a full toolbox, step up to 125mm with SL82 mesh. The thicker slab spreads point loads from jockey wheels and trailer feet — which are the number-one cause of cracked residential driveways in SEQ.
150mm: heavy vehicles and shared driveways
150mm with SL82 mesh and trim bars is the right call for shared battle-axe driveways, light commercial use, horse floats, or any slab a 6-tonne tipper will regularly drive across. Above this, you're into engineered slabs with designed reinforcement schedules — not something a domestic concreter should spec from a tape measure.
Control joints matter as much as thickness
A 150mm slab without control joints will still crack — just on its own terms. We saw or tool joints at roughly 3m intervals (no more than 30× the slab thickness) within 12–24 hours of the pour. Joints control where the cracks go. Skip them and the slab decides for itself.