Concrete Driveway Calculator — Slab, Mesh & Formwork

A domestic concrete driveway should be at least 150mm (6 inches) thick. For heavier vehicles (SUVs, campervans), increase to 175-200mm. The slab should be reinforced with A193 mesh (or A142 minimum) on chairs in the upper third of the slab — about 50mm cover below the finished surface — where crack-control reinforcement works best (sitting mesh at the base makes it largely ineffective). Specify a BS 8500 designated paving mix: PAV1 (C30/37, air-entrained) for normal domestic drives, or PAV2 (C32/40, air-entrained) where the surface is regularly treated with de-icing salts or adjoins a salted road (XF4 exposure). The air entrainment (3.5-6%) is what gives freeze-thaw and de-icing-salt durability — it is dosed at the batch plant and cannot be achieved by hand or drum mixing, so order PAV ready-mix rather than a plain C30.

Expansion joints (also called movement joints) should be placed at maximum 3m centres in both directions. They prevent random cracking as the concrete expands and contracts with temperature changes. Use a compressible filler board (10mm thick) with a flexible sealant on top. Also place joints where the slab meets walls, manholes or other fixed structures.

A193 mesh is the standard choice for domestic concrete driveways (7mm wires at 200mm centres, 11.52 m² per 4.8m x 2.4m sheet). A142 (6mm wires) is acceptable for lightly-used slabs. A252 (8mm wires) is used for heavy-duty or commercial applications. Adjacent sheets must lap by at least two full squares plus 50mm — 450mm for 200mm-centre fabric (UK practice minimum 350mm) — and be tied together with wire. This calculator adds 20% for these laps and offcuts on a perimeter-lapped layout. Position the mesh in the upper third of the slab with at least 50mm cover all round.

Yes, a minimum 150mm of compacted Type 1 sub-base is essential. Use our Type 1 Sub-Base Calculator for quantities. It provides a stable, even formation and prevents the concrete slab from cracking due to differential settlement. Compact in 75mm layers using a vibrating plate. On soft clay soils, consider increasing to 200-250mm or using a geotextile membrane.

For a standard 150mm thick slab, you need 0.15 m³ of concrete per square metre. A typical 50 m² driveway needs approximately 7.5 m³ plus 10% wastage = 8.25 m³. This would require 2 loads from a ready-mix truck (standard 6 m³ capacity) with a small part-load surcharge on the second delivery.