What drives concrete cost

Larger pours are cheaper per square foot than small ones. Mobilisation, forming setup, finishing crew and minimum concrete delivery charges are largely fixed, so they spread across a bigger area. A very small pour can cost nearly as much as one twice its size. If you are considering doing a driveway now and a parking pad next year, ask what it costs to do both at once — the difference is often surprising.

Going from four inches to six increases concrete volume by half. That is a real cost, and it is the right call for RV pads, heavy vehicle areas and lift bays, and the wrong call as a blanket upgrade. Reinforcement — fibre through the mix versus steel mesh or bar on chairs — is a smaller cost difference than most people assume, and steel is worth it more often than it gets specified.

Removing an existing slab is priced on weight and access, not area. Roughly 1.3 tons per 100 square feet at four inches thick. A six-inch reinforced slab is heavier, slower to break, and slower to load because the steel has to be cut free. A slab a machine can reach is dramatically cheaper to remove than one behind a house.

This is the line item most often missing from a cheap quote. Excavating to depth and placing compacted aggregate costs money in labour, material and machine time. Skipping it saves a meaningful amount on day one and is the reason a driveway fails in year five instead of year twenty-five. If a quote does not state a base depth, ask.

Whether a mixer can back to the forms is one of the largest single swings in a concrete price. Where it cannot, concrete is pumped or moved by buggy, which is more equipment and considerably more labour. A back-garden slab with gate-only access is a different job from a front driveway, even at identical size.

A standard broom finish is included in any normal quote. Exposed aggregate, saw-cut patterns, integral colour, borders and radius edges all add labour. Decorative work is genuinely more skilled and more time-consuming, and a suspiciously low price for it usually means it is being done quickly.

Poor subgrade, buried debris, a previous slab underneath, drainage that has to be corrected, or tree roots that need managing all change scope. A responsible estimator flags the risk of these at quoting stage rather than discovering them on the day and issuing a variation. We tell you what we can see and what we cannot.

• Does it state base material and compacted depth?
• Does it state slab thickness, and is that thickness different where load is higher?
• Does it state reinforcement type?
• Does it state control joint spacing and how joints are formed?
• Does it include disposal, or is haul-off extra?
• Does it state the cure period before you can drive on it?

If a quote answers all six, you can compare it to another that answers all six. If it answers none, the price is not information.