Tarmac driveways cost per m², built up properly

The gang is racing a temperature, not a clock

Hot-laid tarmac arrives at around 140°C and has to be spread and rolled before it drops below roughly 105°C. In practice that is a 30 to 45 minute window from the lorry tipping to the roller finishing, and less on a cold or windy day. Compact it too late and the surface never reaches density - it looks fine, and it ravels within two winters.

That is why a tarmac gang is four hands rather than two, and why it prices a day rather than an hour. You cannot pause a load, and a load that goes cold on the wagon is scrap you have paid for.

Why base course and wearing course are separate operations

They are two different materials at two different depths doing two different jobs. The base course carries the load and takes up the level; the wearing course is the finish and is thinner, finer and more expensive. Both go through the same laying and rolling, so each is roughly 100 m² a day for the gang.

Plenty of jobs are only one of them. An overlay on a sound existing surface is wearing course alone. A car park built up from a fresh sub-base is both, on separate days. Slide the one you are not doing to zero rather than halving a combined rate and hoping.

Joints are where tarmac fails, and they cost time

Every joint - between loads, between days, against an existing surface, around an ironwork cover - is a potential weak line. Done properly they are cut back, tacked and rolled through; done in a hurry they open up and let water in, and water is what finishes a driveway.

• Access for the wagon and roller. A drive the roller cannot get onto is hand-tamped, and hand-tamped tarmac is a fraction of the output and never as dense.
• Shape. Long straight runs are quick. Narrow drives, tight radii and edges against a garage threshold are all hand work at the exact moment the material is cooling.
• Ironwork. Manholes, gullies and stop taps each need cutting round and finishing by hand.
• Weather. Below about 10°C ambient the window shortens sharply; in rain you do not lay at all, because water trapped under the mat is a delamination waiting to happen.

What is not in this rate

The sub-base. On a new driveway the dig, the muck away and the Type 1 laid and compacted are usually more work than the surfacing, and they are priced on the excavation and sub-base calculators. Kerbs and edgings are separate too.

The tarmac itself is a material, and the roller and whacker are plant - both go in the job section as lump sums, alongside the skips if you are carrying the dig.