Cracked driveway repairs

Reading the crack is most of the job. A single straight crack across a concrete slab, with both sides level and no movement, is shrinkage — concrete shrinks as it cures and it will crack somewhere, which is precisely why control joints exist. It is a sealing job, not a structural one. A crack with a step across it, where one side is lower than the other, means the ground under one side has moved and it is a base problem. A network of interconnected cracks across a tarmac drive — what the trade calls crazing or crocodile cracking — means the base has failed under load across an area, and no amount of crack filling addresses that.

Edge cracks running parallel to the perimeter, a few inches in, are their own story and a very common one. They mean the edge is unsupported — either there was never a proper restraint, or the ground beside the drive has eroded away from underneath it — and the surface is breaking off along the line where it loses support. Filling that crack achieves nothing; the edge needs restraining or rebuilding.

Water is what turns any of them into something worse, and frost is what does the actual work. A crack lets water into the base. The base softens. Water sitting in the crack freezes, expands, and levers the two sides apart a fraction of a millimetre each time. Around here that happens more often than the national average suggests: the Met Office records air frost from roughly twenty days a year on the coast to over seventy-five in the higher Pennines, with Buxton at 51.5 days against 40.0 at low-lying Woodford, and the ground east of Macclesfield rises fast — Kerridge Hill 313 metres, Shutlingsloe 506.

The repair depends entirely on which kind you have. A dormant shrinkage crack gets routed out to a consistent width and depth and filled with a flexible sealant that can accommodate the seasonal movement — not a rigid mortar, which simply cracks again alongside the old crack. A live or stepped crack means opening the area up, dealing with whatever is moving underneath, and reinstating properly. A map-cracked area means the base has gone under it, and that section is a rebuild.

There is a specific trap on imprinted concrete worth naming, because it comes up constantly. Imprinted concrete cracks like any other slab, and it cannot be repaired invisibly — a filled crack is a visible line and a patched area is a visible patch, whatever anybody promises about colour matching. The realistic options are to seal it and accept the line, or to overlay the whole drive. That is a good argument for asking hard questions about joint layout before choosing imprinted concrete rather than after.

A crack is not an emergency and nobody should present it as one. What it is, is cheap to deal with now and expensive to deal with in two winters, because the sequence from crack to pothole is reliable. Sealing a dormant crack before winter is genuinely worthwhile, uncomplicated work — and it is exactly the sort of small job that a contractor with no interest in selling you a new drive is happy to do.