The crack ran from the expansion joint near the garage door in a dead straight diagonal, maybe 4mm wide at its widest point, and the vendor’s agent had already told the buyers it was “just concrete doing what concrete does.” I’ve written that exact line into more contract negotiations than I can count, and it’s rarely the whole story. On this one, in a suburb built over old workings from the Hunter coalfield, that diagonal crack combined with a step in the slab where it crossed the joint told me the movement was ongoing, not historical. The buyers renegotiated by close to $3,000 before settlement.
A driveway isn’t load-bearing in the way a footing is, so a lot of buyers assume cracking out there is cosmetic. Inspectors don’t treat it that way, because a driveway slab sits on the same ground as everything else on the block and it moves first. In Newcastle that’s usually one of two things: reactive clay that swells and shrinks with the season, or old shallow mine workings that are still settling decades after the pit closed. Either way, a driveway crack is often the earliest visible sign of something the footing will show later.
A proper description covers width, direction, and whether the two sides of the crack sit level with each other or have stepped. A hairline crack under 1mm that runs with the slab’s control joints is routine shrinkage and gets a line in the report with no drama attached. A crack over 3mm, especially one that runs diagonally across a panel rather than along a joint, gets flagged as a movement crack and cross-referenced against anything similar under the house. I’ll also note whether the crack is fresh — sharp edges, no dirt or moss in it — or old and weathered, because that tells the reader whether it’s still active.
Driveways within a few kilometres of the coast take a different kind of punishment. Salt-laden air accelerates corrosion in any reinforcing steel sitting close to the surface, and once that steel starts to rust and expand, it cracks the concrete from the inside out in a pattern called spalling. It looks different to a movement crack — more like small craters with rust staining around the edges — and it tends to show up first at the driveway’s edges, where cover over the steel is thinnest. A slab showing this pattern at eight or ten years old, well short of the 25 to 30 years a well-poured driveway should give you, usually means the cover depth was skimped on the original pour.
For a resurfacing job on an already-sound slab, budget somewhere around $45 to $75 per square metre depending on finish. Full replacement of a two-car driveway, once you include removal of the old slab, typically lands between $6,000 and $11,000 in the Newcastle market. Those numbers matter at the negotiating table because a $2,000 defect quoted vaguely tends to get argued down, while a defect backed by a real trade estimate holds up. That’s the point at which I’ll tell a buyer to get a second set of eyes from actual concrete driveway contractors in Newcastle before they finalise any price adjustment, because the report tells you there’s a problem — it doesn’t tell you exactly what fixing it costs on that particular site.
Does every driveway crack need a structural engineer? No. Most fall into routine shrinkage and get noted without further action. Diagonal cracks over 3mm with a visible step, or cracking that lines up with similar movement under the house, are the ones worth a second opinion.
Can a cracked driveway affect finance or insurance? Rarely on its own, but if the report links the crack to broader site movement — old mine subsidence or reactive clay — some lenders will ask for a geotechnical report before settlement.
Is resurfacing enough, or does the slab need replacing? It depends on whether the movement is finished. A specialist can core-test or simply observe the crack over a wet-dry cycle; resurfacing over an active crack just brings it back within a year or two.