In short
Tarmac cracks when the ground under it moves or when water gets in and freezes. Fine surface crazing on an older drive is usually the surface drying out and is cosmetic. Cracks that run in lines, sink at the edges or form a map pattern mean the sub base is failing, and no amount of patching on top will hold.
This is a job for our Tarmac & Asphalt service.
What the pattern of the cracks tells you
The shape of the cracking tells us more than the number of cracks. We look at three things on a site visit.
- Fine, random crazing across the surface. The bitumen has aged and dried in the sun. The drive is still sound underneath. This is the least serious kind.
- A crack along the edge, with the edge dropping. The tarmac has no edge restraint or the ground beside it has washed away. Cars running over the unsupported edge break it off.
- A map or crocodile pattern, often with a dip. The sub base has moved or gone soft. Water is getting into the stone under the tarmac and the surface is flexing every time a vehicle passes.
Why it happens on drives in our area
Most of the cracked drives we see between Horsham and Guildford share one cause: not enough compacted stone under the surface. Tarmac is a wearing layer, not a structure. It relies on a properly compacted sub base to carry the load. A thin base over Wealden clay will heave in a wet winter and shrink in a dry summer, and the tarmac follows it.
Water does the rest. Once a crack opens, rain gets in, freezes, expands and widens it. Drives with no fall and no drainage go first. MyJobQuote's 2026 tarmac guide puts the life of a well laid tarmac drive at 20 to 30 years with light use and regular maintenance. The drives we replace after ten are almost always base failures, not tarmac failures.
Repair or relay
The honest answer depends on what is underneath, so we lift a small section or probe the base before we quote.
| What we find | What we recommend |
|---|---|
| Surface crazing, base firm | Leave it, or seal the surface. No structural work needed. |
| Isolated cracks or a pothole, base firm | Cut out the failed area square, recompact the base and patch with hot tarmac. |
| Map cracking or sinking, base soft | Dig out, rebuild the sub base with compacted Type 1 and relay the tarmac. |
What we do differently on a relay
When we rebuild a drive we sort the ground first: dig to firm material, lay and compact the stone in layers, put in edge restraint and give the surface a fall to a drain, a soakaway or a border. The Asphalt Industry Alliance notes that asphalt is fully recyclable, so the old surface we lift goes for reuse rather than landfill. Only then does the new tarmac go down. That order is the difference between a drive that lasts and one that cracks again in three winters.