A pothole is a symptom. We look at the cause too.

How a pothole forms

Asphalt is porous. A hairline crack lets water reach the granular base underneath. In winter that water freezes and expands by roughly nine percent, pushing the asphalt upward. When it thaws, the void stays and the asphalt above it has nothing to bear on.

The next vehicle that drives over it punches through. That is why potholes appear almost overnight in late winter and early spring, and why they are always deeper than they look from the surface.

A proper patch versus a throw-and-go

The cheap version is cold patch shovelled into the hole and tamped with a boot. It lasts weeks. Water gets around the edges immediately because nothing was cut square and nothing bonded.

The right version squares the hole with a saw cut, removes all loose material down to sound base, compacts the base, applies a tack coat to the vertical faces so the new asphalt bonds to the old, then fills in compacted lifts and rolls it flush.

The difference in cost is not large. The difference in how long it lasts is measured in years.

When patching is the wrong answer

One or two potholes in a driveway that is otherwise sound: patch them. Several appearing in the same area every spring: the base under that section holds water, and you will be patching it annually until it is excavated and rebuilt.

We tell you which situation you have on the first visit, because paying for the same patch three years running costs more than fixing it once.

Questions