Driveway kerbing and edging for tarmac: why the edge matters

Every tarmac driveway needs something solid along its sides. Tarmac has no strength at an open edge: without a kerb or border to hold it, the edge spreads and crumbles under car wheels, and that is often where a driveway starts to fail first. Driveway kerbing does that job. A run of kerbs, a granite border or a row of granite setts set in concrete holds the tarmac in place, and the choice between them comes down mostly to the look of the house and the budget. From its base at Newbridge, Delaney Tarmac fits kerbs and granite borders on tarmac driveways in Kildare and across Dublin, Wicklow, Laois and Offaly.

Why a tarmac driveway needs an edge

Tarmac is laid hot and rolled hard, and it can only be rolled tight against something firm. Against a kerb, the edge comes out dense and square. Against soil or loose stone, the roller pushes the material outwards and the edge is left thin and open. Water then gets in at the side, wheels break the edge away and the crumbling works its way in. As general good practice, the kerbs themselves sit on a concrete bed with concrete packed up behind them, so they cannot be pushed out either. Delaney Tarmac lays its tarmac by machine, a binder course with an SMA wearing course on top, and the edge is what that surface is finished against.

The edging options for a tarmac driveway

There are a few common ways to edge a tarmac driveway in Ireland, and they can be mixed on the same job.

• Concrete kerbs: the plainest and usually the least costly option. They come in straight and curved runs, so they suit a drive that sweeps around a lawn.
• Granite kerbs: natural stone in silver and grey tones, harder wearing and finer looking than concrete. Many Irish streets already have granite kerbstones, so a granite edge ties a driveway to the footpath outside.
• Granite setts: small squared blocks of granite laid in a row as a border, which frames a plain black surface.
• A granite apron: a wider band across the entrance, where every car crosses in and out and the wear is heaviest.

A real job: tarmac with a granite border

On one suburban driveway, the owners wanted a hard-wearing drive for two cars that did not look like a flat sheet of black. Delaney Tarmac machine-laid the tarmac and framed it in silver granite, with a wider granite apron across the threshold at the footpath and a granite kerb around a planted bed. The granite holds the tarmac edge so it cannot crumble or spread, and it matches the granite kerbstones on the street. The full job is on the tarmac driveway with a granite border project page.

"The base is everything. If the sub-base is wrong, the whole thing fails inside three years."

Paul Delaney, Delaney Tarmac

Repairing a crumbling driveway edge

Driveway edge repair is one of the most common small jobs on older tarmac drives, and it usually traces back to an edge that was never held. Patching the broken tarmac on its own does not last, because nothing has changed at the side. The proper repair cuts the tarmac back to a sound, straight line, sets a new kerb on a concrete bed with concrete behind it, then makes the tarmac good against it and seals the joint. Where the edge broke because the base below it went soft, the base is rebuilt first. The repairs the crew carries out are on the page for driveway repair in Dublin.

What edging adds to the price

Kerbing is priced by the metre on the visit, and the figure depends on the material, the length of the run, how many curves there are and whether old kerbs have to come out first. Concrete is the less costly choice and granite the dearer one. Edging is one of the factors in the cost of tarmac driveways in Dublin, alongside the sub-base and the area, and the surface itself is covered under tarmac driveways in Dublin.