Why is my driveway sinking? Causes, repair and cost

A sinking driveway is nearly always telling you something about what is underneath it. The tarmac on top rarely fails on its own: a dip forms where the sub-base below has been squeezed down, softened by water or was never built to carry the weight. The fix is to cut out the sunken section, rebuild the base under it and lay new surface on top, and the cost of a sinking driveway repair depends on how much of that base has gone. A dip in one spot is a local repair, priced on its area after a visit. A drive that is dropping in several places needs rebuilding from the ground up, which costs much the same as a new driveway: €90 to €110 per square metre for tarmac in Ireland, according to HomePros (August 2026).

Why driveways sink

Paul Delaney has spent 45 years laying and repairing driveways across Dublin, Kildare, Wicklow, Laois and Offaly, and the causes under a sunken drive are the same few every time.

• A sub-base that was too thin, or loose fill that was never compacted, so it settles under the weight of cars.
• Soft ground, such as heavy clay or bog-edge ground, with no membrane under the stone to stop the base pressing down into it.
• Water getting under the surface from a blocked gully, a downpipe emptying onto the drive or falls that send water the wrong way, softening the ground beneath.
• An old trench for a water, gas or waste pipe that was filled back in without proper compaction.
• Heavier vehicles than the driveway was built for, such as a skip lorry or a delivery truck, standing on the same spot.

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

Paul Delaney, Delaney Tarmac

A dip in one spot, or the whole drive?

The first job on any visit is to work out which of the two it is. A single dip by the gate, along an old trench line or where a van always parks usually has a local cause, and the rest of the driveway is sound. Water lying in the hollow after rain, cracks fanning out around it and an edge that has started to spread are the usual signs. When the surface is dropping in several places, or cracking in a crazed pattern across the whole drive, the base has failed more widely and patching one hollow only moves the problem along.

How a sunken section is repaired properly

A proper repair does not just fill the dip. The sunken area is cut back to a straight edge in sound tarmac, then dug out to firm ground so the cause can be found and dealt with, whether that is soft ground, a wet spot or a badly filled trench. The sub-base is rebuilt in compacted stone, at 150 to 200mm on sound ground and 250 to 300mm on soft ground as general practice, and the tarmac goes back in two layers, a binder course and an SMA wearing course, with the joint sealed so water cannot get in at the edge.

What does not work is a fresh layer of tarmac laid over the top. The new surface follows the hollow underneath and the dip comes back. The wider choice between a repair, a resurface and a full replacement is set out in driveway repair vs resurfacing, and the repairs the crew carries out are on the page for driveway repair in Dublin.

What a sinking driveway repair costs

There is no honest single figure for fixing a dip, because the price follows the size of the area, how deep the dig has to go and what is found underneath. A local repair is priced on its own area and depth after a visit. Where the whole base has gone, the job is in effect a new driveway, priced in line with the HomePros range above. The visit is what tells you which side of that line your driveway is on, and Paul Delaney looks at every driveway himself before a price is given.

A worked example: a country entrance that had settled

A gated country entrance Delaney Tarmac rebuilt shows the pattern. The approach was loose gravel over hardcore that had broken up and settled unevenly, held water and tracked stone toward the road. Tarmac laid straight over it would have sunk the same way, so the old surface was stripped, the base prepared and fresh tarmacadam laid to an even finish. The full before and after is on the country entrance tarmac driveway project page.

"We are usually called in to lift bad jobs and start again. That is not how we want to be working."

Paul Delaney, Delaney Tarmac

That is why the base gets the time on every job, and why the work carries a five-year workmanship guarantee.