Tarmac Driveway Repair: What You Can Fix and What Needs Relaying
Updated: 3 days ago
Most damage to tarmac driveways can be repaired if the base underneath is still sound. Small potholes and cracks can be patched by a homeowner with cold lay and crack filler; larger patches are better cut out and reinstated hot by a contractor. Sinking, spreading potholes and ruts usually mean water has got into the base, and that is when repair turns into resurfacing or a full relay.
What causes tarmac to break up?
In rough order of how often we see them on drives around Wolverhampton:
Water getting into the layers. A hairline crack lets water in, frost expands it, traffic pumps it, and the hole grows. This is how most potholes start.
A thin build or no proper base. A drive laid on soil, or with little sub-base, flexes under every car. It ruts and cracks early.
Missing edge restraint. Tarmac with no kerb or edging along a free edge has nothing to hold it. The edge crumbles away in a rough line.
Poor drainage. If falls are wrong, water sits on the surface or runs under it, softening the base.
Roots and soft spots. Tree roots lift the surface; old trenches, buried rubbish or clay pockets settle and leave dips.
Age. Oxidised, brittle surface course loses stones in the wheel tracks and crazes over a wide area.
What can you check yourself?
Walk the drive after rain. Puddles show where the surface has dropped or the falls are wrong. Press a screwdriver into cracks: if the material either side is firm, the crack is a surface problem. If the edges are loose and lift out, water is already under them.
Look at the pattern. A single pothole next to a downpipe is usually a local water problem. A line of potholes in the wheel tracks, a spreading area of crazing (cracks like crocodile skin) or a dip you can feel underfoot points to the layers below.
How to repair cracks in a tarmac drive
Hairline and narrow cracks are a fair DIY job. Brush them out, blow out the dust, make sure they are dry, then fill with a bitumen crack sealer or a pourable crack filler. The aim is simply to stop water getting in. Wider cracks may need a backing of fine material before the sealer goes in. Sealing cracks before winter is the cheapest bit of maintenance a tarmac drive gets.
How to repair a pothole in a tarmac drive
Small potholes can be filled with cold lay tarmac. Cut back to sound edges, clean and dry the hole, fill in layers, overfill slightly and compact hard. The detail is in our guide to cold lay; the short version is that compaction matters more than the product.
For bigger holes, or a patch that has to last, a contractor will usually cut a neat square around the damage, take out the failed material, sort any soft base, then reinstate with hot material in layers and seal the joints. A few UK surfacing firms also offer infrared repair, a method more common on roads and car parks than on drives: the existing surface is heated until it can be raked, topped up with new material and rolled, so the patch fuses with the surrounding surface rather than sitting in a cut hole. One UK cost guide puts a single pothole repair at around £100; as with any figure, a site visit is the only way to price your drive.
Why is my tarmac drive sinking?
A sunken patch means something under the tarmac has moved. The most common causes are a sub-base that was too thin or never compacted properly, a soft spot such as an old trench or rotted roots, or water washing fines out of the base. Filling the dip with more tarmac adds weight and hides the cause, so it tends to drop again.
The proper fix is to cut out the sunken area, dig down to firm ground, rebuild the sub-base with compacted MOT Type 1, and reinstate the binder and surface course. If the sinking is widespread, the whole drive needs relaying. On one tarmac drive we laid in Finchfield, the job involved removing five large tree roots and laying 16 tonnes of Type 1 sub-base before any tarmac went down; that is the kind of groundwork that stops sinking coming back.
Why are weeds growing through my tarmac?
Weeds need a gap and some soil. They appear where tarmac is thin, along unsealed edges, in cracks, and where a drive was laid without a proper base so soil sits just under the surface. Pulling or killing the weeds treats the symptom; sealing the cracks and edges removes the way in. If weeds are coming through the middle of a drive everywhere, the build-up is too thin and will keep letting them through.
Frayed and crumbling edges
Edges break up when there is nothing holding them. Pavingexpert is blunt that edgings or kerbs must be used on the free edges of a bitmac drive. Patching a crumbling edge without fitting a restraint just moves the failure a few centimetres inward. The repair is to cut back to sound material, fit a kerb, block or brick edging on a concrete bed, and reinstate the tarmac against it.
When does repair become resurfacing or relaying?
Patch when the damage is local and the drive is otherwise firm. Resurface when the surface is worn or crazed over a wide area but the base is solid and levels allow a new surface course on top. Relay when the drive is sinking, rutting or breaking up in many places, because the problem is underneath.
The difference matters for cost. Most new tarmac drives are quoted at £50-£90 per m² in published UK cost guides, as our tarmac driveway cost guide sets out (Checkatrade's average is around £90 per m² including labour), and patching is a fraction of that, so it is worth getting the diagnosis right before spending either way. When a drive has gone past repair, we dig it out and rebuild it, with a 10-year guarantee on the finished job.
Tarmac repair questions, answered
Can you repair tarmac in winter?
Small cold lay repairs can be done in most weather as long as the hole is dry. Hot repairs and new surfacing need milder, drier conditions, because hot material cools too quickly in the cold to compact properly, and cold, damp weather also slows how long tarmac takes to dry afterwards.
Will a repair match the rest of the drive?
Not exactly at first. New tarmac is blacker than an older surface and stands out for months until it weathers. A drive covered in mismatched patches is often a sign a resurface would look and last better.
Are road planings a cheap fix for a broken drive?
They are cheap, but road planings are a loose, partly bound material, not a repair for a bound tarmac surface.
Not sure what you are looking at?
Ask Pete to come and have a look. Over 25 years of laying drives around Wolverhampton and south Staffordshire, we have repaired plenty and relayed plenty, and we will tell you which one yours needs. Book a free site visit.
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