Driveways · Problem & repair
Cracked tarmac driveway: what the cracks are telling you
Tarmac rarely cracks for cosmetic reasons. The pattern of the crack tells you whether you are looking at a surface issue you can live with for years, or a base failure that will keep coming back however many times it is filled.
Before anyone quotes you for a full replacement, it is worth knowing which of the three common crack types you actually have.
How to tell this is your problem
- Fine hairline cracks that follow no pattern
- Interlinked cracking that looks like crocodile skin
- A single long crack running parallel to the edge
- Cracks that open in summer and close in winter
- Loose chippings gathering along the crack line
Repair or replace?
Repair when the cracking is isolated and the surrounding surface is firm underfoot. Replace when cracking is interlinked across more than roughly a quarter of the area, or when the surface visibly deflects as a car drives over it.
Repair options, cheapest first
- 01
Crack sealing
Suitable for isolated hairline cracks in an otherwise sound surface. The crack is cleaned out and filled with a hot-applied sealant. Cheap, quick, and honest about what it is - a way of keeping water out, not a structural repair.
- 02
Cut-out and patch
For localised failure the affected area is saw-cut back to sound material, the base is dug out, re-stoned and compacted, then re-surfaced. Expect the patch to be visible for the first year or two before it weathers in.
- 03
Overlay
A new wearing course over the existing surface. Only works where the base is sound and levels allow - the finished surface will sit 25-40mm higher, which matters at thresholds and garage doors.
- 04
Full excavation and re-lay
Where the cracking is widespread the only lasting answer is to take everything up, re-build the sub-base to the right depth, and lay fresh binder and wearing courses.
Why it happens
Thin or unbound sub-base
Tarmac is a flexible surface - it moves with whatever is under it. Where the Type 1 layer was laid shallow or never properly compacted, the surface flexes under a car and eventually fatigues into interlinked cracking.
No edge restraint
Without a kerb, block edging or haunched concrete, the outer 100-150mm has nothing holding it in. Cracks then start at the edge and creep inwards.
Water getting underneath
Once water reaches the sub-base it washes out fines, leaving voids. The surface then has nothing to bear onto and cracks over the hollow.
Roots and services
A shallow root or a backfilled service trench that was never compacted will telegraph a straight crack through the surface within a couple of years.
Cost and time on site
Indicative cost
Sealing and small patches are usually a few hundred pounds. A full re-lay is priced per square metre in the same range as any new tarmac driveway.
Typical duration
Patch repairs are typically a single day. A full re-lay on a two-car drive is normally two to four days.
Every quote is priced after seeing the site. Send a photo of the crack and we will tell you honestly whether it is a patch or a re-lay.
Cracked tarmac driveway: common questions
- Can you fill cracks yourself with a DIY product?
- For a genuine hairline crack, yes - a cold-pour bitumen sealant from a builders' merchant will keep water out for a season or two. It will not stop cracking that is caused by a failing base.
- Why does the same crack keep coming back after repair?
- Because the crack is a symptom, not the fault. If the sub-base beneath it is thin, wet or uncompacted, any surface repair sits on the same weakness and re-opens.
- Does cracked tarmac need replacing straight away?
- Not usually. Sealed cracks buy time. What you should not do is leave them open through a wet winter, because water in the base is what turns a crack into a pothole.
- Will a new overlay hide the old cracks?
- Only if the cracks are surface-level. Reflective cracking - the old crack pattern reappearing through the new layer - is common where an overlay is laid over structural movement.
Services that fix this
Related reading: Best Time of Year to Install a Driveway
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