Engineering 6 min readUpdated Jul 2026
Overlay vs full reconstruction, how we decide on site
The wrong answer here is what makes new driveways fail twice.
Overlaying an existing driveway is faster, cheaper and less disruptive. It is also the single biggest way a new surface can fail early, because you are trusting whatever is underneath to perform for the next 20 years. The decision is an engineering one, not a pricing one.
When an overlay is the right call
- The existing surface is structurally sound (no rocking blocks, no cracked concrete slabs, no failing tarmac)
- Levels drain positively, no ponding, no reverse falls into the house
- There is enough kerb / threshold height to gain 20 to 40 mm of build-up without burying door thresholds or air bricks
- The base is bound (sound tarmac, sound concrete), loose scalpings or gravel is not an overlayable base
When we insist on full reconstruction
- The existing base is moving, cracked or dished
- Water is trapped in or under the surface
- The drive was originally laid on soft ground with no proper sub-base
- Utilities need to be re-routed, gullies added or SUDS drainage introduced
- The block paving is settling because the edge restraint has failed
| Overlay | Full reconstruction | |
|---|---|---|
| Typical cost | 40–60% of a full rebuild | Full engineered price |
| Programme | 3–6 working days | 7–15 working days |
| Guarantee | 5 years installation, contingent on base condition | 5 years installation, independent of prior surface |
| Risk | Only as good as the base beneath it | None, designed from subgrade upwards |