A driveway or patio is only as good as what's underneath it. Skip proper groundworks and you'll see cracks, sinking, and drainage problems within a few years. Here's what goes into preparing ground for hard landscaping.
The Groundworks You Don't See
When you look at a finished driveway, you see the surface — block paving, resin, tarmac, or gravel. What you don't see is the 200–300mm of preparation underneath it. This is what determines whether your driveway lasts 5 years or 25.
Step 1: Excavation
The existing ground is excavated to a depth of:
- Paths and patios: 150–200mm
- Standard driveways: 200–250mm
- Heavy vehicle areas: 250–300mm
This removes topsoil, vegetation, and unstable ground. The soil underneath (subgrade) should be firm and compacted.
Step 2: Sub-Base Installation
The sub-base is the structural layer that supports weight. It's typically:
- Material: MOT Type 1 (crushed limestone/granite)
- Thickness: 100–150mm for patios, 150–200mm for driveways
- Compaction: Multiple passes with a vibrating plate or roller
A properly compacted sub-base doesn't move. This is what prevents sinking and cracking.
Step 3: Drainage
Hard surfaces create runoff. You need to manage where that water goes:
Options for Surface Water
- Fall to drain: Slope the surface towards a drain or channel
- Soakaway: Water drains into a pit filled with crates/rubble
- Permeable surface: Block paving with gaps, or resin over permeable base
Drainage Requirements
Any new or replaced driveway over 5m² that slopes towards the road requires planning permission unless you use permeable surfacing or direct water to a soakaway.
Step 4: Geotextile Membrane
A geotextile membrane between the subgrade and sub-base prevents the layers mixing. This is especially important on clay soil, where the sub-base can sink into the ground over time.
Step 5: Bedding Layer
The final layer before your surface material:
- Block paving: 30–50mm sharp sand
- Resin: Concrete base required
- Tarmac: Applied directly to sub-base
- Gravel: 50mm of gravel over sub-base
Surface Options: Pros and Cons
| Surface | Cost/m² | Lifespan | Drainage |
|---|---|---|---|
| Block paving | £40–£80 | 20–25 years | Permeable options available |
| Resin bound | £50–£90 | 15–25 years | Permeable (SUDS compliant) |
| Tarmac | £30–£50 | 15–20 years | Non-permeable |
| Gravel | £20–£40 | Indefinite (replenish) | Permeable |
| Indian sandstone | £50–£100 | 25+ years | Non-permeable |
Common Mistakes to Avoid
1. Shallow Excavation
Some contractors skip proper depth to save time and money. The sub-base ends up too thin, and the surface sinks within a year.
2. Poor Compaction
Sub-base needs multiple passes with a compactor. One quick pass isn't enough. The ground will settle over time, leaving dips and hollows.
3. Ignoring Drainage
Water that sits on or under a driveway causes damage. Freezing water expands. Standing water erodes the sub-base. Proper drainage is essential.
4. No Edge Restraint
Block paving and gravel need something to hold them in place. Without edge restraints (kerbs, blocks, or metal), the edges spread and the surface fails.
How Long Does It Take?
| Project | Duration |
|---|---|
| Small patio (20m²) | 2–3 days |
| Large patio (50m²) | 4–5 days |
| Standard driveway (40m²) | 4–6 days |
| Large driveway (100m²) | 7–10 days |
Cost Breakdown
For a typical 40m² block paved driveway:
- Excavation: £400–£600
- Sub-base (MOT Type 1): £600–£900
- Geotextile membrane: £50–£100
- Drainage: £200–£500
- Block paving: £800–£1,600
- Edge restraints: £200–£400
- Labour: £1,200–£2,000
Total: £3,450–£6,100 (or £85–£150/m²)
Why Choose DNDH for Landscaping Groundworks
We do the groundworks properly — full excavation depth, proper compaction, drainage solutions that work. Our driveways and patios don't sink, crack, or flood because the preparation is right.