Paving Stones & Slabs
A driveway or patio laid in block paving is a long-term investment. Learn about sub-base construction, frost depth, drainage and laying patterns — so the work lasts 30+ years.
Materials & Applications
| Type | Thickness | Application | Approx. cost |
|---|---|---|---|
| Concrete block paving | 60 mm | Patio, path, garden | £20–50/m² |
| Concrete block paving | 80 mm | Driveway (car) | £25–60/m² |
| Concrete block paving | 100–120 mm | Driveway (heavy traffic) | £35–80/m² |
| Natural stone (granite setts) | 40–80 mm | Prestigious, premium finish | £60–180/m² |
| Concrete flags / slabs | 50–70 mm | Patio, path | £30–90/m² |
| Slate flags | 20–40 mm | Patio, entrance | £40–120/m² |
Costs are indicative for materials only, excluding VAT and labour.
Construction Layers
A correctly built layer structure is essential for frost resistance and long-term stability. Getting this wrong is the most common cause of settlement and frost heave.
| Layer | Material | Thickness | Purpose |
|---|---|---|---|
| Paving units | Concrete / natural stone | 60–120 mm | Wearing surface |
| Bedding layer | Sharp / grit sand (0/4 mm) | 30 mm target / 20–40 mm | Fine levelling — never exceed 40 mm |
| Sub-base | Crushed stone MOT Type 1 (0/32–0/63 mm) | 150–300 mm (use dependent) | Load distribution and drainage |
| Capping / fill | Hardcore 20–120 mm (Type 1) | 150–250 mm (heavy traffic) | Frost-free zone, load spread |
| Existing subgrade | — | — | Remove if poor bearing capacity |
Layer thickness by use
| Use | Paving thickness | Sub-base | Total excavation |
|---|---|---|---|
| Path / patio (foot traffic) | 40–60 mm | 100–150 mm | 20–25 cm |
| Driveway (private car) | 60–80 mm | 150–200 mm | 25–35 cm |
| Parking / heavy traffic | 80+ mm | 200–300 mm | 35–50 cm |
Bedding layer (30 mm) and paving thickness are in addition to the sub-base figures. Paving units thinner than 50 mm are not suitable for any trafficked surface.
Frost Depth & Sizing
The combined thickness of sub-base and capping layers must exceed the local frost depthⓘfrost depthThe depth to which ground freezes in winter. Frost heave occurs when water in the ground freezes and expands, lifting the paving surface. Frost depth varies significantly by climate and location. for your region. Always use non-frost-susceptible (granular) materials throughout. This "total thickness vs frost depth" approach is a simplification — proper frost design also depends on how frost-susceptible the subgrade is, on drainage, and on the traffic, so on clay/silt subgrades or under heavier use follow a proper pavement design or local guidance rather than thickness alone.
| Climate zone | Typical frost depth | Recommended total depth |
|---|---|---|
| Mild coastal (e.g. SW England, Atlantic coast) | 0–15 cm | 20–30 cm total |
| Temperate lowland (central / northern UK, NW Europe) | 15–30 cm | 30–45 cm total |
| Cold continental (northern / eastern Europe) | 60–100 cm | 70–110 cm total |
| Subarctic inland (Scandinavia, northern Canada) | 100–200 cm | 110–200 cm total |
Laying Patterns
The pattern affects aesthetics, interlock strength and waste percentage.
Running bond — good interlock and attractive appearance
| Pattern | Waste | Interlock | Difficulty |
|---|---|---|---|
| Stretcher bond | 5–7% | Moderate | Easy |
| Running bond (half-brick) | 5–8% | Good | Easy–Moderate |
| Herringbone (45°) | 10–15% | Excellent | Moderate–Advanced |
| Herringbone (90°) | 8–12% | Excellent | Moderate |
| Random / crazy paving | 10–20% | Good | Advanced |
Drainage & Falls
Joints & Jointing Sand
Jointing sand locks the paving units together and transfers horizontal forces between them.
| Jointing sand type | Application | Consumption |
|---|---|---|
| Standard kiln-dried sharp sand (0–2 mm) | Traditional, cheapest | ~5–7 kg/m² |
| Polymeric / resin jointing sand | Weed-resistant, sets hard | ~5–8 kg/m² |
| Hydraulic jointing mortar | Heavy-duty / trafficked surfaces | ~6–9 kg/m² |
| Lime mortar pointing | Natural stone, fixed joint | ~8–12 kg/m² |
Step by Step
Measure and mark the area with string lines and pegs. Calculate the required falls (minimum 2 cm/m away from the house). Order paving with at least 10% extra for cutting and waste.
Remember to allow for edge restraints around the full perimeter — these are ordered and priced separately.
Excavate to the correct depth (see frost depth table). Typical total excavation depth: 25–50 cm depending on climate zone and traffic loading.
Place and compact in layers of maximum 100–150 mm — an 80 kg plate compactor cannot compact more than this in a single pass. At least 2 passes per layer.
The sub-base (crushed stone MOT Type 1) is placed on top and compacted to a firm, even surface. Check falls with a spirit level and straight-edge.
Set kerbs or edging on compacted sub-base or concrete haunching. Edge restraints must be immovable and serve as the height reference for the finished surface.
Spread bedding (sharp / grit sand 0/4 mm) and screed to a level surface using screed rails. Target thickness: 30 mm — never exceed 40 mm. Do NOT pre-compact. Do NOT lay geotextile underneath.
Lay paving units from a corner or edge, working inward. Tamp each unit down into the bedding with a rubber mallet. Check levels with a straight-edge as you go.
Block paving: Compact the whole surface with a plate compactor (max 150 kg, fitted with a rubber sole plate). Make one pass lengthways, brush in jointing sand, one pass crossways. Repeat until all joints are filled.
Finish the joints to suit the product: dry kiln-dried sand is simply brushed in (do not wet it — water makes it bridge and wash out), while polymeric sand is brushed in on a completely dry surface and then lightly watered to activate it strictly per the manufacturer's instructions, with no rain due for the stated period. Always follow the jointing product's own method rather than a single universal watering step.
Maintenance
Common Mistakes
Ready to calculate materials?
Use the calculator to work out the number of paving units, quantity of sand and total material cost for your project.
Open paving calculator →Frequently asked questions
What base depth is needed for pavers?
For patios and walkways: 4–6" compacted gravel base + 1" bedding sand. For driveways: 8–12" compacted gravel. Add 1–2" for pavers on top.
What slope should paved surfaces have?
Paved areas need at least ¼" per foot (2% grade) slope away from structures to ensure drainage and prevent water damage to foundations.
Do I need geotextile fabric under pavers?
Geotextile fabric between the subgrade and gravel base prevents mixing and improves drainage, especially in clay or silty soils. Highly recommended for most installations.