Laying Block Paving, 8 – 10 cm Thick

Thickness decides how much weight the paving can carry. A thicker block spreads the load of a wheel more evenly into the base. It also tilts less when a car brakes or turns, and it stays level for longer.

• 4 cm: Paths, garden walkways and patios, meaning foot traffic and perhaps a wheelbarrow or lawnmower
• 6 cm: Yards and the area around the house, with an occasional car passing over a good base
• 8 cm: Garage entrances, driveways and everyday parking for cars
• 10 cm: Areas used by vans or service vehicles, business yards and loading areas

In practice, people often lay 4 cm blocks on a driveway because "the car only stands there now and then". After a few seasons, ruts appear along the wheel tracks and blocks start to come loose. You can combine thinner blocks for a path with thicker ones for the drive. Just plan in advance how the two will meet at the same height.

1. Set out the area with pegs and string, then fix the levels and the fall. Water should run away from the house, usually at a slope of roughly 1 to 2 %.
2. Strip the topsoil and dig out. For a path the dig is usually about 20 to 30 cm deep. For a car area it is roughly 30 to 60 cm, depending on the soil and the load.
3. Compact the bottom of the excavation. On clay or soft ground, lay a geotextile membrane as well.
4. Spread the crushed stone sub-base in layers and compact each layer separately with a plate compactor.
5. Set the kerbs or edge restraints in a concrete bed, with concrete haunching behind them for support.
6. Spread the laying course of grit or sharp sand, usually 3 to 5 cm thick, and screed it level with a straight edge. It is not compacted before the blocks go down.
7. Lay the blocks in the chosen pattern, cut the edges and keep checking the lines.
8. Brush jointing sand into the joints, compact the surface with a plate compactor fitted with a rubber mat, then top up the joints.

For driveways, choose a pattern where the blocks lock into each other well, such as herringbone. Straight rows running in the direction of travel tend to spread apart under wheels.

Why does paving sink after a few years? Almost always because of the base, not the blocks. A thicker block will not make up for a weak base.

For a car area, the build-up usually has these layers:

• Sub-base of coarse crushed stone, often around 25 to 40 cm on driveways and less for paths
• Blinding layer of finer material that closes the surface of the sub-base
• Laying course of grit or sharp sand that the blocks sit on directly

Compact layer by layer, never the full depth in one go. A plate compactor only reaches down so far, so an overly thick layer stays soft at the bottom and settles later. For 8 to 10 cm blocks, a heavier compactor is used than for a path. A well-compacted base does not spring underfoot and shows no marks after the compactor passes over it.

The simplest case is a rectangular area on flat, firm ground where a lorry with stone and a small digger can get in. The job takes more work, and so costs more, with:

• Irregular shapes with curves, steps and lots of cuts
• Thicker blocks, which are heavier and slower to cut and need a more powerful saw
• Clay or waterlogged soil, where you need to dig deeper and deal with drainage
• Poor access, when materials have to be carried by hand or barrow
• Breaking out old concrete or tarmac and taking away the spoil
• Matching exact levels at the garage, a door threshold or an existing path
• Drainage channels and gullies

Before you dig, find out where underground services run, especially gas, electricity and water. Ask the network operators for plans or use a cable and pipe detection service. If you damage a gas pipe while digging, move to a safe distance and call the gas emergency number or 112. A new access from a public road normally needs approval from the road or highway authority. In some places, paving a large area or using a surface that does not let rainwater soak away also needs permission. Check local building regulations with your local building authority and do not assume nothing is needed.

• A sub-base that is too thin, or soil used instead of crushed stone
• Compacting the full depth in one go
• Missing or shallow-set kerbs, so the edges spread apart
• The wrong fall, so water sits on the surface or runs towards the house
• A laying course that is too thick or already compacted, so the blocks will not bed in properly
• Small cut pieces at the edges that break out under a wheel
• Thin blocks on an area used for daily parking

A competent DIYer can manage a small path or patio with thinner blocks. You can hire a plate compactor and a masonry saw. For a driveway of 8 to 10 cm blocks, it makes sense to bring in a contractor, because the digging, compacting thick layers and getting precise levels all take machinery and experience.

1. Check where underground services run and set out the area with string.
2. Strip the topsoil and dig to the required depth, with a fall away from the house.
3. Compact the bottom of the excavation.
4. Spread the crushed stone in layers and compact each one with the plate compactor.
5. Set the kerbs in concrete and let it harden.
6. Spread the laying course and screed it level along guide rails without walking on it.
7. Lay the blocks working from a fixed edge, checking lines and level as you go.
8. Cut the edges with a water-cooled saw, wearing a dust mask and safety glasses.
9. Brush sand into the joints, compact with a rubber mat on the plate and top up the joints.

• No dips or waves are visible when a straight edge is run across it
• Water runs off after rain and does not pool anywhere
• The fall runs away from the house, garage and steps
• Kerbs are firm, straight and in line
• Blocks do not move or rock when you step on them
• Joints are full and even, with no large gaps
• Edge cuts are not too small or broken
• Transitions to the garage, paths and thresholds are flush with no step
• There are no cracks or chipped edges on the surface