Surcharge for Paving Small Cobbles (up to 10x10 cm)

With large block paving, one piece covers a fair amount of ground. Small setts are different: a single square metre takes dozens or even hundreds of them. Each one has to be picked up, placed, levelled and checked. The work is therefore much slower, even when the area does not look big at first glance.

The second reason is accuracy. A larger format hides a small deviation, but small cobbles show it. If a row drifts slightly at the start, the error grows over a few metres and the pattern bends. A good paver checks level, joints and the direction of the rows as the work goes along, not just at the end.

Natural stone adds one more factor: the setts are not all the same height or shape. Each one has to be tapped down into the bedding until its top sits flush with its neighbours. With small paving, hand work is the rule.

The process is similar to normal paving. The difference lies mainly in the pace and in the amount of checking:

• Dig out the soil, level the ground and compact it
• Spread and compact a sub-base of gravel or crushed stone, with a thickness that suits the load on the surface
• Set the edge restraints or kerbs, which hold the edges and define the line of the area
• Prepare a bedding layer of fine grit or sharp sand, or a cement-based mix on a rigid base
• Lay the setts by hand along a string line and to the pattern, tapping each one down with a rubber mallet or small hammer
• Fill the joints with sand, fine grit or a jointing compound
• Vibrate or compact the surface, top up the joints and clean the area

For footpaths the sub-base is usually somewhere around 15 to 30 cm thick, with roughly 3 to 5 cm of bedding. The exact build-up depends on the ground underneath and on whether only people will walk on it or cars will drive over it as well. If the setts go into a mortar or concrete bed, follow the manufacturer's instructions and wait out the curing time before you put any load on the surface.

Are you building a new driveway next to the house or a new vehicle access onto a public road? Then check with your local building authority or council first. Local rules differ, and some places require permission for new vehicle access or set conditions on drainage from paved front gardens. In a block of flats, changes to a shared courtyard go through the building management or owners' association.

The surcharge is not the same on every job. These things make the work take longer, and so cost more:

• Irregular natural stone instead of uniform concrete blocks
• A complex pattern, for example arcs, fans, fish-scale layouts or mixed colours
• Small, broken-up areas with corners, steps, manhole covers and a lot of cutting
• A poor or unfinished base that has to be put right first
• Difficult access, where materials cannot be delivered right next to the area

Simple straight rows, a larger continuous area, a well-prepared base and easy access all make the job much quicker.

Small cobbles follow curves, gentle slopes and irregular shapes well. That is why they are used in historic town centres, in the renovation of older houses and anywhere a surface should look fine-grained and handcrafted. On a good base the load spreads across many pieces, and the surface lasts a long time.

Bear in mind that there are a lot of joints. If they are not filled properly, rain washes them out, dirt settles in them and weeds take hold. Small paving also shows every flaw in level straight away. And as with most paving, the cause of later problems is usually an underestimated base, not the setts themselves.

• A poorly compacted base, which leads to dips and ruts over time
• No fall, so water stands on the surface or soaks towards the house (a fall of roughly 2% away from the building is usual)
• No pattern planned in advance, leaving thin slivers at the edges
• Uneven joints, which spoil both the look and the stability
• Poorly filled joints, so the setts loosen and start to move
• Missing or badly set edge restraints, so the paving spreads at the edges

You can lay a short garden path or a bed edging yourself if you have patience. For a driveway or a large area it makes more sense to call a professional, because the base has to carry the weight of a car.

1. Mark out the area with pegs and string, and set the height and fall.
2. Dig out the soil to the required depth and compact the bottom.
3. Spread gravel or crushed stone in layers and compact each layer.
4. Bed the edge restraints in concrete and let them harden.
5. Spread a bedding layer of fine grit and screed it level with a straight board.
6. Lay the setts from a fixed edge along the string line and tap each one down with a rubber mallet.
7. Check the level after every row with a straight edge and spirit level.
8. Brush sand or fine grit into the joints, sweep the surface and compact it.
9. Check the joints again after a few days and top them up.

• The surface is even, with no obvious dips or raised setts under a long straight edge
• No sett moves or clinks when you walk on it
• Joints are even and completely filled
• Rows and pattern are straight, and curves flow smoothly
• Rainwater drains away and does not stand in puddles
• Edge restraints are firm and the paving sits tight against them
• The surroundings are clean and leftover material has been taken away