7 Step Cobble Setts Laying Routine with Brett Granite Setts Over a 6-Metre Drive

Set the falls before the first sett goes down

Many driveway failures begin with a dead-flat surface, since 2,160 granite setts across a 6-metre run need a planned route for water. A minimum fall of 1 in 80 gives 75mm of drop from house to road over that distance. Where the property sits below the highway, an ACO threshold drain or a linear channel across the entrance has to be in position before the drive is pegged out.

Brett Tradition setts are 100mm x 100mm x 50mm riven granite. The stone is dense and has near zero porosity, so rain runs across the face. That behaviour controls every finished level on the job.

String lines are pegged at finished level with a laser or a long spirit level on a straightedge. The fall should run consistently toward the outfall. Where the drive meets a garage threshold, the finished setts need to sit 150mm below the damp proof course.

A cross-fall of around 1 in 40 toward one edge clears water faster than a single fall running down the length of the drive. It also reduces ponding in the wheel tracks, where standing water slowly damages joints during freeze-thaw cycles.

Excavate for the full build-up

For a domestic drive carrying a family car, dig deep enough for 150mm of compacted MOT Type 1 sub-base, 30mm to 40mm of bedding, and the 50mm sett. That puts the excavation at roughly 230mm below finished level, with extra depth allowed where soft clay needs a geotextile separator such as Terram 1000 to stop stone migrating into mud.

Compact the sub-base and restrain the edges

Lay MOT Type 1 in two 75mm layers so compaction reaches the full depth. Spread the first layer, run a plate compactor or Wacker over it in overlapping passes, then repeat with the second layer. Before the bedding course goes on, blind the top with a thin scatter of grit sand to fill surface voids. The finished sub-base should be tight enough that a heel leaves no mark.

Set the perimeter before the field of setts is laid. Granite blocks placed against an unsupported edge will creep under load, the outside joints open, and the paved field starts to loosen from the perimeter. Haunch the edge setts with wet C20 concrete, forming a triangular fillet that rises to roughly two thirds of the sett height on the back face.

Oak railway sleeper edging can give a softer transition into a planted border. The sleeper is bedded on concrete and fixed with galvanised reinforcing bar driven through pre-drilled holes into the ground. It takes the lateral thrust and sits more warmly against gravel or lawn.

Use a semi-dry mortar bed

A driveway taking vehicle loads needs a semi-dry mortar bed. Loose grit sand can be pumped from joints by the point loads of car tyres over a season, which leaves the wearing course moving under traffic.

The standard bedding mix is 6:1 sharp sand to cement. Mix it until a squeezed handful holds together and crumbles when prodded. A wet mix smears and refuses to screed cleanly; an over-dry mix fails to gain strength properly.

Work in bays of about a square metre ahead of your knees. Semi-dry mortar starts curing as soon as cement meets damp sand, so setts need to be placed while the bed is still workable. Screed the mortar to a consistent 35mm, leaving each block a few millimetres proud before final consolidation.

A 100mm sett pressed into a 30mm finished bed gives a robust 130mm of bound material under the wearing surface. Keeping that depth consistent matters more than chasing the small variations in each riven face.

Prime the underside of each sett with a slurry of neat cement and water before bedding. This wet bond coat chemically locks the granite to the mortar bed and gives the corners far better hold under vehicle loads. Across roughly 2,160 units the priming is slow, yet it is part of the specification for a drive that has to carry weight for years.

Run the herringbone across the wheel paths

A 90-degree herringbone pattern interlocks the setts so wheel loads spread sideways into neighbouring blocks. Stretcher bond, the simple running-brick pattern, looks cleaner and concentrates stress along the long joints, so it is better suited to foot-traffic paths. For a 6-metre approach, the herringbone should run at 45 degrees to the direction of travel, preventing a continuous joint from lining up with a tyre track.

Work from the laid granite and keep clear of the screeded bed. A scaffold board spreads body weight across the blocks already in place. Set each sett tight to its neighbours, tap it down with a rubber mallet to the string line, and check the level every square metre with a straightedge laid across the surface.

The working rhythm is bed, slurry, place, tap, check. Keep joints between 3mm and 5mm, using the natural rivenness of the granite as the guide. Brett setts vary slightly in face dimension by design, and a rigid spacer fights the material.

Cut the perimeter after the field is complete

Lay full setts across the field first and leave the cuts until last. Mark the edge pieces in situ against the haunched perimeter, then cut them on a bench saw with a diamond blade and water suppression. Dry-cutting granite throws silica dust that a dust mask handles poorly over a full day. Each cut sett should be at least a third of a full unit, since smaller pieces work loose even when well bedded.

Joint, protect and cure

Granite setts laid on a mortar bed can be finished with a dry mortar joint or a brushed-in resin compound. For the dry option, use a 4:1 kiln-dried sand and cement mix. Brush it into the joints bone dry, then mist it lightly with a fine spray. It sets hard and avoids the staining associated with wet slurry pointing.

Fill the joints completely to depth. A half-filled joint leaves a void where water can sit and freeze, which breaks down the edge support between blocks.

Resin jointing compounds, including the slurry-applied polymer type sold by Romex and similar brands, cost more and need a genuinely dry surface to cure. They flex slightly with thermal movement and resist the weed colonisation that plagues sand joints. On a riven granite face, resin can be awkward to clean before it skins, so use a sponge float and clean water as soon as each joint is filled.

A plate compactor running directly on the granite chips the arrises and cracks the bedding bond. Once jointed, keep vehicles off the driveway for at least seven days in mild weather. If temperatures drop below 5 degrees, the cement cure slows and the waiting time lengthens.

During hot dry spells, mist the surface so the mortar does not flash off and craze. Light foot traffic is usually safe after a couple of days, while the first car should stay off until the bed has hardened throughout.

Drainage and permission

Quotes for this kind of work often leave out the drainage outfall. A 6-metre impermeable granite drive sheds a real volume of rainwater. Since 2008, a domestic front garden in England covering more than five square metres and draining onto the public highway has needed either a permeable construction or a soakaway under the planning rules that followed the surface water flooding reviews.

Setts on a solid mortar bed are not permeable. The system therefore has to include a gravel-filled soakaway trench or a channel drain that takes the run-off somewhere legal, and that buried route determines whether the finished drive is compliant.

The brochure image usually stops at the last brushed joint, while the route taken by the rainwater stays out of sight.