Patios & paving

1. 1

   Set out and check the levels

   Mark the patio, check it is square across the diagonals, and set string lines with a fall of 1:60 to 1:80 away from the house, keeping the finished surface 150 mm below the damp proof course.

2. 2

   Excavate

   Strip turf and topsoil down to firm subgrade, allowing for the sub-base, the mortar bed and the slab thickness plus the fall.

3. 3

   Lay the sub-base

   Roll a geotextile over clay, then spread and compact MOT Type 1 in 75 mm layers, 100 mm total on good ground and 150 mm on clay.

4. 4

   Mix and lay the bedding

   Lay a full wet mortar bed of about 4:1 sharp sand to cement, 30 to 40 mm thick, priming the back of porcelain and dense stone with a slurry.

5. 5

   Set the key slab

   Bed the first corner slab to the string lines and tap it down with a rubber mallet until it is solid and running to the fall.

6. 6

   Lay out from the key slab

   Work outward keeping the joint width consistent for the material, checking level and fall every few slabs, and cutting the perimeter last.

7. 7

   Point the joints

   Once the bed has set, fill the joints with a brush-in compound or a mortar to suit the joint width, then clean the surface before it cures.

Paving in a rear garden is generally permitted development. The rules tighten in front gardens, near the highway, and where surface water has nowhere to go.

• Front-garden surfaces over 5 m² in impermeable materials need planning permission unless run-off drains to a permeable area on your own land (lawn, border, gravel, soakaway). ^[1][2]
• Permeable surfaces (gravel, permeable block paving, porous resin) of any size are permitted development in front gardens, provided sub-base allows infiltration. ^[2]
• Finished paving must sit at least 150 mm below the damp-proof course (DPC) of the house wall, two brick courses, roughly. ^[3]
• Never bury air bricks / underfloor vents. Where paving rises to the wall, keep the opening clear or fit a periscope (telescopic) underfloor vent, blocked vents cause joist rot, condensation and ground-gas build-up. ^[3][5]
• For flush / level access (bifolds, sliders, wheelchairs) the threshold step is capped at 15 mm (chamfered) under Part M. Resolve the DPC conflict with a threshold / ACO slot drain at the door, with cavity-tray and weep detailing. Mandatory for new dwellings and extensions. ^[6]
• Paving in a listed building's curtilage, a conservation area, or an Article 4 area may need permission even when it would otherwise be permitted development. ^[2]
• BS 7533 is the British Standard family for pavements constructed of clay, natural stone or concrete paving units. It's the document specifiers reach for. ^[4]

Numbers that come from real jobs, not marketing copy. Adjust for ground conditions and product datasheets.

• Before any excavation, even shallow lifts of an existing patio, do a CAT & Genny sweep to locate buried services (HSE HSG47). Plastic gas and water mains do not show on a CAT alone; the Genny is what finds them. Full method in the Safety, PPE & site rules guide.
• Minimum fall away from the house is 1:80 (12.5 mm per metre). 1:60 sheds water faster on slabs that hold puddles.
• On a steep site (>1:20), step the patio with riser courses rather than running one long fall, water sheets off rather than skating across joints.
• If run-off goes to a soakaway, oversize it 20 % for porcelain and other impermeable slabs, they shed water faster than block paving.
• Sub-base of MOT Type 1, compacted in 75 mm layers: 100 mm for foot traffic, 150 mm on clay or for occasional vehicle overrun.
• Natural stone is variable thickness, always lay on a full mortar bed, 30–40 mm thick. Never spot-bed. Spot-bedding is the #1 cause of cracked sandstone.
• Porcelain is rectified (factory-cut edges) and demands a primer slurry on the back of every slab before bedding, plus 3–5 mm joints.
• Cure the bed and joints for 24 hours before walking, 72 hours before furniture or pots.
• Cut allowance: rectangular patio with simple borders ≈ 5 %. Curves, circle features, or lots of obstacles ≈ 10–12 %.
• 45° herringbone in block or rectangular slabs typically wastes 8–12 % to cuts at the perimeter, order accordingly.
• Jointing compound: brush-in resin (~25 kg covers ~6–8 m² at 10 mm joints) or kiln-dried sand for block paving (~4–6 kg/m²).

• Indian sandstone, limestone, granite, slate → full mortar bed + brush-in jointing or sand-cement pointing. Joints 8–15 mm.
• Porcelain → SBR slurry primer + full mortar bed + 3–5 mm brush-in jointing. Skipping the primer is the #1 reason porcelain debonds in winter.
• Concrete slabs (smooth or riven) → mortar bed; lighter-weight slabs can be screed-laid on sharp sand.
• Block paving → 30–40 mm sharp sand bed on Type 1 sub-base, kiln-dried jointing sand, mechanical edge restraint.
• Clay pavers → 30–40 mm sharp sand screed bed, joints 2–5 mm, kiln-dried sand swept in after vibration. Kiln-fired colour is permanent, no fade.
• Granite setts → full mortar bed (30–50 mm) with 10–20 mm pointed mortar joints, never butt-jointed or sand-filled. Heaviest UK paving option for traffic.
• Grass-grid cellular pavers → on 50 mm grit/sharp-sand bed over 100–150 mm open-graded 4/20 mm clean (no fines) sub-base; cells filled with topsoil + grass seed or pea gravel. SuDS-compliant for front drives.
• Pattern-imprinted concrete (PIC) → single monolithic C28/35 pour with A193 mesh; colour hardener broadcast wet, release agent dusted, stamp mats applied, acrylic sealer after 24–48 h. Reseal every 3–5 years.
• Limestone, never de-ice with rock salt; calcium carbonate reacts with brine and acid rain and the surface pits. Seal with a breathable impregnator on installation.
• Slate, riven slate is glass-slippery in shade or N-facing aspects once foot-polished; specify a grit-blasted or textured finish on main approaches, or keep it as a feature only.
• Granite setts, shock-load from cars cycles the mortar joints; expect to re-point every 5–10 years under traffic. Use polymer-modified pointing from day one.
• PIC, micro-cracks in the stamped surface are normal in any C28/35 slab; the re-seal hides them visually. Skipping the re-seal is the #1 reason PIC drives look tired by year 5.
• Grass-grid, grass cover fails under daily car use (compaction + shade). Sell honestly as overflow / occasional / fire-engine access only; for daily parking, fill the cells with pea gravel from day one.

• Spot-bedding slabs on five dabs of mortar. It is the single most common cause of rocking, cracked and stained paving, and BS 7533 requires a full bed under the whole slab.
• Laying the patio level to look neat. Without a fall of 1:60 to 1:80 the surface ponds, and in a UK winter that water freezes and lifts the joints.
• Bringing paving up above the damp proof course. Keep the finished surface at least 150 mm below the DPC and never bridge an air brick.
• Skimping the sub-base on clay. 100 mm of MOT Type 1 is a minimum on good ground, 150 mm on clay, compacted in 75 mm layers rather than in one deep pass.
• Leaving the perimeter unrestrained. Slabs without a haunched edge creep outward and the joints open within a season.
• Brushing dry sand into wide riven joints. Sand only suits tight block joints; riven stone needs a mortar or a brush-in jointing compound rated for the joint width.
• Sealing damp or new stone. Trapped moisture blooms white under the sealer and the only fix is stripping it back.

Supply and install ranges for 2026. Access, ground conditions and region move these more than the material choice does.

• Concrete flags or riven concrete: roughly £70 to £110 per m2 installed, the cheapest genuinely durable option.
• Indian sandstone: roughly £90 to £140 per m2 installed, with calibrated stone at the lower end of the labour cost.
• Porcelain: roughly £120 to £180 per m2 installed, because it needs a slurry primer on the slab back and diamond cutting.
• Granite and high-end natural stone: roughly £150 to £220 per m2 installed.
• Groundworks and disposal typically run at 25 to 35 percent of the total. A 30 m2 patio dug 250 mm deep is about 7.5 m3, roughly 12 tonnes to take away.
• Extras that are always forgotten: a channel drain at £60 to £120 per metre installed, and step or edging detail at £80 to £150 per metre.