Installing paving slabs of any kind requires planning, the correct materials and understanding the best practices of paving installation. The below is a quick guide to help anyone looking to lay paving slabs a good starting point. Note: This is informative only and you should seek expert advice from qualified landscapers.
Carry out a simple risk assessment and method statement. If excavating, dig small test holes or use cable-avoidance tools and visually check for services.
Finished level: keep at least 150 mm below the DPC. For patios next to a house this equates to excavating to roughly 300 mm below the DPC to allow for the build-up beneath the finished surface.
Falls: set 1 : 60 (~17 mm/m) to suitable drainage points.
Utilities: identify and mark services before digging.
Patios/paths: dig to suit 100 mm Type 1 + 30–40 mm mortar + slab thickness (~150 mm total below finished level).
Driveways / wet ground: allow 200 mm for the sub-base.
Working room: over-cut the footprint by 150–200 mm for tidy edges. Compact the sub-grade with static or vibratory equipment.
Construction components: sub-grade → sub-base → bedding course → paving course.
Geotextile: roll out non-woven membrane to prevent sub-base migrating into the sub-grade (reduces settlement).
Flexible sub-base: Type 1 at 100–150 mm, compacted in ≤ 70 mm lifts (rule-of-thumb two layers; ~5 plate-compactor passes per lift). On poor soils, use the membrane beneath the Type 1.
Rigid sub-base option: lean-mix concrete ~100 mm with DPM at this stage. Set edge restraints before bedding.
Full wet bed (best on Type 1 sub-base): standard sand/cement mortar prepared to a wet consistency.
| Material | Mix (PSD standard) | Compacted thickness | Notes |
|---|---|---|---|
| Porcelain | 4 : 1 sharp sand / crushed-rock fines : OPC | 30–40 mm | Flat, even bed; no trowel furrows; workable ≤ 2 hours |
| Natural stone | 4 : 1 (avoid builders’ sand; use 0–6 mm crushed rock) | 30–40 mm | Full contact — no spot-/ring-bedding (avoids reflective staining) |
Illustration of full-bed mortar on a Type 1 sub-base with geotextile.
Porcelain: apply 2–3 mm bonding slurry to the back immediately before laying. Tile spacers help keep joints uniform.
Natural stone: use SBR primer / SBR-slurry for adhesion and moisture control.
Place slabs on the full bed and tap home with a rubber mallet.
Joint width: Porcelain 5 mm (use spacers); Natural stone 10–15 mm.
Check levels frequently; BS lipping < 2 mm.
Cutting: Porcelain — continuous-rim diamond (wet-cut). Natural stone — standard masonry blade.
Start at the centre for circles and centre pieces. If part of a larger patio, set circles first.
Open all packs before starting so colours blend naturally across the area. All products may have slight colour variations. For porcelain, ensure all goods are the same batch before laying.
Natural stone: if using multiple packs, mix them together to achieve an even blend.
Clean as you go: wipe fresh mortar with clean water; never use acid cleaners.
Curing: foot traffic 24 h; heavy loads 48 h.
Only when the bed is firm; joint depth ≥ 20 mm.
Sub-base match: On permeable/flexible builds, use a porous polymeric jointing compound. On rigid builds, a non-porous option such as Flowpoint is typical and best left to experienced installers. Keep paving clean and free of slurry; use plenty of clean water and remove surplus resin on completion.
| Stage | Porcelain | Natural stone |
|---|---|---|
| Primer | Bonding slurry 2–3 mm (back) | SBR slurry / primer |
| Joints | Exactly 5 mm (with spacers) | 10–15 mm; avoid cross-joints on random layouts |
| Cutting | Continuous-rim diamond, wet-cut | Standard masonry blade |
| Sealing | Optional (non-porous) | Consider after 3–6 months to resist stains |
Thin-bed adhesive — best practice on concrete. This substitutes sand-cement for an outdoor-rated polymer-modified cement. Common in hotter climates outdoors but not a standard practice in the U.K.
