Patio Material Estimator
Complete patio shopping list — MOT Type 1 sub-base, mortar bed, paving slabs and jointing compound in one estimate. All four layers calculated together. 2026 UK pricing.
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Construction Guide
How to Build a Patio
Layer 1 — MOT Type 1 sub-base
Excavate to the required depth (sub-base + mortar bed + slab thickness + 20–30mm below finished level). Lay MOT Type 1 in layers of no more than 100mm and compact each layer with a wacker plate. A poorly compacted sub-base is the most common cause of sunken, rocking patios. Allow 20% extra material to account for compaction.
Layer 2 — Full mortar bed
Mix sharp sand and cement in a 6:1 ratio (6 parts sharp sand, 1 part cement) to a semi-dry consistency — it should hold its shape when squeezed but crumble if dropped. Spread at 40mm depth across the full area and screed level. Lay slabs immediately and tap down firmly with a rubber mallet. Never use building sand — it is too soft and will produce a weak bed.
Cover the full underside of every slab — no voids. Voids hold water and cause frost damage. Check levels constantly with a spirit level and allow a 1:80 fall away from the house for drainage.
Layer 4 — Jointing
Brush-in compound: Allow the mortar bed to cure for at least 24 hours. Brush dry jointing compound across the surface and into gaps. Add water as directed — usually a light spray — and allow to set. Fast, clean and resilient. Excess wipes off easily. Suitable for most domestic patios.
Traditional mortar pointing: Mix 3:1 sharp sand and cement to a stiff but workable consistency. Press firmly into joints, tool to a neat finish and clean excess promptly. Do not point in frost or if rain is forecast within 24 hours. Do not use on natural stone without a suitable plasticiser — plain cement mortar will stain.
FAQ
Common Questions
Total excavation depth = sub-base depth + mortar bed depth + slab thickness, then set down 20–30mm below finished paving level to allow for falls. For a standard 100mm sub-base + 40mm bed + 50mm slab: 190mm excavation minimum. Add 20–30mm to this to ensure the finished surface sits at the right level relative to doors and DPC.
Generally no — patios at ground level are Permitted Development. However, if the paving covers more than 5m² and is not permeable (allowing water to drain through), you may need to ensure runoff drains to a lawn or border rather than directly to the road. Permeable block paving or gravel avoids this requirement entirely. Listed buildings and Conservation Areas have additional restrictions.
The finished paving surface must be at least 150mm below the damp-proof course (DPC) in the house wall. If you raise the ground level too close to the DPC, moisture can bridge it and cause damp inside. Mark the DPC level on the house wall before setting your finished paving level, and ensure you have at least 150mm clearance below it.
Sharp sand (grit sand) has angular particles that lock together and produce a strong, hard bed when mixed with cement. Building sand has rounded particles and produces a soft, weak mix that will fail under load and freeze-thaw cycles. Always specify sharp washed sand (BS EN 12620) for mortar beds and jointing. Building sand is only suitable for bricklaying mortar and render — not paving.