Patio Planner – Every Material for Building a Patio
One form, the whole job. Measure the patio, choose your slab, and we'll work out the sub-base, bedding mortar, slabs, jointing and edging — plus the total cost.
Build a Patio planner
What will use the patio?
100mm of compacted MOT Type 1 over a membrane, with a 40mm full mortar bed. That's the standard build-up for a garden patio.
Measure rectangles length by width. Split an L-shape into two rectangles, or measure a circle straight across its widest point.
Measure your patio
15 m²
Odd-shaped garden? Split it into rectangles, triangles and circles — we add them up for you.
You need
44slabs (15 m²)
Full build-up: 100mm sub-base + 40mm mortar bed + slabs
- MOT Type 1
- 3.15 t (4 bags)
- Sharp sand
- 0.8 t (1 bags)
- Cement
- 6 × 25kg bags
- Jointing compound
- 3 × 20kg tubs
- Spoil to remove
- 2.7 m³
- Perimeter
- 16 m
How we worked this out
Your patio shopping list
44 × 600 × 600mm paving slabs
Includes 5% for cuts and breakages.
£528
4 × 850kg bulk bags of MOT Type 1
3.15 tonnes compacted to 100mm.
£280
1 × 850kg bulk bags of sharp sand
For a 40mm full mortar bed at 5:1.
£60.00
6 × 25kg bags of cement
£39.00
3 × 20kg tubs of brush-in jointing compound
Apply to damp joints on a dry day — read the tub, they vary.
£96.00
2 × rolls of weed membrane (1m × 10m)
£50.00
27 × 600mm edging units
Only needed on open sides — reduce the count if the patio butts walls.
£108
Patio build-up at a glance
| Layer | Foot traffic | Vehicle crossing | Material |
|---|---|---|---|
| Excavation | 200mm | 250mm | Spoil to a skip |
| Membrane | 1 layer | 1 layer | Woven weed membrane |
| Sub-base | 100mm | 150mm | MOT Type 1 @ 2.1 t/m³ |
| Bedding | 40mm | 50mm | Sharp sand + cement, 5:1 |
| Slabs | 20–40mm | 40mm+ | Riven, porcelain or concrete |
| Joints | 10mm | 10mm | Brush-in compound |
How this planner works
A patio is four layers, and each one is worked out from the same area figure. We take the total area from your measurements, then:
- Slabs: area plus 5% waste, divided by the area of one slab, rounded up.
- Sub-base: area × depth × 2.1 tonnes per m³ of MOT Type 1, then divided into 850kg bulk bags.
- Bedding: area × 40mm gives the mortar volume, split 5:1 by volume into sharp sand and cement, with sand converted at 1.6 tonnes per m³.
- Jointing: area divided by the coverage of a 20kg tub, which is about 6m² at a 10mm joint on 600mm slabs.
- Edging and membrane: from the perimeter and the area respectively.
We also show the spoil volume, because the dug-out material has to go somewhere and a skip is usually the biggest single cost people forget.
Worked example: a 4m × 3m patio
A 4m × 3m patio is 12m². With 600 × 600mm slabs (0.36m² each) and 5% waste you need 35 slabs.
The sub-base at 100mm is 12 × 0.1 × 2.1 = 2.52 tonnes, which is three 850kg bulk bags. The 40mm mortar bed is 0.48m³: about 0.4m³ of sharp sand (0.64 tonnes, one bulk bag) and 0.08m³ of cement, which is around five 25kg bags. Jointing takes two 20kg tubs, and you'll want two rolls of membrane.
Materials come to roughly £700–£900 depending on the slab, plus a skip at around £250 for the 3m³ of spoil and about £60 a day for a plate compactor. Add a couple of days' labour if you're not doing it yourself.
Tips from the trade counter
- The base is the job. Compact the Type 1 in two 50mm layers with a plate compactor, not one 100mm layer. A properly whacked base is why some patios last thirty years and others rock after one winter.
- Set a fall before you start. 1 in 80 away from the house. String lines and a spirit level with a packer taped to one end make this easy.
- Stay 150mm below the DPC. Paving above the damp-proof course bridges it and can cause damp inside the house.
- Prime the back of porcelain slabs. Slurry primer is essential for porcelain — without it, slabs release from the mortar within a year.
- Order the slabs first. Check the pack for shade variation and lay from several packs at once so the colour blends naturally.
- Don't joint in the wet or in frost. Most brush-in compounds need dry, mild conditions and will stain or fail otherwise.
UK rules for patios
A patio laid at ground level in a rear garden is normally permitted development and needs no planning permission. A raised patio or platform more than 300mm above ground level often does, and so does paving in some conservation areas, on listed buildings, or where a planning condition removes permitted development rights.
If the patio increases the amount of hard surface draining towards a public sewer or the highway, plan for run-off to soak into a border or lawn. And keep the finished level at least 150mm below the damp-proof course. Always confirm with your local council before starting — rules differ across England, Wales, Scotland and Northern Ireland.
Frequently asked questions
What materials do I need to lay a patio?
Weed membrane, MOT Type 1 sub-base, sharp sand and cement for the bedding mortar, the slabs themselves, jointing compound, and edging or haunching for any open sides.
How deep should I dig for a patio?
Around 200mm for a foot-traffic patio: 100mm of compacted sub-base, 40mm of bedding mortar and the slab thickness, finishing at least 150mm below the damp-proof course.
How much sub-base do I need for a patio?
100mm of compacted MOT Type 1 for foot traffic, or 150mm if a vehicle will ever cross it. MOT Type 1 weighs about 2.1 tonnes per m³, so 12m² at 100mm is 2.5 tonnes.
Should slabs be laid on a full mortar bed or on dabs?
Always a full bed. Spot-bedding on five blobs leaves voids that crack slabs, hold water and cause frost damage. A 40mm full bed at about 5:1 sharp sand to cement is the standard.
What fall should a patio have?
About 1 in 80 — roughly 12mm per metre — running away from the house so rainwater drains off rather than sitting against the wall.
How much jointing compound do I need?
A 20kg tub of brush-in compound typically covers 5–8m² with 10mm joints on 600 × 600mm slabs. Narrower joints or larger slabs go further.
Do I need planning permission for a patio?
Usually not for a patio at ground level in a rear garden. Raised decking or a raised patio over 300mm high, and paving in some conservation areas or listed properties, can need permission — check with your local council.
How long does a patio take to lay?
For a competent DIYer, a 12m² patio is typically a full weekend for digging out and the sub-base, and a second weekend for laying and jointing. Don't rush the base — it's 80% of the job.