Patio Materials List UK: Slabs, MOT Type 1 and Sand
A 4 × 3 m patio in 600 × 600 mm slabs needs 36 slabs (with 10% for cuts), 2.8 tonnes of MOT Type 1 for the sub-base and 0.6 tonnes of sharp sand for the bed. This is the full shopping list, with how each number was worked out and a chart for other sizes.
The materials list
| What to buy | How much | How we worked it out |
|---|---|---|
| Paving slabs, 600 × 600 mm | 36 slabs | Paving calculator: 12 m² with 10 mm joints, plus 10% for cuts and breakage |
| MOT Type 1 sub-base | 2.8 tonnes (about 4 bulk bags) | 100 mm compacted, at 2.2 tonnes per m³, with 5% extra. Or work it out in the gravel calculator |
| Sharp sand for the bed | 0.6 tonnes (1 bulk bag) | A 30 mm bed, with 5% extra. Use a screed board to level it, and do not walk on it before the slabs go down |
| Or: mortar bed (instead of sand) | 0.9 tonnes of sharp sand and 6 bags of 25 kg cement | Paving calculator, mortar bed: a 40 mm bed at 6 parts sand to 1 of cement |
| Jointing compound | Check the coverage on the pack | The amount depends on the slab thickness and joint width, so use the maker's coverage figure |
| Edge restraint | 14 m of perimeter | 2 × (4 + 3). Only needed on the sides that are not against a wall, where slabs can creep outwards |
| Tools to hire or buy | 1 set | A plate compactor (hire), a rubber mallet, a spirit level, a string line, a wheelbarrow, and a cutter for the edge slabs |
Materials for other patio sizes
600 × 600 mm slabs, 10 mm joints, 100 mm sub-base and a 30 mm sand bed, with the same allowances:
| Patio size | Area | Slabs | MOT Type 1 | Sharp sand |
|---|---|---|---|---|
| 3 × 3 m | 9 m² | 27 | 2.1 tonnes | 0.5 tonnes |
| 4 × 3 m | 12 m² | 36 | 2.8 tonnes | 0.6 tonnes |
| 4 × 4 m | 16 m² | 48 | 3.7 tonnes | 0.8 tonnes |
| 5 × 4 m | 20 m² | 60 | 4.6 tonnes | 1.0 tonnes |
| 6 × 4 m | 24 m² | 71 | 5.5 tonnes | 1.2 tonnes |
| 6 × 5 m | 30 m² | 89 | 6.9 tonnes | 1.5 tonnes |
How the slab size changes the count
For the same 4 × 3 m patio, with 10 mm joints and 10% for cuts:
| Slab size | Slabs to buy |
|---|---|
| 600 × 600 mm | 36 |
| 450 × 450 mm | 63 |
| 400 × 400 mm | 79 |
| 300 × 300 mm | 138 |
| 600 × 300 mm | 70 |
| 900 × 600 mm | 24 |
Larger slabs are quicker to lay but heavy, and a big slab is harder to bed level on a small patio. Smaller slabs are easier to handle and to cut around curves.
Before you order
- Check for buried services before you dig. The free LSBUD (LinesearchbeforeUdig) service shows the gas, water, electricity and telecoms assets near your address.
- Check the levels. Keep the finished surface at least 150 mm below the damp-proof course of the house, and lay it to a fall of about 1 in 80 (about 12 mm per metre) away from the building, so that water drains away from the walls.
- Check the rules. A patio at ground level rarely needs planning permission, but a raised one, one in a conservation area or around a listed building can. In England, paving more than 5 m² of a front garden with an impermeable surface needs permeable materials or drainage to a lawn or border.
- Order the slabs from one batch, and a couple extra for later repairs. Colours and sizes vary between production runs.
How the job goes
- Mark out the patio, and dig out about 150 to 200 mm (the slab, the bed and the sub-base). Compact the soil.
- Lay and compact the MOT Type 1 in layers of no more than about 100 mm, with a plate compactor.
- Spread and screed the sand (or lay the mortar bed), to the right level and fall.
- Lay the slabs from a straight edge or a corner, tapping each down with a rubber mallet, and check the level as you go.
- Leave the joints open, cut the edge slabs to fit, and fill the joints once the slabs are firmly down.
Mistakes that cost people money
- A thin or poorly compacted sub-base. The patio will sink and rock, and you will have to lift it and start again.
- Wrong levels against the house, which lets water run towards the wall instead of away from it.
- Not buying enough slabs from the same batch. A later pack may not match.
- Using a hand rammer where a plate compactor was needed. The base will not be firm enough.
Frequently asked questions
How many paving slabs do I need for a 4m x 3m patio?
36 slabs of 600 × 600 mm with 10 mm joints and 10% for cuts. Without any allowance for cuts it is 33.
How much MOT Type 1 do I need for a patio?
About 0.22 tonnes per m² for a 100 mm compacted layer, so a 12 m² patio needs 2.8 tonnes with 5% extra. That is about 4 bulk bags of 0.8 tonnes.
Should I lay slabs on sand or mortar?
A sharp sand bed is fine for a garden patio, and it is quicker and easier to adjust. Use a full mortar bed on a drive or anywhere a vehicle will go, and for natural stone, which is heavier and needs a firmer bed.
How deep should the sub-base be for a patio?
A compacted layer of 100 mm of MOT Type 1 suits most patios and paths. For a driveway use 150 mm or more, and on soft clay ground go deeper.
More guides
Tools & materials for this project
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and check the Building Regulations and any planning rules for anything structural or close to a boundary.