What is Type 1 sub-base (MOT)?

Type 1 sub-base, commonly known as MOT Type 1 or crusher run, is a crushed aggregate mix graded from 40mm down to dust. It compacts extremely well and provides a stable, load-bearing foundation for driveways, patios and paths. It conforms to the Highways Agency Specification for Highway Works (SHW) Clause 803. This Type 1 MOT calculator works out quantities in tonnes and bulk bags.

How deep should Type 1 sub-base be for a driveway?

For a domestic driveway taking cars, a minimum of 150mm (6 inches) of compacted Type 1 sub-base is recommended. For heavier vehicles or commercial use, increase to 200-300mm. For pedestrian paths and patios, 100mm is usually sufficient. After laying the sub-base, add your surface layer — use our Gravel Calculator (/landscaping/gravel-calculator) for gravel or our Paving Slab Calculator (/landscaping/paving-slab-calculator) for slabs.

How much does Type 1 sub-base weigh?

Compacted Type 1 MOT aggregate weighs approximately 2.1 tonnes per cubic metre. Loose (uncompacted) Type 1 is slightly lighter at around 1.8-2.0 tonnes per m³. This sub-base tonnage calculator uses the compacted density of 2.1 t/m³ as this represents what you need after compaction.

Do I need to compact Type 1 sub-base?

Yes — Type 1 must be compacted using a vibrating plate compactor (wacker plate) in layers no thicker than 100mm. For depths over 100mm, compact in multiple layers. Proper compaction is essential for a stable, long-lasting base. The surface should not move under foot when properly compacted.

Can I use Type 1 under paving slabs?

Yes, Type 1 makes an excellent sub-base for paving slabs. Lay 100-150mm of compacted Type 1, then a 30-50mm mortar bed or sharp sand laying course on top. Use our Paving Slab Calculator (/landscaping/paving-slab-calculator) to work out slab, sand and cement quantities. Type 1 also works under decking — see our Decking Calculator (/landscaping/decking-calculator).

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Type 1 Sub-Base Calculator — MOT Quantities for Driveways & Paths

Calculate Type 1 MOT sub-base quantities in tonnes and bulk bags for driveways, patios and paths.

Area Length

Length of the area

Area Width

Width of the area

Application

Depth

Compacted depth required

Include wastage allowance

Adds 10% extra for compaction and ground irregularities

Wastage Percentage

10% recommended for most projects

Price Per Tonne (optional)

Enter your supplier price for a cost estimate

How We Calculate This

Our Type 1 sub-base calculator works by multiplying your area by the required depth to get the volume, then converting to tonnes using the compacted density of Type 1 MOT aggregate.

The formula

Volume (m³) = Length (m) × Width (m) × Depth (m)

Weight (tonnes) = Volume (m³) × 2.1

Key assumptions

Type 1 MOT density: 2.1 tonnes per m³ (compacted)
Bulk bag volume: 0.75 m³ per bag
Paths and patios: 100mm depth minimum
Driveways: 150mm depth minimum
Heavy use: 200mm+ depth

Type 1 sub-base should be compacted in layers of no more than 100mm using a vibrating plate compactor. The material should conform to SHW Clause 803. Always order 10% extra to allow for compaction and ground irregularities.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Verify with your supplier.