MOT Type 1 Explained: What It Is and How Deep to Lay It
Last updated: September 2026
MOT Type 1 is the crushed stone that goes under almost every patio, path, driveway and shed base in the UK. Get the sub-base right and your paving stays flat for decades. Skimp on it and slabs rock, blocks sink and gravel ruts.
What is MOT Type 1?
MOT Type 1 is a graded aggregate of crushed rock or recycled concrete, with pieces from around 40mm down to fine dust. The mix of sizes is the key. When compacted, the fine particles fill the gaps between the larger stones and lock together into a solid, load-bearing layer. The name comes from the old Ministry of Transport road specification.
Type 1 vs Type 3 vs scalpings
- MOT Type 1: lots of fines, so it compacts very hard. The standard choice for patios, paths, driveways and shed bases.
- Type 3: has fewer fine particles, so water can drain through it. Used under permeable paving and permeable resin-bound driveways.
- Scalpings / crusher run: cheaper, less consistent material. Fine for garden paths and informal areas, but not ideal under driveways.
- Recycled Type 1: made from crushed concrete and brick. Usually cheaper and fine for most home jobs if it's from a reputable supplier.
How deep should it be?
| Use | Compacted depth |
|---|---|
| Garden paths | 75–100mm |
| Patios | 100mm |
| Shed bases | 75–100mm |
| Car driveways | 150mm |
| Soft ground, clay or heavier vehicles | 200mm or more |
These are compacted depths. Loose Type 1 compacts down by roughly a fifth to a quarter, so spread it a bit thicker.
How to lay it
- Dig out to allow for the sub-base, the bedding layer and the paving itself, plus any fall for drainage.
- Lay a geotextile membrane on soft or clay soils to stop the Type 1 sinking into the ground.
- Spread in layers of no more than about 75–100mm at a time.
- Compact each layer with a plate compactor (easy to hire for the day), going over it several times in different directions.
- Check levels with a string line and spirit level, including the fall – patios usually need a fall of about 1 in 60 away from the house.
- Hand tamping isn't good enough for anything you'll drive on. Hire a plate compactor.
How much do you need?
Work out the volume (area × depth in metres), then multiply by around 2.1 tonnes per m³ for compacted Type 1. For example, a 15m² patio at 100mm needs 1.5m³, or about 3.2 tonnes – roughly four 850kg bulk bags. The MOT Type 1 Calculator does the maths and suggests bulk bags vs loose tonnage.
Frequently asked questions
Can I use hardcore instead of Type 1?
Broken bricks and rubble can work for a garden path, but they don't compact as evenly. For patios and driveways, use proper Type 1.
Do I need a membrane under Type 1?
On clay or soft ground, yes – it stops the sub-base mixing into the soil. On firm, well-drained ground it's optional.
Should Type 1 be wet or dry when compacting?
Slightly damp compacts best. Bone-dry Type 1 won't lock together well; waterlogged Type 1 goes soft.
How much does a bulk bag of Type 1 cover?
An 850kg bag covers about 4m² at 100mm, or about 2.7m² at 150mm.