MOT Type 1 vs Type 3: What Is the Difference?
If you have been pricing up a sub-base, you will have seen "MOT Type 1" and "Type 3" used side by side, and wondered whether they are interchangeable. They are not. Both are crushed stone, but they are graded differently, and that changes how they compact and how water moves through them. This guide explains the difference in plain terms.
What does "MOT" mean?
MOT stands for the Ministry of Transport, which originally wrote the specification for road sub-base stone. The name stuck, and the "Type" number refers to the grading of the stone in the original highways specification. Today it is simply the name builders and merchants use.
MOT Type 1
MOT Type 1 is a densely graded crushed stone, from roughly 40mm pieces down to fine dust. The mix of sizes means the fine material fills the voids between the bigger pieces. When you wet it slightly and compact it with a plate compactor, it locks into a tight, firm layer that shows little movement afterwards.
- Compacts to a dense, stable surface
- Gives a flat, even surface to lay bedding and paving on
- Not designed to drain freely, because the fines restrict water flow
This is the material most people mean when they say "sub-base". It is our standard for patios, paths, shed bases and driveways, and you can order it as an MOT Type 1 sub-base bulk bag (800kg).
MOT Type 3
Type 3 is an open-graded stone. It has little or none of the fine material, so there are spaces between the pieces. That gives it two key characteristics:
- It drains freely. Water passes through the gaps instead of sitting in the base.
- It does not lock together in the same way. Without the fines, it is less tightly bound and can give a rougher surface.
Type 3 is sometimes specified where drainage matters, such as under permeable surfaces or as a drainage layer. Permeable paving systems are often designed around specific clean, single-size stone, so follow the specification for your system rather than guessing.
Side-by-side comparison
| MOT Type 1 | Type 3 | |
|---|---|---|
| Grading | Dense, from about 40mm down to dust | Open, with little fine material |
| Compaction | Locks together tightly | Does not lock together as tightly |
| Drainage | Limited | Free-draining |
| Typical use | Patio, path, shed and driveway sub-base | Drainage layers and some permeable builds |
What do we stock?
We list MOT Type 1, as above, and a hardcore / crusher run bulk bag, which is a crushed stone, dust and recycled material mix commonly used as a heavy-duty base under driveways, paths, patios and slabs. We do not currently list Type 3 as a separate product. If your project specifically calls for open-graded stone, check what is recommended for it and call us on 03330 908479 to ask what we can supply.
For drainage jobs such as pipe bedding, soakaways and French drains, many people use clean gravel instead. We stock 10mm gravel / shingle bulk bag and 20mm gravel / shingle bulk bag, plus trade packs for small jobs.
Which should you choose?
- Patio, path, shed base, standard driveway: MOT Type 1.
- Very heavy-duty or very rough base layer: hardcore or crusher run, often topped with MOT Type 1 for a tight surface.
- Drainage or permeable construction: follow the design for your system, which is typically open, clean stone.
If you are working out quantities for Type 1, see how much MOT Type 1 you need for a patio.
Frequently asked questions
Is MOT Type 1 the same as hardcore?
No. Hardcore is a coarser, rougher mix and often includes recycled material, whereas MOT Type 1 is a more tightly graded crushed stone. They are often used together, with hardcore underneath and MOT Type 1 on top.
Can I use Type 1 under a permeable driveway?
Usually not. Permeable systems rely on free-draining stone, and the fines in Type 1 can clog the voids. Follow your system's specification.
Why is MOT Type 1 so popular?
Because it compacts into a firm, stable layer and gives a flat surface for bedding, which suits most patio, path and driveway jobs.
Does Type 1 need compacting in layers?
Yes. Build it up in layers and compact each with a plate compactor. Follow the machine's guidance on layer thickness.
Where can I see how much I need?
Our guides on a patio and a driveway have worked examples.
Ordering and delivery
You can browse the full range in our cement and aggregates collection. Bulk bags are sold at approximately 800kg each (the packed weight can be up to 850kg depending on moisture), and most sands and gravels are also available in 20 to 25kg trade packs for small jobs. Prices on our website are shown excluding VAT, and VAT is added at checkout.
We deliver to addresses in mainland England only; we do not currently deliver to Wales, Scotland, Northern Ireland or the islands. Timber, aggregates and cement have a minimum order of £250 ex VAT, and delivery is £25 ex VAT on orders under £500 ex VAT and free over £500 ex VAT. Bulk bags are delivered by Moffett lorry (truck-mounted forklift) and offloaded at your site, so someone must be there to receive them and you will need a firm, level area with suitable access. We do not offer next-day delivery. Our shipping policy has the full details, or call us on 03330 908479 or email sales@insulationwarehousedirect.co.uk if you would like a hand working out your order.
The quantities in this guide are estimates. Ground levels, how well the material is compacted and how wet it is all change what you need, and densities vary between quarries, so check the amount with your installer or the manufacturer's guidance before you order. Prices and pack sizes are correct at the time of writing.
Working out quantities? See our MOT Type 1 sub-base guide: how much do I need? or go straight to our aggregates calculator.