What Is MOT Type 1?

The Short Answer

By Gary Hodson · Ex-Army. I do the sums so you buy the right amount. · Grading and depths checked against the sources below, prices read on 8 October 2026 · Last reviewed 8 October 2026

MOT Type 1 is crushed stone sold as a mix of sizes, from about 40mm down to dust, made to a written recipe. The recipe is clause 803 of the Specification for Highway Works.¹ Packed down with a plate compactor, the dust fills the gaps between the stones and the layer locks solid. That is why it sits under patios and paths, and under drives and shed bases.

Hardcore is rubble with no recipe. Scalpings and crusher run are quarry products with no set grading. Type 3 has its own clause 805 grading and is a deliberately open mix that lets water through, so it is the one used under permeable paving. For ordinary paving and drives, Type 1 is the grading to ask for.

On 8 October 2026 Wickes charged £75 for an 800kg jumbo bag, which is £93.75 a tonne, and £5 for a 22.5kg bag, which is £222 a tonne.⁷ Loose delivery started at £30 a tonne.¹⁰ For the amount, use 0.21 tonnes per square metre for every 100mm of depth.

A Recipe, Not Just a Rock

The name is a leftover. MOT stands for the old Ministry of Transport, which wrote the first version of the recipe, and the material is still sold as MOT1 or DTp1.³ It has nothing to do with a car test.

Clause 803 says Type 1 must be crushed rock, crushed slag, crushed concrete, recycled aggregate or well burnt shale, with no more than 10% natural sand. The part that makes it Type 1 is the grading. The specification sets how much of the mix must pass through each sieve size:¹

So “40mm to dust” is the trade shorthand, and the rulebook allows a few bigger lumps. Pavingexpert points out that the bulk of a load is below 31.5mm.² The stones must be crushed, not rounded gravel, so the faces grip each other. The fine part must also be non-plastic, meaning it does not turn to putty when wet.¹

Recycled stone is allowed. Crushed concrete sold as Type 1 is legitimate if it meets the same grading. Tarmac, the producer, describes its Type 1 as a graded angular material that meets clause 803.⁶

Type 1 Against Everything It Gets Mistaken For

Merchants use these names loosely. The table shows what each one is meant to be. The last column is the density our sub-base calculator uses for the weight sum.

The clause numbers come from the Specification for Highway Works.¹ The descriptions come from Pavingexpert.²⁴ The densities are our own working figures, not a standard.

Hardcore

Pavingexpert defines hardcore as any hard, crushed inert material that works as fill, and most people picture demolition waste.⁴ Some of it is now crushed and sorted well enough to pass as sub-base, but the same source warns that a lot of what is sold is dirty, with timber and weeds in it, and old tarmac.⁴ Use it to raise levels and fill holes. Put Type 1 on top.

Scalpings and crusher run

Both cover a similar size range to Type 1 with nobody checking the mix. A load can be lumpy or full of fines, and the extra fines mean less load-bearing strength than a true Type 1.² Pavingexpert still lists 50mm of compacted crusher run as an alternative for foot traffic and light drives.³ Crusher run at 75mm or 100mm is too chunky and belongs in fill.²

Type 3

Type 3 is open-graded: the specification allows fewer fines than Type 1 (category UF5 against UF9), so water passes through.¹ It is not no-fines, and Pavingexpert notes that up to a quarter of it can be 1mm or smaller.² It is the stone for permeable paving. For ordinary paving that sheds water to a drain or a border, Type 1 is the usual choice.

How Deep, Job by Job

Depths are compacted depths, after the plate compactor has finished. The tonnes column is our own sum, with 2,100 kg/m³ applied to the compacted depth. That already allows for the extra loose material that squashes down: Pavingexpert’s 5m² a tonne at 100mm compacted works out at about 2,000 kg/m³, so our sums sit about 5% above it. Order a little extra for uneven ground.

The calculator’s own depth guide uses 75mm for foot traffic. If you are laying Marshalls slabs, take their 100mm minimum instead. For a shed, the maker’s base instructions come first.

Build it in layers. Marshalls caps each layer at 75mm,⁵ Pavingexpert at 150mm.³ Two 75mm layers satisfy both. Pavingexpert also gives a very rough rule that Type 1 squashes by about 30%, so 130mm loose becomes about 100mm. The tonnes in the tables are per compacted depth, so that squash is already counted.³ When the top is done it should look tight, with no open holes. Fill any open patches with fines or coarse sand.³

Bags, Bulk Bags or a Loose Load

Prices below were read off the sellers’ own pages on 8 October 2026. They are shop prices as displayed, and the per tonne column is our own arithmetic.

Seller pages:⁷⁸⁹¹⁰ The loose prices are “from” prices for single regions. Delivery is not in them, and yours will differ.

B&Q’s sub-base page shows the spread well. Bulk bags labelled MOT Type 1 ran from £84.95 for 800kg to £192.50 for 850kg, and some listings in that range are granite dust, which is a different product.⁸ Check the weight and grading first, then compare the price.

Worked example: two jobs, three ways to buy

Our own sums, at 2,100 kg/m³ applied to the compacted depth. A 4m by 3m patio at 100mm is 12 × 0.1 = 1.2m³, and 1.2 × 2,100 = 2,520kg, so 2.52 tonnes. A 3m by 6m drive at 150mm is 18 × 0.15 = 2.7m³, and 2.7 × 2,100 = 5,670kg, so 5.67 tonnes.

Small bags make sense for topping up a low spot or filling round a post. Past about half a tonne they cost far more than a bulk bag. For the drive, the loose figure uses six tonnes because 5.67 rounds up and Manchester Grab Hire sets six as its minimum: 6 × £26.57 is £159.42 ex VAT, or about £191 with VAT added. 6 × £30 is £180, and HGS does not say on its page whether that includes VAT.

Do the Weight Sum, Not the Bag Count

Bags are sold by weight, and the weights differ. We found 22.5kg packs, plus 800kg and 850kg bulk bags. The word “bulk” on a listing tells you nothing about the weight. One B&Q marketplace seller warns that moisture can shift each bag by 5% either way.⁸ HGS Southern says the same about its loads.¹⁰

Printed coverage can also run generous. Wickes says its jumbo bag covers 7.7m² at 50mm, which works out at about 2,080kg/m³ and agrees with our figure. Wickes prints 0.6m² at 25mm on the 22.5kg bag page.⁷ At 2,100kg/m³ that bag covers 22.5 ÷ 2,100 ÷ 0.025 = 0.43m², so trust the weight sum and ignore the sticker.

At 100mm one tonne of Type 1 covers 1 ÷ 0.21 = 4.8m² on our numbers. Pavingexpert says about 5m²² and Manchester Grab Hire says 4.5 to 5.5m².¹⁰ The calculator uses 4.8m², which sits inside that range but above its lowest figure, so allow a margin and check the coverage your supplier states for the load you are buying. The same sum works for hardcore at 2,000kg/m³: the same 12m² patio at 100mm needs 1.2 × 2,000 = 2,400kg, or 2.4 tonnes of fill.

Enter your own length and width, plus the depth, in the sub-base calculator and it gives tonnes, and also 850kg bags or 25kg bags. If the sums need unit help, the litres in a tonne guide covers the conversions. The paving calculator sizes the slabs that go on top, and the concrete calculator covers a concrete slab base. For tarmac on top, see tarmac cost per tonne.

Mistakes That Cost Money

• Hardcore as the top layer. It has voids and no grading. Slabs rock on it.
• Tipping the full depth and compacting once. The lower part stays loose and settles later. Work in layers.
• Buying Type 3 for a normal patio. It is made to drain. Use it when the paving maker specifies permeable construction.
• Comparing bag prices without comparing weights. A cheap bag that weighs less is not cheap.
• Ordering a loose load for a small job. Minimums and delivery charges can erase the saving. Two to four bulk bags often win on a patio.
• Trusting the name. “Type 1” on a listing is a claim. Ask for clause 803 and the grading.

Frequently Asked Questions

Work Out Your Quantity