Use a well-graded MOT Type 1 (also sold as 804) for a driveway sub-base. Its mix of crushed stone down to dust locks together under compaction into a dense, load-bearing bed that won’t rut or shift under a car.
Quick specs:
- Material: Crushed rock, graded 40mm down to dust (MOT Type 1 / 804)
- Compacted depth: a typical range for domestic driveways, with deeper layers recommended on soft ground
- Compaction: Plate compactor essential, not hand tamping
- Grading: Must contain fines, not just clean chippings
Clean, no-fines stone has its place, but only as a decorative top layer over a proper sub-base, or under a permeable drainage system. Crushed concrete is used as a recycled alternative where budget or sustainability considerations are important, though it may not provide the same uniformity.
Key Takeaways
A well-graded MOT Type 1 / 804 sub-base, compacted in thin layers to 100 to 150mm depth with a plate compactor, is the foundation every durable driveway needs.
| Point | Details |
|---|---|
| Choose graded aggregate | MOT Type 1 / 804, graded 40mm down to dust, compacts into a locked, load-bearing bed. |
| Compact in thin layers | Spread and compact in 50 to 75mm layers; a plate compactor only densifies the top layer properly. |
| Order extra material | Add 10 to 20% to your loose volume to account for compaction loss during vibration. |
| Match depth to use | Footpaths need roughly 75mm, patios 100mm, driveways 100 to 150mm, deeper on soft ground. |
| Source quarry-direct material | Poweraggregates supplies graded MOT Type 1 / 804 aggregate with nationwide delivery for driveway projects. |
Table of Contents
- What hardcore actually means for a driveway sub-base
- Sub-base materials and what each name actually means
- How deep should the sub-base be, and how do you compact it?
- Laying hardcore for a driveway, step by step
- Concrete driveways need a different approach
- Ordering the right amount and asking suppliers the right questions
- A note from the yard, not the spec sheet
- Get your hardcore sourced and delivered without the guesswork
- Sources
- FAQ
What hardcore actually means for a driveway sub-base
“Hardcore” is builders’ shorthand for crushed, graded aggregate laid beneath a driveway, patio, or path to spread load and stop the surface sinking. It’s not a single product. It’s a category, and the grading inside that category is what decides whether your driveway lasts fifteen years or cracks up within three winters.
The engineering is straightforward once you see it. Large stones alone leave gaps. Pack those gaps with smaller particles and dust, and the whole mass locks together when compacted, creating a bed that barely moves under a two-tonne car.
- Coarse particles (up to 40mm) carry the structural load
- Fines fill voids between stones and bind the layer
- Interlock happens under vibration from a plate compactor
- Drainage path runs through the compacted matrix, not around it
That’s why MOT Type 1 / 804, with its full range of particle sizes, outperforms single-size stone as a structural base, and why plate compaction, not a shovel and boot, is the standard method for getting there.
Sub-base materials and what each name actually means
Yard staff and product listings throw around several near-identical terms. Here’s what you’re actually buying under each one.
- MOT Type 1 / 804: The industry standard sub-base. Graded 40mm down to dust, crushed limestone or granite depending on quarry. This is what you want under a driveway.
- Crusher run: Often the same graded product as Type 1, sometimes slightly coarser. Ask the supplier to confirm the grading before assuming it’s identical.
- Crushed concrete: Recycled demolition material, screened and graded similarly to Type 1. A solid, more sustainable option if the recycled content is properly certified.
- Clean stone / no-fines: Washed chippings with no dust or fines. Good for a decorative loose-gravel finish or a drainage layer, poor as a structural sub-base because there’s nothing binding the stones together.
- MOT Type 3: A free-draining variant with less fines, used where permeability matters more than maximum density, such as under permeable paving systems.
When you’re at the counter or scrolling a product page, the phrase to listen for is “graded to dust” or “40mm down.” If a supplier can’t confirm that grading, ask what percentage passes a fine sieve, because that’s what tells you whether it’ll compact properly or stay loose forever.
How deep should the sub-base be, and how do you compact it?
Depth and compaction aren’t guesswork. They follow fairly fixed rules depending on what’s going on top.
| Finish | Typical compacted depth | Compaction needs |
|---|---|---|
| Footpath | ~75mm | Plate compactor, light passes |
| Patio | ~100mm | Plate compactor, standard passes |
| Domestic driveway (cars) | a typical range for domestic driveways | Plate compactor, multiple passes per layer |
| Heavier traffic (vans, occasional HGV) | 150mm+, ground-dependent | Heavier plate or roller, engineer input on very soft ground |
Those depth figures come from standard UK sub-base guidance, and they assume reasonable ground conditions. Soft clay or waterlogged subsoil pushes the depth up and usually calls for a geotextile membrane underneath.
Falls matter as much as depth. Build in a gradient of roughly 1:60 to 1:80 so surface water runs off rather than pooling, and get edge restraints, kerbs or heavy timber, in before the hardcore goes down, not after.
Pro Tip: A plate compactor only properly densifies the top 50–75mm it’s sitting on. Spread and compact in layers of that thickness rather than dumping the whole depth and running the plate over it once. That single habit, confirmed by multiple installation guides, is the difference between a driveway that settles evenly and one that develops soft patches.
Expect roughly 10 to 20% compaction loss once the vibration plate does its work, so the loose material you tip on site will shrink down noticeably.
Laying hardcore for a driveway, step by step
- Set out and mark falls. Peg the perimeter and run string lines showing your finished level and drainage gradient before you dig anything.
- Excavate to working depth. Dig out topsoil and subsoil to allow for your sub-base depth plus the wearing course above it, checking against your pegs regularly.
- Lay geotextile if needed. On soft or clay ground, roll membrane across the full excavation, overlapping joins by at least 300mm to stop mud pumping up into the stone.
- Install edge restraints. Kerbs or timber edging go in now, before the hardcore, or the finished edge will migrate outward and crumble.
- Spread in layers. Tip and rake hardcore into layers of 50–75mm loose depth across the whole area.
- Compact each layer. Run the plate compactor over each layer before adding the next, checking for even density with no visible movement underfoot.
- Check final depth and level. Measure down from your string lines to confirm compacted depth matches your target before laying the surface finish.
- Hire a plate compactor (100kg+) for domestic driveways; a small vibrating plate meant for patios won’t cut it for vehicle loads.
- Hire a mini-digger if you’re excavating more than a few square metres by hand.
- Call in a structural engineer if the ground is persistently soft, waterlogged, or you’re planning for heavy vehicle loads. No amount of extra hardcore fixes genuinely unstable subsoil.
Concrete driveways need a different approach
A concrete slab behaves differently to block paving or gravel, and the sub-base underneath has to match. Concrete is rigid, so any uneven settlement in the ground beneath shows up as cracking rather than the gentle dips you’d get with flexible paving.
- A well-compacted MOT Type 1 / 804 base of at least 150mm is generally required to reduce differential settlement under the slab.
- Reinforcement, whether mesh or rebar, is worth discussing with a professional for anything beyond a small path, particularly on driveways carrying regular vehicle weight.
- Falls and drainage still matter. Trapped water under a slab, or against it, is one of the more common causes of premature cracking, alongside poor sub-base preparation.
Get the ground engineering wrong here and you’re not looking at a resurfacing job. You’re looking at breaking out concrete.
Ordering the right amount and asking suppliers the right questions
Work out quantity before you order, not after the lorry turns up. For a driveway measuring 40m² at 150mm compacted depth: 40 × 0.15 = 6m³ of compacted material. Because loose stone compresses by 10 to 20% once vibrated, you need to order the loose equivalent, roughly 7 to 7.2m³, which typically works out to around 12 to 13 tonnes depending on the material’s density. Most suppliers sell in bulk bags (around 850kg to a tonne each) or loose loads by the tonne, so that 6m³ compacted target becomes roughly 13 bulk bags once you allow for compaction.
Before you order, ask any supplier:
- What’s the exact grading spec, and does it include fines?
- Is there recycled content, and is it certified?
- Is stock available now, or is it a lead-time order?
- Is delivery tipped on-site or does it need offloading assistance?
- Can they confirm the source quarry and quality documentation?
Power Aggregates supplies quarry-sourced MOT Type 1 / 804 with nationwide delivery, which covers the sourcing and quality-assurance side of that list directly. Always add 10 to 20% extra to your calculated volume for compaction loss and site waste, and confirm delivery access for larger vehicles before the load is booked.
A note from the yard, not the spec sheet
The mistake I see most often isn’t the wrong material. It’s skipping edge restraints because they seem like a finishing touch rather than a structural one. Without them, even perfectly graded hardcore migrates sideways under load.
Pro Tip: Recheck your levels after the final compaction pass, not before it. Compaction loss shifts your finished height more than most DIYers expect.
Get your hardcore sourced and delivered without the guesswork
Sourcing the right grade of MOT Type 1 or 804 is where most driveway projects either go smoothly or stall waiting on the wrong delivery. Poweraggregates supplies quarry-direct aggregates with nationwide delivery across Ireland, so you’re getting material straight from source rather than through several hands.
Whatever finish you’re planning, loose gravel, block paving, or a poured concrete slab, the sub-base underneath needs to match that finish’s specific demands, and our team can talk you through the right grading and depth for your ground conditions before you order. Browse the full range of decorative stone and aggregates to see current stock, or get in touch for a quote on bulk delivery and offloading options for your driveway project.
Sources
- What Sub-Base Do I Need? | Marshalls
- How to Lay an MOT Type 1 Sub-Base: Depths, Compaction and a Step-by-Step Method | Build Journal
- Pavingexpert — subbase guidance
- How to Lay a Sub-Base for a Driveway (Step-by-Step UK Guide) — UK Building Supplies
FAQ
What is the best sub-base for a driveway?
A well-graded MOT Type 1 / 804, containing particles from 40mm down to dust, is the standard choice because the fines bind the larger stones into a compact, load-bearing layer.
What is the best type of sub-base for a concrete driveway?
Concrete slabs generally need at least 150mm of compacted MOT Type 1 / 804 beneath them to limit differential settlement, since any movement in the ground shows up as cracking in the rigid slab above.
What is the cheapest base for a driveway?
Crushed concrete, a recycled alternative to quarried Type 1, is often the most budget-friendly structural option, though clean stone can be cheaper still, it’s only suitable as a decorative top layer, not the structural base itself.
How much hardcore do I need for a driveway?
Multiply your area in square metres by your target compacted depth in metres to get cubic metres, then add 10 to 20% for compaction loss when ordering loose material.
Can I use crusher run instead of MOT Type 1?
Crusher run is often graded the same way as MOT Type 1, but grading can vary by supplier, so confirm it’s “40mm down to dust” before assuming it will compact the same way.