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What Is the Best Aggregate for Driveways & Shed Bases?

29th July 2026

The driveway looked good going down. The gravel was the right colour, the edging was straight, and the whole job was done in a day. Six months later, the sub-base had shifted, the surface was rutting under the car, and the whole thing needed lifting. The aggregate itself was fine. The problem was what went under it.

Choosing the best aggregate for driveways and shed bases is not complicated, but it does require knowing what each material is actually for. Load-bearing and drainage drive every decision. A vehicle-trafficked surface needs a sub-base that compacts hard and locks under repeated weight. A shed base needs a platform that sheds water and holds level. Get either wrong and no amount of careful finishing saves it.

This guide covers the materials that matter, the depths that work, and the mistakes that cost people twice.

What Type 1 & Type 2 Aggregate Do Differently

Type 1 and Type 2 are both unbound granular sub-base materials. They behave differently under load in ways that matter to anyone building a driveway.

Type 1 is well-graded crushed stone with a controlled proportion of fines that lock it together under compaction. That is the source of its load-bearing strength and why it is the standard sub-base for vehicle-trafficked surfaces. Construction Industry Research and Information Association's (CIRIA) susdrain guidance confirms that Type 1's high fines content makes it sensitive to moisture changes and largely impermeable, compared with open-graded materials chosen specifically to provide open voids [1].

Type 2 has fewer fines and compacts less tightly. It has a place under light pedestrian paving or as a drainage layer where water movement matters more than bearing capacity. Under a driveway, it is the wrong choice.

When To Use Type 2 Instead

Type 2 earns its place beneath soakaways, around French drains, or as an open-graded fill in a permeable driveway system. For any surface a vehicle will cross, Type 1 is correct. Using Type 2 beneath a driveway is a common and expensive mistake.

What Gravel Actually Stops a Driveway from Moving

A loose-gravel driveway that migrates onto the pavement or churns into ruts has almost always been built with the wrong material or a skimped sub-base. The surface gravel is rarely the issue. The problem sits underneath it.

Surface material matters too. Rounded materials like pea shingle roll against each other and never truly interlock. Angular crushed stone grips; compact it properly, and it holds position under wheel loads.

Ministry of Housing, Communities and Local Government (MHCLG) guidance on permeable surfacing of front gardens sets out the correct build sequence. It specifies a geotextile membrane at the base, a minimum 200mm of compacted open-graded sub-base, then approximately 50mm of decorative gravel at the surface. Conventional Type 1 contains sand and silt that blocks water movement, which is why open-graded materials are used in permeable systems instead [2].

Since October 2008, any impermeable front garden driveway over 5 square metres needs planning permission unless water drains to a permeable area. Gravel is permeable and does not trigger this. Ten-millimetre angular gravel gives a tighter finish underfoot; 20mm drains better and holds more effectively under tyres.

On softer or clay ground, the depth and specification for a sub-base changes. The same principles apply when choosing aggregates for hardscaping projects, where drainage and load-bearing sit alongside aesthetic choices.

Our aggregate and gravel range is available in bulk bags with delivery across Bristol, Bath, Cheddar, Avonmouth, Newport, and the wider South West.

How Thick a Gravel Base Actually Needs to Be for A Shed

The shed base that fails is almost always one that was compacted by someone standing on it and deciding it felt firm enough. It never is. Ask any groundworker who has lifted a sunken shed six months after the pour.

For a standard timber shed, work through the sequence in order:

Excavate topsoil down to firm ground and lay a weed membrane.
Add compacted Type 1 sub-base across the full footprint.
Top with levelled 20mm angular gravel, extended 50mm beyond the walls.

The Planning Portal's guidance on outbuilding foundations confirms that soil type is a significant factor in both depth and design. Clay soils expand and contract with moisture changes, affecting base performance over time. On firm ground, 100mm of compacted Type 1 is the working minimum; 150mm on soft or clay ground, or for heavier structures [3].

Gravel Base or Concrete: Which Is Right for A Shed?

Gravel drains freely, installs quickly, and needs no curing time. On soft ground, sloping sites, or under a heavy structure, a concrete slab is the more reliable choice. What neither will forgive is poor compaction. Compact in layers, check for level in both directions, and get it right before the shed goes on.

If you are moving from a gravel base to a concrete slab, the preparation sequence changes. Laying concrete correctly starts well before the truck arrives. The sub-base condition, formwork, and weather all affect the finished result.

The Decisions that Hold

Most driveway and shed base failures trace back to one of three choices made early in the job. Wrong sub-base material, rounded stone where angular should have gone, or a base compacted by eye rather than by depth. None of these mistakes is obvious at the time. They show up six months later, once load and water have done their work.

The three things that matter most:

Type 1 sub-base compacts hard and carries load; Type 2 does not.
Angular gravel interlocks under traffic; rounded stone migrates.
Compacted depth, not decorative depth, keeps a base level long-term.

Wright Readymix supplies 17 aggregate and gravel options in bulk bags, delivered across Bristol, Bath, Avonmouth, Cheddar, Newport, and Weston-super-Mare. The team can advise on material selection before you order, whether for a driveway, a shed base, or a larger groundworks job.

Call 0117 958 2090 or get in touch to discuss your aggregate requirements.