If you’ve ever priced up a driveway, patio, foundation base, or drainage job, you’ve probably come across the word aggregate. It’s one of those building materials that’s used everywhere – from large-scale construction sites to domestic garden projects – but not everyone knows what it actually means or which type is best for the job.
In simple terms, aggregates are the crushed stone, gravel, and sand-based materials used to form strong sub-bases, improve drainage, and provide stability for a wide range of building work.
In this blog, we’ll cover what aggregate is and explain the most common types of aggregate and their uses so you can make an informed choice for your next project.
What is aggregate?
Aggregate is a broad term used to describe granular materials such as crushed rock, gravel, sand, and recycled stone. These materials are widely used in construction because they provide strength, stability, and drainage.
Aggregates can be used on their own, or combined with other materials such as cement or asphalt. You’ll often find aggregate used as the base layer underneath:
- Driveways and paths
- Patios and paving
- Roads and car parks
- Concrete slabs and foundations
- Drainage systems
- Landscaping and garden features
There are different grades and types of aggregate because each job needs a different outcome. For example, some projects need a solid, load-bearing base, while others need water to drain away quickly without pooling.
The best aggregate for your project will depend on a few factors, including:
- The weight/load the area will take (vehicles vs foot traffic)
- How much drainage is required
- Whether the base needs to be compacted tightly
- The finish you want to achieve
What are the different types of aggregate and their uses?
When people talk about the types of aggregate, they’re usually referring to either the size of the stone (such as 10mm or 20mm) or the grade of aggregate used for a specific job – for example Type 1 aggregate, Type 2 aggregate, or Type 3 aggregate.
While there are lots of aggregate materials available, Type 1-3 are most commonly used for groundworks and sub-base preparation. Each type performs slightly differently depending on whether you need a base that compacts firmly, supports heavy loads, or drains water quickly.
Below, we break down these common types of aggregate and where they’re typically used.
Type 1 aggregate
Type 1 aggregate (often called MOT Type 1) is one of the most commonly used sub-based materials in UK construction. It’s a crushed stone aggregate made up of a mixture of larger stones and smaller particles (including fines), which allows it to compact tightly and form a strong, stable base layer.
Because it locks together well once compacted, Type 1 aggregate is ideal for projects where strength and durability matter, especially if the surface will be taking regular footfall or vehicle weight over time.
Some common uses for Type 1 aggregate include:
- Sub-bases for driveways, paths, patios, and block paving
- Base layers beneath concrete slabs and foundations
- Hardstanding areas and access routes
- Groundwork preparation for garden buildings and sheds
One of the key benefits of Type 1 is that it creates a firm foundation that helps prevent movement, dips, or sinking later on. For best results, it should be laid in layers and compacted thoroughly using a wacker plate or roller. If the ground is soft or unstable, you may also need to install a geotextile membrane beneath the sub-base to reduce mixing with the soil and improve performance.
Type 2 aggregate
Type 2 aggregate is a heavy-duty option that’s often used when a job needs a deeper or more robust sub-base. Like Type 1, it’s typically crushed stone aggregate, but Type 2 usually contains larger stone sizes and is designed for situations where strength and long-term stability are a priority.
You’ll often see Type 2 aggregate used on projects that will take heavier loads, or where the groundwork needs to be built up more substantially before a finishing layer is added.
Some common uses for Type 2 aggregate include:
- Road construction and deeper sub-base builds
- Commercial yards, car parks, and access roads
- Larger groundwork projects and bulk fill areas
- Bases designed for heavier vehicles and equipment
Type 2 can be a great choice if you’re working on a site where the ground conditions aren’t ideal, or where you need a stronger base layer to support traffic over time. As with any sub-base material, it should be installed in manageable layers and compacted properly to avoid settlement later on.
Type 3 aggregate
Type 3 aggregate is designed for projects where drainage and permeability are just as important as stability. It’s often described as a clean, free-drainage aggregate, meaning it contains fewer fines than Type 1. This allows water to pass through more easily, which can help reduce water build-up within the sub-base.
Because of this, Type 3 aggregate is frequently used for permeable surfaces and groundwork projects where managing surface water is a key consideration, particularly in areas that are prone to pooling or poor drainage.
Some common uses for Type 3 aggregate include:
- Permeable driveways and pathways
- Drainage-focused groundwork builds
- Areas where standing water is an issue
- Soakaways and drainage layers around landscaping features
Type 3 is a popular choice for projects that need a sub-base that stays stable but doesn’t trap moisture. That said, because it contains fewer finer particles, it won’t “bind” in quite the same way as Type 1, so the correct installation depth and compaction method is still important.
If you’re working on a driveway, patio, or hardstanding area where water management is a priority, Type 3 aggregate can be a smart alternative to help improve drainage and reduce the chance of water sitting in the base layers, especially when combined with the right surface finish and fall away from the property.
Our tips for choosing the aggregate for your project
Choosing the right aggregate comes down to what you’re building, how much weight it needs to support, and whether drainage is a priority. To help you make the right choice, here are some of our top tips:
- Start with the purpose of the area – choose your aggregate based on whether the area will take light foot traffic or heavier vehicle weight.
- Think about drainage and ground conditions – if you’re working in an area prone to waterpooling or you need a permeable base, Type 3 aggregate is an ideal option.
- Decide whether you need maximum compaction – Type 1 aggregate is great for firm compaction and creating a stable base.
- Match the aggregate to the surface you’re installing – if you’re laying a finished surface on top, choose the right sub-base aggregate to prevent sinking, movement, and uneven results.
- Don’t underestimate the importance of depth – groundworks should be installed at the correct depth and compacted in layers for long-term strength. Type 2 aggregate is suitable for heavier duty or deeper groundworks builds.
- Use the right compaction method – a wacker plate or roller helps compact the aggregate properly, which reduces movement over time.
If you’re unsure which type of aggregate is right for your project, ask for advice before ordering. Choosing the right aggregate from the start helps prevent problems later on.
Get a bespoke quote today
Choosing the right aggregate makes a big difference to how well a project performs over time – whether you’re laying a patio, building a driveway, or prepping a solid base for foundations.
At JTD Building Supplies, we supply a wide range of aggregates for domestic and trade projects, and we can help you choose the right material for the job based on your site requirements.
If you’re not sure whether you need Type 1 aggregate, Type 2 aggregate, or Type 3 aggregate, get in touch with our team today for practical advice and a bespoke quote.
FAQs on the different types of aggregate
What are aggregates used for in construction?
Aggregates are used for a wide range of building and groundwork projects, including driveways, patios, paths, drainage work, foundations, and concrete mixes. They help create strong sub-bases, improve stability, and support long-term performance.
What’s the difference between gravel and aggregate?
Aggregate is a broad term that includes materials like crushed stone, sand, recycled hardcore, and gravel. Gravel is a type of aggregate and is usually made up of rounded stones and often used for decorative finishes or drainage-based applications.
What are the different types of aggregate?
The most common types of aggregate include crushed stone, natural gravel, sand (fine aggregate), recycled aggregate, and specialist drainage aggregate. For sub-bases in UK construction, the most common grades are Type 1 aggregate, Type 2 aggregate, and Type 3 aggregate.
Is Type 3 aggregate better than Type 1?
Not necessarily as it depends on the project. Type 1 aggregate is usually better for creating a firm, load-bearing base while Type 3 aggregate is better for drainage. If your priority is strength, Type 1 is often the best choice. If your priority is water flow and permeability, Type 3 may be more suitable.
Do I need to compact aggregate?
Yes, most aggregates used for sub-bases should be compacted to improve stability and reduce movements over time. Type 1 aggregate, in particular, performs best when laid in layers and compacted thoroughly using a wacker plate or roller.
Can I use recycled aggregate instead of Type 1?
In many cases, yes. Recycled aggregates (such as crushed concrete and hardcore) can often be used for sub-base work, provided they meet the correct grading and compaction requirements. If you’re unsure, it’s best to check what your project needs and ask for advice before ordering.
