What Is a Sub-Base? A Guide

What Is a Sub-Base? A DIY Guide

When you're laying a patio, driveway, garden path, or even artificial turf, getting the sub-base right is essential.

It’s the hidden layer that supports everything above it. Without it, your project won’t last.

In this guide, we’ll break down what a sub-base is, why it matters, what materials you can use, and how to lay one using tools available for hire from Speedy.

 

What Is a Sub-Base?

A sub-base is the layer of compacted material that sits underneath paving, tarmac, turf, or concrete. It helps spread the load evenly, improves drainage, and prevents sinking or shifting over time.

Without a stable sub-base, your patio might crack, your driveway might dip, and your artificial lawn could become uneven.

 

What Materials Are Used in a Sub-Base?

The most commonly used sub-base material in the UK is:

• MOT Type 1: A crushed aggregate made from limestone or granite, approved for highways and ideal for most domestic projects.

• Type 3: Similar to Type 1 but more permeable, better suited for sustainable drainage (SuDS) areas.

• Sharp Sand: Often used as a screeding layer on top of the sub-base when laying paving slabs or blocks.

• Recycled Aggregate: A sustainable alternative, often used for domestic jobs.

 

How Deep Should a Sub-Base Be?

It depends on the type of surface you're laying:

• Driveways: 100–150mm (MOT Type 1)

• Patios & Paths: 75–100mm

• Artificial Grass: 50–75mm of MOT Type 1, followed by 25–50mm of sharp sand

Always check your local building regulations and use a depth that matches the load the surface will carry.

 

How to Create a Sub-Base

Tools You'll Need (Available to Hire from Speedy)

To lay a proper sub-base, these tools will make the job quicker, safer, and more precise:

• Mini Digger – For excavating the ground

• Wacker Plate/Compactor Plate – Essential for compacting each layer of the sub-base

• Wheelbarrow – For transporting aggregate and sand

• Shovel & Rake – For spreading and levelling

• Laser Level or Spirit Level – To check for a consistent slope and surface

 

How to Lay a Sub-Base (Step-by-Step)

1. Mark & Excavate
Clear the area and dig down to the required depth using the mini digger, allowing for both the sub-base and the surface layer. Ensure you include a slight slope for water drainage.

2. Lay the Sub-Base Material
Spread your MOT Type 1 (or chosen material) in layers of around 50mm. Don’t dump it all in at once, as it won’t compact properly. Use a rake to spread it if needed.

3. Compact Each Layer
Use a wacker plate to compact each layer thoroughly before adding the next. This prevents air gaps that could lead to subsidence.

4. Check the Levels
Use a spirit level or laser level to ensure an even surface with a gentle fall (1:60 is typical) to allow water runoff.

5. Add a Screed Layer (if needed)
If you're laying slabs or artificial turf, add a layer of sharp sand on top and level it out. This helps with final positioning and drainage.

 

Top Tips for a Strong Sub-Base

• Always compact in layers, never all at once.

• Water an MOT Type 1 slightly before compacting to reduce dust and aid binding.

• Use a geo-textile membrane beneath the sub-base to suppress weeds and improve stability.

• Make sure you plan for adequate drainage, especially in areas prone to heavy rain.

 

FAQs

How do I lay a sub-base for a patio or driveway?

To lay a sub-base, excavate the area to the correct depth, then spread MOT Type 1 aggregate in 50mm layers. Compact each layer with a wacker plate and check levels throughout. Add sharp sand if required for paving or turf. Hire the right tools from Speedy Hire for best results.

What is a sub-base and why do I need one?

A sub-base is a compacted layer of crushed stone or aggregate laid beneath surfaces like patios, driveways, or turf. It prevents shifting, improves drainage, and ensures long-term stability.

What is MOT Type 1?

MOT Type 1 is a crushed aggregate made from limestone or granite, widely used in the UK for sub-bases. It compacts well and is approved for use under roads and driveways.

How deep should a sub-base be?

It depends on the surface:

• Driveways: 100–150mm
• Patios/Paths: 75–100mm
• Artificial Grass: 50–75mm MOT Type 1 + 25–50mm sharp sand

Do I need to compact the sub-base?

Yes. Compaction is critical. Use a wacker plate to compact each layer of aggregate to prevent dips or movement later on.

Can I hire tools for laying a sub-base?

Absolutely. Speedy Hire offers mini diggers, compactor plates, wheelbarrows, and more – everything you need to get the job done right.

 

Hire the Right Tools for the Job

Getting your sub-base right is just as important as the surface itself, and the right tools make a massive difference. Speedy Services offers everything from wacker plates and mini diggers to laser levels, available to hire across the UK for fast, reliable delivery.

Ready to start your project? Hire online today or visit your local Speedy depot to get expert advice and the tools you need to build a solid foundation.