However, to ensure your patio area looks polished and remains durable and stable, you’ll need the right sub-base material. You can’t just throw any old base down and hope it holds up.

That’s where we come in. Choosing the best sub-base for your patio will ensure your patio tiles or slabs can withstand heavy foot traffic, high winds, heavy rain, and general wear and tear.

So, stick with us as we break down the choice for your patio, helping you transform a grassy lawn into a beautiful lounge area or driveway.

What is a sub-base for a patio?

Think of a patio sub-base as the foundational framework of a house—you can’t see it, but it holds everything together.

It supports your patio slabs, making sure they remain strong and resilient by preventing settling, shifting, and cracking. Without a solid sub-base, even the highest-quality paving stones could shift or crack over time.

The benefits of using a sub-base

Improves drainage: The UK is prone to wet weather conditions and heavy winds, so you need something that can keep up. A sub-base acts as a defence against moisture damage, preventing issues like erosion, mould growth, and frost damage from water pooling.
Provides stability and support: Without a sub-base, your patio tiles would have no reliable surface to rest on; it distributes the weight across a patio area, preventing sinking, shifting, or cracking over time. This prevents structural issues down the line.
Increases longevity: A compatible sub-base that is properly compacted makes any patio better equipped to handle harsh forces, foot traffic, and shifting soil conditions. It can also prevent weeds or plants from growing through, keeping your patio looking neat.
Creates a level and even surface: If the ground is uneven or poorly compacted, your patio will be bumpy, with slabs sticking out. A sub-base helps to level out any irregularities in the ground, ensuring that your patio surface remains smooth and properly aligned.

Key factors to consider: the different types of sub-base

When it comes to choosing the best sub-base for a patio area, there are a few factors you need to take into account.

1. Soil type

Different soil types require different types of sub-bases, as they have varying levels of compaction, drainage, and stability.

Clay soils: These can become compacted easily and retain moisture, which can lead to shifting or cracking when freeze-thaw cycles occur. For this, use a more robust sub-base material like MOT Type 1.
Sandy soils: This requires extra compaction to prevent shifting, but it has better drainage. Use a shallower sub-base like crushed stone or gravel for sandy soils to create a more stable surface.
Loamy soils: The perfect mix between sandy and clay soils, loamy soils offer good drainage and stability. A thinner layer of sub-base may be best, but consult a professional beforehand as the soil structure can vary.

2. Load requirements

Determine whether you’ll be using your patio to place heavy furniture, store a car, and how often it’ll be used.

For heavy traffic: Walkways or lounge areas will need a thicker and stronger sub-base, such as MOT Type 1 or crushed stone.
For light use: If you don’t use your garden often or you only have light outdoor furniture, a less substantial sub-base, like gravel or sharp sand, may suffice (remember to ensure proper compaction for even weight distribution).
For heavy furniture or vehicles: For gardens with sheds, large furniture, or driveways, crushed stone or gravel mixed with a reinforced material must be used for your sub-base to ensure the patio doesn’t compress under pressure.

3. Climate and seasonal changes

Patios can shift and deteriorate under certain climates and weather conditions, so you need to understand how the sub-base will handle temperature fluctuations and freeze-thaw cycles.

Cold climates: We get many harsh and cold winters in the UK, which can cause water in the sub-base material to freeze, expand, and frost. To prevent this, install frost-resistant materials like gravel or crushed stone for your sub-base.
Mild climates: Frost heave is less of a concern in milder climates, but good drainage is still essential to prevent cracking and erosion. For this, a solid sub-base like MOT Type 1 is essential.
Drought-prone areas: If you live somewhere that doesn’t get much rain, a more stable sub-base like crushed concrete or a tightly compacted crushed stone will help prevent contracting, cracking, and settling.

4. Water drainage and drainage systems

Water pooling can cause many issues for your garden, so you want a sub-base that can prevent the worst from happening. If water isn’t allowed to travel away from the patio, you’ll end up with cracked and eroded tiles.

Natural drainage: For gardens with sloped terrain, a simple sub-base like gravel and crushed stone will help prevent water pooling and collecting on the surface.
Poor drainage: For patios in low-lying areas, extra precautions are needed to encourage water runoff. Aim for a proper slope (typically 1:80) and add a thick sub-base with a layer of geotextile fabric underneath to improve drainage.
Drainage systems: If your garden is prone to flooding, install a drainage system to divert water away from the patio area.

5. Cost and availability

We can only work with the budget we have, and you want to make sure you get the best for your money.

Budget materials: If you’re aiming for something that is both low cost and effective, then opt for gravel or sharp sand. These are perfect for smaller DIY projects and are easy to source, offering good support and drainage.
Premium options: For landscapers and builders working on a professional project, MOT Type 1 or recycled concrete aggregate are more expensive, but they are worth the investment for their superior compaction and long-lasting properties.

How deep should the sub-base be?

A general rule of thumb is to aim for a depth of around 100mm to 150mm. However, the depth of your sub-base will depend on how much material is used, the conditions of your soil, and the intended use of your patio.

If you’re expecting heavy foot traffic in your garden, then you may want to increase the depth of your sub-base for better stability. A smaller sub-base depth will suffice for small, decorative patios. Always remember to take compaction into account, as the base will settle a bit after compaction.

Get started on your patio with beesley and fildes

If you’re renovating or creating a brand-new patio area, then we’re here to help you get the job done.

At Beesley and Fildes, we offer a range of beautiful patio and paving slabs to add beauty and durability to any garden. We also provide a wide range of sub-base materials to make sure your investment goes a long way.

Browse our landscaping range today for unbeatable prices and quality.