What Do You Put Under Block Paving in Exmouth?

Block paving is a highly favoured and durable alternative for driveways, providing both aesthetic appeal and long-term functionality. However, the success of a block paving driveway isn't just about the quality of the blocks themselves—it's also about the materials and layers placed underneath them. These underlying layers provide the required structure, stability, and drainage that prevent sinking, cracking, and other common issues that can arise over time.

In this post, we’ll explore the different layers you should put under block paving driveways, their functions, and how they contribute to a successful, long-lasting installation. You can also find some fantastic illustrations for these topics on the PavingDirect website.

1. Sub-base Layer: The Foundation of Your Driveway

The sub-base is the most important part of a block paver driveway. The primary foundation of this layer provides the necessary load-bearing support to ensure your driveway remains stable and durable, especially under the weight of vehicles. A well-constructed sub-base will prevent future settling or shifting of the surface.

Different Materials for the Sub-base

The material that you select for the sub-base ought to possess a balanced blend of larger stones for strength and finer particles for compaction. The most commonly used materials are:

Type 1 MOT (Department of Transport Specification for Granular Sub-base): Type 1 MOT is the gold standard for a sub-base in block paving. It is made up of a mix of crushed stone and crushed gravel, along with fines to make sure the material compacts properly. This helps the driveway stay stable while allowing for good drainage. Type 1 MOT is highly durable, making it ideal for driveways.

Granular Limestone: Often used as a sub-base material, granular limestone is another good option because of its stability and ability to lock together once compacted.

Crushed Concrete: In some cases, recycled crushed concrete can be used as an environmentally friendly alternative to quarried stone. It's crucial, however, that it is clean and free from contaminants to ensure stability.

Thickness of the Sub-base

Sub-base layer should be at least 100mm thick for a standard domestic driveway. However, this can be increased to 150mm or more, depending on the soil conditions and anticipated vehicle weight. If the soil is particularly soft or prone to movement, such as clay or peat soils, a deeper sub-base may be required.

Compaction

Proper compaction of the sub-base is essential for proper composition. The material should be compacted thoroughly with a mechanical compactor or wacker plate to form a solid foundation. This prevents any shifting or settling once the block paving is laid.

2. Creating a smooth surface for Paving Blocks with Bedding Layer:

The next step is to put on the bedding. This layer makes the paving blocks rest on a smooth, level surface, and it also helps water flow.

Materials for the Bedding Layer Materials.

The bedding layer is typically composed of sharp sand, also known as grit sand, which has angular grains that allow it to interlock and form a solid foundation. Important that the sand be free of clay or silt, as these materials can retain moisture and cause the blocks to shift or sink over time.

Concrete sand, which is finer than sharp sand, can make the surface smoother in some cases. However, sharp sand is generally preferred for its better drainage properties and compaction ability. However, it is generally preferred for its better drainage properties and compaction ability. But it is generally preferred for its better drainage properties and compaction ability.

Thickness of the Bedding Layer

The bedding layer is usually around 25mm to 50mm thick, and is usually around 25mm to 50mm thick. For most domestic driveways, 30mm is the typical thickness. It’s crucial to spread the sand evenly across the surface, and to level it properly before laying the paving blocks. A screed board (a long, flat piece of wood) is often used to level the sand to the correct height, ensuring an even surface.

Leveling the top layer of bedding.

One of the most prevalent errors in block paving is an uneven bedding layer, which can lead to uneven paving blocks. To avoid this, make sure the bedding is level and adjust it if needed. Some installers use a string line or laser level to ensure the bedding layer is perfectly flat.

3. Edge Restraints: Keeping Your Driveway in Order

Edge restraints are a crucial component of any block paving installation, as they aid in maintaining the blocks' stability and preventing their movement under pressure. Over time, the edges of a driveway can suffer from the weight of vehicles or the natural movement of soil. This can cause the blocks to become dislodged. Edge restraints help mitigate this by holding the paving blocks in position.

Materials for Edge Restraints

Concrete Kerbs: One of the most common options for edge restraints, concrete kerbs are strong, durable, and provide a clean, professional finish to the driveway. Additional stability can be achieved by setting them in concrete.

Plastic Restraints: These are a lightweight and flexible option, often used for edging. Excellent control over the edges of the driveway is provided by plastic restraints.

Timber Edging: Sometimes used for aesthetic purposes, timber is a natural, cost-effective material. It may not provide the same level of stability as concrete or plastic options..

Metal Restraints: Galvanized steel or aluminum restraints offer a sleek look and are highly durable, but they can be more expensive.

Edge restraints should be securely fixed in place using a concrete mix or suitable fixing system. They should be installed prior to laying the blocks, ensuring they are level with the surrounding surface.

4. Geotextile Membrane: Preventing Weed Growth and Soil Contamination

Geotextile membranes are highly recommended, especially in areas where the soil conditions are not ideal. While not strictly necessary in all cases, they are highly recommended in areas where the soil conditions are not ideal. A geotextile membrane is a fabric material laid on top of the sub-base before the bedding layer is added.

Geotextile membranes have benefits

Weed Control: One of the primary reasons for using a geotextile membrane is to reduce weed growth. The membrane acts as a barrier, preventing weeds from pushing up through the gaps between the paving blocks. While the membrane doesn’t completely stop weeds, it significantly reduces the frequency and severity of growth.

Preventing Soil Mixing: The membrane also acts as a barrier to stop the underlying soil from mixing with the sub-base material, preserving the integrity and drainage properties of the base layers.

Improved Drainage: In some cases, a high-quality membrane can even improve water drainage by allowing water to pass through it without the risk of clogging the base layers.

5. Drainage: Ensuring Water Flows Away from Your Driveway

Proper drainage is an often-overlooked aspect of block paving driveways, but it’s crucial for avoiding long-term issues like pooling water or erosion.

There are several key drainage considerations

Your driveway should have a slight slope, typically between 2-5%, to direct water off the surface. This prevents water from pooling on top of the blocks, which can weaken the structure over time.

Permeable Paving: If water drainage is a major concern, particularly in areas with heavy rainfall, you might want to consider using permeable block paving. These blocks let water flow through them and go into the ground below, reducing the amount of water that runs off the surface.

Drainage Channels and Pipes: For driveways on flat ground or in areas prone to poor drainage, installing a drainage system may be necessary. This could include drainage channels along the sides of the driveway or land drains that help direct water to a suitable exit point.

Conclusion: Building a Lasting Block Paving Driveway

Building a block paving driveway is more than just laying down beautiful paving blocks. It's about building a solid foundation that supports those blocks and keeps them in place over time. By investing in high-quality sub-base materials, a well-prepared bedding layer, effective edge restraints, and proper drainage solutions, you’ll ensure that your driveway remains functional, stable, and visually appealing for many years.

Remember, the success of your block paving driveway depends on the preparation, not just the look of the surface. Proper installation is key to creating a driveway that can withstand the test of time and weather.