How Deep Should a Sub-Base Be for Paving Slabs?

The thickness of paving slabs is an important factor to consider when planning any kind of outdoor patio or pathway project. While the actual thickness of the pavers themselves may vary, it’s generally recommended to use slabs that are about 3- to 3 1/2-inches thick. In order to ensure a stable and long-lasting surface, it’s necessary to dig a sub-base depth of about 9 inches (22.86 cm) to accommodate any kind of paver. This depth may seem excessive, but it’s necessary to provide a solid foundation and prevent the pavers from sinking or shifting over time. Within this 9-inch depth, approximately 5 inches (12.7 cm) will be filled with the base material, such as sand or gravel, that will help to compact and stabilize the area. It’s important to note that the specific requirements for sub-base depth may vary depending on factors such as soil type, climate, and intended use of the pavement. Consulting with a professional landscaper or contractor can help determine the appropriate sub-base depth for your specific project.

Can You Lay Paving Slabs Without Sub-Base?

Can you lay paving slabs without a sub-base? A sub-base acts as a foundation for the paving, distributing the weight evenly and providing a solid base for the slabs to rest on.

A sub-base helps to distribute this weight evenly, preventing any potential damage to the slabs or the ground below.

This allows room for the sub-base material to be added, usually a combination of crushed stone, sand, or gravel. The sub-base should be compacted and leveled to ensure a smooth and stable surface.

The depth of the sub-base will depend on various factors such as the type of paving slabs, the intended use, and the climate conditions in your area. In general, a sub-base should be at least 100mm thick for light pedestrian use and up to 200mm or more for heavy vehicular use.

Remember, the quality of the sub-base is crucial for the longevity and stability of your paving. It’s always recommended to consult with a professional or do thorough research to determine the specific requirements for your project.

It provides stability, distributes weight evenly, and prevents sinking or shifting.

When it comes to the base of a paver driveway, most driveway pavers have a minimum thickness of approximately 2 3/4 inches. These pavers are typically made from a mixture of concrete and coloring agent, and they’re commonly used as exterior flooring. In order to properly install these pavers, they should be placed over a compacted sub-base of class 2 road base, which should have a minimum thickness of four to six inches.

How Thick Is the Base of a Paver Driveway?

When it comes to the base of a paver driveway, it’s important to consider it’s thickness. This thickness is crucial for ensuring the durability and longevity of the paving slabs.

To ensure a solid foundation for the paver driveway, it should be installed over a sub-base of class 2 road base. This sub-base should have a minimum thickness of four to six inches. The road base provides stability and support for the paver installation, preventing sinking or shifting over time.

The sub-base is typically made up of compacted gravel or crushed stone. This material is carefully leveled and compacted to create a solid base for the pavers. By using a class 2 road base, which is made up of a mix of larger and smaller stones, the sub-base can achieve optimal stability and drainage.

Proper compaction of the sub-base is crucial to ensure it’s effectiveness. This process involves using compacting machinery to compress the material and remove any air voids. A well-compacted sub-base provides a solid and stable foundation for the paver driveway, minimizing the risk of cracks or unevenness in the paving slabs.

It’s also important to note that the thickness of the base may vary depending on the specific requirements of the project. Factors such as the soil conditions, climate, and intended use of the driveway can influence the recommended thickness. In some cases, an engineer or paving professional may need to assess the site and provide specific guidelines for the base thickness.

By following the recommended guidelines and properly preparing the sub-base, you can ensure a sturdy and long-lasting paver driveway. Investing in a solid foundation won’t only enhance the aesthetics of your driveway but also minimize future maintenance and repairs.

How to Properly Level and Compact the Sub-Base for a Paver Driveway

When it comes to laying paving slabs for a driveway, preparing the sub-base is crucial for a long-lasting and stable surface. The first step is to excavate the area to the required depth, which will depend on the specific project and type of soil. Typically, a sub-base depth of around 6-8 inches is recommended.

Once excavated, the sub-base needs to be properly leveled and compacted. This can be done using a plate compactor or a mechanical roller to achieve a firm and even surface. It’s essential to make sure there are no soft spots or uneven areas, as these can lead to future problems such as sinking or shifting of the slabs.

Moreover, it’s important to consider proper drainage by creating a slight slope away from any structures or towards designated drainage areas. This will help prevent water accumulation and potential damage to the driveway.

By investing time and effort into leveling and compacting the sub-base correctly, you can ensure a solid foundation for your paving slabs, minimizing the risk of future issues and maximizing the durability and longevity of your driveway.

Source: Driveway Pavers – ALL Masonry & Landscape Supply

When it comes to laying paving slabs, the material you need to put underneath them depends on the type of paving you’re using. For concrete block paving, unbound sharp sand is the recommended choice as it provides a compacted and stable base. On the other hand, natural sandstone requires a moist sharp sand and cement mix, which can accommodate the various shapes and sizes of the paving stones. Ensuring the right foundation is essential for preventing movement and maintaining the durability of your paved area.

What Do I Need to Put Under Paving Slabs?

When it comes to paving slabs, having a proper foundation is crucial to ensure long-lasting stability. The sub-base, which is the layer beneath the paving slabs, plays a key role in distributing the weight evenly and preventing any potential movement. It’s important to choose the right material to place under the slabs, depending on the type of paving project you’re working on.

For concrete block paving, using an unbound sharp sand is recommended. This sand is compacted to create a solid bed that will prevent any movement. The sharp sand provides a stable base for the paving slabs and helps to distribute the weight evenly. It’s important to ensure that the sand is compacted properly to avoid any future sinking or shifting of the slabs.

On the other hand, for natural sandstone paving, a moist sharp sand and cement mix should be used. This mortar mix is more suitable for accommodating the irregular shapes and sizes of sandstone slabs. The mix provides a strong bond between the slabs and helps to maintain their stability over time. It’s important to mix the sand and cement thoroughly and lay the slabs on a smooth, level surface.

In both cases, it’s crucial to properly prepare the base before laying the paving slabs. This involves excavating the area to the required depth and ensuring that the sub-base is well compacted. The thickness of the sub-base will vary depending on the type of project and the load it needs to bear. However, a general rule of thumb is to aim for a minimum depth of 150mm for areas that will be subjected to pedestrian traffic, and a minimum depth of 200mm for areas that will have vehicular traffic.

Choosing the Right Type of Sub-Base Material for Different Paving Projects (e.g. Gravel, Crushed Stone, Concrete, Etc.)

  • Gravel
  • Crushed stone
  • Concrete


In conclusion, when determining the required depth for a sub-base for paving slabs, it’s crucial to consider the thickness of the pavers being used. Most pavers are approximately 3 to 3 1/2 inches thick, thus necessitating a deeper excavation. Out of this depth, 5 inches (12.7 cm) would be filled with the appropriate base material such as sand or gravel. This sizable sub-base depth helps to provide adequate support and prevent any potential issues with sinking or shifting, ensuring a durable and visually appealing paved surface for years to come.

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