Subbase 40mm
£10.00 + VAT per Tonne
40mm to Dust Slate Aggregate – Ideal for Sub-base Applications
Our 40mm to dust slate aggregate is a fantastic sub-base material, screened to a 40mm to dust grade for reliable compaction. When compressed, the 40mm subbase binds tightly, forming a solid, stable base that is perfect for a wide range of landscaping and construction applications.
Commonly referred to as 40mm scalping’s, this material is a by-product of our slate walling stone production, making it not only a sustainable choice but also a cost-effective solution for groundwork preparation. It’s ideal for use beneath paving slabs, decorative gravel, chippings, driveways, patios, and garden paths—anywhere a firm, load-bearing base is required.
With its excellent compaction properties and natural slate composition, this 40mm subbase aggregate offers a practical, long-lasting foundation.
Key Features:
- Sustainable and eco-friendly – made from slate by-product
- Perfect for use as a sub-base for paving, gravel, or decorative chippings
- Cost-effective alternative to primary aggregates
- Suitable for both domestic and commercial projects
Whether you’re preparing for a garden landscaping project or laying the foundation for driveways and paths, our slate aggregate offers both functionality and value.
Prices + VAT
While our 40mm sub-base does not meet the exact specification of an MOT Type 803 product, it can serve as a cost-effective alternative for applications where strict compliance with 803 standards is not essential.
Please note, this material is not recommended for use as a finished surface, but is ideal for forming a solid base layer.
For more information or to discuss specific project requirements, please don’t hesitate to get in touch with our team—we’re happy to help.
Preparing the Ground for Your Project – Sub-grade, Sub-base & Bedding Layers
Proper ground preparation is essential to the long-term success of any paving or landscaping project. Below is a step-by-step guide to help you get the foundation right.
Sub-grade (Ground Surface)
The sub-grade is the natural earth surface on which your project will be constructed. Begin by removing the topsoil to expose a stable and firm base. Be sure to eliminate any organic matter, such as roots or vegetation, as these can decompose and cause instability over time.
Topsoil depth can vary, typically ranging from 100mm to 275mm. Once removed, the exposed sub-grade should be reasonably level and flat. For added stability and to prevent the sub-base from mixing with the soil below, we recommend laying a layer of Terram geotextile fabric over the sub-grade.
Sub-base Layer
Next, install the sub-base, which provides a strong, load-bearing foundation for the surface layers above. This layer should consist of a well-graded aggregate (various particle sizes) that compacts tightly to form a durable base.
Recommended Sub-base Depths:
- Minimum 75mm for areas with pedestrian traffic
- 100mm to 125mm for domestic driveways or areas with light vehicular use
The sub-base must be thoroughly compacted using a vibrating roller or wacker plate. After compaction, the surface should be level, with a tolerance of no more than ±10mm.
Bedding Layer
The bedding layer sits on top of the compacted sub-base and provides support for your paving slabs or surfacing material. The thickness and specification of the bedding layer will vary depending on the expected load and paving type. Getting this right is critical to ensure even support and long-term durability.
For more in depth laying information check out the Paving Expert Website
Please contact us for local delivery in Cornwall & Devon. All products are available for mainland UK delivery only (excluding some aggregates). We can deliver all across the UK, usually within 72 hours (stock dependent). Please contact us for an accurate delivery price.
Responsibly sourced from our Cornish quarry, our slate supports local craftsmanship while keeping environmental impact to a minimum. As a by-product of our walling and facing stone production, it offers a highly cost-effective and environmentally conscious choice.
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Our in-house experts, including a qualified geologist, can assist with matching and technical guidance. Trust us to source and deliver the perfect stone for your project.