As an approximate guide, one bulk bag will cover:

• 10–12m² at a depth of 50mm

• 6.5–7.5m² at a depth of 75mm

• 5–6m² at a depth of 100mm

Garden borders, rockeries, and footpaths commonly require around 40mm to 50mm of decorative chippings, while domestic driveways typically require approximately 50mm to 75mm depending on the ground conditions and sub-base.

These figures are estimates only. Actual coverage will vary according to the bag weight, ground conditions, compaction and the accuracy of the excavation.

Not sure how many bags you require? Call our Rugby team on 01788 866945 with the length, width and required depth.

20mm Celtic Green decorative chippings are intended as a decorative surface, border, or driveway topping. Colour, natural subtle sparkled texture, and angular shape can vary according to the source of the stone.

You can use our online calculator at https://www.melbros.com/calculator

Excavate the area to the required depth and prepare the ground appropriately. A suitable geotextile membrane may be required to prevent weed growth and stop the subgrade from mixing.

Spread evenly over the prepared sub-base to the recommended depth. Rake or lay by hand to ensure an even, flat distribution across the entire area.

Check the finished surface level and slope to ensure proper drainage away from surrounding structures. Ensure the depth is consistent to prevent exposed patches or uneven surface layers.

Requirements vary according to ground conditions, loading, and the intended use of the surface. Follow the project specification or seek professional advice where appropriate.

Available for collection from our Rugby branch or local delivery using our own fleet.

Bulk bags will normally be delivered by a crane-equipped lorry. Delivery is kerbside and the final offloading position is always subject to safe access and the driver’s discretion.

Please tell us before delivery about:

• Narrow roads or restricted entrances
• Parked vehicles or limited turning space
• Overhead cables, trees or other obstructions
• Soft, sloping or unsuitable ground
• Any other access concerns

Enter your postcode on the product page to check your delivery area. We’ll confirm the delivery date after your order is placed.

What colors are featured in 20mm Celtic Green Slate Chippings?

Celtic Green Slate displays a subtle mix of natural sage green, soft grey, and occasional pale blue undertones. When dry, it features a muted, earthy matte appearance that blends smoothly into natural landscapes. When wet, the stones transform into a deep, glossy emerald-grey that brings dynamic contrast to surrounding foliage and paving.

What are the recommended uses for 20mm Celtic Green Slate?

This 20mm sizing is exceptionally versatile, making it a popular choice for garden pathways, flower borders, rockeries, alpine beds, and surrounding modern patio slabs. Because slate chippings are naturally flat and angular, they lie smooth underfoot while maintaining a neat, structured surface.

Are Celtic Green Slate Chippings fish-friendly for ponds and water features?

Yes, natural slate is completely inert and will not alter the pH balance of water. Celtic Green Slate is entirely fish-friendly and safe for aquatic life, making it an excellent choice for lining pond margins, streams, and decorative water cascades. Rinsing the chippings with clean water before installation is recommended to wash away fine transit dust.

Can 20mm Celtic Green Slate be used on a driveway?

Slate chippings are generally not advised for vehicle driveways. Under the heavy, repeated weight of cars, flat slate pieces tend to crack and break down into smaller fragments over time. Harder, crushed rock types like basalt or granite are better for driveways, leaving Celtic Green Slate best suited for footpaths and decorative ground cover.

How does Celtic Green Slate assist with weed prevention and plant health?

When installed over a quality geotextile landscape membrane, the flat interlocking stones block sunlight from reaching the soil, severely limiting weed growth. The slate layer also functions as a protective mulch, preventing rapid soil drying during hot weather and protecting plant roots from extreme frost in winter.