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 with the aggregate.

Spread the 20mm Black Basalt chippings evenly over the prepared sub-base to the recommended depth, typically around 40mm to 50mm for borders and footpaths, or 50mm to 75mm for driveways. Rake the chippings to ensure an even distribution across the entire area.

Check the finished surface level and slope to ensure proper drainage away from surrounding structures. Ensure the aggregate 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 is 20mm black basalt?

20mm black basalt is a premium, hard-wearing decorative aggregate made from crushed volcanic rock. It features sharp, angular stones with a deep charcoal to jet-black colour.

What is 20mm black basalt used for?

Black basalt is popular for contemporary garden borders, driveways, footpaths, rockeries, and plant toppers. Its bold, dark colour provides a striking contrast against green foliage and lighter paving.

Is 20mm black basalt suitable for driveways?

Yes. Basalt is an extremely dense, tough rock that resists crushing. At 20mm, the angular pieces interlock firmly under vehicle weight, creating a durable, non-slip driving surface that stays in place.

How does the appearance of black basalt change when wet?

When dry, black basalt presents a sophisticated mid-grey to dark charcoal matte finish. When wet, the colour deepens dramatically into an intense, glossy jet-black.

Are black basalt chippings fish-friendly?

Yes. Basalt is an inert, natural igneous rock that does not leach minerals or alter water pH levels. It is completely safe for fish ponds, streams, and decorative water features (rinsing off quarry dust beforehand is recommended).

Will 20mm black basalt fade in the sun?

No. Unlike artificial or dyed stones, the dark colour of natural basalt is permanent and UV-stable, meaning it will not bleach, fade, or weather over time.