20mm Grey Slate Chippings

Natural 20mm Grey Slate Chippings are a versatile decorative aggregate with distinctive grey, charcoal and subtle grey tones with some having pieces of iron. The colour deepens when wet, making the slate particularly effective around planting, pathways, rockeries and water features.

The naturally flat, angular pieces settle together to create a textured, practical surface and can also be used in suitable driveway areas when laid over a correctly prepared sub-base.

Available in a choice of pack sizes, our Welsh grey slate can be ordered as an approximately 850kg bulk bag or in convenient 20kg Maxi Bags, with options of approximately 200kg, 400kg or 1000kg. This makes it easy to choose the right quantity for everything from smaller garden borders to larger landscaping projects.

Garden Borders
Use plum slate around shrubs, grasses and planted beds to create a clean decorative finish while covering exposed soil. A suitable weed-control membrane can be installed beneath the stone where required.

Paths & Walkways
The relatively flat shape of 20mm slate makes it a popular choice for decorative paths and walkways, where the pieces naturally settle together underfoot.

Driveways & Landscaping
20mm plum slate can be used in suitable driveway and landscaping areas when installed over a properly prepared and compacted sub-base.

One of the most distinctive features of plum slate is the change in appearance when wet. When dry, the stone has softer plum, purple and grey tones. Rain or water deepens the colour, bringing out richer shades of plum and purple.

This makes 20mm plum slate particularly attractive around water features, garden planting and areas where the natural colour variation can become part of the design.

The amount of 20mm Plum Slate Chippings you need will depend on the size of your area and the depth at which the slate is laid.

As a guide, at a depth of approximately 50mm, typical coverage is:

1 × 20kg Maxi Bag – approx. 0.24m²
10 × 20kg Maxi Bags (200kg) – approx. 2.4m²
20 × 20kg Maxi Bags (400kg) – approx. 4.7m²
850kg Bulk Bag – approx. 10m²
50 × 20kg Maxi Bags (1000kg) – approx. 11.8m²

A depth of around 50mm is recommended for paths and areas with higher foot traffic. For decorative garden borders and planted areas where a shallower depth is suitable, an approximately 850kg bulk bag may cover around 13–15m².

To calculate the size of your area:

Length × Width = Area in m²

For example, an area measuring 5m × 2m = 10m², so approximately one 850kg bulk bag would typically be required when laid at around 50mm depth.

Use our coverage calculator above to estimate the amount of 20mm Plum Slate required for your area and choose the pack size that best suits your project.

Coverage figures are approximate and can vary depending on ground conditions, compaction, natural stone size variation and the finished depth required.

For larger or more complex projects, send us your measurements and we can help estimate the quantity of slate required.

Our 20mm Plum Slate Chippings are available in a choice of pack sizes to suit different garden and landscaping projects:

10 × 20kg Maxi Bags – approx. 200kg
Ideal for smaller borders, planted areas and lighter landscaping projects.

20 × 20kg Maxi Bags – approx. 400kg
A practical mid-size option for medium-sized paths, borders and garden projects.

850kg Bulk Bag – approx. 850kg
Our most popular option for larger garden and landscaping projects.

50 × 20kg Maxi Bags – approx. 1000kg
A convenient larger-volume option where individually packed 20kg bags are preferred.

As slate is a natural quarried material, individual pieces vary in size, thickness, shape, markings and colour. Pack weights may also vary slightly due to moisture content and the natural characteristics of the stone.

Our 20mm Plum Slate Chippings are a natural Welsh slate, selected for their distinctive plum, purple and subtle grey colouring.

Slate is a naturally quarried material, so variations in colour, markings, thickness, shape and size are an inherent part of the stone and give every landscaping project its own individual character.

The naturally flat structure of Welsh slate allows the chippings to settle together well, making them particularly suited to garden borders, pathways, rockeries, landscaping and suitable driveway areas.

Natural quarry dust may be present when the slate is delivered. Rinsing the chippings after installation, or allowing rainfall to wash them naturally, will reveal the richer plum and purple tones of the stone.

1. Clear the area of existing vegetation and debris.
2. Prepare and level the ground.
3. Install a suitable weed-control membrane where appropriate.
4. For driveways, construct a suitable compacted sub-base before laying the decorative slate.
5. Spread the slate evenly to your required depth.
6. Rinse the slate after installation if required to remove quarry dust and reveal the natural colouring.
   
   

20mm plum slate creates a finer, more compact finish and is particularly suited to paths, driveways and general garden landscaping. If you’re deciding between the two sizes, read our 20mm vs 40mm Plum Slate Chippings guide to compare their appearance, uses and recommended applications.

Looking for a different colour or size? Explore our full Slate Chippings collection, featuring natural plum, grey and green slate in 20mm and 40mm options.