UGR Green Roof Border Pebbles – 20kg Bags

Create an attractive border around your green roof

UGR Green Roof Border Pebbles provide a decorative and practical finish around the perimeter of a living roof.

The colourful beach pebbles can also be positioned around skylights, drainage outlets and other roof features where a clear separation from the vegetation and growing substrate is required.

Supplied in manageable 20kg bags, they are suitable for domestic green roofs as well as larger extensive or intensive systems.

Why use pebbles on a green roof?

A correctly positioned pebble border can offer several practical benefits:

• Helps keep growing medium and vegetation away from roof edges
• Reduces the risk of loose material reaching and blocking gutters
• Keeps vegetation clear of drainage outlets and other penetrations
• Can help reduce wind exposure at the edge of the green roof build-up
• Can form part of a specified fire-break detail
• Creates access routes through larger roofs that require maintenance
• Adds an attractive contrast to sedum, wildflowers and other planting

Pebble borders can also be used to divide planted areas or create decorative features within the roof layout.

Available quantities

Choose from four quantities, each supplied in individual 20kg bags:

• 10 bags: 200kg total
• 20 bags: 400kg total
• 30 bags: 600kg total
• 40 bags: 800kg total

Each 20kg bag covers approximately one linear metre when forming a border around 150mm wide. Actual coverage will depend on the required depth, the size and arrangement of the pebbles and the finished appearance you want to achieve. A deeper or fuller border will require additional bags.

How many bags will I need?

Measure the total length of every area that requires a pebble border, including:

• The outer roof perimeter
• Skylights
• Roof outlets and drains
• Ventilation pipes and other penetrations
• Maintenance routes
• Internal divisions between planted areas

As a general guide:

• A 10m border requires approximately 10 bags
• A 20m border requires approximately 20 bags
• A 30m border requires approximately 30 bags
• A 40m border requires approximately 40 bags

These estimates assume a border approximately 150mm wide and are intended as a starting point rather than a guaranteed coverage figure.

Installing green roof border pebbles

The pebbles should be installed over a suitable filter layer so that small particles and fines cannot enter and obstruct the drainage system.

1. Complete the waterproofing, protection and drainage layers required by the green roof design.
2. Confirm that a suitable geotextile or bonded filter layer is present beneath the proposed pebble areas.
3. Position the edge trim and other perimeter components where required.
4. Mark out a border approximately 150mm wide around the roof perimeter, outlets and penetrations.
5. Carefully distribute the pebbles to the required depth without damaging the membranes beneath.
6. Install the growing substrate alongside the completed border.
7. Keep outlets and drainage openings visible and free from obstruction.

Some installations use a separate filter fleece extending from the drainage layer towards the waterproofing, with the pebbles positioned above it. This is acceptable where the fleece forms a suitable continuous filter layer.

For a neat separation between the pebbles and growing substrate, use the UGR Aluminium Green Roof Edge Trim – 1m.

Important design considerations

Pebbles can contribute to wind, fire and maintenance details, but they should not be treated as a substitute for a properly designed wind-uplift restraint, fire-protection strategy or access system.

The roof structure must also be capable of supporting the combined saturated weight of the complete green roof build-up, including the selected quantity of pebbles.