Wallbarn Modular Green Roof M-Tray® - Crumlin, South Wales

This 1,200m² green roof installation in Crumlin was delivered in partnership with Polyroof / Roberts Manufacturing. Initially specified as a rollout system, the architect revised the specification in favour of Wallbarn’s M-Tray® modular green roof after concerns were raised regarding fire compliance. M-Tray® is physically tested and certified to B Roof(t4), ensuring compliance with fire safety requirements for flat and pitched roofs.

Key benefits of the M-Tray® system included faster installation times and futureproofing: trays can be lifted individually for maintenance without disturbing the surrounding area. These features were particularly important given the scale and complexity of the pitched roof.

To manage structural loading, Wallbarn advised the use of parapet walls and horizontal battens to prevent slumping or stress at the roof edges. These details were incorporated and sealed using Polyroof’s Protec liquid-applied waterproofing system, preserving the membrane’s integrity.

With no dedicated loading bay and restricted access on site, delivery logistics were a critical part of project planning. Over 5,000 M-Tray® units were delivered across four weeks, with batches of 640 trays transported three times a week. Wallbarn’s logistics team worked closely with Haran Roofing, Polyroof and transport providers to ensure seamless, staged deliveries.

This project demonstrated the versatility and reliability of the M-Tray® system, meeting structural, environmental and regulatory demands while delivering a high-quality finish. It has since been nominated for multiple industry awards.