How Wallbarn’s M-Tray® helps manage stormwater, protect drainage systems and support SuDS compliance.

The increasing challenge of stormwater management has placed renewed focus on sustainable drainage solutions. The updated National Standards for Sustainable Drainage Systems, now published on GOV.UK, formally recognise green roofs as a Principle 1 treatment that slows the flow of rainwater and contributes directly to compliant SuDS design.

Wallbarn’s M-Tray® modular green roof system has been developed to meet this need. Designed and manufactured in the UK, M-Tray® combines water attenuation, pollution filtration and ease of installation in a single, pre-grown unit, helping architects and specifiers deliver both performance and sustainability.

Stormwater Attenuation That Saves Money

Each M-Tray® module absorbs and retains rainwater, reducing roof run-off by up to 50 per cent and delaying discharge into outlets by up to an hour. By holding back stormwater, M-Tray® helps mitigate flash flooding, reduce pressure on drainage systems and extend the life of the underlying waterproofing and pipework.

This passive attenuation effect supports SuDS compliance and helps reduce long-term maintenance costs for both the roof and the drainage infrastructure below.

Beyond Water Retention: Pollution and Microplastic Filtration

Independent studies show that green roofs can capture up to 97 per cent of microplastics from rainwater, helping prevent these pollutants from entering urban drainage networks. M-Tray® acts as a natural filtration layer, improving water quality and supporting cleaner, more resilient drainage systems. Learn more about this study

Engineered for Real-World Construction Challenges

Traditional roll-out green roofs involve multiple layers, heavy materials and complex sequencing. M-Tray® arrives pre-grown and ready to place, with no loose substrate or heavy bags to crane to the roof. Installation is clean, fast and safe. The trays are hand-carried into position and simply clipped together, which reduces disruption and health and safety risk.

Ideal for retrofit projects, schools and large commercial schemes with restricted access, the modular design also allows phased installation and future access by lifting individual trays. M-Tray® is a practical, future-proof solution for both new build and refurbishment projects.

Proven Performance and Compliance

• Independently fire tested to BS EN 13501-5 BROOF(t4) by Warrington Fire
• Compatible with a wide range of waterproofing membranes
• Supports BREEAM, BNG and ESG targets
• Sedum and wildflower options to enhance biodiversity
• Trays made from recycled and recyclable polypropylene
• Substrate developed to BS 8616:2019 using recycled mineral aggregates
• Grown in the UK to reduce carbon footprint

Projects such as Turing House School and Crumlin Hospital have demonstrated the M-Tray® system’s value in delivering sustainable, low-maintenance green roofs on challenging sites.

Support from Design to Delivery

Wallbarn supports architects, specifiers and contractors from concept to completion. Technical resources include NBS Source specifications, CAD details, BIM objects and a free estimating service based on scaled drawings.

Our technical team provides guidance on build-ups, logistics and maintenance scheduling to ensure a compliant, efficient installation.

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