South West London School – Wildflower Modular Green Roof with M-Tray®

As part of a major new-build school development in South West London, Wallbarn supplied over 1,500m² of M-Tray® wildflower green roof. This large-scale installation marked a shift from the smaller domestic and retrofit applications commonly associated with modular green roof systems, showcasing M-Tray®’s performance on complex new-build schemes.

The roof consisted of multiple levels with a variety of obstructions, including plant services, ducts, and angled parapets. Wallbarn collaborated closely with main contractor Bowmer & Kirkland and landscaping contractor Kingston Landscapes to develop a solution that provided both protection for the single ply waterproofing membrane and a range of environmental benefits in line with BREEAM considerations. The green roof was also designed to serve as a potential outdoor learning space for pupils.

The M-Tray® wildflower system was chosen for its maturity, ease of installation, and ability to deliver a finished, healthy green roof under tight programme constraints. Delivered on pallets in pre-grown modules, each articulated load of over 600m² was offloaded and positioned for hoisting onto the roof in a matter of hours using a large cherry picker and heavy-duty forklift. The modular format meant that installation could begin immediately, reducing the time the vegetation spent stacked and ensuring optimum plant health on delivery.

Each 500 x 500 mm tray clicks into place to create a seamless surface of sedum, herbs, and native wildflowers. Even during the late-season installation, flowering plants attracted pollinators to the roof. PV panels were also incorporated into the design, with M-Trays installed around the base of the units to improve the building’s overall sustainability. The modular format made it easy to access panel wiring or services when required—an advantage over traditional roll-out green roofs.

By spring 2022, the green roof had matured into a lush, self-sustaining ecosystem, softening what would otherwise have been a large expanse of exposed roofing. The system now provides thermal protection, acoustic benefits, biodiversity value, and a striking visual contrast to the surrounding urban environment. Feedback from the contractor, landscaping team, and the school’s leadership has been overwhelmingly positive—and the roof is now a key feature of this forward-thinking educational facility.