Wallbarn green roof supports green infrastructure specification

A substantial factory extension in an ecologically sensitive location has been topped off with a ‘significant’ Wallbarn green roof which forms a major component of the scheme’s green infrastructure approach.

Kay Premium Marking Films (KPMF), in the Ebbw River valley, South Wales, is a leading manufacturer of self-adhesive vinyl films for wrapping vehicles. Growth meant it required additional manufacturing and storage space.

The planning application for its multi-million pound 1,200m2-plus factory extension outlined how impact on the existing green infrastructure (GI) was an ‘integral design consideration’ for the project, with the objective to ‘minimise impacts and deliver positive new GI features’ as well as strive to make the building’s roof blend into an adjacent hillside.

For environmental consultants Soltys Brewster, the green roof was a ‘significant’ and a ‘major new GI component of biodiversity benefit, habitat and new nectar source’ for the site.

Spec change

Initially, the roof was specified as a roll-out green roof. However, following concerns raised by the architect about fire safety compliance, the specification was changed to award-winning British manufacturer Wallbarn’s modular M-Tray green roof system, which has passed rigorous physical fire testing and is certified to B Roof(t4) standard, ensuring compliance with all relevant fire regulations.

In supplying modular M-Tray for the project, Wallbarn working closely with liquid roofing specialist Polyroof (which supplied its Protec system as part of a full BUR system on the 10° pitch roof) and Polyroof-approved roofing contractor Haran Roofing.

The complex scheme required high levels of communication and collaboration between all stakeholders given its tight timeframes and the site being a live operational environment, challenges which made M-Tray perfect for the installation, as Polyroof noted: “The modular nature of the system [M-Tray] helped mitigate the complex nature of the project, enabling a much faster, cleaner and easier installation process for the installers.

“Additionally, as the sedum was pre-grown, it presented significant benefits over a roll-out green roof system as the plants were already fully established and mature, being fully rooted into the substrate. This enabled an instant green roof to be achieved, perfectly suiting the client’s strict timeframe.

“The suitability of the modular system was further heightened by its ease of removal without causing damage to the green roof, ensuring sufficient accessibility to the waterproofing membrane below should any future inspection or maintenance be required.

“The finished roof was topped with luscious green roof sedum to provide an aesthetically pleasing result that blends harmoniously with the surrounding environment whilst contributing to increased biodiversity,” added Polyroof.

Complete

M-Tray is a complete green roof system in a box - all components of a roll-out system cleverly engineered into 500mm x 500mm cassettes that can be carried by hand on site and clicked into place. Drainage is designed in and the 100mm deep substrate has been developed with horticultural experts to balance long-term nourishment, moisture retention, optimum weight, precise organic matter content, chemical composition and particle size to ensure plant roots have sufficient air but the substrate does not drain too easily.