GRO member and award-winning green roof manufacturer Wallbarn has applied its many years of experience to producing their product M-Tray®. Walbarn combines the key elements of successful living roofs to produce a system that perfectly balances the right depth and composition of growing medium with the ideal vegetation and optimal level of drainage/absorbency.

M-Tray® achieves all of the above with the added bonus of being modular, delivering established green roofs that are quick, easy and clean to install in the tightest of spaces and reduces the chance of specifier or installer error. The modular approach offers an additional benefit unmatched by roll-out systems, the ability to lift any section of the M-Tray® green roof should access be required to the roof deck.

“Our clients really value the fact that all the variables have been designed out for them,” said Wallbarn Director Julian Thurbin. “Project managers simply need to ensure a watertight flat roof (up to 10° pitch), lay our geotextile fabric and then place the 500mm x 500mm M-Tray® cassettes onto the roof and click together; everything required for a successful and sustainable green roof is contained within the cassettes, delivering a long-lasting, beautiful instant green roof.”

“For many customers this is a major selling point,” added Julian. “If a problem arises with the roof deck or works are scheduled that require access to it, the M-Tray® cassettes are simple to lift and equally simple to re-lay, giving deck access in minutes. This is an especially important feature if large areas of a green roof need removing to identify where the deck problem lies. Each M-Tray® cassette is a one-man lift."

Wallbarn is the pioneer of modular green roof systems in the UK and has seen how simplifying the installation process can open up the market for more people to enjoy the many benefits of living roofs. Its market-leading, award-winning M-Tray® system is installed on hotels, homes, holiday villages, commercial premises and even garden rooms and bicycle stores, showing its versatility and widespread appeal.

In developing M-Tray®, Wallbarn identified four areas key to the long-lasting success of a modular system, as Julian explained: “We have a reputation built over 40 years for providing high-quality, market-leading construction solutions and were very clear from the start that we would only bring a modular green roof to market if it performed long-term,” said Julian. “Key to this were the tray design, substrate, plants and water management.”

The appliance of science has informed and directed Wallbarn in all four areas, perhaps most critically in achieving the perfect growing medium, which can make or break the success of a green roof. Wallbarn believes the substrate should be at least 100mm deep to properly nourish its sedum and native British wildflower vegetation mixes and have the ability to slowly release nutrients to support plants long-term.

Achieving the perfect substrate takes into account the long-term nourishment, percentage of organic matter, appropriate moisture retention/drainage and optimum weight. Consideration must also be given to chemical composition, PH values and the size of particles within the substrate to ensure roots have sufficient air but the substrate does not drain too easily.

Wallbarn has worked with horticultural experts to develop and refine its substrate, testing it at its nursery in Hampshire and through an industry recognised, independent test house over the course of a year to ensure it offers the best combination of nutrients, growing conditions, moisture retention, weight, environmental credentials etc. It has moved away from brick based aggregate mixes towards horticultural solutions whilst taking into account recommendations and limits on organics and other ingredients as laid out in BS 8616 & the GRO Code.

The result is a deep growing medium that balances optimum levels of nutrients and aeration supported by suitable drainage. The substrate is environmentally friendly, being peat free, and utilises coir (a waste product from the coconut industry), green compost and recycled lightweight aggregate.