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    Green roofs

    M-Tray® Bee Bus Stop in Brighton

    Retro-greening the public realm

    There is an incredible opportunity to retrofit green roofs on potentially millions of square metres of flat space in urban settings to bring enormous benefits to both the local environmental and to the structure they cover.

    Invented by its Director Julian Thurbin, Wallbarn has a vision to overlay lost or forgotten surfaces in the public realm with natural and sustainable solutions so we can, bit by bit, reclaim nature in the high density urban landscape to improve the environment and help the planet.

    Because M-Tray® is modular and pre-grown, it is particularly ideal for retrofitting on existing structures. It creates and instant, mature green roof and is easy to estimate and easy to install.

    M-Tray® Bee Bus Stop in Cardiff

    Green roofs absorb rainwater, alleviating storm run-off into drainage systems. They absorb dust, soot and other pollution from the air. They cool flat surfaces by absorbing heat from the sun instead of radiating it back into the atmosphere. They reduce ambient temperature and mitigate the Urban Heat Island Effect. They protect the surface of the structure they dress and of course they attract wildlife as well as being far more attractive that what they are covering.

    It is estimated that there are nearly 400,000 bus stops and bus shelters in UK. As well as bus shelters there are thousands of train station roofs, carpark decks, overpasses, substation roofs and a myriad of other concrete flat surfaces which are prime sites for green roofs and living walls.

    Imagine the environmental benefit across cities and across the planet if we could turn the grey and black hard surfaces that surround us into soft, beautiful, living areas. M-Tray® is our attempt to help with this crusade.

    Unique Design

    Unique Design


    • Module measures 500 x 500 x 100mm
    • 4 x units make up exactly 1sq metre making  estimating far easier
    • Carefully spaced drainage holes ensure modules retain water for longer, allowing plants to absorb more rainfall, increasing attenuation and delaying discharge into outlets
    • Design ensures even greater water retention at edges of module, preventing sedum from dying back at the edges.
    • Stronger plant growth at the edges creates a more seamless layer of vegetation when the modules are connected
    • Four gently ridged hand grips are positioned to enable installers to carry each module easier


    Smooth edges & connecting bracket

    • The connecting brackets are designed to give a tight connection, with the minimum gap between each module
    • The joint is only 6mm so the plants will grow over it quickly, making it disappear in ultra-quick time
    • The corners of the modules are rounded and smooth, so no sharp edges (which might puncture the membrane beneath) are present – this also makes handling the trays easier and the edges can be mounted onto Wallbarn pedestals if additional height is required


    Trims & Edging

    100mm aluminium edge trims and connectors fit neatly onto the sides of the modules. Fixings are designed to slot together neatly although they are not always necessary.



    Access to your green roof is futureproofed.

    If there are problems with the deck beneath or inspection is required, one M-Tray® or section can easily be lifted out without disruption to the whole roof, unlike roll-out which often involves the removal of tonnes of soil and vegetation, which then would need to be replaced at an additional cost to the client.



    What is a green roof?

    Sedum or other succulent plants grown into low-level substrates for construction on flat roofs and podium decks.

    What is a modular green roof?

    An instant green roof, pre-grown at our farm in specially designed cassettes. They can be hand-carried and click together to form a seamless green roof. They are lifted into place and can be easily removed to give access to the deck.

    What are the advantages of a modular green roof?

    Speed of installation; accessibility; less mess and disruption; instant results; future proofing

    What is the cost of an M-Tray®?

    • M-Trays┬«= ┬ú88 per sqm (4 Trays to a sqm – ┬ú22.00 each)
    • Available in Sedum or Sedum/Wildflower Mix (┬ú22 each, ┬ú88 per sqm)
    • Approx. ┬ú75/pallet (32 trays) * transport charges subject to short term changes ÔÇô please ask for current quotation
    • Geotextile fleece = ┬ú1.25m┬▓
    • Riverstone washed pebbles – POA

    All prices are subject to alteration.

    Where are the M-Trays grown?

    At our farm near Basingstoke, Hampshire

    How big is the tray?

    500mm x 500mm x 100mm deep

    How many units per m┬▓?

    4 x modules

    How much do the units weigh?

    100kgs/m┬▓ – we recommend that you consult an Engineer to advise on loadings (120 kg/m┬▓ saturated)

    What is the vegetation?

    The vegetation is a mix of 11 x Sedum species. We also have a Wildflower/Sedum mix available upon request.

    Can I walk on the trays?

    The modules are not designed for foot traffic but can tolerate being stepped on for maintenance purposes.

    Can M-Tray® grow in partial shade?

    Yes, however, like any living plant, an element of light is required.

    Do I need to have any design?

    No. However we can produce a layout guide along with estimates for trays, geotextile fleece and border pebbling if required.

    Are there any requirements?

    Yes. Fire regulations require a hard border between vegetation and the walls of buildings as well as around features such as roof lights and fall arrests (consult GRO code for more details)

    Is there a full cover of vegetation?

    Our M-Trays® have been grown at our farm for several months prior to delivery. They will arrive with a minimum 90% cover.

    How much is delivery?

    From £80.00 per pallet (max 32 units/pallet). NB The M-Trays® need to be removed from the pallet immediately. Pebbling and geotextile fleece can be delivered separately.

    Does the area have to be level?

    M-Tray® can be laid on a level area and on a slope up to 15°. Ideally, we recommend not going above 10°.

    Do they need maintenance?

    The sedum is very hardy and will tolerate extreme conditions. Watering the sedum in extreme conditions is advisable and we can supply an irrigation kit if required.

    At the end of Summer and end of Winter we recommend taking time to remove any dead leaves and vegetation that have accumulated.

    Application of a slow release fertiliser is advisable at certain times of the year.

    Do I need irrigation?

    For best year-round results we do recommend installing an irrigation system although this is not absolutely necessary.

    What other materials will I need to buy along with my M-Trays®?

    This depends on your individual requirements.


    • Geotextile fleece to protect existing roof/membrane
    • Riverstone pebbles to be used as a firebreak and to go around drains


    • M-Tray┬« Irrigation Kit
    • Access chamber
    • Aluminium edging

    I have seen modular systems fail, why wonÔÇÖt yours?

    This is our 4th generation of the module, designed and manufactured by Wallbarn here in the UK. The 100mm deep tray with its optimum drainage; our specially mixed substrate and careful choice of mature and hardy sedum species mean the M-Tray┬« is the best quality modular system on the market.

    What other preparations should we consider prior to delivery?

    The M-Tray┬« modules are delivered stacked onto pallets and must be unpacked within 24hrs of delivery. A crane and forklift may be needed to transfer pallets onto the roof.

    Award Winning

    Award Winning

    Pitched against some high-quality roofing products, our M-Tray® modular green roof system beat off all competition to secure the coveted title of Best Roofing System or Product in the 2020 Build It awards.

    The M-Tray┬« has also won the award for ‘Best Green Innovation’ at the 2021 Green Home Awards.

    Fire Rated

    Fire Rated

    Our M-Tray® modular green roof system has a B ROOF t4 fire rating classification.

    To meet current building regulations for fire stakeholders need to demonstrate that the whole ‘as installed’ roof system has a valid fire certificate, tested in accordance with CEN/TS 1187:2012 Test 4 External Fire Penetration and Spread of Flame and the classifications under BS EN 13501-5:2016 Fire Classification Of Construction Products And Building Elements.

    A roof system when tested to CEN/TS 1187:2012 Test 4 Test Methods For External Fire Exposure To Roofs should achieve a European classification rating of B ROOF t(4).

    Under Approved Document B only a test report to BS EN 13501-5:2016 for the exact construction or an EXAP report proves compliance; unless the green roof build-up from the deck to the finished surface includes a minimum 80mm of growing medium with less than 50% organic content.

    M-Tray® by Wallbarn was tested according to CEN/TS 1187 and has both a Classification of B ROOF t(4) and an EXAP Report carried out in conformity with CEN/TS 16459:2019.
    Furthermore, the growing medium is 100mm thick and contains less than 50% organic content. It complies both to BS 8616:2019.

    This is construction law in England.  Similar laws apply in the building regulations of Wales, the building regulations of Northern Ireland and in the Technical Handbooks for Scotland.

    > M-Tray B ROOF t4 Extended Application Report

    > M-Tray B ROOF t4 Indicative Test Report

    > M-Tray B ROOF t4 Classification Report long form

    > M-Tray B ROOF t4 Classification short form

    > M-Tray B ROOF t4 Test Report

    > J002980 Walbarn Green Roof Module Substrate Specification incl Organics Content

    NBS Source

    BIM Library

    M-Tray® module eDrawings Format

    CAD Drawings

    ProductM-Tray® Modular Green Roof Container
    Suitable ForExtensive Green Roof Plants With Lightweight, Free-Draining Substrate
    Type Of ConstructionPermanent
    Width / Breadth500mm X 500mm
    Shape Of Walls / SidesTapered / Angled
    Units Per M24
    MaterialRecycled Polypropylene
    Thickness Of Material3mm
    Internal Ridge Height / Reservoir Height20mm
    Number Of Internal Drainage Reservoirs25
    Drainage Holes Per Unit8
    Distance Between Trays At Base20mm
    Distance Between Trays At 50mm From Base10mm
    Dry Weight (Empty)1.1Kg
    Weight Planted & Saturated *25Kg (100kg per m┬▓ excluding snow load)
    Connectors Per Unit4
    Number Of Handles On Underside4
    Detail Of Corners / EdgesSmooth / Reinforced
    UK Registered Design6140192
    UK Registered TrademarkUK00003041800
    UK Registered Cloned EU design post-Brexit90029539430001
    USA US PatentD787,186S
    USA Registered Design Application29/802,855
    EU Registered Design002953943-0001
    EU Registered Tradename15388523
    Canada Registered Design Application205094
    Argentina Registered DesignN┬║100508
    UAE Registered Design ApplicationD6000639/2021
    * Filled & fully planted field capacity of Wallbarn substrate & mature sedum plants during / after abnormal rainfall conditions.

    M-Tray Bee Bus Stops Gallery


    Export & Licensing opportunities

    As well as supplying live products for installation on UK green roofs and landscaping spaces, Wallbarn is committed to M-Tray® as an export product.

    We can supply the modules as empty trays for local landscapers worldwide to plant up and propagate according to the local climactic conditions and their own markets.

    Licensing opportunities are available for both the M-Tray® brand and the mould, which can be granted to specific partner companies across the globe.

    M-Tray® has been designed and developed by Wallbarn in the UK and holds registered designs and patents in the following territories:

    CountryIP RightStatusRegistration No.
    USADesign PatentRegisteredD787,186S
    UKCloned EU designRegistered90029539430001

    Our aim is to get more green spaces into urban centres worldwide. With M-Tray® this is a possible and economically viable prospect. Join us in our vision.