Front Cover Story
Instant sedum Green Roofs
Green roofs have now become an established element in flat roof and terrace design in the UK. They have been proven to offer environmental benefits to the immediate atmosphere and are now an increasingly important part of urban development. They improve the visual aesthetics of structures and introduce nature back into cities, mitigating the impact of densely populated areas and the urban heat island effect.
“What is a green roof?” is a question similar to “how long is a piece of string?”, they come in many different shapes and types. However, the most common sort and certainly the most cost effective, are the extensive sedum based living roofs, where a certain level of low growing, low maintenance plants are introduced to green up flat roofs, terraces and the like with real vegetation and to bring an element of real nature on hard structures.
WHAT IS THE PROBLEM WITH ROLL-OUT? All green roofs need light, water, drainage, and correctly engineered soils. Without all of these elements the green roof vegetation will not thrive. The actual system comprises of many different layers and each section must be installed in the correct quantity at the right time in order for the vegetation to thrive in the long term. It is extremely easy to make mistakes during construction which will lead to failure.
On roll-out systems it will arrive to site in jumbo bags. The contents then need to be distributed onto the deck, often on delicate roof membranes. This process is fraught with risk. The sharp aggregate can easily damage the membrane. In areas of high wind, the substrate often blows off the roof and can cause damage or injury below. Exposure of loose substrate on the roof space will also lead to the wind drying it out considerably, so the viability of the plants, once installed, is compromised. The cost and time in re-watering the substrate should also be considered. Green roof systems also include a number of filtration and drainage layers which are often sheet membranes supplied in large rolls. Getting large rolls onto sometimes small and inaccessible decks can be problematic and once there, the risk of these lightweight sheets or fabrics blowing off the roof is considerable.
The condition of the plants is also a major factor in roll-out. Sedum is often supplied rolled up in ‘blankets’. This process can seriously damage the plants and if they are not handled carefully or allowed to remain rolled up for too long or in too much heat, they can be damaged beyond feasible use before they have even arrived on site. Getting sedum blankets onto roof spaces is also a considerable challenge. They are very delicate and there is a serious risk that the roots and stems become damaged during transport.
WHY MODULAR?
The main advantages of modular over roll-out green roof systems are plant quality, convenience, speed and safety, future-proofing and instant results.
Wallbarn has over the years worked on designing modular green roof systems to try to make the construction process easier for contractors and to minimise failures. The new M-Tray® process. M-Tray®
modular system is the latest development in that has been designed and developed by Wallbarn to
improve modular green roof systems. Wallbarn is the sole rights holder to the design and name.
Every necessary element required for a successful green roof has been carefully measured and installed in the M-Tray®
modules at the nursery,
so users can be assured that a healthy, sustainable green roof is being supplied.
The plants are fully established and well rooted into the trays, the growing medium and the drainage and filtration components are suitable and compatible, and everything is at the correct level to give strong, healthy growth over the long term.
Mess and disruption are avoided using M-Tray® . Each 500 x 500 x 100mm
module has solid sides, so nothing spills out, a major advantage. Another key benefits is accessibility. One M-Tray®
can easily be carried by one
operative. For areas which are very difficult to access, such as single storey extensions, domestic projects and other completed structures, roll- out is simply not possible. Wallbarn has had experience of M-Tray®
being
hand-balled into even the most awkward areas, even carried through completed buildings or carried through windows. They are the perfect retro-fit product.
Wallbarn has spent a great deal of time and effort designing a simple but very effective clip system for M-Tray®
. Each module clips tightly to its
neighbour, so the joints are almost invisible. Installation is more than twice as fast as with roll-out systems. Time is money, so a considerable saving is achieved.
Once the plants start to grow the green roof becomes seamless. Optimum drainage has been designed into the modules. Excess water can escape but the system will not dry out too quickly.
M-Tray®
was developed to make more green roofs possible. If designers can envisage green roofs on areas which they previously did not think them practiceable and more green roofs appear on buildings in our towns and cities, this is better for the environment and for the users of those buildings.
M-Tray®
is designed and manufactured in the UK and is the subject of Community Registered Design (No. 002953943-0001) and US Design (Application No. 29/553,129).
WALLBARN
TEL: 0208 916 2222 7
WWW.WALLBARN.COM
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