Page 87

RCI March 2018

1Project1_2013 07/05/Layout 1 Project1_GREEN ROOFS Green roof Mike Cottage, director at The Urban Greening Company, explains why maintenance is 084 MARCH 2018 RCIMAG.COM maintenance So why should we maintain green roofs, after all, if they aren’t overlooked, then why bother? We hear this comment frequently along with “maintenance is too expensive”, “I don’t own the building so it’s not my responsibility”, and “there’s no access.” Amazingly (and sadly) there are less than 5% of green roofs being maintained in the UK. This statistic is taken from years of experience and frustration at trying to get clients and owners to plan maintenance. After the defects liability period, they are often simply neglected, as they aren’t seen as an integral part of the building. However, if this is the case, then we need to remind the stakeholders why the green roof was installed in the first place. Creating wildlife corridors, protecting the waterproof layer, reducing thermal gain, and most importantly, reducing and delaying surface water run-off are the key reasons why green roofs have become a mainstream building feature. All these benefits can contribute to the aesthetic value, as well as the financial value of the building, and so it beggars belief that once installed, they are overlooked. There is a misconception that has wrongly been circulated over the past decade that important and invaluable green roofs need no maintenance. Low maintenance – ‘yes’, no maintenance is definitely a ‘no’. Green roofs are live, organic natural structures, and as such, will adapt and change to local climate and other influences in both a positive and negative way. Good design and implementation will play a big role in the level of upkeep required, but no maintenance will almost always lead to failure. So why bother? Keeping invasive weeds under control and keeping the vegetation in a healthy state will improve rainfall attenuation, reduce Urban Heat Island Effect, and provide habitat and foraging for a huge array of species. Ensuring gravel margins and drainage outlets are kept clear of litter, vegetation and leaves, maintains effective drainage capacity and prevents fire risk, in particular, around roof lights and any other roof openings. Ensuring access paths and walkways are clear is a fundamental yet important safety requirement. Maintaining all these elements improve the building value in so many ways. What are the barriers? Tracking down the owner, company or individual who is responsible for the green roof can, and often does prove difficult. Sometimes a green roof is perceived as being complicated, so many organisations and individuals are reluctant to take responsibility, as it can be seen as a burden. This can lead to planned negligence and inevitable degradation of the roof greening viability. Of course this perception couldn’t be further from the truth. In many cases, the stakeholders have embraced their green roof feature (every green roof differs in some way), and they gain an immense pride and satisfaction, and as a result, are often keen to enhance, improve and add as much green space as they can. They see maintenance as being a hugely integral part of their building’s upkeep. Roof access – to be or not to be? Are designers aware or even considering maintenance of the green roof? Time and time again there is no or little anticipation, or understanding of what is needed to look after the roof after the scaffold has been removed. Pity the green roof maintenance operative who in all weathers needs to take heavy sacks of fertiliser, substrate, and tools onto the roof, and who then has to remove sacks of litter and weeds from the roof on completion. Often the only way is to carry the sacks onto a shoulder and climb up a leaning ladder or even worse a vertical CAT ladder, it’s not only hard work but can also be precarious. Providing a simple eye-bolt or restraint to tie a ladder to (so that scrambling on and off a roof is safer) would be good. Providing external steps is even better of course, but we know this can’t always be practical. Where a man-safe line is incorporated onto a roof, is it a fall arrest or restraint system? The choice will have a significant influence for being able to access all the areas. Mobile Elevating Work Platforms (MEWPS) are a good way to get to the height needed, but the hire cost is often prohibitive and may be more than the maintenance cost itself. Some green roofs have no means of access and so no means of maintenance. Some forethought regarding the short, medium and long-term performance is essential. What seems obvious is perceived as being trivial. To tackle the challenges of climate change, urban spread and loss of crucial green space, and to increase the benefits of biophilic green cities and green infrastructure, we need to implement and co-ordinate careful planning, good design, quality installation, regular upkeep and effective maintenance. Protecting the waterproof layer, reducing thermal gain, and reducing and delaying surface water run-off, are the key reasons why green roofs have become a mainstream building feature


RCI March 2018
To see the actual publication please follow the link above