Green Roofs Masterclass
We don’t want out staff to be just technically proficient – we also want them to be knowledgeable about the history, current best practice and wider benefits of all types of green roof systems.
So, this week we sent all our installers on the Green Roofs in the Townscape Masterclass, delivered by @greenroofsuk in the presitigous surroundings of Northamptonshire’s Lamport Academy. And of course, as anyone familiar with the green roof sector in the UK knows all too well, there is always something new to discover with this endlessly innovative approach to low-impact construction.
While the GRO guidelines, which adapt the more stringent German FLL code for the UK construction industry, provide a national standard for green roof installation, one of the themes running through lively discussions throughout the day was that green roofs in the UK suffer from a lack of understanding on the part of clients, contractors and architects about their rationale, design considerations and post-installation care and monitoring requirements. It was a frequently expressed hope that with better training amongst green roof installers, the ethos underpinning good green roof design – letting nature show us the way and do the work – can be communicated to and understood by our fellow construction professionals.
The course covered a number of key issues, and there were particularly significant developments discussed firstly in terms of current green roof policy in London and around the UK, and also in best practice regarding drainage systems in the design and installation of successful long lasting green roofs.
We discovered that while the lack of any formal obligation to install green roofs is likely to remain, that the expectation of the GLA that new developments in London will have them is starting to produce substantially more green roofs in the capital, and that two factors were likely to see this both increase and spread to other important cities: the first is that in the next 7 years EU guidelines will begin to fall in place that require national governments to demonstrate how their cities are delivering green infrastructure; the second, relatedly, is that the Water Act passed by the last Labour government contains a little-heralded clause that water runoff be dealt with ‘at-source’. With 63% of London’s footprint being roofs (roads 23% and vegetated areas such as parks only 10%) it is clear that efforts to better manage unpredictable storm water will move to the rooftops in earnest in the coming years.
At Organic Roofs we are keen to do away with as many over-engineered elements in our green roof installations as possible, and it was great to hear that trends in green roof best practice point in the direction of doing away with expensive plastic drainage layers. Some speakers mentioned seeing specs for 50-70mm drainage boards, which seemed incredibly over-specified to all present. Pointing the direction of travel for green roof design, we were told that Austria has worlds most stringent green roof code and that there are moves there to do away with engineered drainage layer altogether. Apparently the modern vogue for engineered drainage layers has little to do with the needs of the plants and everything to do with the need to evacuate water more quickly from some poorly installed German membranes. Best practice is increasingly moving towards doing away with anything that produces substantial voids on the roof, something that we had previously heard at the Copenhagen World Green Roof Congress in 2012.
Much more was discussed during the course and next week we’ll be looking at best practice in green roof irrigation and how to explain the role of green roofs in insulating and cooling buildings to clients.
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