Page 85

RCI March 2018

2013 07/05/Layout 1 Project1_GREEN ROOFS A ‘clean’ route to A recent Livingroofs.org report revealed the UK’s home-grown green roof market is showing a healthy 17% year-on-year increase. It’s a growth fuelled by urban areas across the UK, following London’s lead in the drive for greener towns and cities. But how green are our roofs? Lee Virgin, London’s branch manager at BriggsAmasco, offers a guide to ‘cleaner’ green roof installation 082 MARCH 2018 RCIMAG.COM green roofing What is there not to love about a green roof? Aesthetically, it brings much-needed colour to an otherwise grey, concrete-coated urban landscape, as well as a healthy, natural oasis for the betterment of the living and built environment. BriggsAmasco is mainly concerned with the fitting of two types of green roof systems – sedum and plug plant. Each has its challenges in terms of installation. The sedum mat is a generally more robust system to fit. It’s grown in a greenhouse before being rolled-up and transported to site. Good forward planning is essential to ensuring a smooth transfer from pallet to roof. A sedum mat will not survive on a pallet for longer than three days, therefore, the roof’s waterproof base should be in positon in good time before its green layer arrives. To optimise the project’s ‘green’ credentials, it’s always advisable to source sedum and plant life from a local grower or nursery. This not only ensures the materials will arrive on-site in a healthier condition, having spent less time dryingout in transit, but the transportation itself results in lower fuel costs and just as importantly, fewer carbon emissions. Plan to plant Plug plants arrive pre-potted and rooted – which is the same as buying from a nursery – and are planted onto a roof via a mixed substrate of mud and brick. An ecology report will determine how many plants are required per square metre, whilst the green layer is generally laid to a width of between 70mm and 100mm. The only potential issue with the installation of the substrate is people walking over it whilst it’s in situ. Plants need to be in positon between April and September; May is most preferable. Good logistics will again pay dividends to avoid projects finishing outside of these optimum times. The main challenge of any roof installation is transferring the material – particularly the substrate – to the top of a building. For instance, when laying a substrate to a thickness of 100mm across a 1,000m roof, that’s a few tonnes-worth of bags that need taking to the roof. In such instances, the process is made easier – though not necessarily quicker – by spreading the load and using more bags. This increases the amount of lifts, but ensures a safer operation. A hoist can be used to convey these materials and presents a ‘cleaner’, if more time-consuming transportation method than a crane, which is generally only scheduled to assist in the lifting of large materials to the roof. Following a project’s handover to the client, the green roof’s maintenance is provided by a qualified sub-contractor. A sedum roof doesn’t require a lot of maintenance, and could be considered the greenest of green roof installations as it thrives in the temperate – and occasionally damp – UK climate. Plug plants need to be nurtured and watered regularly, otherwise the system will die. Green roofs require inspection and tending at intervals to ensure their upkeep. For this to take place safely for those on the roof and on the ground, and without the need to install mechanical failsafe systems, BriggsAmasco installs man-safe railing. This is in spite of the fact such a precaution is not always a health and safety requirement. Case study – Battersea Power Station The redevelopment of the Battersea Power Station site in London provides a fine example of how a green roof system is being employed in a modern, residential and commercial complex. BriggsAmasco was selected to install a multiple roof system for phase one of an eight-phase project, which will eventually transform the derelict 39-acre site into a thriving mini-city, replete with retail stores, restaurants and bars, a six-acre park, a community theatre, and residential apartments. The initial phase involved 12 high-rise residential blocks to the west of the site, comprising 850 residential apartments, as well as retail facilities, theatre space, business studios and two levels of parking. BriggsAmasco supplied six green roofs and two lower – level roofs consisting of limestone paving. None of the green roofs, made-up of plug plant systems, will be accessible to the buildings’ future owners. A glass balustrade lines the perimeter of the building. Beyond that lies Chinese granite terracing and green roofing, which is located between the tracks of an external Building Maintenance Unit on every level of the complex. Each plug plant system was installed within a Hydrotech Monolithic membrane, which provides excellent root protection and allows immediate access to waterproofed areas. The roofing aspect of the Battersea Power Station project was completed in April 2017. www.briggsamasco.co.uk The BriggsAmasco green roof system has been installed at the Battersea Power Station in London


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