School pupils take learning to the (green) roof

The British Association of Landscape Industries (BALI) is the UK’s premier trade association for landscape designers, contractors and suppliers of products and services to the landscaping industry. Membership for designers and contractors requires them to undergo a comprehensive vetting process to ensure the integrity of the BALI brand is maintained and associated with professionalism, quality and service. Equally, product and service suppliers must sign up to the BALI Code of Conduct to ensure they meet and exceed their clients’ expectations. Two BALI affiliate members – Boughton Load and SITA UK – work closely to produce an excellent product for green roof construction, just one example of BALI members leading the way.

St Bartholomew School in Newbury, Berkshire, has future proofed new school buildings by investing in a green roof, and products from BALI affiliate members Boughton Loam and SITA UK have helped in its construction.

The project began with the building contractor, Willmott Dixon, challenging a selection of Year 9 students to investigate the possibility of having a green roof system on new buildings planned for the school. The ‘Willmott Dixon Challenge’ required students to research the design, installation, cost, maintenance and life span of a green roof and establish whether it would improve the biodiversity of the school grounds and positively impact on the environment. The students’ findings were presented to Willmott Dixon senior managers and their design and construction team, who subsequently decided in favour of installing a green roof system.

St Bartholomew School’s interest in green roofs extended to involving a group of Year 8 pupils. They learnt about the different types of materials used and green roof expert Dr Alun Tarr, who spoke at a BALI’s green roof and living walls seminar in Sheffield, led a science experiment with the pupils testing green roof sedum varieties. The group created miniature scaled green roofs, which were then planted in specially constructed wooden boxes in the school grounds. The pupils monitored the growth rate of the sedum over a series of months and incorporated this research into both their science lessons and the overall research put forward to the Willmott Dixon Challenge. West Berkshire Council worked closely with Willmott Dixon in the planning stages, using the scheme as a flagship project for other schools in the area.

RoofGreen UK, subcontracting for Roofline, were brought in to construct the green roof and the pupils selected six different varieties of sedum to achieve as much variation as possible in leaf colour, flower colour and plant height. As well as achieving maximum aesthetic value this ensured the roof encouraged extensive biodiversity. The total roof area covered approximately 4000m² and BALI affiliate members Boughton Loam worked with Roofline to supply 400 tonnes of specialist lightweight growing medium containing BSI PAS 100 quality compost from fellow BALI affiliates SITA UK.

Bernard Courtney, horticulture manager from RoofGreen UK, commented on the logistics of installing the green roof: “It was a massive undertaking to get 400 tonnes of soil and 55 tonnes of gravel to roof level of a six storey building. Moreover, none of the roofs are flat and have a very intricate design with slopes of different angles ranging from 6 degrees to a maximum slope of 18 degrees. Special soil retention brackets had to be installed to ensure maximum stabilisation. Planting was also a massive undertaking on this project: 68,000 plants in an area the size of a small football pitch spread over seven different roof areas. We were very satisfied with the outcome of what was a very prestigious project; our team felt proud to be a part of it”.

For details of BALIcompanies designing, supplying and installing green roofs and green roof products, visit www.bali.org.uk.