This month’s applications feature some big roofing projects, including Stansted Airport, St Stephen’s shopping centre in Hull and a secondary school
A. Because you don't want clutter
The elegant curved roof of the new sports hall at Ashton Park Secondary School in Bristol needed an innovative solution to give architect George Batterham the clean look he sought.
Spanning a 40m radius, the roof is designed to have a simple, uncluttered appearance both inside and outside the building. To achieve this, Arcelor Construction UK’s Arval unit supplied its long-span structural tray system, which spans horizontally between the main structural beams, eliminating the need for steel purlins and giving a plank effect appearance to the ceiling soffit.
Replacing the clutter of supporting purlins, the trays also give lateral stability to the main steelwork frame – known in engineers’ terms as a stressed skin or diaphragm design – while perforations in the trays improve sound absorption. The roof was clad with Arval’s Tacdeck 508 with its secret-fix system, which ensures that no fasteners penetrate the external skin, making the roof completely water tight.
B. Because it makes a wave
More than 6,000m2 of Pilkington Planar glass was used to complete the distinctive undulating roof at the £200m St Stephen’s shopping and leisure complex in Hull city centre.
Covering a 250m-long curved walkway as wide as London’s Oxford Street, the frameless structural glazing system extends down vertically at the ends to form the east and west entrance facades.
A variety of installation techniques were used by contractor Portal to complete the job safely and on time. Access to the glass from inside meant erecting mobile towers to travel to the crash deck scaffold; mobile and tower cranes with powered vacuum glass lifters were needed to gain access to the roof; and abseilers were also drafted in to apply external sealant between panes of glass.
C. Because it’s a bespoke design
Designing a curved, fully insulated concrete roof for a bespoke bungalow development at Chatham in Kent proved a considerable challenge for operatives from specialist contractor Roger Bullivant.
Bullivant’s concrete products division designed and installed a total of 22 ‘dual skin’ reinforced panels for the scheme, each containing polyurethane foam insulation. Individual roof sections span 5.6m, weigh 2.5 tonnes and incorporate five conduits that either hide cables for interior lighting or contain heat transfer pipes.
Bullivant’s project manager Paul Emblin was impressed: ‘Despite our worries, the precast sections were installed in just two days, helping significantly reduce time spent on site.’
D. Because of its size
‘Not your everyday roofing job’ is how BAA project leader Paul Chatten describes the £40m Stansted Airport terminal extension project, which has spectacularly involved using a 450-tonne crane to lift 22, 30-tonne diagrids (roof domes) into place.
The domes were first assembled at a dedicated construction zone at the airport before being carefully transferred by special transporter to the main construction site prior to each crane lift.
Specialist contractors from Watson Structural Steel and Mace had to work very closely with the terminal management team to keep disruption to an absolute minimum as each evening, a 75m-diameter safety exclusion zone was put in place around the crane while lifts were carried out. Weather conditions also meant no lifts could be completed if wind speeds were 17mph or more.
Once each diagrid was placed onto the steel structure, it was secured, glazed and weatherproofed. The scheme was topped out last month, it will open in June and final completion is set for December this year.
E. Because there are lots of them
A total of 24 individual roofs will make up the unique stepped and wave design of Pendle Vale College in Nelson, Lancashire.
Lakesmere won the £1.8m roofing contract for the scheme, designed by architect Capita Percy Thomas, which will initially feature 18 Kalzip aluminium standing seam roofs, with a further six membrane roof areas completed towards the end of the project. Comprising both straight and tapered sheets, some roof elements have been treated to improve acoustic performance, and the specification of the build-up varies to account for varying roof types.
Source
Construction Manager
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