Fabric canopies unite revitalized buildings for Oldham Schools in England.
By Helen Elias
The city of Oldham in the northwest of England had a once-in-a-lifetime opportunity: Oldham Council was awarded £230 million (about $350 million) to spend on transforming secondary education through refurbishment or demolition and replacement with new schools. Most of the money came from the United Kingdom Building Schools for the Future (BSF) program. BSF, the biggest single coordinated investment in schools ever made in the United Kingdom, is driving changes to education across the country. Its stated aims include constructing school environments that encourage both learning and interaction with the environment.
The vision for the new Oldham schools was to provide 21st century centers of learning, helping to regenerate the vibrant and diverse Greater Manchester Borough by providing access to a wide range of opportunities through information technology, health, sports and arts facilities that will benefit the whole community. Two new schools form part of the program for Oldham, each school remarkable for its sustainable approach both during the design and construction phase and use.
Canopies bring outdoor ambiance indoors
Designed by U.K. firm Architects Co-Partnership, Radclyffe School and Failsworth School are both sites where covered courtyards provide the central heart to a collection of school facilities. Buildings on each campus are clustered around a central weather-protected courtyard space where students meet, large assemblies take place, and education activities go forward in a sheltered inside/outside environment.
Covering the space where the school buildings intersect with wide span single ply ETFE canopies was the clear solution to creating large, weatherproof “street spaces” that still felt like an outside area. The EFTE roofing solutions, supported on a discrete cable net structure, have minimal structural impact on the supporting buildings, while still allowing transmission of high levels of natural daylight into the covered areas below. The high light transmission is enough to let plants grow, yet still protect students from UV light, meaning the spaces can be used safely as teaching areas.
The 1,400m2 single skin cable net supported ETFE roof at the Radclyffe School has made the record books as the largest single span, single-ply ETFE foil structure to be installed to date in the U.K. The installation is so wide, in fact, that nets had to be slung underneath the working net during construction to allow installers to work safely.
Collaboration helps meet canopy installation challenges
Design of the fabric roof for both schools was completed by U.K. firm Architen Landrell, brought in to pick up work that had been taken part of the way by another ETFE contractor. Coming to the projects late meant working against the clock to get the program back on track so the school could open on schedule. Low-rise steelwork arch bays had already been designed and installed, but a problem arose: the steelwork arches spanning each space on each school construction site were not deep enough to allow rain to run off once the cable net and ETFE roof were installed. Ponding was an issue, and potential for damage from snow loading could be a problem as well.
Architen Landrell worked with the structural engineer, Tensys, and main contractor, Kier Group, to redesign the ETFE panels and the supporting cable net to create a roof that would perfom to specification, allowing rainwater to drain away and not collect on the roof.
“Using ETFE as a single skin application for a wide span roof such as this, working to its full tension strength, called for careful analysis of the fabric to ensure the loading calculations, especially with regard to snow, were effective to prevent ponding,” says Architen Landrell project manager Adam Hall. “We had to carefully analyze the form-finding and pattern for all of the panels.” The low-rise steel arches were a problem because they were already in place at each school and could not be changed.
Hall and the company’s managing director Lance Rowell had a short time frame to get both roofs redesigned to keep the school construction programs on track for the opening date in February 2008, a fixed and immovable date. They did not want to challenge the vision of a lightweight, floating roof by adding extra cable net structure.
Quick thinking makes canopy installation a success
They set about finding a solution to the ponding problem and ingeniously revised the extrusion jointing system used to connect the ETFE to the steelwork, making the angle steeper to allow water to run off the fabric
“Designing these large roofs had an extra level of complexity because we inherited the projects when they were underway, and they had problems,” says Lance Rowell. “Our approach was to be extremely rigorous. The situation allowed us to develop a methodology for analysis and installation using ETFE foil where the aesthetic integrity of the lightweight roof design was not compromised by introducing extra cable mesh. We allowed the roof design to remain light and elegant through an innovative solution to address what could otherwise have been a serious problem.”