The Central Building on the University of Nottingham鈥檚 Castle Meadow Campus has what has been described as one of the most complicated roof structures in Europe.
The original PTFE (polytetrafluoroethylene) roof, designed and installed in 1994 by Hopkins Architects and Arup, was never designed to be easily replaced.
A team comprising GF Tomlinson, Base Structures and Novum Structures, working to designs by Bond Bryan Architects and Arup Consultants, has managed to strip of the old PTFE and replace it with a modern tensile structure, the latest generation in polyvinylidene fluoride (PVDF) plastic fabrics as part of a refurbishment of the building.
Before work started on site, the building was given Grade II Listed status and at 30-years old is one of the youngest buildings to achieve this. This presented additional challenges to ensure the heritage requirements were met, while meeting the original refurbishment brief.
The building鈥檚 entire framework has been refurbished to preserve its structural integrity and historical significance 鈥� a process that began mid-2024, with the removal of the building鈥檚 glass elements, repainting of the structural frame and refurbishing of key components.
Temporary rigging and birdcage scaffolding were installed to stabilise the frame, while sections of the roof were removed in sequence, starting with the north and south sections, followed by the main roof central section with its three floating oculi and finally the east and west. Structural strengthening, including additional welding and the replacement of worn components was carried out before the new fabric was put on.
The project continues to progress, with the installation of a new glulam mezzanine floor and a new central glass roof box to ensure natural light into the building. The final stages will include installation of new laminated glass to the roof, designed to meet modern building standards.
The university is displaying some of the original structural parts of the building on the campus to showcase the architectural elements and to preserve the legacy of the building鈥檚 original design.
The new roof spans approximately 4,500 square metres; the scaffolding used as a working platform for the replacement weighed 60 tonnes and stood seven metres tall, covering a platform area of 945 square metres. More than 5,000 bolts were removed and replaced, while 15 tonnes of existing glass will be reinstalled, complemented by an additional four tonnes of new glass within the facade.
Base Structures has been responsible for the fabric replacement, with Novum Structures installing the glass box and internal glazed roof lights.
G F Tomlinson managing director Adrian Grocock said: 鈥淭he Central Building project is a perfect example of how we combine innovative construction methods with heritage expertise to deliver transformative projects. The roof replacement represents a significant achievement, and we are proud to be playing a key role in extending the life of this iconic structure. Our longstanding working relationship with University of Nottingham, spanning over more than seven capital projects has allowed us to contribute to the campus鈥檚 evolution and provide world-class facilities that reflect its reputation for excellence.鈥�
Base Structures director Fraser Shirley said: 鈥淗aving built many of the UKs most notable fabric canopies, Base Structures fully appreciated the significance of this elegant and refined structure. The integrated tensegrity design was one of the first of its kind, making this a truly unique project.
鈥淭he fabric replacement works on the Central Building was far from straightforward, presenting an incredibly challenging task as the original builders had never intended for it to be replaced. Due to the sensitive nature of the structure, a meticulous and carefully planned methodology was essential to minimise excessive loading on its components. Significant input from Tensys Ltd was instrumental in developing this approach. The success of this project was ultimately down to the vast experiences with the Tensys and Base design, project and site teams, who in collaboration with the main contractor, GF Tomlinson, carried out the works safely and seamlessly, ensuring the structure鈥檚 integrity was maintained throughout. Base Structures are proud to have played a part in extending its lifespan."
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