St Catherine’s College, University of Oxford

Background

St Catherine’s College is situated to the east of Oxford City Centre, within the historically significant Central Conservation Area of Oxford. The prestigious location, reflects the cultural and architectural heritage of the College, as well as it’s contribution to Oxford’s character. Designed by renowned Danish architect Arne Jacobsen and constructed between 1960 and 1967, the original campus represents a significant example of Modernist architecture. The College is surrounded by green spaces on its eastern, northern and southern boundaries, offering a sense of space and connection to its environmental setting. To the west, the River Cherwell forms a natural boundary and beyond the river, the college has additional buildings.

Project Challenges

The long-term viability of the original buildings was challenged by the presence of Reinforced Autoclaved Aerated Concrete (RAAC) within them. Edgars were able to identify RAAC in all the original Jacobsen structures, which raised significant safety concerns due to the material’s tendency to deteriorate over time. An assessment found that 66% of the roof area, across the original buildings, were made from RAAC panels. Many of the RAAC planks were found to exhibit cracks of varying severity, indicating immediate action was needed. Further challenges presented themselves as, not only did the Jacobsen buildings consist of RAAC, they were Grade I and II listed. A potion of the campus was situated within the Oxford Green Belt, with many of the trees on the site being protected under Category A and B classifications. Furthermore, part of the site fell within a flood zone, making it necessary to have a mindful approach to site management to mitigate any potential risks.

Solutions

Recognizing the urgency of the project, a strategic decision was made to divide the proposals into two distinct phases. The first phase focused on the removal of the existing RAAC panels, thereby addressing the immediate safety concerns associated with the deteriorating material. The second phase would be to replace the panels with a newly engineered roof structure, carefully designed to be synonymous with the original Jacobsen buildings. Edgars collaborated with Oxford City Council, Historic England and the Twentieth Century Society to ensure all stakeholders were aligned on the method and timeline for the project. Each organisation provided valuable insights to ensure the proposed designs respected the standards.

Heritage

A key consideration throughout the planning and execution of the project, was the preservation of the surrounding environment. Edgars ensured all design and logistical arrangements were meticulously planned to ensure no trees within, or around the site would need to be removed. By balancing urgency with careful planning, Edgars aimed to deliver a swift, yet sensitive, solution to the structural challenges posed by the presence of RAAC.

Result

Following a pre-application, both planning and listed building applications were formally submitted six months after the project’s initiation. The applications outlined plans to replace the deteriorating roof structures with the objective of safeguarding the future of the original Jacobsen building.

Client Testimonial

“Removing and replacing the entire roof from a Grade I Listed Building is a huge challenge, but the robust interrogation and hard work of all teams involved ensures that we have found an optimal solution to address the problem of RAAC at St Catherine’s College.  We as a College are grateful to our partners in this project and look forward to restoring the historic Jacobsen Campus to full operations over the coming year.”

– Professor Byron Byrne, Finance Bursar