Educational Project in Central Oxford

About This Project


St Catherine’s College

Project Team:

AtkinsRéalis, Oxford ArchitectsColvin & MogridgeIngleton WoodAKS Ward, Bentley Consulting, MKA Ecology, Beard Construction, Pendery Architecture & Heritage, Oxford City CouncilHistoric EnglandTwentieth Century Society, the Historic Parks and Gardens Trust and St Catherine’s College Governing Body


St Catherine’s College,  Manor Road, Oxford


Tree Frontiers were part of a large collaboration which worked together to submit Planning and Listed Building Consent Applications on behalf of St Catherine’s College, Oxford. The applications seek to address the use of Reinforced Autoclaved Aerated Concrete (RAAC) in several of its Grade I listed buildings. We were asked to provide initial advice to the team regarding the constraints relating to the on-site trees, informing the design process. Further to this we provided an arboricultural impact assessment to accompany the planning application.

The Client:

St Catherine’s College, as it stands today, was built in the sixties and as such is considered one of the more modern Colleges in Oxford. It was designed by the architect Arne Jacobsen of Denmark, and his modernist masterpiece has become the most important 20th century collegiate building in Oxford, gaining it a Grade I listing.

As with many buildings constructed during the sixties, RAAC was used in certain areas, particularly the extensive roof structures. In September 2023 the College restricted access to a number of these areas whilst risk assessments were undertaken and a remediation plan was put in place.

The Opportunity:

We joined the project following recommendation by Edgars, with whom we have collaborated previously on a number of other projects. They recommended us to the design and engineering team led by Atkins Réalis. We were initially appointed to carry out a survey of the trees within the Site boundary, with a particular focus on those which could be affected – either above or below ground – by the proposed works.

Following a visit to the site we drew up an Arboricultural Feasibility Assessment together with a detailed Tree Schedule and a Tree Constraints Plan. These were provided to the project team to guide the design process to ensure the retention and protection of all trees within the site.

Once the plans had been finalised we were then able to write an Arboricultural Impact Assessment which detailed the tree works and tree protection measures which would need to be undertaken. No trees were recommended for removal, but we identified 19 trees which would require facilitation pruning in order to facilitate the erection of scaffold frames and hoists to transport removed material. In addition, we identified that 18 trees had the potential to be impacted through encroachment within their RPAs through the removal and reinstate of existing paving. Working with the Landscape Architect, we were able to develop a methodology that would alleviate harm during these operations. We also prepared a suite of Tree Protection Plans which demonstrated how the trees would be protected during the various phases of the construction programme.

The Results:

We were just one part of this immensely challenging project, but with excellent collaboration between all the teams involved the application to remove and replace the entire roof of this Grade I listed building was submitted. We await the outcome!

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Trees, Structures and Development