A project of sustainable roofing innovation

Through a collaborative effort with David Kohn Architects and structural engineers, the project embraced innovative approaches such as utilising Building Information Modelling (BIM) technology for precise material quantification and whole life carbon assessments. The team also leveraged Environmental Product Declarations (EPDs) for significant carbon savings and employed the tracker+ carbon capture tool for comprehensive sustainability data management from the supply chain. The works were carried on by Sir Robert McAlpine.

For the critical task of waterproofing, RENOLIT ALKORPLAN F membrane was selected, paired with the innovative RENOLIT ALKORPLAN Solar mount system to secure the bespoke tiles.

Safety, strength, and durability in a design with high aesthetic value

The execution of the Gradel Quadrangles project required meticulous planning and innovative techniques, such as AR and AI, to meet the ambitious sustainability goals set by New College.

RENOLIT ALKORPLAN roofing products took on the challenge of waterproofing this complex structure with a keen focus on both durability and aesthetic appeal. The project began with the installation of a single ply membrane, underpinned by the RENOLIT ALKORPLAN Solar bar, guaranteeing a robust 20-year warranty. The roof's intricate geometry required the application of three layers of insulation, starting with a 105mm thick base layer, followed by two subsequent layers of 60mm. This strategic reduction in the thickness of the second and third layers was crucial for achieving the stunning rolling curves and free-flowing design of the roof.

Once the waterproofing was securely in place, the team embarked on setting out and installing the RENOLIT ALKORPLAN Solar bar, with its position meticulously calculated by engineers using Augmented Reality (AR) software. This advanced technology modelled a net, employing an AI algorithm to precisely calculate the placement of each of the 4,000 tiles required for the roof. Utilising the AR software on mobile phones enabled the team to model all tiles, the Solar bar, and the top hat, facilitating the filtering through layers to pinpoint exact locations within the project.

Ensuring each tile was oriented correctly was paramount, as this precision allowed them to seamlessly nestle together, forming a perfect, free-flowing roof, and provided the bond that fortified the tiles' strength. With 8,000 plates meticulously set out and affixed, the subsequent step involved thermally welding the RENOLIT ALKORPLAN roofing products’ F membrane to the plate. This welding bond was essential, offering the adhesion needed to support the RENOLIT ALKORPLAN Solar bar, which in turn, supported a top hat and ultimately the tile. This structure ensured that, even under wind suction loading, the integrity of the roof would remain intact, all the way back to the substrate.

The PVC-P profile forms the base of the system. Hot air welding is used to fuse the RENOLIT ALKORPLAN Solar profile to the roofing membrane for a fully integrated finish. The profile is securely fixed in place and cannot move and is therefore able to host creative finishings such as in the Oxford University. This is without the slightest risk of penetrating the waterproofing membrane!

The project was adorned with 3mm anodized aluminium polygonal-shaped tiles in a light bronze colour, accentuating the building's stone features and contributing to the overall aesthetic excellence. Transitioning from a concrete design to a glulam timber structure with tessellated aluminium tiles not only achieved the desired modern aesthetic but also offered a cost-effective, sustainable alternative. This strategic choice reduced embodied carbon, decreased construction time by three months, and garnered recognition from the Institute of Civil Engineers (ICE) Carbon Champion programme.

The project has been praised as “striking and ambitious” by the Oxford Design Review panel and described as “unusual, quite unlike anything currently in Oxford” by Historic England, underscoring its unique contribution to the architectural landscape, earning it the SPRA Award 2024 for “Best Detailing”.