Project Description
Historical Roof Restoration: A Case Study on the Application of Mastic Asphalt at St Paul’s Cathedral
Introduction:
St Paul’s Cathedral, one of the UK’s most iconic and architecturally significant structures, has undergone meticulous restoration by Sussex Asphalte. This case study delves into the restoration of the cathedral’s North Courtyard and Stone Gallery, focusing on the application of mastic asphalt, a material renowned for its durability and weatherproofing capabilities. The project not only aimed to conserve the historical structure but also to mitigate the damages caused by water ingress to the artwork and internal structures of the cathedral.
Project Overview:
Location: St Paul’s Cathedral, London, UK
Installation: Mastic Asphalt
Project Description:
Sussex Asphalte was entrusted with the renewal of the existing asphalt in the North Courtyard and the iconic Stone Gallery of St Paul’s Cathedral. The project involved the replacement of asphalt laid in 1906, covering a total area of 916m². The Stone Gallery, situated at 53 metres, had suffered from exposure to the elements, leading to surface deterioration and water ingress, which in turn damaged the invaluable artwork inside the Dome.
North Courtyard:
The North Courtyard, spanning 500m², required immediate attention due to water ingress affecting workshops and storage facilities. The project involved supplying recreational duty asphalt with added granite and reusing the asphalt previously stripped from the Stone Gallery. This asphalt had provided 111 years of weatherproof protection, making it the optimal choice for durability, performance, and conservation.
Stone Gallery:
The restoration of the Stone Gallery involved meticulous planning and precision, given the height and the highly sensitive fabric of the building. All materials were transported to the Gallery through a series of hoists, requiring careful operation and management. The asphalt was stripped and re-laid in sections to ensure watertightness, allowing the client to view the condition of the Portland Stone paving beneath the asphalt. During this process, a disused stairwell was discovered and subsequently made safe by operatives.
Execution and Management:
The project demanded excellent project management and skilled installation of asphalt to conserve this architectural masterpiece. The works were phased to enable continued public access to Stone Gallery sections. Detailed asphalt works included adjustments to rainwater outlets, vertical upstand into a chase, and the application of a double angle fillet around the Gallery’s circumference. Through meticulous planning and execution, the works were completed ahead of schedule, ensuring the conservation of one of the most important architectural structures in the UK.
Additional Information:
Sussex Asphalte hosted a site visit for a group of surveyors to promote the roofing profession and asphalt installation by highly skilled craftsmen, given the conservation and architectural significance of St Paul’s Cathedral. The project has been shortlisted as a finalist in the Mastic Asphalt category of the UK Roofing Awards 2018, marking it as one of Sussex Asphalte’s most important projects in its 70-year history.
Conclusion:
The restoration of St Paul’s Cathedral by Sussex Asphalte exemplifies the pivotal role of mastic asphalt in conserving historical structures. The successful completion of this project underscores the importance of skilled craftsmanship, meticulous project management, and the use of durable materials in preserving architectural heritage. The project serves as a testament to the versatility and reliability of mastic asphalt in providing long-lasting protection to buildings of historical and architectural significance.