Government Office Building | London
Trusted partner:
The challenge:
A government building in London was experiencing persistent water ingress due to leaks occurring at critical roof details across multiple roof areas. The existing asphalt roofing systems had deteriorated over time, resulting in water penetration and increasing the risk of damage to the occupied building below. The project involved the refurbishment of five separate roof areas, each presenting unique waterproofing and detailing challenges. In addition to the water ingress issues, three of the five roof areas were affected by poor drainage and ponding water, requiring remedial works to improve long-term performance. The scope also included waterproofing a complex embedded glass roof and undertaking works within a live operational environment, where disruption needed to be kept to an absolute minimum.
The action:
Working in partnership with H20 Seal, a comprehensive refurbishment strategy was developed to address the existing leaks and improve the overall performance of the roofs. A temporary roof structure was installed to provide weather protection throughout the works, allowing the project to progress regardless of weather conditions while ensuring continued operation of the building. Five roof areas were refurbished using an
overlay approach to minimise disruption and avoid unnecessary removal of the existing asphalt substrates. Complete encapsulation of the existing roof systems, extended up and over parapet walls to create a seamless watertight envelope. Detailed waterproofing works were undertaken around the embedded glass roof with red finish in areas confirming ‘fragile roof’. Drainage improvements were incorporated across the affected roof areas. This included the installation of two tapered insulation schemes to promote falls and improve water management, together with the creation of a new internal gutter section on one roof. The works were completed over an eight week programme. Edge protection systems were installed to ensure safe access to the roof for works and future maintenance.
The solution:
AlphaGuard PUMA Flat Roof System was selected for the project due to its ability to provide seamless waterproofing across complex roof details and interfaces. This system is certified with Broof(t4) classification, and comes with a 25-year warranty. Its fast-curing properties enabled installation within the tight programme, while the fully reinforced monolithic membrane provided long-lasting protection across all five roof areas. The versatility of the system made it particularly suitable for encapsulating existing asphalt substrates, waterproofing the embedded glass roof detail and integrating with the new drainage improvements. By combining the AlphaGuard PUMA system with two tapered insulation schemes and a new internal gutter arrangement, the refurbishment not only eliminated the existing leakage issues but also significantly improved water management across the roofs. The project was successfully delivered within the eight-week programme, providing the client with a durable, high-performance roofing solution.
