As the National Theatre prepares to raise the curtain on its 50th anniversary season, Kemper System has ensured that its Grade II listed building continues to perform by providing the waterproofing membrane for a major refurbishment project.
The famous South Bank landmark is an internationally acclaimed example of Brutalist architecture that has become as much of a visitor attraction as the productions that take place inside. The distinctive terraced balconies that form its rectangular concrete silhouette provide both public walkways and roofs for offices below so when their original asphalt surfaces started failing, resulting in leaks, the National Theatre decided to re-waterproof them as part of a £80 million refurbishment programme
Specialist contractor Cobsen-Davies advised the National Theatre on the best approach to minimise disruption to employees and visitors and ensure an environmentally responsible and durable specification. Kemperol 2K-PUR from Kemper System was selected as an effective, flexible membrane that could be applied directly onto the existing substrate without the need for any hot works or strip out. Because the cold liquid-applied membrane is solvent- and odour-free, it could be installed while the building was occupied with minimum disruption and in line with the National Theatre’s sustainability goals.
Re-waterproofing the 4th and 5th floor terraces and the inner quadrangle, Cobsen-Davies worked on small sections at a time so that access to all offices and workshops could be maintained throughout the project. Following minor repairs to the existing substrate, the installation team applied Kemper System’s Kempertec primer and, once this had been allowed to cure, the Kemperol 2K-PUR solvent-free resin was applied to each surface. The Kemperol resin saturates a non-woven reinforcement fleece and cures to form a totally seamless monolithic membrane that is UV stable and permanently elastic with a direct bond to the substrate. In some areas, Kemper System’s Kemperdur Quartz Coating was also applied to provide a coloured, slip-resistant, protective coating, creating designated walkways.
Kieron Lillis, head of engineering at the National Theatre adds: “The solvent-free approach was ideal for us as it meant that we could factor in our business as usual requirements and our sustainability goals while still addressing the long-term needs of maintaining the building. The use of the quartz coating also meant that we could enhance health and safety on the walkways in a single scheme, improving rather than simply repairing the structure.”