MCRMA - Metal in Action - Intelligence No Secret For Kalzip On GCHQ Roof

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Intelligence No Secret For Kalzip® On GCHQ Roof

Although the internal workings of Government Communications are generally kept under wraps, the spectacular new Headquarters building in Cheltenham is certainly garnering a lot of attention. Topped with almost 12,000 square metres of tapered Kalzip aluminium standing seam, the huge doughnut-shaped GCHQ main facility was a winner in the recent Aluminium Imagination Awards and is actually three buildings in one - accentuated by Kalzip 'petals' over the connecting lobbies - surrounding a central courtyard the size of the Royal Albert Hall.

The use of clad stucco-embossed Kalzip continues in a group of six ancillary buildings, referred to as the 'String of Pearls', which house the gatehouse, a visitors centre, staff lodge and support services.

Under Britain's largest PFI project, the main contractor Carillion is also part of the consortium Integrated Accommodation Services which won the bid and is responsible for the maintenance of the building for the next 30 years.

Proving that a relatively simple design can solve complex problems, the round shape of the main building provides a defensive exterior wall, as well as an internal atrium 'street' and the central courtyard garden that is accessible from all three connected buildings. The new complex, designed by architects Gensler in London, replaces 50 separate buildings spread over two sites with one efficient campus that will accommodate over 4,000 employees. Since the focus is on environmentally friendly design, the building makes good use of natural lighting with its extensive glazing; the three-storey 'street' also has a glazed ceiling and allows ventilation to reach every floor of the offices. The consolidation of the facilities into one complex will reduce energy use as much as 40% over the previous, individual buildings.

Kalzip approved contractor Prater Limited installed the roof on the main building, while another approved contractor in the Teamkal network, Kelsey Roofing Industries Ltd, was responsible for the 'String of Pearls'. 'It was an interesting and unusual project,' said Kelsey's Mark Wallace, 'which had to follow a succession of completion dates for each building, allowing Carillion to achieve specific milestones within the overall development.'

Both Kelsey and Prater were involved fairly early on, with Prater suggesting the use of Kalzip to the design team since the sheets could be curved and tapered to fit the continuous curve of the building shape. The petal roofs over the linking lobbies are made from continuous tapered sheets some 70 metres long. To meet thermal performance requirements, the specification also includes decks, vapour barriers and insulation from the Kalzip product portfolio.

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