How big buildings are cleaned

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The Petronas Twin Towers are fitted with a total of 11 cranes that allow cleaners to move up and down between the 32,000 windows. It takes workers a month to clean the panes on each tower and, when they finish, they go back to the top and begin again.The Petronas Twin Towers are fitted with a total of 11 cranes that allow cleaners to move up and down between the 32,000 windows. It takes workers a month to clean the panes on each tower and, when they finish, they go back to the top and begin again.

In August, a specialist team ascended London’s Houses of Parliament to clean the clock faces of the Elizabeth Tower – home to the famous Big Ben bell. The hands on each of the clock’s four faces were frozen for the week-long task but its chimes still rang out and the workers on the 96m-tall tower wore ear defenders to protect their hearing.

Kasia Delgado reveals how four other big buildings around the world are cleaned.

The 24,830 windows of the world’s tallest building are made from a million sq ft of glass. When the 830m tower was cleaned in 2012, a team of 36 people needed three months to wash them. They started from the top floor and worked down, standing on specially designed machines that emerged from cavities in the skyscraper and moved along rails skirting its curved towers. The project manager at Grako, the cleaning company that took on the task, said that coping with the height was “all about mindset”.

Window-washers at the 6,500-window Manhattan landmark have reported how, in winter, food and drink thrown out of windows of high-up floors often freezes on glass lower down – and that frozen coffee and yoghurt, for example, can be particularly difficult to scrub off. This is, of course, far from the only problem when cleaning a New York skyscraper. Richard Hart, head of the Empire State window-washing team in 1937, remarked casually that, “I’ll be working away, and a gust of wind will come screaming up from 34th Street and for a moment I’ll be doing a tap dance on nothing. Anyway, it keeps me interested.”

When the Petronas Towers were opened in Kuala Lumpur in 1996 there was a dispute over whether they were taller than the Sears building in Chicago (now called the Willis Tower) – the world’s tallest when it was completed in 1973. What is not in doubt is the cleanliness of the skyscrapers’ glass. The two towers are fitted with a total of 11 cranes that allow cleaners to move up and down between the 32,000 windows. It takes workers a month to clean the panes on each tower and, when they finish, they go back to the top and begin again.

It took engineers three years to build a machine that would enable cleaners to wash Norman Foster’s 182m tall skyscraper, which opened in 2006. The windows, made up of concave diamond shapes, were impossible to access using ordinary means so a rectangular steel box the size of a small car was designed to move around the roof of the tower on an elevated steel track. The project’s construction manager described the car as “like a ride at Disneyland”.

Copyright The Financial Times Limited 2014

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