|Repairing a broken window is usually not too taxing an affair. But it took a crane and four men four days to replace a broken pane in the world’s largest single-span glasshouse.
When a crack first appeared in one of the 785 windows of the Great Glasshouse of the National Botanic Gardens in Carmarthenshire almost three years ago, the garden’s publicist David Hardy knew that replacing it would be a “tricky operation”.
He said: “The pane measures roughly 4m x 1.5m (13ft 6in x 5ft) and weighs about half a tonne.
“The contractors, from Metallbau Fruhand, Germany, were probably working 40ft up for much of the operation.
“About 100 of the 785 windows in the roof open to regulate the humidity but two or three have been permanently stuck open.
“While the contractors were here fixing that, they were also able to replace the broken pane.”
He said the Great Glasshouse dome, designed by British architect Norman Foster, is tilted by seven degrees on its axis and is orientated to face south, helping to capture the maximum amount of sunlight in a day.
Inside, it is divided into areas of the world, depicting a wealth of exotic plants from the Mediterranean basin, coastal California, Chile, South Africa and south-western Australia.
Each glass pane consists of two 9mm (0.35in) thick sheets of glass with a laminated film in between, making a glass “sandwich”.
The award-winning garden attracts 160,000 visitors a year.