European Stones For The British Museum

Claire Santry

The central courtyard of the British Museum in London, England, will open to the public this autumn for the first time since 1857 following completion of a three-year 26,286m-pesetas project to restore its acres of limestone features.

Measuring 100m x 70m the courtyard accounts for 40% of the building which, like St Paul's and many other landmark buildings in London, is built of indigenous Portland limestone.

More than six million people visit the British Museum every year. This new Great Court will allow them to view the famous museum almost as its original architect intended.

Sir Robert Smirke designed the building with four principal wings arranged around a central quadrangle. It was conceived as a major public space surrounded by magnificent Greek Revival style facades and gave the public direct access to the galleries across a central garden. The walls of the courtyard were clad in Portland limestone and each had a centrally placed solid Portland portico.

But almost as soon as the building was finished in 1852 it was unable to meet the growing demand of the Museum's library. The response was to construct a new reading room in the courtyard, demolish one of the stone porticos and allocate the remaining space to book storage. The inner courtyard became hidden from public view in 1857. The departure of the library in 1997 presented the opportunity to rediscover the courtyard. Construction of the Great Court began in March 1998 and has now entered its final phase. In essence, the inner courtyard becomes the focus of the building just as Smirke had wanted but the Round Reading Room remains and has been enlarged.

The reconstruction of the south portico is probably the largest construction of its kind in Britain for 70 years. Some 20m high and 64m wide, it has four solid stone fluted columns with ionic capitals. More than 2,000 tonnes of stone were used in its creation.

In the meantime, work on the inner courtyard's facades continued. The contractor, a firm called St Blaise, is using 141 cubic metres of Portland Coombefield Whitbed to restore damage caused by previous building alterations to the 6000 square metres of façade and to the other three porticos. In addition a big metal framed window had been introduced about fifty years ago. This has been removed and the wall reinstated.

"Most of the restoration work has been to the east, west and north porticos that 19th-century masons and builders had damaged or altered", explains project manager Mick Bushell. "Fortunately they could not reach all the way to the top of the columns but the lower 4.5 m of twelve columns have had to be reclad with fluted stone and some of the doorways and window surrounds have been replaced.

"The detail of the original work is exquisite so our work has been exacting. It's what this building deserves. Our brief demands joints as tight as 2mm on the walls and the matching up of fine mouldings and details. We have had a 60-strong team of masons on site for most of the past two years and completion is expected this month".

By mid-summer the paving of the courtyard should also be finished. Honed finish French Mereuil limestone will radiate from the Round Reading Room to the main courtyard area where 5 mm-thick slabs are 890 mm square. In total some 5487 square metres of paving will be laid by the installer, Grants of Shoreditch, who are also responsible for the cladding of the Round Reading Room in Spanish Capri limestone.

This latter element has proved to be a complex project, according to Lee Grant, joint managing director of the specialist firm. "The existing Round Reading Room is being partially enlarged on one side with the addition of a tiered elliptical structure to half its height," he explains. "This will be used for temporary exhibitions and a restaurant on the upper level. The designers want to achieve a monolithic appearance so, with solid corner blocks and other solid details, the stone selection has been very high. A typical slab is 120cm x 72cm but there are a lot of details and, because the building is completely round, every piece is curved on face".

The last part of this Capri limestone cladding will be attached to columns above the Reading Room. These columns support a 1,000 tonne lattice-effect glass roof which, supported by 10km of steel and covering an area of 6000sqm, will allow the Great Court and its facilities to attract visitors in wet weather and also in the evenings when the rest of the museum is closed. It will also earn the British Museum Great Court the distinction of being Europe's largest covered public square when it opens to the public in October.

Courting controversy

British stone producers, not unreasonably, assumed that Portland stone would be specified for the Portland stone British Museum. So the specification of Spanish Capri limestone for the Round Reading Room and French Mereuil limestone for paving caused a lot of anger. However, written assurances were sent to the Member of Parliament for the Isle of Portland that the local stone had been specified for two larger elements of the project: the rebuilding of the south portico and the restoration of the courtyard's 6,000 square metres of stone facades.

But when the scaffolding came down from the new south portico in May last year, rumours started to circulate that the stone was not Portland. Eventually English Heritage had the stone tested.

The stone was French Anstrude Roche Claire limestone. The contractor, Easton Masonry, claimed legal fulfilment of the contract because the specification had stated 'Portland stone, or similar'. This is a common architectural practice in the UK, designed to stop Portland Stone producers - there are only two - overcharging for supply to historic buildings. After weeks of deliberation English Heritage concluded that the French stone was a similar oolitic limestone to Portland so the new portico would remain. However, by way of punishment, they alleged poor workmanship that the stone contractor has had to rectify. Only the facades of the Great Court have, therefore, used a British stone.