Notre Dame fire: Rebuilt structure ‘may look the same but it will be altered irrevocably’

The price of reconstructing Notre Dame will come to more than a billion pounds, according to experts, but the good news is that medieval buildings were designed to survive.

Assessing the probable cost, Alan Dunlop, a visiting professor at the University of Liverpool, said any rebuilding would be complicated by the cathedral’s location in the middle of the Seine and the centre of Paris, which could make access — just as it made firefighting — difficult.

“About a billion pounds is a good estimate,” he said. “The oak beams are all gone and the stone will have been affected by the fire so it will be a big task to rebuild it, and it will have to be an outstanding piece of work given its cultural importance. But money will be no object and it doesn’t look like finding £1 billion will be a problem.”

It will take weeks for the debris to be cleared and a proper assessment of the damage to be undertaken. Some of that task may be made easier thanks to an architectural historian who made a painstaking digital model of the cathedral that was his obsession. Andrew Tallon, a specialist in French gothic architecture, who died last year aged 49, spent five years using a special laser-scanning technique to create a three-dimensional image of the cathedral accurate to five millimetres.

Although the stout walls are standing they are likely to have been weakened, and pouring cold water on to hot limestone may have resulted in cracking. But the flying buttresses associated with the gothic style will have provided them with “a structural exoskeleton”, according to Lisa Reilly, an associate professor of architectural history at the University of Virginia, while the sanctuary was partly constructed with fire in mind. “It’s designed so that if the roof burns off, it’s hard for [the fire] to spread to the rest of the building.”

However, two thirds of the roof has been destroyed, as has the spire, and will have to be rebuilt from scratch. But, given that 13,000 trees were required for the original structure, obtaining them might prove problematic: France’s top producer of oak, the Charlois Group, said it was a task that would take several years.

“It’s difficult to say exactly how it will be rebuilt without knowing how much the masonry has been affected,” Jane Kennedy, a specialist at Purcell and the chairwoman of the Cathedral Architects Association, said. “Any reconstruction will probably take many years . . . It’s a sad reminder of how vulnerable buildings are when reconstruction work is being undertaken.”

Eric Fischer, head of the foundation which is overseeing the restoration of Strasbourg cathedral, also warned that the project could take “decades” to complete, despite President Macron pledging that the work will be finished in five years.

Ms Kennedy pointed out that many fires were caused by construction and in particular lead work; the cathedral roof contained 250 tonnes. Something similar may have happened at the Glasgow School of Art, which was being repaired when a fire broke out on June 15 last year. Charles Rennie Mackintosh’s 110-year-old masterpiece was nearing the end of a £36 million restoration after a fire in 2014. It is now being rebuilt a second time, though not everyone is in favour.

“As soon as you rebuild a structure, the new materials alter it,” Professor Dunlop said. “It may look the same but it won’t be the same. With Notre Dame, we can replicate it almost exactly but it won’t be the same.”

Other places of worship have been reconstructed after conflagrations in the past, including Notre-Dame de Reims, which was shelled during the First World War and pieced back together between 1919 and 1938 with the use of a new material — concrete.

Fire swept through St George’s Hall at Windsor Castle on November 20, 1992. It caused great damage but the castle reopened in 1997 after a restoration costing £36.5 million.

York Minister was set alight by a lightning strike on July 9, 1984, causing £4 million of damage. It was rebuilt using traditional methods, although the roof was compartmentalised and hatches were added so fire crews could get easy access in future.

John David, the master mason at York Minster who worked on its reconstruction, has no doubt that Notre Dame can be repaired. “It doesn’t look too far gone to me,” he said. “It’s got to be assessed and the fact it is still standing is very encouraging . . . I think all those people who were in tears watching Notre Dame burn would want it to be restored in the manner it was built.”