Written by Oscar Holland, CNN
As the ashes settle at Notre Dame, the laborious restoration process can begin. Rebuilding the cathedral will take years. Yet, for a structure that took decades to construct, and then stood for centuries more, this may simply mark the latest evolution of a building that has been reshaped many times during its 850-year history.
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These early donations suggest that, perhaps, the most difficult part of any major restoration project -- funding -- may be taken care of. But, assuming the requisite backing transpires, how exactly will the process be carried out?
A 'war of attrition'
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Before distinguishing between the salvageable from the unrecoverable, immediate steps will need to be taken to prevent further damage, according to architectural historian and broadcaster, Jonathan Foyle.
"It's already a wet building because of the water that's been pumped on it, so they're going to need to provide some kind of cover from the elements," he said in a phone interview. "The roof's job was to discharge thousands of tons of water, so where's that going to go? Every time it rains it's going to cause damage at this point, so it's against a war of attrition now."
Firefighters spray water as they work to extinguish a fire at Notre Dame Cathedral in Paris early on April 16, 2019. Credit: Zakaria Abdelkafi/AFP/Getty Images
After protecting the building's remains, restoration teams will begin assessing the level of damage. The vault appears to be only partially damaged, but the stonework could be more compromised than it appears.
High temperatures can change the chemical nature of limestone, Foyle said, with the resulting calcification potentially weakening the structure. And pouring cold water onto hot stone -- as will have inevitably happened as firefighters tackled the blaze -- can caused thermal shocks that may have cracked parts of the cathedral's stonework.
An army of archaeologists
French authorities will then, ultimately, need to take a series of design decisions about how best to rebuild. To do so, they will need to better understand how the medieval cathedral was constructed.
"The stripped roof and upper masonry will reveal aspects of the building's history which probably haven't been understood," Foyle said. "Notre Dame has virtually no building records. We know (that construction) started in 1163 and was basically completed by about 1240, but there are no building accounts.
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"Evidence for the evolution of that building is in the physical fabric, so you'll need an army of archaeologists all over it to better understand which parts they're repairing and what they belong to."
Another episode in 'creation, destruction and repair'
A worker inspects the hull section of The Cutty Sark on October 11, 2007. The original conservation project was interrupted because of the damage caused by a fire on March 21, 2007. Credit: Peter Macdiarmid/Getty Images Europe/Getty Images
The new Cutty Sark, London UK (part of "Maritime Greenwich", UNESCO world heritage site). Credit: Maria Swärd/Moment Open/Getty Images
Authorities may wish to stay faithful to earlier renditions of the state-owned cathedral. But it's also plausible that France takes a bold new direction with one of its most iconic national monuments.
That 19th-century restoration also saw other significant changes to the cathedral's facade and interiors.
"Notre Dame is not a building that has been fossilized in time, Foyle said. "It has not remained static since the early 13th century.
The entire wooden interior of Notre Dame Cathedral has been lost
"It's not something that had been perfectly preserved which was totally destroyed last night. You might (instead) see this as a traumatic episode in the long history of cyclical creation, destruction and repair. It's lived through wars, it's lived through reformers, and this will, I think, prove to be another episode."
The cathedral of York Minster rising above the city. Credit: Terry Roberts Photography/Moment RF/Getty Images
Perhaps a more relevant precedent is the UK's York Minster, a gothic church partially destroyed in a 1984 fire. It was restored over four years a cost of just £2.25 million (about £7 million, or $9 million in today's money). And, in terms of structural damage, Notre Dame may be in better condition, as its vault was primarily made from stone, not wood.
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"It seems as if the church beneath (the burned roof) has been protected from the intense fire," Foyle said. "That's the big difference between somewhere like Notre Dame and York Minster, which had oak vaults and therefore fell to the ground and burned upwards. And even so, York was salvaged."
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