After a long night of work by over 400 Paris firefighters, the fire at Notre Dame Cathedral is beginning to cool as of 7:00pm Eastern Time (1:00am in Paris). We're still not sure about the extent of the damage, but as Paris and the rest of the world watch the fire slowly dying, attention starts to shift to what can be salvaged and rebuilt. And art historians and architects have incredible records of the cathedral, which has been damaged, rebuilt, nearly abandoned, and renovated many times throughout its long history.
Roof and main spire destroyed, extent of damage unknown
Notre Dame's roof and its support structure of 800-year-old oak timbers had almost completely succumbed to the flames. Firefighters reported the cathedral's bell towers safe and said that many works of art had been rescued or were already stored in areas believed safe from the fire. The main spire—750 tons of oak lined with lead—collapsed in flames around 2pm ET, landing on the wooden roof.
The trees that made up the roof's wooden structure were cut down around 1160, and some sources estimate that the beams accounted for 13,000 trees, or about 21 hectares of Medieval forest, many of which had been growing since the 800s or 900s. "You have a stage in France where deforestation was a problem; these buildings consumed huge amounts of wood." That's according to Columbia University art historian Stephen Murray, who spoke with Ars Technica. All that wood, he said, supported an outer roof of lead—until the wood burned and the roof collapsed.
"The entire roof is destroyed; I hope the vaults can resist," reads an email from one of Murray's colleagues in Paris, which he was kind enough to share with Ars Technica. The high vaulted stone ceilings give the cathedral an open, cavernous feel and perfect acoustics for religious services, but they were also built to help protect the interior of the cathedral from an event exactly like this one: the collapse of a burning roof.
"The vaults are intended to fireproof the interior of the building," Murray said. "We don't know yet, as far as I know, whether that has been effective. The weight of that steeple falling on top of the vault may have punctured the vaults."
Some reports this afternoon suggested that furniture inside the cathedral was burning, which (if correct) wouldn't bode well for the vaulted ceiling. Much now depends on whether it also damaged the columns that support the body of the building.
Notre Dame wont be the same again
In a statement, French Prime Minister Emmanuel Macron vowed to the rebuild the cathedral, beginning with a national donation program to raise funds for the effort. It's clear that reconstruction at Notre Dame will be a massive undertaking, but its exact scale depends on exactly what's left behind when the fire finally dies away.
While architects have enough detailed information about the cathedral to pull off a technically very precise reconstruction, the craftsmanship is unlikely to be the same. Today, the stone that makes up the cathedral would be cut using machinery, not by hand by small armies of stonemasons as in the 12th century. "Nineteenth-century and 20th-century Gothic buildings always look a little dead, because the stone doesn't bear the same marks of the mason's hand," Murray told Ars Technica.
Entire forests of 400-year-old oak trees to replace the roof timbers will inevitably also be nearly impossible to come by, so it's likely that Notre Dame will never be quite the same. But, at least in the immediate aftermath, there appears to be a will to rebuild, and Murray notes that France has a large historical restoration industry. "There are companies very, very well equipped to take this sort of thing on," he told Ars Technica.