José Vaz de Matos, a firefighter who works with the Culture Ministry to help secure buildings and artwork, said that if the fire had reached the cathedral’s towers and the wooden belfries inside them, a catastrophic chain reaction would have ensued because the towers help support the whole building.
“If the fire had reached that wooden structure, the belfry was lost,” Mr. Vaz de Matos said. “And from the moment you lose the belfry, you lose the cathedral.”
Gabriel Plus, a spokesman for the Paris fire brigade, said at the news conference on Wednesday that about 60 firefighters were still at the cathedral to monitor the structure and to help the police and building experts navigate the building.
Firefighters identified several remaining risks in the building, he said: the gables, which were no longer supported by the roof’s woodwork and could be toppled by strong winds, and the metal scaffolding previously meant for renovation work, which was deformed by the fire and has to be removed. The vaulted stone ceiling was also covered with melted lead from the destroyed roof, he said, creating a potentially dangerous source of heat.
Mr. Macron’s plan to rebuild the cathedral within five years has prompted debate about how Notre-Dame should be restored — identical to its older self, with similar materials, or in a newer fashion, with modern techniques?
Isabelle Backouche, a historian at the School for Advanced Studies in the Social Sciences in Paris who specializes in urban history, said in an interview that she would not be shocked if reconstruction were done according to “modern plans.”
“Each era copies what was done before and at the same time adds its own inventions,” she said, noting that parts of the cathedral — the world-famous chimeras, for instance — were 19th-century additions or renovations.