With centuries-old wood and no fire safeguards, Notre Dame's attic burned quickly

Notre Dame cathedral engulfed in flames on Monday.

(Image credit: AP Photo/Thierry Mallet)

last updated 17 April 2019

When the first fire alarm went off at Notre Dame cathedral on Monday evening, a staffer checked the most vulnerable part of the entire structure, the attic, and was relieved to see no flames, Paris prosecutor Rémy Heitz said Tuesday.

That didn't last. Within 23 minutes, the attic was ablaze. Known as "the forest," the attic was full of wooden beams from trees cut down between 1160 and 1170, and over the centuries, they became extremely dry. The cathedral has gone through restorations, but firewalls and sprinkler systems were never installed in order to protect the design of the structure. It was also risky to add electrical wiring to the forest. "Everyone knew that the attic was the most fragile part," Pierre Housieaux, president of the Paris Historical Association, told The New York Times.

The flames spread across the attic and roof, up to the spire, which then toppled over and fell through the cathedral's ceiling. Experts say had there been sprinklers inside, the damage might not have been as extensive. Firefighters were prepared, having done exercises at Notre Dame before, and knew to get their water from the Seine. At least 500 were on hand to battle the blaze, with 100 focusing on saving the artifacts and relics inside. The cathedral was undergoing renovations when the fire broke out, including to repair attic beams, construction engineer Olivier de Chalus told the Times. The attic, he added, was Notre Dame's "jewel, the true piece of art that wasn't accessible to many."