"Stroke of luck" and know-how: how Notre-Dame was rebuilt identically

It was on the evening of April 15, 2019, when the roof of Notre-Dame was devoured by flames, that Cédric Trentesaux and Rémi Fromont became aware of the importance of their surveys, the first ever carried out in these frames since their assembly in the XNUMXth century.

Without their work, one of the feats of the reconstruction project - rebuilding the frames identically - would have been simply impossible.

"For the nave and the choir, our surveys were the main source," Rémi Fromont, who has not left Notre-Dame since the fire, agrees to AFP, becoming one of the architects of the project which will be completed with the reopening of the building on December 7.

"These readings are a stroke of luck in the immense misfortune that was the fire," adds Cédric Trentesaux.

Initially, the objective of the two forty-year-olds was nevertheless modest.

"The idea for us was just to document the cathedral, thinking that it might be useful one day, or not," recalls Mr. Fromont.

When they embarked on the adventure in 2014, the two architects had been practicing for ten years and were following additional training in heritage which took them to Notre-Dame.

It was there, during a visit to the building, that they learned that the medieval framework, a veritable forest of oaks 100 metres long and 12 metres high, had only given rise to very fragmentary measurements and that a detailed survey remained to be carried out.

"We stupidly said to ourselves: it hasn't been done, why shouldn't we do it?", remembers Cédric Trentesaux. "But we had absolutely no idea how much work it would take, and even less so the repercussions it has today. We went about it like students absorbed by our passion."

Polar cold

For a year, one day a week, the two comrades inspect the frames from top to bottom and take measurements by hand from a walkway, the tangle of wood making the 3D scanners inoperable.

During the winter, a polar cold reigns in the roof structures and the places are permanently plunged into darkness, forcing the permanent use of projectors and lamps.

But the two architects never thought of giving up. "We got caught up in the game. It was for the glory and the pleasure," sums up Cédric Trentesaux.

Their work, completed at the end of the cycle by the use of a laser device, was completed in 2015 and received an enthusiastic reception in the carpentry community, without however going beyond professional circles. Until April 15, 2019.

The day after the fire, the two architects were urgently dispatched to Notre-Dame to assess the extent of the damage and share their almost intimate knowledge of the framework.

"We had spent a year of our lives there and it had completely gone up in smoke," says Mr. Trentesaux.

When the idea of ​​an identical reconstruction of Notre-Dame finally took hold, their work emerged from anonymity to become the centerpiece on which dozens of carpenters would rely. Needless to say, the slightest imprecision in their measurements would not have gone unnoticed.

"We were relieved to see that we had done our job well," sighs Rémi Fromont, proud to have contributed to "restoring" this work with the help of carpenters using the same techniques of squaring wood by hand as in the Middle Ages.

For both architects, the identical reconstruction is not just a technical feat or a mark of respect for the master carpenters of the 13th century.

"By restoring the framework with the same materials and the same techniques, we are ensuring the historical continuity of Notre-Dame Cathedral," believes Rémi Fromont.

Even the imperfections of the frames, linked to technological progress during the construction in the Middle Ages, have been preserved to guarantee this authenticity.

The approach is radical but Notre-Dame is, according to Mr. Fromont, "a building which would have difficulty supporting the compromise."