Mapei's solutions for Notre-Dame de Paris

Mapei was proud to be part of the extraordinary restoration project of the Cathedral of Notre-Dame de Paris, which was severely damaged by a fire on 15 April 2019. Working with the two contractors Lefèvre and CCR (BALAS group), who had won the tenders launched by the public institution Rebâtir Notre-Dame de Paris—the commissioning body—the company provided solutions for the restoration of the vaults of the transept, the two arms of the transept, and the nave (Lefèvre), as well as the choir (CCR).

The reopening of the Cathedral to the public was scheduled for December 8, on the occasion of the celebration of the Immaculate Conception, although not all operations were expected to be completed by then.

For this project, Mapei applied its most advanced knowledge and skills in the field of structural reinforcement. The reconstruction work on the vaults began in the spring of 2022, following the training of masons and stonemasons on the correct use of the solution chosen by Mapei. The work was carried out daily with the utmost respect for the heritage and with the expertise of various specialists in the restoration of historical monuments.

With the goal of restoring the cathedral to its pre-fire state, a premixed mortar was used—based on natural hydraulic lime (NHL) and Eco-Pozzolana—supplied by Mapei and reinforced with fibreglass mesh. This solution was specifically developed for the consolidation of historic works and was approved by a team of three architects specialised in historical monuments and responsible for the project: Philippe Villeneuve, Rémi Fromont, and Pascal Prunet, in collaboration with Italian architect Carlo Blasi, who oversaw the structural elements. The solution proposed by Mapei underwent a year of testing, with numerous experiments conducted both in laboratories and on site, before being definitively approved by the three architects.

“This structural intervention, acting like a real shell, restored the masonry vaults to their original shape and strength,” said Thomas Briac, the engineer in charge at the Lefèvre company. “It mitigated the effects of future movements and helped avoid fractures in the joints with the adjacent reconstructed areas. The use of the most innovative technologies was of great help, because a heritage project is not a project out of its time.”

“The long experience that Mapei had in relation to mortars used in restoration and consolidation works was greatly appreciated,” said Carlo Blasi, Consultant for the direction of the structural reinforcement works of Notre-Dame Cathedral. “Mapei was able to demonstrate that its materials had been tested, subjected to various trials, and possessed the necessary certifications regarding their resistance.”