Aerial drone view of Notre-Dame Cathedral during reparation works in Paris, France. Image © Agsaz via Shutterstock
Notre Dame Cathedral reopened on December 7th, 2024, welcoming visitors for the first time since the 2019 fire. The restoration of Notre Dame Cathedral was a massive undertaking, led by chief architect Philippe Villeneuve, assisted by Rémi Fromont and Pascal Prunet. The project involved approximately 2,000 craftspeople, 250 companies, and about $900 million, demonstrating the immense scale and complexity of the work on a tight deadline. Despite the major milestone of opening before the end of the year, the restoration works are not yet complete, as they are scheduled to continue through 2026.
2019 – Fire. Image © via Shutterstock, by Martina Baldini
Securing the Structure
It took over five hours to extinguish the flames in April 2019. Once emergency workers were able to enter the cathedral, it became apparent how close the structure had come to collapse, yet the bell towers, stained-glass rose windows and invaluable artworks were mostly untouched. The immediate priority was stabilizing the remaining structure, preventing further collapse, and removing debris. This involved a multi-phased approach spanning over two years. Initial emergency measures included the evacuation of the 1,300 artworks and the clearing of extensive debris. A sliding ‘umbrella’ was created to temporarily replace the collapsed sections of the roof.
2019-2021 – Securing the monument.. Image Courtesy of Histovery
Critical structural stabilization efforts focused on securing the vaults and flying buttresses, followed by the dismantling of tangled and damaged scaffolding, whose 220-ton weight was now threatening the thin walls of the cathedral. Remote-control robots were employed to clear out the debris, broken stones, and charred beams, but all fragments of the structure were carefully sorted and classified for their archeological and scientific value.
Sensors were installed throughout the monument to register any structural shifts, while wooden arches were installed to support the buttresses, while their status was being assessed. Interior scaffolding over 80 feet high was erected for access and further consolidation. Finally, the securing of the transept crossing marked the completion of this initial phase, allowing full-scale restoration to commence, with two chapels even undergoing preliminary restoration during this time.
2019-2021 – Securing the monument.. Image Courtesy of Histovery
2021 -The site of Notre-Dame. Image Courtesy of Histovery
Rebuilding the Spire and Roof
Notre Dame’s original roof was a meticulously crafted network of massive oak beams, earning it the name “the forest.” To rebuild this iconic structure, a national call went out, uniting communities and inspiring unprecedented generosity. From private citizens to state-owned forests, the wood for this monumental undertaking arrived as a testament to shared national heritage. The list of necessary timber pieces was compiled based on Viollet-le-Duc’s plans, many trunks needed to be perfectly straight, over 20 meters in length, and 50 centimeters in diameter. After the pre-selection process, the thousand chosen oak trees were harvested beginning in March 2021.
Rebuilding of the Wooden Trusses using Medieval techniques.. Image © Francoi Mori-AP
This opened the stage for one of the most impressive parts of the restoration: the rebuilding of the oak frameworks and lead roofing of the nave, choir, and transept of Notre Dame. The process respects the original designs of the spire and main attic built between 1859 and 1864 by Viollet-le-Duc, and the 13th-century structures of the nave and choir, also destroyed in the fire.
2021 – Visit the site of Notre-Dame. Image Courtesy of Histovery
Carpenters, employing traditional scribing techniques, create the spire framework from pre-selected oak, testing assemblies before installation. The spire’s openwork and needle will be covered in lead, adorned with decorative elements, and topped with a cross and cockerel. Simultaneously, the nave and choir frameworks are rebuilt using 13th-century techniques, involving the creation of trussed rafter bracing systems from squared oak beams, finally covered with lead sheeting. The completed structures will be prominent symbols of the cathedral’s restoration.
The restoration of Notre Dame Cathedral progressed significantly in early 2024 with the completion of major roof structures. The choir frame, a 32m x 14m x 10m structure, was finished in January, followed by the installation of the final trusses for the nave’s roof in March. The reconstruction of the iconic spire, designed by architect Viollet-le-Duc, and the entire roof structure is a major ongoing phase, as the complete restoration of the church is expected to be finalized in 2026.
Restoration of the Vaults and Masonry
In addition to the forest of oak trees, the restoration required 1,300 cubic meters of limestone, matching the original “white Parisian banks” stone. Geological surveys pinpointed suitable quarries, providing both hard and softer stones for various structural and decorative elements. A specialized extraction process, involving precise cutting and rigorous quality control, ensured the highest quality materials.
2019 – The net (c) Patrick Zachmann. Image Courtesy of Histovery
As the stonework suffered fire and water damage, a desalinization process was necessary, using kaolin and clay compresses to remove salts from the masonry. Collapsed vaults were reconstructed using original methods: wooden struts supported newly cut stones, precisely replicating the original forms. The transept crossing vault, a crucial element, involved a complex process using temporary wooden arches to support the stone voussoirs before final completion. Damaged coped walls and tracery were repaired or replaced with precisely matched new stones. Severely damaged gable stones on the transept were also removed and replaced, while the statutes were restored on-site.
Wooded arches supporting the butresses. Image © via Shutterstock, by AuroraGiampaoli
Conservation of Stained-Glass Windows, Sculptures and Artifacts
Notre Dame’s gargoyles and chimeras are instantly recognizable, grotesque figures adorning the cathedral’s exterior. Representing a blend of religious and secular imagery, they reflect medieval beliefs and artistic styles. While the “chimeras” represent strictly decorative elements, the “gargoyles” serve a functional purpose, acting as rainwater sprouts that deflect water from the cathedral’s walls and foundations. During the fire, several of these exterior sculptures were damaged, therefore, at the foot of the cathedral, a dedicated workshop was installed where sculptors assessed the damage. Depending on their condition, some elements were completely re-carved while others only needed lost features to be re-made and attached to the original sculpture with a rod. Additionally, the massive Grand Organ, though spared by flames, required dismantling for cleaning.
2021 – Chimeras. Image Courtesy of Histovery
Another representative feature of the cathedral is its stained glass windows, dating from the 13th and 19th centuries. Several of these windows had been removed before the 2019 fire in order to be restored. The rest of the windows, some having suffered smoke damage, have also been removed, documented, cleaned, and conserved by specialized workshops before reinstallation.
2019 – Disassembling the stained glass windows. Image Courtesy of Histovery
In a controversial decision, French President Macron has launched a plan to replace 19th-century stained-glass windows at Notre Dame Cathedral with contemporary designs, despite the windows not being damaged during the fire. While the windows are not original, replacing them evokes past controversies surrounding modern window installations in the 1930s, highlighting a recurring tension between preservation and artistic innovation. The project continues despite significant opposition.
Restoring the Interiors
The Notre Dame interior restoration addressed fire damage and centuries of accumulated grime. Initial dusting removed lead dust from the collapsed vaults using specialized vacuums. Subsequently, a latex application and removal method cleaned the interior walls, revealing the original stone color. This technique, while used previously at St. Paul’s Cathedral, generated concerns then and now regarding potential damage and the creation of an “artificially brightened” and ahistorical appearance. While the restoration body assures the goal is to restore original colors, not create a white interior, critics raise concerns about the prioritization of cleanliness over historical accuracy. The debate highlights the inherent tension between modern restoration techniques and preserving a monument’s historical patina.
The unfortunate events of April 2019 led, in a way, to the recreation of a process that has shaped Europe’s architectural history for hundreds of years: the construction site of a cathedral, where workmen and craftsmen from across counties and nations gather for a shared purpose. The French administration, instead of relying on a single contractor for the ambitious works, employed over 250 businesses, small workshops, and niche experts. It became a rare opportunity to employ and showcase diverse skills, some on the verge of disappearance. It all came together on the small island of Île de la Cité in central Paris, on a construction site that, at its peak saw over 600 workers daily, a complex choreography that allowed the Notre Dame Cathedral to be reborn.
3 SEPTEMBER 2024 Notre Dame, Paris. Image © Jackie Matthews via Shutterstock
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