The securisation of Notre Dame took place from 2019 until june 2021.
The devastating fire at Notre-Dame de Paris on April 15, 2019 marked a turning point in the history of this iconic cathedral. The fire partially destroyed the UNESCO World Heritage Site. France and the whole world watched in horror.
This event launched an unprecedented emergency phase, dedicated to securing the site and preserving this national symbol. This article looks in detail at the emergency phase, the safety measures implemented, the challenges encountered, and the outlook for the restoration of Notre-Dame.
More detailed information is available on our website:
- Notre Dame in fire – What happened ? Which consequences ?
- Notre-Dame reconstruction of the buiding after the fire, for the next centuries
- Notre-Dame interior rehabilitation, a delicate, giant and unique renovation
- Notre-Dame Reopening on December 8th, 2024 – An awaited moment
- 15 of the best hotels near Notre-Dame-de-Paris
Background to the Notre Dame fire of April 15, 2019
On the eve of the fire, Notre-Dame-de-Paris was in the process of being renovated, with work aimed at restoring its older parts and improving its structure. However, negligence in the management of the renovation works, particularly with regard to fire safety, contributed to the disaster.
The investigation is still ongoing. However, initial investigations suggest that the fire originated from unsafe welding work. The building’s fire alarms had not been activated and safety devices were inadequate.
What’s more, the cathedral, which dates back to the 12th century, had wooden structures, whose framework, nicknamed the “forest”, was particularly vulnerable. These combined elements allowed the fire to spread rapidly, destroying the emblematic spire and part of the roof.
In less than 30 minutes, the flames engulfed a large part of the cathedral’s roof and framework. Rescue efforts were quickly mobilized. But the complex structure of the building and the risk of collapse complicated the fighting of the fire.
The fire sent shockwaves around the world. Millions of people followed the events live on television and social networks. Solidarity rallies were held in Paris and other cities around the world, testifying to the symbolic importance of Notre-Dame to humanity.
The emergency phase defined the day after the April 15 Notre Dame fire
After the fire, the emergency phase began the next day. This phase was crucial in securing the site, preventing further damage and preparing the building for restoration.
- Damage assessment
An exhaustive damage assessment was carried out to determine the extent of the damage. Experts, including architects, art historians and engineers, were mobilized to analyze the structure and identify the elements to be restored or secured.
- Implementation of security measures
Securing the site was an absolute priority. Several measures were implemented to protect the remains of the cathedral and ensure the safety of workers:- Construction of temporary structures: Scaffolding was erected around the cathedral to support the damaged structure and prevent any further collapse.
- Installation of protective nets: Nets were hung to prevent debris from falling on the public and workers.
- Constant surveillance: Surveillance teams were put in place to monitor the site and prevent any intrusion.
- Preservation of works of art
The cathedral was home to many precious works of art, including stained glass, sculptures and liturgical objects. Specialized teams were tasked with safely removing these objects to preserve them. This involved painstaking work, as some works were fragile and most be handled with care.
Challenges at the start of the rescue operation after the Notre Dame fire
The emergency phase was not without its problems. Numerous obstacles hampered efforts to secure and preserve the works.
- Difficult working conditions
Workers had to cope with extreme working conditions. Safety was a major concern, and the site was often exposed to the elements. In addition, restoration teams had to work in dangerous areas, because of to the risk of collapse and debris on the site.
- Lack of funding
Although pledges poured in from all over the world, funding for the emergency phase was a challenge. The costs of securing and restoring the site rose rapidly, and managing the funds required precise coordination between government, business and private patrons.
The urgent need to secure the structure
In the immediate aftermath of the fire, the structural state of Notre-Dame was extremely worrying. A large part of the roof and framework, known as the “forest” for the density of its wooden beams, had been destroyed. The spire, an icon of the cathedral designed by Eugène Viollet-le-Duc in the 19th century, had collapsed, taking part of the vaulting with it. The risk of collapse was major, not only for the building itself, but also for the surrounding areas.
Initial analyze revealed several critical points of fragility of the structure:
- The Gothic vaults of the nave, although they had largely resisted collapse, were damaged by the collapse of the spire.
- The limestone that forms the core of the structure had been severely weakened by the intense heat of the flames.
- The buttresses, essential architectural elements supporting the structure, were weakened.
- The metal scaffolding erected before the fire for the renovation work had melted under the effect of the heat, forming an unstable structure around the cathedral.
In this high-risk environment, immediate securing of the structure was essential before any restoration work could be attempted.
Stabilizing the main structure for the securisation of Notre Dame
The first priority was to stabilize the parts of Notre-Dame still standing. Efforts were focused on preventing any further collapse, particularly of the vaults and walls of the nave, transept and choir.
Installing arches under the vaults
Despite their initial resilience, the Gothic vaults had significant weaknesses. To prevent collapse, wooden arches were installed under the damaged vaults. These temporary structures relieved the loads on the weakened vaults, ensuring the safety of workers inside the building.
Twenty-eight wooden and metal hangers were installed. This particularly delicate and spectacular operation was carried out under the supervision of the chief architect of historic monuments from July 2, 2019 to February 28, 2020. These hangers compensate for the loss of the weight of the framework and roofing required to balance the structure.
Consolidation of walls and gables
Although apparently intact, the cathedral’s walls and gables were in danger of collapsing. The north and south gables of the transept, as well as the west gable above the façade, required emergency consolidation. Wooden hangers, supported by metal scaffolding, were installed to reinforce these critical areas. Temporary props were also installed to prevent tilting.
Reinforcing the buttresses
Particular attention was paid to the buttresses, the famous structures that support the lateral thrust of the cathedral walls. Their role is crucial in maintaining the integrity of the building, and some had been weakened by the heat of the fire. To prevent failure, safety cables were stretched around the buttresses to stabilize them.
Installation of floors in the extrados of the vaults
Since January 2020, the Installation of floors in the extrados of the vaults has facilitated the evacuation of the accumulated remains by rope access technicians. An in-depth diagnosis has been carried out. Removal of the remains of the roof structure and roofing was completed in March 2021, and contractors are now working on securing the vaults and transept crossing by erecting scaffolding inside the cathedral and installing wooden hangers under the vaults.
Another step for the securisation of Notre Dame: removing the damaged scaffolding – a major challenge
Prior to the fire, complex scaffolding had been erected around Notre-Dame’s spire for restoration work.
This scaffolding, made up of 40,000 metal parts, had melted and twisted in the heat, creating an unstable tangle above the cathedral. Removing the scaffolding was one of the greatest challenges of the safety phase.
The scaffolding posed a threat to the cathedral’s structure, not least because it was caught in the wind. A number of sensors were installed to measure any movements, analyze them and issue alerts if necessary.
A delicate operation of securisation of Notre Dame
Dismantling the scaffolding was a highly complex operation but necessary for the securisation of Notre Dame. Meticulous preparatory work has been underway since early autumn 2019, requiring extensive lifting, access to the upper parts and scaffolding. The charred scaffolding was girdled so that it could be cut and purged, bay by bay (40,000 pieces, 200 tonnes of metal). A protocol to limit lead emissions was put in place in conjunction with the CRAMIF and the Labour Inspectorate.
Specialized rope access technicians, accustomed to working in high-risk environments, were called in to cut out each piece of scaffolding by hand. The operation took several months to complete, because of the complexity of the site and the precautions required to prevent further damage.
When the site was put on hold because of the health crisis at Covid-19, the actual start-up and removal must be postponed. This spectacular operation finally took place between August 2020 and November 24, 2020.
Using state-of-the-art technology
To ensure the safety and precision of operations, cutting-edge technologies were once again employed, including 3D scanners to model the scaffolding and anticipate risks. This enabled the teams to design a detailed removal plan, ensuring that every step was carried out in a controlled manner.
Weather protection: a site under pressure for the securisation of Notre Dame
With the destruction of the roof and framework, the cathedral was exposed to the elements, particularly rain, wind and snow. Weather conditions had the potential to exacerbate the damage, in particular by causing water infiltration that could have further weakened the stonework and internal structures.
Installing protective tarpaulins
The first solution was to install temporary tarpaulins over the most exposed parts of the cathedral, particularly in the nave and choir. These tarpaulins, supported by lightweight structures, protected the interior of the cathedral from the elements during the initial securing phase.
Building a giant “umbrella”
In a later phase, a giant “umbrella” was built over the cathedral. This metal structure, supported by pillars around the building, created a more durable cover under which safety work and preparations for reconstruction could continue, whatever the weather. This “umbrella” was designed to be flexible, allowing it to adapt to the needs of the worksite while offering protection from the natural elements.
Debris and water management
The fire and the efforts to extinguish it had left behind massive quantities of debris, including charred wooden beams, collapsed stones and metal fragments from the spire. The water used to fight the flames had also flooded parts of the building, increasing the risk of mould and crumbling materials.
Cleaning up the debris and managing the humidity required rapid but careful intervention, so as not to compromise the architectural elements and works of art still on site. Drainage systems were installed to evacuate water, and restoration teams began to treat the most sensitive areas.
The stability of all the gargoyles was checked
They had to use a gondola. Protective netting has been installed in the nave and choir to cushion falling stones.
Preservation of Notre-Dame-de-Paris works of art
The devastating fire at Notre-Dame de Paris on April 15, 2019 also threatened the rich artistic heritage it housed. The cathedral’s works of art, accumulated over the centuries, are exceptional testimonies to France’s religious, artistic and cultural history. In addition to monumental sculptures, paintings and liturgical objects, Notre-Dame contained items of immense symbolic value, such as Christ’s Crown of Thorns, preserved as a priceless relic.
The urgent need to safeguard these works of art provoked an immediate reaction. The authorities launched an artistic rescue operation on an unprecedented scale.
Evacuating sacred objects and treasures during the fire
On the evening of the fire, as the flames ravaged the roof and threatened the structure, teams of firefighters, clergy and heritage conservationists moved in. Among the priority items evacuated were the Crown of Thorns, one of the most revered religious objects in the Christian world, and the tunic of Saint Louis. These objects, which were kept in the cathedral treasury, were immediately transferred to the Hôtel de Ville de Paris for safekeeping.
Despite the difficulties and risks involved, most of the relics and sacred objects were saved.
Once the immediate emergency was over, conservation experts were able to carry out a more in-depth assessment of the damage caused by the fire and the fire-fighting efforts. This assessment made it possible to define the necessary steps for restoring the affected works.
Immediate management of untransportable works of art
Some works of art, because of their size or architectural integration, could not be moved immediately. This is particularly true of the large 17th-century paintings known as the “Mays de Notre-Dame”, donated by the Paris Goldsmiths’ Guild. These monumental paintings were too large to be evacuated in a hurry, so they remained inside the cathedral for several days after the fire. They were exposed to the humidity caused by the firefighters’ water, raising concerns about their conservation.
The main challenge in conserving the works of art in the immediate aftermath of the fire was the humidity caused by the tons of water poured over the cathedral to extinguish the flames. This humidity, by penetrating stone, paint and textiles, could cause serious deterioration, including mold, splintering and color fading. Works still in the building, such as the Mays, must be quickly dried under controlled conditions to prevent such damage.
Another problem was soot, produced in large quantities by the combustion of the structural beams. Soot is a degradation agent which, by seeping into the porous surfaces of paintings and sculptures, can not only blacken these works, but also cause chemical reactions with the pigments and materials.
The immediate task was therefore to protect the works of art remaining in the cathedral and to begin restoration work on those that had been affected by fire, smoke or water, and to dismantle those that could be, so that they could be appraised and restored in the workshop.
Securisation of Notre Dame : dismantling potentially affected monumental works of art
This operation, which took place in the weeks following the fire, mobilized restorers, curators and technical teams. The Mays of Notre-Dame, for example, were transported to the Centre de recherche et de restauration des musées de France (C2RMF) for careful study, cleaning and restoration.
The Mays de Notre-Dame, a group of 13 large paintings dating from the 17th century, were a top conservation priority, most of which had been exposed to damp and soot. Overall, they had escaped major structural damage. However, their pictorial surfaces had been altered by smoke and humidity, requiring careful cleaning and stabilization. The restorers used special solvents to remove the soot without damaging the original pigments, then stabilized the pictorial layers with consolidation work.
Another delicate operation: removal and restoration of the stained glass windows
In the case of the stained glass windows, several workshops of qualified master glassmakers (Babet, Baudoin, Duchemin, Isingrini-Groult, Loire, Parot, Vitrail France and the Vincent-Petit manufacture) were called in to meet the urgent need. They worked from scaffolding set up in front of the high windows, equipped with protective nets.
Notre-Dame’s monumental 13th-century rose windows survived the fire, but were threatened by temperature variations and debris. To prevent any damage, special protection was installed to preserve the stained glass windows. Plywood panels were temporarily fitted over the windows to protect them from impact and the elements.
Following the protocol established with the Laboratoire de Recherche sur les Monuments Historiques (LRMH), the stained glass windows in the upper bays of the choir and nave were assessed and dismantled between April and May 2019 by restorers, with the support of stained glass specialists from the André Chastel Center (UMR 8150 Ministère de la Culture-CNRS) for documentation and the removal plan. The stained glass windows of the three roses were maintained and protected in situ.
The panels were carefully numbered, crated and transported to the workshops, before being grouped together in the reserves set up by the public institution in charge of the conservation and restoration of Notre-Dame de Paris. Finally, the openings were braced to maintain their spacing and prevent distortion. Translucent tarpaulins were laid on the outside to ensure watertightness and provide the necessary light for the work.
Protecting sculptures and architectural elements
Particular attention was also paid to the sculptures that form part of the cathedral’s architecture, notably those in the portals and chapels. While some had been damaged by falling debris or bad weather, others, notably the famous gargoyles, had survived. For these elements, micro-abrasion cleaning and impregnation techniques were used to preserve them pending full restoration.
The stone sculptures that adorn the interior and exterior of the cathedral were also assessed. Some, located in the nave or transept, were damaged by collapsing roofing or scaffolding. The statues on the spire, removed a few days before the fire for restoration, were spared.
Restoration teams had to carry out a thorough cleaning of the sculptures, using lasers to remove layers of soot. The most damaged elements were temporarily relocated for restoration in the workshop.
The role of modern technology in preservation.
Modern technology played a key role in the preservation and restoration of Notre-Dame’s works of art, particularly in view of the extent of the damage and the complexity of the project.
Restoring the great organ
One of the most emblematic elements of Notre-Dame, the great organ, was also a victim of the fire, albeit indirectly. While the organ itself did not burn, it was severely damaged by dust, soot and extreme temperature variations during the fire. Moisture introduced by the tons of water poured in to extinguish the fire also endangered the wooden structure and metal components.
The entire instrument must be dismantled to enable complete restoration, a long and painstaking process. The organ’s 8,000 pipes were dismantled one by one, cleaned, restored and stored in optimal conditions until they could be reinstalled once the cathedral had been rebuilt.
Advanced cleaning techniques
Modern restoration techniques, such as the use of lasers to clean stone and paintwork, have made it possible to remove soot without damaging the works. These technologies have been particularly useful for stone architectural elements, which are highly sensitive to traditional cleaning methods.
3D scanners and digital modelling: an aid to restoration and securisation of Notre Dame
Prior to the fire, many of the cathedral’s elements had been digitized in 3D as part of study and conservation work. These digital models were an invaluable aid to the restoration teams, providing them with extremely precise plans for reconstructing damaged or destroyed elements. Sculptures, stained-glass windows and even architectural details could be modeled with great precision, facilitating restoration.
Continuous monitoring and risk management throughout the securisation of Notre Dame
Throughout the security phase, monitoring the condition of the cathedral was a top priority. Given the fragility of the structure and the potential evolution of risks, advanced monitoring systems were put in place.
Motion sensors and real-time monitoring were installed throughout the cathedral, particularly in the vaults, walls and buttresses. These sensors were used to detect any abnormal movement that might indicate a risk of collapse. If any movement was detected, alerts were immediately sent to the teams on site, enabling them to intervene rapidly.
Alongside electronic monitoring, regular inspections were carried out by teams of architects, engineers and firefighters. These inspections were aimed at continuously assessing the condition of the structure and adjusting safety measures where necessary.
Work costs and donor donations for the securisation of Notre Dame
The safety and consolidation work, which began on April 16, 2019 and will continue until June 2021, is estimated to cost 160 million euros.
Renovation of the structure will require around 550 million euros.
Donations from 340,000 donors in 150 countries amounted to 846 million euros. The Pinault family has pledged 100 million euros, the LVMH group and the Arnault family that controls it (France’s largest fortune) have announced a donation of 200 million, and the Bettencourt-Meyers family and their L‘Oréal group have also pledged 200 million. As for the Total group, it has announced 100 million.
Welsh writer Ken Follett has decided to donate all royalties from his story “Notre-Dame”, published after the fire on April 15, 2019, to the Fondation du Patrimoine. The donation will be used to restore Dol-de-Bretagne cathedral.
The remaining 146 million euros will be used for a third phase of work, starting in 2025, once the cathedral has been reopened to the public.