Can Notre-Dame rise from the ashes with 3D printing?

Christophe Petit Tesson, Pool, AFP | Debris inside the Notre-Dame de Paris Cathedral in Paris on April 16, 2019, a day after the fire that devastated the building.

French President Emmanuel Macron has pledged to rebuild Notre-Dame in just five years. This timeframe would be very difficult to achieve using traditional construction methods but one company believes it might be possible with 3D printing.


Macron wants the jewel in Paris’s architectural crown to be restored to its original glory by 2024. But some experts have called this deadline too optimistic and political opponents have accused Macron of wanting to rush the restoration in order to have the cathedral ready in time for the 2024 Olympic Games, which will be held in Paris.

Another option is to rebuild it in a more contemporary fashion, but Paris is slow to adapt to change. Remember the outpouring of disgust and horror when the Louvre revealed its glass pyramid design, or when artist Daniel Buren installed his zebra-striped columns in the courtyard of the Palais Royal?

However, Dutch design firm Concr3de has said that not only is restoration possible, it can be done within the five year target. It can retain the design of the original and it can cost less than the restoration fund. And they can even use the scorched remains of the cathedral in the restoration process.

A mixture of limestone and ash loaded into a 3D printer

Speaking to FRANCE 24, Eric Geboers, co-founder of Concr3de, said, “As the extent of the damage is becoming clear, it is time to think about how to rebuild this sacred monument that has seen so much history. We propose a strategy to rebuild Notre-Dame in a modern way that maintains the soul and layered history of the building.

“Why not reuse what is left? What if we take the remains of Notre-Dame and use them to build her up again? What if we take the stone that has seen so much history and use that to maintain the soul of the building?”

Rebuilding with the remnants

Concr3de suggests combining old materials with new technologies. They will collect the ash, dust and damaged stone remnants in the nave of the cathedral and turn that into a 3D printable powder. “This powder will have the yellowish grey colour of Parisian stone and will be mixed with the charred remains of the wood. We can use this powder and directly 3D print the destroyed parts of Notre-Dame.

“The ash and limestone that remain would probably make up about half of the required materials. Then we would bind them together. But we would not use any plastics or resins. It would be a much more natural and pure procedure than that.”

“It is impossible to say at this stage exactly how long the work would take, but it would certainly be finished within five years,” said Geboers. “Working with our technique is at least five times faster than cutting stone.

“Of course it will take a lot of work but it is possible. With one large printer, you can produce two cubic metres of material in a day.”

If Macron is determined to go down a more traditional way of construction, specialised labour to reconstruct will certainly be part of the delay. Jean-Claude Bellanger, secretary-general of Les Compagnons du Devoir, an organisation that provides training in manual trades, estimated to Associated Press that at least 400 craftsmen would need to be trained. They would become master stone-cutters, woodworkers, quarrymen, roofers, sculptors and other craftsmen.

This type of labour simply isn’t available in France, and Bellanger estimates it would take up to a decade to train a French team. This is before they even lift a hammer to start the reconstruction itself.

And then there is the issue of materials. The fire at Notre-Dame, which was built in the 12th and 13th centuries, destroyed most of the section known as ‘the forest’. This comprised heavy wooden medieval oak beams. There is probably no country in Europe with large enough trees today, so they would have to be sourced from further afield.

The stone is also a problem. The type used in Notre-Dame and in many iconic Paris buildings is called Lutetian limestone, or ‘Paris stone’, and it has that warm grey light. The main quarry for this stone stretched back from the Left Bank of the Seine and is now buried under the city.

Concr3de would be focusing on the stone, as it is difficult to recreate wood with 3D printing.

In more positive news, though, the original design of the church has been preserved. As explained by Geboers, American professor Andrew Tallon did a full 3D scan of the cathedral back in 2000 and Concr3de would use this scan as their starting point.

Private donors have already pomised almost one billion euros for reconstruction, and the number continues to climb. Prime Minister Édouard Philippe has said that the government will present legislation to ease the bureaucratic obstacles that usually delay construction projects in France.

Geboers confirms there would be a lot of change left over from the billion euros fund. “Our methods are not at all an expensive process, certainly a lot cheaper than more traditional methods.”

The Rotterdam-based firm has already produced a sample replacement gargoyle using the technique it has proposed. Using scans of the gargoyle that were readily available online, they created Le Stryge, a demon statue that sat on the roof of Notre-Dame. The sculpture has been remade in a mixture of limestone and ash, materials similar to those left by the fire.

Le Stryge recreated with 3D printing

Geboers is quick to point out that their process would just be one step in the reparation of the cathedral. “Printing the material is obviously only part of the procedure," he said. "We would also have to collaborate for the design, the preparation and of course the installation of the pieces.

“We would like Notre-Dame to rise from its ashes like a phoenix. The fire is now part of its long history. The building should show its layered history proudly, and show the world that it has conquered it. The fire can also be the future of Notre-Dame.”

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