Trusses Raised for Notre Dame Cathedral Rebuild

FRIDAY, JULY 14, 2023


Earlier this week, the oak trusses for the new Notre Dame Cathedral roof were raised into place, marking a huge milestone in reconstruction efforts.

On the evening of April 15, 2019, flames engulfed the more than 850-year-old Notre Dame Cathedral, destroying the spire and nearly two-thirds of the roof. Since then, design, restoration and reconstruction efforts have been underway, with a goal to reopen the cathedral by the end of 2024.

Roof Rebuilding Process

Last month, it was reported that the roof of the cathedral is being rebuilt using medieval woodworking techniques. The reconstruction reportedly hit a milestone when large parts of the new timber frame were assembled and erected at a workshop in western France.

Before the fire, the wooden lattice structure underneath the cathedral's lead roof was known as the “forest.” It was made up of old oak trees that were added to the cathedral between 1220 and 1240. 

Its dimensions reportedly measured more than 300 feet long, 42 feet wide and the transept was over 30 feet tall. Before it collapsed in the fire, it was considered one of the oldest frameworks in Paris.

As part of the reconstruction efforts, workers installed 26 timber frames, known as “bents” or “trusses.” According to the Friends of Notre-Dame de Paris, in March 2020, 1,000 oak trees were cut from roughly 200 French forests to make the frame for Notre Dame Cathedral’s roof and spire.

These trees were reportedly selected through a “painstaking process” in January and February 2020 to fit the precise requirements defined by the chief architects in charge of restoration. The oak trees are roughly 150 to 200 years old, with some standing over 60 feet tall.

The wood was then dried for 12 to 18 months to make sure it does not shrink or move once in place. The Associated Press reported that crews worked with hand axes to fashion the beams for the framework, just like their predecessors’ work back in the 13th century.

The goal of hand tool use for the rebuild is to pay tribute to the craftsmanship of the cathedral’s original buildings, as well as ensure that the “centuries-old art of hand-fashioning wood lives on.” Additionally, carpenters and architects are reportedly using computer design and other technology to speed up construction. Computers were used in the drawing of plans to help ensure that their hand-chiseled beams fit together perfectly.

In May, crews assembled and erected large parts of the new timber frame at a workshop in the Loire Valley, France. The “dry run” reportedly assured architects that the frame is fit for purpose and the next time it is anticipated to be put together will be on top of the cathedral. 

Latest Milestone

On Tuesday (July 11), a crane lifted the trusses from a barge to be guided by ropes and set around the area of the spire. The event reportedly drew crowds along the bridge over the Seine River and its banks, eliciting “oohs” as the first of the six pieces were lifted onto the roof.

“I think it’s a magical moment for a lot of Parisians this morning,” said Transport Minister Clement Beaune.

Each truss reported weighs 7 to 7.5 tons. The forêt will be formed for the cross-shaped roof that ran the length of the nave and transept above stone vaults, and a total of 25 triangular structures across the base will make up part of the cathedral’s charpente, or its essential framework.

Jean-Louis Bidet, the technical director of the Perrault atélier in Normandy, which has been rebuilding the roof frame, had earlier said the pieces of la forêt had been put together “as if they were in their permanent position at the top of the walls of Notre Dame” in a trial run at the company workshop several weeks ago.

“We assembled them to verify they were as they should be,” Bidet told French television.

A statement said the cathedral’s silhouette, now covered in scaffolding, should emerge on the skyline as work advances. The 96-meter-tall spire is also reportedly being reconstructed as it was before the fire.

Gen. Jean-Louis Georgelin, appointed by French President Emmanuel Macron to oversee the reconstruction, said that even the heavy traffic expected during the summer Paris Olympic Games won’t stop work on the cathedral.

“We will work for the cathedral during the Olympics in order to be ready in December 2024,” he said. “This is our goal.”

2024 Opening Date

In March, French officials announced plans to reopen Notre Dame at the end of 2024, less than six years after the building caught fire in which its iconic spire and nearly two-thirds of the roof were destroyed.

The Associated Press reported that the reconstruction is going fast enough that officials plan to reopen the structure to visitors in December 2024, in line with President Macron’s goal. However, the opening will be too late for the Paris Olympic Games as originally planned.

While work is ongoing, a free exhibition is currently open to visitors in an underground facility in front of the cathedral. “Notre-Dame de Paris: at the heart of the construction site” highlights ongoing operations on the site, as well as the expertise and skills of workers. It also reportedly features some remains from the fire and works of art from the cathedral.

Culture Minister Rima Abdul-Malak stressed, however, that renovations will still be ongoing in 2025. About 1,000 people are currently working to rebuild Notre Dame, with plans to be “faithful to the original architecture,” including “sticking to the materials and construction methods” of medieval times, said Philippe Jost, managing director of the government agency overseeing the reconstruction.

   

Tagged categories: Architecture; Asia Pacific; Construction; Design; Design - Commercial; EMEA (Europe, Middle East and Africa); Historic Preservation; Historic Structures; Latin America; Maintenance + Renovation; North America; Ongoing projects; Program/Project Management; Projects - Commercial; Restoration; Restoration; Roofs; timber; Wood; Z-Continents

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