Carpenters are working at a frenzied pace to finish repairing Notre Dame Cathedral

A MARTÍNEZ, HOST:

Notre Dame Cathedral is set to reopen by December of 2024, five years after the Paris landmark caught fire. NPR's Eleanor Beardsley visited one of the many restoration projects, where experts are rushing to finish on time.

ELEANOR BEARDSLEY, BYLINE: The wooden structure supporting Notre Dame's roof was so vast it was known as the forest. It burned like a forest, too.

(SOUNDBITE OF AX CHOPPING)

BEARDSLEY: At this 250-year-old carpentry company in France's Loire Valley, they're busy reconstructing it, but you don't hear the whirring of electric saws. It's the chopping of axes that resounds. The oak trees are transformed into long, square beams by hand. Carpenter Joseph Canuel explains.

JOSEPH CANUEL: (Through interpreter) We made roofs well before saws and sawmills existed, and this is how it worked. You got the wood in the nearby forest, like we're doing. And, yes, we could easily cut this log into two long planks. But keeping the wood fibers the whole length of the beam gives it more resistance.

BEARDSLEY: This company devotes itself to France's historical monuments, so its carpenters are used to working with traditional methods. Still, Notre Dame is special, says CEO Jean-Baptiste Bonhoure.

JEAN-BAPTISTE BONHOURE: We've never done something like that before. The roof frame is dating from the medieval - the 12th century, and especially just the big volume of wood.

BEARDSLEY: He says the nave and choir roof needs some 1,400 oak trees. Peter Henrikson is a carpenter from Minnesota who heard about an opportunity to work on Notre Dame through the organization Carpenters Without Borders, a group reuniting those who share a love of traditional methods. He says these hand-hewn trusses are special.

PETER HENRIKSON: Taken from the round tree to a squared timber all by hand, all with axes - all these timbers are what's called boxed heart. So the middle of the tree is in the middle of the timber.

BEARDSLEY: Notre Dame's charpente, or roof frame, won't be seen by anyone, says Henrikson. So they could have used faster modern techniques.

HENRIKSON: But a lot of people involved with the historic monuments, historic buildings of France, are really enamored with the traditional way of doing it and want to preserve that. And part of redoing the roof as it was is keeping those skills alive.

BEARDSLEY: He's using an ax, a little hatchet, to really make a smooth line.

Edouard Cortes is another carpenter here. He removes parchment-thin layers of wood with his ax, which he says was hand forged in the traditional way to resemble what Notre Dame's carpenters would have used.

EDOUARD CORTES: (Through interpreter) It leaves a magnificent mark on the beams, the same medieval mark found on the beams from Notre Dame. For me, it is a passion to work with such old tools. You work with your hand, your hatchet, your heart and your head.

BEARDSLEY: OK. So they're about to lift up the structure.

A crane lifts one of the giant triangular frames and aligns it next to the others, a dry run before the final installation atop Notre Dame in the coming months. Then the removable metal pins connecting the trusses will be replaced by permanent wooden mortise-and-tenon joints. There won't be a single nail, screw or piece of metal in Notre Dame's roof frame.

JEAN-LOUIS GEORGELIN: We want to restore this scaffold as it was built in the Middle Age.

BEARDSLEY: Retired General Jean-Louis Georgelin is in charge of rebuilding Notre Dame. He says it's important to be faithful to the cathedral's original artisans. That spirit is imbuing the entire restoration.

GEORGELIN: You have people everywhere in France working to restore the stained windows, working to find the stones, working for the organ and here to build the framework, the spire and so on.

BEARDSLEY: To meet the five-year deadline, says Georgelin, they're combining these old methods with the most advanced computer design technology. We're restoring a medieval cathedral, he says, but Notre Dame will also be a cathedral for the 21st century. Eleanor Beardsley, NPR News, Saint-Laurent-de-la-Plaine. Transcript provided by NPR, Copyright NPR.