Notre-Dame de Paris’s structure is one of the oldest in Paris, along with Saint-Pierre de Montmartre (1147), the principal remains of the great Dames de Montmartre abbey founded by Queen Adelaide of Savoy, who was married to King Louis VI the Fat, and parts of Saint-Germain des Prés (1160-1170).
This building has been given the romantic name of “the forest” because for many of the beams used to build it, each beam came from a different tree. The structure is made from oak. Its dimensions are very impressive: 120 m long, 13 m wide at the nave, 40 m in the transept and 10 m high.
Technically, the gothic arches required sharply-sloped roofs. Notre-Dame de Paris’s roofs are at a 55° incline. In addition, as framing timber became less common due to deforestation and urban development at the time, it was necessary to use weaker and lighter cutting wood, which made it possible to erect the structure and increase its incline.
The first choir structure was built using wood cut around 1160-1170 (some of these trees could have been 300 to 400 years old, coming from trees planted in the 8th or 9th centuries!!!). This first structure did not last, but the wood was reused in the second structure built in 1220. The wood is still there today. Why was the second structure built?
The first structure may have been destroyed in a fire,
but the main reason it was rebuilt was to make room for the 2.70 m goutterot wall in the choir, to match the nave wall,
and to make room for larger, taller windows.
The nave structure was built between 1220 and 1240. Work in the nave began in 1182, after the choir was dedicated. Some people believe it may have begun in 1175, before the dedication. Work stopped after the fourth bay was built, leaving the nave unfinished, but façade construction started in 1208. Nave construction would start again in 1218, to strut the façade.
This structure supports a lead roof composed of 1326 tiles, each measuring 5 mm thick, for a total weight of 210,000 kg. In the 11th and 12th centuries, church roofs were covered with flat tiles coming from abundant clay deposits. These deposits were far from Paris, so lead became the material of choice. In 1196, the bishop Maurice de Sully willed 5,000 pounds for purchasing lead.
The choir and nave structures have lasted centuries, but the transept and spire structures were rebuilt in the mid-19th century during the great cathedral restoration campaign led by Viollet-le-Duc. These structures were built according to the standards of the day, differing from the choir and nave structures, in particular because their beams are much larger and spaced apart than medieval beams. the choir bay structure