A huge forest of scaffolding, fused by the fire in April, has to be cut away

The restoration of the cathedral of Notre Dame in Paris, which was badly damaged by fire on 15 April, has entered a new and delicate phase. This involves removing a vast and heavy scaffolding structure at roof level that became fused by the intense heat. It had been erected before the fire in order to carry out restoration work on the 19th-century roof spire, whose dramatic collapse was seen on screens around the world.

Rendering of the system put in place for the removal of the scaffolding
Rendering of the system put in place for the removal of the scaffolding

The removal of the scaffolding requires three levels of steel beams to be positioned around its exterior to form a stabilising “belt”. Once this operation is complete, the same firm that built the scaffolding (Europe Echafaudage) will start to dismantle it, using telescopic crawler cranes that will allow roped technicians to descend into the forest of pipes and gradually cut them away after having coated them with a protective layer to avoid spreading the pollution caused by the melting of the lead roof. Work is expected to be complete next April. 

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The “parapluie roulant”, a temporary sliding roof
The “parapluie roulant”, a temporary sliding roof - The vaulting of the north transept has proved to be structurally sound. It was protected by a layer of plaster and the fact that the roof beams of the two transepts dated from the 19th century and were much lighter than those of the nave’s medieval roof may have helped contain any damage.  The state of the nave vaulting will now be assessed, and to speed this up, two temporary sliding roofs (parapluies roulants), one for the nave and one for the choir, will be installed over the wooden platform recently positioned above the vaults. The transept crossing presents particular difficulties because this is where the roof and the vaults completely collapsed during the fire, leaving parts of the roof beams hanging. These could fall down and further damage the building.