Historic Churches 2022

BCD SPECIAL REPORT ON HISTORIC CHURCHES 29TH ANNUAL EDITION 3 PROGRESS AT NOTRE DAME up the roof structure was measured. This is important according to Fromont, because the roof structure should behave in the same way as the old one, and this will only happen with the precise measurements. The destruction of the roof has revealed that medieval builders used iron staples to bind the stones forming the tops of the walls together. This was so the immense weight of the timber wall plates and roof structure could not push the stones out of place. Carbon-dated to the 13th century, it was the first time this method had ever been used in Gothic architecture. The restoration faced a major additional problem due to salt damage in the porous limestone of the vaulting. The rainwater and water from the fire hoses had soaked into a layer of plaster placed over the vaulting by 18th and 19th century conservators in case of fire. While the plaster worked as designed and protected the vaulting from fire damage, salts from the plaster were drawn into the limestone by the water. Evaporation has led to salt crystallisation within the pores, causing degradation of the limestone. To draw out the salts, a water-based clay poultice was sprayed onto the vaulting so any further crystallisation will now occur in the poultice layer, not the limestone. The poultice will stay in place until completely dry, despite the 2024 deadline for re-opening the cathedral. At present the interior is undergoing a deep clean to remove lead dust. An estimated 460 tonnes of toxic dust was sent into the air by the fire, and afterward, work was stopped for a month to allow ‘decontamination’ to be carried out. Workers in hazmat suits are cleaning the stonework with soft brushes and vacuum machinery, a task projected to take eight months. UNESCO conducted a joint Advisory mission to the site in March this year, at the invitation of France in response to the World Heritage Committee’s recommendations (Decision 44 COM 7B.46), with the main objective being to assess the restoration and redevelopment programme. The recommendations from the mission will provide France with guidance in continuing the work as this unique and beautiful building is brought back to life and its doors re-opened. Progress can be followed on the Friends website, www. friendsofnotredamedeparis.org . Work to rebuild and restore the cathedral of Notre Dame is continuing after the devastating fire of 2019 destroyed two- thirds of its medieval roof and its huge flèche – the spire in the centre designed by Eugène Viollet-le-Duc. The north tower was partially burnt, while the walls of the nave, choir and two transepts suffered water damage and were left structurally unsound. With the ‘safety phase’ completed in 2021, where material at risk of collapse or endangerment to the public was removed, the focus is now on reconstruction and restoration. The president’s plan, developed shortly after the fire, is to re-open the cathedral to the general public in 2024. It is an ambitious schedule. The roof is over 90 metres in length and just under 13 metres in width, and around 1,000 oak trees have already been felled for the reconstruction of its ‘forest’ of timber roof trusses which supported the lead roof and its flèche. The oak is being aged for 12–18 months to minimise shrinkage and movement once in place. Complete replication of the roof structure is possible thanks to detailed studies made back in 2014 by chief architect Rémy Fromont, when every wooden beam that made The fire (Photo: Marin Dacos, CC BY-SA 4.0 bc-url.com/commons-wiki-notredamefire )

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