BCD SPECIAL REPORT ON HISTORIC CHURCHES 32nd ANNUAL EDITION 13 RISING FROM THE ASHES The cleaning and restoration of Notre-Dame, Paris A faithful replica of Viollet le Duc’s spire emerges from the scaffolding (All photos: Jonathan Taylor) ON THE evening of 15 April 2019, flames consumed the roof of Notre-Dame de Paris, one of the great masterpieces of Gothic architecture. The fire, almost certainly ignited by an electrical fault during ongoing renovation work, spread with terrifying speed from the scaffolding surrounding the spire through the medieval timber framework of the roof. Within two hours the 96-metre spire, rebuilt in the 19th century by architect Eugène Viollet-le-Duc, had collapsed in a shower of sparks and molten lead, crashing through the stone vault of the transept below. Twothirds of the lead roof was destroyed. President Emmanuel Macron almost immediately pledged to restore the cathedral to its former glory within five years. Incredibly, that promise was kept. Notre-Dame reopened on 7 December 2024 after a restoration effort involving more than 2,000 skilled craftspeople and expenditure of around 840 million euros raised from 340,000 donors in over 150 countries. STABILISATION AND CLEANING The first two years after the fire were devoted to careful survey and analysis, a massive cleanup operation to remove tons of debris, and emergency works to safeguard what had survived. Enormous timber props were erected to brace the surviving walls which had lost the structural integrity provided by the roof against the flying buttresses. Inside the building, the lead particulates left by the melting of four hundred tons of roof covering had coated every surface in toxic residue and had penetrated into every crack and crevice. Specialist teams wearing full PPE (including hazmat suits and micro-filtered respirators) removed tons of lead-contaminated debris and dust. Once the structure was deemed safe, the complex work began of reinstating what had been lost and consolidating and cleaning what had been damaged. The stone predominantly used to construct the building was the pale Lutetian limestone which had been quarried locally. The stone was relatively porous and had been affected by centuries of wind, rain and weathering, pollution, exploitation by natural organisms, and now the fire. As well as the effects of heat and surface contamination by the various chemical residues, the soft porous limestone had also been exposed to saturating conditions from the fire hoses, mobilising salts and exposing the masonry to the risk of salt crystallisation damage as the masonry dried out, as well as rust expansion from hidden metal cramps. Cleaning was necessary to remove the contaminants and to help identify areas that needed repair, as well as being needed aesthetically essential. Cleaning methods had to be carefully selected to minimise further loss of historic fabric, but also to suit the brief set by the president and those funding the restoration. For the broad areas of plain masonry with little exposure to soot staining, the primary technique was micro-abrasives
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