BCD SPECIAL REPORT ON HISTORIC CHURCHES 32nd ANNUAL EDITION 15 number of times that you can clean a building to this degree without causing significant harm to its form and fabric. THE ROOF For the reconstruction of the roof timbers, the decision was taken to follow the medieval joinery method closely, using the original materials and techniques. Craftspeople trained on the Guédelon project, where a medieval castle is being built using 13th-century methods, were brought in to advise, and the carpentry firms which specialise in the use of hand tools for the conversion of the timbers were contracted to make the timber work and not rely on electric saws. Viollet-le-Duc’s timber-framed flêche, which formed the central spire of the cathedral, was completed in February 2024 and the last trusses were installed a month later. The spire is now adorned with elaborate leadwork, which will be discussed in a further article in the next edition of Historic Churches, and a gilded copper rooster. The original rooster survived the fire but was too badly damaged to be reused, and is now on display in the cathedral below as a symbol of what was lost. FIRE PROTECTION Perhaps the most significant change to Notre-Dame is a comprehensive new fire protection system with over 300 fire detection points, including thermal cameras and an air suction and analysis system in constant operation. Any outbreak detected by at least two sensor pipes will automatically trigger a water misting system. This can reduce temperatures dramatically within a minute, with minimal water damage because of the relatively low volume of water. A new network of dry risers has also been installed which is designed to deliver three times the volume of water of the previous system. Other safeguards included fire compartmentation. Fire barriers introduced at key points now divide the roof into three separate spaces, so a fire can no longer spread quickly through the roof timbers from one end to the other. The thickness of the wooden boarding which separates the trusses from the lead roofing has also been increased by 15 mm, increasing the time it takes for a fire to spread from one side to the other by up to 15 minutes. The result is a cathedral that appears as it always has – ancient, soaring, and sublime – but is now better protected and better understood than at any moment in its 860-year history. However, the unique circumstances surrounding the project gave those financing the restoration a degree of control over the restoration that was unprecedented, determining both the timescale and the philosophical approach. Some would argue that the whole building looks new and that it is no longer possible to tell original from modern. For others, the new work is simply a continuation of the old, preserving its significance. AUTHORS: this article was researched and prepared by the Cathedral Communications editorial team, Jonathan Taylor and Joanna Collie Meticulously cleaned stonework in the nave glows with light, reflecting the aims of the architect that the work would be ‘luminous’ The opportunity was taken to replace plain glazing in the clerestory windows with modern glass to an abstract design
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