Historic Churches 2019

26 BCD SPECIAL REPORT ON HISTORIC CHURCHES 26 TH ANNUAL EDITION WHY NOTRE DAME CAUGHT FIRE The exact cause of the fire at Notre Dame has yet to be determined and an investigation is ongoing, but at the time, renovations were being undertaken to the cathedral’s central spire. Construction sites can create a hazardous environment in terms of fire safety for many reasons: an increased number of electrical and ignition sources through the use of temporary power supplies and hot works such as the heating of lead; doors being propped open while works are under way, potentially interfering with fire separation systems; disabling alarms to avoid falsely triggering them with dust; and smoking on site, to name a few. One of the theories that has been circulating in reports since the incident suggests that the fire was started by an electrical short-circuit. Some sources have speculated that this could be related to the electrified bells in the cathedral beneath the spire and in the dry timber beamed attic known as the ‘forest’. At this stage in the investigation the accuracy of this, and any other theory on the fire’s origin, can’t be confirmed, but we do know that once the building’s roof caught fire, it continued to burn. Notre Dame’s roof was a massive timber structure in an enclosed and extremely dry environment, making it highly susceptible to fire and causing it to take hold very quickly. This, in conjunction with the fire’s roof-top location and the inability to drop water from the air for fear of causing further damage to the building’s structure, made it particularly challenging for firefighters to tackle on their arrival. Interestingly, Notre Dame did have a fire alarm system in place but clearly it is not fit for purpose. It has emerged in a number of news reports that the alarm was not equipped to notify emergency responders immediately when a fire was detected. Instead it was left up to a guard to investigate the cause of the alarm before contacting the authorities. It has also been reported that the fire was mistakenly thought to have started in another part of the cathedral, before it was discovered in the attic after the alarm sounded a second time. Both of these factors resulted in a delay significant enough to allow the fire to become fully established and to spread before the first responders arrived on the scene. If a sprinkler system had been installed the fire could have been extinguished before there was any need to involve the fire service, and had fire barriers been installed in the roof space it is likely that the fire could have been contained, limiting the damage. But officials had decided not to retrofit Notre Dame with a sprinkler system or fire walls because ‘they were concerned electrical wiring would be too big a risk to the timber’, as reported by The New York Times . Of course, they may also have been concerned that retrofitting fire barriers in Notre Dame’s roof voids and attic would risk disfiguring the building’s original structure and fabric, preventing the appreciation of the ‘forest’. Certainly this is a factor that has to be considered, and it is all too easy with the benefit of hindsight The cathedral’s spire was completely destroyed as a result of the fire (Photo: LEVRIER Guillaume - Own work, CC BY-SA 4.0, http://bc-url.com/spire) Much of Notre Dame’s interior was damaged during the fire, but the three great rose windows (pictured before the fire took hold) remain intact (Photo: Alvesgaspar – Own work, CC BY-SA 4.0, http://bc-url.com/rose-window)