Cathedral Fires
The Notre-Dame fire brought the world together to witness the feelings of sadness and helplessness caused by the unstoppable spread of fire through the roof of this iconic heritage building. Commentators made observations on how the fire should be fought, from Donald Trump suggesting they should use an aeroplane to dump water on it, to the author’s comment that it would take a brave fire officer to stop putting water on the flames. A project has commenced by Oxford University to understand what effect heat has on the compressive strength of limestone and what this means for the structural stability of English cathedrals when involved in fire.
Cathedral fires that destroy the roof are fairly rare, occurring only about 54 times in 3500 cathedrals worldwide since 998 AD. France seems to have suffered more than other countries in recent times with cathedral roof fires in Nantes in 1972 (St Pierre and St Paul), 2015 (Basilica Donatien) and 2020 (St Pierre and St Paul again!).
Encouragingly only six of these 54 cathedrals weren’t rebuilt or restored. Often building works are the most common cause of these fires.
The only recorded loss of life were:
Church of the Company, Santiago, Chile 1863
Church of the Holy Blood, Holyoke, Massachusetts, USA, 1875
Grue Church, Norway 1822.
The Church of the Company, Santiago, Chile in 1863 was particularly infamous due to the extraordinary loss of life, estimated at between 2000 and 3000, although only 2000 females were positively identified. Drapes, flags and thousands of candles and lamps contributed to the speed and severity of the fire. The women were segregated with an iron fence from the men, who all escaped safely, as did the clergy who locked the rear doors to save the valuable artefacts. Hooped skirts, the locked rear doors and a degree of panic hampered their escape. News of this tragedy spread around the world and it probably contributed to improvements to fire safety in public buildings in the UK.
The terrible catastrophe at Santiago the capital of Chile in South America, ought to teach a lesson in the construction of churches and public buildings. The place was crowded with more than three thousand women and a few hundred men, and of these about two thousand perished.
It has more than once occurred to us that the large Hall of the Mechanics' Institute ought to have had another door and staircase. When the hall is filled, a considerable time is required for the audience to file, though the door is wide and the stair capacious. But in the event of a rush from any cause, some would incur the danger of being crushed, or trampled to death. To prevent the possibility of such a disaster, it might be considered wise to substitute a stair for the present small room at the south-west end of the Hall.
Grue Church in Norway was not a Cathedral, but is relevant because of the impact of the fire. It was a large wooden Stave church holding its last planned service as it was threatened by the movement of the nearby river. The fire was thought to have been started by sunlight passing through or reflecting from glass and setting fire to the 17 tons of pine tar had been applied to the exterior of the building over the previous two hundred years.
Most of the 500 congregation escaped, but 116 people died as they pressed against the double doors, which opened inwards.
Some escaped following the pastor, Hesselberg, who, piled bibles up against a window and jumped to safety.
Hesselberg was Roald Dahls’ great-great grandfather. He eventually became a member of parliament and worked to ensure that all doors in public buildings opened outwards. This was adopted throughout the Scandinavian countries, but caused problems when the king of Norway, Kristján X visited Iceland and decreed that their churches had to make their doors open outwards. A congregation became trapped when snow fell during the service, preventing the door from opening, illustrating that not all buildings are the same, so the order had to be rescinded.
The Notre Dame fire was the catalyst for the Oxford project which started as an investigation into the compressive strength of limestone when exposed to the temperatures reached in fires.
It quickly became apparent there were so many variables to the propensity for the vaulting to fail that studies would have to be undertaken on the following subjects
The type of stone the cathedral and vaults are constructed of.
Testing these different stones in a furnace.
The type of vaults used in cathedrals (quadripartite. sexpartite, fan etc.).
The span, height and thickness of the arches to give the factor of safety.
The type of buttressing used (pier or flying buttress).
Structural engineering of masonry and pathology of defects.
Fire engineering to determine the fire load of the wooden roof structure.
Fire fighting techniques.
The results of the project are expected late 2022.