The stone vault in the roof of Notre Dame means it was more resilient to fire than many other cathedrals but heat may still have warped the building’s stonework
Source:
https://www.newscientist.com/article/2199991-notre-dames-stonework-isnt-flammable-but-may-be-structurally-damaged/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home