Fiber cement plates is definitely incombustible (A1 class incombustible building material according to EN 13501-1) due to materials in its structure. Only microcracks were observed on plates during sudden cooling after being exposed to 500 degrees of temperature for 2 hours. Therefore, there is no risk of fire and its spreading in buildings produced with fiber cement plates, because fiber cement plates will not burn even if they will be in direct contact with flames in high temperature.
Important note: Insuring buildings against fire is very important today, as is known. Many insurance companies do not insure buildings in which combustible products, products which accelerate fire or which emit poisonous or health threatening gases in high temperatures are used or insure them against very high premium. For this reason, fiber cement plates are now preferred especially under roofing material instead of wooden plates.