12. (1) Public buildings, and all accessories thereof, moveable or immoveable, shall be so erected and kept that the lives of all persons residing therein or having access thereto shall be effectually protected against accidents.
(2) They shall be provided with all means necessary to permit a prompt and easy exit therefrom of the occupants or of the public in case of an alarm of fire or a panic.
(3) Every building of three or more stories, and every school building, shall be provided with safety appliances on the outside, such as iron stairs, safety tubes of canvas or metal, or other means of escape in case of fire, approved or prescribed by the inspector. This provision shall not apply to any public building that is fire-proof to the satisfaction of the inspector.