Ill. Admin. Code tit. 77, § 370.2360 – Hazardous Areas

a) Kitchens
b) Furnace and heater rooms
c) Laundries
d) Rooms or spaces, including repair shops, used for the storage of combustible supplies and equipment in quantities deemed hazardous by the authority having jurisdiction.

Walls at enclosure of hazardous areas shall have a one (1) hour fire resistive rating. Doors at enclosure of hazardous areas shall be a minimum three-fourth (¾) hour "C" label, with automatic closer. Hazardous areas include the following: