Extra (high) hazard occupancies shall be classified as locations where the quantity and combustibility of Class A combustible material is high or where high amounts of Class B flammables are present and rapidly developing fires with high rates of heat release are expected. These occupancies consist of fire hazards involved with the storage, packaging, handling, or manufacture of Class A combustibles and/or the total quantity of Class B flammables expected to be present in more than 5 gal (18. 9 L) in any room or area.