NFPA 13 Chapter 13 addresses special hazard areas with elevated fire risk. High-piled storage (exceeding 12 feet height) requires in-rack sprinklers between shelves in addition to ceiling sprinklers. Class III and IV commodity storage (higher hazard) requires higher design density. Flammable liquid areas require higher discharge density. Paint spray booths require higher protection than general manufacturing. Sprinkler head placement accommodates storage racking while maintaining spray pattern effectiveness.