For the purpose of sprinkler design, a warehouse with moderately combustible contents stored to heights of 12 ft (3.6 m) is classified as an

According to NFPA 13, Standard for the Installation of Sprinkler Systems, hazard classifications are determined by the quantity and combustibility of the contents. An Ordinary Hazard (Group 2) occupancy is defined as one where the quantity and combustibility of contents are moderate to high. A key criterion for this classification is that stockpiles of combustible material do not exceed 12 ft (3.7 m) in height. A warehouse with moderately combustible contents stored to this height fits precisely within the definition of an Ordinary Hazard (Group 2) occupancy, which dictates the required sprinkler system design density and area of operation.

A. Ordinary hazard (Group 1): This classification is for occupancies where stockpiles of combustible materials do not exceed 8 ft (2.4 m).

C. Extra hazard (Group 1): This classification involves very high quantities of combustibles or the presence of flammable liquids, which is beyond "moderately combustible."

D. Extra hazard (Group 2): This classification is for occupancies with substantial amounts of flammable or combustible liquids or materials that burn with extreme rapidity.

1. National Fire Protection Association (NFPA). (2022). NFPA 13, Standard for the Installation of Sprinkler Systems. Section 4.3.3.2, "Ordinary Hazard (Group 2)."

2. Cote, A. E. (Ed.). (2008). Fire Protection Handbook (20th ed., Vol. 2). National Fire Protection Association. Section 17, Chapter 2, "Automatic Sprinkler System Design," pp. 17-20 - 17-21.

3. Oklahoma State University, Fire Protection and Safety Engineering Technology. (n.d.). FPST 3333 - Fire Protection Systems [Courseware]. Module on Sprinkler System Design Criteria. (Discusses NFPA 13 hazard classifications, noting the 12 ft storage height for OH2).