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Author(s): Ron Cote. Published on January 4, 2016.

Mixed Approach

The AHJ has final say in mixed-occupancy protection. BY RON COTÉ

Food trucks are a current rage. An education session at the NFPA Conference & Expo last June, as well as a related story in NFPA Journal, focused on food trucks via a review of applicable provisions of NFPA 96, Ventilation Control and Fire Protection of Commercial Cooking Operations, along with Chicago’s innovative permitting process.

A question on a related topic recently landed within the NFPA life safety group. The inquiry asked for guidance on occupancy classification—for purposes of applying NFPA 101®, Life Safety Code®—of a storage container that had been repurposed as a kitchen, food preparation, and sales area. Service windows are provided for order taking and passing food to customers outside the container. The structure, unlike a mobile food truck, is permanently fixed in place.

An industrial occupancy classification should provide adequate protection for the workers inside the container, but I was uncomfortable with the gaps that classification might leave for customer protection. For example, customers should be protected from the hazards associated with fuel cylinders, such as the propane tank that exploded on a food truck in Philadelphia in 2014, killing a mother and daughter who were working in the truck and injuring a dozen people, some of whom were set afire. I offered that an occupancy classification of mercantile or one of mixed occupancies—part mercantile and part industrial—would be better than that of an industrial occupancy alone.

My opinion was based on the code provisions, applicable to occupancies other than industrial, requiring occupants to be protected from any contents that are relatively more hazardous than those typically associated with the occupancy. The industrial occupancy chapter provisions, in contrast to those of the other occupancies, require occupant protection from high-hazard operations or processes. Other code provisions require all occupancies to be protected from the hazard of commercial cooking equipment in accordance with NFPA 96.

A code provision applicable to multiple-occupancy buildings allows mercantile, business, industrial, and storage occupancies to be considered incidental to the predominant occupancy. In applying this provision, the code user needs to be careful not to defer to an industrial occupancy classification just because it comprises the greater floor area. For example, in a building where 20 percent of the floor area is used as business and 80 percent as industrial, the business occupants might not be adequately protected if the entire building is classified as an industrial occupancy.

I’ve had discussions with authorities having jurisdiction (AHJs) that led them to classify the business and industrial building addressed above as a multiple-occupancy building—part business occupancy and part industrial occupancy. Then, where the mixed occupancies form of protection is utilized, the shared exit access paths must be protected against relative hazards that do not necessarily rise to the category of high hazard—something the industrial occupancy requirements alone would not do.

The mixed-occupancies form of protection requires that the structure comply with the most restrictive requirements of the occupancies involved, unless separate safeguards are approved. Contrast that with the separated occupancies form of protection, where each occupancy meets only the requirements to which it is subject; in this method, the distinct occupancies are required to be completely separated from each other by fire barriers.

The life safety technical committee wisely included code text making occupancy classification subject to the AHJ’s ruling in cases where there is a question of proper classification.

​RON COTÉ, P.E. is principal life safety engineer at NFPA.