Two or more classes of occupancy exist in a building; this is referred to as which term?

• A. A building with a single class of occupancy.
• B. A building designed for non-residential use only.
• C. A building with mixed use but identical occupancy.
• D. A building or structure in which two or more classes of occupancy exist.

Answer: (D)

The main idea is that when a building contains more than one occupancy class, it is described as mixed occupancy. This term is used in life safety codes to recognize that different parts of the structure have different fire hazards, means of egress needs, and protection requirements. Because two or more occupancy types are present, the design and safety provisions must account for all of them, often requiring separation between occupancies with fire barriers and applying the most stringent life safety features where spaces are shared or connect. For example, a building with a restaurant (high hazard/assembly) on one side and offices (lower hazard) on another imposes protections that accommodate both uses, rather than treating the whole building as one simple occupancy. The other descriptions do not fit because they describe single occupancy, non-residential use without multiple classes, or a mixed-use scenario where the occupancy classification remains the same throughout, which is not the case here.