Building occupancy classifications
Building occupancy classifications refer to categorizing structures based on their usage and are primarily used for building and fire code enforcement. They are usually defined by model building codes, and vary, somewhat, among them. Often, many of them are subdivided. Classifications by Group. The following is based on the International Building Code, the most commonly used building code in the United States: Other Considerations. Many buildings may have multiple occupancies. These are referred to as "mixed occupancies" and the different parts will be required to meet the codes for those specific areas. An example of this is  a shopping mall with underground parking. The shopping area itself is Group M (mercantile), while the parking area would qualify as Group S (storage). In places where more than one occupancy may apply, the stricter code is usually enforced. An example of this is a restaurant with seating under 50 which is not addressed in the code as either mercantile or business (this is a technical issue, but could be viewed as either or neither). Code enforcement officials will usually enforce the stricter side of the code.