Section 703
SECTION 703. Mixed Occupancy. (a) General Requirements When a building is of mixed occupancy or used for more than one occupancy, the whole building shall be subject to the most restrictive requirement pertaining to any of the type of occupancy found therein except in the following: (1) When a one-storey building houses more than one occupancy, each portion of the building shall conform to the requirement of the particular occupancy housed therein and; (2) Where minor accessory uses do not occupy more than ten percent of the area of any floor or a building, nor more than ten percent of the basic area permitted in the occupancy requirements, in which case, the major use of the building determine the occupancy classification. (b) Forms of Occupancy Separation Occupancy separations shall be vertical or horizontal or both, or when necessary, of such other forms as may be required to afford a complete separation between the various occupancy divisions in the building. (c) Types of Occupancy Separation Occupancy separation shall be classified as "One-Hour Fire- Resistive", "Two-Hour Fire Resistive", "Three-Hour Fire- Resistive" and "Four-Hour Fire-Resistive: (1) A "One-Hour Fire-Resistive Occupancy Separation" shall be of not less than one-hour fire-resistive construction. All openings in such separation shall be protected by a fire-assembly having a one-hour fire-resistive rating. (2) A "Two-Hour Fire-Resistive Occupancy Separation" shall be of not less than two-hour fire-resistive construction. All openings in such separation shall be protected by a fire-assembly having a two-hour fire-resistive rating. (3) A "Three-Hour Fire-Resistive Occupancy Separation" shall be of not less than three-hour fire-resistive construction. All openings in walls forming such separation shall be protected by a fire assembly having a three-hour fire- resistive rating. The total width of all openings in any three-hour fire-resistive occupancy separation wall in any one-storey shall not exceed 25 per cent of the length of the wall in that storey and no single opening shall have an area greater than 10.00 square meters. All openings in floors forming a "Three-Hour Fire-Resistive Occupancy Separation" shall be protected by vertical enclosures extending above and below such openings. The walls of such vertical enclosures shall be of not less than two-hour fire-resistive construction, and all openings therein shall be protected by a fire- assembly having a three-hour fire-resistive rating. (4) A "Four-Hour Fire-Resistive Occupancy Separation" shall have no openings therein and shall be of not less than four-hour fire resistive construction. (d) Fire-Rating for Occupancy Separation Occupancy Separations shall be provided between groups, subgroupings, or divisions of occupancies. The Secretary shall promulgate rules and regulations for appropriate occupancy separations in buildings of mixed occupancy: Provided, that, where any occupancy separation is required, the minimum shall be a "One-Hour Fire-Resistive Occupancy Separation"; and where the occupancy separation is horizontal, structural member supporting the separation shall be protected by an equivalent fire-resistive construction.