1. In every building used as a place of assembly for public amusement in which seats in rows are provided individual seats shall be provided for all persons congregating therein. The width of seats or chairs shall not be less than eighteen inches measured from center to center. Seats in rows, whether fixed or movable, except in boxes or loges not exceeding sixty square feet in area and in existing balconies of concrete construction having fixed seats, shall not be less than twenty-eight inches apart from back to back. The number of seats in any row, extending from one longitudinal aisle to another, shall not exceed eighteen, so that no seat shall have more than eight seats intervening between it and an aisle, and the number of seats extending from a wall to a longitudinal aisle shall not exceed nine; provided, however, that if the seats are fixed chairs with self-raising seats, so spaced that when the seats are raised there is an unobstructed space of not less than eighteen inches horizontal projection between the rows of seats, and if doorways leading directly to exit corridors are provided not more than five feet apart along the sides of the auditorium, the number of seats in a row may be not more than twenty-five. In buildings regularly used as places of assembly for theatrical, operatic or similar performances or for the display of motion pictures, the seats, except in boxes or loges not exceeding sixty square feet in area, shall be fixed and shall be separated by arms. In boxes or loges, not exceeding sixty square feet in area, and in other locations where loose chairs are permitted, not more than one chair shall be provided for each six square feet of floor space.
2. Every aisle shall lead to an exit door or to a cross aisle; that is, an aisle running parallel with the seat rows and leading to an exit door. No main floor longitudinal aisle of expanding width shall be less than twenty-seven inches wide at any point and where such means of exit accommodates more than one hundred and eighty persons the width thereof shall be increased. Main floor longitudinal aisles increasing gradually in width in the direction of exit travel shall be of such width that the number of persons to be accommodated at any point does not exceed one hundred and twenty persons per eighteen inches of width. If main floor aisles are of a constant width, in theaters having a capacity of four hundred and fifty seats or less on the main floor, the width of the aisles shall be not less than thirty-two inches; in theaters having a capacity of more than four hundred and fifty seats but less than seven hundred and fifty seats on the main floor, the width of the aisle shall be not less than thirty-six inches; and in theaters having a capacity of more than seven hundred and fifty seats on the main floor, the width of the aisle shall be not less than forty-two inches. Main floor aisles having seats on one side only shall be not less than twenty-eight inches wide in theaters having a capacity of four hundred and fifty seats or less on the main floor; not less than thirty inches in theaters having a capacity of more than four hundred and fifty seats and less than seven hundred and fifty seats on the main floor; not less than thirty-two inches in theaters having a capacity of more than seven hundred and fifty seats on the main floor. Main floor cross aisles shall not be less in width than the widest aisle with which they connect. Every auxiliary floor longitudinal aisle shall be at least twenty-eight inches wide. Steps shall not be placed in aisles unless the gradient would exceed one-foot rise in each ten-feet run. Steps, when necessary, shall be grouped, and, so far as practicable, isolated steps shall be avoided. Such steps shall extend across the full width of the aisles. No riser shall be more than eight inches in height, and no tread shall be less than nine inches in width, and whenever the riser of seat platforms is four inches or less, the floor of the aisles shall be made as a gradient. All aisles shall be illuminated. Aisles shall be used only for passage to and from seats and shall be kept unobstructed at all times.
3. “Exit” or “exit way” means the exit doorway or doorways, or such doorways together with connecting hallways, passageways, or stairways, to which persons may pass safely from a room or space to a street or to any open space which provides safe access to a street. Exits or exit ways from any room may lead through other rooms of the same or other tenancies. There shall be a minimum of two exits on the main floor of every such building, one being located at the front and the other being located at the rear of the building. Side exits easily accessible may be installed in place of rear exits. Such exits shall have a minimum width of thirty-six inches and shall have a combined or aggregate width of not less than twenty-two inches for each one hundred seats or major fraction thereof up to and including one thousand seats with one foot additional width for each additional one hundred seats or major fraction thereof, up to and including two thousand seats, and an additional six inches for each additional one hundred seats or major fraction thereof over two thousand seats. All exit doors shall be arranged to swing outward and be so constructed that they can be readily opened from the inside with pressure, and shall never be locked or fastened when the room is open to the public. All such exit doors shall be open upon a well-lighted street, alley, or private passageway having unobstructed access to a street or another alley. Each exit door must have a light above each doorway with “EXIT” in letters large enough to be read from any part of the room, and, where electricity is used for the illumination of these signs, the current shall be on a circuit separate from general house lights. Balconies, galleries, tiers, or other spaces having a capacity of more than two hundred persons each, shall have at least two exit ways and, where the capacity is more than six hundred persons, at least three exit ways, and, where the capacity is more than one thousand persons, at least four exit ways. Such required exit ways may use communicating hallways, corridors, or passageways.
4. All scenery and curtains shall be made as secure against becoming inflamed as reasonably practicable, and also all reasonably practicable arrangements shall be made for the constant supply of water or other means for the extinguishment of fires, and they shall be kept constantly effective during the presence of an audience; provided, however, that any building or structure coming under the provisions of sections 316.060 to 316.100 that has, or may be required to have under the provisions of this section, only one center aisle, such aisle shall be of constant width, and that width shall not be less than the widest minimum width of such aisle provided in this section; and provided further, that any provision of this section relating to the type of seats required shall not apply to any building or structure to which sections 316.060 to 316.100 are applicable where the seating capacity is less than one hundred and eighty persons.