§ 264. Fireproof building. "Fireproof building" means a building
conforming to the following requirements:

1. All exterior walls shall be constructed of brick, or stone, or
concrete, or cinder block, or concrete block, or tile, or terra cotta or
such other material as shall be specified in the rules of the board. The
board shall determine and specify in its rules such requirements as it
deems necessary for the construction of exterior walls.

2. All floors and roofs shall be built of brick, or cinder block, or
concrete block, or tile, or terra cotta, or reinforced concrete
supported by steel or reinforced concrete beams and girders. The board
shall determine and specify in its rules such other materials, the
manner of construction of floors and roofs and such other requirements
as may be deemed necessary to carry into effect the intent of this
chapter.

3. All structural metal shall be encased in fireproof material, of
such thickness as shall be specified in the rules of the board.

4. All vertical openings leading from one floor to another, except one
created by a mezzanine floor, shall be enclosed by fireproof or
fire-resisting materials in a manner conforming to rules adopted by the
board.

5. All stairways, landings, hallways, floor surfaces, furring,
ceilings, partitions, sash, trim, window frames, doors and other
interior finish, shall be constructed of incombustible material; but
nothing in this section shall prevent the use of such combustible
materials as the board shall determine and specify in its rules. Such
rules shall also specify the circumstances or conditions under which
combustible flooring, trim, acoustical material, insulating material or
other interior finish may be used or applied to floors, walls,
partitions or ceilings of fireproof buildings.

6. All windows shall be fire windows except:

a. In buildings less than seventy feet in height erected after October
first, nineteen hundred and thirteen, where the windows are located more
than thirty feet from another building or open on a court or space more
than thirty feet wide;

b. In buildings less than one hundred and fifty feet in height erected
before October first, nineteen hundred and thirteen, where the windows
are located more than thirty feet from another building.

c. Fire windows may be provided with plate glass not less than
one-fourth of an inch in thickness, no light of which shall exceed seven
hundred and twenty square inches in area.

(1) If the windows are located more than thirty feet horizontally or
fifty feet vertically from the nearest opening in the wall of another
building.

(2) If the windows are located more than fifty feet in a vertical
direction above the roof of a building within a horizontal distance of
thirty feet of the wall in which the said windows are located.

7. Partitions. All partitions in the interior of fireproof buildings
shall be of incombustible material. Nothing in this section shall
prevent the use, in a building equipped with automatic sprinklers, of
subdividing partitions of wood, or of wood and glass, in spaces used
solely for office or show-room purposes, provided, however, that where
such spaces are contiguous to any room or rooms in which manufacturing
is carried on, such spaces shall be separated from such room or rooms by
a dividing partition which, including doors, is constructed of
incombustible material.