Section 270 - Construction of buildings erected after October first, nineteen hundred and thirteenNo factory shall be conducted in a building erected after October first, nineteen hundred and thirteen, unless such building shall conform to the following requirements:
1. Fireproof construction. All buildings more than four stories in height shall be fireproof.2. Roofs and walls. Roofs shall be covered either with incombustible material, or tar and slag, or plastic cement or such other materials as the board may approve, supported and laid according to its specifications. Cornices shall be constructed of incombustible material. All exterior walls within twenty-five feet of a non-fireproof building shall be built of brick, stone, concrete, cinder or concrete block or tile, terra cotta or other fireproof material acceptable to the state department of labor.3. Required exits. a. On each floor used as a factory there shall be not less than two exits remote from each other, except that a single exit may be accepted by the commissioner from a floor or other area, of one thousand square feet or less, so long as no person is regularly employed on such floor or other area. One such exit on each floor used as a factory shall be a grade exit, an interior or exterior enclosed fireproof stairway or ramp. The other shall be either such a grade exit, stairway, ramp, or a horizontal exit, except that unenclosed exterior stairways or ramps within the property line, extending up or down to grade may be substituted for enclosed stairways from a floor immediately above or below the ground or first floor. Elevated runways and working platforms on which there is no regular or permanent occupancy shall not be construed as floors.b. No point in any floor above or below the ground or first floor shall be more than one hundred feet distant from the entrance to one such exit at that floor and in a sprinklered building more than one hundred and fifty feet distant from such exit. No point in any ground, or first floor shall be more than two hundred feet distant from an exit from that floor and in a sprinklered building more than two hundred and fifty feet distant from such exit; provided that no point in any ground, or first floor of a building erected after July first, nineteen hundred forty-eight, in which a factory is conducted, shall be more than one hundred fifty feet distant from an exit from that floor and in a sprinklered building more than two hundred feet distant from such exit.c. In every building over one hundred feet in height there shall be at least one exterior fireproof enclosed stairway which shall be accessible from any point in the building.4. Stairways and ramps. a. All required interior stairways and ramps shall be constructed of incombustible material. Two hour fire test enclosures shall be provided in buildings over two stories in height, and in all subgrade stories. One hour fire test enclosures shall be provided for all other stairs and ramps in buildings two stories or less in height. All stairways and ramps shall have an unobstructed width of at least forty-four inches throughout their length except that hand rails may project not more than three and one-half inches into such width. There shall be not more than twelve feet six inches in height between successive landings. The treads shall be not less than ten inches wide and the risers shall be closed and not more than seven and three-fourths inches. No stairway with "winders" shall be permitted as a required exit. The treads shall be constructed and maintained so as to prevent persons from slipping thereon. Ramps used in place of required exit stairways shall have a slope not exceeding one foot in eight feet and shall comply with the requirements for stairways as to material, width, enclosure, ventilation, landings and shall have non-slip surfaces.b. Every such required interior stairway shall be enclosed and ventilated in a manner conforming to rules adopted by the board, except that unenclosed stairways, no part of whose floor opening is more than twenty feet from an open side of the mezzanine and which lead to the floor immediately below, may be accepted from an unenclosed mezzanine not exceeding twenty-five hundred feet in area, unless otherwise specified by the board in its rules.c. Exterior windows within twenty-five feet of a non-fireproof structure shall be fire windows. Skylights, unless provided with wired glass, shall have thereunder a shield of wire mesh in substantial frame work.d. Whenever safe egress may be had from the roof of a building exceeding two stories in height to an adjacent structure all stairways serving as required exits shall extend to the roof, provided that in buildings over five stories in height at least one of the stairways serving as required exits shall extend to the roof. All stairways serving as required exits shall lead (a) continuously to the street, or (b) to a fireproof passageway independent of other exits from the building opening on a road or street, or (c) to an open area affording unobstructed passage to a road or street, except that unobstructed access to exits on the floor immediately below may be accepted for stairways from a mezzanine floor unless otherwise specified by the board in its rules. Provision shall be made for the adequate lighting of all stairways, ramps and passageways by artificial light. Where more than two stairways are provided in a building, not more than two may lead through a common fireproof passage to a street. Required stairways terminating at a floor below roof shall be connected at floor at which such stairs terminate through a fireproof passage to at least one other required stairway.5. Doors and doorways. All doors at required exits or that lead to required exits shall open outwardly. The width of the fireproof passageways and exit doorways including stops, leading to the street at the grade level shall be not less than the aggregate required width of all stairways and ramps leading to them. The aggregate capacity of all other required exit doorways shall be calculated on the basis of twenty-two inches for each fifty persons or fraction thereof to be served by such doorways, but no such doorway shall be less than thirty-six inches in width. The provisions of this section shall not apply to a building, in a city having a population of more than one million, used exclusively by one employer and in which not more than one-tenth of all the persons employed therein are engaged in work for a factory and which, except for such factory work, would be classified as a mercantile establishment.