Section 271. Requirements for buildings erected before October first, nineteen hundred and thirteen

No  factory  shall  be  conducted  in  a
  building  erected  before  October first, nineteen hundred thirteen, and
  not occupied or used as a  factory  building  on  July  first,  nineteen
  hundred   forty-eight,   unless  such  building  shall  conform  to  the
  requirements of  section  two  hundred  seventy.  No  factory  shall  be
  conducted  in  a building erected before October first, nineteen hundred
  thirteen and occupied or used as  a  factory  building  on  July  first,
  nineteen  hundred forty-eight, unless such building shall conform to the
  following requirements:
    1. Required exits. a. On each floor used as a factory there  shall  be
  at least 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 shall be either
  a grade exit, an interior stairway enclosed as hereinafter  provided  or
  ramp similarly enclosed, or an exterior fireproof enclosed stairway. The
  other  shall  be:  either  such  a  grade  exit,  stairway or ramp; or a
  horizontal  exit;  or  an  exterior  screened   stairway;   or   outside
  fire-escapes  on  a  building six stories or less in height, except such
  fire-escapes shall not be accepted as a required exit in such  buildings
  or  particular  classes thereof where the board finds that they will not
  in its opinion furnish adequate and safe means of escape  for  occupants
  in  case of fire. Unenclosed exterior stairways or ramps extending up to
  grade may be substituted for enclosed stairways from a floor area  below
  the ground floor.
    b. No point on any floor above or below the ground floor shall be more
  than one hundred feet distant from the entrance to one such exit at that
  floor nor more than one hundred and fifty feet distant from such exit if
  the building has an automatic sprinkler system conforming to section two
  hundred  and  eighty  and the rules of the board. No point in any ground
  floor area 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.
    c. If safe egress may be had from the roof to  an  adjacent  structure
  every  stairway  serving  as a required exit in a building exceeding two
  stories in height shall be extended to  the  roof.  All  such  stairways
  shall  extend  to  the  first  story  and  lead  to  the street or to an
  unobstructed passageway leading to a street or road or to an  open  area
  affording safe passage to a street or road.
    2.  Stairway  enclosures.  All  interior stairways serving as required
  exits and the landings, platforms and  passageways  connected  therewith
  shall  be enclosed on all sides by partitions of fire-resisting material
  extending continuously from the basement to the roof. Where the stairway
  continues to the top floor such partitions shall extend  to  three  feet
  above  the  roof  or to the roof if it is fireproof. All such partitions
  and  doors  provided  for  openings  therein  shall  be  constructed  in
  accordance with rules adopted by the board.
    3.  Doors.  Where  five or more persons are employed on any floor of a
  factory building all doors on such floor leading to or  opening  on  any
  exit shall open outwardly or be double swinging doors. All exit doors in
  the  first  story,  including  the  doors  of  the vestibule, shall open
  outwardly.