Section 267. Horizontal exit

1. "Horizontal exit" means the connection by
  one or more openings, protected by firedoors, through a fire wall in any
  building, or through a wall or walls between two buildings, which  doors
  shall continuously be unlocked and the opening unobstructed whenever any
  person is employed on either side of the opening.
    2.  Exterior  balconies and bridges not less than forty-four inches in
  width connecting two buildings and not having a gradient  of  more  than
  one  foot  fall in six, may also be counted as horizontal exits when the
  doors opening out upon said balconies or bridges are fireproof doors and
  are level with the floors of the building, and when all  doors  of  both
  buildings  opening  on  such  balconies or bridges are continuously kept
  unlocked and unobstructed whenever any person is employed on either side
  of  the  exit,  and  when  such  balconies  or  bridges  are  built   of
  incombustible  material and are capable of sustaining a live load of not
  less than ninety pounds per square foot with a factor of safety of four;
  and when such balconies or bridges are enclosed on all sides to a height
  of not less than six feet and on top and bottom by  fireproof  material,
  unless  all  windows or openings within thirty feet of such balconies in
  the connected buildings shall be encased in metal frames  and  sash  and
  shall have wired glass where glass is used.
    3.  In  any  case there shall be on each side of the wall or partition
  containing the horizontal exit and independent of said horizontal  exit,
  at  least  one  stairway  conforming  to the requirements for a required
  exit.