Section 242. Cellar and basement stairs in non-fireproof tenements

1.
  Cellar stairs in non-fireproof tenements erected  after  April  twelfth,
  nineteen  hundred  one,  which are occupied by three families or more on
  any story or which are five stories or more in height, shall be governed
  by the  provisions  of  section  one  hundred  fifty  for  non-fireproof
  multiple  dwellings  erected  after  April  eighteenth, nineteen hundred
  twenty-nine. In all other non-fireproof tenements  erected  after  April
  twelfth,  nineteen  hundred  one,  any  stair leading to a cellar may be
  located inside the building, provided  it  is  enclosed  with  fireproof
  walls  and  is  provided with fireproof doors and assemblies at both the
  top and bottom, with the doors self-closing.
    2. In old-law tenements exceeding a basement and three  other  stories
  in height and provided with an inside cellar stair communicating between
  the  entrance  story  and  a  cellar or lower story, the opening to such
  stair if located underneath the main stair leading to the upper  stories
  shall  be  enclosed  from  the  level  of  the  entrance story up to the
  underside of the first flight of such main stairs. The  soffit  of  such
  first  flight  of  main stairs and the partitions forming such enclosure
  shall be fire-retarded or covered with  twenty-six  gauge  metal.    The
  opening  to  such  enclosure shall be provided with a fireproof door and
  assembly with the door self-closing.