Section 189. Stair and public hall construction

Except as provided in
  paragraph g of subdivision three of  section  one  hundred  seventy-one,
  stairs and public halls shall conform to the following provisions:
    1.  In  a  dwelling  more  than  a basement and three other stories in
  height or occupied by four families or more, the soffit and stringers of
  every stair between the lowest entrance story and the next higher  story
  and  the  walls  and  ceilings  of  every  lowest entrance hall shall be
  fire-retarded and in such dwellings converted on and after  July  first,
  nineteen  hundred  fifty-eight,  all doors opening to such entrance hall
  and stairs, and the door assemblies, shall be fireproof with  the  doors
  self-closing.  In  lieu  of  the  requirements  of  this  subdivision, a
  sprinkler system may be installed in accordance with the  provisions  of
  section one hundred eighty-seven.
    2.  Every  door  opening from any stair, entrance hall or other public
  hall to any other part of the  dwelling  shall  be  self-closing.  Every
  glazed  transom  over  any  such  door  shall be glazed with wire glass.
  Every transom shall be stationary. On and  after  July  first,  nineteen
  hundred  fifty-seven,  every glazed panel or other glazed opening in any
  such door shall be glazed with wire glass.
    3. Every stair, except a basement or cellar stair, shall be  two  feet
  six  inches  or more in clear width. Any wooden stair may be replaced by
  an iron stair of like dimensions. Every entrance hall shall be two  feet
  eight inches or more in clear width.
    4. If the number of rooms in a class B dwelling is increased and there
  are  sixteen  sleeping rooms or more above a basement or, if there be no
  basement, above the main entrance story,  all  partitions  and  ceilings
  enclosing public halls and stairs shall be fire-retarded throughout. All
  doors  opening  to  such  public halls and stairs, and their assemblies,
  shall be fireproof  with  the  doors  self-closing.    Stairs  shall  be
  fireproof  and  shall  extend  from  the  main  entrance story through a
  bulkhead to the roof.
    5. On and  after  July  first,  nineteen  hundred  fifty-seven,  every
  interior  sash, or opening other than a door, in the walls or partitions
  of any stair, entrance hall or  other  public  hall,  and  every  window
  therein  not opening to the outer air, shall be removed and the openings
  closed up with material similar to the adjacent walls.