2006 New York Code - First Tier Of Beams.

 
    §  240.  First  tier of beams. 1. In all tenements erected after April
  twelfth, nineteen hundred one, which are five stories or more in height,
  the first floor above the lowest cellar, or,  if  there  be  no  cellar,
  above  the  basement  or other lowest story, shall be fireproof; and all
  exposed portions of any iron or steel beams below the floor arches shall
  be fire-retarded.
    2. In all non-fireproof tenements erected after such  date  which  are
  four stories or less in height, the ceiling of the lowest cellar, or, if
  there  be  no  cellar,  of  the basement or other lowest story, shall be
  fire-retarded or covered with plaster boards at least one-half  inch  in
  thickness, with all joints made true and well pointed.
    3.  In  all old-law tenements which are four stories or more in height
  the ceiling of the cellar, or, if there be no cellar, of the basement or
  other lowest story, shall be fire-retarded.