N.Y. Multiple Dwelling Law § 106

§ 106. Cellar and basement stairs. A cellar or basement stair may be\nlocated inside the dwelling, but shall not be located underneath a stair\nleading to the upper stories unless it is a basement stair leading\nupward from a basement which is the main entrance story of the dwelling,\nor unless it is a stair leading downward from the entrance story which\nis separated by a fireproof arch from the stair leading upward from the\nentrance story. Except as otherwise provided in subdivision five of\nsection fifty-two, all inside cellar or basement stairs shall be\nentirely enclosed with fireproof walls and be provided with fireproof\ndoors and assemblies, with the doors self-closing, at all openings.\n