New York Consolidated Laws, Multiple Residence Law - MRE § 259. Cellar and basement stairs

A cellar or basement stair located inside the dwelling shall be entirely enclosed with fireproof walls and be provided, at all openings, with fireproof doors and assemblies, with the doors self-closing, except that in any dwelling three stories or less in height, such stair may be enclosed with walls or partitions constructed of fire-resistive materials.