New York Consolidated Laws, Multiple Residence Law - MRE § 205. Separation and ventilation of stairs

1. All stairs and fire-stairs shall be completely separated from one another and from every elevator or other shaft by fireproof walls.  They shall be constructed of fireproof material throughout and shall contain no wood or other inflammable material of any kind, except that handrails of hardwood may be provided.

2. Access to stairs and fire-stairs from any public vestibule or other public hall shall be through fireproof doors and assemblies, with the doors self-closing and at least three feet wide, or through pairs of such doors at least four feet wide, containing in either case a fixed sash glazed with wire glass at least one-quarter inch thick and at least three hundred sixty square inches in area.

3. At the highest level of every stair and fire-stair there shall be provided a window or a skylight.  At such termination, there shall also be an opening of at least one hundred forty-four square inches which shall communicate directly to the outer air, which opening may be a part of such window or skylight.  Except as herein provided, such skylight shall comply with the provisions of subdivision two of section one hundred eight.