New York Consolidated Laws, Multiple Residence Law - MRE § 255. Egress from apartments

1. A dwelling three or more stories in height shall have at least two means of egress from every apartment or suite.  Such means shall be remote from each other.  Except where it opens into a stair as permitted in subdivision three, one means shall be to a public hall connecting with an enclosed stair or fire-stair not more than fifty feet distant from such means.  The other required means of egress shall open either directly upon a fire-escape or a public vestibule or other public hall connecting with a stair or fire-stair.

2. Except as hereinafter provided for dwellings two stories or less in height, such vestibule, hall or stair shall be separated from the public hall or stair, on which the first means of egress opens, by a fireproof wall, unpierced except by a fireproof door and assembly with the door self-closing.  In a dwelling two stories or less in height, the separating wall may be fire-retarded.

3. In a dwelling three stories or less in height and occupied by four families or less on each story, and in any section of a permanently occupied dwelling which is two stories or less in height and occupied by four families or less on each story, a means of egress from an apartment may open directly into a stair without the intervention of a public hall.  Such means shall have a fireproof door and assembly with the door self-closing and without a transom.