N.Y. Mult. Resid. Law § 26
In every such dwelling three stories or more in height there shall be from each story at least two independent means of egress accessible to each apartment or suite. The first means shall open into a public hall connected with a stair affording safe access to a street, or to a yard, court or passageway affording continuous, safe and unobstructed access to a street. The second means shall be directly to a fire-escape or to an enclosed stair without passing through the first means, except that where the first means includes an interior stair which is closed off at each floor level by fire-retarded construction with a fireproof self-closing door therein, the second means may be another such interior stair or a fire-escape directly accessible on the same story from a public hall therein whether or not such public hall is also a part of the first means provided such fire-escape is not a wire, chain, cable, vertical ladder or rope fire-escape. In lieu of a second means of egress a sprinkler system may be installed in the public halls and stairs.
Except as required by the provisions of article four of this chapter, the second means of egress shall not be required in a multiple dwelling of fireproof construction, six stories or less in height, erected before July first, nineteen hundred fifty-two, if the egress arrangements thereof complied with requirements of law applicable at the time the dwelling was erected.
N.Y. Mult. Resid. Law § 26