N.Y. Multiple Residence Law § 130

§ 130. Entrance halls. Every entrance hall shall be at least three\nfeet eight inches in clear width from the entrance to the first stair.\nIf such an entrance hall is the only entrance to more than one required\nstairs, the width of such hall shall be increased in every part, for\neach such additional flight of stairs, by one-half the width required\nfor one flight of stairs.\n