N.Y. Multiple Residence Law § 260

§ 260. One and two-story frame dwellings; area limitation. A frame\ndwelling not exceeding two stories in height erected pursuant to plans\nfiled after April first, nineteen hundred fifty-nine, and containing an\narea greater than three thousand square feet must, in addition to any\nother applicable provisions of this article, comply with the following\nprovisions:\n 1. Fire-stopped partitions shall be constructed between apartments in\nsuch dwelling so as to prevent the passage of fire, smoke or gases from\none apartment to another.\n 2. No section of such dwelling shall contain more than three thousand\nsquare feet. Each such section shall be separated from all other\nsections of the dwelling by fire walls of masonry or other materials\nhaving a fire resistive rating of at least two hours. Such wall (1)\nshall be unpierced except for openings for heat, utility and other\nservice lines and ducts with such openings sealed with incombustible\nmaterials (2) shall extend continuously from the floor of the lowest\nlevel of the dwelling, to at least two feet above the level of the\nfinished roof and (3) be fire-stopped at floors and roof in such manner\nas to prevent the passage of fire, smoke or gases between sections.\nWhere there is a peaked or sloped roof, such wall may terminate at the\ntop of the roof boards.\n