N.Y.C. Admin. Code tit. 27, ch. 2 § 27-2083

Except as provided in subdivision d of section 27-2082 of this article, no dwelling unit in the cellar or basement of a multiple dwelling erected after April eighteenth, nineteen hundred twenty-nine may be occupied unless:


a. Every room in a dwelling erected after July fourteenth, nineteen hundred sixty-seven has a minimum height of eight feet, and in dwellings erected prior thereto has a minimum height of nine feet in every part, except that four beams each not more than twelve inches wide may extend a minimum of six inches below the basement ceiling.


b. Every part of the ceiling of every such room is above the height of the curb level directly in front of each such part by not less than:


(1) Four feet six inches for a room in a dwelling unit located in the front of the dwelling, or


(2) Two feet for a room in a dwelling unit located in the rear of the dwelling. If the yard is sixty feet or more in depth, this requirement does not apply. Height above curb level is measured on the street on which the dwelling fronts.


c. The level of any yard or court upon which a required window opens conforms to the requirements of subdivision eight of section twenty-six of the multiple dwelling law.


d. Every room has at least one window opening upon a street, yard or court and is a part of a dwelling unit containing at least one room with a window opening upon a street or yard.


e. A required window in every room shall comply with the provisions of subdivision c of section 27-2058 of article one of this subchapter, except that the total area of all windows in such room shall be at least one-eighth of the floor area of the room and the top of each window shall be located not more than one foot from the ceiling.


f. Except as provided in subdivision g, not more than one apartment, as recorded in the certificate of occupancy, shall be located in the cellar unless the yard is sixty feet or more in depth. Such apartment shall contain no more than five rooms and a bathroom and shall be occupied either by the janitor or a rent-paying tenant, if no member of the family is under the age of sixteen years. No required window in any room of such apartment shall open upon a court less than five feet in width. Every part of the apartment shall be:


(1) Within twenty-five feet of the inner surface of the front or rear wall of the dwelling, or


(2) Have a window opening upon a court of the dimensions provided in subdivision seven of section twenty-six of the multiple dwelling law but in no event shall such court be less than ten feet in width.


g. A maximum of three additional rooms may be located in the cellar exclusively for the use of persons regularly and continuously employed in the maintenance of such dwelling. Each such room:


(1) Shall be completely separated from any other room or private hall;


(2) Shall have access to at least one bathroom without passing through the apartment provided for in subdivision f; and


(3) Shall comply with the provisions of subdivision f for required windows.