N.Y.C. Admin. Code tit. 27, ch. 2 § 27-2058

a. Required windows. Every living room in a multiple dwelling erected after April eighteenth, nineteen hundred twenty-nine, shall have at least one window opening on:


(1) a street;


(2) a lawful yard or court on the same lot;


(3) a partially enclosed balcony or space above a setback which opens directly to a street, yard or court if the area of the front of such balcony or space open to the outer air is at least equal to seventy-five percent of the floor area of such balcony or space; or


(4) A completely enclosed balcony or space above a setback in a fireproof multiple dwelling if: the enclosure is not more than one story in height; the outer enclosing walls and roof are of incombustible materials; an area, glazed with clear plate glass or plastic equivalent, on the outer enclosing walls if at least fifty percent of the area of the interior enclosing walls; and at least fifty percent of such glazed area opens on a street, legal yard or court. One-half of such glazed area shall be openable. A living room does not include a kitchen under this paragraph.


b. No required window of a living room shall open on an offset or a recess of less than six feet in width.


c. Size of windows.


(1) The total area of all windows in the room shall be at least one-tenth the floor area of such room, except that when a room opens solely on a balcony or space above a setback the total area of such opening shall be one-tenth the combined floor area of the room and that portion of the balcony or space directly in front of such room. In determining the ratio of windows to floor area, the combined glazed area of windows and doors opening on a balcony or a space above a setback may be used.


(2) Every required window shall be at least twelve square feet.


(3) At least one-half of every required window shall open, except that for a mullioned casement window a minimum of five and one-half square feet is sufficient. In a room where a centralized mechanical ventilating system provides forty cubic feet of air per minute, twenty-five percent of the window area or five and one-half square feet of such area, whichever is greater, shall be openable.


(4) The top of one required window in every room shall be at least seven feet above the floor, except that in dwellings erected pursuant to plans filed after April twenty-third, nineteen hundred fifty-nine, and prior to June fourteenth, nineteen hundred sixty-seven, this requirement shall not apply.


d. Through ventilation.


(1) No part of any living room with windows, or doors in lieu thereof, opening on a balcony or space above a setback shall be more than thirty feet from the exterior face of the outer enclosing wall.


(2) In any dwelling unit in a non-fireproof multiple dwelling or in a dwelling unit of three rooms or less in a fireproof multiple dwelling, no part of any room shall be more than thirty feet from a window opening on a street or yard unless such room also opens on a legal court.


e. Openings on lot line. Every window and its assembly in a wall situated on a lot line, except a street line, shall be fireproof; the assembly shall have a fire resistive rating of at least three-quarters of an hour; and the window shall be glazed with wire glass at least one-quarter of an inch thick. Every such window shall be of automatic self-closing construction whenever it is less than fifty feet above the non-fireproof roof of another structure located thirty feet or less from the lot line.


f. Dining space. A dining space shall have a window which:


(1) Complies with the provisions of subdivision a of this section, and


(2) Has an area at least one-eighth the floor area of such dining space.