New York Consolidated Laws, Multiple Dwelling Law - MDW § 212. Yards and courts

1. No tenement shall be enlarged or its lot diminished in any way which would leave any yard or court less in any dimension than the minimum dimensions prescribed for yards or courts in section twenty-six.

The restrictions of this subdivision shall not apply to tenements erected after April twelfth, nineteen hundred one, on lots which run through from one street to another street and do not exceed one hundred feet in depth.

2. Any court constructed on or after December fifteenth, nineteen hundred sixty-one in a tenement to ventilate any room, public hall, water-closet compartment or bathroom shall be of the dimensions prescribed in section twenty-six, and such court shall under no circumstances be roofed or covered over at the top.  Every such court, if an inner court, shall be provided at the bottom with one or more horizontal air-intakes constructed as provided in section twenty-six.

3. Any shaft or court constructed after April eighteenth, nineteen hundred twenty-nine, which is used to light or ventilate any room occupied for living purposes in any old-law tenement shall be at least twenty-five square feet in area and four feet in width in every part, and shall under no circumstances be roofed or covered over at the top.  Every such shaft shall be provided at the bottom with a horizontal air-intake or duct at least four square feet in area communicating directly with a street or yard and so arranged as to be easily cleaned.

4. In every old-law tenement there shall be a door at the bottom of every shaft and inner court giving access to the shaft or court and whenever the shaft or inner court is less than two hundred square feet in area or ten feet in any dimension, such door and its assembly shall be fireproof with the door self-closing.  Where a window or door existing on April eighteenth, nineteen hundred twenty-nine, gives proper access to such a shaft or court, such window or door shall be deemed sufficient.