§ 213. Lighting and ventilation of rooms. 1. No tenement, its lot or any room, public hall or stairs therein shall be so altered as to have its light or ventilation diminished in any way not approved by the department.

2. In every tenement erected after April twelfth, nineteen hundred one, every stair hall, public hall and living room and at least one water-closet compartment or bathroom containing a water-closet in each apartment, shall have at least one window opening directly upon a street or upon a lawful yard or court existing on April eighteenth, nineteen hundred twenty-nine. Such window shall be so located as to properly light all portions of such hall, room or compartment. Every part of an apartment of three rooms or less in such a tenement shall be within eighteen feet of a street or yard or have a window opening upon a lawful inner or outer court existing on April eighteenth, nineteen hundred twenty-nine. When a room in a tenement opens upon an inner court on a lot line and less than ten feet wide from the lot line to the opposite wall of the dwelling, such room shall be provided with a sash window communicating with another room in the same apartment. Such window shall contain at least ten square feet of glazed surface and be made so as to open readily.

3. No room in any old-law tenement shall be occupied for living purposes unless it meets the conditions in one of the following paragraphs:

a. Such room has a window opening directly upon a street, or upon a yard at least four feet in depth, or above the roof of an adjoining building, or upon a court or shaft at least twenty square feet in area open to the sky.

b. Such room is located on the top story and is adequately lighted by a ventilating skylight opening directly to the outer air.

c. Such room has a sash window opening directly into an immediately adjoining room in the same apartment which latter room opens directly on a street or yard at least four feet in depth. Such window shall have a vertically sliding pulley-hung sash not less than three feet by five feet, except that when it is impossible to construct a window of such size, the department may permit such window to be narrower. Both halves of the sash shall be made so as to open readily, and the lower half shall be glazed with translucent glass, or with obscure wire glass if the department shall so require. So far as possible such window shall be in line with windows in outer rooms opening on a street or yard, so as to afford a maximum of light and ventilation.

d. Such room has an alcove opening, of no less dimension than required for such a sash window, to such an adjoining room, in addition to the usual door openings.

4. In every existing tenement the department, in addition to the requirements of subdivision four of section eighty, may, as often as it deems necessary, require the walls and ceilings of every room that does not open directly on a street to be kalsomined or painted white to improve the lighting of such room.

5. Notwithstanding anything in this section to the contrary, no room in any old-law tenement in an apartment which is vacant on June thirtieth, nineteen hundred sixty, or thereafter becomes vacant, and, on and after June thirtieth, nineteen hundred seventy no room in any old-law tenement shall be used for living purposes unless such room shall have a window opening directly upon the street, or upon a yard not less than four feet deep, or above the roof of an adjoining building, or upon a court or shaft of not less than twenty square feet in area, open to the sky without roof or skylight, unless such room is located on the top floor and is adequately lighted and ventilated by a skylight opening directly to the outer air.

An alcove shall be deemed to comply with the requirements of this subdivision if (1) it opens directly into an immediately adjoining room in the same apartment, and (2) such adjoining room opens directly on a street or yard, and (3) a single unbroken open space occupies at least sixty per centum of the area of the vertical plane between the alcove and such adjoining room. The required open space between any such alcove and an adjoining room through which it receives light and ventilation shall not be obstructed by any curtain, portiere, fixed or movable partition or other contrivance or device.