Section 30. Lighting and ventilation of rooms

1. The provisions of this
  section shall apply only  to  multiple  dwellings  erected  after  April
  eighteenth,  nineteen  hundred  twenty-nine, and shall apply to all such
  dwellings unless otherwise expressly limited.
    2.  Except  as  in  this  section  and   in   sections   thirty-three,
  seventy-six,  one  hundred  fifteen,  one  hundred  sixty,  one  hundred
  seventy-six, two hundred, two hundred thirteen, two  hundred  fifty  and
  two   hundred   fifty-one  otherwise  expressly  provided,  every  room,
  including kitchens, water-closet compartments and bathrooms, shall  have
  at  least  one  window  opening  directly upon a street or upon a lawful
  yard, court or space above a setback upon the same lot as that  occupied
  by  the  multiple  dwelling  in  which such room is situated. Every such
  window shall be so located as to light  properly  all  portions  of  the
  room.
    3. No room in any apartment of three rooms or less, and no room in any
  non-fireproof apartment, shall extend in depth, from a street or yard on
  which  it  faces,  more  than  thirty feet without a window opening on a
  lawful court.
    4. a. Nothing in this section or section twenty-six shall be construed
  as prohibiting the windows or doors  of  any  room  from  opening  on  a
  partially-enclosed  balcony  or  space  above  a  setback, provided such
  balcony or space opens directly to a street or to a lawful yard or court
  and the area of the front of the balcony or space which is open  to  the
  outer  air  is  at  least  equal to seventy-five per centum of the floor
  surface area of such balcony or space. Any living room thus lighted  and
  ventilated by windows or doors opening on such balcony or space shall be
  at most thirty feet in depth measured from the extreme outer face of the
  wall  forming the partial enclosure of the balcony or space. The windows
  or doors providing light and ventilation for a  room  or  rooms  opening
  exclusively  on  such  a balcony or space shall have altogether at least
  the area of one-tenth of the combined floor  surface  of  such  room  or
  rooms  and the portion of the balcony or space directly adjoining and in
  front of such room or rooms.
    b. On a  fireproof  dwelling  a  balcony  or  space  above  a  setback
  permitted  under  paragraph  a  of  this  subdivision  may be completely
  enclosed, provided the outer  enclosing  wall  or  walls  and  roof  are
  constructed  of  incombustible  materials  and the walls are glazed with
  clear plate glass or plastic equivalent and such  glazed  wall  area  is
  equal  to  at  least  fifty per centum of the area of the interior walls
  enclosing such balcony or space. At least fifty per centum of the glazed
  area shall be openable directly upon a street or upon a lawful  yard  or
  court.  No window shall open from any bathroom, water-closet compartment
  or cooking space upon such enclosed balcony.
    c. The enclosure on any balcony or a space above a setback  shall  not
  (1)  be  more than one story in height or (2) be erected in violation of
  the provisions of paragraph a of subdivision six of section one  hundred
  two of this chapter.
    5.  No  multiple dwelling shall be so altered as to diminish the light
  or ventilation of any room or public hall  or  stairs  in  any  way  not
  approved by the department.
    6.  No  window  shall  be  required  in any public room of a fireproof
  multiple dwelling if such room is used solely for  storage  purposes  or
  has  adequate  mechanical ventilation maintained to provide at least the
  number of changes of the  air  volume  of  such  room  approved  by  the
  department  as  necessary  for the health and safety of the occupants of
  such dwelling. Any fresh air supply system required  by  the  department
  for  such  purposes  shall  be provided with adequate means for removing

  dust from the incoming air and with adequate means to heat such  air  at
  least to sixty degrees Fahrenheit.
    7.  No  required window shall open upon any offset or recess less than
  six feet in  width  except  a  window  of  a  water-closet  compartment,
  bathroom,  or  stair or of a cooking compartment less than eighty square
  feet in floor surface area.
    8. (a) The windows in every room, except a  water-closet  compartment,
  bathroom, or cooking space less than eighty square feet in floor surface
  area,  shall  have  a total area at least one-tenth of the floor surface
  area of such room and every window in such a room, including a mullioned
  casement window, shall be at least twelve square feet in area.
    (b) All required  windows  shall  be  so  constructed  that  at  least
  one-half  of  their required area may be opened, except that a mullioned
  casement  window,  if  otherwise  large  enough  to  supply  the  window
  requirements of the room, need be readily openable to the outer air only
  to the extent of five and one-half square feet of its area.
    (c)  Where  fresh  air  is  furnished in any room through a mechanical
  ventilating unit or system which is an integral  part  of  the  dwelling
  structure  and  capable of introducing not less than forty cubic feet of
  air per minute, the required window area in such room need  be  openable
  only to the extent of twenty-five per cent of such window area but in no
  event less than five and one-half square feet.
    9. Transoms or partition sash, or louvres having a minimum area of 144
  square  inches and arranged to be opened or closed, shall be provided to
  private halls  or  to  adjoining  rooms  to  secure  through-ventilation
  whenever  required  by  the department, but no such transom or partition
  sash or louvre shall be required in a room having two windows opening to
  the outer air if each window is at least nine square feet in area, or in
  a room having a mullioned or single window with an aggregate area of  at
  least eighteen square feet.
    10.  All windows and their assemblies in walls situated on a lot line,
  except those facing on a street, shall  be  fireproof,  with  assemblies
  having a fire-resistive rating of at least three-quarters of an hour and
  glazed  with  wire  glass  at  least one-quarter of an inch thick. Every
  opening in a wall situated on a lot line which is less than  fifty  feet
  in  a vertical direction above a non-fireproof roof of another structure
  within a distance of thirty feet of the wall in  which  the  opening  is
  located shall be an automatic fireproof window.