Section 61. Business uses

1. Except as may be otherwise provided by any
  local law, ordinance, rule or regulation, business may be  conducted  in
  any multiple dwelling including:
    a. Baking and fat-boiling as provided in section fifty-nine,
    b.  Storage  of passenger motor vehicles as provided in section sixty,
  and
    c. Any manufacturing business in  which  seven  or  more  persons  are
  employed,  or  any  employment  agency as defined in section one hundred
  seventy-one  of  the  general  business  law  other  than  a  non-profit
  employment  agency  in  a  fireproof class B multiple dwelling owned and
  occupied  by  a  non-profit  corporation  organized  for   and   engaged
  exclusively in promoting religious, education or philanthropic purposes,
  provided  that every means of egress from such a business space shall be
  separate and distinct from and without means of communication  with  any
  means of egress from the dwelling portion of the building.
    2.  The  number  of  means  of egress from the portion of any multiple
  dwelling where business is conducted shall be in conformity  with  those
  provisions of the local laws, ordinances, rules and regulations covering
  means of egress from buildings in which a like business is conducted.
    3. There shall be no manufacturing business conducted above the second
  floor of any non-fireproof multiple dwelling.
    4. Where business is conducted in any multiple dwelling erected before
  April  eighteenth,  nineteen  hundred  twenty-nine,  such business space
  shall also comply with all the following requirements in a manner  which
  the department shall deem adequate to prevent the spread of fire:
    a.  Within  or appurtenant to such space, all pipe chases and openings
  around flues shall be fire-stopped, and such flues shall be kept in good
  order and repair.
    b. All other openings from such space  into  non-fireproof  shafts  or
  into  entrance  halls shall either be sealed with fire-retarded material
  or equipped with  a  self-closing  fire-retarded  door  or  window  with
  fire-retarded assemblies.
    5.  Where business is conducted in any non-fireproof multiple dwelling
  erected after April eighteenth, nineteen hundred twenty-nine, the  walls
  and  ceiling  of  such  business  space  shall  be  fire-retarded.   The
  department may also require the walls and ceilings of any business space
  in any multiple dwelling erected before such date  to  be  fire-retarded
  when  the  department  shall  deem  such  requirement  necessary for the
  protection of the occupants.
    6. If the ground story  of  any  non-fireproof  multiple  dwelling  is
  extended  for  business  purposes,  the  underside  of  the roof of such
  extension shall be fire-retarded. If there are fire-escapes  above  such
  extension, its roof shall be fireproof.