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.
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.
There shall be no manufacturing business conducted above the second floor of any non-fireproof multiple dwelling.
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.
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.
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.