A. 
Buildings occupied in whole or in part as defined in this code shall comply with the requirements hereinafter set forth concerning occupancy, size, light and ventilation in order to provide safe and healthful environment.
B. 
The term "accessory use" shall have a uniform meaning and shall apply in the same manner and under the same conditions or restrictions to all residential buildings.
A. 
Every dwelling unit shall contain at least 120 square feet of habitable floor space for the first occupant thereof and at least 90 additional square feet of habitable floor space for every additional occupant thereof, the floor space to be calculated on the basis of total habitable floor area within the dwelling unit.
B. 
In lodging units and rooming units the maximum number of occupants shall be limited to the number determined on the same basis as for dwelling units.
C. 
In buildings occupied as clubs, dormitories, sorority or fraternity houses and providing sleeping accommodations for more than five persons, the maximum number of occupants so accommodated in any habitable room shall be limited to the number determined on the basis of the floor area, in square feet, of the room divided by 50 square feet per occupant.
A. 
It shall be prohibited to use for sleeping purposes any kitchen, nonhabitable space or public space.
B. 
It shall be prohibited, in lodging houses and rooming houses, to use for dining purposes any communal kitchen containing less than 100 square feet of floor area or any nonhabitable space or public space other than dining space.
C. 
It shall be prohibited to use any cellar space in a multiple dwelling as habitable space. Cellars in one- and two-family dwellings may be used as habitable space, provided that the cellar complies with all the following requirements:
(1) 
Combustion air shall not be taken from habitable space directly or indirectly.
(2) 
All habitable space in cellars shall be ventilated by mechanical means. The ventilating system shall replace the air in the habitable spaces at least three times per hour. The air supply of said ventilation system shall be from the exterior or may be drawn from the floor above, provided that the floor above is occupied by the same tenancy as the cellar.
(3) 
Walls of cellars shall be constructed to prevent condensation forming thereon when the relative humidity in the habitable area is 35%.
(4) 
All fuel-burning equipment shall be separated from habitable space by a partition having a minimum fire rating of one hour.
A. 
Habitable space shall have a minimum ceiling height of seven feet six inches over 50% of the floor area; and the floor area where the ceiling height is less than five feet shall not be considered in computing floor area.
B. 
A dwelling unit shall contain at least one habitable room having a minimum of 120 square feet of floor area and a minimum horizontal dimension of 10 feet.
C. 
Kitchens shall have a minimum of 60 square feet of floor area, and other habitable spaces shall contain not less than 70 square feet of floor area and shall have a minimum horizontal dimension of seven feet.
D. 
Every alcove less than 60 square feet in area, except a cooking space or foyer, shall be deemed to be part of a habitable room. The area of the opening in the dividing partition between the alcove and the room shall be at least 80% of the wall area of such partition, measured on the alcove side, but not less than 40 square feet. The depth of such alcove shall not exceed half its width. The floor area of the alcove shall be added to the floor area of the room in determining light and ventilation requirements for the room. An alcove with an area of 60 square feet or more, but less than the required area of a habitable room, shall be separately lighted and ventilated as required for habitable space.
Basements shall not be deemed habitable unless all of the following conditions shall be met: Such room shall be at least seven feet six inches in height in every part from the finished floor to the ceiling. Ceilings of such rooms shall be at least three feet six inches above the surface of the street, alley, yard or court adjoining the same. There shall be appurtenant to such room if used for sleeping purposes the use of a water closet. Every room shall have a window or windows opening upon the street, an alley or upon a yard or court. The total area of windows in every room shall be at least one-eighth (1/8) of the floor area of the room, and the sash shall be made to open the full width, and the top of each window shall be within six inches of the ceiling. All exterior walls surrounding such room shall be dampproof. The floor of such room shall be dampproof and waterproof.
A. 
Habitable space shall be provided with natural light through one or more windows, skylights, transparent or translucent panels, or any combinations thereof, that face directly on legal open spaces at least six inches above the adjoining finished grade or are above a roof. The amount of light required for each room shall be equivalent to that transmitted through clear glass equal in area to 10% of the floor area of the habitable space.
B. 
Habitable space shall be provided with electric light.
C. 
Every habitable room shall be provided with natural ventilation through at least one window opening that faces directly on legal open space. No such window shall be less than 12 square feet in area between stop-beads, and the top of at least one window shall not be less than six feet six inches above the floor. It shall be constructed so that at least 45% of its area may be opened. A skylight arranged to give a clear ventilating opening of eight square feet shall be deemed the equivalent of the window called for, but such skylight shall not be placed on any shaft on which a window of a toilet room opens.
D. 
Habitable space also may be provided with mechanical ventilation, in lieu of or in addition to natural ventilation.
A. 
Dwelling units shall be separated from each other and from other spaces outside the dwelling unit.
B. 
Sleeping rooms within dwelling units shall be separated from each other and from other spaces outside the sleeping rooms to provide privacy.
C. 
Lodging units and boarding units shall be separated from each other and from other spaces outside the lodging units.
D. 
A communal kitchen or dining room in a lodging house shall be accessible to the occupants sharing such kitchen or dining room without going through a dwelling unit or lodging unit of another apartment.
A. 
Public spaces shall be provided with electric light.
B. 
In public stairs, stairways and passageways, electric lighting shall be available at all times so as to afford safe passage for occupants and users. Such lighting shall conform to the following:
(1) 
A sufficient number of fixtures shall be provided so that the distance between fixtures is not more than 30 feet and so that no wall is more than 15 feet distant from a fixture.
(2) 
Incandescent lighting shall be based on not less than one-four (1/4) watt per square foot of floor area, except that each fixture shall have a lamp or lamps with a total of not less than 25 watts.
(3) 
Fluorescent lighting shall be based on not less than one-tenth (1/10) watt per square foot of floor area, except that each fixture shall have a lamp or lamps of a total of not less than 15 watts.
(4) 
Where under these formulas the calculated wattage does not correspond to that of a standard lamp, the next larger size shall be used.
C. 
Public spaces shall be provided with either natural ventilation, conforming to the requirements for habitable space, or with mechanical ventilation.
A. 
In every private dwelling, apartment house and multiple residence, there shall be a separate water closet for each family. Each such water closet shall be placed in a room completely separated from every other water closet; such room shall be not less than three feet wide and shall be enclosed with partitions which shall extend to the ceiling. No drip trays shall be permitted in connection with any water closet nor shall a water closet fixture be enclosed.
B. 
Toilet rooms and bathrooms shall have provisions for privacy.
C. 
Toilet rooms and bathrooms for dwelling units in multiple dwellings shall be located within the dwelling units and shall be accessible from any sleeping room without passing through any other sleeping room.
D. 
Unless located within dwelling units or directly connected with sleeping rooms, toilet rooms and bathrooms in multiple dwellings shall be provided in each story containing habitable space and shall be accessible thereto.
E. 
Toilet rooms for employees in multiple dwellings shall be in separate room for each sex where there are five or more employees, shall be readily accessible to such employees and shall not open directly into any public kitchen or other public space used for the cooking or preparation of food.
F. 
In one- and two-family dwellings, bathrooms and toilet rooms shall be provided with floors of moisture-resistant material.
G. 
In multiple dwellings, floors of bathrooms, toilet rooms and similar spaces shall be waterproof; such waterproofing shall extend six inches or more above floors except at doors, so that floors can be flushed or washed without leaking. Walls shall be constructed or covered with a moisture-resistant material.
H. 
All shower enclosures shall have waterproof floors and water-resistant walls.
I. 
No water closet shall be placed out of doors.
A. 
Kitchenettes, bathrooms and toilet rooms shall be provided with electric light appropriate for the use of such rooms.
B. 
Laundry rooms, furnace rooms and similar nonhabitable spaces shall be provided with electric light appropriate for the use of such rooms.
C. 
Stairs shall be provided with electric light to allow safe ascent or descent.
D. 
Kitchenettes, bathrooms and toilet rooms shall be provided with ventilation in accordance with either of the following: Natural ventilation as required for habitable space, except that for toilet rooms and bathrooms, a window shall not be less than one foot in width measured between the stop-beads and shall not be less than five square feet in area, and the openable area of a window in a kitchenette shall not be less than three square feet; or mechanical ventilation exhausting not less than 25 cubic feet per minute for bathrooms and toilet rooms and not less than 100 cubic feet per minute for kitchenettes.
E. 
Spaces in multiple dwellings which contain central heat-producing, air-conditioning and other equipment shall be ventilated to the outer air, and air from these spaces shall not be recirculated to other parts of the building.
F. 
Ventilation shall be provided in unheated attics, spaces below flat roofs and in crawl spaces. Location and net areas of ventilation openings shall be such as to minimize deterioration of structural members from condensation or other causes, in conformity with generally accepted standards.
A. 
Safe, continuous and unobstructed exit shall be provided from the interior of the building to the exterior at street or grade level.
B. 
Exits shall be arranged, constructed and proportioned so that occupants may escape safely from the building in case of emergency.
C. 
In one- and two-family dwellings, in addition to a primary exit from the building, there shall be provided a secondary exit or, in lieu thereof, one or more openings for emergency use as defined in § 231-25.
D. 
In multiple dwellings approved exits shall be provided.
A. 
At least one opening or secondary exit shall be provided at each floor level containing a habitable space or recreation room.
B. 
Such openings shall include doors and openable parts of windows, located so as to provide ready access to legal open spaces.
C. 
Such openings shall have a minimum area of five square feet, with a minimum dimension of 16 inches, with bottom of openings no higher than three feet above finished floor in all above-grade stories and no higher than four feet six inches where required in basement and cellar.
One- and two-family dwellings exceeding three stories in height shall have exits from every story which shall provide safe continuous passage to a legal open space and which shall comply with one of the following requirements:
A. 
One interior stairway enclosed in a fire separation having a fire resistance rating of at least one hour. All openings in such enclosures shall be provided with a self-closing opening protective as set forth in the following table:
Opening Protectives For Interior wall Openings
Fire-resistance rating of wall separation in which opening occurs, in hours
Fire-resistance rating of opening protective, in hours
2 or more
1 1/2
1 or 3/4
1
B. 
Two interior stairways with all doors opening upon such stairways equipped with a self-closing device.
C. 
One interior stairway with all doors opening upon such stairway equipped with a self-closing device and one exterior stairway or fire escape providing exit from each dwelling unit on any story.
D. 
One interior stairway equipped with an automatic sprinkler system, with all doors opening upon such stairway equipped with a self-closing device.