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.
Buildings, for the purpose of this code, shall be classified in respect to their occupancies as follows:
A. 
One-family dwellings: buildings containing not more than one dwelling unit occupied exclusively for residential purposes by the immediate family of the owner or tenant, not having more than one kitchen or one kitchenette and with not more than two lodgers or boarders residing with a family.
B. 
Two-family dwellings: buildings containing two dwelling units with not more than two lodgers residing with a family in either one of such dwelling units.
C. 
Multiple dwellings: buildings containing three or more dwelling units; buildings with sleeping accommodations for more than two persons, used or occupied as a dormitory or for similar uses; garden apartments.
D. 
Accessory structures: garages and similar-type structures on residential premises.
A. 
In dwelling units, the maximum number of occupants shall be limited to the number determined on the basis of the floor areas of habitable rooms, other than kitchens, as follows:
(1) 
One occupant per room having floor area of at least 60 but less than 120 square feet.
(2) 
Two occupants per room having floor area of at least 120 but less than 180 square feet.
(3) 
Three occupants per room having floor area of 180 or more square feet.
B. 
In lodging 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 dormitories and providing sleeping accommodations for more than two 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 to prepare or eat meals in lodging units.
C. 
It shall be prohibited to use any cellar space as habitable space.
A. 
Habitable space shall have a minimum ceiling height of eight feet over 75% of the floor area; and the floor area where the ceiling height is less than five feet six inches shall not be considered in computing floor area.
B. 
Kitchens shall have a minimum of 60 square feet of floor area, and other habitable spaces shall contain not less than 60 square feet of floor area and shall have a minimum horizontal dimension of six feet.
C. 
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 shall be separately lighted and ventilated as required for habitable space.
Basements shall not be deemed habitable space where required windows are located only on one wall and the depth of the basement space exceeds four times its clear height.
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 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 artificial light.
C. 
Habitable space shall be provided with natural ventilation through openable parts of windows or other openings in exterior walls that face legal open spaces above the adjoining finished grade or above a roof, or through openable parts of skylights, providing total clear ventilation area equal to not less than 5% of the total floor area of each habitable space.
D. 
Habitable space may also be provided with mechanical ventilation 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 shall be separated from each other and from other spaces outside the lodging units.
A. 
Height. Public space shall have a minimum height of eight feet measured from finished floor to finished ceiling.
B. 
Light and ventilation.
(1) 
Public spaces shall be provided with artificial light.
(2) 
In public stairs, stairways and passageways, artificial light shall be electric lighting available at all times so as to afford safe passage for occupants and users.
(3) 
Public spaces shall be provided either with natural ventilation conforming to the requirements for habitable space or with mechanical ventilation.
A. 
Height. Nonhabitable space, except crawl spaces and attics, in multiple dwellings shall have a minimum height of seven feet measured from floor to ceiling.
B. 
Toilet rooms and bathrooms.
(1) 
Toilet rooms and bathrooms in one- and two-family dwellings shall have provisions for privacy.
(2) 
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.
(3) 
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.
(4) 
Toilet rooms for employees in multiple dwellings shall be in separate rooms 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.
(5) 
In one- and two-family dwellings, bathrooms and toilet rooms shall be provided with floors of moisture-resistant material.
(6) 
In multiple dwellings, floors of bathrooms, toilet rooms and similar spaces shall be waterproof.
C. 
Light and ventilation.
(1) 
Kitchenettes, bathrooms and toilet rooms shall be provided with artificial light appropriate for the use of such rooms.
(2) 
Laundry rooms, furnace rooms and similar nonhabitable space shall be provided with artificial light appropriate for the intended use of such rooms.
(3) 
Stairs shall be provided with artificial light to allow safe ascent or descent.
(4) 
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 such openable areas shall be not less than one and one-half (1/2) square feet for bathrooms or toilet rooms and not less than three square feet for kitchenettes, 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.
(5) 
Spaces in multiple dwellings which contain central heat-producing, air-conditioning and other requirements shall be ventilated to the outer air, and air from these spaces shall not be recirculated to other parts of the building.
(6) 
Ventilation shall be provided in unheated attics, spaces below flat roofs and 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. 
Stairs, both interior and exterior, shall be of sufficient width in conformity with generally accepted standards so as to serve the occupants.
B. 
Railings shall be provided on open portions of stairs, balconies, landings and stairwells.
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 exit openings for emergency use.
D. 
In multiple dwellings, approved exits shall be provided.