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 a 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 buildings and premises.
Buildings, for the purpose of this code, shall be classified in respect to their occupancies as follows:
A. 
One- and two-family dwellings: buildings containing one or two dwelling units with not more than one family in either one of such dwelling units.
B. 
Multiple dwellings:
(1) 
Buildings containing three or more dwelling units.
(2) 
Apartment houses.
(3) 
Garden apartments.
(4) 
Buildings of mixed occupancy.
C. 
Business units.
D. 
Accessory structures.
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: one occupant per room having a floor area of at least 90 but less than 140 square feet, two occupants per room having a floor area of at least 140 but less than 200 square feet and three occupants per room having a floor area of 200 or more square feet.
A. 
The use for sleeping purposes of any kitchen, nonhabitable space or public space is prohibited.
B. 
The use in any dwelling of any cellar space as habitable space is prohibited.
C. 
The use of mobile homes or trailers for habitable space is prohibited.
A. 
Size.
(1) 
Habitable space shall have a minimum ceiling height of seven feet six inches.
(2) 
A dwelling unit shall contain at least one habitable room having a minimum of 150 square feet of floor area and a minimum horizontal dimension of 10 feet.
(3) 
Kitchens shall have a minimum of 60 square feet of floor area, and other habitable spaces shall contain not less than 80 square feet of floor area and shall have a minimum horizontal dimension of seven feet.
(4) 
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 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.
B. 
Basements. 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.
C. 
Light and ventilation.
(1) 
Habitable space shall be provided with natural light through one or more windows, skylights or transparent or translucent panels, or any combination thereof, that face directly on legal open spaces of at least six inches above the adjoining finished grade or 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.
(2) 
Habitable space shall be provided with artificial light.
(3) 
Habitable space shall be provided with natural ventilation through openable parts of windows or other openings in exterior walls that face legal open space 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.
(4) 
Habitable space may also be provided with mechanical ventilation, in addition to natural ventilation.
D. 
Miscellaneous requirements.
(1) 
Dwelling units shall be separated from each other and from other spaces outside the dwelling unit.
(2) 
Sleeping rooms within dwelling units shall be separated from each other and from other spaces outside the sleeping rooms, to provide privacy.
A. 
Height. Public space shall have a minimum height of seven feet six inches measured from finished floor to finished ceiling.
B. 
Light and ventilation.
(1) 
Public spaces shall be provided with artificial light.
(2) 
In public spaces, stairways and passageways, artificial light shall be electric lighting provided at all times so as to afford safe passage for occupants and users. Such lighting shall conform to the following:
(a) 
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.
(b) 
Incandescent lighting shall be based on not less than 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 60 watts.
(c) 
Fluorescent lighting shall be based on not less than 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 40 watts.
(3) 
Public space shall be provided with either adequate natural ventilation, conforming to the requirements for habitable space, or with adequate 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, shall be accessible from any sleeping room without passing through any other sleeping room and shall have provisions for adequate privacy.
(3) 
Toilet rooms for employees in multiple dwellings and business units 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 kitchen or other public space used for the cooking or preparation of food.
(4) 
In one- and two-family dwellings, bathrooms and toilet rooms shall be provided with floors of moisture-resistant material.
(5) 
In multiple dwellings and business units, floors of bathrooms, toilet rooms and similar spaces shall be surfaced with ceramic tile, and such tile shall extend at least four inches above the floor on all walls. Such tile shall be maintained in a watertight condition so that floors can be flushed or washed without leaking.
(6) 
In all dwellings and business units, shower enclosures and bathtubs shall be maintained in a watertight condition.
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 spaces 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 ventilation in accordance with either of the following:
(a) 
Natural ventilation as required for habitable space, except that such openable areas shall not be less than three square feet for bathrooms or toilet rooms and not less than six square feet for kitchenettes.
(b) 
Mechanical ventilation exhausting not less than 30 cubic feet per minute for bathrooms and toilet rooms and not less than 120 cubic feet per minute for kitchenettes.
(5) 
Spaces in multiple dwellings which contain central heat-producing, air-conditioning and other equipment or which are designed or used for the parking or storage of motor vehicles shall be ventilated directly 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 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. 
Stairs, both interior and exterior, shall be of sufficient width, in conformity with generally accepted standards, so as to serve the occupants.
B. 
Firmly secured railings shall be provided on 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 and business units, approved exits shall be provided.
E. 
Every entrance from the street, roof, passageway, courtyard, cellar or other entrance to a multiple dwelling shall be equipped with approved automatic self-closing and selflocking doors. Such doors shall be locked at all times except when an attendant shall actually be on duty.
F. 
The owner of every multiple dwelling shall install and maintain a light or lights at or near the outside of the front entranceway of the building which shall, in the aggregate, provide not less than 50 watts incandescent illumination for a building with a frontage up to 22 feet and 100 watts incandescent illumination for a building with a frontage in excess of 22 feet, or equivalent illumination, and shall be kept burning from sunset every day to sunrise on the day following. In the case of a multiple dwelling with a frontage in excess of 22 feet, the front entrance doors of which have a combined width in excess of five feet, there shall be at least two lights, one at each side of the entranceway, with an aggregate illumination of 150 watts or equivalent illumination.