A. 
Buildings occupied in whole or in part as defined in this Part 1 shall comply with the requirement 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 Part 1, shall be classified in respect to their occupancies as follows:
A. 
One- and-two family dwellings.
(1) 
Buildings containing one or two dwelling units with less than four lodgers residing with a family in either one of such dwelling units.
B. 
Multiple residences.
(1) 
Buildings containing one or two dwelling units with more than four lodgers with a family in either one of such dwelling units.
(2) 
Buildings containing three or more dwelling units.
(3) 
Apartment houses and apartment hotels.
(4) 
Lodging houses.
(5) 
Buildings with sleeping accommodations for more than five persons used or occupied as a club, dormitory, fraternity or sorority house or for similar uses; garden apartments.
C. 
Accessory structures. Garages, carports 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 80 but less than 120 square feet;
(2) 
Two occupants per room having floor area of at least 120 but less than 180 square feet; and
(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 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, 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 prepare or eat meals in lodging units.
D. 
It shall be prohibited to use any cellar space as habitable space.
A. 
Size.
(1) 
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.
(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 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.
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:
(a) 
Natural light through one or more windows, skylight, 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 the 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) 
Artificial light.
(c) 
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.
(2) 
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 dwellings units shall be separated from each other and from other spaces outside the sleeping rooms to provide privacy.
(3) 
Lodging units shall be separated from each other and from other spaces outside the lodging units.
(4) 
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 occupant.
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 stairs, stairways and passageways artificial light shall be electric lighting available 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 25 watts.
(c) 
Fluorescent lighting shall be based on not less than 1/10 watt per square foot of floor area, except that fixture shall have a lamp or lamps of a total of not less than 15 watts.
(d) 
Where under these formulas the calculated wattage does not correspond to that of a standard lamp, the next larger size shall be used.
(e) 
Public spaces shall be provided with either natural ventilation, conforming to the requirements for habitable space, or with mechanical ventilation.
A. 
Height. Nonhabitable space, except crawl spaces and attics, in multiple residences 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 residences 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 room, toilet rooms and bathrooms in multiple residences shall be provided in each story containing habitable space, and shall be accessible thereto.
(4) 
Toilet rooms for employees in multiple residences 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 residences, 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.
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:
(a) 
Natural ventilation as required for habitable space, except that such openable areas shall be not less than 1 1/2 square feet for bathrooms or toilet rooms and not less than three square feet for kitchenettes; or
(b) 
Mechanical ventilation exhausting not less than 25 cfm for bathrooms and toilet rooms and not less than 100 cfm for kitchenettes.
(5) 
Spaces in multiple residences 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.
(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. 
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 residences, approved exits shall be provided.