§ 152.06 LIGHT, VENTILATION AND OCCUPANCY LIMITATIONS.
   (A)   General.
      (1)   Scope. The provisions of this chapter shall govern the minimum conditions and standards for light, ventilation and space for occupancy of a structure.
      (2)   Responsibility. The owner of the structure shall provide and maintain light fixtures, ventilation and space conditions in compliance with these requirements. A person shall not occupy as owner-occupant, or permit another person to occupy, any premises that do not comply with the requirements of this chapter.
      (3)   Alternative devices. In lieu of the means for natural light and ventilation herein prescribed, artificial light or mechanical ventilation in accordance with applicable state and local codes and ordinances shall be permitted. (IPMC 2006 § 401)
   (B)   Light.
      (1)   Every habitable room shall have at least one window or skylight facing directly to the outdoors. The minimum total window area, measured between stops, for every habitable room, shall be not less than 8% of the floor area of such room. Whenever walls or other portions of structures face a window of any such room and such light-obstructing structures are located less than three feet from the window and extend to a level above that of the ceiling of the room, such a window shall not be deemed to face directly to the outdoors and shall not be included as contributing to the required minimum total window area. Whenever the only window in a room is a skylight-type window in the top of such room, the total window area of such skylight shall equal at least 15% of the total floor area of such room.
      (2)   Means of egress: common halls and stairways. Every common hall and stairway in residential structures shall be lighted with at least a 60-watt standard incandescent light bulb or equivalent for each 200 square feet of floor area, provided that the spacing between lights shall not be greater than 30 feet. Every public hall and stairway in structures devoted solely to a dwelling occupancy and containing not more than three dwelling units shall be supplied with conveniently located light switches, controlling a lighting system which may be turned on when needed, instead of full time lighting.
      (3)   Other spaces. All habitable spaces shall be provided with natural or artificial light sufficient to permit the maintenance of sanitary conditions, and the safe occupancy of the space and utilization of the appliances, equipment and fixtures and in accordance with applicable state and local codes and ordinances. (‘74 Code, § 14.7-12) (IPMC 2006 § 402)
   (C)   Ventilation.
      (1)   Habitable spaces. Every habitable room shall have at least one window or skylight which can easily be opened or such other device as will ventilate the room. The total of openable window area in every habitable room shall be equal to at least 45% of the minimum window area size or minimum skylight type window size, as required in (B) above, except where there is supplied by mechanical means or some other device affording ventilation and approved by the Enforcement Authority.
      (2)   Bathrooms and toilet rooms. Every bathroom and toilet room shall have at least one openable window directly to the outdoors with a minimum glazed area of 8% of the total floor area. The total openable area of the window shall be a minimum of 45% of the minimum glazed window area. A window shall not be required in such spaces equipped with a mechanical ventilation system. Air exhausted by a mechanical ventilation system from a bathroom or toilet room shall discharge directly to the outdoors and shall not be re-circulated in accordance with all applicable state and local codes and ordinances.
      (3)   Clothes dryer exhaust. Clothes dryer exhaust systems shall be independent of all other systems, and discharged directly to the outdoors in accordance with applicable state and local codes and ordinances.
      (4)   Screens. The owner of a dwelling unit shall be responsible for providing and hanging all screens whenever the same are required under the provisions of this chapter. Every window or other device with openings to outdoor space, used or intended to be used for ventilation shall likewise be supplied with screens. Screens shall be required during April 1 through November 1 to provide protection against bats, mosquitoes, flies and other insects. ('74 Code, § 14.7-12) (IPMC 2006 § 402-403)
   (D)   Occupancy limitations.
      (1)   No person shall occupy or let to another for occupancy any dwelling or dwelling unit for the purpose of living therein, which does not comply with the following requirements.
      (2)   General requirements.
         (a)   For every dwelling unit there shall be at least 150 square feet of floor area for the first occupant and at least 100 additional square feet of floor area for each additional occupant. The floor area shall be calculated on the basis of the total floor area of the dwelling unit exclusive of stairways. For the purpose of such calculation, only the floor area in a basement meeting the requirements for basement occupancy shall be counted.
         (b)   No room used for sleeping purposes shall have a floor area of less than 70 square feet. No room shall be used for sleeping purposes by two or more persons unless there is at least 50 square feet of floor area for each person 12 years of age and over and at least 35 square feet of floor area for each child over one year of age and less than 12 years of age.
         (c)   No dwelling or dwelling unit, containing two or more sleeping rooms, shall have room arrangements such that access to a bathroom or water closet compartment intended for use by occupants of more than one sleeping room can be had only by going through another sleeping room, nor shall room arrangements be such that access to a sleeping room can be had only by going through another sleeping room or a bathroom or water closet compartment.
         (d)   At least 50% of the floor area of every habitable room shall have a ceiling height of at least seven feet; and the floor area of that part of any room where the ceiling height is less than five feet shall not be considered as part of the floor area in computing the total floor area of the room for the purpose of determining the maximum permissible occupancy thereof.
      (3)   Basement occupancy. No basement space shall be used as a habitable room or dwelling unit unless in accordance with applicable state and local codes and ordinances.
         (a)    The floor and walls are impervious to leakage of underground and surface runoff water and the area is insulated against dampness.
         (b)   The total of window area in each room is equal to at least the minimum window area sizes as required in § 152.06(C)(1).
      (4)   Prohibited uses. Kitchens and uninhabitable or public spaces shall not be used for sleeping purposes. No basement space shall be used as a habitable space unless it conforms to the minimum requirements of this chapter.
(‘74 Code, § 14.7-14) (Ord. G-31-85, passed 12-23-85; Am. Ord. G-25-99, passed 12-14-99; Am. Ord. G-03-09, passed 2-24-09; Am. Ord. G-9-17, passed 4-25-17)