(a) Natural light and ventilation.
(1) All guest rooms and habitable rooms within a dwelling unit or congregate residence shall be provided with natural light by means of windows or skylights with an area of not less than one-tenth of the floor area of such rooms with a minimum of 10 square feet. Not less than one-half of the required window or skylight area shall be openable to provide natural ventilation.
(2) All bathrooms, water closet compartments, laundry rooms, and similar rooms shall be provided with natural ventilation by means of windows with an openable area not less than one-twentieth of the floor area of such rooms with a minimum of 1.5 square feet.
(b) Origin.
(1) Required windows shall open directly onto the public way or a yard or court located on the same lot as the building.
Exception: required windows may open into a roofed porch or lanai where the porch or lanai:
(A) Abuts a public way, yard, or court;
(B) Has a ceiling height of not less than 7 feet; and
(C) Has the longer side at least 50 percent open and unobstructed. The area of fixed openings in open guardrails of minimum height may be credited for this requirement.
(2) A required window in a service room may open into a vent shaft that is open and unobstructed to the sky and not less than 4 feet in least dimension. No vent shaft shall extend through more than two stories.
(3) For the purpose of determining light and ventilation requirements, any room may be considered as a portion of an adjoining room when one-half of the area of the common wall is open and unobstructed and provides an opening of not less than one-tenth of the floor area of the interior room or 25 square feet, whichever is greater.
(c) Mechanical ventilation.
(1) In lieu of required openable windows for natural ventilation, a mechanical ventilation system may be provided for all spaces except bedrooms.
(2) Mechanical ventilation systems for bathrooms containing a bathtub or shower or combination thereof, laundry rooms, and similar rooms, shall provide not less than five air changes per hour and shall be connected directly to the outside. The point of discharge of exhaust air shall be at least 3 feet from any opening which allows air entry into occupied portions of the building.
(3) Mechanical ventilation systems for all habitable rooms, except bedrooms, and public corridors shall be capable of providing not less than two air changes per hour. At least one-fifth of the air supply shall be taken from the outside.
(4) All bathrooms, lavatories and toilet compartments that are ventilated by mechanical ventilation shall have fixed openings, from adjacent rooms or corridors or from other approved sources, which are sufficient to provide an inflow of air necessary to make exhaust ventilation effective. The exhaust air from bathrooms, lavatories, and toilet compartments shall not be recirculated. Exhaust duct systems for toilet compartments and bathrooms shall be separate from the exhaust duct systems for other portions of a building.
(5) Toilet compartments, bathrooms, and kitchens ventilated in accordance with this subsection may be provided with artificial light. When a water closet in a bathroom or toilet compartment is completely enclosed by partitions, such enclosure shall be separately lighted and ventilated.
(6) Systems of mechanical ventilation installed to comply with this code shall be kept in good working order and in continuous operation at all times during occupancy of the room served by such system. All openings to ventilators shall be ratproofed.
(d) Hallways. All public hallways, stairs, and other exitways shall be adequately lighted at all times in accordance with the building code.
(Sec. 25-4.4, R.O. 1978 (1983 Ed.)) (1990 Code, Ch. 27, Art. 4, § 27-4.4) (Am. Ord. 97-50)