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(Added Coun. J. 4-29-98, p. 66679, § 1; Amend Coun. J. 9-14-16, p. 31143, § 5; Amend Coun. J. 11-9-16, p. 36266, § 26*)
* Editor's note – The amendment of Coun. J. 11-9-16, p. 36266, § 26 to this section did not take into account the amendment of Coun. J. 9-14-16, p. 31143, § 5, which renders the later amendment unnecessary.
(a) Roof spaces.
(i) Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilation openings. The ventilation openings shall be tested for rain and snow infiltration in a manner representative of the intended installation and shall not permit the entrance of rain and snow when so tested. Ventilation openings shall not be provided in roof areas, or portions thereof, which are subject to snow drift as determined by Section 13-52-280.
(ii) The minimum required net free ventilating area shall be 1/150 of the area of the space ventilated. Where ridge or gable vents are utilized, one- half of the ventilation openings shall be provided by ridge or gable vents, with the balance of the ventilation openings provided by eave or cornice vents. The openings shall be covered with corrosion-resistant mesh or other approved materials with openings not more than 1/2 inch (13 mm) in any direction.
(iii) The minimum required area is permitted to be reduced to 1/300, provided that a vapor retarder having a permeance not exceeding 1 perm is installed on the warm side of the ceiling; or the ridge or gable ventilation openings are located in the upper third of the space to be ventilated with the balance of the required ventilation provided by eave or cornice vents.
(b) Crawl Spaces.
(i) Crawl space areas, other than those used as an underfloor plenum, shall be ventilated by an approved mechanical means or by openings in exterior foundation walls. Openings shall be located as close to corners as practicable and shall provide cross ventilation on at least two approximately opposite sides. The openings shall be covered with corrosion-resistant mesh not less than 1/4 inch (6 mm) nor more than 1/2 inch (13 mm) in any direction.
(ii) Openings shall have a net area of not less than 1 square foot (0.093 m
2
) for each 150 square feet (13.95 m
2
) of foundation space. Where an approved vapor retarder is installed over the ground surface, the required net area of openings shall be reduced to 0.1 square foot (0.093 m
2
) for each 150 square feet (13.95 m
2
) and vents shall have manually operable louvers.
(c) Alternative mechanical ventilation. Enclosed attic, rafter and crawl spaces which are not ventilated as herein required shall be equipped with a mechanical ventilation system conforming to the applicable requirements set forth in Chapter 18-28 of this Code.
(Added Coun. J. 4-29-98, p. 66679, § 1; Amend Coun. J. 9-14-16, p. 31143, § 6; Amend Coun. J. 11-9-16, p. 36266, § 26*)
* Editor's note – The amendment of Coun. J. 11-9-16, p. 36266, § 26 to this section did not take into account the amendment of Coun. J. 9-14-16, p. 31143, § 6, which renders the later amendment unnecessary.
All courts and yards required to serve rooms for natural light or natural ventilation purposes shall comply with the requirements of this section.
(a) Minimum width. (i) Every such court or yard shall have a minimum width of 3 feet (1,005 mm) up to a height of 36 feet above grade and thereafter an additional 2 inches (76 mm) for each 1 foot (305 mm) of height or fraction thereof up to a maximum width of 15 feet (7,620 mm). Above required width values shall apply to outer courts and twice these values shall apply for inner courts. (ii) In the case of irregular or gore- shaped courts or yards, as these are defined in Section 13-172-030, the average width shall not be less than the required width of a court in accordance with subsection (a) (i) of this section, but shall not be less than 5 feet (1,524 mm) at any point.
(b) Access to court. A door or other means of access shall be provided at the bottom of every court that is not otherwise provided with convenient access for purposes of cleaning.
(c) Air intakes. Every court which serves one or more habitable rooms and which does not open for its full height on one or more sides to a street or legal yard, shall be connected at or near the bottom with a street or yard by a horizontal intake or passage of fire-resistance rated construction, as provided in Section 15-8-660. Such intake or passage shall have a cross-sectional area of not less than 21 square feet (1.95m2) and shall remain fully open at both ends and unobstructed for its full size and length, except that grilles of noncombustible construction are permitted at the ends of the intake.
(Added Coun. J. 4-29-98, p. 66679, § 1)
(a) Permissible projections. Every required court and yard shall remain unobstructed for its required area and full height, except for the projections permitted in subsections (b) through (f) of this section.
(b) Maximum encroachment. A part of any building or structure shall not extend into side courts, inner courts or yards required for light and ventilation of habitable and occupiable rooms unless permitted by the Chicago Zoning Ordinance. The encroachment shall not exceed 20 percent of the legal area of the yard or court which is required for light and ventilation purposes.
(c) Accessories. In Class A (residential) and Class B (institutional) occupancies, clothes poles, arbors, garden trellises and other such accessories shall not be prohibited in the open spaces at ground level.
(d) Steps and architectural features. Steps, window sills, belt courses and similar architectural features, as well as rain leaders and chimneys, shall not project more than 2 feet (610 mm) beyond the face of the wall.
(e) Exterior stairways and fire escapes. Outside stairways, smokeproof tower balconies, fire escapes or other required elements of a means of egress shall not project more than 4 feet (1,219 mm) beyond the face of the wall.
(f) Motor vehicle parking. Where approved, required court and yard areas for automobile parking spaces or private garages not exceeding one story in height where accessory to and only for the occupants of a Class A (residential) occupancy are permitted, provided that required windows for light and ventilation are not obstructed thereby.
(Added Coun. J. 4-29-98, p. 66679, § 1; Amend Coun. J. 4-15-15, p. 106130, § 12; Amend Coun. J. 9-14-16, p. 31143, § 7)