The provisions of Section 1202 of IBC are adopted by reference with the following modifications:
1. Revise Section 1202.1 to read:
"1202.1 General.
Every space intended for human occupancy shall be provided with natural ventilation in accordance with Section 1202.5, or mechanical ventilation in accordance with the Chicago Mechanical Code.
Exceptions:
1. Where the air infiltration rate in a dwelling unit is less than 5 air changes per hour where tested with a blower door at a pressure 0.2 inch w.c. (50 Pa) in accordance with the Chicago Energy Conservation Code, the dwelling unit shall be ventilated by mechanical means in accordance with Section 403 of the Chicago Mechanical Code.
2. In dwelling units in Group I-1, R-2, R-3, and R-5 occupancies, natural ventilation in accordance with Section 1202.5 shall be provided in all living, dining and sleeping rooms with a floor area of 70 square feet (6.5 m
2
) or more.
3. Rooms containing bathtubs, showers, spas and similar bathing fixtures shall be mechanically ventilated in accordance with the Chicago Mechanical Code.
4. Ambulatory care facilities and Group I-2 occupancies shall be ventilated by mechanical means in accordance with the Chicago Mechanical Code.
5. Natural ventilation shall not be substituted for mechanical ventilation in rooms or spaces where mechanical ventilation is specifically required by the Chicago Mechanical Code or Chicago Energy Conservation Code.
6. Ventilation and exhaust systems for occupancies and operations involving flammable or combustible hazards or other contaminant sources as covered in the Chicago Mechanical Code or the Chicago Fire Prevention Code shall be provided as required by both codes."
2. Revise the exceptions to Section 1202.2.1 to read:
"Exception: The net free cross-ventilation area shall be permitted to be reduced to 1/300 provided at least 40 percent and not more than 50 percent of the required venting area is provided by ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located not more than 3 feet (914 mm) below the ridge or highest point of the space, measured vertically, with the balance of the ventilation provided by eave or cornice vents. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet (914 mm) below the ridge or highest point of the space shall be permitted."
3. Revise item 4 in Section 1202.3 to read:
"4. Any air-impermeable insulation shall be a Class II vapor retarder or shall have a Class II vapor retarder coating or covering in direct contact with the underside of the insulation."
4. Revise item 5.1.3 in Section 1202.3 to read:
"5.1.3. Where both air-impermeable insulation and air-permeable insulation are provided, the air- impermeable insulation shall be applied in direct contact with the underside of the structural roof sheathing in accordance with Item 5.1.1 and shall be in accordance with the R-values in Table 1202.3 for condensation control. The air-permeable insulation shall be installed directly under the air- impermeable insulation."
5. Delete item 5.1.4 in Section 1202.3.
6. Revise exception 2 to Section 1202.3 to read:
"2. Section 1202.3 does not apply to enclosures that are humidified beyond 35 percent during winter months."
7. Revise Table 1202.3 by deleting all rows except for Climate Zone 5.
8. Revise note a to Table 1202.3 to read:
"a. Contributes to, but does not supersede, thermal resistance requirements for attic and roof assemblies in the Chicago Energy Conservation Code."
9. Revise Section 1202.4 by deleting "1202.4.2."
10. Revise Section 1202.4.1 to read:
"1202.4.1 Ventilation openings.
Ventilation openings through foundation walls shall be provided. The openings shall be placed so as to provide cross-ventilation of the under-floor space. The net area of ventilation openings shall be in accordance with Section 1202.4.1.1 or 1202.4.1.2."
11. Delete Section 1202.4.2.
12. Delete Section 1202.4.4.
13. Revise Section 1202.5 and its subsections to read:
"1202.5 Natural ventilation.
Where required, natural ventilation shall be through windows, doors, louvers or other openings to the outdoors that open upon a public way or a yard or court complying with Section 1205. The operating mechanism for such openings shall be readily controllable by the occupants of the room or space served.
1202.5.1 Ventilation area required.
The net openable area of the openings to the outdoors, without regard for window opening control devices or limiters, shall be at least 4 percent of the floor area being ventilated.
1202.5.1.1 Adjoining spaces.
For the purpose of natural ventilation, any space is permitted to be considered as a portion of an adjoining room where at least one-half of the area of the common wall is open and unobstructed and provides an opening of not less than 10 percent of the floor area of the interior space or 25 square feet (2.32 m2), whichever is greater. The net openable area shall be at least 4 percent of the aggregate floor area.
1202.5.1.2 Remote rooms.
Where rooms and spaces without openings to the outdoors are ventilated through an adjoining room, the opening to the adjoining room shall either:
1. be unobstructed and shall have an area of not less than 8 percent of the floor area of the remote room or space, but not less than 25 square feet (2.3
m2).
2. be equipped with doors, movable panels, or louvers that are operable from within the remote room and that when fully open provide a net open area of not less than 10 percent of the floor area of the remote room or space, but not less than 30 square feet (2.8
m2).
The openable area of the openings to the outdoors shall be based on the total floor area being ventilated.
1202.5.1.3 Residential basements.
Where at least 40 percent of the net floor area of a Group R dwelling unit, not used as congregate living facilities, is located entirely above grade and provided with natural ventilation as required in this section, basement-level occupiable spaces may be provided with mechanical ventilation and exhaust providing at least 0.35 air changes per hour in lieu of natural ventilation openings.
1202.5.1.4 Openings below grade.
Where openings below grade provide required natural ventilation, the outside horizontal clear space measured perpendicular to the opening shall be one and one-half times the depth of the opening. The depth of the opening shall be measured from the average adjoining ground level to the bottom of the opening.
1202.5.2 Contaminants exhausted.
Contaminant sources in naturally ventilated spaces shall be removed in accordance with the Chicago Mechanical Code and the Chicago Fire Prevention Code."
14. Delete Section 1202.6.
(Amend Coun. J. 2-19-20, p. 14473, Art. II, § 56; Amend Coun. J. 1-26-22, p. 43756, Art. II, § 14)