General.
Municipal Code of Chicago § 18-28-406.1
in effect18-28-406.1 General.
Uninhabited spaces, such as crawl spaces and attics, shall be provided with natural ventilation openings as required by Chapter 12 of the Chicago Building Code or shall be provided with a mechanical exhaust and supply air system. The mechanical exhaust rate shall be not less than 0.02 cfm per square foot (0.00001 m 3 /s • m 2 ) of horizontal area and shall be automatically controlled to operate when the relative humidity in the space served exceeds 60 percent.
(Amend Coun. J. 9-14-21, p. 35949, Art. IV, § 7)
Source: City of Chicago, Municipal Code of Chicago (American Legal Publishing, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/chicago/latest/chicago_il/0-0-0-2694574Fetched: 10/24/2026
