55 ILCS 5/5-1064
The county board in any county with a population not in excess of 1,000,000 located in the area served by the Northeastern Illinois Metropolitan Area Planning Commission may prescribe by resolution or ordinance reasonable rules and regulations (a) governing the construction and alteration of all buildings and structures and parts and appurtenances thereof and governing the maintenance thereof in a condition reasonably safe from the hazards of fire, explosion, collapse, contagion and the spread of infectious disease, but any such resolution or ordinance shall be subject to any rule or regulation now or hereafter adopted by the State Fire Marshal pursuant to "An Act to regulate the storage, transportation, sale and use of gasoline and volatile oils", approved June 28, 1919, as amended, (b) for prohibiting the use for residential purposes of buildings and structures already erected or moved into position which do not comply with such rules and regulations, and (c) for the restraint, correction and abatement of any violations. However, the county shall exempt all municipalities located wholly or partly within the county where the municipal building code is equal to the county regulation and where the local authorities are enforcing the municipal building code. Such rules and regulations shall be applicable throughout the county but this Section shall not be construed to prevent municipalities from establishing higher standards nor shall such rules and regulations apply to the construction or alteration of buildings and structures used or to be used for agricultural purposes and located upon a tract of land which is zoned and used for agricultural purposes.
In the adoption of rules and regulations under this Section the county board shall be governed by the publication and posting requirements set out in Section 5-1063.
Beginning on the effective date of this amendatory Act of the 92nd General Assembly, any county adopting a new building code or amending an existing building code under this Section must, at least 30 days before adopting the building code or amendment, provide an identification of the building code, by title and edition, or the amendment for identification under Section 10.18 of the Capital Development Board Act .
For the purposes of this Section, "building code" means any ordinance, resolution, law, housing or building code, or zoning ordinance that establishes construction related activities applicable to structures in the county.
Violation of any rule or regulation adopted pursuant to this Section, except for a violation of the provisions of this amendatory Act of the 92nd General Assembly and the rules and regulations adopted under those provisions, shall be deemed a petty offense.
All rules and regulations enacted by resolution or ordinance under the provisions of this Section shall be enforced by such officer of the county as may be designated by resolution of the county board.
55 ILCS 5/5-1064