Chicago City Council has approved updates and changes to the Mechanical, Fuel Gas, Energy Transformation, Building, Rehabilitation, and Interim Fire Prevention codes, modernizing the mechanical code, fire prevention code, and fuel gas code, as well as general changes to the building and rehab codes to allow for simpler and more affordable residential development. These updates include full updates to the Mechanical, Fuel Gas, Energy Transformation, and Interim Fire Prevention codes, bringing Chicago’s Construction Codes into line with the current model codes.
Note that there are changes throughout the codes that have been adopted, and the ordinance should be carefully reviewed to understand the full scope of changes, however, some critical and impactful changes/ updates are noted below.
The full language of the ordinance is linked here (PDF Document), and is available on the Chicago City Clerk website under SO2026-0024930.
These changes became optional to follow on October 1, 2026 (with DOB approval) and are mandatory for all projects submitted on or after December 1, 2026. The date for project submission is based on when the permit fee is paid to the City of Chicago, and the permit number is generated and assigned to the project.
The exception that permits make up air in dwelling units to be provided through an undercut at the unit entry door has been removed. All dwelling units must be provided with ducted make up air.
The pilot program that allowed for the mechanical ventilation of dwelling units in lieu of natural ventilation has been formalized and included in the code. Fully sprinklered buildings that have more than 20 units and all units are provided with mechanical ventilation per Section 403, d, are permitted to not provide natural ventilation. Note that there are no exceptions provided for natural light requirements, and those must still be met in all living, dining, and sleeping rooms.
Interlocking stairs have been added to the building code, and sections defining their use and design have been included. An interlocking stair is similar to a scissor stair, where there are two stairs within a single vertical shaft, however in an interlocking stair, the stairs are separated by a rated wall. The updated CBC requires that the shaft walls of an interlocking stair be 3 hour fire rated, while the stairs themselves are separated by a 2 hour rated wall. For residential (Group R) buildings up to 150’-0” or 15 stories, and are fully sprinklered, an interlocking stair is permitted to be counted as 2 separate exits from each floor. Additionally, the Department of Buildings and the Fire Prevention Bureau are permitted to allow interlocking stairs to be counted as two exits from other buildings and occupancy types, however this must be approved on a project by project basis.
There are also a number of changes to smaller residential only buildings (R-2, R-3, and R-5) buildings, allowing most exceptions to be increased to 5 stories. This includes allowing exterior stairs and porches to be made of combustible materials on buildings up to 5 stories, depending on the fire separation distance. Additionally, exceptions are provided for egress courts on similar buildings. The intent behind these changes is to allow for larger and more cost efficient residential buildings.
Note that there is a separate proposal, unrelated to this ordinance, to allow for single stair conditions in certain types of buildings. This has not been accepted by the City, and does not appear likely to be approved.
The Chicago Energy Transformation Code has been updated to the 2024 IECC, to match the Illinois Energy Code requirements. The Chicago specific amendments, such as the electrification ready dwelling units and solar ready roofs have been maintained.
A minor change in the zoning code, related to EVSE ready spaces, now allows for exterior EVSE spaces to be provided with conduit only to the spaces, rather than what was previously required, which was wire and conduit.
Please feel free to reach out if you have any questions regarding these, or any other code updates. MAPS also can provide a presentation on this topic, which can provide up to 1 hour of AIA CE credit.