Illinois Building Code: Which Editions Are Adopted

Direct answer

No statewide building code; a statewide energy code based on the 2024 IECC took effect 30 November 2025 in Illinois. Illinois Energy Conservation Code — the 2024 IECC with Illinois amendments, with ASHRAE 90.1-2022 as the commercial alternative. The 2024 Illinois Energy Conservation Code replaced the 2021-based code, which had been in force since 1 January 2024. Projects applying for a permit on or after 30 November 2025 must comply with the 2024 edition. Building and residential codes are adopted locally. Municipalities may adopt energy requirements more stringent than the state code, including the Illinois Stretch Energy Code, but not less. Record the permit application date with it: a code change normally applies from an effective date, and an application filed before that date is usually reviewed under the previous edition. This was checked on 2026-10-01 against Illinois Capital Development Board, which is the source that controls. The cross-state comparison further down this page comes from the ICC adoption chart dated January 2024, so where the two disagree the record above is the newer one.

Content and cited inputs reviewed by Harth team · Published 2026-09-07 · Updated 2026-10-01.

Which codes has Illinois adopted now?

No statewide building code; a statewide energy code based on the 2024 IECC took effect 30 November 2025.

Illinois Energy Conservation Code — the 2024 IECC with Illinois amendments, with ASHRAE 90.1-2022 as the commercial alternative.

Transition: The 2024 Illinois Energy Conservation Code replaced the 2021-based code, which had been in force since 1 January 2024. Projects applying for a permit on or after 30 November 2025 must comply with the 2024 edition.

Local adoption: Building and residential codes are adopted locally. Municipalities may adopt energy requirements more stringent than the state code, including the Illinois Stretch Energy Code, but not less.

Checked 2026-10-01 against Illinois Capital Development Board. Confirm the edition and effective date for the specific permit jurisdiction before relying on it.

The cross-state record

For comparison across states, every I-Code the ICC Master I-Code Adoption Chart (January 2024) tracks, as it records Illinois. Where this disagrees with the record above, the record above is newer:

Illinois has a recorded edition year for 2 of the 17 codes: 2021 for the residential energy and commercial energy codes. The building, residential, fire, mechanical, plumbing, private sewage, fuel gas, green construction, property maintenance, existing buildings, swimming pool and spa, performance, wildland-urban interface, zoning and green building standard codes appear as adopted by individual state or local agencies rather than as a statewide standard, so whether they apply depends on the permit jurisdiction for the project address.

Source: ICC Master I-Code Adoption Chart (January 2024).

How Illinois compares with its neighbours

Statewide editions in force, checked 2026-10-01; “Local” means no state adoption, “(limited)” a state adoption for some buildings only, and * a state-titled code built on that edition.

Indiana, Wisconsin and Iowa differ from Illinois on the building code alone. A practice working across that border is working to two editions, whatever the office standard says.

Where Illinois sits in the national record

Illinois is one of 17 jurisdictions with no statewide IBC edition in force. Adoption runs through local programmes or applies only to a subset of buildings, so there is no single answer for the state and the permit jurisdiction for the address decides.

Across all 17 codes the January 2024 ICC chart tracks, Illinois has a recorded edition for 2, which ranked it 46th of 51. A low count is not a gap in regulation — it usually means the state legislates through its own documents, or leaves the discipline to local adoption.

What the chart does and does not tell you

The chart's own legend matters more than the numbers:

• An edition year means one or more state or local agencies adopted that edition. It does not mean every building in the state is designed to it.
• “Some jurisdictions only” is the chart's X: the code is in use somewhere in the state but is not the standard for all buildings.
• “Not adopted” is a blank cell — no state or local jurisdiction reported adopting that code.
• “State-written code” means the state publishes its own document in place of the model edition, so the model text is a reference, not the law.

ICC states plainly that not every jurisdiction notifies it of an adoption, and this chart is dated January 2024. Treat it as the starting point for a search, never as the answer.

How to confirm the edition that governs a Illinois project

1. Open Illinois Capital Development Board and find the currently adopted code list with its effective date.
2. Check whether the permit authority for the project address is the state or a local programme with its own adoption.
3. Read the state amendments alongside the model edition — an amended table or definition changes the requirement even when the edition matches.
4. Record the permit application date. A code change usually applies from an effective date, and applications filed before it are normally reviewed under the previous edition.
5. Get the answer in writing from the authority having jurisdiction before it drives a design decision.

Illinois code-basis worksheet

Fill this in once per project and keep it with the drawing set. Every row is a question a plan reviewer can ask, and the answer changes with the address and the application date, not with the state.

This worksheet records a determination; it does not make one. The authority having jurisdiction decides which edition and which amendments apply.

Where can you explore related guidance?

• Explore all code adoption guidance
• Indiana Building Code: Which Editions Are Adopted
• Wisconsin Building Code: Which Editions Are Adopted
• Missouri Building Code: Which Editions Are Adopted
• Iowa Building Code: Which Editions Are Adopted

Sources and method

Adopted editions transcribed from the ICC Master I-Code Adoption Chart (January 2024), reproduced with the chart's own legend so an “X” is not mistaken for a statewide adoption. ICC notes that not all jurisdictions report their adoptions and publishes updates at iccsafe.org/adoptions. The current edition, its effective date and the state amendments are published by Illinois Capital Development Board, which controls.

Source links

• iccsafe.org

• iccsafe.org

• cdb.illinois.gov