Illinois — Code Adoption Summary
Adoption model: Home-rule for building/electrical (municipalities adopt), with statewide-mandatory energy, plumbing, and accessibility codes. Chicago has its own codes.
Last verified: 2026-07-03
Confidence: verified
Primary sources: IL Capital Development Board (energy) — https://cdb.illinois.gov/business/codes.html · IDPH (plumbing) · Chicago DOB — https://www.chicago.gov/city/en/depts/bldgs.html
Statewide-mandatory items (apply everywhere in IL)
| Code family | Adopted edition | Notes | Source |
|---|
| Energy (IECC) | Illinois Energy Conservation Code — updated effective 2025-11-30 (2024 IECC-based) | permits on/after 2025-11-30 comply; 2026 Stretch Code in development | cdb.illinois.gov |
| Plumbing | Illinois Plumbing Code (state, IDPH — not IPC/UPC verbatim) | statewide | dph.illinois.gov |
| Accessibility | Illinois Accessibility Code | statewide | cdb.illinois.gov |
| Building (new, since 2025-01-01) | Municipalities/counties must adopt IBC/IEBC/IRC for new construction | statewide mandate to adopt (edition set locally) | cdb.illinois.gov |
Electrical (NEC)
- No single statewide NEC edition — municipalities adopt the NEC locally, often on a delayed cycle. Confirm the city/county's adopted NEC edition per project.
Adoption model & precedence
- Energy + plumbing + accessibility: statewide, cannot be weakened; AHJ enforces the current state edition.
- Building + electrical: local jurisdiction is the AHJ; since 2025-01-01 all must adopt an IBC/IRC edition, but the specific edition + NEC edition is local.
Major cities / counties
| Jurisdiction | Notes | Building dept. |
|---|
| Chicago | Home-rule — own Chicago Building Code + Chicago Electrical Code (historically distinct; transitioning to ICC-based with heavy amendments). Do not assume state/NEC edition. | chicago.gov/buildings |
| Aurora / Naperville / Rockford / Joliet | Municipal adoptions of IBC/NEC + IL statewide energy/plumbing | respective city depts |
| Cook County (unincorp.) | County adoption | cookcountyil.gov |
AHJ fallback (when local adoption is unverified)
- Certain floor: IL Energy Conservation Code (2024 IECC-based), IL Plumbing Code, IL Accessibility Code — statewide.
- Building/electrical: confirm the municipality's adopted IBC + NEC editions. Chicago = its own codes (confirm with Chicago DOB).
- Action: contact the local building department (or Chicago DOB) for building + NEC edition.
Change log
- 2026-07-03 — created; verified statewide IL Energy Code (eff. 2025-11-30, 2024 IECC), IL Plumbing Code, 2025 statewide IBC/IRC adoption mandate; local NEC; Chicago own codes.
