Illinois Building Codes After 2025: State Baseline and Local Rules

Illinois now has a statewide structural baseline, but local departments still control permits, amendments, zoning, and inspections. Learn the two code paths and project overlays.

July 10, 202614 min readGovCodex TeamBuilding Permits

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Direct Answer: Illinois now has statewide baseline construction requirements for privately funded projects, effective January 1, 2025, but it still does not have one uniform permit code or one statewide permit office. A city, village, or county with an adopted building code must meet the baseline rules in 20 ILCS 3105/10.18. A jurisdiction without an adopted building code follows separate state fallback rules: 20 ILCS 3105/10.09-1 for covered commercial construction and the Home Repair and Construction Task Force Act for new one- and two-family dwellings. In all settings, the local authority having jurisdiction controls permits, zoning, local administration, and inspections. Statewide energy, plumbing, accessibility, fire-safety, and project-specific agency rules apply as additional layers.

Verified against current Illinois government sources: July 18, 2026. Code editions and local amendments change; confirm the current CDB directory entry and local building department requirements before design or construction.

Key Takeaways

The old shorthand that Illinois has “no statewide residential building code” is no longer accurate. Since January 1, 2025, Illinois law supplies a statewide structural baseline for both jurisdictions that adopt codes and jurisdictions that do not.
Local control still matters. The local building department remains the authority having jurisdiction for privately funded work and decides the permit path, local amendments, submittal requirements, inspections, and interpretations.
In a jurisdiction with an adopted code, the local code must meet the structural baseline in 20 ILCS 3105/10.18. The adopted edition and amendments can differ from the next town.
In a non-building-code jurisdiction, do not assume there is no standard. Covered commercial work follows Section 10.09-1 and its inspection/certification path. New one- and two-family contracts use the separate residential rules in 815 ILCS 670.
The Illinois Energy Conservation Code applies statewide even where a municipality has not adopted or does not enforce a local building code. The current state page identifies the amended 2024 IECC as effective November 30, 2025.
Plumbing, accessibility, highway right-of-way, water, sewer, stormwater, and work near public waters can add separate state or local approvals.
Start with the parcel, not the mailing address. Then identify the local authority, code status, statewide overlays, and any outside-agency approvals before preparing plans.

Scope note: This guide covers privately funded projects. State-funded construction and state-owned facilities can follow CDB processes that are different from a homeowner's or private developer's local permit path.

What Changed in Illinois on January 1, 2025?

Public Act 103-0510 changed the Capital Development Board Act. The practical result is a two-path system with a statewide floor:

Local code status	Structural rule	Who reviews and enforces
City, village, or county has adopted a building code	The local code applies, but Section 10.18 requires its structural design rules to be at least as stringent as the statutory baseline for residential, new nonresidential, and existing-building work	The local building department or its designated official
Jurisdiction has not adopted a building code	Covered commercial work follows Section 10.09-1; new one- and two-family construction follows 815 ILCS 670 and the residential code chosen or incorporated under that law	Local filing authority, qualified inspectors where required, and the parties responsible under the applicable state path

For adopted codes, Section 10.18 defines baseline codes using editions of the International Residential Code, International Building Code, and International Existing Building Code that fall within the statute's permitted age range. It also requires a local government to report an adopted code and amendments to CDB before the local effective date. That reporting supports the state's municipal code directory.

This change did not create one statewide permit application, one statewide fee schedule, or one statewide zoning ordinance. It created minimum structural protection while keeping local administration in place.

The First Question: Which Office Has Jurisdiction?

Use the actual parcel boundary and municipal status. A postal city can differ from the permitting jurisdiction, especially near annexation boundaries or on unincorporated land.

Confirm whether the parcel is inside a city or village or in unincorporated county territory.
Open the CDB Building Codes and Regulations directory page and locate the Illinois Municipal Code Directory.
Record the local code editions, amendments, and the directory's reporting date.
Confirm the same information with the local building official. The CDB FAQ explains that the local code official is the authority having jurisdiction for privately funded construction and CDB does not overrule that official's project decision.
Ask whether zoning, fire, public works, health, or utility reviews use separate applications.

The directory is a starting point, not a substitute for the local ordinance. A recently adopted ordinance may not yet appear, and the ordinance may contain amendments that change plan details.

Building Code Is Only One Layer

An Illinois permit check should separate structural code, zoning, trade rules, and outside-agency approvals.

Layer	Typical question	Primary authority to verify
Structural building code	Which adopted code or state fallback path applies?	Local building department, CDB directory, Section 10.18, Section 10.09-1, or 815 ILCS 670
Zoning	Is the use allowed, and do setbacks, height, lot coverage, parking, or design rules fit?	City, village, or county zoning office
Energy	Which energy code edition and compliance documents apply?	Illinois CDB Energy Code and local reviewer
Plumbing	Are plumbing plans, a licensed plumber, or a separate permit required?	Illinois Department of Public Health and local plumbing authority
Accessibility	Does the facility or housing type fall under the Illinois Accessibility Code?	Illinois CDB Accessibility Code and local reviewer
Electrical, mechanical, and fire	Which adopted editions, statewide fire rules, and trade permits apply?	Local building/fire authorities and the Illinois State Fire Marshal, as applicable
Road access or right-of-way	Does a driveway, utility, or other activity enter a state-maintained highway right-of-way?	Illinois Department of Transportation highway permits and utility permits
Water, sewer, or stormwater	Does the project need a construction, discharge, or facility approval?	Illinois EPA permitting and the local utility
Rivers, lakes, streams, dams, or public waters	Is work in or along regulated water subject to a state permit?	Illinois DNR Office of Water Resources

One approval does not waive the others. A zoning approval does not prove building-code compliance, and a building permit does not automatically authorize work in a highway right-of-way or regulated waterway.

How the Two Structural Paths Work

Path 1: The jurisdiction has an adopted code

Use the adopted ordinance and every incorporated amendment. Section 10.18 sets a floor, but the locally adopted package remains the working code. The local package may include newer model codes, stricter provisions, administrative chapters, permit exemptions, contractor-registration requirements, and locally chosen electrical or fire standards.

Ask the department for:

the exact adopted code editions and effective date;
the local amendment ordinance;
whether the project is reviewed as new construction, an addition, an alteration, a repair, or a change of occupancy;
the current plan checklist and electronic-submittal rules;
trade-permit sequencing and contractor credential requirements; and
required inspection stages and whether any third-party reports are needed.

Path 2: The jurisdiction has no adopted building code

Do not interpret “no local code” as “no construction standard” or “no inspections.” The state fallback is different for commercial and residential construction.

For new or substantially improved commercial buildings, Section 10.09-1 supplies the applicable IBC or IEBC path, together with electrical, statewide energy, plumbing, accessibility, and fire/life-safety rules. The statute requires qualified inspection and a compliance certification before occupancy, filed with the municipality or county.

For a new one- or two-family dwelling, 815 ILCS 670 governs the construction contract in a non-building-code jurisdiction. The buyer and builder may agree to a qualifying current code; when the contract is silent, the statute incorporates the current IRC together with the Illinois Energy Conservation Code and Illinois Plumbing Code. Additions, alterations, accessory buildings, and other residential scopes need a project-specific local and state review rather than an assumption that the new-home contract rule answers them.

Before design, ask the county or municipality to confirm in writing:

that it is currently a non-building-code jurisdiction;
which commercial or residential fallback rule applies and which code edition it incorporates;
who may perform required inspections or certifications;
what documents must be filed and when; and
which zoning, septic, well, driveway, floodplain, or other local permits still apply.

A rural parcel may lack a locally adopted general building code while remaining subject to zoning and multiple statewide programs.

Residential, Commercial, and Existing-Building Projects

Project condition	Structural starting point	Questions that change the path
New one- or two-family dwelling	Compliant local residential code, or the 815 ILCS 670 contract path in a non-building-code jurisdiction	Local administration, energy documents, plumbing, septic or sewer, driveway, floodplain, fire access
Residential addition or structural remodel	Local adopted code where one exists; otherwise confirm the locally administered permit rules and every applicable statewide program	Existing nonconformity, load path, egress, smoke/CO alarms, energy scope, zoning envelope
New commercial or multifamily building outside IRC scope	IBC-based baseline or compliant local building code	Occupancy, construction type, fire protection, accessibility, site/civil approvals
Alteration, repair, or change of occupancy in an existing commercial building	IEBC-based baseline or the local existing-building provisions	Work-area classification, change of use, accessibility, fire/life-safety upgrades

Classify the project before selecting code provisions. A change of occupancy can trigger a different review even when the construction looks modest, and an addition can cause zoning or stormwater review outside the building footprint.

Statewide Rules That Commonly Change the Plan Set

Energy conservation

The Illinois Energy Conservation Code page says the code applies to all buildings in Illinois, including places where the municipality has not adopted or does not enforce a building code. The page identifies the amended 2024 IECC as effective November 30, 2025 for residential and privately funded commercial construction. Confirm the required compliance report, climate-zone assumptions, testing, and local review process.

Illinois also has a voluntary Stretch Energy Code. It applies where a municipality adopts it; do not assume the stretch code is statewide or that a neighboring community has made the same choice.

Plumbing

The Illinois Department of Public Health plumbing program administers the Illinois Plumbing Code and plumber licensing. A local building department may intake or inspect plumbing work, but the statewide code and licensing layer still matters. Confirm whether drawings need plumbing review and whether the work must be performed by a licensed Illinois plumber.

Accessibility

The Illinois Accessibility Code implements state accessibility requirements for covered facilities. Accessibility is not limited to a final ramp detail; it can affect site routes, entrances, toilet rooms, counters, dwelling units, and alterations. Determine applicability during concept design.

Fire and life safety

Do not label fire prevention as exclusively local. The Illinois State Fire Marshal FAQ explains the relationship between statewide fire-prevention rules, local codes, and home-rule authority. Confirm the occupancy, the responding fire authority, the locally adopted fire code, and any state review before treating a local building-code approval as the only fire-safety layer.

When Another Illinois Agency Enters the Project

Outside approvals are easiest to handle before the local plan set is finished:

State highway frontage: IDOT says permits are required for non-utility work in state highway right-of-way, and it maintains a separate utility-permit program. Confirm road ownership because a local street, county highway, and state route have different administrators.
Water, wastewater, and stormwater: The Illinois EPA permitting hub identifies Bureau of Water programs for water and sewer facilities, wastewater discharge, and construction or industrial stormwater.
Private septic and well: The IDPH private sewage program and private water program explain the state and delegated local-health workflows. Confirm soil, system, well, and licensed-contractor requirements before fixing the site plan.
Construction stormwater: Illinois EPA's construction stormwater page identifies permit coverage for disturbance of one acre or more and smaller sites that are part of a larger common plan of development.
Work in or along public waters: The Illinois DNR permit-program page covers activities involving rivers, lakes, streams, public waters, and dams.

These are screening questions, not a universal permit list. The project location and disturbance determine whether an agency has jurisdiction.

Why Chicago and Nearby Suburbs Still Differ

Chicago enforces its own Chicago Construction Codes, including Title 14B and related trade codes. The statewide baseline does not turn Chicago's application process or amendments into the same rules used by a suburb.

The same principle applies across metropolitan counties. Use the broader workflow here, then move to the canonical local guide where one exists:

Those pages cover narrower local intent. The statewide guide should help you identify the governing layers, not duplicate every local checklist.

A Permit-Ready Illinois Workflow

Pin the parcel to a jurisdiction. Verify incorporated or unincorporated status and road ownership.
Check the CDB directory and local ordinance. Record code editions, amendments, and effective dates.
Confirm adopted-code status. Determine whether Section 10.18's local-code path, Section 10.09-1's commercial fallback, or 815 ILCS 670's new-home contract path governs.
Classify the project. New residential, residential alteration, new commercial, existing-building alteration, and change of occupancy can use different provisions.
Run zoning first. Check use, setbacks, height, lot coverage, parking, overlays, and whether discretionary approval is needed.
Screen statewide layers. Energy, plumbing, accessibility, and any professional-design requirements should shape the plans.
Screen outside agencies. Road access, utilities, septic, well, stormwater, floodplain, and public-water work can control the site plan.
Build one coordinated submittal. The application, site plan, architectural sheets, structural information, energy documents, and trade plans should describe the same project.
Confirm inspections before work. Know which work must remain exposed and who can inspect in a non-building-code jurisdiction.
Close the permit. Complete final inspections and obtain the required certificate or local closeout record.

Application Checklist

Parcel number, legal address, owner, and permitting jurisdiction
Project description and valuation using the department's definitions
Current survey or scaled site plan with lot lines, setbacks, easements, utilities, and proposed work
Existing and proposed floor plans and elevations
Structural plans, details, and calculations appropriate to the scope
Energy compliance documents for the current statewide code
Plumbing, electrical, mechanical, and fire-protection documents when required
Accessibility analysis for covered projects
Contractor registrations, licenses, and design-professional seals when required
Evidence of zoning and outside-agency approvals
Inspection sequence and responsible contact for corrections

Frequently Asked Questions

Does Illinois have a statewide residential building code now?

Illinois now has statewide residential baseline pathways effective January 1, 2025, but not one uniform residential code administered from Springfield. In places with an adopted compliant code, the local code is used. For a new one- or two-family dwelling in a non-building-code jurisdiction, 815 ILCS 670 governs the code incorporated into the construction contract. Local permitting and zoning remain local.

Can a county or town still have no adopted building code?

Yes. But “no adopted local building code” does not mean there are no standards. The CDB's current FAQ explains the minimum structural, inspection, and certification path for non-building-code jurisdictions, and statewide energy, plumbing, and accessibility requirements may still apply.

How do I know which code edition applies?

Check the CDB Illinois Municipal Code Directory, then verify the adoption ordinance and effective date with the local building official. For a non-building-code jurisdiction, ask the official to identify the applicable commercial or residential fallback path and documentation requirements in writing.

Does the statewide baseline replace Chicago's code?

No. Chicago continues to administer its own construction codes, amendments, permit processes, and inspections, subject to applicable state law.

Does a building permit cover zoning too?

Not necessarily. Zoning regulates land use and the building envelope; building codes regulate construction and life safety. Some departments coordinate both reviews, but the approvals remain legally distinct.

What if the local official and a general state web page seem to disagree?

Ask for the controlling local ordinance, adopted edition, and project-specific determination. The CDB FAQ identifies the local code official as the authority having jurisdiction for privately funded projects. Preserve the written response with the permit file.

Verify the Rules for Your Property

Illinois now has a statewide structural floor, but the permit path still turns on the exact parcel and project. Browse the GovCodex Illinois permit directory for local starting points, or run a permit check to identify the likely jurisdiction and approval layers before you finalize plans.

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