DuPage County Building Codes: Permits, Inspections, and Stormwater

Construction in unincorporated DuPage County is governed by the building codes adopted in Chapter 8 of the county code and enforced by the Building and Zoning Department.¹ The county uses its own residential code for houses and townhouses, the 2021 International Code Council suite for commercial and multi-family work, the 2020 National Electrical Code, the 2021 Illinois Energy Conservation Code (effective January 1, 2024), the Illinois State Plumbing Code, and the Illinois Accessibility Code. Most structural, mechanical, electrical, and plumbing work needs a permit before it starts, and a separate stormwater certification may also apply.

Which Codes Apply Where

The county’s adopted codes directly govern only unincorporated DuPage County. If your property sits inside a municipality such as Naperville or Wheaton, that city enforces its own codes and may use different editions or amendments. Confirm your jurisdiction before you assume county rules apply.

For projects that do fall under the county, here is what each code covers:¹

The DuPage County Building Code governs one- and two-family dwellings and townhouses. The county writes this residential code itself rather than adopting the IRC directly.
The 2021 International Building Code, International Fire Code, International Mechanical Code, International Fuel Gas Code, and International Property Maintenance Code apply to commercial and multi-family projects.
All electrical installations follow the 2020 NEC.
Energy compliance follows the Illinois Energy Conservation Code, demonstrated through REScheck for residential projects and COMcheck for commercial ones.
Plumbing and accessibility follow Illinois state codes rather than their international counterparts.

When You Need a Permit

New homes, commercial buildings, additions, and structural alterations always require a permit. So do a lot of projects that feel minor:

Sheds. Any shed needs a permit; those over 150 square feet require full construction plans.²
Pools, spas, and hot tubs. A permit is required for any pool 24 inches deep or greater, with 250 square feet or more of surface area, or using a water-recirculating system. The county also requires a 48-inch non-climbable fence with self-closing, self-latching gates.³
Decks. All decks need a permit, a plat of survey, and a construction plan with cross-section and top-view drawings.⁴
Mechanical and electrical work. Replacing a furnace, installing central air, upgrading a main electrical panel, or rerouting plumbing all require permits and trade inspections.

Purely cosmetic work is generally exempt. Paint, flooring, and swapping cabinets do not need a permit. Move a wall, relocate plumbing, or add an electrical circuit, and you are back in permit territory.

Permit Fees

Fees are based on the estimated cost of construction. The current schedule took effect May 1, 2025:⁵

Single-family homes and townhouses: $10 per $1,000 of construction cost, $50 minimum. New construction is valued at $90 per square foot of exterior dimensions. Remodeling uses actual cost, with a $100 minimum. Decks, patios, and similar features are valued at $10 per square foot.
Multi-family and condominiums: $20 per $1,000, $100 minimum. New construction is valued at $90 per square foot; remodeling carries a $200 minimum.
Commercial and industrial: $30 per $1,000, $150 minimum. Public agency projects get a 50 percent reduction on the building permit portion.
Accessory structures: $10 per square foot for structures 150 square feet or less, and $30 per square foot for larger ones such as detached garages and gazebos.

A 10 percent green building incentive is available for private developments meeting LEED Gold or Platinum or an equivalent county-approved standard. The schedule also carries a penalty category for work already started without a permit, so getting the permit first is cheaper.

What You Need to Submit

Incomplete applications are the main reason permits stall. Expect to supply:

A current plat of survey showing property lines, existing structures, and the proposed work to scale with distances to lot lines, sealed and signed by an Illinois-licensed land surveyor.⁴
Construction plans. The county accepts owner-prepared drawings for small projects like decks and sheds. Larger residential projects and commercial work typically require plans sealed by an Illinois-licensed architect or engineer.
Energy compliance documentation using REScheck (residential) or COMcheck (commercial) for any project affecting heating, cooling, or the building envelope.
Current DuPage County registration for every contractor on the job. Registrations last one year.⁴
A performance bond on certain project types. For decks, the bond is included in the permit fee and refunded after the final inspection passes.⁴
A trust disclosure form if the property is held in a trust.

Applications are submitted through the Accela Citizen Access portal or in person at the Building and Zoning office; appointments can be scheduled at 630-407-6700.⁶⁷ Plan review time depends on complexity. If staff request revisions, the review clock restarts when you resubmit, so complete first submissions save real time.

Inspections and the Certificate of Occupancy

Once the permit is issued, the county inspects at specific milestones, and nothing can be covered up before the relevant inspection passes. For a new residential build, inspections typically run through footings and foundation, framing, rough-in for electrical/plumbing/mechanical, insulation and energy, and a final walkthrough. Schedule inspections by calling 630-407-6700 at least 24 hours ahead.³ A passing final inspection triggers the Certificate of Occupancy, which closes the permit and authorizes you to use the building.

Expiration and the Cost of Skipping the Permit

Permits go void if work has not started within 180 days of issuance, or if more than 180 days pass between required inspections.³ Restarting means a new application and new fees. If your project moves slowly, keep inspections progressing.

Building without a permit costs more than building with one. The fee schedule imposes an increased charge when the county finds unpermitted work.⁵ Unpermitted work also surfaces in home inspections and title searches at resale, and fixing it after the fact often means opening finished walls so an inspector can verify what is behind them.

Stormwater Certification Runs on a Separate Track

Chapter 15 of the county code sets stormwater rules that catch many property owners by surprise. You need a stormwater management certification before starting any development that:⁸

Adds 2,500 square feet or more of new impervious surface (driveways, roofs, patios) compared to pre-development conditions.
Disturbs 5,000 square feet or more of land.
Involves flood plain, wetlands, or buffer areas.

Projects below all three thresholds and clear of flood plain or wetlands are generally exempt, though some still need a letter of permission or general certification. Properties with flood plain require Base Flood Elevation and flood plain delineation on the site plan, and work in the regulatory floodway needs Illinois Department of Natural Resources approval before the county will certify.

Violations run $100 to $1,000 per day, and the county can issue a stop-work order that halts construction until you comply. Property owners, developers, and contractors are jointly liable.⁹ Once a stop-work order is issued, you have 14 days to resolve the violation or apply for the required certification. Certifications expire December 31 of the third year after issuance.⁸

Federal Rules That Apply on Top

Local code compliance does not satisfy federal requirements that reach the same project.

Lead Paint in Pre-1978 Homes

Renovation, repair, or painting that disturbs lead-based paint in a home built before 1978 must be performed by an EPA-certified lead-safe contractor if the property is a rental, child care facility, or flip. Owners working on their own primary residence are generally exempt, but the exemption disappears if part of the home is rented or used for child care.¹⁰

Radon-Resistant New Construction

DuPage County sits in EPA Zone 1, where predicted average indoor radon levels exceed the action threshold. The ANSI/AARST CCAH-2020 standard covers radon-resistant techniques in new one- and two-family homes, including rough-in of control components during construction and post-build testing.¹¹ Passive radon piping installed during construction costs far less than retrofitting a full mitigation system later.

OSHA Fall Protection

Federal rules require fall protection for any worker on a surface six feet or more above a lower level, which covers most residential roof lines and upper-story framing. The rule applies to contractors and their employees, not to homeowners working on their own property, but an OSHA citation against your contractor can delay the job.¹²

Fair Housing Act Design and Construction

New multifamily buildings with four or more units must meet Fair Housing Act design requirements covering accessible entrances, 32-inch minimum clear door widths, reinforced bathroom walls for future grab bars, and usable kitchen and bathroom layouts. All units in elevator buildings, and all ground-floor units in buildings without an elevator, are covered. These rules have been in effect since 1991 and are enforced independently of local code.¹³

Floodplain Construction

Property in a Special Flood Hazard Area must comply with the National Flood Insurance Program on top of the county’s stormwater ordinance. Residential buildings must have their lowest floor elevated to or above the Base Flood Elevation. Basements below the BFE are only allowed where the community has obtained a specific FEMA exception, and even then must be floodproofed and certified by a licensed architect or engineer.¹⁴ If your lot is near a creek, river, or mapped flood zone, check the flood maps before finalizing plans.

1
DuPage County, IL. Building Code
2
DuPage County, IL. Sheds
3
DuPage County, IL. Swimming Pools, Spas, Hot Tubs
4
DuPage County, IL. Decks
5
DuPage County, IL. Building and Zoning Fee Schedule
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DuPage County, IL. Accela Citizen Access
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DuPage County, IL. Building and Permits
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Municode Library. DuPage County Code of Ordinances – Article IV Stormwater Management Certifications
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Municode Library. DuPage County Code of Ordinances – Article XIV Prohibited Acts and Enforcement Penalties
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US EPA. Lead Renovation, Repair and Painting Program
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U.S. Environmental Protection Agency. Radon Standards of Practice
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Occupational Safety and Health Administration. Duty to Have Fall Protection
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U.S. Department of Housing and Urban Development. Fair Housing Act Design Manual
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FEMA.gov. Residential Buildings with Basements