ADU Rules in Springfield, Illinois

Springfield is the Illinois state capital and Sangamon County seat with a population of about 114,000 in central Illinois. Known as the "Land of Lincoln," Springfield is where Abraham Lincoln lived, practiced law, and launched his political career — the Lincoln Home National Historic Site is managed by the National Park Service. Illinois has no statewide ADU preemption law — Springfield's local zoning governs.

Springfield Zoning Code

The City of Springfield Zoning Ordinance governs all land use. Springfield has a mix of historic urban neighborhoods, state government office areas, mid-century residential development, and newer suburbs.

Permitted ADU Types

Depending on the residential zone:

• Accessory apartments: Conversion within primary structure
• Detached accessory dwelling units: In rear yards of eligible residential zones

Verify current ADU-specific provisions with the Springfield Office of Planning and Economic Development.

Size Limits

Accessory dwelling units in Springfield are subject to:

• Maximum floor area per zone
• Lot coverage restrictions

Verify current limits with Springfield Planning.

Setbacks

Per Springfield residential zone (typical):

• Rear: Minimum setback
• Side: Minimum setback
• Accessory structures: Per zoning ordinance

Lincoln Home National Historic Site Area

The Lincoln Home NHS (managed by the NPS) encompasses four blocks in Springfield's central area. Properties adjacent to or near the Lincoln Home NHS area may have additional considerations for exterior changes, depending on local historic overlay districts.

Historic Districts

Springfield has locally designated historic districts beyond the NPS area. Properties in local historic districts may require Historic Sites Commission review for exterior modifications associated with ADU construction.

State Government Proximity

As the state capital, much of Springfield's land use and economy revolves around state government. Residential areas near the Capitol complex may have mixed zoning. Verify your property's zoning district before planning.

Lake Springfield Floodplain

Parts of Springfield near Lake Springfield (the city reservoir) and Sangamon River tributaries may be in FEMA flood zones. Verify flood map status for relevant properties.

Permit Process

1. Verify zoning: Springfield Office of Planning and Economic Development
2. Check historic district status: If near Lincoln Home NHS or local historic district
3. Check flood zone status: If applicable
4. Submit plans: Springfield Building and Zoning Division
5. Building permit and inspections
6. CO: Required before occupancy

Contact

City of Springfield Office of Planning and Economic Development 800 East Monroe Street, Springfield, IL 62701 Phone: (217) 789-2377 Website: springfield.il.us

Disclaimer: Illinois has no statewide ADU law. Springfield zoning governs locally. Properties near Lincoln historic sites may have additional review requirements. Verify current ADU allowances with the City of Springfield before starting any project.