Accessory Dwelling Unit (ADU) Rules for Unincorporated Madison, IL

Is your property eligible for an ADU?

# of Properties

27,183

Owner-occupied

73%

Zoning districts

Avg Home Value

$74,970

Median Lot Size

0.72 acres

Avg Income

$101,684

Residential Types:

27,183 housing units

Single Family

Apts (4+ units)

13%

Condos

Other

85%

Zoning Districts:

34,336 parcels · 62 districts

45%(15,518)

29%(9,894)

10%(3,438)

6%(2,211)

Other

10%(3,275)

ADU Rules

What can you build in Unincorporated Madison, IL?

Unincorporated Madison, IL follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.

Eligibility

–Internal / Attached ADU: Conditional Use Permit
–Detached ADU: Special Permit

Detached ADU Size Limits

–Detached ADU area may not exceed 1,000 sq ft.

Parking

–No ADU-specific parking; min/max not stated; unlisted uses follow parking for the most similar listed use as determined by the Zoning Administrator.

What's allowed on your lot?

These are the municipality-wide rules. What's allowed on a specific property also depends on state laws, setbacks, floor area ratio, lot coverage, environmental constraints, topography, and other property-specific factors. Search your address on FutureLot to see what's allowed on your property.

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Is your property eligible for an ADU?

ADU rules in other Illinois municipalities

Rules change at the town line. Check the municipality your property is actually in.

Madison County

Alton Edwardsville Granite City

See all municipalities in Madison County →See all Illinois municipalities →