ADU rules for Alton
Accessory Dwelling Unit (ADU) Rules for Alton, IL
Is your property eligible for an ADU?
# of Properties
12,841
Owner-occupied
50%
Zoning districts
20
Avg Home Value
$26,201
Median Lot Size
0.16 acres
Avg Income
$58,876
Residential Types:
12,841 housing units
Single Family
1%
Apts (4+ units)
18%
Condos
3%
Other
79%
Zoning Districts:
14,719 parcels · 20 districts
R-2
75%(11,015)
R-1
9%(1,309)
C-2
5%(754)
R-3
3%(370)
Other
9%(1,271)
ADU Rules
What can you build in Alton, IL?
Alton, IL follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: Not addressed in the local bylaw
- –Detached ADU: Not addressed in the local bylaw
Parking
- –No ADU-specific parking standard identified. Citywide off-street parking not required in C-4/MR; general residential standard is two spaces per dwelling unit, which may apply absent an ADU rule.
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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ADU rules in other Illinois municipalities
Rules change at the town line. Check the municipality your property is actually in.
Madison County