ADUs are allowed in CollinsvilleTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Collinsville, IL
Is your property eligible for an ADU?
# of Properties
9,751
Owner-occupied
70%
Zoning districts
42
Avg Home Value
$56,468
Median Lot Size
0.26 acres
Avg Income
$68,313
Residential Types:
9,751 housing units
Apts (4+ units)
7%
Condos
1%
Other
92%
Zoning Districts:
10,780 parcels · 42 districts
R-1
52%(5,612)
R-1A
25%(2,683)
R-3
8%(853)
B-4
3%(319)
Other
12%(1,313)
ADU Rules
What can you build in Collinsville, IL?
Collinsville, 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: Conditional Use Permit
Detached ADU Size Limits
- –Maximum detached ADU floor area is capped by the cumulative accessory-structure limit by lot size (1,500 sq ft under 2 acres; 2,250 sq ft at 2+ acres; 3,000 sq ft at 3+ acres) and may not exceed the primary building’s base floor area.
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.
St. Clair County