ADUs are allowed in OfallonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Ofallon, MO
Is your property eligible for an ADU?
# of Properties
32,319
Owner-occupied
88%
Zoning districts
46
Avg Home Value
$363,193
Median Lot Size
0.21 acres
Avg Income
$118,125
Residential Types:
32,319 housing units
Single Family
83%
2-3 Family
1%
Other
16%
Zoning Districts:
36,050 parcels · 46 districts
R-1
70%(25,248)
R-3
11%(3,831)
R-4
6%(2,298)
MUTD
3%(986)
Other
10%(3,687)
ADU Rules
What can you build in Ofallon, MO?
Ofallon, MO follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: By Right
- –Detached ADU: By Right
Interior / Attached ADU Size Limits
- –Maximum ADU size of 800 sq ft, or 1,000 sq ft on lots at least 1 acre in size.
Detached ADU Size Limits
- –Maximum detached ADU size of 800 sq ft, or 1,000 sq ft on lots at least 1 acre.
Max Units
- –1 ADU per single-family lot
Owner Occupancy
- –Owner-occupancy not required.
Parking
- –No min/max stated; unlisted uses follow the most similar use or APA PAS guidance; alternative parking study allowed.
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 Missouri municipalities
Rules change at the town line. Check the municipality your property is actually in.
St. Charles County