ADUs are allowed in Unincorporated JeffersonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Jefferson, MO
Is your property eligible for an ADU?
# of Properties
72,112
Owner-occupied
82%
Zoning districts
36
Avg Home Value
$1,634,560
Median Lot Size
0.57 acres
Avg Income
$93,036
Residential Types:
72,112 housing units
2-3 Family
1%
Apts (4+ units)
1%
Other
98%
Zoning Districts:
78,294 parcels · 36 districts
R07
24%(18,638)
LR2
21%(16,357)
R40
18%(14,005)
R10
15%(11,713)
Other
22%(17,581)
ADU Rules
What can you build in Unincorporated Jefferson, MO?
Unincorporated Jefferson, 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
Detached ADU Size Limits
- –Maximum ADU area is the remaining share of the combined accessory-building cap: RA-5/LR-2 use the larger of 4,000 sq ft or 5% of lot area not occupied by the principal building; R-40/R-20/R-10/R-7 use the larger of 1,200 sq ft or 5% of that area; subtract existing accessory-building area.
Owner Occupancy
- –No owner-occupancy requirement for ADUs.
Parking
- –Sufficient on-site parking required for the ADU; cannot be satisfied by the driveway. Loft above a detached garage requires additional on-site parking beyond the principal driveway.
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.
Jefferson County