ADUs are allowed in Unincorporated WilliamsonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Williamson, TN
Is your property eligible for an ADU?
# of Properties
13
Zoning districts
42
Zoning Districts:
29,121 parcels · 42 districts
RD-5
18%(5,333)
RP-5
18%(5,175)
NC
16%(4,781)
MGA-1
16%(4,583)
Other
32%(9,249)
ADU Rules
What can you build in Unincorporated Williamson, TN?
Unincorporated Williamson, TN 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 size is the greater of 750 sq ft or 25% of the principal dwelling’s floor area, but not more than 75% of that floor area.
Detached ADU Size Limits
- –Maximum detached ADU size is the greater of 750 sq ft or 25% of the principal dwelling, but never more than 75% of the principal dwelling.
- –Detached ADU structure size cap: lots ≤1 acre—min(75% of principal dwelling, 2,000 sq ft); >1 and <5 acres—max(75% of principal dwelling, 2,000 sq ft); ≥5 acres—max(75% of principal dwelling, 2,000 sq ft) (may be exceeded if principal setbacks are met).
Owner Occupancy
- –No owner-occupancy requirement stated.
Parking
- –No ADU-specific minimum; max = 125% of the minimum for the development (may exceed with an approved alternative plan); Planning Director determines minimum for uses not listed; shared/alternative parking options may be approved.
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 Tennessee municipalities
Rules change at the town line. Check the municipality your property is actually in.
Williamson County