ADUs are allowed in Unincorporated MadisonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Madison, ID
Is your property eligible for an ADU?
# of Properties
2,847
Owner-occupied
78%
Zoning districts
28
Avg Home Value
$248,809
Median Lot Size
1.08 acres
Avg Income
$94,677
Residential Types:
2,847 housing units
Single Family
13%
Other
87%
Zoning Districts:
8,521 parcels · 28 districts
TAG
47%(4,003)
AG
37%(3,155)
RR1
4%(371)
C
3%(269)
Other
8%(723)
ADU Rules
What can you build in Unincorporated Madison, ID?
Unincorporated Madison, ID 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
- –For lots under 2 acres, maximum ADU size is the greater of 1,500 sq ft or 50% of the primary dwelling (including basement); no size limit on lots 2 acres or larger.
Detached ADU Size Limits
- –On lots under 2 acres, a detached ADU may be up to the larger of 1,500 sq ft or 50% of the primary residence’s total area (including basement). On lots 2 acres or larger, there is no size cap.
Parking
- –1 off-street space per 2 bedrooms (to support both primary dwelling and ADU); no max. ADU permit required; Planning Commission may waive parking on appeal if it does not diminish health, safety, or welfare.
Rental Restrictions
- –One unit must be owner-occupied; renting both the primary residence and the ADU simultaneously is prohibited. ADUs must comply with rental regulations and any short-term rental rules.
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.
Check my propertyHow can we help you?
Get matched with trusted local builders
Understand what's allowed on your property
Learn the key rules and size limits for ADUs
Is your property eligible for an ADU?
ADU rules in other Idaho municipalities
Rules change at the town line. Check the municipality your property is actually in.
Madison County