ADUs are allowed in Unincorporated FlatheadTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Flathead, MT
Is your property eligible for an ADU?
# of Properties
3,622
Owner-occupied
22%
Zoning districts
85
Avg Home Value
$597,693
Median Lot Size
0.02 acres
Avg Income
$85,156
Residential Types:
3,622 housing units
Single Family
19%
Apts (4+ units)
6%
Condos
65%
Other
11%
Zoning Districts:
36,357 parcels · 85 districts
SC
20%(7,095)
R-2
11%(4,001)
R-1
9%(3,362)
SAG-10
7%(2,636)
Other
53%(19,263)
ADU Rules
What can you build in Unincorporated Flathead, MT?
Unincorporated Flathead, MT 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 internal ADU size is the greater of 1,000 sq ft or 40% of the principal single-family home’s habitable space.
Detached ADU Size Limits
- –Maximum detached ADU size is the greater of 1,000 sq ft or 40% of the principal dwelling’s habitable floor area.
Parking
- –1 space per 400 sq ft of ADU gross floor area; maximum 2 spaces; no ADU-specific exemptions; general residential parking rules apply (on same lot, front-yard setback limits)
Rental Restrictions
- –Minimum rental term of 30 days or longer; short-term rentals under 30 days are not within the ADU use and require Administrative Conditional Use approval under Short-term Rental Housing where 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 Montana municipalities
Rules change at the town line. Check the municipality your property is actually in.
Flathead County