ADUs are allowed in Great FallsTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Great Falls, MT
Is your property eligible for an ADU?
# of Properties
2,521
Owner-occupied
37%
Zoning districts
20
Avg Home Value
$443,156
Median Lot Size
0.04 acres
Avg Income
$66,045
Residential Types:
2,521 housing units
Single Family
13%
Apts (4+ units)
38%
Condos
47%
Other
2%
Zoning Districts:
22,917 parcels · 20 districts
R-3
46%(10,560)
R-2
25%(5,672)
PUD
5%(1,128)
R-9
4%(979)
Other
20%(4,578)
ADU Rules
What can you build in Great Falls, MT?
Great Falls, 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
Detached ADU Size Limits
- –Detached accessory dwelling units are not permitted; no detached ADU floor area is allowed.
Owner Occupancy
- –No owner-occupancy requirement for ADUs.
Parking
- –No ADU-specific parking; min/max not stated. General residential rates apply; accessory living spaces not fully independent and have no separate parking; reductions possible via shared parking and Director approvals (C-4/C-5).
Rental Restrictions
- –Detached ADU may not be rented or leased at all; short-term rentals prohibited; may only be used by the principal occupant, the occupant’s immediate family, or unpaid temporary guests for up to 30 days.
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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Is your property eligible for an ADU?
ADU rules in other Montana municipalities
Rules change at the town line. Check the municipality your property is actually in.
Cascade County