Accessory Dwelling Unit (ADU) Rules for Big Sky, MT

Is your property eligible for an ADU?

# of Properties

Zoning districts

Zoning Districts:

2,484 parcels · 23 districts

R-SF-11000

18%(452)

RC-SF-20

14%(357)

RC-SF-2.5

12%(294)

RC-SF-10

10%(249)

Other

46%(1,132)

ADU Rules

What can you build in Big Sky, MT?

Big Sky, 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 ADU floor area of 1,000 sq ft on lots under 10 acres; 2,000 sq ft on lots 10 acres or larger.

Detached ADU Size Limits

–Maximum detached ADU floor area: 1,000 sq ft on lots under 10 acres; 2,000 sq ft on lots 10 acres or larger.

Max Units

–1 ADU per Single-family Dwelling Unit

Parking

–2 spaces/ADU; Town Center Parking Plan may count on-street spaces; shared parking allowed with CUP/PUD up to 30% reduction; spaces within 100 ft of the unit; water-quality measures apply

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.

Gallatin County

See all municipalities in Gallatin County →See all Montana municipalities →

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