Montana Statewide Rule
Montana Subdivision and Platting Act Setback Framework
Key Facts
- Duplex law
- SB 323 (cities over 5,000)
- ADU law
- SB 528 / MCA 76-2-345
- Planning act
- SB 382 Land Use Planning Act
- Subdivision review
- MCA 76-3-101
Summary
Montana setbacks are set by local zoning, but 2023 housing laws limit them: SB 323 requires cities over 5,000 to allow duplexes on single-family lots, and SB 528 (MCA 76-2-345) requires ADUs. Setbacks cannot be used to effectively prohibit these housing types.
(3) In a city with a population of at least 5,000 residents, duplex housing must be allowed as a permitted use on a lot where a single-family residence is a permitted use, and zoning regulations that apply to the development or use of duplex housing may not be more restrictive than zoning regulations that are applicable to single-family residences.
Full Breakdown
Setbacks are primarily local, but Montana's 2023 housing reforms constrain them. SB 323 requires municipalities over 5,000 population to allow duplexes on lots zoned for single-family use; SB 528, codified at MCA 76-2-345, requires those cities to allow accessory dwelling units. SB 382 enacted the separate Montana Land Use Planning Act governing how larger cities plan and zone. Local setback standards remain but cannot effectively bar a state-allowed duplex or ADU. Several of these laws drew litigation and injunctions, so confirm current status. The Subdivision and Platting Act (MCA 76-3-101 et seq.) still frames local subdivision review.
Violations & Penalties
State-preemption challenges are available when local setbacks effectively prohibit a duplex or ADU that 2023 law requires cities to allow.
Frequently Asked Questions
Can Montana cities still set their own building setbacks?
Does Montana have a statewide minimum setback?
Sources
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