MT · State directory
Montana ADU rules
Official accessory dwelling unit regulations for 13 jurisdictions in Montana, plus statewide law.
Not sure which city yet?
We have read the ordinances for 13 Montana cities and lined them up side by side: detached vs internal, size limits, owner occupancy, and approval process.
Statewide ADU law
Montana has state-level ADU legislation that applies across local jurisdictions. Local rules below may add requirements on top of state law.
- mca.legmt.govOfficial sourceVerified August 2026https://mca.legmt.gov/bills/mca/title_0760/chapter_0020/part_0030/section_0450/0760-0020-0030-0450.html
- mca.legmt.govOfficial sourceVerified August 2026https://mca.legmt.gov/bills/mca/title_0760/chapter_0020/part_0020/section_0150/0760-0020-0020-0150.html
Cities
Belgrade6 sources · verified August 2026Billings5 sources · verified August 2026Bozeman4 sources · verified August 2026Butte-Silver Bow4 sources · verified August 2026Columbia Falls4 sources · verified August 2026Great Falls4 sources · verified August 2026Helena4 sources · verified August 2026Kalispell4 sources · verified August 2026Livingston3 sources · verified August 2026Missoula4 sources · verified August 2026Whitefish4 sources · verified August 2026
Counties & regions
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