Building permits, zoning and land rules in Gallatin County, Montana

Gallatin County does not issue building permits and directs applicable projects outside Bozeman and Belgrade to the Montana State Building Department¹. In state jurisdiction, residential buildings with fewer than five dwelling units are exempt from state building permits unless serving transient guests; local requirements may still apply². Farm and ranch buildings also fall within the state building-permit exemption, which does not establish exemption from separate electrical, plumbing or mechanical requirements². Montana adopts a uniform state building code; applicability depends on state exemptions and certified local jurisdiction¹¹.

In county-zoned unincorporated Gallatin County, a Land Use Permit is separate zoning approval generally required before building, moving a structure or making structural alterations, subject to district exceptions¹. Pouring concrete or installing permanent improvements before that approval is prohibited; preparatory site work is at the landowner’s risk¹. Structures exempt from Land Use Permitting still must meet applicable setbacks, height and lot-coverage standards¹².

For applicable projects in state jurisdiction, contact the Montana State Building Department at 406-841-2040; Gallatin County issues no building permits¹. Town of Manhattan issues building permits for buildings or enclosed structures greater than 200 square feet, and Town of West Yellowstone requires building permits for covered construction and structural changes^3,13. Local septic permitting stays with the Gallatin City-County Health Department throughout the county⁴.

For state-permitted projects, the permit holder must notify the inspector when work is ready and provide access². County zoning approval is separate: the Planning Director may require a Certificate of Completion and zoning-compliance inspection with a Land Use Permit or Change of Use Permit¹². Reach Gallatin County Planning & Community Development at 406-582-3130 or planning@gallatin.mt.gov for unincorporated-land zoning questions^1,14.

Gallatin County publishes 22 zoning districts with distinct requirements; identify the parcel’s district and subdistrict before applying development standards to unincorporated land⁵. Bozeman, Town of Manhattan, Three Forks and Town of West Yellowstone set their own zoning inside municipal limits^15,16,17,18. Local septic approval remains with the Gallatin City-County Health Department⁴.

Bear Canyon residential standards require front yards of 35 feet, rear and side yards of 25 feet, and building setbacks of 65 feet from the centerline of Bozeman Trail Road, Mount Ellis Lane, Bear Canyon Road or any county road in the district¹⁹. Bear Canyon residential building height is capped at 32 feet¹⁹. East Gallatin’s Neighborhood Commercial and Commercial districts require front and rear setbacks of 15 feet and side setbacks of 10 feet²⁰.

Short-term rentals unlisted in a zoning district’s regulations are prohibited there; unzoned areas have no county zoning restriction on that use, but Health Department public-health and sanitation permitting applies in both zoned and unzoned areas²¹.

Gallatin County minimum lot sizes depend on the zoning district and subdistrict; unzoned land divisions still need Planning Department review of applicable subdivision processes⁹. In Gallatin Canyon/Big Sky, R-SF-7,500 and R-SF-11,000 require 7,500 and 11,000 square feet respectively, while RC-SF lists no minimum lot size; other development standards still apply⁶. The Recreational Business subdistrict requires at least one acre⁶.

River Rock requires 4,500 square feet and 45 feet of width for Duplex Townhouse and Traditional Single Family lots; other permitted principal uses require 7,500 square feet and 70 feet of width²². Zoning District 6 Agriculture Exclusive requires 40 acres and 660 feet of width, except for agricultural-production land²³. Residential Suburban districts there require at least one acre and 150 feet of width, with larger lots possible because of district designation, soils or groundwater²³.

The Gallatin City-County Health Department requires an approved septic permit before any non-public or public wastewater treatment system is installed in Gallatin County⁴. Applications need signed wastewater-treatment and property-information-request forms, fee payment and a scaled site plan; site evaluation must be performed by a county Registered Site Evaluator or Montana-registered professional engineer, and a county Registered Installer must be on-site during installation²⁴. Call Environmental Health at 406.582.3120 or email ehs@gallatin.mt.gov⁴.

Montana DEQ has primary responsibility for public wastewater systems serving more than 24 people for more than 60 days a year or having more than 14 connections⁴. Only 20.6% of Gallatin County soils are rated not limited for conventional drain fields; this supports evaluating the site before purchase, not assuming septic is impossible elsewhere¹⁰.

We could not confirm a countywide tiny-home occupancy rule; ask Gallatin County Planning how the proposed dwelling fits the parcel’s district^5,14. River Rock’s Residential Single Family Medium Density district requires each dwelling unit to have at least 900 square feet of floor area and limits lot coverage to 40%, a concrete constraint on a small-home design there²².

In Gallatin Canyon/Big Sky, temporary personal-use camping with no more than five tents or RVs falls outside the campground definition; that provision does not authorize permanent RV residence⁶. Renting multiple RV spaces requires subdivision review, and RV parks in the Commercial and Industrial Mixed Use subdistrict are conditional uses subject to campground, utility and subdivision standards^6,7.

1. Ask Gallatin County Planning to identify the parcel’s zoning district and the required Land Use Permit; call 406-582-3130 or email planning@gallatin.mt.gov^1,5,14.

1. Assemble applicable wastewater, floodplain and road-access documentation; wastewater evidence can include a septic permit or approval to connect to an existing system, plus Montana DEQ subdivision approval where applicable^1,12.

1. Submit the complete Land Use Permit application through MyGov and allow at least four weeks for staff processing, subject to seasonal demand⁵. Planning’s new fee schedule took effect September 21, 2026; credit-card payments add 3%, while check and cash payments are accepted^5,14.

1. Ask the Montana State Building Department which building and trade permits apply outside Bozeman and Belgrade; separate electrical, plumbing and mechanical permits may be required².

1. Obtain required county land-use approval before pouring concrete or installing permanent improvements, and arrange applicable state inspections and any county Certificate of Completion inspection^1,2,12.

Start with County Planning to identify zoning, allowable use and Land Use Permit requirements, then establish approved wastewater service before submitting the application^1,5,12. In unincorporated regulatory floodplains, grading, excavation, fill, bank stabilization and structures require floodplain approval; mapped floodplains do not cover every flood threat²⁵. Access onto a county-maintained road needs county road-access approval, while access under Montana Department of Transportation jurisdiction needs an approach permit^12,26. Subdivision fire-access standards additionally require access within 150 feet of all building exterior parts and capacity for a 30-ton, two-axle fire apparatus; those standards are not a universal driveway rule²⁷.

Land divisions that do not qualify for an exemption follow county subdivision review; the agricultural exemption requires the created parcel to be used exclusively for agriculture⁹. A qualifying homeowner may personally install plumbing in a personal-use home without a state plumbing permit, provided the home is not intended for rental or speculative resale⁸. For a new well using the Montana permit exception, DNRC requires a Notice of Intent before water use beginning in 2026²⁸.