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

A single-family home in unincorporated Mineral County does not need a building permit¹. Mineral County is under state building-code jurisdiction, where residential buildings with fewer than five dwelling units and farm and ranch buildings are exempt from state building permits². An owner working on the owner's property is conditionally exempt from contractor registration, but the exemption does not erase zoning, septic, floodplain, subdivision or other applicable requirements⁵. A residence serving transient guests is outside the residential exemption, so a short-term rental project may need a state building permit and a state Property Manager license unless another exemption applies^2,12.

Mineral County does not operate a local building-permit program¹. Mineral County Environmental Health and Planning handles septic regulation and publishes forms for land-use, subdivision and floodplain applications, although its page does not give a complete review timeline⁴. The office can be reached at (406) 822-3525⁴. The FY 2024 schedule lists $100 for a floodplain determination, $175 with a site visit, $400 for a small-scale floodplain permit and $1,000 for a large-scale permit¹³. County-road driveway and approach permits go through the Mineral County Road Department at (406) 822-3560¹⁴. For a nonexempt project, building permits and inspections come from the Montana Building Codes Program at (406) 841-2056^2,15.

Mineral County has no countywide zoning, while the Town of Alberton has local zoning districts that the town—not the county—administers^7,8. Subdivision and floodplain rules can still affect development outside a zoning district^16,17. In Alberton's R-1 district, a permitted use generally needs a 5,000-square-foot lot at least 34.5 feet wide; existing recorded lots, multifamily dwellings, mobile-home parks and other land uses have separate standards⁸. R-1 permitted-use setbacks are 15 feet in front, 5 feet in the rear and at least 7.5 feet at the side, with separate rules for conditional uses, corner lots, alleys and accessory buildings⁸. An Alberton manufactured home treated as a single-family dwelling must be at least 1,000 square feet, sit on a permanent foundation and meet the ordinance's other conditions⁸.

Mineral County Environmental Health and Planning regulates and permits septic and wastewater treatment systems and publishes the county regulations and permit request⁴. The application must include the applicable fee before review, and construction without an issued installation permit or approved site evaluation carries a $500 fee¹⁸. The installer must notify the department at least 48 hours before completion, and the completed system needs a final inspection before it is covered¹⁹. Only 0.1 percent of Mineral County soils are rated without severe limitations for a conventional septic drain field, so make septic feasibility an early purchase contingency²⁰. State subdivision sanitation approval does not replace the local drainfield permit²¹.

Inside the Town of Superior, camping on private property requires the owner's explicit permission, while public-place camping is restricted by season and overnight hours unless the appropriate agency authorizes it⁹. Superior also requires RV sink water and sewage to go only to a disposal site approved by Mineral County Environmental Health and Planning⁹. We could not confirm a countywide rule allowing or prohibiting one household from living in one RV, or a countywide tiny-home rule; ask Environmental Health and Planning about the parcel's wastewater plan and floodplain status before moving an RV or tiny home onto the site⁴.

1. Confirm whether the parcel is inside Alberton's zoning jurisdiction or Superior, where the town camping rule applies^8,9.
2. Confirm that the project qualifies for Montana's building-permit exemption; contact the Montana Building Codes Program about a nonexempt project^2,15.
3. If you will do the plumbing personally, confirm that the home is for your own use and is neither speculative resale construction nor a rental before relying on the state plumbing-permit exemption⁶.
4. Start septic review with Environmental Health and Planning and make feasibility a purchase contingency because only 0.1 percent of local soils are rated without severe limits for a conventional drain field^4,20.
5. Ask the Floodplain Administrator whether the site is in a Special Flood Hazard Area before placing fill, cutting a road, installing a culvert or starting construction^4,17.
6. For a new or expanded well, check the permit-exception limits and file the required Notice of Intent before using the water¹¹.
7. Obtain any required state-highway approach authorization and county land-use, subdivision or floodplain approvals before work begins^4,10.

Mineral County is steep, forested and mostly public land: only 8.1 percent of the county is at a 15 percent slope or less, 91.8 percent is wooded, and 82 percent is federal land²⁰. Only 0.1 percent of county soils are rated without severe limitations for a conventional septic drain field, so make buildability and septic feasibility purchase contingencies²⁰. Ask the Floodplain Administrator whether a streamside parcel is in a Special Flood Hazard Area; permitting can apply to fill, roads, culverts, manufactured homes and building work^4,17. An agricultural-use-only land division may qualify for exemption from local subdivision review, but adding a building that needs water or sewer or later changing the parcel's use can trigger review¹⁶. The effective property-tax rate is about 0.6 percent, and the median annual property-tax bill is about $1,728²⁰.