County seat: Missoula
Building in Missoula County
How zoning works here
This county administers zoning across the unincorporated county.
Missoula County has countywide zoning regulations (revised 2026) covering unincorporated areas outside the City of Missoula; the county uses a Consolidated Planning Board that serves both city and county jurisdictions.
Building permits
This county issues building permits for unincorporated areas
Missoula County is a certified local government for building code enforcement. The county Building Division issues building permits for structures in unincorporated Missoula County (outside Missoula city limits). Within the City of Missoula, the City Development Services department handles permits (contact 406-552-6630).
Who to call
Sanitation / septic
Missoula Public Health — Environmental Health / Land Sanitarian
Subdivision review
Missoula County Department of Planning, Development and Sustainability
Cities with their own jurisdiction
Inside these limits the municipality, not the county, is generally the planning and permitting authority: Missoula, Stevensville, Hamilton (shared with Ravalli), Seeley Lake.
Check a specific parcel in Missoula County
County rules are only part of the picture. Terrain, soils, septic feasibility, flood, wetlands and access are parcel-specific.
County authority details researched from primary county sources and verified 2026-08-14. County rules change and this page is a starting point, not a determination. Confirm anything you intend to rely on directly with the office that administers it. Sources: www.missoulacounty.us, www.missoulacounty.us, www.missoulacounty.us, missoulapublichealth.org