Unincorporated Yellowstone County building permits

Building department

Address

301 South Park Ave, Floors 4-5, Helena, MT 59620 (mailing: Building Codes Bureau, PO Box 200517, Helena, MT 59620-0517)

Phone

(406) 841-2056

Email

buildingcodes@mt.gov

Office hours

Mon–Fri, state business hours; online permitting available 24/7 via https://aca-prod.accela.com/bcb/

Website

Official site

Inspection guide

See how inspections work in Unincorporated Yellowstone County — sequence, scheduling & re-inspection fees.

Codes adopted

Montana adopts a single statewide building code by rule and, by default, enforces it directly — local governments only gain enforcement authority once the state certifies them. Under the Montana Building Codes Act (Mont. Code Ann. Title 50, Chapter 60), the Department of Labor & Industry's Building Codes Bureau adopts one state building code applicable everywhere (§ 50-60-203, codified further at Administrative Rules of Montana Title 24, Chapter 301) — currently the 2021 editions of the IBC, IRC, IMC, IFGC, IECC, IEBC, ISPSC, and UPC, with the 2020 NEC for electrical (effective statewide since 6/11/2022 per the Bureau's own Current Codes page). A city, county, or town may adopt and enforce its own building-code program under § 50-60-301, but its adopted code "may include only codes adopted by the Building Codes Bureau" — a local edition can never diverge from or be less stringent than the state's. Critically, under § 50-60-302, a local government cannot enforce ANY building code — even one it has formally adopted — until the Bureau certifies its program (requiring an approved code, a published fee schedule, an enforcement plan, and properly licensed or nationally certified inspectors); certification is granted per TRADE, not as one blanket designation. The Bureau's own "Certified City, County and Town Programs" list uses the key B=Building, P=Plumbing, E=Electrical, M=Mechanical, SP=Pool, W=Wildland-Urban-Interface — a jurisdiction can be certified for Building only while Electrical/Plumbing/Mechanical remain directly state-enforced within the same city limits (e.g., Havre, Anaconda-Deer Lodge), or certified across all trades (e.g., Billings, Missoula, Great Falls, Bozeman, Helena, Kalispell). Non-certified jurisdictions — most of Montana's unincorporated county land, since very few counties appear on the certified list — fall under direct enforcement by the state Building Codes Bureau (§ 50-60-304). Montana also exempts private homes and buildings of four or fewer dwelling units not serving transient guests from the state building-permit requirement entirely, though electrical, plumbing, and mechanical permits remain separately required regardless. Always confirm with the specific jurisdiction which trades it is certified for versus which remain directly state-enforced.

• 2021 International Building Code (IBC) — adopted statewide by ARM Title 24, Chapter 301; effective June 11, 2022
• 2021 International Residential Code (IRC) — ARM Title 24, Chapter 301; effective June 11, 2022
• 2021 International Existing Building Code (IEBC) — ARM Title 24, Chapter 301; effective June 11, 2022
• ICC A117.1-2017 (Accessibility) — ARM Title 24, Chapter 301; effective June 11, 2022
• 2021 Uniform Plumbing Code (UPC) — ARM Title 24, Chapter 301; effective June 11, 2022 (fixture table at ARM 24.301.351)
• 2021 International Mechanical Code (IMC) — ARM Title 24, Chapter 301; effective June 11, 2022
• 2021 International Fuel Gas Code (IFGC) — ARM Title 24, Chapter 301; effective June 11, 2022
• 2020 National Electrical Code (NEC) — ARM Title 24, Chapter 301; effective June 11, 2022 (NEC Technical Advisory NEC_TIA-23-3_210.8 issued August 12, 2022)
• 2021 International Energy Conservation Code (IECC) — ARM Title 24, Chapter 301; effective June 11, 2022
• 2021 International Swimming Pool and Spa Code (ISPSC) — ARM Title 24, Chapter 301; effective June 11, 2022
• 2021 Wildland Urban Interface Code (WUIC) — ARM Title 24, Chapter 301; effective June 11, 2022
• NOTE: All codes listed are statewide codes administered directly by the Montana Building Codes Bureau for areas (like unincorporated Yellowstone County) that are NOT within a certified local-government building code jurisdiction.

Permit types & fees

• Residential Building Permit

  In unincorporated Yellowstone County, Yellowstone County itself issues NO building permits or Certificates of Occupancy — confirmed directly by the county: 'Yellowstone County does not issue Building Permits or Certificates of Occupancy for structures outside the city limits of Billings.' Building permit authority instead sits with the Montana Building Codes Bureau (state DLI), EXCEPT that Montana state law exempts private homes and apartment buildings of four or fewer dwelling units (that do not serve transient guests) from the state building permit requirement entirely. Practical effect: most single-family homes, duplexes, triplexes, and fourplexes built in unincorporated Yellowstone County require NO building permit from any government body — county or state — for the structure itself. A state building permit IS required for 5+ unit residential buildings and any non-exempt structure.

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• Electrical Permit

  All electrical work in unincorporated Yellowstone County requires a State Electrical Permit from the Montana Building Codes Bureau, since Yellowstone County is not a certified local government for electrical code enforcement. Homeowners may wire their own home under a Homeowner Electrical Permit; all other work requires a Montana-licensed electrical contractor. Governed by Title 50, Chapter 60, Section 604, MCA and ARM 24.301.431.

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• Plumbing Permit

  Plumbing work in unincorporated Yellowstone County is permitted directly by the Montana Building Codes Bureau under Title 50, Chapter 60, Section 505, MCA and ARM 24.301.301/24.301.361, since the county is not a certified local plumbing-code jurisdiction. A per-fixture fee schedule applies. Homeowners performing their own plumbing on their own owner-occupied, non-rental residence are exempt from needing a permit.

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• Mechanical / HVAC Permit

  HVAC, furnace, gas piping, and other mechanical work in unincorporated Yellowstone County requires a State Mechanical Permit from the Montana Building Codes Bureau under Title 50, Chapter 60, Section 104, MCA and ARM 24.301.172, since the county is not a certified local mechanical-code jurisdiction. The fee is calculated from the total cost of the mechanical system installed.

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• Roofing Permit (Reroof)

  Reroofing is listed as a 'Type of Work' option (Reroof) on the Montana state Application for Building Permit. Because most single-family and up-to-fourplex residential structures are exempt from the state building permit requirement in Montana (private homes/apartments with four or fewer units not serving transient guests), a straightforward residential re-roof on an exempt dwelling generally does NOT require a state building permit. Confirm applicability with the Building Codes Bureau for your specific structure.

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• Solar Panel Permit

  Solar installations in unincorporated Yellowstone County are permitted through the Montana Building Codes Bureau's electrical/alternative-energy permitting track — there is no separate 'solar permit'; instead, the permit type depends on who performs the installation and whether it is grid-tied. The Bureau publishes a specific solar permitting decision flow for new residential construction.

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• Accessory Dwelling Unit (ADU)

  Montana has no ADU-specific state permit type; an ADU in unincorporated Yellowstone County is permitted the same way as any other residential structure. Because the state building-permit exemption applies to 'private homes and apartments with four or fewer units,' a detached or internal ADU that brings the total unit count on the property to four or fewer generally does not require a state building permit for the structure itself — but its electrical, plumbing, and mechanical systems each require their own state permits regardless.

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• Water Heater Permit

  Installing or replacing a water heater in unincorporated Yellowstone County requires a state plumbing permit line item from the Montana Building Codes Bureau, unless the owner-occupant exemption applies (homeowner doing the work themselves on their own non-rental, non-speculative residence).

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• Electric Vehicle (EV) Charging Station / EVSE Permit (State Electrical Permit)

  Unincorporated Yellowstone County has no county-run electrical program and no dedicated EV charger/EVSE permit or fee line. All electrical work, including EV charging station/EVSE circuit installation, requires a State Electrical Permit from the Montana Building Codes Bureau (Title 50, Chapter 60, Section 604, MCA), the same statewide program used for the county's general electrical-permit entry, since Yellowstone County is not a certified local government for electrical code enforcement. The Bureau's Application for Residential/Homeowner Electrical Permit fee schedule (ARM 24.301.431) was checked directly and contains no distinct 'electric vehicle,' 'EV charger,' 'EVSE,' or 'charging station' line item; an EVSE circuit addition would be billed under an existing general-purpose fee category -- most likely 'Alternative Energy connection (residential change of service)' ($45) if tied to a service change, or the '1 additional circuit or piece of equipment' ($45) / '2-3 additional circuits or pieces of equipment' ($70) categories for a standalone dedicated circuit -- depending on project scope.

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• Sign Permit

  Unincorporated Yellowstone County has no separate county sign code or county-run permitting office. Sign permits for property in the county's zoning jurisdictional area (the area within roughly 4.5 miles of the Billings city limits, per the county zoning code) are administered by the same joint City/County Planning Division (Planning and Community Services Department) that handles Billings' own sign permits, via the shared Citizen Access / CityView online portal. The Division's own published guidance states plainly: 'Sign Permits are required in the City of Billings and in the zoning areas around the City limits.' Signs are reviewed against the Billings Municipal Code Sign Regulations (Chapter 27, Zoning, Article 27-1400, previously codified as Article 27-700) and, for electronic message display (EMD) signs specifically, against a distinct Yellowstone County EMD Sign Regulations document the Planning Division has published for county-side EMD signs.

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• Fire Sprinkler / Fire Alarm Permit

  Montana's Building Codes Bureau (DLI) does not certify a distinct 'Fire' trade for local governments -- its Certified City, County and Town Programs roster only ever lists Building (B), Plumbing (P), Electrical (E), Mechanical (M), Pool (SP), and Wildland-Urban Interface (W) columns, and Yellowstone County does not appear on that roster at all (confirmed directly against the Bureau's own PDF, updated 4/22/2026). Separately, the Montana Department of Justice (DOJ) Division of Criminal Investigation maintains its own, different 'Fire Inspection Certified Jurisdiction' roster for local fire-code enforcement -- and on that roster too, only 'Billings City Limits' appears; unincorporated Yellowstone County is absent. With no local building-trade certification AND no local fire-inspection certification, there is no distinct fire-sprinkler or fire-alarm permit product for unincorporated Yellowstone County. Fire suppression system work is instead submitted as part of the same State Building Permit (BCP-1) used for general construction, which lists 'Fire Suppression' as one of its explicit 'Type of Work' checkboxes (confirmed directly on the Bureau's Application for Building Permit, Rev. 11/25) alongside 'Change of Use,' 'Reroof,' etc. The area's Montana DOJ Deputy State Fire Marshals (Yellowstone County is split between 'Area 4' and 'Area 9,' both currently assigned to Billings-based deputies) are responsible statewide for inspection of public buildings and certification of local inspection programs, and may be looped into plan review by the Bureau for occupancies that warrant it, but do not publish a separate permit application or fee schedule of their own for unincorporated county fire-suppression work.

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• Change of Use / Zoning Compliance Permit

  Yellowstone County itself issues no building Certificates of Occupancy for structures outside Billings city limits (confirmed elsewhere in this dataset), so there is no county-issued 'Change of Occupancy' building certificate. The county's real change-of-use control operates on the zoning side: Section 27-1628 of the joint Billings/Yellowstone County zoning code requires a County Zoning Compliance Permit from the City/County Planning Division before any land use is established OR CHANGED, in whole or in part, anywhere in the county's zoning jurisdictional area -- regardless of whether new construction is involved. This permit is explicitly limited to a zoning-conformance review and does not substitute for building-code compliance; if a change of use also changes a building's occupancy classification under the International Building Code (egress, fire rating, etc.), a separate state Building Permit (BCP-1) marking 'Change of Use' as the Type of Work is additionally required from the Montana Building Codes Bureau, unless the structure/use qualifies for the state's residential building-permit exemption.

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