Montana Building Permit Guides

Montana has one building code, adopted by the Department of Labor and Industry by rule. From 26 September 2026 it is based on the 2024 International Building, Residential, Existing Building, Mechanical and Fuel Gas Codes, the 2024 Uniform Plumbing Code and the 2023 National Electrical Code, all amended by the Administrative Rules of Montana, Title 24, chapter 301.

Enforcement is split. The department’s Building Codes Program is the authority by default; a city or county whose program the state has certified issues permits and inspects within its own area instead (MCA §50-60-106). A local government may not adopt or enforce a building code more stringent than the state’s, apart from voluntary, incentive-based energy conservation standards (MCA §50-60-301).

The state building code does not apply to residential buildings of fewer than five dwelling units (unless they serve transient guests), to farm or ranch buildings of any size, or to private garages and storage buildings for the owner’s own use, unless the local government has made the code apply to them (MCA §50-60-102). So a house may need a building permit inside a certified city and none on a rural parcel outside one. An exemption from the building permit is never an exemption from zoning, floodplain or septic rules, or from an electrical or plumbing permit.

Where the state issues the permit, the building permit must be issued before any plumbing, mechanical or electrical permit, and plan review averages about three weeks. The permit fee follows a valuation table, with plan review charged at 35 percent of the permit fee (ARM 24.301.138).

Outside certified jurisdictions, design snow loads are taken from the ASCE 7 standard through the ASCE 7 Hazard Tool, with a minimum roof snow load of 30 psf after reductions unless a Montana-licensed design professional justifies less. The department generally requires a Montana-licensed design professional for publicly owned buildings, buildings outside the conventional light-frame provisions, and buildings subject to moderate-to-severe snow or seismic loads.

Since 1 January 2026 anyone in business as a construction contractor needs a construction contractor licence from the Department of Labor and Industry (MCA §37-45-201); contractors with an active registration on 31 December 2025 were converted to it. The department’s FAQ lists an online application and a $70 fee, and no exam. The exemptions in MCA §37-45-104 include casual or minor work under $2,500 a job, an owner working on their own property (but not one building to sell, unless they have lived there as their primary residence for the last 12 months), an owner who hires licensed contractors, and an independent contractor with no employees. That independent contractor must still hold an Independent Contractor Exemption Certificate if they work away from their own business premises, unless they carry workers’ compensation (MCA §39-71-417).

Electricians and plumbers are licensed by state boards. An individual may do electrical work on their own property or residence kept for their own use, except on a grid-tied generator (MCA §37-68-103), and the owner of a single-family home used only for their own personal use may do its plumbing (MCA §37-69-102). The department issues homeowner electrical permits, and says homeowners doing their own plumbing on a home that is not built to sell or rent need no state plumbing permit.

In areas the state covers, an electrical permit is required for any installation in new construction, remodelling or repair (ARM 24.301.431). The exceptions in MCA §50-60-602 are narrow: utility signal and traffic equipment, refineries and mines, low-voltage signal, communications and fibre-optic wiring, and maintenance by electricians employed on their employer’s premises; plugging an appliance into an existing outlet is not an installation.