Montana Building Code: Which Editions Are Adopted

Direct answer

2024 I-Codes as the Montana State Building Code, effective 26 September 2026 in Montana. 2024 IBC, IRC, IEBC, IECC, IMC, IFGC, ISPSC and IWUIC, the 2024 Uniform Plumbing Code and the 2023 NEC, adopted by reference with Montana amendments under ARM Title 24, Chapter 301. The 2024 codes replaced the 2021 editions, which had been in force since 11 June 2022. The Department of Labor and Industry adopted them through MAR Notice No. 2026-95.2, published on 25 September 2026 after a public hearing on 28 August 2026. Record the permit application date with it: a code change normally applies from an effective date, and an application filed before that date is usually reviewed under the previous edition. This was checked on 2026-10-01 against Montana Department of Labor and Industry, Building and Commercial Measurements Bureau, which is the source that controls. The cross-state comparison further down this page comes from the ICC adoption chart dated January 2024, so where the two disagree the record above is the newer one.

Content and cited inputs reviewed by Harth team · Published 2026-09-07 · Updated 2026-10-01.

Which codes has Montana adopted now?

2024 I-Codes as the Montana State Building Code, effective 26 September 2026.

2024 IBC, IRC, IEBC, IECC, IMC, IFGC, ISPSC and IWUIC, the 2024 Uniform Plumbing Code and the 2023 NEC, adopted by reference with Montana amendments under ARM Title 24, Chapter 301.

Transition: The 2024 codes replaced the 2021 editions, which had been in force since 11 June 2022. The Department of Labor and Industry adopted them through MAR Notice No. 2026-95.2, published on 25 September 2026 after a public hearing on 28 August 2026.

Local adoption: The state building code is enforced statewide for residential and commercial buildings, by the Department of Labor and Industry or by certified city, county and town building code programs. The fire code is adopted separately by the Fire Prevention and Investigation Section and remains on the 2021 IFC.

Checked 2026-10-01 against Montana Department of Labor and Industry, Building and Commercial Measurements Bureau. Confirm the edition and effective date for the specific permit jurisdiction before relying on it.

The cross-state record

For comparison across states, every I-Code the ICC Master I-Code Adoption Chart (January 2024) tracks, as it records Montana. Where this disagrees with the record above, the record above is newer:

Montana has a recorded edition year for 11 of the 17 codes: 2021 for the building, residential, fire, mechanical, fuel gas, green construction, residential energy, commercial energy, existing buildings, swimming pool and spa and wildland-urban interface codes. No adoption at all is recorded for the plumbing, private sewage, property maintenance, performance, zoning and green building standard codes.

Source: ICC Master I-Code Adoption Chart (January 2024).

How Montana compares with its neighbours

Statewide editions in force, checked 2026-10-01; “Local” means no state adoption, “(limited)” a state adoption for some buildings only, and * a state-titled code built on that edition.

Idaho, Wyoming and North Dakota differ from Montana on the building code alone. A practice working across that border is working to two editions, whatever the office standard says.

Where Montana sits in the national record

Of the 50 states and the District of Columbia, 10 enforce the 2024 IBC statewide, 0 a later edition, 24 an earlier one, and 17 have no statewide IBC edition in force. Montana is at or ahead of the national middle on the building code, so the risk runs the other way: work arriving from a slower-moving state may be drawn to an older edition.

Across all 17 codes the January 2024 ICC chart tracks, Montana has a recorded edition for 11, which ranked it 3rd of 51. A low count is not a gap in regulation — it usually means the state legislates through its own documents, or leaves the discipline to local adoption.

What the chart does and does not tell you

The chart's own legend matters more than the numbers:

• An edition year means one or more state or local agencies adopted that edition. It does not mean every building in the state is designed to it.
• “Some jurisdictions only” is the chart's X: the code is in use somewhere in the state but is not the standard for all buildings.
• “Not adopted” is a blank cell — no state or local jurisdiction reported adopting that code.
• “State-written code” means the state publishes its own document in place of the model edition, so the model text is a reference, not the law.

ICC states plainly that not every jurisdiction notifies it of an adoption, and this chart is dated January 2024. Treat it as the starting point for a search, never as the answer.

How to confirm the edition that governs a Montana project

1. Open Montana Department of Labor and Industry, Building and Commercial Measurements Bureau and find the currently adopted code list with its effective date.
2. Check whether the permit authority for the project address is the state or a local programme with its own adoption.
3. Read the state amendments alongside the model edition — an amended table or definition changes the requirement even when the edition matches.
4. Record the permit application date. A code change usually applies from an effective date, and applications filed before it are normally reviewed under the previous edition.
5. Get the answer in writing from the authority having jurisdiction before it drives a design decision.

This site also hosts a transcription of the 2009 model code chapters as adopted in Montana at /building-codes/us-states/montana. That is a historical reference for the 2009 editions and is not Montana's current code basis.

Montana code-basis worksheet

Fill this in once per project and keep it with the drawing set. Every row is a question a plan reviewer can ask, and the answer changes with the address and the application date, not with the state.

This worksheet records a determination; it does not make one. The authority having jurisdiction decides which edition and which amendments apply.

Where can you explore related guidance?

• Explore all code adoption guidance
• Idaho Building Code: Which Editions Are Adopted
• Wyoming Building Code: Which Editions Are Adopted
• North Dakota Building Code: Which Editions Are Adopted
• South Dakota Building Code: Which Editions Are Adopted

Sources and method

Adopted editions transcribed from the ICC Master I-Code Adoption Chart (January 2024), reproduced with the chart's own legend so an “X” is not mistaken for a statewide adoption. ICC notes that not all jurisdictions report their adoptions and publishes updates at iccsafe.org/adoptions. The current edition, its effective date and the state amendments are published by Montana Department of Labor and Industry, Building and Commercial Measurements Bureau, which controls.

Source links

• iccsafe.org

• iccsafe.org

• bsd.dli.mt.gov