Montana Current Building Codes

Montana’s building codes are designed to ensure the safety and structural integrity of buildings within the state. These codes encompass various aspects of construction, including electrical, plumbing, and fire safety, to protect both residents and the environment. Compliance with these regulations is essential for anyone involved in construction or renovation projects in Montana.

Montana building codes

Current Commercial Code of Montana

2012 IECC with Montana amendments or ASHRAE 90.1-2010
Passed 9/20/2013, effective 11/7/2014

Current Residential Code of Montana

2012 IECC with Montana amendments
Passed 9/20/2013, effective 11/7/2014

Due to state amendments, the residential code is not quite equivalent to the 2012. Still, major improvement to the new energy code include:

    • More efficient windows (U-0.32);

More efficient crawlspace walls;

  • Mandatory whole-house blower-door test requirement, beginning 2016;
  • More stringent heating duct leakage testing;
  • Whole-house mechanical ventilation;
  • More efficient lighting (75 percent high efficiency fixtures and lights)


See Administrative Rules of Montana (Title 24, Chapter 301.161) for Incorporation by Reference of the IECC.

Climate Zone: 6B

Code Adoption and Change Process

Code Change Process

Regulatory: The energy codes are reviewed on a three-year cycle corresponding to the adoption of new versions of the International Code Conference (ICC) Uniform Codes. Proposed changes are submitted to the Building Codes Bureau, which must file its proposed rules with the Secretary of State within six months of adoption.

Code Change Cycle

Three-year code review/change cycle.

Next Code Update



November 7, 2014 The Administrative Rules of Montana (Title 24, Chapter 301.161) now require that commercial buildings and (R-2 and R-4) residential buildings over three stories comply with the 2012 IECC or ASHRAE 90.1-2010. The commercial code is equivalent to the 2012 IECC.

All residential buildings must meet the minimum requirements of the 2012 IECC with Montana amendments. Due to the state amendments, the residential code is not quite equivalent to the 2012 IECC.

June 1, 2013 High Performance Building Standards, promulgated to implement parts of the 2009 legislature’s SB 49, are adopted. These standards apply to “the construction, renovation, and maintenance of public buildings…as well as all new state-leased buildings”. Read more about these standards here.
January 12, 2011 A bill (Senate Bill 159) is introduced in the Montana Legislature that would affect future updates to the state energy code (currently based on the 2009 IECC). The bill would require the Department of Labor and Industry (DLI) to demonstrate a five-year payback period for the added incremental costs (relative to the 2009 IECC) of constructing a home to proposed code updates in the future. The bill passes the state Senate on February 1st and state House on April 1st. On April 13th, this bill is vetoed by the governor.
Spring 2010 Montana adopts the 2009 IECC with state amendments. Following a public hearing in November 2009, the Montana Department of Labor and Industry (DLI) files the final adoption notice to amend ARM 24.301.161. The state’s 46 local certified jurisdictions will have an additional 90 days to adopt the same code and edition for their jurisdictions. All other areas are under the jurisdiction of the State Building Codes Bureau. Training classes are to be held during the 5th Annual Building Codes Education Conference; the Montana Building Codes Bureau also plans for additional training and will be coordinating with the Montana Department of Environmental Quality (DEQ) for additional training ideas and methods.
June 25, 2009 The Montana Building Code Council votes to adopt the 2009 IECC with amendments. The Montana Department of Labor and Industry will accept comments on the new code when the department holds the public hearing as part of the administrative Rules process, which should take effect in fall. The existing Montana amendment allowing residential basement insulation delay until the space was finished for occupancy is removed.
April 2009 The state legislature enacts Senate Bill 49, directing state agencies to adopt high performance building standards guiding the construction of new buildings or renovations made to older existing buildings.

Article: Montana agency closer to adopting energy-saving building standards

January 26, 2007 The 2006 I-codes, with the exception of the energy code, become effective.
September 3, 2004 The state adopted the 2003 IECC with minimal changes as the statewide energy code.
1999 The Montana legislature enacts HB 641, which relates to the construction of, the installation of equipment in, and standards for materials to be used in all buildings or classes of buildings, including provisions dealing with safety, accessibility to persons with disabilities, sanitation, and conservation of energy. The adoption, amendment, or repeal of a rule is of significant public interest for purposes of 2-3-103.
1985 The state’s first energy code is the 1983 Model Energy Code (MEC). Montana adopts the appendix of Chapter 53 (Energy) referenced in the 1985 Uniform Building Code, which referenced the 1983 MEC.

Montana adopts several of the MEC editions and supplements in the late 1980s and early 1990s, including the 1991 MEC with reference the first Standard 90.1 edition, ASHRAE 90.1-1989.

1972 Montana first adopts a statewide building code with the adoption of the ICBO Uniform Codes.

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Paul Tschida
Public Education Specialist
Energy Efficiency and Compliance
Department of Environmental Quality

David Cook
Bureau Chief, Business Standards Division
Department of Labor and Industry

Ken Baker
Senior Manager, Codes
Northwest Energy Efficiency Alliance

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