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State Profile

Code Type: Commercial Residential
Current State Code 2021 IECC and ASHRAE 90.1-2019 2021 IECC with Amendments
Effective Date
Adoption Date
State Amendments No Yes
State Code Analysis*
Enforcement Mandatory Statewide Mandatory Statewide
Can use COM/REScheck Yes Yes


Model Code Savings Potential

Statewide Savings Potential (2010-2030) Residential Commercial
Cost $0.15B $0.05B
Energy (primary) 16MBtu 6MBtu

Consumer Cost Savings

Consumer Cost Savings Residential
per Home
per 1,000 ft2
Annual ($) $119 $151
Annual (%) 8.5%
Life-cycle (30 year) $948 $1480
Simple Payback 11.0 years 5.0 years
Positive Cash Flow 2.7 years


Code Type: Residential Commercial
Field Study Yes No
Training Program No No

Additional Information



    Montana first adopted a statewide building code in 1972 with the adoption of the ICBO Uniform Codes. Montana adopted the appendix of Chapter 53 (Energy) referenced in the 1985 Uniform Building Code, which referenced the 1983 MEC.

    The state adopted the 2003 IECC with minimal changes as the statewide energy code on September 3, 2004. The state building code energy provisions contained mandatory minimum requirements for all newly constructed buildings and additions that are heated and/or mechanically cooled. The provisions also applied to state-owned and operated buildings and all alterations and repairs to existing buildings.

    Basement wall insulation below uninsulated floors, except for rim joists and perimeter cripple walls, was delayed until such time as the basement is actually finished for occupancy.

    After beginning the process to adopt the 2006 IECC, an introductory meeting was held on November 6, 2008 by the Montana Building Codes Bureau to ask members of the building codes community about restarting the process to adopt the 2009 IECC. The meeting outcome was to begin moving forward with the 2009 IECC with further discussion about adopting even more efficient codes.

    HB420 passed in April 2009 which allows local cities and counties to adopt energy conservation standards stricter than the state code.

    In June 2009, the Montana Building Codes Council voted to adopt a new statewide Montana energy code: the 2009 International Energy Conservation Code (2009 IECC) with amendments. In spring 2010, Montana adopted the 2009 IECC with state amendments. Following a public hearing in November 2009, the Montana Department of Labor and Industry (DLI) filed the final adoption notice to amend ARM 24.301.161 with the Secretary of State on March 15 with an effective date of March 26, 2010.

    The State of Montana, Department of Labor and Industry filed the final adoption notice for the 2009 International Energy Conservation Code with the Secretary of State on March 15th with an effective date of the adoption to be March 26, 2010. Local certified jurisdictions will have an additional 90 days to adopt the same code and edition for their jurisdictions.

    State-Owned/Funded Buildings

    S.B. 49, created energy efficiency standards for state-owned and state-leased buildings. Energy efficiency building standards apply to new construction and major renovation projects for state-owned buildings and new construction projects for state-leased buildings. The buildings must exceed the effective International Energy Conservation Code by 20%, to the extent that it is cost effective.

    Adoption Process

    Local government code enforcement jurisdictions have 90 days to adopt the state building code once they receive notification from the state of change to the code. If an approved local government code enforcement program does not exist, the State Building Codes Bureau enforces the applicable codes on commercial buildings and residential buildings with five or more dwellings. Three counties and 38 incorporated cities have adopted the state energy code. 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.

    Enforcement Process

    When required by the building official, plans and specifications must be submitted. The building official may also require that plans and specifications be prepared by a licensed architect or engineer. A registered architect or engineer may prepare all energy compliance submissions or COMcheck and REScheck will also be acceptable means of showing compliance.

    Compliance Process

    The builder must provide a labeling sticker. The label must be permanent and placed on the interior electrical panel. The R-values and U-values provided for building envelope components and mechanical equipment efficiency must be shown on the label.

    On May 6, 2010, Montana was announced as one of the states that will participate in BECP's Compliance Evaluation Pilot Study.