Michigan Part 9A. Mechanical Code rules

February 22, 2024

The Part 9A. Mechanical Code rules were filed with the Secretary of State November 13, 2023, and become effective on March 12, 2024. The Part 9A Mechanical Code rules will adopt by reference the 2021 third printing edition of the International Mechanical Code with amendments, deletions, and additions deemed appropriate for use in Michigan.

Until the electronic and hard copies are available from the International Code Council (ICC), one can use the 2021 International Mechanical Code with the Part 9A Michigan Amendments for the 2021 Michigan Mechanical Code. The bureau will notify the public when the electronic and hard copy versions of each code are available for purchase and update the code books information on our website, which links to ICC for purchase. Below is an important change that has been made to the code.

  • R 408.30947b provides for the implementation of ASHRAE 15-2022 within the 2021 Michigan Mechanical Code. ASHRAE 15-2022 defines a clear path for and establishes safety standards associated with the utilization of A2L refrigerants, resulting from an Environmental Protection Agency (EPA) rule issued in late 2021. This EPA rule issued under the American Innovation and Manufacturing Act of 2020 (AIM), mandates an 85% reduction in the production and consumption of hydrofluorocarbon refrigerants by 2036. Although this drawdown is 12 years away, manufacturers have begun significant production and distribution of equipment utilizing A2L refrigerants. This rule supersedes the ASHRAE 15-2019 standard listed in the Referenced Standards section of the 2021 Michigan Mechanical Code.

Please contact the Mechanical Unit at bccmech@michigan.gov for questions concerning the 2021 Michigan Mechanical Code.


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