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2024 International Mechanical Code

Product Code/ISBN: 9781959851776

The 2024 International Codes have undergone substantial formatting changes as part of the digital transformation strategy of the International Code Council to improve the user experience. The changes, promoting a cleaner, more modern look and enhancing readability and sustainability, include:

  • Single column text format and modernized font styles improves readability
  • QR Codes replace vertical margin sidebars and arrows to identify code changes more accurately
  • Shading for table headers and notes improves locating tables and applicable notes
  • Grouping of associated content brings tables and figures immediately after the parent section
  • Users have capability to validate authenticity of their book and register it with the ICC to receive incentives.


The International Mechanical Code  establishes minimum regulations for mechanical systems using prescriptive and performance-related provisions. The IMC® was developed with broad-based principles that make possible the use of new and innovative materials, methods and design. 

Important changes in the 2024 IMC include:

  • Provisions prohibiting the use of domestic ductless range hoods in Groups I-1 and I-2 were removed.
  • An identification requirement was added for Group A2L and B2L refrigerants.
  • The requirements for machinery rooms containing Group A2L refrigerants were changed and Group B2L refrigerants were added to the provisions.
  • Limits for the use of Group A1 and A2L refrigerants changed in high probability systems used for human comfort, unless permitted as excepted.
  • UL 2158A Standard was added to the requirements for commercial dryer exhaust.
  • Ventilation requirements for outpatient healthcare facilities to match the requirements in ASHRAE 62.1-2019.
  • Addition of a new minimum landing at the roof hatch for personnel to safely use the hatch when accessing the roof for repair and maintenance.
  • Addition of a new testing option for grease ductwork.
  • Requirements for steam baths were added.
  • A new standard requirement for refrigeration systems containing carbon dioxide was added.