2024 Uniform Mechanical Code

2024 Uniform Mechanical Code (UMC)

The 2024 Uniform Mechanical Code (UMC®) provides the latest requirements and standards for the design, installation, maintenance, and inspection of mechanical systems. Developed through the ANSI Consensus Process and designated as an American National Standard by ANSI, the 2024 UMC incorporates contributions from professionals across the building and mechanical industries.

This comprehensive mechanical code covers heating, ventilation, cooling, and refrigeration systems, while providing flexibility for innovative technologies and modern mechanical applications.

Key Updates in the 2024 Uniform Mechanical Code

The 2024 UMC includes important updates and new requirements, including:

• New minimum air filtration requirements for occupied spaces in mechanically ventilated buildings
• Revised outdoor air intake requirements for transient occupancies
• New air balancing requirements for ventilation systems
• New exceptions for materials exposed to ducts or plenums
• New provisions for high-probability systems using Group A2L refrigerants for human comfort applications
• Updated refrigerant safety group classifications based on flammability and toxicity
• New requirements for refrigeration machinery rooms using A2L and B2L refrigerants
• Updated materials standards for refrigerant piping, tubing, and fittings
• New design requirements for geothermal district systems ambient temperature loops (ATL)
• Appendix H: Minimum qualifications for installers, inspectors, and employers for systems covered by the UMC
• Appendix I: Mechanical system requirements for indoor horticultural facilities
• Appendix J: CO₂ monitoring and clean air delivery requirements for ventilation in occupied spaces