2027 International Mechanical Code®

Mechanical systems installations and continuing throughout the life of a building. Sets minimum requirements for permanently installed mechanical systems and equipment to support safe, healthy, reliable building environmental control and related processes.

The International Mechanical Code (IMC®) 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. For the most current adoptions details go to International Code Adoptions.

Important changes in the 2027 IMC include:

• Reference to ASHRAE 15 is added to the code, indicating that compliance with Table 1103.1, in addition to the effective dispersal volume charge (EDVC) limitations of ASHRAE 15, is required to eliminate refrigerant machinery rooms.
• Additional terminology and requirements for group controllers are added to address buildings with large voluminous spaces and heavy refrigeration loads, where a leak in one cooling unit can create hazardous conditions elsewhere in the building.
• The use of ASHRAE 62.1 Section 6.3 is allowed for determining the minimum outdoor airflow rate in occupancies other than Group R-2, R-3, and R-4 occupancies.
• The use of exhaust-only ventilation systems in corridors is prohibited when providing required outdoor air to dwelling units opening into corridors.
• Provisions regarding Type I hoods are clarified, providing two clear paths for code compliance: one prescriptive and a second, hybrid method that utilizes some prescriptive requirements in addition to being listed and labeled in accordance with UL 710.