2021 International Mechanical Code
This reference establishes minimum regulations for mechanical systems using prescriptive and performance-related provisions. The IMC was developed with broad-based principles that make possible this use of new materials, methods and designs.
Important changes in this edition include:
- Clothes dryer exhaust terminals required to be at least 3 feet from any opening into a building.
- Polyurethane spray-applied foam on the exterior of ducts in attics and crawl spaces required to meet specific smoke and flame index limits.
- Fire and smoke dampers must be provided with approved access for inspection and maintenance.
- Refrigerant tables updated to include new refrigerants.
- Addition of condensate termination identification markings and discharge restrictions.
- Approved factory-built combination intake/exhaust terminations permitted, relaxing separation requirement.
- 30% reduction in minimum mechanical ventilation for whole-house balanced ventilation systems.
- Continuous operation requirement for manicure and pedicure station exhaust systems.
- Grease duct horizontal cleanout required within 3 feet of a horizontal discharge fan.