ICC IMC-2021使用规定性和性能相关规定制定了机械系统的最低规范。IMC的开发采用了广泛的原则，使新材料、新方法和新设计的使用成为可能。该版本的重要变化包括:干衣机排气终端要求距离建筑物的任何开口至少3英尺。在阁楼和爬行空间的管道外部喷涂聚氨酯泡沫，以满足特定的烟雾和火焰指数限制。防火阀和防烟阀必须提供经批准的检查和维护通道。制冷剂表更新，包括新制冷剂。增加冷凝水终端识别标记和排放限制。允许使用经批准的工厂制造的进气/排气组合终端，放宽分离要求。整体最低机械通风量减少30%- 室内平衡通风系统。美甲和足疗站排气系统的连续运行要求。水平排风机3英尺范围内需要进行润滑脂管道水平清洗。

ICC IMC-2021 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 materials, methods and design.Important changes in the 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.