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 2021 IMC 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...