The provisions of the code are mandatory for which type of buildings?

The provisions of the International Mechanical Code (IMC) are generally designed to apply to new constructions, ensuring that all aspects of mechanical systems meet current safety and efficiency standards. In many jurisdictions, existing buildings may be held to different, often less stringent, requirements as they are already established and may not have to comply with the latest code. This exceptional treatment means that updates and renovations in existing structures might not necessitate full compliance with the new codes unless they are making significant modifications.

In the context of the question, the correct answer highlights that the code's provisions are mandatory primarily for new constructions and other specific categories mandated by local regulations, rather than existing structures which may have grandfathered standards. Historic buildings, while often subject to preservation controls, may not adhere fully to all sections of the IMC due to their unique requirements, and temporary structures typically have different guidelines that don't fall under the comprehensive purview of IMC standards.