Model codes such as those published by the International Code Council (ICC) are not automatically law. They become legally enforceable only when a governmental authority, typically at the state, county, or municipal level, formally adopts them through legislative or administrative action. This authority may adopt the entire model code, selected sections of it, or a modified version that includes local amendments. For example, a city might adopt the 2021 International Residential Code (IRC) but change specific requirements, such as insulation values or ventilation methods, to better suit local climate conditions or construction practices.
For building professionals, this means it is essential to verify which version of a code is currently in effect within the jurisdiction where the work is being performed. One must also be aware of any local amendments that could alter or override provisions in the model code. While provisions not formally adopted by the local authority are not enforceable for compliance purposes, they may still be referenced as best practices or guidance in consulting and diagnostic evaluations.