What code has the greatest legal authority over construction projects?

Local codes have the greatest legal authority over construction projects because they are enacted by local jurisdictions, such as cities or counties, to govern building practices within their specific areas. Local codes are tailored to meet the unique needs and conditions of the community, addressing factors like climate, local building materials, and population density. They are enforceable and must be adhered to by all construction projects within that jurisdiction.

While federal codes and state codes also play important roles in setting regulations and standards—particularly for specific situations like environmental protection or workplace safety—they often serve as frameworks that local codes build upon or reference. Industry standards, on the other hand, provide guidelines and best practices but do not carry legal authority; they are generally voluntary and used as a benchmark for quality and safety improvements rather than being mandatory requirements.