Establishes the "Missouri Building Codes Act"

HB 3466 establishes Missouri's standardized "Missouri Building Codes Act," requiring local governments (counties, municipalities, fire districts) to adopt model building codes from national organizations like the International Code Council (ICC) and National Fire Protection Association (NFPA) by August 2028. The bill mandates compliance for all new construction and building inspections, while creating a Missouri Building Codes Commission to oversee implementation and review local amendment requests based on safety, health, and affordability. Local authorities may propose limited amendments but must obtain commission approval, and all adopted codes must be publicly filed and posted online. This replaces inconsistent local codes with a unified system, directly affecting builders, inspectors, and local governments managing construction standards.