Concerning performance-based building codes for middle housing.

HB 2346 establishes a state-approved performance-based building code pathway for "middle housing" in Washington, defined as residential buildings with 1 to 24 units (e.g., duplexes, townhomes). Instead of requiring specific construction methods, the bill directs the State Building Code Council to create measurable performance standards for safety, durability, and energy efficiency, allowing builders to demonstrate compliance through engineering analysis or third-party certification. This aims to reduce permitting delays, lower housing costs, and support industrialized construction by enabling reusable designs across jurisdictions. The bill directly affects developers, manufacturers, local governments, and housing providers by streamlining approvals for middle housing projects.