The proposed bill aims to address the shortage of middle housing in Washington by establishing a performance-based building code compliance pathway specifically for middle housing buildings. This new framework is intended to reduce regulatory friction, enhance permitting predictability, and support off-site manufacturing and industrialized construction. The bill emphasizes the need for a system-level performance-based compliance pathway under the international building code, which would allow for the reuse of approved designs across jurisdictions and help lower housing delivery costs while ensuring health, safety, and welfare protections.

To implement this, the state building code council is tasked with adopting a mandatory appendix to the international building code that outlines the performance-based compliance pathway for middle housing buildings, defined as those with one to 24 dwelling units. The council will convene a technical advisory group to recommend performance-based code amendments and develop performance criteria for various building systems and materials. The bill also stipulates that the performance-based approach should align with existing energy efficiency and emissions programs, facilitating coordinated compliance and reducing duplicative processes. The council is required to adopt rules that recognize certifications from independent third-party organizations, ensuring that these certifications demonstrate compliance with the state building code for permit review and inspection purposes.