WA HB2346

State Building Code Council must adopt a mandatory appendix to the International Building Code establishing a performance-based compliance pathway for middle housing buildings of 1-6 stories with 1-24 dwelling units

Technical advisory group to be convened including Department of Labor and Industries, Department of Commerce, University of Washington, and Washington State University to recommend performance criteria for building systems, components, and materials

Third-party certifications from nationally recognized evaluation organizations may be accepted as demonstrating code compliance, and local jurisdictions must accept these certifications for permit review and inspection

Performance-based pathway must integrate compliance across building codes, energy codes, and greenhouse gas emission rules (including embodied carbon) as an alternative to separate prescriptive compliance pathways

Implementation required in the first substantive state building code update occurring after January 1, 2027