Washington Building Codes

Washington State Building Code Council (SBCC) administers statewide mandatory codes based on 2021 I-Codes with WA amendments. WSRC (residential), WSBC (commercial), WSEC (energy). WAC 51-50/51-51. Energy code MORE stringent than IECC - mandatory blower door testing (4 ACH50 Zones 4C/5B, 3 ACH50 Zone 6B). Heat pump requirements increasing. Uses UMC/UPC (not IMC/IPC). L&I administers statewide electrical (NEC 2023). Climate Zones: 4C (marine - Puget Sound/west), 5B (dry - eastern lowlands), 6B (dry - mountains). Cascadia Subduction Zone - SDC D throughout west (M9.0+ risk). Tsunami inundation zones on Pacific coast. Mt. Rainier/St. Helens lahar zones. Significant WUI/wildfire risk eastern WA. Snow loads 25-300+ psf (extreme variation). Ice barrier required statewide. Shoreline Management Act within 200 ft of water. GMA Critical Areas (wetlands, geologic hazard, fish & wildlife). Seattle has local amendments exceeding state. No statewide GC license (L&I licenses electricians). 39 counties.