Concerning zoning regulations in commercial, retail, and mixed-use areas in cities and code cities.

SB 5555 requires cities and code cities in Washington to allow housing units in existing ground-floor commercial, retail, or mixed-use buildings within specific transit-accessible areas (e.g., within 1/2 mile of light rail stops or 1/4 mile of bus rapid transit stops). It removes parking requirements, limits density restrictions (allowing up to 50% more units within existing building envelopes), and eliminates design standards for residential conversions in qualifying buildings. The bill also mandates that cities permit taller buildings using mass timber products in commercial zones and prohibits requirements like transportation studies for such conversions. These changes apply to buildings with a certificate of occupancy at least three years old, directly affecting property owners, developers, and local zoning regulations in participating jurisdictions.