WA HB1757

Cities must adopt regulations by June 30, 2026 allowing residential conversions in commercial, mixed-use, and residential zones; state requirements automatically supersede conflicting local rules if cities miss this deadline.

Existing buildings in multifamily zones can add housing units at up to 50% higher density than normally allowed, provided health and safety standards are met.

Cities cannot impose new parking requirements for added dwelling units, though they may require retention of existing parking for current residential and remaining nonresidential uses.

Building permit applications cannot be denied due to nonconformity on parking, height, setbacks, elevator size, or modulation unless officials make written findings of significant detriment to surrounding area.

Energy code compliance exemptions apply when new dwelling units total under 2,500 square feet (or 50% of building), when projected energy use meets clean buildings standards, or when adding units within existing homes in residential zones.