Zoning › State preemptions › Washington

Washington HB 1110 — Middle Housing (Tier 1: cities >=75,000) (WA)

Tracked preemption from the Washington overlay bundle.

Overview

← All state preemptionsWashington overlay roll-upWashington zoning wikiWashington building codesFederal overlaysGlossaryFederal-conflict: Yes
Effective
2024-07-01
Sunset
—
Authority
state
Scope
state:WA
Other Washington preemptions
Washington HB 1110 — Middle Housing (Tier 2: cities 25,000-75,000)Washington HB 1110 — Middle Housing (Tier 3: small cities in Tier 1 UGA)Washington SB 5184 — Lot Splitting for Housing CapacityWashington SB 5290 — Local Permit Review TimelinesWashington HB 1337 — Accessory Dwelling Units StatewideWashington E2SHB 1220 — Comprehensive Plan Housing ObligationsWashington Growth Management Act — Zoning for Growth Targets
Primary-source summary
HB 1110 — Middle Housing (effective July 1, 2024)

Trigger predicate

When this evaluates true for a parcel, the law's preempted fields take precedence over base zoning.

AND
  • city.population ≥ 75000
  • parcel.base_zone_category == res_sf

Preempted fields

6 fields on the base district schema are rewritten when the trigger fires.

FieldOpValueNote
base_districts[category=res_sf].max_units_per_lotfloor_at4Baseline floor: 4 units per lot by-right in all SF residential zones
base_districts[category=res_sf].max_units_per_lotfloor_at66 units allowed within 1/2 mile of major transit stop if >=2 units affordable
base_districts[category=res_sf].min_lot_size_sfcap_atbase SF lot minimumCities cannot require lots larger than needed for a single-family home
base_districts[category=res_sf].parking_ratiocap_at1.0Cities may require up to 1 space per unit
base_districts[category=res_sf].parking_ratiowaive—No parking may be required within 1/2 mile of major transit stop
review_typewaive_discretionary—Middle housing must be permitted by-right; only objective design standards allowed

Citation

Authority source
WA HB 1110 (2023) / RCW 36.70A.635
§ RCW 36.70A.635
https://app.leg.wa.gov/billsummary?BillNumber=1110&Year=2023

Research notes

Tier 1 applies to cities with population >=75,000. JBLM (Pierce County) and NAS Whidbey (Island County) AICUZ zones may constrain application on parcels within military accident potential or noise contour areas — federal_conflict_check flags target intersections with federal AICUZ overlays.