ADU Rules in Vancouver, Washington

Important: This page covers Vancouver, Washington — a city in Clark County in the southwestern corner of Washington State, USA. It is not Vancouver, British Columbia, Canada. These are two entirely separate cities in different countries on different sides of the US-Canada border.

Vancouver, WA (population ~195,000) is Clark County's largest city and the fourth-largest city in Washington State. Located on the north bank of the Columbia River directly across from Portland, Oregon, Vancouver is part of the Portland metropolitan area. The city is home to Fort Vancouver National Historic Site, one of the most significant historic sites in the Pacific Northwest, and serves as a bedroom community for Portland as well as a growing independent economic hub.

Washington State ADU Law: HB 1337 (2023)

Washington HB 1337 (2023) is the critical statewide ADU law that applies to Vancouver, WA and all Washington cities. Key provisions:

• Cities must allow up to 2 ADUs per lot — one attached/internal + one detached — by right on any lot with a single-family home
• No owner-occupancy requirement permitted
• No ADU-specific impact fees allowed
• Cities may not require ADUs to be smaller than 1,000 square feet
• State law limits how restrictive local setback, lot coverage, and height requirements for ADUs can be

Washington HB 1110 (2023) accompanies HB 1337, requiring cities to allow duplexes and middle housing in residential zones — further expanding housing options in Vancouver, WA.

Vancouver is subject to the Washington Growth Management Act (GMA), which requires comprehensive planning with an Urban Growth Area (UGA) and zoning consistent with long-term growth targets. Clark County coordinates with Vancouver on UGA boundary planning.

Vancouver, WA Local ADU Code

Vancouver's Community Development Department administers local zoning and building permits. Local ADU standards must comply with HB 1337 and may not be more restrictive than state law allows.

Permitted ADU Types

• Detached ADU: A separate structure in the rear or side yard, independent from the primary home
• Attached ADU: An addition to the primary dwelling sharing at least one wall
• Internal/Converted ADU: Conversion of existing garage, basement, or accessory space

Lots may have up to 2 ADUs simultaneously — one attached/internal + one detached.

Size Limits

State law prohibits Vancouver from requiring ADUs to be smaller than 1,000 square feet. Consult Vancouver's Community Development Department for the current maximum size standards in your zone.

Setbacks

HB 1337 limits Vancouver's ability to impose setbacks that would prevent reasonable ADU siting. Setbacks vary by zoning district. Verify current requirements with the city's Permit Center before designing an ADU.

No Owner-Occupancy Requirement

State law prohibits owner-occupancy mandates. Vancouver, WA may not require property owners to live on-site to rent an ADU.

Oregon Comparison Note

Residents familiar with Portland, Oregon's ADU rules should note that Vancouver, WA operates under Washington state law — not Oregon law. Washington HB 1337 provides robust ADU rights, generally comparable to Oregon's ADU reforms, but with Washington-specific requirements and processes.

Critical Areas Ordinance (CAO)

Vancouver, WA maintains a Critical Areas Ordinance protecting wetlands (Vancouver Lake lowlands have significant wetland systems), fish and wildlife habitat (Columbia River system), frequently flooded areas (Columbia River and tributary floodplains), steep slopes, and critical aquifer recharge areas. FEMA flood maps are particularly relevant for properties near the Columbia River, Vancouver Lake, and Burnt Bridge Creek. CAO buffers can substantially affect where an ADU may be placed on a lot.

Seismic Hazard

Vancouver, WA and the greater Portland-Vancouver metro area face seismic risk from the Cascadia Subduction Zone (CSZ), capable of producing a magnitude 9.0+ earthquake. The Columbia River basin has areas of soft alluvial soils and fill susceptible to liquefaction. ADU foundations should be designed to meet Washington State Building Code seismic provisions. Geotechnical investigation is recommended for properties on soft or fill soils.

Permit Process

1. Check your property's zoning and CAO constraints using Vancouver's online GIS portal
2. Schedule a pre-application meeting with Vancouver's Community Development Department if needed
3. Prepare construction plans meeting Washington State Building Code requirements
4. Submit permit application at Vancouver's Permit Center (P.O. Box 1995, Vancouver, WA 98668)
5. Plan review and permit issuance (ministerial for HB 1337-compliant ADUs)
6. Construction inspections
7. Final inspection and Certificate of Occupancy

Contact Vancouver, WA Community Development: (360) 487-7800 | vancouver.wa.gov/permit-center

Disclaimer: This guide covers Vancouver, Washington (Clark County, USA) and provides general information based on Washington HB 1337 (2023) as of April 2026. Zoning regulations change frequently. Always verify current requirements with the City of Vancouver, WA Community Development Department before making development decisions. This is not legal advice.