Everything homeowners need to know about building an accessory dwelling unit in Vancouver, Washington - size limits, setbacks, permits, and the 2024 rule changes that brought the city in line with Washington's statewide ADU law.
Last verified: August 2026
8/10 · Very ADU-friendly
1,000 sq ft
Max ADU size
Per zone*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Vancouver Municipal Code Chapter 20.810 (Accessory Dwelling Units) for general reference - it is not legal advice. Regulations change; always confirm current requirements with the City of Vancouver's Community Development Department before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage/outbuilding conversion)
1,000 sq ft of gross floor area
Same as the primary dwelling's zone, not the shorter limit for accessory structures
A garage or outbuilding conversion must meet the primary structure's setback standards, not the looser accessory-structure standard
Common approach for basement or above-garage conversions
Allowed zoning districts
Up to two ADUs are allowed on any legal lot with a single-family residence, citywide. Vancouver doesn't set one flat citywide height cap for ADUs - instead, setback and height standards match whatever applies to the primary dwelling in that particular zone. Confirm your parcel's exact zone and standards with Community Development before you design.
Additional standards
Setbacks, parking & other rules
Setbacks
Same as the primary structure for the underlying zone, not the reduced setback allowed for ordinary accessory structures
Parking
No additional on-site parking required for the ADU itself
Units per lot
Up to 2 ADUs permitted in addition to the primary dwelling, in any combination of attached and detached
Owner-occupancy
Not required. Vancouver eliminated its owner-occupancy requirement under Ordinance M-4378 in September 2024
Building code
Must meet Washington State Residential Code dwelling-unit standards, plus applicable plumbing, electrical, mechanical, fire, and health codes
Rental registration
Long-term rentals, including ADUs, must register annually under Vancouver's new Rental Registration Program (VMC Chapter 5.08), which launched January 1, 2026; short-term rentals under 30 days need a separate STR permit
Ordinance history
How Vancouver's ADU rules got here
2023Washington passes HB 1337. The statewide law required cities to allow at least two ADUs per lot in urban growth areas, guarantee at least 1,000 sq ft of ADU floor area, cap ADU impact fees at 50% of what's charged to the primary unit, and bar parking mandates near transit. It's since been codified as RCW 36.70A.680 and .681.
2024Local code brought into compliance. Vancouver adopted Ordinance M-4378 in September 2024, rewriting Municipal Code Chapter 20.810: the size cap rose from 800 to 1,000 sq ft, up to two ADUs per lot became allowed, owner-occupancy was eliminated, and off-street parking requirements were dropped.
2025Development standards refined. Ordinance M-4517, codified in November 2025, further amended ADU development standards and the rules for converting existing garages or outbuildings into ADUs.
2026Rental Registration Program launches. Adopted by City Council in July 2025 and effective January 1, 2026, the program requires an annual $30-per-unit registration license for long-term rental housing citywide, including ADUs.
Vancouver has grown quickly in recent years, and Clark County's housing market has stayed notably tight. Regional reporting ties part of that demand to in-migration from higher-cost, higher-tax parts of the Portland metro across the river - Washington has no state income tax, while Oregon's top marginal rate runs close to 10%. That dynamic hasn't been measured specifically against ADU construction, but it plausibly adds to interest in ADUs as one of the few ways to add housing on an already-built lot.
Permit process
How Vancouver ADU permitting works
1
Confirm zoning eligibility
Contact Land Use Planning to confirm your lot's zone, setbacks, and height standards, especially if you're converting an existing garage or outbuilding.
2
Submit a Request for Utility Services
This determines whether civil engineering review is needed for water or sewer capacity before you finalize your design.
3
Prepare your plan set
Site plan, floor plans, elevations, and structural drawings meeting Washington State Residential Code standards.
4
Apply for a residential building permit
Required for every ADU, including one built entirely inside the existing house. Submit through the city's online permitting system; plan review is handled by the Building Plans Examiners.
5
Construction & inspections
Once permits issue, build and schedule the standard framing, plumbing, electrical, and final inspections.
6
Register the rental (if renting)
Long-term rentals need an annual $30 rental registration license starting in 2026; short-term rentals under 30 days need a separate STR permit and business license.
Contacts: Building Plans Examiners, planreview@cityofvancouver.us / 360-487-7828. Land Use Planning, cddplanning@cityofvancouver.us / 360-487-7803. Fees and timelines change periodically - confirm current figures with Community Development.
Budgeting
What it costs to build an ADU in Vancouver
Garage conversion
Roughly $70,000-$180,000, the least expensive path since the shell already exists
Basement conversion
Roughly $100,000-$220,000, depending on existing ceiling height and utility access
New detached ADU
Roughly $150,000-$330,000+ for a code-compliant, fully finished freestanding unit
Impact fees
Capped by state law at 50% of the principal dwelling's impact fees
Rental registration (if renting long-term)
$30 per unit per year starting January 1, 2026; waived if you register within the program's first 90 days
These are general ranges from local contractor estimates and regional reporting, not quotes - Vancouver's costs tend to run more moderate than Seattle-area cities like Bellevue, though actual cost still depends heavily on lot conditions, finishes, and utility work.
Before you apply
Tips for a smooth approval
Start with the Request for Utility Services. Many delays come from water or sewer capacity questions, not zoning - get that checked before you finalize a design.
Register a long-term rental early. The new $30/year registration fee is waived if you register within the first 90 days of the program launching January 1, 2026.
Double-check garage conversion setbacks. A converted garage or outbuilding must meet the primary structure's setback standards, not the looser rule for ordinary accessory structures, so measure before you assume your existing footprint works.
Confirm your impact fee amount up front. It's capped at 50% of the primary home's rate under state law, but the exact dollar figure depends on your specific project - ask Community Development early.
Decide your rental strategy before you design. Short-term rentals need a separate $250 STR permit and $50 business license on top of the long-term rental registration, so plan for whichever path you intend to take.
FAQ
Common questions
Do I need to live on the property to build an ADU in Vancouver, WA?
No. Vancouver eliminated its owner-occupancy requirement under Ordinance M-4378 in September 2024, and Washington's 2023 statewide ADU law (HB 1337) bars cities from reinstating it.
How many ADUs can I build on one lot?
Up to two, in any combination of attached and detached, in addition to the primary dwelling.
Do I need extra parking for an ADU?
No additional off-street parking is required specifically for the ADU.
What's the maximum size for an ADU?
1,000 sq ft of gross floor area, whether attached or detached. Height matches whatever the underlying zone allows for the primary dwelling.
How long does the permit process take?
Timelines vary by project type and completeness of the application - confirm current review times with Community Development before budgeting your schedule.
How much does an ADU cost to build in Vancouver?
Garage conversions tend to run roughly $70,000-$180,000, basement conversions $100,000-$220,000, and new detached units $150,000-$330,000 or more, based on local contractor estimates and regional reporting - not counting permit or impact fees.
Does Washington's statewide ADU law change anything for Vancouver specifically?
Yes. HB 1337 (2023) set a floor under Vancouver's own rules - guaranteeing two ADUs per lot, at least 1,000 sq ft of floor area, capped impact fees, and no parking mandate near transit - and Vancouver updated its local code (Ordinance M-4378) in September 2024 to formally comply.
Do I need to register my ADU as a rental?
If you rent it long-term, yes - Vancouver's Rental Registration Program, effective January 1, 2026, requires an annual $30-per-unit registration license. Short-term rentals under 30 days need a separate STR permit and business license instead.
Can I rent my ADU out on Airbnb or a short-term rental platform?
Yes, with a permit. Vancouver requires a $50 business license and a one-time $250 short-term rental permit for stays under 30 days, separate from the long-term rental registration program.
