ADU rules in Vancouver

Detached backyard ADUs are allowed, and up to two ADUs (in any mix of attached and detached) may share a lot with the house. Vancouver replaced its entire land use code on July 31, 2026 (Ord. M-4533), so there is no longer a standalone ADU chapter: a lot with a house plus ADUs is regulated as the Flex-Plex Building Type (FPB), described as a cluster of two to six detached or attached units including 'single-unit and rowhouses with up to two (2) accessory dwelling units (attached or detached).' FPB is allowed in the Low-Scale Neighborhood, Medium-Scale Neighborhood, Mixed-Use Neighborhood, Institutional/Campus and Manufactured Home districts, which covers every district where detached houses are allowed. Existing garages and outbuildings may still be converted, and 20.430.070(B)(3) lets that happen 'even if they violate current code requirements for setbacks and/or max impervious.'

Attached and internal ADUs (basement, addition, conversion inside the house) are allowed on the same terms as detached ones. The code's definition covers both forms: 'An attached ADU is located within or attached to a housing unit. A detached ADU is a unit that is separate from a housing unit and is on the same property.' The Single-Family Residential Building Type states that when a single-family building includes ADUs, 'the 040 Flex Plex Building Type (FPB) will be utilized,' so the same two-ADU allowance and the same building standards apply whichever form you build. Setbacks under FPB are 5 feet at the side and rear, zero feet from an alley, and buildings on the same lot may sit on a zero lot line.

The 1,000 sq ft ceiling is now definitional: an ADU is 'a dwelling unit located on the same lot as a single-family housing unit, duplex, triplex, fourplex, townhome or rowhome under 1,000 square feet.' The impact fee section confirms the same figure, giving the reduced ADU rate to 'up to two ADUs (1,000 square feet or less).' There is no ADU-specific height limit; an ADU built as part of a Flex-Plex takes the zoning district height range, which in the Low-Scale Neighborhood district is three floors above grade and 45 feet. Because Flex-Plex allows two to six units on a parent parcel, a unit over 1,000 sq ft is still buildable, it simply counts as an ordinary dwelling unit rather than an ADU (and loses the 50 percent impact fee break). The repealed VMC 20.810.040(D) used the same 1,000 sq ft cap, so this number did not change on July 31, 2026.

No owner-occupancy requirement, at application or afterward. The city answers the question directly: 'No, the property owner is not required to live on the property where an ADU is located.' The rewritten Title 20 contains no ADU occupancy standard of any kind (the words appear nowhere in the ADU, building type or use chapters), and the repealed VMC 20.810 had dropped owner occupancy well before that. Washington also forbids it: RCW 36.70A.681(1)(b) says a city 'may not require the owner of a lot on which there is an accessory dwelling unit to reside in or occupy the accessory dwelling unit or another housing unit on the same lot.' You can rent out both the house and the ADU.

The July 31, 2026 code eliminated minimum off-street parking for all residential development citywide: Table 20.450.045-3 lists 'Residential Uses / Any Residential Uses' at 'None Required,' and the bicycle parking table requires none for household living on parcels of six or fewer units. The city summarizes the change as 'Parking allowed but not required.' The old rules were already generous but not this clean: repealed VMC 20.810.040(G) required no additional parking for an ADU, while 20.810.060(A) said converting a garage 'shall not result in the elimination of the requirement of one legal on-site parking space to serve the single-family residence.' That leftover space-for-the-house rule is gone, though the city's ADU page still describes it for applications received before 7/31/2026. Vancouver is therefore well past the RCW 36.70A.681(2) floor, which only bars parking mandates within half a mile of a major transit stop.

Ministerial. A house plus one or two ADUs is six or fewer dwelling units on a parent parcel, and the new code exempts that scale from land use review twice over: 20.210.030(A)(13) exempts 'Middle housing developments, 6 or fewer dwelling units on a parent parcel' from the procedures of the decision-making chapter, and 20.280.020(D)(3) exempts new construction of single-family and middle housing of six units or less from site plan review. The city confirms the permit path: 'Residential construction of 1-6 housing units on one lot and three (3) or fewer floors above grade will be processed as a Residential Building Permit (RES).' No hearing, no discretionary criteria, no neighbor notice. Seven or more units on a parcel, or four or more stories, drops you into Type I site plan review plus a commercial building permit.

An ADU can be rented long term with no owner-occupancy or minimum-lease condition beyond the code's definition of household living: 'Length of tenancy. Tenancy is longer than thirty (30) calendar days.' Renting it does pull the property into the city's rental housing registration program, which has applied since January 1, 2026 and exempts only 'owner-occupied single-family residences without an accessory dwelling unit' (VMC 5.08.050, 5.08.060). Renting for fewer than 30 consecutive nights makes it a short-term rental, which needs a nontransferable STR permit plus a city business license, expires on sale of the property, and competes for a hard citywide cap: 'the city may issue no more than eight hundred and seventy (870) active short-term rental permits at any given time.' STRs are 'only permitted within a legally established dwelling unit' and may not be operated 'in an accessory structure,' so a permitted ADU qualifies but a converted shed does not. Units can also be sold off separately through a unit lot subdivision (up to nine unit lots, processed as a short plat) or as condominiums.