ADU rules in Beaverton

A detached backyard ADU is permitted outright. Section 60.50.03.2.B.3 lists 'Constructing a new detached dwelling or placing a manufactured home on the lot' as one of the ways to create an ADU, and Table 20.05.20.A makes 'Accessory Dwelling Units' a Permitted (P) use in all four residential zones (MR, RMA, RMB, RMC). The ADU must accompany a single-detached dwelling: Section 60.50.03.2.A allows one 'only in conjunction with a single-detached dwelling', which excludes lots developed with a duplex, triplex, quadplex, townhouse or cottage cluster. A detached unit must stand at least 6 feet from the primary dwelling and any other structure on the site, and a one-story ADU no taller than 15 feet may sit 5 feet from the rear property line regardless of the zone's normal rear setback.

Attached and internal ADUs are permitted on the same footing as detached ones. Section 60.50.03.2.B allows an ADU created by 'Conversion of existing living area, attic, basement or garage' or by 'Adding floor area to the primary structure or to an accessory structure'. The Chapter 90 definition of Accessory Dwelling Unit confirms the unit 'can be within or attached to the single-detached dwelling, a detached building or a manufactured home', and that an attached unit 'may have a separate exterior entrance or an entrance to an internal common area accessible to the outside'. Only an ADU created by adding floor area to an accessory structure is required to have its own exterior entrance (60.50.03.2.D.1).

Section 60.50.03.2.C.1 caps an ADU at 800 square feet of floor area. The exception in 60.50.03.2.C.2 is generous and often decisive: an ADU 'that result[s] from the conversion of a level or floor (e.g. basement, attic, or second story) of the primary dwelling' is not subject to the 800 sq ft cap and may occupy that entire level, provided no new square footage is added through a contemporaneous renovation. Beaverton dropped the older 'lesser of 800 sq ft or 50 percent of the primary dwelling' formula in ORD 4822 (effective June 30, 2022); several ADU vendor sites still quote the repealed 50 percent test. Height is governed by the underlying zone except for the 15-foot one-story form that buys the reduced 5-foot rear setback.

There is no owner-occupancy requirement anywhere in the operative text: not in Section 60.50.03 (the ADU standards, last amended by ORD 4859 effective January 2, 2025), not in the Section 40.05 application procedure or its approval criteria, not in the Chapter 20 use tables, and not in the Chapter 90 definition. State law independently forbids one. ORS 197A.425(1)(b)(B) provides that 'Reasonable local regulations relating to siting and design' does not include 'owner-occupancy requirements of either the primary or accessory structure or requirements to construct additional off-street parking.' Beaverton's population is far above the 2,500 threshold in ORS 197A.425(1)(a), so the mandate applies. There is no local text in conflict with the statute here, so this is a clean 'no' rather than a preempted-but-still-printed requirement.

Section 60.30.10.3.A.1 states flatly: 'Minimum number of required parking spaces. No minimum parking is required for any use.' ORD 4844 (August 2023, the Parking Policy and Code Project) converted Beaverton's whole parking chapter from minimums to maximums. Table 60.30.10.5.A does list a row for 'Dwelling, Accessory Unit' at 1.8 spaces in both Parking Zone A and Parking Zone B, but that column is headed 'Maximum Permitted Parking Spaces', so it is a ceiling on how much parking you may build, not a requirement. State law reinforces this: ORS 197A.425(1)(b)(B) bars 'requirements to construct additional off-street parking' as a condition of ADU approval.

An ADU needs a dedicated Accessory Dwelling Unit land use application, triggered whenever 'An accessory dwelling unit is proposed to be added to a property' (40.05.15.1.A.1), but it is ministerial: 'The Type 1 procedure, as described in Section 50.35. of this Code, shall apply to an application for Accessory Dwelling Unit. The decision making authority is the Director.' There is no hearing and no discretionary criterion; the approval criteria are compliance checks against Chapter 20 and Chapter 60 plus fees and submittal completeness. A building permit is required on top of the land use decision, and new Planning Division applications are filed through the Beaverton Electronic Permitting System (BEPS). An attached ADU built as a floor-area addition to a house in the RMA, RMB, RMC or CM-RM zone also triggers Single-Detached and Middle Housing Design Review One under 40.21.15.1.A.5, which is likewise a Type 1 Director decision.

Nothing in the Development Code limits who may occupy an ADU or for how long, and there is no owner-occupancy test, rental cap, or rental registration to satisfy, so long-term renting is unrestricted. Beaverton has no short-term rental ordinance and no STR license: searches of the Beaverton Code (current through Ordinance 4880, March 3, 2026) turned up no short-term-rental or vacation-rental chapter, and the Development Code has no short-term rental, vacation rental or transient lodging use category. What does apply is the lodging tax. Beaverton Code 7.18.015.O.3 defines 'transient lodging' to include 'Houses, cabins, condominiums, apartment units or other dwelling units, or portions of any of these dwelling units, used for temporary human occupancy', and 7.18.015.N defines a 'transient' as anyone occupying for fewer than 30 consecutive days, so an ADU rented nightly is taxable: 4 percent of rent under 7.18.020.A, with the host or booking platform registering as a transient lodging tax collector under 7.18.060. Separate sale is not available: an ADU is by definition a second unit on the same lot, and Beaverton's middle housing land division path in Section 40.45 covers middle housing, not ADUs. An owner who wants two separately sellable units can build a duplex instead, because the Chapter 90 definition lets an applicant whose second unit satisfies both definitions choose which to apply for.