Oregon Revised Statutes Chapter 215 § 215.495 — Accessory dwelling units

Accessory dwelling units. (1) As used in this section: (a) “Accessory dwelling unit” has the meaning given that term in ORS 215.501. (b) “Area zoned for rural residential use” has the meaning given that term in ORS 215.501. (c) “Single-unit dwelling” has the meaning given that term in ORS 215.501. (2) Consistent with a county’s comprehensive plan, a county may allow an owner of a lot or parcel within an area zoned for rural residential use to construct one accessory dwelling unit on the lot or parcel, provided: (a) The lot or parcel is not located within an area designated as an urban reserve as defined in ORS 197A.230; (b) The lot or parcel is at least two acres in size; (c) One single-unit dwelling is sited on the lot or parcel; (d) The existing single-unit dwelling property on the lot or parcel is not subject to an order declaring it a nuisance or subject to any pending action under ORS 105.550 to 105.600; (e) The accessory dwelling unit will comply with all applicable laws and regulations relating to sanitation and wastewater disposal and treatment; (f) The accessory dwelling unit will not include more than 900 square feet of usable floor area; (g) The accessory dwelling unit will be located no farther than 100 feet from the existing single-unit dwelling; (h) If the water supply source for the accessory dwelling unit or associated lands or gardens will be a well using water under ORS 537.545 (1)(b) or (d), no portion of the lot or parcel is within an area in which new or existing ground water uses under ORS 537.545 (1)(b) or (d) have been restricted by the Water Resources Commission; (i) No portion of the lot or parcel is within a designated area of critical state concern; (j) The lot or parcel is served by a fire protection service provider with professionals who have received training or certification described in ORS 181A.410; and (k) The county has adopted land use regulations that ensure that: (A) The accessory dwelling unit has adequate setbacks from adjacent lands zoned for resource use; and (B) The accessory dwelling unit has adequate access for firefighting equipment, safe evacuation and staged evacuation areas. (3) A county may not allow an accessory dwelling unit allowed under this section to be used for vacation occupancy, as defined in ORS 90.100. (4) A county that allows construction of an accessory dwelling unit under this section may not approve: (a) A subdivision, partition or other division of the lot or parcel so that the existing single-unit dwelling is situated on a different lot or parcel than the accessory dwelling unit. (b) Construction of an additional accessory dwelling unit on the same lot or parcel. (5) A county may require that an accessory dwelling unit constructed under this section be served by the same water supply source or water supply system as the existing single-unit dwelling, provided such use is allowed for the accessory dwelling unit by an existing water right or a use under ORS 537.545. If the accessory dwelling unit is served by a well, the construction of the accessory dwelling unit shall maintain all setbacks from the well required by the Water Resources Commission or Water Resources Department. (6) An existing single-unit dwelling and an accessory dwelling unit allowed under this section are considered a single unit for the purposes of calculating exemptions under ORS 537.545 (1). (7) Nothing in this section requires a county to allow any accessory dwelling units in areas zoned for rural residential use or prohibits a county from imposing any additional restrictions on accessory dwelling units in areas zoned for rural residential use, including restrictions on the construction of garages and outbuildings that support an accessory dwelling unit. [2021 c.396 §2; 2022 c.85 §5; 2023 c.76 §1; 2023 c.611 §9; 2025 c.38 §37; 2025 c.589 §1; 2025 c.590 §18]