ORS 197A.425: Accessory dwelling units.

(1)(a) A city with a population greater than 2,500 or a county with a population greater than 15,000 shall allow in areas within the urban growth boundary that are zoned for detached single-unit dwellings the development of at least one accessory dwelling unit for each detached single-unit dwelling, subject to reasonable local regulations relating to siting and design.

      (b) As used in this subsection:

      (A) “Accessory dwelling unit” means an interior, attached or detached residential structure that is used in connection with or that is accessory to a single-unit dwelling.

      (B) “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.

      (2) Subsection (1) of this section does not prohibit local governments from regulating vacation occupancies, as defined in ORS 90.100, to require owner-occupancy or off-street parking.