ADU rules in Medford

Medford allows one detached ADU (an 'ADU-D', which 'shares no common walls with the primary dwelling or the ADU-A') wherever there is a qualifying primary dwelling. Table 10.314 lists 'Accessory Dwelling Unit (ADU)' as 'Ps', a permitted use subject to the special use standards of 10.821, in all eight residential zones from SFR-00 through MFR-30, and 10.821(3) plus the SIC 881 'Dwelling Units' row of 10.337 extend ADUs into the commercial and industrial zones wherever the primary use on the property is already a primary dwelling. The primary dwelling has to be a detached single-family dwelling, an attached single-family dwelling divided by a lot line (duplex or townhouse), or a manufactured dwelling on an individual lot, and only one ADU is allowed per primary dwelling. ADUs are not counted in residential density, but in the single-family zones the total number of units on one unit of land, ADUs included, may not exceed four, and the ADU provisions do not apply inside cottage cluster developments.

An 'ADU-A' is defined as one 'attached to the primary dwelling unit by a shared wall or as an additional story above or below the primary dwelling unit', so additions, over-garage units, basement units and upper-floor conversions all qualify. Section 10.821(2)(c) expressly allows an ADU created by converting an existing structure as well as by new construction, and lets nonconforming existing structures be used subject to the nonconformity standards of 10.032 through 10.037 and to approval by the Building Official and the Planning Director. Interior conversions carry a tighter size cap than new construction: 50 percent of the primary dwelling's gross floor area instead of 75 percent, still under the same 900 square foot ceiling.

Section 10.821(2)(d) caps the ADU at 'not exceed 75 percent of the GFA of the primary dwelling, or 900 square feet, whichever is less', so 900 square feet is a hard ceiling and modest primary homes hit the percentage first: a 1,000 square foot house supports only a 750 square foot ADU. Converting existing space inside the primary dwelling into an attached ADU is capped at 50 percent of the primary dwelling's GFA or 900 square feet, whichever is less. 'Floor area' is defined in 10.012 as the sum of the gross floor area of each story measured from the exterior faces of the structure, including basement floor area and habitable attic area, excluding courts, unenclosed porches and vent shafts. There is no ADU-specific height limit; the ADU takes the base zone's height, setback and lot coverage standards, except that lot coverage may be exceeded by up to 10 percent and that extra coverage is reserved for the ADU alone.

Medford imposes no owner-occupancy requirement on ADUs, at application or on an ongoing basis. Section 10.821 is silent on occupancy, and exact-phrase searches of the entire municipal code return no hits at all for 'owner occupancy'; 'owner occupied' appears only in the boarding and lodging house definition in 10.012, the matching boarding house rows of Table 10.314, and a sidewalk-repair notice provision in 3.023. That matches state law: ORS 197A.425(1)(b)(B), the recodified successor to the SB 1051 and HB 2001 ADU mandate formerly at ORS 197.312(5) and (6), provides that 'reasonable local regulations relating to siting and design' do not include 'owner-occupancy requirements of either the primary or accessory structure'. ORS 197A.425(2) would let Medford require owner-occupancy specifically for vacation occupancies, but the vacation rental license criteria in 8.031(3) ask only for a 24-hour contact person, annual neighbor notice and good neighbor guidelines, not that the owner live on site.

Section 10.821(2)(f) says flatly that 'No additional parking shall be required for an ADU.' The primary dwelling still has to satisfy Table 10.743-1, which sets a minimum of 2.0 spaces per dwelling unit for 'Residential, Single-Family', and where an existing primary dwelling falls short the code will forgive up to one of those spaces if the parcel is in the Central Business overlay or an established Transit Oriented District, within a quarter mile of a transit stop, within a half mile of a bike lane, shared-use path or neighborhood bikeway, has at least 24 feet of frontage with usable on-street parking, or cannot comply because of structures built before January 1, 2019. Separately, 10.743(3) exempts whole areas from parking minimums outright, including the Central Business District, anything within a half mile of a designated frequent transit corridor, the Historic Preservation Overlay and Climate Friendly Area overlays. One siting rule to design around: where alley access is available the ADU must take its vehicle access from the alley unless off-street parking need not be built at all. Oregon law reaches the same result, since ORS 197A.425(1)(b)(B) bars requiring additional off-street parking as an ADU condition.

An ADU is a permitted use subject to special-use standards ('Ps') in every residential zone under Table 10.314 and in every commercial and industrial zone under the SIC 881 'Dwelling Units' row of 10.337, which states that 'the special use regulations for accessory dwelling units (ADUs) in commercial and industrial zones correspond with special use Section 10.821'. ADUs appear on none of Medford's land use review lists (Type I in 10.142, Type II in 10.168, Type III in 10.182), and 10.200(3)(b)(iv) exempts detached single-family residential development on a legally created lot from Site Plan and Architectural Review, so a code-compliant ADU is handled administratively through the building permit, with the 10.821 standards applied at plan check. Two exceptions bite. Inside the Historic Preservation Overlay, 10.821(1)(b) and 10.406 route new construction and exterior alterations to a Type III Historic Review or a Minor Historic Review. And legalizing a pre-2019 unpermitted ADU that cannot meet the Article V standards requires a Type III Exception under 10.186.

Nothing in 10.821 limits who may occupy an ADU or for how long, and there is no minimum lease term and no owner-occupancy test, so ordinary long-term rental is unrestricted. Renting to overnight guests is a 'vacation rental' that needs a City of Medford business license: 8.031(3) requires the owner to name someone reachable by telephone 24 hours a day, seven days a week while the property is occupied, to distribute a flier with that contact information to neighbors within 250 feet each year, and to build the city's good neighbor guidelines into the rental contract. Medford's 11 percent transient lodgings tax under 8.800 through 8.820 applies to any dwelling unit or portion of one rented for 27 consecutive days or less. The catch that matters most for new ADUs is the incentive: an owner who takes the 50 percent ADU system development charge reduction must record a restrictive covenant with Jackson County agreeing not to use the ADU as a short-term rental, defined as fewer than 30 consecutive days, for 10 years, and must file an annual questionnaire reporting the monthly rent charged and certifying no short-term use; opting out or defaulting means repaying the exempted charges with 9 percent interest. The ADU also cannot be sold off separately, since 10.012 requires it to sit on the same tax lot as the primary dwelling.