ADU rules in McMinnville

A detached backyard ADU is allowed outright with a detached single dwelling in the R-1, R-2, R-3 and R-4 residential zones, where 'Accessory Dwelling Unit (ADU)' is listed as a permitted use (17.12.010(D), 17.15.010(D), 17.18.010(D), 17.21.010(D)). Section 17.11.040(B)(3) expressly contemplates 'construction of a detached accessory dwelling unit on a lot with a primary single dwelling', and 17.11.040(B)(4) also lets you build a new primary house and re-designate the existing house as the ADU. Only one ADU is allowed per lot or parcel. ADUs are prohibited in the R-5, C-1 and C-2 zones and are limited in C-3 to lots holding a single dwelling built and occupied before November 25, 2021.

Attached and internal ADUs are allowed on exactly the same terms as detached ones: 17.11.040(A) says 'An accessory dwelling may be located within, attached to or detached from the primary single dwelling.' Section 17.11.040(B) lists conversion of an attic, basement, garage or any other portion of the primary dwelling, and adding floor area including a second story, as approved ways to establish the unit. The same 50 percent / 1,000 square foot cap and one-per-lot limit apply. Manufactured homes, recreational vehicles, travel trailers and other towable structures may not be used as an ADU, though modular structures may.

Section 17.11.040(B)(5) caps the ADU at 50 percent of the primary dwelling exclusive of the garage, or 1,000 square feet, whichever is less; the minimum size is whatever the Oregon Building Codes Division requires. Table 1 in 17.11.040(C) adds three shape controls: a detached ADU may not exceed the height of the primary building or 25 feet, whichever is less; the ADU's lot coverage may not be larger than the coverage of the primary dwelling; and front, side and rear setbacks match the underlying zone, subdivision or Planned Development overlay. Note that the 50 percent test means a modest primary house, not the 1,000 square foot ceiling, is usually the binding constraint: a 1,600 square foot house yields an 800 square foot ADU.

Nothing in McMinnville's Title 17 requires the owner to live on the property; a full-text search of the 384-page operative zoning ordinance returns no owner-occupancy provision of any kind, and section 17.11.040 imposes no residency condition. This matches ORS 197A.425(1)(b)(B), which excludes 'owner-occupancy requirements of either the primary or accessory structure' from the reasonable siting and design regulations a city may impose on ADUs. The only occupancy hook sits on short-term rental use, which state law leaves cities free to regulate: a Resident Occupied Short-Term Rental must by definition be occupied full time by a resident, and a full Short-Term Rental permit requires the owner or the owner's agent to live within the 97128 zip code and be reachable 24 hours a day.

Table 1(k) of section 17.11.040(C) is explicit: 'No additional off-street parking is required for accessory dwelling units.' The off-street parking chapter backs this up, since the residential parking table in 17.60.060(A) has no ADU line at all (it covers single detached dwellings, middle housing, apartments, SROs and short-term rentals). This complies with ORS 197A.425(1)(b)(B), which bars cities from requiring additional off-street parking as a condition of ADU approval. The one exception is short-term rental use, which ORS 197A.425(2) preserves as vacation-occupancy regulation: an ADU operated as a full Short-Term Rental must provide one off-street, hardscaped space per bedroom on the same property.

An ADU is an outright permitted use, reviewed administratively. It appears in the permitted-use list of every zone that allows it (for example 17.12.010(D) in R-1) and is absent from the conditional-use lists in those chapters, so no Planning Commission hearing is involved. It is also absent from all three application tracks in Chapter 17.72 (Director's Review without Notification, Director's Review with Notification, and Public Hearings), meaning there is no land use application to file at all: the city's Applications & Fees page lists no ADU form. What an ADU does trigger is building permit review, including a Residential Design Standards Review, which the 2026/2027 Planning Fee Schedule prices at $1,450 for a single dwelling, plex, townhome or ADU and which may be requested before building permit submittal.

The zoning ordinance places no cap, minimum lease term, licensing regime or primary-residence test on renting an ADU on an ordinary long-term lease, and the C-3 version of the ADU standards states the general principle that 'occupancy and use standards for an ADU shall be the same as those applicable to a primary dwelling on same site.' Short-term rental, defined in Chapter 17.06 as use of an entire dwelling unit for rent for no more than 30 consecutive days, is a separate permitted use that expressly includes ADUs but requires a Short-Term Rental permit under 17.12.010(P), reviewed by the Planning Director with mailed notice to owners within 100 feet and a prior neighborhood meeting. The binding conditions are a 500-foot separation from any other short-term rental (and no two on one property), one off-street hardscaped space per bedroom, transient lodging tax registration, the permit number in every listing, and annual renewal ($1,833 initial and $259 renewal in FY 2026/2027). Permits are issued to the current owner and become void on sale. A smaller Resident Occupied Short-Term Rental permit (up to two guest rooms, resident living there full time) is the alternative under 17.12.010(O). The ordinance contains no mechanism for selling an ADU separately from the primary dwelling: it is allowed 'only in conjunction with a detached single dwelling' and stays on the same lot.