ADU rules in Ashland

A detached backyard ADU (Ashland calls it an accessory residential unit, or ARU) is permitted outright with a building permit in every residential zone: R-1, R-1-3.5, RR, WR, R-2, R-3, plus the Normal Neighborhood (NN) and North Mountain (NM) districts. The definition in AMC 18.6.1.030 expressly contemplates a unit 'located in a detached building located on the same lot' with its own entrance. One ARU is allowed per lot and total dwellings on the lot may not exceed two, so a lot that already holds a duplex cannot add one. ARUs are exempt from the zone's maximum density and minimum lot area standards, so there is no lot-size gate.

The same section covers attached and interior units on identical terms. AMC 18.6.1.030 defines an accessory residential unit as one that 'can be attached to a single-family dwelling, within a portion of an existing single-family dwelling (i.e., conversion of gross floor area within the primary residence), or located in a detached building,' so basement conversions, garage conversions and additions all qualify. Ashland's own ADU Guide lists the four accepted variations as detached in the backyard, attached addition, above a garage, and conversion of existing floorspace, garage or basement. The only practical difference is in the Historic District Overlay, where attached and interior floor area counts toward the maximum permitted floor area while a detached unit set six feet or more from the house does not.

AMC 18.2.3.040.F splits the cap by zone, measured as gross habitable floor area (GHFA). In the R-1, R-1-3.5, RR, WR and NN zones an ARU may not exceed 50 percent of the single-family dwelling's GHFA and may not exceed 1,000 sq ft. In the R-2 and R-3 multiple-family zones the same 50 percent rule applies but the ceiling drops to 500 sq ft. In the North Mountain NM zones the cap is 750 sq ft, or 500 sq ft where the unit is a second story above a detached accessory building. The 50 percent test usually binds first on a modest house: a 1,400 sq ft home caps the ARU at 700 sq ft even in R-1. The unit must also meet chapter 18.2.5 dimensional standards for lot coverage, setbacks and height (35 ft or 2 1/2 stories in the R-1 zones, 30 ft inside the Historic District Overlay).

No owner-occupancy condition exists anywhere in Ashland's ARU rules. AMC 18.2.3.040 opens with an exhaustive list ('provided the accessory residential unit meets all of the following requirements') running A through F, covering zone, unit count, density, minimum-density crediting, dimensional standards and size, and none of them touches who lives on the property. Oregon law also forecloses one: ORS 197A.425(1)(b)(B) says reasonable local regulations relating to siting and design 'does not include owner-occupancy requirements of either the primary or accessory structure.' The residency requirements that do exist in Ashland's code attach to travelers' accommodations, not to ARUs, which ORS 197A.425(2) expressly preserves by allowing local regulation of vacation occupancies.

Ashland does not require any off-street parking for an ARU, and in fact requires none for any use. Ordinance 3229 (12/19/2023) rewrote chapter 18.4.3 so that AMC 18.4.3.030 now contains only subsection A, 'Maximum Number of Off-Street Automobile Parking Spaces,' and Table 18.4.3.040 carries only two data columns: maximum voluntarily provided off-street automobile spaces, and minimum bike spaces. The row for 'Single-Family Dwellings, Accessory Residential Units and Duplexes' reads 'No maximum' for cars and 'No bike parking requirements.' Building more spaces than a listed maximum, where one applies, would need a conditional use permit, but that ceiling does not bind single-family lots. State law reaches the same result independently: ORS 197A.425(1)(b)(B) bars requiring additional off-street parking as a condition of ADU approval.

Ministerial. AMC 18.2.3.040 states that accessory residential units 'are permitted outright with an approved building permit' when they meet the section's standards, and Table 18.2.2.030 lists the use as 'S' (permitted subject to special use standards) rather than 'CU' in R-1, R-1-3.5, R-2, R-3, RR and WR. AMC 18.5.2.020.C.2 then exempts ARUs meeting section 18.2.3.040 from Site Design Review, so there is no discretionary land use hearing and no public notice step. The city's ADU Guide describes the same path: property owners 'do not need to go through a complex Planning Action process' and instead proceed directly to a building permit. A conditional use permit re-enters only in narrow situations, chiefly exceeding the maximum permitted floor area in the Historic District Overlay.

Nothing in AMC 18.2.3.040 limits who may occupy an ARU, so ordinary long-term tenancy needs no registration, license or deed restriction. Short-term use is a different land use. AMC 18.6.1.030 defines residential use as long-term occupancy and treats occupancy for less than 30 days as transient lodging, and Table 18.2.2.030 marks both 'Travelers' Accommodation' and 'Accessory Travelers' Accommodation' as 'N' (not allowed) in R-1, R-1-3.5, RR and WR, and 'CU+S' in R-2 and R-3 only. Where allowed, AMC 18.2.3.220 layers on a conditional use permit, Site Design Review, business-owner residency on site, a primary residence at least 20 years old, proximity to a boulevard, avenue or neighborhood collector, a business license and transient occupancy tax; an accessory travelers' accommodation additionally may not have kitchen cooking facilities, which an ARU by definition has. The city's ADU Guide states the practical result: in single-family zones ADUs 'cannot be utilized as vacation rentals and cannot be rented for intervals of less than 30 days.'