ADU rules in Gresham

Gresham allows one accessory dwelling per existing primary single detached dwelling anywhere such a dwelling legally exists, with no conditional-use hearing and no lot-size gate. Community Development Code 10.0110(B) says an Accessory Dwelling 'may be freestanding or attached to the primary dwelling,' and the section opens by directing that 'The Manager shall approve' a complying application. Freestanding units get their own setback line in Table 10.0110: no closer to the street than the primary dwelling, 5 ft from an interior side lot line, 10 ft from a rear line with no alley and 5 ft where an alley abuts. A freestanding unit may not exceed the height of the primary dwelling, and its primary entry may not face an interior lot line when it sits within 10 feet of that line.

The same standard covers attached and fully internal units, which take the ordinary single detached dwelling setbacks of the land use district rather than the freestanding table. The Article 3 definition of Accessory Dwelling spells out the range: attached units 'may be interior to the primary dwelling; attached by a wall, ceiling, or floor; connected by a roof, breezeway, deck, or other structural connection; or above an attached garage,' so basement conversions and interior carve-outs qualify as long as the unit has its own kitchen, bathroom and sleeping area. Since June 4, 2026 conversions, attached units and freestanding units all run through one review track and one size cap; the city's older ADU handout, which split them into Type I conversions and Type II attached units with different caps, no longer matches the code.

One cap now applies to every ADU type: 'Accessory Dwellings shall have a maximum floor area of 900 square feet or 75 percent of the floor area of the primary dwelling, whichever is less.' Because it is the lesser of the two, a modest primary house is often the binding constraint, so a 1,000 sq ft house supports only a 750 sq ft ADU. This replaced a tiered scheme on June 4, 2026; the prior code held freestanding units to 750 sq ft and 50 percent of the primary dwelling, and capped a unit built beside or behind a detached garage at 750 sq ft counting the garage. Height is the second limit: the ADU must meet the district maximum (35 ft in LDR-5, LDR-7, TR, TLDR, MDR-12 and OFR) and a freestanding ADU may not exceed the height of the primary dwelling, with a further rear roof height limit in LDR-5, LDR-7, TR, LDR-PV, VLDR-SW and LDR-SW that starts at 21 ft at the rear setback line and rises one foot for every additional foot of distance from the rear property line.

Section 10.0100 lists its approval standards exhaustively at 10.0110(A) through (N) and none of them requires the owner to live on the property, at application or on an ongoing basis, and the June 2026 rewrite added no such requirement. State law also forecloses one: ORS 197A.425(1)(b)(B) provides that 'reasonable local regulations relating to siting and design' does not include 'owner-occupancy requirements of either the primary or accessory structure.' Gresham, a Metro city of roughly 110,000 inside the urban growth boundary, is well past the 2,500 population threshold that triggers the mandate. Owner occupancy surfaces only in short-term rental licensing, where a 'hosted homeshare' under Gresham Revised Code 9.56.025 must be owner-occupied, and ADUs are barred from short-term rental use in any case.

Gresham has abolished parking minimums citywide, so an ADU adds no parking obligation. Development Code 9.0802(A) states flatly that 'Vehicle parking minimums are not required for any land use type,' and Table 9.0851(A)(1)(a) lists the auto parking requirement for single detached dwellings as None across LDR-5, LDR-7, TR, TLDR, MDR-12, OFR and the plan district low density zones. Section 10.0100 sets no separate ADU space count; its Vehicle Access and Parking subsection only governs how parking is arranged if you build it (alley access where an alley abuts, driveway approaches limited to 34 percent of frontage or 28 feet, stalls of 8.5 by 18 feet, tandem parking allowed only within a single unit). ORS 197A.425(1)(b)(B) independently bars requiring additional off-street parking as a condition of ADU approval. Gresham's November 2022 ADU handout still says three paved parking spaces are needed on site; that sheet is out of date.

Every ADU is now a ministerial approval: 'An application for an accessory dwelling shall be reviewed by the Manager under a Type I procedure.' Type I is Gresham's clear-and-objective track under Section 11.0300, with no pre-application conference, no neighborhood meeting and no public notice, decided by the Manager within roughly 45 days of a complete application and appealable only within 12 days. Building permits follow separately under the Oregon Residential Specialty Code. This is a real change: before June 4, 2026 only interior conversions were Type I, while attached, over-garage and most freestanding ADUs went through Type II administrative review with mailed notice and a substantially longer timeline. If a design cannot meet the 10.0110 standards, the application also picks up the variance criteria in Section 10.1500.

Renting an ADU by the month or year is fine, but the code bans short stays outright: 'Accessory Dwellings shall not be used as short-term rentals (see Gresham Revised Code Article 9.56).' GRC 9.56 defines a short-term residential rental as a hosted homeshare or vacation home rental of up to 30 consecutive days and requires an annual city certificate of registration before anyone may advertise or operate one, so the ADU exclusion closes off that whole market rather than merely licensing it. For long-term tenancy the city's ADU handout states that an ADU 'can be rented out after the property owner attains a residential rental license,' the residential rental property license administered under GRC Article 9.55, which carries periodic inspection obligations. No minimum lease term, tenant-income test or primary-residence test attaches to the ADU itself, and Section 10.0100 says nothing about selling the ADU separately from the primary dwelling.