Portland ADU Rules & Requirements (2026)

Portland ADU rules at a glance

Portland was an early ADU pioneer and maintains one of the most developer-friendly regimes in the country. The city allows both Type A (attached) and Type B (detached) ADUs on nearly all residential lots. Detached ADUs are capped at 800 sq ft or 75% of the primary dwelling's area, whichever is less. Side and rear setbacks are 5 feet, and the height limit is 20 feet (25 feet if matching the primary roof pitch).

Parking minimums were eliminated citywide in 2018, and Oregon HB 2001 (2019) preempted local owner-occupancy requirements. Portland uses Type I ministerial review, meaning the Bureau of Development Services cannot deny a compliant application based on discretionary design concerns. Combined plan review typically runs 6 to 12 weeks.

SDC waivers matter

Portland's largest ADU-specific benefit is its System Development Charge (SDC) waiver program. If you deed-restrict the ADU against short-term rental use (< 30-day stays), the city waives transportation, water, sewer, and parks SDCs — saving roughly $12,000 to $18,000 in soft costs. ADUs used for STR pay the full SDC schedule.

Type A vs Type B ADUs

Type A ADUs are attached — a converted basement, garage, or addition that shares at least one wall with the primary residence. Type B ADUs are detached — standalone cottages in the back yard. Portland does not recognize JADUs the way California does; an internal conversion is simply a Type A ADU with its own entrance, kitchen, and bath.

What Portland does allow

Unlike most California cities, Portland explicitly allows ADUs to be operated as short-term rentals — you just forgo the SDC waiver. Two ADUs per lot are possible in some zones where one Type A and one Type B configuration is permitted.