Oregon residential & ADU permit data

Oregon was an early mover on statewide accessory dwelling units and remains one of the most permissive states. Senate Bill 1051 (2017) required cities with more than 2,500 residents and counties with more than 15,000 to allow at least one ADU on each lot with a detached single-family home inside an urban growth boundary, subject only to reasonable siting and design standards; a follow-up, HB 4031, corrected a drafting error to keep the requirement tied to urban growth boundaries.

House Bill 2001 (2019), best known for legalizing 'missing middle' housing, also sharpened the ADU rules. It bars cities over 2,500 from imposing off-street-parking mandates or owner-occupancy conditions on ADUs — the two requirements that most often make a backyard unit infeasible. The ADU duty is now codified in ORS 197.312, and cities had to bring their codes into compliance by 2020. The practical effect across Oregon's urban areas is that a homeowner can add a rental ADU without providing a new parking space and without living on site, whether the unit is a conversion, an attached addition or a detached cottage.

HB 2001 layered middle housing on top of that ADU baseline. Cities of 10,000 or more and the Portland metro must allow duplexes, triplexes, fourplexes, townhouses and cottage clusters in areas previously zoned single-family, while mid-size cities of 2,500 to 10,000 must at least allow duplexes — so many lots can host both a middle-housing building and an ADU. A later law, SB 458, made it easier to divide middle-housing lots so the units can be sold individually.

Oregon's approach is notably cleaner than its neighbors': unlike Washington's later HB 1337, which scales ADU counts and parking caps by lot size and transit proximity, Oregon set a simpler statewide floor years earlier, and unlike most states it ties everything to the urban-growth-boundary system rather than to raw population thresholds alone. Igni tracks live Portland permit data sourced from the city's PortlandMaps open-data portal, so new ADU and middle-housing activity surfaces as soon as it is permitted.

This is an informational summary, not legal advice; cities may add design and siting standards within the statutory limits, so verify the current state statute and your local code before relying on it.