ADU rules in Oregon
Representative cities: Portland, Eugene.
ADU permit rule
Permit requiredGenerally allowedcity authority
Fee basis
Valuation-based building + trade permits per the local fee schedule.
Typical timeline
Plan review; Portland and other cities review ADUs under standard residential review (weeks).
Setback
Per local zoning; state law sets minimum allowances for ADUs in single-family zones.
Area threshold
Oregon HB 2001 requires most cities to allow ADUs in single-family zones (size/number set locally).
Exempt if
None — an ADU always requires a building permit.
Go / no-go
allowed
Oregon’s HB 2001 (2019) requires cities (generally those over 10,000 population) to allow accessory dwelling units in single-family zones, so ADUs are broadly permitted statewide. Local zoning still sets size, setbacks, parking, and owner-occupancy rules — verify with your city.
ADU official sources: Oregon BCD — About Oregon Residential Building Permits · Oregon BCD — 2023 ORSC Update Resources
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Frequently asked questions
Do I need a permit to build an ADU in Oregon?
Per Oregon rules, an ADU is "yes" for a permit and the authority is "city". Oregon’s HB 2001 (2019) requires cities (generally those over 10,000 population) to allow accessory dwelling units in single-family zones, so ADUs are broadly permitted statewide. Local zoning still sets size, setbacks, parking, and owner-occupancy rules — verify with your city. Always confirm with the issuing building department.
How big can an ADU be in Oregon?
Area threshold: Oregon HB 2001 requires most cities to allow ADUs in single-family zones (size/number set locally).
What are the ADU setbacks in Oregon?
Setback: Per local zoning; state law sets minimum allowances for ADUs in single-family zones.
How much does an ADU permit cost in Oregon?
Fee basis: Valuation-based building + trade permits per the local fee schedule.