Accessory Dwelling Units (ADUs, SB391)


On August 29, 2023, the Board of County Commissioners passed Ordinance 23-05 to allow ADUs on Rural Residential zoned properties in the rural areas of Lane County. The approved Ordinance can be viewed here. The application form to apply for an ADU can be found here.

SB 391 - Background

On June 23, 2021, Governor Kate Brown signed Senate Bill (SB) 391 into Oregon law. This law allows rural accessory dwelling units (ADUs) in rural residential zoned areas, subject to certain conditions. More information about this is below.

The full text of the enrolled bill can be viewed here

Overview of the SB (not an exhaustive list; SB 391 includes some additional requirements):

Counties may allow one ADU on lands zoned rural residential if the following conditions are met:

  • The county adopts an ordinance to allow ADUs in rural residential zoned areas (lands subject to LC 16.290, but not lands subject to LC 16.231)
  • The lot or parcel is at least two (2) acres in size
  • One single family dwelling is sited on the lot or parcel
  • The lot or parcel is served by a fire protection service provider
  • Complies with all applicable state laws relating to sanitation and wastewater disposal
  • Limited to 900 square feet of useable floor space
  • Within 100 feet of the existing single family dwelling
  • The lot or parcel and ADU comply with rules of the State Board of Forestry under ORS 477.015 to 477.061 and Oregon residential specialty code relating to wildfire hazard mitigation


  • Cannot be utilized for vacation occupancy
  • The ADU cannot be separated from the primary dwelling by land division
  • Are not allowed in urban reserves
  • More than one ADU on a lot or parcel

Required development standards (these land use regulations must be adopted by the County):

  • Adequate setbacks from adjacent lands zoned for resource use
  • Adequate access for firefighting equipment, safe evacuation and staged evacuation areas
  • Adequate defensible space and fuel break standards where the ADU is not subject to ORS 477
  • Other criteria or standards that may be adopted by the County

County Process and Implementation:

  1. A county must decide whether to allow ADUs or not. If yes, then the Board of County Commissioners (“Board”) must adopt an ordinance to allow ADUs in Lane County Code. 
  2. The Board will decide if they would like to adopt the text of the bill as is, or if they would like to modify certain provisions. This bill allows counties to place additional conditions (be more restrictive) than the law.
  3. If the Board would like to develop and adopt additional local standards, they will need to provide policy guidance for staff to develop the local standards.
  4. Once the Board decides whether to adopt the bill as is or with additional local standards, the public hearing process to adopt the law into Lane County Code will begin. Draft code will be presented to the Lane County Planning Commission and the Board of Commissioners to consider adopting ADU provisions.

Staff Contact: 
For questions about establishing an ADU, please contact our Planner-on-Duty line at 541-682-3577 or visit our office in person at 3050 N Delta Hwy, Eugene, OR on weekdays between 9:00 a.m. and 3:00 p.m.