ZDO 839: Accessory Dwelling Units

839.01 Standards Inside an Urban Growth Boundary Or Unincorporated Community

Accessory dwelling units inside an urban growth boundary or unincorporated community shall comply with the following standards:

1. Only one accessory dwelling unit shall be allowed per detached single-family dwelling or manufactured dwelling.
2. No accessory dwelling unit shall be allowed in a cottage cluster development, or in a manufactured dwelling park, or accessory to a temporary dwelling approved pursuant to Section 1204, Temporary Permits.
3. In the R-2.5 and VTH Districts, only one accessory dwelling unit shall be allowed per townhouse.
4. The maximum floor area of an accessory dwelling unit shall be:
   1. 500 square feet in the R-2.5 District; and
   2. 900 square feet in all other zoning districts except the VR-4/5, VR-5/7, and VTH Districts.
5. When calculating floor area, all contiguous space in a building shall be included except:
   1. A primary dwelling unit;
   2. Space that is separated from the accessory dwelling unit with a wall that does not contain a door; and
   3. Space that is separated from the accessory dwelling unit with a wall that contains a door, if the door provides access only to unconditioned space (i.e., with no heating or cooling) that is provided with no plumbing.

839.02 Standards in the VR-4/5 And VR-5/7 Districts

In the VR-4/5 and VR-5/7 Districts, accessory dwelling units shall comply with the following standards:

1. An accessory dwelling unit either may be located above a detached garage, or it may be integral to a primary dwelling.
2. If the accessory dwelling unit is located above a detached garage:
   1. The maximum floor area of the accessory dwelling unit shall be 900 square feet. When calculating floor area, all contiguous space in a building shall be included except:
      1. A primary dwelling unit;
      2. Space that is separated from the accessory dwelling unit with a wall that does not contain a door; and
      3. Space that is separated from the accessory dwelling unit with a wall that contains a door, if the door provides access only to unconditioned space (i.e., with no heating or cooling) that is provided with no plumbing.       
   2. The accessory dwelling unit shall be subject to the standards in Table 315-3, Dimensional and Building Design Standards in the VR-5/7, VR-4/5, and VTH Districts, that apply to accessory structures in the VR-4/5 and VR-5/7 Districts.
3. If the accessory dwelling unit is integral to a primary dwelling, it shall be subject to the standards in Table 315-3 that apply to primary dwellings in the VR-4/5 and VR-5/7 Districts.

839.03 Standards int eh VTH District

In the VTH District, accessory dwelling units shall comply with the following standards:

1. An accessory dwelling unit either may be located above a detached garage, or it may be integral to a primary dwelling.
   1. The maximum floor area of the accessory dwelling unit shall be 500 square feet. When calculating floor area, all contiguous space in a building shall be included except:
      1. A primary dwelling unit;
      2. Space that is separated from the accessory dwelling unit with a wall that does not contain a door; and
      3. Space that is separated from the accessory dwelling unit with a wall that contains a door, if the door provides access only to unconditioned space (i.e., with no heating or cooling) that is provided with no plumbing.
   2. The accessory dwelling unit shall be subject to the dimensional standards in Table 315-3, Dimensional and Building Design Standards in the VR-5/7, VR-4/5, and VTH Districts, that apply to accessory structures in the VTH District.
2. If the accessory dwelling unit is integral to a primary dwelling, it shall be subject to the standards in Table 315-3 that apply to primary dwellings in the VTH District and to Subsection 1005.11(A).

839.04 Standards Outside An Urban Growth Boundary And Unincorporated Community

Accessory dwelling units outside both an urban growth boundary and an unincorporated community shall comply with the following standards:

1. Only one accessory dwelling unit shall be allowed per lot of record.
2. The lot of record on which the accessory dwelling unit will be sited shall:
   1. Be a minimum of two acres;
   2. Contain one, and only one, detached single-family dwelling, prefabricated structure, or manufactured dwelling;
   3. Not contain any other dwelling, including, but not limited to, dwellings approved pursuant to Section 846, Recreational Vehicles as Second Dwellings, or Section 1204, Temporary Permits;
   4. Not contain a guest house;
   5. Be served by a fire protection service provider with professionals who have received training or certification described in Oregon Revised Statutes (ORS) 181A.410.
3. The primary dwelling on the lot of record shall not be subject to an order declaring it a nuisance or subject to any pending action under ORS 105.550 to 105.600.
4. The accessory dwelling unit shall comply with the following standards:
   1. Maximum Floor Area: The floor area of the accessory dwelling unit shall not exceed 900 square feet. When calculating floor area, all contiguous space in a building shall be included except:
      1. A primary dwelling unit;
      2. Space that is separated from the accessory dwelling unit with a wall that does not contain a door; and
      3. Space that is separated from the accessory dwelling unit with a wall that contains a door, if the door provides access only to unconditioned space (i.e., with no heating or cooling) that is provided with no plumbing.
   2. Maximum Separation Distance: The accessory dwelling unit shall be located within 100 feet of the primary dwelling. This distance shall be measured from the closest portion of each structure.
   3. Minimum Setbacks: The accessory dwelling unit shall comply with the minimum setback standards for primary dwellings in the applicable zoning district.
   4. Access: Adequate access shall be provided for firefighting equipment, safe evacuation, and staged evacuation areas. Access shall be considered "adequate" if, prior to approval of an onsite wastewater treatment, building, or manufactured dwelling placement permit for the accessory dwelling unit, documentation is submitted from the fire protection service provider acknowledging compliance with the provider's access standards.
   5. Wildfire Hazard Mitigation:
      1. The construction provisions of Section R327 of the Oregon Residential Specialty Code shall apply to:
         1. All accessory dwelling units, if the Statewide Wildfire Hazard Map described in ORS 477.490 has not been approved.
         2. Accessory dwelling units only in areas designated as high wildfire hazard, identified pursuant to ORS 477.490, if the Statewide Wildfire Hazard Map described in ORS 477.490 has been approved.
      2. Minimum defensible space rules established by the State Fire Marshal, as described in ORS 476.392, shall apply to accessory dwelling units located in areas designated as wildland-urban interface, identified pursuant to ORS 477.490, if the Statewide Wildfire Hazard Map described in ORS 477.490 has been approved.
5. Use of the accessory dwelling unit as a short-term rental is prohibited.
6. The placement or construction of any additional dwellings, or of a guest house, is prohibited on any lot of record developed with an accessory dwelling unit approved pursuant to Subsection 839.04.

[Added by Ord. ZDO-249, 10/13/2014; Amended by Ord. ZDO-250, 10/13/2014; Amended by Ord. ZDO-269, 9/6/2018; Amended by Ord. ZDO-276, 10/1/2020; Amended by Ord. ZDO-282, 7/1/2022; Amended by Ord. ZDO-283, 9/5/2023; Amended by Ord. ZDO-285, 9/3/2024