Unofficial mirror of portland.gov/ppd. Always verify with the official source. View original ↗

Accessory dwelling unit (ADU) zoning requirements

← Permitting & Development

Breadcrumb: Home > Permitting & Development > Accessory dwelling unit (ADU) zoning requirements

Source: Accessory dwelling unit (ADU) zoning requirements ↗ Last modified: Sun, 19 Apr 2026 19:57:44 GMT

Definition of an accessory dwelling unit (ADU)

The Portland Zoning Code defines an accessory dwelling unit (ADU) as a smaller home on the same lot as the main one.

An ADU must include independent living facilities with provisions for:

  • Living
  • Cooking
  • Eating
  • Sleeping
  • Sanitation (bathroom)

ADUs allow for residential occupancy, independent of the main unit. The unit may feature:

  • A separate exterior entrance
  • An entrance to an internal common area that is accessible from the outside.

Benefits of ADUs

ADUs offer many advantages.

  • Provide more housing units that fit well with single-dwelling developments.
  • Make more efficient use of existing housing stock and infrastructure.
  • Offer a mix of housing options.

Ways to create an ADU

  • Convert part of an existing primary structure.
  • Add to an existing primary structure.
  • Convert an existing accessory structure.
  • Construct a new detached building.

"Detached" means stand-alone or separate and not connected by a roof or deck or other element.

Portland zoning rules for ADUs

Under the Portland Zoning Code, ADUs can be:

  • Accessory to a house
  • Located within a house
  • Proposed as a manufactured home
  • Detached and accessory to a duplex

Visit Chapter 33.205 of the Portland Zoning Code ↗ for all ADU zoning requirements.

Zoning for detached ADUs

  • Use the Detached Covered Accessory Structures Worksheet. It will show the zoning rules for your project.

Detached ADUs on different property types

Different property types (base zones) have different rules for detached ADUs.

You can have a detached ADU in the following zones:

Find the base zone of your property on the Portland Zoning App ↗.