Accessory Dwelling Units

Background: The City of Edmonds currently allows each house to have an “accessory dwelling” (a small, additional living unit) on a residential lot if it is attached to or part of the main house.  Some cities also allow homeowners the option to have a “detached” accessory dwelling (also known as a “backyard cottage”) instead of an attached unit.  Whether attached or detached, the accessory dwelling must meet community standards for size, lot placement, ownership, parking, etc.


Example attached accessory dwelling unit

Example dettached accessory dwelling unit

Note: Allowing the option for detached accessory dwelling units in Edmonds would require a zoning code amendment, which includes a public process.

Policy Ideas

  • Detached Accessory Dwelling Unit: Allow one [1] attached or detached accessory dwelling per property, where it is associated with a primary (main) dwelling, in a single-family residential zone.

  • Accessory Dwelling Unit Permitting: Allow accessory dwellings to be approved through the standard permit process if all requirements are met. Currently, accessory dwelling units require a special “conditional use” permit.

  • Example Detached Accessory Dwelling Designs: Develop examples of detached accessory dwelling designs that would help homeowners who want to plan for such a unit.

  • Criteria for Accessory Dwelling Units: Require that each accessory dwelling meet City criteria for the following:

  1. Maximum size of 800 square feet or no more than 50% of the primary dwelling’s floor area, whichever is less

  2. Appearance that is compatible with the primary house on the property

  3. Height of 15 feet or less for a separate backyard cottage and up to the normal maximum for single-family houses (25 feet) for accessory dwellings that are part of the primary house or comprise a second story on a detached garage

  4. Property setback standards as for primary dwelling, except maybe closer to abutting alley

  5. At least one on-site vehicle parking space for the accessory dwelling (in addition to the required parking spaces for the primary dwelling)

  6. Owner occupancy (so that the property owner lives in either the primary or accessory dwelling most of the year)