ADU Services

Frequently Asked Questions

  • What does an ADU Cost to build?

    Every ADU is different. ADU’s can cost anywhere from $80,000 to $250,000. Call us for an estimate if you would like to learn more.

  • Where can I build an ADU?

    ADUs are allowed on sites that are zoned Residential, Commercial, and in the Central Employment (EX) zone and can be created accessory to a house (detached single family dwelling), an attached house (rowhouse) or a manufactured home. ADUs are not allowed with other development types (eg duplexes) and only one ADU is allowed per site. An ADU is also not allowed with an attached house using the provision for attached houses on corners in 33.110.240.E.

  • What is the definition of a ADU?

    The Zoning Code defines an Accessory Dwelling Unit as a smaller, auxiliary dwelling unit on the same lot or within a house, attached house or manufactured home. The unit includes its own independent living facilities with provisions for sleeping, cooking, and sanitation, designed for residential occupancy independent of the primary dwelling unit. The unit may have a separate exterior entrance or an entrance to an internal common area accessible to the outside.

  • Do either the primary home or the ADU have to be owner inhabited?


  • Do I need to offer parking for my ADU?

    Additional on-site parking is not required for an ADU. However, if parking is required for the existing dwelling unit, that parking must either be retained or replaced on-site. Any replacement parking must meet the parking standards in Chapter 33.266 of the Portland Zoning Code.

  • What are the setback requirements for my ADU?

    According to the city of Portland, a detached ADUs must be set back 60 feet from the front lot line or 6 feet behind the house.

  • Just how much area can my separated ADU use?

    No greater than 15% of the overall site location.

  • What is the max size an ADU can be?

    The optimum size is no more than 75% of the living location of your house or 800sf, whichever is less.

  • How high can my ADU be?

    No greater than 18 feet high.

  • Is now a great time to develop an ADU in Portland?

    Yes. The City of Portland is waiving system advancement charges (SDCs) for ADU tasks whose structure authorization application is sent prior to July 31, 2018 (offered that tenancy starts prior to June 30, 2019). This is a huge offer, as the expense of SDCs can quickly reach 5 figures.

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