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The City of Portland, Oregon

Development Services

From Concept to Construction

Phone: 503-823-7300

Email: bds@portlandoregon.gov

1900 SW 4th Ave, Portland, OR 97201

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Accessory Dwelling Units (ADUs)

You will find information on this page about adding an accessory dwelling unit to a property. Every dwelling unit functions as a separate unit. They are commonly known as "mother-in-law apartments", "granny-flats" or studio apartments.

An accessory dwelling unit (ADU) is a second dwelling unit created on a lot with a house, attached house or manufactured home. The second unit is created auxiliary to, and is smaller than, the main dwelling. ADUs can be created in a variety of ways, including conversion of a portion of an existing house, addition to an existing house, conversion of an existing garage or the construction of an entirely new building.