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Accessory Dwelling Units (ADUs) are booming in Portland, Oregon. ADUs are small separate living units on single family lots that are often called granny flats or mother-in-law units. Over the last few years, fee waivers from the City of Portland have increased ADU development from 30 units per year to over 200 units. These discreet forms of density can offer a variety of environmental, social, and economic benefits to ADU owners and their communities. Many of these benefits, however, have always been speculated rather than substantiated by data.

In an effort to better understand the real impact or benefit of this housing form, the Oregon Department of Environmental Quality and partners conducted a survey of ADU owners in Portland, Eugene, and Ashland, Oregon. This was the largest survey of ADUs owners ever conducted in the United States and the results have significant utility in policy for Oregon cities and beyond.

This presentation will present the results of survey and highlight topics such as ADU affordability, environmental impact, occupant demographics, owner demographics, community economic impact, and car ownership and parking statistics. Attendees will gain knowledge of ADU development trends and learn about how ADUs contribute to our communities.

Biographical Information

Jordan Palmeri is a Science and Policy Analyst with the Oregon Department of Environmental Quality Green Building Program.


Neighborhood planning -- Oregon -- Portland, Community development -- Oregon -- Portland, City planning -- Oregon -- Portland, Infill housing -- Oregon -- Portland


Urban Studies | Urban Studies and Planning

Persistent Identifier

Accessory Dwelling Units in Portland, Oregon: Evaluation and Interpretation of a Survey of ADU Owners