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Here is Accessory Dwelling Unit Zoning Codes from a range of cities that allow ADUs; the spreadsheet includes summaries of facets of the respective regulations.
If you’re willing to add to this dataset for your state, please contact us.
For more in depth information on Portland’s ADU regulations, review the following information. An introduction to the rules governing ADUs in Portland, OR is contained in this on-line guide. Among its more helpful links are:
Portland also allows accessory structures, some permitted and some not, that don’t qualify as separate dwelling units yet often have attributes similar to ADUs. For a table-format summary of codes related to these other structures, check out this Accessory Structure (Informal) Code Guide.
In 2003, Portland reviewed its ADU regulations and came up with recommended program changes to better meet the public policy objectives of the program. This Accessory Dwelling Unit Monitoring Project report contains lots of good information, including case studies and images of built ADUs.