A building permit is required to build an accessory dwelling unit. Depending on the scope of work, your project will most likely also require electrical, plumbing and/or mechanical permits. For new construction, your permit will be reviewed under provisions of the current Oregon Residential Specialty Code. View more information on building codes
It is recommended that you visit the Development Services Center to talk with staff about your project while in the planning stages. Staff can help you determine if an ADU is allowed on your property and to discuss zoning standards that are applicable to your project. They can also help answer questions about the building code and applicable construction standards, and utilities.
Property taxes are not assessed or collected by the City of Portland. It is recommended that applicants consult their county assessment and taxation office to determine how property taxes may be affected by the addition of an ADU to the property. The Multnomah County tax assessor's customer service line is 503-988-3326 or visit their website at https://multco.us/assessment-taxation/news/are-you-considering-building-accessory-dwelling-unit for more information.