Can I Build ADU in Portland, OR? (2026)
Find out if you can build a adu in Portland, OR. Rules, permit requirements, costs, and next steps.
Yes, ADUs are allowed in Portland, OR. California state law ensures by-right approval.
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a residential lot — also called a granny flat, in-law suite, or backyard cottage. In Portland, OR, ADUs are permitted by right under state law, making them one of the most accessible ways to add housing on your property. ADUs can be detached, attached to the main home, or created by converting an existing garage or accessory structure.
ADU Rules in Portland
ADU Rules in Portland: Detached ADU max size: 800 sq ft. Attached ADU max size: 75% of primary dwelling up to 800 sqft. Setbacks: 5 ft side, 5 ft rear. Owner-occupancy: Oregon HB 2001 (2019) prohibits local owner-occupancy requirements for ADUs in Oregon cities with population 10,000+. Portland eliminated its own owner-occupancy requirement in 2016. Neither the primary dwelling nor the ADU is required to be owner-occupied. Short-term rental of an ADU has separate permit requirements.. State preemption applies: OR law requires Portland to approve compliant ADUs by right.
Costs & Fees
ADU permits in Portland: Total estimated permit cost: $3,000–$8,000 in permit fees plus system development charges. Contact the Portland Bureau of Development Services (BDS) for current fee schedule.
Timeline
Portland BDS (Bureau of Development Services) processes ADU permits ministerially. Standard ADU: 4-8 weeks plan review. Pre-approved standard plan sets available from BDS reducing review time. Construction typically 3-9 months. Permits expire if construction not started within 2 years.
Next Steps
Next steps for building an ADU in Portland: 1. Review full ADU rules including size limits, setbacks, and parking. 2. Apply for an ADU permit through the Portland Bureau of Development Services (BDS) at https://www.portland.gov/bds/permits-applications. 3. Hire a licensed contractor familiar with OR ADU requirements.
Portland Bureau of Development Services (BDS)
Phone: (503) 823-7300
Website: https://www.portland.gov/bds
Online Permits: https://www.portland.gov/bds/permits-applications
Frequently Asked Questions
Can I build an ADU in Portland?
Yes. Portland is one of the most ADU-friendly cities in the US. You can build a detached ADU up to 800 sqft in your backyard or an attached ADU up to 75% of your primary home's size (max 800 sqft). Oregon HB 2001 (2019) preempts local restrictions, and Portland eliminated owner-occupancy requirements in 2016. No additional parking is required. A building permit from Portland BDS is required.
What is the difference between Portland's middle housing and ADU rules?
Portland's middle housing rules (implementing Oregon HB 2001) allow duplexes, triplexes, fourplexes, cottage clusters, and townhomes on any single-family lot by-right — these are full dwelling units. ADUs are accessory units added to a lot that already has a primary dwelling. You can combine both: for example, a duplex with an ADU in the backyard could allow up to 3 or more units on a single lot.
Do I need a permit for a home business in Portland?
Yes. A Home Occupation Permit (approximately $80) is required to operate a business from your Portland home. You may have limited client visits (up to 4 per week per business), up to 2 non-resident employees, and must not create external evidence of the business. Oregon also allows cottage food operations (baked goods, jams, etc.) with registration from the Oregon Department of Agriculture.
Can I do Airbnb in Portland?
Yes, with a permit. Portland requires a Short-Term Rental Permit (Type A or B). Type A allows renting your primary residence including entire home when you are away. Annual fee starts at $178. You must display your permit number on listing platforms. Portland collects Transient Lodging Tax (currently 11.5%) — Airbnb remits this automatically. Operating without a permit carries fines up to $500/day.
What are the setbacks in Portland's R5 zone?
In Portland's R5 zone (one of the most common single-family zones), the front setback is 10 feet, side setbacks are 5 feet on each side, and the rear setback is 5 feet. R5 allows up to 50% lot coverage and buildings up to 30 feet tall (2 stories). Verify your specific parcel at PortlandMaps.com — overlay zones, historic districts, or environmental overlays may add additional requirements.
Is solar required on new homes in Portland?
No. Oregon does not have a statewide new-construction solar mandate like California. Solar is encouraged and Portland offers expedited solar permits, but it is not required. The Oregon Residential Energy Tax Credit provides financial incentives for solar installation. Portland General Electric (PGE) and Pacific Power both offer net metering programs.
How do I look up the zoning for my Portland property?
Use PortlandMaps at portlandmaps.com. Enter your address to find your zone designation, overlay zones, flood zone status, historic designation, environmental overlay, and other land use information. Portland Maps is the official City of Portland resource and is regularly updated. You can also contact Portland BDS at (503) 823-7300 or visit the permit center at 1900 SW 4th Ave.
Source: Portland Bureau of Development Services (BDS) — Building Regulations. Last verified April 5, 2026. View source