Do I Need a Permit to Build an ADU in Portland, OR?

ADU-specific overview

What makes this different from a simple accessory structure

Pulled from the city's ADU guidance and linked code references.

Permit type: Residential building permit through Portland Bureau of Development Services (BDS). Attached and detached ADUs both follow the residential permit path under Title 33.205.
Maximum size: 800 square feet of living area or 75% of the living area of the primary dwelling, whichever is less. Garage and storage areas are excluded from the size calculation.
Setbacks: Detached ADU: rear setback of 5 feet; side setbacks per base zone (typically 3–5 feet depending on the zone). Front setback must meet the standard zone requirement. No minimum separation from the primary dwelling. Attached ADU follows the primary structure's setback.
Owner occupancy: No owner-occupancy requirement. Portland removed this requirement in 2018. Oregon HB 2001 (2019) further prohibits cities from requiring owner occupancy as a condition for ADU approval.
Parking: No additional parking required for an ADU. Portland eliminated its ADU parking requirement prior to statewide mandate.
Utilities: ADU may share utilities with the primary dwelling or have separate connections. A new water or sewer connection triggers Portland Water Bureau or Bureau of Environmental Services fees. Separate metering is common but not universally required.
JADU distinction: Portland does not use a California-style Junior ADU (JADU) designation. Smaller ADUs created within existing single-family space are simply Attached ADUs under Title 33.205 and do not follow a separate junior-unit track.

Oregon HB 2001 (2019) mandated that cities with 10,000+ residents allow ADUs in all single-family zones — Portland was already ahead of this standard.
Portland's ADU SDC Waiver program can substantially reduce upfront costs; verify current availability and eligibility with BDS before applying.
Portland's middle-housing policies and ADU program are among the most permissive in the country, shaped by years of incremental reform pre-dating HB 2001.

Fees

Estimated city fees

Baseline for a simple permitted adu: Portland BDS permit and plan review fees are valuation-based. A new detached ADU valued at $150,000–$250,000 commonly generates $2,000–$5,000+ in combined permit and plan review fees before SDC waiver. Verify with Portland BDS.

Fee	Amount	Notes
Building permit fee	Valuation-based	Portland BDS charges building permit fees based on declared construction valuation. Use the Portland BDS permit fee schedule at portland.gov/bds for current amounts.
Plan review fee	Valuation-based	A plan review fee is charged separately from the building permit fee. Portland BDS calculates this based on project valuation and type.
System Development Charges (SDCs)	Potentially waived for qualifying ADUs	Portland offers an ADU SDC Waiver program. SDCs can otherwise be significant for new dwelling units. Confirm current waiver availability and eligibility with Portland BDS at application.
Oregon Building Codes Division surcharge	1% of permit fee	A state surcharge of 1% of the permit fee is collected by Portland and remitted to the Oregon Building Codes Division on residential permits.
Utility connection fees	Project-specific	A separate water, sewer, or utility connection for the ADU may trigger Portland Water Bureau or Bureau of Environmental Services fees.

Documents

Required documents

Completed building permit application submitted through Portland's Development Hub (ePlans).
Site plan showing lot dimensions, existing dwelling, proposed ADU footprint, setbacks, impervious surfaces, and utility lines.
Architectural plans including floor plans, elevations, cross sections, and roof plan.
Structural plans or engineering calculations for elements beyond prescriptive code.
Oregon Energy Efficiency Specialty Code (OEESC) compliance documentation.
Stormwater management plan if the project adds impervious surface above Portland's threshold.
SDC Waiver application if claiming the ADU System Development Charge waiver.
Contractor's Oregon Construction Contractors Board (CCB) license number if a contractor is performing permitted work.

Timeline

Typical timing

Plan review: 4–8 weeks for standard plan review; over-the-counter review may be available for simple attached ADU conversions
Total cycle: 8–20 weeks typical from submittal to permit issuance; total project time including construction and inspections varies widely

Correction rounds, SDC waiver processing, and utility coordination can extend the timeline. Portland BDS posts current plan review queue times on its website.

Process

How the permit process works

Confirm zoning and lot eligibility Use Portland Maps (portlandmaps.com) to verify the parcel zone. ADUs are allowed by right in all single-dwelling and applicable multi-dwelling residential zones under Title 33.205 and Oregon HB 2001.
Determine ADU type and design parameters Decide between an attached ADU (conversion or addition to the primary structure) or a detached ADU (separate structure). Confirm the proposed size is within Portland's 800 sqft or 75%-of-primary-unit limit and meets setback standards.
Prepare permit package Assemble site plan, architectural drawings, structural documents, energy code compliance, and any stormwater materials. Portland BDS provides guidance documents and pre-application resources on its ADU page.
Apply for SDC waiver (if applicable) If claiming the ADU System Development Charge waiver, submit the SDC Waiver application to Portland BDS alongside or before the building permit application. Confirm current waiver availability.
Submit through Portland Development Hub (ePlans) File the building permit application and upload plans through Portland's online permit portal. Pay the plan review deposit at intake.
Respond to plan review corrections Portland BDS reviewers will issue correction notices if the plans need changes for zoning, structural, energy, or stormwater compliance. Address each correction promptly to advance the application.
Pay remaining fees and issue the permit After plan approval, pay the remaining permit fees. Portland BDS issues the permit; post it at the job site before construction begins.
Complete inspections and obtain occupancy Schedule required inspections (footing, framing, insulation, mechanical, final) through Portland's permit portal. Once all inspections pass, Portland BDS finalizes the permit and the unit may be occupied.

Code basis

What Portland reviews against

Portland City Code Title 33 Chapter 33.205 (Accessory Dwelling Units), Oregon Residential Specialty Code (ORSC), Oregon Energy Efficiency Specialty Code (OEESC), and Oregon HB 2001 (2019) middle-housing mandate.

Residential permit page Portland permit portal

If you skip the permit

What can go wrong

Portland BDS can issue a Stop Work Order and require full after-the-fact permitting for any unpermitted ADU construction.
An unpermitted ADU cannot be lawfully occupied or rented; it lacks a Certificate of Occupancy.
After-the-fact permitting is more costly and may require opening finished walls or correcting non-compliant work before inspections can pass.
Code enforcement complaints can result in daily fines and liens under Portland City Code.
Title and financing complications arise when a property with an unpermitted dwelling unit is sold or refinanced.
Oregon CCB law requires a licensed contractor for permitted work done by a contractor; use of an unlicensed contractor creates additional legal exposure.

FAQ

Common Portland adu permit questions

Do I need a permit for an ADU in Portland, OR?

Yes. Any ADU — attached or detached — requires a residential building permit from Portland BDS. Portland's ADU rules under Title 33.205 treat the ADU as a separate dwelling unit, not as a simple accessory structure.

What is the maximum ADU size in Portland?

The Portland ADU size limit is 800 square feet of living area or 75% of the living area of the primary dwelling, whichever is less. Garage and storage spaces are not counted toward this limit.

Does Portland require the owner to live on site for an ADU?

No. Portland removed its owner-occupancy requirement for ADUs in 2018. Oregon HB 2001 (2019) also prohibits cities from using owner-occupancy as a condition of ADU approval.

What are the System Development Charges (SDCs) for an ADU in Portland?

Portland offers an ADU SDC Waiver program that can eliminate or reduce SDCs, which can otherwise amount to tens of thousands of dollars for a new dwelling unit. Verify current waiver availability and eligibility with Portland BDS before applying.

Does Portland require parking for an ADU?

No. Portland does not require additional off-street parking for an ADU. This was removed prior to the Oregon statewide mandate.

How long does an ADU permit take in Portland?

Standard plan review at Portland BDS typically takes 4–8 weeks. Total time from submittal to permit issuance is often 8–20 weeks. Correction rounds and SDC waiver processing can extend the timeline.

What does Oregon HB 2001 mean for Portland ADU owners?

HB 2001 (2019) requires all Oregon cities over 10,000 residents to allow ADUs by right in all areas that allow single-family housing, and prohibits owner-occupancy mandates and certain other local barriers. Portland was already ahead of most HB 2001 requirements before the law passed.

Sources

Official links and freshness

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