Permit Required? Required
Typical Fee Range $2,500–$7,500 SDC waivers available for units restricted from Short-Term Rental use (2026 rules).
Fee Method Valuation-based
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What's Required in Portland

  • ADUs are allowed on most residential lots citywide (Attached or Detached).
  • Maximum size of 800 sq ft or 75% of the primary dwelling (whichever is less).
  • Must have independent kitchen, bathroom, and a separate entrance.
  • System Development Charge (SDC) waivers apply if unit is not used as an AIRBNB for 10 years.
  • Must maintain 5-foot setbacks from side and rear property lines.
  • No additional off-street parking is required for ADU units in Portland.

How to Get a ADU Permit in Portland

1

Step 1: Check SDC Waiver Eligibility

Verify if you can bypass $10k+ in impact fees by agreeing to rental restrictions.

2

Step 2: Professional Plans

Hire an architect to prepare detailed structural, site, and MEP plans.

3

Step 3: DevHub Submission

Submit 'Residential New Construction' application via Development Hub PDX.

4

Step 4: Fee Payment

Pay the permit and plan check fees ($2,500+ typical without waivers).

5

Step 5: Full Inspection Series

Complete all sequence inspections (Foundation to Final).

Frequently Asked Questions

Yes, detached accessory dwellings are allowed citywide on qualifying residential lots.
City fees typically range from $2,500 to $7,500 depending on SDC waiver status.
It is a program where the city waives 'System Development Charges' in exchange for long-term housing use.