Portland ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Portland, Oregon means pulling a building permit from the local authority that issues it. ArchPermit tracks 16 source-cited requirements (9 required, the rest conditional) for this jurisdiction. Submittals go through Development Hub PDX (DevHub) online portal. These requirements were last reviewed June 22, 2026; confirm the exact forms and fees with the local permitting authority.
A source-cited checklist of what an ADU (accessory dwelling unit) permit package needs in City of Portland. Every item links to its authoritative source; items that vary are flagged to confirm locally.
ADUs must comply with the Oregon Residential Specialty Code (two-family dwellings) as modified by Portland's ADU Code Guide, and are capped at 800 sf (or 75% of the main home's living area, whichever is smaller). ADUs are NOT automatically by-right — if a zoning development standard isn't met, an Adjustment Review (~8–10 weeks) is required. A System Development Charge (SDC) waiver is available if the owner agrees not to use the ADU as a short-term rental for 10 years. Trade (electrical/plumbing/mechanical) permits are also required; electrical work must use a licensed contractor.
- Architectural Plansrequired
Scaled dimensioned floor plans showing demolished/existing/proposed walls, windows and doors, room-use labels, plumbing fixtures, furnace/water-heater location, and electrical fixtures, exhaust fans, and smoke & CO detectors. Single-line drawings are not accepted.
source · reviewed 2026-06-22 - Building Elevationsrequired
All exterior building elevations (normally three sides required).
source · reviewed 2026-06-22 - Building Permit Applicationrequired
The base BDS building/site-development permit application capturing site address, scope, contractor, applicant, and valuation.
source · reviewed 2026-06-22 - Building Section(s)required
Dimensioned section(s) showing typical wall/floor/ceiling/roof/foundation construction, ceiling heights, fire-rated separation assemblies between units, and any non-typical construction.
source · reviewed 2026-06-22 - Energy Conservation Informationrequired
Insulation R-values for ceiling, walls, and floors; storm-window locations or window U-values in the area of work.
source · reviewed 2026-06-22 - Site Plan (Plot Plan)required
Scaled plan showing property lines + dimensions, lot area, streets/easements, address & R-number, north arrow, grade elevations at corners, building separations/setbacks, existing + proposed building and paving, sewer/water lines, stormwater disposal, and major geographic features.
source · reviewed 2026-06-22 - Stair Detailsrequired
Dimensions for risers, treads, headroom clearance, and guardrails/handrails.
source · reviewed 2026-06-22 - Utility Functioning & Separation Informationrequired
Documentation of how plumbing, mechanical, and electrical systems function and are separated between the two units.
source · reviewed 2026-06-22 - W-3 Water Meter Sizing Worksheetrequired
Completed Portland Water Bureau small-meter sizing worksheet used to size the water service.
source · reviewed 2026-06-22 - Erosion Control Planconditional
Required (may be part of the site plan) if the project results in ground disturbance.
source · reviewed 2026-06-22 - Major Residential Alteration & Addition (MRAA) Formconditional
Required when adding a new story/basement, replacing ≥50% of exterior wall area on a floor, adding >800 sf of floor area, or adding area exceeding 100% of the existing footprint; triggers a neighborhood-notice process.
source · reviewed 2026-06-22 - Residential SDC Formconditional
The one-and-two-family System Development Charge form, submitted with the building permit when SDCs apply.
source · reviewed 2026-06-22 - Stormwater Plan and/or Mitigation Formconditional
Required if the project adds more than 500 sf of impervious area.
source · reviewed 2026-06-22 - Structural Calculations (stamped)conditional
Calculations stamped by the architect/engineer of record with a design summary demonstrating the load path to the foundation; required when engineering is involved.
source · reviewed 2026-06-22 - Structural Plansconditional
Scaled framing/structural sheets, required when walls/beams/supports are removed or altered (e.g. basement/garage/attic conversions).
source · reviewed 2026-06-22 - Tree Preservation / Planting Planconditional
Required (may be part of the site plan) for new development on sites ≥5,000 sf and for ground-disturbing additions/alterations.
source · reviewed 2026-06-22