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 to 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
Portland ADU permit questions
- Do I need a permit to build an ADU in Portland?
- Yes. An accessory dwelling unit (ADU) in Portland requires a building permit. ArchPermit tracks 16 cited requirements for this jurisdiction (9 required, the rest conditional). Always confirm the exact forms, fees, and code edition with the local permitting authority that issues the permit.
- What does an ADU permit package require in Portland?
- Core required items include: Architectural Plans; Building Elevations; Building Permit Application; Building Section(s); Energy Conservation Information; Site Plan (Plot Plan), plus 3 more. Each requirement links to its authoritative source, and nothing is permit-ready until an independent licensed professional reviews and seals it.
- How are ADU permits submitted in Portland?
- Portland accepts permit submittals via Development Hub PDX (DevHub) online portal. ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.