Residential Additions in Portland: Permits and Application Requirements

Get application requirements for a one or two-family home addition that builds up or builds out. Find documents and plans you'll need to apply for a permit.
On this page

Do you need a permit for an addition?

Yes, a building permit is required for an addition to one or two-family dwelling units. 

If you're making structural changes, like adding a dormer, a second floor, or expanding the footprint, you need a permit.

Depending on your project, you may also need an electrical permit, a mechanical permit, and a plumbing permit.

Your project needs to comply with zoning requirements. Find out what you can do on a site.

Permit application requirements for all additions

Use this table to determine what you need to provide with your application.

If the conditions listed in the left column are true about your project, then provide the application requirement listed in the right corresponding column.

We cannot issue permits for incomplete applications.

If the conditions are true about your projectThen include the application requirement
For all residential addition projects
Architectural plans (details in the plans and specifications section)
Site plan (details in the plans and specifications section)
Structural plans and calculations (details in the plans and specifications section)
If the owner is doing the work 
If there's electrical work 
If there's heating and cooling work
If there's plumbing work
If YES to electrical, mechanical, or plumbing work, also include:
If four or more bathrooms total are on the site (even if you're not adding new bathrooms)
If your project won't need calculations that demonstrate the lateral load meets codes (see criteria in the document)
If adding more than 500 square feet of space


If removing more than 50% of the existing exterior walls
Include the Major Residential Alteration and Additions (MRAA) requirements
If the site is in a Flood Hazard Area

Flood plain information is available on PortlandMaps Flood Hazard gallery

Contact Site Development for additional submittal requirements.


Phone: 503-823-7300

If the building is served by an on-site septic system (not connected to the public sewer) AND the project is adding a bedroom
If the building is served by an on-site septic system (not connected to the public sewer) and the project is NOT adding a bedroom. 
If the addition will add to the ground-floor level of the building (building out)Please see the table below, additions building out (adding footprint).

Additions building out (adding footprint)

If you plan to add to the ground-floor level of the building, there are additional requirements to include with your application. Expanding the building footprint can include stairs and decks.

In addition to the requirements listed above, please provide the following application requirements based on your project conditions.

If the conditions are true about your projectThen include the application requirement
If a cesspool or septic tank is on the site, but the building is now served by public sewer.

Submit this disclaimer or if your project is within 10 feet of a septic tank or cesspool you will need to have your septic tank decommissioned.

If more than 500 square feet of the ground will be disturbed AND if your site qualifies as a "simple site".

To qualify as a simple site, ALL of the following must be true: 

  • Area of work is flat, less than 10% slope prior to development
  • Less than 10,000 square feet of ground disturbance
  • More than 50 feet from a wetland or waterbody
  • Outside of an environmental, greenway, or river overlay zone
If more than 500 square feet of the ground will be disturbed


The site is complex. See the conditions for a simple site above. If any boxes are left unchecked, your site is complex.
Graphical erosion control plan
If the project is on a slope that is more than 20%;


If the property is in or near a Mapped Landslide Inventory Area;


If the proposed foundation design is non-prescriptive;


If the foundation is placed on more than 12 inches of fill.

Soil (Geotechnical) engineering report

Visit Chapter 24.70 Clearing, Grading, And Retaining Walls (24.70.050.A.9)

If your project will add more than 500 square feet of impervious area*

*Impervious area is the area of a property that does not allow rainwater to naturally drain or seep through into the ground. This can include paved areas.

Or a Storm Report from an Oregon-licensed engineer

For stormwater management policy and design requirements visit the Stormwater Management Manual.

Plans and specifications

Site plan checklist


 The site plan shows the whole property and the footprint of all structures and the driveway. Often called a "plot plan."

  • Site plans must be drawn to scale, e.g. 1 inch = 10 feet or 1/4 inch = 1 foot. The scale used must be clearly shown.
  • Show the entire lot
  • Clearly distinguish between existing conditions and proposed work
  • Must be in black and white (drawings may not contain color)
  • Line quality and contrast must be easy to read
  • Dimensions and notes must be 12 point font minimum
  • Not allowed: We will not accept photos or maps from Google Maps and PortlandMaps

All additions

  • Property lines, with dimensions
  • Total area of the lot in square feet
  • Adjacent streets and any easements
  • Property address and R number
  • North arrow (an arrow that shows the direction of north)
  • Grade elevations at property corners and corners of structure(s) with reference elevation datum
  • Distance between exterior walls and eaves and property lines

Additions building out (adding footprint)

Provide these additional requirements to the site plan:

  • Area of any existing or proposed buildings in square feet
  • Area of any proposed paving in square feet
  • Landscaping. If your lot is 5,000 sq. ft. or greater, show the location, size, and species of existing trees that are 6” diameter and larger.
  • Street trees. Show existing street trees.
  • Major geographical features (e.g. flood plain, natural drainage courses with elevation and centerline)
  • Location of existing
    • septic tanks
    • cesspools; and
    • drain fields (both abandoned and in active use)
  • If adding more than 500 sq. ft. of impervious area or establishing a new sewer service connection: Show the location of
    • sewer lines
    • water lines; and
    • method of stormwater disposal
  • For additions that include a basement, provide a cross-section showing
    • the basement foundation excavation; and
    • the distance to property lines
      Please use the Temporary Excavation Guidelines to determine application requirements. 

Architectural plan checklist


  • Scale plans to be ¼ inch = 1 foot and details scaled to ½ inch = 1 foot
  • Single-line drawings are not acceptable – plans must be drawn to show wall thickness
  • Floor plans: Label the existing layout and the proposed new layout. Even if you are only working on a small part of the building, you still need to show the whole floor layout.
  • Building elevations must be to scale and show the slope of the ground adjacent to the building.

All additions

  • Fully dimensioned floor plans, showing:
    • Demolished walls, existing walls to remain, and proposed walls (with wall legend)
    • Windows (noting size, sill height, method of operation, safety glazing, and window wells where required) and doors (showing size and swing direction) for each floor affected
    • Label the use of each room
    • Plumbing fixture layout
    • Gas/oil furnace and water heater location
    • Electrical light fixtures, exhaust fans, and smoke and carbon monoxide detectors
  • Exterior building elevations (side view of each side)
    • Labels for new and existing areas
    • Existing and proposed roof pitch(es) and siding material
    • New building height (dormers and additional stories) must be dimensioned from an identifiable base point on the site (see: Zoning Code Measurements Chapter).
  • Dimensioned building section(s), showing:
    • Typical wall, floor, ceiling, roof, and foundation construction
    • Overall ceiling height and any dropped ceilings or soffits in converted areas
  • Stair details with dimensions for risers, treads, headroom clearance, guardrail, and handrails
  • Energy conservation information:
    • Insulation R-value for ceiling, walls floors, U-values for windows and doors
    • If your addition adds 225 square feet or more of new, heated space, plans must clearly specify at least one "Additional Measure" energy upgrade. Visit the Oregon Residential Energy Code for tables on Additional Measures.
      • Small additions (225 to 599 square feet) may choose either a Small Additional Measure from ORSC Table N1101.3, or an Additional Measure from Table N1101.1(2).
      • Large additions (600 square feet and larger) must choose an Additional Measure from Table N1101.1(2). 
  • Details of all non-typical construction

Structural plans checklist


  • Scale plans to be ¼ inch = 1 foot and details scaled to ½ inch = 1 foot.
  • Most additions require structural plans drawn by an Oregon-licensed architect or engineer.
    • Exception: A licensed design professional may not be required for simpler projects that meet
      • Prescriptive design requirements in the Residential Code;
      • Projects that meet the "minor addition" criteria found in the Lateral Bracing Requirements for Minor Additions and Dormers in Existing 1 & 2 Family Construction

  • To determine whether your addition project can be designed prescriptively, or whether you will need a licensed architect or engineer, make a 15-minute appointment with our Residential Building Code reviewers.
  • Structural engineering plan review of limited scope: When structural plans and supporting calculations have been stamped by an Oregon-licensed engineer and when the project meets the criteria in the document, Limited Structural Engineering Plan Review for Single Family Dwellings, you may request a structural review of limited scope. 

Get information about structural and engineering requirements for one and two-family residential projects.

All additions

  • Gravity load analysis showing load transfer through added or altered areas, including:
    • Roof framing plan showing existing and new members. Include beams and rafters (with lumber size, spacing, and span) and supporting walls and posts.
    • Floor framing plan(s) showing existing and new members. Include beams and joists (with lumber size, spacing, and span) and supporting walls and posts.
    • Foundation plan showing how new loads are supported. Include ventilation, underfloor access, and holdowns.
    • Calculations for new structural elements or existing structural elements that are impacted by the addition.
    • Where a new load is added to an existing foundation, provide EITHER
      • A stamped letter from an engineer addressing the adequacy of the existing foundation to support the new load;
      • Calculations demonstrating the existing foundation is prescriptively adequate, with the added loads, at the assumed soil pressure of 1500 PSF.
  • Lateral load analysis for resistance to wind and seismic forces, showing either prescriptive or engineered method, including:
    • Prescriptive method (per ORSC R602.10): Locate, dimension, and identify the type of braced panels and braced wall lines.
      To demonstrate that all braced wall lines are adequate to resist wind and seismic forces, use an online calculator like the APA Wall Bracing Calculator. Use a calculator based on the 2018 or 2021 International Residential Code design criteria. Provide the wall bracing worksheet generated by the APA Wall Bracing Calculator with your plans.
    • Engineered method: drawings, details, and calculations prepared and stamped by a licensed design professional showing shear walls, nailing pattern, type of sheathing, and hold downs where required.
      Engineering calculation packets shall be separate from the plans, but engineering details are to be incorporated into the construction documents and cross-referenced on the plans
    • Minor additions: Provide calculations demonstrating the project is a 'minor' addition or 'minor dormer' using the criteria in the document, Lateral Bracing Requirements for Minor Additions and Dormers in Existing 1 & 2 Family Construction
  • Details for connections to existing construction

Prepare files for upload

All documents and plans should be PDFs.

For how to prepare PDFs and file naming standards, visit our guide on File Naming Standards and Preparing PDFs for DevHub upload.

Paper plans

Paper plan reviews are limited. Most permits must be submitted electronically. 

If your project qualifies for paper plan review, please review the following submittal requirements for paper size, number of copies, and other specific requirements.

See if you qualify for paper plan review.

Permit process overview

Learn about the permit process from planning to inspections.

  1. Define and research. 
  2. Gather your completed application requirements and apply. This page has application requirements for residential additions.
  3. Permit review and getting your permit. Respond to any feedback from the city, get your permit, and begin work
  4. Inspections. Get your work inspected by the city and close out your permit(s).

Apply for a permit

Gathered your completed application requirements and apply.

Apply for a permit now on DevHub

Need help?

We're here to help you determine the specific requirements for your project.

For quick questions, call General Inquiries at 503-823-7300.

For specific questions about your project, we recommend scheduling a free 15-minute virtual appointment with permitting staff.

Schedule a free 15-minute virtual appointment now