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Development Services

From Concept to Construction

Phone: 503-823-7300

TTY : 503-823-6868

1900 SW 4th Ave, Portland, OR 97201

Garage, Shed, Accessory Structures

Information relating to small, non-habitable structures on the same property such as a house or duplex.

Applying For My Permit

The following information must be submitted when applying for a permit to construct a garage, shed or accessory structure. Since every project is unique, there may be some situations where you will be asked to provide additional information.

  • Completed building permit application form
  • If lot slope exceeds 20%, submit a geotechnical engineering report prepared by an engineer registered in the State of Oregon
  • Erosion control plan (may be a part of the site plan)
  • Mitigation form and/or a stormwater plan if your project will add more than than 500 square feet of impervious area
Site Plan(Scale site plans to most appropriate scale, e.g. 1”=10’ or 1/4”=1’)
  • Property lines, with dimensions
  • Total area (in square feet) of the lot
  • Adjacent streets and any easements
  • Property address and R number
  • North arrow
  • Distance between buildings and between buildings and property lines
  • Grade elevations, for lot, at property corners and corners of structure(s)
  • Grade elevations, for driveway, at the top of the curb and at the gutter
  • Existing street features such as hydrants and power poles
  • Area (in square feet) of any existing or proposed buildings
  • Dimensions and area (in square feet) of any proposed and existing paving
  • Location of sewer and water lines and method of stormwater disposal
Architectural Plans (Scale of plans to be ¼”=1’ and details scaled to ½”=1’. Single line drawings are not acceptable – plans must be drawn to show wall thickness)
  • Fully dimensioned floor plans (including existing and proposed walls, window/door sizes and locations) of each floor affected
  • Use of each area
  • Plumbing fixture layout
  • All exterior building elevations (three side views)
  • Building sections showing typical wall, floor, ceiling, roof and foundation
  • Insulation R value for ceiling, walls and floors
  • Gas/oil furnace and water heater location
  • Electrical light fixtures, smoke detectors and fans
  • Details of all non-typical construction
Structural Plans (Scale of plans to be ¼”=1’)
  • Foundation plan including hold-downs
  • Cross sections showing framing members, blocking and materials
  • Roof framing including lumber size, spacing and span
  • Braced wall panel locations shown on appropriate plans (BP/ABP per CABO or engineered calculations)
  • Any engineering calculations may be attached to the plans and engineering details incorporated into the plans or cross-referenced on the plans
  • Connections to existing construction
To submit for a permit, bring the completed building permit application and four (4) copies of site, architectural and structural plans (for the area of proposed work and areas affected by such work) along with intake fees to the Development Services Center.
 
If you are hiring sub-contractors to do work on your project, and know who they are when applying, they will be listed on your permit at that time. If you don't know when you apply for your permit, they can be added after issuance. Sub-contractors you hire must be registered with the State of Oregon and carry a current CCB license.
 
THINGS TO CONSIDER:
(1) Fire Walls and Fire Protection
The building code does not restrict placement of a structure on the lot, but it does require that if a structure is close to a property line, it must be constructed to a greater level of fire protection. Construction within three feet of a property line that you share with a neighbor (not a street or public alley) is required to be fire rated.

If your accessory structure is a garage and it will be attached to, or within six feet of the house, then the interior walls of the garage must be covered with a layer of ½” gypsum board for additional fire protection. Any openings (such as doors and windows) within this distance may be required to be protected, depending on the configuration.

Visit Planning and Zoning staff at the Development Services Center or call (503) 823-7526 to determine your setbacks. The zoning code regulates how close a structure can be to a property line.
 
(2) Building a Garage
You will need to show how you will provide the required parking space. Parking in your driveway alone may not meet this requirement. A detached garage may have structural deficiencies that would need to meet building code standards

The City requires that the garage be accessed via a driveway. If you don’t currently have a driveway you will be required to put one in. The driveway will need to be paved if it is within 150’ of an improved public right-of-way. For additional information on paving surfaces, see Portland City Code, Title 24.45.020.

If your project requires construction in the public right-of-way, then the Portland Department of Transportation will review the project, and issue a separate transportation permit for this work as well. For more information about right-of-way requirements, contact the Portland Department of Transportation at (503) 823-7002.
 
(3) Cargo Containers
Sometimes, cargo containers can be used as accessory structures. These are challenging in that they too must meet all the requirements of the code.
 
(4) Residential Engineering
Your project must be designed to meet all the requirements of the building code. This usually means that a full foundation with footings to the frost depth, and a complete lateral force resisting system are required.

The building code has two options for showing the building will resist lateral loads. View more information on residential engineering.

Visit the Plan Review staff at the Development Services Center to learn more about braced panel detail, alternate braced panel detail and two-story braced panel detail.
 
(5) Decommissioning a Septic Tank or Cesspool
When building an accessory structure, the septic tank/cesspool must be located if it exists.
  • Visit the records staff at the Development Services Center to locate any old plumbing records showing a septic system/cesspool.
  • If the septic system/cesspool is decommissioned, and within ten feet of the new structure, you must sign a disclaimer for on-site-sewage disposal system form.
  • If the septic system/cesspool is within ten feet of the new structure, it will need to be decommissioned
Call Environmental Soils staff at (503) 823-6892 for more information on decommissioning septic tanks and cesspools.