Build an Accessory Building / Shed

What an Accessory Structure Is

An Accessory Structure is a detached building or structure subordinate in size and use, but located on the same lot as, a principal building.

Accessory Structures come in many different forms, but for residential uses they are often detached garages, shops, sheds, carports, gazebos, greenhouses, etc.

In residential zones, depending on how big the lot is, Accessory Structures can be up to 800 square feet. Accessory structures on lots smaller than 20,000 square feet in area are limited to 600 square feet.

In non-residential zones, Accessory Structures can be a variety of sizes, but all non-residential Accessory Structures over 200 square feet require a Type II Minor Site Plan and Design Review process.

Please note that Accessory Dwelling Units (ADUs) are different from Accessory Structures and are subject to different standards. See more information about ADUs.

Download the Accessory Structure Planning Guide (PDF) for more information!

Easements & Setbacks

Many properties have public utility easements ("PUEs") along side and rear property lines. Easements supercede the setback standards of a property's underlying zone. In other words, new Accessory Structures cannot be built in or encroach upon an easement.

For example, if your Accessory Structure is small enough that Oregon City Municipal Code allows it a three-foot setback from the property line, but your property has a five-foot easement area along that same property line, the structure must be set back at least five feet to avoid the easement. Easements can be found on many plat maps or at OCWebmaps.

Otherwise, residential Accessory Structures 600 square feet or less and under 17 feet in building height (as measured at the roof's midpoint above average grade) can be set back as little as 3 feet from a side or rear property line, including projections.

Residential Accessory Structures larger than 600 square feet and/or more than 17 feet in height must be sited clear of the setbacks of the underlying zone, including projections.

Prohibitions on New Accessory Structures

Residential Accessory Structures cannot be located in front of the front building line of the primary residential structure on the lot.
Cargo containers are not allowed as residential Accessory Structures unless modified to where the average person cannot tell it's a cargo container.
Permanent membrane or fabric-covered Accessory Structures cannot be visible from any public right-of-way.
Metal structures are prohibited within a historic district, or on an individually designated historic property, unless authorized by OCMC Chapter 17.40.

Application Review Criteria

The Planning Division reviews Accessory Structure applications for compliance with Oregon City Municipal Code. Generally speaking, the following chapters of the code are directly applicable to all Accessory Structures:

The property's underlying zone
OCMC 17.54.010 - Supplemental Zoning Regulations and Exceptions, Accessory Structures
OCMC 17.62 - Site Plan and Design Review

However, different properties have different characteristics, configurations, and dimensions. Depending on the circumstances, an Accessory Structure application might involve additional review if the project requires a Variance or is located in:

A historic district or historically designated lot
The Flood Management Overlay District
A Geologic Hazard area
The Natural Resource Overlay District
The Willamette River Greenway District
A Non-conforming lot, site, or structure

Find Out More About Your Property

The City's website has a variety of resources available including Property Reports and OCWebMaps, our online mapping system. You may also email the Planning Division or call 503-722-3789 for more information.

Application Review Processes

Generally, the Planning Division reviews residential Accessory Structure applications through a Type I Land Use process that's integrated into the application packet attached at the bottom of this page. Type I applications involve a non-discretionary review process and are typically reviewed by staff within two weeks.

In non-residential zones, all non-residential Accessory Structures over 200 square feet require a Type II Minor Site Plan and Design Review process.

Typically, the Building Division and sometimes Public Works must also review an Accessory Structure project for compliance with the codes they oversee.

Accessory Structure projects that are in overlay districts or require a Variance are typically reviewed through a Type II (PDF) or Type III (PDF) Land Use process that usually begins with a Pre-Application Conference.

How to Apply

Fill out the Planning Review of an Accessory Structure Application (PDF) packet. Planning Review is typically done when an applicant files for a building permit, unless additional review (as outlined above) is required.

So once you fill out the application packet, you can submit it with your Building Permit application and required materials by emailing it to Permits. You can contact the Building Division with questions about filing for a building permit via email or by calling 503-722-3789, as well.

If you have any questions about the Planning application process, you can email the Planning Division or call 503-722-3789.

Planning Review Fees

Once we receive an Accessory Structure application, Planning Division staff must take time to review it to ensure the project complies with all relevant codes. The fees we charge are related to the time and effort typically required to review your project.

You can view our Planning Review of a Building Permit Fee, and all other potential review processes that may affect such a project, on our Planning Fee Schedule.

System Development Charges (SDCs)

Residential Accessory Structures don't typically trigger SDCs. However, Oregon City's Public Works Department may charge SDCs for non-residential Accessory Structures under certain circumstances. You can email Public Works for more information about SDCs.