Accessory Dwelling Unit Laws in Oregon


Like most states in America accessory dwelling unit (ADU) laws in Oregon are mainly decided on a city or county level. Below is a list some of the most populous cities in the Beaver State and the ADU laws that they have. The cities include:

  • Portland
  • Beaverton
  • Salem
  • Eugene

Portland

We begin our look at ADU regulations throughout Oregon in the state’s most populous city, Portland. Luckily the city has provided a guide to it’s rules relating to Accessory Dwelling Units.


The laws relating to ADU’s in Portland highlight that they can only be built within certain zoning types. They are allowed on certain lots types that are zoned for residential, central employment or commercial. They can be constructed on sites of existing manufactured homes, detached homes and row houses. Other dwelling like duplexes are not included. 

Below are some criteria that a person must follow when construing ADUs in Portland:

  • The maximum size of an ADU may be no more  than or 800 square feet or 75% of the house’s living area, whichever is less. (According to the guide the living area can be calculated by subtracting a number of features from the total house size like garage areas and the exterior walls thickness)
  • The ADU’s electrical circuits have to be completely separate to that of the main dwelling unit.

It is recommended you check with the city to see what the most recent ADU laws are.

Beaverton

The city of Bereavement has issued Building Code Considerations for Accessory Dwelling Units. A summary of requirements for building an Assessor Dwelling Unit on property in the city is below:

  • The ADU cannot exceed 800 square feet or more than fifty percent of the gross floor are of the primary dwelling, whichever is less. 
  • A building permit is required to construct an ADU. Electrical, plumbing and mechanical permits may also be required. 
  • The ADU should have a habitable room no less than 120 square feet. 
  • All habitual rooms require must be at least 7 feet tall. 
  • The ADU has to have access to the electrical service panel.
  • A side hinged exit door is allowed on an ADU. It must be at least 36 inches wide and 6 foot eight inches high.

A person can check with the city to see what the most up to that ADU laws are.

Salem

In Salem Tiny Houses that are built on land can fall under the ‘Accessory Dwelling Unit’ category. A summary of the characteristics of an ADU under Salem’s specific code for the category is below:

  • Square footage is limited 75% of the main house or 900 square feet , whichever is less.
  • In Salem ADUs do not require off street parking.
  • There should only be one ADU per lot.
  • A bathroom and a kitchen must be included in an ADU.
  • The height limit for detached ADUs is 25 feet. 
  • The ADU mustn’t have a direct interior connection to the main house.

Eugene

The city of Eugene does have specific rules for ADUs, which can be found in their ADU document

Some specifics for constructing a ADU in Eugene include:

  • The size or the unit cannot be larger that 800 square feet or 10 percent of the total lot area, whichever is smaller. 
  • A maximum of 2 bedrooms are allowed in the unit.
  • The owner is obliged to have a 3 foot hard walkway that is from the alley or street to the primary entrance of a detached ADU. The walkway must be constructed on a hard surface. 

For further claifiation of Eugene’s ADU laws, please contact the city directly.

Conclusion on Oregon ADU laws

Many localities in Oregon allow owning ADUs. In Portland, they are allowed if they are allowed if certain requirements are met such as the maximum size of an ADU being not more than or 800 square feet or 75% of the house’s living area, whichever is less. They are also allowed in Beaverton under certain rules, like not exceeding 800 square feet or more than fifty percent of the gross floor are of the primary dwelling, whichever is less.

To find out more about accessory dwelling unit laws in cities that weren’t mentioned above, make sure to contact them directly.

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This article is written for informational purposes only and is not to be construed as legal advice.

Sources

  • Portlandoregon.gov, Bureau of Development Services, Program Guide -Accessory Dwelling Units (2019)
  • Beavertonoregon.gov, Building Code Considerations for Accessory Dwelling Units (2019)
  • www.eugene-or.gov, Eugene Building & Permit Services, Accessory Dwelling in the City
  • City of Salem, Code of Ordinances § 700.007 (2020)

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