Green Structures NW
ADU Plans     |     ADU Guidelines     |     ADU Ideas     |     ADU Info
An accessory dwelling unit, usually just called an ADU, is a secondary housing unit on a single-family residential lot. The term “accessory dwelling unit” is a institutional-sounding name, but it’s the most commonly-used term across the country to describe this type of housing. The fact that it’s a secondary housing unit—rather than a given structural form—is what defines an ADU.  When we are learning about concepts, it’s natural to want to know what that concept looks like in the flesh. We want to visually embed the design concept in our brains as a tangible object that we can mentally reference. However, ADUs vary in their physical form quite a bit, not only on form and function, but what is allowed in each city. Below are some links to local cities regulations for the planning of ADU's.  Oregon law now requires all cities to allow ADU construction within urban growth boundaries.
While their structural forms vary, ADUs share some common traits and face common design and development challenges. For one thing, the fact that they’re secondary housing units on single family residentially zoned lots places ADUs into a unique category of housing. ADUs also have some other distinguishing characteristics that help further define, differentiate, and distinguish them from other housing types.  
  • ADUs are accessory and adjacent to a primary housing unit.
  • ADUs are significantly smaller than the average US house.
  • ADUs tend to be one of two units owned by one owner on a single family residential lot.
  • ADUs typically are developed after the primary house by homeowner developers.
  • A large range of municipal land use and zoning regulations differentiate ADU types and styles, and dramatically affect their allowed uses.
City of Portland Info:
City of Salem Info: