Washington County ADU Permits

In Washington County, an accessory dwelling unit is a secondary, self-contained dwelling unit that may be allowed in conjunction with a detached single family dwelling. Accessory dwelling units are subordinate in size, location, and appearance to the primary detached single family dwelling.

An accessory dwelling unit generally has its own outside entrance and always has a separate kitchen and bathroom. It may be located either within, attached to, or detached from the primary detached single family dwelling unit. Only one accessory dwelling unit may be created in conjunction with a detached single family dwelling unit.

This guide quickly outlines a summary of key zoning and construction standards. For an in-depth review of the application and review procedures for installing an ADU, see the pdf below.

  • 1 attached or detached ADU per residential property

  • SDC Fees-$6-25,000

  • Size-800 SF or 50% of the primary residence, whichever is smaller

At Dweller, we are responsible for all tasks, including design, permitting, construction and installation of the ADU. As part of this model, Dweller’s fixed cost covers not only the cost of construction and installation, but also the cost of permitting, utility connections and landscaping.

Click here to learn more about the Washington County Permitting Code for Accessory Dwelling Units (ADUs).