On Jan. 14 Washington City Council adopted amendments to the city code governing detached accessory dwelling units (ADUs), revising lot‑size, setback, size and height limits and clarifying how ADU square footage is calculated.

Community Development Director Eldon Gibb said the package responds to market demand and planning‑commission feedback. Key elements adopted include removal of the 10,000‑square‑foot minimal lot requirement, allowance for attached garages/carports for ADUs, a tiered square‑footage cap (1,000 sq ft in R‑1‑6/R‑1‑12 with higher caps for lots over 15,000 sq ft), and a height and setback formula that increases allowable height the farther the ADU is placed from the property line.

Council wrestled with whether the ordinance should require ADU exterior materials to be the "same" as the primary residence; the council struck stricter language and instead approved a standard that calls for similar materials and build quality to reduce subjective enforcement problems. Local ADU builder Dan Witt supported the similar‑material formulation, saying, "Similar build and quality puts that in the same realm," and noted typical ADU sizes are 500–600 sq ft.

Fire Chief Evans explained that fire‑rating requirements affect how close an ADU can be sited and what type of rated walls or glazing would be required if an ADU sits within 3–5 feet of a property line; council considered these constraints when debating setback and height thresholds.

The council adopted the ADU changes in two related ordinance items (8b and 8c) on a 4–1 roll call; Councilwoman Caspersen voted no on the final adoption, citing neighborhood compatibility concerns. The amendments are now city code and will be enforced through building‑permit and plan‑review processes.

Next steps: Staff will publish updated code language and coordinate with Building and Fire departments on plan review guidance; applicants with pending ADU proposals should consult planning staff on how the new standards apply.