Home Remodeling in
Auburn, WA

ADUs are allowed outright in every residential zone that allows single-unit or middle housing, alongside new or existing homes. Up to two ADUs are allowed per home on individually owned lots that meet the zone's minimum lot size, attached, detached, internal, or any mix.

Each ADU must be between 300 and 1,000 square feet, not counting garage space, and can be up to three stories tall. It has to connect to city sewer or be served by a septic system, and its appearance has to stay in keeping with the single-family home.

Under the residential code, an ADU closer than 5 feet to the main house needs a fire wall on both dwelling walls, at least one layer of 5/8 inch Type X gypsum board or equal.

Exterior stairs can sit in the rear and side setbacks, but no closer than 10 feet to the nearest property line. Air exhaust openings have to end at least 3 feet from property lines and from operable windows and doors.

These are the items most likely to force a redesign late on, so they belong in the first layout rather than the last.

Auburn requires one parking space per ADU, on top of the house's own parking, unless the property is within half a mile walking distance of a major transit stop. That exemption comes from state law, RCW 36.70A.698.

The Permit Center is on the second floor of the Auburn City Hall Annex, 1 E Main St., on (253) 931-3090. Applications go in online through MyBuildingPermit.com.