Washington County, OR Fence Regulations: Retaining Walls (2026)

The Community Development Code treats retaining walls differently depending on whether they stand alone or combine with a fence. Section 419-5 caps tiered retaining wall structures at 7 feet in any required yard, counting all tiers within the yard toward that limit; non-tiered walls in the same yard are likewise capped at a combined 7 feet total. Section 419-4 governs the separate case of a combination fence-and-retaining-wall structure in a side or rear yard: the retaining wall portion cannot exceed 4 feet, the fence portion on top cannot exceed 6 feet measured from the back-filled or highest side, and the non-back-filled or lowest side cannot exceed a combined 10 feet.

That structure is available only where an existing or proposed grade difference between properties requires a retaining wall, as determined by the Building Official, and it is exempt from a structural building permit only when the backfill is level for a proportional horizontal distance to the wall's height. D separately exempts tiered retaining walls up to 7 feet, and all retaining walls over 7 feet located outside a required yard on two or more contiguous properties, from the county's setback requirements. Any retaining wall over 4 feet still requires a building permit under Section 419-3, regardless of whether the setback exemption applies.