Mason County, WA Fence Regulations: Retaining Walls (2026)

Mason County treats retaining walls as structures subject to the county's grading and building permit framework rather than a standalone wall ordinance. Under Mason County Code § 14.44.050(b)(2), an excavation for the footings of a retaining wall is exempt from Chapter 14.44's separate grading permit only when the wall is authorized by a valid building permit from Community Development. That exemption disappears the moment the finished excavation leaves an unsupported cut more than five feet high, or reaches beyond the lot line and affects a neighboring property; either condition pulls the project back into full grading review under the chapter.

Once a wall crosses into engineered territory, for example when tied to a project moving five thousand cubic yards or more of material, § 14.44.090's engineered grading rules require plans stamped by a civil engineer and, where the site sits in or near a landslide hazard critical area, a soils or geotechnical report under § 14.44.100. Beyond the building permit, § 14.44.150(c) layers on its own charge: 'Separate permits and fees shall apply to retaining walls or major drainage structures,' billed under the county's adopted grading fee schedule in addition to any plan review fee, though standard terrace drains draw no extra charge.

The county's definitions chapter also classifies a 'landscape wall' or 'retaining wall' as any structure of rock, block, log or similar material built between differing grades to stabilize soil or protect structures, distinct from a hedge. Enforcement for unpermitted or noncompliant walls runs through § 14.44.240, which routes violations to Chapter 14.12 (general penalty) and Chapter 15.13 (enforcement).