Snohomish County, WA Fence Regulations: Retaining Walls (2026)
Key Facts
- Permit-exempt wall height
- 4 feet or less
- Height measured from
- Bottom of footing to top
- Surcharge walls
- Always need a permit
- Fence atop wall
- Measured on uphill side
- Code sections
- SCC 30.50.103, 30.28.040
Summary
In unincorporated Snohomish County, a retaining wall up to four feet high (measured from the bottom of the footing to the top of the wall) is exempt from a building permit unless it supports a surcharge. Walls over four feet, or supporting extra load, need a permit.
Retaining walls that are not over four feet (1,219 mm) in height measured from the bottom of the footing to the top of the wall, unless supporting a surcharge or impounding Class I, II or III A liquids.
(d) Water tanks supported directly upon grade if the capacity does not exceed 5,000 gallons (18,927 L) and the ratio of height to diameter or width does not exceed two to one.
(e) Sidewalks and driveways.
(f) Painting, papering, tiling, carpeting, cabinets, counter tops and similar finish work.
(g) Prefabricated swimming pools regulated under the IRC that are less than 24 inches (610 mm) deep.
(h) Prefabricated swimming pools regulated under the IBC that are accessory to a Group R-3 occupancy which are: less than 24 inches (610 mm) deep, do not exceed 5,000 gallons (18,925 L), and are installed entirely above ground.
(i) Swings and other playground equipment accessory to detached one- and two-family dwellings.
(j) Window awnings for Group R-3 and U occupancies and structures regulated by the IRC that are supported by an exterior wall, do not project more than 54 inches (1,372 mm) from the exterior wall, and do not require additional support.
(k) Flag and light poles that do not exceed 20 feet in height.
(l) Oil derricks.
(m) Temporary motion picture, television and theater stage sets and scenery.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through legislation passed August 12, 2026).
Full Breakdown
SCC 30.50.103(1)(c) exempts retaining walls not over four feet in height, measured from the bottom of the footing to the top of the wall, unless the wall supports a surcharge or impounds Class I, II, or IIIA liquids. Walls taller than four feet, or any wall carrying a surcharge such as a slope or driveway load above it, require an engineered building permit through Planning and Development Services. Where a fence is built on top of a retaining wall, SCC 30.28.040(2) requires fence height to be measured on the uphill side, so a fence atop a wall cannot use the wall to gain extra effective height on the downhill face.
Violations & Fines
Constructing an over-height or surcharge-loaded retaining wall without a permit is a code violation; PDS may require engineering, permitting, or removal.
Frequently Asked Questions
How tall can a retaining wall be without a permit?
How is fence height measured on a retaining wall?
Sources & Official References
Other rules in Snohomish County
Compare Snohomish County to another location·View the Washington fence regulations overview
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