Bellevue, WA Fence Regulations: Retaining Walls (2026)
Key Facts
- Permit-exempt height
- 4 ft or less, footing to top
- Engineer required
- Modular block walls over 4 ft
- Drain required
- Modular block walls over 4 ft
- Surcharge exception
- Permit needed regardless of height
- Minor-improvement cutoff
- Under 30 inches
- Governing sections
- BCC 23.05.090; BCC 23.76.086
Summary
Bellevue exempts retaining walls up to four feet from a building permit under BCC 23.05.090, but anything taller, or one holding back a surcharge, needs a permit. Modular block walls over four feet must be engineer-designed with a wall drain under BCC 23.76.086.
d. Retaining walls which 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. [BCC 23.05.090(B)(3)(d)] ... A. Modular block walls over four feet in height as measured from the bottom of the base block must be designed by a professional civil or geotechnical engineer. B. A wall drain must be provided for all modular block walls greater than four feet in height as measured from the bottom of the base block. The drains must be installed per the clearing and grading development standards. [BCC 23.76.086]
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 6929, passed July 14, 2026).
Full Breakdown
090(B)(3)(d) lists retaining walls not over four feet in height, measured from the bottom of the footing to the top of the wall, as exempt from the city's building permit requirement, unless the wall supports a surcharge or impounds Class I, II or III-A liquids, in which case a permit is required regardless of height. 76. 086(B) requires a wall drain, installed per the city's clearing and grading development standards, on every modular block wall over that same four-foot mark. 086(D) obligates that engineer to provide construction monitoring or testing per the permit conditions, submit construction inspection reports to the department, and deliver a final letter confirming the wall was built to the geotechnical recommendations before the final clearing and grading inspection is scheduled.
025 as an added constraint. 76 separately excludes a "rockery" or rock wall stacked at up to about a 1H:4V batter from counting as a retaining wall, and BCC's structure definition carves out residential fences, retaining walls, and rockeries under 30 inches as minor improvements outside the structure permitting scheme entirely.
Violations & Fines
Building or clearing/grading work done without the required permit, or a modular block wall over four feet built without a licensed engineer's design, is enforced as a civil violation under BCC 23.05.170(B) through Chapter 1.18 BCC, with a monetary penalty, and can also be charged as a misdemeanor under BCC Title 10 as an added or alternative penalty; each day of noncompliance counts as a separate offense. The building official may issue a stop work order under BCC 23.05.180 the moment unpermitted or non-engineered wall construction is discovered, and may assess a special investigation fee tied to that order before work can resume.
Frequently Asked Questions
Do I need a permit for a retaining wall in Bellevue?
Does a modular block retaining wall need an engineer in Bellevue?
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Sources & Official References
Other rules in Bellevue
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Retaining Walls in Nearby Cities
How other cities in King County handle retaining walls.