Union City, CA Fence Regulations: Retaining Walls (2026)
Key Facts
- Max free-standing height
- 3 ft (non-hillside districts)
- Wall + fence combined
- Capped at § 18.32.040(A) yard limit
- Exposed faces
- Must be architecturally treated
- Exceptions
- Granted by Director, limited findings
Summary
Union City caps free-standing retaining walls in residential districts at three feet, requires architectural treatment on exposed faces, and lets a fence stack on top up to the combined yard height limit.
A retaining wall which is not part of a building shall not exceed three feet in height.
2. Fencing on top of a retaining wall is permitted when the total height of both the wall and fence do not exceed the applicable maximum height requirement in Section 18.32.040(A).
3. The sides of exposed exterior retaining walls shall be architecturally treated.
4. Exceptions. Exceptions may be granted by the director where the director finds that no practical alternative exists, the purpose of the regulation will not be compromised, and no detrimental impact will result. (Ord. 55-64 § 6.3, 1964; Ord. 55.111-73 § 3, 1973; Ord. 55.124-74 § 2, 1974; Ord. 55.262-85 § 2, 1985; Ord. 55.322-91, Exh. A, 1991; Ord. 457-95 § 2, 1995; Ord. 609-03 § 2, 2003; Ord. 670-06 § 3, 2006; Ord. 900-22 § 4, 2022; Ord. 917-23, 9/26/2023)
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4940544; v16 updated 2026-06-23).
Full Breakdown
Union City Municipal Code Section 18.32.040(B) limits retaining walls in residential districts, outside the hillside combining district, to three feet in height when the wall is not part of a building. A fence can sit on top of a retaining wall, but the combined height of wall plus fence cannot exceed the yard's applicable maximum under Section 18.32.040(A). Exposed exterior retaining wall faces must be architecturally treated, and the Director may grant exceptions where no practical alternative exists, the regulation's purpose is not compromised, and no detrimental impact results.
Violations & Fines
A retaining wall built over three feet without a granted exception, or left without required architectural treatment, is a zoning violation enforceable as an infraction under Section 1.16.020, with repeat violations escalating to a misdemeanor.
Frequently Asked Questions
How tall can a retaining wall be in a Union City backyard?
Can I put a fence on top of my retaining wall?
Sources & Official References
Other rules in Union City
California rules heatmap·Compare Union City to another location·View the California fence regulations overview
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Retaining Walls in Nearby Cities
How other cities in Alameda County handle retaining walls.