Boise, ID Fence Regulations: Retaining Walls (2026)
Key Facts
- Front setback max
- 36 inches
- Other setback max
- 72 inches
- Permit-exempt height
- under 4 feet
- Enforcing agency
- Planning & Building Depts.
Summary
Boise caps retaining walls in setbacks at 36 or 72 inches, and a building permit kicks in above 4 feet of exposed height.
C. Retaining Walls: The following shall apply to retaining walls located within setbacks: (1) Individual retaining walls shall not exceed 36 inches in height when located within a front setback or clear vision triangle. (2) Individual retaining walls shall not exceed 72 inches in height when located within any other setback. (3) Walls shall be separated by a minimum distance of five feet in order to be considered as separate walls.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-31: Code current through: Ord. 20-26, passed 6-9-2026).
Full Breakdown
Boise's Development Code splits retaining walls by location: walls in a front setback or clear vision triangle top out at 36 inches, while walls in any other setback can go to 72 inches. Multiple walls must be spaced at least five feet apart to count as separate structures, or their combined height gets counted toward the limit. Separately, the adopted building code exempts retaining walls up to 4 feet (measured footing to top of wall) from a permit, anything taller, or any wall holding back a surcharge or hazardous liquids, needs a permit and typically an engineer's design.
Violations & Fines
Building without a required permit can trigger a stop-work order and a special investigation fee equal to double the normal plan review and permit fees. Oversized walls in a setback are a zoning code violation subject to the City's standard code enforcement process.
Frequently Asked Questions
Do I need a permit for a retaining wall in Boise?
How tall can a retaining wall be in my front yard?
Sources & Official References
Other rules in Boise
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