Phoenix, AZ Fence Regulations: Retaining Walls (2026)

Retaining wall rules are set out in the Planning & Development Department Technical Guideline 'Required Permits for Fences and Retaining Walls' (TRT/DOC/00181) under Phoenix Building Construction Code 105.2.2. A permit is required for all retaining walls over 3 feet in height measured from the top of the footing to the top of the wall, and for retaining walls 3 feet or less burdened by a surcharge from a house, building, road, swimming pool, or that support a fence on the wall or within 3 feet measured horizontally from the uphill side. No permit is required for retaining walls 3 feet or less with no surcharge load. 'Surcharge' means any lateral or gravity load applied to a retaining wall over and above the design load of the retained soil. Retaining walls over 3 feet require structural design calculations and details; combinations of retaining walls and fences always require calculations regardless of location or overall height, and combinations exceeding 9 feet require zoning approval before permit issuance. The location and height of all retaining walls must be shown on grading and drainage plans.