Mountain View, CA Fence Regulations: Retaining Walls (2026)

' Read against the rest of the exemption list, the threshold is deliberately tight. The same section exempts decks, platforms, paths and driveways only when they are 'not over eighteen (18) inches above natural grade' and not already subject to Chapter 8 permitting, showing the city treats 18 inches as its general bright line for when earth-retention or grade-change work moves from administratively exempt to permit-required. 35, which bars establishing, constructing or altering any use or structure unless any required zoning permit has first been obtained.

50 also makes clear this is an exemption from the zoning permit specifically, not a blanket exemption from every code requirement; a retaining wall still must satisfy Chapter 8's building and grading standards, and taller or structurally significant walls typically require engineered plans reviewed by the Building Division before construction can begin. The practical effect for homeowners is that small retaining walls holding back minor grade differences can be built without a discretionary zoning review, but anything approaching or exceeding roughly a foot and a half of retained grade change should expect both a grading permit and a zoning permit review.