Ames, IA Fence Regulations: Retaining Walls (2026)

Ames Municipal Code Sec. 5.104, Building Permits Not Required, exempts several categories of small construction from needing a building permit, including subsection (5): retaining walls that are not more than 4 feet in height above the lowest adjacent grade, unless the wall supports a surcharge or impounds Class I, II or IIIA liquids, in which case a permit is required regardless of height. Separately, the Zoning Ordinance regulates how far a retaining wall may project into a required yard setback. Sec. 29.402(2)(c)(v) allows retaining walls that retain fill to fully project into a required setback up to 4 feet in height in a front setback and up to 6 feet in height in a side or rear setback.

Sec. 29.402(2)(c)(vi) removes any height limit for a retaining wall that retains only existing natural grade rather than fill, so a wall built to hold back a naturally sloping hillside is not subject to the 4-foot or 6-foot figures that apply to fill walls. Fences, by contrast, are separately exempt from a building permit entirely under Sec. 5.104(4), regardless of height, so only the retaining-wall threshold in subsection (5) applies here. Taken together, a homeowner adding a retaining wall in Ames needs to check two thresholds: whether the wall's height triggers a Chapter 5 building permit, and, separately, whether the wall's location and height comply with the zoning setback allowance in Sec. 29.402(2)(c). The Building Official administers permit review; the Zoning Enforcement Officer reviews the setback and height standard for compliance.