Caldwell, ID Fence Regulations: Retaining Walls (2026)

Retaining walls in Caldwell are regulated primarily through the Idaho Residential Code, enforced by the Building Safety Division, rather than a stand-alone city wall ordinance. Under the permit-exemption provisions of IRC Section R105.2, a retaining wall is generally exempt from a building permit when it is not over four feet (4') in height measured from the bottom of the footing to the top of the wall, provided it does not support a surcharge (such as a slope, driveway, or structure above) or impound Class I, II, or III-A liquids. A wall taller than four feet, or one carrying a surcharge, requires a building permit and typically engineered (often stamped) plans for lateral earth pressure and drainage. Separate from the building permit, a retaining wall that also functions as or supports a fence must still satisfy zoning Section 10-02-07 for combined height near property lines, and no wall or fence over three feet may sit in a vision triangle. Walls along a boundary should be located by survey, since they can affect the adjoining parcel and grade. Because thresholds and engineering requirements depend on the specific site and wall type, owners should confirm with the Building Safety Division before construction and provide a site plan showing the wall's location relative to property lines.