Fort Collins, CO Fence Regulations: Retaining Walls (2026)

The City's amendments to the 2024 International Building Code, adopted at City Code Sec. 2. The exemption caps at 4 feet measured from the low side grade to the top of the wall, and it only applies if the wall is not supporting a surcharge; where it does, the exemption requires the horizontal distance to the next uphill retaining wall to be at least equal to the height of the lower wall, a spacing test aimed at stacked walls on sloped lots. Any retaining wall over 4 feet, or a shorter wall carrying a surcharge load without meeting that spacing rule, falls outside the exemption and needs a full building permit, which in Fort Collins means engineered drawings stamped by a Colorado-licensed engineer submitted to the Community Development and Neighborhood Services Department (CDNS) for plan review before construction starts.

2's amended text states that exemptions 'shall not be deemed to grant authorization for any work to be done in any manner in violation of the provisions of this code or any other laws or ordinances,' so an unpermitted retaining wall still must be built to sound engineering practice and stay off neighboring property. Retaining walls tied to a platted subdivision, or built as part of a larger grading or site plan reviewed under the Land Use Code, may also need separate development review regardless of the building-permit exemption.

Homeowners planning a wall near a property line should also check setback and grading standards in the applicable land use instrument, since the permit exemption addresses only the building code, not zoning or drainage requirements.