Arapahoe County, CO Fence Regulations: Retaining Walls (2026)

5, Fence Regulations, in Chapter 4 of the Land Development Code, which the code states applies only to fences and walls in unincorporated Arapahoe County. Before any fence is built, altered or moved, the owner must first obtain a fence permit from the county's Public Works and Development (PWD) Building Division; permit fees are set by the Board of County Commissioners to cover inspection and administrative costs. Retaining walls fall under this permitting scheme whenever they carry a fence on top: the LDC's Chapter 7 definition of 'Fence Height' says that when a fence is erected on top of a retaining wall, the fence's height is measured from the top of the wall, not from the ground below it.

The structural threshold itself is set at four feet: any retaining wall taller than four feet, measured from finished grade on the wall's low side, needs a design stamped by a structural engineer licensed in Colorado, and that engineer's seal must appear on the plans submitted with the fence-permit application. A separate, stricter limit applies at corners, retaining walls inside the 30-foot corner sight-distance triangle cannot exceed three feet, matching the general obstruction limit that also caps fences, signs and plant growth there. 5, but the code specifically keeps the corner-lot and masonry/retaining-wall provisions in force on that land, so a farm or ranch parcel does not get a pass on the engineering trigger.

The PWD Director, the Zoning Administrator or their designees may inspect any fence or retaining wall in the county, permitted or not, and order repair or removal if it becomes a structural hazard or public-welfare nuisance.