In unincorporated Douglas County, any retaining wall taller than 4 feet in height requires a building permit. Walls at or below 4 feet generally do not, unless the adopted Building Code requires one.
The Zoning Resolution ties retaining-wall permits to height: anything over 4 feet needs a building permit, matching the International Residential Code threshold Douglas County has adopted. The 4-foot measurement is typically taken from the bottom of the footing to the top of the wall, and tiered or surcharge-loaded walls can be aggregated, so confirm the design with the Building Division. Walls must not obstruct traffic sightlines and, like fences, cannot be placed in the public right-of-way. Engineering (stamped plans) is commonly required for taller or load-bearing walls.
Constructing an over-height retaining wall without a permit is a code violation; the county may require engineering review, permitting after the fact, or corrective work.
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See how Douglas County's retaining walls rules stack up against other locations.
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