Orange County applies hillside management overlays in unincorporated foothills and canyon areas, restricting grading, ridgeline development, and density on slopes above defined gradients to protect viewsheds and wildfire safety.
OC Zoning Code applies hillside management standards in unincorporated areas like Silverado, Modjeska Canyon, Trabuco Canyon, and Coto de Caza, where parcels exceeding defined slope thresholds face stricter setbacks, lower building coverage caps, and ridgeline silhouette protection. Grading is limited by slope-density formulas reducing allowed unit counts on steeper terrain. Wildfire-Urban Interface mapping aligns with these areas, layering Title 5 fire code requirements for defensible space, ignition-resistant construction, and emergency access width. Planning Commission discretionary review is typically required for tract maps and large estate homes in these zones.
Building beyond hillside envelope or grading without slope-density compliance triggers stop-work, restoration, and discretionary permit revocation.
See how Costa Mesa's hillside overlay rules rules stack up against other locations.
Help us keep this page accurate. If you notice an error or outdated information, let us know.