Lassen County, CA Fence Regulations: Retaining Walls (2026)

Lassen County administers retaining walls through the California Building Standards Code rather than a dedicated county wall ordinance. Under California Residential Code Section R105.2 (Work exempt from permit), retaining walls that are not over four feet in height, measured from the bottom of the footing to the top of the wall, are exempt from a building permit unless they support a surcharge — meaning an added load such as a slope, driveway, or structure above the wall. A retaining wall taller than four feet, or any wall supporting a surcharge, generally requires a building permit and structural review to confirm it can resist soil and water pressure. The permit exemption addresses only the building permit; the wall must still comply with all other codes and with Title 18 zoning, including setback and drainage considerations. Where a fence is placed on top of a retaining wall, jurisdictions commonly measure the fence height from the top of the wall (treating the wall top as finished grade), so a combined wall-and-fence near a property line can quickly exceed zoning fence limits and require review. Because retaining-wall requirements depend on height, soil, surcharge, and location, owners should consult Lassen County Planning and Building Services (221 S. Roop St., Susanville, 530-251-8333) and submit engineering for any wall over four feet. This guidance is for unincorporated areas; Susanville handles its own permits.