Kern County, CA Accessory Structures: ADU Rules (2026)

Kern County Code §19.90.030 (Development Standards) sets the local ADU framework. Maximum size: 1,200 sq ft for detached units; 1,200 sq ft or 50% of the primary dwelling for attached/conversion units. The principal dwelling must contain a minimum gross area of 1,200 square feet. Lots served by both community water and public sewer must be at least 7,500 net square feet; lots with only community water and a private septic system require half a net acre; lots without community water or sewer require one net acre. The ADU must have a separate kitchen, bathroom, and entrance, and either the principal dwelling or the ADU must be owner-occupied (note: state law preempts owner-occupancy for ADUs permitted between Jan. 1, 2020 and Jan. 1, 2025 under Gov. Code §65852.2(a)(6)). State preemption under Gov. Code §65852.2 requires ministerial approval within 60 days, allows 4-foot side and rear setbacks, exempts certain conversion ADUs from new parking, and removes parking entirely if the property is within one-half mile of public transit. JADUs (junior ADUs) up to 500 sq ft are governed by Gov. Code §65852.22 and require owner occupancy. Permits are issued through Kern County Planning & Natural Resources at (661) 862-8600.