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

Lake County's Community Development Department processes ADUs as a ministerial zoning permit through the Planning Division, following California's state ADU framework (Gov. Code §65852.2 and the related Accessory Dwelling Unit Handbook). Under state law, a detached ADU on a single-family lot may be up to 800 sq ft and 16 feet tall, with 4-foot rear and interior side setbacks; an ADU attached to the primary home may reach 25 feet. Required parking may not exceed one space per bedroom and is waived where the property is within a half-mile walking distance of public transit. ADUs permitted between January 1, 2020 and December 31, 2024 are not required to be owner-occupied. A single-family lot is allowed one ADU and, if owner-occupied, may also add a Junior ADU (a JADU within the existing single-family home). The County participates in California's AB 1332 pre-approved ADU plan program to speed review; pre-approved plans still require site-specific permitting, and a pre-approved plan used as a primary residence must meet the 360 sq ft minimum size and include a fire-suppression system. This is significant for the wildfire-rebuild context following the 2015 Valley Fire.