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

Sec. 3(h) of the Zoning Ordinance governs granny units, the county's locally defined accessory dwelling, separate from the state-mandated ADU standards under Government Code Section 66310 et seq. A granny unit zoning permit can only be issued at the same time as, or after, the principal dwelling is built on the parcel, so a granny unit cannot be approved as the first structure on a vacant lot. The unit must meet the development standards of its base zoning district and the performance standards of Article 41, and it may be attached to or detached from the principal dwelling as long as it meets all of the base district's setbacks that apply to the primary dwelling.

Size is capped by parcel area: on parcels under 40,000 square feet of net parcel size the granny unit cannot exceed 720 gross square feet, while parcels of 40,000 square feet or larger allow up to 1,008 square feet. Garages and open or covered porches are excluded from that gross floor area calculation, and land used for road easements does not count toward the net parcel size threshold. Only one such unit is allowed per lot: a granny unit cannot coexist with a guest house, residential second unit or similar dwelling on the same parcel unless the granny unit is removed or converted to another authorized use.

Parking is scaled to size, one space for units of 720 square feet or less and two spaces for larger units up to 1,008 square feet, in addition to what the principal residence already requires. The unit must include its own kitchen and bathroom facilities separate from the main house.