Floor Area Ratio (FAR)
Also: FAR
Floor area ratio (FAR) is the ratio of a building's total floor area to the lot size, used to cap how much you can build. California ADU law overrides FAR and lot-coverage limits that would block at least an 800-square-foot ADU — so a tight FAR can't be used to deny a reasonably sized unit.
This state override is why small or already-developed lots can still add an ADU. For attached ADUs, the unit is generally capped at 50% of the main house's floor area. On a tight, already-built Sacramento lot, this matters in practice: even when the existing home already eats most of the parcel's allowed floor area, the city cannot use FAR to deny at least an 800-square-foot ADU. The 50% rule mainly shapes attached units — bolting a unit onto a modest 1,200-square-foot Sacramento home limits the addition to roughly 600 square feet — which is one reason owners of smaller homes often choose a detached build or a garage conversion instead.
Go deeper:Sacramento ADU rules & setbacks
Related terms
Back to the ADU glossary.