Alameda County planners define floor area ratio; Measure D changes cited for agricultural buildings

Alameda County Planning Director Albert Lopez told the Transportation & Planning Committee on May 19 that floor area ratio, or FAR, measures development intensity by comparing allowable building square footage to parcel size.

Lopez illustrated FAR with examples (a 10,000-square-foot lot with FAR 1 allows 10,000 square feet of building area) and said the metric is used primarily for commercial and industrial regulation while residential projects are more often measured by units per acre. He told the committee that the county code defines what counts as ‘‘floor area’’ and that Measure D (2022) recently changed several technical treatments.

Committee members raised edge cases such as swimming pools, solar panels, mausoleums/columbariums, and covered horse arenas. Lopez said uncovered patios, decks and permeable surfacing are generally excluded from FAR calculations, but structures that are covered and require a building permit — including some agricultural buildings and covered arenas — are typically counted. He noted the Measure D amendments allowed small adjustments (for example, an ag-specific FAR increase from 0.01 to 0.02) to accommodate agricultural buildings.

Lopez and staff also described that the county distinguishes residential and nonresidential floor-area definitions and that parking, setbacks and other standards make it unusual for a parcel to be fully covered by buildings. The committee discussed whether the county or the Measure D ballot language ultimately controls local definitions; staff said county code provides the working technical definitions and Measure D informed recent changes.

There was no public comment on the FAR briefing.