Floor area ratio measures the square footage of a building on each floor and compares that to the size of the lot. For example, a two-story house that is 1,250 feet on both the first and second floor has a total of 2,500 square feet of floor area. If this house were on a 10,000 square foot lot, it would have a floor area-to-site area ratio of 0.25:1 (10,000 ÷ 2,500 = 0.25). If this same size house were on a 5,000 square foot lot, it would have floor-area-to-site area ratio of 0.5:1 (5,000 ÷ 2,500 = 0.5)
The proposed FAR tool would control the visible bulk of a house while providing flexibility in house design. Most of the floor area of covered and enclosed areas within a house are included. A basement would not count toward a house’s FAR because the majority of a basement’s bulk is below ground. Similarly, only attic space that significantly contributes to a building’s visible bulk would be counted toward a house’s FAR.
Because FAR is intended to reduce the bulk of the primary house, internal garages, internal accessory dwelling units and enclosed porches that contribute bulk would be counted toward a house’s FAR. However, when such features are detached from the primary house and located elsewhere onsite — thereby reducing the bulk of the primary house by distributing it over the whole lot — these detached structures would not count toward a house’s FAR (but would be subject to other size restrictions).