Floor Area Ratio (FAR)
The correlation between the plot area on which the building is constructed and the building floor area that can be used or is allowed to be used
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What is Floor Area Ratio (FAR)?
Floor Area Ratio (FAR) indicates the correlation between the plot area on which the building is constructed and the building floor area that can be used or is allowed to be used.
A higher floor area ratio implies an urban or denser construction. FAR guidelines are determined by the municipalities and differ from one locality to another.
The floor area ratio can be determined by using the following formula:
Floor Area Ratio (FAR) = Total Building Floor Area / Gross Lot Area
Summary
- Floor Area Ratio (FAR) refers to the relationship between the area upon which the building is constructed and the building floor area that is usable or is allowed to be used.
- FAR guidelines are determined by municipalities and generally differ from one locality to another.
- Ratio will vary depending on the variation in population density, construction-related activities, growth patterns, and the nature of the building’s space or land.
Example of Using Floor Area Ratio (FAR)
Assume that a plot of land comes with a floor area ratio (FAR) of 3.0, and the lot area is 1,000 square feet. A single-story building covering 3,000 square feet (3.0 * 1,000 square feet) can be constructed. A three-story building covering 1,000 square feet can also be constructed.
Interpretation of Floor Area Ratio
The floor area ratio considers not only the footprint of the building but also the building’s entire floor area. Unoccupied areas like parking garages, elevator shafts, and basements are not included in the calculation of a floor area ratio.
Localities may experience limited space or limited capacity, and the use beyond that capacity puts stress on them. It can be referred to as the safe load factor.
The variation in population density, construction-related activities, growth patterns, and the nature of the building’s space or land cause the FAR to vary. Since the safe load factors for agricultural, residential, and industrial spaces are different, the FAR is different for the different spaces. The local governments set up restrictions and regulations to establish FAR.
Floor area ratio (FAR) can also help in determining the development level in an economy. The real estate industry seeks increases in the FAR, implying that they seek to open up land resources and spaces to developers.
A higher FAR enables developers to finish high density construction projects, which, in turn, leads to increased sales and supply and decreased expenses per project. On the other hand, a low FAR restrains constructions and growth.
If the FAR increases, the property may become more valuable in the event the building is constructed in a way that allows more space or more people.
Purpose of Floor Area Ratio (FAR)
The floor area ratio figure can be used by local governments to divide land areas into zones to restrict urban density. The ratio not only restricts building density but also puts a restriction on the number of persons allowed in a building in the absence of controls on the external shape of the building.
For example, assume that the FAR to be followed by a plot of land is 0.2. It implies that the total floor areas of all the buildings’ floors on the said plot of land should not exceed one-fifth of the plot area.
Hence, if the plot is 15,000 square feet, the aggregate floor areas of the floors in all the buildings on the plot should not be more than 3,000 square feet.
Architects can plan to consume the allowable area in either a single-story building or multi-story building. However, for the same floor area, the footprint of the multi-story building should be smaller than that of a single-story building.
Certain flexibility in the building design can be allowed when the vertical and horizontal limits are combined into one figure. The benefit of considering the floor area as unchanging is that it is consistent with the other considerations applicable to zoning regulations.
Additional Resources
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