FAR, the floor area ratio, is determined by multiplying the area of a property by a number determined by the property’s zoning district. For instance a 20’x100′ property in a zoning district of R5 has a factor of 1.25 allowing for 2500 square feet of ‘habitable’ interior space.
The issue is what is considered habitable. FAR accounts for the gross built area including thicknesses of walls, suggesting that the very walls that help define the interior spaces are habitable. This results in something unfortunate, the attempt to make structural walls thinner resulting in larger interior spaces, which results in buildings that feel less sturdy by the increase in noise infiltration, vibration and other factors.