The usable floor area of an apartment building is the area that can be used for a specific purpose. The usable floor area is calculated on the basis of the dimensions of the building and includes the entire floor space minus the walls.
In addition to the living spaces, the usable floor area also includes any loggias or parking spaces. Functional areas such as a boiler room or circulation areas such as stairs are not defined as usable floor area. The usable floor area is used to calculate the running costs and the rent and is generally essential for calculating the value of an apartment building.