It is not unusual to use approximations for the total area of a real estate asset. Different countries use different measurement rules, and different real estate professionals measure different things (built area, lettable area, usable area...). I do not recall having ever seen a building where everyone agrees on the total area (although it might look odd, but this is also true in some instance for the number of parking spaces). It is not unusal in that respect that following a remeasurement of a property, the total area grows or shrinks by plus or minus 2 to 3% (that is the reason why real estate companies always says that their portfolio represents "around" x sqm).
