ADD-ON FACTOR

The total usable square feet divided by the total number of rentable square feet within a commercial real estate lease. If the two numbers are identical, it will result to 1 but usually it is slightly lower than 1 due to the reason that some square footage will be totally or partly non-usable. The non-usable square footage includes those spaces shared with other tenants ( such as restrooms, elevators, stairwells, lobbies, or hallways) or it is occupied by structural components ( such as interior walls and support poles). If the building is poorly designed, the usable area are significantly less than the rentable area.