This general overview of the standards for measuring office space allows you to get a general idea on how commercial space should be measured for rental purposes. The standards have been the generally accepted method for measuring commercial space for many years. It should be noted that this standard can and should be used in measuring commercial space in old as well as new buildings. It is applicable to any architectural design or type of construction.
Usable Area
The Usable Area is the actual area of a floor which is occupied. The amount of Usable Area on a multi-tenant floor can vary over the life of a building as corridors expand and contract and as floors are remodeled. Usable floor area is converted to Rentable Area using a conversion factor (common area factor). The Usable Area of an commercial space is computed by measuring to the finished surface side of the space side of corridor and other permanent walls, to the center of the partitions that separate the space from adjoining Usable Areas, and to the inside finished surface of the dominant portions of the permanent outer building walls. No deduction is made for columns and projections necessary to the building.
The Usable Area of a floor is equal to the sum of all Usable Areas on that floor.
Rentable Floor Area
The Rentable Floor Area is the tenant’s pro-rata portion of the entire floor, excluding elements of the building that penetrate through the floor to areas below. The Rentable Area of a floor is fixed for the life of a building and is not affected by changes in corridor sizes and configuration. The Rentable Area of floor area is computed by measuring to the inside finished surface of the dominant portions of the permanent outer building walls, excluding any major vertical penetrations of the floor.
No deduction is made for columns and projections necessary to the building. The Rentable Area of a suite on the floor is computed by multiplying the Usable Area of that suite by the quotient of the division of the Rentable Floor Area of the floor by the Usable Area of the floor resulting in the RF/U Ratio.
Building Common Area
The Building Common Area includes those areas of a building that are used to provide services to building tenants, but which are not included in the office area of any specific tenant. It also includes any associated common areas and is applied to the Rentable Floor Area to calculate the Rentable Area.
Gross Rentable Area
Rent is typically paid based upon the Gross Rentable Area which includes the Floor Rentable Area plus the pro rata share of Building Common Area.
Building Rentable Area + Pro Rata Building Common Area = Rentable Area
Load Factor
The Load Factor, or R/U Ratio, is the percentage of space on a floor that is not usable plus a pro-rata share of the Building Common Area, expressed as a percent of Usable Area. It is also known as the Common Area Factor or the Loss Factor. A Typical range is 10% to 18%.
Gross Rentable Area ÷ Usable Area = R/U Ratio
