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This help desk is a free resource intended for discussion purposes only. Neither BOMA, its chapters, affiliates, or Extreme Measures Inc.® are responsible for the information, comments or opinions expressed herein. For complete information, refer to the official publications of the standards themselves.

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Usable Area Calculation

Art Webb
RAND Corporation
September 5, 2013

Some of our building rooms and spaces are classified as Building Common Area and some are classified as Office Area, per the 1996 BOMA standard. Which formula(s) below are correct:

a) Usable Area = Building Common Area + Office Area
b) Usable Area = Office Area
c) Rentable Area = Usable Area + Major Vertical Penetrations

Adam Fingret
Extreme Measures Inc.
September 5, 2013

Hi Art,

Technically, none of your formulas are correct. According to the Standard:

Usable Area = Office Area + Store Area + Building Common Area.

The term Usable Area is often used to describe the actual measured area of tenant space prior to common area allocation, so yes, b) Usable Area = Office Area, but only if we are talking about the one office tenant (and not all of the tenants on the floor or in the building).

Rentable Area = Usable Area + a proportionate share of Floor Common Area and Building Common Area. Note that both Usable and Rentable Area definitions specifically exclude Major Vertical Penetrations.

Hope this helps

Art Webb
RAND Corporation
September 5, 2013

The building in question is owned and occupied entirely by our company. There is no commercial store area in the building. In this particular case, would it be true that Usable Area = Office Area + Building Common Area?

There are other buildings where the company rents a floor or several floors within a building, but not the entire building. There is no commercial store area on the floors leased by the company. In a case like this, would it still be true that Usable Area = Office Area + Building Common Area on the rented floors?

In both of the above cases, does the Floor Rentable Area = Floor Usable Area + proportionate share of Floor Common Area?

Adam Fingret
Extreme Measures Inc.
September 9, 2013

For the building in question, yes Usable Area = Office Area + Building Common Area. The same is true of the other buildings.

In both cases Rentable Area always includes a proportionate share of Floor Common Area AND Building Common Area. Note that Building Common Area is itself measured like other Usable Areas, but is applied in the form of a Building R/U Ratio to tenants only e.g. Office & Store Usable Area.

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