The BOMA (Building Owners and Managers Association) Standard is the most comprehensive method for the measurement and calculation of square footage inside Commercial Real Estate available. This standard has been approved by the American National Standards Institute (ANSI), and spells out how each area on the floor of a building is classified. Following are the basic terms and definitions associated with this Standard:

Building Gross Area

The largest is the Gross Area, which is measured from the inside finish surface of exterior wall of the building. This accounts for the total square footage of each floor.

Vertical Penetrations

The next classification of space is Vertical Penetrations. These areas are defined as major vertical shafts that pass through multiple floors in a building such as elevators, stairwells, mechanical ducts or shafts. The area is measured from the outside finish surface of the wall surrounding the penetration. This area is subtracted from the gross square footage of a floor, as it is not occupiable space.

Usable Area

Usable Area is defined as all space on the floor that is occupiable. This area includes all office space & support areas, conference rooms, copy rooms and secondary circulation such as interior corridors. This area is measured from the inside finished surface of the exterior wall of the building to the interior finish surface of any common or vertical penetration on the floor. Usable area that is divided by demising partitions for tenants or departments is measured to the centerline of each demising partition.

Common Area

The next group is Common Area. This category of space defines all areas that are used to support the building such as restrooms, service closets, electrical and mechanical rooms. Additionally, all areas used for major circulation such as lobbies, major corridors outside the tenant or occupied areas are typically common as well. This area is measured from the inside finish surface of the usable area on the floor to the outside finish surface of the Vertical Penetration

Common Area

For the complete BOMA standard, please refer to the most current version of the following publication:

ANSI/BOMA Z65.1-1996
STANDARD FOR MEASURING FLOOR AREA IN OFFICE BUILDINGS (© 1996)
Building Owners and Managers Association International
1201 New York Avenue, NW
Suite 300
Washington, DC 20005

Additional information about this and BOMA International can be found online at http://www.boma.org.

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