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Taking the guesswork out of the BOMA method of building measurement

As an industry leader in building re-measurement, customers often ask RDM how the BOMA method works. We’ve found this to be essential information to any CRE professional.  What we’ve provided below is a brief overview.

Space Allocation

To begin, let’s talk a little bit about space allocation, which is particularly important for the BOMA method.
A commercial property can be broken down into the following space types: tenant space, floor common space, building common space, and vertical penetrations.

Tenant space refers to office areas, as well as any storage or retail areas.
Building common space and floor common space refers to lobbies, corridors, bathrooms, and mechanical rooms; all areas that are shared by tenants.
Vertical penetrations refer to any areas that are not slabbed over, such as shafts, stairwells, and elevators.

The BOMA Method

The BOMA method is the prevailing method in pretty much every market in the country, outside of New York City. The latest BOMA standard, which was released in 2010, allows for more than one type of BOMA, including:

  • BOMA Method A (Legacy Method)
  • BOMA Method B (Single Load Factor Method)
  • New Concept of Optional Adjustment (allows for a cap on the load factor)

The one that is most frequently used across the country is BOMA Method A. This is also called the “Legacy Method”, as it is very similar to BOMA 1996.

To determine office RSF using BOMA methods:

  1. Measure the entire property top to bottom, including all enclosed areas on the roof and sub levels.
  2. Deduct the vertical penetrations.
  3. Apportion the building common areas back to each floor.


Load Factor vs. Loss Factor

While it’s a common mistake in Real Estate to use the terms “Load Factor” and “Loss Factor” interchangeably, they actually have very different meanings. The load factor of a given space is the rentable area divided by the usable area.  The loss factor on the other hand is the percentage of the unused square footage divided by the rentable area.

RSF ÷ Usable Area = Load Factor
% of Unused SF ÷ RSF = Loss Factor


Efficient vs. Inefficient Floor Plates

Properties are said to have “efficient floor plates” when they maximize the amount of usable space and minimize the amount of common space.  Conversely, properties are said to have “inefficient floor plates” when they have large mechanical rooms, wide corridors, long wraparound corridors, or complex core configurations.

Properties that have a lot of setbacks also tend to be inefficient, because the size of the core areas remains the same throughout the building, but the usable office areas decrease in size as you get towards the top.

This article was written by Joe Leach. Joe is the Senior Sales Director at RDM, a leading provider of measurement services throughout the U.S. Contact Joe via email or LinkedIn.