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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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Method B - BBC Inside Tenant Area

Dixon + Associates
August 6, 2020

I have a long skinny 5 story building that has (4) building cores spaced equally across the building, each core with toilet rooms, stair shaft and elevator. At some point in the past the building cores located on the (2) extremes ends of the building, (on some of the upper floors), have been totally encompassed by a tenant. Access into the tenant spaces is by card reader only, however, they are fail-safe and in an emergency someone could exit through the tenant space to the exit stair if needed. Pg 37 of the 2017 BOMA states the BBC path needs to connect all "essential" circulation, Service and Amenity areas and the illustration on pg 70 (ill36d) clearly shows a BBC that occurs inside of a tenant space. I have also read another post on this site (July 11, 2018) where it was suggested that the BBC needs to connect each of the essential building cores, even when there are multiple cores. The "essential" part of access to the encompassed building cores would be in an emergency.

Now to my question:
Following 2017 BOMA Standard for Office Buildings, would a BBC "path" be required to the building cores that are located inside, and totally encompassed by, a tenants space? Or would that "path" just be considered as part of the tenants S.F. because other than an emergency situation, the tenant would be the only one with access to the building core?


David Fingret
Extreme Measures Inc.
August 6, 2020

Hi Chad,

When establishing BBC on any given floor, you should essentially ignore the current configuration, except if you are using an existing corridor configuration to establish the BBC. The existing or previous occupancy really shouldn't have an impact on your BBC configurations. As the standard states, when establishing BBC, it helps to visualize each floor in base building configuration and then determine the most efficient and minimum BBC path that could occur on the floor if there were only two tenants. Your situation is a bit more complicated since you have multiple cores. The standard states:

"On Multi-Wing and Multi-Core Floors or Floors with Mezzanines, multiple instances
of BBC may be required."

A such, you may establish four separate BBC paths for each floor that has four cores. Keep in mind, it's the minimum path. The BBC path will likely occur within existing tenant space. The minimum BBC path should consider emergency egress as this would be considered "essential Circulation".

I hope this helps.


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