# IBC 2018 Concentrated Business Occupancy



## Michael Schirmer (May 16, 2019)

Hi.  I'm new here and found this via another forum where I was told of this forum.  Glad to see a place where building code can be discussed.

With the introduction of the IBC 2018, Business occupancy has been subdivided in Table 1004.5 and then Section 1004.8. Now the occupancy for Business is 1:150 and then there is "Concentrated Business Use" where the number of seats is counted. Sure, it says for call centers, etc, but that isn't how the cities around my area are using it like Plano, Texas. They are counting the cubicle, no matter the use. I'm curious if anyone else has worked with cities with IBC 2018 and what are your understandings? There are a few mixed answers in our office on how to determine the floor space of the "Concentrated Business Use (CBU)" area. Do you count only the floor space under the cubicles, the entire region of cubicle area or the entire open office area where the cubicles exist, which could include areas that could be classified as a hall? 

Any thoughts on this?


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## RLGA (May 16, 2019)

Section 1004.8 states the actual occupant load, but not less than 50 sq. ft. of "*gross *occupiable floor space." Thus, I would treat it just like you would for the standard gross floor area for business areas per Table 1004.5.


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## Tim Mailloux (May 16, 2019)

RLGA said:


> Section 1004.8 states the actual occupant load, but not less than 50 sq. ft. of "*gross *occupiable floor space." Thus, I would treat it just like you would for the standard gross floor area for business areas per Table 1004.5.



So the new concentrated load is the high number using either 1 person per 50sf of gross floor space or the actual number of people?


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## RLGA (May 16, 2019)

Tim Mailloux said:


> So the new concentrated load is the high number using either 1 person per 50sf of gross floor space or the actual number of people?


Yes, it's the greater of the two. Per the _Significant Changes to the International Building Code_ (2018 Edition): "...the occupant load must be established at a minimum of one occupant for each 50 square feet."


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## Michael Schirmer (May 16, 2019)

So in the example below, which area do you include is sq ft of Concentrated Business Area?  Green only? Red only? Red and Blue?  This is part of our issue of determining what code implies.


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## RLGA (May 16, 2019)

Red plus blue and then some (some areas not highlighted would be included in the gross floor area); but I agree with you...this is not a concentrated business use. I bet if you took that gross floor area and divided it by 150 you would get a number very close to the number of cubicles shown.


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## Michael Schirmer (May 16, 2019)

RLGA said:


> Yes, it's the greater of the two. Per the _Significant Changes to the International Building Code_ (2018 Edition): "...the occupant load must be established at a minimum of one occupant for each 50 square feet."


The code says


RLGA said:


> Yes, it's the greater of the two. Per the _Significant Changes to the International Building Code_ (2018 Edition): "...the occupant load must be established at a minimum of one occupant for each 50 square feet."


Thanks.  We're going to get that book then.  Might be more there that we need clarification.


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## Michael Schirmer (May 16, 2019)

I didn't mean to add that first part and dont know how to edit yet.


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## RLGA (May 16, 2019)

This is a call center floor plan--there's a big difference between what you show and what is shown below.


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## Michael Schirmer (May 16, 2019)

RLGA said:


> This is a call center floor plan--there's a big difference between what you show and what is shown below.


I agree.  The city put out its rule that all workstations fall under the category of "concentrated business".  They also give leniency to the lesser number.


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## Michael Schirmer (May 16, 2019)

RLGA said:


> This is a call center floor plan--there's a big difference between what you show and what is shown below.


With this plan you show, would you still include the empty open office above office 1 & 2, as well as the corridor area for the "concentrated business"?  Just reclarifying.


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## RLGA (May 16, 2019)

Michael Schirmer said:


> With this plan you show, would you still include the empty open office above office 1 & 2, as well as the corridor area for the "concentrated business"?  Just reclarifying.


No, I would apply the 1:150 OL factor to that space (unless it has another defined use not indicated), as well as the open area just outside of those offices.


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## Michael Schirmer (May 16, 2019)

That is what I was assuming.  I think the first city I had to use the 2018 code for confused me on how to interpret.  Texas allows cities to choose the code.  There is actually one city we deal with still on 2006 codes.


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## Tim Mailloux (May 16, 2019)

Remember that the gross floor area for the business use included in the calculation is everything with a roof over it, Corridors, toilets, stairs shafts, elevator shafts, mechanical shafts, etc. minus any floor area net functions of space such as conference rooms.


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