# figuring occupancy count



## omahawildcat (May 12, 2016)

our jurisdiction has decided they have figured occupancy wrong for some time. It used to be if you had an office space, the entire office space including conference room, break room, waiting would fall under B occupancy. Now they break everything out and list the break room, conference room and waiting area under assembly. My understanding is that these spaces are ancillary to the office spaces thus are figured in with the B occupancy. My impression is that the city has decided to do this to lessen the opportunity for single egress occupancies.


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## mark handler (May 12, 2016)

If an assembly space is less than 750 sq. ft. or has an occupant load less than 50, then it can be classified as a Group B or as a part of the occupancy group in which it is located.


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## Timo (May 12, 2016)

We have always calculated occupant loads based on use, per the Maximum Floor Area Allowance Per Occupant table.  Code allows or requires you to classify small conference rooms as B business, but that is totally separate issue, and should not be confused with the actual use of the space.


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## fatboy (May 12, 2016)

We do the same basically, regardless of the occupancy type, we have always calculated the occupant load on the actual use of the space, and apply the applicable factor from the load table.


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## omahawildcat (May 12, 2016)

Classifying a break room in a business occupancy as assembly is fairly stupid don't you think? The break room is only used by office employees. You are not going to have people coming off the street and filling up your break room. The whole use of gross square footage to calculate B occupancy is what I assumed would get you the occupancy of actual employees and visitors.


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## omahawildcat (May 12, 2016)

Timo said:


> We have always calculated occupant loads based on use, per the Maximum Floor Area Allowance Per Occupant table*.  Code allows or requires you to classify small conference rooms as B business*, but that is totally separate issue, and should not be confused with the actual use of the space.


Where would this be stated in the code?


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## omahawildcat (May 12, 2016)

mark handler said:


> *If an assembly space is less than 750 sq. ft. or has an occupant load less than 50, then it can be classified as a Group B or as a part of the occupancy group in which it is located*.


Where is this located?


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## omahawildcat (May 12, 2016)

By the way, We are using 2006 IBC


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## cda (May 12, 2016)

omahawildcat said:


> Classifying a break room in a business occupancy as assembly is fairly stupid don't you think? The break room is only used by office employees. You are not going to have people coming off the street and filling up your break room. The whole use of gross square footage to calculate B occupancy is what I assumed would get you the occupancy of actual employees and visitors.


Not always

Some businesses will bring in out of town employees for training

Some will bring in general public for different functions 

And other


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## jar546 (May 12, 2016)

cda said:


> Not always
> 
> Some businesses will bring in out of town employees for training
> 
> ...



Very true, see it all the time and have been an occupant in someone else's building too.  This created an issue with bathrooms, HVAC comfort and safety.  We always base it on actual use which is what the IBC tells you to do.  There are, of course some exceptions.


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## cda (May 12, 2016)

*AREA, GROSS.* The floor area within the inside perimeter of the exterior walls of the building under consideration, exclusive of vent shafts and courts, without deduction for corridors, stairways, closets, the thickness of interior walls, columns or other features. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal projection of the roof or floor above. The gross floor area shall not include shafts with no openings or interior courts.*

FLOOR AREA, NET.* The actual occupied area not including unoccupied accessory areas such as corridors, stairways, toilet rooms, mechanical rooms and closets.


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## cda (May 12, 2016)

omahawildcat said:


> Where is this located?


*Assembly Group A. *

Assembly Group A occupancy includes, among others, the use of a building or structure, or a portion thereof, for the gathering of persons for purposes such as civic, social or religious functions; recreation, food or drink consumption; or awaiting transportation.

*Exceptions:*

1.  A building or tenant space used for assembly purposes with an occupant load of less than 50 persons shall be classified as a Group B occupancy.
2.  A room or space used for assembly purposes with an occupant load of less than 50 persons and accessory to another occupancy shall be classified as a Group B occupancy or as part of that occupancy.
3.  A room or space used for assembly purposes that is less than 750 square feet (70 m2) in area and is accessory to another occupancy shall be classified as a Group B occupancy or as part of that occupancy.


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## mark handler (May 12, 2016)

omahawildcat said:


> Where is this located?


In the code book try chap three


omahawildcat said:


> Where would this be stated in the code?


Try the code book chapter three


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## fatboy (May 12, 2016)

omahawildcat said:


> Classifying a break room in a business occupancy as assembly is fairly stupid don't you think? The break room is only used by office employees. You are not going to have people coming off the street and filling up your break room. The whole use of gross square footage to calculate B occupancy is what I assumed would get you the occupancy of actual employees and visitors.



Well, no, I don't believe it is "stupid", I try not to promote "stupid" codes. I have seen, been in, heard about, read about, saw on the news, meetings in buildings that were fully attended, if not over-attended, by folks that were not part of the group that normally occupy the building. To think that it doesn't happen, IMHO, is "stupid".

I am referring to conference/meeting rooms, break rooms are another story, not typically calculated separately.


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## JBI (May 12, 2016)

omahawildcat, Table 1004.1 is the key to establishing 'occupant load' correctly. That table looks at the 'use of the space' *not* the 'occupancy classification' of the building. Applying a 100 s.f. per occupant area in a conference room would be, in your words, fairly stupid. Similarly, applying a 15 s.f. per occupant area to an office within a restaurant would again be fairly stupid. The intent of Chapter 10 is to insure adequate minimum means of egress from any part of the building. That is hardly stupid at all.


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## mark handler (May 12, 2016)

JBI said:


> omahawildcat, Table 1004.1 is the key to establishing 'occupant load' correctly. That table looks at the 'use of the space' *not* the 'occupancy classification' of the building. Applying a 100 s.f. per occupant area in a conference room would be, in your words, fairly stupid. Similarly, applying a 15 s.f. per occupant area to an office within a restaurant would again be fairly stupid. The intent of Chapter 10 is to insure adequate minimum means of egress from any part of the building. That is hardly stupid at all.


Figuring occupancy  is different from figuring exiting

the original post "figured occupancy wrong" not exiting.


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## JBI (May 12, 2016)

mark handler said:


> Figuring occupancy  is different from figuring exiting
> 
> the original post "figured occupancy wrong" not exiting.



And the name of the post is 'figuring occupancy count'.


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## mark handler (May 13, 2016)

And the text in the post says different


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## RANDOM (May 13, 2016)

omahawildcat said:


> Classifying a break room in a business occupancy as assembly is fairly stupid don't you think? The break room is only used by office employees. You are not going to have people coming off the street and filling up your break room. The whole use of gross square footage to calculate B occupancy is what I assumed would get you the occupancy of actual employees and visitors.



The conference or break room -that alone would be an Assembly space-, can only become part of the primary area or main occupancy if the area of this particular room is less or equal to 10% of the main occupancy area. In this way the Assembly room becomes what the code calls "Accessory Occupancy". Code requirements will derive from the main occupancy.

If the accessory area is a daycare facility, it is less probable that the plan checker will accept it as accessory.


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## Builder Bob (May 16, 2016)

Chapter 10 is for occupant load to ensure adequate means of egress are provided for the individual spaces. Chapter 10 does not care about "Occupancy Classification" but rather the intended use of the space....

*SECTION 1001 ADMINISTRATION 

1001.1 General. *
Buildings or portions thereof shall be provided with a _means of egress_ system as required by this chapter. The provisions of this chapter shall control the design, construction and arrangement of _means of egress_ components required to provide an _approved means of egress_ from structures and portions thereof.

With that being said, I don't care when dealing with the means of egress (Chapter 10) if it an accessory, incidental, separated, or non-separated - Chapter 10 doesn't address the methodology of design for building area and height limitations.


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## JBI (May 16, 2016)

Looks like the OP does not want to clarify the exact issue - occupancy class of spaces or occupant load of spaces. 
Maybe omahawildcat will return to let us know what the problem is, and if it is now resolved.


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## ecf1618 (Jul 6, 2016)

I am trying to figure out this occupant load calculation issue as well and I am seeing mixed comments here about how to calculate occupant load for a building or space.  What method do you use to calculate total occupant load?  Do you use table 1004.1.2 "function of space" for each room and add them together?  Or do you group the entire office space square footage and divide it by 100? Thanks.


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## mtlogcabin (Jul 6, 2016)

1004.1.2 Areas without fixed seating.
The number of occupants shall be computed at the rate of one occupant per unit of area as prescribed in Table 1004.1.2.



erik1618 said:


> Do you use table 1004.1.2 "function of space" for each room and add them together?



Yes that is the correct way to calculate occupant load and egress requirements


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## cda (Jul 6, 2016)

erik1618 said:


> I am trying to figure out this occupant load calculation issue as well and I am seeing mixed comments here about how to calculate occupant load for a building or space.  What method do you use to calculate total occupant load?  Do you use table 1004.1.2 "function of space" for each room and add them together?  Or do you group the entire office space square footage and divide it by 100? Thanks.




Since I lost my easy linking ability

Also look at the definition of gross and now I forgot the other 

It is on the table


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## Builder Bob (Jul 7, 2016)

Yes the occupant load is calculated for each space for its intended use, then the sum of all these areas is the occupant load for the structure.

gone are the days of saying it is a business occupancy and using 100 gross for the SF of the building.


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## ecf1618 (Jul 7, 2016)

Builder Bob said:


> Yes the occupant load is calculated for each space for its intended use, then the sum of all these areas is the occupant load for the structure.
> 
> gone are the days of saying it is a business occupancy and using 100 gross for the SF of the building.



Thanks!  I have older architects tell me to use that method of "saying it is a business occupancy and using 100 gross for the SF of the building."  Was that how it was done in previous building codes before the IBC?  Like in the SBC?

Also, what is your opinion on break rooms and the occupant load factor in table 1004.1.2?  I am gravitating towards saying assembly with tables and chairs which would give it a 15 sf net load factor.  I am thinking this because the business does not have a conference room and if they were to have some kind event where additional people come into the building that are not employees (but employees are there working in their offices) they may use the break room to gather.  What do you think?


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## cda (Jul 7, 2016)

erik1618 said:


> Thanks!  I have older architects tell me to use that method of "saying it is a business occupancy and using 100 gross for the SF of the building."  Was that how it was done in previous building codes before the IBC?  Like in the SBC?
> 
> Also, what is your opinion on break rooms and the occupant load factor in table 1004.1.2?  I am gravitating towards saying assembly with tables and chairs which would give it a 15 sf net load factor.  I am thinking this because the business does not have a conference room and if they were to have some kind event where additional people come into the building that are not employees (but employees are there working in their offices) they may use the break room to gather.  What do you think?




Just be careful or the ahj will enforce assembly requirements do that room. If you can some how keep the occupant load under 50 do it, unless it is just obvious that it can hold more, such as showing 30 tables for training and 3 chairs per table.


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## ADAguy (Jul 7, 2016)

Stupid is, as stupid does.

How many exits do most elevators have? How many people can you pack in an elevator? Square footage does not always limit the number of occupants in a given area.

Break rooms when used for birthdays, donuts, etc. can often exceed the intended persons per square foot count (standing room only) yell "fire" and how many can get out in a timely fashion?

Exclusive of code good practice is to consider the total number of occupants within the tenant space vs the likelihood that they will all be in one room at the same time.
Code alone is not always a guarantee of survivability in the event of a mass evacuation from a single room.


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## JBI (Jul 7, 2016)

ADAguy, That's why the IBC allows for an increase in calculated occupant load as long as you don't go below 5 s.f. per person. 

Most properly, the spaces are analyzed individually for 'function' of space - so a conference room or break room is usually calculated at 15 s.f. per person to allow for tables and chairs with aisles between. The office areas are a 100 s.f. per person.


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## Builder Bob (Jul 7, 2016)

ALSO, the occupant load factor used in chapter 10 is to ensure that more adequate means of egress are used in the design of the structure......... OL for the structure may be debated... One of the hottest debates that went on for a while was the school gymnasium ---- which was often cited for school assemblies .... Which causes problems when the school is leased by a church for Sunday Services and causes egress problems due to security grates/grills being used to isolate the school from the public use Gymnasium....


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## ADAguy (Jul 7, 2016)

Good topic and discussion, thank you all.


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## steveray (Jul 8, 2016)

We run it space by space for egress, but if it comes down to a fixture count issue, I would have no issues lumping some small conference rooms at 100 per in a B as long as the egress works and they are actually doing "gross" correctly..In multi tenant buildings I see designers not assigning the common areas (corridors, bathrooms, mechanicals)to anyone and that is a problem.


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## JBI (Jul 8, 2016)

Corridors, bathrooms and mechanical rooms don't have an occupant load per se as they are not normally occupied within the context of the Code. 
For a 'gross' square footage calculation they get lumped in with the primary occupancy. 
For a 'net' calculation they are generally ignored (or subtracted out). 
The logic being that, for example, in an A2 Occupancy I can't put tables and chairs in the corridors, bathrooms, mechanical rooms and then use them as 'assembly space'.


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## ADAguy (Jul 8, 2016)

Interesting, though you "can't"/shouldn't put tables and chairs in corridors it doesn't mean that in after hour raves or during parties they won't.
Some never "get it".


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## steveray (Jul 8, 2016)

I have a new school coming in with a "corriteria"....must be a design thing!


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## ADAguy (Jul 8, 2016)

similar to a "cafetorium"/multiuse room


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