# How would you classify a Residential Lobby?



## kareemmidani (Apr 16, 2021)

Hello dear friends!
I am new to this forum so please bear with me! 
I'm working on a residential building, and we were asked by our professor to calculate the Occupancy Loads of each space.
And two things hit my mind with confusion.

1) Do I consider the "reception" of the lobby as occupancy Assembly and if so "Unconcentrated (Tables & Chairs)"?
2) My second concern is regarding the exit staircase and the exit discharge. Are those considered accessory to the upper Residential floor plans R-2 (if I'm not mistaken)?
Do I calculate them _with_ or _without _ the lobby.

I have attached a picture of my ground floor plan,
please share your thoughts,
thank you!  



__ https://www.pinterest.com/pin/504966176977150413/

P.S. If image is not visible, click here instead.


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## cda (Apr 16, 2021)

looks like a mixed up occupancy!!!

Which code and edition are you working with???  IBC or a NFPA ????

I guess kind of a question which space does the reception service????

I guess I would go with 5 net



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


I am not sure on question 2, but normally not worried about???


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## kareemmidani (Apr 16, 2021)

Oops, totally forgot to mention that I am working with IBC.
And yes, I'm working on a mix-use apartment building. This floor plan is a podium that consists of *three separated entrances*:
– One to the Apartments (where the Lobby + Reception hosts the space for Residential Units above)
– One to the Restaurant. (Assembly – A-3)
– One to the Supermarket. (Mercantile – M)

My second question is about the Emergency Staircase, if I were to classify the occupancy for the Lobby, do I include the staircases?
If not, what or how would the emergency staircases be classified as? If the floors above, are Residential (R-2).

Thank you


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## cda (Apr 16, 2021)

Well, never heard the question asked before.

I am thinking if any, would be what the major occupancy is R-2


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## mark handler (Apr 17, 2021)

The only portion of the "lobby" that has an occupancy is the reception.  1/150
the other areas are 1004.2.1 Intervening Spaces or Accessory Areas TABLE 1004.5


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## cda (Apr 17, 2021)

mark handler said:


> The only portion of the "lobby" that has an occupancy is the reception.  1/150
> the other areas are 1004.2.1 Intervening Spaces or Accessory Areas TABLE 1004.5



1/15?


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## e hilton (Apr 17, 2021)

Kareem ... this is your class assignment, why don’t you propose answers and let us tell you if you are correct.  Include cade sections to support your answer.


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## mark handler (Apr 19, 2021)

cda said:


> 1/15?


No I would classify it a business


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## cda (Apr 19, 2021)

mark handler said:


> No I would classify it a business



Sorry still in the *Hammurabi* edition,


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## Harrison Staab (Apr 19, 2021)

kareemmidani said:


> Hello dear friends!
> I am new to this forum so please bear with me!
> I'm working on a residential building, and we were asked by our professor to calculate the Occupancy Loads of each space.
> And two things hit my mind with confusion.
> ...


Hi Kareem!

Architect here. A few comments that may be helpful. (I assume IBC is used here)

Though you have two stairs, both exit the building via the same exit passageway to the exterior. You need to separate these. The stair on the right could egress through the Reception using the Lobby exception.
Assuming this is the level of discharge, the stair doors need to swing out, in the direction of egress. Think about what direction people are moving in an emergency and make the doors swing that way.
Your stairs also do not appear to have access to the lobby. Add doors to the Lobby "hall". I'd think this would be functionally useful (what if a user wants to take the stairs instead of the elevator, or worse, what if the elevators are broken?), and would provide additional means of egress.
Doors at the end of the Lobby hall to the ammenity?

To your questions:
1. Our firm has classified reception lobbies as R-2 (Chapter 3/5) with Unconcentrated Assembly (Chapter 10). This is the most conservative way to do it and it really depends on the AHJ.
2. The stairs are not "accessory" as defined in Chapter 5, but yes, they are considered R-2 (Chapter 3/5). For purposes of egress calculations (Chapter 10), you only need to calculate them by what spaces are using them. As designed, you lobby isn't even connected to them. The stairs are going to be sized based on the higher occupant load of either the largest level above/below or the sum of the convergence of levels immediately above and below. If you add doors to the lobby, you will need to size the doors based on the stair occupant load and the lobby.

Hope this is helpful. Best of luck to you in your studies!


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## ADAguy (Apr 19, 2021)

cda said:


> Sorry still in the *Hammurabi* edition,


Be "nice" with your responses


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## ADAguy (Apr 19, 2021)

as to stairs, Is the lobby area sprinklered? How many stories?


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## Paul Sweet (Apr 19, 2021)

You might consider the lobby as similar in function to a library reading room - one person per 50 SF.

Harrison Staab nailed it with the stairs.

Is the little room between the Service Room and Elevators a Lavatory?  You will need one for the Receptionist.


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