Multiple Stories Occupant Loads

[EasilyConfused]

Renovating the 1st floor of a two story building.

Can someone explain how occupant loads from the 2nd floor impact the 1st floor to me?

The exit corridor & exits obviously need to be sized to handle everyone in the building. Is it a simple as adding the occupant loads of of both the 1st and 2nd floors and sizing corridors and exit doors to be able to handle the combined occupant load? Splitting the combined occupant load between doors (say 3 or whatever required) so that each door would allow for it's portion of the load?

Thanks

 

[mtlogcabin]

Can someone explain how occupant loads from the 2nd floor impact the 1st floor to me?

Normally an upper floor will not impact a lower floor. The code addresses it in a couple of areas

1005.4 Continuity.

The capacity of the means of egress required from any story of a building shall not be reduced along the path of egress travel until arrival at the public way.

1005.6 Egress convergence.

Where the means of egress from stories above and below converge at an intermediate level, the capacity of the means of egress from the point of convergence shall not be less than the sum of the required capacities for the two adjacent stories.

1004.1.1 Cumulative occupant loads.

Where the path of egress travel includes intervening rooms, areas or spaces, cumulative occupant loads shall be determined in accordance with this section.

1004.1.1.1 Intervening spaces.

Where occupants egress from one room, area or space through another, the design occupant load shall be based on the cumulative occupant loads of all rooms, areas or spaces to that point along the path of egress travel.

1004.1.1.2 Adjacent levels.

The occupant load of a mezzanine or story with egress through a room, area or space on an adjacent level shall be added to the occupant load of that room, area or space.

 

[EasilyConfused]

So, the reality of it is design egress for each floor individually? As if the 2nd floor occupant load doesn't even exist?

Any idea how the code has come to terms with this?

 

[cda]

1st floor people are presumed gone by the time the 2nd floor makes it down? I think

 

[cda]

There is convergence sometimes :::

http://publicecodes.cyberregs.com/icod/ibc/2009f2cc/icod_ibc_2009f2cc_10_par021.htm?bu2=undefined

 

[Paul Sweet]

CDA has it - people from one floor are presumed gone by the time the next floor makes it down. The exception is if you have a stair from a basement and a stair from upstairs discharging through the same door or passage (convergence). Then you add the people coming up from the people going down.

 

[EasilyConfused]

CDA & Paul- That actually makes sense. Glad I asked. Thanks.