Exit discharge convergence- Total Occupant Load

[damstein]

Can anyone please clarify if an exterior exit door serving a stair from floor above and basement also needs to include 1st floor occupant load passing through stair enclosure?

 

[RLGA]

The door must have the capacity for the largest of these two conditions:

1. The occupants of the first story; or
2. The sum of the occupants from the second story and the basement.

 

[sfred]

The door must have the capacity for the largest of these two conditions:

1. The occupants of the first story; or
2. The sum of the occupants from the second story and the basement.

Agreed. The reasoning is that the 1st floor occupants have already left the building before the occupants on the 2nd floor or basement have arrived. They aren't all converging at the same time

 

[damstein]

Great - That was my reading for section 1005.6 and the Commentary as well.

Thanks guys!

 

[walker.t]

The door must have the capacity for the largest of these two conditions:

1. The occupants of the first story; or
2. The sum of the occupants from the second story and the basement.

I’m picturing the stairs in a stair tower converging at the first floor, doors from the first floor opening into the stair tower, then everyone egressing through separate doors to the exterior. In such an arrangement, why wouldn’t 1004.2.1 (Intervening Spaces or Accessory Areas) apply? This would require that we take the sum of the first floor occupants and the combined occupant load of the converging stairs.

IBC 1004.2.1 Intervening Spaces or Accessory Areas. Where occupants egress from one or more rooms, areas or spaces through others, the design occupant load shall be the combined occupant load of interconnected accessory or intervening spaces. Design of egress path capacity shall be based on the cumulative portion of occupant loads of all rooms, areas or spaces to that point along the path of egress travel.

Great - That was my reading for section 1005.6 and the Commentary as well.

I don’t see how 1005.6 supports that interpretation, it is only making reference to the stairs and ramps that are converging, not to the occupant load on the level of convergence.

IBC 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 be not less than the largest minimum width or the sum of the required capacities for the stairways or ramps serving the two adjacent stories, whichever is larger.