IBC 2009 Assembly Exits

[annoyitated]

I have attached a diagram and am curious as to the required width of Corridor A and Corridor B. My reading of 1028.3 Exception is that they would need to dispersed and accommodate 100 percent of the required width. Both Sections 1028.2 and 1028.3 discuss distribution of exits but not really how to get there. Section 1018.2 would require Corridor A and B to be sized according the spaces they serve, but what is that determination?

Is it accommodating all 406 occupants?

Is it to accommodate 300 occupants from the two spaces it serves directly?

Is it to accommodate the 300 occupants plus half of the 106 from the third space (takes into account a fire could disable egress to one of the exits from that space)?

 

[cda]

What floor is this on??

Not an exit person but I am thinking the corridor has to handle half of the ol from the 180 room and 120 room


Other than that looks good

 

[annoyitated]

What floor is this on??

Not an exit person but I am thinking the corridor has to handle half of the ol from the 180 room and 120 room


Other than that looks good

Third floor.

 

[annoyitated]

So, let me add a wrinkle to that diagram. If we were to add an addition that surcharged that corridor, what would be the new occupancy load for that corridor?

Would it be 1/2 of the 300 + 1/3 of the 700 (assuming the stairs are taking a third of the 700 as well)?

Or would it be 1/2 of the 300 + 1/4 of the 700 since they can go either way at that point?

 

[annoyitated]

My AHJ is asking that we design the Corridor A and B widths to accommodate the 406 floor occupants plus the 234 occupants from Space Z occupants as they read the commentary of 1018.2 to read specifically "the total occupant load served by a corridor is not split to establish the corridor fire-resistance rating or capacity". My argument is that the two corridors do not serve Space W but rather only X and Y. Additionally, I have always believed similar to The Code Corner No. 22 Egress Width (attached for convenience) description of how to calculate the egress components was a matter of division similar to Space Z's calculation of 700/3. If i treated the calculation of the floor in a similar manner where does the code (not commentary) tell me that i can't simply divide provide 1/3 of the egress capacity down Corridors A and B to the Stair?

 

[cda]

The exit width should be as evenly distributed as possible among the required exits. At no time should the loss of one egress path diminish the egress capacity by 50%. Therefore, with buildings requiring only two exits, each exit must handle 50% or more of the occupants. For buildings requiring three exits, the egress width of any two exits must handle 50% or more of the occupants.