Number of Exits - Based on Converging Occupant Loads?

[nealderidder]

Consider a building with two stories above grade and one story below. We'll call them 2FL, Ground Floor and Basement. Each floor has an occupant load of 251. Where 2FL and Basement converge at the ground floor I use a combined load of 502 to determine egress width per CBC 1005.6.

At the ground floor, do I use that floor's 251 occupants to determine the number of exits required per 1006 or do I use the converging occupant load of 502, which would require one additional exit?

 

[classicT]

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.

 

[nealderidder]

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.

Right, but that says nothing about number of exits, it only tells me how much width is required from that point to an exit.

 

[classicT]

What type of stairway is it? Exit access, interior exit stairway, or exterior exit stairway?

If it is either an interior or exterior exit stairway, you have already entered the exit, so all you have left is the exit discharge, which needs to be sized appropriately.

 

[nealderidder]

What type of stairway is it? Exit access, interior exit stairway, or exterior exit stairway?

If it is either an interior or exterior exit stairway, you have already entered the exit, so all you have left is the exit discharge, which needs to be sized appropriately.

That's the tricky bit, two exit access stairs. Exit access distance is short enough to allow it.

 

[classicT]

Ok, so is your concern Section 1006.3.2? If so, take note that the left column is occupant load per story. The occupant load of the upper story would not be added to the main level.

1006.3.2 Egress Based on Occupant Load
Each story and occupied roof shall have the minimum number of separate and distinct exits, or access to exits, as specified in Table 1006.3.2. A single exit or access to a single exit shall be permitted in accordance with Section 1006.3.3. The required number of exits, or exit access stairways or ramps providing access to exits, from any story or occupied roof shall be maintained until arrival at the exit discharge or a public way.

TABLE 1006.3.2
MINIMUM NUMBER OF EXITS OR ACCESS TO EXITS PER STORY​

OCCUPANT LOAD PER STORY​	MINIMUM NUMBER OF EXITS OR ACCESS TO EXITS FROM STORY​
1-500​	2​
501-1,000​	3​
More than 1,000​	4​

 

[nealderidder]

Ok, so is your concern Section 1006.3.2? If so, take note that the left column is occupant load per story. The occupant load of the upper story would not be added to the main level.

1006.3.2 Egress Based on Occupant Load
Each story and occupied roof shall have the minimum number of separate and distinct exits, or access to exits, as specified in Table 1006.3.2. A single exit or access to a single exit shall be permitted in accordance with Section 1006.3.3. The required number of exits, or exit access stairways or ramps providing access to exits, from any story or occupied roof shall be maintained until arrival at the exit discharge or a public way.

TABLE 1006.3.2
MINIMUM NUMBER OF EXITS OR ACCESS TO EXITS PER STORY​

OCCUPANT LOAD PER STORY​	MINIMUM NUMBER OF EXITS OR ACCESS TO EXITS FROM STORY​
1-500​	2​
501-1,000​	3​
More than 1,000​	4​

Aha! That certainly seems to say I don't need to consider converging occupant loads to determine number of exits from that story. Thanks T!

 

[steveray]

Yep...agree....

 

[Paul Sweet]

Converging occupants don't trigger additional separate exits, but they probably require wider (or more) doors at that exit to meet the required total width.

 

[bill1952]

In the example given - half of two floors through each of two exits - and total is over 500 - I don't believe two exits is enough.

 

[Paul Sweet]

Table 1006.3.2 bases the number of exits on occupant load PER STORY (posts #6 & 7).