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Corridor question

C

cda

SAWHORSE
Joined
Oct 19, 2009
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Basement
Have seen this posted twice recently, using different scenarios.

Is there a code section that supports it???



"""50/50 split in the capacity, with 1/2 going one direction and the other 1/2 going the other direction,""""


As in if the occupant load of the building is say 58, does the code support splitting that number so say a rated corridor is not needed.
Because 29 go one way and 29 the other??

Just wonder how you herd people so they split evenly???
 
YES....It's not like we are doing timed release or something like that where we can guarantee that there will only be 29 at a time in it. If 2 15 person rooms enter it, regardless of which direction they might be likely to head, rate it or sprinkler it...Let's not confuse or blend CPET and OL.
 
Thanks just trying to see where the code support is for:::



""50/50 split in the capacity, with 1/2 going one direction and the other 1/2 going the other direction,""""
 
None - it is strictly a matter of interpretation of how to apply "corridor serving 30 " , I know from NFPA Fire and Life Safety Plan Review Class this was presented back in the 80's as the methodology for applying the "serving" quotation of the code.
The SBCCI Commentary also supported this interpretation back in the day and gradually was morphed out of commentaries and written interpretations from the Code Making Authority.
 
Builder Bob said:
None - it is strictly a matter of interpretation of how to apply "corridor serving 30 " , I know from NFPA Fire and Life Safety Plan Review Class this was presented back in the 80's as the methodology for applying the "serving" quotation of the code.
The SBCCI Commentary also supported this interpretation back in the day and gradually was morphed out of commentaries and written interpretations from the Code Making Authority.
Click to expand...


Thanks

Always wonder how you herd people one way and some the other.

Especially when the clown is chasing after them with a horn.
 
So if you have two required exits and you are calculating exit width for your various components you do not use 1/2 of the occupant load? of course you do!
 
JPohling said:
So if you have two required exits and you are calculating exit width for your various components you do not use 1/2 of the occupant load? of course you do!
Click to expand...

Yes when applying required exit width and number of required exits.

But does that extend to " occupant load served by corridor " ????

Where is the code to back it
 
wish I could find it, but same logic prevails..............how do you herd only half thru each component? why is that allowed?
 
Not if the lead cow is calm and people in the queue are not subjected to additional signs of fire like heat or smoke obscuration. There are some great Human Behavior studies available from the late Guylene Proulx and Dr. John L Bryan.
 
Corridor width is not necessarily a function of 'emergency' evacuation. It may be that everyone enters and exits through the front door during the normal course of occupancy. The second means of egress or second exit is often primarily or predominantly for 'emergency' situations.
 
A corridor with 2 doors is different than just a corridor...a corridor with 30 people in it is just that, can you say that 15 go each way so that your doors work. YES, but you can't say the corridor only has an OL of 15 because there are 2 doors to chose from with 30 people....
 
JBI said:
Corridor width is not necessarily a function of 'emergency' evacuation. It may be that everyone enters and exits through the front door during the normal course of occupancy. The second means of egress or second exit is often primarily or predominantly for 'emergency' situations.
Click to expand...



Where does it say

"emergency exit" in the IBC

OR

"Fire Exit"

I hate those terms being used, and one of these days by golly, I am going to introduce a code section to ban them!!!!





I would say any additional exit width required, is for minimum to get the "occupant load" served by the Egress system out of the building.

As in Rhode Island Night club???
 
cda said:
Yes when applying required exit width and number of required exits.

But does that extend to " occupant load served by corridor " ????

Where is the code to back it
Click to expand...

1005.5. Distribution of egress capacity.
Where more than one exit, or access to more than one exit, is required, the means of egress shall be configured such that the loss of any one exit, or access to one exit, shall not reduce the available capacity to less than 50 percent of the required capacity.

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.

CORRIDOR. An enclosed exit access component that defines and provides a path of egress travel.

Basically a corridor is nothing more than an intervening space that must be traversed to reach an exit. The above sections are where you go to back up the reasons for determining occupant loads for a corridor and then requiring exits sized upon 1/2 the occupant load in the corridor going each direction
 
mtlogcabin said:
1005.5. Distribution of egress capacity.
Where more than one exit, or access to more than one exit, is required, the means of egress shall be configured such that the loss of any one exit, or access to one exit, shall not reduce the available capacity to less than 50 percent of the required capacity.

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.

CORRIDOR. An enclosed exit access component that defines and provides a path of egress travel.

Basically a corridor is nothing more than an intervening space that must be traversed to reach an exit. The above sections are where you go to back up the reasons for determining occupant loads for a corridor and then requiring exits sized upon 1/2 the occupant load in the corridor going each direction
Click to expand...


Where does it say 1/2 occupant load going each way??
 
It is a given mathematical equation when the second exit has to accommodate 50% or 1/2 of the OL
How else can you meet 1005.5. where there are only 2 exits provided?
 
cda said:
Where does it say

"emergency exit" in the IBC

OR

"Fire Exit"

I hate those terms being used, and one of these days by golly, I am going to introduce a code section to ban them!!!!

I would say any additional exit width required, is for minimum to get the "occupant load" served by the Egress system out of the building.
As in Rhode Island Night club???
Click to expand...

And I didn't use those terms, so I'm not sure why you quoted me... unless it was to misquote me?
 
mtlogcabin said:
It is a given mathematical equation when the second exit has to accommodate 50% or 1/2 of the OL
How else can you meet 1005.5. where there are only 2 exits provided?
Click to expand...



Where does it say 1/2 occupant load going each way??

Agree with your statement there, but that is just a performance item.


If you had four required exits, you would have to accommodate 50 % through them. and the width would be spread out.
 
Yes, if you can meet 2012 IBC, 1021.2 exception #1 - show the areas of the 50/50 split and the associated single exit required.


1021.2 Exits from stories.
Two exits, or exit access stairways or ramps providing access to exits, from any story or occupied roof shall be provided where one of the following conditions exists:
1. The occupant load or number of dwelling units exceeds one of the values in Table 1021.2(1) or 1021.2(2).
2. The exit access travel distance exceeds that specified in Table 1021.2(1) or 1021.2(2) as determined in accordance with the provisions of Section 1016.1.
3. Helistop landing areas located on buildings or structures shall be provided with two exits, or exit access stairways or ramps providing access to exits.

Exceptions:
1. Rooms, areas and spaces complying with Section 1015.1 with exits that discharge directly to the exterior at the level of exit discharge, are permitted to have one exit.
 
My bottom line I think is

If you have a non sprinkled building

A corridor

An occupant load of 30 using that corridor

You cannot say 15 will go one way and 15 will go another way

There for I do Not have to rate the corridor

You do.

It serves 30
 
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