Dead end hallway subject to cumulative occupant load rules for number of exits?

[MrkDLGA]

I am under the 2019 CBC (California) (2018 IBC) for a plancheck I am working on. The following layout of a wing of a school building on the second floor. Common path of travel distances worked, so we didn't have a rated corridor, just a hallway as part of the exit access system. I am being told though that basically no dead end hallways of any length can serve more than one classroom because the cumulative occupant load rules would push the occupant load over 49 and that intervening room hallway would then require two exits. CBC 1006.2.1. Which makes sense, but it doesn't make sense because I could propose adding a dividing pony wall down the middle of that dead end hallway so that each half stays under 50 occupants. Same exit system and safety, just worse space. Its like I need to use the following exception 1: Vestibules, lobbies and foyers excepted, but "hallway" is a long way from those enumerated exceptions.

Any thoughts on if the hallway is allowed? Or any thoughts on the best way to reconfigure this?

 

[RLGA]

It is not an intervening space--it is a dead-end corridor subject to Section 1020.4. If it is more than 50 feet in length (if sprinklered) or its length is more than 2.5 its width, you must find a way to shorten the distance (i.e., move the doors closer to the main corridor).

 

[mtlogcabin]

Unless it is a California thing the occupant load has nothing to do with the dead end requirements. There is no such thing as a hallway in today's code. There are corridors which you have and aisle's which you do not have.

 

[Jay Smith]

The real question here seems to be whether this area complies with 1006.2.1.

 

[RLGA]

The real question here seems to be whether this area complies with 1006.2.1.

1006.2.1 is irrelevant for dead-end corridors.

 

[Jay Smith]

1006.2.1 is irrelevant for dead-end corridors.

The issue that is holding up the OP is not dead end corridors. It’s the number of exits for greater than 49 occupants in this space.

 

[Builder Bob]

If you divide the corridor in half, wouldnt you make the corridor 44" on each side of the additional 5" wide wall.

 

[RLGA]

The issue that is holding up the OP is not dead end corridors. It’s the number of exits for greater than 49 occupants in this space.

The issue is that they incorrectly considered a dead-end corridor an intervening room or space. A dead-end corridor is not an intervening room, area, or space but part of the corridor system.

This logic is supported by subparagraph 1 in Section 1006.1, which does not require the "number of exits from foyers, lobbies, vestibules, or similar spaces" to be determined by the cumulative occupant load egressing through them. These types of spaces would likely see occupant loads far greater than what this dead-end corridor is expected to handle, and they are not required to provide two or more means of egress. The reality is that this dead-end corridor functions similarly to that of a vestibule.

Additionally, refer to Section 1020.6, which states corridors (in this case, fire-resistance-rated corridors) "shall not be interrupted by intervening rooms." How can a portion of a corridor (rated or not) be considered an "intervening room" when it cannot be interrupted by intervening rooms?

The doors can be moved forward easily, but at what distance from the main corridor, in the OP's plan reviewer's mind, is it not an "intervening space"? There is nothing, so the code includes maximum lengths for dead-end corridors.

 

[Jay Smith]

The issue is that they incorrectly considered a dead-end corridor an intervening room or space. A dead-end corridor is not an intervening room, area, or space but part of the corridor system.

This logic is supported by subparagraph 1 in Section 1006.1, which does not require the "number of exits from foyers, lobbies, vestibules, or similar spaces" to be determined by the cumulative occupant load egressing through them. These types of spaces would likely see occupant loads far greater than what this dead-end corridor is expected to handle, and they are not required to provide two or more means of egress. The reality is that this dead-end corridor functions similarly to that of a vestibule.

Additionally, refer to Section 1020.6, which states corridors (in this case, fire-resistance-rated corridors) "shall not be interrupted by intervening rooms." How can a portion of a corridor (rated or not) be considered an "intervening room" when it cannot be interrupted by intervening rooms?

The doors can be moved forward easily, but at what distance from the main corridor, in the OP's plan reviewer's mind, is it not an "intervening space"? There is nothing, so the code includes maximum lengths for dead-end corridors.

Thank you. I was hoping you‘d explain that aspect of it.

 

[MrkDLGA]

Thank you all for your debate on this. I do comply with the dead end corridor length, and I do agree with you that it is a corridor- with 0 hour rating in this case. Maybe I can preserve the plan with your arguments.
It gets a little harrier on the other floor, where the client asked for a double classroom with a divider. We provided two exits from that space to the corridor, as I have done on other school projects. The rub is they they both need to enter that dead end corridor because of the configuration of an office blocking access to any other part of the corridor. I can see arguing that this is a corridor and no other rules should apply: as long as I comply with its required width, rating, dead end length, common path of travel length rules, there are no further rules that require a particular configuration for the corridor. What are your thoughts on this?

 

[RLGA]

Thank you all for your debate on this. I do comply with the dead end corridor length, and I do agree with you that it is a corridor- with 0 hour rating in this case. Maybe I can preserve the plan with your arguments.
It gets a little harrier on the other floor, where the client asked for a double classroom with a divider. We provided two exits from that space to the corridor, as I have done on other school projects. The rub is they they both need to enter that dead end corridor because of the configuration of an office blocking access to any other part of the corridor. I can see arguing that this is a corridor and no other rules should apply: as long as I comply with its required width, rating, dead end length, common path of travel length rules, there are no further rules that require a particular configuration for the corridor. What are your thoughts on this?

The classroom in the lower right corner would not comply since you are creating merging paths. Thus, you have a single common path of egress travel. Could Office B be shortened on the right-hand side to allow egress directly to the main corridor?

 

[MrkDLGA]

To be a devil's advocate I generated another sketch dividing the double classroom into two classrooms, but leaving the configuration with the office. Both this sketch and the previous sketch have exactly the same amount of people being served by the corridor, and the same amount of occupants in the overall space. I can't see why one would be safe, and the other not safe?
I think we either have to believe or not that a space is an occupied room, versus a corridor which is something that is not a space.
1006.2 only speaks about a requirement for multiple exits or exit access doors for larger occupancy spaces, but does not add a requirement for a second travel path for the exit access. My understanding from code interpretation articles is that requirement comes from the risk inside that larger, more occupied space (such as a fire in front of the door). Providing two exit access doorways mitigates that risk to that large group of people. There is not the same risk inside the corridor, as it does not have any occupancy and is dedicated for exiting. The language in 1007 further enumerates the requirement for multiple "exits, exit access doorways, and exit access ramps and stairs" but does not list travel paths.
Are there other code sections that I should be looking at that add the requirement for multiple travel paths (I comply with the common exit path length rules)?
I think the plan checker is using the intermediate space rule to enforce multiple paths (as plan checkers always like to have the most broad reading of any unclear part of the code), but I don't know of any code section that specifically requires multiple paths within the exit access system (beyond the common path distance rule).
Thank you for your thoughts on this.

 

[RLGA]

My old-school thinking may be showing. The definition of CPET was rewritten in the 2015 edition and then again in the 2018 edition. I like the 2012 definition, which my comment addresses. The 2015 definition muddied things a little (deleted the reference to merging paths but referred to "within a story") and added exit access doorways. The 2018 edition removed "within a story" and replaced it with "of each room, area, or space." If the intent was to provide the situation as you have presented, they should have added at the end of the definition, "within each room, area or space."

The main problem with the current definition is that you are no longer required to provide separate paths to different exits. The section now allows you to measure up to two exit access doorways, regardless of what happens beyond those doorways. Although adding the wall between the two classrooms shows a contradiction in my interpretation, the code requires compliance with the worst-case situation and establishes a different set of criteria. So if the rooms had an operable partition that creates a larger room with an occupant load that exceeds the allowable load for a single means of egress, providing the doorways as shown does not improve the safety intended by the separation requirements of Section 1007.1.1. The entire purpose of the CPET was to avoid trapping a large group of people in a single space.

You can submit what you have shown, but please don't be surprised if they reject it for the same or similar reasons I have stated above.