Convoluted MOE

[Sifu]

Not sure how well you can see this but I have a lot of concerns with this exit strategy. I am having trouble even articulating my concerns.

There are obvious issues that can probably be corrected but the concept has me stumped. Hoping some MOE experts can weigh in. The problems stem from a lack of exit capacity at the center stair/core area of the building. I think the only way they can even get close to it working is to "herd" the occupants in unequal numbers to the far exits on each side. I think this presents a problem when the loss of the remote located exits are lost and the double egress door must accommodate not less than 50%. The double egress door is not the issue, per se, but the stair door is, it would be too small if even 1 more person is added from either side. (I know it's too small as shown but that is secondary to the main concerns). So the only other option is to then send them across the opposite assembly space, which is an intervening space concern, as well as a cumulative occupant load question. Each of the large assembly spaces must also be an exit from the center core, which is why they have the double egress door, but they don't even show the number of occupants. I can't wrap my head around this. They are either directing hundreds of people down a single undersized exit stair, or making them run across to the other side, which may be an EATD issue (if the stair can't be considered because it is at capacity). I would love to find a compliance path but it feels so wrong I may be having a mental bock.

I had a meeting with the DP about this months ago in a "pre-submittal" meeting and voiced lots of concerns. This is what has now been submitted, and I am lost.
4 story type IIIB, R2 over 2 story IA, S-2 podium, some A and B sprinkled in, NFPA 13, mixed use separated. The pool/amenity areas are on the 3rd level and open to the air.

Let'er rip.

 

[JPohling]

going to need more than one floor and larger and clearer plans to take a stab at it, but I think I am seeing 240 occupants pointed toward a 36" door at one center stair and that is not gonna work so that makes the rest suspect

 

[Sifu]

going to need more than one floor and larger and clearer plans to take a stab at it, but I think I am seeing 240 occupants pointed toward a 36" door at one center stair and that is not gonna work so that makes the rest suspect

Yes, that is an obvious issue, and the architect has been made aware, the bigger question is the possibility that they are actually going to have more than the 240 as depicted if the unequal distribution isn't valid. If it is valid, then they could just decrease the number of occupants through the double egress doors and get the number down to fit the clear opening. But that is the big question for me. They have selected the number of occupants egressing through that door to fit the stair door (they just didn't do it correctly), but I am not sure that is valid. If it is, how far down could they go? Two exits are required, can it be designed so that 0 occupants are calculated at one of them? I know of no code that requires any sort of distribution ratio for two exits, other than the 50% rule. In this case, if more than the 75 use that door under duress, they will cause the door to be overloaded. And the same applies to the other side. I am having real problems articulating my concern. I guess it is that if the loss of the far left exit access door occurs they will not be overloading the double egress door, but they will be overloading the stair door, and the only answer to this is that they egress through the other side, which to me is even messier. I see a real bottleneck.

The floors below are parking and some R2, the floors above are all R2. The central stair discharges at the main lobby using the exit discharge provisions, the two remote stairs (left and right) discharge to the exterior via exit passageways. I haven't found any serious issues up to this floor, and don't expect any above. This floor is the issue...but I am only in to page 10 of 400 or so, so the jury is still out. I am concerned here because if I can't find a path to compliance it might be a gamechanger.

 

[steveray]

We always split evenly (no real basis though other than logic), and then this....

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 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.

 

[BayPointArchitect]

2012 IBC 1004.1.2 Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.

I remember reading an ICC statistic where a typical apartment has 2.5 occupants. However, I see that most of these units are rounded up to 4 people and some units are calculated at 7. Is this being designed for a fraternity or student housing? As the building official, you might want to ask the DP to introduce some added safety feature that would achieve an equivalent level of safety.

 

[Sifu]

2012 IBC 1004.1.2 Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.

I remember reading an ICC statistic where a typical apartment has 2.5 occupants. However, I see that most of these units are rounded up to 4 people and some units are calculated at 7. Is this being designed for a fraternity or student housing? As the building official, you might want to ask the DP to introduce some added safety feature that would achieve an equivalent level of safety.

Not a frat or student housing. Plain old R2. As far a as reduced load, it is up to them to ask, which they already did and were given some leeway, to the tune of about 200 occupants.

 

[Yikes]

Sorry, it's hard for me to read at small scale. Is there a horizontal exit in there somewhere?

 

[Sifu]

Sorry, it's hard for me to read at small scale. Is there a horizontal exit in there somewhere?

Yes, it is the thicker red line just right of center. The building requires a fire wall because of area limitations. The horizontal exit is there because they are so overloaded on their stairs they needed it. It is a double serving as the fire wall in accordance with NFPA 221. The issue is the fact that they are "directing" everyone from the main residential corridor to the Horizontal exit because they can't fit any more through the stairs due to the huge occupant loads from the pool and A use areas, which are also be "directed" to other exits.