Exiting question. California CBC 2019

[JPohling]

I will try and paint a picture of my scenario in a way that I can get some solid answers. Long narrow two story building. There are three exit stairs. One at each end of the building connected to each other with a corridor. There is a central two story open area with a open stair and elevator smack in the middle of the building/corridor. The building was originally designed to have an occupant load on the floor of more than 500 persons, hence the 3 exit stairs.

Have a tenant that will take the entire end of the building just beyond the atrium. This tenant area will now have one of the exit stairs internal to them and no other tenants will be able to access this stair. This large tenant will exit down their internal stair along with going out the other direction thru the corridor and down the open stair within the two story open area. All exiting travel distances work.

The remaining tenants on the floor all have access to the other enclosed exit stair as well as the open stair in the center thru the rated corridor. Everyone has access to two stairs and all travel distances are in compliance. I do not see an issue with this exiting concept at all.

A fire marshal is insisting that this proposed large tenant cannot capture the one exit stair and make it unavailable for the rest of the tenants on the floor. he quotes this section.
Section 1001.2: It shall be unlawful to alter a building or structure in a manner that will reduce the number of exits or the capacity of the means of egress to less than required by this code. I do not believe what we are proposing creates a situation that is "less than required by this code"

My concern that I would like more clarification on is based upon CBC Table 1006.3.2 "Minimum number of exits or access to exits" for an occupant load of 501- 1000 that requirement is 3. We have 3 stairs. I do not believe that all three stairs need to be available to everyone on the floor, but I cannot find code language that would clarify this.

That are your thoughts?

 

[Joe.B]

Does part of the proposed improvements include a fire separation? That might be what sways the fire marshal into reconsidering their position.

 

[JPohling]

We have 2 assembly meeting rooms that are separated by a 1 hour occupancy separation within the suite. Not sure what your getting at?

 

[Joe.B]

I'm just imagining the fire marshal is looking at the building as one "building" and if you show that there is a true occupancy separation maybe they will look at it differently.

 

[JPohling]

Gotcha! no, it is a single building. I have not seen any code language that would indicate for instance that one of the other tenants in the other side of the building that for conversation sake is a 2,000 SF tenant would need to have access to all three of the stairs. That is the issue. These other tenants are all able to access two stairs properly. For some reason the fire marshal is thinking that if the building has x amount of stairs then everyone need to get to x amount of stairs when only two would be required per code.....................

 

[Joe.B]

I guess this is where my mind is going:

503.1 General

Unless otherwise specifically modified in Chapter 4 and this chapter, building height, number of stories and building area shall not exceed the limits specified in Sections 504 and 506 based on the type of construction as determined by Section 602 and the occupancies as determined by Section 302 except as modified hereafter. Building height, number of stories and building area provisions shall be applied independently. For the purposes of determining area limitations, height limitations and type of construction, each portion of a building separated by one or more fire walls complying with Section 706 shall be considered to be a separate building.

504.2 Mixed Occupancy

In a building containing mixed occupancies in accordance with Section 508, no individual occupancy shall exceed the height and number of story limits specified in this section for the applicable occupancies.

1004.1 Design Occupant Load

In determining means of egress requirements, the number of occupants for whom means of egress facilities are provided shall be determined in accordance with this section.

1004.4 Multiple Occupancies

Where a building contains two or more occupancies, the means of egress requirements shall apply to each portion of the building based on the occupancy of that space. Where two or more occupancies utilize portions of the same means of egress system, those egress components shall meet the more stringent requirements of all occupancies that are served.

I think that if you can show the fire marshal that you are dealing with two distinctly separate occupancies they will come around.

 

[JPohling]

This is a B occupancy office building, with a couple A meeting rooms within our large suite. There is no issue with the occupancies and or separation or anything like that.

This all hinges on the FM believing that if there are 3 stairs in the building that all tenants on the floor need access to all 3 stairs and that is the issue. I see no code language that would support that idea. A floor plate with 501-1000 occupants needs to have 3 exit stairs from the floor. I see nothing that would require that if you have a bunch of smaller suites on the floor that they all would need access to the 3 stairs.

 

[Paul Sweet]

What happens if they do this and somebody else wants to do the same thing to most of the other side of the building? That leaves the people in the middle with only one open (exit access) stairway.

 

[JPohling]

What happens if they do this and somebody else wants to do the same thing to most of the other side of the building? That leaves the people in the middle with only one open (exit access) stairway.

If they were to do exactly what we are proposing then it would be completely acceptable and properly exiting as they would have their own internal stair along with the common area open stair. What could not happen would be anything less than the full tenant on each side as you would need to maintain access to the second stair for the other tenant. First come first served.

 

[Joe.B]

This is a B occupancy office building, with a couple A meeting rooms within our large suite. There is no issue with the occupancies and or separation or anything like that.

This all hinges on the FM believing that if there are 3 stairs in the building that all tenants on the floor need access to all 3 stairs and that is the issue. I see no code language that would support that idea. A floor plate with 501-1000 occupants needs to have 3 exit stairs from the floor. I see nothing that would require that if you have a bunch of smaller suites on the floor that they all would need access to the 3 stairs.

I agree, there are no issues with what you're proposing, except that the FM disagrees. It sounds to me like you just need to show the FM how this complies with code, so I was giving you a couple of code sections that demonstrate how your proposal meets code. I thought that's what you were asking for...