Number of exits 1

[sprinkler1000]

The number of exits required is based on the occupant load.
When we are dealing with a multistory building, and enclosed staircases, there is no doubt that each enclosed staircase is an exit.
But, sometimes, when we deal with buildings with few floors, is common to have stairs that are not enclosed, but are access to exits in other floor below.

The question is, are the number of exits required by code (NFPA 101 or IBC), required on a floor by floor basis?
When a stair leads to an exit in a floor below, is it ok if we count it as an exit to comply with the number of exits required, as it is a way to reach an exit?

 

[cdafd]

There are a few more variables involved.

One is are you talking brand new or existing?

 

[sprinkler1000]

In my case is new building.
I didnt know that code had different criteria for number of exits, if it is either new or existing.

 

[cdafd]

With new , hopefully there was a building plan review and the editing is correct


On existing, the exiting should have met the code adopted at the time the building was built. So, what you see would depend on year built and brand of code used. Plus, exiting configuration requirements have changed over the years.

I don't know if you can rephrase your question for a better answer.

If I state it correctly the exit stairs have to handle the largest occupant load, but if that is say on the third floor of a six story building, it only applies from third floor down

Like I said a lot of variables to your first question

 

[stookeyfpe]

Review this before you go any further in MOE (means of egress) analysis.

http://www.slideshare.net/richlux/building-code-egress

 

[sprinkler1000]

Thanks both for taking the time to reply.

I have come to the conclusion that an open stair that leads to an exit in other floor below, as long as the capacity and the máximum travel distance is not exceded, count as an exit when cheking compliance with number of exits.

 

[cdafd]

I know you are trying to learn about exits.

But why the question?/ A building you office out of or one you are working in??


In a building, soemtimes you can have one floor open to the next, via an open stair,

this is from the IBC

Exceptions:
1. In all occupancies, other than Group H and I occupancies,
a stairway is not required to be enclosed when
the stairway serves an occupant load of less than 10
and the stairway complies with either Item 1.1 or 1.2.
In all cases, the maximum number of connecting open
stories shall not exceed two.
1.1. The stairway is open to not more than one
story above its level of exit discharge; or
1.2. The stairway is open to not more than one
story below its level of exit discharge.

 

[sprinkler1000]

We are working with the architects trying to design the exits in a new building they are designing, to comply with NFPA 101.

Regarding your comment (I could not find the ítem in IBC 2009 that limits the occupant load to 10 people), the ítem 1021.1 exception Nº3 allows exit access stairways to count as exit.

Let me give the example to clarify my doubt:

new building sprinklered, with two floors (ground floor and first floor)
Occupant load 600 in each floor.
On the first floor we have two exits that lead to outside and one open or enclosed stairway that leads to ground floor (not directly to outside) and exit through it.

On the ground floor we have three exits.

Capacity of means of egress and máximum travel distances are in compliance.

My concern is if the first floor is complying with the number of exits required since only two exits are provided in that floor, and code requires three when occupant load excedes 500.

 

[sprinkler1000]

I forgot to clarify. The questions are related to a real work case.

 

[cdafd]

SECTION 1022
EXIT ENCLOSURES
1022.1 Enclosures required. Interior exit stairways and interior
exit ramps shall be enclosed with fire barriers constructed
in accordance with Section 707 or horizontal assemblies constructed
in accordance with Section 712, or both. Exit enclosures
shall have a fire-resistance rating of not less than 2 hours
where connecting four stories or more and not less than 1 hour
where connecting less than four stories. The number of stories
connected by the exit enclosure shall include any basements
but not any mezzanines. Exit enclosures shall have a fire-resistance
rating not less than the floor assembly penetrated, but
need not exceed 2 hours. Exit enclosures shall lead directly to
the exterior of the building or shall be extended to the exterior
of the building with an exit passageway conforming to the
requirements of Section 1023, except as permitted in Section
1027.1. An exit enclosure shall not be used for any purpose
other than means of egress.
Exceptions:
1. In all occupancies, other than GroupHand I occupancies,
a stairway is not required to be enclosed when
the stairway serves an occupant load of less than 10
and the stairway complies with either Item 1.1 or 1.2.
In all cases, the maximum number of connecting open
stories shall not exceed two.
1.1. The stairway is open to not more than one
story above its level of exit discharge; or
1.2. The stairway is open to not more than one
story below its level of exit discharge.

 

[cdafd]

can it be stated that you have a first floor and second floor?

Or is there a basement?

 

[cdafd]

not a building code expert, so

It sounds like you need a third exit on the floor that has only two. I do not think that it can be unenclosed


From 708

7. In other than Groups I-2 and I-3, a shaft enclosure is
not required for a floor opening or an air transfer
opening that complies with the following:
7.1. Does not connect more than two stories.
7.2. Is not part of the required means of egress system.
7.3. Is not concealed within the construction of a
wall or a floor/ceiling assembly.
7.4. Is not open to a corridor in Group I and R occupancies.
7.5. Is not open to a corridor on nonsprinklered
floors in any occupancy.
7.6. Is separated from floor openings and air transfer
openings serving other floors by construction
conforming to required shaft enclosures.
7.7. Is limited to the same smoke compartment.

 

[cdafd]

Suggest you post the question here also,

http://www.thebuildingcodeforum.com/forum/commercial-building-codes/

 

[sprinkler1000]

Thanks a lot cdafd, for your time and the info.

I will take a look at all you posted.