Enclosed Exit Enclosure 1022

[JustReid]

I have a question that seems to be up to interpretation.

I am looking at 2009 IBC Section 1022.1 Exception 1. The wording states “…a stairway is not required to be enclosed when the stairway serves an occupant load of less than 10…

Assume everything else in the Exception is in compliance and only two exit stairs.

So could you have 20 occupants on the second floor and the two exit stairs would only serve 10 and therefore not be required to be enclosed? Or is the reference to a total occupant load of 10 on the second floor?

Definition from 1002 - Occupant Load - The number of persons for which the means of egress of a building or portion thereof is designed.

 

[Builder Bob]

Since the stairway or the access corridor to teh stairways is a common atmosphere, the stairways are serving te 20 occupants in the same air...... JMHO.

 

[JustReid]

This might be over analyzing these sections, but the code section uses stairway (singular) so I am wondering if that would be split in two for the total of 20 on the second floor and still allow the unenclosed stairs.

 

[mtlogcabin]

Look at 1016.1 exception 3

If the exit access travel distance from the most remote point using the unenclosed stair meets the travel distances of table 1016 for the occupancy then you may be correct and would be allowed

Excellent question

Code path

1021.1 Exits from stories.

All spaces within each story shall have access to the minimum number of approved independent exits as specified in Table 1021.1 based on the occupant load of the story .

Exceptions:

3. Exit access stairways and ramps that comply with Exception 3 or 4 of Section 1016.1 shall be permitted to provide the minimum number of approved independent exits required by Table 1021.1 on each story .

 

[mark handler]

Playing devil’s advocate

"....serves an occupant load of less than 10...." VS Has an occupant load of less than 10

Two stairs serve an occupant load of twenty; each stair has a load of 10. But the code does not say “has” it says “serves” .

 

[mtlogcabin]

Playing devil’s advocate"....serves an occupant load of less than 10...." VS Has an occupant load of less than 10

Two stairs serve an occupant load of twenty; each stair has a load of 10. But the code does not say “has” it says “serves” .

Interesting point and I would have to agree.

However the question that should be asked is, are 2 exits required from this space by 1021?

If yes then are both stairs required to be constructed as exit enclosures. I don't think so if the exiting complies with 1016.1 exception 3.

 

[JustReid]

For the purpose of this discussion, we will assume the travel distance is greater than 75 feet. Does the definition of occupant load come into play you think? Where it says "or portion thereof" could that be a portion of the second floor?

I am leaning to everyones thinking that the occupant load of the second floor would only be allowed to be 10.

 

[rooster]

if the language says "less than 10" wouldn't that mean the occupant load could only be 9? then I guess the question would be whether it means 9 for the whole floor or 18.

 

[gbhammer]

if the language says "less than 10" wouldn't that mean the occupant load could only be 9? then I guess the question would be whether it means 9 for the whole floor or 18.

rooster I believe your correct, 9 is the magic number not 10.

The loss of exception 8 and 9 hurts the DP who wants an open two story building.

I would have to sway in the direction of 9 occupants per stair, and the stairs can remain open. It would be very easy to justify that train of thought if each second story space with an occupant load of 9 or less had its own stair.

 

[JustReid]

Yes, agree with the 9 or 18 since we can't have fractions of people(and I'm back on the fence). This is similar to conference rooms used to only being allowed to be 735 sf (when using 15 occ/sf) and remain a B. But now we have the additional exception that clearly states 750 (2009 edition, I have yet to fully go through 2012).

It looks like the code path provided by Mtlogcabin would allow an exit access stairway to be provided for egress all the way to the exterior as long as the exit access travel distance was not exceeded. Does everyone agree that the 2009 edition intended "exit access stairways" to be assumed to be unenclosed? Cite definitions 1002 EXIT ACCESS DOORWAY ...unenclosed exit access stair...

But apparently this all goes away once we adopt the new book. The 2012 removed the unenclosed reference from the definition and put everything in 1009.3 where it clearly states that they are to be enclosed but then goes into the list of exceptions. So it appears the 2009 exit access stair provisions were an incomplete thought and they finished the thought in the 2012. Sheesh. Makes it tough for those of us working in the 2009 edition.