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Exit access stair unenclosed for 4 stories

N

nealderidder

Sawhorse
Joined
Dec 7, 2010
Messages
398
Location
Sacramento, CA
I'm working on conceptual design for a 4 story mixed use project in California. It's a small building (40'x80') and has frontage on three sides. I've got an exterior exit stair on the back. That exit on the back falls within the maximum allowed travel distance to an exit for the entire building, therefore my second exit doesn't have a limit on travel distance. This is where it gets interesting...

Out of habit I was going to pop an interior exit stair at the front of the building for the second exit. But then I got thinking... if I don't have a distance limit, I can use the front door at grade as my second exit for the entire building (I could probably get to that door even if I had a 250' limit) so why put in an exit stair? Why not move vertically via an Exit Access Stair?

CBC 1019.3 #4 says that with a smoke curtain and some additional sprinklers I can connect an open stair for four stories. My client would love to have the stair open at the main entry (cool stair with glass rails and lots of steel). So can I really have a four story opening in a four story building with an exit access stair in it?

What would require me to enclose this stair? Can it be open to the rest of the building?


Regards,
Neal
 
If you comply with Section 1019.3, Subparagraph 4, your building does not include a Group I-2 or Group I-3, and the stair does not connect to a basement, then you can have an open stairway. I recently did that for a 3-story college classroom building.

Make sure your exterior exit stairs are separated from the interior per Section 1027.6.
 
RLGA said:
If you comply with Section 1019.3, Subparagraph 4, your building does not include a Group I-2 or Group I-3, and the stair does not connect to a basement, then you can have an open stairway. I recently did that for a 3-story college classroom building.

Wow. And that stairway can be open to and communicate with the other floors? No separation at all needed?

I thought there might be a conflict with 712.1 which seems want such vertical openings limited to two floors but then 712.1.12 that says that vertical openings for exit access stairs are OK.

I feel like I'm missing something, It just seems wrong to put a big open shaft through four floors and not separate it at all!
Click to expand...
 
Section 712 applies to all vertical openings, which does include a reference to Section 1019 in Section 712.1.12 for exit access stairs.
 
How about 1006.3? In my scheme I've got two exits (or access to exits) on each floor. One is an Exterior Exit Stairway and one is the Exit Access Stair we're talking about that leads to the front door at grade.

1006.3 says: The path of egress travel to an exit shall not pass
through more than one adjacent story.

Does this mean both of my exits from each floor can't pass through more than one adjacent story before I reach an exit or does it mean one of the two required exits can't pass through more than one adjacent story?

The language seems a bit like the exit access travel distance language which is widely accepted to mean only one exit must meet this requirement:

1017.3 Measurement. Exit access travel distance shall be
measured from the most remote point within a story along the
natural and unobstructed path of horizontal and vertical
egress travel to the entrance to an exit.
 
I would agree that the language is similar in that they both use the word "an."

However, if it becomes a particular problem with interpretation it is rejected, you can always refer to the "general versus specific" rule.

Per IBC Section 102.1, "Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable." This is the basic IBC provision; however, California has heavily modified Chapter 1, and the similar requirement is located in Section 1.1.7.2. Applying those provisions, Section 1006.3 would be considered a general requirement and Section 1019.3 would be considered a specific requirement; thus, Section 1019.3 would be permitted and essentially becomes an exception to 1006.3.
 
Excellent, I'll keep that one at the ready.

This provision that would allow an unenclosed 4 story egress (component) stair is new to me and has me imagining all kinds of crazy stuff.

For instance - Why not throw the elevator into the mix? I can locate the elevator shaft adjacent to this open stair (say next to the mid-level landings) and I'll have open stairs with an adjacent elevator all with no vertical enclosure (other than the elevator shaft itself). I can meet the 3006.3 requirement for hoistway opening protection with a drop down smoke door like a Door Systems DSI 600 and I don't need an enclosed lobby.

Does anyone see a problem with that?
 
nealderidder said:
Excellent, I'll keep that one at the ready.

This provision that would allow an unenclosed 4 story egress (component) stair is new to me and has me imagining all kinds of crazy stuff.

For instance - Why not throw the elevator into the mix? I can locate the elevator shaft adjacent to this open stair (say next to the mid-level landings) and I'll have open stairs with an adjacent elevator all with no vertical enclosure (other than the elevator shaft itself). I can meet the 3006.3 requirement for hoistway opening protection with a drop down smoke door like a Door Systems DSI 600 and I don't need an enclosed lobby.

Does anyone see a problem with that?
Click to expand...

Yes. The elevator is not an exit access stairway, so Section 1019.3 would not apply--you'd have to use Section 712, which would only allow a shaft enclosure (712.1.1) or an atrium (712.1.7) for the elevator. If you consider it an atrium, then the stairway in the atrium would be considered an exit stair per Sections 1023.2, Exception 2, and Section 404.10, and the travel distance would stop at the first riser. However, the atrium would need to comply with the requirements of Section 404, which requires a 1-hour enclosure (except up to three stories are permitted to be unenclosed) and smoke control (with standby power if smoke control is an active system [i.e., smoke pressurization or exhaust systems]).
 
You lost me a bit... I don't need 1019.3 to apply to the elevator, it comes with its own shaft (would probably do a CMU shaft). I'm just talking about this enclosed elevator shaft sitting next to the open stair. The only thing that could throw a monkey wrench into the works is if the elevator needs closed lobbies (which would necessitate a separation from the open stair), but I can avoid that with smoke doors. Or am I not getting what you're telling me?
 
If the elevator is in a shaft enclosure, then it doesn't matter where the elevator is located. Elevator lobbies or other elevator opening protection would not be required if the building is sprinklered throughout per Section 3006.2, Subparagraph 1.
 
Just the discussion I was looking for....

In Florida we have to follow the Florida Building Code, based on the IBC, which has the same sections as discussed. However, we also have to comply with the Florida Fire Prevention Code which is based on NFPA 1 & 101. NFPA 101-7.2.2.5.1.1 states "All inside stairs serving as an exit or exit component shall be enclosed in accordance with 7.1.3.2".

7.1.3.2 is a big section describing wall ratings, opening protections, finishes, etc. but doesn't provide explicit conditions like in the Building Code. So it seems the only way the OP's project could be built in Florida is if each floor was small enough to allow only one exit, thereby allowing the unenclosed stair to not be considered an exit or exit component. Is this interpretation correct?

What is everyone's experience with this topic from the NFPA side?


Thanks,
Tim
 
RLGA said:
and the stair does not connect to a basement
Click to expand...

First time posting, but I'm working on a similar project as nealderidder, where I'm trying to get an open stairway under the provisions of 1019.3 Condition 4. However, one of those four floors is a basement (and one of them is a roof). Can you point me to the code section that precludes the basement connection?

If the basement can't be connected through the same vertical opening, can the stair to the basement just be relocated elsewhere in the building? If so, how far away would it need to be relocated in order to not constitute a vertical opening?
 
So to clarify,

Do you want only two floors open to each other?

Or do you want more than two floors open to each other??

Or is your question can you have an enclosed stair serving all the floors ??


You do know it is Easter time, so you may not get some responses till Monday.
 
I drew a quick sketch, but can't seem to figure out how to attach it here... So I made an imgur link to it here. Hopefully the link works. Sorry, this is my first time on the forum so I'm still kinda figuring out the mechanics of it.

But yes, ideally, the same opening would connect from basement to roof.

And I have no expectations about response time! Just happy to have some good code discussions with knowledgeable people.
 
As Neal noted above, 1019.3 Condition 4 allows up to 4 floors in other than B or M Occupancies:

1019.3 Occupancies other than Groups 1-2, R-2.1, 1-3, and
R-2.1. In other than Group 1-2, 1-2.1, 1-3, and R-2.1 occupancies,
floor openings containing exit access stairways or ramps
that do not comply with one of the conditions listed in this
section shall be enclosed with a shaft enclosure constructed in
accordance with Section 713.

And the pertinent Condition 4 states:

Exit access stairways and ramps in buildings equipped
throughout with an automatic sprinkler system in
accordance with Section 903.3.1.1, where the area of
the vertical opening between stories does not exceed
twice the horizontal projected area of the stairway or
ramp and the opening is protected by a draft curtain and
closely spaced sprinklers in accordance with NFPA 13.
In other than Group B and M occupancies, this provision
is limited to openings that do not connect more
than four stories.

I'm trying to figure out where the CBC precludes a basement as one of the four stories allowed, as Ron mentioned. Or for that matter, if one of those floors being an occupiable roof poses any issues.

Thanks!
 
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