Open Stair as Exit Access

[DTBarch]

Given:
2018 I-Code Jurisdiction. 2 story office building (plus 1 basement level below) with 2 rated enclosed stairways at each end, and an un-enclosed stair in the central core area. Fully Sprinklered. In addition to the unenclosed stair with a horizontal projected area of 163 sf, there is an adjacent but separate atrium area with a vertical opening measuring approx. 632sf Total cumulative occupant load for the 2nd floor is 148 occupants.

Proposed Alteration:
Prospective tenant #1 wishes to lease 75% of the east wing, collapsing the common egress corridor to the east rated stairway which would place the east enclosed stairway within their leased premises and eliminate access to that exit stairway from the rest of the floor. The remaining 25% of the east wing (Tenant #2) would retain the balance of the common egress corridor (less than 50' dead end), and use the central unenclosed stair plus the west wing rated stairway as the two required exits. The central unenclosed stair would qualify to be used as an exit access for one of the two required exits per the exception under 1019.3.4 with the installation of a draft curtain and additional "closely spaced" sprinklers. The total exit travel distance from the the easternmost extreme tenant space to the 1st floor exit door is well under the 300' limit. Therefore, the unenclosed central exit access stair would replace the east rated stairway as the primary 2nd exit for the 2nd floor tenants.

Question:
The central unenclosed stair does not sit within the atrium opening, therefore, the opening vs. stair area is not exactly what is addressed in the 1019.3.4 verbiage, BUT the atrium does sit directly adjacent to the stair. As such, would the separate atrium opening impact the ability to utilize 1019.3.4 as an exception to be used as the 2nd exit for the 2nd floor after the proposed alteration. (counter to the similar scenario described in 1019.3.4, the atrium opening is more than 2x the projected area of the stairway.


ea

 

[Yankee Chronicler]

An atrium isn't just the hole in the floor, it's the entire area/volume on the two connected stories.

 

[DTBarch]

An atrium isn't just the hole in the floor, it's the entire area/volume on the two connected stories.

Yankee, I'm referring specifically to the language presented in Section 1019.3.4 where it references "the area of the vertical opening between stories" as it relates to the "horizontal projected area of the stairway". It's a straight SF area comparison they are referencing, not a volume.

 

[walker.t]

there is an adjacent but separate atrium area…

Question:
The central unenclosed stair does not sit within the atrium opening

Adjacency doesn’t come into play here assuming that by “separate” you mean just that - that the floor opening for the exit access stairway is not contiguous with the atrium opening.

would the separate atrium opening impact the ability to utilize 1019.3.4 as an exception…[continued in next quote]

No, assuming when you say “separate” you really mean exactly that - no connection between the opening in the floor for the stairway or the atrium opening.

Looking at your plan it looks like the floor opening for the stairway is less than twice the footprint of the stairway so you can use the draft curtain and the closely spaced sprinklers per 1019.3 Exception 4 and you won’t have to put the stairway in a shaft enclosure.

…to be used as the 2nd exit for the 2nd floor after the proposed alteration.

I don’t think that’s related to whether the stairway has to be in a shaft enclosure or not, is it? I thought you established you were within the allowable travel distances…

The total exit travel distance from the the easternmost extreme tenant space to the 1st floor exit door is well under the 300' limit. Therefore, the unenclosed central exit access stair would replace the east rated stairway as the primary 2nd exit for the 2nd floor tenants.

Not related to your question, I noticed you’re showing the doors to the wheelchair accessible toilet compartments in front of the toilets, doors have to be set in the corner diagonally opposite the toilet, see A117.1 604.9.3.1.

 

[Yankee Chronicler]

Yankee, I'm referring specifically to the language presented in Section 1019.3.4 where it references "the area of the vertical opening between stories" as it relates to the "horizontal projected area of the stairway". It's a straight SF area comparison they are referencing, not a volume.

Well, I'm confused.

First, if whatever you are arguing isn't dependent on the stair being in an atrium, why did you mention it?

Second, I'm looking at the 2021 IBC Commentary, and there is no section 1019.3.4 -- so what are you talking about?

Is the floor opening (not the stair) protected by an automatic fire shutter?

 

[walker.t]

there is no section 1019.3.4 -- so what are you talking about?

I noticed that, too, I assumed that the OP meant 1019.3 Exception 4 because that has the reference to “vertical opening between stories.”

 

[Yankee Chronicler]

I'm too old to play guessing games. I'm happy to try to answer questions, but I don't think it's asking too much for the people asking the questions to at least get the code references correct.

 

[DTBarch]

I'm too old to play guessing games. I'm happy to try to answer questions, but I don't think it's asking too much for the people asking the questions to at least get the code references correct.

Yankee. I appreciate a good sense of humor. If you carefully read my OP, I state this is reference to the 2018 IBC. The specific section happens to be mostly unchanged in the 2021 code. The ".4" is referring to listed exception #4, fully within and graphically displayed below 1019.3. I apologize if that was too cryptic and it actually caused you to unsuccessfully guess at what the additional .4 might have been referring to. If you break through that "brain teaser" and read the list of exemptions including #4, you'll clearly see explanations for the referenced area definitions that you were originally confused about, and nothing that speaks to fire shutters, especially when the code is referring to a horizontal opening, not a vertical one.

Furthermore, contrary to your reply, nowhere do I mention reference to the "2021 Code Commentary" document which, as you know, is not code. As a result, your comment about incorrect code references is unfortunate. Again, sorry for the liberties in the exemption reference.

The intent of that specific exemption is relief from enclosure of the stair which is granted in exchange for draft curtains and fire sprinklers that will create both a smoke barrier, and water curtain at the stair boundary to prevent fire and smoke from migrating up thru the opening in the floor as long as the area of the larger vertical opening is limited to twice the size of the stair area.

While technically, in our case, the stair itself is compliant as an exit access stair, it does happen to sit directly adjacent to an atrium opening that is approximately 3x the size of the stair area (50% larger than the allowable area delta in Section 1019.3 - Exemption #4), so in the event of a fire event, one might reasonably come to the conclusion that the relatively large atrium opening that sits directly adjacent to the stair would potentially denegrate, or otherwise weaken the safety measures placed at the opening to the stair as it relates to the migration of fire and smoke.

Let me further explain my question. I know you stated that you were "too old to play guessing games"guess", so I want to be respectful and as clear as I can be to avoid any age related confusion The presentation of my question is out of an abundance of caution directly related to life safety that is motivating me to think beyond simple code syntax, and to the intent behind the code. In my 30+ years of experience as a practicing registered architect, (I'm kinda old too), whenever you decrease the number of life safety components, for example one of two existing enclosed and protected stairways from an existing building, you best have rock solid justification and assurance that your altered condition and new required replacement 2nd exit is fully compliant.

Since my client is asking us to eliminate one of the two existing bona-fide rated stair enclosures from this 40 year old building, I'd like to be sufficiently sure that the alternative exit that the occupants are left with, is free from compliance challenges relative to life safety liability. Additionally, in the real world, ambiguous and unaddressed code interpretations can unexpectedly derail a 5 year, 10,000sf commercial lease deal if plan review comments are not expected until a date well beyond execution of the lease document. That's all part of my fiduciary duty to my client, and this is all legitimate due diligence to satisfy that responsibility. Hopefully that clears up the code section mystery and provides sufficient context to process my question if you choose to do so.

I appreciate your time and willingness to participate in the discussion.

 

[walker.t]

The following are my opinions on a couple of things in your most recent post.

While technically, in our case, the stair itself is compliant as an exit access stair, it does happen to sit directly adjacent to an atrium opening that is approximately 3x the size of the stair area (50% larger than the allowable area delta in Section 1019.3 - Exemption #4), so in the event of a fire event, one might reasonably come to the conclusion that the relatively large atrium opening that sits directly adjacent to the stair would potentially denegrate, or otherwise weaken the safety measures placed at the opening to the stair as it relates to the migration of fire and smoke. [Emphasis added.]

The way that would play out is if you apply the technical requirements and there’s a fire and someone dies that when you get sued they’ll find an expert witness that will say you failed to comply with the standard of care because you should have known better with 30+ years experience. If your intuition is telling you this is a liability risk then you should follow your intuition and enclose the stair.

That's all part of my fiduciary duty to my client

As I understand the phrase “fiduciary duty,” architects cannot have a fiduciary duty to their clients because their highest obligation is to protect the health, safety, and welfare of the public.

 

[DTBarch]

The following are my opinions on a couple of things in your most recent post.


The way that would play out is if you apply the technical requirements and there’s a fire and someone dies that when you get sued they’ll find an expert witness that will say you failed to comply with the standard of care because you should have known better with 30+ years experience. If your intuition is telling you this is a liability risk then you should follow your intuition and enclose the stair.


As I understand the phrase “fiduciary duty,” architects cannot have a fiduciary duty to their clients because their highest obligation is to protect the health, safety, and welfare of the public.

Thanks Walker. Good high level rule of thumb that is quite possibly the prudent choice in the absence of further gathered intelligence. I'm hoping for some level of experienced precedent and insight that may define the risk in a way different than my base assumptions. It's a bit of a technically nuanced issue, so may not be possible, but the Forum is one very useful source of intelligence. Am also discussing with the local AHJ and Fire Marshal. Thanks again for your time.

 

[Yankee Chronicler]

Yankee. I appreciate a good sense of humor. If you carefully read my OP, I state this is reference to the 2018 IBC. The specific section happens to be mostly unchanged in the 2021 code. The ".4" is referring to listed exception #4, fully within and graphically displayed below 1019.3. I apologize if that was too cryptic and it actually caused you to unsuccessfully guess at what the additional .4 might have been referring to. If you break through that "brain teaser" and read the list of exemptions including #4, you'll clearly see explanations for the referenced area definitions that you were originally confused about, and nothing that speaks to fire shutters, especially when the code is referring to a horizontal opening, not a vertical one.

Actually, you wrote that it's 2018 I-Code jurisdiction -- you didn't state which of the 2018 codes you were looking at. And Exception number 4 to any section of the codes is not same as ####.#.4. Many section of the I-Codes have numbering that go to two or three decimals before getting to exceptions.

Furthermore, contrary to your reply, nowhere do I mention reference to the "2021 Code Commentary" document which, as you know, is not code. As a result, your comment about incorrect code references is unfortunate. Again, sorry for the liberties in the exemption reference.

I never said you were referring to the 2021 Code Commentary. I said I was looking at the 2021 IBC Commentary. Of course I know that the Commentaries are not enforceable. They are there -- and we look at them -- for guidance in issues where we aren't certain how (or if) the enforceable language of the codes applies.

The intent of that specific exemption is relief from enclosure of the stair which is granted in exchange for draft curtains and fire sprinklers that will create both a smoke barrier, and water curtain at the stair boundary to prevent fire and smoke from migrating up thru the opening in the floor as long as the area of the larger vertical opening is limited to twice the size of the stair area.

While technically, in our case, the stair itself is compliant as an exit access stair, it does happen to sit directly adjacent to an atrium opening that is approximately 3x the size of the stair area (50% larger than the allowable area delta in Section 1019.3 - Exemption #4), so in the event of a fire event, one might reasonably come to the conclusion that the relatively large atrium opening that sits directly adjacent to the stair would potentially denegrate, or otherwise weaken the safety measures placed at the opening to the stair as it relates to the migration of fire and smoke.

This is why I asked if what you refer to as the atrium opening (by definition, even the open exit access stair opening creates an atrium) is protected by an automatic horizontal fire shutter. If not, IMHO you have to count the combined area of the stair opening and what you refer to as the atrium opening together. The combined area exceeds what Exception #4 allows. Therefore, to do what you want to do would require a an automatic fire shutter at what you refer to as the atrium opening.

Let me further explain my question. I know you stated that you were "too old to play guessing games"guess", so I want to be respectful and as clear as I can be to avoid any age related confusion The presentation of my question is out of an abundance of caution directly related to life safety that is motivating me to think beyond simple code syntax, and to the intent behind the code. In my 30+ years of experience as a practicing registered architect, (I'm kinda old too), whenever you decrease the number of life safety components, for example one of two existing enclosed and protected stairways from an existing building, you best have rock solid justification and assurance that your altered condition and new required replacement 2nd exit is fully compliant.

If you were to consider this under the Performance Method of the IEBC, would you lose points by eliminating one of two existing enclosed exit stairs? I haven't looked at it, but I suspect you would, and that's food for thought.

Since my client is asking us to eliminate one of the two existing bona-fide rated stair enclosures from this 40 year old building, I'd like to be sufficiently sure that the alternative exit that the occupants are left with, is free from compliance challenges relative to life safety liability. Additionally, in the real world, ambiguous and unaddressed code interpretations can unexpectedly derail a 5 year, 10,000sf commercial lease deal if plan review comments are not expected until a date well beyond execution of the lease document. That's all part of my fiduciary duty to my client, and this is all legitimate due diligence to satisfy that responsibility. Hopefully that clears up the code section mystery and provides sufficient context to process my question if you choose to do so.

I appreciate your time and willingness to participate in the discussion.

Another concern, beyond your question: In the 50' dead-end corridor adjacent to the hatched tenant area, the 50-foot corridor is defined by a door at the right-hand (in plan) end of the corridor -- with another 30 feet or so of dead end corridor beyond that. Is the door I have circled existing, or is it being added specifically to limit the dead-end corridor to 50 feet in length? Thirty or forty years ago, that was an accepted practice. It isn't any more, and (at least in my state) hasn't been accepted for decades. Your dead-end corridor as actually about 80 feet in length.