Atria and mezzanines: Rand Hall’s latest Code fiction

[Updated Oct. 8, 2018 and Oct. 15, 2018]: [October 8, 2018 update: I just made a video based on the blog post below. Also, I’ve removed two of the six mezzanine “issues” I had initially written about: first, the 200-foot limit for exit access travel within the atrium doesn’t prevent a different path of exit access travel from being compliant, since only one of the two egress paths (the shortest) defines the exit access travel distance; second, while I still think that the area of the so-called mezzanine at the roof level is greater than half of the area of the atrium below, it’s too hard for me to definitively measure such floor area to be absolutely sure. There is the additional issue that the open-air roof gallery is not exactly “sprinklered,” so it’s unclear if it’s area should be 1/3 or 1/2 of the room it is in. In any case, there are still four problems with the roof-top mezzanine assumption being argued by Cornell and the City of Ithaca, any one of which would render the Rand Hall Fine Arts Library scheme noncompliant. These four remaining problems are explained below, and in the video.]

 

I received an email yesterday from the Director of Code Enforcement for the City of Ithaca Building Division claiming that Cornell’s proposal for a fifth-floor roof gallery—above the Fine Arts Library now being constructed in Rand Hall—was actually a mezzanine within the atrium below. This is important since a 5-story building would be absolutely noncompliant, whereas a 4-story building (with mezzanine)—while still egregious—is supported by numerous Code variances that Cornell has obtained over the years. The Building Division Director wrote: “The roof top gallery must meet the code requirements for a mezzanine otherwise the building is non-compliant. I have discussed this issue with the design team several times and have been assured that it will be sized so that it does meet the code requirements for a mezzanine. The sizing of the roof top area must include the permanently enclosed space at that level and all the open area that can be occupied. I do not believe that the code requires the mezzanine to be open to the atrium because the mezzanine has two exits.”

He then quoted a portion of the 2015 NYS Building Code (based on the 2015 International Building Code, or IBC) which seems to support his argument: “Exception 2. A mezzanine having two or more exits or access to exits is not required to be open to the room in which the mezzanine is located.”

In response, I replied as follows (where all references to the Code can be found here):

You have quoted only part of the mezzanine requirements, which state that a mezzanine need not be open to the room in which the mezzanine is located if it meets certain criteria (having at least 2 exits). However, there are six other criteria for qualifying as a mezzanine that the roof gallery does not meet. If even one of the following six criteria is not met, then the building, as designed, is noncompliant.

1. The definition of a mezzanine in Chapter 2 of the 2015 IBC states that a mezzanine is “an intermediate level or levels between the floor and ceiling of any story and in accordance with Section 505.” Clearly, the open roof gallery is not between a floor and a ceiling of any space, since there is no ceiling above it. Therefore, it is not a mezzanine.

2. The definition of an atrium in Chapter 2 of the 2015 IBC states that an atrium must be “closed at the top.” Therefore, it is impossible to include an open-air roof gallery as part of an atrium, since the atrium, in that case, would not be “closed at the top.”

3. Section 505 states that a mezzanine must be “in” the room for which it is so designated, not “on top of” the room, as is the case with the roof gallery. Specifically, Section 505.2.1 states: “The aggregate area of a mezzanine or mezzanines within a room shall be not greater than one-third [can be increased to one-half with sprinklers] of the floor area of that room or space in which they are located.” [emphasis added]. This section twice reiterates that the mezzanine must be “within” or “in” the room or space. This is not just a figure of speech, but is deliberate and important. Mezzanines are allowed to have certain fire safety benefits, unlike ordinary stories, precisely because they are “in” another room, where occupants of the mezzanine are more aware of any fires that may originate in that room, since the mezzanine has what used to be called a “common atmosphere” with the room in which it is located. Being “in” the room is therefore integral to the very essence of a mezzanine, whether or not the “opening” between the mezzanine and the room it is in has been closed off per the exception; the advantages of being “in” the room still apply. It is improper to ignore that part of the definition, and just look at the requirements for maximum area. If one used only the logic of maximum area, then any space, say a third-floor office, could be considered a mezzanine of a larger second-floor space that happened to be below it, even if there were no logical connections between the two spaces, but only a vertical adjacency.

4. It is also problematic to even consider that an atrium can have a mezzanine within it, since atriums are just “openings connecting two or more stories … which are closed at the top and not defined as a mall. Stories, as used in this definition, do not include balconies within assembly groups or mezzanines that comply with Section 505.” What this definition refers to when it states that mezzanines do not count as stories is not a mezzanine within the atrium (which would make no sense), but rather a mezzanine adjacent to the atrium, i.e., within a story surrounding the atrium opening. Only a conventional room or space can have a mezzanine. An atrium is not a conventional room or space, but rather is defined as an “opening” adjacent to such rooms or spaces. Once “mezzanine” floor area is inserted into an atrium, that floor area is, by definition, no longer an opening between stories, and so cannot be part of the atrium. Rather, it would be part of the adjacent stories that surround the atrium.

[Oct. 8, 2018 update] Issues #5 and #6 are no longer applicable, for the reasons explained in the update note at the top of the blog post. 5. Even if the roof gallery were considered as a mezzanine within the atrium, it still would be noncompliant, since Section 404.9.3 of the 2015 IBC limits the “portion of the total permitted exit access travel distance that occurs within the atrium” to no more than 200 feet. If the gallery is considered as a mezzanine within the atrium, then the exit access travel distance within the atrium, measured from the most remote point of the roof gallery, and following the atrium exit access stair “B” all the way down to the 2nd-floor exit, would be far greater than the 200-foot limit for exit access travel distance “that occurs within the atrium.”

6. The total area of the enclosed and open occupied spaces at the roof level (what is being called a mezzanine) is approximately 2,275 square feet; whereas the floor area of the atrium (measured at the 2nd floor) is approximately 4,335 square feet. Therefore, the so-called mezzanine exceeds the allowable area, based on the atrium floor area.

You correctly state that the building is noncompliant if the roof-top gallery, including all enclosed and occupied open spaces on the roof, does not qualify as a mezzanine. I think it is clear that—for the 6 reasons given above—the roof-top occupied spaces cannot be considered as a mezzanine. Therefore, the building is noncompliant.

Please reconsider your preliminary Code interpretation and let Cornell and their architects know that their notion of a roof-top mezzanine cannot be logically sustained.

[October 19, 2018 update]

On October 4, 2018, I asked the Director of Facilities for Cornell’s College of Architecture, Art, and Planning (copied to many other relevant parties, including the Director of Code Enforcement for the City of Ithaca Building Division, Mike Niechwiadowicz) to “confirm whether the entire roof structure of Rand Hall—including all columns that support the roof, and all beams that brace those columns, and all floor decks that brace the beams that brace the columns—has a 1-hour fire rating? This is important since an atrium, per 2015 IBC Section 404.6, needs to be separated from all adjacent spaces by a 1-hour horizontal assembly and/or fire barrier; as you know, there is an occupied space above the atrium’s roof that would need to be separated from the atrium by 1-hour fire-rated construction.”

On October 15, 2018, I got the following reply: “All the supporting elements, columns, braces, and floors, have a one hour rating. There was a variance granted by the state to not fireproof the horizontal roof steel. In regards to the roof, Per Tim D. from GHD, it is outside of the building and not a space within the building and therefore does not need a one hour separation. Also, the penthouse is a mezzanine to the atrium below and therefore does not need to be separated.”

On October 16, 2018, I responded as follows: “Thanks for the detailed answers. The occupied space above the atrium remains extremely problematic. Cornell’s 2016 Code variance was granted on the basis of an atrium roof with no occupied spaces above it, and so the variance cannot be applied to the current scheme. Section 404.6 of the 2015 Building Code specifically requires that ‘atrium spaces shall be separated from adjacent spaces by a 1-hour fire barrier … or a horizontal assembly…’ The occupied roof-top gallery is clearly an ‘adjacent space’ and so must be separated from the atrium with a 1-hour horizontal assembly. Cornell is claiming—improperly—that the roof-top occupancy is actually a mezzanine within the atrium below; this is a transparent attempt to get around the prohibition of a fifth story and the prohibition of an occupied space above a non-fire-rated atrium roof (horizontal assembly). But what Cornell is calling a mezzanine violates both the definition of mezzanine and the definition of atrium in Chapter 2 of the Code, not to mention the requirement that a mezzanine be ‘within’ a space or room [see detailed explanation below]. And as Mike has written to me previously, if the roof-top gallery space is not a mezzanine—which it clearly isn’t— the whole scheme is noncompliant.

“Please ask the design team to reconsider their plans for a fifth-floor above the atrium. It is likely that a formal complaint will be filed with the City of Ithaca and, if necessary, with the New York State Division of Code Enforcement and Administration if construction goes forward as currently planned—unless you can explain to me why none of the four reasons I have listed below applies to the current proposal. Please respond to my specific questions about the mezzanine designation, i.e., why you believe that every one of the four reasons I have cited below is incorrect. I’ll email again in a couple of weeks before initiating the complaint process, hoping that common sense will prevail during that time period.”

Then, on October 19, 2018, I wrote a follow-up email to the the Facilities Director (and other relevant parties): “I just re-read your email dated Oct. 15, 2018, and now am totally confused about Cornell’s intentions with respect to the roof gallery. Mike Niechwiadowicz wrote that the building permit for the Ho Fine Arts Library was granted on the basis of the roof gallery being treated as a mezzanine within the atrium. Your quote from Tim D. from GHD, on the other hand, implies that the roof gallery is not only not a mezzanine, but is not even a relevant consideration, being ‘outside’ of the building. Let me quote from Mike’s email to me, dated Oct. 4, 2018: ‘The roof top gallery must meet the code requirements for a mezzanine otherwise the building is non-compliant. I have discussed this issue with the design team several times and have been assured that it will be sized so that it does meet the code requirements for a mezzanine. The sizing of the roof top area must include the permanently enclosed space at that level and all the open area that can be occupied.’ [emphasis added]

“So please clarify how the roof gallery is being considered from a fire safety (Building Code) standpoint. On the one hand, if it is being considered as a mezzanine, then my comments in the prior email stand. On the other hand, if it is being simply ignored, please consider the following explanation as to why that latter standpoint is equally flawed.

“You wrote: ‘In regards to the roof, Per Tim D. from GHD, it is outside of the building and not a space within the building and therefore does not need a one hour separation.’ There are two claims here, amounting to the same thing: (1) The roof gallery is outside the building; and (2) the roof gallery is not a space within the building. From these two claims, the conclusion is drawn that the atrium does not need to be separated from the occupied roof gallery by a 1-hour fire-rated horizontal assembly.

“But the Code, and common sense, do not support this conclusion. First, from the Code: Section 404.6 states that ‘Atrium spaces shall be separated from adjacent spaces by a 1-hour fire barrier… or a horizontal assembly…’ Any adjacent (occupied) space—not only an adjacent ‘story’—needs to be separated from the atrium. But is the roof gallery part of the building? The 2015 Building Code specifically identifies ‘occupied roofs'” as being part of the building since, per Section 1006.3, ‘The means of egress system serving any story or occupied roof shall be provided with the number of exits or access to exits based on the aggregate occupant load served in accordance with this section’; and the means of egress is defined as ‘a continuous and unobstructed path of vertical and horizontal egress travel from any occupied portion of a building or structure to a public way…’ Since means of egress systems are, by definition, in buildings; and since occupied roofs must have means of egress, it follows that occupied roofs are part of buildings. One could put this in the form of a logical syllogism:

Major premise: Means of egress systems are in buildings (Definition, Chapter 2).

Minor premise: Occupied roofs must have means of egress (Section 1006.3)

Conclusion: Occupied roofs are part of buildings.

“From all this, it follows that the occupied roof gallery is not only a space adjacent to the atrium (which is really the only relevant criterion), but is also part of the building, contrary to the unsupported assertion made by Cornell’s Code consultant. The requirement in Section 404.6 is for separation of the atrium from ‘adjacent spaces,’ not only from adjacent stories. And an occupied roof is both a ‘space’ and a space that is part of the building.

“Second, based on common sense: Hundreds of assembly occupants may gather on the roof gallery above the atrium and their safety is threatened by placing them above an atrium without any fire-rated separation. This is what the 2015 ‘Code Commentary’ says about the need for fire-rated enclosure: ‘One of  the basic premises of atrium requirements is that an engineered smoke control system combined with an automatic fire sprinkler system that is properly supervised provide an adequate alternative to the fire-resistance rating of a shaft enclosure. It is also recognized that some form of boundary is required to assist the smoke control system in containing smoke to just the atrium area. The basic requirement, therefore, is that the atrium space be separated from adjacent areas by fire barriers and horizontal assemblies having a fire-resistive rating of at least 1 hour.’ [emphasis added] The current scheme not only violates this basic requirement for separation, but also violates the explicit logic of a smoke control system (i.e., ‘in containing smoke to just the atrium area’) by venting atrium smoke—not harmlessly into the outside air—but rather right at the roof level, immediately adjacent to the occupied roof gallery itself! I’ve noted previously that the exit access stairway will also serve as a smoke vent system when its door is opened, thereby making egress from the roof gallery even more precarious. If your intention was to design a building that puts occupants at maximum risk, you have succeeded admirably.

“Mike Niechwiadowicz has written explicitly that ‘the roof top gallery must meet the code requirements for a mezzanine otherwise the building is non-compliant.’ Since the roof gallery is not a mezzanine, the building is non-compliant. All other Code interpretations seeking to justify this dangerous proposal are equally flawed.

“I’m still eager to hear back from you before I initiate a formal complaint.”

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