elevator connecting 1st floor w/ mezzanine

[Tim Mailloux]

And 713.4 explicitly says mezzanines don't count.

thats not what it says

 

[Paul Sweet]

The rated shaft requirement might also be to protect surrounding spaces from an equipment fire in the shaft, especially if it's a hydraulic or machine-room-less elevator.

 

[tmurray]

you trying to get all the AHJs here fired?

Prescriptive requirements should be worded clearly enough so that complete understanding of the intent is not required in order to determine compliance.

In this case the wording used in 713.4 would require a 1 hour fire rating. If the intention was to exempt mezzanine floors from Section 713, that belongs in 713.1. The guidance in 713.4 is just provided for choosing between the two cases of a 1 hour fire rating and a 2 hour fire rating.

Cheers, Wayne

Maybe I'm the idiot because I'm not familiar with the US code process. So, when something is added to the code, there is a reason right? In our system, each code change is accompanied with a document like this: https://cbhcc-cchcc.ca/eng/public-review/2025_1/2025-proposed-changes-to-nbc-combined-file-2025-01-15.pdf.

It tells me as a building official exactly what the intent was behind a provision. If the intent of the enclosure is to prevent fire spread between floors, but it's an open mezzanine, it doesn't make much sense to enforce that provision in those circumstances. This need for discretion has been recognized by our supreme court, who indicated that they expect building officials to act with discretion and not "code enforcement robots" (their words). Furthermore, our supreme court has established simply because something does not comply with the code, does not automatically mean that it is a deficiency that must be corrected. The building official must apply their discretion in accordance with the code intent.

 

[Yankee Chronicler]

Prescriptive requirements should be worded clearly enough so that complete understanding of the intent is not required in order to determine compliance.

In this case the wording used in 713.4 would require a 1 hour fire rating. If the intention was to exempt mezzanine floors from Section 713, that belongs in 713.1. The guidance in 713.4 is just provided for choosing between the two cases of a 1 hour fire rating and a 2 hour fire rating.

Cheers, Wayne

Except that the wording of 713.4 (the code, not the commentary) explicitly says

The number of stories connected by the shaft enclosure shall include any basements
but not any mezzanines.

Tim's interpretation is that zero stories connected is less than four, therefore even when a shaft connects zero stories it still requires a 1-hour rating. My interpretation (which, obviously, I think is consistent with both the letter and the intent of the code) is that "less than four" means "two or three." And I believe this is entirely consistent with section 713.4:

713.4 Fire-resistance rating. Shaft 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 shaft enclosure shall include any basements
but not any mezzanines. Shaft enclosures shall have a
fire-resistance rating not less than the floor assembly penetrated,
but need not exceed 2 hours. Shaft enclosures shall
meet the requirements of Section 703.2.1.1.

It says, right there, that a 1-hour rating is required when connecting less than four stories. And immediately after that it states that "The number of stories connected by the shaft enclosure shall include any basements but not any mezzanines." I don't know how it can be any plainer -- in considering how many stories a shaft connects, we don't count mezzanines.

And that's entirely consistent with what a mezzanine is -- a raised level within a single story.

 

[Yankee Chronicler]

thats not what it says

That's exactly what it says.

The number of stories connected by the shaft enclosure shall include any basements
but not any mezzanines.

 

[Tim Mailloux]

The mezzanine reference 713.4 is intended to guide us on how to count stories in a building that includes a mezzanine. The goal is to ensure that a building with three stories and a mezzanine doesn’t get penalized and is not required to provide a 2-hour rated shaft enclosure. According to 713.4, there are only two options available for shaft enclosure ratings: the first option is to have a 2-hour rated enclosure for buildings with four stories or more, and the second option is a 1-hour rated enclosure for buildings with less than four stories.

 

[wwhitney]

My interpretation (which, obviously, I think is consistent with both the letter and the intent of the code) is that "less than four" means "two or three."

You might be right about the intent (beyond my knowledge), but we can say unequivocally that "less than four" includes one and zero.

It says, right there, that a 1-hour rating is required when connecting less than four stories. And immediately after that it states that "The number of stories connected by the shaft enclosure shall include any basements but not any mezzanines." I don't know how it can be any plainer -- in considering how many stories a shaft connects, we don't count mezzanines.

It could be plainer by saying that for 2 or 3 stories, a 1 hour rating is required, and for 4 or more stories a 2 hour rating is required. That implies that for 1 story, no rating is required, but even that could be explicitly stated.

But it doesn't do any of that, it just says "less than four". So the letter of the code clearly requires a 1 hour rating for 1 story.

Cheers, Wayne

 

[Yankee Chronicler]

I disagree (obviously) with Tim Mailloux and wwhitney. I understand your arguments, and I find them unpersuasive.

In most jurisdictions, a question such as this would be resolved by the AHJ saying, "It means what **I** say it means." [IBC 104.1] In my state, such differences of opinion can be resolved only by submitting the question to the State Building Inspector for a formal interpretation.

 

[Inspector Gadget]

Disclaimer: I'm a Canadian, using Canadian Codes.

I had a vaguely similar situation with a building whose work is still ongoing. The building had a legal, conforming interconnected floor space - that is, it had an open, unrated stair shaft connecting two floors. A designer argued that installing an elevator between those two floors did not require a rated shaft, since it would have been another interconnected floor space.

Our codes state that yes, you can do that, as long as the *machinery* is then isolated from the rest of the building with a rated assembly.

Given the frequent similarities I see between 'Murrican codes and NBC, does your code have a "if not rated shaft, then rated machinery room" clause or path?