Elevator Enclosure Fire-Rating | Mezzanines

[LaNouba]

2018 IBC

I have an elevator serving 3 mezzanine levels within 1 story/room. By definition, the mezzanine levels are open to the story/room. The elevator hoistway penetrates the mezzanines, and does not abut to other walls/rooms/spaces. You can walk around the 4 sides of the hoistway at ground and mezzanines.

• I had concluded I could apply 712.1.9 if I used a metal screened enclosure so that the opening is not concealed.
• I concluded it becomes concealed if I use gyp walls, which becomes a shaft, which requires a 1-hr rating.

Do these conclusions sound correct?

1. Is there a case where I can have solid gyp walls, but not the 1-hr rating?
2. Does adding glass, open louvers, or metal screen to gyp walls help comply with 712.1.9, which would remove the 1-hr rating requirement?
3. Can this be considered an atrium, and would that remove the 1-hr rating requirement?
4. Does the fact it is only 1 story/room remove the fire-rated requirements altogether?

Sketch: brown represents 3 mezzanine levels, green elevator, all within one room (black box)

I'm lost in a loop:
712.1.9 Two-story openings, item 3: What is considered "concealed"?
712.1.11 Mezzanine: Vertical openings between a mezzanine complying with Section 505 and the floor below shall be permitted.
713.4 Fire-resistance rating: The number of stories connected by the shaft enclosure shall include any basements but not any mezzanines.

Thank you!

 

[Paul Sweet]

I'd be surprised if code writers even thought about a situation like this.

Logically if there are no walls outside the "shaft" enclosure, so every level is open to every other level, then an unrated enclosure wouldn't increase the fire hazard of the space.