Mezzanine

[Sifu]

Consider a room with a mezzanine. For simplicity's sake lets call it a square box, type VB, NS. The square box has a mezzanine running the perimeter of the floor below, like a race track going around it. (This is not a gym with a racetrack). A portion of the mezzanine is cut off by walls that go full height on each end, but there is still a floor and 42" knee wall overlooking the floor below. The DP has it marked "no access to this area. No storage no occupancy of any kind". I believe this area is still considered in the area determination for the mezzanine whether occupied/used or not. Besides the fact that we know it will be used for something, I believe by definition it is a mezzanine, as occupancy or use is not stipulated in the definition. But as always, I am open to correction. I have never had this proposed before. And in playing my own devil's advocate, I wonder if it would be considered a mezzanine (or equipment platform...without equipment) if they called it a 10' wide shelf.

2018 IBC:
[BG] MEZZANINE. An intermediate level or levels
between the floor and ceiling of any story and in accordance
with Section 505.

2018 commentary:
A common design feature in factories, warehouses
and mercantile buildings is an intermediate loft, or
platform, between the story levels of a building.

FYI, as it is proposed, the "usable/occupied" portion of the mezzanine is exactly 1/3 of the room below, so this is an attempt at mitigating the area limitation. As an aside, they have already oversized the mezzanine because they have counted the enclosed portions of the room below so they will need to redesign it, but I would rather call their attention to it now so they don't just try to cut off a bigger chunk on resubmittal.

 

[Sifu]

Also, as VB, NS with proposed occupancies of M, A-2, S-1 and F-1 a second story would not be permitted, so this is more than semantics.

 

[e hilton]

Maybe have them build a partition at the edge of that area to block it from view below. So it truly is a non-usable space.

 

[bill1952]

I understand why it raises questions. I thought one of the reasons that requirements for a mezzanine we're less restrictive than a second floor was it's being open to the main floor. We're there a fire for instance on main floor, the openess would allow you to become aware of it much as sooner than if it were a second floor. The "many rooms" on the mezz bother me in blocking views. Just a thought.

 

[TheCommish]

What is the floor area below? divide by 3
What is the area of the intermediate floor? is this greater than answer from above, if yes design fails the exception for mezzanine. Consider it a 2nd floor, then does the design meet the requirements for 2 story building?


MEZZANINE. An intermediate level or levels between the floor and ceiling of any story and in accordance with Section 505.
Does not say anything about occupied, unoccupied or storage.

2015 IBC

505.2.1 Area limitation. The aggregate area of a mezzanine or mezzanines within a room shall be not greater than one-third of the floor area of that room or space in which they are located. The enclosed portion of a room shall not be included in a determination of the floor area of the room in which the mezzanine is located. In determining the allowable mezzanine area, the area of the mezzanine shall not be included in the floor area of the room.

Where a room contains both a mezzanine and an equipment platform, the aggregate area of the two raised floor levels shall be not greater than two-thirds of the floor area of that room or space in which they are located.
Exceptions:

1. The aggregate area of mezzanines in buildings and structures of Type I or II construction for special industrial occupancy in accordance with
Section 503.1.1 shall be not greater than two thirds of the floor area of the room.

2. The aggregate area of mezzanines in buildings and structures of Type I or II construction shall be not greater than one-half of the floor area of the room in buildings and structures equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1 and an approved emergency voice/alarm communication system in accordance with Section 907.5.2.2.

505.2.3 Openness. A mezzanine shall be open and unobstructed to the room in which such mezzanine is located except for walls not more than 42 inches (1067 mm) in height, columns and posts.
Exceptions:

1. Mezzanines or portions thereof are not required to be open to the room in which the mezzanines are located, provided that the occupant load of the aggregate area of the enclosed space is not greater than 10. Some mezzanines are enclosed. Over the pharmacy in CVS and the like is a stock storage mezzanine.

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.

3. Mezzanines or portions thereof are not required to be open to the room in which the mezzanines are located, provided that the aggregate floor area of the enclosed space is not greater than 10 percent of the mezzanine area.

 

[Sifu]

They have two exit stairs, and have an OL less than 10, so they don't need to be open to the floor below, but much of it is anyway. The question boils down to whether the "unoccupied" area with no access but a 10' wide floor with knee walls is still considered a mezzanine. As an "intermediate level" or a "platform" I think it does. As E Hilton says, build a full height wall and the question might go away. But what if there were no knee wall at all? Or it was constructed of a "floor" that is not capable of supporting live loads? Can they just call it a shelf and move on? I ask because I try to anticipate the responses and artfully head them off so that this issue doesn't end up getting ping-ponged back and forth, costing me time as well as them.

The DP has classified most of the mezzanine is as S-1, which is limited to one story, but even if considered "accessory storage" to the main occupancy, which is an M, it would then become part of the M occupancy, and still be limited to one story, so IMO it does not meet the limitations of t504.4 as a two story, VB, NS structure. I don't think they have any option other than to reduce the size of the mezzanine (based on the enclosed spaces below), the only question is by how much, because if the "unoccupied" portion is considered a mezzanine, the occupied portion has to get a lot smaller.

 

[JMarsh]

The DP has classified most of the mezzanine is as S-1, which is limited to one story, but even if considered "accessory storage" to the main occupancy, which is an M, it would then become part of the M occupancy,

I don't see that is can be classified as an Accessory space due to it's being larger than 10% (506.2.3). That would kick you into separated or non-separated mixed use.

 

[JMarsh]

edit 508.2.3. (I'm new here. How to edit a post?)

 

[steveray]

I have recommended that people wall of a portion of a mezzanine when CPET is an issue....This isn't much different, but I would look at it pretty closely before deciding and talk with the FM that may do the ongoing inspections and note it to death.....

 

[Sifu]

I don't see that is can be classified as an Accessory space due to it's being larger than 10% (506.2.3). That would kick you into separated or non-separated mixed use.

If they chose to call it accessory storage instead of classifying it as S-1 they could as long as they are accessory to the main occupancy, there is no 10% limit to the area used such as there is for an accessory occupancy from 508.2. The difference in my opinion is that as an S-1, they can store whatever they want as long as it meets the criteria of 311.2, but as an accessory storage, it must be accessory to the primary use and so it is presumed to be of the same hazard as the main occupancy. See IBC 311.1.1. But it won't help them since the main occupancy is an M and it is restricted to a single story. So either way, S-1 or M with accessory storage, both are restricted to a single story.

 

[Paul Sweet]

Want to take bets on how long those walls stay after they get a CO?

 

[Sifu]

Want to take bets on how long those walls stay after they get a CO?

The walls on either end will definitely end up with doors in them, but I don't review what is not there. At this point, unless I get more education I am calling it a mezzanine and restricting the size of the mezzanine to include this space. Their indent seems pretty clear, but I try to stay out of the intent idea and just review what exists. And if a mezzanine exists that does not meet the restrictions I won't proceed. I would bet a week's pay that it will be used for storage and display once in operation, if not additional office spaces. We'll see what happens.

 

[steveray]

[A] 105.1 Required. Any owner or owner’s authorized
agent who intends to construct, enlarge, alter, repair, move,
demolish or change the occupancy of a building or structure,
or to erect, install, enlarge, alter, repair, remove, convert or
replace any electrical, gas, mechanical or plumbing system,
the installation of which is regulated by this code, or to cause
any such work to be performed, shall first make application
to the building official and obtain the required permit.

[A] 114.1 Unlawful acts. It shall be unlawful for any person,
firm or corporation to erect, construct, alter, extend, repair,
move, remove, demolish or occupy any building, structure or
equipment regulated by this code, or cause same to be done,
in conflict with or in violation of any of the provisions of this
code.