Library Balcony - Floor Fire Resistance?

[MKALLAY]

I have someone looking at a project that involves an addition to an existing historic building. The existing construction is generally non-combustible (concrete and masonry) and the proposed project could meet height and area requirements including the new addition with a construction type of IIA. At issue is a tall library space that has full height shelving, and a walkway at an intermediate level to access higher shelving. The walkway is of unprotected steel construction. Applicable code is California 2022 (based on IBC 2021)

The question that has come up, is the walkway considered a "floor", and if so, would a fire rating be required as per Table 601? Or, would it be possible to consider this a special occupancy element as per Section 410.2.2 Technical Production Areas: Galleries, Gridirons and Catwalks? In that case, a fire rating of the gallery would not be required. I am leaning towards the latter interpretation but would be interested in any feedback!

 

[Joe.B]

Mezzanine?

 

[walker.t]

The question that has come up, is the walkway considered a "floor", and if so, would a fire rating be required as per Table 601?

Sounds like a mezzanine to me. Per IBC 2021 505.2, the mezzanine does not count towards your story count.

Regarding construction type:

Commentary on IBC 505.2 (partial quote)
This section does not include any special requirements for the construction of a mezzanine or for fire-resistance ratings; therefore, the mezzanine is to be constructed of materials consistent with the construction type of the building. Required fire-resistance ratings are determined on the basis of Table 601 for the appropriate construction type.

Or, would it be possible to consider this a special occupancy element as per Section 410.2.2 Technical Production Areas: Galleries, Gridirons and Catwalks?

No. “Technical production area” is defined in IBC Chapter 2:

2021 IBC definition of Technical Production Area (partial quote)
Open elevated areas or spaces intended for entertainment technicians to walk on and occupy for serving and operating entertainment technology systems and equipment.

Library patrons and staff are not entertainment technicians, books are not entertainment technology systems and equipment.

 

[MKALLAY]

OK; I was also relying on 410.1 Applicability: "The provisions of Sections 410.1 through 410.7 shall apply to all parts of buildings and structures that contain stages or platforms and similar appurtenances as herein defined". But that definition for Technical Production Area seems to narrow down the possible scope outside of the condition we are looking at.

 

[Yankee Chronicler]

I have someone looking at a project that involves an addition to an existing historic building. The existing construction is generally non-combustible (concrete and masonry) and the proposed project could meet height and area requirements including the new addition with a construction type of IIA. At issue is a tall library space that has full height shelving, and a walkway at an intermediate level to access higher shelving. The walkway is of unprotected steel construction. Applicable code is California 2022 (based on IBC 2021)

The question that has come up, is the walkway considered a "floor", and if so, would a fire rating be required as per Table 601? Or, would it be possible to consider this a special occupancy element as per Section 410.2.2 Technical Production Areas: Galleries, Gridirons and Catwalks? In that case, a fire rating of the gallery would not be required. I am leaning towards the latter interpretation but would be interested in any feedback!

I would need to see more detailed drawings. Is there a "floor" on which the upper level of library shelves is installed, or is the upper aisle walking surface a catwalk grate type affair that's part and parcel of the library shelving system?

 

[MKALLAY]

We currently do not have the details, but here is an image of the existing space:



The space houses a rare book collection, and is built almost like a vault, with concrete walls, and floor/ceiling assemblies. The books are located above in glass cases, and are retrieved by staff upon request; as currently used, the public do not access the upper level. The walkway has a clear width of 30". Again, this is an existing space, and no change is proposed here, but we need to establish the construction type for the building in order to justify an addition in another area of the building.

An interesting problem!

 

[LR419]

Mezzanine?

Yes.

 

[Yankee Chronicler]

That's a mezzanine floor, not part of a tall shelving system as originally described. In fact, that space in nothing like the description in the opening post.

It's a floor. In construction type II-A it requires a 1-hour fire resistance rating, per IBC Table 601.

 

[TheCommish]

Depending on the area of the upper level v. The open area below it could be a mezzanine, having glass front or a partition does not exclude the area from being a mezzanine.

Next what code was rhe building constructed under if any? How is the proposed addition connecting to the original building, could it be considered or constructed to be a separate building, then the existing building construction maybe less important.

 

[Yankee Chronicler]

Depending on the area of the upper level v. The open area below it could be a mezzanine, having glass front or a partition does not exclude the area from being a mezzanine.

I wrote that it's a [mezzanine] floor. I didn't say it's a story. There's a difference. That's not a catwalk grate that's an integral part of a book shelf system, which is what the opening post appeared to be describing. That's part of the building, not part of the FF&E.

However, you raise a good point -- depending on what's going on in the rest of the building, it actually might be a story rather than a mezzanine.

 

[TheCommish]

I confused floor with story in my mind.

 

[bill1952]

Since I was the proponent for "technical production areas" in the codes, this caught my attention. Obviously these elevated floor areas are not TPAs, but based on limited access and other characteristics I'm not sure how protecting them like a 2A floor adds needed safety. Doesn't feel like a condition that the codes ever specifically considered.

 

[MKALLAY]

Since I was the proponent for "technical production areas" in the codes, this caught my attention. Obviously these elevated floor areas are not TPAs, but based on limited access and other characteristics I'm not sure how protecting them like a 2A floor adds needed safety. Doesn't feel like a condition that the codes ever specifically considered.

bill1952, thanks for that - it does seem that the condition presents a similar level of risk as a TPA, but given the specific wording of the definition, clearly outside of the original scope of applicability.

I will add - the project designer has found there is a provision in the California Historic Building Code that may offer some relief on this item (I was not aware there was a Historic Building Code!). The question to confirm there is if we can qualify.

Thanks, everyone above who provided comments! As I tell our staff - knowledge is power!