Need UL-listed 1-hour soffit assembly around pipes at ceiling

[J La]

Working on a restaurant project in a Type-IA structure. We have a Pollution Control Unit (PCU) that's required to be within a 1-hour rated enclosure. There are some existing plumbing drain lines at the ceiling that run along one side of the room, but we are not allowed to have any pipes within our rated enclosure that do not serve the PCU. The building inspector said we can soffit around these pipes with a UL-listed/tested assembly.

I have been all over the USG, UL, and other sites (plus ChapGPT) looking for such an assembly, but am coming up empty handed. Here's what I need:

1. UL-listed/tested soffit assembly (both vertical and horizontal assemblies
2. Soffit will be framed with metal studs
3. Rated soffit assembly will need to be 1-sided (asymmetric), as we'll only be able to apply GWB to the "outside" of the soffit once it's framed

I did find UL V497 (3-5/8" metal studs, (3) layers Type X GWB), but this is only tested for vertical assemblies.

FYI, existing ceiling assembly is 1-hour rated composite concrete deck, steel beams, all with spray-applied fire-proofing, and the 4 walls around the PCU enclosure are 1-hour UL U419).

 

[JPohling]

Perhaps use a shaft wall assembly that can be constructed from just a single side.

 

[RLGA]

For the horizontal, look at UL Designs I501, I504, I505, I506 System A, and I507. You can use a symmetrical wall system for the vertical (frame and apply gypsum to both faces and then attach the horizontal), or consider UL Designs V497, W415, and W443 for a single-sided system.

 

[J La]

Thank you @RLGA! I believe I507 for the horizontal portion and V497 for the vertical portion gets me where I need to be. Both are 1-sided with 3 layers of GWB (plus insulation for the vertical assembly).