Appeal 34944

2022 OSSC 703.2.1

A fire-resistance rating of building elements, components or assemblies shall be determined by the test procedures set forth in ASTM E119 or UL 263. The fire-resistance rating of penetrations and fire-resistant joint systems shall be determined in accordance with Sections 714 and 715, respectively.

Equivalency of two-hour rated assembly in lieu of two-sided UL Assembly.

Two assemblies are proposed for equivalent ratings, one at the interior wall and the other at the floor ceiling assembly. A (2) hour fire separation is required per Code Guide OSSC/27/#1 for interior generators.

Interior Wall (Exhibit D - Wall Assembly 2) - An existing 8" CMU wall separates the generator room from adjacent spaces or at the exterior, providing the basis for fire separation. An additional (2) layers of 5/8" GWB - Type X and light gauge furring is proposed to capture structural items at the interior of this existing wall.

Floor/Ceiling Assembly (Exhibit D - Assembly A) - Existing 2x4 wood decking and a layer of GWB currently separate the generator space from the story above. The design proposes repairing the existing GWB and adding a second layer of 5/8" GWB - Type X. In addition, structurally independent light gauge framing is added below the lowest wood support beam with hat channels and (2) layers of 5/8" GWB. The light gauge framing cavity will be filled with mineral wool insulation, a K-13 acoustical treatment is proposed below the lowest GWB layer.

See (Exhibit E) for rated connection details for capturing existing wood framing members and for termination of the other - UL listed - fire separation within the area.

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See (Exhibit F) for clarification of proposed assembly and it's relationship to tested assembly GA FC 5710 and GA FC 4370. The proposed assembly is a combination of both assemblies to provide a combined (2) hour fire separation integrating the existing wood framing and sub-floor for the floor above.

The non-combustible framing and GWB furring/finishes will be installed per GA FC 4370. Modifications from the tested assembly are highlighted and clarified. These include 6" framing instead of 8" framing, 5/8" GWB instead of 1/2" GWB, and hat channels rather than resilient channels. This assembly is used for fire separation only; not as a sound separation assembly.

The upper portion of the assembly - including the existing framing and subfloor - will mirror GA FC 5710. Modifications are highlighted - including omission of a resilient channel as the sound separation is not required. Type X GWB is proposed in lieu of Type C, given the additional furring layer provided below.

This appeal requests that the existing cardecking (2x4 on end) meets equivalence for a (2) hour rating within GA FC 5710 to the the two layers of 15/32" plywood subfloor and finish floor.

A non-emergency generator is proposed within this building; requiring a (2) hour fire separation from adjacent spaces. (See Exhibits A, B & C for areas of work)

The existing structure supporting the story above is exposed wood framing, including support columns separate from the exterior wall. Existing masonry walls separate the space, but full grouting conditions are unknown. The design proposes adding a minimum of (2) layers GWB - Type X to the interior of the new generator room to provide protection of existing structural members and to provide a inspectable smoke/fire separation.

Modifying the existing structure or testing the existing assemblies per a UL listing is infeasible.

Note that the generator is proposed as natural gas with a direct connection to a gas line. No fuel tank within the generator room is proposed.

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Note: The generator is considered non-emergency as fire life safety systems are not connected to the power source. The generator does supply STANDBY power for normal building loads in case of a power outage.

The project team wishes to maintain the existing framing and subfloor and incorporate it within a combined (2) hour rated fire assembly required by the inclusion of the new generator. As the existing structure does not match an available tested and listed rated assembly, a hybrid approach between two listed assemblies is proposed.

The risk to fire life safety is assumed to be greater from within the generator room itself, leading the team to focus on a creating an new inspectable assembly of at least (2) layers of GWB, to protect the existing wood structure above. Additional layers of GWB are recommended for acoustical separation, leading to the additional rated assembly underneath the existing cardecking to provide extra protection and to verify a smoke seal at that assembly.