Appeal 19049

703.2

The fire-resistance rating of building elements, components or assemblies shall be determined in accordance with the test procedures set forth in ASTM E 119 or UL 263 or in accordance with Section 703.3. Where materials, systems or devices that have not been tested as part of a fire-resistance-rated assembly are incorporated into the building element, component or assembly, sufficient data shall be made available to the building official to show that the required fire-resistance rating is not reduced. Materials and methods of construction used to protect joints and penetrations in fire-resistance-rated building elements, components or assemblies shall not reduce the required fire-resistance rating.

Vallaster Corl Architects are overseeing construction of a new 7-story residential building in Portland, Oregon. The project includes 5-stories of Type III-B construction over 2 stories of Type IA construction. Members of horizontal assemblies in Type IA construction that have direct connections to columns are considered primary structural members per §202 of the 2014 OSSC. Primary structural members are required to be 3-hour fire rated per Table 601.

§704.3 allows protection to either be through individual encasement or membrane protection for structural members when not supporting a load bearing wall. The proposed design provides two levels of protection: (1) encasement protection per UL N307 that is installed inside a (2) 2-hour fire rated membrane cavity per UL D503.

As an alternate design, the project would like to request the flexibility to provide encasement protection to the structural beam per the 3-hour fire rated UL N307 (assembly details attached, further analysis in attached engineering judgement letter) or per the 3-hour fire rated UL N309 (assembly details attached, comparable to UL N307 except N309 uses mineral wool batts and blankets instead of mineral wool boards).

The proposed design is compared to a 3-hour fire rated restrained beam in the attached engineering judgement letter (EJ), per UL N307, to achieve the required minimum fire-resistance. However, the proposed steel beam (W16x26) is smaller than the tested steel beam (W8x28), and the proposed encapsulating mineral boards (Rockwool Comforboard) are different than the ones used in the tested assembly (Albi Dri-Clad)—hence the request of this appeal.

The proposed design has been reviewed and analyzed in the attached EJ letter—stamped by an Oregon registered fire protection engineer. The proposed protection of the structural beam includes two levels of protection, encasement protection per UL N307 (3-hour fire rating) installed inside a 2-hour fire rated membrane cavity per UL D503. Although the proposed beam is smaller than the UL N307 tested beam, the beam size does not play an active role in the fire rating of the proposed design (see Sections 5 and 6 in the attached EJ letter).

Additionally, the proposed mineral boards are greater in thickness and density than the tested boards used to achieve a 3-hour fire rating in UL N307—while other components of the proposed design provide equivalent or greater protection (Table 1 of the attached EJ letter). The proposed design will comply with the minimum required 3-hour fire-resistance per Table 601 of the 2014 OSSC, for protection of a primary structural member in Type IA construction.

Based on the analysis provided in the attached EJ letter and the conservative justification that the proposed design will provide at minimum equivalent protection to the tested 3-hour fire rated beam, UL N307, we urge you to grant this appeal.