jar546
CBO
Question in Detail:
In a Type VB, Group R-2 occupancy, multifamily, three-story building with fire partitions terminating at the underside of a 1-hour rated roof/ceiling assembly, there's a provision in the 2018 IBC Section 711.2.3 that grants an exception. This exception states that supporting construction for horizontal assemblies separating units isn't obligated to have a fire-resistance rating. The purpose of the rated roof/ceiling assembly is to establish unit separation as mandated by Section 420.
In this scenario, should the exterior walls be fire-rated, or do they qualify for exemption under Section 711.2.3's exception? Our understanding is that the exterior walls don't require a fire rating and fall under the exception.
Opinion: This opinion is also applicable to the 2021 and 2024 IBC.
In essence, the 2018 IBC Section 711.2.3 generally mandates that supporting construction be fire-protected to meet the necessary rating of the supported horizontal assembly. However, there's an exception to Section 711.2.3 that pertains to three specific applications for construction supporting horizontal assemblies in buildings of Type IIB, IIIB, or VB construction. Application #2 of this exception explicitly exempts supporting construction for horizontal assemblies needed for the separation of dwelling units and sleeping units, as specified in Section 420.3.
Since the proposed 1-hour rated roof/ceiling assembly isn't actually separating dwelling units and sleeping units on different floors but is primarily maintaining the required fire separation continuity between dwelling units, I believe that the exterior walls of the Type VB building supporting the 1-hour rated roof/ceiling assembly align with application #2 of the exception to Section 711.2.3. Consequently, they are not required to have a fire-resistance rating due to supporting construction.
Do you agree?
In a Type VB, Group R-2 occupancy, multifamily, three-story building with fire partitions terminating at the underside of a 1-hour rated roof/ceiling assembly, there's a provision in the 2018 IBC Section 711.2.3 that grants an exception. This exception states that supporting construction for horizontal assemblies separating units isn't obligated to have a fire-resistance rating. The purpose of the rated roof/ceiling assembly is to establish unit separation as mandated by Section 420.
In this scenario, should the exterior walls be fire-rated, or do they qualify for exemption under Section 711.2.3's exception? Our understanding is that the exterior walls don't require a fire rating and fall under the exception.
Opinion: This opinion is also applicable to the 2021 and 2024 IBC.
In essence, the 2018 IBC Section 711.2.3 generally mandates that supporting construction be fire-protected to meet the necessary rating of the supported horizontal assembly. However, there's an exception to Section 711.2.3 that pertains to three specific applications for construction supporting horizontal assemblies in buildings of Type IIB, IIIB, or VB construction. Application #2 of this exception explicitly exempts supporting construction for horizontal assemblies needed for the separation of dwelling units and sleeping units, as specified in Section 420.3.
Since the proposed 1-hour rated roof/ceiling assembly isn't actually separating dwelling units and sleeping units on different floors but is primarily maintaining the required fire separation continuity between dwelling units, I believe that the exterior walls of the Type VB building supporting the 1-hour rated roof/ceiling assembly align with application #2 of the exception to Section 711.2.3. Consequently, they are not required to have a fire-resistance rating due to supporting construction.
Do you agree?
