architect629
Member
We do a lot of projects that are sprinklered but still require separation of incidental uses with a 1 hour fire barrier, per 2018 IBC Section 509. We've done a handful of fit outs in single story unprotected combustible type IIIB or VB buildings. We've always directed the contractor to extend the fire barrier to the underside of the roof sheathing (per IBC 707.5), fire stop the joint between the wall and roof, and fire stop any penetrating wood structural members. I know there is no UL assembly for this condition, but an AHJ or inspector has never raised an issue with this approach.
We're now working on a new project in a 5B building and GC is giving us push back to this approach. I reached out to Hilti for an engineering judgement, and they can only provide a firestop joint detail with a 1 hour F rating if the roof/ceiling assembly is also fire rated. We can provide a rated roof/ceiling assembly, and based on 509.4.1 (below), I don't believe we need to rate the entire supporting structure of the roof. We've just never been required to do this before.
Does anyone else have experience with this kind of condition? How are you addressing joint condition between a rated wall assembly and a wood roof/floor construction?
We're now working on a new project in a 5B building and GC is giving us push back to this approach. I reached out to Hilti for an engineering judgement, and they can only provide a firestop joint detail with a 1 hour F rating if the roof/ceiling assembly is also fire rated. We can provide a rated roof/ceiling assembly, and based on 509.4.1 (below), I don't believe we need to rate the entire supporting structure of the roof. We've just never been required to do this before.
Does anyone else have experience with this kind of condition? How are you addressing joint condition between a rated wall assembly and a wood roof/floor construction?