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2x4 truss runner penetrating 1 hour rated tenant wall.

R

RPM001

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Apr 17, 2019
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14
Location
Ft. Lauderdale FL
We are building apartments in South Florida which are separated with a 1hr fire rated drywall tenant wall (the building has fire sprinklers). Above the tenant wall sits a truss which is wrapped with fire rated drywall and achieves the 1 hour requirement as well. In that attic space we have some penetrations for fire sprinkler pipe, plumbing pipe, electrical conduit - all of which we have fire stop pipe collars, etc.

However we also have 2x4 yellow pine wood runners attached to the trusses which penetrate through the 1 hour fire wall which the inspector did not like (the runners span the entire length of the building and impact every unit). Any idea on a UL detail or how to make that 2x4 penetration compliant with fire stopping measures?
 
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Those would be the truss braces. Any chance you could ask the engineer if they could be cut off at the demising walls? It’s possible the roof sheathing provides adequate bracing, in addition to the braces that would remain connected to the trusses within the individual apartment attic area.
 
The walls between apartments are only required to be fire partitions--they do not need to extend through the attic to the roof deck if the roof assembly is a 1-hour assembly with the ceiling forming the fire-resistive plane. Section 708.4.2 allows draftstopping per Section 718.4 above the fire partitions, which do not require through penetration protection.

If the building is sprinklered throughout per NFPA 13 (which requires sprinklers in concealed spaces), then no draftstopping is required; thus, it could be wide open in the attic. If sprinklered throughout per NFPA 13R, and the attic space is sprinklered too per NFPA 13, then again no draftstopping required.
 
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