Is a damper needed here?

[Yikes]

Type V-A apartment building. Ceiling membrane at top floor is part of 1 hour roof assembly.
Ducts are rigid spiral. Attic provides space to route ducts from HVAC closet to ceiling registers.
Have you seen any typical UL F-C penetration that addresses this issue?

 

[klarenbeek]

Definitely needs a ceiling radiation damper with this setup, both at the mechanical closet lid and at the register locations. The other option would be to maintain the dwelling unit separation up through the attic to the bottom side of the roof deck if that's even possible based on trusses/rafters.

 

[Yikes]

Definitely needs a ceiling radiation damper with this setup, both at the mechanical closet lid and at the register locations. The other option would be to maintain the dwelling unit separation up through the attic to the bottom side of the roof deck if that's even possible based on trusses/rafters.

If I maintain the unit separation, do I still need a ceiling damper? (due to Type V-1hr construction, achieved via ceiling membrane on the roof trusses).

 

[steveray]

do I still need a ceiling damper? (due to Type V-1hr construction, achieved via ceiling membrane on the roof trusses).

You don't/ shouldn't generally need a damper due to construction type....

 

[klarenbeek]

The problem is that if your separation is the ceiling membrane, each duct penetration is an opening in it that needs to be protected. In the IMC, there are no exceptions for duct penetrations of rated horizontal assemblies.

 

[princeofpen]

Based upon the size of the duct you wouldn't meet any exception/s in 716.5.2 and would need dampers in place at each penetration