Rated shaft enclousers in PA

[mtf125]

I have a vertical shaft in a building that has supply and return ductwork in it. The ductwork exits the shaft runs horizontally on the floor and then enter another shaft. IBC 2000 requires the whole assembly to be rated, i.e. I have to wrap the ductwork with fire proofing. Does anyone know of a way I can get around not wrapping the ductwork or enclosing the ductwork with rated gypsum? I wanted to just install fire dampers at both shaft penetrations.
Please help.
Thanks

 

[DouginMB]

I don't see a problem with simply providing fire dampers at each shaft penetration.

 

[mtf125]

IBC 2000 (Section 707.5 Continuity) "These walls shall be continuous through concealed spaces such as the space above a suspended ceiling.". I have been trying to find a loop hole in the 711 section under penetration, but haven't had much luck.
Thanks