plenums in rated roof cieling assemblies

[tim walocha]

2012 IMC Section 302.3
Stud Cavity and Joist Space Plenums. Stud wall cavities and the spaces between solid floor joists to be utilized as air plenums shall comply with the following conditions.
1. .......
2. Such cavities or spaces shall not be part of a required fire-resistant rated assembly.

I have a rated roof ceiling assembly using triangular roof trusses. No solid floors. Cam this space be used as a plenum?

Section numbers please and thank you!!

 

[Francis Vineyard]

It can according to Sections 602.1 and 602.2

Section 602.3 (aka 302.3) is for spaces between studs and joist.