Yes, for 1-hour rated G500, L500 and P500
series floor-ceiling assemblies,
fiberglass insulation may be added to the plenum or joist space above the gypsum wallboard provided
an additional layer of gypsum wallboard is added to the assembly.
Can I add glass fiber insulation to
a fire rated partition design when it is not specified as a component?
Yes, glass fiber
insulation of a thickness
not exceeding the depth of the stud is OK to add to the wall stud cavity.