Fire blocking a wood stud wall built against cinder block.
I am building a game room in the basement. One wall of the game room is against the cinder block basement wall which is coated in Drylok to prevent water ingress. Because the cinder block wall is not plumb, the treated wood studs vary from 1.5” to 0” from the cinder block – I started with the base plate 1” from the bottom of the cinder block but later found the cinder block wall bulged inward even more. The studs have a base plate and a top plate of treated lumber. The back of this new wall is thus open to the cinder block and there are variable gaps between the back of the studs and the cinder block & certainly a 1” gap at the bottom. The question is how do I adequately fire block this wall? Can I simply stuff (may be extra) fiber glass insulation between the studs and directly against the cinder block? If so can this insulation still have a vapor barrier or must it be unfaced? If fiber glass cannot be used, what can? – Perhaps mineral wool instead? Would I have to use fire blocking foam to fill the gaps between the back of the studs themselves & the cinder block? By chance, there is about 3-4” of the aluminum sheet the builder placed between the top of the cinder block and the main house joists protruding from the top of the cinder block. It currently is bent downwards by the proximity of the top plate of the new game room wall. Could this somehow be part of any fire block in this area?
Thanks for any insights.