I'm removing old wood paneling and drywall which is glued to (what appears to be regular Styrofoam) foam board, which is glued to a cinder block basement wall. The goal is to add more insulation (2x4 framing + rockwool) to the existing foam board (R10 -> R24).
The issue is that pulling the drywall down is ripping chunks out of the existing foam board - up to 1/2" deep so far - I was hoping to leave in place. The foam should act as vapor barrier, right?
Do I need to patch it somehow (low expanding spray foam?) before installing framing? Any value in replacing all the old foam with newer product?