I live in a rowhome where directly attached is another home. The homes use to have a front porch and through the years almost everyone has combined the porch into a living space. Because of this, the from roof of my living room is combined with the front-roof of the property next to me. I have removed the ceiling and can reach into the airspace above their property. I'm worried about fire hazards and am already experiencing problems with rodents that i believe are coming from this way.
I was going to put cement board to seal between the two properties(for fire and rodent) and fiberglass batt insulation along the roof since this uninsulated 'porch roof' is already making the area cold but i'm worried this will somehow affect the airflow and lead to dry rot or other issues. Any advice? (also, i plan on adding can/recessed lighting in this ceiling area to light the room underneath)