Hi, I am looking at different options for insulating the attic of a very complicated slate roof. The house has 3 main stories and a basement which has just gotten an air and vapor barrier installed. The roof line extends into the 3rd story behind knee walls and closets. The attic is almost entirely uninsulated and there are more rooms built in the attic making it difficult to access the floor and connections to the areas behind the knee walls. I am thinking of removing all of the walls in the attic (assuming they are nonstructural) creating ventilation channels in the rafter bays and insulating with batts, foam board, or cellulose, my concern is if there are roof leaks I won’t be able to see them behind the insulation. I’m wondering if there will be enough airflow to dry out the water or if I need to insulate differently. The house is on the coast in northern Maine.

Thanks, Jinen