I have an unfinished attic that has several items in it making it impossible at this time to remove the floor boards and add insulation. There presently is some old fiberglass batts that have lost a lot of their loft. Before this heating season begins, could I add some mineral wool to the roof rafters and minimal exposed wall areas for the time being until I can remove flooring(boards) and install the mineral wool there? Do I need to cover this with drywall on the ceiling since this does not burn? If this is acceptable, what would be the best way to attach it to the rafters? When I install this in the floor, would I have to remove the insulation I added to the roof? It will be easier to get this done before winter sets in that to install in floor. Please comment. Sorry, I don't like cellulose for a variety of reasons.