I have the same moisture problem in my attic. This moisture has cause the growth of mold/mildew on the underside of the roof plywood. I also have a ridge and soffit venting. I was wondering does anyone know who or how to remove this mildew? Since I use the attic for storage,I can not add addition insulation above the ceiling. I was thinking of adding insulation between the roof rafters. I thought I could use either roll or sheet insulation. I believe if I used roll insulation I would have to provide air space between the roof sheathing and the insulation. Any thoughts?