Tom writes from Hyde Park, Massachusetts: "I want to insulate my attic roof. However, the joists are not 16" on center. They range from 21" to 22". Where can I buy rolls to accommodate this situation?"

Answer: Owens Corning manufactures insulation that is either 15" or 23" wide. My suggestion is to cut the 23" product, which can be a challenge when working on the ceiling of the attic. I assume your attic is or will be conditioned, meaning heated and or air conditioned. Otherwise, there is no need to insulate the attic roof. For unconditioned attics, insulate the floor above the rooms that are heated and/or conditioned and make sure there is adequate ventilation in the attic.