Steve writes from Saint Paul, Minnesota: "The sloping roof in our upstairs bedrooms consists of asphalt shingles, 3/4" board sheathing, 2 x 4 studs with Balsam Wool insulation between them, and untaped gypsum board at the ceiling. The face of the Balsam Wool where I can see it looks to be in good condition and I can't easily remove it because of a knee wall, so I plan to remove the gypsum board, leave the Balsam Wool in place and then add 2 inches of rigid insulation (Foamular 150) and new gypsum board to the room side of the studs. My concern is that the high R value of the foam insulation compared to the Balsam Wool insulation will put the existing vapor barrier of the Balsam Wool on the outside of most of the insulation value instead of on the inside. Do you think I will have any problems with this proposal? What about putting the rigid insulation and new gypsum board over the existing gypsum board instead of removing it?"

Answer: My friends at Owens Corning are not familiar with balsam wool, having never made the product, but they suggest you consider slitting the vapor retarder on the existing insulation before installing the FOAMULAR® insulation.