Steve writes from Saint Paul, Minnesota: "I would like to upgrade the insulation in an upstairs room that has knee walls and slant walls with Balsam wool insulation between the 2 x 4 studs. The facing of the Balsam wool appears to be in good condition, so I plan to carefully remove the existing gypsum board, but leave the balsam wool in place and then install 2 inch rigid insulation (Foamular® add generic 150) on the inside of the studs. I would then cover this with new gypsum board. Do you foresee any problems with this? My concern is that the Balsam wool has a lower R value than the rigid insulation, which would put its vapor barrier on the wrong side of the majority of the insulation."

Answer: Fiber glass insulation would be the best option in the situation you describe. It would be labor intensive to cut each piece of FOAMULAR® insulation and place it snugly between the studs. Also, the back side of knee walls would most likely have to be covered with a 15 minute thermal barrier because of building code requirements. Heat could also be a factor with the application being up in an attic or rafter assembly. I recommend PINK FIBERGLAS™ insulation.