Mark writes from Round O, South Carolina: "I want to install additional insulation in my attic. There is blown insulation between the ceiling joists now but my concern is that there isn't a vapor barrier beneath the existing. Should I should remove it and install kraft faced underneath or will unfaced batts over the existing be sufficient?"

Answer: Most communities require a vapor retarder but its use and placement varies throughout the U.S. depending on humidity levels. Your local building code official makes those decisions and any exceptions. Some building codes do not require a vapor barrier in your situation if the attic space has sufficient ventilation. If you need a vapor barrier, consider getting a "paint on" vapor barrier for the ceilings below the attic. This paint can be found at any local paint shop.