John writes from Islip, New York: "I hired a contractor to install vinyl siding. He insists on not taping the seams of the insulation board under the siding. How much energy is lost through these seams, and is it important."

Answer: We recommend taping the seams to help prevent water intrusion into the wall system. If you are installing new siding over existing siding it probably won't matter. If it is new construction, I would tape the seams when installing the foam insulation. Energy savings is only a small part of the benefit.