Steve writes from Spartanburg, South Carolina: "Has there been any research done to compare a 2x6 wall construction fully insulated vs. a 2x4 wall construction fully insulated? Would the energy savings pay for the extra material cost (disregarding labor)? What is the best insulated wall system for a home from the outside (using brick or stone) to the inside? Could you also give me information on the ceiling/roof and the floor/crawl space? I know of a person who installed a 'foil' of some kind against his rafters. He says this keeps his attic several degrees cooler in the summer than his neighbor's house without it? What do you know about this?"

A 2x6 wall is a better wall and will pay for itself. As to how long it will take to pay for itself is hard to say due to the large variation in building material and energy costs. When using a brick or stone veneer I feel a better wall would be one that encompasses rigid PINK foam on the exterior. Foam board reduces the heat transfer that occurs through the framing and slows the moisture drive that can happen when a wet brick wall heats up from the sun. A 2x4 wall with 1 inch foam has a better system R-value than a 2x6 wall with no foam. Radiant barriers in the attic do reduce the attic temperature but they can increase the temperature of the roof, which could reduce the life of the shingles. Adding insulation to the floor of the attic will have a greater impact than the foil on the energy efficiency of the home, provided you can add insulation to the floor. Even if you can reduce the attic temperature with a radiant barrier you really have not done anything to reduce the heat gain to the living space of the house.