Mike writes from Covington, Louisiana: "My entire house is framed in 2 X 4.The rafters are 2 X 4 trusses. The floor joists are 2 X 4's also. Most of the ceiling above the original house's living space has blown insulation. However, the space above what used to be the garage, and is now an office, has no insulation at all. What do you recommend for insulation above the garage? Remember, these are 2 X 4 joists."

Answer: If you are limited to the spacing provided by a two-by-four joist, we recommend using R-15 FIBERGLAS™ insulation, a higher-density product made for 3-1/2" cavities. If the framing allows insulation to go above the size of the framing, you can use a higher R-value. If the space above the office is not conditioned, we recommend using a Kraft-faced insulation. Install the insulation with the paper installed toward the warm-in-winter side of the 2 by 4 framing. If you go beyond R-13 or R-15 with batt insulation, install the first layer to fill the 2 by 4 cavity and place the next layer perpendicular to the first.