Garage door insulation cuts energy bills and street noise. Here's how to insulate your garage door yourself. Garage door insulation can make your life warmer, cooler, and quieter. It lowers energy bills, acts as a barrier between you and street noise, and brightens an otherwise dreary space. Garage door insulation is an easy DIY project; it’ll cost you about $200 to insulate two 9-foot-wide doors. Types of Insulation Any insulation type will increase the energy efficiency of your garage door. Here are the most popular types to apply to the back of garage doors: Batt insulation. This flexible insulation, often found stuffed into exterior walls, is commonly made of fiberglass. It’s usually backed by paper or foil, which act as vapor and air barriers. Insulating values are R-3 to R-4 per inch of thickness. Cost is about 30 cents per square foot. Foam board insulation. These rigid panels, typically made from polystyrene, provide a high insulating value for rela