How to Insulate Your Garage This Winter Anyone who lives in the Midwest knows just how important insulation is in winter. When temperatures drop below freezing, your body and home need an extra layer of protection to keep heat in and the cold out. Your garage door is no different. A garage door without insulation is like a light jacket, which doesn’t do much good when it’s below freezing outside. But add insulation and now your garage door is like a goose down parka, which can stand up to the coldest temperatures. Besides keeping the cold at bay, insulation also acts as a barrier between street noise and your garage, ideal if your garage is attached to your home.