If you have an attached garage, and especially if you have living space above your garage, make sure that your garage door is properly insulated. When we moved into our house we had a crappy, uninsulated metal garage door, and we ended up having a terrible time controlling the temperature in the bedroom above our garage. It was too hot in the summer and too cold in the winter. But I insulated the garage door this past winter, and that’s all behind us now.
The garage was decidely warmer all winter long, as was the room above it. Likewise, we’ve had much better temperature control this summer. While this is undoubtedly reducing our energy bills, the best thing about it is that it makes our house more comfortable/livable.
So how did I do it? While there are garage door insulation kits available for sale, I couldn’t find any at our local stores when I went out looking. Thus, I simply bought foam sheathing at Home Depot and cut it to fit in the garage door panels. The ‘pocket’ in the door panels is just over 1.5 inches deep, so I used a double layer of 3/4 inch sheathing, which I tucked behind the metal lip that runs around each panel. I then secured it all in place with aluminum foil tape — I considered using Liquid Nails, but wanted to be able to take it down if it didn’t work as I had hoped. And while I was at it, I also insulated our water heater (which is located in our garage) with a water heater blanket.
Note: A few words of caution… First of all, as several commenters have pointed out, you might need to re-balance your garage door due to the added weight. Unless you really know what you’re doing, this is best left to a professional. Also, foam board is flammable, and not meant to be exposed. Thus, there is some risk in using the method outlined above instead of a “real” garage door insulation kit.