They sell insulation kits at the local big box hardware store and I cringe every time I see them. The box weighs about 15 pounds, which doesn't sound like a lot. It is definitely enough to un-balance a garage door. The springs are calibrated for the weight of the door, and adding weight makes the door "heavy" for the springs. This means that if you pull an operator disconnect handle when the door is in the open position, the door is likely to descend much more quickly than you anticipate. People have been hurt when a garage door came down on them and the momentum knocked them over. Only add weight if the door springs can be re-torqued or replaced with springs of the proper pull.
Garage door springs come in two styles: torsion (see above), which mounts on the header above the door, and extension (Photo 1), which floats above the upper roller track. In the past, extension springs were safer to install but didn’t have containment cables running through the center of the spring. Without cable, these springs become dangerous, heavy whips when they break. They also tend to be noisier than torsion springs, and we recommend you use them only if you don’t have the 12 in. of headroom above the door that a torsion spring requires.
Remember, not all garage door springs are alike. They are not one size fits all. If yours breaks, make a note of the brand and color code on the spring you need to replace. We'll get you the garage door opener parts you need, from seal kits to torsion and extension spring kits. Save money by replacing garage door hardware instead of replacing the whole unit.
Just in case you still want to know: You could glue foam panels to the inside of the door, but it would be better to just pressure fit them in place to avoid the weight of the glue. Any weight that you add to the door has the very real potential to unbalance the door. If the springs were a little "hot" or strong to start with, it may not be a bad thing to add weight. If the springs were the right ones, even a few pounds will un-balance the door. If they were too weak to start with, any additional weight is going to make it worse.
Great! We specialize in all sorts of garage door repair work. Working around the garage door can be fairly dangerous if you’re trying to repair this issue on your own. Most garage door companies will quickly remind folks about this, and it’s true. Their are some hazards to watch out for when working around these heavy and high tension doors. We recommend you give an expert a call to address the issue in a safe and timely manner for you.