I have been thinking of insulating my two-car garage door. It's a wooden door using a screw-drive lift (Genie Excelerator). I've seen that there are two possibilities: Foil-faced bubble wrap (for lack of a better term) and ordinary fiberglass insulation blankets. My garage is heated (laundry, hot water and boiler in the garage).

Which seems to do a better job? With a blanket, how much thickness is added? Did you have to get the spring re-tensioned after applying the insulation to take up some of the new weight added? I've lifted my door manually and found it quite heavy, despite the spring. I love my door opener, so I don't want to screw it up (pardon the pun). I'll go download the user manual for it to check weight tolerances.

Thanks for any info provided!