We have an attached garage with a roller shutter door made by Bunka Shutter (文化シャッター). In the winter, the ice that melts off the car puddles up on the garage floor and the radiant heat from our home creates condensation on the inside of the garage door. This then freezes and the door (and where it touches the floor) gets covered in ice, seals it shut, and prevents it from opening.
Solution: Keep your garage door slightly open about an inch — no condensation.