Insulate garage door with pipe foam
To insulate the bottom of the garage door in a very easily and cheap way I just bought 3 meters of pipe insulating foam for 3 euros. The pipe insulation foam is very flexible and light and a very cheap material to keep the pipes from freezing in winter and comes as tubes with an opening in the side to easily adapt them to the pipe. I though of using this opening side or pre-slit to put it on the bottom of the garage door. This is not a complete insulation method for a garage door but it helps a lot to keep the cold away. It took me less than five minutes to adapt the foam to the bottom of the door. Here is a short video on how I did it