Using your drill, add tension to the torsion spring. This system uses a single spring for a double door, but many manufacturers use two springs for a double door. The painted line on the spring acts as a gauge for the number of turns you put on the spring. To keep the bar from turning while you’re adding tension, attach a locking pliers to the bar on both ends of the spring. Apply lubricant for garage doors to the spring.
A standard double garage door is 7 ft. high by 16 ft. wide. Standard single doors are 7 ft. high by 8 or 9 ft. wide. Because the doors are so large, few home centers and only some garage door stores keep many doors in stock, so expect to order one instead of buying it off the shelf. Garage doors are available in wood, fiberglass and steel. Steel doors, like ours, are light, maintenance-free, affordable, readily available, and have an insulating value as high as R-19.