Proper maintenance of your bottom weatherstripping helps to keep water, dirt, leaves, rodents and insects on the other side of your garage door. The weatherstrip, also called an astragal, also works to insulate your garage. If you are dealing with an older door, the seal will probably need to be replaced. Most garage doors have a channel-type system, making it easier for you to slide the weatherstrip into grooves during installation.
Disengage the garage door from the automatic opener with the door in the closed position by pulling down on the emergency cord. You will feel the latch release. Now the door can be lowered and raised manually.
Raise the garage door until the bottom is just below the track junction. This is the place where the track is connected to the curved portion of the track. Secure the door by clamping the roller and track together with a C clamp.
Check both ends to see if the grooves have been slightly closed together at the ends from the previous installation. If so, pry the ends open with a flat tip screwdriver. Then slide the weatherstripping out of the grooves.
Clean the channels or grooves with a spray detergent or lubricant to ease installation of the new weatherstrip.
Slide in the new weatherstrip by forming the strip into a U-shape and feeding the strip into both channels at the same time. You may need to insert one side first and then the other. Continue to gradually feed the strip to the far end of the door until 3 inches protrudes.
Fold the 3 inches of excess back inside the U formation to meet evenly with the door. On the original side where you fed in the weatherstripping, trim the material to 3 inches with the box cutter and fold it as well inside the U formation. Leaving approximately 3 inches this allows for shrinkage. Crimp both ends of each channel slightly with your pliers to prevent sliding.
Remove the C clamp. Draw down the door to the closed position. Reconnect the door to the motor by pulling the emergency cord toward the motor and test the garage door opener.