If you stand back from your garage door while in your garage and look at the bottom, you may notice light from outside. If you see this light, you have a faulty seal between the garage door and the floor. This gap allows cold air to flow quickly into your garage. Air infiltration will significantly increase the heating bill for your garage and also will contribute to uncomfortable drafts. Seal these gaps when they appear to keep the heat where you want it--in the garage.
Open the garage door fully. This gives you access to the bottom edge of the door.
Insert your pry bar under each nail that holds the seal down to the bottom of the garage door. Lift up on the pry bar to remove each nail. Remove and discard the old seal once all the nails are removed.
Nail one end of the new seal to the bottom of the garage door. Pull it tight and nail the other end to the bottom of the garage door.
Go to the centre of the garage door and finish nailing the new seal from the centre outward to the edge of the door.
Open the ends of the channel on the bottom of the garage door with a regular screwdriver.
Pull out the old rubber seal, called astragal. Spray silicone spray over the entire channel.
Slide in the new rubber seal and close the channels with your regular screwdriver.
If your concrete floor is uneven, you can seal any remaining gap by purchasing a length of 3/4-inch foam pipe insulation and screwing or nailing it to the back of your garage door.