A door sweep is a strip of flexible material in the base of a overhead garage door that makes contact with the ground to seal out rain and wind. If your garage floor is uneven, it can be hard to obtain a good door-bottom seal. But you can make an effective self-adjusting door sweep from inexpensive preformed slit foam insulation sized for pipes of 3/4-inch diameter. This type of pipe insulation is sold at hardware and home centers.
How to produce
Buy enough of the pipe insulation to match the width of the door. Open the door so the underside is head high. Place the pipe insulation over the bottom of the door so the slit will face down as soon as the door is shut. Expand the slit apart so that you can fasten the insulation to the door with screws. Use enough screws to securely hold the material. Add washers to the screw heads to stop them from tearing during the pipe insulation. If the material tears with usage, it is not hard to replace. In case you have a wooden door, you are able to simply nail down the pipe insulation to the back of the door with 4d box nails so that the insulation presses against the ground once the door closes.