How to Cover a Gap on an Exterior Door

Measure the left side of the door frame where the door itself touches it. Measure the right side, then measure the top. Record the measurements.

Set out the strips of tubular gasket and measure out pieces to match the door measurements. Cut through the metal flange and rubber gasket with a hacksaw. Lay the pieces on the ground and fit them together as they will be on the door frame. Trim as needed so the corners will fit tightly together.

Hold the tubular gasket against the door frame on one side, with the rubber facing away from the door. Open the door, move the tubular gasket in place, then close the door to ensure it presses against the tube, making a tight seal.

Open the door again to expose the flange. Mark the flange's screw holes on the door frame with a pencil.

Drill pilot holes into the door frame where you marked. Hold the tubular gasket in place, matching the screw holes to the pilot holes, and drill wood screws into place. Make sure the screw heads are flush with the flange so they don't interfere with the opening and closing of the door.

Measure, mark and drill the other side piece and the top piece, just as you did in steps 3 through 5. Open and close the door a few times to ensure that the door touches the rubber tubing, sealing the door completely.