Making a flap for a dog door is a simple project that almost anyone can do, requiring only a few simple household tools and a couple of floor mats. This type of dog door is a sturdy flap that will allow wanted animals in, while keeping some unwanted animals out. The hefty weight of the floor mats will also help keep hot and cool air from escaping or entering the house through your door flap.
Measure the dimensions of the old dog door flap. If there is no flap, measure the dimensions of the dog door frame. Shave off about 0.5 cm (¼ inch) from this measurement so the flap can swing easily through the door in both directions. Make sure the mats do not have spikes for gripping carpet. The mats should be completely smooth on the back side.
Cut the mats to the necessary dimensions. Most dog door flaps are a rectangular shape with rounded corners. Draw the outline of the flap on the mat with a pen or marker. Cut the shape out using heavy duty scissors. Repeat for the other flap. Make sure each flap is exactly the same size.
Glue the back sides of the two mats together. Allow the glue to dry for at least one hour before hanging the flap from the dog door.
Measure the top of the rubber flap. Cut one aluminium strip to equal this measurement. If your door had an original flap, there may already be a removable piece that is intended to hold the flap in place. If this is the case, simply unscrew the screws holding it onto the door and remove it from the doorway. If there is no strip to hold the flap in place, cut a piece of aluminium that equals the length of the dog door flap.
Drill holes into the metal strip and mats 5 cm to 7.5 cm (2 to 3 inches) apart. If you are using the original flap-holding strip, drill holes in the mat to match the holes already present on the flap strip.
Slip a wood screw through the pre-drilled holes in the metal strip and door flap. Make sure to align the holes in the metal strip and flap so that the metal strip lays across the flap with no overhanging edges. Hold the flap against the door and mark the placement of the screws with a pencil. Remove the screws from the flap. Starting with one screw at a time, slip the screw back through the metal and door flap and screw it into the marked place on the door using a power screwdriver. Make sure the screws are very tight. If they're loose, the flap may fall away from the dog door. Continue to screw the remaining screws into the door using the same method.