Things You'll Need
Square head bit
Square head deck screws (4 inches long)
Any door can become uneven over time. You may not notice it so much though, unless you have a set of double doors or French doors. Since these doors meet in the middle, the fit and swing has to be perfect or the two doors won't line up properly. Fixing uneven French doors is not hard to do with the proper tools.
Inspect the french doors to determine where they appear to be uneven. Often this is at the top of the door, near the topmost hinge.
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Inspect each hinge and each screw within the hinge. A common problem is that over time, as the doors are opened repeatedly, some of the screw hinges can come loose.
Tighten down any loose screws with a screwdriver. Don't over tighten because it may strip the screw head.
Check to see if any screws from the hinges have pulled out from the wall. This is also very common because the manufacture usually supplies screws that are way too short. You should use screws that are at least 3 1/2 to 4 inches long.
Install square-head, 4-inch-long deck screws with the cordless drill. Get a helper to hold the door in place while you do this. Use screws slightly oversized, and you won't have to make any repairs to the pulled-out screw hole. Square head screws don't strip out as easily as Phillips head screws do.
You may find that your door is warped due to moisture damage. Remove the door at the hinge pins with a hole punch and hammer, and order a replacement door. You don't have to replace the entire French door set and frame. Repairing a warped door can cost more than replacing it.
Always wear proper protection for home improvement projects: eye protection, gloves and dust mask.