French doors add style to a room and allow for ease of movement, especially when moving furniture or other large objects in and out. Like single doors, French doors are prone to sticking along the door jambs or to each other if not installed properly. Also, wood expands over time, so even French doors that were installed properly can still fail to close. Fortunately, fixing French doors is a relatively simple do-it-yourself project that doesn't require professional help.
Open and close the doors individually. Watch for the areas where the doors sticks, particularly around the top and bottom of each door. Open and close the doors together to check for sticking along the center where the two doors meet. Where the doors stick will determine how you fix the problem.
Tighten the existing screws into the hinges. Check the doors to see whether the catching persists. If there is rubbing along the top edge or center where the doors meet, remove the current screws in the top hinge only and replace with screws that are 2 1/2 inches in length. The longer screws will pull the door down and toward the door jamb, helping to relieve pressure along the top and center of the door.
Take out the screws in the bottom or middle hinge, replace with longer screws and tighten if the door is rubbing along the floor.
Smooth away any spots that stick with a sanding block. This can be done while the door is in place if you have access to the necessary spots. If not, remove the door from its hinges and lay it flat on the floor to sand. Before doing so, mark the spot with a pencil on either end where the door needs to be sanded. Replace the door.
Remove strips of wood using a hand planer if the sticking points are too large to be sanded away and are not fixed by swapping out the screws. Shave off thin bits of wood at a time, as more can always be removed later; you do not want to remove so much that gaps are left around the door jamb. A hand planer can be used on the door while it is still hanging, or the door can be removed for ease of access. Put the door back into the hinges and test to see whether additional strips of wood need to be shaved away. Sand the sections where the planer was used.