Many common door problems are caused by poor installation or misalignment of the door and frame over time. Excessive gaps between the door and frame can prevent the door from staying closed properly, and can even pose a security risk by keeping the lock from operating as intended. By fixing these gaps, homeowners can improve the door's operation and allow locks and latches to perform more effectively. Minor gaps can be fixed fairly easily, while larger gaps may require more complex repair jobs.
Fixing small gaps
Loosen the hinges using a screwdriver or drill. There is no need to remove them completely.
Slide wooden or cardboard shims behind each hinge. Fit these shims between the door jamb and the back of the hinge, then re-tighten the hinges. The shims will bring the door closer to the lock jamb on the frame, and may eliminate minor gaps.
Remove the strike plate from along the lock jamb. Place wooden or cardboard shims behind the plate then screw it back in place. This will position the strike closer to the lock, which can help the lock operate properly in spite of a gap between the door and frame.
Seal the gap with weatherstripping. If the lock is working properly and the door stays closed, consider adding stick-on weatherstripping to seal small gaps. This can eliminate drafts and improve energy efficiency on doors with no operational problems.
Fixing large gaps
Fix large gaps by adding a wood filler section along the edge of the door. Close the door and measure the gap between the door and the jamb. A 1.5 mm (1/16 inch) gap is typically required to allow the door to swing freely. Determine how large the gap is, then subtract 1.5 mm (1/16 inch). This is the distance by which you will need to extend the edge of the door.
Remove the door from the opening. Use a hammer and centre punch to remove the hinge pins, then lift the door out of the frame. Set it on a pair of sawhorses as you work.
Cut the edge of the door (the opposite of the hinge edge) with a circular saw to expose fresh wood. Set your cut to 3 mm (1/8 inch). The fresh wood will be easier to bind to the new filler edge.
Use the dimensions you calculated in Step 1, plus the 3 mm (1/8 inch) you cut in Step 3 to cut a new length of lumber the same length and thickness as the door.
Apply wood glue to the edge of the filler piece and stick it to the edge of the door. Clamp the two pieces together, then drill two long decking nails into the edge of the door to join the sections together.
Allow the glue to dry overnight, then sand the joints where the filler meets the door. Clean away sanding dust and repaint the door to restore its appearance. Rehang the door by tapping the hinge pins back into place.