How to Fix Cracks in a Door's Corner

Loosen and remove the screws that hold the door to the hinges. Assign a helper to hold one end of the door, while you hold the other end and lay it flat on a large table or a pair of sawhorses in an open space, so you can work around the door easily.

Remove any paint, varnish or lacquer on the door to help locate the crack, if required, with a paint stripper, scraper or sandpaper. However, skip this step if the corner crack is clearly visible through the finish.

Mark the location of the corner crack on the door with masking tape. Slide the rounded edge of a putty knife inside the crack to remove any filler, debris or caulk.

Screw a small wood-clamping block on either side of the corner crack, spaced 1/2-inch apart. Ensure the blocks are centered along the middle of the crack.

Insert the tip of a small paintbrush in a container of polyurethane glue and apply a small amount inside the corner crack. Work the adhesive into the edges, corners and crevices of the crack to ensure complete coverage.

Position the jaws of a bar clamp around the clamping blocks on the door. Tighten the clamp to bring the two pieces together, using the clamping blocks for leverage. Let the glue dry according to the time specified on its label.

Loosen and remove the clamp from the door when the glue cures. Also unscrew and remove the clamping blocks.

Insert tinted wood putty into the screw holes you made through the door. Ensure the putty matches the shade of the surrounding wood surface so the repaired patch does not stand out. Allow the putty to cure for the time specified on the label’s directions.

Sand the surface of the cured putty with medium-grit sandpaper until smooth. Prime the repaired patch so it blends with the surrounding, and paint if required. Allow the finish on the door to dry completely before you rehang the door.