Repairing Mismatched Mitered Corners

Method 1

• 1

  Clamp the mitered corner together with enough pressure so that the corner comes together and any gap that was present is closed. This works best on trim pieces that have opened up once installed, or on mitered frame corners that have a gap in them.

• 2

  Hammer a finishing nail through one side of the mitered corner into the other side, so that it goes straight through the mitered joint.

• 3

  Hammer a second finishing nail through the other side of the mitered corner into the side you nailed through first. Cross nailing will hold the mitered corner closed once the clamp is released.

Method 2

• 4

  Measure both edges of an unattached mitered corner to find the end that is closest to a perfect 45-degree angle. This method works best for miters that are mismatched, but not yet attached and where a perfect mated corner is required without the use of nails to close gaps, or filler to disguise gaps.

• 5

  Hand-plane the edge of the second-best mitered end, shaving off very small portions at a time until the two mitered ends match perfectly.

• 6

  Hand-sand the mitered edges if a plane is taking off too much lumber. Once you have sanded or planed the miter to a point where it mates well to form a corner, you can connect the lumber into a mitered corner.

Method 3

• 7

  Apply wood filler to the gap of a mismatched mitered corner when the gap is purely an aesthetic problem. If the corner needs to be structurally sound, then use the finishing nail method instead.

• 8

  Wipe off excess wood filler and leave to dry fully.

• 9

  Sand the corner lightly before retouching with wood finish to match the surrounding finish on the mitered corner.