Simple Solutions

How to Cut an Out of Square Miter Joint

By: Joe Truini

A 45° miter joint is the perfect means for joining two pieces of molding in a 90° corner (such as case molding around a window). Unfortunately not all such corners are exactly 90 degrees, so the miter joint has to be adapted to fit tightly. Here’s how to go about it:

  1. Nail the top piece of molding in place with a 45° angle cut.
  2. Line up the side molding so it’s even with the frame and overlays the top molding.
  3. Mark the inside and outside points on the side molding where it intersects the top miter joint.
  4. Connect the two points with a straight line and make the cut along that line.
  5. The result should be a tight fitting miter that matches the existing corner.



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How to Cut an Out of Square Miter Joint