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.

Watch the video above to find out more.

Editorial Contributors
avatar for Joe Truini

Joe Truini

Radio Show Co-Host

Joe Truini is a contractor, author, and the host of “Simple Solutions” on Today’s Homeowner TV and the weekly Today’s Homeowner radio show. He has worked on both large commercial projects and residential remodeling, and has written for national publications such as This Old House and Popular Mechanics. He has also written eight books, including three best-selling shed-building books. Joe lives in Connecticut with his family and enjoys hiking, traveling, and baseball in his spare time.

Learn More