How to mitre outside corner moulding

Written by kevin mcdermott
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An "outside" corner doesn't refer to a corner that's outdoors. It means a corner that juts out into a room—like the outer edge of a chimney wall or cabinet frame—as opposed to an "inside'' corner, as in the corner of a room. (One way to remember: An outside corner is one you could hurt yourself on; an inside corner is where you had to sit when you were bad.) An outside corner is 90 degrees, so trimming around it is a matter of mitring two pieces of moulding at 45 degrees each.

Skill level:

Things you need

  • Tape measure
  • Moulding
  • Mitre saw
  • Trim nailer

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  1. 1

    Measure the wall from the outside corner, going in either direction.

  2. 2

    Transfer the measurement to a piece of moulding, putting a pencil mark on the top of the piece, near the back, where the piece will meet the wall.

  3. 3

    Put the moulding on your mitre saw, setting it in the position it will go on the wall (with the back side of the trim standing against the saw fence). Your pencil mark should be directly under the blade.

  4. 4

    Turn the saw blade 45 degrees outward from the piece of moulding, so the blade is right at the mark toward the back of the trim and pointing out away from the measured span.

  5. 5

    Hold the moulding firmly with one hand. Engage the saw motor and bring the blade down through the wood in one smooth motion. The front face of the moulding should be longer than the back after you make the cut.

  6. 6

    Repeat the steps for piece of moulding that will sit on the opposite direction off the corner, making sure that the blade against points away from the measured span of trim. This will mean that the piece of trim will sit on the opposite side of the blade as before, and the blade will be swivelled to 45 degrees in the opposite direction as before.

  7. 7

    Hold the two pieces of moulding at the corner with their mitre cuts facing each other, to confirm them fit tightly. Secure both pieces there with your trim nailer.

Tips and warnings

  • If the mitres don't fit tightly it means your wall is off square. Re-cut the moulding, adjusting the blade angle of the mitre saw to make the mitre tight.
  • Wear eye protection such as goggles when using a mitre saw and trim nailer.

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