Mitering Outside Crown Molding Corners

Crown molding can increase the classic look of your home, but to install it, you will need to know how to cut outside crown molding corners with a miter saw. As simple as it may seem to make these corners, it takes skill that a novice carpenter is not likely to have. To acquire this expertise, you will need practice and the right tools. If possible, practice the mitering on pieces of crown molding that have been discarded. To avoid higher molding costs, be sure you not only learn how to cut these outside corners, but also learn how to cut them with consistent precision.

Step 1 – Measuring for Your Molding

Measuring your walls where you plan to install your molding is a key step in making precise outside corner cuts. These corners must fit together tightly. To be sure they do, measure carefully the wall surface and the distance between both outside corners. Your measurements must include even the smallest detail with no rounding of inches or centimeters. If there is a possibility of error in measuring, it will be better to cut a trifle too long than a trifle too short. You can always trim off any excess.

Step 2 – Selecting Molding for Your Cut

In choosing lengths of crown molding, find a length of molding that is close in length to the piece you'll be cutting. It is best to choose one that is at least 4 or 5 inches longer than your finished piece will be.

Step 3 – Cutting Your Molding

To cut your molding accurately, you must be careful about how it is placed on your miter saw. First, set your saw for a 90 degree cut. When you are ready to cut, always place the outside (finished) surface of your molding against the back surface of your miter box. This means that when the molding is in place on your miter box, you should be looking at the surface that will be touching the wall. Try to envision the rear surface of your miter box as the wall on which the molding will be attached. In this scenario, the miter box bottom will represent the ceiling above the molding. When cutting, be sure you cut completely through the molding. Even a tiny edge left uncut on the molding end will prevent corners from fitting tightly together. 

Step 4 – Attaching Your Molding to the Wall

To attach your molding to the wall, hold it in place. Tack one end by driving a small finish nail through the molding and into the wall without driving the nail all the way into the molding. Tack the middle and far end of your molding the same way. When you're sure the molding is accurately in place, finish driving the tack nails into the molding using your nail set. Then, drive in other nails about 8 inches apart.

Step 5 – Finishing

Use wood filler or putty to fill nail holes or cracks in the molding. Finish by sanding, applying primer and adding paint or varnish.