Cut Your Chair Rail
If you are installing your chair rail on a wall that forms a corner with the adjacent wall, you will need to cut your chair rail at a 45-degree bevel cut. This will ensure that your two pieces of chair rail fit together seamlessly when they meet in the corner of your wall. Cut your 45-degree bevel cut on your miter saw first, before you install it.
To cut a 45-degree bevel cut:
1. Measure your chair rail from the back, marking the width with a pencil.
2. With your miter saw at 90 degrees, cut your chair rail on your mark.