Crown molding is installed at the wall-ceiling intersection, held at an angle — the spring angle — away from both surfaces. The two most common spring angles are 38° (flat crown) and 45° (standard crown). The spring angle determines how the molding is positioned in the miter saw for cutting — using the wrong angle produces miter cuts that don’t close properly. Inside corners should always be coped — where one piece is back-cut to follow the profile face of the adjacent piece — rather than mitered, which opens up as wood moves seasonally. RainFire Builders copes with all inside crown corners as standard practice.