How to Install Crown Molding

1. Measure the Room

   Measure the room for total linear wall length. For example, a 165 square-foot room with two 15-foot walls and two 11-foot walls could be completed using one 12-foot section of crown molding for each short wall and two 8-foot sections for each of the long walls.

   Make sure to buy enough crown molding to cover the walls, with some excess for waste. Buying about 25 percent more molding than you need is a good plan. If possible, it is best to cover the walls with long single pieces rather than to join pieces together, as it can be tricky to join pieces together end to end. Most home centers will carry crown molding pieces in 8- and 12-foot lengths, but a specialty lumber yard may carry 16-foot lengths.

2. Cut the Crown Molding

   Measure and mark the crown molding piece for cutting. While you can miter-cut crown molding with a manual miter box and saw, it's better to use a power miter saw, as cuts will be more precise.

   Unlike the technique used to cut construction lumber, where you position the workpiece flat against the miter saw table and fence, crown moldings are cut with pieces positioned at a 45-degree angle, upside-down on the miter saw table. The top edge of the crown molding that will meet the ceiling goes flat against the horizontal saw table, while the bottom edge of the crown molding rests against the vertical back fence of the saw. The piece of crown molding will be positioned at an angle as you cut it.