When hanging crown molding a problem that you may experience is that its corner was constructed out of square. This is actually a common problem because the majority of older homes have settled, and newer homes are being thrown together with no care about how square the corners and seams are. In order to prevent your crown molding from having gaps or cracks due to these out-of-square problems, you should avoid using the basic 45 degree corners. Instead, most professional finish carpenters choose to cope each pieces of molding, meaning that each piece of crown molding gets shaped to fit the opposite piece that is already installed in the corner.
This may seem like it is a complicated job that requires a lot of experience and extensive knowledge in mathematical equations, but the truth is that this task can be accomplished by any homeowner that has a little knowledge and with a few basic carpentry tools.
Step 1: Cut the First Corner Piece
Begin by measuring the length of the wall to find out how long of a piece that you need. Transfer this measurement to the crown molding, and make a mark on the highest side of it. When you do this, make sure that you you take exact measurements so the piece of molding is tight from end to end.
Cut the piece of crown molding on a miter saw by holding the flat surface tight against the table. Use finishing nails to secure the molding in place, making sure that you nail into the wall studs so that the molding does not move.
Step 2: Cut the Second Corner Piece
Once again, measure the length that you need, but this time you have to cut the piece at a 45-degree angle. To accomplish this, transfer the measurement from the wall and mark it on the crown molding’s highest point. Place the piece of molding into the saw with the footing against the back fence. Tip the piece upwards until the top bevel is flat against the fence, while making sure that the bottom bevel is flat against the table. If done correctly, there should be a triangular gap on the back of the piece. Hold the crown molding as tightly as you can, and proceed to cut. Whether you are completing an inside or an outside corner, be sure to cut the angle in the correct direction.
Step 3: Cope the Molding
When coping the piece of molding so that it forms to the joint that you are forming, use a basic hand coping saw. Study the piece of wood, starting with each specific angle and wood grain style. You want to do this so that you can judge where you need to trim it with a copying saw. What you want to have when you are done is a back angle along the top edges of the 45 degree cut that is around 30 degrees. Use a speed square to make a mark on each end that is at a 30-degree angle, and make the cuts. Take your time to form the cut to the shapes within the wood.
Since the majority of corners in the houses of today are out-of-square, the best way to hang crown molding that has no cracks or gaps is to use a miter saw for the basic cuts. You can then form it with a hand held coping saw.