Step-by-Step Instructions to Install Crown Molding

Line up your first piece of crown molding in a corner, using a ladder. The top of the molding will go against the ceiling, and the side will go against the wall.

Determine where the first length of crown molding will end, and mark that spot on the wall with a pencil; molding lengths are generally 6 to 8 feet long, depending on the manufacturer. If you need to cut the molding to fit a smaller area, mark the location of the cut needed on the molding.

Set your molding upside down in a miter saw, lined up as though the flat table of your saw were the ceiling and the vertical fence of the saw were the wall. Angle the blade 45 degrees to the left if you are installing counterclockwise around the room and to the right if you are installing clockwise.

Line up the mark you made for cutting your molding to length under the 45 degree blade. If the entire piece of molding will be installed, line it up so the saw will cut only through the last ½ to ¾ inch of molding. Even if the molding is meeting another piece in the center of a wall, you must miter the end at a 45 degree angle, because the molding itself is angled against the wall. Making any straight cuts will leave gaps between pieces of molding.

Slowly lower the angled miter blade through the molding to create a 45-degree mitered end. Repeat with both ends of the crown molding piece, so that each end is mitered at 45 degrees, and the piece is the right length.

Set the piece of molding back in place. Attach the molding to the wall and ceiling, using 6D or 8D finishing nails installed every 6 inches.

Miter the end of any adjoining pieces of molding in the opposite direction that you mitered the first so that they fit together perfectly. This applies wherever you join molding, whether in corners or at the center of a wall.

Spread a thin bead of wood glue on both joint edges, push them together, and nail the second piece in place. Wipe excess glue away with a damp sponge. When the glue dries, lightly sand the joint with fine-grit sandpaper to make sure the joint is flush.

Continue mitering, nailing and gluing crown molding pieces until the installation is complete. Use wood filler putty and a putty knife to fill any nail holes. Lightly sand the putty after it's dry, and paint or stain the molding.