Crown Molding Installation

Compound miter joint

Image by slworking2 via Flickr

Whether your painting or staining the crown molding, it’s best to finish the wood before you install it.
When applying the finish be sure to coat all sides of the crown. This will seal the wood from moisture, preventing the wood from warping and rotting. If you don’t seal the back side, you’ll have a potential for moisture penetration.

Nailing is important for crown molding. Chance’s are there won’t be a solid backer for the crown molding installation. You’ll have to rely on the studs in the wall and joist in the ceiling for your backers. The best way to find the backers (wood behind the drywall), is to take a 3” nail and penetrate the drywall to see if you hit wood. The best way to do this is to drive the nail approximately where you are planning to nail the molding to your wall and ceiling, Staying close enough to the corner so the nail holes won’t show when the crown molding is installed.

Normally the crown molding is nailed in the first 3/8” of the molding, top and bottom, to the ceiling and wall. To see where this is, hold a piece of crown molding up to the corner, exactly where it will be installed. Draw a line on the ceiling and wall against the molding. Measure to each line. Don’t exceed this distance or you will need to lean to finish drywall, prime and paint.

Cut crown molding

Foyer Crown molding and Wall panels

Image via Wikipedia

There are two ways to cut crown molding. A miter joint, made with an electric miter saw or a miter box or a coping saw. Inside corners can be made with both. Outside corners and joints where the total length of the crown molding won’t extend the total length of the corner, must be mitered. Outside corners with a 90 degree angle require a 45 degree angle cut on each piece of crown. Totaling 90 degrees. Lapping joints where the wall is longer than the crown molding, is usually cut a 22.5 a degree angle. One angle is cut at a back 22.5 degree angle. The other is cut at a forward 22.5 degree angle. How do you decide witch is witch? You cut the forward angle where the joint is most visible. Entering a room is where you see most imperfections. You start at the opposite end of the room and work toward the area where people will enter the room. The main thing is you realize the joint is much more visible from one angle verses another.

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