Crown moulding requires coping so that separate pieces will nest against each other.
When painted, polyurethane moulding looks much like solid wood moulding. Putting it up, however, is much easier. There are no finely fitted cope joints here. The corner is actually made from small blocks that screw in place. The outside edges of the blocks are square, and adjoining moulding, which runs along the walls, butts against the corner blocks. The only cuts you'll have to make are simple square ones that cut the moulding to length.
Unlike wood, polyurethane moulding screws to the wall. Use trim-head screws, which are essentially drywall screws with a smaller head. The holes the screws leave are large enough to need filling. Use glazing putty by rolling some into a ball and packing it into the hold. Run your thumb along the moulding and over the putty to create a patch that follows the shape of the moulding.
While polyurethane won't take a stain, it paints nicely. The advantage of glazing putty is that you can paint over it almost immediately. See the manufacturer's directions on the back of the can for specifics.
Tools and Materials
| Electric drill | Power miter saw or miter box | Tape Measure |
| Pencil | Framing square | Caulking gun |
| Inside and outside corners | Straight mouldings | Latex adhesive caulk |
| Trim-head screws | Glazing putty | |
Step 1. Install the inside and outside corner block square. Apply adhesive latex caulk. Align and screw blocks in place with trim-head screws.
Step 2. Measure the distance between corner blocks. Mark the straight mouldings across the face with a pencil and adjustable combination square. Cut the moulding on a power miter saw or by hand in a miter box.
Step 3. Apply a bead of latex adhesive caulk to the edges of the moulding that will contact the ceiling and wall. Once in place, snug it into position to equally contact the wall and ceiling. Then drive trim-head screws through the moulding and into the wall studs and ceiling joists. Wipe away excess caulk. Fill gaps along the wall and ceiling with latex caulk. Fill the screw holes with glazing putty and paint the moulding.
Step 4. Designer tip for instant formality: Companies that make polyurethane moulding also make rosettes that fit on the ceiling around light fixtures. They install quickly and create a formal-looking room. You'll want to screw the rosette to the ceiling joists, so position it on the ceiling before you install it, and trace around it in pencil. Using a stud finder, locate where the joists cross the pencil line and mark the position lightly. Put construction adhesive on the back of the rosette, put it in place, and drive trim-head screws into the joists.
