>Installing the Crown MoldingBefore you add crown molding, you need to measure the area and draw a chalk line on the wall so that you know where to place the molding. You will need one person to hold the chalk line on one end of the wall while you hold the line at the other end. Make your line even with the bottom of the crown molding on the adjacent wall. Lining the crown molding with the bottom of the chalk line should make the crown molding on all walls even.If there are any spaces between the top of the crown molding and the ceiling, you can use caulk to cover these spaces. If there is space in the corner, you might have to cut the molding to fit the size of the corner. You want to screw the nails into the studs on the wall so that the molding has something to keep it on the wall. A nail of at least two and one half inches or more should be used when you nail the molding to the wall.When you begin placing the molding on the wall, you will need someone to hold one end while you nail the other end to the wall. Find the beginning of the chalk line that you made and place the straight edge of the molding flush against this line. Using a nail gun, shoot through the top of the molding into the top plate of the wall. Repeat this step every 16 inches along the crown molding. After the molding is in place, you can go back to see if there are any loose nails. Work your way around the entire room with the crown molding. You can install one long piece of molding on the wall, or you can use separate pieces to make the job easier. Use a nail to connect the two pieces together. After the molding is installed, you can paint it to match the walls in the room.