Things You'll Need:
-
Step 1
Measure the dimensions of the room to determine the amount of polystyrene crown molding required. A room that measures 14 feet by 20 feet will require 68 feet of molding. Order or purchase extra to allow for waste or bad cuts.
-
Step 2
Set the molding on a flat surface and apply two coats of primer allowing the recommended drying time between coats. Apply two to three coats of the finish paint and allow to dry between coats. Make sure paint is thoroughly dry before beginning installation.
-
Step 3
Cut the end of the beginning piece of molding at a 45 degree angle. Cut the opposite end straight; this squares the cut edge from the factory.
-
Step 4
Insert construction adhesive into the caulking gun after cutting off the tip of the adhesive tube and puncturing the inner seal. Apply the adhesive to the back of the trimmed crown molding in strips 3 inches long and 6 inches apart.
-
Step 5
Press the crown molding strip into place with the top edge against the ceiling and the mitered end in the corner of the room. If the section of molding wants to slip out of place, secure with painter's tape randomly along the bottom edge.
-
Step 6
Square the end of the next section. Apply the construction adhesive and join the sections with square ends butting together. Continue this process until you reach the next corner of the room.
-
Step 7
Miter the end of the section of crown molding that will be at the corner at 45 degrees. Hold the section with the longer edge of the mitered edge into the corner and mark the end that will meet the installed section. Square cut this end, trimming off a little at a time until the fit is tight and smooth.
-
Step 8
Finished polystyrene crown molding installationCaulk along the edges of the polystyrene molding where the molding meets the wall and the ceiling, smoothing with your finger. Apply a small amount of spackle to any gaps between the square ends and the mitered ends. Allow the spackle to dry and sand lightly. Touch up any areas of the painted surface that may have been nicked during the installation.













