How to Install Polystyrene Crown Molding

Crown molding is a decorative way to finish the trim in a room and provides a smooth transition from the walls to the ceilings in a room. Crown molding has been used in all types of architecture for centuries and was once so expensive that it was only used in churches and the homes of the very wealthy. Crown molding is still expensive, but there is an alternative polystyrene product widely available that allows the average homeowner to incorporate this elegant look into the home. It is easily installed and requires no special skills to cut and fit.

Things You'll Need

• Tape measure
• Primer
• Paint
• Paint brushes
• Miter saw
• Pencil
• Construction adhesive
• Caulking gun
• Ladder
• Painter's tape
• Painter's caulk
• Spackle
• Sandpaper

Instructions

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.

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.

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.

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.

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.

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.

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.

8. 

   Caulk 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.

Tips & Warnings

• Polystyrene crown molding can be primed and painted after installing, but the job goes faster if primed and painted before installing.

• Handle polystyrene crown molding gently. It can easily nick.

References

• Video instructions
• Source for product