GUIDE: Installing Plaster Moldings

Installation Instructions for Plaster Crown Moldings

NOTE: Attach the crown moldings to primed walls before painting the moldings themselves.

Installing our plaster crown moldings is straightforward. The key is to be meticulous and follow these installation instructions. We also recommend watching our instructional video which demonstrates step by step how to install our plaster moldings. Whether the moldings need to be screwed or not depends on their weight. A good rule of thumb is to always screw if in doubt.

1. Check the height of the selected crown molding.
2. Measure and draw a horizontal line on the wall (the installation line), for example, with a chalk line, to indicate how far down the molding will be placed. Make sure to check which part of the molding should be against the wall and which part should be against the ceiling.
3. Attach two support blocks along the installation line to help hold the molding in place. If the molding is of a lighter model, nails may suffice.
4. Measure on the crown molding where the corner should be cut.
5. Place the molding in a miter box and cut it at a 45º angle with a wood saw. Start from the edge of the molding and finish at the mark. Pre-drill two holes in the crown molding if it is heavy.
6. To glue the molding in place, use SEMIN CE 78 plaster filler. The consistency of the filler (adhesive) should be thick and pliable. Apply the filler to the contact surfaces that will adhere to the ceiling and wall. 
7. Press the molding firmly against the wall and ceiling so that the filler penetrates between the wall, ceiling, and molding. If the molding is heavy, screw in screws into the pre-drilled holes and then remove the support blocks.
8. Collect any excess filler with a putty knife and fill in the screw holes and any gaps in the filler.
9. Cut the other corner molding with the same measurements and procedure as above.
10. Brush off dust from the ends of the crown moldings with a brush and water.
11. Glue all edges (contact surfaces) of the other corner piece and attach it using the same method as the first corner piece. Ensure the moldings are at the same height. Be meticulous when joining the moldings and fill the seam and screw holes with filler.
12. Then wipe away any excess filler with a sponge dampened with water. Let the plaster filler dry.
13. After drying, sand first with 100-grit sandpaper and then with 150-grit sandpaper.
14. Prime (apply a base coat to) the entire crown molding.
15. Finally, paint the molding by hand with a brush or with spray paint.