Attaching a cornice involves preparing the pieces, applying a suitable adhesive, and securing them firmly in place. Proper cutting and fitting, including accounting for joint gaps, are crucial steps before the final attachment.
Preparing Your Cornice Pieces
Before you attach your cornice, precise preparation is essential for a professional finish.
Measuring and Cutting
Start by accurately measuring the lengths required for each wall. When cutting, especially for corners like an exterior angle, carefully mark the length and the correct cut orientation using a pencil. Using a miter box or power saw with a fine-tooth blade designed for your cornice material (plaster, polyurethane, polystyrene) will help achieve clean, accurate cuts.
Leaving Joint Gaps
A key step often overlooked is allowing for expansion and contraction, particularly with materials like polystyrene or polyurethane. As highlighted in installation guides, "make sure to always leave a three millimeter joint gap between" cornice pieces. This small gap prevents buckling or cracking as temperatures fluctuate. Don't worry, this gap is filled later in the process.
Methods of Attachment
The primary method for attaching modern cornices is typically with a strong adhesive.
Using Adhesive
- Choose the Right Adhesive: Select an adhesive specifically designed for cornice installation and compatible with your cornice material (e.g., acrylic-based, solvent-free).
- Apply Generously: Apply a continuous bead of adhesive to the back surfaces of the cornice that will meet the wall and the ceiling. Ensure good coverage without applying so much that it squeezes out excessively.
- Position and Press: Carefully position the cornice piece along the marked line on the wall and ceiling. Press it firmly into place along its entire length.
Using Nails or Screws (Support)
For heavier cornices or in situations where extra support is needed while the adhesive dries, temporary or permanent fixings might be used:
- Temporary Nailing: Small panel pins can hold lightweight cornices in place until the adhesive cures. These can often be removed afterward.
- Permanent Fixing: For substantial plaster cornices, screws or nails driven into wall studs or joists might be necessary. These fixings should be counter-sunk and later concealed with filler.
Installation Steps Overview
Here is a general sequence for attaching cornice:
- Measure Walls: Determine the length needed for each section.
- Mark Lines: Lightly draw guide lines on the wall and ceiling where the cornice will sit.
- Cut Cornice: Cut the pieces to length, including necessary angle cuts (like exterior angles) and ensuring a three millimeter joint gap between pieces.
- Apply Adhesive: Run adhesive along the contact surfaces of the cornice back.
- Position Cornice: Align the cornice with the guide lines and press firmly.
- Secure (if needed): Use temporary nails or screws to hold the cornice while the adhesive sets, especially on long runs or corners.
- Fill Gaps and Holes: Once the adhesive is dry, fill the small 3mm joint gaps between pieces, corner gaps, and any nail/screw holes with a suitable filler.
- Sand and Paint: Sand the filled areas smooth and paint the cornice to match your room's decor.
By following these steps, including preparing pieces with the correct cuts and vital joint gaps, you can achieve a secure and professional cornice attachment.
