How to Fit a Ceiling Cornice: The Complete Step-by-Step Guide

Dreaming of transforming the look of your home without major building work? Fitting a ceiling cornice is an elegant, accessible solution that can give any room a whole new character. This guide walks you through the installation step by step, for a truly professional finish.

Tools and Materials You Will Need

Before you start, make sure you have all the necessary tools within easy reach:

Tools:

• Tape measure and pencil
• Spirit level or laser level
• Mitre box or powered mitre saw
• Fine-toothed hand saw
• Cartridge gun
• Filling knife and a stable stepladder
• Sandpaper, 120-180 grit

Consumables:

• Cornices (room perimeter + 10% for wastage)
• Mounting adhesive made specifically for mouldings
• White acrylic caulk
• Panel pins (optional)

Our tip: go for polyurethane cornices, where the detail is more sharply defined and the finish distinctly more premium.

Step 1: Preparing the Surfaces

Careful preparation is the key to a successful installation. Start by thoroughly cleaning the wall-to-ceiling junction. Strip off any loose wallpaper, flaking paint or dust.

Key points:

• Surfaces must be clean, dry and slightly porous
• On gloss paint, sand lightly to improve adhesion
• Fill any holes and cracks with filler

Step 2: Marking Out the Guideline

Hold a test length of cornice against the wall-to-ceiling junction and pencil in its outline at several points around the room. Join these marks up with a level or a chalk line to obtain a perfectly horizontal guideline.

This reference line will guide you throughout the installation and guarantee a flawless result.

Step 3: Mastering the 45° Mitre Cuts

This is the most technical stage of the job. The quality of your cuts will determine how the finished result looks.

For internal corners (the most common):

• Set the cornice in the mitre box, ceiling face against the back
• For the left-hand length: cut at 45° towards the right
• For the right-hand length: cut at 45° towards the left

For external corners:

• Reverse the logic: the left-hand length is cut towards the left, the right-hand length towards the right

Pro tip: always dry-fit the pieces before you reach for the adhesive. Fine-tune with sandpaper if needed.

Step 4: Fitting the Cornice

Start with the corners:

1. Apply a generous zigzag bead of adhesive to both contact faces (wall side and ceiling side)
2. Position the cornice, following your marks
3. Press firmly and evenly for 30 seconds
4. Hold heavy lengths in place with temporary panel pins

Then fit the straight runs:

1. Once the corners are in, fill the gaps with lengths cut at 90°
2. Apply adhesive to the contact faces AND to the mating edges of the joints
3. Wipe away any squeezed-out adhesive straight away with a damp sponge

Step 5: A Professional Finish

Leave the adhesive to dry for 12 to 24 hours before finishing:

1. Remove the temporary holding pins
2. Fill the nail holes and joints with white acrylic caulk
3. Smooth the joints with a wetted finger
4. Once dry, sand back any imperfections lightly
5. Dust off before painting, if you intend to paint

Expert Advice

Factor	Recommendation
Temperature	Work between 10°C and 30°C
Uneven walls	Use a slow-setting adhesive and close the gaps with caulk
Choice of material	Polystyrene for beginners, polyurethane for premium results
Painting	Wait 24-48 h and use an acrylic paint, with a primer if necessary

Frequently Asked Questions

Can cornices be painted?
Yes, most cornices take acrylic paint once the adhesive and the caulk have cured completely (24-48 h). A primer may be needed.

How do you repair a broken cornice?
Polyurethane lengths can be repaired with a specialist adhesive and some filler. Where the damage is more serious, replacing the whole section is generally the better option.

How much cornice should I order?
Measure the total perimeter of the room and add 10% for cuts and the odd mistake. Standard lengths are 2 metres.

Browse our cornice collection and enjoy free delivery on orders over 150€. Our team of experts is on hand to advise you.