How to Fit Plaster Cornice and Coving: A Step-by-Step Guide

The short answer: measure the room, mark level guide lines on the wall and ceiling, cut the corners with a mitre box and a fine-toothed saw, spread coving adhesive on the two back edges, and press each length into place, resting it on temporary nails while the adhesive sets. Then fill the joints, sand, prime and paint. Each stage is below.

Before you start

Choose the right size

Go by ceiling height first. Most of our cornice listings state the room height the profile is designed for, for example up to 8ft 6in, 9ft or 10ft. Smaller rooms suit a smaller profile. Every cornice profile in our range has a Sample option, so you can hold one up before you order full lengths. Not sure whether you want cornice or coving? Read cornice vs coving.

Work out how much you need

Measure the perimeter of the room with a tape measure, and allow for any awkward angles. Most of our profiles come in 3m (10ft) lengths and a few are a little shorter, so check the listing. Order around 10% more than the room size to allow for mitres and wastage.

Tools and materials

• Tape measure, spirit level and pencil, or a chalk line
• Mitre box or mitre block and a fine-toothed saw
• Trowel or scraper for the adhesive
• Nails or panel pins for temporary support, and a hammer
• Damp sponge or cloth, and dust sheets
• Wet and dry abrasive paper, 120 or 180 grade
• Coving adhesive

Which adhesive, and how much

Use a coving adhesive. We stock Gyproc Coving Adhesive (5kg and 12.5kg) and Herculite Fibrefix Adhesive (5kg and 25kg) in our fixing and filling adhesives range. As a guide, 1kg fixes about 3m (10ft) of cornice, and both set in around 45 minutes. Both can also be used to fill joints and mitres.

Fitting our lightweight polymer cornice instead? Use the ORAC adhesives in our lightweight adhesives and fillers.

How to fit plaster cornice, step by step

1. Check the surfaces. The wall and ceiling need to be sound, clean and even. Wipe away dust with a damp cloth so the adhesive grips, and check there are no cables or pipes behind the wall where you'll be fixing.
2. Mark your guide lines. Mark where the top and bottom edges of the cornice will sit, all round the room, using a spirit level and pencil or a chalk line. Keep the lines straight and level.
3. Put in support nails. Tap nails part way into the wall along the lower guide line, ready to take the weight of the cornice. Offer a length up to check it sits right.
4. Cut the corners. Internal and external corners need mitres. Cut them with a mitre box or block and a fine-toothed saw, and line each piece up with the last so the joints meet cleanly.
5. Apply the adhesive. Spread adhesive with a trowel or scraper along the two back edges of the cornice, the ones that touch the wall and the ceiling.
6. Fix it in place. Lift the length onto the support nails and press it into place so the whole length makes contact with the wall and ceiling. Tap nails into the ceiling along the top edge to hold it while it sets. On uneven surfaces you may need to reinforce the hold with drywall screws through the cornice.
7. Clean off and fill. Scrape off excess adhesive and wipe it with a damp sponge before it sets. Use the surplus adhesive to fill any gaps at the corners and joints.
8. Finish. Once the adhesive has set, take out the temporary nails. Go round the room, fill any remaining gaps, then sand the joints and corners with 120 or 180 grade wet and dry paper.

Painting plaster cornice

Make sure the plaster and filler are fully dry and clean. Seal with a primer or a mist coat (watered-down paint), then apply at least two coats of matt emulsion, letting each coat dry before the next. A fine brush helps on detailed profiles. Painting it to match the ceiling ties the room together, or a contrasting colour makes it a feature.

Looking after it

Dust with a soft cloth, or wipe with a damp cloth and a mild detergent. Avoid abrasive cleaners. Fill any small cracks promptly and touch up the paint.

Can UK Plaster fit it for me?

We mainly fit cornice for insurance companies, because the labour costs can be too high for many individuals, but arrangements for direct customers can be made. For larger or more ornate cornice, we recommend a skilled fibrous plasterer. We're always happy to advise on installation: call 01204 693900, Monday to Friday, 9am to 5pm.

Matching an existing cornice

If you're repairing or extending a cornice that's already there, start by tracing the profile. If it isn't in our range, our cornice matching service can reproduce it.

Fitting a ceiling rose as well? See how to install a plaster ceiling rose. Or browse our plaster cornice and coving range.