How to install a plaster cornice, ceiling centre or dome

How to install a plaster cornice, ceiling centre or dome

Fixing Instructions

Plaster Cornice

It is important to understand when cutting plaster cornice about the projection and depth of the cornice.

1. Projection is the distance between the wall and the outside edge of the cornice on the ceiling wall.

2. Depth is the distance between the ceiling and underside edge of the cornice on the wall.

Measuring, Cutting and Fixing Cornice

1. On the ceiling, draw a chalk line a distance from the wall equal to the top measurement of the cornice. This is the projection.

2. On the wall, mark a chalk line equal to the bottom measurement of the cornice. This is the depth.

3. Measure the lengths of the chalk line around the room to enable the correct lengths needed for the job.

4. Along the chalk line marked on the wall, fix a temporary nail at approximately one metre intervals,to enable the cornice to sit on, whilst the adhesive sets. These nails will be removed once the cornice has properly adhered to the ceiling and wall surfaces.

5. Cut the corner angles and if necessary place the cornice in a large mitre box and cut. When cutting cornice always refer to the projection and depth. Cornice to be cut face up with the projection equaling a 45 degree angle. The cornice should always be cut at their projection and depth measurements.

6. Once the cornice has been cut to the desired lengths and mitre cut, you are now ready to fix.

7. Cornice adhesive can now be applied to the top and bottom edges of the cornice with a 10mm bleed of adhesive along the full length.

8. Place the cornice on top of the nails and forcefully press the top to the ceiling so as to maintain pressure along the edge.

9. See that the next length is placed up to the first and carefully push into place using the adhesive with care to form the joint.

10. When the adhesive starts to grip, proceed to scrape off any excess with a broad knife and brush or sponge off to a clean finish.


Paint, wall paper and other textures should be removed with a stripper or scraper. To apply moulds to materials of uneven surfaces, soften the moulds with dampening to improve their pliability. On very difficult surfaces, hold in place by screwing to the wall.

Cutting Guide

Large Box — Place your cornice against the two back guides (4), position cornice with the base of the box as the ceiling and the back guides as the wall. Hold cornice in this position using wedges placed in the appropriate slots (2). Place the saw blade against the faces of the 45 degree angle guides (1), start to cut carefully and the angle is automatic with the guide.

1. Cutting guides V-shaped blocks with a cutting angle of 45 degree giving the cutting mitre.

2. Movable wedges. They are designed to hold the cornice while cutting. They slide into the appropriate slot to the dimension of the cornice. One can return to these wedges for further cuts on other lengths.

3. Slot positions. The intervals are calculated for different cornice sizes.

4. Back guides. Either side preference blocks angled at 45 degrees as a guide across the base to cut the mitre.

How to install a plaster cornice, ceiling centre or dome

5. Base bottom plate. Thickness 25mm.

Please choose plaster products carefully as no refund or exchange is possible on these made to order items.

All care is taken, however, no responsibility will be accepted for shortages where the site has been unattended on delivery.

Ceiling Centres

1. Trace the circumference of the rose from a central point of your choice. Apply a 10mm bead of adhesive around the perimeter of the centre with a few added dobs towards the middle.

2. To maintain pressure against the ceiling, it may be necessary to make a prop to stand from the floor to the centre until the adhesive has adhered too the ceiling.

3. Alternatively fix screws around the perimeter of the centre for added strength. The screw can be countersunk into the centre and filled in with adhesive.

4. Clean off excess adhesive with a broadknife and brush or sponge to a clean finish.

5. To suspend a light, find the centre of the rose and with a drill, make a hole to allow for electrical cord and fitting of light. If you have made extra holes or marks, patch up with cornice adhesive.


In response to customer demand for specialist architectural plasterwork, Bailey Interiors often supplies prefabricated products such as plaster ceiling domes. The suspension for ceiling domes can be attached to timber, steel or concrete.

To view our broad range of all types of decorative plaster including decorative plaster ceilings, contact us for a sample portfolio brochure of recently completed projects.

Leave a Reply