A plaster cornice or a simple caving are used to finish the edges of a ceiling where it meets the walls. Ready-made gypsum coving is widely available, generally in a fairly limited range of profile sizes and in various lengths. However, you can buy any number of period-style fibrous-plaster cornices, many of which are exact copies of Georgian and Victorian originals.

This sequence describes how to make a coved ceiling, but you can use the same method to fit a cornice.

Start by marking parallel lines along the wall and ceiling, setting them off from the angle at the distance specified in the manufacturer’s instructions, then scratch the plastered surfaces within the lines in order to provide a good key for the adhesive (1).

Measure the wall and cut the coving to fit, using the template to saw the mitre . Remember that when you are cutting mitres for outside corners, the coving must be longer than the wall, and must extend up to the line of the return angle drawn on the ceiling. Cut the coving with a fine-toothed saw, sawing from the face side.

Prepare the special adhesive by mixing the powder with clean water and stirring it to a creamy consistency. The adhesive should remain usable for about 30 minutes, but it is best to aim at making just enough for one length of coving at a time. Use a filling knife to apply the adhesive liberally to the back faces of the coving which will be in contact with the wall and ceiling.

Templates are sometimes provided by the makers which are intended to be used as guides when you are cutting the internal and external mitre joints.

Dry, bare plaster must be dampened just before the coving is put in place. Press it into the angle and level it with the guidelines (2). If a piece of coving is more than about 2m (6ft 6in) long, two people should fit it. Should it tend to sag when in place, support it with a couple of nails driven temporarily into the wall under its bottom edge and remove them when the adhesive has set.

Scrape away any beads of surplus adhesive before it sets and use it to fill the mitre joints as the work progresses. Use your finger to apply the adhesive to internal mitres if you find it easier, but finish off all joints with a filling knife to leave a sharp corner (3).

Wipe along the edges of the coving with a damp brush or sponge to remove any traces of adhesive. When it dries, prime the coving for painting.

Some makers of plaster coving and cornice supply a cardboard template with their product, which enables you to cut mitred corners more easily.

Mark the coving or cornice to length on one edge, bearing in mind whether you are mitring for an external corner or an internal one. Trim and fold the template and place it over the coving in line with the measured mark, then press it down so that it moulds itself to the curve of the material. Use the appropriate edge of the template — for an external or an internal mitre — and, with a soft pencil, draw the cutting line along it on the face and edges of the coving, tracing the template’s edge.

Cut the mitre with a fine-toothed saw, following the marked angle.

If you use plaster coving or cornice right through the house, it is worth making a mitre block as a jig to help you cut the joints accurately.

Cut a baseboard from 18mm (3Ain) plywood or chipboard about 200mm (8in) wide and 450mm (1ft 6in) long. Cut a piece of 100 x 50mm (4 x 2in) planed softwood to the same length for a fence.

Glue the fence to the baseboard flush with one long edge. When the adhesive has set, mark out and make three saw cuts, one at right angles to the face of the fence and two at 45 degrees in opposite directions. Nail a stop batten to the baseboard at a distance from the fence which will allow the coving to fit snugly between them for cutting.

The baseboard of the mitre block represents the ceiling and the fence represents the wall. Lay the coving in the jig with the end to be cut in the right direction for either an external or an internal mitre.

A plaster cornice or a simple caving are used to finish the edges of a ceiling where it meets the walls. Ready-made gypsum coving is widely available, generally in a fairly limited range of profile sizes and in various lengths. However, you can buy any number of period-style fibrous-plaster cornices, many of which are exact copies of Georgian and Victorian originals.

This sequence describes how to make a coved ceiling, but you can use the same method to fit a cornice.

Start by marking parallel lines along the wall and ceiling, setting them off from the angle at the distance specified in the manufacturer’s instructions, then scratch the plastered surfaces within the lines in order to provide a good key for the adhesive (1).

Measure the wall and cut the coving to fit, using the template to saw the mitre . Remember that when you are cutting mitres for outside corners, the coving must be longer than the wall, and must extend up to the line of the return angle drawn on the ceiling. Cut the coving with a fine-toothed saw, sawing from the face side.

Prepare the special adhesive by mixing the powder with clean water and stirring it to a creamy consistency. The adhesive should remain usable for about 30 minutes, but it is best to aim at making just enough for one length of coving at a time. Use a filling knife to apply the adhesive liberally to the back faces of the coving which will be in contact with the wall and ceiling.

Templates are sometimes provided by the makers which are intended to be used as guides when you are cutting the internal and external mitre joints.

Dry, bare plaster must be dampened just before the coving is put in place. Press it into the angle and level it with the guidelines (2). If a piece of coving is more than about 2m (6ft 6in) long, two people should fit it. Should it tend to sag when in place, support it with a couple of nails driven temporarily into the wall under its bottom edge and remove them when the adhesive has set.

Scrape away any beads of surplus adhesive before it sets and use it to fill the mitre joints as the work progresses. Use your finger to apply the adhesive to internal mitres if you find it easier, but finish off all joints with a filling knife to leave a sharp corner (3).

Wipe along the edges of the coving with a damp brush or sponge to remove any traces of adhesive. When it dries, prime the coving for painting.

Some makers of plaster coving and cornice supply a cardboard template with their product, which enables you to cut mitred corners more easily.

Mark the coving or cornice to length on one edge, bearing in mind whether you are mitring for an external corner or an internal one. Trim and fold the template and place it over the coving in line with the measured mark, then press it down so that it moulds itself to the curve of the material. Use the appropriate edge of the template — for an external or an internal mitre — and, with a soft pencil, draw the cutting line along it on the face and edges of the coving, tracing the template’s edge.

Cut the mitre with a fine-toothed saw, following the marked angle.

If you use plaster coving or cornice right through the house, it is worth making a mitre block as a jig to help you cut the joints accurately.

Cut a baseboard from 18mm (3Ain) plywood or chipboard about 200mm (8in) wide and 450mm (1ft 6in) long. Cut a piece of 100 x 50mm (4 x 2in) planed softwood to the same length for a fence.

Glue the fence to the baseboard flush with one long edge. When the adhesive has set, mark out and make three saw cuts, one at right angles to the face of the fence and two at 45 degrees in opposite directions. Nail a stop batten to the baseboard at a distance from the fence which will allow the coving to fit snugly between them for cutting.

The baseboard of the mitre block represents the ceiling and the fence represents the wall. Lay the coving in the jig with the end to be cut in the right direction for either an external or an internal mitre.