What is a plaster cornice?
A plaster cornice is a decorative moulding of plaster fixed to a plastered ceiling, usually in the angle between wall and ceiling. Its job is partly ornamental and partly practical: it dresses the plain ceiling and hides the joint between wall and ceiling, which is why cornices were sometimes added later. The Dutch term is stuclijst.
Traditionally a plasterer runs the cornice in situ, pulling a running mould with the cut profile along a straight timber rule through wet plaster. Alternatively the profile is cast in plaster and fixed in lengths. A cheaper period alternative was a timber moulding painted to match the ceiling; a true plaster cornice cost more but looked finer. Today there are also ready-made cornices in plaster, polyurethane (PU) or polystyrene that are simply glued in place.
Recognising it
- A hard, cold profile that flows seamlessly into the ceiling.
- A run cornice is continuous, without the regular butt joints of ready-made lengths.
- Old cornices are often clogged with layers of distemper or emulsion, which softens the detail.
Application
- Repair rather than replace. A specialist plasterer can take a template from the surviving profile and run or cast a matching section.
- Remove old paint carefully. Thick paint fills the profile. In a listed building, get the plasterwork assessed first.
- Treat corner cracks as movement. A hairline crack between cornice and wall or ceiling usually comes from shrinkage or movement. A paintable acrylic decorators’ caulk lasts better than filler, which cracks again.
- Fix ready-made cornice properly. Use the adhesive the manufacturer specifies on a clean, sound surface, and mitre the corners.
- Match the material to the room. Plaster suits period interiors; PU is light with a crisp profile; polystyrene is cheap but dents easily.
| Plaster | Suits period interiors |
|---|---|
| Polyurethane (PU) | Light with a crisp profile |
| Polystyrene | Cheap but dents easily |
Common mistake: caulking and painting over a loose old cornice without checking its fixing. A heavy plaster cornice that comes away can fall; have it checked first.
Related terms
- Cove moulding
- Mouldings
- Scagliola
- Gypsum
- Plaster coat
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