Cornice moulding

A cornice moulding (also called crown moulding) is the profile fitted along the line where wall meets ceiling. Think of it as the ceiling’s counterpart to the skirting board: it covers a joint that tends to crack, softens the transition from wall to ceiling and gives the room a frame. Its roots go back to the cornices of classical architecture. In Turkish it is known as kartonpiyer.

Materials and types

Traditional cornices are cast in plaster and fixed with plaster adhesive on site; they hold fine, deep profiles, so they remain the choice for classic interiors. Polyurethane cornices are lighter, resist knocks and come in ready lengths. Polystyrene products are the cheapest, but detail and surface hardness are lower.

In terms of form there are two broad approaches. Moulded, decorative profiles carry the character of classic and neoclassical rooms. Plain, flat profiles in modern interiors simply create a clean junction line.

Cornices with hidden lighting

A very common use in homes is to fit the cornice slightly away from the wall, or to use a hollow profile, and place an LED strip behind it. Light bounces off the ceiling to give soft, indirect ambient light and makes the ceiling feel higher. To keep the LEDs from showing up as a row of dots, the gap between profile and ceiling and the choice of strip need care.

In a render, a cornice, especially one with hidden lighting, controls how light falls across the ceiling. For that glow to fade naturally, the area light or emissive surface has to be placed correctly and the ceiling material should not be too glossy.