Cornice (Coving) Selection and Installation Guide

Choosing the profile by ceiling height, working out quantities and installing in seven steps — mitred corners, filling and painting included.

Two decisions determine the result of a cornice installation: the ratio of profile height to ceiling height, and cutting the corner joints correctly. Too tall a profile crushes a low ceiling, too slim a one disappears; corners that are not mitred at 45° stay visible after painting. This guide covers seven steps from sizing to topcoat.

Required Materials and Tools

• Fine-tooth hand saw or mitre saw • PU-based mounting adhesive (NOT silicone) • Laser level or chalk line • Acrylic filler • 180-220 grit abrasive • System primer of the topcoat brand • Interior topcoat • Damp cloth • Trestle or ladder

Step-by-Step Application

Choose the profile height — Measure the ceiling height and set the profile height accordingly: 90-130 mm at 2.40-2.70 m, 150-200 mm at 2.70-3.00 m, 218 mm and above over three metres. Style comes second: plain or stepped for modern ceilings, patterned for classic interiors.
Calculate quantity and waste — Measure the room perimeter in metres, add about 10% for corner and joint cuts and divide by the 2400-2440 mm bar length for pieces. Increase the allowance in rooms with many corners.
Mark the line — Mark the lower edge of the profile on the wall with a laser or chalk line. If the ceiling is slightly out of level, follow the marked straight line rather than the ceiling, otherwise the run reads as wavy.
Mitre the corners at 45° — Cut internal and external corners at 45° on a mitre saw; the material is too dense for a utility knife. Dry-fit both pieces to confirm the angle closes.
Bond — Apply the PU-based mounting adhesive as an uninterrupted bead to both faces that meet wall and ceiling, and to the joint at butt and corner connections. Silicone-based adhesive is not used. Wipe squeeze-out with a damp cloth before it cures; curing takes about one hour in normal conditions.
Fill and sand the joints — Fill joints and corner connections flush with acrylic filler and sand with 180-220 grit once dry. Skip this and every joint shows as a line after painting.
Prime and topcoat — Lightly mat and clean the whole surface with 180-220 grit (release-agent residue repels paint), apply the system primer homogeneously and then the topcoat. The primer must be the system primer of the topcoat brand; spot priming leaves tonal differences over filled areas.

Profile selection table by ceiling height

The table matches available profile heights to ceiling height. The values are a starting point for a balanced look; where a cornice is combined with other mouldings the profile can be one step slimmer.

Ceiling height	Profile height	Example product	Suitable family
below 2.40 m	45 - 70 mm	P83004 · P81005	Plain / slim patterned
2.40 - 2.70 m	90 - 130 mm	P81601 · P81088 · P81132	Plain · Patterned
2.50 - 2.80 m (modern)	127 mm stepped	P831212 · P831212A	Stepped
2.70 - 3.00 m	150 - 200 mm	P88091 · P81159 · P81166	Plain · Classic patterned
above 3.00 m	218 - 315 mm	P81354 · P81169 · P81170	Wide profile
above 3.50 m / commercial	470 mm	2P81175	Cornice + coving

Plain, stepped or patterned: which suits which room?

Plain profiles are single-faced and crisp, giving an uninterrupted shadow line on modern ceilings. Stepped profiles break light in two or three layers and suit transitional interiors. Patterned (classic motif) profiles turn the cornice into an ornament in its own right and stay legible in tall classic living rooms, entrance halls and commercial spaces. Corner profiles (175 mm) complete the ceiling-to-wall return.

Use in wet rooms and with hidden lighting

Polyurethane is closed-cell and absorbs less than 1% water, so there is no blistering, mould or deformation in bathrooms and kitchens. For concealed lighting, cornice profiles have no LED channel, so the dedicated hidden light profiles are used; both products can share the same ceiling.

The four items that set the price

Section (profile height and width), pattern workmanship, quantity calculated in running metres and about 10% cutting waste. The price covers the product only; shipping and installation are separate and goods are ex-works. Quotations are free and valid for 7 days.

Frequently Asked Questions

How is the profile chosen by ceiling height?

90-130 mm at 2.40-2.70 m, 150-200 mm at 2.70-3.00 m and 218 mm or more above three metres. Below 2.40 m, slim 45-70 mm profiles are preferred.

How are corners joined?

Internal and external corners are mitred at 45° on a saw, dry-fitted to confirm the angle, then bonded with adhesive on the joint and filled.

Which adhesive is used?

A PU-based mounting adhesive; silicone-based adhesive is not suitable. Curing takes about one hour in normal conditions.

How many metres should I order?

Measure the room perimeter in metres, add about 10% for cutting and divide by the 2400-2440 mm bar length for pieces.

Can it be used in bathrooms and kitchens?

Yes. Closed-cell polyurethane absorbs less than 1% water, so it does not blister, mould or deform in wet rooms.

Can it be left unpainted?

The factory primer is white and is a technical base. Indoors a topcoat is needed for appearance and cleanability; the primer must be the system primer of the topcoat brand.