Coving, also called cornice in some circles, is a decorative moulding fixed around the top of a room to hide the joint between the wall and the ceiling. While not as frequently fitted in modern homes, adding coving can bring a classical and elegant finish to any room. This guide covers everything you need to know about choosing, cutting, and installing coving yourself.
Understanding Coving Materials and Their Differences
Coving comes in several materials, each with its own strengths. The three main types are plaster, polystyrene, and polyurethane (also called duropolymer) coving. Plaster is the most traditional option and offers an authentic period look, but it is heavy, fragile, and can chip easily during installation. It requires skilled labour, typically two people, and needs two to three coats of paint to finish properly.
Polystyrene coving is the cheapest option, but it is not as durable or versatile. Polyurethane coving, such as the Orac Decor range, has become popular among DIY enthusiasts. It is lightweight, strong, and can be installed by one person in roughly half the time needed for plaster coving. It flexes naturally with the building as it moves with seasonal changes, so cracking is not an issue.
| Feature | Plaster Coving | Polystyrene Coving | Polyurethane Coving |
|---|---|---|---|
| Weight | Very heavy | Very lightweight | Lightweight |
| Strength | Fragile, chips easily | Low durability | Strong, resilient |
| Installation | 2 people, skilled | 1 person, easy | 1 person, quick |
| Paint required | 2-3 coats | 1-2 coats | 1 coat (pre-primed) |
| Flexibility | None, cracks easily | Limited | Flexes with building |
| Cost | Medium to high | Low | Medium |
The most common sizes are 125 mm and 85 mm. The stated size refers to the imaginary line across the coving, not the physical height. Think of it as the hypotenuse of a triangle, with the wall and ceiling forming the other two sides. Polyurethane coving is pre-primed and needs only one coat of paint. For context on how coving relates to other wall finishes, understanding plastering techniques and wall finishes is also useful.
Essential Tools and Materials for Coving Installation
Before you begin, gather all the necessary tools. Having everything ready beforehand makes the job much smoother. Here is what you will need:
- A hand saw with a fine or medium-toothed stiff blade for clean cuts
- A mitre box or mitre block for cutting corner joints, or a mitre saw or Wonder Mitre template
- Coving adhesive, either ready-mixed or powder-based, or silicone adhesive with a sealant gun
- A pencil for marking measurements
- A spirit level or chalk line for drawing guidelines around the room
- A hammer and panel pins to support coving while adhesive sets
- A sponge or cloth and water for cleaning excess adhesive
- A filling knife for spreading adhesive and filling gaps
- A trimming knife (Stanley knife) for scoring painted surfaces
- A paintbrush for blending caulk into joints
If you are unsure about the right saw or adhesive, checking out a mortar coving tool review can help you select the best equipment. Good tools make the cutting process more accurate and reduce frustration. For other finishing work, knowing how different wall finishes such as swirl finish are applied is also helpful for coordinating your decorating plan.
How to Measure, Mark, and Prepare Your Room for Coving
Start by taking a small offcut of coving and holding it flush against the wall and ceiling at various points around the room. Mark along the top and bottom edges to create guide lines. Use a spirit level to ensure the marks are straight, or use a chalk line stretched between two panel pins. These lines will be your reference when sticking the coving in place.
Offer up a full length of coving against the wall before cutting to check it looks right. This is especially important in older rooms where walls may not be perfectly square. Do not force the coving to match imperfections. Fit it straight and fill gaps later. Remove any flaking paint, loose plaster, or wallpaper from between your guide lines. Use a multi-sensor detector to locate pipes or cables and mark their positions below the pencil line.
If fitting coving onto fresh plaster, brush on diluted PVA and let it dry before applying adhesive. This prevents the dry plaster from absorbing moisture too quickly. For painted surfaces, score near your pencil marks with a Stanley knife to give the adhesive something to grip. Understanding how wall materials behave with adhesives helps avoid common installation mistakes.
Cutting Coving: Mitre Blocks, Wonder Mitre, and Mitre Saws
Cutting coving is the most challenging part of the job. The golden rule for beginners is to buy an extra length for practice before cutting your actual pieces. Mitre joints are used at corners. External mitre joints go around protrusions such as chimney breasts, while internal mitre joints are used in room corners.
When measuring, always measure along the edge that sits against the wall. Write “wall” on the back of the coving to avoid confusion. Place the coving upside down in the mitre box, with the wall edge pointing up. The numbered slots correspond to different cuts:
- Slot 1 for right-hand internal mitre
- Slot 2 for left-hand internal mitre
- Slot 3 for left-hand external mitre
- Slot 4 for right-hand external mitre
Start with the longest wall to minimise waste. For walls longer than a single length, join pieces with a butt joint or a mitre join at 45 degrees for a stronger finish. Use a fine-toothed saw for clean cuts. Offer up each piece without adhesive first to check the fit, then sand ends with fine sandpaper. If walls are not square, use an angle finder to determine the corner angle and cut a custom groove in your mitre box.
Alternative tools include a Wonder Mitre, which sits inside the coving and grips it securely, suitable for coving up to 125 mm. A coving mitre saw uses an adjustable blade guide for accurate cuts. For rooms with unusual angles, false ceiling designs for complex corners can provide additional insight.
Fixing Coving with Adhesive and Achieving a Professional Finish
Mix powdered adhesive to a thick paste following the instructions, or use ready-mixed adhesive. Spread it evenly along both long edges of the coving using a filling knife. There is no need to apply adhesive to the centre of the back, as this area does not make contact. Alternatively, use silicone-based adhesive with a sealant gun.
Apply a generous amount so it squeezes out slightly from the edges when pressed into position. Excess can be scraped off and cleaned with a damp cloth. Line up the coving with your guide lines, pressing firmly along the full length. For subsequent pieces, also apply adhesive to the mitre joint surfaces.
Fill any gaps with adhesive using your filling knife. Scrape off excess immediately and wipe clean. If a long length might sag before the adhesive sets, tack small panel pins underneath for temporary support. Fill the holes later with decorators caulk. Always check for pipes and cables with a detector before nailing into walls.
Once dry, apply decorators caulk along the edges where coving meets the wall and ceiling, and over mitre joints. This hides gaps and gives a seamless finish. Then paint the coving in your chosen colour. Understanding common painting defects and how to avoid them helps achieve a flawless result.
Understanding Coving Profiles, Sizes, and the Difference from Cornice
There is often confusion between coving and cornice. Coving fits into the corner between the wall and ceiling. It has a uniform profile, symmetrical when viewed from the side. If coving projects 10 cm across the ceiling, it drops 10 cm down the wall. Coving designs tend to be simple.
Cornice is a broader term for decorative architectural moulding used to add visual interest. It can be added to cupboards, used instead of coving, or installed alongside it. Some cornice profiles hold uplighters for indirect lighting effects.
Coving profiles include simple curves and named patterns such as Egg and Dart, Dentil, Cove, and Rope. Cornice profiles include Swag and Bow, Acanthus Leaf, and Swan Neck. The term “profile” is also used for skirting boards, with common types including Torus and Bullnose. Choosing the right profile depends on the architectural style of your home. For rooms with high ceilings, vaulted ceiling designs often benefit from more ornate profiles, while simpler coving suits modern interiors. Coordinating your coving with indoor wall cladding options creates a cohesive interior design scheme.
Fitting coving is not difficult when you take your time, plan carefully, and practice cutting on scrap pieces first. With the right tools and this step-by-step approach, you can achieve professional-looking results that enhance your home for years to come.