How to Install Cornices and Coving
This is a building project which is squarely in the DIY category. Removing old coving may result in damage to the walls and ceiling, so be prepared for some plastering, painting and decorating. But unless it’s part of a major property development project, you’re not going to need expert tradesmen or architects.
Whether you’re using polystyrene, paper-covered gypsum, plaster or new ultra-light SuperCove, begin by cutting off 100mm of cove. Use it to mark the edges on the walls and ceilings at regular intervals and join the marks together with a pencil and straight edge. Score the area between the guidelines with a craft knife in criss-crosses to make a key for the adhesive.
Use a mitre box and fine toothed saw to cut the angled edges of the cove or cornice so that the corners can be fashioned accurately (use reverse angles, of course, at either end). Use a filling knife to ‘butter’ the back and top of the cove with adhesive, press it gently into place against the ceiling and the walls along the whole length, taking care to line up with the guidelines. With long stretches, support the cove against gravity temporarily with the occasional galvanised nail (you might need some in the ceiling, too, to prevent it sliding forwards).
Beware: external corners can catch you out unless you’re wary – they need to be cut at the same slope, rather than opposite angles, at each end. Measure the total length from the bottom edge of the cornice or cove, not the top, for these corners. Finally, invite the family to give you a round of applause.