Plaster cornice is the moulded plasterboard trim that fills the corner where your walls meet the ceiling, hiding the joint and adding a finished edge. Most Australian homes use a coved profile in plaster, and sizes and prices depend on the profile, the length of the room and how much finishing the walls need (indicative — get itemised quotes).
This guide covers cornice styles, the common cove sizes, Gyprock cornice profiles, how to install cornice, what it costs and how to paint it. We also link out to related plaster, paint and moulding guides for each step.
Key points
- Plaster cornice comes in cove, square set and decorative profiles, and the cove is the standard choice for most Sydney homes.
- Common cove sizes include 55 mm, 70 mm, 75 mm and 90 mm, and bigger rooms with higher ceilings suit the larger profiles.
- Installing cornice is a skilled job because the mitres, corners and joint finishing decide how the room looks.
- Old plaster and textured ceilings can contain asbestos, so never sand, drill or scrape them before they are tested.
What is plaster cornice?
Plaster cornice is a pre-formed plasterboard trim that is fixed to the wall and ceiling with adhesive and finished with a setting compound.
| Term | What it means | Why it matters |
|---|---|---|
| Cornice cove | Curved, concave profile that sweeps from wall to ceiling | The most common style; the curve softens the corner and hides small gaps |
| Coved cornice | Another name for the same cove style | Suppliers use both terms, so searching either finds the same range |
| Cornice plaster | The plaster material or adhesive used to bond and finish the trim | The wrong compound cracks or lets go, so use what the cornice maker specifies |
| Gyprock cornice | Cornice made by Gyprock, one of the major plasterboard brands | Profiles and sizes vary by range, so check the current catalogue |
| Square set | A flush, shadow-free corner finish with no trim | A modern alternative with no cornice but harder to finish perfectly |
| Mitre | The angled cut where two lengths meet at a corner | Tight mitres are the difference between a neat room and obvious joins |
- Typical material: gypsum plaster core with a paper face, matching standard plasterboard.
- Typical length: supplied in long lengths for rooms, so check your supplier for current sizes.
- Common use: living rooms, bedrooms, hallways and renovations that need a finished corner.
Cornice styles and plaster cornice profiles
Choose the profile by ceiling height, room size and period of the home. This table compares the main cornice styles.
| Style | Best for | Strength / look | Price band |
|---|---|---|---|
| 55 mm cove cornice | Small rooms, bathrooms and low ceilings | Subtle, unobtrusive curve | $ (indicative — get itemised quotes) |
| 70 mm cove cornice | Standard bedrooms and hallways | Balanced, widely stocked profile | $ (indicative — get itemised quotes) |
| 75 mm cove cornice | Living rooms and open-plan areas | Slightly bolder cove for larger spaces | $$ (indicative — get itemised quotes) |
| 90 mm cove cornice | High ceilings and heritage-style rooms | Strong, formal presence in big rooms | $$ (indicative — get itemised quotes) |
| Decorative or ornate cornice | Period homes and feature rooms | Detailed profile with shadow lines | $$$ (indicative — get itemised quotes) |
| Shadowline | Modern minimal interiors | Recessed gap instead of a coved trim | $$ (indicative — get itemised quotes) |
Choose a shadowline for a modern look
If you prefer a crisp, recessed detail, read our P50 shadowline guide before you choose a cornice.
Match other trims in the room
Skirting and architraves should balance the cornice, so see our mouldings, architraves and skirting guide for pairing advice.
Gyprock cornice profiles and sizes
Gyprock cornice profiles are the most widely requested in Sydney. Always check the current Gyprock catalogue or your supplier for exact dimensions, because ranges change.
- Cove range: you will find small-to-large cove sizes in plain profiles, but confirm which sizes are in the current range before you plan the job.
- Larger coves: larger cove cornice dimensions, such as the 75 mm and 90 mm sizes, suit higher ceilings when the supplier lists them.
- Cornice 90mm: a popular choice for living rooms with generous ceiling heights because the bigger curve looks proportioned.
- Square-set options: some systems offer flush or shadow details instead of a cove, which suits modern builds.
- Moisture-resistant boards: for bathrooms and laundries, ask your supplier which board and cornice combination is suitable for wet areas.
- Compare brands: other manufacturers offer similar sizes, so always confirm the exact profile before ordering extra lengths.
If you are choosing a board brand, read our Gyprock vs plasterboard guide and our plasterboard sizes and thickness guide.
Plaster cornice cost
Plaster cornice costs vary with profile, room size, ceiling height and the finishing standard you want.
| Item | What drives the price | Typical range |
|---|---|---|
| Cornice supply only | Profile, size and length | Low cost per lineal metre (indicative — get itemised quotes) |
| Installed standard cove cornice | Room count, corners and ceiling height | Mid range per lineal metre (indicative — get itemised quotes) |
| Large or decorative cornice | Profile detail, weight and extra labour | Upper range per lineal metre (indicative — get itemised quotes) |
| Removal of old cornice | Fixing method, plaster condition and testing | Adds to the quote (indicative — get itemised quotes) |
| Ceiling and wall repairs | Cracks, water damage and patching | Varies widely (indicative — get itemised quotes) |
| Painting after installation | Number of coats and ceiling height | Quoted per room (indicative — get itemised quotes) |
- Room shape: more internal and external corners mean more mitres and more labour per metre.
- Access: high ceilings, stairwells and cathedral roofs need scaffold or a platform and add cost.
- Bundled work: having the plasterer and painter work in sequence reduces patching and rework.
Plaster cornice pros and cons
| Pros | Cons |
|---|---|
| Hides the wall-to-ceiling joint and small movement cracks | Needs skilled mitring and finishing for a neat result |
| Wide choice of sizes and styles from standard to ornate | Bigger profiles are heavy and harder to lift into place |
| Paints easily with the walls and ceiling | Shows cracks if the room moves and the joints are not flexible |
| Adds a finished, period or classic character | Dust and mess during installation and finishing |
| Works with most interior wall and ceiling types | Not suited to wet areas unless the right products are used |
How to choose plaster cornice
- Measure ceiling height and pick a profile that suits it, since bigger coves overwhelm a low room and tiny ones vanish in a tall room.
- Match the home’s style by choosing plain cove for modern homes and ornate profiles for period houses.
- Check the wall and ceiling condition, because loose or damp plaster will not hold a heavy cornice.
- Compare brands and ranges, noting that Gyprock cornice profiles and other makers may differ in size.
- Plan your finish: decide on sheen and colour before you buy so cornice, ceiling and walls work together.
- Ask for a sample length and hold it in the room before ordering the full quantity.
How to install cornice and installing plaster cornice
Installing plaster cornice is detailed work, and most homeowners get a better result by hiring a licensed plasterer. If you do tackle a small room yourself, follow these steps.
- Confirm the surfaces are safe: if your ceiling or cornice is old, have it tested for asbestos before you drill, cut or sand it.
- Mark the wall and ceiling lines with a chalk line so the cornice sits straight along the full run.
- Cut the mitres for internal and external corners and dry-fit each piece before you use adhesive.
- Mix cornice cement as the label directs, then apply it along both back edges of the cornice.
- Press the cornice into place, pin it temporarily and wipe off squeezed-out adhesive with a damp sponge.
- Fill and sand the joints with the correct setting compound, wearing a dust mask, eye protection and gloves.
- Prime and paint once everything is fully dry, using the products and recoat times shown on the label.
- Working at height: use a stable platform, not a wobbly ladder, and never overreach with a heavy length of cornice.
- Dust control: sealed rooms with plastic sheeting and a vacuum sander reduce the dust spread through the house.
Painting plaster cornice and choosing roller covers
Paint finish is where cornice either looks crisp or patchy, so match the products to the surface.
- Prime new cornice: use a suitable sealer or undercoat so the paint does not soak in unevenly over the joints.
- Cut in first: use a quality angled brush along the cornice edges, then roll the ceiling while the edge is still wet.
- Roller covers: choose a short-nap cover for smooth ceilings and a longer nap for textured finishes, and replace worn covers before they shed fibres.
- Colour choice: white-on-white is classic, while painting the cornice a wall colour softens the corner in dark rooms.
- Covercrete colours: if you plan a coloured or tinted finish, check the supplier’s current colour card and test a sample before committing.
- Calculate quantities: use our paint calculator guide to work out how much paint you need for the ceiling, walls and trim.
Cornice repairs, cracks and alternatives
- Hairline cracks: flexible caulk and repainting usually fix movement cracks along the wall-to-cornice joint.
- Loose cornice: a section that has dropped needs re-fixing with adhesive and pins; see our how to patch plasterboard guide.
- Water stains: find and fix the leak first, then replace damaged plaster before you repaint.
- Feature finishes: modern textured or polished plaster looks can sit beside cornice; read our micro cement and concrete look finishes guide.
- Removing cornice: test for asbestos before removal in older homes, and book a licensed assessor if there is any doubt.
- Replacing with shadowline: changing styles needs wall repairs and is often best done during a full renovation.
Plaster cornice FAQs
How to install cornice?
Mark the lines, cut accurate mitres, apply cornice cement to the back edges, press the length into place and pin it while it sets. Fill and sand the joints, then prime and paint. Test old ceilings for asbestos first, and hire a licensed plasterer for large or high rooms.
What size cove cornice should I choose?
Smaller rooms with low ceilings suit 55 mm or 70 mm cove cornice, while living areas and high ceilings suit 75 mm or 90 mm. Hold a sample length in the room before you order, because the right size depends on the proportions of the space.
What are Gyprock cornice profiles?
Gyprock cornice profiles are the shapes and sizes in the Gyprock range, mostly plain coves in several sizes. Because ranges change, always check the current catalogue or ask your supplier to confirm exact dimensions before you buy.
Can I paint plaster cornice straight away?
Not before it is dry and sanded. Prime new cornice and joints with a suitable sealer, then paint with two coats as the label directs. Skipping primer leaves patchy sheen where the compound soaks up more paint than the plasterboard.
Is old cornice a health risk?
It can be. Older ceilings, textured coatings and fibre sheets may contain asbestos, which is dangerous when disturbed. Do not sand, drill or scrape suspect material. Get it tested, and use a licensed assessor and removalist if the result is positive.
How much does plaster cornice cost?
Cost depends on the profile, room size, corner count, ceiling height and finishing. Supply-only cornice is the cheapest option, while installed prices include labour and setting compound. Ask for an itemised quote so you can compare like for like.
Getting plaster cornice installed in Sydney
Plaster cornice looks best when the mitres are tight and the walls and ceiling are painted well. TQN Construct’s licensed painters and trade partners handle prep, finishing and painting across Sydney with itemised quotes and workmanship cover. Book a free quote.
