How To Installing Cornice – Video Series



USG Boral Cornice
USG Boral Cornice Adhesive
Plasterboard nail or screws


USG Boral Mitre Master, or:
Mitre Box
150mm broad knife, or:
USG Boral DIY broad knife 150mm
Measuring tape & pencil
Fine-tooth saw
Small tool
Sponge for clean-up
Claw hammer


PLEASE NOTE: Ceiling cornices come in many shapes and sizes, complimenting a range of architectural styles. Find out more.


  1. 1.To ensure accurate placement of your cornice, mark with a pencil or string line where the bottom of the cornice will be on your wall, i.e. for a 90mm SHEETROCK® cove cornice, this would be 90mm down from the ceiling.
  2. 2.Measure the length of cornice required for each wall. Mark the bottom edge of the cornice lengths to fit your wall measurements. It's helpful to write on the paper on the bottom edge of the cornice with a pencil, so you can clearly tell the top from the bottom.


We also recommend using offcuts to practice cutting mitres before actually cutting your cornice.

  1. 3. If you're using a Mitre Box, place the cornice in upside down - so that the bottom edge is uppermost in the box. Cut with a fine-tooth saw using push pressure only.
  2. 4.If you're using a USG Boral DIY Mitre Master, place it so the indentations rest on the edge of the cornice. Cut with a fine-tooth saw. The Mitre Master can be used for internal and external angles of 55mm, 75mm and 90mm cornice.


Download the USG Boral Plasterboard Installation Manual for comprehensive technical information and installation guidelines.

  1. 5. Most of your cornice angles are likely to be internal - for example the corners of rooms. But you may also need to create external angles for around a fireplace or a room divider. In this case, you need to reverse the way you cut your cornice.


  1. 1.Mix USG Boral Cornice Adhesive in a small container. Only mix an amount you can use within 45 minutes.
  2. 2.Using a 150mm broad knife, butter a 10mm bead of adhesive to the back edges of the cornice and to the mitre edges.
  3. 3.Press the cornice firmly into position, squeezing excess adhesive out from under the cornice.
  4. 4.Part-drive nails along the bottom edges of the cornice to provide temporary support. (For long lengths of cornice, we recommend doing this in both the wall and ceiling along its length).
  5. 5.Leave it for 20 minutes to allow adhesive to partially set then remove temporary nails and smooth excess adhesive using the small tool.
  6. 6.Clean off any excess adhesive with a wet sponge to leave a smooth surface. Using the small tool, apply a small amount of cornice adhesive to the mitres and clean to a smooth finish.

Your cornice is now ready for painting!


  1. Ensure any ladders, scaffolding, trestles or planks you use are adequate and safe
  2. Read cautionary notes on all product packaging
  3. Wear safety gloves when using sharp tools
  4. Wear a dusk mask and eye protection when sanding
  5. We recommend you consult with a licensed electrician and/or plumber about any electrical wiring and/or plumbing requirements, prior to installing plasterboard

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