Ceiling Insulation Installation Instructions

These instructions should be read in conjunction with local standards AS 3999 and all applicable local, state and federal building regulations. Before you start installing, please make sure you are familiar with our Health and Safety Message. Ensure that you use tools and equipment that are suitable for the intended application. This will include suitable safety equipment.Safety Switch Off

Do not start work until the site is safe!

Assess the ceiling condition and structure together with the method of installation you are to use based on the appropriate requirements established in the building code, site assessment and or plans provided. Installation must be completed to the requirements of relevant standard: AS3999:1992.


  • Sharp knife for trimming insulation
  • Ladder
  • Suitable clothing (see our Health and Safety message)
  • Tape measure
  • Non-conductive insulation stick for positioning insulation in hard to reach areas
  • Kneeling board to span ceiling framing


  • Determine the most suitable product for your project. Ceilings can be insulated using blanket or batts.
  • Where you have existing insulation that is level with the ceiling joists, you can install additional insulation over the top. It is recommended that this is installed at right angles to the existing insulation.
  • Insulation is available in varying widths and thicknesses to suit most framing spaces. Please check Knauf Insulation’s product guide for the most suitable product for your application.
  • To calculate the number of packs needed, determine the area (m²) to be insulated by multiplying the length by the width or wall height. The number of m² of insulation material is clearly marked on each pack. Divide the total area to be insulated by the m² in a pack to determine the number of packs required (don’t forget to round up to the nearest whole pack). Allowances should be made for areas that are unable to be insulated. Click here to easily calculate how many packs you will need.


  • Don’t take the insulation out of the packages until you’re in position and ready to install.
  • Before installation, gently agitate the insulation by ‘bouncing’ it on its side until it recovers to thickness stated on the label.Light covers
  • Do not block ceiling vents and take care around downlights and other sources of heat. – Consult the appliance manufacturer’s instructions for appropriate clearances. Additional guidance is provided in AS 3999.


  • Start installing the insulation at the far corners of the roof and work your way back towards the ceiling access.
  • When installing insulation between ceiling joists, ensure that you achieve a snug fit avoiding any gaps.
  • When installing insulation in truss roofs, ensure that insulation is firmly butted together to achieve a consistent layer of insulation without any gaps.
  • Where required, use a sharp knife to cut the insulation to fit. It is important that when you cut the insulation that you avoid coming into contact with any electrical services.
  • When installing insulation in a roof eave (i.e. where the roof joins the ceiling), make sure the insulation covers the top plate but is not in contact with the roof. It is important to maintain a 20mm gap between the roofing substrates and the insulation.

STEP 4Ceiling 1

  • Complete a final check of the installation ensuring all areas have been insulated and that you have an even and consistent layer of insulation.
  • Finish your project by removing all packaging from the ceiling and disposing of all rubbish and excess insulation responsibly.


  • Once you have worked your way back to the ceiling access, make sure you insulate the ceiling access panel before exiting the roof space.

For more installation advice watch our ceiling install video here and read our electrical safety information here before doing any work in the ceiling space.