How to DIY ceiling insulation in your home

Follow these simple DIY instructions to help reduce your heating and cooling bills and make a difference to your comfort. By installing ceiling insulation, it will keep your home cooler in summer or warmer in winter.

What you need:

  • Bradford Black ceiling insulation batts
  • Tape measure
  • Retractable utility knife and a tool (like a bread knife) for creating a straight edge
  • Step ladder if needed to access the roof space
  • Torch or lamp for lighting
  • Sturdy kneeling board to lay across beams
  • Broom handle or other long non-electrical conductive poker (not metal)
  • Gloves, dust mask and long sleeves

Measure the area you need to insulate

You can roughly measure the area in your ceiling or you can work out the m2 required from your house plans.

Measure the distance between your ceiling joists. Measure to the centre of the joists and remember, the distances may vary so make sure you measure them all. This will tell you what width of ceiling batts you will need:

  • If your joist centres are 450mm wide, purchase 430mm batts
  • If your joist centres are 600mm, wide purchase 580mm batts
Batts can be easily trimmed using your knife and straight edge to fit odd distances.

    Decide on your R-Value and 

    R-value is a measure of the insulation batt's resistance to heat flow, also known as thermal resistance. The higher the R-value the slower your home will heat up in summer and the more heat will be retained in winter, so you can enjoy a more even temperature all year round. 

    Calculate how many packs you need

    Look at the coverage per pack for the batt you’re going to buy. Divide the total ceiling area to be insulated by the coverage per pack. Round it up and you’ve got the number of packs you need to buy.

    Tip: It’s always a good idea to get an extra pack above the minimum required, in case you need to cut batts and you don't want to find yourself short halfway through the job!

      Preparation & Safety

      Keep yourself safe with the following steps:

      • Don’t install on a hot day – your roof space can reach temperatures of up to 70 degrees in summer. The best time to install ceiling insulation is early in the morning before the heat has built up. Take some water with you, it can be a thirsty job.
      • Turn off power at the fuse box before commencing installation, and place a warning tag on it so nobody mistakenly turns it back on while you’re working.

      Installing the insulation

      • Set up your light in the roof so you can see clearly.
      • Take your sealed packs into the roof. They will expand a lot and this saves you from dragging individual batts up a ladder. Open the packs with your utility knife, drawing it down the side of the pack.
      • Don’t stand on the ceiling plasterboard – only on the joists or use your kneeling board. Position your kneeling board over at least two joists for maximum stability.
      • Start from the outside of the roof and work your way back to the access point.
      • Push your batts out towards the eaves so the first batt is 50mm across the top plate (edge of the outside wall) but remember the 20mm gap between roof and batt. Use your poker to push them into limited access areas.
      • Fit the batts snugly between the ceiling joists onto the ceiling plaster, and butt them up against each so they’re firm but flat.
      • Fill in any gaps with offcuts or trim a piece off another batt.
      • When you are all done, have a shower to wash off any skin irritation.

      Handy tips:

      What else is in your roof that you need to be careful of?

      • If you have air-con ducting in your ceiling, just lay it on top of the insulation batts.
      • Batts can be laid over electrical wiring but should be cut around downlights. In Australia, a clearance of 50mm around the perimeter of the downlight fitting is required to help dissipate any heat.
      • Don’t block any ventilation openings, like ceiling or eave grilles. Getting that fresh air into your ceiling is a key part of keeping your home comfortable year-round.