How should a roof in Sydney be insulated?

The most effective way to control the living space temperature is to place to place good insulation right on top of your ceiling. So, if you do not have ceiling insulation, this is the first step.

Then insulation directly under the roof is next. The pictures below best show how this is achieved:

How a roof should be insulated
Example of a typical insulation solution under a new colorbond metal roof

Step number 1 will to turn your home into a fridge. A fridge keeps its contents cool in the middle of a hot summers day. by having an insulated ‘skin’.
Step 2 just makes the temperature in the attic more bearable so that the ceiling insulation does not need to work as hard.
Combine the two and you will have the best combination.

If you have cathedral ceilings, then there is limited space to install ceiling insulation. In this case, the solution is to ‘super – insulate’ between the ceiling and the outer roof. Aircell insulation is an option here because it is thinner and has a higher R rating, but it comes at a price premium of about $3 per square metre. This type of insulation under the roof and a stuffing of ceiling batts at any available cavity is especially effective in cathedral ceilings and where there is no cavity to create an effective insulation layer.