Typical homes will be built with 90mm cavities so you are limited to insulation that will fit this size. You can request larger frames from the builder but its not common and can cost a lot more. The standard wall R ratings are between R1.5 and R2.7 and in some cases there are separate ones at R4.0.
Another important factor is the thickness of the material used as this will limit the amount of insulation you can use.
|R6.0||260mm||> $20/m2||Typical Upgrade|
Small gaps in ceiling insulation can cause a lot of heat or cold air to pass through. A good option is to use a cross hatch installation which crisis crosses each other.
Its used for:
More details can be found on the Bradford Wall Wrap section
Bradford has some good information on the various options that are worth exploring in more detail.
This is essentially a foil that is attached to an insulation blanket. Its common for colorbond roofs.