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What R value should I use?
This page on choice says 1.5 for the walls and 1.5 to 3.0 for the ceiling : http://www.choice.com.au/reviews-and-tests/household/heating-and-cooling/home-heating/home-insulation-buying-guide/page/r-value-what-is-it.aspx
However when I follow the link I read 2.8 for the walls and 4.1 for the ceiling: http://www.yourhome.gov.au/passive-design/insulation
However it also says there "Total R-value". Including the drywall and the cladding then?