What does R value mean

What is R value & how is it measured

“R” value is calculated by thickness divided by thermal conductivity
Gardiner Australia’s PE30 was tested by the CSIRO & has a thermal conductivity of 0.033W /mtr2 K.
(“W” = watts per metre square measured in degrees Kelvin, & “K” =  Kelvin which is a laboratory measure of temperature)


                   What is Gardiner Australia’s foams  R value

Gardiner Australia 10mm thick foam, divided by 0.033W/ mtr2 K gives R 3

Gardiner Australia’s 8mm foam divided by 0.033W/ mtr2 K,  gives R 2.4

Gardiner Australia’s 5mm foam divided by 0.033W/ mtr2 K,  gives R 1.5


                 Does “aluminium”  foil on PE increase R value

In short, no.
The “foil” is metalized polyester not aluminium coated paper & this metalized polyester can easily flake with flexing.
The idea was to put a silver foil on porous products  to increase the water vapour resistance of the product. As the foil is so thin it will only marginally increase R value. It was often put on PE foam to match the look of pre-existing porous products for consumer reassurance rather than a functional improvement.
Gardiner Australia’s PE crosslinked foam has a fantastic water vapour resistance & so the foil may help sell the product to some, but it does not require it.


                    Is fluffy insulation a better R value product 

Fluffy insulation  R value ratings are one thing  but it must be remembered, if you compress it into a cavity reducing its thickness, the R value drops to the R value of the new thickness and importantly,  if it gets wet, its thermal conductivity also falls. A wall cavity therefore, where fluffy insulation is squashed into which then absorbs ambient water vapour, means it no longer will have the original dry, non-compressed, R value.