What does R value mean
“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 valueIn 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.