R values are a measure of the ability of a product to resist the flow of heat. This measure allows the effectiveness of different insulation materials to be compared. The higher the R value number, the better insulation properties of the product. Because Insulmax fills all available space, we state the R value as – R 2.8 over 100mm. So, if your wall was 50mm thick the R value of the product would be R 1.4 and if it were 150mm thick the R value of the insulation would be R 4.2 For older homes, R values of the material are important but not as important as the realisation that the R value of the wall with no insulation is in the region R 0.2.