After working with it a bit i can see the value of insulating paper for external walls. The 3mm Wallrock Thermal Liner is what i generally use. Can anyone speak as to whether the Erfurt 'Graphite Plus' insulating lining paper (4mm) is any good in reality? It claims to be 20% more effective but i dont have any independent data on this. It's about 1/3 of the price. Or other brands (Red Label)? I have the below info on the Wallrock: " Wallrock Thermal Liner is applied to a solid wall dwelling with a U Value of 2.1 W/m2K the resulting U Value is improved (i.e. reduced) to 1.79 W/m2K. This represents a saving of 15% in the static heat loss. Its Thermal Resistance has been measured at 0.0821 m2K/W.” To view the full document, please click here." Thanks,