Reflective foil insulation works by providing a radiant barrier between a hot surface, and the area on the other side – e.g. between the roof of a house and ceiling space underneath it.
Foil insulation depends on an air gap of 2- 3cm between itself and the roof, in order for it to be effective. A layer of dirt or dust on the foil will greatly reduce the effectiveness of reflective foil insulation. When installed correctly, reflective foil insulation will significantly reduce the amount of radiant heat transfer into the roof or attic space, which in turn will effect the overall temperature in the living space below.