On a traditional roof, the insulation serves to support the waterproofing and there is a need to place a barrier to the steam under the insulation material owing to the permeability of this solution to steam. The protection layer depends on accessibility to the rood. Expanded cork board are practically inert and wholly compatible with most of the materials deployed in civil construction, thereby accepting the application of the waterproofing system, avoiding the carrying out of screeds, namely on roofs with limited accessibility when restoring buildings.
Thermal delay – The thermal delay calculation is based on the thermal conductivity value of the insulating materials and the exterior temperature differences are deemed to be negligible. However, the temperatures of the exterior surfaces are subject to thermal amplitudes 24 hours a day. This temperature variation, typical of the Mediterranean countries, leads us to consider not only thermal conductivity, but also the thermal inertia of the materials, resulting in a delays in the propagation of heat flow from the exterior to the interior. This thermal delay will be greater, the larger the heat capacity and the lower the thermal diffusivity of the materials going to make up the roof. The economic thickness calculations of the thermal insulations should bear in mind not only the thermal conductivity value but also its thermal diffusivity.