When insulating a roof, the objective is to cover the entire area, ie; every nook, cranny and gap whilst ensuring that the wooden timbers within the roof maintain their ability to breathe. This is achieved by installing a breathable card membrane or Vent Card between the rafters. Open cell insulation is then sprayed onto the membrane of the vent card to the appropriate depth ensuring that an adequate level of heat retention is achieved.
This card creates the 50mm air gap required by building regulations.
The installation of the vent card serves several important functions;
It is imperative that the vent card is fitted and that the vent card has the ability to breath. Some installers out there today have used cards that did maintain the 50mm ventilation channel but were not breathable and did NOT let the moisture vapour pass through them. In this case, moisture will build up causing wood rot, insect infiltration and encourages mold growth which, throughout the years, will shorten the life of your roof.