Breathable Vent Card System
The basic principle of open cell foam, is to insulate the entire surface of the roof area whilst ensuring that the timbers within the roof structure maintain their ability to breathe. This is achieved by installing the foam following the system as it was devised, and that is to install the breathable card membrane/ Vent card, and applying the appropriate depth of foam to ensure that an adequate level of thermal retention is achieved.
This card allows us to create the 50mm air gap required by building regulations. Open cell spray foam should be used in insulating a roof as opposed to closed cell due to the fact that the open cell insulation can "breath". Open cell insulation allows moisture from the house to pass through itself, into the 50mm gap created by the vent card and ultimately removed through the gaps in the roof tiles.
The system of using the vent card serves several important functions;
It allows for a controlled level of ventilation to the roof, necessary for the alleviation of moisture vapour from within the roof space and timbers.
It prevents the foam from pushing, pulling or having any other negative effects on the felt membrane.
It provides a firm stable base for the application of the open cell.
It completes the open cell system by allowing moisture vapour to pass through to the ventilation channel.
It is imperative that the vent card is fitted AND that the vent card is breathable, as there have been cards used previously that did maintain the ventilation channel, however they did NOT let the moisture vapour pass through them to reach it. This would be akin to spraying directly onto a non breathable bituminous felt, the moisture gets trapped between the foam and the felt and over time this moisture build up will cause a problem.
Irish building regulations stipulate that a 50mm air gap must be maintained between your insulation material and the roofing felt. We use CPI E- Zero 500 open cell spray foam insulation combined with the unique CPI breathable vent card system. E-Zero 500 is NSAI Agrément certified and is CE marked.
We use water blown spray form insulation as opposed to chemical blown spray foam, so when you property has be insulated your living environment is warmer and healthier than before we started.