Breathable Vent Card

Why use?
Breathable Vent Card

When insulating a roof, the objective is to cover the entire area, i.e, 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.

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 has the ability to “breath”. It allows moisture from the house to pass through the linked cells, into the 50mm space created by the vent card and ultimately removed through gaps in the roof tiles.

Breathable vent card benefits
The installation of the vent card serves several important functions;

  • It allows moist air from the house to pass through and out into the external environment.
  • It prevents any condensation that may form on the underside of the roof from dripping down into the attic space.
  • It prevents the foam from having any other negative effects on the roof tiles, battens or felt membrane.
  • It provides a firm base for the spray foam.

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Breatheable Vent Card - Uvalue
``Breathable`` 50mm air gap

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.

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