8 x Cromar Vent 3 Pro Breathable Membrane 1m x 50m is appropriate whether draped unsupported over rafters or laid directly over insulation. Providing a permanent quality breather underlay, which will last the life of the roof construction, will allow the escape of water vapour from within the roof structure and protect against wind-driven rain, snow, and dust.
When tested in accordance with BS5534 2014 Annex A , Vent 3 Pro felt is suitable to be in the applications below and zones attached.
| 345 mm batten gauge | 245mm batten gauge | 345mm gauge taped laps | 345mm gauge integral tapes |
| Zones 1 ‐4 | All zones | All zones | All Zones |
