Permo Air is a low resistance air-open roof underlay, suitable for pitched roofs. It is the ideal solution where there is a high risk of condensation forming in the roofspace; particularly during the drying out period of a building. Permo Air roof membrane is BBA approved and NHBC accepted without the need for additional high-level ventilation, saving time and cost.
Suitable for Cold and Warm Roofs.
Wind zones 1-3 with battened headlap.All wind zones with taped headlap.
Should be installed in line with the details set out in the BBA approved certificate and the terms laid down in BS5533
An unsupported underlay should provide a drape between rafters sufficient enough to ensure that water will run away from the batten fixing nail penetrations allowing draining from the eaves gutter
Contact between the membrane and the roof covering should be avoided during installation
Should be laid with a maximum drape of 15mm