Permo® air is the most breathable air open low resistance underlay on the market. It is the ideal solution where there is a high risk of condensation forming in the roof space. It is a low resistance air-open roof underlay, suitable for pitched roofs. Permo Air roof membrane is BBA approved and NHBC accepted without the need for additional high-level ventilation, saving time and cost. Area of application Suitable for Cold and Warm Roofs. Wind zones 1-3 with battened headlap. All wind zones with taped headlap. Key Features Air and vapour permeable. BBA & NHBC approved for needing no additional high level ventilation, saving time and cost. Assists during the drying out period and helps with the ventilation on complex roofs. Strong 3 layer recyclable fleece. All products supplied by Klober are covered by its 10 year guarantee.