Klober air-open underlay tops performance ratings

Variable performance of many vapour permeable underlays ultimately prompted the NHBC and BSI to require supporting high level ventilation for such products.

For roofs needing the highest standard of ventilation performance during a building’s critical drying out period to prevent condensation forming in the roofspace, Klober’s BBA and IAB-approved ‘air-open’ Permo® air offers not just an exceptional level of breathability, with a water vapour transmission sd-Value of 2736 g/m²/day, but a water vapour resistance which has been independently confirmed to be as low as 0.03 MNs/g. This has resulted in its specification for many complex roof designs as well as historic and commercial buildings.