Air-open underlay from Klober tops performance ratings

Variable performance of vapour permeable underlays ultimately prompted the NHBC and BSI to require supporting high level ventilation for all except those classified as air-open membranes.

Klober Permo® air offers exceptional breathability, with a water vapour transmission sd-Value of 2736 g/m2/day and a water vapour resistance confirmed independently as 0.03 MNs/g. Ideal for vapour dispersal during a building’s critical drying out period, Permo air is suitable for cold and warm roof installations. It has also been tested for wind uplift resistance by the BRE who found it to be suitable for use up to Zone 5 on the BS5534 wind speed map.