prevents moisture from entering buildingBreather Membranes (or Breathable Membranes) are the most common form of underlay used in pitched roofs. Breather membranes allow water vapour to escape from the building, therefore preventing condensation from forming mould, mildew or wet rot on timbers etc. At the same time Breather Membranes will not allow water droplets to pass through its uppermost side, providing a waterproof layer underneath the roof covering. email 13506299541(at)vip.163.com