This 1.5m x 50m Breath Shield120 Membrane is suitable for use in Zones 1, 2 & 3 and is first class in its resistance against water penetration in both warm and cold roofs, due to its vapour permeable properties. It allows roofs to breathe without the need for traditional ventilation, and can be a full supported or unsupported underlay beneath tiled or slated pitched roofs.