Proctor Roofshield is a unique, three - layer, nonwoven, spunbonded, polypropylene breather membrane with a patented melt - blown core. It is intended for use as a pitched roof underlay (breathable roofing felt) and is fixed beneath tiles and slates, Roofshield provides a secondary barrier to the ingress of rain, wind and snow. It has a low vapour resistance and is air - permeable; additionally, it eliminates the incidence of interstitial condensation in pitched roofs, the product provides the most cost - effective solution to controlling interstitial condensation in a pitched roof.