EcoDri FR Underlay is a heavy-weight, fire-retardant, self-supporting synthetic roof underlay with excellent vapour permeability. It features a microporous, water-resistant film laminated to two layers of non-woven spun-bonded polypropylene. EcoDri FR is designed for use beneath roof claddings to assist with the weathertightness and moisture management of buildings.EcoDri FR is composed of 80% recycled materials and features a dark grey top and white bottom. The hues may vary depending on the recycled material content.