Structural underlays are designed to provide micro ventilation to the underside of the zinc, drain away any moisture, and offer acoustic absorption properties. They are specifically designed for use under fully supported traditional metal roofing and cladding. The extreme elasticity of the monofilaments that make up the spacer mat allows excellent sound absorption, significantly decreasing rain drumming noise. This product is a structural underlay mat fabricated with synthetic monofilaments, that can be purchased loosely bonded to a breather membrane with adhesive strips.