Product Description IKO Pitched Roof Underlay is a lightweight high performance underlay for pitched tiled and slated roofs, ventilated in accordance with BS 5534: 2003. Installed in the same manner as conventional tile and slate underlays, IKO Pitched Roof Underlay prevents the ingress of wind-blown dust, rain and snow into the roof void. The lightweight fabric type construction makes it clean and easy to handle, and the option of a high coverage roll size allows rapid installation. IKO Pitched Roof Underlay is a three-layer construction, comprising two UV stabilised, high tensile polypropylene fabric layers fused together by a combination of heat and pressure, around an impervious polypropylene film. The membrane is dark grey in colour and printed on the topside with a special grid pattern, to assist cutting and reduce wastage.