Single Ply Fully Adhered/Partially Bonded Built-Up Felt Systems. Tapered Roof MG is a high performance Polyisocyanurate with mineral coated glass facers suitable for use below single ply fully adhered roof membranes, single ply waterproofing systems and partially bonded built-up felt. An Environmental Product Declaration (EPD), certified by IGBC is available for this product. Please contact technical support for further details.