Base Sheet Koppers non-perforated base sheets may be specified as an alternate for the first applied ply in solid mop specifications. In such alternate specifications the base sheet shall be continuously imbedded in steep asphalt followed by the remaining plies applied in the coal tar pitch. See Application Considerations and Specifications - Base Sheet for further information. When specifying base sheet as an alternate for the first ply, use the designation BS as a subscript to the specification number. When base sheets are mechanically fastened in high wind areas, specify the use of discs to be used with the fasteners, 2" (51mm) dia. min. or as required with type of fastener. Refer to the FMRC Approval Guide for specific requirements.  Return to General Requirements and Considerations for the Designer