Copper Roof Work Copper Roof Work Originally a Lead roof, then Asphalted Stripping back Asphalt to reveal original timber work. Original timber then covered with exterior Plywood. Exterior Plywood then covered with Bituminous Building Paper and Copper Sheeting fixed over the top. Copper Sheeting fixed to Dome using hidden Copper Cleats. All Copper Sheets joined together using either a Standing Seam Joint or a Double Cross Welt Joint. With no mechanical fixings through Copper Sheeting.