Calder Lead Roofing Expansion Joint Plus Cover Flashing - 1.5m x 400mm Description The plus product has a metal cover over the rubber section so that the rubber is not visible from above. Sometimes the design of a roof means a traditional lead lined gutter is not practical because the necessary drip provision cannot be accommodated. The Calder gutter expansion joint overcomes this problem. Its two lead strips are connected by a high performance, double sided and vulcanized, EPDM synthetic rubber band. Each expansion joint has a 10 year guarantee.