A method of joining narrow waterproof sheets to obtain a waterproof sheet of wide width having a gently curved joint which is free from any acutely stepped portion. It comprises disposing a cure tape between the overlapping edge portions of the sheets to be joined, positioning a piece of cushiony material...http://www.google.com/patents/US4379114?utm_source=gb-gplus-sharePatent US4379114 - Method of joining waterproof sheets, and their joint structure
