Abstract: A seam structure for connecting two rubber sheets in edge-to-edge manner, wherein the connection surfaces (i.e. the adhering area) between the edge joints of the two rubber sheets are respectively enlarged without increasing the thickness of the rubber sheets. The seam structure includes a base edge joint having a L-shaped cross section provided at an end edge of the first rubber sheet and a covering edge joint having a L-shaped cross section provided at an end edge of the second rubber sheet. The base edge joint has a root portion and an end portion defining a base connection surface extended sidewardly from the root portion to the end portion. The covering edge joint has a root portion and an end portion defining a covering connecting surface extended sidewardly from the root portion to the end portion thereof Therefore, the covering connection surface is adapted to be sealingly attached on the base connection surface so as to overlappingly connect the covering edge joint with the base edge joint.

Abstract: A seam structure for connecting two foam sheets in edge-to-edge manner, wherein the connection surfaces (i.e. the adhering area) between the edge joints of the two foam sheet are respectively enlarged without increasing the thickness of the foam sheets, allows two foam sheets of a thinner width than is used with conventional seam structures to be connected with sufficient strength to overcome horizontal separating forces. The seam structure includes a base edge joint provided at an end edge of the first foam sheet and a covering edge joint provided at an end edge of the second foam sheet. The base edge joint has a root portion and an end portion defining a base connection surface extended sidewardly from the root portion to the end portion. The covering edge joint has a root portion and an end portion defining a covering connection surface extended sidewardly from the root portion to the end portion thereof.