The present invention relates to a roofing shingle, which can surely prevent water such as rainwater from leaking through a roof. A roofing shingle has a rectangular plate (11) provided with first through fourth seam portions (11a-11d). The first and second seam portions (11a, 11b) are positioned in...http://www.google.es/patents/US6619006?utm_source=gb-gplus-sharePatente US6619006 - Roofing shingle
