A sealing element for sealing joints and the intermediate space between an inner wall, an outer wall shell and a window frame includes (1) a first block-shaped sealing element section of a first flexible foam having a first indentation hardness and (2) a second web-shaped sealing element section which projects from an edge area of the first sealing element section, the second sealing element section including at least one sealing strip which is a second flexible foam having a second indentation hardness, the first indentation hardness being at least 1.5 times greater than the second indentation hardness.