Abstract: An insert element (8) for sealing cavities (6, 7) in vehicle body carriers (4) has sealing means constituted by a foamable material (11) which is secured in the cavities (6, 7) by securing means (9). The insert element (8) comprises a foamable material (11) and a support structure (10) which comprises a frame (13) and an inner part (14) for carrying the foamable material (11). The frame (13) has at least two lateral and not immediately oppositely arranged support faces (12), and carries securing means (9). With this arrangement, the foamable material can completely engulf the securing means (9) with foam during the foaming process and can flow into apertures of an intermediate metal sheet (5) foreseen for receiving the securing means (9). This ensures that these apertures are impermeably sealed against air and noise during the foaming process.