Abstract: The screwed insert (1) has a shaft body (2) designed to receive a threaded fixing element and with an outer cutting thread (3) and a terminal flange (19), and ends in a pre-boring element (20). This pre-boring element includes one or more boring legs (21, 22) that extend parallel to each other and are unsupported at their ends, and of which the radially inner and outer adjacent surfaces form a continuation of the wall of the shaft body (2) and a longitudinally aligned cutting edge (23). Each of these cutting edges (23) terminates in an outer cutting tip (28,29). A centring tip (34) is provided at the free end of a radially inwardly directed continuation (35) of one of the boring legs (22) and is able to be pushed to one side when a long fixing element (1) is advanced.

Abstract: An insulating material plate (4) is fixed to the surface (6) of a structure (8) by a dowel (2) with a disk-like head (14), countersunk in a countersunk hole (24) of plate (4) and carrying on its outer surface an insulating material washer (10). Washer (10) prevents the thin plaster layer (22) from separating at the location of dowel head (14), due to the thermal expansions and differing thermal conduction between the dowel material and the mortar material. The insulating material washer (10), which is e.g. made from the same material as the insulating plate, also makes it possible to level the outer surface (20) of the insulating material plate by abrasion, prior to the application of the mortar layer, so that a smaller thickness of the latter can be used.