floor 19 whereas the u sections 11 serve for stiffening and connecting the prefabricated elements 1 themselves together in the case of embodiment depicted in fig7 the u sections 9 are employed for the connection with a wall or respectively floor 19 which in this case is in the plane of the drawing here the above described designs of the u sections 9 are employed thus in the top part of fig7 u sections are indicated which have lugs 12 by means of which the u sections 9 may be connected with the wall or respectively ceiling or floor 19 for this purpose fastening means 17 such as screws bolts screw anchoring plugs and the like are provided on the lugs 12 alternatively it is possible for the fastening means 17 to be arranged on the base face 14 u sections 9 which are provided with recesses 16 rendering possible access to the base 14 even if there is a pre existing prefabricated element 1 in place if a suitable recess is provided in the surface element 3 of the prefabricated element 1 in addition to the fastening of the u sections 9 using screws screw anchoring plugs and the like it is also to possible employ other suitable connecting methods such as bonding the stiffening and connecting elements 11 and 11 a which are arranged between adjacent prefabricated elements 1 in accordance with the above description may if required be additionally secured using fastening element 10 on the prefabricated elements 1 here it is also possible to use more particularly screws.