[en] The user of technical products is confronted with the question of the durability of the construction units mostly only then if defects occur. It is assumed partly, that a tacitly assured warranty exists even if no arrangements were agreed upon. The problem of the warranty of the construction unit durability, however, has various aspects from the view of the users and of the producers. Only a consideration of all points of view corresponding to the individual construction unit leads to satisfactory solutions. (orig.) 891 HP 892 AG