Over 50% of the work done by the designer on a day-to-day basis is routine design that consists of reusing past design solutions (Moore, 1993). Despite of this fact, there are no tools that rationally support reuse of such solutions. Case-based design (CBD) has been pointed out as a promising aid to help this situation. In order to be of practical use, however, a case-based design system has to be able to use the information that the designer creates during the design process. The design information that the designer creates is today mostly in the form of weakly structured information, e.g. text documents, calculation documents, and 2D-drawings. This paper proposes an approach that enables capturing and representation of weakly structured information for the purpose of case-based structural design. The representation proposed allows us to apply most of the objectoriented abstract principles also on weakly structured information. It is also shown how the conceptual framework, the dependency structure, and the design process can be captured, represented, and used in CBD. The approach is successfully implemented into a prototype for reuse of computerized design calculation documents.