This paper addresses DW design problems, with the goal of improving the DW logical design process. Some of the existing work in transformation oriented methodologies for DW design construct the DW starting from an Entity-Relationship model of the source database, and arrive to a conceptual or high-level-logical dimensional model of the DW. We propose a mechanism for obtaining the DW logical schema through pre-defined transformations applied to the source logical schema, which can be used as a complement to the existing DW design methodologies. The transformations allow a refined logical design of the DW and provide a trace of the design and a mapping between the source and DW logical structures.